Mechanically robust, superinsulation all-ceramic aerogels via an ambient-pressure sandwich design

Creating mechanically reinforced ceramic aerogels at ambient pressure to improve their reliability in extreme environments remains a significant challenge. Here we demonstrate an ambient-pressure assembly approach to fabricate sandwich-structured ceramic nanofiber aerogels (S-CNFAs), which have superior structural adaptability compared to CNFAs formed with fibrous membranes or crimped nanofibers. Benefiting from a hierarchical architecture design strategy involving ceramic nanofibers with dense dual-phase structures at the microscale, flake-shaped bonding and arched cellular structures at the mesoscale, and a compact-fluffy-compact stacking structure at the macroscale to enhance stress transfer and dissipation, S-CNFAs achieve exceptional compressive and bending resilience, along with a record-high tensile strength of 565 kPa (more than tenfold enhancement) and specific tensile strength of 22.5 kPa cm 3  mg −1 (over 300 % improvement), and demonstrating exceptional resistance to complex mechanical environments (220 N bursting strength at >30 % strain, knotting capability). Simultaneously, the all-ceramic sandwich architecture confers ultralow thermal conductivity (23.8 mW m −1  K −1 , comparable to still air) and unparalleled thermomechanical stability from cryogenic conditions (−196 °C) to ultrahigh temperatures (∼1300 °C). This ambient-pressure assembly paradigm opens scalable routes to high-performance ceramic aerogels.