Electrolyte additive, electrolyte and lithium ion secondary battery

The invention relates to an electrolyte additive, an electrolyte and a lithium ion secondary battery. The composition of the electrolyte additive comprises a compound with structural characteristics shown in the specification. The electrolyte additive can form a thin and uniform passivation protection film on the surface of an electrode active material, can improve the cycle characteristic and the storage performance of a battery used in a high-temperature environment when applied to an electrolyte, has low internal resistance and excellent discharge load characteristic at a high temperature, and can perform high-speed discharge. Meanwhile, the interface film impedance formed by participation of the additive can inhibit decomposition of LiPF6 at high temperature, alleviate high-temperature cyclic gas production caused by reaction of PF5 and a solvent, and further improve the high-temperature performance of the battery. In addition, the additive can adapt to various electrode materials and has wide application