We explored the potential of aqueous zinc metal batteries (AZMB) while addressing the challenges that impede their practical development, including issues such as hydrogen evolution reaction (HER), zinc substrate corrosion, and dendrite growth. We showcased the utilization of in situ electrochemical mass spectrometry (ECMS) to precisely quantify hydrogen evolution during the process of zinc electrodeposition. This approach offers insights into the relationship between HER and the morphology of the electrodeposited zinc, shedding light on its impact on the long-term performance of batteries.

       Furthermore, we introduced a thoughtfully designed organic additive, tetraalkylsulfonamide (TAS) additive designed to actively suppress both HER and dendrite formation, thereby enhancing the overall cyclability of the battery system. Through a series of experimental methodologies, including 67Zn and 1H nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry (HRMS), and density functional theory (DFT) studies, the mechanism underlying the effectiveness of TAS is elucidated. Specifically, we show the potency of TAS to displace water molecules from the solvation shell of Zn2+ ions, thereby altering the solvation matrix and disrupting the hydrogen bond network of free water.

       We further confirmed the effectiveness of TAS in suppressing HER and dendritic growth through voltammetry synchronized with in situ monitoring of the electrode surface. We employed ECMS to capture real-time data on HER suppression during zinc electrodeposition, revealing a significant reduction in HER activity in the presence of TAS. This suppression of passivation product formation, coupled with the disruption of the solvation matrix, led to a robust maximization of the stability of zinc metal anodes.

       Experimental results demonstrated a remarkable enhancement in battery cycle life, with a substantial improvement from approximately 100 hours to over 2500 hours in coin cells cycled in the presence of TAS. These findings underscored the potential of TAS as a key additive in the development of AZMBs, offering a promising avenue for addressing the challenges associated with HER, dendrite formation, and electrode passivation, thereby advancing the practical viability of aqueous zinc-based battery technologies.