Graphene is a two-dimensional material that captured worldwide attention when it was isolated by University of Manchester researchers in 2004.
Some of its claims include being 100 times stronger than steel and being able to conduct electricity.
But harnessing those properties into a workable and affordable product has been difficult, which is what Yufei Wang, acting managing director at SupraG, has been working on.
He first worked with graphene when he was a research assistant during his bachelor degree at Monash University, where he developed technologies for using graphene for energy storage applications.
The university and Wang later approached investors to commercialise the work they had done in the lab, including an international investor that is a graphene manufacturer in China, which led to establishing a company at the end of last year with the manufacturer.
Now, SupraG is working on scaling up work to produce graphene-based supercapacitors and approaching international customers who might be interested in the product.
“At the moment at SupraG, we’re doing pilot-scale manufacturing or production of the graphene-based energy storage devices,” Wang said.
Patented technology
Graphene is a two-dimensional material made of carbon atoms, with a thickness of less than 1 nanometre.
SupraG is able to synthesise graphene and control its assembly behaviour to form graphene-based bulk materials with a purposely-designed nanostructure.
“Although individual graphene sheets are very popular with fancy properties, the difficult thing is how you make graphene bulk materials and how you design its nanostructure to reserve the outstanding properties of graphene,” Wang said.
“The key of our technology is that we design the assembly behaviour of graphene sheets to fabricate graphene bulking material with tunable nanostructures to suit different application requirements.”
This means SupraG is able to control the nanostructure of graphene bulk materials down to a sub-nanometre scale, which can greatly improve energy storage efficiency compared to commercial products.
Some of the challenges around this work included how to scale up manufacturing to produce a low-cost and environmentally friendly graphene material, which SupraG has achieved with its technology, including producing graphene dispersion in water to create individual graphene sheets in large quantities.
SupraG continued to refine the technology to transfer the graphene dispersion to a graphene gel film with a fine-tuned nanostructure.
“The key thing is we can control the nanostructure down to a sub-nanometre scale,” Wang said.
The quality of graphene materials can also vary significantly, depending on how it is manufactured, which can pose problems.
“We see a lot of manufacturers in the market saying they can produce tonnes of graphene every year. [But] every parameter in the whole process may be different for different manufacturers,” Wang said.
“We have tested a lot of the suppliers’ products, and it does vary a lot. One thing is the size and chemistry of the graphene sheets. The second thing is if it’s real graphene or if it’s multi-layered graphene flakes or even maybe graphite flakes.”
Wang said the quality of the graphene can also depend on how companies carry out the chemical reaction.
But he warns against being too overly focused on quality because different applications require different quality. For example, companies like Samsung and IBM require extremely high quality single-layered graphene sheets for applications like transparent electrodes.
“But for some other applications, for example energy storage, we may not need a large graphene sheet,” Wang said.
“’Quality’ is a very tricky word to use because different applications require different raw materials.”
Fast-charging supercapacitors
SupraG is looking into using graphene for supercapacitors, which can charge faster than conventional batteries and is able to discharge and recharge more cycles than rechargeable batteries.
But one barrier for use is their high cost and low energy density, which means applications are limited. For example, traditional supercapacitors cannot be used on electric buses due to the prohibitive cost and limited energy.
But with SupraG’s technology, the company is working to overcome this barrier by making smaller and lighter graphene supercapacitors with improved energy storage ability.
This means industries such as transportation could potentially use the company’s technology – something traditional supercapacitors haven’t been used for.
“This is a very promising area that we are looking forward to. But that requires a large module, it still takes a bit of time to be there,” Wang said.
SupraG is a semi-finalist in the Australian Technologies Competition, and is also looking into using its products in consumer electronics.
Its strategy is to target both the Australian and Chinese markets – it is in talks with the State Grid Corporation of China, which is interested in using its products in power management.
“Different countries have different advantages in terms of manufacturing or technology development. We hope to capitalise on resources from different countries to build up a unique business case with our technology,” Wang said.
“We hope that if we’re successful in the future, [we can work] with more technologies and help with more technology commercialisation.”
[Image: The image illustrates SupraG's graphene technology - graphene sheets are intercalated with other molecules which ensure a compact structure and well-reserved property of graphene. If the graphene sheets are stacked together, it will lose the outstanding properties of graphene.]