Concentrated Aqueous Solutions Research Articles

Understanding the Ageing Processes of Electrolytes in Aqueous Magnesium Batteries Using Radiation Chemistry

Manufacturing aqueous batteries based on the magnesium cations is an important step towards more sustainable and safer energy storage solutions. Thus, it is important to understand how these systems age and which species are formed throughout numerous charge/discharge cycles. To this end, we have used radiolysis to induce accelerated aging in concentrated solutions of magnesium bistriflimide Mg(TFSI)2 (also called “water‐in‐salt electrolytes” or WISEs). We demonstrate in this work that the degradation products formed, whether in the gas or liquid phase, are very similar to those formed in concentrated LiTFSI aqueous solutions. In fact, the behavior under ionizing radiation is driven by the anion/water molar ratio regardless of whether the cation is Li+ or Mg2+. This is because both cations are non‐reactive, and the bond strengths in the TFSI‐ anion do not vary with the nature of the cation. Reaction mechanisms are proposed to explain the formation of several species under ionizing radiation.

Effects of Nanoconfinement on Dynamics in Concentrated Aqueous Magnesium Chloride Solutions.

Water behavior in various natural and manufactured settings is influenced by confinement in organic or inorganic frameworks and the presence of solutes. Here, the effects on dynamics from both confinement and the addition of solutes are examined. Specifically, water and ion dynamics in concentrated (2.5-4.2 m) aqueous magnesium chloride solutions confined in mesoporous silica (2.8 nm pore diameter) were investigated using polarization selective pump-probe and 2D infrared spectroscopies. Fitting the rotational and spectral diffusion dynamics measured by the vibrational probe, selenocyanate, with a previously developed two-state model revealed distinct behaviors at the interior of the silica pores (core state) and near the wall of the confining framework (shell state). The shell dynamics are noticeably slower than the bulk, or core, dynamics. The concentration-dependent slowing of the dynamics aligns with behavior in the bulk solutions, but the spectrally separated water-associated and Mg2+-associated forms of the selenocyanate probe exhibit different responses to confinement. The disparity in the complete reorientation times is larger upon confinement, but the spectral diffusion dynamics become more similar near the silica surface. The length scales that characterize the transition from surface-influenced to bulk-like behavior for the salt solutions in the pores are discussed and compared to those of pure water and an organic solvent confined in the same pores. These comparisons offer insights into how confinement modulates the properties of different liquids.

Management of toxic waste released by incorrectly discarded batteries in Brazil

Abstract The main difference between a dry cell battery and an alkaline one is the composition of the electrolyte. In zinc–carbon batteries, dry cell, the electrolyte is a paste formed by mixing ammonium chloride and zinc chloride, whereas in alkaline batteries, the electrolyte is a concentrated aqueous solution of potassium hydroxide containing a certain amount of zinc oxide, hence the name alkaline for this battery. Therefore, the improper disposal of these materials has numerous consequences for the environment, since the potentially toxic metals present in them can be leached, infiltrating, and contaminating the soil layers, the groundwater, as well as the fauna and flora of the regions nearby. Thus, the objective is to perform studies that aim to simulate and analyze the release of potentially toxic metals present in batteries found in normal environmental conditions, through leaching tests from regular batteries (Zn–C) on fertilized soil, simulating a landfill, in addition to tests on sandy soil in order to aid the identification of possible waste release.

Interfacially self-assembled Fe2O3 nanoparticles decorated kaolinite for high performance anti-bacterial and anti-cancerous agents

Nano-engineering of naturally occurring layered materials incorporates enhanced inherent properties for bionanotechnology. Here, kaolinite was treated with a concentrated aqueous ferrous sulfate solution at 100 °C for 1 h for surface modification. Therefore, interfacially self-assembled nanostructure of ferric oxide (Fe2O3) decorated kaolinite composites (FDKC) was fabricated from cationically (Fe2+) modified kaolinite (CMK) after calcinations at 680 °C. Characterized nanocomposites by ATR-IR, EDS, XRD and SEM were tested for antimicrobial activity and antibiofilm activity against Gram negative bacteria Escherichia coli (E. coli), Klebsiella spp (K. spp) and Salmonella typhi (S typhi), as well as Gram positive Staphylococcus aureus, while cytotoxic activity was observed against HeLa cell. CMK and FDKC showed significantly higher antimicrobial activity and biofilm destruction ability than virgin kaolinite (p < 0.05). Besides, FDKC showed the highest anticancer activity in HeLa cell at moderate concentration. The synergistic effect of nanocomposites would offer the modulation of enhanced electronic and physical properties from a simple technology to improve inherent antimicrobial activity and cell toxicity of kaolinite for targeted assay.

