Papers by Keyword: Ni Sulfides

Abstract: The nickel sulfide (Ni3S2) thin film could be prepared from Ni/S double layer, which was deposited on nickel foil using evaporation and sputtering. The nickel sulfide electrode was discharged and charged between 0.6V and 2.6V versus Li/Li+ at room temperature. The nickel sulfide film had the first discharge capacity of 270mAh/g, and two plateaus at 1.3V and 1.8V.

Abstract: The microstructure of Ni sulfides prepared by thermal sulfidation of pure Ni and their dependence of fabrication parameters were investigated by means of scanning electron microscopy and X-ray diffractions. Sulfidation was made by isothermally annealing Ni with the sulfur in vacuum sealed glass ampoules at 673 K for 120 – 600s under the sulfur pressure of 100 and 220 kPa. The sulfide layers formed in the early stage were found to consist of spherical particles smaller than 0.5um, which were grown and agglomerated with increasing annealing temperature. Thickness of sulfides developed on Ni substrate was found to increase with increasing annealing time and sulfur pressure. It was also found that compositions of dominant Ni sulfides changed with varying annealing time. At the initial stage, only Ni3S2 sulfide was formed on pure Ni, which was tightly bonded to Ni substrate. On increasing annealing time, NiS sulfide was formed. On further increasing annealing time, NiS1.97 sulfide was formed, which always coexisted with NiS sulfide. A mechanism for sulfidation of Ni is proposed as follows: 3Ni + 2S
Ni3S2, Ni3S2 +S
NiS, NiS + S
NiS1.97

Abstract: Ti and Ni sulfides were formed on the surface of Ti-Ni alloys by isothermal annealing at various sulfur pressures, and then microstructures of the surface sulfide layers were investigated by means of scanning electron microscopy and X-ray diffractions. Morphology of sulfurized surface changed from granular shape to porous shape at the sulfur pressure of 80 kPa, which is related to the change in sulfide from NiS1.97 to NiS. Two-layered sulfide was observed in which the inner layer was mainly Ti8.2S11 , and the outer layer was a mixture of NiS1.97 and NiS. The discharge curve of the Ti and Ni sulfides cathode formed on the Ti-Ni current collector at the first cycle showed a plateau voltage of 1.6 V, and the discharge capacity was found to be about 530 mAh/g-NiS1.97.