Membrane-free self-driven system with lithium extraction and electric energy generation functions as well as preparation and application of membrane-free self-driven system

Abstract

The invention relates to the technical field of liquid lithium resource extraction and energy recovery, in particular to a membrane-free self-driven system with lithium extraction and electric energy generation functions as well as preparation and application of the membrane-free self-driven system. The membrane-free self-driven system provided by the invention takes an active metal elementary substance electrode as an anode, an electrode with a high-selectivity lithium ion channel as a cathode and lithium-containing water as an electrolyte; during use, the anode is subjected to self-corrosion reaction to generate electrons, the electrons flow into the cathode through an external circuit, electron-ion coupling is generated at the cathode, and in order to maintain electric neutrality, lithium ions are captured from the electrolyte, so that the lithium ions are driven to be embedded and recycled at the cathode, and electric energy is generated at the same time. According to the membrane-free self-driven system, an energy transfer mechanism in the nature is used for reference, and the problems of high cost and complexity of a traditional membrane separation technology are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid lithium resource extraction and energy recovery, and in particular to a membrane-free self-driving system capable of both lithium extraction and electric energy generation, and the preparation and application thereof. Background Art

[0002] With the dramatic growth in global demand for smart devices and renewable energy storage, the demand for lithium as a key material is expected to triple by 2050 from 2028. However, existing lithium extraction methods are not only time-consuming and energy-consuming, but also have significant negative impacts on the environment. In particular, the method of extracting lithium from salt lakes consumes a lot of water resources and energy, and produces high levels of carbon dioxide emissions, which are even higher than steel production. The limitations of these traditional methods not only make lithium extraction expensive, but also have serious negative impacts on the environment. There is an urgent need to find more efficient and environmentally friendly alternatives. Despite the abundant underground lithium resources, the development of new mines and processing facilities is relatively slow and costly. In order to cope with the crisis of lithium supply shortage, it is urgent to develop new, low-carbon lithium extraction technologies.

[0003] Lithium mineral resources are mainly distributed in remote areas with limited power grid power supply, so the lithium extraction process faces energy supply problems. However, these areas usually have abundant renewable energy resources, such as solar energy and wind energy. The lithium extraction process driven by renewable energy can effectively solve the energy bottleneck in salt lake lithium extraction. For example, solar-driven lithium extraction methods can be carried out without relying on traditional energy, reducing carbon emissions and providing a sustainable solution. Another major challenge in the lithium extraction process is to improve selectivity and extraction rate. Although membrane separation technology performs well in selectivity, its high material cost and potential membrane fouling problems limit its industrial application. Traditional membrane-assisted lithium extraction technology also requires electric field drive, which increases the complexity of the equipment and the difficulty of operation.

[0004] Therefore, it is very important to provide a technical solution that can solve the above technical problems. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a membraneless self-driving system that combines lithium extraction and electricity generation, and its preparation and application. The membraneless self-driving system of the present invention utilizes the self-corrosion process of active metal elements as electron donors, and drives lithium ions to be embedded in the cathode lithium ion transport bin material through an electron-ion coupling path. It can not only efficiently extract lithium ions from lithium-containing water sources with different lithium concentrations such as seawater or salt lake brine, but also generate electricity. The system draws on the mechanism of energy transfer in nature and avoids the high cost and complexity of traditional membrane separation technology. This innovative self-driving system provides a new efficient and environmentally friendly way for future lithium extraction and resource recovery, and has important practical application value.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The first object of the present invention is to provide a membraneless self-driving system that combines lithium extraction and electricity generation, wherein the membraneless self-driving system uses an active metal single substance electrode as an anode, an electrode with a highly selective lithium ion channel as a cathode, and lithium-containing water as an electrolyte.

[0008] In one embodiment of the present invention, the membrane-free self-driving system can be self-driven without external energy input; allowing lithium ion extraction under different environmental conditions (seawater or salt lake brine with different lithium grade values);

[0009] By adjusting the potential difference between the cathode electron acceptor and the active metal element, the lithium ion insertion and recovery efficiency is optimized.

