Fabrication of high-performance supercapacitors based on hollow SnO2 microspheres

Abstract

Hollow SnO2 microspheres are prepared from resorcinol–formaldehyde gel and different tin compound precursors, including stannous sulfate (SnSO4), stannous chloride dihydrate (SnCl2·2H2O), and stannic chloride pentahydrate (SnCl4·5H2O) via chemically induced self-assembly in hydrothermal environment. Morphological and structural characterizations of as-prepared hollow SnO2 microspheres are carried out using scanning electron microscopy, X-ray diffraction, and nitrogen adsorption–desorption method. Their electrochemical properties as the supercapacitor electrode materials for application are also investigated using cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurement in 1 M H2SO4 electrolyte. There are redox peaks in CV curves and a large number of Faradic plateaus in GCD curves. At different scan rates, all the obtained samples have excellent electrochemical properties. The hollow SnO2 microspheres obtained from SnSO4 and SnCl2·2H2O as precursors show relatively lower specific capacitances of 395 and 347 F g−1, respectively. However, the specific capacitance of SnO2 from SnCl4·5H2O is up to 663 F g−1. The high specific surface area and hollow structure of SnO2 microspheres are due to facilitating the rapid transport of electrolyte ions and improving the electrochemical performance. It is expected that hollow SnO2 microspheres are the promising redox supercapacitor materials.