Surface modification of garnet with amorphous SnO2via atomic layer deposition

Abstract

In recent years, with the wide application of lithium ion batteries, severe safety problems of organic electrolytes have been exposed. The high reliability and safety of solid electrolytes make them an appealing choice to replace organic electrolytes. A cubic phase garnet-type solid electrolyte, Li₇La_2.75Ca_0.25Zr_1.75Nb_0.25O₁₂ with high ionic conductivity at room temperature and wide electrochemical stability window arouses extensive attention. However, its large interfacial resistance associated with lithium ion transport hampers the practical application of this material to real battery systems. To solve this issue, we sputtered an amorphous SnO₂ layer onto the surface of the solid electrolyte via atomic layer deposition to reduce interfacial resistance. Also, the existence of the amorphous SnO₂ layer prevents interface reactions of garnet with metallic lithium, which greatly improves the cycling stability of Li/garnet/Li symmetric cells. We believe that atomic layer deposition is an effective strategy to improve the electrochemical performance of solid-state lithium metal batteries, and can be extended to other alkali and alkaline earth metal batteries.