Low temperature lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and especially relates to a low temperature lithium ion battery. The low temperature lithium ion battery comprises a positive plate, a negative plate, a diaphragm and an electrolyte; the positive active material of the positive plate is ternary material-doped lithium manganate, and the surface of the above ternary material is coated with a fast ion conductor; the negative active material of the negative plate is graphite or amorphous carbon-coated graphite; and the electrolyte comprises a lithium salt, a solvent and an additive, the lithium salt is a mixture containing at least two of LiPF6, LiBOB, LiODFB, LiFSI, LiTFSI and LiPO2F2, and the solubility of the lithium salt is 1.0-1.5 mol / L. The comprehensive optimization of the material system of the positive plate, the negative plate and the electrolyte and the cell structure of the battery reduces the interface impedance of the battery at a low temperature, and improves the initial discharge voltage of the battery in an ultralow temperature environment, so the battery can normally work under -40 DEG C ultralow temperature and large rate conditions.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, in particular to a low-temperature lithium ion battery. Background technique [0002] Due to its outstanding advantages such as high energy density, low self-discharge, and no memory effect, lithium-ion batteries have become the main solution for mobile energy, and are widely used in many fields such as mobile phones, tablets, electric vehicles, and home energy storage. The use environment of lithium-ion batteries is relatively complex, so higher requirements are placed on the performance of lithium-ion batteries. The current low-temperature performance of lithium-ion batteries is relatively poor, which has restricted the promotion and use of lithium-ion batteries in the field of electric vehicles. The main manifestations are that after the temperature drops (<0°C), the viscosity of the internal electrolyte of lithium ions increases, and the mobility of lithium ions changes. Poo...

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Problems solved by technology

[0003] In the existing technology, the traditional lithium-ion battery low-temperature solution is mainly the external heating method of the battery pack, which has the disadvantage of long heating time, and the cost of the battery system is greatly increased; one is to add an electrolyte solvent with a low melting point and low viscosity at low temperature The main method is to improve the low-temperature performance while seriously weakening the high-temperature performance of the battery, and it is difficult to guarantee the long-term low-temperature cycle performance, and the application field is relatively limited.

Wuhan Zhongju Energy Technology Co., Ltd. published an invention patent with the application number 200910063261.7. In the invention, it mentioned a polymer lithium-ion battery whose main material is lithium manganese oxide or lithium iron phosphate, which can meet the low-temperature discharge capacity of -40°C. Up to 70% of the initial capacity, the improvement in charging is not obvious; Hunan Tianheng New Energy Co., Ltd. has disclosed an invention patent with the application number 201010534033.6, in which it is mentioned that the main material of the positive electrode is lithium manganese oxide or nickel cobalt manganese One or more polymer lithium-ion batteries of lithium cobaltate and lithium cobaltate can meet the low-temperature 0.2C low-rate discharge capacity of -40°C and reach more than 85% of the initial capacity. application

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