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

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-MoxC) consisting of 1D nitrogen-doped carbon nanotubes with cobalt filling grown on 2D nitrogen-doped MoxC 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-MoxC@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-MoxC 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-MoxC in LSBs.