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In this study, high-temperature solid-phase techniques are used to prepare pristine and Mg-modified LiNiO 2 cathode materials. Various characterizations are performed to analyze the morphology, structure, and electrical state of the two materials. Electrochemical tests show that Mg doping effectively improves the electrochemical properties of the materials. In particular, the modified sample exhibits a higher specific discharge capacity of 244.5 mA h g−1 than the pristine sample. Moreover, its maximum capacity retention after 304 cycles at 1 C is 54.1%. In situ X-ray powder diffraction imaging reveals that the modified material has better phase-transition reversibility than the pristine material. Density functional theory calculations indicate that Mg-doped Li sites can accelerate Li+ transport. Atomic force microscopy results demonstrate that Mg-doped Li sites act as supportive skeletons that enhance the mechanical properties of the material. Therefore, the proposed strategy for the Mg doping of Li sites can improve the architecture of LiNiO 2 cathode materials. [ABSTRACT FROM AUTHOR]

Bamboo exhibits various excellent properties and is widely used in construction. However, appropriate disposal of the bamboo waste generated in a green manner is difficult. To realize resource recycling, we used a simple treatment method to prepare waste bamboo as a negative electrode material exhibiting considerable electrochemical properties for sodium-ion batteries. The electrochemical properties of high-temperature calcination materials considerably improved after impurity removal treatment using an acid solution, which was performed to eliminate the influence of impurities on electrochemical properties. However, the materials still could not meet commercial requirements. A simple pre-oxidation modification treatment enabled the introduction of O atoms into the carbon skeleton to expand the layer spacing, improved the transport kinetics of Na+ in the carbon skeleton, and further increased the platform capacity of the pre-oxidation material. The preoxidative high-temperature co-treated materials exhibited a specific charge capacity close to 280 mAh g−1 at a 0.1 C rate and a capacity attenuation of almost zero after 100 cycles, and showing a specific charge capacity of more than 150 mAh g−1 at a 2 C rate test. In the context of sustainable development, this study makes waste bamboo become a candidate of low-cost negative electrode material for sodium-ion batteries. • Waste bamboo is used to make hard carbon anode material. • Acid leaching and pre-oxidation treatment can form more defects. • The hard carbon demonstrates admirable electrochemical performance. [ABSTRACT FROM AUTHOR]

Configuring a carbon substrate with low surface polarity seems very important and significant for accelerating the cathode electrochemical performances of the Lithium-sulfur batteries, which is widely regarded as one of the most promising candidates for the next-generation green energy suppliers. The corn starch-derived carbon with in-situ multi-elements doping, initially carbonized by 6 mol/L H 2 SO 4 and then calcined in nitrogen atmosphere, is employed to configure sulfur cathode for Lithium–Sulfur batteries in this study. As-received carbon with randomly distributed graphical domains serves as charge carriers diffusion channels during discharging/charging cycles, thus endowing the cathode considerable excellent performances. Specifically, the loading amount of sulfur in cathode is around 60.31 wt% and the effective utilization efficiency of active reagent sulfur in cathode is up to 60 %. On activating the cathode at 0.114 A g−1 at 0, 25 and 40 °C, the initial discharge capacities of the Lithium–Sulfur batteries with corn starch-derived carbon-based composite cathode (with ∼1.3 mg cm−2 sulfur) are 278.6, 1023.7 and 976.1 mAh∙g−1, respectively. Accordingly, more uniform, and thinner solid electrolyte interphase membrane formed under room temperature activation, leaving in the dramatically diminished R sur value, contributes to the comparable cycling stability and rate performances of as-designed carbon-based sulfur cathode for Lithium–Sulfur Batteries. [ABSTRACT FROM AUTHOR]

