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The conductivity of strong electrolytes increases under high electric fields, a nonlinear response known as the first Wien effect. Here, using molecular dynamics simulations, we show that this increase is almost suppressed in moderately concentrated aqueous electrolytes due to the alignment of the water molecules by the electric field. As a consequence of this alignment, the permittivity of water decreases and becomes anisotropic, an effect that can be measured in simulations and reproduced by a model of water molecules as dipoles. We incorporate the resulting anisotropic interactions between the ions into a stochastic density field theory and calculate ionic correlations as well as corrections to the Nernst–Einstein conductivity, which are in qualitative agreement with the numerical simulations. [ABSTRACT FROM AUTHOR]

This paper presents a mean field theory of electrolyte solutions, extending the classical Debye–Hückel–Onsager theory to provide a detailed description of the electrical conductivity in strong electrolyte solutions. The theory systematically incorporates the effects of ion specificity, such as steric interactions, hydration of ions, and their spatial charge distributions, into the mean-field framework. This allows for the calculation of ion mobility and electrical conductivity, while accounting for relaxation and hydrodynamic phenomena. At low concentrations, the model reproduces the well-known Kohlrausch's limiting law. Using the exponential (Slater-type) charge distribution function for solvated ions, we demonstrate that experimental data on the electrical conductivity of aqueous 1:1, 2:1, and 3:1 electrolyte solutions can be approximated over a broad concentration range by adjusting a single free parameter representing the spatial scale of the nonlocal ion charge distribution. Using the fitted value of this parameter at 298.15 K, we obtain good agreement with the available experimental data when calculating electrical conductivity across different temperatures. We also analyze the effects of temperature and electrolyte concentration on the relaxation and electrophoretic contributions to total electrical conductivity, explaining the underlying physical mechanisms responsible for the observed behavior. [ABSTRACT FROM AUTHOR]

We establish the connection between the measured small angle x-ray scattering signal and the charge–charge correlations underlying Kirkwood transitions (KTs) in 1:1, 2:1, and 3:1 aqueous electrolytes. These measurements allow us to obtain underscreening lengths for bulk electrolytes independently verified by theory and simulations. Furthermore, we generalize the concept of KTs beyond those theoretically predicted for 1:1 electrolytes, which involves the inverse screening length, a0, and the inverse periodicity length, Q0. Above the KTs, we find a universal scaling of a 0 ∝ c − ζ / 3 and Q0 ∝ c1/3 for the studied electrolyte solutions, where ζ is the ionic strength factor. [ABSTRACT FROM AUTHOR]

We study microbubbles (MBs) in aqueous electrolyte solutions and show that increasing the salt concentration slows down the kinetics of MB dissolution. We modified the Epstein–Plesset theory and experimented with NaCl aqueous solutions to estimate the MB effective surface charge and to compare it with predictions from the modified Poisson–Boltzmann theory. Our results reveal a mechanism responsible for the change in the dissolution of MBs in aqueous electrolyte solutions, with implications for emerging fields ranging from physics of solutions to soft and biological matter. [ABSTRACT FROM AUTHOR]

The capacitive deionization technology uses the electrochemical adsorption of ions in porous electrodes to desalinate seawater or brackish water. Recently, capacitive deionization has gained significant attention as a technology for selective adsorption of ionic species from multicomponent aqueous electrolytes. To investigate the mechanism of selective adsorption at the molecular level, we performed molecular dynamics simulations of aqueous electrolytes and porous electrodes with different divalent or trivalent ions, electrode pore sizes, and applied voltages. We calculated the free energy barriers preventing ions from entering the pores of the electrode and the structure of the water molecules near the ions and the electrode surface under various conditions. Our results suggest that, when the pore and ion sizes are comparable, the steric and electrostatic interactions between the hydrated ions and electrode pores are comparable in magnitude. Moreover, the relative importance of the two interactions can be reversed by slight changes in the external conditions, such as the ion size, valence of the ions, electrode pore size, and applied voltage. Thus, by finely tuning the electrode pore size and the applied voltage, it may be possible to selectively adsorb a particular ionic species from a multicomponent electrolyte through capacitive deionization using a porous electrode. [ABSTRACT FROM AUTHOR]

Vapor–Liquid Equilibria (VLE) of hydrogen (H2) and aqueous electrolyte (KOH and NaCl) solutions are central to numerous industrial applications such as alkaline electrolysis and underground hydrogen storage. Continuous fractional component Monte Carlo simulations are performed to compute the VLE of H2 and aqueous electrolyte solutions at 298–423 K, 10–400 bar, 0–8 mol KOH/kg water, and 0–6 mol NaCl/kg water. The densities and activities of water in aqueous KOH and NaCl solutions are accurately modeled (within 2% deviation from experiments) using the non-polarizable Madrid-2019 Na+/Cl− ion force fields for NaCl and the Madrid-Transport K+ and Delft Force Field of OH− for KOH, combined with the TIP4P/2005 water force field. A free energy correction (independent of pressure, salt type, and salt molality) is applied to the computed infinite dilution excess chemical potentials of H2 and water, resulting in accurate predictions (within 5% of experiments) for the solubilities of H2 in water and the saturated vapor pressures of water for a temperature range of 298–363 K. The compositions of water and H2 are computed using an iterative scheme from the liquid phase excess chemical potentials and densities, in which the gas phase fugacities are computed using the GERG-2008 equation of state. For the first time, the VLE of H2 and aqueous KOH/NaCl systems are accurately captured with respect to experiments (i.e., for both the liquid and gas phase compositions) without compromising the liquid phase properties or performing any refitting of force fields. [ABSTRACT FROM AUTHOR]

A crucial aspect in the simulation of electrochemical interfaces consists in treating the distribution of electronic charge of electrode materials that are put in contact with an electrolyte solution. Recently, it has been shown how a machine-learning method that specifically targets the electronic charge density, also known as SALTED, can be used to predict the long-range response of metal electrodes in model electrochemical cells. In this work, we provide a full integration of SALTED with MetalWalls, a program for performing classical simulations of electrochemical systems. We do so by deriving a spherical harmonics extension of the Ewald summation method, which allows us to efficiently compute the electric field originated by the predicted electrode charge distribution. We show how to use this method to drive the molecular dynamics of an aqueous electrolyte solution under the quantum electric field of a gold electrode, which is matched to the accuracy of density-functional theory. Notably, we find that the resulting atomic forces present a small error of the order of 1 meV/Å, demonstrating the great effectiveness of adopting an electron-density path in predicting the electrostatics of the system. Upon running the data-driven dynamics over about 3 ns, we observe qualitative differences in the interfacial distribution of the electrolyte with respect to the results of a classical simulation. By greatly accelerating quantum-mechanics/molecular-mechanics approaches applied to electrochemical systems, our method opens the door to nanosecond timescales in the accurate atomistic description of the electrical double layer. [ABSTRACT FROM AUTHOR]

We determine the surface tension of aqueous electrolyte solutions in contact with non-polar dielectric media using a thermomechanical approach, which involves deriving the stress tensor from the thermodynamic potential of an inhomogeneous fluid. To obtain the surface tension, we calculate both the normal and tangential pressures using the components of the stress tensor, recently derived by us [Y. A. Budkov and P. E. Brandyshev, J. Chem. Phys. 159, 174103 (2023)] within the framework of Wang's variational field theory. Using this approach, we derive an analytical expression for the surface tension in the linear approximation. At low ionic concentrations, this expression represents the classical Onsager–Samaras limiting law. By utilizing only one fitting parameter, which is related to the affinity of anions to the dielectric boundary, we successfully approximated experimental data on the surface tension of several aqueous electrolyte solutions. This approximation applies to both the solution–air and solution–dodecane interfaces, covering a wide range of electrolyte concentrations. [ABSTRACT FROM AUTHOR]

