High-Performance SnTe-Graphite Composite Aerogels for Simultaneous Thermal Insulation and Thermoelectric Conversion

The simultaneous realization of efficient thermal insulation and waste heat harvesting remains a pivotal challenge in advanced thermal management and sustainable energy systems. Although thermoelectric aerogels offer a promising solution, their performance is traditionally constrained by the strong coupling among the Seebeck coefficient, electrical conductivity, and thermal conductivity. To overcome this limitation, this study demonstrates a synergistic strategy combining directional structural design with the incorporation of a high-Seebeck-coefficient thermoelectric phase. Using low-cost flake graphite as the conductive skeleton and SnTe as the active thermoelectric phase, SnTe-graphite composite aerogels (ST-GCAs) with highly anisotropic architectures were fabricated via directional freeze drying and carbonization. The results reveal that the anisotropic structure effectively decouples transport properties, endowing the material with high electrical conductivity parallel to the freezing direction and superior thermal insulation perpendicular to it. Notably, the incorporation of SnTe facilitates a transition from a metallic to a semiconducting transport mechanism, significantly enhancing the Seebeck coefficient. Consequently, the optimal sample maintains an ultra-low vertical thermal conductivity of 0.093 W·m −1 ·K −1 at room temperature, while achieving a Seebeck coefficient of 77.77 µV·K −1 and a ZT value of 0.02 at 973 K, representing an enhancement of approximately one order of magnitude (15.5 times) compared to the pristine GCA. This work provides a scalable route for developing lightweight, high-temperature-resistant composite materials capable of simultaneous high-efficiency thermal insulation and thermoelectric energy conversion.