A discharging internal resistance dynamic model of lithium-ion batteries based on multiple influencing factors

Direct current internal resistance (DCR) is a key indicator for assessing the health status of batteries, and it is of significant importance in practical applications for power estimation and battery thermal management. The DCR of lithium-ion batteries is influenced by factors such as environmental temperature, state of charge (SOC), and current rate (C-rate). In order to investigate the influence of these factors on battery DCR, this paper proposes a DCR dynamic model of lithium-ion battery based on multiple influencing factors (multi-factor). The model utilizes a binary quadratic polynomial to perform least squares fitting of the DCR with respect to environmental temperature and battery SOC. The obtained coefficients of the binary quadratic polynomial are then fitted with a cubic polynomial with respect to the C-rate, thus establishing the relationship between DCR and C-rate, environmental temperature, and SOC. Multi-rate hybrid pulse power characterization (HPPC) experiment is conducted to perform charging-discharging tests on lithiumion batteries. The experimental results demonstrate that the RMSE between the estimated DCR obtained from the established model and the experimental values is 0.9758 mΩ, confirming the effectiveness of the proposed DCR model.