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

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Organosulfur compounds offer high capacity for lithium batteries but suffer from product dissolution and poor conductivity.
• Existing challenges include the shuttle effect of lithium polysulfides (LiPSs) and limited electron/ion transport.

Purpose of the Study:

• To develop a novel cathode material for rechargeable lithium batteries using organosulfur compounds.
• To address the limitations of dissolution, shuttling, and conductivity in lithium-sulfur batteries through material design.

Main Methods:

• Synthesis of sulfur-deficient niobium sulfide encapsulated by nitrogen-doped coral-shaped carbon (NbSx@N-CC) via arc discharge.
• Integration of NbSx@N-CC with carbon nanotubes as a host for diphenyl tetrasulfide (PTS).
• Electrochemical characterization of the Li-PTS battery performance.

Main Results:

• The NbSx@N-CC host effectively adsorbs LiPSs, suppressing the shuttle effect and improving reaction kinetics.
• The battery achieved an initial discharge capacity of 520.7 mAh g⁻¹ at 0.5 C with a low decay rate of 0.067% per cycle over 500 cycles.
• High capacity retention (97% after 150 cycles) was maintained under demanding conditions (high PTS loading, low electrolyte ratio).

Conclusions:

• Defect engineering in niobium sulfide, combined with a nitrogen-doped carbon host, is a viable strategy to overcome challenges in lithium-organosulfur batteries.
• The developed NbSx@N-CC material significantly enhances the electrochemical performance and stability of PTS-based cathodes.
• This approach offers a promising pathway for advanced high-energy-density rechargeable lithium batteries.