Carbogels for sustainable and scalable thermoelectric applications

Abstract: Thermoelectric generators (TEGs) based on commercially used thermal super-insulating materials can facilitate sustainable and large-scale ambient waste heat recovery while bequeathing an added economic and environmental value to thermal insulations in industry. This requires the optimization of the thermoelectric (TE) properties through electrical functionalization of such materials. Moreover, the associated engineering challenges of assembling TEG modules must be overcome. Herein, we propose using super-insulating Resorcinol-formaldehyde (RF) carbogels for scalable and sustainable TE applications through their electrical functionalization. Using a combination of a pyrolysis process and carbon fibers insertion, we achieved an increment by 12 orders of magnitude in electrical conductivity as well as ZT whilst retaining their intrinsic ultralow thermal conductivity (<50 mW/mK). A TE module in the form of a thermoelectric vacuum insulation panel (TVIP), was then fabricated using only a p-type material, to demonstrate a proof-of-concept self-powered WiFi-based vacuum-failure detection application in confined spaces in automobiles or aeronautics. Finally, by extrapolating the optimized output power and with a CAD-assisted assembly of a large TEG module (1000 cm2), the potential of scalable low-grade waste heat recovery is discussed.