The solid electrolytes Li2O-LiF-P2O5 (Li2O of 40-60 mol%, LiF of 5-20 mol%, P2O5 of 30-45 mol%) were prepared using a melt-quenching technique and their electrochemical performance was investigated. Among the prepared electrolytes, the optimized solid electrolyte Li2O-LiF-P2O5 having the mole ratio of 50:30:20 exhibits a high ionic conductivity of 4.4 x 10(-7) S cm(-1) and low electronic conductivity of 2.1 x 10(-12) S cm(-1). Furthermore, to control the ratio between the components of the solid electrolytes, the equations for determination of the ionic conductivity and activation energy of the solid electrolytes with various component ratios were obtained. The solid electrolytes have significant chemical and electrochemical stabilities to lithium metal which promises successful application in lithium-ion batteries. The solid electrolytes Li2O-LiF-P2O5 were used as the coating material for surface modification of LiMn2O4 electrode material, which exhibited higher capacity and cycling stability at high charge cut-off potential of 4.5 V compared to the pristine material. Moreover, the solid electrolyte as the coating material of LiMn2O4 reduces an increase in the electrode resistance and resistance of the interface between the solid electrolyte and electrode material which results in the improvement of the electrochemical performance.