Cobalt Sulfide Confined in N-Doped Porous Branched Carbon Nanotubes for Lithium-Ion Batteries

摘要

Lithium-ion batteries (LIBs) are considered new gen-eration of large-scale energy-storage devices. However, LIBs suffer from a lack of desirable anode materials with excellent specific capac-ity and cycling stability. In this work, we design a novel hierarchi-cal structure constructed by encapsulating cobalt sulfide nanowires within nitrogen-doped porous branched carbon nanotubes (NBNTs) for LIBs. The unique hierarchical Co9S8@NBNT electrode displayed a reversible specific capacity of 1310 mAh g-1 at a current density of 0.1 A g-1, and was able to maintain a stable reversible discharge capac-ity of 1109 mAh g-1 at a current density of 0.5 A g-1 with coulombic efficiency reaching almost 100％ for 200 cycles. The excellent rate and cycling capabilities can be ascribed to the hierarchical porosity of the one-dimensional Co9S8@NBNT internetworks, the incorporation of nitrogen doping, and the carbon nanotube confinement of the active cobalt sulfide nanowires offering a proximate electron pathway for the isolated nanoparticles and shielding of the cobalt sulfide nanowires from pulverization over long cycling periods.