A novel hybrid battery thermal management system using a wavy minichannel and a composite phase change material

A novel hybrid battery thermal management system (BTMS) coupled with a wavy minichannel (WMC) and a composite phase change material (CPCM) is introduced and experimentally investigated for cylindrical Li-ion cells under discharging rates of 3C and 5C. The CPCM includes PA, OBC and h-BN for providing a high energy storage capacity, good temperature stability and thermal management effectiveness. Detailed material characterization and mechanical properties were carried out on the CPCMs. The experimental results validated the effectiveness of the use of CPCM for thermal management. Heat transfer experiments showed that using a low fluid flow rate (1.0 Lmin^-1) under experimental conditions could meet the heat dissipation needs from the batteries to the flowing fluid through the WMC. The effect of using the WMC and/or the CPCM was also experimentally investigated regarding the maximum battery temperature (T_max) and temperature difference (ΔT) across the battery. Although the use of the WMC significantly reduces the T_max, it could not prevent the increase in the ΔT because heat cannot be dissipated from the entire surface of the battery. Using a hybrid solution based on both the WMC and the CPCM could effectively keep the battery temperature during 3C and 5C discharge rates. The best case for the BTMS for the discharge rate of 5C is concluded as Case_3_CPCM_3 with the T_max of 33.45 °C, while the battery pack has exceeded the safe limit of 40 °C, with its capacity being only 50 %. The ΔT could be kept under the safety temperature limits for a 3C discharging rate, while the ΔT could not be reduced to the desired temperature value for 5C discharging, which requires further research for such a fast-discharging scenario.