Low-temperature-resistant electrolyte as well as preparation method and application thereof

Abstract

The invention discloses a low-temperature-resistant electrolyte as well as a preparation method and application thereof. The low-temperature-resistant electrolyte comprises an electrolyte, an additive and a solvent; the electrolyte comprises lithium hexafluorophosphate and other lithium salts; the additive comprises fluoroethylene carbonate and / or a nitrile compound with 2-3 nitrile functional groups; the solvent comprises a first solvent and a second solvent; the first solvent comprises a mixed solvent of dimethyl carbonate and diethyl carbonate; and the second solvent comprises a mixed solvent of methyl ethyl carbonate and methyl propyl carbonate. With the low-temperature-resistant electrolyte disclosed by the invention adopted, a lithium ion battery can have very excellent low-temperature performance, and the charging and discharging performance of the lithium battery at the temperature of 20 DEG C below zero to 40 DEG C below zero is ensured.

Description

technical field [0001] The invention belongs to the technical field of electrolytes, and in particular relates to a low-temperature resistant electrolyte and its preparation method and application. Background technique [0002] Electrolyte is an important carrier for ion transmission in lithium-ion batteries, and its composition and performance will largely affect the cycle capacity and service life of batteries. Lithium-ion batteries with conventional electrolyte systems are under low temperature conditions, the viscosity of the electrolyte increases and the conductivity decreases, which often leads to low charge and discharge capacity and lithium precipitation, which in turn leads to the failure of normal use or even explosion of the product. [0003] At present, the conductive salt in the electrolyte is mostly lithium hexafluorophosphate, but the low-temperature performance of the secondary lithium battery using lithium hexafluorophosphate as the conductive salt is diffic...

AI Technical Summary

Problems solved by technology

Lithium-ion batteries with conventional electrolyte systems are under low temperature conditions, the viscosity of the electrolyte increases and the conductivity decreases, which often leads to low charge and discharge capacity and lithium precipitation, which in turn leads to the failure of normal use or even explosion of the product

[0003] At present, the conductive salt in the electrolyte is mostly lithium hexafluorophosphate, but the low-temperature performance of the secondary lithium battery using lithium hexafluorophosphate as the conductive salt is difficult to meet the actual needs

When the ambient temperature is as low as minus 40 degrees Celsius or even lower, the battery cannot fully release its full capacity, or even fail to work normally, thus limiting the application of secondary lithium batteries in extreme temperature conditions

When the temperature is lowered, the current commercial electrolyte solution that uses lithium hexafluorophosphate as the conductive salt will crystallize or solidify, the viscosity will increase, the conductivity will drop sharply, and the interface impedance between the electrolyte and the electrode will increase greatly, resulting in a sharp drop in battery performance and even battery failure. Work

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