Synergistic catalytic conversion and chemisorption of polysulfides from Fe/Fe3C/FeN0.0324 nanocubes modified separator for advanced Li-S batteries

[Display omitted] Lithium sulfur batteries (LSBs) have been considered as one of the most promising options for next generation high-performance batteries. However, the heavy shuttle effect and inferior redox conversion during the charge/discharge processes of the batteries have greatly hindered their further applications. In this study, to address these disadvantages of LSBs, Fe/Fe3C/FeN0.0324 heterostructured nanocubes were designed and prepared through high temperature carbonization process using Prussian blue precursor. Then the Fe/Fe3C/FeN0.0324 nanocubes were used to modify the commercial polypropylene (PP) separator, which can greatly catalyze the redox transformation of polysulfides and provide sufficient active sites for chemisorption. As result, the modified separator endowed LSBs with excellent rate capacity and cycle stability, delivering a high-capacity of 1025 mAh/g at 0.5 C with nearly 100% coulombic efficiency. It also displayed a superb cycling performance with a per-cycle capacity attenuation rate of 0.09% after 300 cycles. When the current density increased to 1 C with the S loading of 1.73 mg cm−2, Fe/Fe3C/FeN0.0324-PP separator presented a satisfactory capacity decay rate of 0.05% per cycle after 1000 cycles. Besides, it also presented outstanding electrochemical performance even at high sulfur loading of 4.5 mg cm−2. This work has provided a new avenue for the design of nanomaterials with synergistic effect of catalytic conversion and chemisorption of polysulfides for the promotion of high-performance Li-S batteries.