Nanoengineered Functional Cellulose Ionic Conductor Toward High‐ Performance All‐Solid‐State Zinc‐Ion Battery

Abstract The rechargeable zinc‐ion battery is regarded as a promising candidate for the next‐generation energy storage system, however, zinc dendrite growth and hydrogen evolution reaction (HER) have greatly hindered the practical application of the battery. Herein, a functionalized, nano‐engineering Zn 2+ coordinated carboxylate cellulose solid‐state electrolyte (denoted as Zn‐CCNF@XG) for zinc‐ion battery is constructed through a straightforward approach. According to the experimental and density functional theory (DFT) results of dissociation energy, the notably decreased dissociation energy by −COOH is favorable to Zn 2+ de‐coordinating and rapid ion‐hopping in Zn‐CCNF@XG to achieve high ionic conductivity and transference number. More importantly, the engineered molecular channels are beneficial to enlarging the distance between the nanofibril chains, providing a larger space for the movement of Zn 2+ . Benefiting from the coordination of Zn 2+ with −OH in carboxylate cellulose nanofibrils, Zn‐CCNF@XG as a good ionic conductor displays a high ionic conductivity of 1.17 × 10 −4 S cm −1 and transference number of 0.78. The Zn||NaV 3 O 8 ·1.5H 2 O full cell with Zn‐CCNF@XG maintains a capacity retention of 83.46% with a coulombic efficiency of 99.99% after 3000 cycles (1 A g −1 ). The proposed strategy by introducing a functional group to cellulose nanofibrils effectively avoids the dendrite and HER, providing valuable guidelines for the practical application of zinc‐ion batteries.