A freestanding MoO₂-decorated carbon nanofibers interlayer for rechargeable lithium sulfur battery

Lithium-sulfur (Li-S) battery based on sulfur cathodes is of great interest because of high capacity and abundant sulfur source. But the shuttling effect of polysulfides caused by charge-discharge process results in low sulfur utilization and poor reversibility. Here, we demonstrate a good approach to improve the utility of sulfur and cycle life by synthesizing carbon nanofibers decorated with MoO2 nanoparticles (MoO2-CNFs membrane), which plays a role of multiinterlayer inserting between the separator and the cathode for Li-S battery. The S/MoO2-CNFs/Li battery showed a discharge capacity of 6.93 mAh cm−2 (1366 mAh g−1) in the first cycle at a current density of 0.42 mA cm−2 and 1006 mAh g−1 over 150 cycles. Moreover, even at the highest current density (8.4 mA cm−2), the battery achieved 865 mAh g−1. The stable electrochemical behaviors of the battery has achieved because of the mesoporous and interconnecting structure of MoO2-CNFs, proving high effect for ion transfer and electron conductive. Furthermore, this MoO2-CNFs interlayer could trap the polysulfides through strong polar surface interaction and increases the utilization of sulfur by confining the redox reaction to the cathode.