Cobalt nanofibers @ Ni3S2 nanosheets (Co@Ni3S2) composites with high surface area (241.67 m2/g) were successfully synthesized via a chemical conversion route. The special nanostructure afforded sufficient space for the volume change, ensured efficient electrolyte penetration, increased contact area between electrolyte and active material during discharge–charge process. Moreover, the existence of the cobalt nanofibers with high conductivity provided a possibility for the rapid transportation of the electrons and lithium ions. The composite electrodes presented a reversible discharge capacity of 531 mAh/g with a good cyclic stability. This research perhaps inspired the designing of high performance electrode materials with a novel structure for high performance energy storage devices.