Reconstructing Electric Double Layer with β-diketone Additive for Highly Invertible Zn Anode

Aqueous Zn ion batteries (AZIBs) have emerged as a promising option for energy storage on a large scale. However, the unsteady electric double layer (EDL) that causes the continuous H₂O and SO₄²⁻ induced side reactions and byproducts, results in unstable anode electrolyte interphase (AEI) and restricts the practical application of AZIBs. A novel EDL reconstruction strategy is proposed by a prior adsorption process of the organic molecules, achieving steady AEI and uniform Zn deposition. Experimental results and theoretical calculations illustrate that the zinc acetylacetonate (Zn(C₅H₇O₂)₂, Zn(acac)₂) that conceives a pair of polar groups (─C═O) contributes to stability of AEI. As a result, the electrolyte with Zn(acac)₂ additive (ZnSO₄ + Zn(acac)₂, ZAH) realizes Zn//Zn cells a highly invertible plating/stripping performance over 2400 h with an average Coulombic efficiency of 99.55%. Moreover, the Zn//NH₄V₄O₁₀ pouch cells with ZAH electrolyte maintain an impressive capacity retention of 55.81% during 3000 cycles. These results spotlight the enormous potential of Zn(acac)₂ additive, providing promising feasibility on highly reversible Zn anodes.