Layered solid Brønsted acid for dynamic interfacial pH regulation toward durable zinc anodes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) offer safe, low-cost grid storage but suffer from hydrogen evolution reaction (HER) at the zinc anode.
• HER leads to unstable interfacial pH, byproduct formation, and dendrite growth, limiting AZIB performance.

Purpose of the Study:

• To develop a material for interfacial pH regulation and zinc anode protection in AZIBs.
• To suppress HER and dendrite formation for enhanced battery stability and longevity.

Main Methods:

• Synthesis of layered solid Brønsted acid HNbMoO₆·H₂O (HNM).
• Density functional theory (DFT) calculations to investigate ion adsorption and interfacial interactions.
• Electrochemical testing of HNM-modified zinc anodes in symmetrical and asymmetrical AZIBs, and full cells.

Main Results:

• HNM effectively adsorbs and neutralizes OH^- ions, maintaining stable interfacial pH.
• DFT calculations confirmed strong OH^- adsorption (E_ads = -4.15 eV) by HNM.
• HNM suppressed HER and dendrite growth, promoting uniform Zn²⁺ deposition.
• HNM@Zn anodes achieved 99.7% Coulombic efficiency over 1000 cycles in asymmetrical cells.
• Stable cycling for over 1750 hours in symmetrical cells and 130 mAh g^-1 capacity after 1000 cycles in full cells.

Conclusions:

• HNM acts as an effective multifunctional material for interfacial pH regulation in AZIBs.
• The engineered interface enhances Zn²⁺ ion transport and deposition kinetics.
• This strategy offers a pathway towards high-performance and durable aqueous zinc-ion batteries.