2021/12/07 更新

写真a

タカハシ マサクニ
髙橋 勝國
Takahashi Masakuni
所属
自然科学学域 助教
職名
助教
外部リンク

学位

  • 人間・環境学 ( 2021年3月 )

研究分野

  • ナノテク・材料 / 無機物質、無機材料化学

学歴

  • 京都大学   Graduate School of Human and Environmental Studies   Department of Interdisciplinary Environment

    - 2021年3月

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経歴

  • 岡山大学   大学院自然科学研究科   助教

    2021年4月 - 現在

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論文

  • High Ionic Conductivity of Liquid-Phase-Synthesized Li<inf>3</inf>PS<inf>4</inf>Solid Electrolyte, Comparable to That Obtained via Ball Milling

    Kentaro Yamamoto, Seunghoon Yang, Masakuni Takahashi, Koji Ohara, Tomoki Uchiyama, Toshiki Watanabe, Atsushi Sakuda, Akitoshi Hayashi, Masahiro Tatsumisago, Hiroyuki Muto, Atsunori Matsuda, Yoshiharu Uchimoto

    ACS Applied Energy Materials   4 ( 3 )   2275 - 2281   2021年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Recently, several sulfide solid electrolytes have been synthesized by liquid-phase synthesis for the commercialization of all-solid-state batteries. Unfortunately, the ionic conductivity for most of these electrolytes is unsatisfactory compared to that of solid electrolytes synthesized by conventional ball milling. This problem is attributed to different mechanisms between the liquid phase and the solid phase in reaction and formation. However, to the best of our knowledge, the effect of the solvent on the ionic conductivity of solid electrolytes has not been extensively investigated, although the identification of these properties is a key point in understanding the liquid-phase synthesis. Herein, the correlation between ionic conductivity and crystallinity originating from the solvents used has been investigated. As a result, the ionic conductivity of the electrolyte was found to be strongly dependent on polarity (δP) with low crystallinity. The highest ionic conductivity (5.09 × 10-4 S cm-1 at 25 °C) was obtained using butyl acetate, which exhibited the lowest δP. Moreover, the highest ionic conductivity of Li3PS4 produced by liquid-phase synthesis using butyl acetate was very comparable to that obtained by ball milling (5.14 × 10-4 S cm-1).

    DOI: 10.1021/acsaem.0c02771

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  • Improvement of lithium ionic conductivity of Li<inf>3</inf>PS<inf>4</inf> through suppression of crystallization using low-boiling-point solvent in liquid-phase synthesis

    Masakuni Takahashi, Seunghoon Yang, Kentaro Yamamoto, Koji Ohara, Nguyen Huu Huy Phuc, Toshiki Watanabe, Tomoki Uchiyama, Atsushi Sakuda, Akitoshi Hayashi, Masahiro Tatsumisago, Hiroyuki Muto, Atsunori Matsuda, Yoshiharu Uchimoto

    Solid State Ionics   361   2021年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    Liquid-phase synthesis for solid electrolytes has received considerable attention owing to its shape control, with the potential to produce particles easily on a large scale, and its low cost and energy consumption. However, solid electrolytes prepared through liquid-phase synthesis have been shown to have lower ionic conductivity than solid electrolytes prepared through the mechanical milling method. Recently, following various efforts, our group found that the crystallinity and remaining intermediate are the reasons for the low ionic conductivity of these materials. By using tetrahydrofuran (THF), we successfully improved the ionic conductivity of Li PS to 1.85 × 10 S cm at 25 °C, higher than that afforded by ethyl propionate, which was reported to produce the highest ionic conductivity among the solvents used for liquid-phase synthesis. High-energy X-ray diffraction (XRD) measurements coupled with pair distribution function (PDF) analysis were employed to analyze the synthesized materials in order to determine why the ionic conductivity was higher than that of a sample prepared using ethyl propionate. The PDF analysis revealed that the crystallization of Li PS can be suppressed using THF, which has a lower boiling point than ethyl propionate. Moreover, it was revealed that the solvent could not be removed completely when the material has an amorphous structure, and thus, the ionic conductivity was lower than that of a material prepared using the solid-phase synthesis method. 3 4 3 4 −4 −1

