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

Abstract 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 H 2 O and SO 4 2− 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(C 5 H 7 O 2 ) 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 (ZnSO 4 + 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//NH 4 V 4 O 10 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.