LAUSR

Abstract Research interest in thermocell technology has been increasingly occurring due to its large Seebeck coefficient (~1 mV/K) and flexible structure, which are its unique advantages for use in wearable devices directly converting thermal energy into electricity. It is timely and critical to investigate the technology to potentially overcome the technological drawbacks of thermocell such as its relatively low power density and limited overall energy efficiency. In this paper, the correlation between the performance of a Fe(CN)63−/4− thermocell and ion concentrations are studied through factorial experiments. Solubility tests are conducted to obtain the maximum concentration. Activity coefficient is found non-negligible in the Nernst equation. The saturation line calculated through concentration solubility product shows relatively close agreement with experimental results. Total concentration, as well as the concentration ratio of ions, have a significant effect on the thermocell performance. At the optimised concentration point on the saturation line, power density, Seebeck coefficient and efficiency respectively increase by 7.38%, 8.93% and 5.69%. And the mass of solute decreases by 12.64%, compared with the widely used 1:1 concentration ratio. Results demonstrate to improve the power density of thermocell, the solution needs to be saturated and the ion concentration ratio should be taken into account.