Hierarchical Interface Enabled by a Guest-Anionic Chemistry for High-Rate Aqueous Zinc-ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) face challenges in practical application due to poor zinc anode reversibility.
• Interfacial side reactions and dendritic growth on the zinc anode limit the cycle life and safety of AZIBs.
• Developing stable solid electrolyte interphases (SEIs) is crucial for overcoming these limitations.

Purpose of the Study:

• To enhance the reversibility and stability of the zinc anode in AZIBs.
• To investigate the effect of a co-solute, acesulfame potassium, on electrolyte properties and interfacial behavior.
• To demonstrate the performance of AZIBs utilizing the modified electrolyte.

Main Methods:

• Introduction of acesulfame potassium as a co-solute in a low-concentration aqueous electrolyte.
• Electrochemical characterization of the zinc anode, including cycling performance at high current densities.
• Assembly and testing of Zn//I2 full cells and large-sized pouch cells.

Main Results:

• The designed electrolyte significantly improves zinc anode reversibility, enabling stable operation at 40 mA cm⁻² and 67.6% depth of discharge.
• A stable SEI with a hierarchical crystalline-amorphous bilayer structure is formed, suppressing side reactions and promoting uniform zinc deposition.
• Zn//I2 full cells show high rate capability (135.0 mAh g⁻¹ at 20 A g⁻¹) and exceptional lifespan (96.3% retention after 40,000 cycles).

Conclusions:

• Acesulfame potassium effectively regulates the zinc anode interface, leading to enhanced electrochemical performance.
• The developed electrolyte chemistry demonstrates significant potential for practical, high-performance aqueous zinc-ion batteries.
• The study highlights the promise of guest-anionic chemistry in advancing energy storage solutions.