A novel parameters acquisition method based on electrochemical impedance spectroscopy mathematical model in lithium ion cell

Electrochemical impedance spectroscopy (EIS) is a widely used technique in presenting the complex impedance character in the frequency domain of the lithium-ion cells, and it can be used to decouple the interfacial reaction, species transport, and lithium ion diffusion process effectively. Meanwhile, it also can be used to provide the support for judging the health status of the cells. The EIS mathematical model can precisely reflect the internal reaction mechanism in lithium-ion cells. Using the model, the cell parameters can be obtained without disassembling cells, with the help of parameter identification technology. In this paper, Genetic Algorithm considering the parameter sensitivity analysis is used to identify the parameters. A novel identification strategy, which distinguishes different parameters in different frequency ranges, is proposed in detail. Finally, the application of the EIS mathematical model in studying the variation trend of the cell parameters with the aging of the cells is shown.