Paper batteries could soon be powering household gadgets, medical devices and electric vehicles.
Scientists have devised a new kind of ultra-thin battery that resembles a simple sheet of black paper.
More than 90% of the battery is made of cellulose, the same plant material used in newsprint, writing paper and packaging.
Researchers at Rensselaer Polytechnic Institute in Troy, New York, US, embedded the paper with carbon “nanotubes”, tiny tube-like structures which act as electrodes.
The body of the paper is infused with an electrolyte, a substance containing free electrically charged atoms, or ions.
The device is engineered to function both as a high-energy lithium battery and a supercapacitor. Both store energy, but capicitors release theirs in a quick burst after reaching their maximum storage potential.
The paper battery can be rolled, twisted, folded or cut into any number of shapes without losing its ability to function.
A number of batteries can also be stacked, like a ream of printer paper, to boost the total power output.
Professor Robert Linhardt, who led the research team whose work was reported today in the journal Proceedings of the National Academy of Sciences, said: “It’s essentially a regular piece of paper, but it’s made in a very intelligent way.
“We’re not putting pieces together – it’s a single, integrated device. The components are molecularly attached to each other: the carbon nanotube print is embedded in the paper, and the electrolyte is soaked into the paper. The end result is a device that looks, feels, and weighs the same as paper.”
The paper battery can operate at temperatures as high as 149C and as low as minus 73C.
A major potential application is as a power supply for medical devices implanted in the body.
The scientists found that it can be activated by naturally occurring electrolytes in human sweat, blood and urine.
“It’s a way to power a small device such as a pacemaker without introducing any harsh chemicals – such as the kind that are typically found in batteries - into the body,” said co-researcher Dr Victor Pushpara.
The researchers are now working on a way to mass produce the devices cheaply. They hope ultimately to produce the paper battery using a newspaper-type roller printer.