<p>Ensuring the safety and performance of lithium-ion batteries (LIBs) is a significant challenge for electric vehicles. To tackle this issue, an innovative liquid-immersed battery thermal management system (LIBTMS) using bionic baffles with fish-like perforations is developed. The thermal-flow-electric coupling characteristics of LIBTMSs with different baffle structures (no baffle, conventional baffle, baffle with circular perforations and baffle with fish-like perforations) are systematically investigated using experimental and numerical methods. The results indicate that the forced flow scheme exhibits better thermal management performance and voltage equalization than static flow. Moreover, the LIB temperatures and voltage deviations of different LIBTMSs increase quickly with increasing discharge rates. More importantly, the innovative LIBTMS exhibits the best thermoelectric performance due to its excellent thermoelectric equilibrium behavior caused by high electrical and temperature consistency, as well as the best overall performance involving the balance between the pressure loss and heat transfer capacity of the system. Compared with other structures, the innovative LIBTMS using baffles with fish-like perforations exhibits a maximum reduction of 10.1%, 15.2%, 25.8% and 9.0% in LIB maximum temperature, maximum temperature difference, system pressure drop and voltage deviation, respectively, under the same operating conditions. Furthermore, for the LIBTMS using baffles with fish-like perforations, the bottom inlet and top outlet configuration and coolant precooling are suggested to enhance cooling performance.</p>