LiOH Solution Research Articles

Fabrication of N,C-H2TiO3 Ion Sieves for Rapid Adsorption of Lithium Using Rheological Phase Methods

Modifying β-H2TiO3 by elemental doping improves its adsorption capacity and shortens the equilibrium adsorption time, which is of positive significance for its industrial application.Herein, a novel N, C co-doped Li2TiO3 lithium ion sieve precursor N,C-Li2TiO3-3 (noted as N,C-LTO-3) was successfully prepared via the rheological phase method using urea as a vital raw material. Crystal structure of N,C-LTO-3 was characterized via XRD, XPS, FT-IR, and Raman. The morphology of N,C-LTO-3 was analysed by SEM and HR-TEM. The N,C-LTO-3 was pickled and obtained to N,C-H2TiO3-3, namely N,C-HTO-3. The equilibrium adsorption capacity (Qe) of N,C-HTO-3 was as high as 40.6mg⋅g-1 in LiOH solution of 100mg·L-1 at 293K. Ti4+ dissolution loss rate is below 0.5% in the fifth cycle. Adsorption isothermal curve, kinetics, and thermodynamic behaviour were fitted with the according equations. The exchange energy of N,C-HTO-3 for Li+ was calculated by density functional theory (DFT) to assess the feasibility of lithium absorption. Furthermore, N,C-HTO-3 exhibited high regeneration and selectivity for Li+ in lithium-containing brine, making N,C-HTO-3 an ideal candidate for Li+ extraction.

Ethanol Oxidation Reaction on Electrodeposited Pd and Sb‒Pd Catalysts in Alkaline Solution Containing Na or Li Cations

Abstract This work reports the galvanostatical electrodeposition of Pd and Sb‒Pd catalysts on rotating glassy carbon (GC) electrode using surfactant-free electrolytes and the prepared catalysts were tested is the electro-oxidation reactions in alkaline solutions. Characterization of Pd and Sb‒Pd catalysts was performed with scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) technique. Cyclic voltammetry (CV) and chronoamperometry were applied in order to study the electrocatalytic behavior of Pd and Sb‒Pd catalysts in the ethanol oxidation reaction (EOR) in alkaline solution containing Na+ or Li+ cations from the point of the impact of the selected alkali metal cations on the electrocatalytic activity. The peak current of EOR at Pd and Sb‒Pd catalysts in the solution with Li+ cations is 2.5 times higher compared to the values obtained in the solution with Na+ cations. EOR starts at rather negative potentials in LiOH solution regarding NaOH for approximately 0.03 V indicating the active role of OHad and the impact of the nature of alkali metal cations which consequently arises from the formation of OHad ‒ cation clusters. The role of Sb in bimetallic catalyst was established by adjusting the extent and persistence of OHad surface coverage.

Corrosion of Chromium Coating Fabricated on Zircaloy-4 Substrate.

In the nuclear industry, coated cladding is a topical problem and it is chosen as the near-term and most promising ATF (Accident-Tolerant Fuel) cladding concept. The main objective of this concept is to enhance the accident tolerance of nuclear power plants and accordingly, the performance of cladding is expected to be improved. This work assesses the corrosion performance of a Zircalloy-4 alloy coated with a thin chromium coating by MS (magnetron sputtering), tested under a CANDU (CANada Deuterium Uranium) reactor primary circuit simulated condition (LiOH solution, 10 MPa, 310 °C, pH = 10.5). The anticorrosive performance is evaluated by a gravimetric analysis, a metallographic analysis, X-ray diffraction, electronic microscopy, and electrochemical methods. A four times less gain mass was noticed compared to uncoated Zircaloy-4, indicating a smaller corrosion rate. The SEM micrographs illustrate that the coatings are still adherent, and they are keeping the initial morphological characteristics during the autoclaving process. A SEM cross-section analysis shows values of the thickness of the coatings between 0.8 and 1.46 µm. By XRD, the presence of Cr2O3 oxide is identified. Electrochemical testing confirms good stability and good corrosion performance of Cr coating over time under autoclave conditions.

