A thermoelectric battery stores energy when charged by converting heat into
chemical energy
Chemical energy is the energy of chemical substances that is released when they undergo a chemical reaction and transform into other substances. Some examples of storage media of chemical energy include batteries, Schmidt-Rohr, K. (2018). "How ...
and produces electricity when discharged. Such systems potentially offer an alternative means of disposing of
waste heat from plants that burn fossil fuels and/or nuclear energy.
History
Thomas Johann Seebeck (1780-1831) discovered the
thermoelectric effect in 1821. The symmetrical
Peltier effect (
Jean Charles Athanse Peltier, 1785-1845) uses an electric current to produce temperature differences. In the middle part of the twentieth century the thermo-electric generator was often used in place of
galvanic batteries.
Copper/ammonia
In 2014 researchers demonstrated a prototype system that uses copper electrodes and ammonia as the electrolyte. The device converted some 29 percent of the battery's chemical energy into electricity.
The ammonia
electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
is only used as an
anolyte (electrolyte surrounding an anode) that reacts with the copper electrode as waste heat warms the ammonia, generating electricity. When the reaction uses up the ammonia or depletes the copper ions in the electrolyte near the cathode the reaction stops.
Waste heat then is used to distill the ammonia from the used anolyte. The ammonia is then added to the cathode chamber. The battery's polarity reverses and the anode becomes the cathode and vice versa.
The system's
power density was some maximum power density of 60+-3 1 W m
−2(based on a single electrode), with a maximum energy density of 453 W h m
−3 (normalized to the electrolyte volume), substantially higher than that of other liquid-centered thermal-electrics.
Power density increased with the number of batteries in the system.
Volatilization of ammonia from the spent anolyte by heating (simulating distillation), and re-addition of this ammonia to the spent catholyte chamber with subsequent operation of this chamber as the anode (to regenerate copper on the other electrode), produced a maximum power density of 60 ± 3 W m
−2, with an average discharge energy efficiency of 29% (electrical energy captured ''versus'' chemical energy in the starting solutions). An acid added to the catholyte increased power 126 ± 5 W m
−2.
Telluride
Telluride based batteries convert 15 to 20 percent of heat to energy.
Fulvalene diruthenium
Fulvalene di
ruthenium promises greater efficiency, but is too expensive for commercial use.
See also
*
Thermoelectric generator
*
COGAS
References
{{galvanic cells
Battery types
Thermoelectricity