Both electrodes were lightweight and their large surface area provided high energy density of 110 Wh/kg, comparable to commercial batteries.
The latter material supports 3,000 times its own weight and can return to its original shape when unweighted.
Nanotubes, a powdered nickel catalyst and sugar were mixed.
Dried pellets of the substance were then compressed in a steel die in the shape of a screw.
The nickel was removed, leaving a screw-shaped piece of foam.