Enhancement of the electrochemical performance of free-standing graphene electrodes with manganese dioxide and ruthenium nanocatalysts for lithium-oxygen batteries

Hybrid ternary Graphene/Ruthenium/alpha-MnO2 (rGO/Ru/alpha-MnO2) flexible nanocomposite cathodes were fabricated via controlling both reduction and vacuum filtration processes without using a binder and conductive carbon additives for flexible Li-air battery system. To compare the electrochemical performance of the Graphene/Ruthenium/alpha-MnO2 cathodes, bare rGO and rGO/Ru free-standing cathodes were also manufactured. rGO cathodes with well-dispersed alpha-MnO2 nanowires and ruthenium nanoparticles were successfully synthesized and shown to dramatically increase (decrease) oxygen reduction (evolution) reactions. The enhancement on the electrochemical performance of the synthesized cathodes was attributed not only to catalysis effect of rutheniumand alpha-MnO2 but also well-stacked morphology of the nanocomposite architecture which enables increased oxygen flow between the layers and, hence boosted reaction kinetics.