2023/11/26 更新

写真a

ナラ ヒロキ
奈良 洋希
所属
理工学術院 理工学術院総合研究所
職名
主任研究員(研究院准教授)
学位
博士(工学) ( 早稲田大学 )

学歴

  •  
    -
    2008年

    早稲田大学   理工学研究科   応用化学  

  •  
    -
    2005年

    早稲田大学   理工学研究科   応用化学  

  •  
    -
    2003年

    早稲田大学   理工学部   応用化学  

委員歴

  • 2015年04月
    -
    継続中

    電気化学会  関東支部幹事

  • 2021年04月
    -
     

    電気化学会  代議員

所属学協会

  •  
     
     

    国際電気化学会

  •  
     
     

    米国電気化学会

  •  
     
     

    電気化学会

  •  
     
     

    電池技術委員会

研究分野

  • エネルギー化学   リチウム二次電池,燃料電池,電気化学インピーダンス

研究キーワード

  • 応用電気化学

受賞

  • ナノテクノロジーフォーラム賞

    2021年09月   早稲田大学 ナノ・ライフ創新研究機構  

    受賞者: 奈良洋希

  • 国際研究集会出張助成

    2019年   小笠原科学技術振興財団   Sn–Ni alloy Anode Pre-doped in Vinylene Carbonate Containing Electrolyte for Lithium-ion Capacitor  

    受賞者: 奈良洋希

  • 科学技術研究助成

    2017年   スズキ財団   Li金属二次電池用Liデンドライト析出検知セパレータの析出検知過程の可視化  

    受賞者: 奈良洋希

  • アルミニウム研究助成事業

    2017年   日本アルミニウム協会   Li ⾦属⼆次電池におけるLi デンドライト析出検知Al セパレータの開発  

    受賞者: 奈良洋希

  • 研究費助成

    2011年   東京応化科学技術振興財団   リチウム二次電池用硫黄正極のブロックコポリマー修飾によるポリスルフィド溶出抑制とインピーダンス法によるその詳細解析  

    受賞者: 奈良洋希

  • ENEOS研究奨励賞

    2011年   JXエネルギー   リチウム二次電池用硫黄正極の修飾ブロックコポリマー中における支持塩,溶媒の影響評価  

    受賞者: 奈良洋希

  • Most Excellent Paper Award

    2011年   The 3rd International Workshop on Advanced Electrochemical Power Sources  

    受賞者: Hiroki Nara, Toshiyuki Momma, and Tetsuya Osaka

  • 国際研究集会出張助成

    2010年   小笠原科学技術振興財団   Feasibility of Diblock Copolymer Ion Gel Electrolyte Used BMPFSA as Plasticizer  

    受賞者: 奈良洋希

  • 若手研究者支援事業

    2010年   早稲田大学総合研究所   リチウム二次電池用硫黄正極のブロックコポリマー修飾有無による充放電特性に与える影響解明  

    受賞者: 奈良洋希

  • 水野賞

    2008年   早稲田大学   Development of Lithium Battery Materials Using Phase Separated Electrolytes  

    受賞者: 奈良洋希

  • 国際交流助成

    2007年   丸文研究交流財団   Cycle property of mesoporous Sn anode for lithium ion secondary batteries  

    受賞者: 奈良洋希

  • 国際交流助成

    2004年   電子回路基盤技術振興財団   Preparation of Gel Electrolyte Using Self-assembling Diblockpolymer for Lithium Secondary Battery  

    受賞者: 奈良洋希

▼全件表示

 

論文

  • Strategic design of Fe and N co-doped hierarchically porous carbon as superior ORR catalyst: from the perspective of nanoarchitectonics

    Minjun Kim, Konstantin L. Firestein, Joseph F. S. Fernando, Xingtao Xu, Hyunsoo Lim, Dmitri Golberg, Jongbeom Na, Jihyun Kim, Hiroki Nara, Jing Tang, Yusuke Yamauchi

    CHEMICAL SCIENCE   13 ( 36 ) 10836 - 10845  2022年09月  [査読有り]

    担当区分:責任著者

     概要を見る

    In this study, we present microporous carbon (MPC), hollow microporous carbon (HMC) and hierarchically porous carbon (HPC) to demonstrate the importance of strategical designing of nanoarchitectures in achieving advanced catalyst (or electrode) materials, especially in the context of oxygen reduction reaction (ORR). Based on the electrochemical impedance spectroscopy and ORR studies, we identify a marked structural effect depending on the porosity. Specifically, mesopores are found to have the most profound influence by significantly improving electrochemical wettability and accessibility. We also identify that macropore contributes to the rate capability of the porous carbons. The results of the rotating ring disk electrode (RRDE) method also demonstrate the advantages of strategically designed double-shelled nanoarchitecture of HPC to increase the overall electron transfer number (n) closer to four by offering a higher chance of the double two-electron pathways. Next, selective doping of highly active Fe-N-x sites on HPC is obtained by increasing the nitrogen content in HPC. As a result, the optimized Fe and N co-doped HPC demonstrate high ORR catalytic activity comparable to the commercial 20 wt% Pt/C in alkaline electrolyte. Our findings, therefore, strongly advocate the importance of a strategic design of advanced catalyst (or electrode) materials, especially in light of both structural and doping effects, from the perspective of nanoarchitectonics.

    DOI

    Scopus

    91
    被引用数
    (Scopus)
  • Systematic analysis of interfacial resistance between the cathode layer and the current collector in lithium-ion batteries by electrochemical impedance spectroscopy

    Hiroki Nara, Daikichi Mukoyama, Ryo Shimizu, Toshiyuki Momma, Tetsuya Osaka

    Journal of Power Sources   409   139 - 147  2018年09月  [査読有り]

    担当区分:筆頭著者, 責任著者

    DOI

    Scopus

    67
    被引用数
    (Scopus)
  • Impedance Analysis of LiNi1/3Mn1/3Co1/3O2 Cathodes with Different Secondary-particle Size Distribution in Lithium-ion Battery

    Hiroki Nara, Keisuke Morita, Daikichi Mukoyama, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   241   323 - 330  2017年07月  [査読有り]

    担当区分:筆頭著者, 責任著者

     概要を見る

    Mid to low frequency impedance for a cathode in a lithium ion battery (LIB), which is affected by lithiumion diffusion into active materials, was investigated. We had earlier suggested that charge-transfer and diffusion impedances are attributed to a particle size distribution for a commercially available LIB, and we designed an equivalent circuit in which two series circuits of charge-transfer resistance and Warburg impedance were connected in parallel. Here, to validate the design of the equivalent circuit, the secondary-particle size distribution of the LiNi1/3Mn1/3Co1/3O2 cathode in a lab-made LIB, in which the secondary-particles were controlled into wide and narrow distribution by sieving, was investigated by electrochemical impedance spectroscopy. The equivalent circuit was designed in which series circuits of charge-transfer resistance and Warburg impedance were connected in parallel. Dependency of impedance response on the number of parallels of the series circuits was evaluated for the cathodes using different secondary-particle size distributions of the active material. Additionally, the tendency of change in the charge-transfer resistance and the limiting capacitance was discussed from the standpoint of secondary-particle size distribution. The results confirm the effectiveness of the designed equivalent circuit which reflects the secondary-particle size distribution of cathode active materials. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    48
    被引用数
    (Scopus)
  • Impedance Analysis with Transmission Line Model for Reaction Distribution in a Pouch Type Lithium-Ion Battery by Using Micro Reference Electrode

    Hiroki Nara, Daikichi Mukoyama, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   163 ( 3 ) A434 - A441  2016年  [査読有り]

    担当区分:筆頭著者

     概要を見る

    Electrochemical impedance spectroscopy (EIS) using an equivalent circuit is a powerful tool in the diagnosis of lithium-ion batteries (LIBs). However, LIBs have been increasingly used in applications requiring power higher than that used for conventional LIBs for portable electric devices. Considering this demand for LIBs, the ionic resistances in the electrodes, which raise a reaction distribution under high-power operation, are important. This consequently means EIS analysis should include ionic resistances in the electrodes in equivalent circuits. Additionally, the impedance response of LIBs are too complicated to be analyzed in detail because the impedance response consists of overlapping elemental processes such as chemical reactions and ion migration. This paper therefore presents an analysis of impedance responses, which are independently obtained by a micro reference electrode, by using a transmission line model (TLM) that possesses the ability to count the ionic resistances in the electrodes. Similar to the conventional Randles equivalent circuit, the equivalent circuit with TLM could fit the impedance responses simulated by the equivalent circuit with measured responses. This paper discusses the potential of EIS using an equivalent circuit coupled with a TLM for diagnosis of LIBs in power applications. (C) The Author(s) 2015 Published by ECS. All rights reserved.

    DOI

    Scopus

    50
    被引用数
    (Scopus)
  • Impedance analysis of the effect of flooding in the cathode catalyst layer of the polymer electrolyte fuel cell

    Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   113   720 - 729  2013年12月  [査読有り]

     概要を見る

    A common understanding of polymer electrolyte fuel cells (PEFCs) is important to promote the development of PEFCs. This understanding is crucial because complicated phenomena such as chemical reactions, ion transport, and gas diffusion occur during the operation of PEFCs. Electrochemical impedance spectroscopy (EIS), which can separate reactions into elementary processes, is a powerful tool for the analysis of PEFCs without requiring disassembly of the cell. In this study, the effect of flooding in the cathode catalyst layer of PEFCs was analyzed by EIS using the transmission line model (TLM) to determine the distribution of catalytic reactions in the primary and secondary pores. The analysis was conducted by varying experimental conditions such as the relative humidity of the gases supplied into the anode and cathode, the flow rate, and the partial pressure of oxygen in the gas mixture supplied to the cathode channel. The EIS analysis suggests that the resistance to the catalytic reaction in the primary pores drastically increased with the current density. The results suggest that the flooding preferentially occurred in the primary pores, resulting in the reduction of active sites by generated water. The EIS method is a powerful tool for developing membrane electrode assemblies (MEAs) with effective porosity and tortuosity for gas diffusion and ionic transportation, and furthermore, it is a useful tool for judging the process of MEA preparation. (C) 2013 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    31
    被引用数
    (Scopus)
  • Structural analysis of highly-durable Si-O-C composite anode prepared by electrodeposition for lithium secondary batteries

    Hiroki Nara, Tokihiko Yokoshima, Mitsutoshi Otaki, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   110   403 - 410  2013年11月  [査読有り]

     概要を見る

    The structure of the highly durable silicon-based anode prepared by electrodeposition was investigated for volume change and chemical structure. With repeated charge-discharge cycles, the volume change resulting from the anode film thickness decreased, and, after 100 cycles, essentially no difference was observed between the charged and discharged states. The buffering effect of the volume change was considered to be achieved by the formation of Li2O, Li2CO3, and lithium silicates such as Li4SiO4, whose existence were supported by STEM, EELS, and XPS analyses. From the structural analyses, the main reactions related to the capacity of the silicon-based anode were considered to be the formation of LixSi and Li2Si2O5. LixSi and Li2Si2O5 can be delithiated into Si and SiO2, respectively. (C) 2013 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    31
    被引用数
    (Scopus)
  • Highly durable SiOC composite anode prepared by electrodeposition for lithium secondary batteries

    Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    ENERGY & ENVIRONMENTAL SCIENCE   5 ( 4 ) 6500 - 6505  2012年04月  [査読有り]

     概要を見る

    A highly durable SiOC composite anode was prepared for use in lithium secondary batteries. The SiOC composite was synthesized by electrodeposition of SiCl4. The composite anode delivered a discharge capacity of 1045 mA h per gram of Si at the 2000th cycle and 842 mA h per gram of Si even at the 7200th cycle. The reason for the excellent cyclability was investigated by methods including field emission scanning electron microscopy (FESEM), scanning transmission electron microscopy with an energy dispersive X-ray analyser (STEM-EDX), and X-ray photoelectron spectroscopy (XPS). The results revealed that the excellent cyclability was achieved by the homogeneous dispersion of SiOx and organic/inorganic compounds at the nanometre scale. The structural uniformity of the SiOC composite is believed to have suppressed the crack formation attributable to the stress resulting from the reaction of silicon with lithium during charge-discharge cycles.

    DOI

    Scopus

    93
    被引用数
    (Scopus)
  • Impedance Analysis Counting Reaction Distribution on Degradation of Cathode Catalyst Layer in PEFCs

    Hiroki Nara, Satoshi Tominaka, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   158 ( 9 ) B1184 - B1191  2011年  [査読有り]

     概要を見る

    A novel transmission line (TML) model is proposed for the impedance analysis, which is nondestructive measurement, on degraded cathode catalyst layers in polymer electrolyte fuel cells (PEFCs). The test PEFC consisted of 1.0 mg/cm(2) of Pt-Ru as an anode catalyst, 1.0 mg/cm(2) of Pt as a cathode catalyst, and Nafion 212 as an electrolyte. The model counts the distribution of the oxygen reduction reaction (ORR) at the inside and outside of agglomerates of the carbon supported catalysts. We demonstrated the importance of the distribution of the ORR for achieving excellent agreement between the calculated and experimental data. The change in parameters obtained by impedance analysis with the TML model was verified by destructive tests, such as transmission electron microscopy, field emission scanning electron microscopy, cyclic voltammetry, micro-Fourier transform infrared spectroscopy and nitrogen adsorption-desorption measurements. Variations of the parameters such as the charge transfer resistance, the double layer capacitance, and the ionic resistance inside and outside the agglomerates of the carbon supported catalysts could be explained by multiple considerations of these destructive test results. Impedance analysis with the TML model offers the possibility understanding the state of degraded cathode catalyst layers in membrane electrode assemblies without the need for disassembling PEFCs. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3610988] All rights reserved.

    DOI

    Scopus

    32
    被引用数
    (Scopus)
  • Feasibility of an interpenetrated polymer network system made of di-block copolymer composed of polyethylene oxide and polystyrene as the gel electrolyte for lithium secondary batteries

    Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHEMISTRY   76 ( 4 ) 276 - 281  2008年04月  [査読有り]

    担当区分:筆頭著者

     概要を見る

    The feasibility of a di-block copolymer, composed of a polyethylene oxide (PEO) chain and a polystyrene (PS) chain covalently bonded, as the gel electrolyte for lithium secondary batteries was investigated. The PEO-PS di-block copolymer gel electrolyte showed a high ionic conductivity of similar to 1 mS/cm at room temperature. Moreover, it retained good mechanical strength within a co-continuous phase separated structure, and it suppressed the dendritic deposition of Li. Indications were that the interface between the electrolyte and the Li metal was chemically stable, as a result of the PEO phase fixed to PS by covalent bonding. In addition, it was indicated that the Li/PEOPS di-block copolymer gel electrolyte/LiFePO4 cell had a high charge-discharge efficiency of similar to 99% during 30 cycles, while maintaining a discharge capacity of 124 mAh/g.

