Effects of excessive lithium deintercalation on Li+ adsorption performance and structural stability of lithium/aluminum layered double hydroxides

Adsorption of lithium ions from aqueous solution by magnetic aluminum-based adsorbents

Magnetic aluminum-based adsorbents (MLDHs) were prepared with a coprecipitation method and used to separate lithium ions from the aqueous solutions. In static adsorption experiment, the adsorption capacity of MLDHs for lithium ions reached 8.22 mg/g. In a mixed solution of various metal ions, the adsorbents exhibited higher selectivity for lithium ions. Kinetic studies indicated that the adsorption process conformed to a pseudo-second-order model. The experimental data were fitted with nonlinear regression using commonly used adsorption isotherms. It was found that the adsorption isotherm process could be described by the Langmuir model. In addition, the thermodynamic parameters revealed that the adsorption of lithium was a spontaneous endothermic process.

Adsorption performance and mechanism of Li+ from brines using lithium/aluminum layered double hydroxides-SiO2 bauxite composite adsorbents

A combined method of solid-phase alkali activation and surface precipitation was used to prepare the lithium/aluminum layered double hydroxides-SiO2 loaded bauxite (LDH-Si-BX) and applied to adsorb Li+ in brines. In the study, various characterization techniques such as SEM, XRD, BET, Zeta potential, and x-ray photoelectron spectroscopy (XPS) were applied to characterize and analyze the adsorbents. The adsorption-desorption performance of LDH-Si-BX for Li+ in brines was systematically investigated, including adsorption temperature, adsorption time, Li+ concentration, and regeneration properties. The results indicated that the adsorption kinetics were better fitted by the pseudo-second-order model, whereas the Langmuir model could match the adsorption isotherm data and the maximum Li+ capacity of 1.70 mg/g at 298K. In addition, in the presence of coexisting ions (Na+, K+, Ca2+, and Mg2+), LDH-Si-BX showed good selective adsorption of Li+, and the pH studies demonstrated that the adsorbents had better Li+ adsorption capacity in neutral environments. In the adsorption process of real brines, LDH-Si-BX had a relatively stable adsorption capacity, and after 10 cycles of adsorption and regeneration, the adsorption capacity decreased by 16.8%. It could be seen that the LDH-Si-BX adsorbents prepared in this report have the potential for Li+ adsorption in brines.

Regulating lithium extraction based on intercalated SO42- in Li/Al-LDHs

Reasonable construction of Li/Al-LDHs with interlayer anions is essential to improve the adsorption performance, especially for intercalating SO₄^2- anions and blocking Li⁺ desorption. Hence, anion exchange between Cl^- and SO₄^2- in the interlayer of Li/Al-LDHs was designed and prepared to demonstrate the strong exchangeability of SO₄^2- for Cl^- intercalated in the Li/Al-LDH interlayer. Intercalated SO₄^2- enlarged the interlayer spacing and significantly transformed the stacking structure of Li/Al-LDHs, resulting in fluctuating adsorption performance with changes in the intercalated SO₄^2- content at different ionic strengths. What is more, SO₄^2- repelled the intercalation of other anions, thus inhibiting Li⁺ adsorption, as verified by the negative correlation between adsorption performance and intercalated SO₄^2- content in high-ionic-concentration brines. Desorption experiments further revealed that enhanced electrostatic attraction between SO₄^2- and the Li/Al-LDH laminates hindered Li⁺ desorption. Additional Li⁺ in the laminates was essential for preserving the structural stability of Li/Al-LDHs with higher SO₄^2- contents. This work provides a new insight into the development of functional Li/Al-LDHs in ion adsorption and energy conversion applications.

Recent Advances in Lithium Extraction Using Electrode Materials of Li-Ion Battery from Brine/Seawater

With the rapid development of industry, the demand for lithium resources is increasing. Traditional methods such as precipitation usually take 1–2 years, and depend on weather conditions. In addition, electrochemical lithium recovery (ELR) as a green chemical method has attracted a great deal of attention. Herein, we summarize the systems of electrochemical lithium extraction and the electrode materials of the Li-ion battery from brine/seawater. Some representative work on electrochemical lithium extraction is then introduced. Finally, we prospect the future opportunities and challenges of electrochemical lithium extraction. In all, this review explores electrochemical lithium extraction from brine/seawater in depth, with special attention to the systems and electrode of electrochemical lithium extraction, which could provide a useful guidance for reasonable electrochemical-lithium-extraction.

Recent Advances in the Lithium Recovery from Water Resources: From Passive to Electrochemical Methods

The ever-increasing amount of batteries used in today's society has led to an increase in the demand of lithium in the last few decades. While mining resources of this element have been steadily exploited and are rapidly depleting, water resources constitute an interesting reservoir just out of reach of current technologies. Several techniques are being explored and novel materials engineered. While evaporation is very time-consuming and has large footprints, ion sieves and supramolecular systems can be suitably tailored and even integrated into membrane and electrochemical techniques. This review gives a comprehensive overview of the available solutions to recover lithium from water resources both by passive and electrically enhanced techniques. Accordingly, this work aims to provide in a single document a rational comparison of outstanding strategies to remove lithium from aqueous sources. To this end, practical figures of merit of both main groups of techniques are provided. An absence of a common experimental protocol and the resulting variability of data and experimental methods are identified. The need for a shared methodology and a common agreement to report performance metrics are underlined.