[0010] Electrons generated by self-corrosion of the anode flow into the cathode through an external circuit, where electron-ion coupling occurs. To maintain electrical neutrality, lithium ions are captured from the electrolyte, driving the embedding and recovery of lithium ions in the cathode while generating electrical energy. After the lithium ion extraction is completed, the cathode electrode is rinsed clean and immersed in an aqueous solution with oxygen for self-oxidation to release the enriched lithium ions and prepare for cyclic lithium extraction.

[0011] In one embodiment of the present invention, the active metal element is selected from one of iron, aluminum, magnesium or zinc (the purity of the active metal element is higher than 90wt%, and it can spontaneously corrode in seawater or brine to generate electrons as an electron donor);

[0012] The material with highly selective lithium ion channels is selected from one or more of FePO4, porous carbon materials or surface-modified metal oxides (which also have ultra-high embedding selectivity for lithium / magnesium and lithium / sodium ions, provide a place for electron-lithium ion coupling, and realize the spontaneous lithium release process of oxygen oxidation after lithium extraction is completed, and its oxidation potential should be lower than the oxidation potential of oxygen);

[0013] The lithium-containing water is selected from seawater, salt lake water or geothermal brine.

[0014] In one embodiment of the present invention, the active metal single substance electrode is a plate-shaped or mesh-shaped electrode (to increase its specific surface area, thereby improving the electron generation efficiency).

[0015] In one embodiment of the present invention, the material having a highly selective lithium ion channel is one or more of FePO4, porous carbon materials or surface-modified metal oxides.

[0016] In one embodiment of the present invention, the electrode having a highly selective lithium ion channel is prepared by the following method:

[0017] (A1) mixing a highly selective lithium ion electrode material with a conductive agent, a binder and a solvent, and grinding the mixture to obtain a mixed slurry;

[0018] (A2) coating the mixed slurry prepared in step (A1) on a current collector, and obtaining an electrode having a highly selective lithium ion channel after drying.

[0019] In one embodiment of the present invention, in step (A1), the mass ratio of the highly selective lithium ion electrode material, the conductive agent, and the binder is 7 to 8:1 to 2:1;

[0020] The solid content of the mixed slurry is 75-85%;

[0021] The conductive agent is selected from one of superconducting carbon, carbon fiber or carbon nanotube, the binder is selected from one of polyvinylidene fluoride, ethyl cellulose (EC) or styrene-butadiene rubber (SBR); the solvent is selected from one of N-methylpyrrolidone, isobutyl isobutyrate or p-xylene.

[0022] In step (A2), the coating amount of the mixed slurry is 1 mg / cm 2 ~100mg / cm 2 ;

[0023] The current collector is selected from one of conductive carbon cloth and metal titanium;

[0024] The drying process is carried out under vacuum conditions, at a temperature of 90-110°C, for more than 24 hours.

[0025] A second object of the present invention is to provide a method for using a membraneless self-driven system for both lithium extraction and electricity generation, comprising the following steps:

[0026] (S1) placing the anode and the cathode in an electrolytic cell containing a lithium-containing electrolyte, and using a constant current discharge mode to enable the cathode to extract lithium from the lithium-containing electrolyte;

[0027] (S2) After step (S1) is completed, the cathode electrode is cleaned and placed in an oxygen-saturated NH4Cl aqueous solution for self-oxidation to release lithium ions.

[0028] In one embodiment of the present invention, in step (S1), during the constant current discharge process, 1.2 to 3.3 mA cm -2 .

[0029] In one embodiment of the present invention, in step (S1), during the auto-oxidation treatment, the temperature is 5 to 40°C and the time is 0.5h to 24h.

[0030] The third object of the present invention is to provide a membrane-free self-driven system for lithium extraction and electric energy generation for use in lithium extraction.

