Up to now, it has been assumed that electric cars would be battery operated and hybrid vehicles will form a major part of the market. Lithium is currently the most viable alternative to petrol and in consumer electronics. And it is attracting massive investment.
But what about the potential for an alternative technology – supercapacitors? Both batteries and supercapacitors are electrochemical energy storage media, but they are as different as night and day. Both are capable of energy storage and targeted energy release – and yet there are major differences between the two. Batteries store very large amounts of energy that is released slowly but constantly.
State-of-the-art supercapacitors can only store small amounts of energy (they have poor energy density per kilogramme) but they release this energy much faster and more powerfully with large short-term peak currents. Nevertheless, they have, until now, been unable to compete with conventional battery energy storage in many applications.
Now, a major scientific breakthrough based on groundbreaking research from the University of Surrey claims to have discovered new materials offering an alternative to battery power and between 1000 and 10,000 times more powerful than existing supercapacitors. Patents on the new materials have been filed by a company called Augmented Optics and its wholly owned subsidiary Supercapacitor Materials, registered specifically for the purpose of commercialising them.
Supercapacitors with these properties would allow electric cars to travel similar distances as petrol cars, but without the need to stop for lengthy recharging breaks of typically six to eight hours. Instead, they would recharge fully in the time it takes to fill a regular car with petrol. Very high energy density supercapacitors would also make it possible to recharge a mobile phone or laptop in just a few seconds.
The materials are known as hydrophilic polymers. They are based on large organic molecules composed of many repeated sub-units and bonded together to form a three-dimensional network. The test results from the new polymers suggest that extremely high energy density supercapacitors could be constructed in the very new future. Not only that, but the polymers age and show markedly improved conductivity with time – for reasons not currently understood, they self-organise over 30 days.
The proprietary materials developed in this project are electrically active hydrophilic polymers: an industrial grade version based on a hydrophilic structure amalgamated with a transparent condiucting polymer called PEDOT:PSS and a higher performance polymer where Imidazole is used instead of the PEDOT:PSS. Imidazole is an organic compound with the formula C3N2H4.
“These polymers also have many other possible uses in which tough, flexible conducting materials are desirable, including bioelectronics, sensors, wearable electronics, and advanced optics,” says Dr Ian Hamerton, now Reader in Polymers and Composite Materials from the Department of Aerospace Engineering, University of Bristol. “The materials can be processed on a large scale by low cost printing technology, offering excellent mechanical properties and the ability of incorporating a large variety of functional molecular structures.”