Flexible Silica Aerogel Composites for Thermal Insulation under High-Temperature and Thermal–Force Coupling Conditions

The objective of this research was to develop a high-performance flexible silica aerogel composite for thermal insulation under high-temperature and thermal–force coupling conditions. Based on synthesis of flexible silica aerogels with methyltrimethoxysilane as the precursor, flexible silica aerogel composites were developed by wet-impregnating ceramic fiber felt. Morphology, microstructure, chemical structure, hydrophobicity, and compression performance evolutions of the flexible silica aerogels and their composite counterparts with temperature revealed that the resulting flexible silica aerogel samples have excellent stability at 900 °C. Flexible silica aerogel composites show 100 and 70% recovery with 50% strain after treatment at 500 and 900 °C, respectively. Thermal insulation performance of the flexible silica aerogel composites was comprehensively studied from different aspects, including thermal conductivity, thermal shield behavior under high-temperature and thermal–force coupling conditions, and thermal shock resistance. Thermal conductivities of the flexible silica aerogel composite at 25–1100 °C are lower than those of most reported aerogel composites. Coupling of force under high temperature leads to degradation of thermal insulation performance, owing to deformation with compression. The synthesis method of the flexible silica aerogel is facile and inspiring, and the flexible silica aerogel composites have promising prospects in thermal insulation under high-temperature and thermal-stress coupling conditions, such as suppressing thermal runaway propagation of lithium-ion batteries.