A Novel Strategy to Overcome the Hurdle for Commercial All-Solid-State Batteries via Low-Cost Synthesis of Sulfide Solid Electrolytes

Unlike commercial lithium-ion batteries, the high cost and low ionic conductivity of solid electrolytes (SEs) continues to be a big hurdle in commercially available all-solid-state batteries (ASSBs). Rather than the conventional dry-process and high-energy ball milling processes, the productive solution synthesis of bulk-type SEs is the most crucial issue in the successful application of high-energy-density ASSBs. In this study, the way is paved to overcome the hurdle for commercial lithium phosphorus sulfide chloride (LPSCl) SEs via a readily processable bulk-type solution-based synthesis without acquiring any high-energy ball-milling processes. By incorporating an elemental sulfur additive during the preparation process, Li₂ S and S form a polysulfide, and P₂ S₅ is induced to react readily to provide LPSCl with excellent ion conductivity as high as 1.8 mS cm^-1 . Surprisingly, the purity of bulk type precursors does not affect the final composition and ionic conductivity of sulfide electrolytes, which show the same electrochemical characteristics of ASSB cells with a high discharge capacity of 185.6 mA h g^-1 . The study offers a promising strategy for saving the production cost of sulfide SEs, possibly up to 92%, and their commercial ASSBs are expected to be achieving a competitive cost per energy density of ≈0.46 $ W^-1 .