The Frequency-Domain Impedance Model for a High-Rate Pulse-Discharged Lithium-Ion Battery Pack

In this article, the impedance characteristics of a lithium-ion battery pack under the high-rate periodic pulse discharge are studied. The impedance transfer function of lithium-ion batteries in the electrochemical reaction process is derived from the reaction mechanism of the high-rate periodic pulse-discharged lithium battery, and the frequency-domain impedance model is established. The frequency response characteristics of lithium-ion batteries at low frequency and high frequency are analyzed. Finally, model validation and impedance extraction are carried out on the battery test data under low- and high-frequency pulse discharge conditions. The results show that the frequency-domain impedance model can well simulate the frequency-domain characteristics and dynamic behavior of the lithium-ion battery (pack) under the high-rate periodic pulse discharge, and the impedance extraction based on the harmonic analysis method can achieve good modeling accuracy.