Porous N-doped carbon nanofibers assembled with nickel ferrite nanoparticles as efficient chemical anchors and polysulfide conversion catalyst for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are deemed to have great prospects in the next generation advanced energy storage systems and have been considered in recent years. However, the majority of substrates with both high electronic conductivity and full coverage of adsorption-catalysis synergy are difficult to achieve. Herein, nitrogen functionalized porous carbon nanofibers assembled with nickel ferrite nanoparticles (NFO/NCFs) are successfully prepared by electrospinning combined with hydrothermal treatment, which were applied to current collector containing Li₂S₆ catholyte and binder-free for Li-S batteries. With its abundant active sites, the NFO/NCFs have a vital role in the adsorption and catalysis of the polysulfides, which further accelerate the redox kinetics. Consequently, Li₂S₆ catholyte impregnated NFO/NCFs electrode (sulfur loading: 5.09 mg cm^-2) exhibits the first discharge capacity of 997 mAh g^-1 and maintains at 637 mAh g^-1 after 350 cycles at 0.2C, which is superior cycling performance than NCFs. Even at 10.2 mg cm^-2 sulfur loading, the composite electrode shows a high area capacity of 8.35 mAh cm^-2 at 0.1C and retains 6.01 mAh cm^-2 after 150 cycles. The results suggest the multifunction NFO/NCFs that anchor effectively and catalysis are beneficial to realize the goal of the large-scale application for Li-S batteries.