Efficient Suppression of Dendrites and Side Reactions by Strong Electrostatic Shielding Effect via the Additive of Rb 2 SO 4 for Anodes in Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) have attracted considerable attention due to their low cost and environmental friendliness. However, the rampant dendrite growth and severe side reactions during plating/stripping on the surface of zinc (Zn) anode hinder the practicability of AZIBs. Herein, an effective and non-toxic cationic electrolyte additive of Rb 2 SO 4 is proposed to address the issues. The large cation of Rb + is preferentially adsorbed on the surface of Zn metal to induce a strong shielding effect for realizing the lateral deposition of Zn 2+ ions along the Zn surface and isolating water from Zn metal to effectively inhibit side reactions. Consequently, the Zn||Zn symmetric cell with the addition of 1.5 mm Rb 2 SO 4 can cycle more than 6000 h at 0.5 mA cm -2 /0.25 mAh cm -2 , which is 20 times longer than that without Rb 2 SO 4 . Besides, the Zn||Cu asymmetric cell with Rb 2 SO 4 achieves a very high average Coulombic efficiency of 99.16% up to 500 cycles. Moreover, the electrolyte with Rb 2 SO 4 well matches with the VO 2 cathode, achieving high initial capacity of 412.7 mAh g -1 at 5 A g -1 and excellent cycling stability with a capacity retention of 71.6% at 5 A g -1 after 500 cycles for the Zn//VO 2 full cell.