Insights on Bi-O dual-doped Li 5.5 PS 4.5 Cl 1.5 electrolyte with enhanced electrochemical properties for all-solid-state lithium metal batteries

Sulfide-based all-solid-state lithium metal batteries (ASSLMBs) are viable options for electric vehicles due to their promising high energy densities. However, the poor stability of sulfide towards air/moisture and lithium metal anode inhibits their development. Herein, we tailored the Bi-O dual-doping amount to enhance the chemical/ electrochemical stability of Li5.5PS4.5Cl1.5 electrolyte for ASSLMBs. The optimized Li5.54P0.98Bi0.02S4.47O0.03Cl1.5 demonstrates improved air/moisture stability in various environments with different dew points due to the formation of oxysulfide units PS3O and LiBiS2 phases. Incorporating Bi-O into the structure leads to enhanced Li dendrites suppression and accelerated the transport rate of Li-ion at the interface. This improvement arises from the uniform current distribution and the formation of the of the composite SEI, which includes phases such as LiCl, Li2O, and Li-Bi alloy. The Li5.54P0.98Bi0.02S4.47O0.03Cl1.5 exhibits enhanced compatibility with Li metal and yields superior cycling performance when applied the Li metal anode in both lithium symmetric cells and ASSLMBs combined with LiCoO2 and high-nickel LiNi0.9Mn0.05Co0.05O2 at various operating temperatures (-20 degrees C, 25 degrees C, and 60 degrees C). When cycled at 0.2 C at 25 degrees C, LiCoO2-based electrode delivers a notable initial discharge capacity of 156.6 mAh g-1. Even after 150 cycles, the battery maintains a significant portion of this capacity, retaining 79.7 %. This dual-doping strategy provides a guideline for designing solid electrolytes for highperformance ASSLMBs.