Ultra-high SiO2-loaded hydrogel with enhanced mechanical strength, thermal regulation, and ablation resistance for lithium-ion battery safety

Thermal runaway in lithium-ion batteries poses severe safety risks due to fire and explosion. Here, we report a counterintuitive strategy to fabricate a hydrogel by incorporating 500 wt% nano-SiO 2 into a polyacrylamide (PAM) matrix. The resulting composite exhibits nanoconfined porous structure and outstanding mechanical, thermal, anti-freezing, and ablation resistance properties. Compared to pure PAM, the hydrogel achieves 33× higher tensile strength (1.3 MPa), 645× higher compressive strength (27.75 MPa), and 1133× higher fracture energy (2.04 MJ m −3 ). Abundant bound water and nanopores extend vaporization duration, enhancing thermal regulation and flexibility at −10 °C. Post-ablation residues with micro/nano hierarchical porosity exhibit low thermal conductivity (0.104 W m −1  K −1 ) and reduced peak heat release (54.3 kW m −2 ), effectively suppressing heat and flame propagation. Thermal runaway tests confirm the hydrogel's ability to delay propagation and provide critical escape time. This multifunctional material offers a new design avenue for advanced thermal protection in battery systems.