We prepared spinel-phase LiMn2O4 layer by using rf magnetron sputtering system. LiMn2O4 films were deposited at room temperature and then annealed at 750°C for crystallization to spinel type. In order to reduce the interface reaction such as Mn dissolution phenomenon during operation, we introduced SnOx (coating-layer) thin film. The SnOx films were deposited on LiMn2O4 films by rf magnetron sputtering system. A SnOx-coated LiMn2O4 film was more stable during the chargingdischarging reaction and maintained good cycle behavior at high temperature conditions of 55°C.