The quest for viable battery storage alternatives to lithium-ion continues this week, with news that researchers have demonstrated rechargeable aluminium-ion batteries as a possibility for future renewable energy storage.
In a study completed at Northwestern University in Illinois and published in Nature Energy, Dr Dong Jun Kim – now of the University of New South Wales School of Chemistry – led a team of researchers to demonstrate a strategy for designing active materials for rechargeable aluminium batteries.
As we have reported, the promise of aluminium-ion batteries has included faster recharging times, no thermal runaway issues, longer life and lower costs.
As Dr Kim, himself, puts it: “Developing batteries using aluminium has received a lot of expectation for delivering high energy to price ratios.”
That’s partly because aluminium is the third most abundant element in the earth’s crust behind oxygen and silicon. And, according to the UNSW, it also has one of the highest theoretical volumetric capacities, thanks to its multiple redox states.
These qualities are particularly promising in contrast with lithium-ion, which – having single-handedly powered the portable electronics revolution of the past few decades – is being leaned upon almost as heavily as renewable energy transforms global electricity grids.
As North Carolina State University’s Veronica Augustyn wrote here in October, demand is rapidly growing for alternatives to li-ion: “high-capacity batteries that won’t catch fire or explode… (and) smaller, lighter batteries that charge in minutes – or even seconds – yet store enough energy to power a device for days.”
That is not to mention the cost of lithium-ion batteries, often inflated by the addition of cobalt, which is often sourced at a high cost – both economic and human.
But, as this University of Standford research team found back in 2015, there have been some major road blocks preventing progress on some of the favoured cheaper alternatives, including aluminium-ion batteries.
The fundamental challenge, says the UNSW, has been “finding appropriate host electrodes for insertion of complex aluminium ions.”
But Dr Kim’s team believes it might have found an answer to that problem.
“We found a novel way to design rechargeable aluminium batteries by employing a redox-active macrocyclic compound as the active material,” Dr Kim said.
As the UNSW explains it Dr Kim and his team have managed to use a large organic chemical compound as the part of the battery that stores energy.
“We believe the research discussed in the article opens up a new approach to designing aluminium-ion batteries that could be of interest to scientists investigating next-generation electrochemical energy storage,” Dr Kim said.
But Like the Stanford researchers before him, Dr Kim is quick to warn that the research findings do not mean al-ion is about to knock li-ion off its perch.
“Our results showed promising battery performances, however, it is early days and we stress that there is need to improve even more in every aspect. So it does not make much sense to compare against the well-established lithium-ion battery system.”
And he is not restricting his studies to aluminium, either.
“I look forward to further research on utilising redox-active organic molecules for multivalent-ion intercalation batteries such as aluminium, magnesium, zinc, and calcium,” he said.