Researchers from Tomsk Polytechnic University (TPU), along with collaborators from the University of Lille in France, have synthesized a new material, based on reduced graphene oxide (rGO), for energy storage devices and supercapacitors.
The rGO modification technique that involves the use of organic molecules, derivatives of hypervalent iodine, reportedly enabled acquiring a material that is capable of storing 1.7 times more electrical energy.
Despite their potential, supercapacitors are not as widespread as they could be. For further development of the technology, it is required to enhance the efficiency of supercapacitors. One of the key challenges is to increase the energy capacity.
Pavel Postnikov, Associate Professor and Research Supervisor, Research School of Chemistry and Applied Biomedical Science, Tomsk Polytechnic University, said: “It can be achieved by expanding the surface area of an energy storage material, rGO in this particular case. We found a simple and quite fast method. We used exceptionally organic molecules under mild conditions and did not use expensive and toxic metals”.
Powder-form rGO is coated on the electrodes, which leaves hundreds of nanoscale layers of the substance on it. The layers have a propensity to agglomerate, namely, to sinter. The interlayer spacing must be higher to extend the materials’ surface area.
For this purpose, the researchers modified rGO with organic molecules, which resulted in the interlayer spacing increase. Insignificant differences in interlayer spacing allowed increasing energy capacity of the material by 1.7 times. That is, 1 g of the new material can store 1.7 times more energy in comparison with a pristine reduced graphene oxide.
The reaction went ahead with the development of active arynes from iodonium salts. These have an intriguing property to form a single layer of new organic groups on surfaces of the material. Scientists from TPU have been developing the chemistry of iodonium salts for several years.
"The modification reaction proceeds under mild conditions by simply mixing the solution of iodonium salt with reduced graphene oxide. If we compare it with other methods of reduced graphene oxide functionalization, we have achieved the highest indicators of material energy capacity increase", said Elizaveta Sviridova, Study Author and Junior Research Fellow, Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University