BENGALURU: Lithium-ion batteries power most electronics, but have limited density – they can store only a certain amount of energy per mass or volume of the battery.
IISc researchers have now come up with alternative technologies to store more energy with the same mass or volume. The team from the Department of Materials Engineering studied how to boost the movement of ions in magnesium batteries, which can have higher energy density. A new study, using a machine learning model, showed that using amorphous materials as positive electrodes to build these batteries can significantly increase their rate of energy transfer. The team built a computational model of an amorphous vanadium pentoxide material, calculated how fast magnesium ions can move within it.
Assistant Professor Sai Gautam Gopalakrishnan said lithium-ion or magnesium batteries contain a positive (cathode) and negative (anode) electrode, separated by a liquid electrolyte. Each time a lithium or magnesium ion goes from the cathode to anode or vice-versa, energy is exchanged with the device. In magnesium batteries, each magnesium atom can actually exchange two electrons, whereas each lithium atom can only exchange one electron with the external circuit. So one gets close to twice the amount of energy per atom moved, Gopalakrishnan said. The cathodes need to act like a sponge – upon applying external potential, they should absorb and release magnesium ions into the electrolyte. But the main bottleneck in commercialising magnesium batteries is the lack of good materials that can act as cathodes, he added.
But because magnesium moves slowly within these materials, it is unable to absorb and release ions at a fast pace. “If we break the crystallinity and create something that is amorphous, haphazard and chaotic, that may actually help magnesium to move fairly well within the structure,” Gopalakrishnan explained.