The study of electrolytic solutions is of relevance in many research fields, ranging from biophysics, materials, and colloid science to catalysis and electrochemistry. The dependence of solution dynamics on the nature of electrolytes and their concentrations has been the subject of many experimental and computational studies, yet it remains challenging to obtain a full understanding of the factors that govern solution behavior. Here, we provide additional insights into the behavior of aqueous solutions of alkali chlorides by combining 17O relaxation data with diffusion and viscosity data and contrast their behavior with 1H nuclear magnetic resonance relaxation data. The main findings are that 17O relaxation correlates well with viscosity data but not with diffusion data, while 1H relaxation correlates with neither. Certain ionic trends match known ion-specific series behavior, especially at high concentrations. Notably, we also examine the ranges of the interactions and conclude that the majority of the effects are tied to local water reorientation dynamics. [ABSTRACT FROM AUTHOR]

Graphene-based applications, such as supercapacitors or capacitive deionization, take place in an aqueous environment, and they benefit from molecular-level insights into the behavior of aqueous electrolyte solutions in single-digit graphene nanopores with a size comparable to a few molecular diameters. Under single-digit graphene nanoconfinement (smallest dimension <2 nm), water and ions behave drastically different than in the bulk. Most aqueous electrolytes in the graphene-based applications as well as in nature contain a mix of electrolytes. We study several prototypical aqueous mixed alkali-chloride electrolytes containing an equimolar fraction of Li/Na, Li/K, or Na/K cations confined between neutral and positively or negatively charged parallel graphene sheets. The strong hydration shell of small Li+ vs a larger Na+ or large K+ with weaker or weak hydration shells affects the interplay between the ions's propensity to hydrate or dehydrate under the graphene nanoconfinement and the strength of the ion–graphene interactions mediated by confinement-induced layered water. We perform molecular dynamics simulations of the confined mixed-cation electrolytes using the effectively polarizable force field for electrolyte–graphene systems and focused on a relation between the electrochemical adsorption and structural properties of the water molecules and ions and their diffusion behavior. The simulations show that the one-layer nanoslits have the biggest impact on the ions' adsorption and the water and ions' diffusion. The positively charged one-layer nanoslits only allow for Cl− adsorption and strengthen the intermolecular bonding, which along with the ultrathin confinement substantially reduces the water and Cl− diffusion. In contrast, the negatively charged one-layer nanoslits only allow for adsorption of weakly hydrated Na+ or K+ and substantially break up the non-covalent bond network, which leads to the enhancement of the water and Na+ or K+ diffusion up to or even above the bulk diffusion. In wider nanoslits, cations adsorb closer to the graphene surfaces than Cl−'s with preferential adsorption of a weakly hydrated cation over a strongly hydrated cation. The positive graphene charge has an intuitive effect on the adsorption of weakly hydrated Na+'s or K+'s and Cl−'s and a counterintuitive effect on the adsorption of strongly hydrated Li+'s. On the other hand, the negative surface charge has an intuitive effect on the adsorption of both types of cations and only mild intuitive or counterintuitive effects on the Cl− adsorption. The diffusion of water molecules and ions confined in the wider nanoslits is reduced with respect to the bulk diffusion, more for the positive graphene charge, which strengthened the intermolecular bonding, and less for the negative surface charge, which weakened the non-covalent bond network. [ABSTRACT FROM AUTHOR]

Concentrated ionic aqueous electrolytes possess a diverse array of applications across various fields, particularly in the field of energy storage. Despite extensive examination, the intricate relationships and numerous physical mechanisms underpinning diverse phenomena remain incompletely understood. Molecular dynamics simulations are employed to probe the attributes of aqueous solutions containing LiCl, NaCl, KCl, MgCl2, and CaCl2, spanning various solute fractions. The primary emphasis of the simulations is on unraveling the intricate interplay between these attributes and the underlying physical mechanisms. The configurations of cation-Cl− and Cl−–Cl− pairs within these solutions are disclosed. As the solute fraction increases, consistent trends manifest regardless of solute type: (i) the number of hydrogen bonds formed by the hydration water surrounding ions decreases, primarily attributed to the growing presence of counter ions in proximity to the hydration water; (ii) the hydration number of ions exhibits varying trends influenced by multiple factor; and (iii) the diffusion of ions slows down, attributed to the enhanced confinement and rebound of cations and Cl− ions from the surrounding atoms, concurrently coupled with the changes in ion vibration modes. In our analysis, we have, for the first time, clarified the reasons behind the slowing down of the diffusion of the ions with increasing solute fraction. Our research contributes to a better understanding and manipulation of the attributes of ionic aqueous solutions and may help designing high-performance electrolytes. [ABSTRACT FROM AUTHOR]

The electrochemical conversion of CO2 into valuable chemicals is a promising route for renowable energy storage and the mitigation of greenhouse gas emission, and production of multicarbon (C2+) products is highly desired. Here, we report a 1.4 %Pd−Cu@CuPz2 comprising of dispersive CuOx and PdO dual nanoclusters embedded in the MOF CuPz2 (Pz=Pyrazole), which achieves a high C2+ Faradaic efficiency (FEC2+) of 81.9 % and C2+ alcohol FE of 47.5 % with remarkable stability when using 0.1 M KCl aqueous solution as electrolyte in a typical H‐cell. Particularly, the FE of alcohol is obviously improved on 1.4 %Pd−Cu@CuPz2 compared to Cu@CuPz2. Theoretical calculations have revealed that the enhanced interfacial electron transfer facilitates the adsorption of *CO intermediate and *CO−*CO dimerization on the Cu−Pd dual sites bridged by Cu nodes of CuPz2. Additionally, the oxophilicity of Pd can stabilize the key intermediate *CH2CHO and promote subsequent proton‐coupled electron transfer more efficiently, confirming that the formation pathway is skew towards *C2H5OH. Consequently, the Cu−Pd dual sites play a synergistic tandem role in cooperatively improving the selectivity of alcohol and accelerating reductive conversion of CO2 to C2+. [ABSTRACT FROM AUTHOR]

