High-power capacitors to replace batteries

The new breed of capacitors – components usually used to store an electric charge for seconds – can hold massive amounts of power and store it for much longer than traditional rechargeable batteries.

That solves two conundrums for engineers. It means they could make electric cars that don’t need to charge for hours every few hundred miles, and it removes the major downside of wind farms and solar panels, that they can’t store the excess energy they make on windy or sunny days.

The promise of so-called supercapacitors, or ultra high-energy capacitors, to transform renewable energy and electronic devices is one reason why the EU has set up the Graphene Flagship, one of the biggest ever research initiatives worth hundreds of millions of euros over the next ten years, when contributions from partners are also taken into account.

This ‘massive funding from the EU…puts a huge burden – or responsibility – on our shoulders, and will require us to focus on results and stay away from hype’, said Professor Andrea Ferrari of Cambridge University, one of the lead investigators of the Graphene Flagship.

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‘Efforts are currently dedicated to move supercapacitors towards high energy density as well as high power density.’ 

The idea behind the initiative is to drive forward the study of graphene, one atom thick carbon that is highly conductive and stronger than steel. Graphene is being used to make ultra-strong materials for planes, miniscule medical devices, and it is being rolled up into microscopic nanotubes to make supercapacitors.

Prof. Andre Geim, a physicist who won the Nobel Prize in 2010 for his work on graphene, famously made the substance by pulling a piece of sticky tape off a piece of carbon. However, the technique is ill-suited to mass production, and scientists are still trying to work out how to make graphene in large quantities economically.

EU projects

In the laboratory, however, research on graphene is already well underway. EU-funded projects like 2DNANOCAPS and AUTOSUPERCAP, a project aimed specifically at cars, have made significant steps in getting the technology to work. They're focussing their efforts on making the supercapacitors hold their charge for longer.

‘Whereas batteries possess a high energy density but low power density, today’s supercapacitors possess high power density but low energy density,’ said Trinity College’s Dr Deirdre Savage, a researcher at 2DNANOCAPS. ‘Efforts are currently dedicated to move supercapacitors towards high energy density as well as high power density.’ In other words, the aim is to extend the cycle time between recharging.

While easy enough to say, this is hard to do. The main barriers, Savage said, are ‘the intrinsic difficulty in handling and processing materials at nano-scale, and the lack of communication across different scientific disciplines’.

That’s where the Graphene Flagship comes in. The 10-year initiative has four Nobel Laureates on its advisory council: Professor Albert Fert, Professor Andre Geim, Professor Kostya Novoselov and Professor Klaus von Klitzing, and is aimed at giving researchers the resources and network to communicate across different areas of science. This should enable them to realise the potential of graphene, and if they succeed, then charging your laptop every day will soon seem as old fashioned as payphones and floppy disks.