Nanostructured polycrystalline Ni3S2 as electrode material for lithium ion batteries

Abstract

We report the facile synthesis of nanostructured polycrystalline nickel sulphide (NP-Ni₃S₂) on Ni foil at 750 and 800 °C by employing powder vapor transport technique. X-ray diffraction patterns(XRD) confirms the formation of polycrystalline Ni₃S₂ phase with rhombohedral structure. Raman spectroscopy and x-ray photo-electron spectroscopy (XPS)further confirms the formation of Ni₃S₂ phase. Scanning electron microscopy (SEM)reveals the formation of flower shaped nanostructures of NP-Ni₃S₂ material. As an electrode material of Li⁺ batteries, the initial discharge capacities for NP-Ni₃S₂ materials deposited at 750 and 800 °C are found to be∼2649 mAh g⁻¹ and∼1347 mAh g⁻¹, respectively with initial capacity loss of∼1067 mAh g⁻¹ and∼363 mAh g⁻¹ after first cycle and capacities of∼931 mAh g⁻¹ and∼818 mAh g⁻¹ after 30 cycles for a current density of 60 mA g⁻¹. An excellent capacity retention for NP-Ni₃S₂ material synthesized at 800 °C is due to its larger surface area and shorter diffusion length for mass and charge transport brought about by the flower-like porous nanostructures showing that the NP-Ni₃S₂ material synthesized at higher temperatures is more suitable as electrode material for Li⁺ batteries.