3D porous nano/micro nickel sulfides with hierarchical structure: controlled synthesis, structure characterization and electrochemical properties

Abstract

A series of nickel sulfide nanocrystallines with hierarchical structures was successfully fabricated in situ on a nickel substrate. The nanocrystalline materials with three dimensional (3D) structures were synthesized via self-assembly under moderate conditions, with ethylenediamine and ethylene glycol as the mixed solvents. The structure and morphology of each nickel sulfide could be controlled by adjusting the polarity of the mixed solvents. With the reduced solvent polarity, the 3D flower-like nickel sulfide spheres were transformed into two-dimensional (2D) nanoflakes, then into one-dimensional (1D) prism-like microrods, and finally into 1D pearl-like nanochains. When the nickel sulfides were used as electrode materials in lithium-ion batteries, the obtained samples with different morphologies had different initial discharge capacities. The initial discharge capacity of the as-prepared nickel sulfides with 1D nanostructures reached approximately 550 mA h g⁻¹, which was higher than that of the samples with 2D and 3D structures. This study explores a novel method to control the synthesis of metal chalcogenides with specific morphologies.