Cobalt-iron oxide nanotubes decorated with polyaniline as advanced cathode hosts for Li-S batteries

Lithium-sulfur (Li-S) batteries are generally considered as potential candidates for sustainable energy storage systems owing to low cost and high theoretical energy storage capability. However, the actual implementation of sulfur cathode in Li-S batteries is seriously hampered by the undesirable shuttle effect of lithium polysulfides (LiPS), inferior electroconductibility of S/Li₂S and huge volume change during lithiation/delithiation process. Herein, the CoFe₂O₄ nanotubes decorated with polyaniline (PANI) are rationally designed and fabricated as efficient sulfur hosts to handle these challenges. Specifically, both CoFe₂O₄ and PANI components possess strong chemical affinity to the soluble intermediate LiPS. Meanwhile, from the perspective of structural superiority, the internal void space of nanotubes can effectively accommodate active sulfur particles and tolerate the large volume change upon cycling. Besides, the conductive polymer of PANI can greatly improve the cathode conductivity and facilitate the electron transfer for active materials. More importantly, the S/CoFe₂O₄@PANI electrode achieves excellent cycling performance with superior initial capacity of 864.1 mAh g⁻¹ and good reversible capacity retention with 582.6 mAh g⁻¹ even after 500 cycles at 2 C rate.