Passive protection containment of high temperature and impact hazards from thermal runaway in aviation power lithium-ion batteries

The thermal shock caused by thermal runaway of lithium-ion batteries causes damage in the installation structure and poses a threat to the safety of surrounding personnel and equipment, which is a key issue limiting their aviation applications. Through a self-built high-temperature impact experimental platform for thermal runaway of lithium battery, it was found that the impact pressure on the pack top plate of battery from single-cell thermal shock can reach up to 13.23 kPa, causing the external surface temperature beyond 274 °C. The combined effect of high temperature and impact pressure increases the risk of the casing undergoing plastic deformation, buckling, or even failure. To effectively mitigate such risks, a passive protection method that involves applying a fireproof coating to the top plate of the battery pack. is proposed. Through large panel combustion experiments and cone calorimeter tests, it was found that the epoxy resin-based intumescent fireproof coatings can effectively block the impact pressure induced by thermal runaway of a lithium-ion battery by expanding, and absorbing heat, thereby reducing and delaying the temperature rise of the top plate of the battery pack, demonstrating excellent thermal shock resistance. By comparing the containment effects of fireproof coatings of different thicknesses, it was found that the 1.0-mm-thickness coating is more suitable for practical application requirements. Referring to relevant airworthiness regulations, verification tests were conducted on the thermal runaway containment of lithium battery. The analysis of the experiment results shows that the 1.0-mm-thickness E80S20 coating and E85S15B3 coating reduced the maximum temperature of the top plate of the battery pack by 52.16% and 55.80%, respectively. Additionally, the maximum structural deformation decreased by 72.2% and 44.4%, respectively. The study indicates that the passive protection technology of fireproof coating can effectively enhance the containment of high temperatures and impact hazards caused by thermal runaway. This approach can serve as an effective measure in the safety design of aviation power lithium-ion battery systems.