Abstract In this study, we have successfully coated the CeO 2 nanoparticles (CeONPs) layer onto the surface of the Ni-rich layered LiNi 0.7 Co 0.2 Mn 0.1 O 2 cathode materials by a wet chemical method, which can effectively improve the structural stability of electrode. The X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) are used to determine the structure, morphology, elemental composition and electronic state of pristine and surface modified LiNi 0.7 Co 0.2 Mn 0.1 O 2. The electrochemical testing indicates that the 0.3 mol% CeO 2 -coated LiNi 0.7 Co 0.2 Mn 0.1 O 2 demonstrates excellent cycling capability and rate performance, the discharge specific capacity is 161.7 mA h g−1 with the capacity retention of 86.42% after 100 cycles at a current rate of 0.5 C, compared to 135.7 mA h g−1 and 70.64% for bare LiNi 0.7 Co 0.2 Mn 0.1 O 2 , respectively. Even at 5 C, the discharge specific capacity is still up to 137.1 mA h g−1 with the capacity retention of 69.0%, while the NCM only delivers 95.5 mA h g−1 with the capacity retention of 46.6%. The outstanding electrochemical performance is assigned to the excellent oxidation capacity of CeO 2 which can oxidize Ni2+ to Ni3+ and Mn3+ to Mn4+ with the result that suppress the occurrence of Li+/Ni2+ mixing and phase transmission. Furthermore, CeO 2 coating layer can protect the structure to avoid the occurrence of side reaction. The CeO 2 -coated composite with enhanced structural stability, cycling capability and rate performance is a promising cathode material candidate for lithium-ion battery. [ABSTRACT FROM AUTHOR]

This study synthesizes pristine and Nb-doped lithium-rich manganese-based cathode materials by solvothermal and high-temperature solid-phase methods. Analysis by focused ion beam scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy indicates successful Nb doping into the material's bulk structure. Electrochemical evaluation reveals that electrochemical performance is significantly enhanced by Nb doping. The discharge capacity of Nb-0.02 can maintain 271.7 mAh·g−1, and its cycle retention rate is up to 98.50% after 300 cycles at 0.2C; however, under the same parameters, the pristine material's discharge capacity and cycle retention rate are 212.8 mAh·g−1 and 86.68%. The initial coulombic efficiency and initial discharge capacity of Nb-0.02 is 86.94% and 287.5 mAh·g−1, while that of the pristine material is 73.59% and 234.2 mAh·g−1. Density functional theory calculations demonstrate that Nb doping accelerates Li-ion diffusion and stabilizes material structure due to stronger Nb–O bonds from reduced Li-ion migration barrier energy. Thus, the proposed modification strategy for Nb doping can illuminate the structural design of lithium-rich manganese-based cathode materials. • Nb elements are distributed across the surface and in the bulk material. • ICE and cycle performance are significantly enhanced by Nb doping. • DFT calculations confirm that Nb doping accelerates Li-ion diffusion. [ABSTRACT FROM AUTHOR]

• Structure evolution features of LDHs precursors with pH was investigated. • Role of pH on activating the performance of LDHs type adsorbents was concluded. • Precipitative formation mechanism of LDHs adsorbents was firstly proposed. Aluminum-based adsorbents, simply prepared by eluting the lithium-aluminum layered double hydroxide precursors with deionized water, is the only industrialized adsorbents for selectively separating Li+ from saline brines. Taking the roles of lattice and surface Li+ active sites on its performances into consideration, influence of ending pH modulating on prominently improving the adsorbing capacity and stability of aluminum-based adsorbents prepared by precipitation method is initially investigated. As experimentally evidenced that, the maximum desorption amount of Li+ at the eluting stage should be controlled to around 20 mg/g Li+ rather than thoroughly removed to effectively avoid the topotactic solid-phase transformation from adsorbent to α-Al(OH) 3. As-prepared adsorbents not only has high adsorption capacity up to 8.4 mg/g in 400 ppm LiCl solution, but also owns unique self-healing ability, thus promising the excellent cycling stability. It is firstly proposed that the formation of the layer-structured precursor by precipitation method is well in accordance with the three-step formation mechanism and pH modulating mainly contributes to the anions exchange between solution Cl- and interlayer OH–. This study experimentally proves the importance of pH adjusting for preparing high performance lithium adsorbents by precipitation method, which is very significant and important for effectively extracting lithium resources from the complicated multi-component liquid minerals. [ABSTRACT FROM AUTHOR]

