Scientists have developed power paper - a new material consisting of nanocellulose and a conductive polymer - that has an outstanding ability to store energy.
One sheet, 15 centimetres in diameter and a few tenths of a millimetre thick, can store energy similar to the supercapacitors currently on the market, researchers said.
The material can be recharged hundreds of times and each charge only takes a few seconds.
"Thin films that function as capacitors have existed for some time. What we have done is to produce the material in three dimensions. We can produce thick sheets," said Xavier Crispin, professor of organic electronics at Linkoping University in Sweden.
The structural foundation of the material is nanocellulose or cellulose fibres which, using high-pressure water, are broken down into fibres as thin as 20nm in diameter.
With the cellulose fibres in a solution of water, an electrically charged polymer (PEDOT:PSS), also in a water solution, is added. The polymer then forms a thin coating around the fibres.
"The covered fibres are in tangles, where the liquid in the spaces between them functions as an electrolyte," said Jesper Edberg, doctoral student, who conducted the experiments together with Abdellah Malti, who recently completed his doctorate.
The new cellulose-polymer material has set a new world record in simultaneous conductivity for ions and electrons, which explains its exceptional capacity for energy storage, researchers said.
Unlike the batteries and capacitors currently on the market, power paper is produced from simple materials - renewable cellulose and an easily available polymer.
It is light in weight, requires no dangerous chemicals or heavy metals and is waterproof, they said.
