Ellen Phiddian
Cosmos science journalist
Much of the world’s lithium, crucial for the green energy transition, is found in liquid brines.
At present extracting this lithium is energy-intensive and expensive. Other methods of purifying lithium involve dangerous chemicals like sulphuric acid, and high amounts of energy.
But an Australian startup is working on a method that can extract lithium cleanly and much more efficiently.
The technology could make lithium 40% cheaper to produce, and end up extracting lithium from recycled batteries and even seawater.
It uses a technique called electrofiltration: using electricity, and a very fine membrane, to separate mixtures.
The membranes have been developed by Professor Huanting Wang, a researcher at Monash University.
“My research in nanostructure membranes is all about efficiency and ingenuity to make the most of this limited mineral resource,” says Wang.
Monash has spun Wang’s research into a startup company, ElectraLith, which is developing the membranes for commercial applications.
“We’re looking at taking the concept and putting it into electrodialysis systems,” says Dr Shaun Oosthuizen, Chief Technology Officer at ElectraLith.
“These systems have been around for the past 50 years. They’ve been used in anything from seawater desalination, to the dairy industry.”
Electrodialysis uses electric charge to separate charged particles out of water.
Current systems can pick up lithium (Li+) ions, which have a single positive charge. But they can’t distinguish lithium from other single-charge (or monovalent) metals in the mix, like sodium (Na+) or potassium (K+).
“You can get very basic selectivity, where you have some lithium being concentrated up, but ours appears to be orders of magnitude better,” says Oosthuizen.
Once they’ve perfected their lithium-specific membrane, ElectraLith is confident they’ll be able to slide it into existing electrodialysis infrastructure.
And then?
“We can unlock some of these brine resources that are currently uneconomical,” says Oosthuizen.
Rio Tinto, one of ElectraLith’s investors, has its eyes on high-altitude lithium brines in South America’s “lithium triangle”, between Argentina, Bolivia and Chile.
“When we start our process, the first step will be to go to the lithium triangle, put it in place and offer a more environmentally friendly, more cost efficient, safer, faster way of refining lithium,” says ElectraLith CEO Charlie McGill.
“Over time, we would then look to other resources.”
One possible application is recycling.
“As a secondary application, recycling is something that we’re really interested in, and our technology should work with recycling lithium-ion batteries as they come into their end of life,” says McGill.
At the moment, one of the things holding this back is not the recycling technology – it’s getting large enough supplies of dead lithium batteries, according to McGill.
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Eventually, the membranes could be improved to the point where they can extract lithium from seawater.
“Even though seawater is a brine, the concentration of lithium is too low for cost effective extraction, but we are already thinking about designing the next generation of membranes to improve Lithium extraction, so maybe in the future we can extract Lithium from new sources,” says Dr Zhouyou Wang, a Monash researcher who has just been awarded an ARC early career fellowship to develop the membranes further.
McGill is hoping to see the membranes hit the market in two to four years’ time.
“Once we’re comfortable with it, we prove it, we stress test it, we get the voltage, right, we get all that right – then we can essentially mass produce it. It’s not that expensive,” he says.