Troublesome green algae serve as coating substrate in record-setting battery

Sep 10, 2009

(PhysOrg.com) -- Unwanted blooms of Cladophora algae throughout the Baltic and in other parts of the world are not entirely without a positive side. A group of researchers at the Angstrom Laboratory at Uppsala University have discovered that the distinctive cellulose nanostructure of these algae can serve as an effective coating substrate for use in environmentally friendly batteries. The findings have been published in an article in Nano Letters.

"These algae has a special structure characterised by a very large surface area," says Gustav Nyström, a doctoral student in nanotechnology and the first author of the article. "By coating this structure with a thin layer of conducting polymer, we have succeeded in producing a battery that weighs almost nothing and that has set new charge-time and capacity records for polymer-cellulose-based batteries."

Despite extensive efforts in recent years to develop new cellulose-based coating substrates for battery applications, satisfactory charging performance proved difficult to obtain. However, nobody had tried using algal cellulose. Researcher Albert Mihranyan and Professor Maria Strømme at the Nanotechnology and Functional Materials Department of Engineering Sciences at the Ĺngström Laboratory had been investigating pharmaceutical applications of the cellulose from Cladophora algae for a number of years. This type of cellulose has a unique nanostructure, entirely different from that of terrestrial plants, that has been shown to function well as a thickening agent for pharmaceutical preparations and as a binder in foodstuffs. The possibility of energy-storage applications was raised in view of its large surface area.

"We have long hoped to find some sort of constructive use for the material from blooms and have now been shown this to be possible," says Maria Strømme, Professor in Nanotechnology and leader of the research group. "The battery research has a genuinely interdisciplinary character and was initiated in collaboration with chemist professor Leif Nyholm. Cellulose pharmaceutics experts, chemists and nanotechnologists have all played essential roles in developing the new material."

The article in , in effect, introduces an entirely new electrode material for energy storage applications, consisting of a nanostructure of algal cellulose coated with a 50 nm layer of polypyrrole. Batteries based on this material can store up to 600 mA per cm3, with only 6 per cent loss through 100 charging cycles.

"This creates new possibilities for large-scale production of environmentally friendly, cost-effective, lightweight energy storage systems," says Maria Strømme.

"Our success in obtaining a much higher charge capacity than was previously possible with batteries based on advanced polymers is primarily due to the extreme thinness of the polymer layer," says Gustav Nyström.

More information: pubs.acs.org/doi/pdfplus/10.1021/nl901852h

Source: Uppsala University (news : web)

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User comments : 9

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moj85
4 / 5 (1) Sep 10, 2009
But how does this compare with current batteries? is 6% loss in 100 charges considered good compared to our current technology?
sesc
4 / 5 (1) Sep 10, 2009
Cool to read about research from our lab here on Physorg! Just thought I'd point out that the name is "Ångström Laboratory" (like the length unit, 1/10 nm), not "Ĺngström".
danman5000
4 / 5 (1) Sep 10, 2009
Yeah I would have liked to see a comparison to current battery technology, as these numbers don't mean too much to me. 6% in 100 charges sounds like a lot to me, but ofc this is just research soI'm sure that will improve. It's definitely a neat idea for a battery.
laserdaveb
not rated yet Sep 10, 2009
600 ma what? hour..day..second?
NeilFarbstein
2 / 5 (2) Sep 10, 2009
thats good but others have beaten it
ormondotvos
5 / 5 (1) Sep 10, 2009
Dear physorg:

Please stop publishing half articles. Comparisons with real units would be nice.

And Angstrom? Please answer the questions.

Energy density in wh/kg?

Projected deterioration in 10,000 cycles?

I need one for my electric airplane.
sesc
3 / 5 (1) Sep 11, 2009
@orm: The energy density is right there in the linked abstract: 38-50 mAh/g of the active material.
This is basic research guys so 10k cycles is something for the future. Suffice to say they're happy for now as this marks a clear improvement over previous results with this kind of materials.
bfast
4 / 5 (2) Sep 11, 2009
Amp hours ain't energy dencity, watt hours is. At 1 volt, 50mah/g = 50wh/kg. To get the 1000wh of a typical deep cycle lead-acid battery we'd have a 20kg battery. Some improvement over lead acid, but hardly what the cutting edge of lithium ion is doing.
sesc
4.5 / 5 (2) Sep 11, 2009
@bfast, agreed, I was a bit quick there this morning, sorry. I think the problem is that we're comparing apples and pears really. It was fairly obvious for me that if you build a battery out of filter paper, water & algae, the goal isn't to drive airplanes or cars... not even to compete with Li ion heavy-duty stuff. This is made clearer in a German article I just read, http://bit.ly/2jzGu -- main goal is to provide power for "smart clothes" & packaging, and low-tech batteries for developing countries that can easily be made on site.
For such small batteries mAh is the normal capacity unit. Given an operating voltage (which isn't specified here, I'm afraid) that is all the data one needs. Wh comes into play in the car-battery league, or that's my experience.

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