Preparation method of inorganic solid-state membrane for selectively extracting lithium from liquid-phase resource and application of inorganic solid-state membrane

Abstract

The invention relates to the technical field of electrochemical lithium extraction, in particular to a preparation method and application of an inorganic solid-state membrane for selectively extracting lithium from a liquid-phase resource. The method comprises the following steps: forming Li4Ti5O12 powder into a film, and placing the film in the center of an H-shaped electrolytic bath to distinguish a cathode chamber from an anode chamber; putting electrodes into the cathode chamber and the anode chamber respectively, adding a solution, and applying an electromotive force between the two electrodes, so that lithium selectively penetrates through the Li4Ti5O12 powder from the anode chamber to enter the cathode chamber; and after reacting for a period of time, recovering the solution in the cathode chamber to obtain the lithium-rich solution. The reaction in the solution includes. The prepared lithium selective solid-state membrane has ultrahigh selectivity and low price, and lithium resources in the lithium selective solid-state membrane can be selectively obtained from salt lake brine and even seawater which are complex in composition. And the obtained lithium product is lithium hydroxide, so that the additional value of the lithium product is improved, the subsequent separation cost is reduced, the complicated subsequent lithium precipitation process is shortened, and the method is energy-saving and environment-friendly.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical lithium extraction technology, specifically relating to the preparation and application of an inorganic solid membrane for selectively extracting lithium from liquid phase resources. Background Technology

[0002] With the application of large-scale energy storage and the development of wearable electronic devices, the demand for lithium resources is increasing daily. Traditional ore mining and the drying of old brine in salt lakes can no longer meet the consumption demand for lithium salt products. People are gradually focusing their attention on obtaining lithium resources from low-grade salt lakes or seawater containing more impurity ions, and selective lithium extraction has become a research hotspot. Electrochemical methods for extracting lithium from liquid-phase resources have attracted widespread attention as a representative of low energy consumption, pollution-free, and high selectivity. Iron phosphate materials are widely favored by researchers due to their low raw material costs and stable synthesis processes.

[0003] Battery-based redox methods, such as LiFePO4 or LiMn2O4, offer better separation of magnesium and lithium. However, the separation of lithium and sodium ions remains a complex issue. Furthermore, both materials exhibit varying degrees of dissolution loss and capacity degradation. Battery-based redox and adsorption methods, currently considered potential industrial solutions, face challenges in achieving continuous operation. These processes are limited by the requirements of adsorption and desorption (or electrochemical lithium extraction and release) stages, each requiring a washing step. Therefore, achieving full automation and continuous production on an industrial scale remains a significant challenge.

[0004] However, another continuous electrodialysis separation technology based on inorganic solid electrolytes exists: inorganic solid electrolytes are considered the most critical material for all-solid-state lithium-ion batteries due to their high ionic conductivity and excellent safety. It is generally believed that ion transport in inorganic solid electrolytes occurs through lithium-ion diffusion channels generated by vacancy or interstitial mechanisms. The ion diffusion capability of inorganic solid electrolytes depends on their crystal structure framework.

[0005] However, since the ion-selective extraction of lithium from inorganic solid-state electrolytes based on electrodialysis has only been proposed in recent years, relatively few researchers have focused on this method. Most researchers focusing on this method still concentrate on conventional solid-state electrolyte materials already used in all-solid-state lithium-ion batteries, neglecting the fact that the vast majority of classic solid-state electrolyte lithium-ion batteries rely on rare rare-earth elements. These elements are derived from scarce reserves, require harsh and expensive calcination conditions, suffer from high electrochemical impedance leading to low yields, and cannot remain stable in the alkaline environment produced by the electrolyte, severely limiting the industrial application of this technology. Furthermore, previous research has mainly focused on advancements in material properties and separation techniques. An efficient and comprehensive separation process suitable for industrial applications and a method for lithium extraction that conserves resources has not yet been provided. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing an inorganic solid-state selective membrane for selectively extracting lithium from liquid-phase resources, and its application. The inorganic solid-state selective membrane prepared by this method exhibits high lithium-ion selectivity, significantly improving the lithium resource recovery capacity from liquid-phase resources, thereby broadening the range of usable lithium resources. Furthermore, the inorganic solid-state selective membrane prepared by this invention is inexpensive and does not involve the use of rare earth elements. The lithium product obtained by this invention is lithium hydroxide, which increases the added value of the lithium product, reduces subsequent separation costs, greatly shortens the complex subsequent lithium precipitation process, and is energy-saving and environmentally friendly.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for preparing an inorganic solid-state selective membrane for selectively extracting lithium from liquid phase resources, the method comprising the following steps:

[0008] (1) Li4Ti5O 12 Powder is formed into a film;

[0009] (2) Place the product obtained in step (1) in the center of the H-type electrolytic cell to distinguish the cathode chamber and the anode chamber; place electrodes in the cathode chamber and anode chamber respectively and add solution, then apply an electromotive force between the two electrodes so that the reaction occurs on both the anode side and the cathode side.

