• Energy Research
• natural sciences close

Abstract High-performance harvesting of waste heat energy and its conversion into electric energy via thermo-electrochemical cells is an essential strategy of renewable energy development. Even though there is a large amount of scientific research available, but due to expensive electrode materials and low efficiency, the thermo-electrochemical cells have not found practical application. Here we demonstrated thermo-electrochemical cell with nickel (Ni) hollow microspheres-based electrodes, provided the highest hypothetical Seebeck coefficient of 4.5 mV/K (for aqueous electrolyte based thermocells) until today and open-circuit voltage values of up to 0.2 V. High values of Seebeck coefficient provide the ability to collect low-temperature heat, and high output potential differences which allow to fabricate batteries for commercial power circuits for various microelectronic devices. This work also proposed a mechanism and science behind the electrode processes, which explains a extremely high values of the hypothetical Seebeck coefficient. This is the first time to use Ni hollow microsphere in thermo-electrochemical cell for heat harvesting and thermal energy conversion into electricity. Because of the low cost of Ni microspheres electrode-based developed thermo cells could be commercially feasible for harvesting low-quality thermal energy.

An important direction in the development of energy saving policy is harvesting and conversion into electricity of low-grade waste heat. The present paper is devoted to the improvement of the efficiency of thermo-electrochemical cells based on carbon fiber electrodes and potassium ferri-/ferrocyanide redox electrolyte. The influence of the carbon fiber electrode surface modification (magnetron deposition of silver and titanium or infiltration implantation of nanoscale titanium oxide) on the output power and parameters of the impedance equivalent scheme of a thermo-electrochemical cell has been studied. Two kinds of cell designs (a conventional electrochemical cell with a salt bridge and a coin cell-type body) were investigated. It was found that the nature of the surface modification of electrodes can change the internal resistance of the cell by three orders of magnitude. The dependence of the equivalent scheme parameters and output power density of the thermoelectric cell on the type of electrode materials was presented. It was observed that the maximum power for carbon fiber modified with titanium metal and titanium oxide was 25.2 mW/m2 and the efficiency was 1.37%.