Efficient Suppression of Dendrites and Side Reactions by Strong Electrostatic Shielding Effect via the Additive of...

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 Rb₂ SO₄ 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 mm Rb₂ SO₄ 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 Rb₂ SO₄ . Besides, the Zn||Cu asymmetric cell with Rb₂ SO₄ achieves a very high average Coulombic efficiency of 99.16% up to 500 cycles. Moreover, the electrolyte with Rb₂ SO₄ 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.