Nitrogen and Sulfur Doped Porous Carbon Sheet with Trace Amount of Iron as Efficient Polysulfide Conversion Catalyst for High Loading Lithium‐Sulfur Batteries

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The major challenges in enhancing the cycle life of lithium‐sulfur (Li−S) batteries are polysulfide (PS) shuttling and sluggish reaction kinetics (S to Li 2 S, Li 2 S to S). To alleviate the above issues, the use of heteroatom‐doped carbon as a cathode host matrix is a low‐cost and efficient approach, as it works as a dual‐functional framework for PS anchoring as well as an electrocatalyst for faster redox kinetics. Here, the dual role of heteroatom‐doped carbon sheets (CS) in the chemisorption of Li 2 S 6 and catalysis of its faster conversion to Li 2 S is established. To substantiate the catalytic effect, composite cathodes were prepared by encapsulating sulfur in CS which is further blended with carbon nanotubes (CNTs) to form a free‐standing cathode. The electrochemical performances of the three cathodes (S@Fe−N‐CS‐CNT, S@Fe−S‐CS‐CNT, and S@Fe‐NS‐CS‐CNT) were evaluated by constructing Li−S cells. The S@Fe‐NS‐CS‐CNT delivers a high initial discharge capacity of 1017 mAh g −1 at 0.5 C rate and sustains a capacity of 751 mAh g −1 after 260 cycles with a capacity retention of 73.8 %. Even at a high S loading (12 mg cm −2 ), it delivers an initial discharge capacity of 892 mAh g −1 and retained 575 mAh g −1 after 200 cycles.