Modeling and Experimental Validation on a Bipolar Membrane Electrodialysis Stack for Lithium Sulfate Separation

Recycling lithium-ion battery materials is a crucial step to achieving a circular economy. Among a few methods for recycling spent battery materials, a novel hydrometallurgical recycling process with leaching by acids and precipitation by bases was proposed [1]. Lithium sulfate (Li2SO4) leachate solution is generated at the end of the closed-loop recycling process. Such Li2SO4 solution can be separated by electrodialysis (ED) to form H2SO4 and LiOH solutions, which are reused for leaching and precipitation of the recycling process. The present study attempts to model this ED process and validate the model with experimental data.An ED stack based on bipolar membranes (EDBM); see Fig. 1a, was built with repetitive unit cells, each consisting of a bipolar membrane, anion exchange membrane (AEM), and cation exchange membrane (CEM). Li2SO4 enters the dilute channel and splits into SO4 2- and Li+, which travel through the AEM and CEM, respectively. Water electrolysis occurs within the bipolar membrane to produce H+ and OH-, which react with SO4 2- and Li+ to form H2SO4 and LiOH, respectively; see Fig. 1b. A two-dimensional (2D) multiphysics model is developed to elucidate the coupled transport processes within the unit cell. Conservation equations for mass, momentum, and species are solved. The transport of ions is described by the Nernst-Planck equation. Electroneutrality equations are satisfied in these membranes and channels. Electro-osmotic water transport across the membranes is considered.The effective cross-sectional area of the stack was 121.8 cm2 (70mm×174mm). The flow channel between consecutive membranes was 0.8 mm, with a mesh inserted to facilitate mixing. Experiments were carried out with the EDBM stack over different conditions such as current density, number of cell pairs, and flow rates. All experiments were operated at constant current mode [2]. The feed, acid, and base solutions were recirculated through their tanks at initial concentrations of 1.1, 0.1, and 0.1 mol/L. The ion concentrations of the solutions were measured periodically with inductively coupled plasma (ICP) mass spectrometry. The weight and the pH value of the solution tanks were also recorded.The concentration of H2SO4 is found to increase with time linearly, whereas that of LiOH levels off due to a significant electro-osmosis that drags water through the CEM into the concentrate channel. This drag reduces the performance of EDBM due to the dilution of water into the concentrate compartment. However, electro-osmotic water transport also leads to a velocity increase in the concentrate channel, which is consistent with the simulation results in our previous ED model [3]. It is found that the voltage loss across the bipolar membrane ca. 1V accounts for a significant part of the unit cell of about 1.27V.The migration of ions in electrodialysis mainly relies on diffusion and electric drive. The streamlines and the concentration distribution of Li+ under different voltages indicate that increasing voltage accelerates ion migration, see Fig. 1(c). Furthermore, the effect of the potential and concentration variations on EDBM performance is also investigated. The effects of applied current density and inlet velocity are studied on species concentrations and fluxes. Increasing the stack current density accelerates the separation process, see Fig. 1(d). It is found that increasing the solution flow rate can increase LiOH solution concentration, ion recovery rate, and current efficiency. However, the impact of the flow rate is low.This work demonstrates that EDBM can be a simple and energy-saving alternative to the current chemical precipitation method to produce LiOH from Li2SO4. The present study provides new insights into optimal operation and design for Li2SO4 EDBM. The findings are helpful in determining how the stack can be scaled up for practical application.[1] A review of recycling spent lithium-ion battery cathode materials using hydrometallurgical treatments, JCY Jung, PC Sui, J Zhang, J. Energy Storage 35, 102217, 2021.[2] Electrodialysis of a Lithium Sulphate Solution: An Experimental Investigation. B Kang, D Kang, JCY Jung, A Asadi, PC Sui, J. Electrochem. Soc. 169 (6), 063515, 2022.[3] A Comprehensive Computational Fluid Dynamics Modeling of Lithium Sulphate Electrodialysis, A Asadi, HB Harandi, JCY Jung, PC Sui, J. Electrochem. Soc. 170(9), 093502, 2023. Figure 1

Practical surface-reconstruction strategy based on self-reactive interface design enables ultralong cyclability of commercial cathodes for lithium-ion batteries