[0010] (3) After a period of reaction, the cathode chamber solution can be recovered to obtain a lithium-rich solution.

[0011] The method of this invention achieves selective separation of lithium by taking advantage of the difference between the desolvation energy and diffusion energy barrier of lithium ions and impurity ions crossing inorganic crystal materials.

[0012] In step (1), the crystallization degree, surface smoothness and porosity of the selective film are controlled by controlling the molding method; in step (2), static solution reaction or dynamic solution reaction can be used on both the anode side and the cathode side; in steps (2) and (3), the selectivity and reaction rate can be adjusted by different electromotive forces and different reaction times.

[0013] The molding reaction described in step (1) can directly react Li4Ti5O 12 Alternatively, to form a film, lithium- or titanium-containing precursors such as Li2CO3 and TiO2 can be mixed, formed into a film, and then calcined to generate Li4Ti5O in situ. 12 .

[0014] Preferably, Li₂CO₃ and TiO₂ are thoroughly mixed in a stoichiometric ratio of 2:5, then first formed into a film and subsequently calcined to obtain in-situ generated Li₄Ti₅O₂. 12 ;

[0015] Furthermore, Li₂CO₃ and TiO₂ are thoroughly mixed at a stoichiometric ratio of 2:5, calcined at 600℃ for 2-4 hours, thoroughly mixed again, cold-pressed, and then calcined again at temperatures above 700℃ to obtain a more smooth and uniform Li₄Ti₅O₂. 12 .

[0016] Preferably, the solution added to the anode chamber is a liquid phase resource containing lithium ions, and the solution added to the cathode chamber is one or more of NaOH, KOH, LiOH, Na2SO4, K2SO4, Li2SO4, NaNO3, KNO3, LiNO3, NaCl, KCl, and LiCl.

[0017] Furthermore, oxidation occurs in the anode chamber and reduction occurs in the cathode chamber. The closure of the circuits on both sides relies on lithium ions passing through Li4Ti5O. 12 Furthermore, the anodic reaction is one or more of the following: oxygen evolution reaction and chlorine evolution reaction.

[0018] Furthermore, the cathode reaction described in step (2) is a hydrogen evolution reaction.

[0019] Furthermore, the molding method is one or more of the following: cold pressing, extrusion after mixing, film formation with binder, and 3D printing.

[0020] Furthermore, a high potential is applied to the anode chamber and a low potential is applied to the cathode chamber.

[0021] A second aspect of the present invention is to provide an inorganic solid selective membrane prepared by the method.

[0022] A third aspect of the present invention is to provide an application of the membrane described herein in lithium extraction from seawater and salt lake brine.

[0023] Advantages and beneficial effects of the present invention:

[0024] 1. The lithium-selective solid film prepared by this invention has ultra-high selectivity and low price, and does not involve rare earth elements or elements that are harmful to the environment.

[0025] 2. The lithium product obtained by this invention is lithium hydroxide, which increases the added value of the lithium product, reduces the subsequent separation cost, greatly shortens the complex subsequent lithium precipitation process, and is energy-saving and environmentally friendly.

[0026] 3. The lithium-selective inorganic solid membrane prepared by this invention can extract lithium ions from liquid phase resources with extremely low concentrations, and can selectively obtain lithium resources from complex salt lake brines or even seawater.

[0027] 4. The application process of the inorganic solid selective membrane in this invention is suitable for coupling hydrogen production reactions with new energy sources such as hydroelectric power. Detailed Implementation

[0028] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] The electrochemical lithium extraction described in this invention refers to the extraction or enrichment of lithium resources from liquid phase resources using electrochemical methods. The formulas for calculating the lithium-sodium selectivity coefficient and lithium-magnesium selectivity coefficient in the embodiments are as follows:

[0031]

[0032]

[0033] C Li,r 、C Mg,r 、C Na,r These represent the concentrations of Li+, Mg2+, and Na+ in the cathode solution after the reaction. C Li,f 、C Mg,f and C Na,fLi in the anode (feed) solution + Mg 2+ and Na + The concentration.

[0034] Example 1

[0035] Li2CO3 and TiO2 were added to anhydrous ethanol at a stoichiometric ratio of 2:5, dispersed by ultrasonication, then manually ground for 30 minutes, calcined in a tube furnace at 600°C for 2 hours, then cold-pressed into small sheets, and finally placed in a tube furnace again and reacted at 800°C for 10 hours under an inert atmosphere to obtain a selective inorganic solid membrane.

