Electrolyte Solution Research Articles

Nonflammable Phosphate-Based Electrolyte for Safe and Stable Potassium Batteries Enabled by Optimized Solvation Effect.

Current potassium-ion batteries (PIBs) are limited in safety and lifetime owing to the lack of suitable electrolyte solutions. To address these issues, herein, we report an innovative non-flammable electrolyte design strategy that leverages an optimal moderate solvation phosphate-based solvent which strikes a balance between solvation capability and salt dissociation ability, leading to superior electrochemical performance. The formulated electrolyte simultaneously exhibits the advantages of low salt concentration (only 0.6 M), low viscosity, high ionic conductivity, high oxidative stability, and safety. Our electrolyte also promotes the formation of self-limiting inorganic-rich interphases at the anode surface, alongside robust cathode-electrolyte interphase on iron-based Prussian blue analogues, mitigating electrode/electrolyte side reactions and preventing Fe dissolution. Notably, the PIBs employing our electrolyte exhibit exceptional durability, with 80% capacity retention after 2,000 cycles at high-voltage of 4.2 V in a coin cell. Impressively, in a larger scale pouch cell, it maintains over 81% of its initial capacity after 1,400 cycles at 1C-rate with high average Coulombic efficiency of 99.6%. This work represents a significant advancement toward the realization of safe, sustainable, and high-performance PIBs.

Removal of Co(II) and various metal ions from the residue of the zinc plant through solvent extraction using both acid and neutral extractants

AbstractThe recovery of cobalt from secondary sources is a crucial issue in technology development, particularly for its numerous applications in various industries. Solvent extraction has proven an effective method for metallic ions separation from secondary sources. The main goal of this work was to study the separation of metals by solvent extraction technique from zinc plant leach waste. Initially, several extractants, including Cyanex 272, Cyanex 301, LIX 5640 H, Alamine 336, and tri‐n‐octylamine (TOA), were tested to treat the leach solution. It was discovered that the saponified extractant di‐(2‐ethylhexyl) phosphoric acid (D2EHPA) (10%) + tri‐n‐butyl phosphate (TBP) (10%) effectively eliminated interfering elements such as manganese, zinc, and iron, with extraction efficiencies of 95%, 98%, and 99.9%, respectively. To increase the concentration of cobalt in the purified solution, the cobalt recovery step was performed using various acids on the loaded organic phase. The best outcome was achieved using ammonium sulphate salt (1 M), which recovered about 50% of the cobalt present in the organic phase. The recovered cobalt was then subjected to the electrowinning process to produce cobalt metal of high purity. A cathodic current density of 100 A/m2 was determined to be the optimal current for the electrolyte solution. Lastly, scanning electron microscope (SEM) and X‐ray fluorescence (XRF) analyses were carried out to examine the structure and purity of the resulting metallic cobalt, which was found to have a purity of 99.5%.

Ion detection in a DNA nanopore FET device.

An ion detection device that combines a DNA-origami nanopore and a field-effect transistor (FET) was designed and modeled to determine sensitivity of the nanodevice to the local cellular environment. Such devices could be integrated into a live cell, creating an abiotic-biotic interface integrated with semiconductor electronics. A continuum model is used to describe the behavior of ions in an electrolyte solution. The drift-diffusion equations are employed to model the ion distribution, taking into account the electric fields and concentration gradients. This was matched to the results from electric double layer theory to verify applicability of the model to a bio-sensing environment. The FET device combined with the nanopore is shown to have high sensitivity to ion concentration and nanopore geometry, with the electrical double layer behavior governing the device characteristics. A logarithmic relationship was found between ion concentration and a single FET current, generating up to 200nA of current difference with a small applied bias.&#xD.

Determination and correlation of the solubility of magnesium sulfate in ethanol solutions with different concentrations: Application to the removal of magnesium from zinc electrolytic waste solution

Determination and correlation of the solubility of magnesium sulfate in ethanol solutions with different concentrations: Application to the removal of magnesium from zinc electrolytic waste solution

In situ and ex situ approaches for molecular scale understanding of electrochemical interfaces

Abstract Microscopic studies on electrolyte solution / electrode interfaces provide the most fundamental information not only for understanding the electric double layer formed at the interfaces but also for designing sophisticated electrochemical (EC) devices. In this study, we developed tip-enhanced Raman spectroscopy (TERS), which is based on an electrochemical scanning tunneling microscope (EC-STM), and demonstrated electrochemical TERS (EC-TERS) measurements of benzenethiol monolayers on Au(111). A specially-designed cell enables us to carry out reproducible EC, EC-STM, and EC-TERS measurements, which indicates consistent results among these techniques for the oxidative desorption of the benzenethiol monolayers.

