Investigation of Mechanical Characteristics of Catholytes in Composite Cathode of All Solid-State Batteries

All-solid-state batteries (ASSBs) are leading the path to safer and more efficient energy storage. The solid electrolyte is a critical component in determining the performance and stability of ASSBs, responsible for both ion transfer and resisting dendrite growth. A robust solid electrolyte that excels in these functions is essential for advancing ASSB technology. Existing solid electrolytes face challenges like poor interfacial contact, mechanical debonding, and mechanical failure. While the field predominantly focuses on ion transfer and micro-scale mechanical properties, there is a noticeable gap in understanding macro-scale mechanics. This study addresses this gap by examining prevalent solid electrolytes, including Li₆PS₅Cl, Li₃YCl₆, Li₃YBr₃Cl₃, and Li₇La₃Zr₂O₁₂. Through traditional compression testing supported by video analysis, we reveal the correlations between pellet density and slenderness with elasticity, strength, and toughness across sulfide, halide, and oxide solid electrolyte materials. Our findings underscore the macro-scale mechanical advantages of LPSCl, exhibiting a relatively large elastic range (5–83 MPa), high compressive strength (~103 MPa), significant toughness (~16 MPa), and semi-ductile nature. The notable differences in elastic, non-linear, and failure mechanics among solid electrolytes emphasize the relevance of macro-scale mechanical properties in predicting cell failures such as capacity fading, dendrite growth, and contact loss.