Synergistic Strategy of Targeted Capture and Potential Responsive Release for High-Performance Zinc-Iodine Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• The shuttle effect from polyiodide species dissolution and migration limits zinc-iodine (Zn─I₂) battery applications.
• Current carbon-based cathodes offer insufficient confinement for iodine species due to weak physical adsorption.

Purpose of the Study:

• To develop a novel cathode material that dynamically captures and releases iodide ions, suppressing the shuttle effect in Zn─I₂ batteries.
• To enhance the energy density and cycle stability of iodine-based batteries.

Main Methods:

• Synergistic strategy combining targeted I^- capture (forming BiOI) and responsive I^- release during Bi³⁺ reduction.
• Ex situ spectroscopic analysis and Density Functional Theory (DFT) calculations for validation.
• Incorporation of Bi₂O₃ to introduce an additional redox couple.

Main Results:

• Successfully suppressed polyiodide formation and ensured efficient cathode reversibility.
• Achieved a dynamic and directional capture-release process at a potential lower than I₂ reduction.
• Demonstrated a high capacity level for iodine single-electron conversion, surpassing inherent side reaction limitations.

Conclusions:

• The proposed decoupled capture-release mechanism effectively mitigates shuttle effects in Zn─I₂ batteries.
• Bismuth-based materials offer a universal design principle for manipulating iodine electrochemistry.
• This approach paves the way for high-energy, long-lifespan halogen-based batteries.