A group of researchers at the Russian Moscow-based Skolkovo Institute of Science and Technology (Skoltech) has tested how plasma treatment can significantly improve the capacitance of supercapacitors.
Basically, there are two ways to increase the amount of energy a supercapacitor stores. Either you enhance the effective surface area of the electrodes by intricate surface design, or you introduce foreign atoms into the carbon material of the electrodes.
Foreign atoms can be introduced into the carbon material of supercapacitor electrodes through plasma treatment.A specific mixture of nitrogen and argon plasma can double the areal capacitance of carbon nanowall electrodes.
“Our team is investigating ways to improve the performance of devices known as supercapacitors by tinkering with the carbon-based material used in their electrodes,” said Assistant Professor Stanislav Evlashin, the principal investigator of the study.
“We found that what happens first is that the amorphous carbon remaining after the growth of carbon nanowall structures is cleared away,” explained Evlashin. “This is followed by the formation of new defects and the incorporation of heteroatoms into the carbon material structure. Amorphous carbon, along with the heteroatoms of nitrogen, contributes to the occurrence of pseudo capacitance.”
“This could lead to the development of supercapacitors with greater energy storage capabilities and broader applications,” the researchers said. “These are energy storage devices that complement batteries in electric cars, trains, port cranes, and elsewhere.”
Supercapacitors have been considered as an interesting option for energy storage, in particular for rapid energy delivery – making them suitable for tasks such as acceleration and regenerative braking.
The major disadvantages are that they have a self-discharge rate of 10–20% per day, low voltages exist within individual cells so series connections are necessary to attain higher voltages, and supercapacitors deliver poor energy density compared to batteries.
