A "Zn²⁺ in Salt" Interphase Enabling High-Performance Zn Metal Anodes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc ion batteries (AZIBs) offer high safety and low cost.
• Zinc metal anodes face challenges like hydrogen evolution, side reactions, and dendrite growth, limiting AZIB performance.
• Developing stable zinc anodes is crucial for advancing AZIB technology.

Purpose of the Study:

• To develop a protective interphase for zinc anodes in aqueous electrolytes.
• To enhance the stability and reversibility of zinc metal anodes.
• To improve the cycling performance of aqueous zinc ion batteries.

Main Methods:

• In situ construction of a "Zn²⁺ in salt" (ZIS) interphase on the zinc anode surface (ZIS@Zn).
• Utilizing the hydrophobicity of the ZIS interphase to isolate the anode from the aqueous electrolyte.
• Employing the ZIS interphase as an ordered, water-free ion-conducting medium for zinc deposition.
• Assembling symmetric cells and full batteries with a vanadium-based (NVO) cathode for performance evaluation.

Main Results:

• The ZIS interphase effectively suppressed hydrogen evolution reactions and side reactions.
• Uniform zinc deposition and rapid Zn²⁺ migration were achieved at the interface.
• Symmetric cells demonstrated dendrite-free plating/striping for 4500 hours and a critical current density of 14 mA cm^-2.
• Full batteries with ZIS@Zn anodes and NVO cathodes retained 88% capacity after 1600 cycles.

Conclusions:

• The ZIS interphase provides an effective strategy for stabilizing zinc anodes in aqueous electrolytes.
• This approach significantly enhances the reversibility and long-term cycling stability of AZIBs.
• The water-free ion-conducting ZIS interphase is key to overcoming the limitations of aqueous zinc metal anodes.