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• Battery thermal management is studied with phase-change materials and heat pipes; • Phase change materials improve the temperature uniformity of the battery pack; • Phase change-heat pipe cooling reduces by 22.3% battery temperature than using air; • Phase change material RT31 reduces by 11.8 % battery temperature at 5–50 W·m−2·K−1; • Short circuit of combination cooling reduces by 29.9% temperature than air cooling. Lithium-ion battery packs generate high-level heat under harsh and rigorous conditions. The inadequate heat dissipation results in high pack temperature above the safe operating range. This study investigates an efficient and cost-effective battery thermal management system based on phase change materials and a micro heat pipe array. The battery is treated as a single domain. A battery pack with six series stacked batteries is analyzed using the Newman-Tiedemann-Gu-Kim model. The thermal performance of a battery thermal management system is analyzed using phase change materials with various melting temperature values, ambient temperature, and convective heat transfer coefficients of micro heat pipe arrays. Results show that the maximum temperature of the cooling system with micro heat pipe arrays and phase change materials is 33.8 °C, which is reduced by 22.3 % and 7.8 % compared to the air-cooled and cooling system with micro heat pipe arrays. At forced convection of 50 W·m−2·K−1, the maximum battery temperature values for the phase change material RT31, RT35, and RT42 are reduced by 11.8 %, 8.9 %, and 5.4 % compared to those at forced convection of 5 W·m−2·K−1. Under short-circuit conditions, the cooling system with micro heat pipe arrays and cooling system with micro heat pipe arrays − phase change materials reduce the maximum battery temperature by 12.4 % and 29.9 % compared to the air-cooled system. Results show that the developed model for the battery thermal management system provides a reference for designing phase change materials with micro heat pipe arrays. [ABSTRACT FROM AUTHOR]

• The heat generation model for cylindrical Li-ion battery was built. • A liquid immersion cooling battery pack containing 60 batteries were established. • At 2C discharge rate, 0.5 L/min flow rate was recommended. • The battery pack can address localized high-rate discharge events (4.5C or 6.5C). • Liquid immersion cooling BTMSs have great heat dissipation performance. With the increasingly severe challenges of the thermal management of battery packs for electric vehicles, the liquid immersion cooling technology has gradually attracted more attention due to its superior characteristics such as high heat dissipation efficiency, well temperature uniformity and low risk of thermal runaway. To investigate the heat transfer characteristics of the liquid immersion cooling BTMSs, the 3D model of the 60-cell immersion cooling battery pack was established, and a well-established heat generation model that leveraged parameters derived from theoretical analysis and experiments was incorporated into the 3D simulation to analyze the thermal characteristics of battery pack. The simulation results showed that under the discharging rate of 2C, even with the lowest coolant flow rate in this work (0.2 L/min), no localized abnormal overheating within the battery pack was observed, and the highest temperature was 34.22 °C. The temperature uniformity within the battery pack improved with the increase of the coolant flow rate. It was recommended to maintain a flow rate above 0.5 L/min to ensure a temperature difference below 5 °C. The experimental apparatus of the immersion cooling battery pack was also developed to explore the heat dissipation and temperature uniformity at 2C discharge rate. The simulation results were in well agreement with the experimental results, with the deviation less than 0.43 °C when the flow rate exceeded 0.6 L/min. The effect of the localized high-rate discharge events (4.5C and 6.5C) at different battery pack locations on temperature distribution and uniformity was further discussed based on the verified 3D model. The results suggested that liquid immersion cooling systems offered promising potential for achieving both efficient heat dissipation and preventing thermal runaway in battery packs. [ABSTRACT FROM AUTHOR]

• A 35kWh battery pack with a novel hybrid thermal management system is prototyped. • Phase change material is innovatively integrated with cooling plate. • The battery thermal management at the battery pack level and module level is studied. • Both cooling and thermal insulation performances are investigated. • Desirable control strategies are obtained for battery pack under 0.5C to 1.5C discharge rates. Controlling the temperature of a battery pack within an optimal range and ensuring uniform temperature distribution are the key to improving battery life. With the elevating energy density of batteries, more efficient and energy-saving thermal management system is urgently required for improving electric vehicle (EV) performance in terms of safety and long-term durability. In this work, a novel hybrid thermal management system towards a high-voltage battery pack for EVs is developed. Both passive and active components are integrated into the cooling plate to provide a synergistic function. A 35kWh battery pack incorporated with electrical, mechanical and thermal management components was designed, manufactured and integrated. As the core hardware, a pack-level cooling plate set was innovatively designed by integrating with phase change material (PCM). The results show that the combined passive and active cooling strategy ensured a desirable working temperature below 40˚C and a uniform heat distribution across the entire pack at discharging rates ranging from 0.5C to 1.5C under customized control strategies. Moreover, the cycling performance of air cooling and hybrid cooling, as well as the thermal insulation performance at both battery module level and pack level are compared, demonstrating the superior thermal management capability of the hybrid solution. [ABSTRACT FROM AUTHOR]