Molecular-Level Zn-Ion Transfer Pump Specifically Functioning on (002) Facets Enables Durable Zn Anodes.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Metallic zinc anodes in zinc-ion batteries (ZIBs) face challenges like dendrite growth and side reactions, limiting cycle life.
• Modulating zinc deposition on specific crystal facets, particularly (002), is crucial for enhancing anode stability and battery longevity.

Purpose of the Study:

• To improve the cycling stability and lifespan of zinc anodes in ZIBs.
• To promote uniform, in-plane zinc deposition by modifying the electrolyte composition.
• To investigate the mechanism of zinc deposition influenced by electrolyte additives.

Main Methods:

• Addition of trace amounts of zinc tetrafluoroborate (Zn(BF4)2) to a 3 M zinc sulfate (ZnSO4) electrolyte.
• Electrochemical testing of modified zinc anodes, including galvanostatic cycling and plating capacity measurements.
• Fabrication and testing of aqueous Zn|(NH4)2V6O16·3H2O full cells to evaluate long-term performance.

Main Results:

• The optimized electrolyte facilitated in-plane Zn deposition via a specific ion transfer process, enhancing (002) facet function.
• Achieved extended cycling stability for Zn anodes with high Zn utilization (34.2% at 500 h, 51.3% at 360 h).
• Demonstrated a competitive cumulative plating capacity (CPC) of 2.87 Ah cm-2 and full cells with minimal capacity degradation over 2000 cycles.

Conclusions:

• The addition of Zn(BF4)2 is a cost-effective strategy to promote stable Zn anode performance in ZIBs.
• This approach significantly enhances cycling stability and lifespan, addressing key limitations in ZIB technology.
• The findings offer valuable insights for optimizing metal anodes in ZIBs and other energy storage systems.