Combining different metals in coordination compounds is an efficient strategy to improve their various properties. Herein, mixed nickel–cobalt hexacyanoferrate (NixCoyHCF) microcubes of varying x : y molar ratios are synthesized via a co-precipitation route and comprehensively characterized to study their material and electrochemical properties. NixCoyHCF microcubes display the battery-type electrochemical energy storage mechanism in aqueous electrolytes. Among the samples, Ni1Co2HCF microcubes deliver the highest specific capacity of 134 mA h g−1 (1068 F g−1) at a specific current of 1 A g−1. This significant enhancement in the capacity indicates the synergistic and cooperative effects between Ni and Co sites in Ni1Co2HCF microcubes. The asymmetric supercapacitor device assembled with Ni1Co2HCF microcubes delivers an excellent energy density of 74.4 μW h cm−2 at a power density of 750 μW cm−2 and retains 87.7% of its initial capacity after 2000 cycles at a current density of 5 mA cm−2, indicating its robust structural integrity and electrochemical durability. This study highlights the promising potential of mixed-metal hexacyanoferrates as high-performance electrodes for aqueous supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] Amino acids are among the most commercially promising additive solutions for achieving stable zinc anodes. However, greater attention should be given to the limitation arising from the protonation effects induced by high isoelectric point amino acids in the weakly acidic electrolytes of aqueous zinc-ion batteries (AZIBs). In this study, we introduce histidine (HIS) and ethylenediaminetetraacetic acid (EDTA) as hybrid additives into the aqueous electrolyte. Protonated HIS is adsorbed onto the anode interface, inducing uniform deposition and excluding H 2 O from the inner Helmholtz plane (IHP). Furthermore, the addition of EDTA compensates for the limitation of protonated HIS in excluding solvated H 2 O. EDTA reconstructs the solvation structure of Zn2+, resulting in a denser zinc deposition morphology. The results demonstrate that the Zn||Zn battery achieved a cycling lifespan exceeding 1480 h at 5 mA cm−2 and 5 mAh cm−2. It also reached over 900 h of cycling at a zinc utilization rate of 70 %. This study provides an innovative perspective for advancing the further development of AZIBs. [ABSTRACT FROM AUTHOR]

Formation of C−N bonds through the electrochemical utilization of CO2 and nitrogen containing compounds (N‐compounds) is appealing for the purpose of converting waste and readily available sources or pollutants into value added chemicals at ambient conditions. Existing research predominantly explores these electrochemical reactions independently, often in aqueous electrolytes, leading to challenges associated with competitive hydrogen evolution reaction (HER), low product selectivity, and yield. Functional electrolytes such as those containing ionic liquids (ILs) present selective solubility to the solute reactants and present unique interactions with the electrode surface that can suppress the undesired side reactions such as HER while simultaneously co‐catalyzing the conversion of CO2 and N‐compounds such as N2, NO, NO2, and NO3. In this concept paper, we discuss how the microenvironment enabled by ILs can be leveraged to stabilize reaction intermediates at the electrode‐electrolyte interface, thereby promoting C−N bond formation on an active electrode surface at reduced overpotential, with the case study of CO2 and N‐compounds co‐catalysis to generate urea. [ABSTRACT FROM AUTHOR]

Zn dendrite growth and parasitic reactions at the interface of zinc anode/electrolyte in aqueous zinc batteries severely hinder its lifespan in application. Herein, the zinc anode is effectively stabilized by introducing trace amounts of 4‐aminobutane‐1‐phosphate (ABPA) into the ZnSO4 electrolyte. The ABPA adsorbs onto the surface of zinc anode and then further decomposes to a high conductive organic/inorganic composite in situ SEI layer including amino, partial carbon chain, and zinc phosphate. In the SEI layer, the residual undecomposed carbon chain promotes the desolvation of Zn2+, the amino induces uniform Zn2+ plating and zinc phosphate facilitates the migration of Zn2+. Thus, this in situ SEI layer not only suppresses water‐related side reactions but also enhances the Zn2+ transport kinetics. As a result, Zn||Zn symmetric cell delivers an ultralong cycle life of over 13 000 cycles at 50 mA cm−2 and 1 mAh cm−2. A high average Coulombic efficiency of 99.72% is achieved in over 1000 cycles in Zn||Cu half‐cell. The Zn||I2 full cell delivers a high‐capacity retention of 91.42% after 40,000 cycles. Moreover, a 49 mAh Zn||I2 pouch cell maintains 80.28% capacity retention over 300 cycles and 61.22% after 1000 cycles. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (AZIBs) have become a promising energy storage device due to their low cost and high security. However, the severe dendrite growth and side reactions on metallic zinc (Zn) anode hamper their commercial implementation. Herein, a strongly electronegative trifluoroborate anion (─BF3−) functionalized polyacrylamide hydrogel (PAME) is well‐designed and constructed as the quasi‐solid‐state electrolyte to overcome these obstacles. The PAME chain segments terminated with strongly polar functional groups promote the conversion of water molecules from free water to bound water through the enhanced hydrogen bonding interaction to alleviate the side reactions. Furthermore, the PAME electrolyte featured with hierarchically porous structure and enhanced electrostatic interaction among the ─BF3− groups, and Zn2+ ions homogenizes the high‐flux Zn ion transport and induce the uniform deposition to restrain dendrite growth. Consequently, the assembled Zn‖PAME‖Zn batteries deliver remarkable cycling stability over 1800 h at 1 mA cm−2 and 900 h at 15 mA cm−2. Additionally, the constructed Zn‖PAME‖MnO2 full cells achieve a reversible capacity of 202 mAh g−1 at 2.0 A g−1 with a capacity retention rate of 91.4% over 500 cycles. This work sheds light on constructing the strongly polar hydrogel electrolyte to boost free‐dendrite Zn anodes for long‐lifespan AZIBs. [ABSTRACT FROM AUTHOR]

Regulating the electrical double layer (EDL) structure can enhance the cycling stability of Zn metal anodes, however, the effectiveness of this strategy is significantly limited by individual additives. Inspired by the high‐entropy (HE) concept, we developed a multicomponent (MC) EDL structure composed of La3+, Cl−, and BBI anions by adding dibenzenesulfonimide (BBI) and LaCl3 additives into ZnSO4 electrolytes (BBI/LaCl3/ZnSO4). Specifically, La3+ ions accumulate within EDL to shield the net charges on the Zn surface, allowing more BBI anions and Cl− ions to enter this region. Consequently, this unique MC EDL enables Zn anodes to simultaneously achieve uniform electric field, robust SEI layer, and balanced reaction kinetics. Moreover, the synergistic parameter – a novel descriptor for quantifying collaborative improvement – was first proposed to demonstrates the synergistic effect between BBI and LaCl3 additives. Benefitting from these advantages, Zn metal anodes achieved a high reversibility of 99.5 % at a depth of discharge (DoD) of 51.3 %, and Zn|MnO2 pouch cells exhibited a stable cycle life of 100 cycles at a low N/P ratio of 2.9. [ABSTRACT FROM AUTHOR]

Exploring cathode materials with excellent electrochemical performance is crucial for developing rechargeable aqueous zinc ion batteries (RAZIBs). Zinc hexacyanoferrate (ZnHCF), a promising candidate of cathode materials for RAZIBs, suffers from severe electrochemical instability issues. This work reports using low contents of alkaline metal cations as electrolyte additives to improve the cycle performance of ZnHCF. The cations with large sizes, particularly Cs+, changes the intercalation chemistry of ZnHCF in RAZIBs. During cycling, Cs+ cations co‐inserted into ZnHCF stabilize the host structure. Meanwhile, a stable phase of CsZn[Fe(CN)6] forms on the ZnHCF cathode, suppressing the loss of active materials through dissolution. ZnHCF gradually converts to an electrochemically inert Zn‐rich phase during long‐term cycling in aqueous electrolyte, leading to irreversible capacity loss. Introducing Cs+ in the electrolyte inhibits this conversion reaction, resulting in the extended lifespan. Owing to these advantages, the capacity retention rate of ZnHCF/Zn full batteries increases from the original 7.0 % to a high value of 54.6 % in the electrolyte containing 0.03 M of Cs2SO4 after 300 cycles at 0.25 A ⋅ g−1. This research provides an in‐depth understanding of the electrochemical behavior of ZnHCF in aqueous zinc electrolyte, beneficial for further optimizing ZnHCF and other metal hexacyanoferrates. [ABSTRACT FROM AUTHOR]

