Breakthroughs in energy storage could revolutionise the energy industry.
It boils down to surface area to weight. If we can squeeze a lot of area out per ounce of conductor, then we have done it. We have found the holy grail of physics, and in the process we may open up the possibility of living in an age of plenty.
That may seem a tad over the top, but just consider what we could do if energy was so cheap it was almost free. Some say the answer lies with nuclear fusion, they are right, but may not be for the reasons that are often cited. Nuclear fusion has already been invented, and it works incredibly well. So well in fact, that the only nuclear fusion reactor that we have access to is based 149.6 million kilometres away, and is called the sun.
It is that that this reactor has a design fault, the earth orbits it at an angle, meaning that we can’t access it at night time, and some regions of the world see less of it than others. If we could capture all the energy that falls on the Earth from this nuclear fusion reactor for 88 minutes, we would have a year’s worth of electricity supply. If we were to cover an area roughly the size of Yorkshire in solar panels, we could create enough electricity for the entire global economy – if it wasn’t for that pesky habit that the sun has of disappearing off the edge of the horizon.
Lithium ion batteries are great, and have fallen in cost by some 80 per cent since 2008, but they are still some way from fully compensating us for the unreliable sun.
It boils down to how long a battery can last. If you can re-charge it an infinite amount of time, then, within reason, it is almost irrelevant how much it cost to make.
But as all owners of smart-phones know, lithium ion batteries have a limited life. Supercapacitors can have a lifetime which is around 500 times longer than that of a lithium ion battery. Imagine that, a battery in an electric car that can last for several generations.
Supercapacitors have one other advantage, they can be charged up super-fast.
They have one major drawback. They don’t have much storage capacity. It boils down to surface area. The larger the surface area of the conductor in a supercapacitor, the greater the storage capacity.
One solution to this problem may come with the new generation of super-materials. Take graphene, the one-atom thick material of pure carbon, first isolated at Manchester University in 2004. One gram of graphene has the same surface area as a tennis court, meaning that in theory, it would make a wonderful supercapacitor.
Now scientists at The University of Central Florida, UCF, have created a new process for making flexible supercapacitors, using, yes, you have guessed it, newly discovered super-materials. The resulting supercapacitors composed of nanometre thick wires coated with two-dimensional materials.
Principal investigator, Yeonwoong ‘Eric’ Jung explained it thus: “There have been problems in the way people incorporate these two-dimensional materials into the existing systems – that's been a bottleneck in the field. We developed a simple chemical synthesis approach so we can very nicely integrate the existing materials with the two-dimensional materials."
Nitin Choudhary, a postdoctoral associate who conducted much of the research published recently in the academic journal, ACS Nano, said: “If they were to replace the batteries with these supercapacitors, you could charge your mobile phone in a few seconds and you wouldn't need to charge it again for over a week."
But there is an alternative.
Other researchers are looking at using supercapacitors as a kind of short-term battery. So, let’s say your phone has a lithium-ion battery and a supercapacitor, containing a super-material as a conductor. If you are never more than a few feet away from a charging point, you can use the super capacitor, re-charging every time you put the phone down, but use the lLithium ion battery for longer usage. Or say you are using your electric car to nip down to the shops, or short drive to the local railway station – you can use the supercapacitor for that. And only use the lithium ion battery for the much rarer longer distance journeys.
In this way the life of a lithium ion battery could be extended by an order of magnitude longer than the current few years. They could also be used by the national grid to offer back-up energy when it is only needed for a short period of time – for example, if the wind dies down for a few minutes and wind turbines stop generating electricity.
And that is why supercapacitors could save the world.