Although Al-doped high-voltage LiCoO2 (HVLCO) cathode has been widely used in commercial lithium-ion batteries, it still suffers from poor cycling stability due to its unstable surface/interface structure causing bad side reactions. Herein, a surface reconstruction strategy based on self-reactive interface design has been proposed, to construct a uniform and ultrathin (∼ 5 nm) LiAlO2 (LAO) layer on the surface of HVLCO cathodes. The construction of LAO layer is realized by a facile and scalable process involving chemical immersion in LiOH solution and subsequent heating treatment. Moreover, the LAO coating layer imparts both lower interior stress upon lithiation and lower migration energy barrier of Li ions, guaranteeing stable and rapid lithium storage, which is confirmed by substantial characterizations and theory calculations. Consequently, ultralong cycle life over 10,000 h (1000 cycles) at 0.1 C is achieved for the surface-reconstructed HVLCO cathode, with an 86% capacity retention. Especially, different kinds of commercial HVLCO products as well as NCM (LiNi0.6Co0.2Mn0.2O2) cathode material, after the same surface reconstruction, also show remarkably reinforced electrochemical performance. This practical surface-reconstruction strategy may serve as a useful guideline for future design and performance optimization of commercial cathode materials.

Effect of Boron Content in LiOH Solutions on the Corrosion Behavior of Zr-Sn-Nb Alloy.

In pressurized water reactors, LiOH may be concentrated in some areas, leading to the accelerated corrosion of fuel claddings. Injecting boric acid into primary coolants can mitigate the accelerated corrosion effect of LiOH on Zircaloys, but the effects of boron content on the corrosion behavior of the Zr-Sn-Nb alloy are still unknown. This work focused on the corrosion and hydrogen absorption behavior at 360 °C/18.6 MPa in 100 mg/kg LiOH solutions with 0 mg/kg, 50 mg/kg, and 200 mg/kg boron contents for up to 510 days, aiming to study the effect of boron content on corrosion resistance in LiOH solutions. Corrosion kinetics, microstructures of oxide films, hydrogen absorption concentrations and hydride morphology were obtained after the test. The results show that injecting boron in LiOH solutions can significantly reduce the corrosion weight gain, hydrogen concentration, and hydrogen length of Zr-Sn-Nb alloys, that is, improving corrosion resistance effectively. During the oxidation of the Zr-Sn-Nb alloy, B3+ and Li+ incorporate in oxide films. The incorporation of Li+ may lead to the generation of oxygen vacancies, which can carry oxygen from the solutions to O/M interface, accelerating corrosion. The incorporation of B3+ in oxide films will slow down the oxidation of Zr-Sn-Nb alloys by reducing the oxygen vacancies caused by Li+ aggregation.

Effects of cell configuration and bipolar membrane on preparation of LiOH through bipolar membrane electrodialysis from salt lake brine

Bipolar membrane electrodialysis (BMED) is a promising process to prepare LiOH from the salt lake brine. Revealing the effects of the cell configuration and property of bipolar membrane (BM) on the mass transfer and current efficiency of BMED is crucial to promote its industrial application. Herein, two-compartment (C-B) and three-compartment (A-C-B), and three types of BMs (FBM, BP-1, and TWBP1) were systematically studied. Results show that three-compartment is superior to two-compartment, as the latter could restrain electromigration of Li+, enable recombination of H+ and OH–, and lead to lower current efficiency. Among three BMs, TWBP1 has highest current efficiency, while BP-1 can prepare LiOH solution with least impurity ions. To reveal the influencing mechanism of the BMs’ properties on the electromigration of Li+ and co-ions leakage, CVC curves and chronopotentiograms were detailly investigated. Results show that the higher energy consumption of BP-1 may be attributed to its highest specific resistivity, while its better co-ions selectivity is beneficial to prepare acid/base solutions with lesser impurities, indicating that effects of the specific resistivity and selectivity of BMs on BMED process for producing LiOH from salt lake brine is an important “trade-off” relationship needing to be balanced to realize the higher current efficiency and higher quality products.

Corrosion and fretting-corrosion behavior of Zr-Nb alloy under aqueous LiOH solution

Zirconium alloys are the key materials for nuclear reactor’s core components due to low neutron cross-section and good mechanical and corrosion properties. During operation in nuclear reactor, some core components (exposed to the corrosive environment of coolant water having LiOH) may undergo corrosion and fretting-corrosion. This work presents a novel experimental approach for investigating the Zr-2.5 Nb alloy's corrosion and in-situ fretting-corrosion response. The corrosion analysis was performed using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization, to study the effect of LiOH concentration in water and exposure duration. It is observed that the corrosion rate increases with increasing the concentration of LiOH in water and decreases with increasing the exposure duration. The fretting-corrosion tests were performed between SS-410 and Zr-2.5 Nb in aqueous LiOH solution. The results reveal that the contact resistance and coefficient of friction (COF) decrease with increasing concentration of LiOH in the solution. The present work highlights the scientific understanding of corrosion and fretting-corrosion phenomena in zirconium alloy and elucidates key mechanisms and factors governing the degradation behavior which can help in preventing the failure of the components.

