Bioinspired Active-Defense Coating with a Thermal Stability Relay for Mitigating Matrix Thermal Runaway Propagation.

Inspired by the iron birch (Betula schmidtii), a biomimetic active-defense coating (IBMC) is engineered. Within a polymeric-aerogel matrix, rigid mica platelets mimic protective bark, while temperature-responsive sustained-release microspheres (SRMs) function as artificial cells. Upon thermal shock, SRM actively release repair agents to trigger a distinct thermal stability relay mechanism. Initially (<400 °C), the released amino-silicone oil induces rapid interfacial cross-linking to counteract polymer decomposition. Subsequently, at extreme temperatures (>800 °C), an amorphous inorganic skeleton reconfiguration occurs, where inorganic components mechanically interlock into a rigid, self-supporting scaffold, effectively propped open by hollow SRM derivatives acting as rigid spacers. This active-defense strategy effectively prevents the catastrophic structural collapse typical of conventional insulation. Consequently, the coating demonstrates exceptional dimensional stability, achieving a minimal radial shrinkage of only 5.7% at 1000 °C. By suppressing macro-cracks and thermal bridges, it retains an ultralow thermal conductivity of 0.075 W/(m·K) and sustains a 197.7 °C thermal gradient. Ultimately, IBMC provides a compact and robust thermal management solution for mitigating thermal runaway across high-risk scenarios, including battery modules, steel structures, and datacenters.