Lithium ion battery, preparation method thereof and electric automobile comprising lithium ion battery

Abstract

The invention provides a lithium ion battery, a preparation method thereof and an electric vehicle comprising the lithium ion battery. The lithium ion battery comprises a positive pole piece, a negative pole piece, an isolating membrane and electrolyte. The positive pole piece comprises a positive active material; the positive active material comprises a substrate, a first coating layer and a second coating layer; the first coating layer coats the surface of the substrate in a discrete island form; the second coating layer coats the surfaces of the first coating layer and the substrate in a continuous layered form; and the electrolyte comprises an additive A and an additive B, the additive A is selected from one or more of cyclic sulfate compounds as shown in a formula 1 and a formula 2, and the additive B is selected from one or two of lithium difluoro bis (oxalate) phosphate and lithium tetrafluoro (oxalate) phosphate. According to the lithium ion battery, preparation method thereof and the electric automobile comprising lithium ion battery of the invention, the gas production rate of a lithium ion battery can be reduced, the cycle life and storage life of the lithium ion battery can be prolonged, and the increase of direct-current internal resistance of the lithium ion battery in cycle and storage processes can be remarkably inhibited.

Description

[0001] This invention is a divisional application based on the invention with the application number 201810474538.4, the application date is May 17, 2018, the applicant is Ningde Times New Energy Technology Co., Ltd., and the invention name is "lithium-ion battery". technical field [0002] The invention relates to the technical field of batteries, in particular to a lithium ion battery. Background technique [0003] Lithium-ion batteries have broad application prospects in the field of electric vehicles due to their high energy density, long cycle life, and no pollution. In order to meet the requirements of consumers for the extended range of electric vehicles, it is one of the effective ways to develop positive electrode active materials with high specific capacity. [0004] At present, lithium-nickel-cobalt-manganese ternary materials have become a research hotspot due to their high theoretical specific capacity and safety characteristics. However, the high nickel content...

AI Technical Summary

Problems solved by technology

When the temperature is lowered to room temperature, the Li 2 O will absorb CO in the air 2 and H 2 O to form LiOH and Li 2 CO 3 and other residual lithium, the existence of these residual lithium will intensify the gas production of lithium-ion batteries and deteriorate the storage performance

Lithium-nickel-cobalt-manganese ternary materials are usually in the form of secondary particles formed by the agglomeration of primary particles, and the compressive strength is poor. After crushing, the specific surface area of ​​the positive electrode active material increases significantly, resulting in an increase in the contact area with the electrolyte. Gas production problem worsens

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