Aqueous Solutions Of LiCl Research Articles

Swelling and Degrafting of Poly(3-sulfopropyl methacrylate) Brushes.

Upon exposure to a good solvent, polymer brushes prepared via surface-initiated polymerization can undergo degrafting via cleavage of bonds that anchor the polymer tethers to the underlying substrate. As polymer brushes are often used in a solvent swollen state, this has implications for the longevity of these polymer coatings. Improving the fundamental understanding of this process is thus also of practical importance. It is believed that degrafting is the consequence of tension amplification at the bonds that anchor the polymer grafts, which is driven by swelling of the polymer brush film. Taking advantage of the sensitivity of the swelling behavior of poly(3-sulfopropyl methacrylate) (PSPMA) brushes toward changes in ionic strength, this study has investigated the degrafting behavior of these brushes in aqueous media at different LiCl and NaCl concentrations. The aim of these experiments was to investigate whether the rate constant of the degrafting process was correlated with the swelling ratio of the PSPMA brushes. The experiments show that in aqueous LiCl solutions, the initial rate constant of the degrafting process is correlated with the swelling ratio of the PSPMA brush. This observation represents a first example of the correlation between these two parameters for hydrophilic polymer brushes in aqueous media and supports the idea that degrafting is a mechanochemical process driven by a swelling-induced tension at the polymer-substrate interface.

Role of Nitrogen-doping in porous carbon for enlarging working voltage window of aqueous supercapacitors in neutral electrolyte

The fundamental mechanism on enlarging working voltage window of carbon-based aqueous supercapacitors is still unclear owing to the indistinct principles in inhibiting water splitting occurred at the electrochemical interface. Herein, we design a set of N, O co-doped porous carbon (NOPC) free-standing electrodes with adjustable N-doping level, and establish that N-doping (N-content and specific N-configuration) governs neutral HER and OER. The NOPC electrode with a lower N-doping level can possess a wide working potential window of − 1–1 V, and thus the corresponding aqueous symmetric supercapacitors showcase a wide working voltage window of 2 V in LiCl aqueous solution. In situ spectroscopy evidences and theoretical simulation demonstrate that the low N-doping (N-content and percentage of pyrrolic nitrogen) level can weaken the interaction between the electrode and interfacial water molecules and suppress the formation of *OOH intermediate during the charge–discharge process, and thus significantly decreasing the HER and OER activities to inhibit water splitting. The finding can shed light on the fundamental understanding of mechanism on enlarging working voltage window of carbon-based aqueous supercapacitor.

Coupled Electron- and Ion-Transfer Processes at a Liquid/Liquid Interface Decorated with Photoactive Nanomaterials.

The influence of the ion transfer on photoinduced electron transfer (ET) reactions was studied on the surface of hyperbranched semiconducting BiVO4 particles spontaneously adsorbed at the liquid-liquid (L/L) interface between an aqueous LiCl solution and bis(triphenylphosphoranylidene) ammonium tetrakis(pentaflurophenyl)borate (BATB) in 1,2-dichlorethane. The organic electrolyte was supplemented with [Co(bpy)3](PF6)3 to accept photoexcited electrons from BiVO4 under formation of the corresponding Co(II) complex. The L/L interface was stabilized at the orifice of a micropipette (MP) and allowed to record ion transfer cyclic voltammetry (ITCV) by applying a Galvani potential difference between two reference electrodes in the electrolyte solutions with intermittent illumination by visible light (λ>420 nm). The photogenerated holes caused oxidation of water to O2. Co(II) and O2 were detected at constant at an amperometric microelectrode (ME) facing the orifice of the MP in either the organic or the aqueous electrolyte. The overall current exhibits a photocurrent only in the -range, in which the IT of PF6 - is kinetically limited. The amperometric detection of photogenerated products followed the same pattern as the photocurrent in the total current.

