CoSe2 nanoparticles-decorated carbon nanofibers as a hierarchical self-supported sulfur host for high-energy lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries have gained widespread attention owing to their high theoretical energy density and low cost. However, the commercial application of these batteries is hindered by the severe shuttle effect and slow redox reaction kinetics of polysulfides. In this study, a hierarchically porous membrane consisting of CoSe2 nanoparticle-decorated carbon nanofibers containing carbon nanotubes (CoSe2@CNF/CNT) is constructed as a self-supported sulfur host for Li-S batteries. The hierarchical conductive network of CNFs/CNTs with N-doped porous carbon facilitates electron/ion transport and provides sufficient space to mitigate the volume expansion of lithium polysulfides (LiPSs). Moreover, the modified CoSe2 nanoparticles serve as both chemical trappers and electrocatalysts, chemically anchoring LiPSs and accelerating the redox kinetics to inhibit the shuttle effect. As a result, an initial specific discharge capacity of 1098.8 mA h g−1 is achieved at 1 C. Importantly, the cathode exhibits superior cycling stability with a capacity decay rate as low as 0.06% over 500 cycles. This work offers a feasible approach to designing multi-functional sulfur hosts for high-energy-density Li-S batteries.