Low Interface Resistance in Solid-State Lithium Batteries Using Spinel LiNi0.5Mn1.5O4(111) Epitaxial Thin Films

Solid-state Li batteries that use spinel LiNi0.5Mn1.5O4 as a positive electrode are promising energy-storage devices for portable electronics and electric vehicles. For practical applications of such batteries, it is crucial to understand the ionic conductivity across the solid-electrolyte/electrode interfaces. Here, we demonstrate a low interface resistance of 34 Omega cm(2) in solid-state Li batteries using LiNi0.5Mn1.5O4(111) epitaxial thin films with atomically ordered surfaces as the positive electrode. Further, we find that the interface resistance using Li3PO4/LiNi0.5Mn1.5O4(111) is larger than that using LiNi0.5Mn1.5O4(001) epitaxial thin films. These results indicate the presence of anisotropic interface resistance when different facets of spinel LiNi0.5Mn1.5O4 are used as the positive electrode.