Synergistic solvation-surface engineering for high-performance aqueous zinc metal batteries

Abstract

Aqueous zinc metal batteries (AZMBs) are promising for large-scale energy storage but suffer from Zn metal instability, dendritic growth, and parasitic reactions in conventional electrolytes, hindering commercialization. Here, we propose a synergistic strategy combining solvation engineering and surface adsorption using multifunctional L-threonine (L-Thr). We demonstrate that L-Thr regulates Zn²⁺ solvation by displacing H₂O molecules to suppress water reactivity, disrupts the hydrogen-bond network of water clusters to reduce free water, and preferentially adsorbs on Zn(101) facets, forming a hydrophobic interface that homogenizes Zn²⁺ flux. These synergistic effects enable dendrite-free Zn deposition with minimal side reactions. Consequently, Zn//Cu half-cells achieve a Coulombic efficiency (CE) of 99.71% over 2000 cycles (2 mA cm⁻², 1 mAh cm⁻²), while Zn//Zn symmetric cells exhibit exceptional stability for over 2500 hours (0.5 mA cm⁻², 0.5 mAh cm⁻²). Remarkably, a Zn anode with 68.3% utilization operates stably for 240 hours. Moreover, a practical Zn//NH₄V₄O₁₀ (Zn//NVO) pouch cell with lean anode capacity (N/P ratio = 2.94 : 1) and high cathode loading (12.03 mg cm⁻²) retains 85.4% capacity after 200 cycles, demonstrating its real-world applicability.