Variable-frequency pulse formation method based on optimal frequency of lithium ion battery

Abstract

The invention relates to a variable-frequency pulse formation method based on the optimal frequency of a lithium ion battery. The method comprises the following steps of: performing off-line measurement on an electrochemical impedance spectrum of the lithium ion battery to obtain optimal frequencies under different formation voltages; in the formation process, according to the voltage of the formed battery, selecting the optimal frequency of the battery under the voltage as the frequency of pulse formation, adjusting the amplitude and the duty ratio of pulse current, and carrying out variable-frequency pulse formation on the lithium ion battery. According to the pulse formation method based on the optimal frequency of the lithium ion battery, polarization in the battery in the formation process can be slowed down, non-uniform accumulation of reduction products is avoided, and a uniform and compact SEI film is formed, so that the cycling stability of the lithium ion battery, especially the cycling performance at normal temperature and high temperature, is improved, and the service life of the lithium ion battery is prolonged.

Description

technical field [0001] The invention relates to a lithium ion battery formation method, in particular to a frequency conversion pulse formation method based on the optimal frequency of the lithium ion battery. Background technique [0002] Lithium-ion batteries are energy storage components that have been widely used in recent years. Due to their high specific energy, high power density, high efficiency, and environmental protection, they have been widely used in consumer electronics, electric drives, and energy storage power stations. The formation process is a key process of lithium-ion batteries. During the first charging process, before lithium ions are intercalated into graphite, the electrolyte solution will undergo a reduction reaction on the surface of the electrode material, forming a layer of SEI film that is insoluble in organic solutions. The SEI film has an important impact on the initial capacity loss, safety, and cycle life of lithium-ion batteries. [0003]...

AI Technical Summary

Problems solved by technology

[0004] In order to alleviate the internal polarization phenomenon of lithium-ion batteries during the formation process and the formation of uneven SEI films due to the diffusion of lithium ions, the present invention provides a variable-frequency pulse formation method based on the optimal frequency of lithium-ion batteries. The polarization phenomenon of the ion battery during the formation process forms a uniform and dense SEI film, thereby improving the cycle performance of the lithium-ion battery and prolonging the service life of the lithium-ion battery

Images