CoSe ₂anchored vertical graphene/macroporous carbon nanofibers used as multifunctional interlayers for high-performance lithium–sulfur batteries

Abstract

The rational design of VGMFs@CoSe ₂is a smart strategy to achieve high-performance Li–S batteries.

Abstract

The practical application of lithium–sulfur batteries is significantly limited by sluggish conversion kinetics and the shuttle effect. To overcome these intractable obstacles, we develop three-dimensional vertical graphene/macroporous carbon nanofibers decorated with CoSe ₂nanocatalysts (VGMFs@CoSe ₂) as the freestanding interlayer for high-performance Li–S batteries. By integrating the vertical graphene nanosheets and the continuously packed macroporous, the hierarchical fiber is endowed with high conductivity and large pore volume, which can significantly enhance electron transportation and effectively improve the storage capacity of sulfur species. Moreover, CoSe ₂anchored on the fiber plays an important role in accelerating conversion kinetics. Consequently, the VGMFs@CoSe ₂-based cells exhibit remarkable rate capability with a high specific capacity of 917.7 mA h g ⁻¹at 3C and good stability at 6C within 120 cycles. Even at high sulfur loading and low E/S ratio (8.5 mg cm ⁻², 7.4 μL mg), the battery still delivers a high areal capacity of 10.6 mA h cm ⁻²at the first cycle. After 500 cycles at 4C, the cell achieves a capacity retention of 569 mA h g ⁻¹with only a capacity decay rate of 0.078% per cycle. This study provides a novel carbon structure, which is useful not only for the application of Li–S batteries but also for other areas.