Defect-Engineered NbS_x as an Efficient Cathode Host for High-Performance Li-Organosulfur Batteries

Organosulfur molecules are considered highly promising cathode materials for lithium batteries due to their high theoretical specific capacities. However, their practical application is hindered due to the issues of the dissolution and shuttling of the discharge products, as well as the electron/ion insulation. In this study, niobium sulfide with abundant sulfur vacancies encapsulated by nitrogen-doped coral-shaped carbon (NbS_x@N-CC) is synthesized using an arc discharge method and interwoven with carbon nanotubes to form an ideal host material for diphenyl tetrasulfide (PTS) as a cathode in rechargeable lithium batteries. The NbS_x@N-CC catalyst can accelerate the cathodic reaction kinetics, adsorb lithium polysulfides (LiPSs) to mitigate the shuttle effect, thus significantly improving the cycling performance. At the 0.5 C rate, the battery exhibits an initial discharge capacity of 520.7 mAh g^-1, with a diminutive cycle capacity decay rate of 0.067% per cycle over 500 cycles. Even under the condition of high PTS loading (6.0 mg cm^-2) and low electrolyte (5 μL mg^-1), the Li-PTS battery can still maintain a capacity retention rate of 97% after stably cycling 150 times at a 0.2 C rate. This work demonstrates that defect engineering is one of the effective approaches to address the challenges of lithium-organosulfur batteries.