Experimental study on thermal management of lithium-ion battery with graphite powder based composite phase change materials covering the whole climatic range

In order to ensure the normal operation of lithium-ion battery in any climate environment, it is necessary to explore the temperature dependence of lithium-ion battery performance, and adopt an effective and low energy thermal management system to maintain the temperature of lithium-ion battery within the normal operating temperature range. In this paper, the temperature dependence of heat generation behavior and charge-discharge performance of lithium-ion battery was studied, and the critical temperature of heat preservation and preheating process was determined. On this basis, graphite powder/paraffin composite phase change material and graphite powder/paraffin/nickel foam ternary composite phase change material with optimized composition were pre -pared. The thermal management experiment of large-capacity rectangular lithium iron phosphate battery covering the whole climatic range was carried out. The performance of the following thermal management modes was compared: air natural convection, paraffin, graphite powder/paraffin composite, graphite powder/ paraffin/nickel foam ternary composite. The experiment showed that the necessary heat dissipation of lithium-ion battery was needed at 20 degrees C and 40 degrees C to avoid exceeding the upper limit of normal working temperature. The charge-discharge performance of lithium-ion battery was very sensitive to low temperature environment, especially the battery endurance and charge-discharge capacity. Both graphite powder/paraffin and graphite powder/paraffin/nickel foam composites can effectively control the surface temperature rise of lithium-ion battery, and keep the surface temperature above 0 degrees C for at least 40 min in the extremely cold environment of-20 degrees C. They also had similar heating efficiency. However, the ternary composite had better temperature ho-mogeneity in both the high temperature environment of 40 degrees C and the extremely cold environment of-20 degrees C. The maximum temperature difference of ternary composite in the preheating process was 21.43% lower than that of binary composite.