Electrolyte concentration dependences of NiO based thermoelectrochemical cells performance

Thermoelectrochemical cells are a promising scientific direction in the field of renewable energy development and a way to increase the efficiency of various exothermic technological processes. In this work, the output parameters of the thermoelectrochemical cell based on nickel electrodes at alkaline electrolyte have been investigated. The measurements were carried out by the potentiodynamic method in thermostated cells with a salt bridge. The main indicators of the thermocells efficiency (open-circuit voltage, short-circuit current, output power and filling factor) have been measured and calculated for electrolyte concentrations from 0.1 M, to 3 M and at temperature gradient from 5 to 30 K. It was shown, that the volt-ampere characteristics have a nonlinear view and the deflection point strongly depended on the electrolyte concentration. The best fill factor value within the studied system is 40%. The machanism of non-linear voltage-current curve was supposed. It has been shown, that the potential difference in the cell depends on two opposite processes: the main potential-forming reaction (Ni2+↔Ni3++e−) and the side NiOOH decomposition reaction. Presumably the side reaction is realized by the accumulation of a certain potential on the electrode and it depends on the electrolyte concentration.