Method for improving formation interface of lithium ion battery

Abstract

The invention provides a method for improving a formation interface of a lithium ion battery. The method comprises steps that 1) after the lithium ion battery is baked, liquid injection is performed totally twice, the vacuumizing position of a battery core is increased during primary liquid injection, that the air in the battery core is removed is guaranteed, a negative pressure state is kept between the battery core and the electrolyte, nitrogen pressure is utilized for multiple times of liquid injection circulation, after the liquid injection is finished, the battery core is subjected to standing, after standing is finished, secondary liquid injection is performed, pumping negative pressure is performed, the electrolyte is injected into the battery core by utilizing the nitrogen, high-temperature aging of the battery core is performed after secondary liquid injection, clamps are arranged on the aged battery core, two gaskets are placed on a screw, the screw is tightened, lithium ionbattery formation is performed by adopting constant current charging, a vacuum valve is opened in the formation process, the battery is subjected to standing for 5 minutes, and the battery is then subjected to 0.2C constant-current charging to 3.34-3.35 V. The method is advantaged in that bad black spots of the formation interface are ameliorated by adjusting the vacuum degree during liquid injection and negative pressure formation, moreover, electrochemical performance of the battery core is improved, and use cost of the battery core is reduced.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery formation processes, in particular to a method for improving the formation interface of lithium-ion batteries. Background technique [0002] As a "secondary" battery, lithium-ion batteries have the advantages of high specific energy, long life, low pollution, and no memory effect, making them have a broad market in passenger cars, energy storage, forklifts, and ships. In the production process of lithium-ion batteries, formation is a relatively important process. During formation, a layer of solid electrolyte interfacial film (SEI film) will be formed on the surface of the negative electrode sheet. The quality of the SEI film directly affects the cycle life and safety of the battery cell. , thermal stability, self-discharge and internal resistance and other electrochemical properties. Therefore, under the premise of ensuring the excellent electrochemical performance of the battery cel...

AI Technical Summary

Problems solved by technology

[0003] The technical problem solved by the present invention is to provide a method for improving the formation interface of lithium-ion batteries, so as to solve the problem that a small amount of "black spots" appear on the negative electrode sheet after the negative pressure formation of the battery cell proposed in the background technology, and the existence of "spots" indicates The poor chemical formation interface will reduce the electrochemical performance of the battery during use, and its service life will also be shortened, resulting in an increase in cost.