Construction of Co@N-CNTs grown on N-MoxC nanosheets for separator modification to enhance adsorption and catalytic conversion of polysulfides in Li–S batteries

Abstract

The shuttle effect of lithium polysulfides (LiPSs) and the slow kinetics of redox reactions seriously hinder the potential application of lithium–sulfur batteries (LSBs). Herein, multi-dimensional hybrid nanostructures (Co@N-CNTs/N-Mo_xC) consisting of 1D nitrogen-doped carbon nanotubes with cobalt filling grown on 2D nitrogen-doped Mo_xC nanosheets derived from MXenes are constructed, and applied to the separator modification to enhance the electrochemical performance of LSBs. Notably, the as-fabricated multi-dimensional frameworks can not only afford strong physical blocking and chemisorption towards LiPSs but also provide a large number of active sites to catalyze their reversible conversions. As a result, LSBs assembled with the integrated Co@N-CNTs/N-Mo_xC@PP separator exhibit a high reversible capacity of 1067 mA h g⁻¹ at 0.5C, and an enhanced capacity of 610 mA h g⁻¹ after 500 cycles at 1C with an ultralow capacity decay of 0.09% per cycle, which is superior to that of the cells assembled with N-Mo_xC nanosheets or Co@N-CNTs separators. In addition, an excellent rate capacity of 612 mA h g⁻¹ at 2C and superior cycling stability under high sulfur loading (3.1–4.4 mg cm⁻²) can be achieved, which further confirms the potential applications of Co@N-CNTs/N-Mo_xC in LSBs.