Preparation method of fast charging type lithium ion battery pole piece, pole piece and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method of a fast charging type lithium ion battery pole piece. The method comprises thefollowing steps of coating slurry with active substances on the two surfaces of a current collector to obtain the pole piece with a first active substance layer and a second active substance layer which are symmetrically arranged; rolling the two surfaces of the pole piece; and cleaning the redundant first active material layer to obtain the fast charging type lithium ion battery pole piece witha double-sided coating area and a single-sided coating area. According to the preparation method of the fast charging type lithium ion battery pole piece, the rolling thickness of the single-side coating area of the pole piece after rolling is consistent with that of the double-side coating area, and the compression degree of active substance layers at the two sides of the pole piece can be effectively ensured to be consistent during rolling; and the failure problems of powder falling, lithium precipitation and the like of the single-side coating area in the subsequent charging and dischargingprocess due to different thicknesses of the single-side coating area and the double-side coating area of the pole piece and different compression degrees when the pole piece is rolled to pass througha roll gap in the traditional process, are effectively avoided.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a preparation method of a pole piece of a fast-charging lithium-ion battery, a pole piece and a lithium-ion battery. Background technique [0002] Lithium-ion batteries have the advantages of high energy density, long cycle life, and good safety performance. With the gradual increase of the lithium-ion battery market, consumers have higher and higher requirements for the fast charging performance and energy density of lithium-ion batteries. Therefore, the development of lithium-ion batteries with high energy density and fast charging capability has always been the direction of research and development personnel's attention. [0003] The electrical performance of lithium-ion batteries depends to a large extent on the structure and performance of the pole piece. To improve this performance, the current common method in the industry is to optimize the posi...

AI Technical Summary

Problems solved by technology

[0006] However, since the total thickness of the single-side active material coating plus the current collector foil before rolling is less than the total thickness of the double-side active material coating plus the current collector foil, the pole piece in the single-side coating area passes through the roll gap during rolling. The degree of compaction is small, resulting in a smaller compaction density in the one-sided coated area than in the double-sided coated area

The small degree of pressure will cause two problems: First, the small degree of pressure on the one-side coating area of ​​the pole piece can transmit electrons, but due to the large pores between the particles, if the amount of conductive carbon is not enough, the conductivity of the material itself will be reduced. If the performance is relatively poor, it is difficult to form a good electronic conductive network, that is, the electronic conductivity of the pole piece is low, the problem of lithium precipitation is prone to occur during the battery cycle, the safety performance of the battery cell is reduced, and the cycle life is shortened; Second, the battery pole piece Rolling belongs to powder rolling, and its purpose is to improve the compaction density and uniformity of the active material of the battery pole piece, improve the adhesion of the active material, and improve the surface roughness

The inventors found that the reason is that during the charge-discharge cycle of the battery cell, the negative electrode single-sided coating area is prone to powder drop and lithium precipitation problems, resulting in a decline in the electrical performance of the battery cell.

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