Abstract
Lithium-ion batteries (LIBs), which serve as the core energy carriers for electric vehicles and energy storage systems, are highly dependent on temperature control for their performance and safety. Traditional thermal management systems and thermal runaway (TR) suppression mechanisms face challenges in balancing heat dissipation efficiency and energy consumption, while passive thermal management technologies based on phase change materials (PCMs) have become a research hotspot due to their advantages of high latent heat storage capacity and energy-free operation. However, pure PCMs suffer from issues like low thermal conductivity, phase separation, and leakage, which severely limit their applications. To address this, Composite PCMs have been developed by incorporating thermally conductive enhancers, structural support materials, and encapsulation technologies, significantly improving thermal conductivity, shape stability, and reliability. Furthermore, hybrid system integration strategies encompass PCM-Air, PCM-Liquid, and Heat Pipe-PCM systems. These configurations achieve synergistic thermal buffering and active cooling through coordinated effects, providing improved temperature control performance and TR suppression capabilities under high-power operation. This review provides a comprehensive and critical overview of PCM-based battery thermal management, with particular emphasis on the latest advances in flame-retardant and intumescent composite PCMs that not only maintain excellent temperature uniformity during normal operation but also actively prevent thermal runaway propagation in battery packs under abuse conditions. Key focus areas include material-level flame-retardant design strategies and hybrid system integration. This review connects material enhancement strategies with hybrid thermal management performance and distinguishes routine temperature regulation from abuse specific evidence of thermal runaway mitigation, thereby providing an integrated framework for evaluating PCM-based battery thermal management technologies.