CoFe2O4 nanoparticles loaded N-doped carbon nanofibers networks as electrocatalyst for enhancing redox kinetics in Li-S batteries

Highlights: • CFONC/Li₂S₆ as binder free electrode for Li-S battery with high sulfur loading. • CFONC as efficient electrocatalyst to facilitate the kinetics of redox reaction. • CFO accelerates homogeneous deposition of Li₂S on the surface of substrate. • CFONC inhibits the shuttle of polysulfides and thus protects the lithium anode. Lithium sulfur (Li-S) batteries have been paid more attention to meet the demand of high capacity energy storage. However, most substrates applied to electrodes, which have both high conductivity and full coverage of adsorption-catalysis synergies, are difficult to achieve. Herein, the combination of electrospinning and hydrothermal method is developed to fabricate the composite membrane of ferri-based spinel CoFe₂O₄ (CFO) loaded nitrogen doped carbon nanofibers (CFONC) applied to positive current collector with Li₂S₆ catholyte and binder-free of Li-S batteries. Benefiting from the improved catalytic performances in redox reaction of lithium polysulfides due to the abundant active sites which originate from CFO, the CFONC composite with S loading of 4.74 mg exhibits an initial specific discharge capacity of 1096 mAh g⁻¹ at 0.2 C and a high specific discharge capacity of 681 mAh g⁻¹ after 500 cycles with a capacity decay as small as 0.076% per cycle. Even with S loading of 7.11 mg, the cell of CFONC delivers a high initial capacity of 6.1 mAh and maintains 4.8 mAh after 300 cycles. The results show that the efficient chemical anchoring polysulfides and catalyzing redox reaction by multifunctional CFONC composites is a feasible strategy for the large-scale application of lithium sulfur batteries with high performance in the future.