It is a battery that looks like a piece of paper and can be bent or twisted, trimmed with scissors or moulded into any shape. While the battery is only a prototype, a few centimetres square right now, US researchers at Rensselaer Polytechnic Institute (RPI) in New York, who developed it, have high hopes for it in electronics and other fields that need smaller, lighter power sources. “We would like to scale this up to the point where you can imagine printing batteries like a newspaper,” said Robert Linhardt, a professor at the Center for Biotechnology and Interdisciplinary Studies at RPI.
Unlike other batteries, Linhardt explained, it is an integrated device, not a combination of pieces. The battery uses paper infused with an electrolyte and carbon nanotubes that are embedded in the paper. The carbon nanotubes form the electrodes, the paper is the separator and the electrolyte allows the current to flow.
Students at the school were the inspiration for the work, said Linhardt. His students were working on methods to dissolve paper and cast it into membranes for use in dialysis machines. Meanwhile, students of Pulickel Ajayan in RPI’s materials science department were trying to make carbon nanotube composites using polymers. The groups got together and found they could use paper instead of polymers and combine the projects.
Then came Omkaram Nalamasu’s students, also at RPI, who said the project—a thin sheet, black on one side and white on the other—resembled an electrical device.
And for more than 18 months, the groups developed the projects— into a battery, a capacitor which stores electricity, and a combination of the two.
Ajayan sees potential uses in combination with solar cells, perhaps layers of the paper batteries that could store the electricity generated until it is needed.