Electrolyte for low-temperature lithium ion battery electrolyte and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries. The invention discloses a low-temperature lithium ion battery electrolyte which is composed of a solvent, a lithium salt and an additive, the lithium salt is a mixed lithium salt and comprises at least one of lithium hexafluorophosphate or lithium tetrafluoroborate and a special lithium salt, and the special lithium salt is composed of at least one of lithium bis (oxalato) phosphate, lithium bis (fluorosulfonyl) imide or lithium difluorophosphate; and the weight percentage of the special lithium salt in the electrolyte is 0.5%-5.0%. The invention also discloses an electrolyte containing the low-temperature lithium ion battery electrolyte. Through necessary and selective addition and combination of the components, the purpose of the invention can be achieved, the low-temperature performance of the electrolyte is synergistically improved, the high-temperature performance is not lost, the application temperature range of the lithium ion battery is widened, and the influence of the environment on the performance of the battery is reduced to a certain extent. The electrolyte provided by the invention can meet low-temperature charging, and has low-temperature discharging performance different from the low-temperature discharging performance commonly required at present.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries. In particular, it relates to an electrolyte solution for a low-temperature lithium-ion battery and the lithium-ion battery. Background technique [0002] Since it was applied to 3C products by Sony in 1992, lithium-ion batteries have been gradually used in many fields, and have become more and more indispensable in the context of global new energy in the 21st century. Lithium-ion batteries are currently ideal energy storage devices due to their advantages such as high working voltage, small size, light weight, high specific energy, no memory effect, no pollution, small self-discharge, and long cycle life. [0003] Lithium-ion batteries usually consist of positive electrodes, negative electrodes, separators, electrolytes, and structural components. Among them, the electrolyte is an important part of the lithium-ion battery, known as the blood of the lithium-ion battery, which plays...

AI Technical Summary

Problems solved by technology

[0004] While lithium-ion batteries have been developed rapidly, there are still some limitations that limit their applications, and the ambient temperature used is one of the important limiting factors

When the ambient temperature used is too low, the electrochemical performance of the lithium-ion battery will decrease proportionally. The main reasons are: (1) the lithium ion in the positive electrode material has a reduced electrical conductivity and a reduced ion diffusion rate at low temperatures; (2) At low temperatures, the viscosity of the electrolyte increases, the migration of lithium ions becomes difficult, and the impedance between the electrolyte, the electrolyte, and the interface increases; (3) the viscosity of the electrolyte increases at low temperatures, and the wettability of the separator is poor; (4 ) The lithium ion deintercalation resistance of the negative electrode increases

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