The study focusses on optimising the cooling of lithium-ion batteries using a direct contact liquid-based immersion cooling system. Lithium-ion batteries are significantly influenced by the temperature with an operational limit of 35 °C and an inter electrode temperature difference less than 3.5 °C for prolonged service life. The paper uses a resistance-based energy model to simulate battery temperature during discharge, while cooling the arrangement using a commercially available dielectric. The study explains the vortex activity that occurs as the fluid traverses the battery module. The simulation reveals an undesirable thermal gradient over the cell surface due to the construction of the battery stack. To mitigate this effect, vortex generators (VG) are introduced that alter the flow behaviour and reduce the temperature difference formed on the battery surface. By altering the position of the vortex generators, the corresponding change in fluid behaviour, the vorticity magnitude, and the average Nusselt number is established. Two key indices: the cooling uniformity index and pumping power index are introduced to quantify the thermal gradient on the cell surface and the total pressure loss as the fluid flows through the system. The findings indicate that a middle-positioned VG produces the most favourable cooling index of 0.18 which corresponds to a maximum reduction in temperature difference of 1.65 °C and a pumping power index of 0.14 showcasing the most effective cooling performance.