High-voltage electrolyte for lithium ion battery

Abstract

The invention provides high-voltage electrolyte for a lithium ion battery. The high-voltage electrolyte is composed of an electrolyte lithium salt, fluorocarbonate, nitriles, a solvent and an additive, wherein the electrolyte lithium salt is LiPF6 with the concentration of 1.2mol/L-1.6mol/L; a fluorocarbonate solvent accounts for 10%-60% of the total mass of the solvent; the nitriles account for 5%-15% of the total mass of the solvent; a non-aqueous organic solvent accounts for 23%-84.5% of the total mass of the solvent; the additive is lithium difluorophosphate and accounts for 0.5%-2% of the total mass of the solvent. By compounding and combining cyclic fluorocarbonate, straight-chain fluorocarbonate, the nitriles, the additive and the like, the high-voltage heat stability of the electrolyte is prone to improve and the problems that the high-temperature circulating stability of conventional electrolyte is poor and the high-temperature storage is not ideal are improved. Meanwhile, the electrolyte has small viscosity when the materials are matched; the wetting property of an electrode material is facilitated, the liquid injection time of the lithium ion battery is shortened and the rate performance of the battery is improved.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, and more specifically, the invention relates to a high-voltage electrolyte solution for lithium-ion batteries. Background technique [0002] Energy density and safety are the two main directions of lithium-ion battery industry research. The energy of a lithium-ion battery is determined by the capacity of the lithium battery and the cut-off voltage of the charge. Therefore, in order to increase the energy density of the lithium battery, it is necessary to increase the cut-off voltage of the charge or adopt a new high-energy-density lithium battery material system. Although the development of most new high-energy-density lithium battery materials has become a research and development hotspot worldwide, it is still in the basic research stage. At present, lithium cobalt oxide, lithium manganese oxide, ternary materials and lithium iron phosphate materials are still used as the mainstream positi...

AI Technical Summary

Problems solved by technology

Although the high-voltage cycle performance of this fluorocarbonate has been significantly improved at room temperature, severe flatulence will occur when it is cycled at high temperature

Moreover, the viscosity of this cyclic fluoroethylene carbonate is high, which affects the wettability of the separator and the rate performance of the battery.

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