High-voltage electrolyte containing fluorine-containing cosolvent

The invention discloses a high-voltage electrolyte containing a fluorine-containing cosolvent, the high-voltage electrolyte comprises a main lithium salt, the fluorine-containing cosolvent and an additive, the fluorine-containing cosolvent is composed of fluoroethylene carbonate, linear fluorocarboxylic ester and linear fluorocarbonic ester, the fluoroethylene carbonate accounts for 5-30 wt% of the total mass of the electrolyte, the linear fluorocarboxylic ester accounts for 5-10 wt% of the total mass of the electrolyte, and the linear fluorocarbonic ester accounts for 5-10 wt% of the total mass of the electrolyte. And the working voltage of the high-voltage electrolyte is greater than or equal to 4.48 V. The fluorine-containing cosolvent disclosed by the invention can remarkably restrain the problem of 85 DEG C storage gas production expansion caused by high-content fluoroethylene carbonate under high voltage, the safety of the electrolyte is improved, and meanwhile, the high-voltage cycle performance of the