    DOI

    Scopus

    9
    被引用数
    (Scopus)
  • Publisher Correction: Mesoporous multimetallic nanospheres with exposed highly entropic alloy sites (Nature Communications, (2023), 14, 1, (4182), 10.1038/s41467-023-39157-2)

    Yunqing Kang, Ovidiu Cretu, Jun Kikkawa, Koji Kimoto, Hiroki Nara, Asep Sugih Nugraha, Hiroki Kawamoto, Miharu Eguchi, Ting Liao, Ziqi Sun, Toru Asahi, Yusuke Yamauchi

    Nature Communications   14 ( 1 )  2023年12月

     概要を見る

    Correction to: Nature Communications, published online 13 July 2023 The original version of the Supplementary Information associated with this Article included incorrect Supplementary Datasets. Dataset 1 reported an editorial policy checklist; Dataset 3 reported a general description of Supplementary Figures and Tables contained in the Supplementary Information PDF file; Dataset 4 contained editorial instructions to the authors for the preparation of the final version of the article. Datasets 1, 3, and 4 have been removed in the corrected version of the Article. In addition, the Reporting Summary and the Source Data file were originally published with the wrong titles of Dataset 2 and Dataset 5. The HTML version of the article has been corrected.

    DOI PubMed

    Scopus

  • Mesoporous multimetallic nanospheres with exposed highly entropic alloy sites

    Yunqing Kang, Ovidiu Cretu, Jun Kikkawa, Koji Kimoto, Hiroki Nara, Asep Sugih Nugraha, Hiroki Kawamoto, Miharu Eguchi, Ting Liao, Ziqi Sun, Toru Asahi, Yusuke Yamauchi

    Nature Communications   14 ( 1 )  2023年07月

     概要を見る

    Abstract

    Multimetallic alloys (MMAs) with various compositions enrich the materials library with increasing diversity and have received much attention in catalysis applications. However, precisely shaping MMAs in mesoporous nanostructures and mapping the distributions of multiple elements remain big challenge due to the different reduction kinetics of various metal precursors and the complexity of crystal growth. Here we design a one-pot wet-chemical reduction approach to synthesize core–shell motif PtPdRhRuCu mesoporous nanospheres (PtPdRhRuCu MMNs) using a diblock copolymer as the soft template. The PtPdRhRuCu MMNs feature adjustable compositions and exposed porous structures rich in highly entropic alloy sites. The formation processes of the mesoporous structures and the reduction and growth kinetics of different metal precursors of PtPdRhRuCu MMNs are revealed. The PtPdRhRuCu MMNs exhibit robust electrocatalytic hydrogen evolution reaction (HER) activities and low overpotentials of 10, 13, and 28 mV at a current density of 10 mA cm−2 in alkaline (1.0 M KOH), acidic (0.5 M H2SO4), and neutral (1.0 M phosphate buffer solution (PBS)) electrolytes, respectively. The accelerated kinetics of the HER in PtPdRhRuCu MMNs are derived from multiple compositions with synergistic interactions among various metal sites and mesoporous structures with excellent mass/electron transportation characteristics.

    DOI PubMed

    Scopus

    15
    被引用数
    (Scopus)
  • Tunable thiophene-based conjugated microporous polymers for the disposal of toxic hexavalent chromium

    Mohammed G. Kotp, Nagy L. Torad, Hiroki Nara, Watcharop Chaikittisilp, Jungmok You, Yusuke Yamauchi, Ahmed F.M. EL-Mahdy, Shiao Wei Kuo

    Journal of Materials Chemistry A   11 ( 27 ) 15022 - 15032  2023年05月

     概要を見る

    Herein we report the rational syntheses of three conjugated microporous polymers (CMPs) through one-pot polycondensation coupling of a boronated triphenylpyridine (TPP-3Bor) with 4,7-bis(5-bromothien-2-yl)benzo[c][1,2,5]thiadiazole (ThZ-2Br), 2,5-dibromothiophene (Th-2Br), and 1,4-dibromobenzene (Bz-2Br), yielding the TPP-ThZ, TPP-Th, and TPP-Bz CMPs, respectively, featuring different thiophene contents, topologies, and molecular structures. Various characterization techniques are used to investigate the structural properties of these TPP-based CMPs, revealing their spherical morphologies, tunable pore volumes, and high thermal and chemical stabilities. We test the TPP-based CMPs for their use in the dynamic adsorptive reduction of toxic Cr(vi) ions. Among them, the TPP-ThZ CMP possesses the highest adsorption capacity for Cr(vi) (209 mg g−1); this performance is also higher than those of other recently reported adsorbents. Furthermore, our TPP-based CMPs exhibit good reusability for the reduction and adsorption of Cr(vi) ions. Accordingly, these novel thiophene-based CMPs not only function as dynamic materials for the reduction-adsorption of Cr(vi) but also reveal the potential of thiophene linkers in the future design of such Cr(vi) adsorbents.

    DOI

    Scopus

  • Ni-Fe nanoframes via a unique structural formation induced by sonochemical etching

    Azhar Alowasheeir, Hiroki Nara, Miharu Eguchi, Yusuke Yamauchi

    Chemical Communications   92  2022年10月

     概要を見る

    A uniform nanoframe structure derived from a Prussian blue analogue (PBA) with an internal cavity is successfully synthesized by sonochemical etching. The uniquely structured PBA nanoframes possess a three-dimensional open structure and high surface area, resulting in enhanced electrochemical properties for the oxygen evolution reaction as a model reaction.

    DOI PubMed

    Scopus

  • Two-Dimensional Metal–Organic Framework Superstructures from Ice-Templated Self-Assembly

    Yujie Song, Xiaokai Song, Xiaoke Wang, Jingzheng Bai, Fang Cheng, Chao Lin, Xin Wang, Hui Zhang, Jianhua Sun, Tiejun Zhao, Hiroki Nara, Yoshiyuki Sugahara, Xiaopeng Li, Yusuke Yamauchi

    Journal of the American Chemical Society   144 ( 38 ) 17457 - 17467  2022年09月

     概要を見る

    Here, we report the synthesis of two-dimensional (2D) layered metal-organic framework (MOF) nanoparticle (NP) superstructures via an ice-templating strategy. MOF NP monolayers and bilayers can be obtained by regulating the concentration of colloidal MOF NPs without any external fields during self-assembly. Adjacent polyhedral MOF NPs are packed and aligned through crystalline facets, resulting in the formation of a quasi-ordered array superstructure. The morphology of the MOF layers is well preserved when subjected to pyrolysis, and the obtained carbon NPs have hollow interiors driven by the outward contraction of MOF precursors during pyrolysis. With the advantages of large surface areas, hierarchical porosity, high exposure of active sites, and fast electron transport of the 2D layered structure, the mono- and bilayered carbon NP superstructures show better oxygen reduction activity than isolated carbon particles in alkaline media. Our work demonstrates that ice-templating is a powerful strategy to fabricate superstructures of various MOFs and their derivatives.

    DOI PubMed

    Scopus

    28
    被引用数
    (Scopus)
  • Soft Template-Based Synthesis of Mesoporous Phosphorus- and Boron-Codoped NiFe-Based Alloys for Efficient Oxygen Evolution Reaction

    Yunqing Kang, Yanna Guo, Jingjing Zhao, Bo Jiang, Jingru Guo, Yi Tang, Hexing Li, Victor Malgras, Mohammed A. Amin, Hiroki Nara, Yoshiyuki Sugahara, Yusuke Yamauchi, Toru Asahi

    SMALL   18 ( 33 )  2022年08月  [査読有り]

     概要を見る

    Controlling the morphology, composition, and crystalline phase of mesoporous nonnoble metal catalysts is essential for improving their performance. Herein, well-defined P- and B-codoped NiFe alloy mesoporous nanospheres (NiFeB-P MNs) with an adjustable Ni/Fe ratio and large mesopores (11 nm) are synthesized via soft-template-based chemical reduction and a subsequent phosphine-vapor-based phosphidation process. Earth-abundant NiFe-based materials are considered promising electrocatalysts for the oxygen evolution reaction (OER) because of their low cost and high intrinsic catalytic activity. The resulting NiFeB-P MNs exhibit a low OER overpotential of 252 mV at 10 mA cm(-2), which is significantly smaller than that of B-doped NiFe MNs (274 mV) and commercial RuO2 (269 mV) in alkaline electrolytes. Thus, this work highlights the practicality of designing mesoporous nonnoble metal structures and the importance of incorporating P in metallic-B-based alloys to modify their electronic structure for enhancing their intrinsic activity.

    DOI PubMed

    Scopus

    28
    被引用数
    (Scopus)
  • Identification of Soluble Degradation Products in Lithium-Sulfur and Lithium-Metal Sulfide Batteries

    Fabian Horsthemke, Christoph Peschel, Kristina Kosters, Sascha Nowak, Kentaro Kuratani, Tomonari Takeuchi, Hitoshi Mikuriya, Florian Schmidt, Hikari Sakaebe, Stefan Kaskel, Tetsuya Osaka, Martin Winter, Hiroki Nara, Simon Wiemers-Meyer

    SEPARATIONS   9 ( 3 )  2022年03月  [査読有り]

    担当区分:責任著者

     概要を見る

    Most commercially available lithium ion battery systems and some of their possible successors, such as lithium (metal)-sulfur batteries, rely on liquid organic electrolytes. Since the electrolyte is in contact with both the negative and the positive electrode, its electrochemical stability window is of high interest. Monitoring the electrolyte decomposition occurring at these electrodes is key to understand the influence of chemical and electrochemical reactions on cell performance and to evaluate aging mechanisms. In the context of lithium-sulfur batteries, information about the analysis of soluble species in the electrolytes-besides the well-known lithium polysulfides-is scarcely available. Here, the irreversible decomposition reactions of typically ether-based electrolytes will be addressed. Gas chromatography in combination with mass spectrometric detection is able to deliver information about volatile organic compounds. Furthermore, it is already used to investigate similar samples, such as electrolytes from other battery types, including lithium ion batteries. The method transfer from these reports and from model experiments with non-target analyses are promising tools to generate knowledge about the system and to build up suitable strategies for lithium-sulfur cell analyses. In the presented work, the aim is to identify aging products emerging in electrolytes regained from cells with sulfur-based cathodes. Higher-molecular polymerization products of ether-based electrolytes used in lithium-sulfur batteries are identified. Furthermore, the reactivity of the lithium polysulfides with carbonate-based solvents is investigated in a worst-case scenario and carbonate sulfur cross-compounds identified for target analyses. None of the target molecules are found in carbonate-based electrolytes regained from operative lithium-titanium sulfide cells, thus hinting at a new aging mechanism in these systems.

    DOI

    Scopus

  • Efficient lithium-ion storage using a heterostructured porous carbon framework and its in situ transmission electron microscopy study

    Minjun Kim, Joseph F. S. Fernando, Jie Wang, Ashok Kumar Nanjundan, Jongbeom Na, Md. Shahriar A. Hossain, Hiroki Nara, Darren Martin, Yoshiyuki Sugahara, Dmitri Golberg, Yusuke Yamauchi

    Chemical Communications   58 ( 6 ) 863 - 866  2022年  [査読有り]

     概要を見る

    A heterostructured porous carbon framework (PCF) composed of reduced graphene oxide (rGO) nanosheets and metal organic framework (MOF)-derived microporous carbon is prepared to investigate its potential use in a lithium-ion battery. As an anode material, the PCF exhibits efficient lithium-ion storage performance with a high reversible specific capacity (771 mA h g(-1) at 50 mA g(-1)), an excellent rate capability (448 mA h g(-1) at 1000 mA g(-1)), and a long lifespan (75% retention after 400 cycles). The in situ transmission electron microscopy (TEM) study demonstrates that its unique three-dimensional (3D) heterostructure can largely tolerate the volume expansion. We envisage that this work may offer a deeper understanding of the importance of tailored design of anode materials for future lithium-ion batteries.

    DOI PubMed

  • Hollow carbon architectures with mesoporous shells via self-sacrificial templating strategy using metal-organic frameworks

    Tao Li, Bing Ding, Victor Malgras, Jongbeom Na, Zongyi Qin, Xiangjun Lu, Yoshio Bando, Hiroki Nara, Zeid A. Alothman, Jie Wang, Yusuke Yamauchi

    CHEMICAL ENGINEERING JOURNAL   420  2021年09月  [査読有り]

     概要を見る

    The rational design and fabrication of ordered mesoporous materials with highly exposed surface area are of great significance to address the fundamental challenges in electrochemistry-related applications by providing more active sites and fast ion/gas diffusion channel. In this work, a self-template method is reported to prepare hollow-structured mesoporous carbon (HOMC) nanoplates by depositing resol-F127 micelles onto the surface of metal-organic-framework (MOF) nanoplates, followed by hydrothermal reaction and carbonization. The parameters influencing the morphology and microstructure of the HOMC materials, i.e., the MOF-to-resol-F127 ratio and the concentration of resol-F127 micelles, are systematically investigated. Fe-doped HOMC (Fe/ HOMC) is obtained after carbonization, as a result from adding FeCl3 during the hydrothermal reaction. Benefiting from morphological aspects, such as the nanoplate shape, the hollow structure, and mesoporous walls, the Fe/HOMC exhibits higher electrocatalytic activity and efficiency than the commercial Pt/C during oxygen reduction reaction (ORR). In addition, when compared to traditional Pt/C benchmark, the Fe/HOMC shows a superior durability and tolerance to methanol poisoning while operating for ORR. The assembled Zn-air battery possesses high power densities with excellent cycling stability. The strategy proposed here can provide a new avenue for the design of ordered mesoporous materials with hollow structure for a wide variety of applications.

    DOI

    Scopus

    16
    被引用数
    (Scopus)
  • Polypyrrole Modification of High Sulfur-Loaded Three-Dimensional Aluminum Foam Cathode in Lithium–Sulfur Batteries for High-Rate Capability

    Natsuki Nakamura, Tokihiko Yokoshima, Hiroki Nara, Hitoshi Mikuriya, Ayahito Shiosaki, Seongki Ahn, Toshiyuki Momma, Tetsuya Osaka

    Journal of The Electrochemical Society   168 ( 4 ) 040517 - 040517  2021年04月  [査読有り]

     概要を見る

    A low-resistance polypyrrole (PPy) film that can achieve high rates (rates of >1C) while suppressing polysulfide dissolution is developed in this study. To achieve high-rate characteristic in a sulfur cathode with high sulfur loading, a three-dimensional (3D) aluminum foam current collector is used and the Li+ concentration of the PPy film is enhanced by a glyme-Li equimolar complex as the polymerization electrolyte. A PPy-sulfur/ketjenblack (S/KB) 3D aluminum foam laminated cell with a sulfur loading of 5 mg cm(-2) is prepared. Consequently, a high discharge capacity of 794 mAh g(-1)-sulfur at 3.0C is achieved using 1 M lithium bis-(trifluoromethylsulfonyl)imide (LiTFSI) with dimethoxyethane (DME) and 1,3-dioxolane (DOL), (DME/DOL = 1/1 vol.) as the electrolyte and Li foil as the anode. In the cycling test, PPy-S/KB 3D Al foam cathode achieved a significant improvement in discharge capacity retention compared to bare S/KB 3D Al foam cathode without PPy coating. Moreover, almost no polysulfide dissolution is confirmed from the ultraviolet-visible spectrum of the electrolyte after the cycle evaluation. Here, we prepare a 3D structure S/KB cathode that can support high rates while suppressing sulfur dissolution by PPy coating, and reveal its potential for lithium-sulfur battery application.

