Among post-lithium ion battery technologies, rechargeable chemistries with Zn anodes bear notable technological promise owing to their high theoretical energy density, lower manufacturing cost, availability of raw materials and inherent safety. However, Zn anodes, when employed in aqueous electrolytes, suffer from hydrogen evolution, passivation, and shape changes. Alternative electrolytes can help tackle these issues, preserving the green and safe characteristics of aqueous-based ones. Deep eutectic solvents (DESs) are promising green and low-cost non-aqueous solvents for battery electrolytes. Specifically, the cycling of Zn anodes in DESs is expected to be reversible, chiefly owing to their dendrite-suppression capability. Nevertheless, apart from a few studies on Zn plating, insight into the cathodic–anodic electrochemistry of Zn in DESs is still very limited. In view of developing DES-based battery electrolytes, it is crucial to consider that a potential drawback might be their low ionic conductivity. Water molecules can be added to the eutectic mixtures by up to 40% to increase the diffusion coefficient of the electroactive species and lower the electrolyte viscosity without destroying the eutectic nature. In this study, we address the electrochemistry of Zn in two different hydrated DESs (ChU and ChEG with ~30% H₂O). Fundamental electrokinetic and electrocrystallization studies based on cyclic voltammetry and chronoamperometry at different cathodic substrates are completed with a galvanostatic cycling test of Zn|Zn symmetric CR2032 coin cells, SEM imaging of electrodes and in situ SERS spectroscopy. This investigation concludes with the proposal of a specific DES/H₂O/ZnSO₄-based electrolyte that exhibits optimal functional performance, rationalized on the basis of fundamental electrochemical data, morphology evaluation and modeling of the cycling response.

The graphical abstract shows a schematic representation of Zn plating from a deep eutectic solvent with different hydration level pinpointing advantages and draw backs.

Zinc‐based batteries are emerging as promising alternatives to mainstream technologies due to their superior safety, cost‐effectiveness, and abundance of raw materials. However, zinc anodes, exhibit insufficient cycle life and low utilization in aqueous electrolytes, mainly owing to shape change and passivation. While nanostructuring of Zn anodes has been explored for Zn‐Ni rechargeable alkaline batteries, no explicit electrochemical studies have elucidated how nanostructures, fabricated in the oxidized state, are reduced during the initial formation step, yielding elemental Zn. In this work, a hydrothermal synthesis of freestanding electrodes is proposed, based on vertically aligned ZnO nanorods grown directly on carbon cloth (CC) ( ZnO/CC ). ZnO nanostructuring mitigates passivation, while the carbon cloth fiber network confines soluble Zn(II) intermediates, hindering diffusion into the electrolyte bulk. Moreover, the CC substrate provides optimal electronic contact to the active material, and acts as a built‐in current collector. This work investigates the evolution of ZnO/CC during the first electrochemical reduction cycle, with emphasis on morphochemical nanostructure changes rather than establishing a benchmark anode. Electrochemical measurements are combined with advanced characterization techniques, high‐resolution transmission electron microscopy (HRTEM), and X‐ray absorption hyperspectral imaging via scanning transmission X‐ray microscopy (STXM) and ptychography at the Zn L‐edge. This multimodal approach offers unprecedented insights into the ZnO‐to‐Zn reduction to guide future Zn‐ion anode design.

Recycling of hardmetal scrap is strategic for critical raw materials recovery. Available recycling processes are polluting and have a large carbon footprint. Attempts to exploit controlled corrosion failed in industrial practice, owing to self-limiting processes. We revisit the corrosion route, in view of gaining the fundamental knowledge enabling high-throughput recovery. We selected the worst-case approach of highly corrosion-resistant CoNiWC-based hardmetal grades and neutral aqueous electrolyte at room temperature. Systematic electrochemical measurements, UV–Vis spectroscopy and SEM microscopy disclosed that, even though there is no hope to overcome the self-limiting corrosion rate, nevertheless, by exploiting the mechanical action of anodic O₂ evolution acting precisely at the interface between the residual active material and the corrosion film, the latter can be efficiently removed, periodically reactivating the hardmetal corrosion in a way that results in an ultra-high scrap destruction rate, of interest for real-life industrial processes.

Zinc-based batteries are considered a promising alternative for sustainable energy storage due to their low cost and environmental benefits. However, challenges such as dendrite formation, passivation, and zincate migration hinder their performance and long-term stability. In this study, we address these issues by developing anion-selective poly­(vinylbenzyltrimethylammonium chloride) membranes via cathodic electropolymerization to modify zinc anode. These films were designed to confine zincate ions and reduce passivation and shape change during cycling while preventing self-discharge and avoiding the contact between metallic Zn and active water. Under extremely harsh testing conditions (closed cell, small amount of electrolyte), the Zn anode is modified with electropolymerized polymer and shows significantly improved performance compared to bare Zn foil. The highly rechargeable Zn anode reported is an important step toward practical Zn secondary aqueous batteries. This work proposes an improved, water-based strategy for zinc anode modification with electropolymerized anion-exchange films that improves the performance in alkaline electrolytes, as demonstrated by fundamental electrochemical tests and cycling of Zn–Ni batteries.

Exposure of LIB materials to ambient conditions with some level of humidity, either accidentally owing to imperfect fabrication or cell damage, or deliberately due to battery opening operations for analytical or recycling purposes, is a rather common event. As far as humidity-induced damage is concerned, on the one hand the general chemistry is well known, but on the other hand, concrete structural details of these processes have received limited explicit attention. The present study contributes to this field with an investigation centered on the use of Raman spectroscopy for the assessment of structural modifications using common lithium iron phosphate (LFP) and nickel–cobalt–manganese/lithium–manganese oxide (NCM-LMO) cathodes. The impact of humidity has been followed through the observation of differences in Raman bands of pristine and humidity-exposed cathode materials. Vibrational spectroscopy has been complemented with morphological (SEM), chemical (EDS), and electrochemical analyses. We have thus pinpointed the characteristic morphological and compositional changes corresponding to corrosion and active material dissolution. Electrochemical tests with cathodes reassembled in coin cells allowed for the association of specific capacity losses with humidity damaging.