Cooling and preheating behavior of compact power Lithium-ion battery thermal management system

A novel honeycomb battery thermal management system with a combination of liquid-cooling and composite phase change material has been proposed for the cylindrical power lithium-ion battery to improve the cooling effect under harsh discharge conditions and the capacity reduction in low-temperature environment. The cooling and preheating performance have been compared at a discharge rate of 4C for three different monomer battery systems without any heat dissipation elements, with passive composite phase change material, or with hybrid cooling elements. The effects of the thickness of composite phase changed material, the size of micro-channel, the channel level number, the flow velocity of inlet liquid and the heating strategy on the cooling behaviour of the monomer battery are studied and examined. Furthermore, the impacts of inlet/outlet arrangement mode and inlet liquid flow velocity on the thermal behaviour of the cell module are analysed. When the environment temperature is 40 °C, the optimal parameters on thermal performance are decided, which reliably control the highest temperature, cell–cell temperature difference and the mass fraction of liquid phase of composite phase change material within an allowable range, and save the space of the module as much as possible. At the discharge rate of 4C and the coolant inlet flow velocity of 0.06 m/s, the highest temperature and cell–cell temperature difference of the module can be controlled at 46.21 °C and 3.5 °C, respectively, and keep the mass fraction of the liquid phase of composite phase change material at around 55% after battery discharge. When the battery module is heated from −15 °C to 10  ° C, there are different optimal pulse width modulation heating strategies for 20 W and 10 W heating belts and the battery module can be rapidly heated in about 6 min.