    DOI

    Scopus

    7
    被引用数
    (Scopus)
  • Single Atom-Based Nanoarchitectured Electrodes for High-Performance Lithium-Sulfur Batteries

    Jie Wang, Bing Ding, Xiangjun Lu, Hiroki Nara, Yoshiyuki Sugahara, Yusuke Yamauchi

    ADVANCED MATERIALS INTERFACES   8 ( 8 )  2021年04月  [査読有り]

     概要を見る

    Lithium-sulfur (Li-S) batteries have attracted particular interest as promising next-generation energy storage devices because of their high theoretical energy density and low cost. The real performance of Li-S batteries is, however, far from achieving the expected values, even when using a porous, highly conductive host of sulfurs to improve their electric conductivity and accommodate their volume changes. The performance restrictions are mainly attributable to the slow reaction kinetics of converting lithium polysulfides species to lithium sulfide and elemental sulfur during the charging and discharging processes, respectively. Recent studies show that single-atom catalysts (SACs) with superior catalytic activity offer an effective strategy for solving this tough issue. The recent advances in utilizing SACs for Li-S batteries, which involve catalyst preparation, battery performance, and mechanistic insights, are summarized here. Modification of the cathodes and separators with SACs helps to absorb polysulfide and promote their conversion kinetics, thus suppressing the notorious "shuttle effect." In addition, the introduction of SACs into Li-S batteries promotes the efficiency of Li stripping/plating and prevents the growth of Li dendrites. Overall, the boost effects of SAC on Li-S batteries performance are noticeable and deserving of more research attention to develop better Li-S batteries.

    DOI

    Scopus

    23
    被引用数
    (Scopus)
  • High-rate and high sulfur-loaded lithium-sulfur batteries with a polypyrrole-coated sulfur cathode on a 3D aluminum foam current collector

    Natsuki Nakamura, Tokihiko Yokoshima, Hiroki Nara, Hitoshi Mikuriya, Ayahito Shiosaki, Seongki Ahn, Toshiyuki Momma, Tetsuya Osaka

    Materials Letters   285   129115 - 129115  2021年02月  [査読有り]

     概要を見る

    In this study, the high-rate performance of high sulfur-loaded cathodes have been demonstrated using a novel battery that comprises of a 3 dimensional aluminum foam (current collector), sulfur (active material), acetylene black (conductive additive), and polypyrrole (PPy) coating. Consequently, a stacked laminated cell was prepared, which comprised of two 70 x 70 mm(2) PPy-sulfur/ketjen black sheets (sulfur loading = 4.3 mg/cm(2)), 1 M lithium bis-(trifluoromethylsulfonyl)imide (LiTFSI) with dimethoxyethane (DME) and 1,3-dioxolane (DOL), (DME/DOL = 1/1 vol%), and three Li foils as the cathodes, electrolyte, and anodes, respectively. The 1 M LiTFSI DME/DOL electrolyte, which is suitable for high rate, is applicable because the PPy coating suppresses dissolution of polysulfide into the electrolyte. The discharge capacities were 462 mAh (1075 mAh/g sulfur) at 0.4C (267 mA) and 251 mAh (583 mAh/g-sulfur) at 3.8C (2670 mA). An enhanced conductive path was formed in the cathode by the 3D Al foam and AB, which considerably improved the high-rate performance. This demonstration is particularly significant from the viewpoint of commercializing the high-power output and high-energy-density Li-S batteries for industrial applications such as small mobile device and drone power source. (c) 2020 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    9
    被引用数
    (Scopus)
  • Electrochemical Activity of Nitrogen-Containing Groups in Organic Electrode Materials and Related Improvement Strategies

    Qianchuan Yu, Zhihuan Xue, Meichen Li, Peimeng Qiu, Changgang Li, Shengping Wang, Jingxian Yu, Hiroki Nara, Jongbeom Na, Yusuke Yamauchi

    ADVANCED ENERGY MATERIALS   11 ( 7 )  2021年02月  [査読有り]

     概要を見る

    In recent years, due to their structural diversity, adjustability, versatility, and excellent electrochemical properties, organic compounds with nitrogen-containing groups (OCNs) have become some of the most promising organic electrode materials. The nitrogen-containing groups acting as electrochemical active sites include carbon-nitrogen groups, nitrogen-nitrogen groups, nitrogen-oxygen groups in OCNs, and nitrogen-containing groups in covalent organic frameworks. The molecular structure regulation of OCNs with nitrogen-containing groups acting as electrochemical active centers can suppress dissolution in electrolytes, increase electronic conductivity, and improve the kinetics of redox reactions. The kinetics behavior and electrochemical characteristics of OCN electrode materials in alkali metal rechargeable batteries with organic electrolytes are reviewed, and the related relationships between the structure and electrochemical properties of OCNs are the core of this review. Herein, the electrochemical reaction mechanisms and the strategies to improve the electrochemical activity of nitrogen-containing groups in OCNs are clarified, and the conjugate molecular structure of OCNs is shown to be an important direction for improvement. These results will have implications for research on electrode materials and provide more choices for rechargeable batteries. Moreover, this work will guide the study of more efficient OCNs that can be used as electrode materials.

    DOI

    Scopus

    43
    被引用数
    (Scopus)
  • Scale-up Efforts

    Tetsuya Osaka, Tokihiko Yokoshima, Hiroki Nara, Hitoshi Mikuriya, Toshiyuki Momma

    Next Generation Batteries: Realization of High Energy Density Rechargeable Batteries     415 - 422  2021年01月

     概要を見る

    Both the high sulfur loading cathode and less electrolyte are the most important parameters to realize lithium-sulfur batteries with high energy density. A high sulfur loading cathode was achieved by using 3D structured aluminum foam to act as a support structure and current collector. Moreover, the energy density close to 200 Wh kg-1 was successfully obtained by decreasing the electrolyte in the pouch cell. 5 Ah cell was developed by using the six sheets of the cathode in the cell. Recently, a multi-layer pouch-type cell with a high capacity of 5 Ah and a high energy density of 300 Wh kg-1 was successfully developed with technically reoptimized preparation conditions. These results indicate the possibility of the development of a lithium-sulfur battery with discharge capacity and high energy density for commercial use.

    DOI

    Scopus

  • AlCl3-graphite intercalation compounds as negative electrode materials for lithium-ion capacitors

    Yamato Haniu, Hiroki Nara, Seongki Ahn, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    Journal of Materials Chemistry A   9 ( 48 ) 27459 - 27467  2021年  [査読有り]

    担当区分:責任著者

     概要を見る

    Lithium-ion capacitors (LICs) are energy storage devices that bridge the gap between electric double-layer capacitors and lithium-ion batteries (LIBs). A typical LIC cell is composed of a capacitor-type positive electrode and a battery-type negative electrode. The most common negative electrode material, graphite, suffers from low rate capability and cyclability due to the sluggish kinetics of the Li+ intercalation/de-intercalation process. In this work, metal chloride-pillared graphite, which has recently attracted attention as high-rate LIB anodes, is applied as the negative electrode for LICs for the first time to overcome this drawback. It is shown that AlCl3-graphite intercalation compounds (AlCl3-GICs) with a wide interlayer spacing benefit faster Li+ diffusion. The low molecular weight and conversion reaction of the AlCl3 pillar further enhance the specific capacity per mass. An optimized LIC cell composed of an AlCl3-GIC negative electrode and activated carbon as the positive electrode exhibited higher energy and power densities compared to LICs using graphite as the negative electrode, and displayed stable cycling performance with 85% capacity retention after 10 000 charge/discharge cycles. The AlCl3-GICs synthesized in this work displayed improved electrochemical performances and have the potential to replace the graphite electrode in conventional LICs.

    DOI

  • Effect of fluoroethylene carbonate and vinylene carbonate additives on full-cell optimization of Li-ion capacitors

    Seongki Ahn, Minori Fukushima, Hiroki Nara, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    ELECTROCHEMISTRY COMMUNICATIONS   122  2021年01月  [査読有り]

     概要を見る

    Lithium-ion capacitors (LICs) operate by two mechanisms, namely a double-layer mechanism based on a capacitor-like positive electrode and the intercalation mechanism of a battery-like negative electrode. Hence, well-designed reaction kinetics between the positive electrode and negative electrode are essential for optimizing LIC full-cell configurations. In this study, we investigated the influences of fluoroethylene carbonate (FEC) or vinylene carbonate (VC) as electrolyte additives on full-cell performance of LICs. We confirmed that the internal resistance of graphite increased with the use of FEC, which degraded the cyclability of the LIC full-cell. Conversely, LICs consisting of the VC additive had good cyclability over 4000 cycles owing to the solid electrolyte interphase (SEI) containing polymeric species. This detailed investigation into the function of SEI compounds derived from VC additives and their effect on cyclability will provide new insights into optimization of LIC full-cell configurations with appropriate electrolyte additives.

    DOI

    Scopus

    7
    被引用数
    (Scopus)
  • Tunable Concave Surface Features of Mesoporous Palladium Nanocrystals Prepared from Supramolecular Micellar Templates

    Muhammad Iqbal, Yena Kim, Adhitya Gandaryus Saputro, Ganes Shukri, Brian Yuliarto, Hyunsoo Lim, Hiroki Nara, Asma A. Alothman, Jongbeom Na, Yoshio Bando, Yusuke Yamauchi

    ACS APPLIED MATERIALS & INTERFACES   12 ( 46 ) 51357 - 51365  2020年11月  [査読有り]

     概要を見る

    Concave metallic nanocrystals with a high density of low-coordinated atoms on the surface are essential for the realization of unique catalytic properties. Herein, mesoporous palladium nanocrystals (MPNs) that possess various degrees of curvature are successfully synthesized following an approach that relies on a facile polymeric micelle assembly approach. The asprepared MPNs exhibit larger surface areas compared to conventional Pd nanocrystals and their nonporous counterparts. The MPNs display enhanced electrocatalytic activity for ethanol oxidation when compared to state-of-the-art commercial palladium black and conventional palladium nanocubes used as catalysts. Interestingly, as the degree of curvature increases, the surface-area-normalized activity also increases, demonstrating that the curvature of MPNs and the presence of high-index facets are crucial considerations for the design of electrocatalysts.

    DOI PubMed

    Scopus

    11
    被引用数
    (Scopus)
  • Effect of Mass Balancing on Cell Performance and Electrochemical Investigation of Sn–Ni Alloy as Anode for Li-Ion Capacitors

    Seongki Ahn, Yusuke Nakamura, Hiroki Nara, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    Journal of The Electrochemical Society   167 ( 13 ) 130512 - 130512  2020年09月  [査読有り]

     概要を見る

    Lithium-ion capacitors (LICs) have been attracting research interest over the past years as promising electrochemical energy devices because they show higher energy densities than supercapacitors and higher power densities than batteries. In this study, we synthesized an Sn-Ni alloy by electrodeposition and applied it as an anode for LICs. To optimize the full-cell configuration, we controlled the mass balancing between the loading amounts of active materials in the cathode and anode with different mass ratios of 16:1, 8:1, and 4:1. In addition, the Sn-Ni alloy was investigated using electrochemical impedance spectroscopy under different depth of discharge (DOD) levels. The LICs assembled with a mass ratio of 4:1 between the cathode and anode exhibited good cyclability, rate performance, energy, and power density. This study not only improved the cycle performance of LICs full cell by mass balancing, but also revealed the relationship between the electrochemical characteristics of LICs and DOD levels of the Sn-Ni anode.

    DOI

    Scopus

    4
    被引用数
    (Scopus)
  • Facile fabrication of sulfur/Ketjenblack-PEDOT:PSS composite as a cathode with improved cycling performance for lithium sulfur batteries

    Seongki Ahn, Takayuki Noguchi, Toshiyuki Momma, Hiroki Nara, Tokihiko Yokoshima, Norihiro Togasaki, Tetsuya Osaka

    Chemical Physics Letters   749   137426 - 137426  2020年06月  [査読有り]

     概要を見る

    Lithium sulfur batteries (LSBs) are regarded as promising electrochemical energy storage devices owing to their higher theoretical capacity than commercial cathode materials. Herein, we report a simple method for preparing a modified sulfur/Ketjenblack (S/KB) cathode using polymer composite poly(3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT:PSS), which displays ionic and electron conductivity and can suppress polysulfide dissolution during the charge-discharge process. The S/KB + PEDOT:PSS cathode displayed higher electrochemical performance than the S/KB cathode. The effectiveness of suppressing polysulfide dissolution was determined visually and by UV-visible spectroscopy. The findings demonstrate the multi-functionality of PEDOT:PSS as an efficient electron conductive additive for S/KB cathode in high-performance LSBs.

    DOI

    Scopus

    13
    被引用数
    (Scopus)
  • Technology of electrochemical impedance spectroscopy for an energy-sustainable society

    Hiroki Nara, Tokihiko Yokoshima, Tetsuya Osaka

    Current Opinion in Electrochemistry   20   66 - 77  2020年04月  [査読有り]

    担当区分:筆頭著者, 責任著者

     概要を見る

    Electrochemical impedance spectroscopy has been widely used to understand the chemistry and physics of battery systems. This review covers electrochemical impedance spectroscopy used for the interpretation of impedance data of lithium-ion batteries (LIBs) from advanced equivalent circuit models to the mathematical model, which is developed by John Newman. In addition, as a method to realize an energy-sustainable society using diagnostics based on the combination of LIBs and electrochemical impedance spectroscopy, on-board diagnostics of battery packs are achieved based on an input signal generated by a power controller in a battery management system instead of the conventionally used frequency response analyzer. The diagnostic system is applicable to energy management systems which are installed in homes, buildings, and communities, accumulating the impedance data on state of health of LIBs. Finally, a future possibility regarding the diagnostics of battery packs coupled with the machine learning of impedance data is introduced.

