Three dimensional topological porous carbon/carbon nanotube/graphene matrix decorated with CoFe alloy for lithium sulfur batteries

Abstract

As a potential replacement of lithium-ion batteries (LIBs), lithium-sulfur batteries (LSBs) have high theoretical energy density and long cycle life. However, the poor conductivity of sulfur and Li 2 S 2 /Li 2 S, the shuttle effect of polysulfides and sluggish conversion kinetics have been the hindrance to the development of LSBs. Here, CoFe-nitrogen-doped carbon tubes & hierarchical porous carbon @ graphene oxide (CoFe-NCNT&HC@GO) is proposed to improve the conductivity, mitigate the shuttle effect and enhance the electrochemical kinetics of sulfur electrode. By applying such a three-dimensional topological matrix as a sulfur host and separator modifier, the as-prepared LSB reaches a high capacity of 1130 mAh g −1 after 130 cycles at a current density of 2 A g −1 ; After 500 cycles, the capacity remains around 900 mAh g −1 with an average coulombic efficiency of 99.8 % and a capacity fade rate of 0.062 % per cycle. The results demonstrates that this 3D matrix exhibits strong structural stability, high electrical conductivity , and efficient catalytic ability, and it provides a potential solution for high-performance lithium-sulfur batteries. • Three dimensional topological porous carbon/carbon nanotube/graphene composites were successfully design and prepared. • In situ growth of carbon nanotubes supporting graphene oxide to form 3D topological conducting structures. • FeCo nanoparticles provide multiple efficient catalytic sites for rapid polysulfide conversion.