Multifunction Co-Nx species to manipulate polysulfides conversion kinetics toward highly efficient lithium-sulfur batteries

It is highly important to develop high-performance sulfur cathode to solve low areal sulfur loading, shuttling and sluggish conversion of polysulfides for lithium-sulfur batteries. Herein, a three-dimensional (3D) freestanding framework configured with Co nanoparticles and Co-N-x codoped carbon nanotubes anchored in a carbon foam is synthesized and investigated as a new type of sulfur host. Such an architecture can serve not only as a conductive carbon networks but also as host scaffold for high sulfur-containing electrodes. The hierarchical porous structures cooperated with high density and dispersion multifunctional Co-N-x species can efficiently trap and manipulate catalytic conversion kinetics of polysulfides. Benefiting from above characteristics, the designed cathodes exhibit a high capacity (1259 mA h g(-1)) at 0.1 C and excellent cycling performance with an ultralow decay of 0.038% per cycle over 500 cycles at a high current density of 3 C. Even with a high sulfur loading (7.0 mg cm(-2)) and lean electrolyte (E/S = 5 mu L mg(-1)) operation, a high areal capacity of 4.34 mA h cm(-2) is still achieved after 100 cycles at 0.1 C. This work provides a low-cost route for preparation of freestanding cathode materials toward highly efficient lithium-sulfur batteries.

Automated summary

A new type of three-dimensional freestanding framework sulfur cathode has been synthesized and investigated for lithium-sulfur batteries, which can efficiently solve the problems of low sulfur loading, shuttling, and sluggish conversion. The material exhibits high capacity and excellent cycling performance, even under high sulfur loading and lean electrolyte conditions, achieving high areal capacity.