    DOI

    Scopus

    31
    被引用数
    (Scopus)
  • Influence of Li-salts on Cycle Durability of Sn-Ni Alloy Anode for Lithium-ion Capacitor

    Yusuke NAKAMURA, Hiroki NARA, Seongki AHN, Toshiyuki MOMMA, Wataru SUGIMOTO, Tetsuya OSAKA

    Electrochemistry   88 ( 2 ) 74 - 78  2020年03月  [査読有り]

    担当区分:筆頭著者, 責任著者

     概要を見る

    Tin-nickel (Sn-Ni) alloy is a promising candidate as an anode for the lithium-ion capacitor (LIC) because it is superior in volumetric energy density compared with that of the graphite anode. However, its cycle durability requires improvement, even with a higher utilization ratio of the anode. The effect of lithium salts, LiPF6 and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is investigated for usage in the LIC in severe conditions (utilization ratio of the anode: 20%). The LIC with LiTFSI delivered its initial capacity up to similar to 400 cycles, which is 4 times longer than the LIC with LiPF6. The reason for the capacity decay in the LiPF6 system is attributed to the narrowing of the potential range of the activated carbon cathode due to a widening potential range of the Sn-Ni alloy anode during operation. This widening is attributed to the loss of the active material due to peeling-off from the substrate. However, when LiTFSI is used, no such decay is observed. It is suggested that a polymer-like solid electrolyte interphase derived from TFSI- may suppress the loss of the active material. This finding can encourage the development of an Sn-based anode for LICs in combination with a mild operating condition and electrolyte additives. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

    1
    被引用数
    (Scopus)
  • Synthesis of Stacked Graphene-Sn Composite as a High-Performance Anode for Lithium-Ion Capacitors

    Seongki Ahn, Yamato Haniu, Hiroki Nara, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    Journal of The Electrochemical Society   167 ( 4 ) 040519 - 040519  2020年02月  [査読有り]

     概要を見る

    A Lithium-ion capacitor (LIC) is composed of an electrochemical capacitor-like cathode and battery-like anode which store charge based on non-faradaic and faradaic processes, respectively. As an anode material for LIC, graphite is widely used because of its physical and electrochemical advantages. In the LIC system, stable cyclability at the high rate conditions is essential for bridging the gap between lithium-ion batteries and supercapacitors. However, there have been reported that the low working potential of graphite (close to 0.05 V vs Li/Li+) causes Li plating on the graphite surface and non-unity coulombic efficiency at high current charge/discharge results in degradation of cycle performance. To overcome this issue, stacked reduced graphene oxide-tin (SrGO-Sn) composite by co-reduction of graphene oxide and Sn2+ are studied in this work. The LIC consisting of SrGO-Sn anode shows good long-term cyclability with a remarkable capacity retention of 85, 77, and 60% at 10,000, 50,000, and 100,000th cycle and coulombic efficiency of 98% after 120,000 cycles. We believe that this study presents a new approach to the design of the high-performance LIC using an alternative to conventional graphite-based anode materials. (c) 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.

    DOI

    Scopus

    16
    被引用数
    (Scopus)
  • Synthesis of Lithium Sulfide (Li2S) Wrapped Carbon Nano Composite for Binder-Free Li2S Cathode

    Yunwen Wu, Toshiyuki Momma, Hiroki Nara, Tao Hang, Ming Li, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   167 ( 2 )  2020年01月  [査読有り]

     概要を見る

    Lithium sulfide (Li2S) is considered to be a promising cathode material for safer energy storage cells due to its compatibility with Li metal-free anodes. However, challenges remain regarding the insulating nature of Li2S, which leads to poor electrochemical performance, currently making Li2S electrodes far from practical in real-world applications. Herein we present a chemical method to synthesize Li2S nanoflake wrapped carbon material, Ketjenblack (LS@KB) composite, which can be coated on different current collectors without the addition of a binder. The high contact area between KB nanoparticles and Li2S nanoflakes effectively improves the cathode's conductivity, which contributes to a high Li2S weight ratio (83%). In addition, we prove that the well wrapped LS@KB structure enhances the physical confinement of polysulfides, leading to improved cyclability. As a result, the synthesized LS@KB cathode delivers stable cyclability (1000 cycles) with a fading rate of 0.03% per cycle at 0.5 C-rate. This room temperature fabrication strategy conquers the major drawbacks existing in Li2S fabrication, such as high temperature, hazardous gas release, complex and high-cost production process, making it a promising cathode material for light and safe portable electronic devices. (C) 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.

    DOI

    Scopus

    4
    被引用数
    (Scopus)
  • Tin addition for mechanical and electronic improvement of electrodeposited Si–O–C composite anode for lithium-ion battery

    Seongki Ahn, Takahiro Kadoya, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    Journal of Power Sources   437   226858 - 226858  2019年10月  [査読有り]

    DOI

    Scopus

    6
    被引用数
    (Scopus)
  • Fabrication of powdered Si-O-C composite by electrodeposition harvesting method as a long-cycle-life anode material for lithium-ion batteries

    Seongki Ahn, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    Materials Letters   251   184 - 187  2019年09月  [査読有り]

    DOI

    Scopus

    6
    被引用数
    (Scopus)
  • In-situ lithiation through an ‘injection’ strategy in the pouch type sulfur-graphite battery system

    Toshiyuki Momma, Yunwen Wu, Hitoshi Mikuriya, Hiroki Nara, Tetsuya Osaka

    Journal of Power Sources   430   228 - 232  2019年08月  [査読有り]

    DOI

    Scopus

    6
    被引用数
    (Scopus)
  • Effect of enhanced structural stability of Si-O-C anode by carbon nanotubes for lithium-ion battery

    Ahn Seongki, Nara Hiroki, Yokoshima Tokihiko, Momma Toshiyuki, Osaka Tetsuya

    MATERIALS LETTERS   245   200 - 203  2019年06月  [査読有り]

    DOI

    Scopus

    9
    被引用数
    (Scopus)
  • Application of Sn-Ni Alloy as an Anode for Lithium-Ion Capacitors with Improved Volumetric Energy and Power Density

    Journal of The Electrochemical Society   166 ( 15 ) A3615 - A3619  2019年  [査読有り]

    DOI

    Scopus

    11
    被引用数
    (Scopus)
  • Potentiostatic way to fabricate Li2Sx cathode with suppressed polysulfide formation

    Yunwen Wu, Takuya Jin, Toshiyuki Momma, Tokihiko Yokoshima, Hiroki Nara, Tetsuya Osaka

    Journal of Power Sources   399   287 - 293  2018年09月  [査読有り]

     概要を見る

    The usage of Li metal in lithium sulfur (Li-S) battery has largely hampered the application of Li-S battery due to the formation of Li dendrite during cycling. Here, a novel potentiostatic (p-stat) lithiation method was developed to fabricate Li2Sx cathode. The pre-lithiated Li2Sx cathode can be used to pair with the Li metal free anode to make a full cell with better safety. The dissolution of the polysulfide in electrolyte is the main problem in S cathode, which leads to severe active material loss during lithiation process. Normally, the way to alleviate the dissolution of polysulfide is by trapping the polysulfide from diffusing into the electrolyte. In this work, it is innovatively raised the p-stat lithiation method which can suppress the formation of polysulfides. As a result, dissolution of polysulfide species could be kinetically suppressed. The p-stat lithiated Li2Sx cathode exhibits higher capacity performance (around 400 mAh g(-1)) than the galvanostatic (g-stat) lithiated Li2Sx cathode. The Li metal free full cell assembled by pairing p-stat lithiated Li2Sx cathode with graphite anode shows stable cyclability.

    DOI

    Scopus

    5
    被引用数
    (Scopus)
  • High performance sulfur graphite full cell for next generation sulfur Li-ion battery

    Yunwen Wu, Toshiyuki Momma, Tokihiko Yokoshima, Hiroki Nara, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   388   5 - 10  2018年06月  [査読有り]

     概要を見る

    Sulfur (S) Li-ion battery which use the metallic Li free anode is deemed as a promising solution to conquer the hazards originating from Li metal. However, stable cycling performance and low production price of the S Li-ion battery still remain challenging. Here, we propose a S-LixC full cell system by paring a S cathode and a prelithiated graphite anode which is cheap and commercially available. It shows stable cycling performance with a capacity around 1300 mAh (g.S)(-1) at 0.2 C-rate and 1000 mAh (g.S)(-1) at 0.5 C-rate. In addition, 0.1% per cycle capacity fading rate with a capacity retention of 880 mAh (g.S)(-1) after 400 cycles at 0.2 C-rate has been achieved. The pre-formed solid electrolyte interphase (SEI) layer on the pre-lithaited graphite anode largely contributes to the high capacity performance. Notably, a 10-times-enlarged scale of S-LixC laminate type full cell has been assembled with high capacity performance (around 1000 mAh (g.S)(-1)) even after high rate cycling.

    DOI

    Scopus

    8
    被引用数
    (Scopus)
  • Liquid Chromatography-Quadruple Time of Flight Mass Spectrometry (LC-QToF/MS) for Deterioration Analysis of Lithium-ion Battery during Storage

    Misako Tochihara, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHEMISTRY   85 ( 11 ) 721 - 727  2017年11月  [査読有り]

     概要を見る

    Degradation of lithium-ion battery (LIB) was evaluated by using liquid chromatography-quadruple time of flight mass spectroscopy (LC-QToF/MS). Lab-made LIBs were degraded by storing at their states of charge of 50% at 25 or 60 degrees C for three months. The degradation of the LIB was accelerated at 60 degrees C compared with that at 25 degrees C. The electrochemical impedance spectroscopy analysis suggested that the remarkable degradation occurred for solid electrolyte interphase (SEI): it was implied that on one hand, the composition of the SEI for the LIB degraded at 25 degrees C did not vary, on the other hand, that at 60 degrees C varied. For LC-QToF/MS analysis, although decomposed products derived from the electrolyte solution were detected from the electrolyte in the LIB degraded at both 25 and 60 degrees C, those decomposed products were almost the same. Whereas, the difference between decomposed products at 25 and 60 degrees C was confirmed for the interphases between electrodes and electrolyte. The characteristic decomposed products at 60 degrees C was a product with more than C35 and more than 500 m/z of mass number. This product should be one of the reason of capacity degradation due to the internal resistance increase. Thus, a possibility of LC-QToF/MS was demonstrated. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

    Scopus

  • On-site chemical pre-lithiation of S cathode at room temperature on a 3D nano-structured current collector

    Yunwen Wu, Toshiyuki Momma, Seongki Ahn, Tokihiko Yokoshima, Hiroki Nara, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   366   65 - 71  2017年10月  [査読有り]

     概要を見る

    This work reports a new chemical pre-lithiation method to fabricate lithium sulfide (Li2S) cathode. This pre-lithiation process is taken place simply by dropping the organolithium reagent lithium naphthalenide (Li(+)Naph(-)) on the prepared sulfur cathode. It is the first time realizing the room temperature chemical pre-lithaition reaction attributed by the 3D nanostructured carbon nanotube (CNT) current collector. It is confirmed that the Li2S cathode fabricated at room temperature showing higher capacity and lower hysteresis than the Li2S cathode fabricated at high temperature pre-lithiation. The prelithiated Li2S cathode at room temperature shows stable cycling performance with a 600 mAh g(-1), capacity after 100 cycles at 0.1 C-rate and high capacity of 500 mAh g(-1) at 2 C-rate. This simple on -site prelithiation method at room temperature is demonstrated to be applicable for the in-situ pre-lithiation in a Li metal free battery. (C) 2017 The Authors. Published by Elsevier B.V.

    DOI

    Scopus

    42
    被引用数
    (Scopus)
  • Impedance Measurements of Kilowatt-Class Lithium Ion Battery Modules/Cubicles in Energy Storage Systems by Square-Current Electrochemical Impedance Spectroscopy

    Tokihiko Yokoshima, Daikichi Mukoyama, Hiroki Nara, Suguru Maeda, Kazuhiro Nakazawa, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   246   800 - 811  2017年08月  [査読有り]

     概要を見る

    Electrochemical impedance measurements of lithium ion batteries (LIBs) in energy storage systems (ESS) were performed. Square-current electrochemical impedance spectroscopy (SC-EIS), which is a simple and cost-effective approach to measure impedance, was chosen to investigate a large-scale LIB system. Harmonics calculated by Fourier transform from a square waveform were used to determine the impedance. On the basis of a simple electrochemical reaction involving the ferri/ferro-cyanide redox couple and the LIB, the accuracy of the impedance measurement was found to depend on both the signal-to-noise ratio of the power spectra of the harmonics as well as the attenuation rate of the "measured value of impedance" and the "theoretical spectra value" from Fourier series. The accuracy was improved by adjusting the input waveform to be close to an ideal square waveform from Fourier series. The accuracy was further improved by the combined use of a simple moving average and an overall average. The impedance from a degraded square waveform generated by a cost-effective power controller was able to be determined by increasing the measurement time, which aided averaging. By designing the input signal to be close to an ideal square waveform from Fourier series, kilowatt-class LIB modules/cubicles in an ESS was able to be measured. Moreover, a degraded LIB module in an ESS was able to be detected using EIS, which highlights the utility of this technique for in situ impedance measurements of large-scale LIB systems. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    25
    被引用数
    (Scopus)
  • Techniques for realizing practical application of sulfur cathodes in future Li-ion batteries

    Hiroki Nara, Shingo Tsuda, Tetsuya Osaka

    JOURNAL OF SOLID STATE ELECTROCHEMISTRY   21 ( 7 ) 1925 - 1937  2017年07月  [査読有り]

    担当区分:筆頭著者, 責任著者

     概要を見る

    The development of lithium-sulfur batteries is associated with many problems. These problems include polysulfide dissolution, the shuttle phenomenon, the low electric and ionic conductivity of S, and the volume change that occurs during charge and discharge. In this review, various elemental techniques for overcoming these problems are summarized from the standpoints of the supporting materials. These techniques include preventing polysulfide dissolution from the cathodes through physical and chemical adsorption on the supporting materials, the use of electrolytes that do not dissolve polysulfides via the coordination of Li+ and solvents, and the use of ion-exchange polymers to permeate Li+ selectively. The following approaches to enable practical applications of S cathodes in future Li-ion batteries are introduced: the utilization of Li-free anode materials, such as C and Si; the use of Li2S cathodes, which are prepared via a pre-lithiation process; and increasing the areal capacity of the S cathode by using a suitable current collector such as Al foam, thus providing a large amount of space for Li+ to migrate and the electron-conductive path. The utilization of an Al foam current collector is one of the promising approaches to creating a cost-effective Li-ion battery owing to the established mass production of Al foam for use in NiMH batteries; such Li-ion battery can achieve an unprecedentedly high areal capacity of 21.9 mAh cm(-2). Owing to the resulting areal capacity, the possibility of developing a lithium-sulfur battery with an energy density greater than 200 Wh kg(-1) has been demonstrated. Consequently, the combination of these approaches, as introduced in this review, would help create a bright, sustainable society.

