Biochar used to produce supercapacitors

While batteries rely on chemical reactions to produce sustained electrical energy, supercapacitors collect charged ions on their electrodes (in this case, the biochar, produced by heating wood in low oxygen), and quickly release those ions during discharge.

This allows them to supply energy in short, powerful bursts – during a camera flash, for example, or in response to peak demand on the energy grid, said study leader Junhua Jiang, a senior research engineer at the Illinois Sustainable Technology Center at the University of Illinois.

Many of today’s supercapacitors use activated carbon, usually from a fossil-fuel source, Jiang said in a statement.

‘Costly and complicated procedures are normally used to develop the microstructures of the carbon – to increase the number of pores and optimize the pore network,’ he said. ‘This increases the surface area of the electrode and the pores’ ability to rapidly capture and release the ions.’

In wood-biochar supercapacitors, the wood’s natural pore structure is said to serve as the electrode surface, eliminating the need for advanced techniques to fabricate an elaborate pore structure.