More and more the world is looking to capacitors to replace batteries. The reasons for wanting such a change include faster charging times and safety precautions, as capacitors do not need dangerous chemicals. Finding capacitors that can challenge batteries is not very easy though, because they generally have a lower energy density than batteries. However, micro and nanoscale capacitors could be built and linked together to potentially rival batteries. Researchers at Rice University have recently discovered a previously overlooked microcapacitor with the highest capacitance reported for something of its size.
A common method for making graphene is chemical vapor deposition on sheets of copper. When this happens there is the possibility for a layer of copper oxide to form between the copper and the graphene, and numerous graphene studies have noted this, but never looked too carefully at it. The Rice researchers almost did not look at it either, as they were just trying to make copper nanowires coated in carbon. Testing the wires gave some unexpected results because the copper oxide layer was still there. Closer examination showed it was acting as an insulator between the conductive graphene and copper, forming a capacitor. A good capacitor too as it breaks the records for other microcapacitors.
By connecting together millions of these nanocables, it should be possible to create a large-scale energy-storage device. Exactly how much energy such an array could store is hard to say at the moment, especially as quantum mechanics plays a role at the scale of a single nanocable. However, even if it is not able to challenge a conventional battery, it may still be able to transmit radio signals at the nanoscale, similar to the coaxial cables the give our televisions an image.