    DOI

    Scopus

    15
    被引用数
    (Scopus)
  • Carbonate-based additive for improvement of cycle durability of electrodeposited Si-O-C composite anode in glyme-based ionic liquid electrolyte for use in lithium secondary batteries

    Shohei Seko, Hiroki Nara, Moongook Jeong, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   243   65 - 71  2017年07月  [査読有り]

     概要を見る

    The cycle durability of electrodeposited Si-O-C composite anodes in glyme-based ionic liquid electrolytes, known as Li(G3)TESI or Li(G4)TFSI (triglyme: G3 and tetraglyme: G4), which is one of the most promising electrolytes for sulfur cathode, was improved for use in lithium secondary batteries by using additives, fluoroethylene carbonate (FEC) or vinylene carbonate (VC). We revealed an importance of the activation process and the effects of additives in the Si-O-C composite anode. The capacity of the Si-O-C composite anode decreased with charge-discharge cycles in electrolytes without additives. Meanwhile, although the capacity retention in electrolytes with additives was improved by 10-20%, their initial capacity was smaller than those without additives. To solve the contradiction, an activation process, in which the Si-O-C composite anode was charged and discharged in electrolytes without additives, was introduced before charge-discharge cycles in electrolytes with additives. Owing to the optimized activation process, the initial capacity in electrolytes with additives showed as high as 1100-1300 mAh(-1) as those without additives with better capacity retention. Therefore, the necessity to adequately generate an activation reaction and to form SEI derived from additives for the Si-O-C composite anode to have better charge-discharge performance was demonstrated. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    17
    被引用数
    (Scopus)
  • The Nationwide Cancer Genome Screening Project in Japan SCRUM-Japan, GI-screen: Efficient identification of cancer genome alterations in advanced gastric cancer.

    Shigenori Kadowaki, Kohei Shitara, Satoshi Yuki, Shuichi Hironaka, Takeshi Kato, Hiroki Nara, Takeshi Kajiwara, Naoki Izawa, Satoru Iwasa, Toshikazu Moriwaki, Daisuke Naruge, Taito Esaki, Hiroshi Saeki, Toshihiro Kudo, Haruhiko Cho, Takao Tamura, Hiromichi Ebi, Shogo Nomura, Atsushi Ohtsu, Takayuki Yoshino

    JOURNAL OF CLINICAL ONCOLOGY   35  2017年05月

    DOI

  • A pre-lithiation method for sulfur cathode used for future lithium metal free full battery

    Yunwen Wu, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   342   537 - 545  2017年02月  [査読有り]

     概要を見る

    Lithium metal free sulfur battery paired by lithium sulfide (Li2S) is a hot point in recent years because of its potential for relatively high capacity and its safety advantage. Due to the insulating nature and high sensitivity to moisture of Li2S, it calls for new way to introduce Li ion into S cathode besides the method of directly using the Li2S powder for the battery pre-lithiation. Herein, we proposed a pre-lithiation method to lithiate the polypyrrole (PPy)/S/Ketjenblack (KB) electrode into PPy/Li2S/KB cathode at room temperature. By this process, the fully lithiated PPy/Li2S/KB cathode showed facilitated charge transfer than the original PPy/S/KB cathode, leading to better cycling performance at high C-rates and disappearance of over potential phenomenon. In this work, the ion-selective PPy layer has been introduced on the cathode surface by an electrodeposition method, which can suppress the polysulfide dissolution from the cathode source. The lithium metal free full battery coupled by the prepared Li2S/KB cathode and graphite anode exhibited excellent cycling performance. Hence, we believe this comprehensive fabrication approach of Li2S cathode will pave a way for the application of new type lithium metal free secondary battery. (C) 2016 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    30
    被引用数
    (Scopus)
  • Development of Areal Capacity of Si-O-C Composites as Anode for Lithium Secondary Batteries Using 3D-Structured Carbon Paper as a Current Collector

    Seongki Ahn, Moongook Jeong, Koki Miyamoto, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   164 ( 2 ) A355 - A359  2017年  [査読有り]

     概要を見る

    To enlarge the areal capacity of Si-O-C composites as an anode for high energy Li secondary batteries, 3D-structured carbon paper is used as a current collector for electrodeposition of Si-O-C composites. For higher surface affinity between organic solvents with carbon paper, surface treatment of carbon paper is carried out using a sulfuric acid-hydrogen peroxide mixture (SPM) solution. The higher deposited Si amounts and areal capacity are obtained by SPM treatment of carbon paper due to its enhanced surface affinity between carbon paper and electrolytes during Si-O-C electrodeposition. In addition, two kinds of organic solvents, propylene carbonate (PC) and ethylene carbonate/diethyl carbonate (EC/DEC), are employed to investigate their suitability for the electrodeposition of Si-O-C composites. As a result, it is confirmed that the Si-O-C composites synthesized by EC/DEC solvents show more stable cycle abilities than in the case of using PC solvents at a high charge current density of 1.0 mA cm(-2). This is due to the exfoliation of carbon paper by PC, resulting in fast capacity fading during charge/discharge cycle. Nevertheless, it is confirmed that the use of carbon paper as a substrate for Si-O-C electrodeposition is an effective way to increase deposited Si amounts and discharge areal capacity. (C) 2017 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    7
    被引用数
    (Scopus)
  • The Potential for the Creation of a High Areal Capacity Lithium-Sulfur Battery Using a Metal Foam Current Collector

    Hiroki Nara, Tokihiko Yokoshima, Hitoshi Mikuriya, Shingo Tsuda, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   164 ( 1 ) A5026 - A5030  2017年  [査読有り]

    担当区分:筆頭著者, 責任著者

     概要を見る

    A high areal capacity lithium-sulfur battery making use of mass produced aluminum metal foam as a current collector was investigated. A sulfur/Ketjenblack (KB) composite was filled and deposited into the aluminum foam current collector via a predetermined filling procedure, resulting in high sulfur loading. The value for this loading was found to be 17.7 mg sulfur/cm(2) by using carboxymethyl cellulose and styrene butadiene rubber (CMC + SBR) as a binder. An operating single-layer pouch-type cell with an S/KB+CMC+SBR on Al foam cathode was created as a result of this synthesis and found to possess an unprecedentedly high areal capacity of 21.9 mAh/cm(2). On the basis of the achieved areal capacity, the energy density of a theoretical lithium-sulfur battery was estimated with the assumption of an electrolyte/sulfur ratio of 2.7 mu L/mg. This was calculated upon 100% of the pore volume in the S/KB-CMC + SBR on Al foam cathodes and polyolefin separator, along with the inclusion of the weights of the tabs for the current lead and pouch film packaging in the case of a seven-layer pouch-type battery. With this calculation, it was determined that the creation of a lithium-sulfur battery with an energy density of greater than 200 Wh/kg is plausible. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.

    DOI

    Scopus

    30
    被引用数
    (Scopus)
  • Electrophoretically deposited carbon nanotube anchor layer to improve areal capacity of Si-O-C composite anode for lithium secondary batteries

    Seongki Ahn, Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   336   203 - 211  2016年12月  [査読有り]

     概要を見る

    In this study, we report the preparation of carbon nanotubes (CNTs) anchor layer on a Cu substrate (CNTs/Cu) by using electrophoretic deposition technique. The CNTs anchor layer increases adhesion strength between Si-O-C composites and Cu substrate, as a result, it is possible to improve deposited Si amounts and areal capacity. The electrodeposited Si-O-C composites on CNTs/Cu (Si-O-C/CNTs/Cu) show homogenously coated surface morphology without cracks even large passing charge for electrodeposition of 15 C cm(-2), resulting in 0.21 mg cm(-2) of deposited Si amounts. On the other hand, Si-O-C composites deposited on as-received Cu substrate (Si-O-C/Cu) begin to peel off from substrate at 8 C cm(-2) of passing charge, resulting in 0.13 mg cm(-2) of deposited Si amounts, and decrease down to 0.10 mg cm(-2) at 15 C cm(-2) of passing charge. As a results, the improved Si amounts deposited on CNTs/Cu substrate achieve higher areal capacity, delivering 0.24 mA h cm(-2), which attains increase in 84.6% in comparison to Si-O-C/Cu, which has areal capacity of 0.13 mA g cm(-2) at 8 C cm(-2) of passing charge. Moreover, the Si-O-C/CNTs/Cu shows improved anode performances including discharge capacity and C-rate performance of the Si-O-C composites than Si-O-C/Cu without CNTs anchor layer. (C) 2016 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    15
    被引用数
    (Scopus)
  • New approach for enhancing electrical conductivity of electrodeposited Si-based anode material for Li secondary batteries: Self-incorporation of nano Cu metal in Si-O-C composite

    Moongook Jeong, Seongki Ahn, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    NANO ENERGY   28   51 - 62  2016年10月  [査読有り]

     概要を見る

    The poor electrical conductivity of Si-based anode materials is a critical challenge for the development of high-performance Li secondary batteries. We propose a new approach for enhancing the electrical conductivity of an electrodeposited Si-O-C composite anode via self-incorporation of nano Cu metal (n-Cu) using a facile and inexpensive electrochemical synthetic method. The Si-O-C composite with n-Cu (Cu/Si-O-C composite) shows stable cycle performance with a fairly high specific capacity. Since Cu precursor ions for the electrodeposition of n-Cu are directly dissolved from a Cu substrate used as the current collector for the anode, electrical conducting additives that causes increase in the weight and volume of the electrode are not unnecessarily supplemented. In the synthesis process, the n-Cu metal and Si-O-C composite are electrodeposited simultaneously. The n-Cu/Si-O-C composite anode results in improved electrochemical performance, including enhancement of areal and specific capacity; coulombic efficiency; and rate capability. Electrochemical impedance spectroscopy suggests that such improvements in performance are due to the enhanced electrical conductivity resulting from the conductive network of the incorporated n-Cu. Moreover, the electrical conductive properties of the incorporated n-Cu suppress electrochemical degradation of the n-Cu/Si-O-C composite anode. (C) 2016 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    37
    被引用数
    (Scopus)
  • Electrochemical impedance spectroscopy analysis with a symmetric cell for LiCoO2 cathode degradation correlated with Co dissolution

    Hiroki Nara, Keisuke Morita, Tokihiko Yokoshima, Daikichi Mukoyama, Toshiyuki Momma, Tetsuya Osaka

    AIMS Materials Science   3 ( 2 ) 448 - 459  2016年  [査読有り]

    担当区分:筆頭著者

     概要を見る

    Static degradation of LiCoO2 cathodes is a problem that hinders accurate analysis using our developed separable symmetric cell. Therefore, in this study we investigate the static degradation of LiCoO2 cathodes in separable symmetric cells by electrochemical impedance spectroscopy (EIS) and inductively coupled plasma analyses. EIS measurements of LiCoO2 cathodes are conducted in various electrolytes, with different anions and with or without HF and/or Hli O. This allows us to determine the static degradation of LiCoO2 cathodes relative to their increase of charge transfer resistance. The increase of the charge transfer resistance of the LiCoO2 cathodes is attributed to cobalt dissolution from the active material of LiCoO2. Cobalt dissolution from LiCoO2 is revealed to occur even at low potential in the presence of HF, which is generated from LiPF6 and H2O. The results indicate that avoidance of HF generation is important for the analysis of lithium-ion battery electrodes by using the separable cell. These findings reveal the condition to achieve accurate analysis by EIS using the separable cell.

    DOI

    Scopus

    16
    被引用数
    (Scopus)
  • Film Properties of Electropolymerized Polypyrrole for a Sulfur/Ketjenblack Cathode in Lithium Secondary Batteries

    Natsuki Nakamura, Yunwen Wu, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   163 ( 5 ) A683 - A689  2016年  [査読有り]

     概要を見る

    A novel polypyrrole (PPy) film was investigated to determine the optimal conditions for operation in a Li/S battery. The PPy film was prepared by oxidative electropolymerization to improve the Li/S battery performance, as reported in our previous paper. In such a system, the PPy film was coated directly on the S/Ketjenblack cathode to solve the problem of polysulfide dissolution. The optimum PPy film preparation conditions to prevent polysulfide dissolution and to promote Li+ permeability were determined by varying the PPy polymerization bath composition and polymerization potential. As a result, the inclusion of 1.0 M lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) in the polymerization bath (0.1 M pyrrole in 1-methyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl) imide) was found to be the most important factor for producing a PPy film with a high Li+ transport number (t(Li+) approximate to 1). A polymerization potential of 4.5 V versus Li/Li+ was shown to be optimum for the promotion of Li+ permeability. The mechanism by which the PPy film prevents polysulfide dissolution and increases Li+ permeability is discussed by analyzing the SEM, CV, XPS, and C-13 solid-state NMR data. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/),which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.

