Layered Solid Brønsted Acid for Dynamic Interfacial pH Regulation Toward Durable Zinc Anodes

Abstract

Aqueous zinc-ion batteries (AZIBs) are promising candidates for large-scale grid energy storage due to their inherent safety, durability, and low cost. However, their practical performance is hampered by hydrogen evolution reaction (HER) on Zn anode, causing unstable Zn/electrolyte interfacial pH values and thus formation of byproducts and uncontrollable Zn dendrite growth. To address these issues, we developed a layered solid Brønsted acid HNbMoO6·H2O (HNM) for interfacial pH regulation and Zn anode protection. Density function theory (DFT) calculations suggested the strong adsorption of OH⁻ ions by HNM (Eads = - 4.15 eV), and the abundant interlayer hydrated protons in HNM can effectively adsorb and neutralize OH⁻ ions, offering stable interfacial pH values, preventing alkaline byproduct formation and suppressing tip-induced dendrite growth. Moreover, the layered HNM establishes stable ion transport channels, enabling ordered Zn2+ flux and homogeneous Zn2+ deposition. Notably, HNM simultaneously inhibits HER and accelerates Zn2+/Zn plating/stripping kinetics. Resultedly, HNM@Zn enabled excellent Coulombic efficiency of 99.74% (over 1000 cycles) in asymmetrical cells, exceptional Zn2+ transference number of 0.79 and stable cycling of over 1750 hours in symmetrical cells, and retaining a capacity of 130 mAh g⁻¹ after 1000 cycles in HNM@Zn||α-MnO2 full cells. This work provides insights into multifunctional anode engineering for interfacial pH regulation towards high-performance AZIBs.