Non-aqueous Systems Research Articles

Nonaqueous Contact-Electro-Chemistry via Triboelectric Charge.

Mechanochemistry revolutionizes traditional reactions through mechanical stimulation, but its reaction efficiency is limited. Recent advancements in utilizing triboelectric charge from liquid-solid contact electrification (CE) have demonstrated significant potential in improving the reaction efficiency. However, its efficacy remains constrained by interfacial electrical double-layer screening in aqueous solutions. This study pioneered chemistry in nonaqueous systems via CE for catalysis and luminescence. Density functional theory simulations and experiments revealed varying electron transfer capabilities and chemoselectivity of CE across different solvents. Phenol degradation via CE in dimethyl sulfoxide (DMSO) exhibited a rate over 40 times faster than that of traditional mechano-driven chemistry. A more intuitive comparison revealed that CE degradation of phenol in DMSO exhibits a 30-fold rate improvement compared to deionized water, where the degradation remains incomplete. Luminol oxidation by radicals generated solely via CE in DMSO eliminates the dependence on traditional catalysts and side reactions, establishing a pure and simple system for investigating the reaction mechanisms. A high and stable luminescence characteristic was maintained for 3 months, enhancing the imaging accuracy and stability exponentially. This study underscores the impact of triboelectric charge on reaction efficiency and chemoselectivity, establishing a new paradigm in nonmetal catalysis, mechanoluminescence, and providing profound insights into reaction kinetics.

Tetracyanoethylene Na+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {Na}^+$$\\end{document}/K+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {K}^+$$\\end{document} radical anion coordination sites unveiled via electronic and vibrational fingerprints

Tetracyanoethylene (TCNE) is a very effective electron acceptor and can form stable complexes with various chemical species and is known for its interesting electronic and optical properties. The formation of the monoanion gives TCNE unique electronic and chemical properties, making it a material of interest for several technological applications including solar cells, organic battery electrodes, sodium/potassium-ion batteries and information storage devices. The chemico-physical characterization of Na+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {Na}^+$$\\end{document} and K+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {K}^+$$\\end{document} coordination of TCNE in solution is not available so far, although it would be valuable for understanding the molecular mechanisms of charging and discharging processes in innovative battery devices. The present theoretical-computational study characterizes the vibrational and electronic properties of ion-coordinated TCNE in solution. We analyzed the ground electronic state through equilibrium structures, focusing on structural features, stability, optical properties and Raman vibrational modes. The Na+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {Na}^+$$\\end{document} and K+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {K}^+$$\\end{document} cations, coordinated at two distinct sites, significantly alter the geometry, and modulate electronic and vibrational properties. Using ab initio molecular dynamics simulations, we computed vibrational spectra, finding that TCNE complexes serve as effective probes for detecting environmental variations, with key vibrational modes on CC and CN moieties being sensitive to cation interactions. Additionally, a correlation between C=C bond distances and vibrational frequencies was observed. In conclusion, this study provides further insight into the role of TCNE in optoelectronic applications and nonaqueous battery systems.

Study of substituents-regulated dyeing properties in non-aqueous media systems based on MD simulation and DFT

To investigate the relationship between N-acetoxyethyl group and dyeing properties of disperse dyes in D5 non-aqueous medium dyeing system, the adsorption and diffusion behaviors of three disperse dyes with different structures were studied by molecular dynamics (MD). The diffusion coefficients, the planar distribution densities of dyes in different directions, and the intermolecular interaction energies were calculated. Molecular dynamics simulation (MD) was used to calculate molecules polarity index (MPI). Meanwhile, the practical dyeing experiments also were investigated to compare with simulated results. The results showed that the adsorption and diffusion behavior of disperse dyes with different structures were significantly different. Compared with dye B257, D-1 and D-2 are more easily adsorbed and diffused into the interior of the fiber because of the introduction of polar acetoxyethyl group. Moreover, the diffusion coefficient of D-2 in the fiber was relatively low, indicating that the combination between dye and polyester fiber was stable. XY plane distribution density and MPI revealed that the introduction of acetoxyethyl was beneficial to increase the adsorption amount of dye on the fiber, which was mainly related to the high binding energy between dye molecule and polyester fiber. The results of dyeing experiments showed that the decreased solubility of disperse dyes in the D5 medium was conducive to improving the dyeing rate of disperse dyes. This was consistent with the simulated interaction between dyes and D5. This study will provide a basis for further rapid and accurate development and selection of disperse dyes with high dyeing rate in non-aqueous medium systems.

