Feiyu Tao, Lei Chen, Zhaoqian Li, Jiaqin Liu, Xingwei Cai, Daming Zhu, Hong Zhang, Chengwu Shi, Yingke Ren, Linhua Hu, Y N Wu
ABSTRACT 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(ClO 4 ) 2 electrolytes, achieving dual regulation of the electrolyte‐electrode interface and Zn 2+ solvation structure. The preferential NIC adsorption at the zinc anode establishes a H 2 O‐depleted inner Helmholtz plane, forming an interfacial layer that governs Zn 2+ 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 NH 4 V 4 O 10 //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.