Updated on 2025/01/05

写真a

 
NARA, Hiroki
 
Affiliation
Faculty of Science and Engineering, Waseda Research Institute for Science and Engineering
Job title
Researcher(Associate Professor)
Degree
PhD in Engineering ( Waseda University )

Research Experience

  • 2023.08
    -
    Now

    Waseda University   Research Institute for Science and Engineering   Researcher   Associate Professor

  • 2020.04
    -
    Now

    Tokyo Kasei University   Part-time Lecturer

  • 2023.04
    -
    2023.07

    Waseda University   Research Organization for Nano & Life Innovation   Researcher   Associate Professor

  • 2022.04
    -
    2023.03

    National Institute for Materials Science   World Premier International Research Center Materials Nanoarchitectonics   Special Researcher

  • 2022.04
    -
    2023.03

    JST-ERATO   Yamauchi Materials Space-Tectonics   Group Leader

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Education Background

  •  
    -
    2008

    Waseda University   Graduate School, Division of Science and Engineering   Applied Chemistry  

  •  
    -
    2005

    Waseda University   Graduate School, Division of Science and Engineering   Applied Chemistry  

  •  
    -
    2003

    Waseda University   Faculty of Science and Engineering   Applied Chemistry  

Committee Memberships

  • 2023.04
    -
    Now

    電気化学会  広報委員

  • 2021.04
    -
    Now

    電気化学会  代議員

  • 2019.04
    -
    Now

    電極ナノ構造・デバイス研究会  運営幹事

  • 2015.04
    -
    Now

    電気化学会  関東支部幹事

Professional Memberships

  • 2019.04
    -
     

    電極ナノ構造・デバイス研究会

  •  
     
     

    International Society of Electrochemistry

  •  
     
     

    Electrochemical Society

  •  
     
     

    Electrochemical Society of Japan

  •  
     
     

    電池技術委員会

Research Areas

  • Energy chemistry   Lithium-ion battery, Fuel cell, Electrochemical impedance spectroscopy

Research Interests

  • Applied Electrochemistry

Awards

  • Nano technology forum award

    2021.09   Research Organization for Nano & Life Innovation, Waseda University  

    Winner: Hiroki NARA

  • 国際研究集会出張助成

    2019   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

    Winner: 奈良洋希

  • 科学技術研究助成

    2017   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

    Winner: 奈良洋希

  • アルミニウム研究助成事業

    2017   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

    Winner: 奈良洋希

  • 研究費助成

    2011   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

    Winner: 奈良洋希

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Papers

  • 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  2022.09  [Refereed]

    Authorship:Corresponding author

     View Summary

    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

    148
    Citation
    (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  2018.09  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    Lithium-ion batteries are required to have high-power density, that is to reduce impedance, for use in electric vehicles. This paper focuses on interfacial resistance between the cathode layer (CL) and the current collector (CC) observed at high frequencies, which is generally attributed to a resistance of surface film like SEI. To investigate the interfacial resistance systematically, different interfaces between the CL and the CC were prepared by controlling the press rate for the cathode preparation, or by introducing a carbon under-coating layer (CUL), followed by electrochemical impedance spectroscopy (EIS). The interfacial resistance between the CL and the CC prepared with an insufficient press rate or without a CUL was extremely high for the entire cathode. From the cathode cross-sectional observation, it was observed that this high interfacial resistance was caused by low contact rate at the interface. Using a pouch-type symmetric cell, EIS revealed that the interfacial resistance is attributed to electric resistance, that is, contact resistance at the interface. Also, the other resistances were attributed to be the ionic resistance of the electrolyte and pores in the cathode, and the charge transfer resistance of the cathode. Furthermore, the effectiveness of the CUL was shown to decrease the cathode impedance.

    DOI

    Scopus

    91
    Citation
    (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  2017.07  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    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

    52
    Citation
    (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  [Refereed]

    Authorship:Lead author

     View Summary

    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

    63
    Citation
    (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  2013.12  [Refereed]

     View Summary

    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

    34
    Citation
    (Scopus)

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Books and Other Publications

  • テクノロジー・ロードマップ : 2023-2032

    出川, 通( Part: Contributor)

    日経BP社  2023.01 ISBN: 9784296200955

  • テクノロジー・ロードマップ : 2021-2030

    出川, 通( Part: Contributor)

    日経BP社  2020.11 ISBN: 9784296107445

  • 電気化学・インピーダンス測定のデータ解析手法と事例集

    技術情報協会( Part: Joint author)

    技術情報協会  2018.12 ISBN: 9784861047305

  • 次世代電池用電極材料の高エネルギー密度、高出力化

    技術情報協会( Part: Joint author)

    技術情報協会  2017.11 ISBN: 9784861046858

  • テクノロジー・ロードマップ : 2018-2027

    出川, 通( Part: Contributor)

    日経BP社  2017 ISBN: 9784822258627

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Presentations

  • 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

    Presentation date: 2010.11

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

    Presentation date: 2010.09

  • Li二次電池用電解析出Si負極の作製条件の検討

    Presentation date: 2010.09

  • Development of LIB and its New Role in Future Society

    Presentation date: 2010.09

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

    Presentation date: 2010.08

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Misc

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Industrial Property Rights

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Teaching Experience

  • 自然といのちA(社会とエネルギー)

    東京家政大学  

    2020.10
    -
    Now
     

  • エネルギーデバイス特論

    早稲田大学大学院  

    2019
    -
    Now
     

  • ナノ電気化学特論

    早稲田大学大学院  

    2014.04
    -
    Now
     

  • 新エネルギー技術

    中央大学  

    2020.04
    -
    2020.09
     

  • 新エネルギー技術

    中央大学  

    2011.04
    -
    2011.09
     

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