Experimental Study on the Effect of Fire-Extinguishing Pads and Flame-Retardant Coatings for Suppressing Thermal Runaway Propagation in Lithium-Ion Batteries

This study investigated strategies to mitigate thermal runaway propagation, a major cause of fire spread in lithium-ion batteries, by analyzing fire incidents and reproducible experiments. Experiments were conducted on 18650 lithium-ion battery packs under three conditions: unprotected, with an automatic fire-extinguishing pad, and with a flame-retardant-coated nonwoven fabric. Under unprotected conditions, thermal runaway was clearly observed, exhibiting a typical pattern of progressive heat propagation from the impact point to the surrounding cells. Under protective conditions, both measures effectively suppressed propagation. The flame-retardant nonwoven fabric produced a peak temperature of approximately 674 ℃; however, it induced rapid cooling, which reduced propagation. The automatic fire-extinguishing pad confined the runaway to a single cell, exhibiting a nonpropagating pattern. These results confirm that the use of protective materials can significantly reduce the risk of thermal propagation in lithium-ion battery systems.