Enabling highly stable quasi-solid-state zinc ion battery by a dual-network wood-based hydrogel electrolyte

Aqueous zinc-ion batteries have received much attention due to its low-cost, high safety and environmental-friendliness, however, the zinc anode is suffered from water-induced parasitic reactions and zinc dendrites. Herein, a wood-based hydrogel electrolyte is developed to reduce the water activity and guide the zinc ions deposition, which is mainly attributed to the formed dual-network between the polyacrylamide chain and the oriented wood fibers. The obtained hydrogel electrolyte exhibits a high ionic conductivity (10.9 mS·cm −1 ) with an outstanding tensile strength of 250 kPa. By taking advantages of these unique characteristics, the assembled Zn symmetric battery shows stable cycling lifespan for 2000 h at the current density of 1 mA·cm −2 with a fixed capacity of 1 mAh·cm −2 . Even at a high current density of 5 mA·cm −2 , the symmetric battery still works stably for over 400 h. Moreover, the Zn//Cu asymmetric battery with the hydrogel electrolyte delivers a high average Coulombic Efficiency of 98.7% for over 200 cycles. Besides, the full battery with the hydrogel electrolyte exhibits a long cycling lifespan of 1000 cycles at 4 A·g −1 , further confirming its functions of stabilizing zinc anode. This design of the dual-network structure in the wood-based hydrogel electrolyte provides an innovative approach for developing high-performance and dendrite-free quasi-solid-state zinc ion battery.