Analysis of equivalent circuit models in lithium-ion batteries

Abstract

This study investigates lithium-ion (Li-ion) battery discharge at a constant current by comparing equivalent circuit simulation data with experimental data. The simulations employ Thévenin equivalent circuit models consisting of a resistance, capacitance, and power source. Voltage and resistance are measured during battery discharge at a constant 2 A direct current (DC). The experimental output results of the resistor-capacitor (RC) circuit are calculated and compared to the simulation results over the time of discharge. Both single and triple RC circuits are utilized in the experiment, with the triple RC circuit model demonstrating less error than the single RC circuit when compared to the simulated data. This study suggests that the output voltage of a Li-ion battery generally obeys a simulated Thévenin equivalent circuit model composed of the multiple RC elements under constant current discharge.