Studies on thermal management of Lithium-ion battery pack using water as the cooling fluid

Study of battery thermal management is critical for safe and better performance of Lithium-ion batteries, considering several recent battery failures and explosions. Lithium-ion batteries are generally used in stacks to meet the high energy requirements. Thus, the heat generated in a battery pack must be properly managed for efficient operation. A battery thermal management system (BTMS) is an ideal tool to understand the thermal health of a battery. An attempt is made here to study the influence of water as the coolant on the battery thermal management. A variable heat generation that depends on the discharge rate is assumed in the simulations. A 5C charge/discharge rate (per hour) per battery and two packs of 5 batteries each are considered for the analysis. Due to symmetry only half pack (2.5 batteries) with symmetry boundary conditions is considered in the simulations. The influence of volume flow rate, flow direction, and contact area on the battery thermal behaviour are analysed. Results indicate that a 5C charge/discharge produces maximum temperatures of 319.31 K and 316.93 K at flow rates of 0.25x10(-6) m(3)/s and 1.6x10(-6) m(3)/s, respectively. Whereas, the uncooled batteries with 5C charge/discharge produces a maximum temperature of 336.623 K. Therefore, the uncooled peak temperature is estimated to be reduced by 5.85% by circulating the coolant at 1.6x10(-6) m(3)/s. Furthermore, by reversing the direction of water flow in one of the channels, leads to redistribution of heat and hence the temperature distribution in the battery pack is observed to be more uniform. Flow reversal also helped to reduce the peak temperatures by 2.77 K in the battery pack. All the calculations are performed using the commercial software COMSOL.