Monolithic nitrogen-doped graphene frameworks as ultrahigh-rate anodes for lithium ion batteries†
Three-dimensional (3D) nanocarbon architectures have attracted great interest in materials science and nanotechnology. In this work, we report the synthesis of a 3D nitrogen-doped graphene nanoarchitecture by using catalytic carbonization of aromatic polyimide (PI) on magnesium oxide (MgO) nanowires. The produced porous graphene nanofibers are crosslinked into an integrated monolithic structure, thereby offering continuous electron conductivity and efficient charge transport. Moreover, nitrogen doping was achieved during the in situ carbonization, enhancing the electronic and interfacial properties of the porous graphene nanofibers. The obtained monolithic frameworks were directly used as binder-free electrodes for lithium batteries, and yield remarkable electrochemical performances, such as high reversible capacity, high rate capability, and superb cycling stability. The monolithic structures can be used as a material platform for the preparation of other functional composites, extending their applications beyond energy storage.