Comparative Study on Thermal Insulation Performance of the Various Materials for Suppressing Thermal Runaway Propagation in Lithium-Ion Battery Modules

The thermal runaway propagation in lithium-ion battery modules poses a serious threat to the safety of electric vehicles and energy storage systems. This study experimentally evaluated the thermal propagation suppression performance of five insulating materials: polyimide foam, nano-porous silica aerogel, ceramic fiber, pre-oxidized fiber aerogel, and mica sheet on 4 Ah ternary pouch cell modules. Thermal runaway was triggered in Cell 1 via an external short circuit (30C), and propagation behavior was characterized in terms of temperature evolution, propagation time, mass loss, and microstructural analysis. The results indicated that aerogel-based materials exhibited excellent thermal insulation performance. For the nano-porous silica aerogel, the temperature difference between its front and back surfaces reached as high as 484 °C, while the temperature rise of the adjacent cell was kept below 107 °C, thereby completely blocking propagation. The module mass loss was only 17.63 g, corresponding to a material loss rate of 0.67%. Pre-oxidized fiber aerogel also effectively suppressed propagation, albeit with a slightly higher material loss rate of 2.20%. In contrast, ceramic fiber and mica sheets only partially delayed thermal runaway propagation, as the adjacent cells still exhibited cracking and electrolyte leakage. Polyimide foam failed to prevent thermal runaway propagation, only extending the total propagation time from 424 s to 678 s (an increase of 60%) before being completely burned. Microstructural SEM analysis revealed that the aerogel materials suffered only slight fiber fracture, whereas the ceramic fiber underwent severe structural damage, the mica sheets displayed cracks and melting, and the polyimide foam was completely combusted. Taken together, these findings suggest that nano-porous silica aerogel is the preferred material for blocking thermal runaway in lithium-ion batteries, offering practical guidance for the thermal safety design of battery systems.