Lithium ion battery formation method and lithium ion battery

Abstract

The invention relates to the technical field of lithium ion batteries, and discloses a lithium ion battery formation method and a lithium ion battery. The lithium ion battery formation method comprises the following steps: providing a lithium ion battery semi-finished product into which an electrolyte is injected, and carrying out first standing operation on the lithium ion battery semi-finished product; carrying out pressurization operation on the lithium ion battery semi-finished product after the first standing; wherein the charging current of the multiple times of charging operation is gradually increased, the charging current is 0.1-1.5 C, the charging frequency is greater than or equal to 3, and the current difference value of the two times of charging operation is 0.05-1.0 C; and carrying out secondary standing operation on the intermediate product of the lithium ion battery, and then carrying out exhausting and packaging operation to complete formation operation. Formation operation is carried out by adopting multiple times of charging, so that the uniformity and speed of SEI film formation are flexible and controllable, formation of a uniform and stable SEI film is facilitated, and the performance and quality of a lithium ion battery finished product are improved.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a lithium ion battery formation method and the lithium ion battery. Background technique [0002] Lithium-ion batteries have the characteristics of high energy density, high working voltage, long life and no memory effect, and are widely used in aerospace, medical and energy storage fields. With the promotion of large-scale applications of lithium-ion batteries in recent years, The development of power lithium-ion batteries is rapid, and its manufacturing technology has also made great progress. Among them, formation is an important process in the production process of lithium batteries. During formation, a passivation layer is formed on the surface of the negative electrode, that is, the solid electrolyte interface film. , referred to as the SEI film (solid electrolyte interface), the SEI film consumes a part of the lithium ions of the positive electrode during the formation...

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Problems solved by technology

[0003] At present, the traditional process is generally as follows: after the battery is filled with liquid, it is allowed to stand at room temperature for a period of time, and then the temperature is raised to stand still, and then the formation is carried out. Form a dense SEI film. Although this method is desirable and has good results, it takes a long time for formation, low equipment utilization, long production cycle, and low production efficiency of lithium-ion batteries, which is not conducive to speed-up and production increase.

[0004] At the same time, under the high-capacity and high-pressure compaction system of lithium-ion batteries, the infiltration of the electrolyte is relatively difficult, and the film formation is easy to be uneven and unstable during the formation process, which hinders the formation of the SEI film in the formation process. At the same time, the infiltration of the electrolyte is uneven, resulting in It is difficult to form a film. The quality of the SEI film directly affects the electrochemical performance of the battery such as cycle life, stability, self-discharge and safety, and has a greater impact on the battery. Gas is generated during the formation of lithium-ion batteries, and the battery bulges. Poor interface, which affects battery performance

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