Challenges in Measuring Transport Parameters of Carbonate‐Based Electrolytes

AbstractNumerical simulations are a powerful tool for the development and improvement of Li‐ion batteries. Modeling the mass transport of the involved electrolytic solutions requires precise determination of the corresponding electrolyte parameters. In this work, we attempt to measure the conductivity, the diffusion coefficient, the transference number and the thermodynamic factor for a system of 0.5 M LiPF6 dissolved in a blend of ethylene carbonate and ethyl methyl carbonate (EC : EMC, 3 : 7 weight) at 20 °C and 50 °C. Applying galvanostatic polarization experiments to symmetrical Li metal | electrolyte+separator | Li metal cells reveals, however, a potential response qualitatively deviating from theoretical expectations. Impeded diffusion processes indicate the presence of additional, undesired porous structures on the Li electrodes, preventing a reliable evaluation of the electrolyte parameters. To spectrally resolve the diffusive processes, we conduct very‐low‐frequency impedance spectroscopy. The impedance in fact exhibits multiple interfering diffusive features. In our measurements, an explicit identification of the impedance for the sole diffusion through the separator is however not feasible. Therefore, the authors doubt that polarizing experiments using Li metal electrodes yield accurate parameters for electrolytes.

Applications of Electrochemistry at the ITIES in Drug Discovery and Development – A Review

AbstractThe field of electrochemistry at the interface between two immiscible electrolyte solutions (ITIES) has been continuously expanding over the years due to their vast number of applications, including to investigate the partitioning of ionizable drugs at liquid‐liquid systems. The aim of this Review is to highlight the great potential of ITIES as simple model of biological membranes to gather information on drug partition, lipophilicity, and pharmacokinetics that can be very useful for researchers in the field of drug discovery for development of new drugs with enhanced permeability. Relevant contributions and perspectives to improve the applicability of ITIES in partition studies were highlighted and discussed. The second part of this Review pretends to highlight the application of electrochemistry at the ITIES as experimental technique to investigate interactions between small ligands, including drugs, and DNA, a topic of high research interest in pharmaceutical and biological sciences, which remains with lots of opportunities to explore.

Personalized Hydration Strategy to Improve Fluid Balance and Intermittent Exercise Performance in the Heat

Sweat rate and electrolyte losses have a large inter-individual variability. A personalized approach to hydration can overcome this issue to meet an individual’s needs. This study aimed to investigate the effects of a personalized hydration strategy (PHS) on fluid balance and intermittent exercise performance. Twelve participants conducted 11 laboratory visits including a VO2max test and two 5-day trial arms under normothermic (NOR) or hyperthermic (HYP) environmental conditions. Each arm began with three days of familiarization exercise followed by two random exercise trials with either a PHS or a control (CON). Then, participants crossed over to the second arm for: NOR+PHS, NOR+CON, HYP+PHS, or HYP+CON. The PHS was prescribed according to the participants’ fluid and sweat sodium losses. CON drank ad libitum of commercially-available electrolyte solution. Exercise trials consisted of two phases: (1) 45 min constant workload; (2) high-intensity intermittent exercise (HIIT) until exhaustion. Fluids were only provided in phase 1. PHS had a significantly greater fluid intake (HYP+PHS: 831.7 ± 166.4 g; NOR+PHS: 734.2 ± 144.9 g) compared to CON (HYP+CON: 369.8 ± 221.7 g; NOR+CON: 272.3 ± 143.0 g), regardless of environmental conditions (p < 0.001). HYP+CON produced the lowest sweat sodium concentration (56.2 ± 9.0 mmol/L) compared to other trials (p < 0.001). HYP+PHS had a slower elevated thirst perception and a longer HIIT (765 ± 452 s) compared to HYP+CON (548 ± 283 s, p = 0.04). Thus, PHS reinforces fluid intake and successfully optimizes hydration status, regardless of environmental conditions. PHS may be or is an important factor in preventing negative physiological consequences during high-intensity exercise in the heat.

