French scientists demonstrated that seaweed, when burned to a crisp, is a great material for making supercapacitors that could provide more power than traditional batteries. Today, the electrodes in supercapacitors are usually made from activated carbon. According to Francois Béguin of the CNRS Research Centre on Divided Matter and his colleagues, cooked seaweed carbon can be charged to much higher voltages making small supercapacitors to power, say, laptops, more of a practical possibility. From News@Nature:
"People working on carbons are always looking for improved properties," says Mildred Dresselhaus, a specialist in carbon materials at the Massachusetts Institute of Technology. She points out that coconut shells are already used as a source of porous carbon for water filtration and other applications. "Low-tech routes are commonly used when they do the job," Dresselhaus says…
The French team cooked alginate (abundant in brown seaweeds) in an air-free enclosure, turning it into a black powder. They then combined this with a polymer binder to make a hard material, which they shaped into electrodes for supercapacitors.
The amount of electrical charge and energy that these devices can hold is comparable to that of capacitors made from commercial activated carbons. But the seaweed capacitors can be charged to voltages twice as high without breaking down, and the material is twice as dense. They hold up well over time, too: their charge-storage capacity declines by only 15% after 10,000 cycles of charging and discharging.
