Graphene Nanosheets Based Cathodes for Lithium-Oxygen Batteries

Lithium-oxygen batteries have attracted considerable attention as a promising energy storage system. Although these batteries have many advantages, they face several critical challenges. In this work, we report the use of graphene nanosheets (GNSs), nitrogen-doped graphene nanosheets (N-GNSs), exfoliated nitrogen-doped graphene nanosheets (Ex-N-GNSs), and a blend of Ex-N-GNSs with nitrogen-doped carbon (Hybrid 1) as oxygen cathodes. These cathode materials were characterized by the Brunauer-Emmett-Teller (BET) surface area analysis, cyclic voltammetry (CV) and scanning electron microscopy (SEM). In order to mitigate safety issues, all solid-state cells were designed and fabricated using lithium aluminum germanium phosphate (LAGP) as ceramic electrolyte. The cathodes prepared from GNSs, N-GNSs, Ex-N-GNSs, and Hybrid 1 exhibit remarkable enhancement in cell capacity in comparison to conventional carbon cathodes. This superior cell performance is ascribed to beneficial properties arising from GNSs and nitrogen doped carbon. GNSs have unique morphology, higher oxygen reduction activity, whereas nitrogen-doped carbon has higher surface area.