Nitrogen-doped carbonaceous scaffold anchored with cobalt nanoparticles as sulfur host for efficient adsorption and catalytic conversion of polysulfides in lithium-sulfur batteries

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The effective inhibition of lithium polysulfides (LiPSs) and promotion of their conversion in the redox processes is indispensable to achieve the long cycle stability and excellent rate performance of lithium-sulfur (Li-S) batteries. Especially, the generally slow electrocatalytic sulfur redox kinetics and large interfacial Li2S nucleation energy barriers have hindered the widespread application of Li-S batteries. Herein, a robust three-dimensional sulfur carrier (denoted as Co-NCNT) is well-constructed using the potassium citrate derived porous carbon sheets as substrate and the catalytic growth nitrogen-doped porous carbon nanotubes as vertical scaffolds. Such a rationally designed structure guarantees efficient electron transfer pathways and ions diffusion channels. More importantly, it is conducive to the adsorption/catalytic conversion of intermediate lithium polysulfides and the nucleation of Li2S. Due to these merits, the S@Co-NCNT cathode achieves an initial discharge capacity up to 1072.7 mAh g−1 at 1.0 C, and it can retain a high capacity of 482.9 mAh g−1 with a capacity attenuation rate of only 0.045% per cycle after 1000 cycles. Upon a high sulfur loading of 5.87 mg cm−2, the S@Co-NCNT electrode can still reach an initial capacity of 739.5 mAh g−1 at 0.3 C. Particular emphasis is that our work broadens the way to prepare well-designed carbonaceous materials sulfur host for long-life Li-S batteries.