Efficient Capture and Electroreduction of Dilute CO2 into Highly Pure and Concentrated Formic Acid Aqueous Solution.

High-purity CO2 rather than dilute CO2 (15 vol %, CO2/N2/O2 = 15:80:5, v/v/v) similar to the flue gas is currently used as the feedstock for the electroreduction of CO2, and the liquid products are usually mixed up with the cathode electrolyte, resulting in high product separation costs. In this work, we showed that a microporous conductive Bi-based metal-organic framework (Bi-HHTP, HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) can not only efficiently capture CO2 from the dilute CO2 under high humidity but also catalyze the electroreduction of the adsorbed CO2 into formic acid with a high current density of 80 mA cm-2 and a Faradaic efficiency of 90% at a very low cell voltage of 2.6 V. Importantly, the performance in a dilute CO2 atmosphere was close to that under a high-purity CO2 atmosphere. This is the first catalyst that can maintain exceptional eCO2RR performance in the presence of both O2 and N2. Moreover, by using dilute CO2 as the feedstock, a 1 cm-2 working electrode coating with Bi-HHTP can continuously produce a 200 mM formic acid aqueous solution with a relative purity of 100% for at least 30 h in a membrane electrode assembly (MEA) electrolyzer. The product does not contain electrolytes, and such a highly concentrated and pure formic acid aqueous solution can be directly used as an electrolyte for formic acid fuel cells. Comprehensive studies revealed that such a high performance might be ascribed to the CO2 capture ability of the micropores on Bi-HHTP and the lower Gibbs free energy of formation of the key intermediate *OCHO on the open Bi sites.

Risperidone/cyclodextrin inclusion complex electrospun nanofibers for fast-disintegrating antipsychotic drug delivery

In this paper, the inclusion complexes (ICs) of hydroxypropyl-beta-cyclodextrin (HPβCD) and risperidone were electrospun into nanofibrous film for potential fast-disintegrating drug delivery system. Risperidone is used to treat bipolar disorder, schizophrenia, and mood swings from autism. However, it is practically insoluble in aqueous medium. On the other hand, the encapsulation of risperidone into HPβCD cavity by inclusion complexation can enhance water solubility of this drug molecule. Here, the IC systems were prepared with 4/1 and 2/1 M ratio (HPβCD/risperidone). The highly concentrated HPβCD aqueous solutions (200 %, w/v) were used for the fiber formation. Finally, the system having 4/1 M ratio resulted in a clear and homogeneous solution showing that the HPβCD and risperidone completely formed IC. However, HPβCD/risperidone-IC having 2/1 M ratio was turbid and contained some small clumps of un-complexed risperidone. Even so, free-standing and thin nanofibrous films were obtained for both systems with an average fiber diameter of ∼315 nm and ∼280 nm for 2/1 and 4/1 systems, respectively. Both HPβCD/risperidone-IC nanofibers were produced with approximately 100 % preservation of risperidone within the nanofiber matrix without the loss of risperidone during electrospinning process, that is, HPβCD/risperidone-IC nanofibers retained the initial M ratio of 2/1 and 4/1 as in electrospinning solution. Both HPβCD/risperidone-IC nanofibrous films showed fast-disintegration and fast-release characteristics in artificial saliva and aqueous medium verifying their potential as a fast-disintegrating oral drug delivery system for risperidone.

Enhanced Durability and Antireflective Performance of Ag-Based Transparent Conductors Achieved via Controlled N-Doping.

