Positive Influence of Oxalate and Cyanate on the Supercapacitance Performance of V/Co 2D-Nanolayered Structures

Two-dimensional (2D) nanolayered and nanohybrid structures, which are composed of different species of organic anions and multi-valence inorganic cations, are considered favorable in the field of energy storage for use as supercapacitors. In this study, host–guest interactions were used to build a series of these nanohybrids. The host was the layered double hydroxides of vanadium–cobalt (V/Co) nanolayers with different molar ratios. Cyanate was used as a guest to design a V/Co supercapacitor with a 2D-nanolayered structure. In addition, oxalate was used as a new additive to improve the performance of the V/Co supercapacitor. X-ray diffraction, infrared spectroscopy, thermal analyses, and scanning electron microscopy confirmed the formation of the nanolayered structures of cyanate-V/Co. In the case of the oxalate-V/Co nanostructures, a new phase of cobalt oxalate was produced and combined with the nanolayered structure to build a 3D porous structure. A three-assembly electrode system was used to study the electrochemical supercapacitive behavior of the cyanate-V/Co and oxalate-V/Co nanolayered structures. The results indicated that the OXVC-20 electrode possessed the highest specific capacitance as compared to that of the OXVC-16 and CNOVC electrodes. An excellent stability performance of up to 91% after various charge–discharge cycles was detected for the optimum case. Because of the positive effect of oxalate on the supercapacitance performance of the V/Co supercapacitor, it is suggested as a new track for building active electrodes for high-performance supercapacitor applications.