Investigation of the solid-state electrolyte/cathode LiPON/LiCoO2 interface by photoelectron spectroscopy

The electronic structure of a solid electrolyte/solid electrode interface (SESEI) of an all-solid-state thin film battery was investigated The thin film battery consisted of a UPON solid electrolyte and a LiCoO2 cathode The lithium phosphorus oxynitride (UPON) electrolyte was RF sputtered in a step-by-step procedure onto the cathode and investigated by photoelectron X-ray-induced spectroscopy after each deposition step An intermediate layer was found-composed of some new species-that differs in its chemical composition from the cathode as well as the UPON solid electrolyte material and changes with growing layer thickness In contrast, the electronic structure of the underlying cathode material remained predominantly unchanged