Abstract: The invention discloses electrolyte of a lithium ion secondary battery. The electrolyte comprises a non-aqueous solvent and a lithium salt dissolving in the non-aqueous solvent, wherein the non-aqueous solvent contains boronic acid derivative lithium salt with the mass accounting for 0.5-15% of the total mass of the non-aqueous solvent; the structure formula of the boronic acid derivative lithium salt is described in the following formula in the specification, wherein R1, R2, R3, R4, R5 and R6 are any in hydrogen, halogens, alkyl bases, alkylene bases, alkyl halide bases, aromatic groups containing halogen substituent bases or oxygen-containing groups; the oxygen-containing groups refer to alkyl bases, halogenated alkoxy bases, oxygen-containing aromatic groups or oxygen-containing aromatic groups containing the halogen substituent bases; at least two of R3, R4, R5 and R6 are halogens which are F or Cl; at least one of R1 and R2 is an aromatic group or aromatic group containing the halogen substituent bases. The invention has the advantages that since the boronic acid derivative lithium salt is added into the electrolyte, when the lithium ion battery is charged for the first time, a stable-compact-flexible SEI (Solid Electrolyte Interphase) film is formed, so that the low-temperature discharging performance and the cycling performance of the electrolyte are improved.
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