Ag-based transparent conductors (TCs) are often proposed as an alternative to ITO coatings. However, while their performance has been widely demonstrated, their environmental durability is frequently overlooked or addressed with the use of highly specific encapsulating layers. In this work, the durability and antireflective performance of Ag-based TCs are simultaneously enhanced. To do so, a transfer matrix modeling approach is used to determine the general requirements for high performance antireflective properties as a function of Ag thickness and dielectric refractive indices, offering more widely applicable insight into stack optimization. Coating durability is investigated as a function of the Ag microstructure, which is modified by altering the N2 concentration used for doping of the Ag layer and the selection of the seed layer. Increasing N2 concentration during Ag deposition was found to decrease grain size and durability of Ag coatings deposited on Si3N4 whereas all coatings on ZnO(Al) showed higher stability. Significantly higher durability is found when specifically combining intermediate N2 concentrations in the sputtering gas mixture (Ag(N):5%, compared to 0% and 50%) and a ZnO(Al) seed layer, and a mechanism accounting for this increased durability is proposed. The addition of NiCrNx protective coatings increases the system durability without altering these trends. These findings are combined to fabricate a highly performant Ag-based TC (TV = 89.2%, RVFS = 0.23%, 21.4 Ω), which shows minimal property changes following corrosion testing by immersion in a heated and highly concentrated aqueous NaCl solution (200 g/L, 50 °C).

Thermodynamics of acidic dissociation of ammonium ion in concentrated aqueous solutions of ammonium nitrate

Based on pH-metric measurements, the equilibrium constants for ammonia protonation at 298.15 K and ionic strengths I = 5–9, supported by ammonium nitrate, were calculated. Using direct calorimetric measurements, the enthalpies of this process were determined at 288.15, 298.15 and 303.15 K and I = 5–9 and its full thermodynamic parameters were calculated. The sharp increase in exothermicity and decrease in entropy of this process observed at high ionic strengths are explained by decrease in the contribution of desolvation of reagents in the region of deficiency of solvent molecules and the influence of association of ions of background electrolyte. The obtained thermodynamic characteristics of ammonia protonation clearly indicate that a change in solvation state of reaction participants at high ionic strengths changes the nature of this reaction.

Hydrogen-bonded structure of hydrated water in polyvinyl pyrrolidone aqueous solution investigated by X-ray absorption and emission spectroscopy

Polyvinylpyrrolidone (PVP) is a hydrophilic polymer that is widely used in various biomedical applications owing to its excellent biocompatibility. It has been suggested that water-polymer interactions play a key role in controlling biocompatibility, although the molecular-level consequences of these interactions remain unknown. In this study, the hydrogen-bonded structures of water molecules hydrating PVP were investigated using X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES). XAS spectral profiles revealed that the CO bonds in highly concentrated PVP aqueous solutions have at least two states: one where hydrogen bonds are formed with water molecules and the other where they are not. In the XES profile of water extracted from a solution with a stoichiometric ratio of nw = 1.0, increased hydrogen bonding and hydrogen bond distortion were identified from the enhancement of 1b1′ and 3a1 peaks, respectively. Because it is difficult for water molecules to form strong hydrogen-bonded structures in tetrahedral coordination at nw = 1.0, these findings suggest that the presence of strong hydrogen bonds between the CO sites and water prevents the formation of tetrahedrally coordinated hydrogen-bonded structures among water molecules.

Force Fields for High Concentration Aqueous KOH Solutions and Zincate Ions.

Motivated by increasing interest in electrochemical devices that include highly alkaline electrolytes, we investigated two force fields for potassium hydroxide (KOH) at high concentrations in water. The "FNB" model uses the SPC/E water model, while the "FHM" model uses the TIP4P/2005 water model. We also developed parameters to describe zincate ions in these solutions. The density and viscosity of KOH using the FHM model are in better agreement with experiment than the values from the FNB model. Comparing the properties of the zincate solutions to the available experimental data, we find that both force fields agree reasonably well, although the FHM parameters give a better prediction of the viscosity. The developed force field parameters can be used in future simulations of zincate/KOH solutions in combination with other species of interest.

