Compact ion-selective monolayer via electronic modulation for highly stable zinc metal anodes

Achieving highly reversible Zn anodes remains a critical challenge for aqueous zinc-ion batteries (AZIBs) due to uncontrolled dendrite growth and parasitic side reactions. Conventional strategies of electrolyte engineering or protective coating improve Zn metal reversibility but at the cost of environmental friendliness or complex production procedure. Here, we introduce a molecular engineering strategy that precisely tailors the electric double layer (EDL) at molecular scale using self-assembled monolayers (SAMs). Unlike conventional thick surface coatings, our approach exploits π-π stacking interactions between aromatic backbones, with electron-donating substituents (-OCH 3 ) amplifying intermolecular dispersion forces to create an ultradense protective layer. This molecularly-engineered interface exhibits dual functionality: the steric hindrance effect creates a water-deficient inner Helmholtz plane while the electron-rich aromatic rings serve as Zn 2+ coordination sites, establishing a “molecular-level ion-selective channel” that fundamentally reconstructs the EDL architecture. Simultaneously, the SAMs modulate the Zn anode electronic structure, reducing work function from 3.86 to 3.61 eV, thereby enhancing electron-donating capability for accelerated Zn deposition. These synergistic effects enable exceptional Zn anode performance, achieving over 3000-hour stable cycling at 1 mA cm −2 and high Coulombic efficiency of 99.91% over 2900 cycles. This work establishes molecular-level EDL engineering as a powerful paradigm for metal anode stabilization, demonstrating that precise manipulation of interfacial chemistry at the angstrom scale can overcome longstanding challenges in energy storage systems.