Rational Design of Highly Stable and Active Single-Atom Modified S-MXene as Cathode Catalysts for Li-S Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Lithium-sulfur (Li-S) batteries face challenges like the shuttle effect and slow sulfur conversion, limiting their practical use.
• Developing efficient catalysts is crucial for overcoming these limitations and enhancing Li-S battery performance.

Purpose of the Study:

• To propose and evaluate single atoms (SAs) integrated into sulfur-functionalized MXenes (S-MXenes) as catalysts for Li-S batteries.
• To identify promising SA-modified S-MXenes through computational screening and understand their catalytic mechanisms.

Main Methods:

• First-principles calculations and high-throughput screening were employed to investigate various SA-modified S-MXenes.
• Gibbs free energy barriers for key reactions and adsorption energies of intermediates were calculated.
• Strain engineering and machine learning models were utilized to further analyze and predict catalytic performance.

Main Results:

• 73 promising SA-modified S-MXene candidates were identified, showing excellent stability and polysulfide immobilization.
• Ni, Cu, or Zn SAs significantly reduced the Gibbs free energy barrier (51%-75%) compared to graphene catalysts.
• Strain engineering enhanced catalytic activity by optimizing the d-band center of metal atoms.
• A machine learning model (R² = 0.88) revealed the importance of SA electronegativity and coordination environment.

Conclusions:

• Single atom catalysts on S-MXenes offer a promising strategy for advancing Li-S battery technology.
• The study provides fundamental insights into catalyst design for improved Li-S battery kinetics and stability.
• This work paves the way for rational design of highly efficient catalysts for next-generation batteries.