A breakthrough in the efficacy of calcium-ion batteries could be an alternative to lithium-ion batteries.
A team of researchers from the Rensselaer Polytechnic Institute (RCI) have created a battery using calcium-ion in a water-based electrolyte. The benefits of calcium-ion based batteries is that calcium-ions are larger in size and have a higher charge density, which would allow for a more efficient battery in a smaller size.
The other advantage of calcium-ion batteries over lithium-ion is that calcium-ion is far more abundant and far cheaper than lithium-ion.
However due to the larger size of calcium-ions the researchers had to overcome the difficulty of inserting the calcium-ions into the battery electrodes.
The lead author of the study, Dr Nikhil Koratkar, explained how they overcame the issues, “The calcium ion is divalent, and hence one ion insertion will deliver two electrons per ion during battery operation. This allows for a highly efficient battery with reduced mass and volume of calcium ions. However, the higher ionic charge and the larger size of calcium ions relative to lithium makes it very challenging to insert calcium ions into the battery electrodes. We overcome this problem by developing a special class of materials called molybdenum vanadium oxides that contain large hexagonal and heptagonal shaped channels or tunnels that run through the material.”
The research team believes that with the increasing costs of lithium-ion, calcium-ion batteries will become the battery chemistry that is most widely used to power a greener world.
“This work can lead of a new class of high-performing calcium-based batteries that use Earth abundant and safe materials and are therefore affordable and sustainable. Such batteries could find widespread use in portable and consumer electronics, electric vehicles, as well as grid and renewable energy storage,” said Koratkar.
