Enhancement of the Supercapacitive Performance of Cobalt-tin-cyanate Layered Structures through Conversion from 2D Materials to 1D Nanofibers

Abstract

Rational design of the micro-nanomorphology is highly desired for metal hydroxides to achieve overall high-performance electrodes for supercapacitor and energy storage applications. Here, in the current study, we have succeeded in controlling the morphology of Sn/Co nanolayered structures to obtain plate and nanofibrous morphologies. Additionally, the plate nanostructures could be transformed to obtain plate-nanofibrous morphologies. In this trend, dual anions such as cyanate and nitrate are applied to intercalate among the nanolayers of cobalt-tin and act as building blocks or pillars, producing a series of nanolayered structures. By repulsion forces among the intercalated anions, the nanolayers of Sn/Co are curled and converted to nanofibers. This conversion was confirmed by scanning electron microscopy. In addition, the intercalation reactions and nanolayered structures were indicated by X-ray diffraction, thermal analyses and Fourier-transform infrared spectroscopy. The electrochemical supercapacitive behavior of the different nanostructures of Sn/Co HDS and Sn/Co LDH, such as plate, Plate-nanofiber and nanofibrous morphology has been investigated in three assembly electrode system. The results suggested that the nanofiber morphology of Sn/Co LDH exhibited better specific capacitance performance than the other two morphologies. The enhanced specific capacitance (658 Fg−1) and excellent cyclic stability (89%) of the nanofibers of the Sn/Co LDH could be attributed to the synergistic effects between the electric double layer capacitive character of the tin and the pseudocapacitance nature of the cobalt.