“In any given battery, something is either very rare or it’s toxic or it’s expensive. Those are the things that have been plaguing the battery industry,” said Apparao Rao, professor of physics at Clemson University in South Carolina and director of the Clemson Nanomaterials Institute.
His team has used aluminium and a graphene anode for a battery that can operate over 10,000 cycles. The energy density is 200 Wh/kg.
“The problem isn’t that aluminum ions are deficient,” said Anthony Childress, a graduate student at the Clemson Nanomaterials Institute. “It’s that unlike lithium ions that have been around for a while, we do not know much about how aluminium ions behave inside the battery.”
Their new battery technology uses aluminium foil and thin sheets of graphite called few-layer graphene as the electrode to store electrical charge from aluminium ions present in the electrolyte. “We knew that aluminum ions could be stored inside few-layer graphene,” said Ramakrishna Podila, assistant professor of physics and astronomy who also worked on the project. “But the ions need to be packed efficiently to increase the battery capacity. The arrangement of aluminium ions inside graphene is critical for better battery performance.”
“Previous attempts by other researchers to make high-capacity aluminium batteries were not very successful,” said Jingyi Zhu, a recent Clemson graduate. One explanation for lower performance in other labs could be that cathodes had defects. The team used their expertise in Raman spectroscopy, a method of identifying and measuring molecular signatures, to test their aluminium ion batteries and confirm capacity.