Lithium-ion battery fiber constructed by diverse-dimensional carbon nanomaterials

Graphene fibers are supposed to be ideal electrodes for fiber-shaped lithium-ion batteries. However, a big challenge remains in how to bring effectively the remarkable properties of graphene onto macroscopic graphene fibers. Here, the assembly of 2D reduced graphene oxides is coordinated by 1D carbon nanotubes resulting in a novel composite fiber. A brick–bridge network with high alignment, optimal porosity and low junction contact resistance is formed, in which reduced graphene oxides serve as the brick and carbon nanotubes as the bridge. Consequently, the composite fiber provides a fast, robust and massive transport network both for electrons and Li-ions. A large specific capacity of 522 mAh g−1 at 50 mA g−1 is achieved. Moreover, high retentions of 143% and 72% are obtained after 800 cycles at 500 mA g−1 and when current density is increased from 50 to 500 mA g−1, respectively.