Analysis of Causes and Protective Measures against Corrosion Perforation in the Shell-Side Outlet Flange of a Sour Water Steam Heater

Heat exchangers, as essential devices for facilitating heat transfer, have found a variety applications in various industries. However, the occurrence of corrosion-related failures in real-world scenarios remains a prevalent problem that can lead to catastrophic incidents. This paper investigates the problem of corrosion perforation on the outlet flange of a heat exchanger in a sour steam stripper from a petrochemical company. Failure analysis was performed using physical testing and chemical analysis, metallographic examination, microscopic observation, and energy spectrum analysis. Intergranular corrosion experiments and flow calculations were performed to verify the analysis. The results indicate that the main cause of the flange corrosion perforation was the formation of a highly concentrated NH4HS aqueous solution during the cooling process of the NH3, H2S, and water vapor in the fluid passing through the heat exchanger, and the velocity was too high, which triggered alkali-sour water washout corrosion. To prevent the recurrence of similar corrosion perforations, recommendations for material and process optimization are proposed to effectively reduce the safety production risks in refinery units and provide valuable information for the safe long-term operation of a sour steam stripper.

B-site disorder driven Griffiths-like phase and electrochemical behavior in Y2NiCrO6 double perovskite

In this investigation, nanoparticles of B-site disordered Y2NiCrO6 (YNCO) double perovskite were synthesized by the facile sol–gel method to evaluate their magnetic and electrochemical properties. Their crystallographic structure is monoclinic and the average size of the particles is 79±16 nm. XPS analysis indicated a mixed oxidation states of B-site transition metals Ni2+/Ni3+ and Cr2+/Cr3+. The mixed valence states of Ni and Cr, along with the mixed magnetic phases of YNCO, constitute a signature of the B-site disorder. This antisite disorder contributed to the observation of a Griffiths-like phase arising from ferromagnetic short-range interactions above the magnetic transition up to the Griffiths temperature, T G = 137 K. The synthesized YNCO double perovskite demonstrated a promising behavior as an electrode material for electrochemical supercapacitors. In a three-electrode system, it displayed a specific capacitance of 270 F g−1 at a current density of 0.5 A g−1. In a symmetric two-electrode system, YNCO exhibited a specific capacitance of 180 F g−1 at 0.5 A g−1, alongside an energy density of 6.25 Wh kg−1 at 250 W kg−1 power density. In both cases, we employed a mild 0.5 M neutral aqueous Na2SO4 solution as the electrolyte, in contrast to the typically employed corrosive and concentrated alkaline aqueous solution. The fascinating magnetic and charge storage properties of the B-site disordered YNCO double perovskite indicate its potential for use in spintronic devices and as efficient electrodes in symmetric hybrid supercapacitors.

Giant Thermoelectric Response of Confined Electrolytes with Thermally Activated Charge Carrier Generation.

The thermoelectric response of thermally activated electrolytes (TAEs) in a slit channel is studied theoretically and by numerical simulations. The term TAE refers to electrolytes whose charge carrier concentration is a function of temperature, as recently suggested for ionic liquids and highly concentrated aqueous electrolyte solutions. Two competing mechanisms driving charge transport by temperature gradients are identified. For suitable values of the activation energy that governs the generation of charge carriers, a giant thermoelectric response is found, which could help explain recent experimental results for nanoporous media infiltrated with TAEs.

Dielectric Response and Linear Absorption Spectroscopy of Ionic Systems.

Time-dependent electric fields applied to ionic systems can induce both a dielectric and a conductive response, leading to the generation of macroscopic polarization and current, respectively. It has long been recognized that it is not possible to determine the two types of responses separately. However, this aspect is often not adequately accounted for in dielectric and absorption spectroscopies of ionic systems. To clarify this, we theoretically investigate the dielectric and conductive responses of ionic systems containing polyatomic ions based on linear response theory. We derive general expressions for the frequency-dependent dielectric functions, conductivity, and absorption coefficient, including those measured experimentally. Furthermore, we show that the dielectric and conductive responses cannot be uniquely distinguished even at the theoretical level and, therefore, cannot represent experimentally measured quantities. Instead, dielectric and absorption spectra of ionic systems should be expressed in terms of the generalized dielectric function that encompasses both dielectric and conductive responses. We propose a computational method to calculate this generalized dielectric function reliably. Model calculations on concentrated aqueous solutions of NaCl, a monatomic salt, and LiTFSI, a polyatomic salt, show that the dielectric and linear absorption spectra of the two systems based on the generalized dielectric function are significantly different from purely dielectric counterparts in the far-IR, terahertz, and lower-frequency regions. Moreover, the spectra are mainly determined by the autocorrelations of total dipole and total current, but dipole-current cross-correlation can also significantly contribute to the spectra of the LiTFSI solution. The present theoretical approach could be extended to nonlinear spectroscopy of ionic liquids and electrolyte solutions.