    DOI

    Scopus

    21
    被引用数
    (Scopus)
  • Micro-scale Li2S-C composite preparation from Li2SO4 for cathode of lithium ion battery

    Jun Liu, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   183   70 - 77  2015年11月  [査読有り]

     概要を見る

    A facile and scalable method is proposed to prepare microscale Li2S-C composite from Li2SO4 through carbon-thermal reduction, followed by a carbon coating process. Multi-solvent recrystallization was utilized to reduce the particle size of Li2SO4 to 2 mu m. This fine-grain Li2SO4 helps to shorten the particle size of reduction product from 10 mu mto 3 mu m. Using fine Li2SO4 also brings the benefit of greatly reducing the over potential during the initial charge process and increasing the kinetics for Li2S materials. Finally, the microscale Li2S-C composite prepared from fine Li2SO4 enables a stable capacity of 350 mAh g(-1) at 0.2 C, higher than that obtained using a cathode prepared from commercial Li2SO4. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    23
    被引用数
    (Scopus)
  • One-Step Hydrothermal Synthesis of SnS2/SnO2/C Hierarchical Heterostructures for Li-ion Batteries Anode with Superior Rate Capabilities

    Chun-Yi Chen, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   183   78 - 84  2015年11月  [査読有り]

     概要を見る

    Novel three-dimensional hierarchical heterostructures composed of two-dimensional SnS2 nanoflakes and zero-dimensional SnO2 nanoparticles were fabricated via a one-step hydrothermal method. Size of the heterostructures was ca. 2 mu m in diameter, and individual SnS2 nanoflakes with thickness of ca. 150 nm were connected to central core of the heterostructures. The SnO2 nanoparticles in a diameter of ca. 5 nm uniformly covered entire surface of the SnS2 nanoflakes. Moreover, both of these structures were highly crystalline. Meanwhile, amorphous carbon was formed within the heterostructures. The SnS2/SnO2/C hierarchical heterostructures had a high initial specific reversible capacity of 1065.7 mAh g(-1), stable cycling stability of 638 mAh g(-1) after 30 cycles, and superior rate capability of 550.8 mAh g(-1) at 1C rate. These SnS2/SnO2/C hierarchical heterostructures showed better performance than individual SnS2 and SnO2 nanomaterials, and the performance was even higher than the graphene-SnS2 and graphene-SnO2 nanohybrid materials. This is attributed to a synergistic effect of high surface area, which is provided by the unique SnS2 internal nanoflake layered structures decorated with ultra-fine SnO2 nanoparticles, and an effective beneficial buffer matrix to accommodate the large volume change upon cycling, which is caused by the side-products such as Li2S or Li2O. The SnS2 nanoflake was deduced to play a similar role as graphene material, since both possess 2D conducting layer structures. The uniform carbon dispersion within the structures also stabilizes the structures and improves electrical conductivity of the hierarchical heterostructures. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    28
    被引用数
    (Scopus)
  • Application of Electrochemical Impedance Spectroscopy to Ferri/Ferrocyanide Redox Couple and Lithium Ion Battery Systems Using a Square Wave as Signal Input

    Tokihiko Yokoshima, Daikichi Mukoyama, Kazuhiro Nakazawa, Yuhei Gima, Hidehiko Isawa, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   180   922 - 928  2015年10月  [査読有り]

     概要を見る

    To realize electrochemical impedance spectroscopy (EIS) using a simple measurement system, application of a square potential/current waveform to the input signals of EIS was investigated. The impedance of a simple redox reaction of [Fe(CN)(6)](4-)/[Fe(CN)(6)](3-) solution was measured by the potentio-EIS using a square waveform as the input signal, which was generated by a potentiostat system without a frequency response analyzer (FRA). A steady impedance response in the frequency range of 40 Hz-3.5 kHz was obtained, and the impedance was obtained by the potentiostat system with an FRA. The errors-the differences between the impedance measured by EIS with a square potential waveform and that of conventional EIS-were sufficiently low to allow impedance analysis. The impedance of a lithium-ion battery (LIB) was measured by galvano-EIS using a square waveform input signal generated by a power controller. A steady impedance response in the frequency range of 5 Hz-2.5 kHz was obtained, and the errors were sufficiently low to allow impedance analysis. It was demonstrated that both square potential-EIS (SP-EIS) and square current-EIS (SC-EIS) have great potential as simple systems for measuring impedance. Moreover, it was demonstrated that SC-EIS has potential as a simple measurement system for analyzing the state of an LIB. Thus, the potential of the SP/SC-EIS methodology was confirmed for electrochemical systems. (C) 2015 Published by Elsevier Ltd.

    DOI

    Scopus

    34
    被引用数
    (Scopus)
  • Effect of electrolyte on cycle performances of the electrodeposited Sn-O-C composite anode of lithium secondary batteries

    Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   275   525 - 530  2015年02月  [査読有り]

     概要を見る

    The electrodeposited Sn-O-C composite anode cycling with LiClO4 delivered stable cycle performances showing discharge capacity of 473 mA h g Risri with 95% of coulombic efficiency at 100th cycle. However, the anode showed poor cycle performances with LiPF6 delivering discharge capacity of 69 mA h g(-1) of sn at 100th cycle with 70% of coulombic efficiency. Electrochemical investigation performed by cyclic voltammetry and differential capacity plots revealed that the Sn-O-C composite cycling with LiPF86 suffered from retarded phase transition reaction between Li and Sn during charge/discharge process. X-ray photoelectron spectroscopy declared the existence of fluorinated-Sn and LiF. Moreover, energy dispersive X-ray spectroscopy found increase in their amount with repeated cycles. The morphologies of the Sn-O-C composite cycled with LiPF6 showed aggregated particles containing the chemical state of fluorinated-Sn and LiF on its surface. Furthermore, the significant pulverization and aggregation of the active material were observed from the Sn-O-C composite cycled by LiPF6 rather than that of LiClO4, which was probably promoted by the generated HF strongly corroding metallic component. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    8
    被引用数
    (Scopus)
  • Review-Development of Diagnostic Process for Commercially Available Batteries, Especially Lithium Ion Battery, by Electrochemical Impedance Spectroscopy

    Tetsuya Osaka, Daikichi Mukoyama, Hiroki Nara

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   162 ( 14 ) A2529 - A2537  2015年  [査読有り]

     概要を見る

    Electrochemical impedance spectroscopy (EIS) can be utilized to characterize battery features, because it allows the dynamics of each elemental process of the battery reaction to be sensitively and separately determined without destruction of the cell. In addition, EIS is expected to be utilized for premonitory diagnosis of onboard batteries in electric vehicles. Here; an overview of the recent diagnosis technologies for determining the health of commercial lithium-ion batteries (LIB) using EIS is provided. We describe equivalent circuit design techniques while explaining and investigating physical and chemical phenomena for a wide range of measured impedance spectra, which are obtained using commercial LIBs.. Attention is then focused on separation of the frequency responses of each electrode with or without a reference electrode, symmetric cell, and temperature control. Additionally, a square-current EIS (SC-EIS) technique, which we have proposed, is introduced for monitoring of large-scale LIB systems as a promising future technique. (C) 2015 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    122
    被引用数
    (Scopus)
  • Li2S cathode modified with polyvinylpyrrolidone and mechanical milling with carbon

    Jun Liu, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   273   1136 - 1141  2015年01月  [査読有り]

     概要を見る

    Polyvinylpyrrolidone (PVP) is used with polyethylene oxide (PEO) as a mixed binder for mechanically milled Li2S. PVP demonstrates its advantage in terms of increasing the capacity of Li2S, but boosts the potential barrier at the beginning of the first charge. It is also revealed that PVP retards the charge-transfer kinetics of Li2S. In Li2S-C prepared by mechanical milling, carbon compensates for the electrochemical insulation of the PVP binder and improves the cycle stability. As a result, the Li2S-C-PVP electrode with 60 wt% Li2S content displays a low potential barrier at the onset of charge and a stable capacity of about 460 mAh g(-1) at 0.1 C. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    46
    被引用数
    (Scopus)
  • Suppression of polysulfide dissolution by polypyrrole modification of sulfur-based cathodes in lithium secondary batteries

    Natsuki Nakamura, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   274   1263 - 1266  2015年01月  [査読有り]

     概要を見る

    In order to solve the problem of polysulfide dissolution into the electrolyte on sulfur-based cathodes, we propose a novel method of modifying the S cathode by coating it with a polypyrrole (PPy) film, which is prepared by oxidative electropolymerization using a solution consisting of, 1-methyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and pyrrole. The PPy film demonstrates a high Li+ transport number. The film also exhibits a superior ability to inhibit polysulfide dissolution into the electrolyte during the charge discharge cycles. Furthermore, the charge discharge properties of the coated cathode is evaluated using an electrolyte consisting of 1.0 M LiTFSI in a mixture of 1,2-dimethoxyethane (DME) and 1,3-dioxolane (DOL), which is known to easily dissolve polysulfides. Because of the surface modification with the PPy film, the cathode exhibits excellent specific capacities of 823 and 354 mAh g(-1) at C-rates of 0.1 and 1.0 C, respectively, with high coulombic efficiency. Thus, the strategy of coating the S cathode with PPy is successful in inhibiting the polysulfides dissolution even in electrolytes known to easily dissolve polysulfides, besides allowing high C-rate operation. Further, the modification of the S cathode allows the selection of a suitable electrolyte based on the anode, rather than being limited by the cathode. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    48
    被引用数
    (Scopus)
  • Liquid Chromatography-Quadruple Time of Flight Mass Spectrometry Analysis of Products in Degraded Lithium-Ion Batteries

    Misako Tochihara, Hiroki Nara, Daikichi Mukoyama, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   162 ( 10 ) A2008 - A2015  2015年  [査読有り]

     概要を見る

    The electrode surfaces of degraded lithium-ion batteries (LIB) were analyzed by liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOF/MS). The solid-electrolyte interphase (SET) layer influences the performance of LIBs. Therefore, we conducted a study aimed at clarifying the deterioration mechanism of LIBs by examining the components in the SET before and after degradation due to cycling. We believe that the change in the mass transfer characteristics at the electrode interface influenced by SET deterioration can be clarified via Lc-QTOF/MS, which would allow elucidation of the deterioration mechanism. The analysis results showed that the degradation products contain multiple components, including polymers of carbonate compounds and phosphate esters, which are formed via electrochemical and chemical reactions, resulting in remarkably reduced capacity. The results suggest that LC-QTOF/MS is a valuable technique for the degradation analysis of LIBs. (C) The Author(s) 2015. Published by ECS. All rights reserved.

    DOI

    Scopus

    31
    被引用数
    (Scopus)
  • Li-Rich Li-Si Alloy As A Lithium-Containing Negative Electrode Material Towards High Energy Lithium-Ion Batteries

    Shinichiroh Iwamura, Hirotomo Nishihara, Yoshitaka Ono, Haruhiko Morito, Hisanori Yamane, Hiroki Nara, Tetsuya Osaka, Takashi Kyotani

    SCIENTIFIC REPORTS   5  2015年01月  [査読有り]

     概要を見る

    Lithium-ion batteries (LIBs) are generally constructed by lithium-including positive electrode materials, such as LiCoO2, and lithium-free negative electrode materials, such as graphite. Recently, lithium-free positive electrode materials, such as sulfur, are gathering great attention from their very high capacities, thereby significantly increasing the energy density of LIBs. Though the lithium-free materials need to be combined with lithium-containing negative electrode materials, the latter has not been well developed yet. In this work, the feasibility of Li-rich Li-Si alloy is examined as a lithium-containing negative electrode material. Li-rich Li-Si alloy is prepared by the melt-solidification of Li and Si metals with the composition of Li21Si5. By repeating delithiation/lithiation cycles, Li-Si particles turn into porous structure, whereas the original particle size remains unchanged. Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si. The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode. Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

    DOI

    Scopus

    50
    被引用数
    (Scopus)
  • Electrodeposited three-dimensional porous Si-O-C/Ni thick film as high performance anode for lithium-ion batteries

    Xin Qian, Tao Hang, Hiroki Nara, Tokihiko Yokoshima, Ming Li, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   272   794 - 799  2014年12月  [査読有り]

     概要を見る

    A novel 3D porous Si-O-C/Ni thick film anode is successfully prepared by electrodeposition of porous Ni on Cu substrate and galvanostatical electrodeposition of Si-O-C composite on porous Ni substrate. The 3D porous Si-O-C/Ni thick film is electrochemically activated at a current density of 50 mu A cm(-2) for the first cycle and 200 mu A cm(-2) (0.5 C) for the subsequent cycles, it displays superior electrochemical performance with discharge capacity of 706.3 mAh g(-1) of Si after 100 cycles. The properties of this thick film is analyzed by field emission scanning electron microscopy (FESEM) and scanning transmission electron microscopy with energy dispersive X-ray analyzer (STEM-EDX). The results show that Si-O-C composite not only covers the surface area of porous Ni but also attaches to the highly porous dendritic walls, along with the porous structure of Ni which provides proper accommodation for the volume change of silicon during the lithiation/delithiation processes, are believed to result in the high capacity and excellent cyclability. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    19
    被引用数
    (Scopus)
  • Zinc-Air Battery: Understanding the Structure and Morphology Changes of Graphene-Supported CoMn2O4 Bifunctional Catalysts Under Practical Rechargeable Conditions

    Moni Prabu, Prakash Ramakrishnan, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka, Sangaraju Shanmugam

    ACS APPLIED MATERIALS & INTERFACES   6 ( 19 ) 16545 - 16555  2014年10月  [査読有り]

     概要を見る

    Nitrogen-doped/undoped thermally reduced graphene oxide (N-rGO) decorated with CoMn2O4 (CMO) nanoparticles were synthesized using a simple one-step hydrothermal method. The activity and stability of this hybrid catalyst were evaluated by preparing air electrodes with both primary and rechargeable zinc-air batteries that consume ambient air. Further, we investigated the relationship between the physical properties and the electrochemical results for hybrid electrodes at various cycles using X-ray diffraction, scanning electron microscopy, galvanodynamic charge-discharging and electrochemical impedance spectroscopy. The structural, morphological and electrocatalytic performances confirm that CMO/N-rGO is a promising material for safe, reliable, and long-lasting air cathodes for both primary and rechargeable zinc-air batteries that consume air under ambient condition.

    DOI

    Scopus

    128
    被引用数
    (Scopus)
  • A Lithium-Ion Sulfur Battery Based on a Carbon-Coated Lithium-Sulfide Cathode and an Electrodeposited Silicon-Based Anode

    Marco Agostini, Jusef Hassoun, Jun Liu, Moongook Jeong, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka, Yang-Kook Sun, Bruno Scrosati

    ACS APPLIED MATERIALS & INTERFACES   6 ( 14 ) 10924 - 10928  2014年07月  [査読有り]

     概要を見る

    In this paper, we report a lithium-ion battery employing a lithium sulfide cathode and a silicon-based anode. The high capacity of the silicon anode and the high efficiency and cycling rate of the lithium sulfide cathode allowed optimal full cell balance. We show in fact that the battery operates with a very stable capacity of about 280 mAh g(-1) at an average voltage of 1.4 V. To the best of our knowledge, this battery is one of the rare examples of lithium-metal-free sulfur battery. Considering the high theoretical capacity of the employed electrodes, we believe that the battery here reported may be of potential interest as high-energy, safe, and low-cost power source for electric vehicles.

    DOI

    Scopus

    119
    被引用数
    (Scopus)
  • Carbon-coated Li2S Synthesized by Poly(vinylpyrrolidone) and Acetylene Black for Lithium Ion Battery Cathodes

    Jun Liu, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    CHEMISTRY LETTERS   43 ( 6 ) 901 - 903  2014年06月  [査読有り]

     概要を見る

    A carbon-coated Li2S was prepared through an adsorption and successive annealing process by using poly(vinylpyrrolidone) (PVP) and acetylene black (AB) as carbon source with Li2S powder. The coating layer was composed of amorphous carbon and embedded AB particles. The carbon coating was found to effectively alleviate the dissolution of polysulfide and the discharge capacity at the first 15 cycles was 800 mA h g(-1) with gradual fading afterward.

