Lithium–sulfur batteries, as one of promising next‐generation energy storage devices, hold great potential to meet the demands of electric vehicles and grids due to their high specific energy. However, the sluggish kinetics and the inevitable “shuttle effect” severely limit the practical application of this technology. Recently, design of composite cathode with effective catalysts has been reported as an essential way to overcome these issues. In this work, oxygen‐deficient ferric oxide (Fe2O3−x), prepared by lithiothermic reduction, is used as a low‐cost and effective cathodic catalyst. By introducing a small amount of Fe2O3−x into the cathode, the battery can deliver a high capacity of 512 mAh g−1 over 500 cycles at 4 C, with a capacity fade rate of 0.049% per cycle. In addition, a self‐supporting porous S@KB/Fe2O3−x cathode with a high sulfur loading of 12.73 mg cm−2 is prepared by freeze‐drying, which can achieve a high areal capacity of 12.24 mAh cm−2 at 0.05 C. Both the calculative and experimental results demonstrate that the Fe2O3−x has a strong adsorption toward soluble polysulfides and can accelerate their subsequent conversion to insoluble products. As a result, this work provides a low‐cost and effective catalyst candidate for the practical application of lithium–sulfur batteries.

Lithium−sulfur (Li−S) batteries have received intense interest as next-generation electrochemical energy storage systems because of their high specific energy and natural abundance potential. However, its practical reality is seriously limited by the safety concerns from heterogeneous lithium deposition and the so-called "shuttle effect". Herein, this work reports a novel gel−polymer−inorganic separator specifically for the lithium−sulfur battery, which could enable homogeneous lithium deposition and inhibit the diffusion of polysulfides, simultaneously. The composite separator exhibits a superior electrochemical performance up to 500 cycles at 0.5 C with a capacity retention of 718.2 mA h g −1 . It is worth noting that the corresponding fade rate for 1000 cycles was 0.04%/cycle even tested at 2 C. This outstanding cycling stability can be attributed to the strong anchoring effect of polar carboxymethylcellulose sodium to polysulfides, which is confirmed by the permeation experiments and X-ray photoelectron spectroscopy analyses. Besides, the Al 2 O 3 coating layer on the anode side could achieve relatively uniform lithium deposition and inhibit the growth of dendrite to some extent. As a result, this study may provide a novel strategy for the effective design of separators toward the practical reality of the high-performance lithium−sulfur battery.

The development of a high specific energy lithium–sulfur battery is heavily hindered by the so-called “shuttle effect”. Nevertheless, as an effective strategy, most modified separators cannot block and reuse polysulfides simultaneously. Here, a unique and versatile film fabricated by nitrogen and phosphorus co-doped carbon nanofibers uniformly anchored with TiC nanoparticles is incorporated between the separator and cathode of the lithium–sulfur battery. The battery armed with this functional film exhibits a high capacity of 737.1 mA h g–1 at 5 C with a slow capacity-fading rate of 0.06%/cycle over 500 cycles. Even when augmenting the sulfur loading to 17.1 mg cm–2, it can achieve a capacity of 837.3 mA h g–1 with a retention of ∼80% after 50 cycles. The TiC nanoparticles as well as heteroatom doping in the porous carbon nanofiber exhibit strong physiochemical adsorption and catalytic effect, which is proven by experiments and theoretical calculations. Thus, the diffusion of polysulfides can be effectively inhibited. Meanwhile, heteroatom doping can further enhance the conductivity and reaction activity of this film. Hence, the adsorbed polysulfides could be revived and renewed during the subsequent cycling process, which is accurately observed and confirmed by experiments for the first time.