Preparation method and application of square laminated lithium ion battery capable of improving stress

Abstract

The invention discloses a preparation method of a square laminated lithium ion battery capable of improving stress. The preparation method comprises the following steps: 1, preparing positive electrode slurry; 2, coating a positive electrode; step 3, manufacturing negative electrode slurry; 4, coating a negative electrode; step 5, performing sheet punching operation to obtain a cut positive electrode sheet and a cut negative electrode sheet C1; and 6, sequentially carrying out existing processes of lamination, tab welding, shell entering, drying, liquid injection, exhausting, formation, aging and capacity grading on the cut positive plate obtained in the step 5 and the cut negative plate C1 to obtain the finished square laminated lithium ion battery. The method is scientific in design, the coating process of the positive plate is improved, and the two sides of the positive plate are scientifically coated with the ceramic adhesive and the positive slurry according to a preset mode, so that the binding force of the bottom corner of the battery shell to a battery pole group assembled in the battery shell can be effectively reduced, and the stress concentration problem of the square laminated lithium ion battery is relieved; and the cycle performance of the square laminated lithium ion battery is improved.

Description

technical field [0001] The invention relates to the technical field of sheet lithium-ion batteries, in particular to a preparation method and application of a square laminated lithium-ion battery capable of improving stress. Background technique [0002] Due to the advantages of high energy density, long cycle life, high power density and no pollution, lithium-ion batteries are more and more widely used in the field of electric vehicles. With the continuous improvement of the cruising range of electric vehicles, the requirements for the energy density of lithium-ion power batteries are also getting higher and higher. [0003] In order to pursue higher energy density, lithium-ion batteries are increasingly converted from wound structures to laminated structures. The electrode group of laminated lithium-ion power batteries is usually thick, and as the cycle progresses, the electrode group will continue to expand, resulting in an increase in the expansion force of the battery....

AI Technical Summary

Problems solved by technology

The electrode group of laminated lithium-ion power battery is usually thicker. As the cycle progresses, the electrode group will continue to expand, resulting in an increase in the expansion force of the battery.

Due to the limitation of the casing structure of the square laminated battery, the bottom and edge of the battery casing cannot be deformed, especially the binding force (ie, the binding stress) of the bottom corner of the battery casing to the battery pole group assembled in it is more obvious , therefore, there will be a problem of uneven force on the pole group during the cycle, and the uneven force on the pole group will lead to different degrees of reaction between the pole piece and the electrolyte

For example, the side reaction in the area where the pole piece is under a large force is serious, which further increases the thickness of the pole piece, which in turn leads to an increase in the binding force of the battery case, and lithium precipitation occurs on the negative electrode piece, which leads to serious attenuation of the battery cycle performance.

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