Self‐Lubricating Nanofiber/Hollow Microsphere All‐Ceramic Architecture for Robust Flexible Thermal Insulation

The integration of ultrahigh thermal stability, minimal thermal conductivity, and robust mechanical flexibility into a single thermal insulation material remains a critical challenge, especially for safeguarding against transient thermal extremes like lithium battery thermal runaway. This study presents an all-inorganic flexible membrane fabricated via a facile electrospinning technique, which strategically embeds hollow silica (SiO₂) microspheres (HSMs) within a scaffold of SiO₂ nanofibers (SNF). This design yields a 3D self-lubricating architecture that confers extraordinary mechanical durability, withstanding over 100 000 bending cycles under 99% strain and 72 h of vibration without significant weight loss-a performance that surpasses conventional ceramics by orders of magnitude. Simultaneously, the composite membrane exhibits an ultralow and stable thermal conductivity of 31.39 mW m^-1 K^-1, together with a high specific airflow resistance of 122.11 (kPa S m^-1) mm^-1, synergistically inhibiting heat conduction and convection. The SNF/HSMs composite membrane demonstrates exceptional thermal resilience, enduring long-term exposure at 1100°C and surviving drastic thermal shocks from 1300°C to -196°C. When evaluated in a practical flame test at 700°C, a mere 5-mm-thick membrane effectively maintains a low backside temperature of ≈160°C. This work establishes a groundbreaking design principle for high-performance, flexible thermal protection systems.