Naked eye detection of anions: Dihydrazone receptor-based visual sensing

In this study, we designed and synthesized a novel colorimetric sensor for fluoride ions by integrating a thienodicarbohydrazide framework with salicylaldehyde, resulting in a unique bis-hydrazone-phenol receptor. This sensor exhibited exceptional selectivity for fluoride and acetate ions in nonaqueous environments, with detection visible to the naked eye. Upon interaction with fluoride ions, the receptor underwent a significant red shift in its UV–Visible absorption spectrum, moving from an absorption maximum at 332 nm–380 nm, signalling the recognition event. Acetate ions induced a similar shift. The binding interactions were thoroughly investigated, with a Jobs plot revealing a 1:1 receptor-anion complex formation with fluoride ions and a 1:2 complex with acetate ions. Further validation came from 1H NMR titration, which confirmed the presence of hydrogen bonding interactions between the receptor and the ions. The receptor demonstrated remarkable binding constants of 5.2 × 10⁴ M−2 for acetate and 1.6 × 10⁴ M−1 for fluoride ions, highlighting its strong and selective affinity. Fluorescence titrations further confirmed the receptor's potential as a chemo sensor, showing distinct emission changes in the presence of fluoride and acetate ions. This study not only underscores the receptor's capability for visual detection of fluoride ions in non-aqueous systems but also paves the way for its application in diverse analytical and environmental settings.

Bottlebrush Random Copolymers at Oil‐Oil Interfaces

Comprehensive SummaryOil‐in‐oil nonaqueous emulsions are of great interest for developing emulsion‐templated polymers and encapsulation systems that are incompatible with water‐sensitive substances. Tailor‐made amphiphilic block copolymers are by far the most efficient stabilizers for oil‐in‐oil emulsions while less attention is given to copolymers with more complex architectures. Here, we report the stabilization of DMSO‐silicone oil interface by bottlebrush random copolymers (BRCPs) containing norbornene backbones with densely grafted poly(methyl methacrylate) (PMMA) and polystyrene (PS) side chains. The assembly kinetics of BRCPs at the DMSO‐silicone oil interface can be divided into three processes, including diffusion, reconfiguration and reorganization, and can be varied by tuning the degree of polymerization of the backbone (NB). Due to the high efficiency of BRCPs in reducing the interfacial tension, when using BRCPs as stabilizers, stable silicone oil‐in‐DMSO traditional emulsions and high internal phase emulsions (HIPEs) can be successfully obtained, while no stable emulsions can be achieved with linear PMMA‐b‐PS serving as the stabilizer. This study, for the first time, underscores the great potential of amphiphilic bottlebrush copolymers in preparing oil‐in‐oil emulsions. Given the advances in polymerization strategy, a broad variety of amphiphilic bottlebrush copolymers are expected to be synthesized and applied in the stabilization of nonaqueous biphasic systems.

Reconfigurable All-Oil Microfluidic Devices by 3D Printing.

Nanoparticle surfactants have been widely used to construct structured liquids in oil-water systems. Less attention, though, has been given in non-aqueous systems, for example, oil-oil systems, mainly due to the lack of suitable surfactants. Here, by using newly developed molecular brush surfactants (MBSs) that form at the DMSO-silicone oil interface, the construction of all-oil microfluidic devices is reported with advanced functions. Due to the high interfacial activity of MBSs, Plateau-Rayleigh instabilities of liquid jets can be completely suppressed, leading to the production of liquid threads with jammed MBSs at the interface. Taking advantage of the 3D printing technique, all-oil microfluidic devices with complex structures can be constructed, showing promising applications in mass transmission, chemical separation, and material synthesis.

