Molecular fence on the inner Helmholtz plane for highly reversible zinc metal anodes

The practical application of aqueous zinc-ion batteries is hampered by rampant dendrite growth and by-reactions originating from the destabilized electrode–electrolyte interface. While current strategies focus on constructing artificial interphases or manipulating the bulk solvation structure, they often overlook the precise regulation of the chemical microenvironment at the Inner Helmholtz Plane (IHP)—the very origin of interfacial reactions. This work reports a distinctive electrolyte additive strategy using hexafluorobenzene (HFB) that achieves molecular-level reconstruction of the IHP without altering the primary solvation structure of Zn 2+ ([Zn(H 2 O) 6 ] 2+ ). Multiscale simulations and spectroscopic analysis confirm that the electron-rich aromatic plane of HFB enables its preferential adsorption onto the Zn surface over water molecules, thereby forming a dehydrated and hydrophobic IHP. This reconfigured interface serves a dual critical function. This reconfigured interface functions as an efficient molecular fence that blocks water contact and suppresses hydrogen evolution while simultaneously reducing zinc ions interfacial migration barrier to guide dendrite-free deposition. Zn//Zn symmetric batteries with HFB additive achieve an ultra-stable cycling lifespan exceeding 3400 h at 1 mA cm −2 /1 mAh cm −2 . This work reveals the mechanism of stabilizing metal anodes through specific interface adsorption, providing a novel approach for the design of electrolytes in advanced aqueous batteries. • A hydrophobic molecular fence constructed via π–Zn interaction with HFB, enabling dynamic and reversible conformational adjustments at the zinc anode interface. • HFB significantly reduces the desolvation energy barrier of Zn 2+ at the interface by creating a water-deficient microenvironment, which optimizes the uniformity of Zn nucleation and deposition. • Multiscale simulations elucidate the specific adsorption-dominated IHP regulation mechanism, providing a novel strategy and theoretical insights for zinc anode modification and high-stability AZIBs using hydrophobic aromatics.