Decoupled yet Synergistic Microdomains via In Situ Phase Separation Enabling Ultra‐Stable Zinc Metal Anodes

ABSTRACT While artificial polymer interphases enhance the redox reversibility of Zn metal anodes, their long‐term efficacy is hindered by persistent instability at the electrode‐electrolyte interface. The fundamental compromise lies in concurrently maintaining mechanical integrity and rapid ion transport. To tackle this head‐on, we develop an in situ phase separation strategy to prepare a functional polymeric interphase (PN) composed of highly entangled polymer‐rich tough‐phase domains (octylamine‐grafted PVA skeleton) and elastic Zn 2+ ion‐conductive regions (nano‐confined zincophilic solvent). The former is designed to endow the electrode‐electrolyte interphase with robust mechanical properties, while the latter is dedicated to guaranteeing excellent interfacial ionic conductivity. These decoupled yet synergistic microdomains contribute to rigid‐flexible integrated interface that enables long‐term dendrite‐free Zn deposition, even under high current densities and deep plating/stripping conditions. As a result, Zn anode configured with PN witnesses over 2400 h of highly reversible cycling (∼32‐fold lifespan extension compared to unprotected Zn anode), attaining a maximum cumulative capacity of 21.45 Ah cm −2 at 10 mA cm −2 . Even at an ultra‐high depth of discharge (DOD) up to ∼70%, Zn anode can be stably cycled over 400 h, demonstrating its remarkable cycling durability. This work validates interfacial phase separation as a powerful paradigm for advancing anodic Zn plating/stripping chemistry.