Immobilization of human tyrosine hydroxylase onto magnetic nanoparticles – A novel formulation of a therapeutic enzyme

Human tyrosine hydroxylase (hTH) has key role in the production of catecholamine neurotransmitters. The structure, function and regulation of hTH has been extensively researched area and the possibility of enzyme replacement therapy (ERT) involving hTH through nanocarriers has been raised as well. However, our understanding on how hTH may interact with nanocarriers is still lacking. In this work, we attempted to investigate the immobilization of hTH on magnetic nanoparticles (MNPs) with various surface linkers in quantitative and mechanistic detail. Our results showed that the activity of hTH was retained after immobilization via secondary and covalent interactions as well. The colloidal stability of hTH could be also enhanced proved by Dynamic light scattering and Zeta potential analysis and a homogenous enzyme layer could be achieved, which was investigated by Raman mapping. The covalent attachment of hTH on MNPs via aldehyde or epoxy linkers provide irreversible immobilization and 38.1 % and 16.5 % recovery (ER). The hTH-MNPs catalyst had 25 % ER in average in simulated nasal electrolyte solution (SNES). This outcome highlights the relevance of immobilization applying MNPs as a potential formulation tool of sensitive therapeutic enzymes offering new opportunities for ERT related to neurodegenerative disorders.

STUDY OF THE INFLUENCE OF PLASMA-ELECTROLYTICE OXIDATION PARAMETERS ON THE FUNCTIONAL PROPERTIES OF HETEROXIDE COATINGS

The results of a study of the influence of the parameters of plasma-electrolytic oxidation in diphosphate electrolyte solutions of metal platforms made of titanium alloys, as the basis for the formation of heterooxide coatings with photocatalytic activity, on the level of their functional properties are presented. It has been established that heterooxide coatings obtained in PEO modes on titanium alloy platforms, in which zinc and tungsten compounds were incorporated as dopants, demonstrate photocatalytic activity in the processes of azo dye degradation under UV irradiation. An increase in the concentration of oxygen-containing compounds of dopants in electrolyte solutions has a positive effect on their incorporation into the composition of the monoxide matrix of the composite, morphology and catalytic properties of the obtained coatings. Based on the results of determining the morphological features of the structure of the coatings, it was proved that, compared with titanium monoxide, as a material for a photocatalytic platform, heterooxide coatings have a more developed globular surface microstructure, which positively affects the level of their functional performance. A symbatic dependence between the content of incorporated dopants and the specific surface area of coatings, as well as their photocatalytic activity, has been proven. It is noted that the change in the phase structure of the surface layers in the process of plasma-electrolytic formation of the TiO/ZnO-WO3 coating on the surface of the carrier metal causes an increase in the mechanical characteristics of the resulting coatings, in particular, the microhardness almost doubles. The obtained results can become the basis for the creation of functional materials for the catalytic neutralization of natural, synthetic and man-made toxicants, which will lead to the solution of a number of environmental problems both during the war crisis and during the post-war reconstruction of the country.

Binder-free phosphor-coated multiphase bismuth cobalt-selenide electrode for solar-charged quasi-solid-state hybrid supercapacitors

The enormous utilization of fossil fuels and the accelerated progression of global warming have irreversible destructive consequences on Earth's biodiversity. In response to this concern, there is a growing need to adopt green and renewable energy sources as effective strategies for mitigating environmental challenges. Herein, we report the novel synthesis and electrochemical properties of a binder-free phosphorus-coated multiphase bismuth-cobalt selenide/nickel foam (P@BCS/NF) electrode. Phosphorization was performed under an N2 atmosphere in a tube furnace to cover the electrodes. The synthesized electrode exhibited a porous nanorod morphology, which enhanced its electrochemical and energy storage properties. The P@BCS/NF electrode delivered a high areal capacity value of 836.4 µAh cm−2 in 1 M KOH electrolytic solution with excellent cycling stability, 81.4 % capacity retention, and 98.8 % coulombic efficiency over 10,000 cycles. A quasi-solid-state hybrid supercapacitor (QHSC) device was constructed using P@BCS/NF as the positive electrode and activated carbon as the negative electrode. The QHSC device showed maximum areal energy and power density values of 384.37 μWh cm−2 and 21750 μW cm−2, respectively, together with high stability of 94.4 % capacitance retention after 10,000 cycles. The practical application of the QHSC device was demonstrated in a PVA-KOH electrolytic environment by powering various electronic devices.

