Cation-Engineered Gradient Interfacial Structure Toward Dendrite-Free and Shuttle-Free Aqueous Zn-Iodine Batteries.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous Zn-iodine batteries (AZIBs) face challenges like uncontrolled dendrite growth, water side reactions, and polyiodide shuttling.
• These issues limit the cycle life and efficiency of AZIBs, hindering their practical application.
• Optimizing the zinc anode interface is crucial for overcoming these limitations.

Purpose of the Study:

• To develop an effective strategy for regulating the electric double layer (EDL) at the Zn anode in AZIBs.
• To suppress detrimental side reactions and improve the stability of AZIBs using interfacial modification.
• To enhance the overall performance and cycle life of aqueous Zn-iodine batteries.

Main Methods:

• Utilized an amphiphilic acetylcholine cation (ACh+) as an interfacial modifier for the Zn anode.
• Engineered a hydrophobic-hydrophilic gradient interfacial structure on the Zn anode surface.
• Investigated the effect of the modified EDL on Zn deposition, ion transport, and polyiodide shuttle suppression.

Main Results:

• The ACh+-modified EDL structure effectively reduced direct Zn-electrolyte contact and suppressed side reactions.
• The strategy significantly lowered the Zn2+ desolvation energy barrier and inhibited polyiodide shuttling.
• Achieved high Coulombic efficiency (99.82%) and remarkable long-term stability for the Zn anode.
• The Zn-I2 full cell demonstrated an ultralow capacity decay rate over 25,000 cycles.

Conclusions:

• The "EDL-directed regulator" strategy using ACh+ provides an effective method for interfacial engineering in AZIBs.
• Optimizing the Zn anode interfacial chemistry is key to advancing the performance and durability of aqueous Zn-iodine batteries.
• This work offers a promising approach for developing high-performance and stable AZIBs for energy storage applications.