The application of zinc (Zn) metal-based batteries is hindered by the uncontrollable thermodynamics-driven hydrogen evolution reactions and kinetics-induced dendrite growth, resulting in reduced cycling stability and premature battery failure. To tackle these challenges, we introduce a pH-mediated surface charge-reinforced and ion-selective strategy by using a facile self-assembled approach, which in-situ constructed the cysteamine (SH-CH2-CH2-NH2) molecular layers (SALs) on the Zn metal surface (Zn@SCRIS-SALs). Triggered by the pH-mediated-protonation effect, these layers generate a partial positive surface (-NH3+) to repel the hydrated protons and zinc-philic sites (-NH2) for anchoring Zn2+. The synergistic combination of the above effects enabled highly reversible Zn metal chemistry to effectively suppress side reactions and dendrite growth. The Zn@SCRIS-SALs in symmetric cells exhibited stability with an ultralong lifespan of 2500 h under a high current density of 10 mA cm-2. The superior reversibility was further ascertained by integrating Zn@SCRIS-SALs with the I2 cathode in full cells, which showed high-capacity retention compared to bare Zn-based cells. Furthermore, 80 mAh pouch cells assembled with Zn@SCRIS-SALs were operated over 2500 cycles at an areal capacity of 5.18 mA h cm-2. This work offers a new platform to finely modulate the electron state of interfacial molecule layers for highly reversible aqueous Zn ion batteries.
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