A Water-Lean Double-Network Gel Electrolyte Enabling Highly Reversible Zinc Anodes in Aqueous Zinc-Ion Batteries

Aqueous zinc batteries are promising for safe and durable energy storage, but sluggish Zn2+ transport and unstable Zn interfaces limit their cycling performance. Reducing the water content of hydrogel electrolytes can mitigate parasitic reactions, yet preserving ionic conduction remains challenging. Here, we report a water-lean double-network gel electrolyte (DNGE) formed by in situ polymerization of acrylamide within a bacterial cellulose (BC) scaffold in ZnSO4 solution. The resulting BC/polyacrylamide (PAM) architecture combines a water content of 20.5 wt% with an ionic conductivity of 11.72 mS cm−1. Electrochemical measurements and characterization of cycled electrodes indicate reduced polarization, more uniform Zn deposition and less accumulation of crystalline byproducts. With DNGE, Zn||Zn symmetric cells sustain plating and stripping for ~1300 h at 0.5 mA cm−2 and 0.5 mAh cm−2. Zn|I2 full cells deliver ~150 mAh g−1 after 7580 cycles at 10 C. The corresponding pouch cells deliver 169 mAh g−1 after 100 cycles and power a toy car. The BC/PAM architecture therefore enables reduced water content while preserving efficient ion transport and stable Zn electrochemistry.