Defect-engineered NbSx as an Efficient Cathode Host for High-performance Li-organosulfur Batteries

Organosulfur molecules are considered as 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, we synthesize abundant sulfur-vacancies niobium sulfide encapsulated by nitrogen-doped coral-shaped carbon (NbSx@N-CC) by an arc discharge method, and interweave it with carbon nanotubes (CNTs) to form an ideal host material for diphenyl tetrasulfide (PTS) as cathode in rechargeable lithium batteries. The NbSx@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 0.2 C rate. This work demonstrates that defect engineering is one of the effective approaches to address the challenges of lithium-organosulfur batteries.