Constructing a Super-Saturated Electrolyte Front Surface for Stable Rechargeable Aqueous Zinc Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable aqueous zinc batteries (RAZB) offer safety and cost advantages but suffer from limited lifespan due to zinc dendrite formation.
• Zinc dendrites cause short circuits and capacity fading, hindering practical application of RAZB.

Purpose of the Study:

• To develop a strategy to suppress zinc dendrite growth and improve the cycling stability of RAZB.
• To investigate the mechanism of dendrite suppression using a metal-organic framework (MOF) coating.

Main Methods:

• Fabrication of a MOF as a protective front surface layer for the zinc anode.
• Electrochemical testing of symmetric zinc cells and aqueous MnO2-Zn batteries.
• Raman spectroscopy to analyze ion complexation and solvation structures.

Main Results:

• The MOF coating effectively maintained a super-saturated electrolyte layer on the zinc anode.
• Symmetric zinc cells with the MOF coating achieved 3000 hours of stable cycling at 0.5 mA cm⁻², a 55-fold improvement over bare anodes.
• Aqueous MnO2-Zn batteries demonstrated a reversible capacity of 180.3 mAh g⁻¹ and 88.9% retention after 600 cycles with high mass loading.

Conclusions:

• MOF-based front surface layers are highly effective in preventing zinc dendrites and enhancing RAZB performance.
• The super-saturated electrolyte layer mediated by the MOF is crucial for stable zinc deposition.
• This approach offers a promising pathway for developing safer, longer-lasting, and cost-effective aqueous zinc batteries.