Engineering p-d Coupling at Fe-Bi and Zn-Bi Sites for Efficient Li-S Conversion

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• High-performance lithium-sulfur (Li-S) batteries require advanced electrocatalytic sulfur hosts.
• Atomically dispersed metals with tailored electronic structures are essential for efficient Li-S battery operation.

Purpose of the Study:

• To develop novel dual-atom catalysts (DACs) for enhanced Li-S battery performance.
• To investigate the role of earth-abundant bimetallic pairs (Fe-Bi, Zn-Bi) on nitrogen-doped carbon supports.

Main Methods:

• Synthesis of 3d-6p DACs using earth-abundant Fe-Bi or Zn-Bi pairs on nitrogen-doped carbon.
• Characterization using aberration-corrected scanning transmission electron microscopy (STEM) and X-ray absorption spectroscopy (XAS).
• Electrochemical testing in Li-S cells and density functional theory (DFT) calculations.

Main Results:

• Confirmed atomically dispersed bimetallic centers stabilized by transition metal-nitrogen (TM-N) coordination.
• Demonstrated accelerated polysulfide conversion and near-ideal discharge plateau ratios with DACs, especially Fe-Bi.
• Achieved superior rate capability (>50% capacity retention at 3C) and long-term cycling stability (~80% retention after 1000 cycles at 1C).

Conclusions:

• Bismuth (Bi) induces synergistic electronic effects (ligand-field and p-d coupling) that enhance catalyst activity.
• The Bi-driven cooperative activation overcomes d-electron limitations, leading to high-rate and durable Li-S electrocatalysts.
• Presents a general, scalable strategy for designing advanced electrocatalysts for Li-S batteries.