Ordered Hierarchical Hydrogel Electrolyte for Long‐Life Zinc‐Ion Batteries

Hydrogel electrolytes show significant promise for mitigating critical issues of Zn anodes, yet reconciling ionic conductivity with mechanical strength remains challenging. To resolve this trade-off, an ordered hierarchical hydrogel electrolyte (OHHE) is engineered by inducing the directional alignment of bacterial cellulose (BC) nanofibers. The ordered channels for fast Zn²⁺ migration result in a high ionic conductivity (36.19 mS cm^-1) and Zn²⁺ transference number (0.75), facilitating homogenization of Zn²⁺ flux. Furthermore, a hierarchical interfibrous interface integrating nanofiber interlocking and enhanced hydrogen-bond network bridging achieves mechanical reinforcement through energy dissipation (a tensile strength of 27.35 MPa, Young's modulus of 127.81 MPa, and toughness of 5.60 MJ m^-3) to physically suppress dendrite penetration. Concurrently, this dense hydrogen-bond network firmly immobilizes free water at the Zn-OHHE interface, thereby suppressing side reactions. Benefiting from this triple-synergy mechanism, Zn//Zn symmetric cells deliver stable cycling for over 1600 h at 3 mA cm^-2/3 mAh cm^-2 and over 1400 h at a depth-of-discharge of 42%. Additionally, full cells with NaV₃O₈·1.5H₂O cathodes exhibit 82.47% capacity retention even after 3800 cycles at 5 A g^-1. This tailored structural design offers novel insights for realizing high-performance and long-life aqueous zinc-ion batteries.