Performance comparison of phase change material/liquid cooling hybrid battery thermal management system under different cyclic charging-discharging mode designs

Hybrid battery thermal management systems coupling phase change material with liquid cooling are considered promising in thermal safety guarantee of lithium ion battery packs during long operating cycles. However, long-term performance comparisons of the reported hybrid battery thermal management systems in the literature are difficult. The main reason is that they have employed different cyclic charging-discharging mode designs, but the influential mechanisms of the mode designs on the heat dissipation performances of the hybrid battery thermal management systems are still unclear. In this work, thermal behaviors of the lithium ion battery pack during different cyclic charging-discharging processes are simulated to elucidate the influential mechanisms of cyclic charging-discharging mode designs on the cooling performances of the hybrid battery thermal management systems. High C-rates are employed for both charging and discharging processes considering the more significant cooling demand under harsh conditions. The results demonstrate that in the charging-discharging mode designs, rest interval before the discharging process is vital to control temperature rise during the cyclic processes, while effects of rest interval after the discharging process are weak. Consequently, compared with the rest interval number, position of the rest interval in the cyclic charging-discharging processes is more important in the improvement of system thermal performance. Further, universality of the conclusions under different material properties and working conditions is also examined. This work could provide useful guidance for not only the performance comparison of the hybrid battery thermal management systems reported in different studies, but also the future designs of the cyclic charging-discharging tests.