Novel power sources could be built from thin sheets of a material that is little more than paper. Robert Linhardt and colleagues of Rensselaer Polytechnic Institute in Troy, New Jersey, have discovered that cellulose dissolved in an ionic liquid and poured over carbon nanotubes could dry to form a thin paper layer with a backing layer made from carbon nanotubes.
Folding the paper over forms a supercapacitor, while adding a coating of lithium oxide makes it into a battery. These functions can be combined to make a supercapacitor charged by a battery, with both components based on the same technology. This could ultimately be useful for electrically powered vehicles, which need large bursts of power that a capacitor could provide more easily than a battery alone.