Ion‐Regulating SPEEK–BNNS Hybrid Interfaces Enabling Low‐Barrier Zn‐Ion Transport and Dendrite‐Free Zinc Anodes

ABSTRACT The practical application of aqueous Zn‐ion batteries (AZIBs) is severely limited by unstable Zn‐metal anodes caused by dendritic growth and parasitic interfacial reactions. Herein, we report an organic–inorganic hybrid protective layer composed of sulfonated poly(ether ether ketone) (SPEEK) and boron nitride nanosheets (BNNS), fabricated via a scalable and controllable spray‐coating process. The hybrid architecture synergistically integrates the mechanical robustness of BNNS with the ion‐regulating functionality of SPEEK, effectively addressing the trade‐off between interfacial rigidity and ionic transport. This structure promotes uniform Zn 2+ flux, suppresses dendrite growth, and stabilizes the Zn/electrolyte interface. Theoretical calculations, including density functional theory and nudged elastic band analysis, further reveal that SO 3 H groups in SPEEK lower the Zn 2+ adsorption energy and migration barriers, facilitating Zn 2+ transport across the protective layer. The hybrid protective layer enables long‐term stable Zn plating/stripping (>1800 h at 1 mA cm −2 , 1 mAh cm −2 ) and uniform, dendrite‐free deposition, as directly visualized by in situ optical microscopy. Consistent interfacial stabilization is further confirmed in Zn/MnO 2 full cells with improved rate capability and capacity retention. This work highlights a practical and rational interfacial design strategy for stabilizing Zn‐metal anodes toward durable AZIBs.