A Multifunctional MoC-Decorated Dual-Carbon Nanofiber Host for High-Performance Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but face challenges.
• The shuttle effect of lithium polysulfides (LiPSs) and slow sulfur conversion kinetics limit practical application.
• These issues lead to rapid capacity decay and reduced cycle life in Li-S batteries.

Purpose of the Study:

• To design and synthesize a multifunctional sulfur host material for advanced Li-S batteries.
• To address the limitations of LiPS shuttle effect and sluggish sulfur conversion kinetics.
• To enhance the electrochemical performance and long-term stability of Li-S cells.

Main Methods:

• Fabrication of a hierarchical dual-carbon architecture: MoC-modified nitrogen-doped carbon nanofibers (NCNF) coated with vertically aligned graphene sheets (VGS).
• Characterization of the VGS@MoC/NCNF material for its structural and compositional properties.
• Electrochemical testing of Li-S cells utilizing the VGS@MoC/NCNF sulfur host.

Main Results:

• The VGS@MoC/NCNF sulfur host effectively confined LiPSs via synergistic physical-chemical interactions.
• MoC nanoparticles provided dual adsorption-catalysis functions, accelerating LiPS redox kinetics.
• The VGS@MoC/NCNF-S cathode exhibited an initial capacity of 1070.8 mAh g^-1.
• Exceptional cycling stability was achieved, maintaining 798.5 mAh g^-1 after 400 cycles at 1 C with a low capacity fade rate of 0.063% per cycle.

Conclusions:

• The designed VGS@MoC/NCNF material serves as a high-efficiency sulfur host for Li-S batteries.
• The integrated functionality of polysulfide confinement and catalytic conversion is crucial for performance enhancement.
• This work presents a promising strategy for developing stable and high-performance Li-S batteries.