Design Glutamate Dehydrogenase for Nonaqueous System by Motifs Reassembly and Interaction Network Analysis.

Glutamate dehydrogenases (GDH) serve as the key regulated enzyme that links protein and carbohydrate metabolism. Combined with motif reassembly and mutation, novel GDHs were designed. Motif reassembly of thermophilic GDH and malate dehydrogenase aims to overcome stability and activity tradeoff in nonaqueous systems. Structural compatibility and dynamic cooperation of the designed AaDHs were studied by molecular dynamics simulation. Furthermore, multipoint mutations improved its catalytic activity for unnatural substrates. Amino acid interaction network analysis indicated that the high density of hydrogen-bonded salt bridges is beneficial to the stability. Finally, the experimental verification determines the kinetics of AaDHs in a nonaqueous system. The activity of Aa05 was increased by 1.78-fold with ionic liquid [EMIM]BF4. This study presents the strategy of a combination of rigid motif assembly and mutations of active sites for robust dehydrogenases with high activity in the nonaqueous system, which overcomes the activity-stability tradeoff effect.

An Alternative Concept in Making Hybrid Flow Batteries into Dendrite-Free Full-Flow Batteries

: In this study, the author proposes an alternative concept of using electrostatic force of cation-exchange resin to attract metal ions and nanoscale conductors onto the polymer matrix to conduct the electrons for the plating/stripping of the metal species. Due to the even distribution of the positively-charged functional groups inside the cation-exchange resin, metal formation can also be well distributed and safety issue caused by metal dendrite can be eliminated. By applying this transformative concept, various hybrid flow batteries could be “upgraded” to dendrite-free full-flow batteries. Interestingly, this new concept could also be generalized for all metal-based aqueous and nonaqueous hybrid systems to upgrade them into next-generation full-flow battery systems. This work offers an alternative concept to deliver unprecedented battery systems and the proof-of-concept would be more easily implemented than anticipated.

Simulation of chemical reactions with methanol and oxalic acid on 4H-SiC surfaces before and after nanoabrasion

Previous work by our team has shown that not only can oxalic acid added to a reactive methanol polishing solution significantly further improve SiC polishing removal rate but also surface quality. However, due to the lack of fundamental information on the nature of the interfacial reaction, the reaction mechanism involved in continuously improving SiC polishing performance remains unresolved. This study explores the chemical interactions of pristine and nano-scratched surfaces with the reaction medium using a molecular dynamics (MD) model combined with the ReaxFF reaction force field. The results show that –OH and –CHn, methanol can effectively break the Si-C bond on the surface of silicon carbide and the high amount of OH and C=O in oxalic acid favors the formation of surface silicon oxides and the softening of the silicon carbide surface. The synergistic effect of oxalic acid and methanol in the pre-scratch system indirectly supports the notion that nanoabrasion caused by nano-abrasives enhances the chemical reactivity of polishing fluid components. In conjunction with the experimental data, a proposed reaction mechanism for organic acid-containing alcohol fluids with SiC based on non-aqueous solvent systems is presented. This may stimulate ideas for better developing and applying novel non-aqueous-based polishing fluids.

Progress and Challenges of Vanadium Oxide Cathodes for Rechargeable Magnesium Batteries.

Among the challenges related to rechargeable magnesium batteries (RMBs) still not resolved are positive electrode materials with sufficient charge storage and rate capability as well as stability and raw material resources. Out of the materials proposed and studied so far, vanadium oxides stand out for these requirements, but significant further improvements are expected and required. They will be based on new materials and an improved understanding of their mode of operation. This report provides a critical review focused on this material, which is embedded in a brief overview on the general subject. It starts with the main strategic ways to design layered vanadium oxides cathodes for RMBs. Taking these examples in more detail, the typical issues and challenges often missed in broader overviews and reviews are discussed. In particular, issues related to the electrochemistry of intercalation processes in layered vanadium oxides; advantageous strategies for the development of vanadium oxide composite cathodes; their mechanism in aqueous, "wet", and dry non-aqueous aprotic systems; and the possibility of co-intercalation processes involving protons and magnesium ions are considered. The perspectives for future development of vanadium oxide-based cathode materials are finally discussed and summarized.

