Mechanism of heat transfer suppression and safety evaluation of high-performance aerogel insulation materials in the thermal runaway propagation of lithium-ion batteries

Thermal runaway (TR) and its propagation (TRP) remain critical obstacles to the safe deployment of lithium-ion batteries (LIBs). This study characterizes TR behavior under thermal abuse across multiple states of charge (SOC) and introduces a glass fiber–reinforced SiO2 aerogel composite as an internal thermal barrier. The composite combines ultra-low thermal conductivity (0.021 W/m·K), high thermal stability (mass loss <4 % only above 300 °C), and robust hydrophobicity (contact angle >135°). Systematic testing demonstrated that increasing barrier thickness linearly extended the delay before adjacent batteries experienced TRP and markedly reduced the severity of propagation. Heat transfer analysis confirmed a stepped enhancement in insulation performance with thickness, with a 2 mm barrier attenuating approximately 50 % of transmitted heat and completely preventing TRP. Structural and electrochemical analyses of surviving batteries revealed negligible changes in crystal lattice, chemical composition, internal resistance, and Li+ diffusion coefficients. A dynamic risk-matrix framework is further developed to translate SOC–thickness pairings into quantifiable risk tiers, providing actionable design targets for battery modules. By quantifying the coupled influence of SOC and barrier dimensions on suppression efficiency, this work delivers a versatile, scalable strategy for improving LIB safety in diverse operating scenarios.