Jayan Thomas, an assistant professor at the University of Central Florida’s NanoScience Technology Center, thought it would be interesting to see if the copper cable we use to conduct electricity could also be used to store energy. It was an intriguing enough idea that he and his graduate student, Zenan Yu, set out to see if they could make it possible.
Thomas and his team had previously been working on inexpensive nanoprinting techniques for producing supercapacitors with highly ordered nanoelectrodes. When they looked for a solution to both conducting and storing electricity in a single cable they again turned to supercapacitors.
In this latest research, which will be reported in the 30 June edition of Advanced Materials, Thomas and Yu essentially wrapped a supercapacitor around a copper cable. The problem they had to overcome was how to create the two electrodes necessary for a supercapacitor.
The trick was to grow electrochemically active nanowires (or nanowhiskers) on a copper wire that had been coated with copper oxide. This layer of nanowires sticking out from the cable created the first electrode for the supercapacitor. The researchers then covered the copper cable and nanowhiskers with a polymer. Next they surrounded the polymer with a nanowire coated copper coil, forming the second electrode.
The insulation of the separator allows the inner copper wire to continue conducting electricity while the layers around the wire can independently store the energy.
In an article published in the journal Nature discussing the work, it is pointed out that design is limited to direct current (DC), which could prove useful for powering small electronic devices and automotive electronics, but not for household or industrial uses that need alternating current (AC).
While this is still pretty preliminary research, Thomas believes that the technology could be transferred to other types of materials such as fibers that could be woven into clothing to power electronic devices. Others believe that the supercapacitor cables might be effective for storing the electrical energy produced by solar panels or wind turbines. In any case, the manufacturing costs of the cables will need to be kept low if they are realistically going to be able to offer an alternative to today's supercapacitor devices.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.