Thermal Model of Heavy Truck Swapping Station Battery Considering V2G

[Objective] The heavy-duty truck swapping station addresses challenges such as long charging times and limited driving range in electric heavy-duty trucks, the power battery faces issues of large capacity, high frequency of use, and a heightened risk of thermal runaway. [Method] To solve the above problems, a coupled bidirectional charging machine's battery thermal-electric coupling model was established to investigate the thermal characteristics of the electric heavy-duty truck's power battery, and the COMSOL-SIMULINK was used for joint simulation. [Result] The results indicate that the proposed coupling model can effectively control the voltage and current of the battery under V2G operating conditions. In the early stages of the V2G condition, the maximum current density is at the junction of the positive electrode and the positive electrode tab. The temperature of the positive electrode tab is significantly higher than the cell temperature, with a temperature difference of 4.1 ℃.In the later stages of the V2G condition, the maximum local current density shifts from the electrode tab towards the bottom of the battery. The bottom region, influenced by concentration, favors electrochemical reactions, the cell temperature is higher than the electrode tab temperature. Under abusive thermal conditions, the sequence of secondary reactions includes the decomposition of the SEI membrane, negative electrode decomposition, and positive electrode reaction with the electrolyte.Among these reactions, the heat generated by electrode secondary reactions is the main cause leading the battery into irreversible thermal runaway. The decomposition reaction of the SEI membrane is an indicative sign of the initiation of thermal runaway in the battery. [Conclusion] The proposed external circuit thermoelectric coupling model can reflect the temperature distribution and thermal runaway effects of the battery thermoelectric coupling model under the excitation of the bidirectional charger in the heavy-duty truck exchange station.