Synergistic Interfacial and Solvation Regulation by Nicotinamide for Dendrite-Free, Deep-Cycling Zinc Metal Anodes

Aqueous zinc-ion batteries (AZIBs) represent a promising alternative to conventional energy storage systems due to their inherent safety profile, yet practical implementation remains impeded by dendritic zinc deposition and water-induced parasitic reactions. This work presents a rational interfacial engineering strategy through the integration of nicotinamide (NIC) into Zn(ClO₄)₂ electrolytes, achieving dual regulation of the electrolyte-electrode interface and Zn²⁺ solvation structure. The preferential NIC adsorption at the zinc anode establishes a H₂O-depleted inner Helmholtz plane, forming an interfacial layer that governs Zn²⁺ diffusion kinetics and enables selective exposure of the energetically favorable Zn (002) crystallographic orientation. NIC's molecular architecture disrupts hydrogen-bonding networks in the bulk electrolyte, effectively suppressing hydrogen evolution reactions (HER) through electrochemical pathway modulation. These synergistic effects translate to remarkable electrochemical performance: symmetric Zn//Zn batteries exhibit 5000 h stability at 0.5 mA cm^-2/0.5 mAh cm^-2 and 210 h at 30 mA cm^-2/30 mAh cm^-2 (73.3% DOD), while Zn//Cu half-batteries demonstrate 99.55% Coulombic efficiency at 0.2 mA cm^-2/0.2 mAh cm^-2. Practical validation in NH₄V₄O₁₀//Zn full batteries retains 417 mAh g^-1 capacity after 1000 cycles at 500 mA g^-1 with 88.94% capacity retention. We establish a molecular paradigm to suppress battery dendrites and side reactions via interfacial and solvation control.