Power paper. Photo: Thor Balkhed.
Power paper. Photo: Thor Balkhed.

Researchers at Linköping University's Laboratory of Organic Electronics in Sweden have developed power paper – a new material consisting of nanocellulose and a conductive polymer that boasts an outstanding ability to store energy.

One sheet of the new power paper, 15cm in diameter and a few tenths of a millimetre thick, can store as much as 1 farad (F) of electrical charge, similar to supercapacitors currently on the market. The material can be recharged hundreds of times and each charge only takes a few seconds. It's a dream product in a world that requires new methods for storing renewable energy –from a windy day to a calm one, from a sunny day to one with heavy cloud cover.

"Thin films that function as capacitors have existed for some time," says Xavier Crispin, professor of organic electronics and co-author of an article on the research just published in Advanced Science. "What we have done is to produce the material in three dimensions. We can produce thick sheets." Other co-authors are researchers from KTH Royal Institute of Technology, Innventia, the Technical University of Denmark and the University of Kentucky in the US.

Power paper looks and feels like a slightly plastic-y paper and the researchers have amused themselves by making an origami swan from one piece, giving an indication of its strength. The structural foundation of the material is nanocellulose, which is produced when normal cellulose fibers are broken down by high-pressure water into fibers just 20nm in diameter. The researchers place this nanocellulose in a solution of water and then add the conductive polymer PEDOT:PSS, which forms a thin coating around the fibers.

"The covered fibres are in tangles, where the liquid in the spaces between them functions as an electrolyte," explains Jesper Edberg, a doctoral student. Edberg conducted the experiments together with Abdellah Malti, who recently completed his doctorate.

The new cellulose-polymer material has already set a world record in simultaneous conductivity for ions and electrons, which explains its exceptional capacity for energy storage, but could achieve even higher capacity with further development. Unlike the batteries and capacitors currently on the market, power paper is produced from simple materials, is lightweight, requires no dangerous chemicals or heavy metals, and is waterproof.

The power paper project has been financed by the Knut and Alice Wallenberg Foundation since 2012. "They leave us to our research, without demanding lengthy reports, and they trust us," says Magnus Berggren, director of the Laboratory of Organic Electronics. "We have a lot of pressure on us to deliver, but it's okay if it takes time, and we're grateful for that.

The challenge now is to develop an industrial-scale process for producing the power paper. "Together with KTH, Acreo and Innventia we just received SEK 34 million from the Swedish Foundation for Strategic Research to continue our efforts to develop a rational production method, a paper machine for power paper," says Berggren.

This story is adapted from material from Linköping University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.