Non‐aqueous organic redox flow batteries (RFB) utilizing verdazyl radicals are increasingly explored as energy storage technology. Verdazyl cations in RFBs with acidic aqueous electrolytes, however, have not been investigated yet. To advance the application in aqueous RFBs it is crucial to examine the interaction with the utilized membranes. Herein, the interactions between the 1,3,5‐triphenylverdazyl cation and commercial Nafion 211 and self‐casted polybenzimidazole (PBI) membranes are systematically investigated to improve the performance in RFBs. The impact of polymer backbones is studied by using mPBI and OPBI as well as different pre‐treatments with KOH and H3PO4. Nafion 211 shows substantial absorption of the 1,3,5‐triphenylverdazylium cation resulting in loss of conductivity. In contrast, mPBI and OPBI are chemically stable against the verdazylium cation without noticeable absorption. Pre‐treatment with KOH leads to a significant increase in ionic conductivity as well as low absorption and permeation of the verdazylium cation. Symmetrical RFB cell tests on lab‐scale highlight the beneficial impact of PBI membranes in terms of capacity retention and I‐V curves over Nafion 211. With only 2 % d−1 capacity fading 1,3,5‐triphenylverdazyl cations in acidic electrolytes with low‐cost PBI based membranes exhibit a higher cycling stability compared to state‐of‐the‐art batteries using verdazyl derivatives in non‐aqueous electrolytes. [ABSTRACT FROM AUTHOR]

Rechargeable zinc‐ion batteries are considered an ideal energy storage system due to their low cost and nonflammable aqueous electrolyte. However, dendrite growth, hydrogen evolution reaction, and self‐corrosion of zinc anode brought about serious safety risks including short circuits and electrode expansion. Therefore, a modified host‐design strategy with a 3D porous structure and bulk‐phase penetrated zincophilic interface is proposed to boost the stability and lifetime of the Zn anode. The porous Zn substrate is constructed by universal HCl etching and the uniform and tight Sn‐penetrated zincophilic interface is formed by effective electron beam evaporation (EBE). The porous substrate can uniform zinc ion flux and the Sn coating could effectively improve zinc ion deposition behavior, thus inhibiting the risk of dendrites growth and side reaction. As a result, the 3D Zn substrate with Sn interface (3D Zn@Sn) exhibits prolonged galvanostatic cycling performance up to 4500 h with a low polarization of ≈25 mV (1 mA cm−2, 1 mAh cm−2) in the symmetric cell. The full cell assembled with KVOH@Ti could maintain a high specific capacity of 148.6 mAh g−1 after 500 galvanostatic cycles (10 A g−1). This work proposed an improved electrode design to realize the high performance of zinc ion batteries. [ABSTRACT FROM AUTHOR]

Manganous‐manganic oxide (Mn3O4), akin to other manganese‐based oxides, faces several critical challenges such as substantial capacity fading and limited rate performance due to its inferior electrical conductivity, in addition to the inevitable dissociation of Mn2+. To address these issues, we introduce for the first time a novel carbon‐coated Mn3O4/Na2CO3 (Mn3O4/Na2CO3/C) composite material. Comprehensive characterizations indicate that Na2CO3 effectively curtails Mn2+dissolution, enhances carbon encapsulation throughout charging/discharging cycles, and exposes additional active sites on the Mn3O4/Na2CO3/C composite. Electrochemical assessments confirm that the Mn3O4/Na2CO3/C‐2 cathode exhibits exceptional electrochemical performance, outperforming other cathodes in the ZnSO4 system. Moreover, the Mn3O4/Na2CO3/C‐2 cathode delivers a high specific capacity of ~550 mAh gM−1 at 0.1 A g−1 and maintains a significant capacity of ~230 mAh g−1 after 360 cycles at 1.0 A g−1 within the 2.0 M ZnSO4+0.2 M MnSO4 electrolyte system, demonstrating its potential as a high‐performance cathode material for aqueous zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

The energy storage capability of supercapacitors (SCs) strongly depend on the operating cell voltage of the electrolytes of choice. In this regard, the inherent distinct electrochemical stability of cations and anions is a factor of relevance for the operating cell voltage. The use of double salts sharing one ion has been described as an approach to circumvent this problem, but whether modifying the solvation structure of cations and anions with different solvent molecules (coordinating and/or non‐coordinating) could help balance their electrochemical stability in SCs has not yet been fully addressed. In this work, electrolytes are prepared by combining solvent mixtures and double salts, specifically 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) and 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIMBF4) in mixtures of water (H2O) and dimethysulfoxide (DMSO) as coordinating co‐solvents and acetonitrile (CH3CN) as a weakly coordinating one. It is found that the presence of this latter one helped to enhanced the cation solvation structure (above 9). This increase of the entropic features allows operating at cell voltages of up to 2.2 V and the subsequent enhancement of the energy storage capabilities and capacitance retentions (up to 15 Wh kg−1 and ≈87% after 10 000 cycles, respectively). [ABSTRACT FROM AUTHOR]

Designing multiple redox sites in electroactive organic cathodes that allow more electron transfer is a permanent target for energy storage. Here, six‐electron zinc–organic batteries are reported accessed by duodecuple H‐bonded NH4+ storage in N‐heterocyclic dipyrazino[2,3‐f:2′,3′‐h]quinoxaline‐2,3,6,7,10,11‐hexacarbonitrile (DQH) cathode. DQH features an extended π‐conjugated aromatic planarity enriched with super electron delocalization routes and dodecahedral‐active imine/cyano motifs, achieving a high capacity up to 385 mAh g−1 at 0.5 A g−1. Besides, DQH cathode redox‐exclusively couples with small‐hydration‐size and low‐desolvation‐energy‐barrier NH4+ ions (0.33 nm and 0.19 eV vs 0.86 nm and 0.36 eV of Zn2+) via flexible H‐bonding interactions. NH4+ topo‐coordination enables DQH anti‐dissolution in aqueous electrolytes to avoid common capacity decay of small organic molecules, and solves the instability and low interfacial reaction kinetics issues caused by rigidly and sluggishly repeated insertion of Zn2+ ions. This gives zinc–organic battery high‐rate ability (30 A g−1) and high lifespan (30 000 cycles at 10 A g−1). [ABSTRACT FROM AUTHOR]

