Anti‐Swelling Supramolecule‐Crosslinked Hydrogel Interphase for Stable Zn Metal Anodes

Abstract Aqueous Zn metal batteries show promise for large‐scale energy storage but face challenges including dendrite formation, volume changes, and side reactions. This study introduces a novel anti‐swelling supramolecule‐crosslinked hydrogel (SCH) interphase to stabilize Zn metal anodes. The SCH, composed of cyclodextrin molecules crosslinked with polyvinyl alcohol, offers a multifaceted approach to enhance anode stability. It homogenizes ion flux and suppresses Zn dendrite growth by creating well‐defined pathways for Zn 2+ movement. The supramolecular structure selectively traps SO 4 2− ions, effectively desolvating Zn 2+ and enabling fast ion transportation. Additionally, by disrupting water cluster hydrogen bonds, SCH reduces free water activity, mitigating corrosion at the Zn surface. Electrochemical tests demonstrate the excellent performance of SCH‐Zn, with symmetric cells achieve lifespans of 1800 h at 4 mA cm −2 /2 mAh cm −2 and 1100 h at 10 mA cm −2 /5 mAh cm −2 . Zn||Cu half‐cells maintain 99.7% Coulombic efficiency over 500 cycles, while full cells with polyaniline cathodes exhibit stable cycling for 1500 cycles at 5 A g −1 with no apparent capacity decay. These results highlight the effectiveness of the SCH in stabilizing Zn anodes. This study provides a new interfacial engineering strategy for high‐performance aqueous Zn batteries, potentially accelerating their practical implementation in large‐scale energy storage.