Impact of the Crystal Orientation of Positive Electrodes on the Interface Resistance across a Solid Electrolyte and Electrode

Understanding the origin of the resistance at the interfaces of a solid electrolyte and electrode material is crucial for the design of high-performance all-solid-state lithium batteries. In particular, it is of considerable importance to quantitatively study the impact of the crystal orientations of electrodes on the interface resistance. However, the investigation of the properties of buried interfaces has been challenging because conventional studies are based on granular samples. In this work, we quantitatively examined the resistance at the interface of the solid electrolyte Li3PO4 and LiNi1/3Mn1/3Co1/3O2 (NMC) positive electrode epitaxial thin films. We fabricated thin-film NMC electrodes with two orientations, (001) and (104), and investigated the battery performance. Furthermore, we clarified that when the surfaces of NMC were exposed to the air, the Li3PO4/NMC interface resistances increased drastically, depending on the crystal orientations.