Wood-based electrodes enabling stable, anti-freezing, and flexible aqueous zinc-ion batteries

As the treasure on the earth, forest resources should be utilized in a high value-added and efficient way. Herein, a wood-based quasi-solid-state aqueous zinc ion battery (AZIB) is developed to address the issues of AZIBs, i.e., low Zn stripping/plating reversibility and poor tolerance to low-temperature environments. Particularly, the anode is fabricated by ultraviolet light irradiation-assisted delignification of wood veneer and subsequent decoration of metallic Ni and Zn. This wood-based electrode exhibits large electrical conductivity, good affinity to aqueous electrolyte, high tensile strength, and can combine the advantages of unique structure and cellulose framework from wood. It is found that this electrode can considerably restrict two-dimensional diffusion of Zn2+ ions, facilitate desolvation process, improve Zn deposition kinetics, and inhibit Zn metal corrosion, thereby significantly stabilizing Zn deposition behavior. Thanks to that, the Zn//Zn cell with wood-based electrodes can deliver a long lifespan of 900 h at 2 mA cm−2 and 2 mAh cm−2. Besides, wood-derived current collector and nanocellulose are used to construct cathode and hydrogel electrolyte, respectively. The assembled wood-based AZIB delivers superior performances even at −20 °C and under bending. The strategy in this work could be extended in other flexible energy storage systems.