Needle-like NiCo2O4 Coated on Graphene Foam as a Flexible Cathode for Lithium-Oxygen Batteries

The electrochemical performance of non-aqueous lithium-oxygen batteries depends largely on the catalytic activity of the cathode, among which the architecture design plays an important role. In this paper, we present a novel free-standing, flexible cathode with needle-like NiCo2O4 coated on a three-dimensional graphene framework. The hierarchical structure exhibits a macropore nest of graphene foam along with mesopore decoration of NiCo2O4 nanorods, which can provide fast diffusion or adsorption for the reactants and abundant active site for the oxygen reduction reaction and oxygen evolution reaction. With the novel cathode, the battery delivers a capacity about 5000 mAhg(-1) at a current density of 400 mAg(-1), and can cycle stably at least 80 times without obvious degradation at the capacity limitation of 1000 mAhg(-1). This flexible cathode shows potential application in foldable electronic devices.