ABSTRACT
This chapter describes the internal structure of lithium battery. The equivalent impedance of lithium battery is obtained by the principle of electrochemical impedance spectroscopy. Lithium battery is the most potential EV battery in the field of EV. On the basis of AC impedance method, the measurement of the lithium batteries internal resistance is based on the sampling integral method. The four-line method is used to measure the output current signal, and the frequency impedance spectrum of the lithium battery is obtained from the ratio of the different voltage signal to the current signal. Electrochemical Impedance Spectroscopy can reflect the subtle changes of lithium batteries, especially the study of battery materials; therefore, it is very important to establish the equivalent model of the battery. The internal resistance of lithium battery is a resistor in the actual operation, so it can be equivalent to a value in simulation.