    DOI: 10.1016/j.ssi.2021.115568

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  • Investigation of the Suppression of Dendritic Lithium Growth with a Lithium-Iodide-Containing Solid Electrolyte

    Masakuni Takahashi, Toshiki Watanabe, Kentaro Yamamoto, Koji Ohara, Atsushi Sakuda, Takuya Kimura, Seunghoon Yang, Koji Nakanishi, Tomoki Uchiyama, Masao Kimura, Akitoshi Hayashi, Masahiro Tatsumisago, Yoshiharu Uchimoto

    Chemistry of Materials   33 ( 13 )   4907 - 4914   2021年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    All-solid-state lithium batteries that use lithium metal as the anode have extremely high energy densities. However, for lithium metal anodes to be used, lithium dendrite formation must be addressed. Recently, the addition of lithium iodide (LiI) to sulfide solid electrolytes was found to suppress lithium dendrite formation. It is unclear whether the cause of this suppression is the improvement of the ionic conductivity of the solid electrolyte itself or the electrochemical properties of the lithium metal/solid electrolyte interface. In this study, the cause of the suppression was quantitatively elucidated. The effect of the interphase on the dendrite growth of doping LiI into Li3PS4 was determined using X-ray absorption spectroscopy and X-ray computed tomography measurements. The results revealed that LiI-doped Li3PS4 suppressed the dendrite formation by maintaining the interface due to inhibition of the reductive decomposition of Li3PS4. In addition, annealed LiI-doped Li3PS4 showed a greater dendrite suppression ability as the ionic conductivity increased. From these results, we not only found that the physical properties of the lithium metal/solid electrolyte interface and the bulk ionic conductivity contribute to lithium dendrite suppression but also quantitatively determined the proportions of the contributions of these two factors.

    DOI: 10.1021/acs.chemmater.1c00270

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  • Substrate-dependent proton transport and nanostructural orientation of perfluorosulfonic acid polymer thin films on Pt and carbon substrate

    Xiao Gao, Kentaro Yamamoto, Tomoyasu Hirai, Noboru Ohta, Tomoki Uchiyama, Toshiki Watanabe, Masakuni Takahashi, Naoki Takao, Hideto Imai, Seiho Sugawara, Kazuhiko Shinohara, Yoshiharu Uchimoto

    Solid State Ionics   357   2020年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    The electrochemical reactions occur on the carbon-supported platinum covered by a proton conducting polymer electrolyte. Thus, it is important to clarify the correlation between proton conductivity and morphology of the polymer electrolyte on Pt or carbon. In this study, the properties of thin films (50–200 nm) of Nafion®, which is the typical polymer electrolyte, were investigated on platinum and carbon substrates. Grazing-incidence small/wide angle X-ray scattering and electrochemical impedance spectroscopy were used to extract morphological and proton transport information. Self-designed interdigitated array electrodes were utilized to test and compare the proton conductivity on the Pt and carbon substrates. Based on the results, the difference in anisotropic behavior of Nafion thin films on each substrate were explored, which exhibit that the proton conductivity of Pt-supported Nafion thin films has more well defined hydrophilic domain structure than that of carbon supported thin films along in-plane direction and while it showed the opposite trend in the out-of-plane direction. These datasets and analyses represented a thorough study of the behavior of Nafion thin films on model substrates of interest, i.e., Pt catalyst/carbon electrodes. These results are expected to further understanding the difference in term of proton transport pathway.

