A composite positive electrode sheet and preparation method thereof, and lithium ion battery

Abstract

The invention relates to a composite positive plate and a preparation method therefor, and a lithium ion battery, and belongs to the technical field of the lithium ion battery. The composite positive plate comprises a positive electrode current collector and a positive electrode material layer arranged on the surface of the positive electrode current collector, wherein the positive electrode material layer is formed by more than two kinds of positive electrode active material coating units in a spliced manner; the positive electrode active material coating units comprise positive electrode active materials; and the positive electrode active materials in the adjacent two positive electrode active material coating units are different in types. According to the composite positive plate provided by the invention, the surface of the positive electrode current collector is coated with multiple kinds of positive electrode active materials to form the positive electrode active material coating units which are spliced to form the positive electrode material layer, so that the advantage of each kind of the positive electrode active material can be taken into play; meanwhile, mutual influence between the positive electrode active materials can be avoided; and the total electrochemical performance of the positive plate is improved.

Description

technical field [0001] The invention relates to a composite positive electrode sheet, a preparation method thereof and a lithium ion battery, belonging to the technical field of lithium ion batteries. Background technique [0002] Lithium-ion batteries have attracted people's attention and use because of their high energy density, long cycle life, and environmental friendliness. The current lithium-ion batteries mainly include lithium iron phosphate batteries, ternary batteries, and lithium manganate batteries. And each battery has its own advantages and disadvantages. For example, lithium iron phosphate battery has good cycle life and high safety performance, but its energy density is low. Ternary battery has high energy density, but poor safety performance and high price. The price of lithium manganate battery Low, but its cycle life is poor. In order to give full play to the advantages of each battery material and improve the overall performance of the lithium-ion batte...

AI Technical Summary

Problems solved by technology

[0004] Due to the different physical properties and electrochemical properties of various positive electrode active materials, after the above-mentioned mixed positive electrode material is made into a positive electrode sheet of a lithium-ion battery, various positive electrode active materials are dispersed in the same positive electrode material layer, and the positions in space are relatively close to each other. There will be an impact between them, so that the improvement of the electrochemical performance of the positive electrode as a whole is relatively limited.

In addition, when preparing the positive electrode sheet, it is necessary to mix various positive electrode active materials first to make a mixed slurry. Due to the different densities of the various positive electrode active materials, the uniformity of the slurry is not easy to control, which will lead to After that, the positive active material on the pole piece becomes uneven, which affects the electrochemical performance of the pole piece and the battery.

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