Lithium ion battery

Abstract

The invention provides a lithium ion battery which comprises a positive electrode piece, a negative electrode piece, an isolating membrane and electrolyte solution. The positive electrode piece comprises a positive electrode current collector and positive electrode diaphragm layers, the positive electrode diaphragm layers are arranged on at least one surface of the positive electrode current collector and comprise positive electrode active materials, the negative electrode piece comprises a negative electrode current collector and negative electrode diaphragm layers, and the negative electrodediaphragm layers are arranged on at least one surface of the negative electrode current collector and comprise negative electrode active materials. The positive electrode active materials include materials, the chemical formulas of the materials are LiaNixCoyMzO2, the negative electrode active materials include graphitic carbon materials, and the battery meets the equation of 58%<=KYa / (KYa+KYc)*100%<=72%. According to the battery, the voltage-resistant abilities of the positive electrode active materials and the negative electrode active materials are reasonably matched, and the interface integrity of the positive electrode piece and the negative electrode piece can be effectively ensured, so that the lithium ion battery has excellent dynamics performance and circulation performance.

Description

technical field [0001] The invention relates to the field of batteries, in particular to a lithium ion battery. Background technique [0002] With the increasing popularity of electric vehicles, people's requirements for batteries are becoming more and more stringent, such as requiring batteries to be small and light, and must also have high capacity, long cycle life and high safety performance. To this end, technicians have made many efforts from various aspects such as battery positive and negative electrodes and electrolyte. [0003] For example, for battery cathode active materials, ternary materials have higher gram capacity and compaction density than lithium iron phosphate, so batteries using ternary materials have higher energy density. However, the volume shrinkage of ternary materials is small during cycling, so that the positive electrode sheet will squeeze the negative electrode sheet, destroying the interface between the positive and negative electrode sheets, ...

AI Technical Summary

Problems solved by technology

However, the volume shrinkage of ternary materials is small during cycling, so that the positive electrode sheet will squeeze the negative electrode sheet, destroying the interface between the positive and negative electrode sheets, and eventually leading to battery failure.

Therefore, despite higher energy densities, batteries with ternary materials as cathode active materials tend to have poor cycle life

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