Synergistic thermal management in lithium-ion batteries: A phase change material-silicone rubber foam composite for suppressing thermal runaway propagation

The propagation of thermal runaway (TR) in high-energy-density lithium-ion batteries remains an unresolved safety challenge, restricting the reliable deployment of electric vehicles and large-scale energy storage systems. In this work, we designed and fabricated a novel phase change material‑silicone rubber foam (PSF) composite with a multi-scale filler architecture via a facile foaming strategy. This composite integrates the flexibility and low thermal conductivity of silicone rubber with the high heat absorption capacity of inorganic phase change materials, while being reinforced by hollow glass microspheres, fumed silica, and montmorillonite. Structural, thermal, and mechanical characterizations collectively demonstrate that the optimized composite (PSF-3) exhibits remarkable thermal insulation, excellent flame retardancy (limiting oxygen index, LOI, up to 37.4 %; UL-94 V-0 rating), and outstanding mechanical robustness. Hot stage experiments and butane flame torch tests further reveal a prolonged “thermal plateau” effect during the phase change process, which effectively delays heat transfer under high-heat-flux conditions. More importantly, thermal runaway propagation experiments on lithium-ion battery (LIB) modules confirm that a 4 mm-thick PSF-3 completely suppressed cascading TR, whereas conventional aerogel insulation merely delayed failure. The triplex synergistic protection mechanism of “physical isolation-heat absorption buffering-thermal insulation” endows PSF composites with the capability to isolate and absorb large amounts of heat, dilute flammable gases, and maintain structural integrity under extreme thermal conditions. This study thus provides a promising strategy for the development of advanced thermal management and fire protection materials, offering critical technical support for enhancing the safety of lithium-ion batteries in electric vehicles and large-scale energy storage systems.