Nitrogen-doped Graphene Hollow Microspheres as an Efficient Electrode Material for Lithium Ion Batteries

Nitrogen-doped graphene hollow microspheres (NGHSs), synthesized through a template sacrificing method, have been employed as the anode material for lithium ion batteries (LIBs). The electrochemical results show that the NGHSs can exhibit an initial discharge capacity of 2716.4mAhg (1), which is significantly higher than the theoretical discharge capacity of graphite (372.0mAhg (1)). Further analysis shows that the NGHSs can exhibit significantly high rate capacity, good reversibility, and excellent cycling stability, which clearly demonstrate the potential uses of the NGHSs as the anode material to boost both energy and power densities of LIBs. Their excellent electrochemical performance could be attributed to their specific microspherical hollow structure which consists of nitrogen-doped graphene. The nitrogen doping can greatly increase the reactivity and electrical conductivity of graphene-based carbonaceous materials and create more sites that are active for the Li+ ion adsorption, while the hollow microspherical structure allows a ready access of the electrolyte to the electrode surface, easier electron and ion transfer, and faster diffusion of electrolytes in and out of the electrode. In addition, the nitrogen-doped graphene and the specific hollow microspherical structure also make the NGHSs highly stable and can buffer against the local volume change during the Li+ detercalation and intercalation processes, which give the corresponding LIBs with better cycling stability. (C) 2014 Elsevier Ltd. All rights reserved.