Antifoams in non-aqueous diesel fuels: Thin liquid film dynamics and antifoam mechanisms

HypothesisFoaming in diesel fuels is not well understood and leads to operational challenges. To combat deleterious effects of foaming, diesel formulations can include additives called antifoams. Existing antifoams, unfortunately, are inherently ash-generating when combusted, with unknown environmental impacts. They are prohibited in certain countries, so identifying effective alternative ash-free antifoam chemistries is needed.ExperimentsWe conduct systematic characterization of foam stabilization and antifoaming mechanisms in diesel for two different antifoams (silicone-containing & ashless chemistries). Employing a custom technique combining single-bubble/single-antifoam-droplet manipulation with white light interferometry, we also obtain mechanistic insights into foam stability and antifoam dynamics.ResultsCoalescence times from both bulk foam and single bubble experiments confirm ashless antifoams are effective at reducing foaming, demonstrating the potential of ashless antifoams. Further, we perform single-antifoam-droplet experiments and obtain direct experimental evidence revealing the elusive antifoaming mechanisms. Interestingly, the silicone-containing and ashless antifoams seemingly function via two different mechanisms: spreading and dewetting respectively. This surprising finding refutes conventional wisdom that spreading is likely the only antifoam mechanism in diesels. These results and the reported experimental framework significantly enhance the scientific understanding of non-aqueous foams and will accelerate the engineering of alternative antifoam chemistries for non-aqueous systems.

Temperature dependence of liquid–liquid equilibria in nonaqueous two–phase systems based on formamide

The cloud–point method was used to determine temperatures located on the binodal surface for several nonaqueous two-phase systems containing formamide, and: {1–pentanol + NaBr} or {1–pentanol + NaNO3}, or {1–butanol + NaNO3}, or {1–butanol + D–sorbitol}, or {acetonitrile + D–fructose}. For comparison purposes, the measurements were made in the water + acetonitrile + D-fructose system. The measured temperatures ranged from about 0 to 90 °C. The experimental data were described by the NRTL model as well as through several empirical equations with the parameters depending on temperature. Finally, the paper discusses the advantages and disadvantages of individual solutions.

Proton Diffusion in Liquid 1,2,3-Triazole Studied by Incoherent Quasi-Elastic Neutron Scattering.

Improving the proton transport in polymer electrolytes impacts the performance of next-generation solid-state batteries. However, little is known about proton conductivity in nonaqueous systems due to the lack of an appropriate level of fundamental understanding. Here, we studied the proton transport in small molecules with dynamic hydrogen bonding, 1,2,3-triazole, as a model system of proton hopping in a nonaqueous environment using incoherent quasi-elastic neutron scattering. By using the jump-diffusion model, we identified the elementary jump-diffusion motion of protons at a much shorter length scale than those by nuclear magnetic resonance and impedance spectroscopy for the estimated long-range diffusion. In addition, a spatially restricted diffusive motion was observed, indicating that proton motion in 1,2,3-triazole is complex with various local correlated dynamics. These correlated dynamics will be important in elucidating the nature of the proton dynamics in nonaqueous systems.

Photothermal Conversion of the Oleophilic PVDF/Ti3C2Tx Porous Foam Enables Non-Aqueous Liquid System Applicable Actuator.

