Facile synthesis and electrochemical performances of hollow graphene spheres as anode material for lithium-ion batteries

The hollow graphene oxide spheres have been successfully fabricated from graphene oxide nanosheets utilizing a water-in-oil emulsion technique, which were prepared from natural flake graphite by oxidation and ultrasonic treatment. The hollow graphene oxide spheres were reduced to hollow graphene spheres at 500°C for 3 h under an atmosphere of Ar(95%)/H(2)(5%). The first reversible specific capacity of the hollow graphene spheres was as high as 903 mAh g(-1) at a current density of 50 mAh g(-1). Even at a high current density of 500 mAh g(-1), the reversible specific capacity remained at 502 mAh g(-1). After 60 cycles, the reversible capacity was still kept at 652 mAh g(-1) at the current density of 50 mAh g(-1). These results indicate that the prepared hollow graphene spheres possess excellent electrochemical performances for lithium storage. The high rate performance of hollow graphene spheres thanks to the hollow structure, thin and porous shells consisting of graphene sheets. PACS: 81.05.ue; 61.48.Gh; 72.80.Vp