Molten air battery offers highest energy storage capacity & is rechargeable

Molten air batteries have been demonstrated to offer highest ever energy storage capacities, making the competition look dwarf. For the first time, researchers have been able to manufacture molten-air batteries that can be recharged - biggest advantage these batteries have over other high capacity batteries. There's however a big challenge that needs to be tackled. The molten electrolyte requires very high temperatures (~800 °C) for the battery to operate. Researchers are optimistic about trying out different compositions and characteristics so that the battery can operate at regular temperatures.

The molten air batteries are the first ones of their kind to use molten salt and free oxygen from air to host multi-electron molecules to store energy. It's this ability to store multiple electrons in a single molecule that gives the massive energy storage capacity to molten-air battery. Traditional batteries, like Li-Ion batteries have single electron per molecule structures which limits their storage capacities. The Vanadium Boride (VB2)-air batteries, which currently have the crown of being the biggest capacity batteries have a serious drawback - they aren't rechargeable.

Researchers have worked out different types of molten air batteries with different storage capacities. The iron, carbon and VB2 -molten air batteries have been developed with intrinsic volumetric energy storage capacities of 10000, 19000, 27000 Wh per liter.

What's yet to be known is the commercial aspect of these batteries. Unless the researchers bring down the costs of manufacturing and operating costs of this battery - they won't get wide adoption. Another important aspect is the overall weight and portability of such batteries, if they were to be used in electric vehicles. The third most important aspect would be the energy required to charge these batteries; which may have significant impact on the operating costs & maintenance.