Pearl-Chain-Embedded Architecture in Polyimide-Based Hybrid Aerogel Membranes: Toward Flexible Thermal Protection for Lithium-Ion Batteries

Thermal protection in confined electronic spaces, particularly within lithium-ion battery packs, faces a persistent conflict: materials must be thin enough to maximize energy density yet robust enough to block heat propagation. To resolve this, we developed a “pearl-chain-embedded” polyimide-silica aerogel membrane via a tailored two-step gelation strategy. By strictly controlling the interfacial chemistry, we employed hydroxyl-containing polyimide chains to establish a dense hydrogen-bonding network with the in situ-grown silica. This molecular-level engineering yields a hybrid membrane that decouples flexibility from thermal stability—retaining mechanical integrity after 1000 folding cycles (bending radius: 3 mm) while suppressing the severe high-temperature shrinkage typical of pure organic aerogels. Critically, in practical safety tests, a layer merely 1 mm thick established a sufficient thermal barrier to block the chain reaction of battery thermal runaway. These findings present a robust pathway for designing ultrathin safety layers in next-generation lithium-ion batteries.