Multi-protection of zinc anode via employing a natural additive in aqueous zinc ion batteries

Dendrite growth and by-products seriously worsen the operating environment of aqueous zinc ion batteries (AZIBs). In view of these problems, we report a natural multifunctional additive, gum arabic (GA), to optimize ZnSO4 electrolyte system for achieving longer plating/stripping process of AZIBs. The strong combination between Zn2+ and polar functional groups of GA can weaken the solvation of Zn2+ with water, thus inhibiting the decomposition of water. In addition, hydroxyl groups extend the hydrogen bond network of the electrolyte, further limiting the activity of water molecules. Meanwhile, aldehyde groups can consume the hydrogen generated to purify the electrolyte environment. It is mainly reflected in smaller exchange current density, wider electrochemical window and dendritic-free Zn metal interface. Under the action of GA, the Zn//Zn symmetric battery achieved 3600 h of stable operation (2.5 mA cm−2, 0.5 mAh cm−2) and the Zn//Cu asymmetric battery achieved up to 500 cycles with average 99.1% coulombic efficiency (0.5 mA cm−2, 0.5 mAh cm−2). In addition, Zn//V2O5 full battery also displays a superior capacity retention and rate performance, far surpassing that using pure ZnSO4 electrolyte.