Gradient thermal management-alarm composite film for omni-directional enhancement of Li-ion battery safety

The widespread of electrical vehicle means a sophisticated and systematic method is required to improve Li-ion battery safety. As being complementary to thermal regulation and flame retardant, alarming enables to detect potential safety hazard and win enough time to take action. Herein, a gradient thermal management-alarm composite film is designed to improve battery safety. Specifically, a lamellar and porous aerogel composes of montmorillonite nanosheets and aminated carbon nanotubes is fabricated to encapsulate sodium acetate trihydrate as composite film. The leakage-proof film with high latent heat and thermal conductivity suppresses temperature raising by 11.4℃, while dropping of electrical resistance from melted hydrate salt lightens LED for high-temperature alarming with superior sensitivity (1 min/75℃). If thermal runaway happened to generate combustion, thermal-chemical reaction integrates with scaffold and isolation effects to achieve low heat release (7.1 kJ/g) and high burning temperature (525.5℃). Meanwhile, sharp fluctuation of electrical resistance during burning acts as flame alarming with duration up to 1800 s. In summary, the two-gradient thermal management-alarm system based on the SPMA composite film endows two strong defense lines to boost battery safety omni-directionally.