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

ABSTRACT 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 (SiO ₂ ) microspheres (HSMs) within a scaffold of SiO ₂ 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.