[0031] The membrane-free self-driving system of the present invention has the following advantages:

[0032] (1) Avoid high cost and complexity: By designing a membraneless electron-ion coupling path, the high material cost and equipment complexity of traditional membrane separation technology are avoided, and the system construction and maintenance costs are reduced; (2) Realize the synergistic generation of electricity: During the lithium extraction process, electricity is generated at the same time, improving the overall benefits of the system and providing an additional source of energy, which is especially suitable for the development of lithium mineral resources in remote areas; (3) Improve lithium extraction efficiency and reduce energy consumption and carbon emissions: By utilizing the self-corrosion process of zero-valent active metals as electron donors, the lithium ions are driven to be embedded and recovered in the cathode, thereby achieving efficient extraction of lithium ions from seawater or salt lake brine, significantly reducing energy consumption and carbon emissions, and providing a low-carbon, sustainable lithium extraction solution.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) Membrane-free design: In the prior art, most lithium extraction methods rely on membrane separation technology, which has high selectivity but is costly and susceptible to contamination. The present invention adopts a membrane-free design, which generates electrons through the self-corrosion of metal elements, drives lithium ions to embed into the cathode material, and achieves efficient lithium extraction, avoiding the high cost and complexity of membrane separation technology.

[0035] (2) Self-driving system: Traditional lithium extraction methods require external power supply, which consumes a lot of energy and is highly dependent on power supply. The present invention uses the self-corrosion process of zero-valent iron as an electron donor to construct a self-driving system without the need for external power supply, significantly reducing energy consumption and achieving a more autonomous and environmentally friendly lithium extraction process.

[0036] (3) Synergistic power generation: In the prior art, the lithium extraction process mainly focuses on the separation and recovery of lithium ions, while ignoring the utilization of energy. The present invention realizes the generation of power during the lithium extraction process, collects and utilizes the power generated in the reaction process through the power generation module, provides an additional source of energy, and is particularly suitable for the development of lithium ore resources in remote areas, thereby enhancing the comprehensive benefits of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the working principle of a membrane-less self-driven system that combines lithium extraction and electricity generation;

[0038] Figure 2 The data graph of lithium extraction from geothermal brine and electricity generation at different current densities;

[0039] Figure 3 The data graph of the simultaneous power generation when lithium is extracted from salt lake brine at different current densities;

[0040] Figure 4 This is the ICP-MS data diagram of lithium extraction from geothermal brine at different current densities;

[0041] Figure 5 This is the ICP-MS data diagram of lithium extraction from salt lake brine at different current densities;

[0042] Figure 6 This is the ICP-MS data diagram of lithium extraction from seawater at different current densities. DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.

[0045] Example 1

[0046] This embodiment provides a membraneless self-driving system that can extract lithium and generate electricity. The membraneless self-driving system uses an active metal single substance electrode as an anode, an electrode with a highly selective lithium ion channel as a cathode, and lithium-containing water as an electrolyte.

[0047] Furthermore, the active metal single electrode is an iron plate;

[0048] The material having a highly selective lithium ion channel is FePO4;

[0049] The lithium-containing water is selected from seawater, salt lake brine or geothermal brine;

[0050] Furthermore, the electrode with highly selective lithium ion channel is prepared by the following method:

[0051] (A1) mixing FePO4, superconducting carbon, polyvinylidene fluoride (the mass ratio of FePO4, superconducting carbon, and polyvinylidene fluoride is 7:2:1) with N-methylpyrrolidone, and grinding to obtain a mixed slurry (solid content of 80%);

[0052] (A2) The mixed slurry prepared in step (A1) was coated on the conductive carbon cloth (coating amount was 50 mg / cm 2 ), and dried (under vacuum conditions, at a temperature of 110°C for 24 h) to obtain an electrode with a highly selective lithium ion channel.

[0053] Among them, the electrode with highly selective lithium ion channels prepared under the following conditions has comparable performance to the electrode with highly selective lithium ion channels prepared in this embodiment, and the specific conditions are as follows:

[0054] In step (A1), the mass ratio of the highly selective lithium ion electrode material, the conductive agent, and the binder is 7-8:1-2:1; the solid content of the mixed slurry is 75-85%;

[0055] In step (A2), the coating amount of the mixed slurry is 1 mg / cm 2 ~100mg / cm 2 The drying process is carried out under vacuum conditions, with a temperature of 90-110°C and a drying time of more than 24 hours.

