Synthesis of self-assembled cobalt sulphide coated carbon nanotube and its superior electrochemical performance as anodes for Li-ion batteries

In this work, cobalt sulphide/functionalised carbon nanotube (CoS2/fCNT) nanocomposites were synthesized via solvothermal method followed by annealing sulphidation. The nanocomposites were composed of fine nanoparticles (2-10 nm) coated along the surfaces of fCNT as well as nanoclusters (30-60 nm) formed by the nanoparticles which intertwined with the fCNT network. The as-synthesized CoS2/fCNT nanocomposites exhibited excellent electrochemical performance as an anode material in Lithium-ion batteries (LIBs), such as superior specific capacity, enhanced rate capability, outstanding cycling stability and near 100% Coulombic efficiency. CoS2/fCNT hybrid nanocomposite electrodes were able to deliver high reversible capacities of 783.4 mAh g(-1) and 337.8 mAh g(-1) at the current densities of 50 and 1000 mA g(-1), respectively. Furthermore, the electrode sustained an impressive capacity retention of 84.1% after unprecedented 1000 discharge-charge cycles at a high current density of 1000 mAh g(-1) The ultra-long cycle stability is much higher than all other reported cobalt sulphide anodes so far. The excellent electrochemical performance of CoS2/fCNT nanocomposite is attributed to the synergistic effects of CoS2 and fCNT. The outstanding stability of the CoS2/fCNT nanocomposites makes it a highly promising anode material to instead of the conventional graphite for future generation LIBs. (C) 2015 Elsevier Ltd. All rights reserved.