Electrochemical energy storage is one of the effective ways that can address the mentioned issues as alternative energy/power produced through solar or windmills can effectively be stored for continuous usage. Hybrid/Asymmetric supercapacitors can deliver a significant amount of power density as well as increased energy density with better rate capability and longer lifespan. The fluffy carbonized hexagonal KCoPO4 synthesized via a simple sol‐gel method accompanied by calcination has delivered high capacitance and longer cyclibility as a positive electrode in aqueous asymmetric supercapacitors. The fluffy carbonized hexagonal KCoPO4 exhibited a specific capacitance equal to 725 F/g at 0.5 A/g current density with excellent cyclic stability. The predominant intercalative pseudocapacitive charge storage behavior seems to be the reason behind the high capacitance of the electrode due to the active involvement of Co2+/3+ redox couple mediate charge storage as intercalative (inner) and capacitive, (outer) surface charges storage on the electrode were close to 37 % and 63 % respectively. Aqueous Asymmetric supercapacitor mode with KCoPO4 being a positive electrode and activated carbon being a negative electrode (KCoPO4//AC) was designed to address its performance in 2 M KOH aqueous electrolyte. The fabricated device in AASc mode (AC//KCoPO4) achieved the highest energy density close to 121.1 Wh/kg with a high power density of 6945 W/kg in the potential window of 1.5 V in 2 M KOH electrolyte. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) are of great interest owing to their potential applications in bioelectronics and neuromorphic systems. However, n‐type OECTs suffer from poor stability and facile degradation, mainly due to the oxygen reduction reactions in organic mixed ionic‐electronic conductors during device operation. In this study, a small‐molecule passivation strategy is introduced to greatly improve the stability of poly(benzobisimidazobenzophenanthroline) (BBL)‐based n‐type OECTs. 6,6‐Phenyl‐C61‐butyric acid methyl ester (PCBM) is spin‐coated onto the BBL layer to form a smooth and hydrophobic passivation layer, which effectively inhibits the oxygen reduction reactions while enabling ion permeation in aqueous electrolytes. Consequently, the OECTs employing the PCBM/BBL bilayers with an optimized PCBM thickness exhibit significantly improved operational stability at various electrolyte conditions (0.1 m NaCl or NaOH) and over a wide gate‐voltage sweep range (from −0.7 to 0.7 V). Owing to the high electron mobility of PCBM, the carrier mobility and switching speed of the PCBM/BBL OECTs are also improved compared with those of the pristine BBL OECTs. This study demonstrates the beneficial effects of simple surface passivation in organic mixed ionic‐electronic conductors and provides valuable insights for the design of high‐performance and stable OECTs for more specialized and advanced applications. [ABSTRACT FROM AUTHOR]

Rechargeable and flexible aqueous batteries (ABs) have emerged as one of promising energy devices which is primarily due to the safety, environmental friendliness and economic efficiency. However, because of the freezing behavior of aqueous electrolytes, most ABs possess poor performance when the working temperature drops below zero. To solve this problem, a gel polymer electrolyte (GPE) with high ionic conductivity (IC) and frost‐resistance is designed for aqueous Zn−Li hybrid batteries by a biomass‐based polymers complex consisting of carboxyl modified sodium alginate (SA) and zwitterionic betaine (BA). Introducing iminodiacetic acid to enrich −COOH groups along the SA main chains could improve IC of the prepared GPEs to 41.27 and 20.96 mS cm−1 at 20 and −20 °C, respectively. At −20 °C, the discharge capacity of the resultant cell is two times higher than that of the liquid electrolyte‐based cell, and the cell presents a capacity retention of 91.6 % after 300 charge/discharge cycles at 1 C. This proposed strategy greatly improve the IC of GPEs at freezing temperature, which is expected to broaden the practical application of GPEs in wide range of temperature. [ABSTRACT FROM AUTHOR]

The molten‐salt synthesis and electrochemical capacitive behaviors of porous carbon are reported using anthracite as the precursor. Upon synthesis, the binary KCl/K2CO3 molten salt not only exfoliates bulky anthracite to carbon nanosheets but also creates rich micro‐ and mesopores in the structure. The resulting porous carbon shows a large surface area of 1399.7 m2 g−1 and a total pore volume of 1.50 cm3 g−1. In 6.0 mol L−1 KOH aqueous electrolyte, it delivers a high specific capacitance of 245.6 F g−1 at a current density of 0.5 A g−1. Flexible micro‐supercapacitors with this porous carbon are assembled following an interdigitated design. The micro‐supercapacitor affords an area capacitance of 18.0 mF cm−2 and an energy density of 1.58 µWh cm−2 at a power density of 20 µW cm−2, and sustains 89.6% of the capacitance after 2000 cycles. Furthermore, the strain sensor fabricated by replacing the current‐collecting fluid at both ends of the electrode provides consistent and stable signal output, regardless of the degree of bending and the number of cycles. This study demonstrates the great potential of anthracite‐based porous carbon in flexible energy and electronic microdevices. [ABSTRACT FROM AUTHOR]

This research innovatively produced polyaniline-coated carbon cloth (PANI@CC) using an electrochemical deposition process, highlighting the impact of carbon cloth substrate characteristics on the performance of symmetric supercapacitors in a coin cell setup. The study compared the electrochemical performance of hydrophilic and hydrophobic, soft, and hard carbon cloth substrates through cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The PANI@0-N (hydrophilic soft carbon cloth) substrate showcased superior electrochemical properties, achieving a maximum specific capacitance of 113.3 F g−1 at a current density of 0.1 A g−1, with a noteworthy rate capability of 88.6%. After 2000 galvanostatic charge–discharge cycles at 1 A g−1, the developed symmetric coin cell supercapacitor retained 74% of its initial capacitance, demonstrating notable durability and efficiency. This underscores the significance of substrate selection in the direct synthesis approach for optimizing supercapacitor performance, making the PANI@0-N-based coin cell a promising option for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Oxide ceramic layers of Ti 5 Al 16 O 34 were fabricated on commercially pure titanium grade 2 substrates by plasma electrolytic oxidation in aqueous electrolyte media at a fixed 10 g/L concentration of trisodium phosphate and 25 g/L sodium aluminate. Lowering the sodium aluminate concentration to 15 g/L and 20 g/L, β-TiAl 2 O 5 and Ti 2 Al 6 O 13 components were produced under similar PEO processing conditions. The composition and structure of the PEO coatings were studied using XPS, XRD, SEM, EDS, mechanical (hardness, adhesion, and tribology), electrochemical impedance spectroscopy, and potentiodynamic polarization tests. The layers possess a polycrystalline character with minor amorphous phases, while their thicknesses varied slightly between samples with similar treatment times. The PEO coatings consist of a compact inner layer with an enriched phosphorus content of about 5–10 wt% and a porous outer layer in which phosphorus is found in less than 1 wt%. Ti 5 Al 16 O 34 coatings showed better mechanical performance regarding microhardness and corrosion resistance compared to β-TiAl 2 O 5 and Ti 2 Al 6 O 13. At a longer applied PEO process duration of 10 min, Ti 5 Al 16 O 34 layer thickness, microhardness, and corrosion current densities of 40.2 μm, 9.37 GPa, and 2.8 nA/cm2 were measured. [Display omitted] [ABSTRACT FROM AUTHOR]

Zinc metal stands out as a promising anode material due to its exceptional theoretical capacity, impressive energy density, and low redox potential. However, challenges such as zinc dendrite growth, anode corrosion, and side reactions in aqueous electrolytes significantly impede the practical application of zinc metal anodes. Herein, 3‐(1‐pyridinio)‐1‐propanesulfonate (PPS) is introduced as a zwitterionic additive to achieve long‐term and highly reversible Zn plating/stripping. Due to the orientation polarization with the force of electric field, PPS additive with π–π conjugated pyridinio cations and strong coordination ability of sulfonate anion tends to generate a dynamic adsorption layer and build a unique water–poor interface. PPS with steric hindrance effect and strong coordination ability can attract solvated Zn2+, thereby promoting the desolvation process. Moreover, by providing a large number of nucleation sites and inducing zinc ion flow, the preferred orientation of the (002) crystal plane can be achieved. Therefore, the interfacial electrochemical reduction kinetics is regulated and uniform zinc deposition is ensured. Owing to these advantages, the Zn//Zn symmetrical cell with PPS additive exhibits remarkable cycling stability exceeding 2340 h (1 mA cm−2 and 1 mA h cm−2). The Zn//V2O5 full cell also delivers stable cycling for up to 6000 cycles. [ABSTRACT FROM AUTHOR]

