Published on August 16th, 2012 | by No Artificial18
Wooden Rechargeable Batteries
Researchers synthesize battery cathode from plant lignin derivatives, which today are mostly made from nonrenewable metals such as lithium or lead.
It may sound completely unreal but scientist Grzegorz Milczarek from Poznan University of Technology in Poland and Olle Inganäs from Linköping University in Sweden have been whittling away at the possibilities of creating a new type of low-cost, Earth-friendly rechargeable battery from wood waste.
Researchers combined a polymer with lignin, a waste material from the paper mills, to create a new kind of battery cathode.
Every battery has 2 electrodes: anode and cathode and are filled with an electrolyte. The aggregate result of the chemical reactions taking place within the electrolyte creates a flow of electrons between two electrodes, resulting in the release of electricity.
Electrolytes are often made of basic and no expansive chemicals. The electrodes, however, are not. They are made from nonrenewable metals such as lead, zinc, nickel, cobalt or lithium, and their cost can be prohibitively expensive.
Less expensive electrodes would be a potentially significant change in all areas of energy supply and energy consumption and that is what Dr Milczarek and Dr Inganas hope they have created.
A good cathode material must be capable of receiving and storing charge (in the form of positive ions and electrons) in large amounts and according to the scientists, whose research appears in the March 23 issue of Science, the new renewable battery cathode made of lignin combined with a polymer known as “polypyrrole”, effectively holds an electric charge.
“The advantage of using a renewable material for charge storage is the enormous amount of this material that is already being produced on Earth by growing plants, which contain about 20 to 30 percent lignin,” Inganäs says. “It is also a low-value material, currently being used for combustion. Lithium-ion batteries, on the other hand, require metal oxides and some of those materials, such as cobalt, are rather rare.”
Lignin is the second most common polymer produced in nature by living organism (the most common being cellulose.) And lignin is inexpensive. Paper is made generally of cellulose, the other component of wood, so the effluent from paper mills, known as brown or black liquor, is mainly water and lignin.
The reason Dr Milczarek and Dr Inganas believed lignin molecules might be suitable for use as cathodes was that they are rich in chemical groups called phenols, and phenols are very easily turned into quinones. It is these quinones that are the essential components. In combination with a polypyrrole, they provide just the sort of electron and proton receptors a cathode requires.
The two researchers’ findings suggest that the lignin-polypyrrole combination makes an effective cathode, able to store a lot of charge.
While the whole technology is still at it’s earliest stages, we could see the use of lignin batteries in our lifetime as we keep utilize our natural resources for renewable energy.
Grzegorz Milczarek and Olle Inganäs (2012) Renewable Cathode Materials from Biopolymer/Conjugated Polymer Interpenetrating Networks, Science 335 (6075), 1468-1471. doi: 10.1126/science.1215159