Lithium ion battery formation method for optimizing performances of SEI membrane

Abstract

The invention relates to a lithium ion battery formation method for optimizing the performances of an SEI membrane. The method comprises the following steps: taking a sample battery, determining the film forming potential of the sample battery, setting sine alternating current at all film forming potentials carrying out periodic charging and discharging multiple times, and carrying out charging with large current in a potential interval for realizing no film formation. The pertinent formation method of a lithium ion battery is designed, and large current charging is adopted in the potential interval for realizing no film formation, so the integral performances of the battery are improved, the formation time is saved, and the making period of the battery is shortened.

Description

technical field [0001] The invention belongs to the technical field of lithium battery formation, and in particular relates to a lithium ion battery formation method capable of optimizing SEI film performance. Background technique [0002] At present, lithium-ion batteries have been widely promoted and used as the most common green and environmentally friendly energy around us. In recent years, with the continuous development of the application market, the client's requirements for the performance of lithium-ion batteries have been continuously improved, especially in the application of electric vehicles, it is required that the matching batteries must have high consistency and stability to meet the requirements of the lithium-ion battery. In the vehicle environment, each battery cell still has high consistency during the long-term cycle process, so that the performance of the entire battery pack will not be attenuated or even a safety accident will occur due to the deterior...

AI Technical Summary

Problems solved by technology

During the cycle, the defective and unstable SEI film will continue to undergo repair and reformation reactions, thus continuously consuming the electrolyte and active lithium ions, resulting in a decrease in the reversible capacity of the battery and attenuation of cycle performance; in extreme cases , may cause a short circuit in the battery due to the growth of side reaction deposits or lithium dendrites piercing the separator, causing safety accidents

[0004] In view of the above reasons, battery manufacturers and scholars have proposed a variety of chemical formation methods to optimize battery performance. Among these methods, most of them use the method of reducing the initial charging current density in order to obtain a dense SEI film through a slow and sufficient reaction. However, it is obvious that This formation method takes a long time, which greatly prolongs the production cycle of the battery; and this method does not take into account the specific formula of the battery system or electrolyte, and is not targeted. Although the slow film-forming reaction effect is relatively good, it is not effective in the cycle test. In the early stage, the repair and reformation reaction of the membrane is still unavoidable, resulting in a rapid decline in battery capacity at the beginning of the cycle.

Images