Engineering Ultrasoft Interactions in Stiff All-DNA Dendrimers by Site-Specific Control of Scaffold Flexibility.

A combined experimental and theoretical study of the structural correlations in moderately concentrated suspensions of all-DNA dendrimers of the second generation (G2) with controlled scaffold rigidity is reported here. Small-angle X-ray scattering experiments in concentrated aqueous saline solutions of stiff all-DNA G2 dendritic constructs reveal a novel anomalous liquid-like phase behavior which is reflected in the calculated structure factors as a two-step increase at low scattering wave vectors. By developing a new design strategy for adjusting the particle's internal flexibility based on site-selective incorporation of single-stranded DNA linkers into the dendritic scaffold, it is shown that this unconventional type of self-organization is strongly contingent on the dendrimer's stiffness. A comprehensive computer simulation study employing dendritic models with different levels of coarse-graining, and two theoretical approaches based on effective, pair-potential interactions, remarkably confirmed the origin of this unusual liquid-like behavior. The results demonstrate that the precise control of the internal structure of the dendritic scaffold conferred by the DNA can be potentially used to engineer a rich palette of novel ultrasoft interaction potentials that could offer a route for directed self-assembly of intriguing soft matter phases and experimental realizations of a host of unusual phenomena theoretically predicted for ultrasoft interactingsystems.

3D printing sequentially strengthening high-strength natural polymer hydrogel bilayer scaffold for cornea regeneration.

3D printing of high-strength natural polymer biodegradable hydrogel scaffolds simultaneously resembling the biomechanics of corneal tissue and facilitating tissue regeneration remains a huge challenge due to the inherent brittleness of natural polymer hydrogels and the demanding requirements of printing. Herein, concentrated aqueous solutions of gelatin and carbohydrazide-modified alginate (Gel/Alg-CDH) are blended to form a natural polymer hydrogel ink, where the hydrazides in Alg-CDH are found to form strong hydrogen bonds with the gelatin. The hydrogen-bonding-strengthened Gel/Alg-CDH hydrogel demonstrates an appropriate thickened viscosity and shear thinning for extrusion printing. The strong hydrogen bonds contribute to remarkably increased mechanical properties of Gel/Alg-CDH hydrogel with a maximum elongation of over 400%. In addition, sequentially Ca2+-physical crosslinking and then moderately chemical crosslinking significantly enhance the mechanical properties of Gel/Alg-CDH hydrogels that ultimately exhibit an intriguing J-shaped stress-strain curve (tensile strength of 1.068 MPa and the toughness of 677.6 kJ/m2). The dually crosslinked Gel-Alg-CDH-Ca2+-EDC hydrogels demonstrate a high transparency, physiological swelling stability and rapid enzymatic degradability, as well as suturability. The growth factor and drug-loaded biomimetic bilayer hydrogel scaffold are customized via a multi-nozzle printing system. This bioactive bilayer hydrogel scaffold considerably promotes regeneration of corneal epithelium and stroma and inhibits cornea scarring in rabbit cornea keratoplasty.

