A novel immersion cooling strategy for improving the thermal performance of lithium-ion battery packs

As electric vehicles proliferate, safeguarding the performance and safety of lithium-ion batteries (LIBs) has become crucial. To address this, a regionalized pulse-based liquid immersion battery cooling system is developed, and a novel dual-pulse synergistic cooling strategy is proposed. The impacts of different flow rate, different channel structures, different pulse methods and output ratios across distinct regions on the battery module's performance are investigated numerically. For the stepped layered baffle arrangement, the LIB maximum temperature decreases as the inlet flow rate increases, but with diminishing returns. At a 3C rate, compared with the no baffle and uniform layered baffle arrangement, the stepped layered baffle arrangement reduces the maximum temperature by 7.5 % and 4.7 %, respectively, and decreases the maximum temperature difference by 22.5 % and 12.2 %, respectively. Furthermore, for a given output ratio, the dual-pulse synergistic cooling method delivers superior thermal stability and uniformity compared with the conventional pulse method. Considering the trade-off between cooling and pressure drop, the dual-pulse synergistic cooling method is preferred, especially at a 20 % output ratio, where its time-averaged performance evaluation criterion (PEC) reaches a maximum value of 1.09. Moreover, under the dual-pulse synergistic cooling strategy, among output ratio allocations targeting different module regions, scheme 2 achieves the highest time-averaged PEC, exceeding schemes 1 and 3 by 6.6 % and 7.8 %, respectively. This indicates that prioritizing the battery module's middle region yields the best overall performance.