Abstract
All-solid-state lithium-ion batteries (ASSLIBs) are promising candidates as the next generation battery because of inherently high safety and high energy density. The practical application of high-performance ASSLIBs is to be achieved by the development of solid electrolytes (SEs) with high ionic conductivity. So far, many SEs with high ionic conductivity over 10−3 S cm−1 have been discovered. However, ASSLIBs still face challenges arising from solid/solid interfaces. ASSLIBs using sulfide SEs involve chemical and mechanical degradations at the interface between cathode materials and solid electrolytes in cathode composites during the charge/discharge process. These degradations increase total resistance in ASSLIBs, leading to cycle deterioration. Therefore, understanding the degradation behavior is important for realizing long-life ASSLIBs. Scanning spreading resistance microscopy (SSRM) is a type of atomic force microscopy technique, which provides current distribution with high spatial resolution at the sample surface. An SSRM study by Otoyama et al. reported that a part of the cathode materials in the electrode shows insufficient electron conduction paths after the charging and involves high local resistance in the domains of the cathode materials.1 The local resistance analysis using SSRM is a useful technique for unveiling the degradation behavior in ASSLIBs.Herein, we investigate the local resistance of cathode composites with LiNbO3-coated LiNi0.5Co0.2Mn0.3O2 (NCM) and argyrodite-type SEs for ASSLIBs after charging and elucidate the degradation behaviors through ex-situ SSRM. The local resistance analysis reveals the intrinsic resistance changes of NCM particles involving lithium deintercalation. Topography and local resistance mapping obtained by ex-situ SSRM study show that a part of NCM particles in cathode composites is electrically isolated after the charging to a high potential.2 Our work demonstrates that the ASSLIBs after the charging to a high potential cause mechanical degradation due to the volume change of NCM particles. Acknowledgments This study is based on the results obtained in the ‘Evaluation of All-Solid-State Battery Material and Foundational Technology Development for Next Generation (SOLiD-Next, JPNP23005)’ project, commissioned by the New Energy and Industrial Technology Development Organization (NEDO). References M. Otoyama et al., J. Phys. Chem. C, 125, 2841 (2021).H. Gamo et al., J. Mater. Chem. A, submitted.
Published Version
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