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Aqueous zinc‐metal batteries (AZMBs) represent a promising frontier in battery technology, offering sustainable and safe alternatives to traditional non‐aqueous batteries. Despite their potential, understanding the kinetics of zinc electrodeposition—a critical factor in AZMB performance—remains underexplored. Utilizing voltammetry on ultramicroelectrodes, we investigate how scan rate influences key processes of nucleation and growth during Zn2+ electrodeposition. The findings highlight the efficacy of the Butler‐Volmer formulation in capturing electron‐transfer kinetics, contrasting with complex electron transfer kinetic models used for non‐aqueous battery chemistries. We clearly demonstrate that there is a strong dependence of scan rate on the measured value of kinetic parameters (exchange current). To accurately probe the charge transfer kinetics, it is essential to apply fast scan voltammetry to decouple the influence of mass transfer, ensuring that the measured current is independent of the scan rate. Furthermore, by studying a model electrolyte additive, the intricate balance between charge transfer and mass transfer dynamics is unveiled, and this information is crucial for enhancing the stability of zinc metal anodes. These insights pave the way for developing advanced electrolyte and current collector formulations, promising enhanced cyclability and sustainability in zinc metal batteries. [ABSTRACT FROM AUTHOR]

The extraordinary chemistry of microdroplets has reshaped how we as a community think about reactivity near multiphase boundaries. Even though interesting physico-chemical properties of microdroplets have been reported, "sessile" droplets' inherent mobility, which has been implicated as a driving force for curious chemistry, has not been well established. This paper seeks to answer the question: Can adsorbed microdroplets be mobile at the nanoscale? This is a tantalizing question, as almost no measurement technique has the spatiotemporal resolution to answer it. Here, we demonstrate a highly sensitive technique to detect nanometric motions of insulating bodies adsorbed to electrified microinterfaces. We place an organic droplet atop a microelectrode and track its dissolution by driving a heterogeneous reaction in the aqueous continuous phase. As the droplet's contact radius approaches the size of the microelectrode, the current versus time curve remarkably displays abrupt changes in current. We used finite element modeling to demonstrate these abrupt steps are due to nanometric movements of the three-phase boundary, where the nonaqueous droplet meets the aqueous phase and the electrode. Furthermore, the velocity with which the liquid interface moves can be estimated to tens-to-hundreds of nanometers per second. Our results indicate that processes that are driven by contact electrification and the frictional movement of bodies on a surface may be at play even when a droplet seems quiescent. [ABSTRACT FROM AUTHOR]

The commercialization of zinc metal batteries (ZMBs) for large‐scale energy storage is hindered by challenges such as dendrite formation, the hydrogen evolution reaction (HER), and passivation/corrosion, which lead to poor stability of zinc metal anodes. HER is a primary contributor to this instability, and despite efforts to enhance ZMB cyclability, a significant knowledge gap remains regarding the origin of HER in these systems. Prior works, based primarily on theoretical calculations with minimal experimental support, suggest that HER originates from Zn2⁺‐solvated water. For the first time, by employing scanning electrochemical microscopy (SECM), and electrochemical mass spectrometry (ECMS), in real‐time the inherently intertwined nature of Zn electrodeposition and H₂ liberation is revealed, both exhibiting the same onset potential in voltammetry. The findings show that water molecules surrounding Zn2⁺ ions undergo reduction simultaneously during Zn2⁺ deposition. Additionally, ECMS conducted under chronopotentiometric/galvanostatic conditions at battery‐relevant current densities elucidates why elevated electrolyte concentrations enhance the prolonged cyclability of ZMBs. Understanding the origin of HER opens avenues for developing high‐performance, reliable aqueous ZMBs, addressing key challenges in their commercialization and advancing their technological capabilities. [ABSTRACT FROM AUTHOR]

The ability of analytical strategies to detect and positively identify molecules under extremely dilute conditions is important for the growth and expansion of analytical techniques and instrumentation. At present, few measurement science techniques can robustly approach the measurement of just a few thousand molecules. Here, we present an electrochemical platform for the detection and positive identification of fewer than 1000 molecules of decamethylferrocene ((Cp*)2FeII). We achieve this remarkable detection threshold by trapping (Cp*)2FeII in a 1,2-dichloroethane microdroplet, which is allowed to dissolve into an aqueous continuous phase while on a gold microelectrode (radius ∼6.25 μm). Because electrochemistry is not sensitive enough to observe the charge of less than 1000 molecules, we dissolved μM amounts hexacyanoferrate(III) in the aqueous continuous phase. The biphasic reaction between hexacyanoferrate(III) and Cp2*(Fe)II allows for a feedback loop when the microelectrode is biased sufficiently negative to reduce Cp2*(Fe)III. This feedback loop, a typical EC′ catalytic mechanism, amplifies the electrochemical signal of Cp2*(Fe)II when the droplet is of small enough dimensions for feedback to occur. Our results demonstrate that clever biphasic reactions can be coupled with dissolving microdroplets to access extremely low limits of quantitation in electroanalysis. [ABSTRACT FROM AUTHOR]