Enhancing the kinetic performance of thick electrodes is essential for improving the efficiency of lithium extraction processes. Biochar, known for its affordability and unique three-dimensional (3D) structure, is utilized across various applications. In this study, we developed a biochar-based, 3D-conductive network thick electrode (∼20 mg cm−2) by in-situ deposition of LiFePO 4 (LFP) onto watermelon peel biomass (WB). Utilizing Density Functional Theory (DFT) calculations complemented by experimental data, we confirmed that this The thick electrode exhibits outstanding kinetic properties and a high capacity for lithium intercalation in brines, even in environments where the Magnesia-lithium ratios are significantly high. The electrode showed an impressive intercalation capacity of 30.67 mg g−1 within 10 min in a pure lithium solution. It also maintained high intercalation performance (31.17 mg g−1) in simulated brines with high Magnesia-lithium ratios. Moreover, in actual brine, it demonstrated a significant extraction capacity (23.87 mg g−1), effectively lowering the Magnesia-lithium ratio from 65 to 0.50. This breakthrough in high-conductivity thick electrode design offers new perspectives for lithium extraction technologies. The watermelon peel serves as the substrate, simultaneously supporting the in-situ loading of LFP, thereby forming an LFP/WB thick electrode exhibits high lithium absorption capacity and excellent kinetic performance in high Mg2+/Li+ ratio brine. It achieved an impressive absorption rate of 30.67 mg g−1·min−1 in 10 min and an average lithium extraction of 23.87 mg g−1 from salt lake brine. This approach effectively reduced the Mg2+/Li+ ratio from 65 to 0.50, enabling efficient lithium separation and comprehensive biological resource utilization. [Display omitted] • The comprehensive utilization of biological resources is achieved. • The low efficiency of Li + extraction with thick electrode is effectively solved. • Effectively reducing the Mg2+/Li+ ratio in low-grade brine. [ABSTRACT FROM AUTHOR]

Improving the kinetic performance of thick electrodes is key to enhancing lithium extraction from salt lakes. Nano-melamine foam (MF), known for its unique porous structure, is ideal for building a three-dimensional (3D) conductive network, thereby boosting electrode kinetics. In our study, we developed a thick electrode (20 mg·g−1) with a 3D-conductive network by in-situ growing LiFePO 4 (LFP) onto a nanoscale MF substrate. This electrode exhibited superior kinetic performance and a high lithium adsorption capacity in brine, achieving up to 32.8 mg·g−1 in just 10 min. Remarkably, even in simulated brine with a high Mg2+/Li+ ratio, it maintained an average coulomb efficiency of 62 %, significantly lowering the Mg2+/Li+ ratio from 65.6 to 0.47. It also showed exceptional stability in actual brine, maintaining an average coulomb efficiency of about 56.6 %. Our development of this high conductivity, thick electrode provides new insights into efficient lithium extraction methods. • The introduction of melamine foam significantly enhanced the extraction efficiency of lithium，addressing the low efficiency commonly associated with lithium extraction in salt lakes. • Demonstrated effectiveness of the LFP/MF materials in real salt lake brine environments, highlighting their potential for practical applications. • The construction of 3D network thick electrode provides a new idea for extracting lithium from salt lake. [ABSTRACT FROM AUTHOR]

