This study introduces an innovative, synergistically optimized coupled cooling design that enhances lithium-ion battery thermal management for electric vehicles, merging jet impingement with immersion cooling techniques. Utilizing Computational Fluid Dynamics (CFD) numerical simulation, distributed iterative optimization is conducted. Initially, the inlet and outlet configurations are determined. Subsequently, the number of jet pipes and the flow distribution are optimized. Finally, the diameters of the jet pipes are refined. This process aims to enhance heat transfer efficiency and reduce total input cost. The results indicate that a design with three inlets and one outlet, using an inlet flow rate of 0.075 kg/s alongside the flow rate of 0.025 kg/s, achieves optimal thermal performance for the batteries. This configuration reduces the maximum battery temperature and average temperature by 17.61% and 15.05%, respectively. Furthermore, an excessive or insufficient number of jet pipes is detrimental to cooling within the battery. Relying solely on mainstream inlet or jet pipe coolant for refrigeration is far less effective than proportionally distributing flow between the two. Selecting 6 jet pipes and a distribution ratio of 2꞉1 can reduce the maximum temperature by 10.10%. In contrast to adjusting jet pipe diameters, optimizing flow distribution exerts a more significant influence on battery cooling efficiency. Ultimately, the optimized solution, compared to the original design (with a flow rate of 0.025 kg/s), reduces the maximum temperature and average temperature by 26.41% and 10.61%, respectively. These improvements demonstrate the effectiveness of coupling jet impingement and immersion methods in battery thermal management, offering valuable insights for the future development of EVs battery cooling technologies.