Unlocking Cycling Stability in All‐Solid‐State Li Metal Batteries via Crystalline/Amorphous Ratio Engineering of Argyrodite Electrolytes

Sulfide solid-state electrolytes are regarded as excellent candidates for all-solid-state lithium metal batteries (ASSLMBs) due to their high ionic conductivity and impressive ductility. However, enhancing the intrinsic ionic conductivity and stabilizing the interface with the lithium metal anode for sulfide solid-state electrolyte in ASSLMBs remains crucial. Herein, the crystalline/amorphous ratio (C/A ratio) of the Li_5.3PS_4.3Cl_1.7 (LPSC) electrolyte is regulated by adjusting the sintering temperatures, achieving a balance between conductivity and mechanical properties. Benefiting from a moderate proportion of the amorphous phase, the LPSC electrolyte achieves both high room temperature ionic conductivity of 8.91 × 10^-3 S cm^-1 and remarkable lithium stability at a C/A ratio of 1.42. Symmetric cells assembled with the electrolyte exhibit a critical current density of 0.71 mA cm^-2 and can be stably cycled for 2800 h at a current density of 0.1 mA cm^-2. The assembled ASSLMB exhibits an initial discharge specific capacity of 169.4 mAh g^-1 at 0.1C, with a capacity retention rate of 71.2% after 100 cycles, demonstrating excellent electrochemical performance. This work provides a new strategy to enhance the electrochemical performance of ASSLMBs by manipulating the crystalline/amorphous ratio of the electrolyte.