Lithium ion battery service life estimation method based on alternating-current impedance imaginary part

Abstract

The invention discloses a lithium ion battery service life estimation method based on an AC impedance imaginary part. The method comprises the following steps: 1) selecting a large number of unaged battery samples, and testing the AC impedance spectrum and capacity value of the battery at different aging stages; 2) calculating a battery AC impedance imaginary part value Z''; 3) establishing a relation table between the battery AC impedance spectrum imaginary part Z'' and the service life under a specific frequency fj according to the test data; and 4) estimating the service life of other batteries with unknown service life according to the relationship between the battery AC impedance imaginary part Z'' and the service life under the specific frequency fj. According to the invention, the service life of the battery is estimated by using the impedance spectrum imaginary part under the specific frequency, and only the impedance test of the battery under the single frequency needs to be performed, so that the AC impedance test time can be greatly shortened, and the service life estimation speed can be effectively improved; and the influence of the contact resistance of the lithium ionbattery on the real part of the impedance spectrum can be eliminated, and the lithium ion battery service life estimation precision can be improved;

Description

technical field [0001] The invention relates to a battery detection technology, in particular to a lithium ion battery life estimation method based on the imaginary part of AC impedance. Background technique [0002] Li-ion battery life is an important fundamental performance parameter for electric vehicle batteries. Lithium-ion batteries are affected by many factors during use, and their lifespan will be attenuated to varying degrees. The lifespan attenuation of lithium-ion batteries is mainly manifested in the reduction of capacity and output power, which directly affects the safety of electric vehicles. For example, the reduction of capacity will shorten the mileage of electric vehicles, and at the same time increase the breakdown rate of electric vehicles, so that electric vehicles cannot meet the travel needs of drivers; the reduction of output power will affect the acceleration and climbing performance of electric vehicles, which is a serious threat The life safety of...

AI Technical Summary

Problems solved by technology

[0003] Although many researchers have conducted a lot of research on the life estimation of lithium-ion batteries, there are still many defects in the existing life estimation methods.

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