Synthesis and characterization of electrospun molybdenum dioxide-carbon nanofibers as sulfur matrix additives for rechargeable lithium-sulfur battery applications

One-dimensional molybdenum dioxide-carbon nanofibers (MoO₂-CNFs) were prepared using an electrospinning technique followed by calcination, using sol-gel precursors and polyacrylonitrile (PAN) as a processing aid. The resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Brunauer-Emmet-Teller (BET) surface area measurements, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MoO₂-CNFs with an average diameter of 425-575 nm obtained after heat treatment were used as a matrix to prepare sulfur/MoO₂-CNF cathodes for lithium-sulfur (Li-S) batteries. The polysulfide adsorption and electrochemical performance tests demonstrated that MoO₂-CNFs did not only act as polysulfide reservoirs to alleviate the shuttle effect, but also improve the electrochemical reaction kinetics during the charge-discharge processes. The effect of MoO₂-CNF heat treatment on the cycle performance of sulfur/MoO₂-CNFs electrodes was examined, and the data showed that MoO₂-CNFs calcined at 850 °C delivered optimal performance with an initial capacity of 1095 mAh g^-1 and 860 mAh g^-1 after 50 cycles. The results demonstrated that sulfur/MoO₂-CNF composites display a remarkably high lithium-ion diffusion coefficient, low interfacial resistance and much better electrochemical performance than pristine sulfur cathodes.