Coupled Electron‐ and Ion‐Transfer Processes at a Liquid/Liquid Interface Decorated with Photoactive Nanomaterials

AbstractThe influence of the ion transfer on photoinduced electron transfer (ET) reactions was studied on the surface of hyperbranched semiconducting BiVO4 particles spontaneously adsorbed at the liquid‐liquid (L/L) interface between an aqueous LiCl solution and bis(triphenylphosphoranylidene) ammonium tetrakis(pentaflurophenyl)borate (BATB) in 1,2‐dichlorethane. The organic electrolyte was supplemented with [Co(bpy)3](PF6)3 to accept photoexcited electrons from BiVO4 under formation of the corresponding Co(II) complex. The L/L interface was stabilized at the orifice of a micropipette (MP) and allowed to record ion transfer cyclic voltammetry (ITCV) by applying a Galvani potential difference between two reference electrodes in the electrolyte solutions with intermittent illumination by visible light (λ>420 nm). The photogenerated holes caused oxidation of water to O2. Co(II) and O2 were detected at constant at an amperometric microelectrode (ME) facing the orifice of the MP in either the organic or the aqueous electrolyte. The overall current exhibits a photocurrent only in the ‐range, in which the IT of PF6− is kinetically limited. The amperometric detection of photogenerated products followed the same pattern as the photocurrent in the total current.

Molecularly engineered chitosan-derived poly(aprotic/protic ionic liquids) double-network hydrogel electrolytes for flexible supercapacitors and wearable strain sensors

Polymeric conductive hydrogels have been highlighted for use in flexible electronics, and there is still a challenge to design and fabricate a high-performance hydrogel electrolyte with integrated and multiple properties, such as sustainability, stretchability and compressibility, ionic conductivity, antibacterial property, strain sensitivity, and low-temperature tolerance. Herein, chitosan (CS) derived poly(aprotic/protic ionic liquids) (CS-PAPILs) are facilely prepared by taking the structural and sustainable features of chitosan and betaine hydrochloride, which are used as a functional component for the fabrication of CS-PAPILs/polyacrylamide (PAM)/LiCl (CS-PAPILs/PAM/LiCl) double-network (DN) hydrogel electrolyte via an in situ polymerization of AM and then a soaking strategy in LiCl aqueous solution. The achieved DN hydrogels exhibit tunable mechanical performance (tensile strength of 70–900 kPa, elastic modulus of 31.5–484 kPa, high compressibility (4450 kPa at 80 % strain), superior low-temperature tolerance (freezing point < -85 °C), anti-dehydration performance, high ionic conductivity at 25/-50 °C (94.8/4.6 mS cm−1), and excellent antibacterial activity. As a proof of concept, an assembled flexible and anti-freezing supercapacitor by the as-prepared DN hydrogel electrolyte demonstrated a high specific capacitance of 108.4F/g (at 2 A/g) and impressive cycling stability over 50,000 cycles at temperature as low as −50 °C. Furthermore, a wearable strain sensor based on the DN hydrogel was also demonstrated, and the sensor can be successfully attached to the human joints to monitor various human motions.

Isocompositional liquid-liquid transition in dilute aqueous LiCl solutions

We here demonstrate that small amounts of LiCl dissolved in water extend the existence window of deeply supercooled liquid water. This shift allows us to observe the isocompositional, sharp liquid-liquid transition (LLT), while this is not possible in pure water. Upon heating at ambient pressure, the hyperquenched and densified glass first turns into the high-density liquid (HDL) and then experiences the LLT to the low-density liquid (LDL) at 137–141 K and ambient pressure. At the LLT the viscosity suddenly jumps up by an order of magnitude, from ∼4.3×109Pas in HDL to ∼3.7×1010Pas in LDL for the 3.1 mol % solution based on our calorimetric analysis. That is, the LLT takes place clearly in the ultraviscous liquid domain at ambient pressure. By contrast, the viscosity of the emerging LDL at the LLT is still in the domain of the soft glass for pure water and for solutions exceeding 5 mol % LiCl that were studied in the past. This is owing to our observation that, first, the LDL's glass transition is lowered by about 8 K to 126 K in the presence of small amounts LiCl, whereas the HDL's glass transition remains at 118 K. Second, the stability of HDL at ambient pressure is increased by high-pressure annealing, shifting the LLT to higher temperatures. Published by the American Physical Society 2024

Calorimetric Heats of Intrusion of LiCl Aqueous Solutions in Hydrophobic MFI-Type Zeosil: Influence of the Concentration.

