Multiple Regulation of Electrolyte with Trace Amounts of Sodium Dehydroacetate Additives Enables High-Performance Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) draw much attention for low cost and high safety. However, hydrogen evolution reaction (HER) and uneven Zn 2+ deposition shorten lifespan, hampering commercial use. In this study, sodium dehydroacetate (SD) containing carbonyl and keto-carbonyl is introduced as multifunctional electrolyte additives, which effectively modifies the solvent shell structure, achieving a Zn 2+ transference number of up to 0.72. Acting as a hydrogen bond acceptor, SD disrupts the water network structure, thereby increasing the HER overpotential by 22 mV and the corrosion potential by 9 mV. The polar functional groups in SD can reversibly capture H⁺ ions and dynamically neutralize OH⁻ ions, maintaining interfacial pH balance on the zinc anode and suppressing HER. Notably, SD not only alters the electrolyte's kinetic but also induces uniform Zn 2+ deposition along the (002) plane, inhibiting dendrite growth and minimizing side reactions. This phenomenon is demonstrated in both symmetric and full-cell configurations. The Zn//Zn symmetric cell achieves an ultra-long cycling lifespan of 2800 hours at 5 mA cm⁻ 2 , and the Zn//VO 2 full battery maintains a capacity retention rate of 73.09% after 2000 cycles with a high average coulombic efficiency of 99.98%, underscoring the effectiveness of this electrolyte additive in enhancing battery performance.