Enhancing the Mechanical Properties of Solid Electrolytes for Crack-Resistant Cathodes in All-Solid-State Batteries

초록

The electrochemical performance of all-solid-state batteries (ASSBs) is strongly influenced by the physicochemical characteristics of solid electrolytes; however, the impact of their mechanical properties on cell performance remains comparatively underexplored. Here, SiO2 incorporation during Li6PS5Cl synthesis induces Si/O co-substitution, forming Li6.1P0.9Si0.1S4.8O0.2Cl with modified mechanical properties. Combined theoretical and experimental investigations show an increase in Young's modulus from 16 to 21 GPa upon Si/O co-substitution. AFM nanoindentation analysis further reveals higher elastic stiffness and hardness for Li6.1P0.9Si0.1S4.8O0.2Cl. Cells employing Li6.1P0.9Si0.1S4.8O0.2Cl-based composite cathodes exhibit markedly improved cycling performance, achieving a capacity retention of 90.8% after 500 cycles, surpassing that of cells based on conventional Li6PS5Cl. Overall, this study underscores the importance of structural engineering for tailoring the mechanical properties of solid electrolytes and provides a design framework for developing mechanically robust composite cathodes for next-generation ASSBs.

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