Eliminating Li Dendrites in PEO-Based Polymer Solid Electrolytes by Doping with SbF3

The present surge in demand for energy storage systems that offer both high energy density and enhanced safety has spurred a transition toward solid-state electrolytes (SEs). Among these, solid polymer electrolytes (SPEs) have garnered considerable attention owing to their inherent advantages such as thinness, low density, and facile manufacturability. However, the issue of uncontrollable dendrite formation upon interaction with Li metal remains a persistent challenge due to localized and concentrated nucleation of Li+. Here, we present a novel electrolyte system based on PEO-LiTFSI-xSbF3 (PLSx, x = 0.5, 1, 1.5 wt %). The PLSx electrolyte exhibits a remarkable ability to consume dendrites through a spontaneous reaction with Li, leading to the formation of a stable LiF/Li3Sb interfacial phase. This interfacial phase, characterized by high ion conductivity, low electron conductivity, and a lithiophilic mesophase, effectively mitigates interfacial side reactions, promotes the uniform deposition of Li+, and significantly enhances the inhibition of dendrite growth. Consequently, Li–Li symmetric cells employing the PLS1 demonstrate exceptional cyclability, surpassing 1000 h. All-solid-state Li-metal batteries (ASSLMBs) enable 300 cycles at a 0.5C rate without any notable capacity degradation. This work opens a promising avenue for designing ASSLMBs using cleverly engineered interface layers.