SCIENTISTS at the US Department of Energy’s Brookhaven National Laboratory say a new form of activated graphene could yield superior supercapacitors for energy storage.
The novel form of carbon has a nanoscale structure which allows the material to act like a super-absorbent sponge for electric charge.
The material was created at the University of Texas and can be incorporated into supercapacitor energy-storage devices. Supercapacitors have very high storage capacity as well as superfast energy release, quick recharge time, and a lifetime of at least 10,000 charge/discharge cycles.
The supercapacitors powered by activated graphene could be used in electric vehicles, which often require a quick release of energy, as well as to smooth out power availability from intermittent energy sources, such as wind and solar power.
While both supercapacitors and batteries store electric charge, batteries do so through chemical reaction, energy is stored and released relatively slowly over a fairly long time.
Supercapacitors, on the other hand, store charge in the form of ions on the surface of the electrodes, similar to static electricity, rather than relying on chemical reactions.
Charging the electrodes causes ions in the electrolyte to separate, or polarise, causing charge to be stored at the interface between the electrodes and the electrolyte. Pores in the electrode increase the surface area over which the electrolyte can flow and interact, increasing the amount of energy that can be stored.
With the new material, supercapacitors can have an energy-storage capacity, or energy density, that is approaching the energy density of lead-acid batteries.
The researchers used potassium hydroxide to restructure chemically modified graphene platelets. Such a process was previously used to create various forms of "activated carbon," which have pores that increase surface area and are used in filters and other applications.
The scientists say the processing techniques used to create the new form of carbon are readily scalable to industrial production. This could have massive implications on research and technology in both energy storage and energy conversion.