[0056] Example 2

[0057] This embodiment provides a membrane-free self-driven system for lithium extraction and power generation in a salt lake, and verification of the performance of lithium extraction and power generation, including the following steps:

[0058] (S1) System construction and material selection: The membrane-free self-driven system for both lithium extraction and power generation is the system described in Example 1, and Sichuan Daying real geothermal brine ( Figure 2 "Geothermal brine" in Chinese) and Qinghai Emerald Lake Salt Lake Real Salt Lake Brine ( Figure 3 Salt lake brine, referred to as "salt lake brine" in Chinese, is used as the electrolyte (lithium ion concentration is about 350 mg L -1 ), providing a medium for the migration of lithium ions and the transmission of electrons.

[0059] (S2) Membrane-free self-driven lithium extraction from salt lakes: The self-made two-electrode method was used for testing, using the anode and cathode of step (S1) respectively, and the constant current discharge mode of the electrochemical workstation was adopted, the discharge current was 1.2 mA, and the discharge time was 1200 s.

[0060] (S3) Lithium ion release and electrode regeneration

[0061] Electrode cleaning: After discharge, the cathode electrode is removed and rinsed with deionized water to remove salt and impurities attached to the surface. Self-oxidation treatment: The cleaned cathode electrode is immersed in an oxygen-saturated 0.1M NH4Cl aqueous solution for 24 hours of self-oxidation treatment to promote the release of lithium ions from the cathode material. Ion concentration analysis: ICP-MS is used to analyze the ion concentration in the release solution, especially Li, Na, Mg ions, to evaluate the lithium extraction efficiency and selectivity.

[0062] pass Figure 2 and Figure 3 It can be found that the discharge and lithium extraction curves of the constructed self-driven lithium extraction system at different current densities in real salt lake water have obvious redox platforms, indicating that the lithium ion embedding process can be completed. The results of ICP-MS show that ( Figure 4 and Figure 5 As shown in the figure, only Li ions and a small amount of Mg ions exist in the released liquid, and the concentrations of Na and Ca ions are both lower than the detection line of the instrument, indicating that the membraneless self-driven liquid lithium ore extraction system has high selectivity for Li ions.

[0063] Example 2

[0064] The present invention provides lithium extraction performance verification in seawater.

[0065] (S1) System construction and material selection

[0066] Anode material: Iron plate is selected as the anode material because iron has a high self-corrosion rate in seawater environment and can effectively release electrons.

[0067] Cathode material: Olivine iron phosphate (FePO4) with highly selective lithium ion channels is selected as the cathode electrode material because of its excellent selectivity and embedding ability for lithium ions.

[0068] Electrolyte: Seawater from a certain area of ​​the South China Sea was selected as the electrolyte. The lithium ion concentration in seawater is relatively low, about 0.17 mg L -1 .

[0069] (S2) Membrane-free self-driven lithium extraction from seawater

[0070] Electrode configuration: The iron plate anode and the electrode (cathode) with highly selective lithium ion channel prepared in Example 1 are installed in an electrolytic cell containing an electrolyte.

[0071] Current control: constant current discharge mode is adopted, with 1.2mA cm -2 Discharge.

[0072] Discharge time: The discharge time was set to 1200 seconds to ensure that lithium ions had enough time to be extracted from seawater and embedded into the cathode material.

[0073] (S3) Lithium ion release and electrode regeneration

[0074] Electrode cleaning: After discharge, the cathode electrode is removed and rinsed with deionized water to remove salt and impurities attached to the surface. Self-oxidation treatment: The cleaned cathode electrode is immersed in an oxygen-saturated 0.1M NH4Cl aqueous solution for 24 hours of room temperature self-oxidation treatment to promote the release of lithium ions from the cathode material. Ion concentration analysis: ICP-MS is used to analyze the ion concentration in the release solution, especially Li, Na, Mg ions, to evaluate the lithium extraction efficiency and selectivity.

