Computationally-Guided Development of Sulfide Solid Electrolyte Powder Coatings for Enhanced Stability and Performance of Solid-State Batteries

Sulfide-based solid-state electrolytes (SSEs) such as Li6PS5Cl (LPSCl) are attractive Li+ superionic conductors for next generation solid state batteries whose narrow voltage window and environmental reactivity hinder widespread commercialization. We have shown these limitations can be mitigated by coating LPSCl powders with thin Al2O3 coatings via atomic layer deposition; however, design rules are needed to identify new coatings with further improved properties. Here we develop a density functional theory-based screening protocol to identify and experimentally demonstrate multiple new oxide coatings with multifaceted benefits. MgO coatings, in particular, improve the electronic conductivity, Li metal stability, interfacial resistance, and the critical current density of coated LPSCl powders. We find that the ionic and electronic conductivity of reaction products formed at oxide interfaces with LPSCl and Li metal are the most predictive metrics for determining a viable coating. These results open a new frontier of research for improving the stability and performance of sulfide-based SSEs.