Achieving Fast Ionic Transport and High Mechanical Properties of Cellulose-Based Solid-State Electrolyte via a Cationic Chain-Extended Effect for Zinc Metal Batteries

In recent years, rechargeable aqueous zinc metal batteries have ushered in rapid development, but their large-scale industrial application is hindered by zinc anode dendrite formation and hydrogen evolution reaction. Using a solid-state polymer electrolyte is one of the strategies to solve this problem. Herein, by introducing the chain-expanding effect of zinc salts on oxidized bacterial cellulose, cellulose-based polymer electrolytes with excellent strength and ionic conductivity are prepared. According to the thermogravimetric calculations, the bound water content in prepared electrolytes greatly increases, which slows down the occurrence of side reactions. More importantly, the expanding distance between the fiber chains provides more space for the movement of Zn²⁺. The obtained solid-state electrolyte displays a high ionic conductivity (38.26 mS cm^-1) and good mechanical properties (tensile stress is 592 kPa and tensile strain is 381%). Due to the properties of the solid electrolyte itself, its electrochemical window is expanded to 2.58 V. The assembled Zn∥Zn symmetrical battery maintains an ultralong cycle lifespan over 980 h of 0.5 mA cm^-2. The Zn∥NH₄V₁₀O₁₀ battery provides the specific capacity (363.1 mAh g^-1 at 0.1 A g^-1) and shows a satisfactory rate performance.