Mitigating thermal runaway propagation in high charge/discharge rate Lithium-ion batteries via SiO2 aerogel composites: mechanisms and risk assessment

Thermal runaway (TR) and its propagation (TRP) remain critical safety challenges in the practical application of lithium-ion batteries (LIBs), posing considerable risks to human safety and property. In this study, cost-effective SiO2 aerogel composites with low thermal conductivity and enhanced insulation performance were prepared by combining sodium silicate (water glass) with glass fiber mats. Using a self-constructed TR testing system, this work investigated the effects of SiO2 aerogel composites thicknesses (0-2 mm) on LIBs subjected to varying charge/discharge rates (1-4 C) following thermal abuse-induced TR in fresh batteries (0.5C). The study indicate that as the thickness of the SiO2 aerogel composites increases, the time interval between consecutive TRP events extends, while the efficiency of heat transfer decreases. Notably, a SiO2 aerogel composites thickness of 2 mm completely prevented TRP, suggesting that thicker barriers are more effective in stopping TRP. Additionally, with higher charge/discharge rates, the time interval preceding TRP was reduced, and the amount of heat transferred to the surface of Battery 2# increased, making it more susceptible to TR. Under such conditions, the internal structure of the battery may deteriorate, reducing its stability and increasing the likelihood and severity of TRP.