Nanoarchitectonics of bimodal porous carbon nanosheet with NiO/Ni nanoparticles derived from nitrile-functionalized benzoxazine for a supercapacitor electrode material

Nitrile-functionalized benzoxazine was successfully synthesized as a precursor for porous carbon. NH4Cl was used as a template to generate the nanosheet morphology and mesopore structure, while nickel(II) chloride in the hydrate form was used as a nickel source. The results showed that carbon samples based on pristine nitrile-functionalized benzoxazine revealed the standard isotherm of type I, representing a microporous nature. This isotherm was altered to type IV, indicating a mesoporous nature after adding the NH4Cl template, and the morphology of the carbon sample was also transformed into a more nanosheet-like structure with increasing NH4Cl loading. The specific surface area, mesoporosity and pore volume of the as-prepared samples tended to increase when increasing NH4Cl template loading, with Ni-PCN5 (5 g of NH4Cl template) having the maximum mesoporosity of 88.7%. The maximum specific surface area and pore volume are 556 m2 g−1 for Ni-PCN5–350 and 0.71 cm3 g−1 for Ni-PCN5, respectively. In addition, the metallic nickel nanoparticles were successfully embedded in the carbon structure, which were further transformed into nickel oxide nanoparticles after an annealing process. This annealing process also resulted in carbon samples with the standard isotherm of type I. For electrochemical performance, Ni-PCN-300 also showed the highest value of the specific capacitance, as high as 181 F g−1 measured at a current density of 0.1 A g−1 in a 1 mol L−1 KOH aqueous electrolyte solution, with an excellent cycling stability of 96.5% over 2000 testing cycles. In short, this work demonstrates a facile, inexpensive and eco-friendly approach to rationally design and synthesize nickel/nickel oxide nanoparticles-embedded porous carbon nanosheets with a micro- and mesoporous structure, as a promising candidate for a supercapacitor electrode material.

Phase Analysis, Microhardness and Wear Resistance of Selective Plated Copper-Based Coatings Containing Silver Particles

This study investigated the composition and properties of copper-based selective electrochemical coatings containing silver particles deposited on 316L stainless steel substrates. The method of formation of the coatings, using acid and alkaline electrolyte solutions, is described. A comparative analysis of the obtained coatings with selective copper coatings without added particles was carried out. An X-ray structural analysis was performed to determine the phase composition. Mechanical properties such as microhardness, surface roughness and wear resistance were investigated. The results show that the coatings are continuous, without visible defects, and the particles are deposited in depth as well. In both types of copper coatings with added silver particles, a dominant Cu phase and the presence of Ag were registered. It was established that the type of oxides formed in the deposition process is an important factor determining the microhardness and wear resistance of the coatings. The conclusions drawn confirm the effectiveness of the selective electrochemical deposition method for obtaining copper-based coatings containing silver particles and determine their characteristic mechanical properties.

Improved chloralkaline reversible electrochemical cells featuring a catalytic-coating-free 3-D printed titanium gas diffusion electrode

This study presents a novel resin 3-D printed chloralkaline reversible electrochemical cell featuring a 3-D printed titanium (3DP-Ti) cathode and a mixed-metal oxide anode. It evaluates the capability of this cell for electricity production (using hydrogen and bleach as fuel and comburent, respectively) and electrolysis of NaCl brine (producing hydrogen, chlorine, and retaining carbon dioxide). Parameters including NaCl concentration, bleach pH, and temperature were varied for examination. Despite the assembled 3DP-Ti does not contain any cathodic catalytic layer, the cell shows outstanding performance and it reaches maximum power densities of 7.38 mWcm−2 and maximum current densities of 12.7 mAcm−2. Hydrogen is flowed through small pores and electricity production dependence on feeding solution pH, electrolyte concentration, and temperature are observed. The system proved as a reversible chloralkaline electrochemical cell by confirming its good performance as an electrolyzer, with faradic efficiencies of 100 % for hydrogen production and 70 % for chlorine production. Energy efficiencies reached 196.54 mg Cl2/Wh and 7.48 mg H2/Wh. During operation as an electrolyzer (stream feeding to the gas diffusion cathode), it also demonstrated the capacity to fix carbon dioxide contained in gaseous streams by reacting with hydroxyl ions produced during the electrochemical hydrogen production. The fixation efficiency was 220.0 mg CO2 fixed/Wh. These findings demonstrate progress in electrochemical cell technology, highlighting its potential for various electrochemical applications.

Large amplitude voltage oscillations during plasma electrolytic oxidation (PEO) of niobium and their correlation with the porous morphology

Plasma electrolytic oxidation (PEO) is a technique that has been widely studied to obtain thick anodic oxide coatings based on aluminum, titanium, niobium, and other valve metals. In the case of niobium oxides, they are attractive because of their properties as semiconductors, biocompatibility, and high corrosion resistance. The electrochemical behavior during this process can vary according to the PEO parameters and influence characteristics such as coating thickness, adherence, morphology, and crystalline structure of the oxide film. In this study, unusual voltage oscillation transients are observed during the anodization of niobium under a galvanostatic PEO regime. The niobium substrates were anodized in three different electrolytic solutions (H3PO4, KOH, and C2H2O4), and the influence of temperature on the oscillation aspects in each one was investigated. In addition, three different current densities were tested to check the effect of this parameter on voltage oscillations. Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), and X-ray Diffraction (XRD) are used to characterize the samples. The results indicate a relationship between the exposed surface area and the pore morphology during the film growth in the oscillatory regime. A simultaneous process of oxide dissolution/pore filling and the micro-discharges observed during the PEO process is proposed.