The article delves into the synthesis and characterization of MoS2-carbon-based materials, holding promise for applications in supercapacitors and ion batteries. The synthesis process entails the preparation of MoS2 and its carbon hybrids through exfoliation, hydrothermal treatment, and subsequent pyrolysis. Various analytical techniques were employed to comprehensively examine the structural, compositional, and morphological properties of the resulting materials. The article explores the electrochemical performance of these electrode materials in supercapacitors and ion batteries (LiB, SiB, KiB). Electrochemical measurements were conducted in aqueous electrolyte for supercapacitors and various aprotic electrolytes for ion batteries. Results highlight the impact of the synthesis process on electrochemical performance, emphasizing factors such as capacitance, rate capability, and charge/discharge cycle performance. Hydrothermally treated MoS2-carbon exhibited a specific capacitance of approximately 150 F g-1 in supercapacitors, attributed to its high surface area and efficient charge storage mechanisms. Additionally, for Li-ion battery materials without hydrothermal treatment showed impressive capacity retention of around 88% after 500 charge-discharge cycles, starting with an initial specific capacity of about 920 mAh/g. Long-term stability was demonstrated in both supercapacitors and lithium-ion batteries, with minimal capacitance degradation even after extensive charge-discharge cycles. This research underscores the potential of MoS2-based materials as effective energy storage solutions. [ABSTRACT FROM AUTHOR]

Current artificial neuromorphic systems are mainly constructed using solid‐state optoelectronic synaptic devices, limiting their potential artificial intelligence applications in liquid medium. Here, colloidal CuInGaSe/ZnSe quantum dots (QDs) with environment‐benign feature and broad visible light absorption are prepared to fabricate a photoelectrochemical (PEC)‐type optoelectronic synaptic device operating in aqueous electrolyte, enabling unique biological synaptic behaviors including paired‐pulse facilitation (PPF), short‐term plasticity (STP), long‐term plasticity (LTP) and learning‐forgetting‐relearning process when simulated by optical pulses with various wavelength, pulse number, frequency, power density, and applied voltage. These results demonstrate the feasibility of building PEC‐type optoelectronic synapses using colloidal QDs, paving the way to realize available optoelectronic synaptic devices for prospective underwater artificial intelligence technology. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogenation of acetylene to ethylene in aqueous electrolytes under ambient conditions faces efficiency and selectivity limitation due to the competitive formation of 1,3‐butadiene and hydrogen. In this study, the development of a  copper nanoparticle/FeNC composite catalyst is reported through a simple mechanical grinding approach that demonstrates remarkable performance, achieving a highest ethylene Faradaic efficiency of 97.7% at 180 mA cm−2 and selectivity of 92.6% at 200 mA cm−2. Experimental investigations reveal that Cu atoms serve as the active sites, and the integration of FeNC improves the specific surface area through its 2D nanosheet morphology. Further analysis utilizing in situ Raman measurements coupled with theoretical calculations confirms that FeNC accelerates water dissociation to provide abundant protons and improving their transfer, thereby suppressing 1,3‐butadiene formation and elevating acetylene selectivity. Notably, the integration of FeNC also transforms the desorption of *C2H4 into an exothermic process, further facilitating ethylene production. Overall, this study introduces a simple and innovative preparation approach of composite catalysts for selective ethylene synthesis, expanding the application scope of Cu‐based FeNC materials in various electrocatalytic hydrogenation reactions. [ABSTRACT FROM AUTHOR]

A thiosemicarbazone‐based iron(III) complex is prepared and used in the preparation of a supercapacitor electrode material. This electrode is produced by a solvothermal reaction of polypyrrole and the complex on carbon felt. The characterization of the complex and material is carried out using UV‐vis, elemental analysis, FT‐IR, XRD, BET, and TGA methods, and the surface morphology is examined using SEM technique. Because the interaction of electrode and electrolyte is of great importance in energy storage systems, as the surface area and pore volume increase, electrode ions at the electrode/electrolyte interface leak to the inner surfaces and interact with the larger surface area, which increases the charge storage performance. The electrode material, nano‐worm structure, reached the highest specific capacitance value of 764.6 F g−1 at 5 mV s−1. Compared to the capacitance value of polypyrrole in its pure form, it is observed to exhibit an 187.2% increase. The highest specific capacitance value of the asymmetric supercapacitor (ASC) formed with a graphite electrode is 318.1 F g−1 at the current density of 1 Ag−1. Moreover, ASC reached a wide working potential of 1.8 V in an aqueous electrolyte and exhibited ultra‐long cycle life (112%), maintaining its stability after 10 000 cycles. [ABSTRACT FROM AUTHOR]

Tungsten oxides suffer from sluggish ion diffusion kinetics, limited ion storage capacity, and inadequate stability within the aqueous zinc ion electrolyte, thereby constraining their applicability in electrochromic energy storage devices (EESDs). Here, the amorphous hydrated tungsten oxide films with large optical modulation, fast response speed, large capacity, and high cycling stability are reported, enabled by tuning the contents of structural water and adjusting the pH value of aqueous zinc ion electrolyte. The enhancement of the electrochromic and ion storage performance is mainly due to the introduction of structural water which triggers pseudocapacitive behavior dominated by surface redox reaction, resulting in high electrochemical activity and fast electrochemical kinetics. Meanwhile, the relatively low pH value ensures the chemical stability of the hydrated tungsten oxide film, in synergy with surface redox that avoids ion trapping, leading to extraordinary cycling stability of up to 13000 cycles, marking the state‐of‐the‐art stability for tungsten oxide‐based materials in aqueous electrolyte. Based on the hydrated tungsten oxide films, high‐capacity and stable large‐size EESDs are constructed with the capability of visually monitoring energy status, recovering energy, and regulating light. This work provides a simple yet effective strategy for enhancing the performance of tungsten oxide‐based aqueous zinc ion EESDs. [ABSTRACT FROM AUTHOR]

Zinc‐ion capacitors (ZICs) are promising next‐generation energy storage systems (ESS) owing to high safety, material abundance, environmental friendliness, and low cost; however, the energy density of ZICs must be improved to compete with lithium‐ion batteries (LIBs). Here, the study implements three strategies to enhance the electrochemical performance and manage dendritic growth on Zn anodes, including crafting a highly efficient redox electroactive niobium pyrophosphate (NbP2O7)/Ti3C2TX‐MXene binder‐free cathode, incorporating a NaClO4 additive electrolyte, and applying a protective Ti3C2TX‐MXene layer on Zn anode. The cathode facilitates rapid Zn2+ ion diffusion and a stable host structure. An electrostatic protection layer formed in additive electrolyte and MXene layers regulates the uniform distribution of the electric fields and supports the equalization of nucleation sites. These results are supported by density functional theory (DFT) calculations. The ZICs display an excellent specific capacitance (113.3 F g−1 at 1.5 A g−1) in aqueous additive electrolytes. The flexible solid‐state ZICs exhibits a volumetric capacitance of 865.05 mF cm−3, and an energy density of 0.347 mWh cm−3 at 2.29 mW cm−3 along with capacitance retention of >100% over 38 000 charge‐discharge cycles. [ABSTRACT FROM AUTHOR]

