Hybrid Graphene-Nanotube Ultracapacitor Developed
The ability to store energy enabled a technological revolution that has given us laptop computers, smartphones, and much more. We are starting to approach the limits of the traditional battery though, as devices keep trying to get smaller and consumers want them to charge faster. One potential alternative to batteries are ultracapacitors, which can be charged very rapidly, and now researchers at George Washington University's Micro-propulsion and Nanotechnology Laboratory have developed a new kind with excellent performance, but a low cost, as reported by the American Institute of Physics.
Carbon, the stuff of pencil lead, diamonds, and organic molecules can express some very interesting and useful properties, when in the proper form. Two rather interesting carbon structures are graphene, an atom-thick sheet of carbon, and nanotubes. The researchers discovered a simple way to produce both, and started investigating how both could be used. They found that if they mixed both into an ink and rolled it onto paper, they would have an ultracapacitor. Ultracapacitors of just carbon nanotubes have been tested before, but the addition of graphene flakes, their surface area and in-plane conductivity, gave this design three times better specific capacitance.
The method the researchers found for producing the graphene and nanotubes was to use an electric arc to vaporize a hollow graphite rod, with a metallic catalyst powder inside. Compared to other ultracapacitors with similar performance to this, this production method is significantly cheaper, and res resulting device is both small and light, which is important as devices shrink.