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, Li2S and S form a polysulfide, and P2S5 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. For overcoming the huddles for commercial all‐solid‐state batteries, a novel pathway for solution‐phase synthesis of sulfide solid electrolytes with high ionic conductivities, as high as 1.8 mS cm−1, is developed. The study offers a promising solution for reducing the production cost remarkably to realize commercial rechargeable batteries with high energy density and stability that can replace the current lithium‐ion batteries.