[0036] The membrane was placed in the center of an H-type electrolytic cell, with seawater and 0.1 MkOH solutions on either side, respectively. A three-electrode system was used for the reaction, with RuO2-IrO2 installed in the feed chamber as the working electrode (WE), Ag / AgCl as the reference electrode (RE), and a platinum mesh as the counter electrode (CE) applying 1.25 V (vs. Ag / Ag / Cl). The reaction was carried out for 50 h.

[0037] Example 2

[0038] Li2CO3 and TiO2 were manually ground in a stoichiometric ratio of 2:5 for 30 minutes, then calcined in a tube furnace at 600°C for 4 hours, and then cold-pressed into small original sheets. Finally, the sheets were placed in a tube furnace again and reacted at 800°C for 8 hours under an inert atmosphere to obtain a selective inorganic solid film.

[0039] The membrane was placed in the center of an H-type electrolytic cell, with salt lake brine and 0.1 MkOH solutions on either side, respectively. A three-electrode system was used for the reaction, with RuO2-IrO2 installed in the feed chamber as the working electrode (WE), Ag / AgCl as the reference electrode (RE), and a platinum mesh as the counter electrode (CE) applying 1.25 V (vs. Ag / Ag / Cl). The reaction was carried out for 50 h.

[0040] Example 3

[0041] Li4Ti5O 12 The film is cold-pressed into small sheets, placed in a tube furnace, and reacted at 700°C for 4 hours under an inert atmosphere to obtain a selective inorganic solid film.

[0042] The membrane was placed in the center of an H-type electrolytic cell, with brine from a salt lake and 0.1 MkOH on either side. A two-electrode system was used for the reaction. RuO2-IrO2 was installed in the feed chamber as the working electrode (WE), and a platinum mesh was used as the counter electrode (CE) to apply 4V. The reaction was carried out for 50 hours.

[0043] Example 4

[0044] Li4Ti5O12 Films were formed by bonding PVDF and NMP, and PVDF and Li4Ti5O 12 A mass ratio of 9:1 yields a selective inorganic solid membrane.

[0045] The membrane was placed in the center of an H-type electrolytic cell, with brine from a salt lake and 0.1 MkOH solutions on either side. A two-electrode system was used for the reaction, with a carbon plate installed in the feed chamber as the working electrode (WE) and the carbon plate used as the counter electrode (CE) to apply 3.5 V. The reaction was carried out for 50 h.

[0046] Initial concentration of the cathode solution and ion concentration in the cathode solution after the reaction (mg / L) in Example 1

[0047]

[0048] Initial concentration of the cathode solution and ion concentration in the cathode solution after the reaction (mg / L) in Example 2

[0049]

[0050] Initial concentration of the cathode solution and ion concentration in the cathode solution after the reaction (mg / L) in Example 3

[0051]

[0052] Initial concentration of the cathode solution and ion concentration in the cathode solution after the reaction (mg / L) in Example 4

[0053]

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an inorganic solid-state selective membrane for selectively extracting lithium from liquid-phase resources, characterized in that, The method includes the following steps: (1) Li4Ti5O 12 Powder is formed into a film; (2) Place the membrane obtained in step (1) in the center of the H-type electrolytic cell to distinguish the cathode chamber and the anode chamber; place electrodes in the cathode chamber and anode chamber respectively and add solution, then apply an electromotive force between the two electrodes so that the reaction occurs on both the anode side and the cathode side; (3) After a period of reaction, the cathode chamber solution can be recovered to obtain a lithium-rich solution.

2. The method according to claim 1, characterized in that, The molding process described in step (1) involves directly molding Li4Ti5O. 12 To form a film, or to mix lithium-containing or titanium-containing precursors, first form a film and then calcine it to generate Li4Ti5O in situ. 12 .

3. The method according to claim 2, characterized in that, The lithium-containing precursor is Li2CO3, and the titanium-containing precursor is TiO2.

4. The method according to claim 1, characterized in that, The solution added to the anode chamber is a liquid phase resource containing lithium ions, and the solution added to the cathode chamber is one or more of the following: NaOH, KOH, LiOH, Na2SO4, K2SO4, Li2SO4, NaNO3, KNO3, LiNO3, NaCl, KCl, and LiCl.

5. The method according to claim 1, characterized in that, Oxidation occurs in the anode chamber, and reduction occurs in the cathode chamber.

6. The method according to claim 1, characterized in that, The molding method is one or more of the following: cold pressing, extrusion after mixing, film formation with binder, and 3D printing.

7. The method according to claim 1, characterized in that, A high potential is applied to the anode chamber, and a low potential is applied to the cathode chamber.

8. An inorganic solid selective membrane prepared by the method according to any one of claims 1-7.

9. The application of the membrane according to claim 8 in lithium extraction from seawater and salt lake brine.

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