Free-standing nitrogen doped graphene/Co(OH)₂ composite films with superior catalytic activity for aprotic lithium-oxygen batteries

The recent boom in large-scale energy storage system promotes the development of lithium-oxygen batteries because of their high theoretical energy density. However, their applications are still limited by the sluggish kinetic, insoluble discharge product deposition and the undesired parasitic reaction. Herein, the free-standing nitrogen doped reduced graphene oxide/Co(OH)₂ (NRGO/Co(OH)₂) composite films were prepared by a facile hydrothermal method. The NRGO/Co(OH)₂ composite films display interconnected three-dimensional conductive network, which can not only promote the diffusion of O₂ and the transport of electrolyte ions, but also provide abundant storage space for discharge products. Moreover, the introduction of nitrogen-containing functional groups results in improved conductivity and electron adsorption ability, which can facilitate electron transport and enhance the surface catalytic activity. Combining with excellent catalytic performance, the lithium-oxygen batteries with NRGO/Co(OH)₂ composite film cathodes deliver low charge overpotential and excellent cycling performance.