Molecular anchoring-induced proton adsorption effect achieves stable zinc metal anodes

Abstract

The development of high-energy, environmentally friendly, and intrinsically safe aqueous zinc-ion batteries (AZIBs) requires stable zinc metal anodes (ZMAs). However, the cycling durability of ZMAs is significantly compromised by interfacial degradation mechanisms, including uncontrolled Zn²⁺-induced dendrite formation, parasitic hydrogen evolution reaction (HER), and surface corrosion. In this work, we introduce a multifunctional electrolyte additive, dicyandiamide (DCD), which induces a molecular anchoring-driven proton adsorption effect to stabilize ZMAs. The cyano group anchors DCD at the interface, regulating Zn²⁺ deposition, while the amine group selectively adsorbs free H⁺ generated by water decomposition, effectively inhibiting the HER and corrosion. With only 0.02 M DCD added, Zn–Zn symmetric cells demonstrate stable cycling for more than 1400 hours at 5 mA cm⁻² and 1 mAh cm⁻², while Zn–Cu half-cells exhibit over 3000 cycles with an average coulombic efficiency of 99.86%. Moreover, the DCD additive enables Zn–NH₄V₄O₁₀ full cells to retain ultrahigh capacity and cycling stability at high current densities (3 A g⁻¹) and under practical conditions (10 μm Zn, 12.5 mg cm⁻²). This study provides a new strategy for designing multifunctional additives that do not significantly alter the electrolyte solvation structure.