Preparation and structural analysis of lithium phosphorus oxynitrogen thin film electrolyte

Lithium phosphorus oxynitride (LiPON) is the most representative thin-film solid-state electrolyte for the applications of thin-film battery. It is also used as an interfacial protective layer to improve the interfacial stability of the electrolyte with the positive and negative electrodes. The radio frequency magnetron sputtering was used to deposit Li₃PO₄ as the sputtering target, and the solid electrolyte of lithium phosphorus oxynitride (LiPON) thin film was deposited under nitrogen atmosphere. By optimizing the sputtering power, working pressure, substrate temperature and other process conditions, the LiPON thin film with dense, uniform and defect-free surfaces was prepared. The XPS indicates that the sputtering process of the thin film is a reactive sputtering process, and N replaced the bridge oxygen bond (—O—) and non-bridge oxygen bond (=O) in the Li₃PO₄ structure to reconstitute nitrogen three-coordinate bond N_t (—N < ) and nitrogen double-coordinate bond N_d(=N—) to form a LiPON film with a network structure. The room temperature ionic conductivity of the LiPON thin film solid electrolyte was measured to be 7×10^-7 S·cm^-1, and the electronic conductivity was 4.8×10^-13 S·cm^-1. The dense morphology and stable electrochemical performance of LiPON thin-film solid-state electrolytes have significant advantages for the application of LiPON in thin-film batteries and interfacial modification of solid-state batteries.