Metal anode instability, including dendrite growth, metal corrosion, and hetero-ions interference, occurring at the electrolyte/electrode interface of aqueous batteries, are among the most critical issues hindering their widespread use in energy storage. Herein, a universal strategy is proposed to overcome the anode instability issues by rationally designing alloyed materials, using Zn-M alloys as model systems (M = Mn and other transition metals). An in-situ optical visualization coupled with finite element analysis is utilized to mimic actual electrochemical environments analogous to the actual aqueous batteries and analyze the complex electrochemical behaviors. The Zn-Mn alloy anodes achieved stability over thousands of cycles even under harsh electrochemical conditions, including testing in seawater-based aqueous electrolytes and using a high current density of 80 mA cm−2. The proposed design strategy and the in-situ visualization protocol for the observation of dendrite growth set up a new milestone in developing durable electrodes for aqueous batteries and beyond.

Aqueous zinc-ion batteries, in terms of integration with high safety, environmental benignity, and low cost, have attracted much attention for powering electronic devices and storage systems. However, the interface instability issues at the Zn anode caused by detrimental side reactions such as dendrite growth, hydrogen evolution, and metal corrosion at the solid (anode)/liquid (electrolyte) interface impede their practical applications in the fields requiring long-term performance persistence. Despite the rapid progress in suppressing the side reactions at the materials interface, the mechanism of ion storage and dendrite formation in practical aqueous zinc-ion batteries with dual-cation aqueous electrolytes is still unclear. Herein, we design an interface material consisting of forest-like three-dimensional zinc-copper alloy with engineered surfaces to explore the Zn plating/stripping mode in dual-cation electrolytes. The three-dimensional nanostructured surface of zinc-copper alloy is demonstrated to be in favor of effectively regulating the reaction kinetics of Zn plating/stripping processes. The developed interface materials suppress the dendrite growth on the anode surface towards high-performance persistent aqueous zinc-ion batteries in the aqueous electrolytes containing single and dual cations. This work remarkably enhances the fundamental understanding of dual-cation intercalation chemistry in aqueous electrochemical systems and provides a guide for exploring high-performance aqueous zinc-ion batteries and beyond.

The quality of solid-electrolyte-interphase (SEI) dictates the performances of most battery chemistries, especially lithium (Li)-metal, but its formation processes as well as evolution during battery operation remain little understood due to the lack of reliable in-operando characterization tools of sufficient spatial and temporal resolutions. Herein, we report an in-operando reflection interference microscope (RIM) that enables the real-time imaging of SEI during formation and evolution in state-of-the-art electrolyte based on LiPF6 dissolved in organic carbonates. By mapping the minimal and localized optical signals generated from interphasial events, RIM reveals with extremely high sensitivity that the stratified structure of SEI formed during four distinct steps, including the emergence of a permanent inner inorganic layer enriched in LiF, the transient assembly of an interfacial structure of an electrified double layer, and the consequent emergence of a temporary outer organic-rich layer, whose presence is reversible with electrochemical cycling. Comparing the morphologies of SEIs, we identify an inverse correlation between the thicknesses of two interphasial sub-components: the thicker the LiF-rich inner layer, the thinner the organic-rich outer layer, implying that the permanent inorganic-rich inner layer dictates the organic-rich outer layer formation and Li nucleation. We also find that trace presence of water (50 ppm) in the electrolyte induces a much thicker and higher quality LiF-rich layer and a much thinner organic-rich layer in SEI, which leads to less electrolyte consumption, and more uniform Li nucleation on the electrode surface. The real-time visualization of SEI dynamics achieved for the first time in this work provides a guideline for the rational design of interphases, a battery component that has been the least understood and most challenging barrier to developing electrolytes for future batteries.

A deep learning network called “residual neural network” (ResNet) was used to decode Raman spectra-encoded suspension arrays (SAs).

Uncontrollable dendrite growth is closely related to non‐uniform reaction environments. However, there is a lack of understanding and analysis methods to probe the localized electrochemical environment (LEE). Here the effects of the LEE are investigated, including localized ion concentrations, current density, and electric potential, on metal plating/stripping dynamics and dendrite minimization. A novel in situ 3D microscopy technique is developed to image the morphology dynamics and deposition rate of Zn plating/stripping processes on 3D Zn–Mn anodes. Using the in situ 3D microscope, the electrode morphology changes during the reactions are directly imaged and Zn deposition rate maps at different time points are obtained. It is found that reaction kinetics are highly correlated to LEE and electrode morphology. To further quantify the LEE effects, the digital twin technique is employed that allows the accurate calculation of the electrochemical environments, such as localized ion concentrations, current density, and electric potential, which cannot be directly measured from experiments. It is found that the curvature of the 3D electrode surface determines the LEE and significantly influences reaction kinetics. This provides a new strategy to minimize the dendrite formation by designing and optimizing the 3D geometry of the electrode to control the LEE.