| Abstract: | Thin film electrode materials are key components in the development of high rate, high capacity solid‐state Li‐ion batteries. Detailed knowledge of the epitaxial film/substrate(current‐collector) interface structures, which provides insights into epitaxial growth mechanisms and the effects of microstructure on electrochemical properties, is essential for efficient materials and device design. Here we report the epitaxial growth mechanism of a typical cathodic LiMn2O4 thin film by exploring the detailed structural and compositional variations in the vicinity of a film/substrate interface using state‐of‐the‐art scanning transmission electron microscopy. Direct observation of atom columns shows the epitaxial film forms an atomically flat and coherent heterointerface with the substrate, but that the crystal lattice is tetragonally distorted with a measurable compositional gradient from the interface to the crystal bulk. The growth mechanism is interpreted in terms of a combination of chemical and physicomechanical effects, namely a complex interplay between the internal Jahn‐Teller distortions induced by oxygen non‐stoichiometry and the lattice misfit strain. |
