Regulating Polysulfide Conversion Kinetics Using Tungsten Diboride as Additive For High-Performance Li-S Battery

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium-sulfur (Li-S) batteries face challenges like low sulfur utilization, polysulfide shuttling, and anode degradation, hindering practical application.
• Developing advanced cathode materials and protective anode strategies is crucial for high-performance Li-S batteries.

Purpose of the Study:

• To enhance Li-S battery performance by addressing polysulfide dissolution and improving sulfur utilization.
• To develop a novel cathode structure incorporating hollow carbon spheres and tungsten diboride nanoparticles.
• To engineer a protected anode to ensure stable cycling.

Main Methods:

• Synthesis of hollow carbon (HC) spheres as a sulfur host.
• Incorporation of tungsten diboride (WB2) nanoparticles as a conductive additive and polysulfide anchor.
• Fabrication of a freestanding lithiated-poly(4-styrene sulfonate) membrane for anode protection.
• Experimental testing and Density Functional Theory (DFT) calculations to analyze WB2-polysulfide interactions.

Main Results:

• WB2 nanoparticles effectively anchor lithium polysulfides (LiPS) via B-S bond formation, accelerating their conversion.
• DFT confirms WB2's strong interaction with LiPS, reducing shuttling.
• The protected anode provides a stable interface and homogeneous Li-ion flux.
• Cells with the optimized cathode and anode show improved active material utilization, rate capability, and cycling stability.

Conclusions:

• The synergistic effect of HC spheres and WB2 nanoparticles in the cathode, combined with the protected anode, significantly boosts Li-S battery performance.
• This approach demonstrates potential for high sulfur loading and reduced electrolyte usage.
• The developed Li-S battery architecture exhibits high reversible capacity and excellent capacity retention.