SnO2/graphite nanosheet composite electrodes and their application in supercapacitors

Abstract

Electrochemical exfoliation of graphite rods under the action of an electric field force led to the formation of two-dimensional (2D) graphite nanosheet arrays (GNSAs) perpendicular to the surface of the graphite substrate and parallel to each other in arrangement. Subsequently, SnO2/graphite nanosheet array (SnO2/GNSA) composite electrodes were prepared by the cathodic reduction electrodeposition method. The morphology, composition, and microstructure of the samples were characterized using field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy, respectively. Electrochemical measurements showed that the composite electrodes achieved specific capacitance values as high as 4105 F·m-2 in the potential window up to 1.4 V with a scan rate of 5 mV·s-1 in 0.5 mol·L-1 LiNO3 solution. Asymmetric supercapacitor fabricated with the as-prepared SnO2/GNSAs exhibited excellent capacitive performance with energy density of 0.41 Wh·m-2 in the potential window up to 1.8 V and retention of 81% after 5000 cycles.