In this study, a battery thermal management (BTM) system immersed in a silicone sealant (SS) is designed for an 18650-type lithium-ion power battery. When compared with a general water-cooled BTM system, the novel BTM system with a simple structure can provide effective heat dissipation and long-term corrosion protection. The thermal performance of. ••BN/silicone composite sealant for battery thermal management system is proposed.••The thermal and waterproof properties of BN based composite sealant are analyzed.••BN based composite sealant apply in immersion liquid cooling for battery module.••Composite sealant immersion cooling exhibit excellent balance temperature capacity.Battery thermal management systemSilicone sealantThermal performanceWater imperviousnessWith the increasing consumption of fossil fuels and excessive burning of non-renewable energy sources increasing the environmental pollution, the problem of energy shortage has gradually become more prominent in the recent years. Energy from fossil fuels is being consumed by both industries and automobiles in large amounts every day. Electric vehicles (EVs) and hybrid EVs, a recent technological development, can likely replace fossil fuel vehicles as an alternative to reduce fossil fuel consumption and reduce greenhouse gas emissions. As the manufacturing technologies for EVs and hybrid EVs have matured in recent years, they have become a frequently researched topic of late [1,2].Lithium iron phosphate is the predominant component of Li-ion batteries used in EVs. Currently, Li-ion batteries are being used in EVs because of their several advantages such as long-life cycle, stable charging capacity, and wide operating temperature range [,, ]. However, since these batteries are very sensitive to high temperatures, it impacts their lifespan, safety, and reliability [6,7]. For security reasons, a battery thermal management (BTM) system is needed to maintain the batteries within an optimal temperature range that offers a good balance between performance and aging. Meanwhile, other studies have demonstrated that the capacity and life of batteries reduce. 2.1. Preparation of SS composite materialsThe SS composite materials were prepared by improving the traditional physical mixing method, as shown in Fig. 1(a). First, equal quality of SS A and SS B (Guangzhou Tolerance Electronic Materials Co. Ltd) was mixed thoroughly in a beaker by stirring continuously for 30 s for even mixing. Afterwards, the BN powder (Hebei Xinnai Materials Co. Ltd; 0, 5, 10, and 15 wt%) was added slowly into the pre-mixed SS solution. The beaker was then placed in a water bath at 10 °C ± 0.5 °C, and then mixed using an electric stirrer at a speed of 1000 rad/min for 10 min. As the BN powder was added, heat was gradually generated by friction during the stirring process, which effectively accelerated the solidification of SS. The role of the water bath was to absorb part of the heat caused by the stirring process and thereby slow down the curing speed of the SS/BN composite materials. After stirring, the SS/BN composite was poured into a container, solidified overnight, and then released from the container to obtain the solid SS/BN composite materials.2.2. Experiment setupFig. 2(a) shows the schematic of the experimental platform that measures the.