Development of a sustainable geopolymer using blast furnace slag and lithium hydroxide

Ground Granulated Blast furnace Slag (GGBS) is a promising alternative to ordinary Portland cement due to its potential to reduce CO2 emissions. However, the limited binding capability of pure GGBS necessitates the use of alkaline activators to enhance its hydration behaviour. The present work establishes the use of lithium hydroxide (LiOH), which can be synthesized by recycling lithium-ion batteries, as an effective alkaline activator for GGBS. Experimental results demonstrate that a 10 M LiOH solution enhances the hydration of GGBS 36 folds. LiOH activated GGBS exhibits the presence of hydration products such as lithium-alumino-silicate-hydrate and calcium-silicate-hydrate from day 1 of hydration, while GGBS mixed with DI water shows onset of hydration only after 28 days. Thermogravimetry results from long-term hydration studies indicate that LiOH activated GGBS forms a 73% higher quantity of hydration products as compared to cement paste samples. Additionally, LiOH activated GGBS demonstrates 42% and 46% higher compressive strength than GGBS activated with NaOH and Na2SiO3 at 7 and 28 days, respectively. Embodied energy analysis reveals that geopolymer prepared with GGBS and recycled LiOH leads to equivalent CO2 emissions reduction of 83% compared to NaOH based geopolymer and 85% compared to cement concrete.

Fabrication and application of a continuously regenerated cationic impurity removal device for ion chromatography

A continuously regenerated cationic impurity removal device (CR-CRD) has been fabricated and applied for ion chromatography (IC). The removal of cationic impurities is realized by electrodialytically replacing the cationic impurities with hydronium ions. The device is configured in a sandwich structure and the central eluent channel is respectively isolated from both electrodes by stacked cation exchange membranes and a bipolar membrane (BPM) plus stacked anion exchange membranes. The eluent channel is packed with cation exchange resins in hydronium form and their continuous regeneration can be achieved by electrodialysis. A desirable feature of the device is gas-free, and no degasser is required. It showed sufficient ability to remove cationic impurities, as indicated by > 99.9 % removal of 10 mL of 1 mM LiOH solution injected (∼10 μmol) or continuous removal of 1 mM LiOH solution at the flow rate of 1 mL/min (1 μmol/min). A useful application was for sample pretreatment in nuclear power industry, by eliminating strong matrix interference of the sample containing LiOH (1 mM) and boric acid (2000 mg/L) with trace anion analysis.

Tribological and corrosion behavior of hydrided zirconium alloy

Zirconium alloys (Zr-alloys) are used for the core components of nuclear reactors due to their exceptional properties, which make them suitable for the given applications such as low neutron absorption cross-section, good corrosion resistance, good wear resistance, good mechanical stability at high temperatures etc. The coolant water that flows inside the pressure tube contains LiOH to control the pH value of the coolant water, which can cause corrosion. The flow of coolant water produces low amplitude vibration, which can cause fretting wear of the components. Further, the coolant water at high temperature causes the hydride formation in the material, degrading the properties of zirconium alloys. The safe working of nuclear reactors is the prime objective, and the corrosion and wear behavior of the core components must be explored to prevent possible failure. Fretting wear or tribo-corrosion experiments were conducted on Zr‐2.5Nb alloy against SS-410 for varied fretting duration to understand the tribological response. Electrochemical corrosion experiments were performed under the aqueous solution of LiOH (10.4 pH) using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization technique. The comparison was made between the tribological and corrosion response of unhydrided‐Zr‐2.5Nb alloy (Zr‐2.5Nb) and hydrided- Zr‐2.5Nb alloy (Zr‐2.5Nb‐H). The hydride formation causes the reduction in corrosion resistance of Zr‐2.5Nb alloy. The oxide layer is formed during the wear and corrosion process which protects the material from further wear and corrosion respectively.