Droplet evaporation and dissolution phenomena are pervasive in both natural and artificial systems, playing crucial roles in various applications. Understanding the intricate processes involved in the evaporation and dissolution of sessile droplets is of paramount importance for applications such as inkjet printing, surface coating, and nanoparticle deposition, etc. In this study, we present a demonstration of electrochemical investigation of the dissolution behaviour in sub-nL droplets down to sub-pL volume. Droplets on an electrode have been studied for decades in the field of electrochemistry to understand the phase transfer of ions at the oil–water interface, accelerated reaction rates in microdroplets, etc. However, the impact of microdroplet dissolution on the redox activity of confined molecules within the droplet has not been explored previously. As a proof-of-principle, we examine the dissolution kinetics of 1,2-dichloroethane droplets (DCE) spiked with 155 μM decamethylferrocene within an aqueous phase on an ultramicroelectrode (r = 6.3 μm). The aqueous phase serves as an infinite sink, enabling the dissolution of DCE droplets while also facilitating convenient electrical contact with the reference/counter electrode (Ag/AgCl 1 M KCl). Through comprehensive voltammetric analysis, we unravel the impact of droplet dissolution on electrochemical response as the droplet reaches minuscule volumes. We validate our experimental findings by finite element modelling, which shows deviations from the experimental results as the droplet accesses negligible volumes, suggesting the presence of complex dissolution modes. [ABSTRACT FROM AUTHOR]

Aqueous zinc metal batteries (AZMB) are emerging as a promising alternative to the prevailing existing Lithium‐ion battery technology. However, the development of AZMBs is hindered due to challenges including dendrite formation, hydrogen evolution reaction (HER), and ZnO passivation on the anode. Here, a tetraalkylsulfonamide (TAS) additive for suppressing HER, dendrite formation, and enhancing cyclability is rationally designed. Only 1 mm TAS is found that can effectively displace water molecules from the Zn2+ solvation shell, thereby altering the solvation matrix of Zn2+ and disrupting the hydrogen bond network of free water, as demonstrated through 67 Zn and 1H nuclear magnetic resonance spectroscopy, high‐resolution mass spectrometry (HRMS), and density functional theory (DFT) studies. Voltammetry synchronized with in situ monitoring of the electrode surface reveals suppressed dendritic growth and HER in the presence of TAS. Electrochemical mass spectrometry (ECMS) captures real‐time HER suppression during Zn electrodeposition, revealing the ability of TAS to suppress the HER by an order of magnitude. A ≈25‐fold cycle life improvement from ≈100 h to over 2500 h in coin cells cycled in the presence of TAS. Furthermore, by suppressing passivation product formation, it is demonstrated that strategy robustly maximizes the stability of Zn metal anodes. [ABSTRACT FROM AUTHOR]

Advancing next-generation battery technologies requires a thorough understanding of the intricate phenomena occurring at anodic interfaces. This focused review explores key interfacial processes, examining their thermodynamics and consequences in ion transport and charge transfer kinetics. It begins with a discussion on the formation of the electro chemical double layer, based on the GuoyChapman model, and explores how charge carriers achieve equilibrium at the interface. This review then delves into essential interfacial processes, including metal nucleation and growth, the development and stability of the solid electrolyte interphase (SEI), and ion movement across the interface. In addition, it analyzes the impact of different electrolyte solutions-such as low- and high-concentration electrolytes and localized high-concentration electrolytes-on these interfacial processes. The role of additives, co-solvents, and diluents in modifying these interfaces is also covered. This review further evaluates techniques for characterizing the SEI layer, highlighting their strengths and limitations in both aqueous and nonaqueous battery systems. By comparing the challenges and opportunities associated with interfaces next-generation nonaqueous metal battery systems, this review aims to offer new insights into their respective advantages and limitations, ultimately guiding the design and optimization of anodic interfaces to enhance the safety and efficiency of future energy storage technologies., (© 2025 Wiley‐VCH GmbH.)