Synthesis of Na_2(Ni, Fe)(SO_4)_2 Cathode Materials from Nickel Sulfide Concentrate by Combined Pyro-and Hydrometallurgical Processes

摘要

In this study, a compact process was introduced to prepare the sulfate-based polyanionic nano cathode material Na_2(Ni, Fe)(SO_4)_2 from nickel sulfide concentrate. The Na_2(Ni, Fe)(SO_4)_2 was synthesized with a four-step process, including sulfate roasting, leaching-purification, co-precipitation, and annealing processes. The crystalline phase identification and microstructure characterization of the final product was performed by X-ray diffraction (XRD) and Scanning electronic microscopy (SEM), respectively. The XRD result shows that the obtained product which was composed of eldfellite compounds Na_2(Ni, Fe)(SO_4)_2 and sodium-rich phase Na_6Fe(SO_4)_4. The SEM reveals that the synthesized material was with a microstructure of nanopore, which might be owing to the nanocarbon powder as nucleation particles can promote the formation of nanometer pore. The nano-material Na_2(Ni, Fe)(SO_4)_2, expected to be a promising candidate in energy storage applications as sodium-ion battery, has been synthesized from nickel sulfide concentrate.