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Li−Air Rechargeable Battery Based on Metal-free Graphene Nanosheet Catalysts

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journal contribution
posted on 26.04.2011, 00:00 by Eunjoo Yoo, Haoshen Zhou
Metal-free graphene nanosheets (GNSs) were examined for use as air electrodes in a Li−air battery with a hybrid electrolyte. At 0.5 mA cm−1, the GNSs showed a high discharge voltage that was near that of the 20 wt % Pt/carbon black. This was ascribed to the presence of sp3 bonding associated with edge and defect sites in GNSs. Moreover, heat-treated GNSs not only provided a similar catalytic activity in reducing oxygen in the air, but also showed a much more-stable cycling performance than GNSs when used in a rechargeable Li-air battery. This improvement resulted from removal of adsorbed functional groups and from crystallization of the GNS surface into a graphitic structure on heat treatment.