Flexible and biodegradable electronics have emerged as a promising solution for escalating electronic waste issue caused by the rapid development of skin patch electronics. Fully biodegradable displays are essential for visualizing biological/physical/chemical/electrochemical signals measured by a wide range of skin patch electronics. Here we propose fully biodegradable electrochromic display providing low operating voltage and low power consumption. The biodegradable transparent conductive electrode was fabricated by transferring free-standing tungsten nanomesh onto poly lactic-co-glycolic acid substrate using electrospinning templating, minimizing damage to the substrate. Electrochromic layer was tungsten oxide which is biodegradable, and a ferrocyanide/ferricyanide redox agent was utilized as a counter electrode reaction to enhance operational stability in an aqueous electrolyte by reducing operating voltage and side reactions. This display successfully visualized diverse signals from various biodegradable electronics such as UV sensors and electrochemical transistors, and finally underwent eco-friendly degradation in phosphate-buffered saline or soil under mild conditions. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction reaction (CO2RR) to produce value‐added multi‐carbon chemicals has been an appealing approach to achieving environmentally friendly carbon neutrality in recent years. Despite extensive research focusing on the use of CO2 to produce high‐value chemicals like high‐energy‐density hydrocarbons, there have been few reports on the production of propane (C3H8), which requires carbon chain elongation and protonation. A rationally designed 0D/2D hybrid Cu2O anchored‐Ti3C2Tx MXene catalyst (Cu2O/MXene) is demonstrated with efficient CO2RR activity in an aqueous electrolyte to produce C3H8. As a result, a significantly high Faradaic efficiency (FE) of 3.3% is achieved for the synthesis of C3H8 via the CO2RR with Cu2O/MXene, which is ≈26 times higher than that of Cu/MXene prepared by the same hydrothermal process without NH4OH solution. Based on in‐situ attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR) and density functional theory (DFT) calculations, it is proposed that the significant electrocatalytic conversion originated from the synergistic behavior of the Cu2O nanoparticles, which bound the *C2 intermediates, and the MXene that bound the *CO coupling to the C3 intermediate. The results disclose that the rationally designed MXene‐based hybrid catalyst facilitates multi‐carbon coupling as well as protonation, thereby manipulating the CO2RR pathway. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable metal batteries have recently garnered considerable attention owing to their low cost, sufficient capacity, and the use of non‐flammable water‐based electrolytes. Among them, manganese batteries are particularly favored because of their stability, abundance, affordability, and high energy density. Despite their advantages, Mn storage host structures remain underexplored. Therefore, developing innovative host materials is crucial for advancing this field. In this paper, the study reports for the first time, the use of Ag0.33V2O5 as a cathode material in aqueous manganese batteries. The study explains the displacement/intercalation behavior of manganese and silver using electrochemical, structural, and spectroscopic analyses. Additionally, it is shown that cation (Ag+, Mn2+, H+) diffusion pathways can be simulated using diffusion‐barrier calculations. Finally, the study demonstrates high‐performance manganese batteries that exhibit a remarkable reversible capacity of ≈261.9 mAh g−1 at a current of 0.1 A g−1 and an excellent cycle retention of 69.1% after 2000 cycles at a current density of 1.5 A/g. The findings of this study contribute to the advancement of aqueous manganese battery technology, offering a promising pathway for developing safer, more cost‐effective, and high‐performance energy storage systems. [ABSTRACT FROM AUTHOR]

Water molecules confined in nanoscale spaces of 2D graphene layers have fascinated researchers worldwide for the past several years, especially in the context of energy storage applications. The water molecules exchanged along with ions during the electrochemical process can aid in wetting and stabilizing the layered materials resulting in an anomalous enhancement in the performance of supercapacitor electrodes. Engineering of 2D carbon electrode materials with various functionalities (oxygen (─O), fluorine (─F), nitrile (─C≡N), carboxylic (─COOH), carbonyl (─C═O), nitrogen (─N)) can alter the ion/water organization in graphene derivatives, and eventually their inherent ion storage ability. Thus, in the current study, a comparative set of functionalized graphene derivatives—fluorine‐doped cyanographene (G–F–CN), cyanographene (G–CN), graphene acid (G–COOH), oxidized graphene acid (G‐COOH (O)) and nitrogen superdoped graphene (G–N) is systematically evaluated toward charge storage in various aqueous‐based electrolyte systems. Differences in functionalization on graphene derivatives influence the electrochemical properties, and the real‐time mass exchange during the electrochemical process is monitored by electrochemical quartz crystal microbalance (EQCM). Electrogravimetric assessment revealed that oxidized 2D acid derivatives (G–COOH (O)) are shown to exhibit high ion storage performance along with maximum water transfer during the electrochemical process. The complex understanding of the processes gained during supercapacitor electrode charging in aqueous electrolytes paves the way toward the rational utilization of graphene derivatives in forefront energy storage applications. [ABSTRACT FROM AUTHOR]

Molybdenum trioxide (MoO3) is a promising positive electrode material for aqueous aluminum‐ion batteries (AAIBs) due to its high theoretical capacity. However, MoO3 faces several challenges in an aqueous electrolyte, such as easy dissolution of reaction products, volume expansion, and low conductivity, which severely limit its application in aqueous batteries. In this work, we effectively increased the overall conductivity of the electrode by in situ growing MoO3 on the Mo2C MXene layer. MXene can effectively inhibit the dissolution and structural loss of MoO3 reaction products. Additionally, the coordination effect of Mo2C and MoO3 achieves a stable near‐surface reaction on the MXene laminates, resulting in the Mo2C/MoO3 composite exhibiting excellent aluminum storage properties (123.5 mAh/g after 200 cycles at 0.4 A/g). The energy storage mechanism of H+/Al3+ co‐insertion/extraction was elucidated through ex situ characterization, and the promotion effect of Mo2C on MoO3 reaction kinetics was verified by density functional theory (DFT) calculations. This work provides new insights into improving the stability of AAIBs cathodes and extends the application of Mo‐based MXene in aqueous batteries. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries (AZIBs) are considered one of the most prospective new‐generation electrochemical energy storage devices with the advantages of high specific capacity, good safety, and high economic efficiency. Nevertheless, the enduring problems of low Coulombic efficiency (CE) and inadequate cycling stability of zinc anodes, originating from dendrites, hydrogen precipitation and passivation, are closely tied to their thermodynamic instability in aqueous electrolytes, which significantly shortens the cycle life of the battery. Electrolyte additives can solve the above difficulties and are important for the advancement of affordable and reliable AZIBs. Organic electrolyte additives have attracted widespread attention due to their unique properties, however, there is a lack of systematic discussion on the performance and mechanism of action of organic electrolyte additives. In this review, a comprehensive overview of the application of organic electrolyte additives in AZIBs is presented. The role of organic electrolyte additives in stabilizing zinc anodes is described and evaluated. Finally, further potential directions and prospects for improving and directing organic electrolyte additives for AZIBs are presented. [ABSTRACT FROM AUTHOR]

