ELECTROLYTE COMPOSITION, METHOD FOR SECONDARY ELECTROLYTE FILLING, AND LITHIUM SECONDARY BATTERY

The present application belongs to the technical field of lithium-ion batteries, and particularly relates to an electrolyte composition suitable for secondary electrolyte filling. The electrolyte composition comprises a first electrolyte and a second electrolyte, wherein the first electrolyte contains 1-2.5 wt% of vinylene carbonate, 0.1-3 wt% of lithium bis(fluorosulfonyl)imide, 5-15 wt% of lithium hexafluorophosphate, 0.01-5 wt% of a positive electrode film-forming additive, 0.01-5 wt% of a negative electrode film-forming additive, and 1-10 wt% of a fluorine-containing solvent, with the balance being a non-aqueous organic solvent. In the present application, by controlling the amounts of VC and LIFSI in the first filling, the additional filling of a fluorine-containing solvent and the addition of a positive electrode film-forming additive, the problems of an excessively high initial DCR, an excessively fast cyclic DCR growth speed, obvious long-cycle attenuation and diving can be avoided. Another core innov