Computationally-Guided Development of Sulfide Solid Electrolyte Powder Coatings for Enhanced Stability and...

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. 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, a density functional theory-based screening protocol is developed 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. It is found 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.