Enhancing air-cooled Li-ion battery pack performance via transverse cell spacing

This study uses numerical simulations to evaluate an air-cooled battery thermal management system (BTMS) for electric vehicles, examining the impact of transverse cell spacing ( T / D ) on a 4P7S lithium-ion battery pack. The simulations in ANSYS Fluent varied T / D from 0 (inline) to 1 (staggered), inlet air velocities from 0.5 to 2 m/s, and discharge rates from 0.5C to 3C, incorporating Bernardi’s heat generation model. The results show that a fully staggered layout ( T / D = 1 ) can lower the maximum cell temperature by about 9 K at 3C, compared to the inline, mainly due to better airflow mixing and less thermal interference. Near-isothermal behavior (305–308 K) are maintained at 0.5C and 1C charges, but temperatures increase to 329 K at 3C, indicating that air cooling alone may be inadequate under heavy loads. Increasing the air velocity from 0.5 m/s to 1 m/s cuts the peak temperature by 20.5 K, with negligible benefits above 1 m/s. The staggered configuration also increases temperature uniformity, especially in downstream cells, underscoring the importance of cell spacing and airflow optimization for enhanced BTMS performance, which influences battery safety, longevity, and future thermal management designs.