Gradient Interphase Engineering Enables Crystallographically Aligned Zinc Anodes for Dendrite-Free Electrochemistry.

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy Storage

Background:

• Rechargeable aqueous zinc-ion batteries (AZIBs) are promising for sustainable energy storage but face challenges with zinc anode degradation.
• Irreversible degradation is caused by corrosion and slow zinc ion (Zn²⁺) deposition kinetics, limiting battery lifespan and performance.

Purpose of the Study:

• To address zinc anode degradation in AZIBs by introducing a novel electrolyte additive.
• To improve Zn²⁺ deposition kinetics and enhance interfacial stability for long-term cycling.

Main Methods:

• Introduced zinc hexafluorosilicate hexahydrate (ZnSiF₆·6H₂O, ZSF) as a multifunctional electrolyte additive.
• Utilized ion coordination chemistry and interfacial engineering to analyze ZSF's effects on the electrolyte and electrode interface.
• Investigated ZSF's impact on water activity, solid electrolyte interphase (SEI) formation, ion desolvation, and Zn²⁺ migration.

Main Results:

• ZSF reconstructs hydrogen-bond networks, suppressing free water, and forms a gradient ZnF₂/SiO₂-rich SEI layer.
• The engineered SEI accelerates Zn²⁺ desolvation, reduces nucleation barriers by 46.0%, and boosts Zn²⁺ migration by 115.6%.
• Symmetric cells demonstrated over 2500 hours of stability; full cells with α-MnO₂ cathodes retained 73.4% capacity after 2000 cycles.

Conclusions:

• ZSF acts as a low-cost, effective additive for enhancing AZIB performance and stability through atomic-level electrolyte engineering.
• The study presents a new paradigm for developing grid-scale deployable AZIBs using functional inorganic electrolyte additives.
• This approach significantly overcomes the limitations of zinc anode degradation in aqueous zinc-ion battery systems.