Efficient Suppression of Dendrites and Side Reactions by Strong Electrostatic Shielding Effect via the Additive of Rb₂SO₄ for Anodes in Aqueous Zinc‐Ion Batteries

Abstract

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 Rb₂SO₄ 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 Zn²⁺ 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 m

Rb₂SO₄ 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 Rb₂SO₄. Besides, the Zn||Cu asymmetric cell with Rb₂SO₄ achieves a very high average Coulombic efficiency of 99.16% up to 500 cycles. Moreover, the electrolyte with Rb₂SO₄ well matches with the VO₂ 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//VO₂ full cell.