Melbourne’s radical engineers storing electricity in ‘2D’ sheets

By se_admin 5 Feb 2020

It may look like grey paint on a roll of kitchen foil but engineer Chun Hin Ng is holding a wonder material, which he hopes will revolutionise how we store energy.

When loads of electronic gizmos were recently installed inside a previously abandoned Port Melbourne factory, the neighbours in the industrial park became curious and started asking questions.

“We are working on the future of energy storage,” Dr Ng told an audience gathered at a nearby café.

As the world moves to an increasingly electrified future, we need new ways to store and handle electricity. Typical batteries are slow to charge and discharge, lose performance after thousands of cycles and often involve harsh acids and scarce metals such as lithium.

The small team at start-up enterprise SupraG Energy recently relocated from its roots at Monash University with an ambitious goal – to convert graphite, commonly used to make pencils, to an atomically thin sheet designed to store electricity.

Larger machinery is on its way, but the current small-scale equipment offered an exclusive glimpse into an exciting engineering story unfolding in Melbourne.

If layers are carefully peeled off a chunk of graphite, a naturally occurring carbon material, eventually a “two-dimensional” sheet of graphene is formed just one atom thick.

“It’s hard for people to grasp because it’s an alien concept, this 2D sheet. It’s on the atom scale,” Dr Ng said.

SupraG takes a slurry of graphite, processes it with other additives and coats it onto a roll of aluminium foil as a supportive backing. In this form, the graphene possesses electrical storage and conductivity properties.

Is this the future of energy storage?

This graphene material is not new and is already incorporated in a minor way in some electronics. The challenge for researchers around the world is to discover the perfect way to manufacture it into a new generation of energy storage devices called super-capacitors, Dr Ng said.

“Yes, it’s amazing but we’re not there yet,” he said.

Unlike normal batteries, which charge slowly as they store energy in chemical reactions, super-capacitors made from graphene quickly create a store of static electricity.

“One side will get positive charge and then negative ions are attracted to it. You build up that charge and when you connect it in a circuit, it discharges very fast.”

Dr Ng explains a super-capacitor made from graphene can store less energy than a similar-sized conventional battery but it can discharge it much faster. He compares the technologies using the analogy of two buckets of water.

“If you think of a bucket of water, energy is how big the bucket is. A super-capacitor might be a one-litre bucket, batteries might be a 10-litre bucket,” he said.

“That one litre, you can just pour it out and that’s all of it gone within a second. But for batteries, it’s a 10-litre bucket with a lid on it and that lid has a little hole.”

“You can flip the 10-litre bucket upside down, but it’s only going to drain as fast as that little hole. It’s going to take much longer to charge and discharge.”

Super-capacitors will not completely replace batteries but complement them in many circumstances, Dr Ng said.

The fast-charging ability of a graphene super-capacitor could accompany the traditional batteries in an electric car, allowing quicker charging of the vehicle. Energy recovery is another option; super-capacitors are already being trialled in Europe to harness the braking energy from trucks.

Applications where high power is required instantly would also benefit from super-capacitors, such as camera flashes or even power backup systems for computers or hospital equipment.

The possibilities may even extend to everyday items becoming energy storage devices.

“We can coat these big films now. Right now, we are using it for batteries but who’s to say, next you could coat it on fabric or you could turn it into an ink and print it,” Dr Ng said.