    DOI

    Scopus

    17
    被引用数
    (Scopus)
  • Electrochemical impedance analysis of electrodeposited Si-O-C composite thick film on Cu microcones-arrayed current collector for lithium ion battery anode

    Tao Hang, Daikichi Mukoyama, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Ming Li, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   256   226 - 232  2014年06月  [査読有り]

     概要を見る

    The impedance behaviors of Si-O-C composite film electrodeposited on Cu microcones-arrayed current collector have been investigated to understand the electrochemical process kinetics that influences the cycling performance when used as a highly-durable anode in a lithium battery. The impedance was measured by using impedance spectroscopy in equilibrium conditions at various depths of discharge and during several hundred charge-discharge cycles. The measured impedance was interpreted with an equivalent circuit composed of solid electrolyte interphase (SEI) film, charge transfer and solid state diffusion. The impedance analysis shows that the change of charge transfer resistance is the main contribution to the total resistance Change during discharge, but an abrupt augmentation of diffusive resistance at high depth of discharge is also observed which cannot be explained very well by the presented model. The impedance evolution of this electrode during charge-discharge cycles suggests that the slow growth of the SEI film as well as the increase of the electrode density are responsible for the capacity fading after long term cycling. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    36
    被引用数
    (Scopus)
  • Distinction of impedance responses of Li-ion batteries for individual electrodes using symmetric cells

    Toshiyuki Momma, Tokihiko Yokoshima, Hiroki Nara, Yuhei Gima, Tetsuya Osaka

    ELECTROCHIMICA ACTA   131   195 - 201  2014年06月  [査読有り]

     概要を見る

    Symmetric cells were prepared with a newly designed separable cell module, which enabled ca. 70 mm by 70 mm electrode sheets to be used for a pouch type 5 Ah class Li-ion battery (LIB). Impedance analysis of the LIB as a full cell state was successfully performed with electrochemical parameters obtained by an impedance analysis of symmetric cells of anodes and cathodes obtained from the operated Li-ion batteries. While the charge transfer resistance of the cathode was found to increase after reassembling the cells symmetrically, other electrochemical parameters were found not to change when comparing the values obtained for full cells with symmetric cells. Eelectrodes degraded by charge/discharge cycling of the battery were also investigated, and the parameter change caused by the degradation was confirmed. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    55
    被引用数
    (Scopus)
  • New Si-O-C composite film anode materials for LIB by electrodeposition

    Tetsuya Osaka, Hiroki Nara, Toshiyuki Momma, Tokihiko Yokoshima

    JOURNAL OF MATERIALS CHEMISTRY A   2 ( 4 ) 883 - 896  2014年  [査読有り]

     概要を見る

    Silicon is one of the most promising materials for lithium secondary battery anodes. However, silicon anodes have a critical drawback to their practical application, which is capacity degradation due to pulverization of the active material by the large volume change of silicon during charge-discharge cycles. This paper reviews recent studies on silicon-based anodes that have attempted to overcome this poor cycle durability through structural control such as through thin films, porous structures, core-shell structures, and by alloying with other metals, and by application of proper binders. Among them, binder-free Si-O-C composite films prepared by electrodeposition exhibit outstanding cycle durability. The origin of this excellent durability is discussed in depth from the standpoint of chemical and morphological changes. Consequently, the combination of active materials such as Si and Li2Si2O5 and inactive materials such as L(i)2O, Li2CO3, and organic compounds is suggested to result in outstanding properties as a lithium secondary battery anode.

    DOI

    Scopus

    30
    被引用数
    (Scopus)
  • Influence of the diffusion-layer thickness during electrodeposition on the synthesis of nano core/shell Sn-O-C composite as an anode of lithium secondary batteries

    Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    RSC ADVANCES   4 ( 51 ) 26872 - 26880  2014年  [査読有り]

     概要を見る

    Electrodeposition was conducted from an organic carbonate solvent via the potentiostatic technique through three consecutive steps in order to synthesise Sn-O-C composite, which delivered a discharge capacity of 596 mA h g of Sn-1 after 50 cycles. However, the composite anode suffered from a significantly low initial discharge capacity, delivering a discharge capacity of 79 mA h g of Sn-1 until the 5th cycle. It was deduced that the improbably low initial capacity was induced by the deposition of Li-rich compounds, which were formed by electrolyte decomposition accompanied by the reduction product of supporting electrolyte salts during the electrodeposition process, on the surface layer. In order to improve the poor initial capacity, we modified the chemical composition of the surface layer by means of implementing the agitation of the electrolyte during the deposition process. This gave rise to varying the diffusion-layer thickness during the deposition process due to the enhancement of convection by movement of the electrolyte itself. As a result, we achieved improvement of the initial discharge capacity, delivering 572 mA h g of Sn-1 at the 1st cycle and 586 mA h g of Sn-1 at the 50th cycle. It was revealed that the surface layer was composed of a decomposition product of the organic carbonate solvent. Furthermore, a smaller particle size of the Sn-O-C composite was obtained via electrolyte agitation, giving rise to homogeneous shell formation on the Sn compound core. Herein, we thoroughly examined the influence of varying diffusion-layer thickness during the deposition process on the properties of the Sn-O-C composites from an electrochemical standpoint.

    DOI

    Scopus

    20
    被引用数
    (Scopus)
  • Analysis of an Electrodeposition Mechanism of Sn-O-C Composite from an Organic Electrolyte

    Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   161 ( 7 ) D3025 - D3031  2014年  [査読有り]

     概要を見る

    Sn-O-C composites were electrodeposited using organic carbonate solvents and their electrochemical mechanism was thoroughly investigated to achieve desired anode performances, such as high capacity and cycle durability for lithium secondary batteries. Cyclic voltammetry study clarified the multiple stages of electrochemical mechanism during the Sn-O-C composite deposition process. It was revealed that Sn deposition, decomposition of organic electrolytes, and reaction between Li+ and deposited Sn were consecutively carried out. X-ray photoelectron spectroscopy and field emission scanning electron microscopy were performed to characterize how each stage contributes to the formation of the Sn-O-C composite. The results showed increase in metallic Sn composition and dense coating with fine particle sizes with a higher overpotential stage. Afterward, different Sn-O-C composite anodes were prepared by varying charge quantities passing through each deposition stage and their electrochemical performances as anode materials were investigated. Discharge capacities were obtained from the lowest value of 33 mAh g of Sn-1 to the highest value of 429 mAh g of Sn-1 at the 100th cycle by varying deposition conditions. Consequently, it was suggested that anode performance was significantly influenced by an electrodeposition process consisting of three consecutive stages with different overpotential regions and reactions of Li ion with deposited Sn. (C) 2014 The Electrochemical Society. All rights reserved.

    DOI

    Scopus

    8
    被引用数
    (Scopus)
  • New Analysis of Electrochemical Impedance Spectroscopy for Lithium-ion Batteries

    Tetsuya Osaka, Hiroki Nara, Daikichi Mukoyama, Tokihiko Yokoshima

    JOURNAL OF ELECTROCHEMICAL SCIENCE AND TECHNOLOGY   4 ( 4 ) 157 - 162  2013年12月  [査読有り]

     概要を見る

    First of all, we express our deepest sympathies for the passing of Professor Su-Moon Park. In the present paper, an electrochemical impedance spectroscopy (EIS), which Professor Su-Moon Park also used frequently for the investigation of electroconducting polymer, is introduced as a recent evaluation tool for a commercially available lithium-ion battery (LIB). The paper surveys how to design equivalent circuits while explaining physical and chemical phenomena in the LIB and how to get more accurate impedance spectra with varying the measuring temperatures. Additionally, a square current EIS (SC-EIS) technique, which we have suggested, is introduced for the larger LIB system as a promising technique for the future.

    DOI

  • Sn-O-C composite anode for Li secondary battery synthesized by an electrodeposition technique using organic carbonate electrolyte

    Toshiyuki Momma, Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Ayano Toyoda, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   242   527 - 532  2013年11月  [査読有り]

     概要を見る

    The Sn-O-C composite anode for the Li secondary battery was synthesized by electrodeposition using an organic carbonate solvent. The composite of Sn with organic/inorganic compounds was prepared by the simultaneous reaction of the reduction of Sn2+ ions and electrolysis of the mixture of ethylene carbonate and propylene carbonate. The galvanostatic potential transients for the electrodeposition of the Sn-O-C composite indicate that multiple steps of reactions corresponding to the electrochemical reduction of the tin precursor and the decomposition of organic solvents are involved. The morphology, crystalline structure and chemical composition of the as-deposited Sn-O-C composite anode were characterized to elucidate the mechanism of the synthesis of the buffering matrix enduring volume expansion.
    The electrochemical behavior of the Sn-O-C composite anode was investigated by cyclic voltammetry and galvanostatical charge/discharged tests. The discharge capacity of 465 mAh (g of Sn)(-1) was obtained at the 100th cycle showing 80% of the capacity retention after the 100th cycle. The discharge capacity was stable after the 50th cycle, where the phase transformation of the Sn element from Sn to Li0.4Sn at the discharged state was found. (C) 2013 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    13
    被引用数
    (Scopus)
  • Structural analysis of highly durable SiOC composite anode prepared by electrodeposition for lithium secondary batteries

    Hiroki Nara, Tokihiko Yokoshima, Mitsutoshi Otaki, Toshiyuki Momma, Tetsuya Osaka

    Electrochimica Acta   110   402 - 8  2013年  [査読有り]

     概要を見る

    The structure of the highly durable silicon-based anode prepared by electrodeposition was investigated for volume change and chemical structure. With repeated charge-discharge cycles, the volume change resulting from the anode film thickness decreased, and, after 100 cycles, essentially no difference was observed between the charged and discharged states. The buffering effect of the volume change was considered to be achieved by the formation of Li 2O, Li2CO3, and lithium silicates such as Li4SiO4, whose existence were supported by STEM, EELS, and XPS analyses. From the structural analyses, the main reactions related to the capacity of the silicon-based anode were considered to be the formation of LixSi and Li2Si2O5. LixSi and Li2Si2O5 can be delithiated into Si and SiO2, respectively. © 2013 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    6
    被引用数
    (Scopus)
  • Electrochemical impedance spectroscopy analysis for lithium-ion battery using Li4Ti5O12 anode

    Tao Hang, Daikichi Mukoyama, Hiroki Nara, Norio Takami, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   222   442 - 447  2013年01月  [査読有り]

     概要を見る

    The impedance of Li-ion battery using a Li4Ti5O12 (LTO) anode for high-power applications was measured at various depths of discharge and temperatures during charge discharge cycles. The measured impedance was interpreted with an equivalent circuit made up of anode and cathode, in which the cathode component was composed of two particle size factors. The values obtained for equivalent circuit elements by modeling were in good agreement with the results measured by other techniques, and indicated that the capacity fade of this Li-ion battery due to cycling is mainly caused by the increase of interfacial resistance and a decrease in the capacity of the LiCoO2 cathode. These results suggest that the cyclability of this LIB was improved by using an LTO anode, and show the validity of the equivalent circuit for interpreting the causes of capacity fade. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    91
    被引用数
    (Scopus)
  • Silicon composite thick film electrodeposited on a nickel micro-nanocones hierarchical structured current collector for lithium batteries

    Tao Hang, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   222   503 - 509  2013年01月  [査読有り]

     概要を見る

    Electrodeposition methods were developed for the fabrication of Si composite anodes with nickel micro-nanocones hierarchical structure (MHS) current collectors for Li secondary batteries. This unique structured nickel current collector is electrodeposited in a simple process to create a complex high surface area conductive substrate, as well as to enhance the interfacial strength between active materials and substrate during cyclic lithiation/delithiation. The MHS supported Si composite anode demonstrated outstanding Li+ storage properties with reversible capacity over 800 mAh g(-1) (600 mu Ah cm(-2)) after 100th cycle with superior retention of 99.6% per cycle. The improved performance of nickel MHS supported Si thick films indicate the potential for their application as electrode materials for high performance energy storage. 2012 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    39
    被引用数
    (Scopus)
  • Proposal of novel equivalent circuit for electrochemical impedance analysis of commercially available lithium ion battery

    Tetsuya Osaka, Toshiyuki Momma, Daikichi Mukoyama, Hiroki Nara

    JOURNAL OF POWER SOURCES   205   483 - 486  2012年05月  [査読有り]

     概要を見る

    To analyze impedance response of an electrochemical system, it is important to model the system with an adequate equivalent circuit. In the present work, an equivalent circuit was designed for the analysis of lithium ion batteries with the contributions of a variety of diffusion parameters resulting from the various particle sizes for the cathode and the solid-electrolyte interphase formed on the anode particles, as well as electrochemical reactions and inductive components. Residual errors resulting from the data fitting was investigated for a variety of equivalent circuits used. The electrochemical impedance of the electrodes in commercial lithium ion batteries at various states of charge was analyzed to evaluate the proposed circuit. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    141
    被引用数
    (Scopus)
  • Electrochemical Impedance Analysis on Degradation of Commercially Available Lithium Ion Battery during Charge-Discharge Cycling

    Daikichi Mukoyama, Toshiyuki Momma, Hiroki Nara, Tetsuya Osaka

    CHEMISTRY LETTERS   41 ( 4 ) 444 - 446  2012年04月  [査読有り]

     概要を見る

    The degradation of the commercial Li ion battery was analyzed by electrochemical impedance spectroscopy, where our previous proposed equivalent circuit was applied. The degradation with the cycling was clearly explained by the main parameters of capacitive and resistive components, i.e., it responded until 300 cycles to the decrease in capacitive component, while after 300 to 550 cycles to the increase in resistive component.

    DOI

    Scopus

    42
    被引用数
    (Scopus)
  • Electrodeposited novel highly durable SiOC composite anode for Li battery above several thousands of cycles

    Toshiyuki Momma, Seiichi Aoki, Hiroki Nara, Tokihiko Yokoshima, Tetsuya Osaka

    ELECTROCHEMISTRY COMMUNICATIONS   13 ( 9 ) 969 - 972  2011年09月  [査読有り]

     概要を見る

    A novel SiOC composite anode material for a Li battery was realized by electrochemical co-deposition of Si, C. and O elements. The composite was deposited by reduction of SiCl(4) in a propylene carbonate based solution. After the initiation process by reduction of the composite in a Li(+) containing electrolyte solution, the SiOC composite was found to be about 3.3 mu m in average thickness and the composite performed as a Li battery anode with over 1000 mAh g(-1) of Si for more than 2000 cycles, and moreover have continued for 7000 cycles with gradual degradation. (C) 2011 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    46
    被引用数
    (Scopus)
  • Effect of the atmosphere on chemical composition and electrochemical properties of solid electrolyte interface on electrodeposited Li metal

    Toshiyuki Momma, Hiroki Nara, Shinpei Yamagami, Chika Tatsumi, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   196 ( 15 ) 6483 - 6487  2011年08月  [査読有り]

     概要を見る

    Many efforts have been paid to realize the superior anodes for future Li batteries in either the dry Ar atmosphere or the dry air atmosphere. In this work, in order to clarify the effects of such atmospheres, the most reactive anodes of Li were freshly electrodeposited under the dry Ar or under the dry air condition. The Solid Electrolyte Interface (SEI) formed during the electrodeposition of Li anodes is revealed to have a different chemical composition and protective feature. The Li deposited under the dry air was revealed to have longer cycle life in the electrolyte than that deposited in Ar, even in the electrolyte containing ionic liquid. From the XPS results, the SEI formed in dry air is proved to be different from that formed in Ar gas atmospheres. that is, the SEI formed in dry air consists of Li(2)CO(3) and Li nitride. In order to improve the performance of the anodes, the atmosphere for the initial preparation of the anode/electrolyte interface should be tuned. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.

