Lithium ion battery positive plate and manufacture method thereof

Abstract

The invention discloses a manufacture method of a lithium ion battery positive plate. The manufacture method comprises the following steps: providing a positive current collector; preparing positive slurry containing an positive active material with a stratified-structured crystal form, uniformly distributing the positive slurry onto the positive current collector, drying, and carrying out primary cold pressing and slicing, so as to obtain a positive plate; carrying out infiltration on the positive plate by virtue of a solvent; and drying, and carrying out secondary cold pressing, so as to obtain the lithium ion battery positive plate. By carrying out infiltration on the positive plate which is subjected to primary cold pressing, residual stress of the positive plate can be effectively reduced, the expansion of the positive plate can be reduced, a lithium ion battery is thinned, and the energy density of the lithium ion battery is increased. The contact among particles of the positive active material is relatively close in a subsequent charging-discharging cycle process, and the cycle performance of the lithium ion battery is improved. Besides, the invention further discloses the lithium ion battery positive plate manufactured by the method and the lithium ion battery adopting the lithium ion battery positive plate.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and more specifically, the invention relates to a lithium ion battery positive plate and a preparation method thereof. Background technique [0002] In recent years, with the popularization and thinning of electronic devices such as smartphones, tablet computers, and wearable devices, the requirements for the energy density of consumer lithium-ion batteries are also getting higher and higher. [0003] The energy density of a lithium-ion battery is calculated according to the following formula: initial volumetric energy density = first discharge energy of the battery (battery capacity × discharge platform) / (battery length × width × thickness). It can be seen from the above calculation formula that under the same material system (battery capacity and discharge platform are consistent) and battery length and width, the thickness of the lithium-ion battery affects the energy density o...

AI Technical Summary

Problems solved by technology

However, due to the mutual cohesive force, the repulsive force between some positive electrode active material particles is offset, so that it cannot be completely expanded, that is, the stress cannot be completely released, which is called residual stress.

In the subsequent processing and charging and discharging process, the residual stress is continuously released, resulting in the rapid expansion of the positive electrode sheet and the increase in the thickness of the battery cell, resulting in loss of energy density and deterioration of cycle performance

[0008] The existing methods to reduce the residual stress of the positive electrode are mainly through high-temperature heat treatment or by standing for a long time. However, these two methods cannot effectively reduce the residual stress, and are time-consuming and inefficient.

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