A Nacre-Mimetic Mullite Nanofiber Aerogel Paper Achieving High-Voltage Electrical and Thermal Insulation via Self-Templated Assembly.

Simultaneously achieving high-voltage electrical insulation and high-temperature tolerance in a single lightweight material remains a formidable challenge due to the intrinsic conflict between dielectric strength and thermal stability. Here, we solve this problem by constructing a flexible, nacre-mimetic mullite nanofiber aerogel paper through a self-templated electrospinning strategy. In this design, functionalized mica nanosheets serve as dielectric barriers uniformly embedded within a mullite nanofiber framework, forming a brick-and-mortar architecture. This structure not only creates an extended tortuous path to suppress electron avalanche breakdown but also establishes a double-network bandgap that inhibits charge transport and segmental chain motion. The aerogel paper thus achieves an exceptional electrical resistivity of 6.5 × 1014 Ω·cm while maintaining stable dielectric performance above 500°C. Moreover, by grafting low-surface-energy ormosil directly into the precursor sol, we circumvent the pore-clogging and hydration issues inherent to post-synthesis treatments, endowing the aerogel paper with super-hydrophobicity. This combination of ultralight weight, high-temperature dielectric stability, and environmental durability represents a paradigm shift in material design for next-generation miniaturized high-power electronics.