Self-Adaptive Superionic Electrolytes via Multiple-Cation Modulation for All-Solid-State Lithium–Metal Batteries

All-solid-state lithium–metal batteries offer devices with high specific energy and intrinsic safety, yet their practical implementation is impeded by interfacial instability at the lithium metal/electrolyte interface, especially under high current densities. Conventional interfacial stabilization approaches require complex and costly interfacial engineering, limiting their practicality, highlighting the urgent need for a simple yet effective electrolyte design strategy. Here, a multiple-cation-presetting (Ag and W) argyrodite electrolyte is developed to simultaneously achieve superionic conductivity (over 10 mS cm–1) and superior interfacial stability with softer texture. During cycling, Ag+ can be extracted from the electrolyte layer, reduced to Ag metal, and diffused into the lithium–metal anode to form a uniform Li–Ag alloy, while W can convert into minor conductive LiWS2 in the solid electrolyte interface. Benefiting from in situ anodic and interfacial modification by the SSE, it facilitates accelerated interfacial kinetics and homogeneous Li+ flux. As a result, the Li symmetric cells exhibit sustainable cycling over 4000 h at 0.5 mA cm–2 and beyond 1000 h at 1 mA cm–2. The Li//LiNi0.8Co0.1Mn0.1O2 cells demonstrate excellent rate capability and extended cycle life, maintaining 82.7% capacity retention after 1100 cycles at 2C. Moreover, the electrolyte sustains stable operation at high areal loading (3 mAh cm–2) and low temperature (−30 °C). Besides, such solid-state electrolytes can be extended to other all-solid-state lithium–metal rechargeable batteries. This scalable dual-cation modulation strategy provides a general and practical route to construct superionic electrolytes with compatibility with an anode by in situ interfacial and lithium metal decoration, advancing the realistic application of next-generation all-solid-state lithium–metal batteries.