Abstract
In the pursuit of sustainable energy harvesting from low-grade heat, thermogalvanic cells (TGCs) have received considerable attention, but still confront profound challenges in efficiency and cost-effectiveness, limiting their real-world applications. To expedite the deployment of TGCs, this study delves into the mechanistic interplay of three crucial determinants: intrinsic temperature coefficient, concentration gradient, and activity coefficient of redox couples, elucidating their impact on TGCs' thermoelectric performance. We report a solvent-assisted liquid-state thermogalvanic cell (SA-LTC) by incorporating organic solvents into the sodium ferrocyanide-based TGCs system. With ethanol as a regulator to the concentration gradient and solvation structure, the temperature coefficient of [Fe(CN)6]3-/4- can be enhanced from − 1.39 to − 4.32 mV K−1, leading to a five-fold increase in thermoelectric power and efficiency. Meanwhile, ethanol imparts a lower freezing point and wider working temperature range to the system, showing its better environmental adaptability. In particular, SA-LTC performs better at lower temperatures, at which it achieved a record-high temperature coefficient of − 5.26 mV K−1 and a power density of 2.17 mW m−2 K−2 at 10–20 °C. This study not only provides useful guidance to the optimization of electrolyte design, but also highlights the potential of TGCs for sustainable energy conversion in varied thermal conditions for practical applications.
Published Version
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