Phase Engineering of ZnSe by Small Molecules as a High-Performance Protective Layer for Zn Anode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc ion batteries (AZIBs) face challenges in practical application due to side reactions and dendrite growth on the zinc (Zn) anode.
• These issues limit the long-term stability and safety of AZIBs.

Purpose of the Study:

• To enhance the performance of Zn anodes in AZIBs by developing a phase-engineered ZnSe coating layer.
• To investigate the role of small molecules in modifying the ZnSe coating for improved Zn deposition and stability.

Main Methods:

• Phase engineering of a ZnSe coating layer by incorporating small molecules (hydrazine).
• Characterization of the ZnSe⋅0.5N₂H₄ coating's electronic structure and its interaction with Zn atoms.
• Electrochemical testing of symmetric Zn cells and full cells using the modified Zn anode.

Main Results:

• The ZnSe⋅0.5N₂H₄ coating exhibits strong adsorption for Zn atoms and effectively inhibits hydrogen evolution.
• Uniform Zn deposition and prevention of by-product and dendrite growth were observed.
• ZnSe⋅0.5N₂H₄@Zn symmetric cells demonstrated long-term cycling stability up to 1900 hours at 5 mA cm^-2 and 300 hours at 20 mA cm^-2.
• The full cell (ZnSe⋅0.5N₂H₄@Zn||NH₄V₄O₁₀) showed excellent cycling stability and rate capability.

Conclusions:

• Phase engineering of protective layers is crucial for high-performance zinc anodes.
• The ZnSe⋅0.5N₂H₄ coating effectively promotes uniform Zn deposition and suppresses dendrite formation.
• This approach offers a promising strategy for developing stable and efficient aqueous zinc ion batteries.