Metal oxide heterostructure decorated carbon nanofiber as a novel redox catalyst for high performance Lithium-Sulfur batteries

Abstract Lithium-sulfur batteries (LSBs) are the promising next-generation energy storage devices; however, the uncontrolled shuttle effect and sluggish redox kinetics severely hinder their commercial success. To solve these barriers, herein, a heterostructure constructed from CoFe2O4 and SnO2 decorated over the carbon nanofiber framework (CoFe@SnCNF) is reported as a sulfur redox catalyst in the cathode of LSB. A synergism between the multiple adsorptive and catalytic sites of the heterostructure enables an efficient lithium polysulfide (LiPS) entrapment and expedites their conversion, meanwhile the carbon nanofiber framework provides a long-range electrical conduction. Based on these merits, the CoFe@SnCNF integrated sulfur cathode with an areal sulfur loading of ~ 2.2 mg cm−2 retained 71.1 % of initial capacity after 100 cycles at 0.2 C, and showed excellent cyclability with a capacity fading rate of only 0.11 % over 200 cycles at 0.5 C. Even under a raised sulfur loading of 5.3 mg cm−2, the cathode still showed an impressive performance with an initial capacity of 442.3 mAh g−1 that retained 78.1 % after 80 cycles. The findings of this work shed light on the feasibility for further development of novel heterostructure by synergistically coupling various polysulfide adsorbing and catalyzing materials.