Abstract: Lithium phosphorus oxynitride (LiPON) thin films were prepared by radio frequency (RF) magnetron sputtering. The morphology, composition and electrochemical performance of LiPON electrolyte thin films placed in humid ambient were investigated using SEM, XRD and XPS, and electrochemical measurements of AC (alternating current) impedance and potential linear scanning, respectively. Obvious changes in surface morphology, composition and electrochemical properties were found for the as-deposited LiPON film placed in humid ambient with a relative humidity of 40% for 24 h. Results showed that the uniformity of the film surface became poor, the contents of phosphorous and nitrogen in LiPON film decreased due to its reaction with H2O, releasing gaseous PH3 and NH3. In addition, the formation of Li2CO3 obviously increased the contents of carbon and oxygen in LiPON film. Therefore, LiPON thin films placed in humid ambient resulted in a bad effect on its electrochemical performance such as the ionic conductivity and the electrochemical stability window.

Key words: LiPON thin films, Thin film electrolyte, Magnetron sputtering, All-solid-state thin film lithium battery