[0075] like Figure 6 As shown, the results of ICP-MS indicate that only Li ions and a small amount of Mg ions exist in the released liquid, and the concentrations of Na and Ca ions are both lower than the detection line of the instrument, indicating that the membraneless self-driven liquid lithium ore extraction system has high selectivity for Li ions.

[0076] This embodiment demonstrates that the membraneless self-driven lithium extraction system provided by the present invention can achieve an efficient and selective lithium extraction process.

[0077] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the explanation of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A membrane-less self-driven system for both lithium extraction and electricity generation, characterized in that: The membraneless self-driving system uses an active metal single substance electrode as an anode, an electrode with a highly selective lithium ion channel as a cathode, and lithium-containing water as an electrolyte; When in use, the anode undergoes a self-corrosion reaction to produce electrons, which flow into the cathode through an external circuit. Electron-ion coupling occurs at the cathode. In order to maintain electrical neutrality, lithium ions are captured from the electrolyte, thereby driving the lithium ions to be embedded and recovered at the cathode while generating electrical energy.

2. A membrane-less self-driven system for both lithium extraction and electricity generation according to claim 1, characterized in that: The active metal element is selected from one of iron, aluminum, magnesium or zinc; The material having a highly selective lithium ion channel is selected from one or more of FePO4, porous carbon materials or surface-modified metal oxides; The lithium-containing water is selected from seawater, salt lake water or geothermal brine.

3. A membrane-less self-driven system for both lithium extraction and electricity generation according to claim 2, characterized in that: The active metal single substance electrode is a plate-shaped or mesh-shaped electrode.

4. A membrane-less self-driven system for lithium extraction and electricity generation according to claim 2, characterized in that: The material with highly selective lithium ion channels is one or more of FePO4, porous carbon materials or surface-modified metal oxides.

5. A membrane-less self-driven system for both lithium extraction and electricity generation according to claim 4, characterized in that: The electrode with highly selective lithium ion channel is prepared by the following method: (A1) mixing a highly selective lithium ion electrode material with a conductive agent, a binder and a solvent, and grinding the mixture to obtain a mixed slurry; (A2) coating the mixed slurry prepared in step (A1) on a current collector, and obtaining an electrode having a highly selective lithium ion channel after drying.

6. A membrane-less self-driven system for both lithium extraction and electricity generation according to claim 5, characterized in that: In step (A1), the mass ratio of the highly selective lithium ion electrode material, the conductive agent, and the binder is 7 to 8:1 to 2:1; The solid content of the mixed slurry is 75-85%; In step (A2), the coating amount of the mixed slurry is 1 mg / cm 2 ~100mg / cm 2 ; The drying process is carried out under vacuum conditions, at a temperature of 90-110°C, for more than 24 hours.

7. A method for using the membraneless self-driven system for lithium extraction and electricity generation as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: (S1) placing the anode and the cathode in an electrolytic cell containing a lithium-containing electrolyte, and using a constant current discharge mode to enable the cathode to extract lithium from the lithium-containing electrolyte; (S2) After step (S1) is completed, the cathode electrode is cleaned and placed in an oxygen-saturated NH4Cl aqueous solution for self-oxidation to release lithium ions.

8. The method for using the membraneless self-driving system for both lithium extraction and electricity generation according to claim 7, characterized in that: In step (S1), during the constant current discharge process, 1.2-3.3 mA cm -2 .

9. The method for using the membraneless self-driving system for both lithium extraction and electricity generation according to claim 7, characterized in that: In step (S1), during the self-oxidation treatment, the temperature is 5 to 40° C. and the time is 0.5 h to 24 h.

10. Use of the membraneless self-driven system for lithium extraction and electric energy generation as claimed in any one of claims 1 to 6 in lithium extraction.

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