Tiny Flexible Power Supply
August 7, 2013

Researchers Develop Tiny, Flexible Power Supply

Peter Suciu for redOrbit.com - Your Universe Online

Searchers from the Royal Society of Chemistry have created a tiny power supply that is made of a flexible material. This powerful micro-supercapacitor is just nanometers thick - or thin, as the case may be - and this could help electronics companies develop devices such as mobile phones and cameras that are smaller, lighter and thinner than ever before.

The bottleneck for making smaller electronic devices such as mobile phones has been in also reducing the size of the power supplies in the electronic circuits. However, supercapacitors are attractive power supplies, as these can store almost as much energy as a traditional battery, while offer the advantage of high-speed energy discharge.

Supercapacitor electrodes are normally made from carbon or other conductive polymers. As a result these can be relatively costly - the reason why many gizmos and gadgets get pricier the smaller they get.

Now the team at the Royal Society of Chemistry, led by Professor Oliver G. Schmidt at the Leibniz Institute for Solid State and Materials Research in Dresden (IFW-Dresden), has examined the use of more affordable materials including manganese dioxide.

As an alternative electrode material it has the promise to not only be far less expensive than carbon or conducting  polymers, but but also to be more environmentally friendly. However, manganese dioxide has not been a natural choice for an electrode material because it isn't typically electrically conductive, nor is it naturally flexible or strong.

This would seem to be enough to make researchers look to other alternative materials; however, the researchers have been able to overcome these limitations by vaporizing the manganese dioxide using an electron beam and then allowing the gaseous atoms to precipitate into thin, flexible films. The researchers further incorporate very thin layers of gold into the films to improve the electrical conductivity of the material.

The resulting tests on the new micro-supercapacitor showed significant promise, and the researchers found that the tiny, bendy power supply can store more energy and provide more power-per-unit volume than even state-of-the-art supercapacitors.

"Supercapacitors, as a new class of energy device, can store high energy and provide high power, bridging the gap between rechargeable batteries and conventional capacitors," said Dr. Chenglin Yan, leader of the research group at IFW-Dresden.

"So we thought a micro-supercapacitor would be an important development in the rapid advance of portable consumer electronics, which need small lightweight, flexible micro-scale power sources."

The finds suggest that the technology could be applied to many miniaturized technologies, including implantable medical devices and even active radio frequency identification (RFID) tags for self-powered miniaturized devices.

Moreover, the flexible technology could open up new possibilities for wearable electronics. This could bolster the wearable electronics market, which is already expected to reach $8.36 billion by 2018 according to recent reports.

The next step the team faces is finding a cheaper alternative to gold to improve the conductivity of the micro-supercapacitor.

"The major challenge we had to overcome in developing this technology was to obtain really high energy density on the micro-scale, at a low cost," added Yan. "The inclusion of gold in our micro-supercapacitor makes it more expensive, so we are now looking at replacing gold with cheaper metals, such as manganese, to make the device more practical for the market."

The findings of the new research by the Royal Society of Chemistry were published in the journal Energy & Environmental Science.

"Compared with other supercapacitors, which are not portable and are relatively bulky, the device demonstrated here allows fast and reliable applications in a portable and smart fashion," the paper states. "Furthermore, the nature of the process allows the micro-supercapacitor to be integrated with other micro-devices, to meet the need for micro-scale energy storage."