Molecular Structure Regulation Elicits Steric Hindrance of Ketone Additives with High Adsorbability for Oriented Deposition of Zn Anode

The uncontrollable dendritic growth and interfacial parasitic reactions severely hinder the large-scale operation of aqueous zinc-ion batteries (AZIBs), root in the fundamental kinetics imbalance between the excessively rapid electrochemical reduction rate and retarded bulk mass transfer. To resolve this dilemma, a rationally structure-designed ketone additive, butane-2,3-dione (BD), was screened from a series of counterparts to achieve highly reversible Zn plating/stripping by moderating electroreduction kinetics. Specifically, the BD molecule preferentially adsorbs in the inner Helmholtz plane to repel solvated Zn-ions via the steric-hindrance effect. The modulated electroreduction kinetics alters zinc deposition behavior, guiding directional Zn (002) texture. Moreover, the constructed H₂O-poor electric double layer mitigates parasitic reactions. Notably, the rebalancing of interfacial consumption rate and ion diffusion rate endows Zn anode with superb reversibility (average 99.7% during 1825 cycles) and great cycling durability (2827 h at 1 mA cm⁻² and 1276 h at 5 mA cm⁻²). The outstanding electrochemical performance of Zn anode under harsh conditions (423 h, 50 mA cm⁻² and 50 mAh cm⁻², 76% depth of discharge) and assembled full cells coupled with multifarious cathodes (Zn//δ-MnO₂ and Zn//NaV₃O₈·1.5H₂O) further highlights the versatility of the steric-hindrance additive in AZIBs.