A review of silicon-based aerogel thermal insulation materials: Performance optimization through composition and microstructure

Silicon-based aerogel (SA) has attracted increasingly more attention in the field of thermal insulation as its extraordinary properties such as ultralight, ultra-low thermal conductivity, and strong designability. However, SA thermal insulation materials (SA-TIMs) have several intrinsic defects such as low strength and poor toughness, which make their processing and handling difficult and restrict their practical applications. Composition optimization and microstructure reconstruction are the most convincing and effective strategies to improve their mechanical and thermal insulation properties, achieve more functions, and reduce cost. This review encompasses a complete survey of scientific achievements related to the two strategies, describing their characteristics, microstructures, and properties. The influence of different compositions and various assembly structures on the final properties of SA-TIMs is thoroughly reported. The main focus of this review is to point out the design principles of SA-TIMs and discuss the most promising development trends towards their widespread applications.