Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Ultracapacitor Delivers a Jolt of Energy at a Constant Voltage

20.07.2012
Chemical batteries power many different mobile electronic devices, but repeated charging and discharging cycles can wear them out.

An alternative energy storage device called an ultracapacitor can be recharged hundreds of thousands of times without degrading, but ultracapacitors have their own disadvantages, including a voltage output that drops precipitously as the device is discharged. Now a researcher from the University of West Florida has designed an ultracapacitor that maintains a near steady voltage.

The novel constant-voltage design, which may one day help ultracapacitors find new uses in low-voltage electric vehicle circuits and handheld electronics, is described in the American Institute of Physics’ Journal of Renewable and Sustainable Energy.

Standard capacitors store energy in an electric field created when opposite electrical charges collect on two plates separated by a thin insulating material. In ultracapacitors the surface area of the plates is increased with a coating of porous activated carbon, which is packed with tiny holes and cracks that can capture charged particles. The space between the plates is filled with an electrolyte solution containing positive and negative ions. As charge accumulates on the plates, they attract ions, creating a double-layer of stored energy.

In both standard capacitors and ultracapacitors, the voltage drops as the stored charge is released. Most electronic devices, however, require constant voltage to operate. An electronic circuit called a DC-DC converter can change the dropping voltage of the capacitor into a constant voltage output, but the converters experience problems below one volt.

“A significant portion of the energy of the ultracapacitor is held below one volt,” notes Ezzat Bakhoum, a professor of electrical engineering at the University of West Florida. “Operation in that region is very difficult because the DC-DC converter cannot function at such low voltage. Applications where the use of an ultracapacitor is precluded because of this problem include low-voltage systems in electric vehicles, hand-held power tools, toys, and cameras, just to name a few.”

So Bakhoum has designed an ultracapacitor that maintains a near-constant voltage without a DC-DC converter. The ultracapacitor is fitted with an electromechanical system that can slowly lift the core of the device out of the electrolyte solution as the stored charged is released. As the electrolyte drains away, the device can hold less charge, thus lowering, its capacitance. Since the voltage of the capacitor is related to the ratio of the stored charge to the capacitance, the system maintains a steady voltage as charge is siphoned off.

Bakhoum built and tested a prototype of the new ultracapacitor. After attaching a 35-watt load to the device, he found he could successfully program the voltage to stay within a 4.9 to 4.6 volt range. Testing also showed that the constant-voltage mechanism operates with a 99 percent efficiency or higher. The lifetime of the electromechanical motor is expected to be about the same as the lifetime of the ultracapacitor’s core, Bakhoum writes.

“The ultracapacitor is a wonderful new energy storage device that has many advantages by comparison with batteries,” says Bakhoum. In addition to their near limitless ability to be recharged, ultracapacitors can release a jolt of energy much more quickly than batteries. One current disadvantage of commercially available ultracapacitors, that they store only a fraction of the energy per unit mass that batteries store, is a challenge that is still being researched. Some groups have experimented, for example, with changing the structure of the electrode to increase surface area, and thus the amount of charge that can be stored.

For Bakhoum, future research steps include modifying the design of the constant-voltage ultracapacitor system so that it can be installed at any angle. He may also explore whether the same type of constant-voltage approach is suitable for new, high-energy-density ultracapacitors.

Paper: “Constant Voltage Ultracapacitor”
Link: http://jrse.aip.org/resource/1/jrsebh/v4/i3/p033116_s1
Journal: Journal of Renewable and Sustainable Energy
Author: Ezzat G. Bakhoum (1)
(1) University of West Florida

Catherine Meyers | Newswise Science News
Further information:
http://www.aip.org

More articles from Power and Electrical Engineering:

nachricht A simple, yet versatile, new design for chaotic oscillating circuitry inspired by prime numbers
22.05.2019 | Tokyo Institute of Technology

nachricht Machine learning speeds modeling of experiments aimed at capturing fusion energy on Earth
20.05.2019 | DOE/Princeton Plasma Physics Laboratory

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New studies increase confidence in NASA's measure of Earth's temperature

A new assessment of NASA's record of global temperatures revealed that the agency's estimate of Earth's long-term temperature rise in recent decades is accurate to within less than a tenth of a degree Fahrenheit, providing confidence that past and future research is correctly capturing rising surface temperatures.

The most complete assessment ever of statistical uncertainty within the GISS Surface Temperature Analysis (GISTEMP) data product shows that the annual values...

Im Focus: The geometry of an electron determined for the first time

Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.

The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or...

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

New system by TU Graz automatically recognises pedestrians’ intent to cross the road

27.05.2019 | Information Technology

On Mars, sands shift to a different drum

24.05.2019 | Physics and Astronomy

Piedmont Atlanta first in Georgia to offer new minimally invasive treatment for emphysema

24.05.2019 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>