Blooms of Cladophora algae may be troublesome, but they do have a positive side. Researchers at the Ångström Laboratory of Sweden's Uppsala University have discovered that the cellulose nanostructure of these algae can serve as an effective coating substrate for use in environmentally friendly batteries.
"These algae have a special cellulose structure characterised by a very large surface area," says Gustav Nyström, a doctoral student in Nanotechnology. "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 was hard to get.
Researcher Albert Mihranyan and professor Maria Strømme at the Nanotechnology and Functional Materials Department of Engineering Sciences at the Ångström 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 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 because of its large surface area.
"We have long hoped to find some sort of constructive use for the material from algae blooms and have now been shown this to be possible," says Strømme. "The battery research has a genuinely interdisciplinary character and was initiated in collaboration with chemist professor Leif Nyholm. Cellulose pharmaceutics experts, battery chemists, and nanotechnologists have all played essential roles in developing the new material."
The new electrode material for energy storage applications consists 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 Strømme.