It’s not every day you hear the words “groundbreaking physics” in the same sentence as “Wagga Wagga” – a rural Australian town 450 km west of Sydney on the banks of the Murrumbidgee River.
But it would be appropriate given physicists in condensed matter and materials (CMM) have been congregating at the Riverina city (population of little more than 70,000 – and yet the largest inland city in NSW) for an annual conference since 1977.
Wagga 2024
The 46th instalment of the Australian Institute of Physics’ CMM meeting, affectionately called “Wagga”, was held on February 6–9 this year at the Charles Sturt University.
Enjoying the rural theme, and taking home the award for best presentation at Wagga 2024, was Dr Jacob Martin from Western Australia’s Curtin University. The prize is a sculpture of a galah lovingly dubbed “Jacko.”
Martin tells Cosmos “there’s nothing better than a joke prize.”
“It’s an honor, of course, to be given the prize, but also that we don’t take it too seriously,” he laughs. He believes the Australian CMM community cuts through the usual “crappy pomp and rubbish” in academia.
His presentation was on research that he is leading at Curtin looking at the formation of graphite. He is the first to admit that he may have edged out others by bringing props to his talk.
This included 3D-printed microscopic views of the structure of graphite and a VR headset!
Graphite and green energy
Graphite is made up of layers of carbon atoms arranged in a 2D hexagonal pattern. It is extremely useful. It’s used as a dry lubricant and as the “lead” in pencils.
But Martin’s team is looking at its use in relation to green energy.
“Our focus is on getting carbon out of the atmosphere and embedded into green technology,” Martin says. “It turns out that a lot of carbon materials are critical for the green transition, but they’re quite energy intensive to prepare. Our goal is to use carbon for good, for renewable energy.”
Graphite is the largest component by mass in lithium-ion batteries, making up about a third of the energy storage devices. Lithium is pulled into the sheets of carbon in the graphite while the battery is charging.
The issue is that it takes an enormous amount of energy to form graphite and remove defects in the sheets which wrinkle, tear and interweave with each other.
Where’s all the energy going?
Because carbon is so stable, it needs to be heated to 3,000°C to form graphite. Current methods take 14 hours to heat and then they need to hold that temperature for another 3 hours.
“It’s a very inefficient process,” Martin says.
He says all the additional energy is to compensate for heat lost through radiation and convection.
“This is not to say, well, batteries are just crap because they produce lots of CO2, so you might as well burn fuel,” Martin is quick to add. “Even when you include all the emissions, batteries are sometimes two times better in terms of the amount carbon emitted. But we have to decarbonise everything. That includes manufacturing the materials for green technology.”
So his team set about to find better ways of making graphite.
Noticing your graphite is screwed
Martin and his colleagues built an instrument to watch the graphite forming. What they found is that it forms twice as fast as previous theory suggested.
“It’s a completely different type of mechanism. That means that we should be able to form graphite on a “seconds” timescale and not on the “hours” timescale,” Martin explains.
Looking at the structure, Martin’s team also noticed something else – screw defects. These spiral structures form between the layers.
“Now we understand how they unravel, and they unravel quickly,” he says.
Discovering how graphite forms means the way it is produced in a lab can be altered. “If you only need to heat the material for 10 seconds, it changes the way you think about this completely. You could have a smaller amount of material and feed it continuously through. We’re now commercialising that,” Martin says.
Virtual and real experiments
A key part of the team’s discovery was made possible by what Martin calls a “sort of experimental-computational approach.”
“We jump between doing virtual experiments and real experiments,” he explains. “The virtual experiments give us things to look for and the real experiments give us things to look at in the simulations.”
It all started when Martin was looking at a disordered form of matter called “glassy carbon.”
“I spent a year looking through simulations and found that there were screws inside the model. I thought, it’d be great if I can image that under an electron microscope. I tried, and I couldn’t see anything.
“But after a conversation with a PhD student I put a sample of graphite in, which is such an easy material to image. The first image I took was full of screw defects. You could see the individual atoms forming a spiral loop.”
Martin was interested in finding out how these screws form and how they get removed. So he and his then PhD student, Dr Jason Fogg, ran the simulation again.
“The simulation allowed us to see how the screws form, and how fast they go away. When we went back to the experiment, we measured how fast the screws go away, and we found the exact same number. It’s by going back and forth. We’re able to do virtual experiments, and then use the electron microscope to see things moving at those temperatures.”
To help understand this process and explain it to others, Martin got help from another student, Callum Wood, and artist Dr Andrea Rassell (a specialist in atomic art) who developed a VR environment in which the user can explore the computer model of graphite on an atomic scale and see the screw defects.
Martin says this research is a great example of the importance of condensed matter physics and materials’ science. It could potentially see a much more efficient way of producing graphite which will be critical in the transition to green energy. For example solar panels came out of CMM.
“I don’t think people appreciate how much condensed matter physics has changed their lives. If it wasn’t for the quantum mechanics that was applied to materials, we wouldn’t have semiconductors, we wouldn’t have computers. It started an entire new field of information science that utterly transformed our lives.”