Layered high-nickel LiNi 0.8 Co 0.1 Mn 0.1 O 2 is a promising candidate of the next generation cathode materials for lithium-ion batteries. However, severe cycling instability and fast capacity drop induced by anisotropic structured change restrict its wide application. To address these defects, the structure design of cathodes is conducted. Herein, a hierarchical layered LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode consisting of orderly stacking hexagonal nanosheets with exposed active {104} facets is successfully synthesized by an improved co-precipitation process and followed with a high temperature lithiation reaction. Benefiting from this unique texture, exposed active {104} facets with lower surface energy supply 3D barrier-free Li+ ion diffusion channels, significantly improving the efficiency of the Li+ diffusion. Moreover, the consistent arrangement of nanosheets in the manner of the {001} facets close attachment is beneficial to alleviate the stress caused by the anisotropic structured change. Thus, this cathode material presents both superior reversible capability (203.8 mAh g−1 at 0.1C, 184.5 mAh g−1 at 1 C, 173.0 mAh g−1 at 5 C and 161.3 mAh g−1 at 10 C) and stable cycling performance (capacity retention of 89.3% after 100 cycles at 1 C, 55.3% after 300 cycles at 5 C and 59.6% after 300 cycles at 10 C). Schematic of single crystal shape evolution of the cathode materials and the corresponding cycle performance of the NCM-3 sample at different rates. [Display omitted] • A hierarchical cathode material consisting of orderly stacking nanosheets with exposed active {104} facets was successfully synthesized. • The exposed active {104} facets with lower surface energy could supply barrier-free Li+ ion diffusion channels. • The consistent arrangement of nanosheets is beneficial to alleviate the stress and inhibit the pulverization of secondary particles. • The hierarchical cathode material presents both superior reversible capability and stable cycling performance. [ABSTRACT FROM AUTHOR]

Lithium-rich manganese-based oxides are included in high-capacity cathodes. Herein we introduce a certain amount of Mg and Na into lithium-rich manganese-based oxide microspheres to overcome the weak cycling performance and poor rate capacity. This work uses the hydrothermal method combined with the high-temperature solid-phase method and CH 3 COONa and C 4 H 14 MgO 8 as dopants. Transmission electron microscopy (TEM), X-ray diffraction (XRD), focused ion beam scanning electron microscopy (FIB-SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and electrochemical characterization are performed to systematically assess the effect of Na and Mg element doping on the morphology, structure and electrochemical characteristics of Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2. The results show that the material has excellent electrochemical performance. These improvements could be related to the presence of Na in Li layers and Mg in TM layers, which can speed up Li-ion diffusion kinetics and improve ionic and electronic conductivity. DFT calculations demonstrate that the injection of Na and Mg reduces the lithium-ion migration barrier energy. This dual-doped modification technique may help researchers better understand how to build high-capacity and stable cathode materials for LIBs. [ABSTRACT FROM AUTHOR]

• Commercial multi-walled carbon nanotubes (MWCNTs) were activated under ultrasonic treatment with nitric acid in one step. • The usage of only 700 ppm activated MWCNTs catalyst increases MEA-based CO 2 desorption amount by 48.49 % and desorption rate by as high as 338.50 %. • The activated MWCNTs catalyst and MEA solution show outstanding stabilities within 20 cyclic CO 2 sorption and desorption tests. Organic amine solution is currently the most commonly used chemical absorbent for carbon dioxide (CO 2) capture, but its drawback such as high energy consumption for regeneration of CO 2 loaded solution has seriously hindered its wide application in industry. Development of catalysts could reduce the regeneration energy consumption of the process. In this study, the catalytic effects of raw multi-walled carbon nanotubes (MWCNTs) and acid-treated MWCNTs in 30 wt% monoethanolamine solution on both absorption and desorption procedures were investigated. The results showed that the addition of raw MWCNTs and acid-treated MWCNTs as catalysts both promoted the CO 2 desorption rate and amount, among which the 700 ppm acid-treated MWCNTs increased the CO 2 desorption amount by 48.49 %. Furthermore, both MWCNTs shortened the desorption time of CO 2 as well. Stability of acid-treated MWCNTs has been examined by 20 cycles in the capture system. Characterization results indicate that the acid treatment increased the surface area of MWCNTs, and created more acid sites on their surfaces through the defected area. Both characteristics contribute to the enhanced CO 2 desorption performance. Therefore, acid-treated MWCNTs can be considered as promising catalysts for promoting CO 2 desorption and reducing energy consumption for CO 2 capture. [ABSTRACT FROM AUTHOR]

