A Lean‐Water Hydrogel Electrolyte with Engineered Water‐Lubricated Pathways Constructed by Unique Water‐Inter‐Micelle Structure

Hydrogel polymer electrolytes (HPEs) can mitigate leakage and suppress side reactions than liquid electrolytes in aqueous batteries. Nevertheless, their water content typically exceeds 80%, which perpetuates water-mediated side reactions. Characterized by a substantial reduction in water content, lean-water HPEs are designed. However, insufficient water severely impedes Zn²⁺ transport due to strong polymer-ion interactions. Herein, a lean-water hydrogel electrolyte with a unique water-inter-micelle structure to overcome this dilemma via engineering water pathways is designed. Minimal water induces zinc dodecylbenzenesulfonate self-assembly into micelles, confining water within micellar interstices. This structure enables rapid Zn²⁺ migration along water-lubricated interstices, achieving 15.3 mS cm^-1 conductivity at a water content of 20.6 wt.%. Subsequently, copolymerization of acrylamide (AM) and 4-acryloylmorpholine (ACMO) yielded a P(AM-ACMO) (PAC) lean-water hydrogel electrolyte. Compared with conventional HPEs, densely packed micelles within PAC create ordered slit channels that establish continuous water pathways using only trace amounts of water. This maximizes water utilization, suppresses side reactions, and endows PAC with high ionic conductivity (3.2 mS cm^-1) and Zn²⁺ transference number (0.88) at only 17.8 wt.% water content. In addition to high ionic conductivity and the ability to suppress dendrites, PAC also demonstrates exceptional adhesion and dehydration resistance, which contribute to its application in practical scenarios.