Investigating the Potential and Limitations of Cell Spacing Adjustment for Optimized Air-Based Battery Thermal Management Systems

Abstract

A reliable battery thermal management system plays a crucial role in the safe, efficient, and long-term operation of a high-performance lithium battery system. This study evaluates the temperature rise, pressure drop, capacity loss, and cyclical cost of an air-cooled battery system consisting of 90 cylindrical battery cells placed in a staggered arrangement in the module. The effect of spacing between the adjacent cells and inflow velocity is investigated for the battery system operating at high charge/discharge rates of 3C and 5C. The results demonstrate that the hybrid model, which consists of the battery life model integrated with the simplified modeling approach for the thermal evaluation of battery packs, provides a cost-effective tool for multi-objective analysis and optimization of air-cooled battery packages. The results reveal that the air-based cooling system has the potential to fulfill the safety standards in all studied cases, and employing battery modules with larger cell spacing at a constant inflow velocity may reduce the maximum temperature, pressure drop, and cyclical cost by up to 2.14%, 93.36%, and 35.69%, respectively, while extending the lifespan of the battery system by up to 55.45%. However, it is found that the air-based cooling system approaches its limit of thermal performance at high inflow velocities. A novel index (MCR index) is proposed in this paper to characterize the limitations associated with adjusting cell spacing for air-based battery cooling systems. It is observed that for systems with an MCR index beyond 600, the effect of cell spacing on thermal performance becomes negligible. This can be used as a useful guideline for optimizing air-based battery thermal management systems or integrating them with other cooling methods.