Mg0.6Ni0.4O hollow nanofibers prepared by electrospinning as additive for improving electrochemical performance of lithium–sulfur batteries

• Mg0.6Ni0.4O hollow nanofibers was first prepared via an electrospinning technique.
• Sulfur/Mg0.6Ni0.4O hollow nanofibers composite cathode showed improved performance of Li–S batteries.
• Mg0.6Ni0.4O had a function of absorption of polysulfides and the catalytic activity towards the Li/S redox reaction.

Mg0.6Ni0.4O hollow nanofibers were prepared by electrospinning technique and subsequent thermal treatment. The as-prepared Mg0.6Ni0.4O hollow nanofibers were used as an additive to prepare sulfur/Mg0.6Ni0.4O composite cathodes. Their crystalline phase and morphologies were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The SEM observation revealed that the sulfur morphology was changed by the Mg0.6Ni0.4O addition, from smooth to rough agglomerated particles. The initial discharge profiles and cyclic voltammetry tests demonstrated the hollow nanofibers of Mg0.6Ni0.4O can not only contribute to reducing the dissolution of polysulfides into electrolytes, but also improve the electrochemical reaction kinetics during charge–discharge process. In addition, the hollow nanofibers of Mg0.6Ni0.4O ensure short diffusion distance for Li+ on interaction in charge–discharge cycles. The effect of the Mg0.6Ni0.4O hollow nanofibers heat treatment temperature on the S/Mg0.6Ni0.4O cycling performance was also investigated. As a result, the cathode with Mg0.6Ni0.4O hollow nanofibers calcined at 700 °C exhibited 910 mAh g−1 of initial capacity and keeping the remaining capacity of 554 mAh g−1 over 20 cycles.