Lithium-ion batteries are extensively acknowledged as efficient devices for energy storage due to their capacity to function at elevated power levels while ensuring stability and reliability. Nonetheless, a significant obstacle in their real-world application is the heat generation that occurs during both charging and discharging processes, which can adversely impact performance, safety, and lifespan. Consequently, research into thermal management strategies has become crucial to facilitate the stable functioning of lithium-ion batteries. This study presents a numerical analysis aimed at investigating the cooling effectiveness of an Oil/Al₂O₃ nanofluid when utilized with a single lithium iron phosphate (LFP) battery. The research scrutinized a total of six parameters, including four dependent variables associated with the thermophysical characteristics of the coolant, one parameter related with the electrical current passing through the battery, as well as one independent variable related to the nanoparticle volume fraction. Simulations were conducted utilizing the commercial software ANSYS Fluent, maintaining the flow conditions at a constant Reynolds number. To assess the impact of nanoparticle concentration, pure oil was juxtaposed with Oil/Al₂O₃ nanofluid across three distinct volume fractions. The findings revealed that although an increase in nanoparticle concentration from 0% to 4% substantially improved heat transfer, resulting in approximately a 20% enhancement in both the average convective heat transfer coefficient and the Nusselt number, it significantly increases pressure drop along the battery chamber, which ultimately results in a slight decrease in performance efficiency of nanofluid.