Various physical and chemical reaction processes occur in non-aqueous liquid systems, particularly in oil phase systems. Therefore, achieving efficient, accurate, controllable, and cost-effective movement and transfer of substances in the oil phase is crucial. Liquid-phase photothermal actuators (LPAs) are commonly used for material transport in liquid-phase systems due to their remote operability and precise control. However, existing LPAs typically rely on materials like hydrogels and flexible polymers, commonly unsuitable for non-aqueous liquids. Herein, a 3D porous poly(vinylidene fluoride)(PVDF)/Ti3C2Tx actuator is developed using a solvent displacement method. It demonstrates directional movement and controlled material transport in non-aqueous liquid systems. When subject to infrared light irradiation (2.0Wcm-2), the actuator achieves motion velocities of 7.3 and 6mms-1 vertically and horizontally, respectively. The actuator's controllable motion capability is primarily attributed to the foam's oil-wettable properties, 3D porous oil transport network, and the excellent photothermal conversion performance of Ti3C2Tx, facilitating thermal diffusion and the Marangoni effect. Apart from multidimensional directions, the actuator enables material delivery and obstacle avoidance by transporting and releasing target objects to a predetermined position. Hence, the developed controllable actuator offers a viable solution for effective motion control and material handling in non-aqueous liquid environments.

Latest progress and challenges associated with lithium-ion semi-solid flow batteries: a critical review.

Since the proposal of the concept of semi-solid flow batteries (SSFBs), SSFBs have gained increased attention as an alternative for large-scale energy storage applications. As a new type of high energy density flow battery system, lithium-ion semi-solid flow batteries (Li-SSFBs) combine the features of both flow batteries and lithium-ion batteries and show the advantages of decoupling power and capacity. Moreover, Li-SSFBs typically can achieve much higher energy density while maintaining a lower cost. Therefore, Li-SSFBs are some of the most promising technologies for future energy storage. Despite these advantages, a significant gap towards the commercialization of Li-SSFBs still exists. In this article, we have reviewed the research progress of Li-SSFBs in aqueous and non-aqueous systems in recent years. We have further discussed the future research trends and application prospects of Li-SSFBs, providing guidelines for future research in this area.

CuS loaded on reduced graphene oxide prepared by ball milling method as cathode material for high- power aqueous Cu-Al hybrid-ion batteries

Aqueous hybrid-ion batteries (AHBs) are a potential low-cost, high safety, high operating voltage and high energy density storage devices. A new type of AHBs was proposed. We use a simple, low-cost and energy-saving ball milling method for the synthesis of material that CuS anchored on reduced graphene oxide (CuS@rGO). Aqueous Cu-Al hybrid-ion batteries were prepared with CuS@rGO as cathode, Cu as anode and LiCuAl (LiCl, CuCl and AlCl3) aqueous solution as electrolyte. The battery produces a reversible capacity of 218.9 mAh g−1 at 2 A g−1. At a high current density of 5 A g−1, the capacity can also reach 166.7 mAh g−1 and the battery capacity retention rate is as high as 80 % after 500 cycles. The successfully prepared CuS@rGO has excellent rate capability and strong cycling stability at high current density, which exceeds most reported aqueous and nonaqueous systems of Aluminum-ion batteries. The introduction of reduced graphene oxide (rGO) can accelerate the electron transfer in composites and provide better electrochemical kinetics, so it is conducive to the rapid storage of aluminum ions.

Expanding the Scanning Electrochemical Microscopy Toolset for Evaluating Electron Transfer Kinetics of Concentrated and Specialized Redox Electrolytes on Carbon Surfaces