For the first time, we report calorimetric measurements of intrusion of aqueous LiCl solutions in a hydrophobic pure siliceous MFI zeolite (silicalite-1) under high pressure. Our results show that the intrusion heats are strongly dependent on the LiCl concentration. The intrusion process is endothermic for diluted solutions (molar H2O/LiCl = 12) as well as for water, but it becomes exothermic for a concentration close to saturation (molar H2O/LiCl = 4). Analysis of the data in the framework of wetting thermodynamics shows that besides surface wetting, other phenomena occur during intrusion, such as hydrogen-bond weakening and composition change. In all cases, water is preferentially intruded so that the intruded phase becomes more diluted than the bulk solution. In the case of the most diluted solution, only water molecules seemed to be intruded. Furthermore, silicalite-1 is shown to be very stable in the presence of LiCl solution, with no noticeable structural and textural modifications observed after intrusion.

A Study on the Regeneration Performance Characteristics of an Internally Heated Regenerator in a Liquid Desiccant System

This paper presents a study of the regeneration performance characteristics of an internally heated regenerator applicable to a liquid desiccant system. The internally heated regenerator used in this study was designed and manufactured to provide good regeneration performance. An experimental setup was established to test the regeneration performance. LiCl aqueous solution was used as working fluid. Variables to evaluate regeneration performance characteristics of the internally heated regenerator were dry bulb temperature, relative humidity and velocity of regeneration air, mass flow rate, temperature and concentration of the LiCl aqueous solution. The experimental conditions were chosen by using a 1/2 fractional factorial DOE. Regeneration rate and regeneration effectiveness were taken as results. From the results, solution concentration and regeneration air relative humidity have strong effects on the regeneration rate. The regeneration effectiveness was affected mostly by regeneration air velocity and LiCl aqueous solution temperature.

Non-monotonic Soret coefficients of aqueous LiCl solutions with varying concentrations.

We investigate the thermodiffusive properties of aqueous solutions of lithium chloride, using thermal diffusion forced Rayleigh scattering in a concentration range of 0.5-2 mole per kg of solvent and a temperature range of 5 to 45 °C. All solutions exhibit non-monotonic variations of the Soret coefficient ST with a concentration exhibiting a minimum at about one mole per kg of solvent. The depth of the minimum decreases with increasing temperature and shifts slightly towards higher concentrations. We compare the experimental data with published data and apply a recent model based on overlapping hydration shells. Additionally, we calculate the ratio of the phenomenological Onsager coefficients using our experimental results and published data to calculate the thermodynamic factor. Simple linear, quadratic and exponential functions can be used to describe this ratio accurately, and together with the thermodynamic factors, the experimental Soret coefficients can be reproduced. The main conclusion from this analysis is that the minimum of the Soret coefficients results from a maximum in the thermodynamic factor, which appears itself at concentrations far below the experimental concentrations. Only after multiplication by the (negative) monotonous Onsager ratio does the minimum move into the experimental concentration window.

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.

Modeling of dilution enthalpies within implicit-solvent models for electrolytes

This work deals with the calculation of dilution enthalpies for strong aqueous electrolyte solutions when their thermodynamic properties are described within implicit-solvent models. The solution is modeled as a collection of charged hard spheres in a continuum solvent. A new general expression is obtained that accounts for the variation of the solution permittivity, of the size of the ions, and of the specific volume of the solution, with temperature and concentration. This expression is used to compute the enthalpies of LiCl aqueous solutions at temperatures in the range of 25∘C to 100∘C for concentrations up to 6 mol kg−1. The mean spherical approximation (MSA) model with implicit continuum solvent is employed to describe the thermodynamic properties of these solutions.

