Unlike conventional lithium-ion batteries, supercapacitors can store and release electrical energy almost instantly; they are also characterized by low wear and resistance to high temperatures. Thanks to these properties, supercapacitors are widely used with electrochemical storage devices, extending their service life. Transport remains their chief area of application: they are used in hybrids and electric cars, where they can switch on during starting and braking.
The scientists from Skoltech have made an attempt to find out how the properties of supercapacitors are affected by changes in the carbon material from which their electrodes are made. “There are essentially two ways to increase the amount of energy stored in a supercapacitor. One could expand the effective surface area of the electrodes by structuring the surface. Alternately, one could introduce atoms of another element into the carbon material of the electrodes,” Stanislav Evlashin, one of the authors of the study, is quoted as saying by Skoltech.
In the course of the study, the authors exposed carbon nanowalls, which serve as the main material for supercapacitor electrodes, to plasma of various compositions. The best results were achieved during treatment with a mixture of nitrogen and argon (an inert gas): the surface capacitance of the supercapacitors doubled, shedding light on the electrochemistry of the process among other things.
“We discovered that at first the amorphous carbon remaining after the growth of the structures gets removed from the surface of the carbon nanowalls, after which new defects are created and heteroatoms are embedded in the structure of the carbon material. Amorphous carbon, just like nitrogen heteroatoms, contributes to the formation of pseudocapacitance,” Mr. Evlashin is quoted as saying by Skoltech.