Performing quantitative measurements of heterogeneous electron transfer reactions at electrodes (e.g., determining k0 and a) under conditions of high redox active molecule concentration in solution, such as those encountered in electrolytes for redox flow batteries (RFBs), presents significant technical challenges. For example, attempting to use transient voltammetry methodology quickly leads to limitations imposed by iR drop, as currents can be large and resistance, especially in non-aqueous systems, can be high. Additionally, using steady-state techniques based on convective principles, such as the rotating disk electrode (RDE), involve the use of relatively large equipment, with moving parts, and usually with requirements of tens to hundreds of mL of solution, which may be limiting for exploring new compounds at high concentration.To address these issues, here we introduce the use of scanning electrochemical microscopy (SECM) for the determining the rates of electron transfer of redox active species at high concentration in non-aqueous [1] and other unconventional systems, such as deep eutectic solvents. SECM enables the resolution of higher rates of electron transfer compared to transient voltammetry and RDE, and it also enables experiments with spatial resolution, enabling the exploration of reactivity on various sites of a heterogeneous electrode. In this presentation, we will describe theoretical and practical aspects of these measurements, and we will demonstrate their utility using two model systems. The first one consists on the observation of inherent rate asymmetries observed for ferrocene derivatives, ubiquitous redox probes, at the graphite/carbonate solvent interface. These asymmetries are not present on aqueous systems or metallic electrodes, demonstrating the ability of the SECM technique to capture unique behaviors. In the second case, we will discuss how SECM measurements can be used on deep eutectic solvents such as ethaline to address how interactions between redox actives and the electrode or the solvent systems modulate the rate of electron transfer. By systematically modifying the strength of interactions by means of molecule choice, solvent composition, and electrode type and structure, we can gain insight into the processes that determine reactivity at redox flow battery electrodes. This insight is critical for exploring the interfacial aspects such as adsorption, passivation, and double-layer effects on kinetics of electron transfer.[1] Gaddam, R.; Sarbapalli, D.; Howard, J.; Curtiss, L.A.; Assary, R.S.; Rodríguez-López, J. An SECM-Based Spot Analysis for Redoxmer-Electrode Kinetics: Identifying Redox Asymmetries on Model Graphitic Carbon Interfaces Chem: Asian J., 2023, 18, 2, e202201120. Figure 1

Bridging Aqueous and Organic Electrolytes: Intercalation Mechanism of TiS2 in Sustainable Aqueous Li-Ion Batteries

Aqueous Li-ion batteries (ALiBs) are a promising alternative for large-scale grid storage owing to water's non-flammability, low cost, and ease of purification. However, the narrow electrochemical stability window (ESW) of water (1.23 V) significantly limits the energy density of ALiBs, compared to their non-aqueous counterpart. The use of a highly concentrated electrolyte, such as 21 mol kg-1 (molality, m) of LiTFSI in water, known as the “water-in-salt” (WiS) electrolyte, can widen the water ESW to ~3 V, but its high cost and low environmental sustainability hinder the commercialization of ALiBs. Therefore, we explored the feasibility of cycling layered TiS2 anodes in ALiBs containing dilute electrolytes (i.e. 2 m LiTFSI in water).We obtained a reversible discharge capacity of ca. 80 mAh g-1 at a current density of 50 mA g-1. By employing three-electrode cycling with online electrochemical mass spectrometry, we identified potential-dependent gas evolution from the cell triggered by multiple chemical/electrochemical reactions, such as (1) solvent co-intercalation, (2) partial TiS2 exfoliation, and (3) TiS2-catalyzed water splitting in dilute aqueous electrolytes. We also identified a completely different potential profile of TiS2, when cycled in an aqueous electrolyte, with two distinct redox plateaus at 2.95 V and 2.88 V, followed by a sloping region until 2.3 V (all vs. Li+/Li0). Recall that in classic non-aqueous electrolytes, TiS2 shows a characteristic sloping profile centered at ca. 2.2 V, the peculiar potential profile suggests a different intercalation mechanism of TiS2 in aqueous electrolytes.In this presentation, we will share our latest findings from complementary physicochemical and computational methods to tackle the complex interfacial reactivity between layered anodes and aqueous electrolytes. Operando synchrotron X-ray diffraction data revealed the reversible uptake-release of water molecules between TiS2 layers, which was also confirmed energetically favorable by theoretical modeling. By introducing triethyl phosphate (TEP) as a co-solvent, we successfully tuned the electrochemical intercalation behavior of TiS2 from purely Li-intercalation (as in non-aqueous systems, when using only TEP as the solvent) to hydrated-Li-intercalation (as in concentrated and dilute aqueous electrolytes, when using water/TEP mixtures as the solvent). These findings suggest that solvent co-intercalation can be a promising strategy for ALiBs. The general implication of these results on the electrode-electrolyte interface and interphase in aqueous batteries will be systematically discussed in the talk. Overall, our work provides new perspectives on developing sustainable energy storage technologies. Figure 1

