Experimental study on the thermal management of batteries based on the coupling of composite phase change materials and liquid cooling

To reduce the severe heat generation during high-intensity operation of battery pack, a heat dissipation module based on a composite phase change material (CPCM) and liquid cooling was constructed. CPCM was attached on the surface of the battery, and a cold water pipe was arranged in the CPCM. Different coupling schemes of CPCM and liquid cooling were realized by changing the hose connection mode. The flow and temperature of cold water were adjusted according to the principle of controlled variables, and the battery pack was charged and discharged. Based on the characterization of CPCM and analysis of charging/discharging data, it was found that: (1) paraffin (PW)/expanded graphite (EG)/high-density polyethylene (HDPE)/nano silver (nano-Ag) CPCM exhibited good thermal stability and low PW leakage rate. (2) The effect of battery thermal management system based on the combination of CPCM and liquid cooling for heat dissipation was much better than that of the system based on pure CPCM for heat dissipation, and the former system was found to be more suitable for cyclic charging and discharging of battery pack. (3) By simply changing the hose connection, different heat dissipation solutions of battery pack modules with coupling of CPCM and liquid cooling could be rapidly realized, and each solution had different operational effects. (4) The heat dissipation effect of the battery pack could be improved by increasing the flow rate and decreasing the temperature of input cold water. However, in terms of performance, the method of changing the flow through the variable pump was found to be more energy-efficient. In addition, when the battery pack emitted less heat, only the variable pump could be adjusted to achieve optimal cooling effect. When the battery pack was very hot or underwent high-intensity charging and discharging, the powers of variable pump and compressor must be simultaneously increased to achieve the best cooling effect.