Fundamental Understanding of the Behavior Under Aging of Aqueous Magnesium-Based Concentrated Electrolytes

The concept of water-in-salt electrolytes (WISEs)1, implying highly concentrated aqueous solutions, has completely rejuvenated the aqueous systems. These electrolytes can be depicted as few water molecules surrounded by cations and anions forming ion pairs. This change of solvation structure compared to standard electrolytes increases the electrochemical stability window. For example, using 20 molal (molality: m, moles per kg) lithium (bistrifluoromethanesulfonyl(imide) (LiTFSI) aqueous solutions, a stability window of 3 V is reached.1 While WISEs open the way for sustainable systems, these solutions only use expensive and toxic lithium salts. To move towards more sustainable elements, one can envision magnesium and associated salts: safer, less expensive and more abundant than lithium. Yet, the state-of-the-art on water-in-salt aqueous Mg batteries is scarce,2,3 with potential windows reaching only 2-2.3 V. There is no clear understanding of the mechanisms at work but the low solubility of Mg salts could account for the narrow potential window. Rationalizing reactivity of water-in-salt solutions on a fundamental level is critical to design efficient strategies to increase the voltage window of concentrated aqueous Mg batteries. We investigated the Mg(TFSI)2/H2O system with radiolysis, a technique which provides a chemical approach4 to exacerbate in a short time the degradation mechanisms. The aging process with radiolysis is much shorter than the electrochemical one and mimics the products of salt and solvent degradation observed during long battery operation. We performed radiolysis to study and compare Mg(TFSI)2 and LiTFSI-based electrolytes with different molalities. Degradation products formed after irradiation were identified using Nuclear Magnetic Resonance spectroscopy (NMR) for the liquid phase, and with gas chromatography coupled to mass spectrometry (GC-MS) and micro-gas chromatography (μ-GC) for the gas phase. For example, the evolution of the amount of H2 and CO2 gases in the case of LiTFSI or Mg(TFSI)2/H2O electrolytes show large discrepancies, hinting at a preferential anion degradation in the Mg system. Overall, the nature of the degradation species strongly depends on the molality, with degradation routes driven by the water or the anion at low or high molalities. Finally, radiolysis allows to identify minor species, providing a view of the long-term (un)stability of these electrolytes.

Macromolecular vs molecular crowding in aqueous solutions: A comparative study of PEG400 and ethylene glycol

Concentrated solutions, also known as crowded solutions, are known to provide a very different environment for dissolved solutes than dilute solutions. Understanding the molecular origin of these differences is important not only for a fundamental understanding of the properties of solutions, but also for the applicative implications. The latter range from making in vitro biochemical assays more similar to in vivo conditions, to the design of aqueous matrices in which the activity of water is reduced (e.g. for batteries). Using a combined computational-experimental approach, we compare the hydration properties of concentrated aqueous solutions of a polymer with an analogue of its monomeric unit in water. The aim of this work is to disentangle the effects related to the chemical nature of a solute from those related to its dimension, and for this purpose we have studied the pair polyethylene glycol, ethylene glycol (PEG versus EG). The analysis of increasingly concentrated solutions of the two systems reveals a completely different microscopic behaviour, in which the different clustering/aggregation of both solutes and water plays the main role. Indeed, water within EG solutions primarily constitutes high-density hydrating water, whereas PEG solutions exhibit confined, bulk-like water patches. These findings indicate that molecular crowding could potentially exhibit greater efficacy than macromolecular crowding in all applications requiring a reduction in water activity.

Transparent regenerated cellulose film containing azobenzene group with reversible stimulus discoloration property

The cellulose film, exhibiting color alterations in response to external stimuli, presents itself as a promising functional material. In this study, a universal dissolution-regeneration technique was employed to manufacture a transparent, regenerated cellulose film, characterized by its reversible multi-stimulus discoloration property. This functional cellulose film, endowed with both photochromic and acid-chromic attributes, was synthesized through the introduction of a cellulose-grafted azobenzene derivative into the cellulose solution. The hue of a cellulose film irradiated with ultraviolet light could be inverted upon exposure to visible light or heat. Furthermore, when subject to heating, irradiation, or immersion in an acidic medium, this functional film demonstrated pronounced transparency. The acid-chromic behavior of the film was readily discernible when exposed to highly concentrated acidic aqueous solutions. Both the photochromic and acid-chromic phenomena were discernable to the unaided eye. After ten cycles, no fading of the reversible discoloration properties of the material occurred. This transparent regenerated cellulose film stands as a viable candidate for applications in optical data storage, intelligent switches, and sensors, owing to its capacity for reversible stimulus-triggered discoloration.

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.