A Solid-State Thin-Film Electrolyte, Lithium Silicon Oxynitride, Deposited by using RF Sputtering for Thin-Film Batteries

In this study, a new lithium-silicon-oxynitride (LiSiON) solid-state thin-film electrolyte was investigated for the first time. The LiSiON thin-film electrolyte was deposited by using the RF sputtering technique. In order to compare the LiSiON thin-film electrolyte to lithium phosphorous oxynitride (LiPON), a conventional thin-film electrolyte, were deposited LiPON thin-film electrolytes by using RF sputtering. Surface morphologies and cross-sectional views of the thin-film electrolytes were characterized by using field emission scanning electron microscopy (FE-SEM). The thin-films showed smooth surfaces without any cracks and pinholes. The smooth surfaces are thought to decrease the interfacial resistance between the electrolyte and the electrodes. In addition, surface morphologies were characterized by using atomic force microscopy (AFM). The sputtering rates were calculated using the thicknesses of the thin-films, as obtained from cross-sectional views. The structural properties of the thin-films were characterized using X-ray diffraction (XRD). All thinfilms showed amorphous properties compared to the target material which is a crystalline material. The ionic conductivity of the LiSiON thin-film was 2.47 × 10 ⁻⁶ (S/cm), which is slightly higher than that of a common thin-film electrolyte LiPON.