Thermally regenerable redox-flow batteries

Low-Temperature Heat (LTH), heat below of 100°C, has recently elicited great interest among the scientific community, as a source of energy since it actually does not see any form of utilization as it is currently simply released into the environment. The conversion of such form of energy from various sources thus becomes of utmost importance as its efficient recycling would allow to decrease the environmental footprint caused by humankind during energy production, and it would open the doors to the exploitation of a huge amount of heat as well, such as geothermal, solar, and industrial waste heat. Thermal regenerable Redox-Flow Batteries (TRBs) are flow batteries that store energy in concentration cells that can be recharged by distillation at temperature <100°C, exploiting LTH. TRBs are composed by a selective ion-exchange solid-state electrolyte which divides two half cells where two water solutions at different concentration of a suitable redox couple (such as LiBr/Br2 or NaI/I2) are injected. The initial experiments prove an unprecedented heat-to-electricity efficiency for both the systems: 3% for TRB-NaI and 4-5% for TRB based on LiBr water solutions, depending on the thickness of the membrane with a power density output of almost 10 W m-2 for both technologies, which opens various possibilities to implement further improvements into this new class of energy storage/converter devices.