Structural analysis and capacitive properties of carbon spheres prepared by hydrothermal carbonization

The structure and capacitive properties of carbon spheres synthesized by heat treatment after hydrothermal carbonization of glucose were investigated. X-ray diffraction, Raman spectroscopy, and 13C NMR spectroscopy measurements revealed that the spheres formed by polymerization of 5-(hydroxymethyl)-2-furaldehyde derived from glucose contained a small amount of microcrystalline graphite. N2 adsorption analysis showed that heat treatment was effective for carbonization and nanopore formation in the carbon spheres. The capacitive properties of the carbon spheres were improved by heat treatment because their specific surface area increased and internal resistance decreased. The capacitance of carbon spheres heat treated at 800 °C was 115 F/g, which was higher than that of commercial activated carbon (90 F/g).