Thermal performance of lithium-ion battery thermal management system based on nanofluid

As the power source of EVs (Electric Vehicles), lithium-ion power batteries have severe requirements for the temperature of the working environment, which makes BTMS (Battery Thermal Management System) very important. A liquid cooling BTMS for 18,650 lithium-ion batteries is established. In order to improve the thermal performance, nanofluids with high thermal conductivity are introduced as coolants, and various kinds of nanofluids are compared with water in terms of their cooling effects on batteries. The best performing is Cu water-based nanofluid, which decreases by 12.6% relative to water in terms of maximum temperature difference of the battery pack, and by 1.066 K in terms of maximum temperature. Then, the influence of various parameters of nanofluids on the thermal performance of BTMS has been studied. The results show that the maximum temperature difference and maximum temperature of the battery pack decrease with the increase of volume fraction and flow velocity of nanofluids, but the pressure drop increases accordingly. The decrease of nanofluid temperature can reduce the maximum temperature of battery pack by 10 K, and the effect is remarkable. But in the same way, it also destroyed the temperature uniformity of the battery pack, and the maximum temperature difference once reached 8.333 K. The influence of cooling channel structure parameters on the thermal per-formance of BTMS has also been studied. Under the same condition of nanofluid flow velocity, the increase in contact angle at the folded back of the cooling channel can improve space utilization, but will reduce the minimum temperature of the battery pack and disrupt the temperature uniformity.