Molecular Engineering of Hybrid Electrolytes for Aqueous Zinc Ion Batteries

Abstract Aqueous zinc‐ion batteries (AZIBs) offer compelling advantages owing to their inherent safety, cost‐effectiveness, and the exceptional electrochemical properties of the Zn metal anode. However, achieving highly reversible Zn (de)plating remains a formidable challenge. In this study, a molecularly engineered hybrid electrolyte is systematically investigated to modulate the Zn 2+ solvation environment and enhance the interfacial stability. A modified phosphate‐based co‐solvent, diethyl(difluoromethyl)phosphonate (DEDFP) is developed by substituting an ethoxy moiety in triethyl phosphate (TEP) with a difluoromethyl group. This fine‐tunes the de‐solvation kinetics, induces a favorable passivation layer, and further minimizes water‐based side reactions. Compared to the TEP‐based hybrid electrolyte, the DEDFP‐based electrolyte promotes laterally uniform Zn growth to achieve an unprecedented Coulombic efficiency of 99.96%. In a Zn|V 6 O 13 full‐cell with a practical N/P ratio of 1.7, this electrolyte demonstrates exceptional cycling stability by retaining 70.06% of its capacity over 486 cycles and sustaining operation beyond 700 cycles—far exceeding the stability of the TEP‐based system, which fails after 381 cycles. This study highlights the pivotal role of molecular engineering in co‐solvent design and provides a strategic framework for advancing hybrid electrolyte systems in AZIBs.