Thermoelectric devices convert heat into electricity but are limited by the small voltage generated from the Seebeck effect. This paper presents a thermo-hydro-electrochemical approach that generates a large thermal-to-electrical energy conversion factor (-87 mV K⁻¹) using low-cost carbon steel electrodes and a solid-state polyeletrolyte. The thermo-diffusion of water in the polyeletrolyte under a temperature gradient alters the corrosion overpotential, generating output power. This finding facilitates further research to increase the energy conversion factor and utilize wasted thermal energy.
