doi:10.1038/nindia.2016.95 Published online 25 July 2016
By using solvents, researchers have converted graphite into graphene nanosheets, which are potentially useful for making supercapacitors1.
Since supercapacitors can store electrical charge, they can be used to make energy-storage devices such as small capacitors, flexible (even rollable) energy-storage devices, transparent batteries and high-capacity, fast-charging devices.
One exciting property that has sparked significant interest in graphene is its ability to store electrical charge. A single graphene sheet large enough to cover a field would weigh just a fraction of a gram. The huge surface area associated with this small amount of graphene can be squeezed inside any battery.
To devise a simple method for making graphene, the researchers converted graphite into graphene nanosheets using probe-assisted ultrasound in conjunction with solvents such as water, glacial acetic acid and ethanol. They then explored the electrochemical properties of the nanosheets.
The graphene nanosheets exhibited a much higher capacity for storing charge than ones made using metal-oxide compounds. This higher capacitance can be attributed to non-aggregation of the graphene nanosheets.
At two different voltages, the nanosheets retained more than 90% of their original capacity to store charge even after 50 cycles of charging and discharging. The results show that the graphene nanosheets are electrochemically stable, suggesting that they could be used to make supercapacitors, the researchers say.
1. Balasubramaniam, M. et al. Tri-solvent mediated probing of ultrasonic energy towards exfoliation of graphene nanosheets for supercapacitor application. Mater. Lett. 182, 63-67 (2016)