Nanostructured polycrystalline Ni3S2 as electrode material for lithium ion batteries

Abstract

We report the facile synthesis of nanostructured polycrystalline nickel sulphide (NP-Ni _3 S _2 ) on Ni foil at 750 and 800 °C by employing powder vapor transport technique. X-ray diffraction patterns (XRD) confirms the formation of polycrystalline Ni _3 S _2 phase with rhombohedral structure. Raman spectroscopy and x-ray photo-electron spectroscopy (XPS) further confirms the formation of Ni _3 S _2 phase. Scanning electron microscopy (SEM) reveals the formation of flower shaped nanostructures of NP-Ni _3 S _2 material. As an electrode material of Li ^+ batteries, the initial discharge capacities for NP-Ni _3 S _2 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-Ni _3 S _2 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-Ni _3 S _2 material synthesized at higher temperatures is more suitable as electrode material for Li ^+ batteries.

Keywords

• powder vapor transport
• nanostructured nickel sulphide
• initially high-charging capacity
• high capacity retention
• Li+ batteries