Ellen Phiddian
Cosmos science journalist
Renewable energy – and rooftop solar in particular – needs effective batteries to keep growing. The current gold standard, lithium-ion batteries, are considered the most efficient, but they have a few drawbacks: lithium, which makes up 2% of the battery, is a precious resource that’s difficult to mine, and the batteries can be environmental hazards through both leaked toxins and fire risk.
As the industry proliferates, it’s becoming apparent that there is a market for improved battery technology. An Australian company has just introduced another option, with the launch of a 100% recyclable battery, which relies on graphene to work.
The batteries – styled as PowerCap – have been developed by a Queensland-based company, Zero Emissions Developments (ZED), and can be manufactured in an emissions-free way.
They work by combining graphene – a carbon-based material with interesting electrical properties – with metal oxides, a more traditional battery component.
“It’s what they call an asymmetrical cell,” explains Ahmed El Safty, CEO and principal engineer of ZED.
“We use graphene on one side – it’s actually graphene derivatives, we’ve done various things to it, to increase the energy density – and on the other side, we have a metal oxide.”
This type of battery is referred to as a “hybrid”.
“In other words, half of it is an electrochemical cell, like a normal battery. And the other half is an electrostatic cell,” says El Safty.
El Safty has spent the last two decades investigating batteries for renewable energy storage.
He began to develop the batteries while lecturing part-time at Queensland University of Technology.
“I met the head of mechanical engineering, physics and chemistry, Professor John Bell, who is now the Deputy Vice Chancellor of the University of Southern Queensland. He allowed me to use his labs.”
ZED is now part of the Australian Research Council-funded Research Transformation Hub for energy storage and conversion – a consortium including six universities and seven commercial companies. One other company in the hub – Gelion, which makes lithium-sulphur batteries – has already become publicly listed.
“We’re now at a point where we’re slightly lighter than your normal lithium battery. But we don’t have the problems that lithium presents, like combustion.
“And not only that, it makes it a hell of a lot easier to recycle at the end of life.”
He says that the battery also lasts longer than commercial lithium batteries.
“We’ve developed the product to a point where it can last three times longer than lithium batteries. Lithium batteries will do about 6,000 to 8,000 cycles before they get to [about] 20% degradation. Whereas we will go to just under 18,000 cycles before that 20% drop.
“That gives you a life of about 30 years if you’re using it in residential applications. So our standard warranty is 20 years.”
The graphene in the batteries will be manufactured in Australia, from waste products. Both it and the metal oxides are fully recyclable.
The batteries have been tested in a few places already – including a school and an aged-care home.
“We’ve been trialling that system for a while. And it’s been providing some really good results. We’ve had a 90%, or 90+%, reduction in electricity bills.”
In addition to these commercial batteries, ZED is selling residential batteries, ranging from 8.5 kWh to 15 kWh in size. (An average Australian household uses around 19 kWh daily.)
They’re also making batteries for “mobile applications” – vehicles. “We build our own golf carts with our batteries in them,” says El Safty.
The company is also working with the University of Southern Queensland to develop grid-stabilising technology for the batteries, allowing them to store and provide excess power to the national energy market.
“Because of the power density that we have, the battery actually has a lot of inertia. And it can provide a lot of systems strength to the grid,” says El Safty.