Thermal Management of a LiFEPO4 Battery Pack in a Cold Temperature Environment Using Phase Change Materials (PCMs)

A substantial amount of heat is dissipated during the discharging process of lithium-ion batteries (LIBs) affecting an increase in surface temperature and lifetime deterioration and initiating an explosion inside the car and planes in extreme conditions. The application of LIBs in a cold climate condition may add additional problems to the above conditions such as low thermal conductivity of the cell materials inside the battery and elevated graphite anode polarization which affect the battery pack performance. Phase change materials (PCMs) can help in controlling the battery pack surface temperature by absorbing the extra heat during phase transition from the system during discharging time and releasing the heat to the environment during the charging and off-time of the batteries. It can also work as an insulation for the battery pack during low-temperature operating conditions. In this study polyethylene glycol 1000 (PEG1000) with phase transition range of 35-40 degrees C has been used as a PCM to control the surface temperature of a LIB pack model LiFEPO4-38120 at ambient and cold temperatures (- 20 degrees C). Aluminum meshes have been added to the system to enhance PCM thermal conductivity and system heat transfer. Experimental runs have been conducted at ambient and cold temperature conditions using a freezer at various rates of 1-3C. The research findings indicate that using a composite of PCM and aluminum meshes between the cells can control the surface temperature and indicates better performance and temperature uniformity especially at very cold temperature environment. The maximum cell temperatures have been reduced by 19-26% at room temperature and 16-31% at low temperature conditions.