Building three-dimensional carbon nanotubes-interwoven Ni3S2 micro-nanostructures for improved sodium storage performance

Abstract

A novel porous micro-nanostructure based on nickel disulfide (Ni3S2) nanoparticles interconnected with carbon nanotubes (CNTs) has been synthesized through a facile vulcanization with sulphur in the Ar + H2 (5%) atmosphere at 550 °C. The superior structural integrity of the Ni3S2/CNTs composites with abundant mesopores can be controlled by adjusting the amount of CNTs. The CNTs not only homogenously embed into every micro-nanostructure but also bridge between micro-nanostructures to form excellent integral conductive network. In the electrode, every Ni3S2/CNTs unit has a micro-nanostructure, resulting in fast transportation of ions and electrons. The experimental proofs reveal that the stable solid electrolyte interphase films on the outer surface of micro-nanostructures can assure the high columbic efficiencies and prevent the polysulfides shuttle effect, which plays an important role in the excellent cycling performance. The charge capacity retention of the Ni3S2/CNTs-10 electrode is up to 82.2% after 200 cycles at the current density of 0.5 A g−1. It shows a high initial coulombic efficiency (up to 83.2%) and stable voltage platforms at different current densities, suggesting that the Ni3S2/CNTs micro-nanostructure is a promising applicable anode candidate for sodium ion batteries.