Solvent Shared Ion Pairs and Direct Contacted Ion Pairs in LiCl Aqueous Solution by IR Ratio Spectra

Solvent Shared Ion Pairs and Direct Contacted Ion Pairs in LiCl Aqueous Solution by IR Ratio Spectra

Phase Chemistry for Hydration Sensitive (De)intercalation of Lithium Aluminum Layered Double Hydroxide Chlorides.

Lithium aluminum layered double hydroxide chlorides (LADH-Cl) have been widely used for lithium extraction from brine. Elevation of the performances of LADH-Cl sorbents urgently requires knowledge of the composition-structure-property relationship of LADH-Cl in lithium extraction applications, but these are still unclear. Herein, combining the phase equilibrium experiments, advanced solid characterization methods, and theoretical calculations, we constructed a cyclic work diagram of LADH-Cl for lithium capture from aqueous solution, where the reversible (de)hydration and (de)intercalation induced phase evolution of LADH-Cl dominates the apparent lithium "adsorption-desorption" behavior. It is found that the real active ingredient in LADH-Cl type lithium sorbents is a dihydrated LADH-Cl with an Al:Li molar ratio varying from 2 to 3. This reversible process indicates an ultimate reversible lithium (de)intercalation capacity of ∼10 mg of Li per g of LADH-Cl. Excessive lithium deintercalation results in the phase structure collapse of dihydrated LADH-Cl to form gibbsite. When interacting with a concentrated LiCl aqueous solution, gibbsite is easily converted into lithium saturated intercalated LADH-Cl phases. By further hydration with a diluted LiCl aqueous solution, this phase again converts to the active dihydrated LADH-Cl. In the whole cyclic progress, lithium ions thermodynamically favor staying in the Al-OH octahedral cavities, but the (de)intercalation of lithium has kinetic factors deriving from the variation of the Al-OH hydroxyl orientation. The present results provide fundamental knowledge for the rational design and application of LADH-Cl type lithium sorbents.

Aqueous electrolytes at the charged graphene Surface: Electrode-Electrolyte coupling

Electrochemical energy sources support the growth in performance and portability of consumer electronics. Further sustainable development assumes an atomistically precise understanding of how the electrolyte binds to the electrode in the charged and uncharged states of the supercapacitors and Li-ion batteries. The present work investigates electrode–electrolyte interactions at the cathode using ab initio molecular dynamics simulations and representative energy-minimized ion-molecular configurations. Graphene is chosen as a material for the cathode, whereas the aqueous solutions of LiCl, NaCl, and KCl are model electrolytes. The study reveals a few fundamentally new physical insights regarding the performance of a supercapacitor. First, the graphene-ions coordination regularities are qualitatively different at charged and uncharged cathode. It is, therefore, essential to account for the effect of charging when studying the physical chemistry of supercapacitors. Second, the energy capacity offered by the aqueous Na-ion electrolyte is worse than those of the aqueous Li-ion and K-ion electrolytes. This observation is a result of an interplay between the dehydration energies and adsorption energies at the cathode energies. Third, the role of cation-solvent binding represents a cornerstone contribution to the capacity of an energy storage device in addition to the well-recognized cation-cathode binding thermodynamics. The reported results are fundamentally important to thoughtfully designing electrolyte compositions and electrode materials for supercapacitors and alkali-ion batteries.

Chain-like Structures Facilitate Li+ Transport in Concentrated Aqueous Electrolytes: Insights from Ultrafast Infrared Spectroscopy and Molecular Dynamics Simulations.

Highly concentrated aqueous electrolytes have attracted attention due to their unique applications in lithium ion batteries (LIBs). However, the solvation structure and transport mechanism of Li+ cations at concentrated concentrations remain largely unexplored. To address this gap in knowledge, we employ ultrafast infrared spectroscopy and molecular dynamics (MD) simulations to reveal the dynamic and spatial structural heterogeneity in aqueous lithium chloride (LiCl) solutions. The coupling between the reorientation dynamics of the extrinsic probe and the macroscopic viscosity in aqueous LiCl solutions was analyzed using the Stokes-Einstein-Debye (SED) equations. MD simulations reveal that the Cl- and Li+ form chain-like structures through electrostatic interactions, supporting the vehicular migration of Li+ through the chain-like structure. The concentration dependent conductivity of the LiCl solution is well reproduced, where Li(H2O)2+ and Li(H2O)3+ are the dominant species that contribute to the conduction of Li+. This study is expected to establish correlations between ion pair structures and macroscopic properties.