Conversion of Lithium Chloride into Lithium Hydroxide Using a Two-Step Solvent Extraction Process in an Agitated Kühni Column

A significant consequence of the green transition is the growing demand of lithium-ion batteries (LIBs), as they are essential for electrical vehicles. In turn, the demand for the raw materials that are needed to produce LIBs is increasing. A common LIB cathode type for electrical cars is lithium nickel manganese cobalt oxide (NMC). Since cobalt is currently considered as a critical raw material, nickel-rich NMC cathodes are now designed with lower cobalt contents. The synthesis of these new NMC types requires LiOH instead of Li2CO3, which was used for Co-richer NMC materials in the past. Most production routes of LiOH start from Li2CO3 or Li2SO4. However, LiCl could also be a potential precursor for LiOH, as it could be obtained from various lithium sources. A two-step solvent extraction process (SX) was developed for direct conversion of LiCl into LiOH, using a phenol (butylhydroxytoluene or BHT) and a mixture of quaternary ammonium chlorides (Aliquat 336) in an aliphatic diluent (Shellsol D70) as the solvent. The SX process was validated in counter-current mode using a rotary agitated Kühni extraction column. The use of a column instead of mixer-settlers reduced the CO2 uptake by the final product (LiOH), which prevented the partial conversion of LiOH to Li2CO3. A total of 75 L of LiCl feed solution was processed in the Kühni column to obtain a solution of LiOH with a final purity of more than 99.95%, at a yield of 96%.Graphical

Tracing the impact of CO2 on the electrochemical and charge–discharge behavior for Al–Mg alloy in KOH and LiOH electrolytes for battery applications

For the first time, it has been found that the electrochemical performance of the Al–Mg alloy as an anode in alkaline batteries has been markedly enhanced in the presence of CO2 and LiOH as an electrolyte. This work compares the electrochemical performance of an Al–Mg alloy used as an anode in Al-air batteries in KOH and LiOH solutions, both with and without CO2. Potentiodynamic polarization (Tafel), charging-discharging (galvanostatic) experiments, and electrochemical impedance spectroscopy (EIS) are used. X-ray diffraction spectroscopy (XRD) and a scanning electron microscope (SEM) outfitted with an energetic-dispersive X-ray spectroscope (EDX) were utilized for the investigation of the products on the corroded surface of the electrode. Findings revealed that the examined electrode’s density of corrosion current (icorr.) density in pure LiOH is significantly lower than in pure KOH (1 M). Nevertheless, in the two CO2-containing solutions investigated, icorr. significantly decreased. The corrosion rate of the examined alloy in the two studied basic solutions with and without CO2 drops in the following order: KOH > LiOH > KOH + CO2 > LiOH + CO2. The obtained results from galvanostatic charge–discharge measurements showed excellent performance of the battery in both LiOH and KOH containing CO2. The electrochemical findings and the XRD, SEM, and EDX results illustrations are in good accordance.

Effect of lithium on the atmospheric corrosion characteristics of TZM as the first-wall material in EAST

The effect of Lithium (Li) coating on the corrosion behavior of molybdenum-titanium-zirconium (TZM) alloy was investigated in low- and high-humidity air at room temperature (RT). Additionally, the corrosion mechanism was also studied through immersion tests in deionized water and LiOH solution. The test results confirm that the corrosion of the TZM alloy depends on the presence of H2O and O2, particularly H2O. In environments with high humidity, the TZM surface without Li coating easily undergoes oxidation, resulting in the formation of dark-green MoO3·xH2O. The Li coating significantly accelerates the surface oxidation of the TZM alloy because of its high absorptive properties for H2O, O2, and CO2, thereby generating Li2O, LiOH, and Li2CO3. These processes lead to a high content of O2 and H2O near the TZM surface, facilitating the formation of MoO3·xH2O. The immersion of TZM in water also leads to oxidative corrosion, which is more severe than that in high humidity air because of the dissolution of MoO3, causing the water to become dark-green. The oxidation of TZM in LiOH solution exhibits a behavior similar to that of water immersion. However, the corrosion in the LiOH solution is more severe because of the reaction between the surface oxide MoO3 and LiOH, which forms a colorless Li2MoO4, accelerating the corrosion process. This study offers valuable insights into the effective anti-corrosion strategies for the cleaning and storage of the TZM wall material in the EAST tokamak.

Polymorphism and Structural Variety in Sn(II) Carboxylate Coordination Polymers Revealed from Structure Solution of Microcrystals.

