d-p Hybridization-Induced "Trapping-Coupling-Conversion" Enables High-Efficiency Nb Single-Atom Catalysis for Li-S...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysts are crucial for enhancing reaction kinetics and polysulfide anchoring in lithium-sulfur (Li-S) batteries.
• Fourth-period d-block single atoms exhibit chemical interactions for effective lithium polysulfide adsorption and catalysis.

Purpose of the Study:

• To design and investigate novel single-atom niobium (Nb) catalysts for improved sulfur immobilization and catalysis in Li-S batteries.
• To explore the mechanism of Nb-N4 active sites in anchoring and converting lithium polysulfides.

Main Methods:

• Theoretical screening guided the design of single-atom Nb catalysts.
• Computational calculations were used to analyze the electronic structure and interaction mechanism.
• Electrochemical performance of Nb-SAs@NC cells was evaluated.

Main Results:

• The Nb-N4 active moiety facilitates d-p hybridization and enhances lithium polysulfide anchoring via a "trapping-coupling-conversion" mechanism.
• Nb-SAs@NC cells demonstrated high capacity retention (>85% after 1000 cycles) and superior rate performance (740 mAh g⁻¹ at 7 C).
• A competitive areal capacity of 5.2 mAh cm⁻² was achieved.

Conclusions:

• Single-atom Nb catalysts offer a promising strategy for high-energy-density Li-S batteries.
• The proposed mechanism provides insights into catalyst design for advanced battery technologies.
• This work opens new avenues for developing high-performance Li-S battery cathodes.