A high-capacity graphene nanosheet material with capacitive characteristics for the anode of lithium-ion batteries

Graphene nanosheets are prepared from H-2 thermal reduction of graphite oxide at 300 C. The graphite oxide interlayer has readily been expanded through chemical oxidation of meso-carbon micro-beads graphite raw material. After H-2 reduction, the carbon/oxygen ratio of graphene is increased from that of graphite oxide due to the removal of oxygen-containing functional groups as it is demonstrated from IR spectra. The d-spacing of resulting graphene nanosheets is increased to 0.37 nm, which facilitates lithium intercalation. Such synthesized graphene nanosheet material as anode of lithium-ion battery has exhibited high reversible discharge capacity of 1,540 mAh g(-1) at a current density of 50 mA g(-1), and the coulumbic efficiency was 97% over 50 cycles. The discharge curve of the anode material shows a continuously increased voltage profile, which is a characteristic of a capacitive material.