An improved hybrid thermal management system for prismatic Li-ion batteries integrated with mini-channel and phase change materials

Battery thermal management systems play a significant role in the safety, performance, and maintenance of electric vehicles. This paper proposes a new hybrid cooling system incorporated with phase change material (PCM) and liquid cooling to achieve high performance and safety for the pack of prismatic batteries. Each four battery cells are grouped as a module and placed between vertically orientated mini-channel cold plates. PCM plates are also placed horizontally between the battery cells. This new design is simple enough to be implemented easily in common cooling systems and could provide parallel cooling of the active and passive methods with subsequent improvement in thermal performance and system safety. Three-dimensional numerical simulations are validated against previous empirical and numerical works. The thermal performance, power consumption, and safety of the hybrid cooling systems are investigated in a variety of battery discharge rates and mini-channel inlet velocities using different numbers of PCM plates. Also, the system performance is tested in a real driving cycle. This new design could notably improve the battery thermal management characteristics. The maximum battery temperatures in the hybrid system with three PCM plates at 2C and 3C discharge rates were 5.6 K and 16.2 K lower than those without PCM plates. Besides, adding three PCM plates reduced the temperature difference by up to 33 % at 3C discharge rate. Another key finding was that at 3C discharge rate, by simultaneously utilizing three PCM plates and decreasing the fluid inlet velocity, the power consumption per battery cell is reduced by 68 % (from 1.187 mW to 0.0375 mW). Furthermore, considering the PCM plates as the emergency backup, the time to reach the critical temperature increased by 38 % and 105 % in the systems with 1 and 3 PCM plates, respectively. Testing in a real driving cycle reveals the superiority of the hybrid system over the active cooling method by peak shaving of the thermal loads and reducing thermal fluctuations and maximum temperature. This novel design for battery thermal management could provide high performance for batteries and reduce fabrication and maintenance costs.