Salinity Gradient-Induced Power Generation in Nanochannels: The Role of pH-Sensitive Polyelectrolyte Layers.

By varying the pH values (pHR) and types of salt solution, we investigate the salinity gradient-induced electrical and mechanical flow energies inside a reservoir-connected charged nanochannel with a grafted pH-sensitive polyelectrolyte layer (PEL) on the inner surfaces. The aqueous solutions of KCl, LiCl, BaCl2, BeCl2, AlCl3, and Co(en)3Cl3 salts are used as the working fluid in the current investigation. We examine the associated ionic transport and flow field, aiming to understand the underlying physics behind the generation of electrical and hydraulic energy through alterations in pHR and types of salt solution. Our results reveal that the PEL space charge density decreases with increasing pHR at lower values, while it remains almost insensitive to higher pHR values. The electrical conductance and maximum pore power of the Co(en)3Cl3 solution are significantly higher compared to salts with monovalent and divalent cations. Furthermore, the magnitude of these two parameters decreases with lower pHR and becomes insensitive to higher pHR values. The results illustrate that the maximum electrical energy conversion efficiency enhances with pHR, reaching its highest level for the Co(en)3Cl3 solution. We expect that the findings of the current work will have a significant bearing on the design and development of a state-of-the-art salinity gradient-based energy convertor as a potential candidate for renewable energy sources.

Layered hydrated-titanium-oxide-laden reduced graphene oxide composite as a high-performance negative electrode for selective extraction of Li via membrane capacitive deionization

In this work, we initially prepared layered lithium titanate (Li2TiO3) using a solid-state reaction. Then Li+ of Li2TiO3 were acid-eluded with Hydrochloric acid to obtain hydrated titanium oxide (H2TiO3). Different weight percentages (50%, 60%, 70%, 80%, and 90%) of the as-prepared H2TiO3 were deposited on a conductive reduced graphene oxide (rGO) matrix to obtain a series of rGO/ H2TiO3 composites. Of the prepared composites, rGO/H2TiO3-60% showed excellent current density, high specific capacitance, and rapid ion diffusion. An asymmetric MCDI (membrane capacitive deionization) cell fabricated with activated carbon as the anode and rGO/H2TiO3-60% as the cathode displayed outstanding Li+ electrosorption capacity (13.67 mg g−1) with a mean removal rate of 0.40 mg g−1 min−1 in a 10 mM LiCl aqueous solution at 1.8 V. More importantly, the rGO/H2TiO3-60% composite electrode exhibited exceptional Li+ selectivity, superior cyclic stability up to 100,000 s, and a Li+ sorption capacity retention of 96.32% after 50 adsorption/desorption cycles. The excellent Li+ extraction obtained by MCDI using the rGO/H2TiO3-60% negative electrode was putatively attributed to: (i) ion exchange between Li+ and H+ of H2TiO3; (ii) the presence of narrow lattice spaces in H2TiO3 suitable for selective Li+ capture; (iii) capture of Li+ by isolated and hydrogen-bonded hydroxyl groups of H2TiO3; and (iv) enhanced interfacial contact and transfer of large numbers of Li+ ions from the electrolyte to H2TiO3 achieved by compositing H2TiO3 with a highly conductive rGO matrix.

