Enhanced heat transfer in battery thermal management system: A comparative review of single-phase and two-phase approaches

Lithium-ion batteries are the main power source for electric vehicles and play a critical role in decarbonizing the transportation sector. However, their performance, durability, and safety are highly sensitive to temperature. Therefore, effective battery thermal management systems (BTMS) are essential for maintaining the inter-cell temperature within its acceptable range and minimizing temperature non-uniformity. This review provides a comprehensive and quantitative analysis of the currently available BTMS technologies, with a focus on single-phase and two-phase cooling strategies. The fundamentals of heat generation from a battery, and the currently available single-phase cooling approaches and two-phase cooling approaches, are first reviewed in sequence. Second, the reported maximum battery temperature, T m a x , and temperature non-uniformity, Δ T collected from the literature, are normalized with respect to operating and ambient conditions. The normalized databases comprise over 700 data points collected from literature, enabling a quantitative comparison of different BTMS. Then, a statistical comparison is performed across different BTMS and C-rates under normal operating conditions. Conversely, the cooling performance and operating limits of single-phase and two-phase approaches are also evaluated under the abuse conditions. The results show that two-phase indirect and immersion cooling generally provide great overall cooling performance, achieving low Δ T m a x and Δ T over a range of C-rates. Meanwhile, single-phase cold-plate liquid cooling is more suitable for low to moderate C-rate applications. The findings of this review offer guidance for future BTMS design and highlight key research needs for managing the higher heat loads of next-generation high-energy-density lithium-ion batteries and emerging solid-state batteries. • A systematic review of single-phase and two-phase battery thermal management strategies for electric vehicles is presented. • Quantitative analysis based on maximum temperature and temperature non-uniformity across BTMS and C-rates is conducted. • Cross-comparison of normalized temperature data clarifies the application scenarios of single-phase and two-phase BTMSs. • Two-phase indirect and immersion cooling generally satisfy single-phase BTMSs at high C-rates.