With the ongoing digital revolution, the world is on the verge to transition to be hyper connected. However, remote sensors and IoT devices that promise such a reality require energy. With sustainability being the top priority, the energy obtained must be from sources that are ubiquitous, abundant, and renewable. Fortunately, low-grade waste heat could serve the purpose provided efficient energy harvesting technologies are developed.
Meanwhile, thermoelectrochemical cells enable the conversion of temperature difference into electrical energy. These devices can use waste heat to sustain a reduction-oxidation reaction, which in turn generates electricity.
However, currently available thermoelectrochemical cells lack commercial implementations due to their low efficiency for energy conversion, costly fabrication, and lackluster output generation. This requires breakthrough in thermoelectrochemical cells to become viable for untethered low-power gadgets.
In this scenario, a team of scientists have devised an effective strategy to take it up a step further. This involved combining the operating principle of thermoelectrochemical cells with that of concentration galvanic cells thereby resulting in hybrid thermoelectrochemical concentration cells. While thermoelectrochemical cells are not new, the design suggested by the researchers addresses some critical shortcomings of existing ones.
The newly fabricated thermoelectrochemical cells are based on redox reactions that involve iodine ions and triiodide. On the contrary, conventional thermoelectrochemical cells, reactions occur in a non-aqueous carbonate solution that uses dimethyl carbonate as a solvent. The selection of these materials results in a peculiar effect.
With the increase in temperature of the hot side by more than 40 C, dimethyl carbonate reacted with iodine ions to generate a porous, gel-like coating of Li2CO3 close to the hot electrode. This helped to maintain large difference in the concentrations of triiodide and iodine cells throughout the cell.