Thermoelectric coupling modeling of lithium-ion batteries operating under low-temperature domain

Accurate thermoelectric coupling model is essential to help to realize safe and reliable thermal management of lithium-ion batteries. In order to accurately estimate the temperature variation of lithiumion batteries operating under low-temperature domain, a lumped thermoelectric coupling model is established, which uses a second-order RC equivalent circuit model as the electrical model and a lumped mass model as the thermal model. By designing a hybrid pulse condition, the parameters of the electrical model are identified for different temperatures, C-rates, and SOCs. For the thermal parameters, the entropy heat coefficients at different temperatures and SOCs are identified using the potentiometric method, and a genetic algorithm is used to determine the specific heat capacity and convective heat transfer coefficient of the battery. To validate the efficacy of the proposed model, various pulse experiments are conducted under temperatures and C-rates. The maximum error in temperature is about 0.42°C for the 10C pulse condition at 0°C and 0.45°C for the 5C pulse condition at -20°C. Under the extreme low-temperature condition, i.e., at -40°C with 1C pulse rate, the average error obtained by the simulation is relatively only 1.59% when the temperature rise changes by only 1.2°C. These results fully demonstrate the accuracy and reliability of the modeling.