Abstract
Lithium-sulfur (Li-S) batteries have attracted extensive attention as a promising next-generation electrochemical energy storage technology, owing to their high energy density and low material cost. However, issues such as severe polarization and poor cycle stability caused by shuttle effect and slow sulfur redox kinetics limit their practical applications. Here, Co 3 Fe 7 alloy embedded into nitrogen-doped hollow carbon sphere composite (CoFe/NHCS) was synthesized as an electrocatalyst for Li-S batteries. The Co 3 Fe 7 alloy demonstrates a strong chemisorption and superior electrocatalytic conversion towards polysulfides, while the nitrogen-doped carbon hollow spheres promote Li + /electron transfer and physically suppress polysulfides shuttling. Their synergistic effect therefore could both accelerate the polysulfides redox conversion and inhibit the polysulfides loss. As a consequence, the Li-S batteries assembled with CoFe/NHCS-modified separators exhibit a superior rate capacity (1029 mAh/g at 2 C) and excellent cycling stability (644 mAh/g at 1 C after 500 cycles). Furthermore, even at a high sulfur loading of 6.7 mg/cm 2 , a high areal capacity of 5.58 mAh/g is achieved, which is retained at 4.45 mAh/cm 2 after 100 cycles. In addition, the CoFe/NHCS possesses an excellent stability in both physical structures and chemical properties over extended cycles, demonstrating its great potential for high-performance and long-cycle-life Li-S batteries. The Co 3 Fe 7 alloy embedded into nitrogen-doped hollow carbon sphere composite exhibits an excellent cycling performance with a high sulfur loading for lithium-sulfur batteries. • Co 3 Fe 7 alloy embedded into nitrogen-doped hollow carbon sphere (CoFe/NHCS) was synthesized for Li-S batteries. • CoFe/NHCS demonstrates an improved adsorptive and electrolytic effect towards polysulfides. • CoFe/NHCS enables Li-S batteries with an excellent rate performance and superior cycling stability. • With a high sulfur loading of 6.7 mg/cm 2 , a high areal capacity of 4.45 mAh/cm 2 is retained after 100 cycles. • CoFe/NHCS possesses an excellent stability in both physical structures and chemical properties over extended cycles.
Published Version
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