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

Abstract 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-Nx 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-Nx 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 μL 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.