Elastic ceramic aerogels for thermal superinsulation under extreme conditions

Thermal insulation under extreme conditions requires materials that can withstand sharp thermal shocks as well as extended high-temperature exposure. In this regard, a new generation of elastic ceramic aerogels (CAGs) are attractive for their tunable structure, light weight, low thermal conductivity, high thermal stability, excellent fire and corrosion resistances, as well as mechanical flexibility. Here we review recent progress in elastic CAGs for thermal superinsulation, focusing on elastic deformability, thermal stability, and thermal insulation. In particular, we first summarize various structure engineering strategies, including one-dimensional nanofibrous structures and two-dimensional nanolayered structures to endow the elasticity that can overcome the intrinsic brittle nature of ceramic materials. We next discuss strategies to further enhance the thermal stability by tuning ceramic crystallinity, oxidation resistance, and thermal expansion behavior, and then elaborate on approaches to reduce the thermal conductivity. Finally, we highlight the optimized elastic CAGs with extreme-low thermal conductivity, ultra-high working temperature, and excellent elasticity for a variety of applications in thermal insulation, gas catalysis, energy storage, and environmental remediation.