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Putting the ‘super’ in Europe's capacity for green power

With the rise in demand for green transportation, European researchers in the 'ILHYPOS' project have developed a new supercapacitor that could help power the next generation of electric cars.

The ILHYPOS supercapacitor soft pack © Ahmed ElAmin
The ILHYPOS supercapacitor
soft pack
© Ahmed ElAmin

Researchers working in the EU-funded ILHYPOS project say their new supercapacitor is more environmentally friendly and safer than those currently on the market. In developing the component for electrical circuits, they have also positioned Europe as a leader in the new field of high-voltage supercapacitors.

Speaking at the final ILHYPOS project meeting in Bologna on 21 July 2009, European Commission Scientific Officer Maurizio Maggiore said the project complements other EU-funded initiatives targeting the development of better hydrogen and fuel cell vehicles for green transportation.

“This project provides a potential solution for the development of a commercial fuel cell vehicle,” Maggiore said. “The new supacapacitor and the ionic liquid they have developed supports this goal. It has also made Europe competitive in the global supercaps market.”

Playing a supporting role

Regular capacitors are widely used as a means of storing or regulating small amounts of electrical energy in many of the devices and machines we use in everyday life, such as cell phones or computers. As part of an electrical circuit, they can be used to maintain a power supply for use on demand, such as audio system speakers, or to provide energy when batteries are being changed in a device.

The supercapacitor, or ultracapacitor, the popular name for an electrochemical capacitor, is able to pack a lot more energy into the same space compared to a regular capacitor. As they can store and release specific amounts of high-voltage energy very rapidly, supercapacitors are used as a sort of intermediary device to start large motors, such as those used on diesel trucks and railroad locomotives. They are used to store and release the sharp bursts of energy needed in consumer devices, such as flash units on portable cameras.

Their ability to store energy quickly also makes them useful for re-capturing energy that might otherwise have been lost, such as when braking a vehicle. More recently, supercapacitors are being examined for use in fuel-cell, hybrid and electric vehicles. By putting supercapacitors to work on the draining job of providing bursts of power when needed, batteries or fuel cells can then be used to provide power for other tasks over longer periods. This extension of the ability of electric vehicles to run for longer periods is crucial to their wider acceptance by the public.

Filling a market gap

Unfortunately, many supercapacitors on the market require special care for use in fuel-cell, hybrid or electric vehicles. Commercial ones make use of electrolyte solutions made up of a salt dissolved in an organic solvent. The volatility of the organic solvents increases sharply with temperature, making such supercapacitors potentially unsafe beyond the 50-60°C range in which fuel-cell and hybrid cars operate.

A project providing answers

Mario Conte © Ahmed ElAmin
Mario Conte
© Ahmed ElAmin

The ILHYPOS prototype fills this gap in the market. Project researchers targeted the development of a supercapacitor for a high-temperature environment with specific energy, power and safety requirements, and based on environmentally friendly materials.

They developed an electrolyte, a non-flammable ionic liquid or salt that was able to “significantly increase” the cell voltage available from the prototype supercapacitor to between 3.5V and 4V, said project coordinator Mario Conte, a scientist with Italy’s National Agency for New Technologies, Energy and the Environment.

"Tests showed the electrolyte remained stable, was non-toxic and operated at temperatures ranging from -20°C to 60°C," Conte said at the final meeting, "exceeding the project’s targets. Charging and recharging stability targets were also achieved. We have demonstrated that the ionic liquid is a very safe electrolyte, and this is a key achievement of the project.”

The ionic liquid can also be used for fuel cells, electrochemical capacitors, dye-sensitive solar cells, and other electrochemical devices, such as and batteries, he added.

Gearing up for production

Project partners prepared and tested other novel materials and components for original hybrid and asymmetric cell designs, such as electrodes (activated carbon materials and new electronically conducting polymers) and separators for the cell components, all needed for the new supercapacitor. Arcotronics Industries developed the techniques and a pilot production line to demonstrate that the prototype supercapacitor could be mass produced.

The supercapacitor is assembled as a soft pack to minimise weight. The assembly method is similar to the process used in the production of lithium-ion batteries, making it easily adaptable for industry. Arcotronics is one of Europe’s leading manufacturers of capacitors and the machines used to make them.

ILHYPOS partners also performed simulations using mathematical models and applied them to a test prototype of a hybrid electric van. The van was developed by Micro-Vett, another project partner.

“The simulations showed there was a significant improvement in efficiency and design simplification,” said Conte.

The ILHYPOS team was made up of researchers from both public and private sectors. Commission Scientific Officer Maggiore said the project has demonstrated that the newly developed supercapicator can perform better than others on the market at normal operating temperatures. “In fact, they have done better than expected,” he said. “Now it is up to industry to decide how to apply their research.”