The study results were published in the journal Renewable Energy.
Thermoelectrochemical cells (thermocells) are miniature devices that generate electricity from the energy of temperature gradients, temperature differences between various objects, or environments.
Modern devices of this type create a greater potential difference than semiconductor thermoelectrics, but they are less powerful in terms of output power. According to scientists, this is what limits their practical application today.
Solving this problem, MISiS scientists were the first to study a new type of thermocells that uses metal oxide electrodes and an aqueous electrolyte. According to the researchers, this solution allows the current to be increased and internal resistance to be reduced, providing a greater increase in power compared to analogues.
"We've shown the possibility of using an oxide-nickel electrode based on hollow nickel microspheres in a thermocell. We have reached a record hypothetical Seebeck coefficient for aqueous electrolytes. Moreover, we've found a nonlinear change in current-voltage characteristics, atypical for thermocells, which ensures an increase in the device's efficiency", Igor Burmistrov, leading expert from the Department of Theoretical Physics and Quantum Technologies at NUST MISiS, said.
The high Seebeck coefficient will allow even human body heat to be used as an energy source, NUST MISIS scientists explained. In the future, the scientists want to create an electrochemical supercapacitor that will be charged by contact with heated surfaces, maintaining the charge for a long time.
Using water systems significantly reduces manufacturing costs and increases the safety of cells, which, scientists believe, will allow to shortly move to implement commercially attractive systems.
"The materials we are designing will allow us to create, for example, electronic batteries built into clothing and using the temperature differences between the human body and the environment. Temperature gradients are everywhere, and devices of this type will help harvest energy dissipated into the environment by industrial objects, buildings, and many others simple and free sources", Igor Burmistrov explained.
According to scientists, the new thermoelectrochemical cell can provide an open circuit voltage of up to 0.2 V at an electrode temperature of up to 85°C, which is 10-20 times higher than analogues, the authors of the study noted.
In the future, the scientists want to increase the output power by optimising the electrode material composition and improving the thermocell’s design.