全固体電池の性能低下の原因を多角的な機器分析によって解明～全固体電池実用化に向け、材料開発や製造プロセス改善などの観点から研究・開発の加速に貢献～

2025-05-12 株式会社東レリサーチセンター

図１

＜関連情報＞

• https://www.toray-research.co.jp/news/article.html?contentId=zspqbaed
• https://pubs.acs.org/doi/10.1021/acsaem.5c00238

硫化物固体電解質全固体電池における充放電サイクル後の電気化学挙動と形態・組成変化との相関 Correlating Electrochemical Behavior with Morphological and Compositional Changes in Sulfide Solid Electrolyte All-Solid-State Batteries after Charge/Discharge Cycles

Yasuhito Aoki,Riko Miyoshi,Kentaro Kato,Sumihisa Ishikawa,Toshikatsu Kojima,and Mitsuharu Tabuchi
ACS Applied Energy Materials  Published: April 4, 2025
DOI:https://doi.org/10.1021/acsaem.5c00238

Abstract

Morphological and compositional changes occurring inside an all-solid-state battery of NCA/Li₆PS₅Cl/graphite after a charge/discharge cycle test were analyzed in detail, combining the interpretation of electrochemical performance measurements and various instrumental analyses. The capacity of the cell faded, and the internal resistance increased after charge/discharge cycles. Also, disassembly analyses show the following features. First, delamination between NCA active materials and the solid electrolyte inside the positive electrode is observed by scanning electron microscopy (SEM), which shows an increase in lithium-ion-transfer resistance at the interface. Second, the chemical structural changes of sulfide solid electrolyte observed around the positive electrode include the generation of the oxygen-substituted and/or chloride-free PS₄ tetrahedra and the generation of the S–S bond. The chemical structural changes may have caused the delamination inside the positive electrode layer observed by SEM. Third, similar structural changes are observed inside the sulfide solid electrolyte layer, which proceeded through the grain boundary of the solid electrolyte. Those chemical structural changes resulted in a decrease in lithium-ion mobility, which was confirmed by AC impedance measurement and ⁷Li and ³¹P NMR analyses.