Due to the low cost of the battery cells and excellent performance at ambient temperature, Lithium-ion (Li-ion) battery is a promising technology for propulsion applications. However, the performance of Li-ion batteries erodes drastically at extreme temperatures (above 65 °C or below 0 °C). Therefore, in order to maintain battery life and performance, it is crucial to keep the batteries within the temperature range where their operating characteristics are optimal. The need for expensive and complex thermal management systems has in fact kept the Li-ion technology from becoming the first choice for Hybrid Electric Vehicle (HEV) applications. In this paper, we propose a Phase Change Material (PCM) for the temperature control.
Due to its high heat capacity, PCM absorbs the heat dissipated by the battery. As long as the heat emitted by the battery does not melt the PCM completely, the system is stable. In this paper, the performance of high-energy Li-ion batteries with a novel thermal management system that uses PCM for temperature control is compared to the Nickel Metal Hydrate (NiMH) batteries currently used in Toyota Prius and Honda Insight HEVs. The battery model is developed using the advanced vehicle simulator (ADVISOR) software, a Matlab/Simulink based software developed by the National Renewable Energy Laboratory (NREL), and validated experimentally. Thermal stability of the batteries is examined using Finite Element Analysis (FEA) for different environmental conditions, driving patterns, and control strategies. Taken together, our results implicate that the PCM is a cheap and reliable thermal management solution. Due to its low thermal conductivity, PCM is more effective if coupled with Aluminum fins and Aluminum foam.