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説明:

Extensive research efforts have been dedicated to Li-excess compounds with anionic redox reaction as potential high-capacity positive electrode materials for Li-ion battery applications. The origin of activation on anionic redox is still under debate, and a unified understanding is necessary, especially for sulfide-based compounds without conductive d electrons. Herein, joint experimental and theoretical study is conducted for Li-excess and stoichiometric compounds with different crystal structures, cation-disordered rocksalt, and cation-ordered layered structures. In contrast to the understanding of Li-excess oxides, sulfide-based compounds with ordered layered structures are electrochemically less active compared with the materials with disordered structure. Theoretical study reveals that a unique local structure for a sulfide ion coordinated by 6 Li ions, SLi6 configuration, is formed, which can be found only for the disordered structure and not for the layered structure. The unique local structure triggers electron delocalization for sulfide 3p orbitals, leading to superior electronic conductivity, as experimentally evidenced, and thus anionic redox is successfully activated. Furthermore, such nonuniform local structures lead to easier structural distortion and efficient S–S dimerization, and even trimerization (S32–), upon delithiation. Although sulfide-based compounds as battery electrode materials suffer from dissolution after oxidation, this practical problem is effectively mitigated by the use of highly concentrated electrolyte solutions with fewer free solvent molecules, leading to superior reversibility for anionic redox. The insights derived can guide the development of high-energy electrode materials with anionic redox with or without transition metal ions possessing conductive d electrons.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Li-ion battery, High-capacity positive electrode, Anionic redox, Sulfides, Transition metals

刊行年月日: 2025-07-30

出版者: American Chemical Society (ACS)

掲載誌:

• Journal of the American Chemical Society (ISSN: 00027863) vol. 147 issue. 30 p. 26238-26253

研究助成金:

• Japan Science and Technology Agency JPMJGX23S3
• Japan Science and Technology Agency JPMJGX23S5
• Japan Science and Technology Agency JPMJPF2016
• Ministry of Education, Culture, Sports, Science and Technology JPMXP1122712807
• Japan Society for the Promotion of Science 19H05814
• Japan Society for the Promotion of Science 21H04698
• Japan Society for the Promotion of Science 24H02204
• Japan Science and Technology Agency JPMJAP2313
• Japan Science and Technology Agency JPMJCR21O6

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1021/jacs.5c04018

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更新時刻: 2025-07-31 16:30:23 +0900

MDRでの公開時刻: 2025-07-31 16:17:50 +0900