Double-edged role of interlayer water on Li+ extraction from ultrahigh Mg2+/Li+ ratio brines using Li/Al-LDHs

Lithium-aluminum layered double hydroxides (Li/Al-LDHs) are the only industrial adsorbents for Li⁺ extraction from Mg²⁺/Li⁺ ratio brines dependent on the special neutral desorption without dissolution damage. In this work, Li/Al-LDHs with different interlayer water contents were designed for the investigation of correlation between interlayer water and Li⁺ adsorption performances in high Mg²⁺/Li⁺ ratio brines. On the one hand, the Li⁺ adsorption capacity of Li/Al-LDHs in the Qarham Salt Lake old brine with a Mg²⁺/Li⁺ ratio exceeding 300 presented a positive correlative relation with the interlayer water content, rising from 1.05 mg/g to 7.89 mg/g as the interlayer water content increased from 5.52% to 18.18%. On the other hand, the interlayer water content would not affect the structure stability of Li/Al-LDHs, while the interlayer spacing was lessened with less interlayer water resulting in an uptrend to the adsorption selectivity on account of the depressed confinement effect. The density functional theory (DFT) calculation further indicated that LiCl was easier to enter the structure of Li/Al-LDHs with more interlayer water in view of the greater interaction energy.

Adsorption of Li(I) Ions through New High-Performance Electrospun PAN/Kaolin Nanofibers: A Combined Experimental and Theoretical Calculation

Lithium (Li), as a strategic energy source in the 21st century, has a wide range of application prospects. As the demand for lithium resources grows, refining lithium resources becomes increasingly important. A novel method was proposed to directly prepare polyacrylonitrile-LiCl·2Al(OH)₃·nH₂O (PAN-Li/Al-LDH) composites from kaolin with simple operation and low cost, showing effective adsorption performance for the removal of Li(I) from brine in a salt lake. Moreover, several techniques have been applied for characterization, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and the Brunauer-Emmett-Teller method. Batch adsorption experiments were conducted to investigate the adsorption behaviors of PAN-Li/Al-LDHs for Li(I) in salt-lake brines, indicating that the adsorption equilibrium could reach within 2 h, and the adsorption kinetics for Li(I) conforms to the pseudo-second-order model. The adsorption isotherms are consistent with those obtained by the Langmuir model, with a maximum adsorption capacity of 5.2 mg/g. The competitive experimental results indicated that PAN-Li/Al-LDHs exhibited specific selectivity for Li(I) in the mixed solutions of Mg(II), Na(I), K(I), and Ca(II) with the selectivity coefficients of 9.57, 19.38, 43.40, and 33.05, respectively. Moreover, the PAN-Li/Al-LDHs could be reused 60 times with basically unchanged adsorption capacity, showing excellent stability and regeneration ability. Therefore, PAN-Li/Al-LDHs would have promising industrial application potential for the adsorption and recovery of Li(I) from salt-lake brines.

Novel Fluorine-Pillared Metal-Organic Framework for Highly Effective Lithium Enrichment from Brine

The continuously developing lithium battery market makes seeking a reliable lithium supply a top priority for technology companies. Although metal-organic frameworks have been extensively researched as adsorbents owing to their exceptional properties, lithium adsorption has been scarcely investigated. Herein, we prepared a novel cuboid rod-shaped three-dimensional framework termed TJU-21 composed of fluorine-pillared coordination layers of Fe-O inorganic chains and benzene-1,3,5-tricarboxylate (BTC) linkages. Besides thermal and chemical robustness, a remarkably high lithium uptake of about 41 mg·g^-1 was observed on TJU-21 as a fast-spontaneous endothermic process. Single-crystal X-ray diffraction demonstrated that the adsorbed lithium was located in the cavity symmetrically assembled by iron sites and organic ligands between adjacent layers, while another kind of cavity in the framework circled by Fe-O-Fe-O-Fe-O-Fe chains and shared BTC linkages was occupied by hydrogen-bonded water molecules. Lithium adsorption resulted in decreased curviness of the coordination layers, and the binding energy change at O 1s as well as the increased Fe 2p peak, suggested potential interaction with iron sites. The practicability of TJU-21 as a lithium adsorbent was further proved by the considerable capacity and selectivity in simulated salt brines with excellent reusability.

Hydrothermal synthesis and adsorption behavior of H4Ti5O12 nanorods along [100] as lithium ion-sieves

The adsorption method is a promising route to recover Li⁺ from waste lithium batteries and lithium-containing brines. To achieve this goal, it is vital to synthesize a stable and high adsorption capacity adsorbent. In this work, Li₄Ti₅O₁₂ nanorods are prepared by two hydrothermal processes followed by a calcination process. Then the prepared Li₄Ti₅O₁₂ nanorods are treated with different HCl concentrations to obtain a H₄Ti₅O₁₂ adsorbent with 5 μm length along the [100] direction. The maximum amount of extracted lithium can reach 90% and the extracted titanium only 2.5%. The batch adsorption experiments indicate that the H₄Ti₅O₁₂ nanorod maximum adsorption capacity can reach 23.20 mg g⁻¹ in 24 mM LiCl solution. The adsorption isotherms and kinetics fit a Langmuir model and pseudo-second-order model, respectively. Meanwhile, the real adsorption selectivity experiments show that the maximum Li⁺ adsorption capacity reaches 1.99 mmol g⁻¹, which is far higher than Mg²⁺ (0.03 mmol g⁻¹) and Ca²⁺ (0.02 mmol g⁻¹), implying these nanorods have higher adsorption selectivity for Li⁺ from Lagoco Salt Lake brine. The adsorption capacity for Li⁺ remains 91% after five cycles. With the help of XPS analyses, the adsorption mechanism of Li⁺ on the H₄Ti₅O₁₂ nanorods is an ion exchange reaction. Therefore, this nanorod adsorbent has a potential application for Li⁺ recovery from aqueous lithium resources.

H₄Ti₅O₁₂ nanorods were successfully prepared by hydrothermal methods followed by a calcination process. Batch experiments indicate that the nanorod adsorbent is a promising adsorbent to recover lithium from liquid lithium resources.