Enhanced safety of lithium-ion batteries by a novel bifunctional aerogel sheet coated with fire extinguishing microcapsules

Severe safety concerns are impeding the large-scale employment of lithium-ion batteries. Disastrous thermal runaway results in catastrophic fires or explosions. Efforts to employ thermal insulation materials have generally improved the thermal safety of the battery module or pack. Conventional thermal insulation materials only prevent heat transfer when thermal runaway is triggered, which doesn’t provide long-term thermal protection. Here, a bifunctional fire-extinguishing microcapsule-coated aerogel sheet is reported to prolong the protection via an aerogel sheet containing temperature-responsive fire-extinguishing microcapsules. On one hand, the fire-extinguishing microcapsules coated aerogel sheet is designed to release fire-extinguishing agent in the early stage of thermal runaway by rapid heat absorption. On the other hand, the released fire-extinguishing agent coupled with a high-temperature resistant aerogel sheet suppresses the further thermal runaway propagation by prohibiting chemical chain reaction and heat transfer. The optimum synthesis of fire-extinguishing microcapsules and aerogel sheets was demonstrated to enhance the thermal safety of the battery module by delaying the thermal runaway propagation from 430 s to 2907 s. This performance is superior to that of conventional thermal insulation materials under a confined battery module condition. This novel strategy has the potential to reduce the damage of thermal runaway to human safety.