Structural Carbon-Enhanced Cementitious Thermoelectric Generators (TEGs): Optimal Energy Filtering and TEG Design for Outstanding Energy Harvesting

Abstract

We report on the development of a cementitious structural thermoelectric generator (TEG), exhibiting a significantly improved power density of 1.2 W/m 2 , via the optimization of the thermoelectric response of individual thermoelements and the TEG assembly. Toward this aim, we combined nano carbon black (nCB) and single-walled carbon nanotubes (SWCNTs) within the cementitious matrix to maximize the carrier-filtering effect for optimal thermoelectric efficiency. The multidimensional carbon nanomaterials self-assembled through electrostatic forces during the dispersion process in aqueous media and formed conductive networks inside the cement matrix at low filler contents. Simultaneously, the additional interfaces between the nCB and the SWCNT nano-reinforcement supported the selective scattering of low-energy carriers. Thus, cementitious thermoelements with significantly enhanced Seebeck coefficient were produced. To our knowledge, the Seebeck, S (+4644.2 μV/K), and power factor, PF (1.51 × 10 4 μW/mK 2 ), values attained in this study are the highest ever reported to date for nanoadditivebased cementitious thermoelectric nanocomposites. The optimal design of the proposed Hybrid TEG device (utilizing thermoelements with only SWCNTs and with SWCNTs/nCB reinforcement) resulted in a decrease of the internal electrical resistance of our cementitious thermoelectric generator, further optimizing its power output, which enabled, under a small ΔΤ of 25 K, the generation of enough power for the autonomous operation of microelectronic devices, like wireless sensors.