Boron Vacancy Engineering in 2D WB-Based MBene Catalysts for Optimizing Lithium Polysulfide Reactions

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

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 impede commercialization.

Purpose of the Study:

• To develop a novel catalyst for Li-S batteries to overcome LiPSs shuttle effect and enhance reaction kinetics.
• To investigate the catalytic mechanism of the novel material for Li-S chemistry.

Main Methods:

• Fabrication of a WB-VB based 2D MXene catalyst with boron vacancies (B vacancies) using a one-step, room-temperature, fluorine-free etching method.
• Characterization of the catalyst's structure and properties.
• In situ X-ray absorption spectroscopy (XAS) to elucidate the catalytic mechanism.

Main Results:

• The WB-VB catalyst effectively inhibited LiPSs diffusion through simultaneous interaction of W and B atoms.
• B-vacancy construction exposed more active W sites and improved the d-band center, accelerating Li-S reaction kinetics.
• Achieved high reversible capacity (1485 mAh g⁻¹ at 0.2 C, 664 mAh g⁻¹ at 4 C) and excellent areal capacity (4.15 mAh cm⁻² at 4.36 mg cm⁻²).
• Demonstrated remarkable cyclic stability.

Conclusions:

• The WB-VB 2D MXene catalyst with B vacancies is a promising material for high-performance Li-S batteries.
• The catalyst effectively addresses key limitations of Li-S battery technology, paving the way for future development.
• In situ XAS provided crucial mechanistic insights into the catalytic process.