Selective Ion Conducting Polymers for Non-Aqueous Redox Flow Battery Applications

Providing sustainable supplies of clean energy is a critical global challenge for the future. As intermittent renewable energy sources are increasingly deployed, grid-scale energy storage solutions are increasingly needed. One approach to addressing this challenge is to use flow battery technology to store and deliver grid-scale amounts of energy. Non-aqueous redox flow batteries can be operated at higher voltages and energy densities compared to aqueous systems and, as such, may offer high volumetric energy density compared to other flow batteries. A significant challenge facing non-aqueous flow batteries, however, is the lack of selective membrane separators engineered for the unique challenges of non-aqueous electrochemical systems. Suitable membranes for non-aqueous redox flow battery applications must be stable in aggressive solvent environments, offer high conductivity, and provide selectivity to prevent cross-over of redox active molecules. Here, we report the synthesis and characterization of a series of negatively charged ion conductive polymeric membranes for non-aqueous flow battery applications. Fixed negative charges were added to a poly(phenylene oxide) backbone via a custom sulfonate group-based side chain. Lithium ion conductivity and ferrocene permeability properties were characterized to evaluate the selectivity of the membrane for ion transport relative to redox active molecule cross-over (as ferrocene is a representative redox active molecule). The polymers exhibited combinations of conductivity and selectivity that are favorable compared to other Nafion-based materials, and the materials appear to be dimensionally stable in a non-aqueous electrolyte over a period of several months. Redox active molecule cross-over was analyzed within a thermodynamic regular solution framework to highlight how thermodynamic factors contribute to cross-over properties. Ultimately, the data suggest a decoupling of ion and redox active molecule transport that could inform future efforts to develop advanced non-aqueous redox flow battery membrane separators. Altogether, this presentation discusses the transport properties and stability of these materials that show promise for non-aqueous flow battery applications.

The Enigma of Titanium Electrodeposition on Various Substrates

Titanium is an oxiphilic reactive metal which readily forms passive oxide films onto substrates. The unique properties of the metal such as low density (d=4.5 g/cm3), high strength, and corrosion resistance in harsh environments offers practical advantages. The pure metal is used abundantly in aerospace, armors, submarines, missiles, biomedicals, golf clubs and special electronic applications. The electro-deposition of corrosion resistant coatings is imperative to protect base metals. A review of previous literature has indicated that methods such as roll-diffusion cladding, magnetron discharge sputtering, electron beam, vacuum evaporation, ion beam enhanced deposition (PVD), thermal spray, chemical conversion coatings etc. have been employed in special applications at a prohibitive cost. Plating of titanium films in molten salts at high temperature, and inert atmospheres is a challenge to follow stringent conditions. Electroplating in ionic liquids is extremely expensive and limited.It will be an important technological advancement if a feasible electrodeposition process for titanium is developed for light base metals and plastics in aqueous or semi-aqueous solutions. Titanium electrodeposition in aqueous systems is not a straight-forward process due to its far negative reduction potential than that of hydrogen. Its multivalence states, stability, limited potential range, gas evolution, and substrate passivation pose technical challenges. The present author has critically evaluated several recipes cited by Russian literature, and a few United States patents. Unfortunately, we could not substantiate their cited claims. We have developed an innovative and proprietary process for electro-deposition of Ti in aqueous and partially non-aqueous systems. Deposition of titanium and its alloy films is demonstrated on variety of substrates such as Steel, Pb, Zn, Al, and selected plastics. It is our hope that this endeavor will open new avenues in surface finishing applications.