Hollow SnO2 microspheres and their carbon-coated composites for supercapacitors

In the presence of sulfonated polystyrene (sPS) template, sPS@SnO2 core shell particles formed via the interaction between the functional group of -SO3H on the template surface and ions of Sn2+ from the precursor of SnSO4 which were in ethanol-aqueous medium. After high-temperature calcination treatment for removal of sPS, the sPS@SnO2 changed into SnO2 hollow spheres. With the further carbonization of the sPS@SnO2@glucose composite microspheres, SnO2@C composite hollow spheres were fabricated. Using SEM, TEM, and N2 adsorption - desorption technology, the structure, specific surface area, and the core-shell structure formation mechanism were determined. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) properties of SnO2 hollow spheres and SnO2@C composites were investigated, respectively, in the foam nickel electrode under alkaline condition. The specific capacitance of SnO2@C composite hollow spheres could reach 25.8 F g−1 in 1 mol L−1 KOH aqueous solution and showed excellent charge-discharge behavior.