4f-5d orbital tag-team catalysis empowers high-loading zinc-iodine batteries

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Conversion-type positive electrodes promise high energy density but face challenges like shuttle effects and slow kinetics.
• The Sabatier principle highlights the difficulty in balancing strong adsorption for stability and fast kinetics for conversion.

Purpose of the Study:

• To overcome limitations in high-loading conversion electrodes by proposing a novel catalytic mechanism.
• To identify optimal catalysts for iodine conversion in zinc-iodine systems using a machine learning-guided approach.

Main Methods:

• Utilized a machine learning-guided descriptor framework to identify cerium single-atom catalysts.
• Employed density functional theory (DFT) calculations to elucidate the f-d orbital tag-team catalysis mechanism.
• Validated the mechanism in a model zinc-iodine battery system.

Main Results:

• Cerium single-atom catalysts demonstrated superior performance compared to d-block analogues.
• The f-d orbital tag-team mechanism simultaneously stabilized intermediates and facilitated bond activation.
• Achieved high iodine loading (44.7 mg cm⁻²) and areal capacity (10 mAh cm⁻²), with practical pouch cell performance at 115 mg cm⁻² mass loading.

Conclusions:

• The f-d orbital tag-team catalysis mechanism effectively addresses shuttle effects and sluggish kinetics in high-loading conversion electrodes.
• This work bridges orbital-level catalyst design with practical battery performance.
• Offers a new strategy for developing advanced high-loading conversion-type positive electrodes for energy storage.