An electrolyte is provided that includes at least one of a compound represented by Formula 1 (wherein, R 1, R2, R3, and R4 represent a hydrogen group, or a methyl group and an ethyl group; X, Y, and Z represent sulfur (S) or oxygen (O)) or Formula 2 (wherein, R1 and R2 represent a hydrogen group, a halogen group, or a methyl group and an ethyl group, or groups in which a part of hydrogen thereof is substituted by a halogen group; X, Y, and Z represent sulfur (S) or oxygen (O)) which can retain chemical stability at high temperatures. Use of the electrolyte of the present invention allows a battery to have excellent characteristics in a hot environment.