Organic polymer materials have attracted much attention in rechargeable aqueous magnesium ion batteries (AMIBs) due to their sustainability and structural designability. However, the ionic storage capability is hindered by their insufficient redox‐active sites, dissolvability in aqueous electrolytes, and short‐range conjugated structures, resulting in low energy density and poor cycling stability. Herein, a sulfur‐heterocyclic aromatic polyimide‐based organic polymer (PTDBS) is constructed with multiple redox‐active sites and long‐range conjugate, which is employed as active material for AMIB anode, achieving an outstanding Mg2+ storage capability. Benefitting from the introduced thioether bonds, PTDBS possesses an enhanced electronic conductivity and additional redox‐active sites for reversible Mg2+ coordination, thus ensuring high redox activity and superior electron affinity. As a result, the PTDBS electrode delivers ultrafast and stable Mg2+ storage in an MgCl2 aqueous electrolyte with a superior rate capacity of 98.6 mA h g−1 at 10.0 A g−1, and remarkable cycling stability over 7500 cycles with a capacity retention rate of 90.0%. Notably, the all‐organic aqueous full cell, realized by coupling the PTDBS anode and the polyindole cathode, achieves a high energy density and long lifespan. This work lays the foundation for the development of highly stable all‐organic electrode materials for large‐scale aqueous energy storage. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) have garnered significant attention in the realm of large-scale and sustainable energy storage, primarily owing to their high safety, low cost, and eco-friendliness. Aqueous electrolytes, serving as an indispensable constituent, exert a direct influence on the electrochemical performance and longevity of AZIBs. Nonetheless, conventional aqueous electrolytes often encounter formidable challenges in AZIB applications, such as the limited electrochemical stability window and the zinc dendrite growth. In response to these hurdles, a series of advanced aqueous electrolytes have been proposed, such as "water-in-salt" electrolytes, aqueous eutectic electrolytes, molecular crowding electrolytes, and hydrogel electrolytes. This comprehensive review commences by presenting an in-depth overview of the fundamental compositions, principles, and distinctive characteristics of various advanced aqueous electrolytes for AZIBs. Subsequently, we systematically scrutinizes the recent research progress achieved with these advanced aqueous electrolytes. Furthermore, we summarizes the challenges and bottlenecks associated with these advanced aqueous electrolytes, along with offering recommendations. Based on the optimization of advanced aqueous electrolytes, this review outlines future directions and potential strategies for the development of high-performance AZIBs. This review is anticipated to provide valuable insights into the development of advanced electrolyte systems for the next generation of stable and sustainable multi-valent secondary batteries. [ABSTRACT FROM AUTHOR]

Aqueous aluminum‐ion batteries present a promising prospect for large‐scale energy storage applications, owing to the abundance, inherent safety, and the high theoretical capacity of aluminum. However, their voltage output and energy density are significantly hindered by challenges such as complex hydrogen evolution and uncontrollable solvation reactions. In this work, we demonstrate that water decomposition is restrain by increasing the electron density of water protons and increasing the dissociation energy of H2O through robust dipole interactions with highly polar dimethylformamide (DMF) molecules. Moreover, the incorporation of dimethyl methylphosphonate (DMMP) flame retardant effectively addresses the flammability risk arising from a substantial presence of organic additives The in‐depth study with experimental and theoretical simulations reveals that the water‐poor solvation structure with reduced water activity is achieved, which can (i) effectively mitigate undesired solvated H2O‐mediated side reactions on the Al anode; (ii) boost the de‐solvation kinetics of Al3+ while preventing cathode structural distortion; (iii) reduce the flammability of hybrid electrolytes. As a proof of concept, the Al//AlxMnO2 full cell employing a hybrid electrolyte demonstrate enhanced stability (deliver 335 mAh g−1 while retaining 71 % capacity for 400 cycles) compared to those with pure electrolyte. [ABSTRACT FROM AUTHOR]

For a reliable evaluation of the electrocatalytic ammonia oxidation reaction (EAOR), we revised the standard electrode potentials in both aqueous and nonaqueous electrolytes using the solvation energies of ammonia. Moreover, we developed an improved assessment protocol for EAOR systems, particularly for those employing nonaqueous electrolytes and/or nitrogen-containing materials. [ABSTRACT FROM AUTHOR]

Aqueous batteries employing Zinc metal anodes (ZMAs) are considered to be promising next‐generation energy storage systems. However, the severe interfacial side reactions and dendrite growth restrict the practical application of ZMAs in aqueous electrolytes. Herein, a water‐insoluble dual‐ionic electrolyte additive of yttrium 2,4,5‐trifluorophenylacetate (YTFPAA) is developed to stabilize the aqueous ZMAs. Notably, the ethanol‐solvated TFPAA− can capture H+ and thus buffer the decreased electrolyte pH caused by the hydrolysis of Y3+. Furthermore, the ethanol‐solvated TFPAA− can dynamically adsorb onto the surface of ZMAs through a reversible oxidation‐reduction reaction, effectively suppressing the interfacial side reactions by forming a water‐poor interface, and enhancing the reversibility of Zn2+ deposition/stripping by redistributing the Zn2+ flux. These favorable effects of TFPAA− combined with the dynamic electrostatic shielding effect of Y3+ ultimately enable uniform and dense Zn2+ deposition. As a result, the Zn/Zn cells assembled with 0.25YTFPAA electrolyte exhibit an impressive cycle life of 2100 h at 0.5 mA cm−2–0.25 mAh cm−2. More importantly, the assembled V2O5/Zn full cell shows an ultra‐long cycle life of up to 18000 cycles at 5.0 A g−1. This work highlights the rational design of multifunctional ionic additives for stabilizing aqueous ZMAs. [ABSTRACT FROM AUTHOR]

Designing next‐generation alternative energy storage devices that feature high safety, low cost, and long operation lifespan is of the utmost importance for future wide range of applications. Aqueous zinc‐ion batteries play a vital part in promoting the development of portability, sustainability, and diversification of rechargeable battery systems. Based on the theory of electrolyte solvation chemistry, deep understanding of interaction between electrolyte components and their impact on the chemical properties has achieved a series of research progress. Analyzing the solvation shell of electrolyte or structure–performance relationship, and establishing more stable and high‐energy battery chemistries are inevitable requirements to suppress the electrolyte–electrode interphase side reaction and realize the functional use of zinc‐ion batteries. In this critical review, the attempt is to overview the current comprehension regarding the electrolyte solvation structure in zinc battery technology. Advanced methodology toward the interactions between zinc cations, solvent molecules, and anions in zinc aqueous electrolytes and the general rules for electrolyte design from the atomic level are summarized. Methods for viable solvation modification are then introduced regarding overcoming the remained challenges for transferring the laboratory results to next‐generation practical applications. Possible research direction with the aim of investigating the ultimate choice for future high‐performance electrolyte solvation construction is also outlined. [ABSTRACT FROM AUTHOR]

Aqueous ammonium‐ion batteries (AAIBs) are considered as one of the most promising technologies for large scale energy storage applications, due to their intrinsic safety, environmental friendliness and low cost. Nevertheless, the practical application of AAIBs is impeded by hydrogen evolution reaction (HER) occurring in diluted aqueous electrolyte. Highly concentrated electrolytes can improve electrochemical stability but lead to higher costs and increased hydrolysis of NH4+. In this work ethylene glycol (EG) is proposed as co‐solvent, which can act as H‐bond modulating agent, to increase the stability of AAIBs with diluted electrolytes. The perturbation of water H‐bond network regulated by EG is proved by spectroscopic methods, while the suppressed HER is confirmed by differential electrochemical mass spectrometry (DEMS) results. As a result, full cells with 3,4,9,10‐perylenebis(dicarboximide) (PTCDI) anode and FeFe(CN)6 (FeHCF) cathode and EG‐added electrolyte exhibit stable cycling performance with capacity retention of 77% after 1950 cycles. [ABSTRACT FROM AUTHOR]