Enhanced Li-Storage of Ni 3 S 2 Nanowire Arrays with N-Doped Carbon Coating Synthesized by One-Step CVD Process and Investigated Via Ex Situ TEM.

In this work, a facile strategy for the construction of single crystalline Ni ₃ S ₂ nanowires coated with N-doped carbon shell (NC) forming Ni ₃ S ₂ @NC core/shell arrays by one-step chemical vapor deposition process is reported. In addition to the good electronic conductivity from the NC shell, the nanowire structure also ensures the accommodation of large volume expansion during cycling, leading to pre-eminent high-rate capacities (470 mAh g ^-1 at 0.05 A g ^-1 and 385 mAh g ^-1 at 2 A g ^-1 ) and outstanding cycling stability with a capacity retention of 91% after 100 cycles at 1 A g ^-1 . Furthermore, ex situ transmission electron microscopy combined with X-ray diffraction and Raman spectra are used to investigate the reaction mechanism of Ni ₃ S ₂ @NC during the charge/discharge process. The product after delithiation consists of Ni ₃ S ₂ and sulfur, suggesting that the capacity of the electrode comes from the conversion reaction of both Ni ₃ S ₂ and sulfur with Li ₂ S.
(© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)