2D Mesoporous Polydopamine Nanosheets Break the Strength–Conductivity Trade‐Off in Hydrogel Electrolytes Toward Stable Zn Anodes

ABSTRACT Hydrogel electrolytes are attractive for aqueous zinc‐ion batteries, but simultaneously achieving mechanical robustness, fast Zn 2+ transport, and interfacial stability remains challenging. Herein, we show that two‐dimensional mesoporous polydopamine nanosheets (2D‐mPDA) act as multifunctional polymeric nanofillers in a poly(vinyl alcohol)‐based hydrogel electrolyte for stabilizing Zn anodes. The polymer‐compatible 2D framework, in‐plane mesoporous ion‐transport channels, and catechol/amine‐rich surface chemistry endow the electrolyte with an ionic conductivity of 31.36 mS cm −1 , a tensile strength of 1.52 MPa, and a Zn 2+ transference number of 0.79, thereby overcoming the usual trade‐off between mechanical strength and ionic conductivity. Experiments and simulations reveal that 2D‐mPDA reconstructs the hydrogen‐bonding network, suppresses water activity, and remodels the primary solvation shell of Zn 2+ through catechol/amine coordination, which lowers the desolvation barrier, homogenizes Zn 2+ flux, and enables dense Zn deposition. As a result, Zn||Zn symmetric cells cycle stably for over 7200 h at 1 mA cm −2 , while Zn||VO 2 full cells retain 90.2% of their capacity after 1500 cycles at 1 A g −1 and remain operational under severe deformation. This work highlights the importance of nanofiller design in hydrogel electrolytes for stabilizing Zn anodes and advancing durable aqueous zinc‐ion batteries.