Saturday 23 July 2011

Super Batteries


Imagine charging your iPhone or mobile in a few seconds. Well, your imagination may someday turn into a reality, say scientists who claim to be working on "super batteries" which not only recharge in just seconds, but also have an almost indefinite lifespan.
A team, led by Dan Li of Monash University, says that a combination of two ordinary materials -- graphite and water -- could help produce such "super batteries" which perform on par with lithium ion batteries.
The scientists are, in fact, working with a material called graphene which may form the basis of the next generation of ultrafast energy storage systems, the 'Advanced Materials' journal reported.
"Once we can properly manipulate this material, your iPhone, for example, could charge in a few seconds, or possibly faster," said Li.
Graphene is the result of breaking down graphite, a cheap, readily available material commonly used in pencils, into layers one atom thick. It is strong, chemically stable, an excellent conductor of electricity and, importantly, has an extremely high surface area.
Li said these qualities make graphene highly suitable for energy storage applications.
"The reason graphene isn't being used everywhere is that these very thin sheets, when stacked into a usable macrostructure, immediately bond together, reforming graphite.
When graphene restacks, most of surface area is lost and it doesn't behave like graphene anymore," he said.The team has discovered the key to maintaining the remarkable properties of separate graphene sheets -- water.
Keeping graphene moist -- in gel form -- provides repulsive forces between the sheets and prevents re-stacking, making it ready for real-world application, say the scientists.
"The technique is very simple and can easily be scaled up. When we discovered it, we thought it was unbelievable. We're taking two basic, inexpensive materials -- water and graphite -- and making this new nanomaterial with amazing properties," said Li.
When used in energy devices, graphene gel significantly outperforms current carbon-based technology, both in terms of the amount of charge stored and how fast the charges can be delivered.
Li said the benefits of developing this nanotechnology extended beyond consumer electronics.
"High-speed, reliable and cost-effective energy storage systems are critical for the future viability of electricity from renewable resources. These systems are also the key to largescale adoption of electrical vehicles.Graphene gel is also showing promise for use in water purification membranes, biomedical devices and sensors," he said.

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