Unraveling the Solvation Structure and Electrolyte Interface through Carbonyl Chemistry for Durable and Dendrite-Free Zn Anode

Aqueous Zn ion batteries are appealing systems owing to their safety, low cost, and environmental friendliness; however, their practical applicability is impeded by the growth of Zn dendrites and side reactions. Herein, a dual-functional electrolyte additive, namely acetylacetone (AT) is utilized for the simultaneous regulation of the solventized structure and anode–electrolyte interface (AEI) to achieve a durable, dendrite-free Zn anode. Theoretical calculations and experimental characterizations reveal that the AT molecule can be adsorbed onto Zn metal surface to reconstruct the AEI and allow for the primordial desolvation of [Zn(H₂O)₆]²⁺ at locations away from the surface of the Zn anode during deposition, which is attributed to the strong polarity of the carbonyl functional group. In addition, the two carbonyls of AT can replace two H₂O molecules in the primary solventized structure of Zn²⁺ to reduce the number of active H₂O molecules, efficiently suppressing Zn dendrite growth and detrimental reactions. As a proof of concept, a Zn//Cu cell is constructed in ZnSO₄ containing 3 vol.% AT electrolyte, delivering stable cycling over 1800 cycles while maintaining a high Coulombic efficiency of 99.74%. This study provides a practical approach for inhibiting dendrite growth and side reactions by harnessing carbonyl chemistry.