• A homogeneous ionic conductor Li 2 MnO 3 layer, delaying the manganese dissolution loss and promoting the Li+ conduction process, was in situ configured onto the surface of Li 1.6 Mn 1.6 O 4 type lithium adsorbents prepared by the combination of hydrothermal and calcination methods without adding any other modification elements. • Li 2 MnO 3 layer not only acts as Li + diffusion accelerator, but also inhibits the dissolution loss of Mn2+. • The granulated Li 1.6 Mn 1.6 O 4 type adsorbent maintains high adsorption capacity up to 26.4 mg/g after 15 dynamic adsorption–desorption cycles in low grade oil–gas field brine with 100 mg/g Li+. Due to the urgently increased demand for lithium resources, Li 1.6 Mn 1.6 O 4 -type lithium ion sieve with excellent selectivity and high theoretical adsorption capacity has attracted a surge of attentions in recent decades. However, the dissolution of manganese element largely limits its large-scale practical application. In this study, taking the excellent Li+ conductivity and structure stability into consideration, a uniform Li 2 MnO 3 coating was in situ grown on the surface of Li 1.6 Mn 1.6 O 4 to stabilize the spinel structure, thus granting the H 1.6 Mn 1.6 O 4 adsorbents excellent adsorption performance. Based on different characterization and application performance results, it is believed that the in-situ formed Li 2 MnO 3 heterostructure during roasting process not only inhibits the Jahn-Teller effect of manganese, but also dramatically promotes the adsorption and desorption rates and capacities of as-configured adsorbent. Distinctively, as-prepared Li 1.6 Mn 1.6 O 4 -type adsorbents with Li 2 MnO 3 heterostructure has high adsorption capacity of 38.0 mg g−1 in 20 ppm Li+ aqueous solution. After 8 cycles, it still maintains high adsorption capacity up to around 42.7 mg/g in 300 ppm Li+ aqueous with pH 12, the calculated capacity retention rate was 91.4 %, and the Mn dissolution loss rate was only 1.6 %. After 15 dynamic cycles, the granulated Li 1.6 Mn 1.6 O 4 -type adsorbents has an adsorption capacity of 26.4 mg/g in oil–gas field original brines with 100 ppm Li+, which is significant and important for extracting lithium resources from low-grade brines. [ABSTRACT FROM AUTHOR]

Using 3D-rGO, an electrode with a three-dimensional conductive network was successfully constructed, which shortened the transmission path of Li+ and showed excellent kinetic properties (the rate in the first 10 min was 3.58mg·g−1·min−1), and it also has a high adsorption capacity (35.8mg·g−1). [Display omitted] • Significant improvement in the kinetic performance of lithium extraction using the LFP/rGO materials, addressing the low efficiency commonly associated with lithium extraction in salt lakes. • Demonstrated effectiveness of the LFP/rGO materials in real salt lake brine environments, highlighting their potential for practical applications. • The development of a three-dimensional conductive network-incorporated thick electrode provides new insights for the fabrication of high-performance lithium extraction electrodes. Constructing thick electrodes with high Li+ adsorption capacity and excellent kinetic performance effectively addresses the low efficiency of lithium extraction from salt lake brines. However, an increase in the content of active material can hinder the Li+ mass transfer within the electrode, resulting in polarization and reduced kinetic performance, which ultimately affects the extraction efficiency. This study synthesized a three-dimensional(3D) conductive network-incorporated thick electrode (∼20 mg/cm2) composed of the redox graphene oxide-loaded LFP(LFP/rGO) composite through an in situ hydrothermal method. The electrode material showed excellent kinetic performance and a high adsorption capacity for Li+ in salt lake brine. Under a constant voltage of 0.8 V in Li+ solution, the Li+ adsorption capacity reached 36.78 mg·g−1 within 10 min, exhibiting an average coulombic efficiency of over 83.53 %. Furthermore, the LFP/rGO composite thick electrode exhibited a Li+ adsorption capacity of 32.82 mg·g−1, along with an average coulombic efficiency of 74.6 %, even in the West Taijinar old brine solution. Additionally, the electrode material demonstrated remarkable cycling stability, maintaining a capacity of 172.09 mAh·g−1 after 50 cycles at a 0.2C rate in a high-concentration salt lake brine. Our preparation strategy offers novel insights for high-performance lithium extraction electrodes. [ABSTRACT FROM AUTHOR]