Fabry-Pérot nanocavities controlled by Casimir forces in electrolyte solutions

Fabry-Pérot nanocavities controlled by Casimir forces in electrolyte solutions

Magnesium-based electrolytes with ionic liquids chloride additives: Quantum chemical stationary point analysis

The application of magnesium in electrolytes may decrease rechargeable battery production and utilization costs and improve some aspects of their performance. Yet, the development of robust electrolyte technologies remains a technological challenge. The search for optimal chemical compositions to avoid the formation of passivation layers on the electrode and increase the electrochemical stabilities of the electrolytes are underway. We hereby report the computational investigation on the magnesium-based electrolyte magnesium triflate supplemented by two chloride-containing additives tetrabutylammonium chloride and 1-ethyl-3-methylimidazolium chloride. Dimethoxy ethane (DME) is used as a molecular cosolvent. By revealing all possible ion-ionic and ion-molecular coordination patterns, we characterize the structural properties of these many-component systems and link them to the recently reported experimental results. Furthermore, the computed binding and cohesion energies were correlated to the transport properties of the electrolytes. We unveiled that the performances of both 1-ethyl-3-methylimidazolium chloride and tetrabutylammonium chloride additives were similar in all respects. However, 1-ethyl-3-methylimidazolium may be preferred because of its smaller size favoring lower shear viscosity. DME extensively participates in the coordination of Mg2+ by competing with chloride and triflate. The nucleophilic oxygen atoms of the anions and solvent molecules dominate the low-energy magnesium solvation patterns. The presence of the chloride anion in the first solvation shell of magnesium routinely corresponds to the highest thermodynamic stabilities of all investigated electrolyte solutions. The reported results foster the understanding of the magnesium-based ion-molecular systems. They are addressed to the researchers of electrolyte solutions and electrostatic coupling.

Surface tension of aqueous electrolyte solutions. A thermomechanical approach.

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.

Theoretical and practical investigation of ion-ion association in electrolyte solutions.

In this study, we present a new equation of state for electrolyte solutions, integrating the statistical associating fluid theory for variable range interactions utilizing the generic Mie form and binding Debye-Hückel theories. This equation of state underscores the pivotal role of ion-ion association in determining the properties of electrolyte solutions. We propose a unified framework that simultaneously examines the thermodynamic properties of electrolyte solutions and their electrical conductivity, given the profound impact of ion pairing on this transport property. Using this equation of state, we predict the liquid density, mean ionic activity coefficient, and osmotic coefficient for binary NaCl, Na2SO4, and MgSO4 aqueous solutions at 298.15K. Additionally, we evaluate the molar conductivity of these systems by considering the fraction of free ions derived from our equation of state in conjunction with two advanced electrical conductivity models. Our results reveal that, while ion-ion association has a minimal influence on the modification of the predicted properties of sodium chloride solutions, their impact on sodium and magnesium sulfate solutions is considerably more noticeable.

Electrochemical regeneration of carbendazim-loaded granular activated carbon

ABSTRACT This study explores the use of in situ electrochemical process to regenerate granular activated carbon (GAC) loaded with carbendazim (CBZ) and simultaneously oxidize the contaminant. The experiment optimized the flow rate ( Q ), current density ( j ), cathodic or anodic chamber, and electrolyte type to achieve the best results. The study found that using GAC in the cathodic chamber and NaCl as a supporting electrolyte, with a j  = 0.5 mA cm−2, and Q  = 100 L h−1, led to a 64% regeneration with an energy consumption of 0.15 kWh kg−1, which is at least 16× lower than those found in the literature for electrochemical, microwave and thermal processes. Consecutive regeneration tests revealed a decrease in GAC adsorptive capacity over time due to blockage by transformation products, and mainly by oxidation-induced changes in pore structure, as confirmed in dissolved organic carbon (DOC), scanning electron microscopy (SEM), and surface area results. The results also showed that in all tested conditions, residual CBZ was not found in the electrolyte solution. Overall, electrochemical regeneration proved to be an energy-efficient method for extending the lifespan of GAC and minimizing disposal in landfills.