The crystal structures of four coordination polymers constructed from Sn(II) and polydentate carboxylate ligands are reported. All are prepared under hydrothermal conditions in KOH or LiOH solutions (either water or methanol-water) at 130-180°C and crystallize as small crystals, microns or less in size. Single-crystal structure solution and refinement are performed using synchrotron X-ray diffraction for two materials and using 3D electron diffraction (3DED) for the others. Sn2 (1,3,5-BTC)(OH), where 1,3,5-BTC is benzene-1,3,5-tricarboxylate, is a new polymorph of this composition and has a three-dimensionally connected structure with potential for porosity. Sn(H-1,3,5-BTC) retains a partially protonated ligand and has a 1D chain structure bound by hydrogen bonding via ─COOH groups. Sn(H-1,2,4-BTC) contains an isomeric ligand, benzene-1,2,4-tricarboxylate, and contains inorganic chains in a layered structure held by hydrogen bonding. Sn2 (DOBDC), where DOBDC is 2,5-dioxido-benzene-1,4-dicarboxylate, is a new polymorph for this composition and has a three-dimensionally connected structure where both carboxylate and oxido groups bind to the tin centers to create a dense network with dimers of tin. In all materials, the Sn centers are found in highly asymmetric coordination, as expected for Sn(II). For all materials phase purity of the bulk is confirmed using powder X-ray diffraction, thermogravimetric analysis, and infrared spectroscopy.

Utilization of lithium sulphate electrodialysis for closed-loop LIB recycling: Experimental study and process simulation

The hydrometallurgical recycling of spent lithium-ion batteries (LIBs) frequently relies on sodium hydroxide and sodium carbonate. This process generates a sodium-enriched solution, requiring treatment prior to safe discharge. This study focuses on a closed-loop recycling process for spent Lithium Nickel Manganese Cobalt Oxide (NMC) cathode material, eliminating sodium ions from conventional hydrometallurgical methods and regenerating acid and precipitant from disposal slurry. It employs lithium hydroxide (LiOH) as the precipitating reagent, while lithium recovery is conducted employing electrodialysis (ED) to regenerate LiOH and sulfuric acid (H2SO4) from the lithium sulfate solution. A part of the LiOH and H2SO4 reagents are subsequently used for the leaching and precipitation steps, creating a closed-loop recycling process. An experimental setup was developed to study the leaching, impurity removal, and metal extraction processes. The closed-loop recycling process was further investigated by simulation of this process. This involved the development of the ED module in both continuous and batch configurations using the Aspen Custom Modeler. This ED module is incorporated into Aspen Plus to integrate with the recycling process under experimental operational conditions. The minimal deviations of 3.34% and 2.38% within the precipitation and co-precipitation processes indicated the accuracy and validity of this work. Utilizing multiple batch-mode ED cells yields a 25% higher recovery of LiOH solution compared to continuous ED cells in the same operation conditions, i.e., employing 48 cells for 96 min under a current density of 1100 A·m−2. Furthermore, increasing the leaching temperature by 60°C yields a 53% increase in lithium leaching efficiency.

Influence of Synthesis Conditions on Chabazite Zeolite Crystallization in LiOH Solution

Influence of Synthesis Conditions on Chabazite Zeolite Crystallization in LiOH Solution

Molten salt-shielded synthesis of Ti3AlC2 as a precursor for large-scale preparation of Ti3C2Tx MXene binder-free film electrode supercapacitors.

MXenes are a group of two-dimensional materials that are promising for many applications, including as film electrode supercapacitors. When synthesizing such materials, special attention is paid to the conditions for obtaining the MAX phase, the chemical, morphological and structural features of which determine the functional properties of the final product. In this study, the Ti3AlC2 precursor is proposed to be obtained using a technologically simple and accessible method of synthesis in molten salt. This method allows reducing the reaction temperature and creating an antioxidant atmosphere. Ti3C2Tx MXene electrode films are produced by the easily scalable blade coating method without a binder. The synthesized materials were studied by X-ray phase analysis and scanning electron microscopy. Electrochemical testing of Ti3C2Tx film electrodes was carried out in a three-electrode configuration in aqueous solutions of 1M H2SO4, 6M KOH, 1M LiOH and 1M Na2SO4 electrolytes. The maximum specific capacity value for Ti3C2Tx MXene binder-free film electrode supercapacitors is obtained in 1M H2SO4 electrolyte (480 F g-1 at a scan rate of 1 mV s-1). The simple, low-cost and scalable production technology and promising electrochemical characteristics of the Ti3C2Tx MXene binder-free film electrode make it an excellent candidate for new-generation supercapacitors.

