Over the last few years researchers have been developing supercapacitors to become the next-generation battery. Instead of using chemical reactions, super capacitors are more powerful batteries equipped with an internal substrate that collects ions that release powerful bursts during discharge. Now one research team from the Illinois Sustainable Technology Center at the University of Illinois has produced super capacitors made out of wood. The researchers have figured out how to convert almost any type of wood into a biochar super capacitor that can produce as much power as an active carbon super capacitor at a fraction of the production cost.
For as long as the technology has been around, researchers have sculpted activated carbon in a long and expensive process using corrosive chemicals. With wood biochar supercapacitors, however, the team of scientists led by senior researcher Junhua Jiang can use the wood’s natural pore structure to serves as the electrode surface. All they have to do is heat the wood – including such varieties as white birch, white pine and red cedar – in a low oxygen environment to create a biochar.
To help further reduce the environmental impact, Jiang and his team activated their biochar with a bath of mild nitric acid to wash away the ash (calcium carbonate, potassium carbonate and other impurities.) What’s more, the remaining nitrate compound byproduct of this process can be used as fertilizer.
The researchers say the resulting biochar supercapacitors cost five to 10 times less to produce while delivering the same performance as those made from active carbon. After the wood-derived batteries have outlived their usefulness they can also be crushed and used as an organic soil amendment.
Images © University of Illinois