Enhanced barrier materials with integrated gas regulation capabilities to mitigate explosion risks in battery systems

[Display omitted] •A multifunctional barrier material was prepared using in-situ polymerization.•Introduce gas regulation function into barrier materials.•Under high-temperature conditions, the mechanical properties of barrier materials are spontaneously enhanced.•The thermal runaway propagation of high-capacity lithium iron phosphate batteries is suppressed.•The danger associated with gas generation during thermal runaway in lithium iron phosphate batteries is reduced. Large-capacity lithium iron phosphate batteries are widely used in energy storage stations and electric vehicles due to their high cost-effectiveness and long lifespan. However, research shows that the gases generated during thermal runaway are mainly combustible, which may lead to fires or even explosions. Nevertheless, within the millimeter-scale confined space of a battery pack, effective solutions are scarce, making it challenging to simultaneously suppress kilowatt-level heat transfer and dilute the accumulated combustible gases. This research has developed a multifunctional fire shield with capabilities of “low-temperature heat conduction, medium-temperature heat absorption, high-temperature thermal insulation, and gas regulation.” The material is composed of hydrogel, aluminum hydroxide, ceramic fiber, and ammonium bicarbonate. In the low-temperature range, it exhibits an excellent thermal conductivity (0.58 W·m−1·K−1), capable of maintaining the battery module’s operating temperature within a reasonable range. In the medium to high-temperature range, its thermal conductivity rapidly decreases (0.04 W·m−1·K−1), and with its high phase change enthalpy (1727 J/g), the material can suppress the thermal propagation of a 100 Ah lithium iron phosphate battery module. This material starts to release CO2 at 90℃. In a confined space, the CO2 mixes uniformly with the gases generated during the thermal runaway process of the battery, reducing the risk of these gases (increasing the lower explosion limit by 44 % and reducing the maximum laminar flame speed by 58 %). Therefore, the multifunctional fire shield demonstrates exceptional heat conduction, heat absorption, thermal insulation, and gas regulation performance. This research provides new insights for the safety design of battery systems.