Energy-Dense Supercapacitors Based On Graphene

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Researchers at Monash University, led by Professor Dan Li of the Department of Materials Engineering, have developed a graphene-based supercapacitor (sometimes these are called ultracapacitors) which can achieve a volumetric energy density similar to that of a lead-acid battery.

Volumetric energy density is the ratio of the supercapacitors’ energy storage capacity to their size (in litres). This is measured in Wh/l (Watt-hours per litre). The volumetric energy density of these new ultracapacitors is 60 Wh/l, which is comparable to lead-acid batteries’ 60-75 Wh/l, and twelve times that of traditional supercapacitors, which are unfortunately too large for electric vehicles.

This means that one litre of these impressive little things can store 60 Wh of energy, enough to power a 60 watt light bulb for one hour per charge, or preferably, a 20 watt CFL for 3 hours. To create their material, the research team used a method similar to that used in traditional paper-making, meaning the process could be easily and cost-effectively scaled up for industrial use.

Supercapacitors are generally made of highly porous carbon infused with liquid electrolyte that transports their electrical charge. They are coveted for their ability to discharge and charge extremely fast (literally seconds), and their long lifespan. However, they are very expensive initially. I own six 10 Farad ones myself, and they are amazingly powerful, but not cheap.

“It has long been a challenge to make SCs smaller, lighter and compact to meet the increasingly demanding needs of many commercial uses,” Professor Li said.

“We have created a macroscopic graphene material that is a step beyond what has been achieved previously. It is almost at the stage of moving from the lab to commercial development,” Professor Li said.

“Unlike in traditional ‘hard’ porous carbon, where space is wasted with unnecessarily large ‘pores’, density is maximised without compromising porosity in Professor Li’s electrode,” according to Space Daily.

Potential applications for this new technology include short-range electric vehicles (since these supercapacitors are still very large, despite the improvement). Additionally, off-grid solar power storage systems (or even grid-tie solar power systems with energy storage to buffer their power or provide backup power during grid power outages) and grid energy storage could use these to handle power demand spikes.