Hierarchical Nanotubes Constructed by Co9S8/MoS2 Ultrathin Nanosheets Wrapped with Reduced Graphene Oxide for Advanced Lithium Storage

Nanostructured hybrid metal sulfides have attracted intensive attention due to their fascinating properties that are unattainable by the single-phased counterpart. Herein, we report an efficient approach to construct cobalt sulfide/molybdenum disulfide (Co9 S8 /MoS2 ) wrapped with reduced graphene oxide (rGO). The unique structures constructed by ultrathin nanosheets and synergetic effects benefitting from bimetallic sulfides provide improved lithium ions reaction kinetics, and they retain good structural integrity. Interestingly, the conductive rGO can facilitate electron transfer, increase the electronic conductivity and accommodate the strain during cycling. When evaluated as anode materials for lithium-ion batteries (LIBs), the resultant reduced graphene oxide-coated cobalt sulfide/molybdenum disulfide (Co9 S8 /MoS2 @rGO) nanotubes deliver high specific capacities of 1140, 948, 897, 852, 820, 798 and 784 mAh g-1 at the various discharging current densities of 0.2, 0.5, 1, 2, 3, 4 and 5 A g-1 , respectively. In addition, they can maintain an excellent cycle stability with a discharge capacity of 807 mAh g-1 at 0.2 A g-1 after 70 cycles, 787 mAh g-1 at 1 A g-1 after 180 cycles and 541 mAh g-1 at 2 A g-1 after 200 cycles. The proposed method may offer fundamental understanding for the rational design of other hybrid functional composites with high Li-storage properties.