High‐Conductivity Argyrodite Electrolyte with Self‐Passivating Stability for Single‐Electrolyte All‐Solid‐State Lithium Batteries

Abstract All‐solid‐state lithium batteries (ASSLBs) are promising candidates for next‐generation energy storage due to their enhanced safety and energy density. Among solid‐state electrolytes (SSEs), argyrodite‐type Li 6 PS 5 X compounds offer economic advantages but suffer from limited ionic conductivity and electrochemical stability. In this study, we design a novel SSE, Li 5.5 P 0.94 Ta 0.06 S 4.5 Cl 0.75 Br 0.75 , featuring dual halide (Cl − /Br − ) occupation and Ta 5+ substitution to enhance conductivity and interfacial compatibility. The resulting SSE exhibits a high ionic conductivity of 12 mS cm −1 at room temperature. Inspired by Al corrosion passivation, it forms in situ self‐passivating interfacial layers, ensuring stability against both lithium metal anodes and high‐voltage cathodes. Batteries incorporating this electrolyte achieved 100% capacity retention over 200 cycles at 0.2C, and over 81% retention after 1200 cycles at 0.5C. Under high‐loading (30 mg cm −2 ) and N / P = 1.8 conditions, 81% capacity was maintained after 150 cycles. A 10 × 6 cm 2 pouch cell retained 96.4% of its capacity after 200 cycles. This work offers a viable route toward high‐performance, scalable ASSLBs using a single‐passivating electrolyte.