Carbon spheres, prepared by hydrothermally treating fresh potato starch, is employed as the sulfur host to configure a high-performance cathode substrate candidate for Li–S batteries. As confirmed by experimental results, both the improved the rate and cycle performances of Li–S batteries cathode with gradient sulfur immobilization, are mainly attributed to the confining, adsorption and conduction multi-functions of as-prepared carbon spheres toward polysulfides. Specifically, on starting the discharging/charging cycles, the active material α-S 8 is irreversibly converted to polysulfides and then transformed between β-S 8 and polysulfides during the next charge/discharge cycles. After initialization at 0.1C for 3 cycles, the initial reversible discharge capacities of the Li–S batteries cathode with optimized sulfur amount are 1072.5, 831.3, 780.4, 726.8, 714.3, 702.7 mAh g−1 sulfur at 0.1, 0.5, 1, 2, 3 and 4 C, which is superior to those of the most previously reported reports. Besides that, as-designed potato-derived carbon based composite cathodes exhibits remarkable rate performance and cycling stability even at wide temperature ranging from −40 to 60 °C, which evidently supports the dominant role of as-prepared 3D carbon spheres in boosting the cathode performance for Li–S batteries. [ABSTRACT FROM AUTHOR]

The relationship between ζ-potential and surface defects of micro-nano sized hexagram-like α-Al2O3 particles was investigated in this paper. The 2D α-Al2O3 particles was prepared by the phase transformation of gibbsite precursor by the following steps during calcination in air: Al(OH)3 → AlOOH→a-Al2O3 → θ-Al2O3 → α-Al2O3. Resulting from the varied intensities of surface defects, as-prepared α-Al2O3 samples have different Eg values around 4.5 eV, which is much narrower than that of bulk α-Al2O3. While benefiting from the interface reaction between surface > AlOH0 and water (>AlOH0 + OH−⇋ > AlO− + H2O), as-prepared α-Al2O3 suspensions can reach their specific pHE values after stirring for 8 h at room temperature. And the measured IEP values of Al2O3-1250°C-2 h, Al2O3-1250°C-3 h, and Al2O3–1300 °C-3 h, which remain 2D morphology, are 7.96, 8.67, and 8.86, respectively. This study is significant and useful for making the industrial applications of α-Al2O3 valid. [ABSTRACT FROM AUTHOR]

• Uniformly dispersed MnCO 3 particles has been synthesized. • CO 2 gas was employed as the sole carburizer. • Mesoporous Mn 2 O 3 microparticles has the similar shape with MnCO 3 precursor. • High adsorption capacity is attributed to electrostatic interaction. Taking the importance and significance of wastewater treatment into consideration, mono-dispersed Mn 2 O 3 powders with sphere-like morphology and mesopore features has been firstly synthesized from the thermal decomposition of MnCO 3 which is prepared via a modified carbonization method using CO 2 gas as the sole carbonate source. The measured isoelectric point, the pH value at which the ζ-potential is zero, of uniformly dispersed Mn 2 O 3 particles is 9.13. Benefiting from the surface electrostatic interaction, as-prepared Mn 2 O 3 microparticles has high adsorption capacity up to 135.5 mg/g toward Congo red dye in aqueous solution. Accordingly, the adsorption process of Congo red by Mn 2 O 3 microspheres could be explained by Langmuir isotherm model and the pseudo-second-order kinetic model. Especially, it is necessary to point out that the removal efficiency of Mn 2 O 3 toward Congo red dye still be well maintained at about 90.78% even after five cycles. Therefore, as-prepared Mn 2 O 3 powders has potential application in large-scale wastewater treatment. [ABSTRACT FROM AUTHOR]

