Achieving Structural-Functional Synergy in Biomass Hydrogel Electrolytes for Dendrite-Free Flexible Zinc-Ion Batteries

The proliferation of flexible electronics demands energy storage devices that are inherently safe, mechanically compliant, and environmentally sustainable. Quasi-solid-state electrolytes are critical for flexible aqueous zinc-ion batteries, yet existing systems rarely integrate biomass sustainability with the requisite electrochemical stability and mechanical resilience. Here, we propose a structural-functional integration strategy to fabricate a fully biomass-based cellulose/hyaluronic acid composite hydrogel electrolyte via a green, one-step dissolution-regeneration process. In this design, hyaluronic acid serves as a multifunctional component: from a structural perspective, its flexible chains disrupt cellulose crystallinity to enhance mechanical compliance; from a functional perspective, its abundant polar groups (–COOH, –CONH–) coordinate Zn 2+ to regulate ion transport and nucleation while confining water molecules to suppress interfacial side reactions. This structural-functional synergy endows the optimized hydrogel with high ionic conductivity (29.5 mS·cm -1 ), excellent mechanical toughness (91 kJ·m -3 ), and superior interfacial stability. Consequently, Zn||Zn symmetric cells exhibit stable plating/stripping for over 8,000 h, while Zn||V 2 O 5 full cells retain 79.6% capacity after 10,000 cycles at 1 A·g -1 . Furthermore, flexible batteries maintain stable operation under mechanical deformation with capacity retention exceeding 92%. This work establishes the structural-functional integration principle as a generalizable design paradigm for high-performance, sustainable flexible zinc-ion batteries.