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

Lithium-ion batteries (LIBs) are considered new generation of large-scale energy-storage devices. However, LIBs suffer from a lack of desirable anode materials with excellent specific capacity and cycling stability. In this work, we design a novel hierarchical structure constructed by encapsulating cobalt sulfide nanowires within nitrogen-doped porous branched carbon nanotubes (NBNTs) for LIBs. The unique hierarchical Co(9)S(8)@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 capacity 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 Co(9)S(8)@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. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s40820-019-0259-z) contains supplementary material, which is available to authorized users.