The present study introduces a facile triethanolamine-assisted combustion method, wherein stoichiometric hydrate transition metal acetate with and without the addition of triethanolamine (TEA) were dissolved and mixed uniformly in deionized water and heated to burn. The ashes were then grinded and calcinated to synthesize layered LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode materials. The structure, morphology, and electrochemical performance of two kinds of LiNi 1/3 Co 1/3 Mn 1/3 O 2 materials were investigated and compared systematically. The results indicate that the sample with TEA possesses smaller particles and exhibits less aggregation and a better hexagonal layered structure. On the contrary, the sample with TEA exhibits lower polarization, a better cycling ability, a significantly improved rate performance, and better electronic conductivity. The enhanced electronic conductivity and electrochemical performance may be ascribed to a higher combustion enthalpy and better dispersion in the solvent following the introduction of TEA. This simple synthetic strategy presents a promising synthetic model for the enhancement of electrochemical performance cathode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Al and F co-modified Li 1.6 Mn 1.6 O 4 is prepared for the first time by a facile sol–gel method followed by a solid-state reaction, which can effectively enhance the adsorption performance of the material as an ion-sieve through the triple synergistic reaction mechanism. [Display omitted] • First synthesis of Al and F co-modified Li 1.6 Mn 1.6 O 4. • The triple synergistic effect of co-modification is studied. • High-temperature in-situ XRD was used to demonstrate the ability of co-modification to improve the structural stability. • The mechanism of action of co-modification was revealed by DFT-based theoretical calculations. A surge of interest has been attracted by Li 1.6 Mn 1.6 O 4 -type adsorbent for collecting lithium resources from salt-lake brines due to its excellent selectivity, high theorical adsorption capacity up to 72. 3 mg g−1 and low cost. However, its large-scale practical application is limited because of its bone element Mn dissolution during the cycled desorption process. Herein, F and Al co-modifying technique, an efficient method for stabilizing its spinel structure or forming protective coating, was employed to improve the application performances of Li 1.6 Mn 1.6 O 4 -type adsorbent prepared by sol–gel method. Based on the various characterization results, the co-modification not only leads to the formation of fluoride-rich coating and the substitution of Mn3+ by Al3+, but also generates the active adsorbents with abundant nano-islands. DFT calculations revealed that the coating layer is indeed AlF 3 rather than LiF. In addition, in-situ high-temperature XRD tests demonstrates that the co-modification can significantly enhance the heat resistance and structural stability of the material. As-prepared adsorbent exhibits greatly improved Li adsorption capacity (increased from 28.5 to 33.7 mg g−1), lower Mn loss rate (decreased from 2.1 to 1.8%), enhanced cycling stability and good adsorption selectivity in the Qarhan brine containing Na+, K+, Ca2+, Mg2+, which is very significant and important for effectively removing lithium from low-grade brines. [ABSTRACT FROM AUTHOR]

Solid-phase reactions were used for the synthetization of the spinel Li 1.6 Mn 1.6 O 4 powder and the lithium ion-sieve MnO 2 ·0.5H 2 O was subsequently obtained by the leaching of the lithium. The physical characterization showed that the polycrystalline precursor and the MnO 2 ·0.5H 2 O were nearly pure spinel, as well as that during the process of the adsorption-desorption, the structural stability was high. The Langmuir isotherm and pseudo second-order kinetics model showed consistency with the adsorption behavior, which indicated the presence of homogeneous adsorption sites for the lithium adsorption and that its process was chemisorption. Adsorbents were found to remain being characterized with a relatively high Li+ uptake (26.13 ​mg ​g−1) with low manganese extracted (1.71%) after the circulation experiment was performed up to 5 times, proving a significant repeatability and stability for the lithium ion-sieve. The concentration factors exhibited the highly selective adsorption capacity for absorbent from Qarhan raw brine with high concentrations of Na+, K+, Ca2+, Mg2+. The adsorbents could be efficiently used for Li+ recovery from Salt Lake brine as well as its excellent potential for further application. Due to the sieving effect (steric hindrance effect and hydration free energy effect), the lithium ion-sieve selectively adsorbed Li+ when the ion-sieve was immersed in brine, indicating that the ion-sieve MnO 2 ·0.5H 2 O was expected to recover Li+ from the solutions including Salt Lake brine, seawater, and wastewater. Image 1 • The precursor was prepared by practical two-stage solid-phase sintering technique. • The Li 1.6 Mn 1.6 O 4 exhibited excellent adsorption performance. • The materials showed the highly selective adsorption from Qarhan raw brine. [ABSTRACT FROM AUTHOR]