Stabilizing Zinc Electrodes with a Vanillin Additive in Mild Aqueous Electrolytes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Metallic zinc (Zn) is a promising anode for aqueous batteries.
• Challenges include zinc dendrite growth and water-induced corrosion, limiting battery lifespan.
• Developing stable Zn anodes is crucial for high-performance aqueous batteries.

Purpose of the Study:

• To investigate vanillin as a bifunctional additive for stabilizing Zn electrochemistry in aqueous electrolytes.
• To elucidate the mechanism of vanillin's action on the Zn anode surface and electrolyte interface.
• To demonstrate the improved performance of vanillin-modified Zn anodes in various battery configurations.

Main Methods:

• Computational modeling to understand vanillin adsorption and interaction with Zn2+.
• Spectroscopic techniques to analyze the Zn electrode-electrolyte interface.
• Electrochemical measurements including cycling tests and Coulombic efficiency in Zn|Zn, Zn|Cu, and Zn|V2O5 cells.

Main Results:

• Vanillin molecules adsorb parallel to the Zn surface, promoting uniform Zn plating and suppressing dendrites.
• Vanillin weakens the solvation of Zn2+ by water, reducing hydrogen evolution and byproduct formation.
• The Zn anode with vanillin additive achieved high areal capacity (10 mAh cm-2) and long cycling stability (1000 h) in Zn|Zn cells.
• High Coulombic efficiency (99.8%) was observed in Zn|Cu cells, and stable operation in full Zn|V2O5 batteries was demonstrated.

Conclusions:

• Vanillin acts as an effective bifunctional additive, enhancing Zn anode stability and performance in aqueous electrolytes.
• The proposed strategy offers a facile, cost-effective approach for designing high-performance aqueous Zn batteries.
• Vanillin's benefits are generalizable to different electrolyte compositions, including Zn(CF3SO3)2-based systems.