Researchers from George Washington University developed a carbon nanotube and graphene composite material based ultracapacitors that combines high performance with low cost. The specific capacitance of the device is three times higher compared to CNT-pure capacitors.

The researchers explain that the hybrid structure is useful because the graphene flakes provide high surface area and good in-plane conductivity, while the carbon nanotubes connect all of the structures to form a uniform network. In addition, the production method is simple, scalable and low cost.

To synthesize the new composite, the researcher vaporized a hollow graphite rod filled with metallic catalyst powder with an electric arc. They then mixed the two nanostructures together to form an ink that they rolled onto paper (a common capacitors separator).