A Polysulfide-Trapping Interface for Electrochemically Stable Sulfur Cathode Development.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high capacity and low cost but face challenges like polysulfide diffusion.
• Polysulfide diffusion leads to capacity fade and limits the practical application of Li-S cells.

Purpose of the Study:

• To address polysulfide diffusion in Li-S cells.
• To enhance the stability and cyclability of Li-S batteries.
• To introduce a novel boron-doped carbon nanotube coated separator.

Main Methods:

• Fabrication of a boron-doped multiwalled carbon nanotube coated separator.
• Integration of the coated separator as a polysulfide-trapping interface in Li-S cells.
• Electrochemical testing to evaluate cyclability and capacity retention.

Main Results:

• The boron-doped carbon nanotube coated separator effectively traps polysulfides, preventing capacity fade.
• Li-S cells with the coated separator show improved cyclability across various rates (0.2C to 1.0C).
• Achieved 60% capacity retention with a low fade rate of 0.04% per cycle after 500 cycles.

Conclusions:

• The boron-doped carbon nanotube coated separator acts as a polysulfide trap, stabilizing the cathode.
• Dissolved polysulfides are repurposed to activate bulk sulfur, enhancing battery performance.
• This work opens new avenues for heteroatom-doped carbon materials in flexible, coated separators for Li-S batteries.