Copper wire that can store electricity

The store-and-transmit cables using nanotechnology is expected to transform high-technology sectors like aircraft manufacturing, spacecraft by embedding these wires throughout the body, significantly boosting total energy storage, while saving space.

"The technique could be used to lighten airplanes and spacecraft, to store excess energy from solar panels and to further miniaturize small electronics," said Dr. Jayan Thomas of University of Central Florida.

"The technique could also replace high energy-density supercapacitors, which provides the quick shot of energy that cars and heavy machinery need to start," Dr. Thomas was quoted by the Indian Science Journal (ISJ) web site, as saying.

Dr. Thomas and his research student Zenan Yu of University of Central Florida, developed coaxial cables with a copper core surrounded by a supercapacitor sheath, which can both transmit and store electricity.

The super capacitor was created by growing nanowires perpendicular to the surface of the wire and these nanowires were coated with a gold palladium alloy, which acts as a current collector for the super capacitor.

The brush-like formation is then given a coating of manganese oxide. This creates a 100-fold increase in surface area, compared to a conventional copper wire, for energy storage.

The nanowires serve as a sheath, covering the copper wire and for the first electrode of the supercapacitor. This is further wrapped in a plastic sheath, with a second electrode, made of nanowires on a copper foil. While the central core conducts electricity, the super capacitor stores additional electricity.

The team also tested its flexibility, strength, wear-resistance of the wire to ensure it is well-insulated and no electrode fractures or short-circuits on bending. They have bent their device at different angles upto 100 times and found its capacitance was generally stable, although folding it 100 times at 180 degree led to a loss of about seven per cent of the initial capacitance.

A single supercapacitor cell produces 1 to 3 volts, and generate direct current, while multiple cells connected in sequence can achieve 12-24 V needed for applications such as electronic devises, humanoid robots and automotive electronics. However, this device cannot be used for household applications, which uses higher voltage and alternating current.

The energy storable cables could be useful for storing power generated by solar panels or wind-power generators. This could also help miniaturize electronic devices by decreasing the size of bulky lithium-ion batteries.

However its adoption as replacement for stand-alone supercapacitors or batteries will depend on cost of inputs and development of simple manufacturing processes.

Dr. Jayan Thomas, who hails from Kerala, did his college education from Mahatma Gandhi University, Kottayam and his doctoral research and post-doctoral fellowship from Cochin University of Science and Technology.