The present study aims to optimize the structural design of a Z-type flow lithium-ion battery pack with a forced air-cooling system known as BTMS (battery thermal management system). The main goal is to minimize Tmax (maximum temperature) and ΔTmax (maximum temperature difference) while ensuring an even airflow distribution within the battery module. The present study thoroughly investigates critical factors, such as the inlet air velocity, tapered inlet manifold, and the number of secondary outlets, to evaluate their impact on thermal performance and airflow uniformity within the battery module. Increasing the inlet air velocity from 3 to 4.5 m/s significantly improves the thermal cooling performance of the BTMS, resulting in a decrease of 4.57 °C (10.05%) in Tmax and 0.29 °C (9.79%) in ΔTmax compared to the original 3 m/s velocity. Further, the study assesses the significance of a tapered inlet manifold as a critical factor, revealing its substantial impact on cooling performance and temperature reductions in battery cells 3–9. It also facilitates a more uniform airflow distribution, decreasing the velocity difference between channel 9 and channel 1 from 3.32 to 2.50 m/s. Incorporating seven secondary outlets significantly improves the heat dissipation ability of the BTMS, resulting in a decrease of 0.894 °C (2.18%) in Tmax and 2.23 °C (72.84%) in ΔTmax compared to the configuration with 0 secondary outlets. By optimizing these parameters, the aim is to enhance BTMS's capabilities, improving LIB (lithium-ion battery) packs' performance and reliability. The optimized structural design parameters proposed in this study yield practical applications that extend beyond theoretical insights, impacting diverse fields reliant on lithium-ion battery technology. Through enhanced thermal management systems, applications in electric vehicles and portable electronics are poised to experience improved performance and longevity. Furthermore, these advancements inform the development of next-generation battery packs, promising reduced overheating risks and extended battery life. Such innovations are critical in energy storage systems for renewable energy applications and electric vehicle technology, facilitating faster charging times and increased driving range. Moreover, the implications extend to aerospace applications, ensuring the reliability of batteries in extreme environmental conditions.