Electrochemical properties of Li[Li _0.2Mn _0.54Co _0.13Ni _0.13]O ₂ cathode thin film by RF sputtering for all-solid-state lithium battery

The Li[Li _0.2Mn _0.56Ni _0.13Co _0.13]O ₂ thin films were prepared by radio frequency magnetron sputtering on Pt/Ti/SiO ₂/Si substrate with target contained a 5% excess of lithium precursor. Thin films were deposited under various deposition conditions such as working pressure, gas ratio of Ar and O ₂, and the temperature of in-situ annealing treatment. The thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The electrochemical property was estimated by a WBC3000 cycler with Li|Li[Li _0.2Mn _0.54Ni _0.13Co _0.13]O ₂ half-type cell at 1C charge/discharge rate. The (0 0 3) and (1 0 4) diffraction peaks which represent layered α-NaFeO ₂ type structure (space group R-3m) were observed. Optimal magnetron sputtering conditions were detected. The 500 °C annealed thin film after deposited at 10 m Torr in Ar:O ₂=3:1 shows a high discharge capacity of around 62 μAh/cm ² μm with a high cyclic retention.