Dynamic response of a thermoelectric cell induced by ion thermodiffusion

Abstract

Aqueous electrolyte solutions under the influence of a temperature gradient can generate thermoelectric fields, which arise from different responses of the positive and negative charges. This is related to the thermo diffusion effect which is quantified by the ionic heat of transport and the thermal diffusion coefficient. When a solution is confined between two metallic electrodes with different temperatures, it is expected to measure the electrostatic potential difference due to the thermoelectric field. We performed experiments in aqueous electrolyte solutions, and our results show that a thermoelectric field appears instantly in the solution as the temperature difference between the electrodes stabilizes. This field arises from the trend to separate both ionic charges in the temperature gradient. The experimental results also show that a slow change in the potential difference is observed, which is related to thermodiffusion in the entire cell. These results are important to understand how the thermoelectric response can be optimized, given the broad interest in the literature to generate thermoelectric energy from thermoelectric cells