Switched-on graphene

Graphene’s potential to transform the way we make and use energy is moving a step closer to reality.

Story Catherine Norwood
Photo Eamon Gallagher

Professor Dan Li

Professor Dan Li is researching graphene’s interactions with other molecules
in order to create new functions that graphene sheets alone can’t offer.

From filtration systems capable of purifying the world’s polluted water supplies, to new ultralight, super-tough materials for advanced space travel, and instantaneous high-capacity solar energy storage systems, the plans for the world’s newest ‘miracle’ material, graphene, certainly do not lack for grand vision.

And little more than a decade after its discovery, the applications for this unique two-dimensional molecule are beginning to emerge from laboratory trials into the first stages of commercial use.

GUIDED BONE REGENERATION

In a collaborative project with China’s Shanghai Jiao Tong University, a graphene membrane developed at Monash University has been used in a bone regeneration trial, placed between damaged bone and surrounding tissue as a scaffold to stimulate bone growth. This also prevents soft tissue from growing into the bone space. The graphene membrane provided better density of bone regrowth compared with conventional titanium foil treatment. The graphene membrane is more flexible than titanium, is highly biocompatible and, because it is porous, may better allow nutrients to pass into the regenerating bone.

Graphene’s electrically conductive lattice-like layer is just one carbon atom thick. It’s lightweight, flexible and transparent, but also 200 times stronger than steel, and impermeable to gases and liquids.

The global race to bring graphene to market is hotly contested, with more than 25,000 patents for related processes and materials registered worldwide between 2005 and 2014.

Professor Dan Li at Monash University is a party to several of those patents, building on his early groundbreaking research that developed a scalable process to make water-soluble graphene from natural graphite.

He’s pioneered graphene gel technologies, which now underpin an expanding range of potential uses, from energy storage systems to wearable electronics.

SMART MEMBRANES

Monash research has shown how coating graphene sheets with polymers can change the size and chemistry of the pores between the layers to create more selective and effective filtration membranes. Stimuliresponsive polymers also provide the potential to create smart membranes, which change their properties when triggered by temperature, light or chemistry. Polymer testing at Monash indicates this approach could be used to create a wide range of separation applications, from water filtration to pharmaceutical manufacturing. This could include the release of drugs from an implanted membrane on demand, triggered by a small electrical potential.

Late in 2015, Monash University took a major step towards commercialising this research with the launch of a joint venture, SupraG Energy, to develop pilot-scale production of graphene gel membranes with applications in energy storage devices.

Professor Li says that while some researchers have focused on the properties of graphene itself, his approach is based on using graphene’s interactions with other molecules to create functions that graphene sheets alone can’t offer.

“The properties of graphene are exciting, but what’s more exciting is how we can design the architecture of graphene materials to deliver those properties in real products,” he says.

The development of an ultra-strong and electro-conductive hydrogel membrane is based on Professor Li's earliest work with graphene, dating to 2006. He found that by dissolving the atom-thin graphene sheets in water and then re-forming them, in a process similar to the traditional technique of paper-making from cellulose fibres, some water remains between the sheets as they restack.

The resulting hydrogel membrane offers superior energy storage capabilities, and, by controlling the way the layers restack, improves the transfer of ions between the layers for capture and discharge of energy. Professor Li says this offers real potential to address one of the major barriers to more widespread use of renewable energy and electrical vehicles: the ability to store that energy. The production process that SupraG Energy is scaling up will bring this potential one step closer to reality.

ULTRASENSITIVE PRESSURE SENSORS

Using ice crystals to force graphene sheets into new patterns has produced an ultralight cork-like aerogel dubbed the G-elastomer by Monash University researchers. It’s pressure-sensitive, and provides a virtually instantaneous resistance response when compressed. The G-elastomer is much more responsive to pressure and vibrations than human skin, suggesting possible uses in wearable electronic monitoring devices, biomedical electronics and bionic limbs.

Proof-of-concept trials at Monash have developed a graphene supercapacitor that can store almost 10 times the energy of a traditional activated carbon-based supercapacitor of similar size. In renewable energy and electrical vehicle applications, this means more energy can be captured for use from sources such as home-based solar cells or the kinetic energy of motor vehicles braking.

Professor Li says that once the SupraG production process is developed, it should be possible to generate graphene gel materials with diverse functions, scaling up proof-of-concept research to the level needed to attract further investment and broader industry partnerships.

To market, to market

Changing the liquid in which the graphene sheets are dissolved, changing the space between the layers, or even coating the graphene sheets with other polymers changes the combined properties of the new materials. Research at Monash has already identified several other configurations of the graphene gel materials and their potential uses (see breakouts).

Professor Li says it’s hard to know when these advanced materials will make it to market. But the process could take many years, with research and commercialisation costs of up to US$500 million. This makes collaborations with researchers, government and industry all the more crucial in order to translate research into real innovation.

To that end the Monash Centre for Atomically Thin Materials was launched in 2015, with Professor Li and Professor Michael Fuhrer as directors. The centre brings together the expertise of researchers within Monash’s science and engineering faculties to establish cross-disciplinary networks and enhance Australia’s nanotechnology capacity, with a specific focus on graphene and other atomically thin materials.

“New materials are the foundation of technological innovation, and innovation is what we need to really boost the economy, not just manufacturing new products,” Professor Li says.

New materials are the foundation of technological innovation, and innovation is what we need to really boost the economy, not just manufacturing new products.
Professor Dan Li

Graphene has yet to achieve the major breakthrough that many researchers believe will make it a ‘disruptive’ technology, one that fundamentally changes society, but Professor Li believes the growing expertise and diversity of local research in the field puts Australia in a prime position to take advantage when it does happen.