Interface Characterization on All-Solid State Batteries by Multi-technique XPS

All-solid-state batteries (ASSBs) have been attracting attention as the next generation batteries, but they face challenges, including internal resistance at the solid electrolyte/electrode interface. This study examines a LiPON/LiCoO2 interface using multi-technique X-ray photoelectron spectroscopy (XPS) to analyze chemical states and energy band diagrams. Results show that interlayer formation and structural changes during manufacturing stimulate Co reduction in the LiCoO2 layer near the interface, leading to an increase in interfacial impedance. To minimize internal resistance, preventing Co reduction is necessary. The study offers insights into the chemical interactions between LiPON and LiCoO2 layers, which may help address challenges in ASSBs commercialization.