Electrodialysis of Lithium Sulfate Solutions from Hydrometallurgical Recycling of Spent Lithium-Ion Batteries

Recycling lithium-ion battery materials is a crucial step to achieving a circular economy. A hydrometallurgical recycling process of spent lithium-ion battery materials involves leaching by acids and precipitation by bases. A large amount of Li2SO4 leachate solution is generated at the end of the recycling process. Such Li2SO4 solution can be separated by electrodialysis (ED) to form H2SO4 and LiOH solutions, which are reused for leaching and precipitation, respectively, making the recycling a closed-loop process. In this study, an ‘electrodialysis stack constructed with bipolar membranes’ (EDBM) is built with repetitive unit cells consisting of a bipolar membrane, anion exchange membrane (AEM), and cation exchange membrane (CEM), see Fig. 1(a). The effective area for each membrane is 121.8 cm2 (70mm×174mm). The gap between these membranes is 0.8mm, with a mesh inserted to allow flow mixing. All experiments were operated at constant current mode. The feed, acid, and base solutions were recirculated through their tanks at initial concentrations of 1.1, 0.1, and 0.1 mol/L. The ion concentrations of the solutions were measured with Inductively coupled plasma mass spectrometry periodically. The weight and the pH value of the solution tanks were also recorded.The trend of concentration variations of the present stack with up to 6 cell pairs is found to be consistent with that observed with a three-compartment configuration in our previous study [1]. The concentration of H2SO4 increases with time linearly, whereas that of LiOH levels off due to a significant electro-osmosis that drags water through the CEM into the concentrate channel. The present setup differs from the three-compartment design in the bipolar membrane, which splits water to produce H+ and OH- at the internal interface, eliminating the formation of bubbly flows in the unit cell. It is found that the voltage loss across the bipolar membrane ca. 1V accounts for a major part of the unit cell of about 1.27V.The effects of current density, number of cell pairs, and flow rates on the overall stack performance are investigated. Increasing the stack current density accelerates the separation process at the cost of higher voltage losses. It is found that increasing the number of cell pairs can improve the overall production efficiency and reduce energy consumption per cell pair. For instance, at 800 A/m2, the specific energy consumption for LiOH production is reduced to 3.40 kWh/kg with five cell pairs versus 5.83 kWh/kg with two cell pairs. It is also found that increasing the solution flow rate can result into the increase of LiOH solution concentration, ion recovery rate, and current efficiency (Fig. 1b), although the impact of flow rate is low.A small EDBM stack is constructed and tested for Li2SO4 separation in the present study. This work demonstrates that EDBM can be a simple and energy-saving alternative to the current chemical precipitation method to produce LiOH from Li2SO4. The present study provides new insights into optimal operation and design for Li2SO4 EDBM. The findings are helpful in determining how the stack can be scaled up for practical application. Furthermore, a 2D multiphysics model is currently under development to elucidate the coupled transport processes within the unit cell. The model will be validated with experimental data of the present setup. Figure 1

Selective dissolution and kinetics of leaching zinc from lime treated electric arc furnace dust by alkaline media

The EAF steelmaking process generates 10–20 kg of dust per ton of steel, containing 15–30% zinc, making it a valuable secondary zinc resource. In this work, selective dissolution and kinetics of leaching zinc from lime (CaO) treated EAF dust using NaOH, KOH, and LiOH alkaline solutions were investigated. By reacting with CaO, insoluble ZnFe2O4 in EAF dust is converted to soluble ZnO and stable Ca2Fe2O5. Optimal zinc leaching conditions were achieved after 2 h at 70 °C and a S/L ratio of 1/300 (mg/ml). Among the alkaline solutions used, the zinc leaching rate was highest using 2 M NaOH solution at 99% zinc recovery. On the other hand, thermodynamic solubility calculations indicate that KOH is a better candidate for practical extraction as it can dissolve 6–8 times more zinc than NaOH. The prevailing rate-controlling mechanisms when using NaOH, KOH, and LiOH solutions were found to be the same. From 25 °C to 50 °C, chemical reaction was primarily rate-limiting. In contrast, from 50 °C to 70 °C, the controlling step later shifted to a product layer diffusion control – implying that higher temperatures and finer particle size are vital to achieving high zinc leaching rates. Finally, a solid by-product containing Ca2Fe2O5 and CaO only, which can be recycled in the iron and steelmaking process, was obtained via calcination at 500 °C.