    DOI: 10.1016/j.ssi.2020.115456

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  • Observation of Liquid Phase Synthesis of Sulfide Solid Electrolytes Using Time-Resolved Pair Distribution Function Analysis

    Koji Ohara, Naoya Masuda, Hiroshi Yamaguchi, Atsushi Yao, Satoshi Tominaka, Hiroki Yamada, Satoshi Hiroi, Masakuni Takahashi, Kentaro Yamamoto, Toru Wakihara, Yoshiharu Uchimoto, Futoshi Utsuno, Shigeru Kimura

    Physica Status Solidi (B) Basic Research   257 ( 11 )   2020年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Time-resolved pair distribution function (PDF) analysis is performed to clarify the formation mechanism of Li PS sulfide solid electrolytes in liquid phase synthesis with acetonitrile (AN), tetrahydrofuran (THF), and ethyl acetate (EA) solvents. This aims to clarify the relationship between their formations and lithium ionic conductivity. A complex is formed between the precursor of the sulfide solid electrolyte and each solvent during the liquid phase synthesis. The ratio of the solvent to the electrolyte is 3.03 in THF solution. The formation speed of precursors of sulfide solid electrolytes increases in the order AN < THF < EA solution, which is the same order as the lithium ionic conductivity. Thus, the correlation between the ionic conductivity and the formation rate of the precursor of the sulfide solid electrolyte might be related to the stability of the complex formed between Li PS and the solvent during liquid phase synthesis. 3 4 3 4

    DOI: 10.1002/pssb.202000106

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  • Synthesis of Sulfide Solid Electrolytes through the Liquid Phase: Optimization of the Preparation Conditions

    Kentaro Yamamoto, Masakuni Takahashi, Koji Ohara, Nguyen Huu Huy Phuc, Seunghoon Yang, Toshiki Watanabe, Tomoki Uchiyama, Atsushi Sakuda, Akitoshi Hayashi, Masahiro Tatsumisago, Hiroyuki Muto, Atsunori Matsuda, Yoshiharu Uchimoto

    ACS Omega   5 ( 40 )   26287 - 26294   2020年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    All-solid-state lithium batteries using inorganic sulfide solid electrolytes have good safety properties and high rate capabilities as expected for a next-generation battery. Presently, conventional preparation methods such as mechanical milling and/or solid-phase synthesis need a long time to provide a small amount of the product, and they have difficult in supplying a sufficient amount to meet the demand. Hence, liquid-phase synthesis methods have been developed for large-scale synthesis. However, the ionic conductivity of sulfide solid electrolytes prepared via liquid-phase synthesis is typically lower than that prepared via solid-phase synthesis. In this study, we have controlled three factors: (1) shaking time, (2) annealing temperature, and (3) annealing time. The factors influencing lithium ionic conductivity of Li3PS4 prepared via liquid-phase synthesis were quantitatively evaluated using high-energy X-ray diffraction (XRD) measurement coupled with pair distribution function (PDF) analysis. It was revealed from PDF analysis that the amount of Li2S that cannot be detected by Raman spectroscopy or XRD decreased the ionic conductivity. Furthermore, it was revealed that the ionic conductivity of Li3PS4 is dominated by other parameters, such as remaining solvent in the sample and high crystallinity of the sample.

    DOI: 10.1021/acsomega.0c04307

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  • Observation of subsurface structure of Pt/C catalyst using pair distribution function and simple modeling techniques

    Masakuni Takahashi, Koji Ohara, Kentaro Yamamoto, Tomoki Uchiyama, Hajime Tanida, Takanori Itoh, Hideto Imai, Seiho Sugawara, Kazuhiko Shinohara, Yoshiharu Uchimoto

    Bulletin of the Chemical Society of Japan   93 ( 1 )   37 - 42   2020年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    The correlation between the PtPt interatomic distance of a Pt/C catalyst and the specific activity of the oxygen reduction reaction is discussed. Total X-ray scattering measurement coupled with pair distribution function (PDF) analysis was performed to obtain subsurface information of the Pt/C catalyst, which can obtain a much longer interatomic distance than X-ray absorption fine structure (XAFS) measurement. The subsurface structure of the catalyst was previously discussed on the basis of simulations with three-dimensional complex models. In this study, the subsurface structure of PtPt bonds in the catalyst could be easily obtained from experimental data by simple model fitting using the PDF. Results based on XAFS measurement showed no correlation with the specific activity. In contrast, the obtained PtPt interatomic distances in the subsurface using PDF showed a strong negative correlation with the specific activity as in a previous study.

