Bond Exchange-Driven Interfacial Relay Redox Enables Ultrahigh-Rate Zn Batteries With High Iodine Utilization.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-iodine batteries offer potential for various applications.
• A major limitation is the "dead iodine" issue, reducing iodine utilization and capacity, especially at high charge/discharge rates.

Purpose of the Study:

• To design an interfacial relay redox strategy to overcome the "dead iodine" problem in zinc-iodine batteries.
• To improve iodine utilization, areal capacity, and rate capability.

Main Methods:

• Developed a strategy using electrochemically generated polyiodides as redox anchors on the current collector.
• Utilized halogen-bond exchange to facilitate uniform polyiodide deposition/dissolution and suppress shuttling.
• Employed hydrophobic organic cation-polyiodide pairs to enhance stability and ion/electron transport.

Main Results:

• Achieved exceptional rate capability up to 100 mA cm⁻².
• Demonstrated high iodine utilization (51%-80% at 1-40 mA cm⁻²).
• Showcased long-term cyclability with over 1,200 cycles at 7.04 mAh cm⁻².

Conclusions:

• The interfacial relay redox strategy effectively eliminates "dead iodine," significantly enhancing zinc-iodine battery performance.
• The developed system exhibits superior rate capability, iodine utilization, and cycle life compared to state-of-the-art systems.
• This work presents a new design paradigm for static halogen batteries with high energy/power density and longevity.