Preparation and characterization of carbon nanospheres as anode materials in lithium-ion secondary batteries

Carbon nanospheres (CNSs) with a diameter of less than 100 nm, containing nitrogen-functional groups, and turbostratic structure were prepared by carbonizing polypyrrole nanospheres (PNSs), which were synthesized by polymerization of pyrrole under ultrasonic conditions in the presence of dual surfactants and catalyst. The materials were characterized by X-ray diffraction, thermogravimetric analysis, field-emission transmission electron microscope, field-emission scanning electron microscope, Raman spectroscope, nitrogen adsorption, and X-ray photoelectron spectroscope. In addition, the electrochemical properties of the CNSs as anode materials in lithium-ion batteries were evaluated. It was found that the use of ultrasonication is a simple and reproducible method for the synthesis of monodisperse PNSs. The CNSs displayed a higher specific capacity than the carbon spheres derived from sucrose and a higher rate capability than commercial mesophase carbon microbeads.