Experimental Study of Heat Generation Rate during Discharge of LiFePO4 Pouch Cells of Different Nominal Capacities and Thickness

High manufacturing cost and thermal stability of Li-ion battery cells are currently the two main deterrents to prolific demand for electric vehicles. A plausible solution to this issue is a modular/scalable battery thermal management system (TMS). A modular TMS can ensure thermal reliability for battery cells of different capacities and size without needing major structural revision besides facilitating mass-production. However, understanding the relationship of heat generation rates with cell capacity and thickness is essential for developing a scalable TMS. The present paper discusses results derived from an experimental investigation undertaken with this purpose. Heat generation rates for LiFePO 4 pouch cells of different nominal capacities are measured at discharge rates of 0.33C, 1C and 3C in ambient temperatures ranging between ？10 and 50 °C using a custom-designed calorimeter. It is observed that heat generation rates of the LiFePO 4 pouch cells become independent of their nominal capacity and thickness if the ambient temperature is regulated at 35 °C. In ambient temperatures lower than 35 °C though, the thin battery cells are found to be generating heat at rates greater than those of thick battery cells and vice-versa at temperatures over 35 °C for all discharge rates. View Full-Tex