Battery cathode made of waste byproducts from paper industry promises sustainable energy storage

March 22, 2012

A breakthrough for inexpensive electricity from solar cells, and a massive investment in wind power, will mean a need to store energy in an intelligent way. According to research at Linköping University (Sweden), published in Science, batteries of biological waste products from pulp mills could provide the solution.

Organic solar cells based on conductive plastic is a low cost alternative that has achieved high enough performance to be upscaled and, in turn, become competitive. However, solar electricity must be able to be stored from day to night, as well as electricity from wind turbines from windy to calm days.

In conventional batteries metal oxides conduct the charge. Materials, such as cobalt, are expensive and a limited resource, therefore, low cost solutions are sought preferably with renewable materials.

"Nature solved the problem long ago," says Olle Inganäs, professor of biomolecular and organic electronics at Linköping University (LiU) and lead author of the article in this week's edition of Science.

He drew inspiration from the process of photosynthesis, where electrons charged by solar energy are transported by quinones; electrochemically active molecules based on benzene rings comprised of six carbon atoms. Inganäs chose the raw material brown liquor that is a by-product from the manufacture of paper pulp. The brown liquor is largely composed of lignin, a biological polymer in the plant cell walls.

To utilise the quinones as charge carriers in batteries, Inganäs and his Polish colleague Grzegorz Milczarek devised a thin film from a mixture of pyrrole and lignin derivatives from the brown liquor. The film, 0.5 microns in thickness, is used as a cathode in the battery.

The goal is to offer ways to store renewable electricity where it is produced, without constructing up large grids. In several countries, major investments are planned. Meanwhile, the performance of cheap has now reached a critical level. A research team at the University of California, Los Angeles, has recently reported efficiency of more than 10 percent of the energy of the captured sunlight.

According to Inganäs who for many years conducted research on organic , the efficiency is sufficient to initiate an industrial scale up of the technology.

"Now we need more research into new based on cheap and renewable raw materials. Lignin constitutes 20-30 percent of the biomass of a tree, so it's a source that never ends."

Explore further: Toward a 'green grid' for delivering solar and wind-based electricity

More information: Renewable cathode material from the biopolymer/conjugated polymer interpenetrating networks by Grsegorz Milczarek and Olle Inganäs. Science 23 March 2012.

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1.8 / 5 (5) Mar 22, 2012
Again, the news tells nothing of importance.

Energy density? Cost? Is it actually working?
3 / 5 (4) Mar 22, 2012
More reasons to cut down trees in developing nations... yeah that's good for the environment.
1 / 5 (6) Mar 22, 2012
Toilet paper.
2 / 5 (27) Mar 22, 2012
"Inganäs chose the raw material brown liquor that is a by-product from the manufacture of paper pulp." By-product which is usually disposed of, frequently in rivers.

Energy density and cost in the article in Science, but you must be a member.
1.7 / 5 (12) Mar 22, 2012
I think you missed the point that these batteries are being made from what is now a biological waste product; not from newly cut trees. And as Weyerhaeuser has shown, trees can be grown and harvested in an ecologically sustainable manner when managed properly; making this a renewable resource.
1 / 5 (5) Mar 23, 2012
Can someone with a Nature membership post the actual numbers for this thing?
Its a pity there isn't a website where people could get relevent information about science without having to trawl through papers and get through paywalls...

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