Less is More: Underlying Mechanism of Zn Electrode Long-Term Stability using Sodium L-Ascorbate as Electrolyte...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc ion batteries are promising energy storage devices.
• Electrode passivation and ion solvation significantly impact battery performance.
• Controlling zinc deposition is crucial for long cycle life.

Purpose of the Study:

• To investigate the effect of sodium L-ascorbate (Ass) as an electrolyte additive in aqueous zinc sulfate (ZnSO₄) electrolytes.
• To understand how Ass modifies passivation layers and Zn²⁺ solvation structure.
• To evaluate the electrochemical performance enhancement in zinc ion batteries.

Main Methods:

• Experimental characterizations (e.g., microscopy, spectroscopy).
• Theoretical calculations.
• Electrochemical testing of Zn||Zn symmetric and Zn||MnO₂ full cells.

Main Results:

• Ass forms unique vertical arrayed micro-nano passivation layers.
• Ass alters Zn²⁺ solvation by replacing water with As^- ligands.
• Improved wettability, ionic diffusion, and suppressed side reactions observed.
• Zn||Zn symmetric cells operated stably for ~3700 hours.
• Zn||MnO₂ full cells achieved 184 Wh kg^-1 at 2 kW kg^-1 and 80.5% capacity retention after 1000 cycles.

Conclusions:

• Sodium L-ascorbate effectively regulates the zinc electrode interface.
• The modified interface promotes uniform zinc deposition and enhances battery stability and energy density.
• Ass is a promising additive for high-performance aqueous zinc ion batteries.