Optical property measurements of lithium chloride aqueous solution for a novel solar neutrino experiment

The lithium chloride aqueous solution has great potential to be the detection medium of a novel solar neutrino detector. The nuclide 7Li provides a charged-current interaction channel with a high cross-section for the MeV-scale solar electron-neutrinos, enabling measurement of the solar neutrino spectrum. This work measures the optical properties and the light yields of a saturated lithium chloride solution. After adsorption with activated carbon and recrystallization, the solution shows little absorption in the sensitive wavelength range of the bialkali photomultipliers. The attenuation length is evaluated to reach 50 meters at 430 nm. In addition to being a pure Cherenkov detector medium, a wavelength shifter, carbostyril 124, is added to the LiCl aqueous solution. The compatibility and the enhancement of the light yield are confirmed, enabling the development of a water-based Cherenkov-enhanced lithium-rich detector.

Efficient lithium extraction using redox-active Prussian blue nanoparticles-anchored activated carbon intercalation electrodes via membrane capacitive deionization

Global demand for lithium (Li) resources has dramatically increased due to the demand for clean energy, especially the large-scale usage of lithium-ion batteries in electric vehicles. Membrane capacitive deionization (MCDI) is an energy and cost-efficient electrochemical technology at the forefront of Li extraction from natural resources such as brine and seawater. In this study, we designed high-performance MCDI electrodes by compositing Li+ intercalation redox-active Prussian blue (PB) nanoparticles with highly conductive porous activated carbon (AC) matrix for the selective extraction of Li+. Herein, we prepared a series of PB-anchored AC composites (AC/PB) containing different percentages (20%, 40%, 60%, and 80%) of PB by weight (AC/PB-20%, AC/PB-40%, AC/PB-60%, and AC/PB-80%, respectively). The AC/PB-20% electrode with uniformly anchored PB nanoparticles over AC matrix enhanced the number of active sites for electrochemical reaction, promoted electron/ion transport paths, and facilitated abundant channels for the reversible insertion/de-insertion of Li+ by PB, which resulted in stronger current response, higher specific capacitance (159 F g−1), and reduced interfacial resistance for the transport of Li+ and electrons. An asymmetric MCDI cell assembled with AC/PB-20% as cathode and AC as anode (AC//AC-PB20%) displayed outstanding Li+ electrosorption capacity of 24.42 mg g−1 and a mean salt removal rate of 2.71 mg g min−1 in 5 mM LiCl aqueous solution at 1.4 V with high cyclic stability. After 50 electrosorption-desorption cycles, 95.11% of the initial electrosorption capacity was retained, reflecting its good electrochemical stability. The described strategy demonstrates the potential benefits of compositing intercalation pseudo capacitive redox material with Faradaic materials for the design of advanced MCDI electrodes for real-life Li+ extraction applications.

Effect of salt addition on cellulose conversion into 5-hydroxymethylfurfural in metal chloride aqueous solution

Metal chloride aqueous solution is an effective method to promote the conversion of cellulose into 5-hydroxymethylfurfural (HMF). In this work, the influences of sodium chloride (NaCl) and lithium chloride (LiCl) on the conversion of cellulose into HMF in ferric chloride (FeCl3) aqueous solution were investigated. The conversion of glucose and fructose in FeCl3–NaCl and FeCl3–LiCl aqueous solutions were studied, and the interaction between active species and cellobiose was characterized by UV spectrum and electrospray ion mass spectrometry to explore salt addition on the reaction of cellulose conversion and the active specie. Results showed that the yield of HMF converted from cellulose in FeCl3 aqueous solution was low, while the yield of HMF was significantly increased when NaCl or LiCl added to the system. In FeCl3–NaCl aqueous solutions, the yield of HMF reach a maximum of 40.0% at a concentration of 0.02 M FeCl3, and hydrolysis of cellulose was the key step in the conversion of cellulose; In FeCl3–LiCl aqueous solutions, the yield of HMF reach a maximum of 36.7% at a concentration of 0.06 M FeCl3, and isomerization of glucose was the controlling step. The characterization results illustrated that the addition of NaCl or LiCl changed the active species in FeCl3 aqueous solutions, and [Fe(OH)2]+ and [FeCl2(OH) + Li]+ were the active species in FeCl3–NaCl and FeCl3–LiCl aqueous solution for cellulose conversion, respectively.