Running on seaweed

French scientists take novel approach to plant-based materials for power storage

From portable electronics to cleaner cars, we’re constantly pushing the limits of battery technology for onboard energy storage. But who’d have thought seaweed could be the stuff to give a big boost to ‘supercapacitor’ alternatives?

Seaweed’s special powers - and economic attractions - have been brought to the fore by a French scientific team led by Francois Béguin at CRMD in Orléans. Interviewed in Nature’s news blog, Béguin says he’s optimistic about bringing the technology into use in the near future, and is in touch with a company interested in doing so.

If it works, it means devices that depend on batteries - from laptops to cars - could run longer, with more oomph.

Most existing supercapacitors - which are capable of providing higher voltage power than batteries - currently consist of a pair of charged-up electrodes made of activated carbon, akin to graphite. The big drawback of this material is that it is porous, and too bulky to use for storing much energy. Béguin’s team, focusing on plant-based alternative materials, faced the problem that cellulose electrodes tended to give up most of their charge-bearing oxygen atoms when they got hot - as they would in normal use. The breakthrough came with the discovery that alginate, a low-cost polymer extracted from seaweed (and already used in thickening foods and cosmetics), could be baked and shaped into electrodes that held on to their oxygen atoms much more tenaciously, keeping their integrity at much higher temperatures than cellulose. Twice as dense as activated carbon, they could not only be charged to much higher voltages without breaking down, but also retained their capacity well under the typical pattern of use, with repeated cycles of charging and discharging. So don’t be too surprised if the restaurants of Orléans start filling up with laptop company execs and hybrid vehicle design teams… - Roger East

10 October 2006

Roger East