The invention belongs to the technical field of batteries, particularly relates to the technical field of
lithium ion batteries, and particularly relates to a non-
aqueous electrolyte which comprises a compound shown in a formula I and a compound shown in a formula II, in the formula I, R1, R2, R3 and R4 are independently selected from any one of a
fluorine atom, a difluorophosphoryloxy group, a
methanesulfonic acid group and a trifluoromethanesulfonic
acid group respectively, and R1, R2, R3 and R4 are independently selected from any one of a
fluorine atom, a difluorophosphoryloxy group, a
methanesulfonic acid group and a trifluoromethanesulfonic
acid group; in the formula II, R5, R6, R7 and R8 are respectively and independently selected from any one of
fluorine atoms,
trifluoromethyl, and C1-C3
alkyl sulfonic acid groups which are substituted by fluorine atoms or not substituted by fluorine atoms; based on the total
mass of the non-
aqueous electrolyte, the
mass percentage of the compound in the formula I is A, the
mass percentage of the compound in the formula II is B, A is more than or equal to 0.01% and less than or equal to 10%, B is more than or equal to 0.05% and less than or equal to 5%, and A / B is more than or equal to 0.01 and less than or equal to 50. According to the present invention, the compound represented by the formula I and the compound represented by the formula II are matched for use in the
electrolyte, such that the cycle performance and the high-temperature storage performance of the electrochemical device can be simultaneously improved.