    DOI

    Scopus

    16
    被引用数
    (Scopus)
  • Nanoindentation and nanowear study of Sn and Ni-Sn coatings

    J. Chen, S. J. Bull, S. Roy, A. Kapoor, H. Mukaibo, H. Nara, T. Momma, T. Osaka, Y. Shacham-Diamand

    TRIBOLOGY INTERNATIONAL   42 ( 6 ) 779 - 791  2009年06月  [査読有り]

     概要を見る

    As potential high capacity anode materials for lithium ion batteries, the Sri and Ni-Sn alloy coatings have been investigated by many electrochemical researchers. However, their mechanical properties have not been extensively Studied, despite the fact that such anode films may fail mechanically during service. Thus, in this study nanoindentation and nanowear tests have been performed. Nanoindentation tests reveal that the ability to carry the load dramatically reduces in the Sri coating after one charge-discharge cycle which makes the plastic strain accumulation in the copper Substrate play a greater Contribution to crack formation and propagation in repeated charge-discharge cycling. Upon the nanoindentation analysis, it also shows that the pores formed by lithiation/delithiation can easily collapse at low loads. Furthermore, nanowear tests explore that the damage resistance of the Sn-Ni alloy film significantly improves after one charge-discharge cycle but it decreases in the Sri film after the same charge-discharge cycle; this explains why the degradation rate of the Ni-Sn alloy is slow after the first charge-discharge cycle and why the high capacity is maintained in further cycling. The links between the mechanical characterization and the degradation in charge-discharge cycling are also discussed. (c) 2008 Elsevier Ltd. All rights reserved.

    DOI

    Scopus

    27
    被引用数
    (Scopus)
  • Applications - Portable | Micro Hybrid Power System: Fuel Cells/Capacitors

    T. Momma, H. Nara, T. Osaka

    Encyclopedia of Electrochemical Power Sources     1 - 12  2009年01月

     概要を見る

    In this chapter, micro fuel cells fabricated by microelectromechanical system (MEMS) technology and hybrid power sources based on a combination of fuel cells and capacitors are introduced. These systems are new systems toward miniaturization of power sources. Significant efforts in developing micro (sub-watt) and portable (1-20 W) direct methanol fuel cell (DMFC) systems are being made, including developments of small fuel cells, such as micro fuel cells fabricated with MEMS technology. MEMS technology based on the manufacturing technology of semiconductor devices is a powerful tool to realize small devices. Examples reported to realize the DMFC configuration by MEMS technology, the so-called micro direct methanol fuel cells (μDMFCs), are introduced in this chapter. The hybrid power supply system based on fuel cells is an attractive power source; the utilization of fuel cells with the assistance of capacitor has the merit of realizing the power supply having the features of both fuel cell and capacitor, that is, a high power density and a high power output. In order to construct the hybrid power supply system, simulation of power output from the power supply, by varying the properties of capacitor and fuel cell, would be the introductory research. Typical assessments are described in this chapter.

    DOI

    Scopus

    2
    被引用数
    (Scopus)
  • Numerical simulation of DMFC-capacitor hybrid power supply system for small electronic devices

    Toshiyuki Momma, Hiroki Nara, Tetsuya Osaka

    ELECTROCHEMISTRY   76 ( 4 ) 270 - 275  2008年04月  [査読有り]

     概要を見る

    A simple numerical simulation of current flowing through electronic devices was examined for a hybrid power supply system composed of a DMFC and a capacitor connected in parallel. The simulation was investigated by representing a combination of ohmic resistance, charge transfer reaction resistance, mass transfer resistance and double layer capacitance of a DMFC as a simple ideal resistor, based on measured data when DMFC was generating electricity. The simulation result was found to agree with experimental measured current flowing through the DMFC and the capacitor, although a slight disagreement was observed because of the presence of ohmic resistance between circuit components. The simulation of DMFC-capacitor hybrid power supply system indicated the importance of the inner resistance of the capacitor. The hybrid simulation was also applied to a system assumed to consist of mu DMFC and micro electrochemical capacitor (MECC) system. The effect of applying a DC-DC converter to the system was indicated. The simulation allows to predict the degree of improvement required without performing actual fabrication of mu DMFC and MECC.

    DOI

    Scopus

    1
    被引用数
    (Scopus)
  • Cycle and rate properties of mesoporous tin anode for lithium ion secondary batteries

    Hiroki Nara, Yoshiki Fukuhara, Azusa Takai, Masaki Komatsu, Hitomi Mukaibo, Yusuke Yamauchi, Toshiyuki Momma, Kazuyuki Kuroda, Tetsuya Osaka

    CHEMISTRY LETTERS   37 ( 2 ) 142 - 143  2008年02月  [査読有り]

    担当区分:筆頭著者

     概要を見る

    A mesoporous Sn anode was electrodeposited in the presence of lyotropic liquid crystals made of nonionic surfactants. The introduction of mesoporous structure was effective for the accommodation of volume change of Sn during charge and discharge cycling of Li ions. The discharge capacity of the mesoporous Sn anode at 1 C rate was as high as 425 mA h g(-1) at the 100th cycle, and that was as high as 320 mA It g(-1) at the 100th cycle even though at 5 degrees C rate.

    DOI

    Scopus

    35
    被引用数
    (Scopus)
  • Mechanical analysis and in situ structural and morphological evaluation of Ni-Sn alloy anodes for Li ion batteries

    J. Chen, S. J. Bull, S. Roy, H. Mukaibo, H. Nara, T. Momma, T. Osaka, Y. Shacham-Diamand

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   41 ( 2 ) 025302  2008年01月  [査読有り]

     概要を見る

    In lithium ion batteries, it has previously been shown that Ni-Sn thin film anodes containing 62 at.% Sn show outstanding electrochemical characteristics, e. g. good capacity and endurance, during charge-discharge cycling. However, their mechanical response, which is likely related to their lifetime in service, has so far received relatively little attention. To address this, nanoindentation and nanowear techniques have been used to characterize the mechanical properties of thin Ni-Sn films electrodeposited on a copper substrate. In situ morphology analysis together with in situ stress measurement has been performed to assess the properties of Ni-Sn thin film anodes during electrochemical cycling. The change in mechanical properties, residual stress and fracture behaviour of the anodes is related to the phase changes which occur during charge-discharge cycling. The correlation between the mechanical properties of the films and their charge-discharge characteristics serves as a useful indicator for optimized design of a Sn-based intermetallic anode film for lithium ion secondary batteries.

    DOI

    Scopus

    26
    被引用数
    (Scopus)
  • Characteristics of interpenetrated polymer network system made of polyethylene oxide-LiBF4 complex and polystyrene as the electrolyte for lithium secondary battery

    T Momma, H Ito, H Nara, H Mukaibo, S Passerini, T Osaka

    ELECTROCHEMISTRY   71 ( 12 ) 1182 - 1186  2003年12月  [査読有り]

     概要を見る

    We propose a polymer blending method for preparing the PEO (polyethylene oxide)-LiBF4 complex electrolyte for lithium secondary battery applying to the IPN (interpenetrated polymer network) gel electrolyte. The polymer blend mixture of PEO-PS (polystyrene) -LiBF4 was prepared as a film by the hot-pressing method. The resulting IPN film was plasticized with the electrolyte solution of 0.5 M LiBF4/EC (ethylene carbonate) -PC (propylene carbonate) (I : I vol.), in which the formation of PEO-LiBF4 complex was confirmed by the Raman spectroscopy. The basic properties as an electrolyte of Li metal batteries, i.e., ionic conductivity, chemical stability at the polymer gel electrolyte/lithium metal interface, and charge-discharge performance of the Li/(PEO-LiBF4/PS) gel electrolyte/LiCoO2 cell were studied and discussed.

    DOI

    Scopus

    6
    被引用数
    (Scopus)

▼全件表示

書籍等出版物

  • 蓄電システム用二次電池の高機能・高容量化と安全対策 : 材料・構造・量産技術、日欧米安全基準の動向を踏まえて

    逢坂 哲彌, 菅原 秀一, 西野 敦, 門間 聰之, 横島 時彦, 向山 大吉, 奈良 洋希

    エヌ・ティー・エス  2015年 ISBN: 9784860434083

  • エヌ・ティー・エス(編), 「高性能蓄電池-設計基礎研究から開発・評価まで-」, 1編2章 「電池設計支援のための先端電気化学的評価方法」 pp. 171-183.

    逢坂哲彌, 門間聰之, 奈良洋希

    壮光舎印刷  2009年09月 ISBN: 9784860432638

  • J. Garche, C. K. Dyer, P. T. Moseley, Z. Ogumi, D. A. J. Rand, B. Scrosati (Eds.),Encyclopedia of Electrochemical Power Sources, “Micro Hybrid Power System: Fuel Cells/Capacitors”

    T. Momma, H. Nara, T. Osaka

    Elsevier  2009年 ISBN: 9780444535320

講演・口頭発表等

  • 参照電極入ラミネート型リチウムイオン二次電池の基礎解析

    発表年月: 2010年11月

  • Feasibility of diblock copolymer ion gel electrolyte used BMPFSA as plasticizer

    発表年月: 2010年09月

  • Li二次電池用電解析出Si負極の作製条件の検討

    発表年月: 2010年09月

  • Development of LIB and its New Role in Future Society

    発表年月: 2010年09月

  • Impedance Analysis for Detection of Deterioration level on Polymer Electrolyte Fuel Cells

    発表年月: 2010年08月

  • Compatibility of Ionic Liquids to Rechargeable Li Batteries

    発表年月: 2010年06月

  • Gel-polymer Composite Electrolyte for Perspective Li-metal Secondary Battery Systems

    発表年月: 2010年06月

  • Application of Ionic Liquid to Electrochemical Nanosystems

    発表年月: 2010年06月

  • Electrodeposited Sn from Organic Electrolyte for Li ion Battery Anode

    発表年月: 2010年06月

  • BMPFSI適用によるリチウム二次電池用ブロックコポリマーイオンゲル電解質の改良

    発表年月: 2010年03月

  • 有機電解液中で電析したSiのLi二次電池用負極としての電気化学的特性評価

    発表年月: 2010年03月

  • R & D for Future Li Batteries by means of Electrochemical Nanotechnology

    発表年月: 2009年11月

  • インピーダンス応答変化の解析によるカソードPt触媒の劣化評価

    発表年月: 2009年11月

  • リチウム二次電池負極を目的とし有機電解液中で電析したSn電極の基礎特性評価

    発表年月: 2009年11月

  • Electrochemical Study of SEI of Metallic Li Anode with Improved Cycle Life by Sulfonyl Additives

    発表年月: 2009年10月

  • イオン液体BMPTFSIを用いたリチウム二次電池用ジブロックコポリマーゲル電解質の評価

    発表年月: 2009年09月

  • スルホニル系有機添加剤によるリチウム溶解析出サイクルへの影響

    発表年月: 2009年09月

  • Thermal and Electrochemical Stability of Diblock Copolymer Gel Electrolyte Containing BMPTFSI or EC-PC as Plasticizer for Lithium Secondary Batteries

    発表年月: 2009年08月

  • Nano-technological Approach to Next Generation Materials for Energy Conversion

    発表年月: 2009年08月

  • リチウム二次電池用ジブロックコポリマ ー電解質可塑剤へのイオン液体適用の可能性

    発表年月: 2009年03月

  • スルホニル系有機添加剤のリチウム金属負極への影響

    発表年月: 2009年03月

  • 1M LiTFSI / BMPTFSI中でのNiSn合金負極特性と初期電流密度依存

    発表年月: 2008年11月

  • Characterization of SEI Films Formed in Different Experimental Atmosphere on Lithium in the Presence of Ionic Liquid

    発表年月: 2008年11月

  • Feasibility of Oxide Free NiSn Alloy Powder for Lithium Secondary Batteries

    発表年月: 2008年09月

  • Application of mesoporous Sn electrode for lithium secondary batteries

    発表年月: 2008年03月

  • In-situ応力測定を用いたリチウム二次電池用メソポーラスSn負極の充放電時の評価

    発表年月: 2008年03月

  • TFSIアニオン系イオン液体を添加した有機電解液中でのリチウム金属負極特性に与える酸素溶存の効果

    発表年月: 2007年11月

  • 表面酸化物制御によるリチウム二次電池用NiSn合金粉末負極の改良

    発表年月: 2007年11月

  • Cycle property of mesoporous Sn anode for lithium ion secondary batteries

    発表年月: 2007年10月

  • リチウムイオン二次電池用電析Sn負極へのメソポーラス構造の導入とその充放電特性

    発表年月: 2007年09月

  • リチウム二次電池用ジブロックポリマーゲル電解質の膜特性改良および評価

    発表年月: 2007年03月

  • DMFC電解質内での物質移動による電圧損失を考慮したDMFC・キャパシタハイブリッドシステムの作動シミュレーション

    発表年月: 2006年11月

  • リオトロピック液晶相を用いたリチウムイオン二次電池用電析Sn系負極材料の作製

    発表年月: 2006年11月

  • 小型電子機器用燃料電池・キャパシタハイブリッドシステムの作動シミュレーション

    発表年月: 2006年04月

  • Application of diblockpolymer gel electrolyte having micro phase separation structure to lithium secondary batteries

    発表年月: 2005年09月

  • Gel electrolyte having micro phase separation structure for lithium secondary batteries

    発表年月: 2005年06月

  • ジブロックポリマーゲル電解質のリチウム二次電池への応用

    発表年月: 2005年04月

  • Preparation of Gel Electrolyte using Self-Assembling Diblockpolymer for Lithium Secondary Battery

    発表年月: 2004年10月

  • ジブロックポリマーの自己組織化を用いたリチウム 二次電池用ゲル電解質の作製

    発表年月: 2004年03月

  • PEO-LiX錯体を用いたポリマーブレンドのリチウム二次電池用電解質特性

    発表年月: 2003年04月

  • PEO-LiXとPSの複合によるポリマーブレンドゲル電解質

    発表年月: 2002年09月

▼全件表示

Misc

▼全件表示

産業財産権

▼全件表示

 

担当経験のある科目(授業)

  • 自然といのちA(社会とエネルギー)

    東京家政大学  

    2020年10月
    -
    継続中
     

  • エネルギーデバイス特論

    早稲田大学大学院  

    2019年
    -
    継続中
     

  • ナノ電気化学特論

    早稲田大学大学院  

    2014年04月
    -
    継続中
     

  • 新エネルギー技術

    中央大学  

    2020年04月
    -
    2020年09月
     

  • 新エネルギー技術

    中央大学  

    2011年04月
    -
    2011年09月
     

  • 無機工業化学

    早稲田大学  

    2010年
     
     
     

▼全件表示