    DOI: 10.1246/bcsj.20190256

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  • Time-resolved pair distribution function analysis of disordered materials on beamlines BL04B2 and BL08W at SPring-8

    Koji Ohara, Satoshi Tominaka, Hiroki Yamada, Masakuni Takahashi, Hiroshi Yamaguchi, Futoshi Utsuno, Takashi Umeki, Atsushi Yao, Kengo Nakada, Michitaka Takemoto, Satoshi Hiroi, Naruki Tsuji, Toru Wakihara

    Journal of Synchrotron Radiation   25 ( 6 )   1627 - 1633   2018年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INT UNION CRYSTALLOGRAPHY  

    A dedicated apparatus has been developed for studying structural changes in amorphous and disordered crystalline materials substantially in real time. The apparatus, which can be set up on beamlines BL04B2 and BL08W at SPring-8, mainly consists of a large two-dimensional flat-panel detector and high-energy X-rays, enabling total scattering measurements to be carried out for time-resolved pair distribution function (PDF) analysis in the temperature range from room temperature to 873 K at pressures of up to 20 bar. For successful time-resolved analysis, a newly developed program was used that can monitor and process two-dimensional image data simultaneously with the data collection. The use of time-resolved hardware and software is of great importance for obtaining a detailed understanding of the structural changes in disordered materials, as exemplified by the results of commissioned measurements carried out on both beamlines. Benchmark results obtained using amorphous silica and demonstration results for the observation of sulfide glass crystallization upon annealing are introduced.

    DOI: 10.1107/S1600577518011232

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MISC

  • Pt/CおよびPt/Pd/Cコアシェル触媒上における酸素還元反応の温度依存性

    内山智貴, LIU Chen, 堀江悠希, 高裕太郎, 高橋勝國, 山本健太郎, 谷田肇, 高尾直樹, 今井英人, 横山浩司, 菅原生豊, 篠原和彦, 内本喜晴

    電解技術討論会(ソーダ工業技術討論会)講演要旨集   41st   2017年

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  • 白金触媒の高エネルギーX線回折を用いた二体相関関数解析

    高橋勝國, 尾原幸治, 内山智貴, 山本健太郎, 谷田肇, 今井英人, 横山浩司, 大木真里亜, 菅原生豊, 篠原和彦, 内本喜晴

    電解技術討論会(ソーダ工業技術討論会)講演要旨集   41st   2017年

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  • 高エネルギーX線回折・X線吸収分光・TEMを相補的に用いた燃料電池用Ptカソード触媒の劣化機構解析

    高橋勝國, 尾原幸治, 内山智貴, 中本康介, 山本健太郎, 谷田肇, 今井英人, 横山浩司, 大木真里亜, 菅原生豊, 篠原和彦, 内本喜晴

    電池討論会講演要旨集   58th   2017年

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  • オペランド斜入射X線小角散乱および軟X線吸収分光を用いたアイオノマー/電極界面におけるアイオノマー構造

    GAO Xiao, 高橋勝国, LIU Chen, 山本健太郎, 内山智貴, 中本康介, 谷田肇, 高尾直樹, 松本匡史, 今井英人, 与儀千尋, 横山浩司, 菅原生豊, 篠原和彦, 大木真里亜, 内本喜晴

    電池討論会講演要旨集   58th   2017年

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  • 放射光X線回折を用いたPt/C触媒の劣化解析

    高橋勝國, 尾原幸治, 山本健太郎, 折笠有基, 谷田肇, 今井英人, 横山浩司, 大木真里亜, 菅原生豊, 篠原和彦, 内本喜晴

    電池討論会講演要旨集   57th   2016年

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担当授業科目

  • 実践応用化学 (2021年度) 前期  - その他

  • 工学基礎実験実習 (2021年度) 1・2学期  - 火5,火6,火7,火8

  • 工学基礎実験実習 (2021年度) 1・2学期  - 火5,火6,火7,火8

  • 工学基礎実験実習 (2021年度) 1・2学期  - 火5,火6,火7,火8

  • 応用化学ゼミナール1 (2021年度) 前期  - その他

  • 応用化学ゼミナール2 (2021年度) 後期  - その他

  • 応用化学特別研究 (2021年度) 通年  - その他

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