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The liquid-cooled thermal management system based on a flat heat pipe has a good thermal management effect on a single battery pack, and this article further applies it to a power battery system to verify the thermal management effect. The effects of different discharge rates, different coolant flow rates, and different coolant inlet temperatures on the temperature distribution uniformity of the power battery system were analyzed, and the effectiveness of the flat heat pipe in improving the thermal equilibrium performance of the liquid-cooled thermal management system was verified.

Summary A thermal management system with the capability of achieving excellent heat dissipation is essential to the development of battery pack for transportation devices. To meet the temperature uniformity requirements of the battery pack, the plate flat heat pipe and liquid‐cooled coupled multistage heat dissipation system had been introduced. In this article, the research status of thermal management systems in battery pack was introduced. And the heat generation and heating power of the Li‐ion cell were studied. Then, the structure model of plate flat heat pipe system was proposed. Finally, the enhanced heat conduction effect of the thermal management system proposed in this article was comprehensively analyzed. Through the analysis of the results, in high discharge rates, the thermal management system proposed in this article could meet the temperature uniformity requirements of battery pack; also, the internal difference would reduce by 30.20%.

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Summary Battery, as the main energy storage element, directly affects the performance of electric vehicle. Battery thermal management research is required as the battery performance influenced by temperature obviously. This article selects liquid cold plate with different heat transfer enhanced fins as the research object. The angle and length of fins are chosen as the variables. Computational fluid dynamics (CFD) methods and experiments are used in this research. The fin angle of 15°, 30°, and 45° and fin length of 8, 10, 12 mm are selected to compose enhanced fins. The results indicate that heat transfer fins inside liquid cold plate can significantly decrease the highest temperature of battery module and temperature difference among cells. Otherwise, different fin angle and fin length can achieve different heat dissipation performance, which is not positive correlation. Then the design reference of heat transfer enhanced fin in liquid cold plate is offered.

To solve the problem of thermal runaway is one of the necessary conditions for the commercialization of lithium-ion batteries. In order to further explore the reaction mechanism of thermal runaway of lithium-ion batteries, a thermal model is built by using a variety of side reactions to further study the inhibition of temperature on thermal runaway. The results show that thermal runaway is triggered by the heat generation of negative material reaction when it is heated to 473.15 K; lower heat dissipation temperature (273.15 K) cannot effectively inhibit the occurrence of thermal runaway.

Summary Due to the sensitivity of the electrochemical performance of lithium‐ion batteries to temperature, the thermal management system becomes an essential component of pure electric vehicles. This paper selects a liquid‐cooled double‐layer battery pack for a certain car as the research object, determines the heating power of the battery cell through experiments, considers the existence of air domain in the battery pack to establish a battery pack thermal management system model, and analyzes the effects of different discharge rates, inlet flow rates, and inlet flow directions on the thermal performance of the double‐layer battery pack. The results show that the temperature of the upper module of the double‐layer battery pack is higher than that of the lower module at the same discharge rates and inlet flow rate; the maximum temperature of the upper module can be effectively reduced by increasing the liquid intake flow of the upper module. When the inlet flow rate of the upper module and the lower module is 550 and 500 L/hour respectively, the temperature distribution difference between the upper and lower modules of the double‐layer battery pack is the smallest, and the heat dissipation performance of the battery pack is the better. The conclusion can provide reference for structural design and optimization of thermal management system of the liquid‐cooled double‐layer battery pack.