Development of new electrode materials for thermo-electrochemical cells for waste heat harvesting

Thermoelectrochemical cells (thermogalvanic elements, thermo-cells) are the promising devices for sustainably generating electricity from waste heat. These systems directly convert heat into electricity with a performance governed by the properties of the electrode materials and electrolyte. The influence of the nature of electrodes on fundamental properties such as the Seebeck coefficient and power output are investigated in this work. Two different metal electrodes (Zn(s) and Ni(s)) not studied before in the thermogalvanic applications are examined in the ZnSO4 and NiSO4 aqueous solutions respectively, and compared with conventional Cu(s) electrodes (in the CuSO4 solution). It is established that for the copper and zinc electrodes, the experimental values ​​do correspond to theoretical values ​​and are well correlated with the data for similar thermogalvanic cells published earlier. It has been recognized that in the case of the nickel electrode there is a two-step mechanism and extremely high (for aqueous systems), value ​​of the hypothetical Seebeck coefficient (about of 2.83 mV/K with a temperature gradient in the range of 30–60 K) is observed. It is shown that nickel electrode ensures double power output in comparison with previously studied copper one, which makes it highly promising for further research. It is supposed that the effect obtained with Ni electrodes characterized with well-developed surface area allows producing the commercial thermo-electrochemical cells for waste heat harvesting.