Modular device for electrochemical lithium extraction

Abstract

Provided in the present application is a modular device for electrochemical lithium extraction. The modular device comprises at least one electrochemical adsorption unit, wherein the inside of each electrochemical adsorption unit is provided with a feed-solution chamber and a recovery-solution chamber, an anion exchange membrane being provided between the feed-solution chamber and the recovery-solution chamber; and a lithium-lean electrode is provided on the side of the feed-solution chamber facing away from the recovery-solution chamber, the lithium-lean electrode being electrically connected to a negative electrode of a power supply, and a lithium-rich electrode is provided on the side of the recovery-solution chamber facing away from the feed-solution chamber, the lithium-rich electrode being electrically connected to a positive electrode of the power supply. In the present application, by means of the modular structural configuration of an electrochemical adsorption unit, the power consumption for lithium extraction is reduced due to a reduction in the distance between electrodes, and high-ratio concentration of lithium is achieved; scalable control over a lithium extraction device is achieved by means of adding or removing the electrochemical adsorption unit; and the present device has a simple structure and involves easy operation overall, runs continuously and stably, and realizes green, continuous and efficient extraction and recovery of lithium from a low-lithium-concentration solution.

Description

A modular device for electrochemical lithium extraction Technical Field

[0001] The present application relates to the technical field of lithium extraction, for example, a modular device for electrochemical lithium extraction, and in particular, to a membrane block device for electrochemical adsorption lithium extraction. Background Art

[0002] Lithium, hailed as the "energy metal of the 21st century" and the "white oil of the future," is one of the most electrochemically active metals. Lithium and its compounds are widely used in various fields, including batteries, ceramics, glass, the nuclear industry, medicine, and aerospace. Lithium resources are widely found in ores and salt lake brines. Due to the high lithium content and abundant resources in salt lakes, the cost of extracting lithium from salt lakes is approximately half that of extracting lithium from ores. Therefore, extracting lithium from salt lake brines offers significant advantages.

[0003] Currently, the main methods for extracting lithium from salt lake brine include precipitation, solvent extraction, adsorption, and electrodialysis. Among them, the more traditional evaporation crystallization / precipitation method is mostly used in systems with high lithium ion concentrations and low magnesium-to-lithium ratios. For solution systems with low lithium ion concentrations and high magnesium-to-lithium ratios, solvent extraction and adsorption are promising methods. However, solvent extraction consumes a large amount of organic solvents, and the adsorption method uses a large amount of acidic solution during the desorption process, causing environmental pollution.

[0004] With the deepening of technological cross-fertilization, the fusion of traditional adsorption and electrochemical technologies has led to the emergence of electrochemical adsorption lithium extraction based on the principles of lithium batteries. This method enhances the efficiency of lithium extraction from active materials and demonstrates significant advantages in low-grade solutions with complex coexisting ions. From the perspective of the future industrial development of electrochemical lithium recovery systems, the design and operating parameters of electrochemical reactors are critical. However, due to the low lithium ion concentration and high magnesium-to-lithium ratio in brines, the lithium extraction rate during electrochemical adsorption lithium extraction is relatively low. Furthermore, the devices used for electrochemical adsorption lithium extraction suffer from problems such as large plate spacing, insufficient brine flow, and poor solution mass transfer, which seriously affect the lithium extraction capacity and energy consumption during electrochemical adsorption lithium extraction. Therefore, given the high magnesium-to-lithium ratio and low lithium content in brines, how to achieve efficient extraction of high magnesium-to-lithium ratio brines and low-grade lithium resources has become a hot topic of research.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] The present application provides a modular device for electrochemical lithium extraction. In the present application, the distance between electrodes is reduced by setting the modular structure of the electrochemical adsorption unit, which is beneficial to reducing the solution resistance and reducing the power consumption of lithium extraction; by adjusting the flow rate of the raw liquid and the recovery liquid, high concentration of lithium is achieved, and the electrochemical adsorption unit can be controlled according to production needs. By adding or reducing electrochemical adsorption units, the scale control of the lithium extraction device can be achieved. The overall structure and operation are simple, the operation is continuous and stable, and the effect of green, continuous and efficient extraction and recovery of lithium from low lithium concentration solution is achieved.

[0008] The present application provides a modular device for electrochemical lithium extraction, which includes at least one electrochemical adsorption unit, each of which is provided with a raw liquid chamber and a recovery liquid chamber, and an anion exchange membrane is provided between the raw liquid chamber and the recovery liquid chamber; the raw liquid chamber is provided with a lithium-poor electrode on the side facing away from the recovery liquid chamber, and the lithium-poor electrode is electrically connected to the negative electrode of the power supply; the recovery liquid chamber is provided with a lithium-rich electrode on the side facing away from the raw liquid chamber, and the lithium-rich electrode is electrically connected to the positive electrode of the power supply.

[0009] In the present application, the modular structure of the electrochemical adsorption unit is set up to reduce the distance between the electrodes, which is beneficial to reducing the solution resistance and the power consumption of lithium extraction; by adjusting the flow rate of the raw liquid and the recovery liquid, high concentration of lithium is achieved; the electrochemical adsorption unit can be controlled according to production needs, and the scale control of the lithium extraction device can be achieved by adding or reducing electrochemical adsorption units. The overall structure and operation are simple, the operation is continuous and stable, and the effect of green, continuous and efficient extraction and recovery of lithium from low lithium concentration solution is achieved.

[0010] It should be noted that the related technical solution adopts an electrochemical lithium recovery device composed of multiple electrochemical basic unit devices connected in series, but in the process of lithium extraction, the operation of lithium adsorption and analysis is independent and carried out alternately in steps, the process is relatively complicated, and the lithium extraction effect is not good; there is also a continuous electrochemical element extraction system, but the lithium extraction system has only one electrode that transfers from the extraction tank to the recovery tank, and the extraction and recovery are carried out in steps. The lithium extraction efficiency is low and the energy consumption is high, which is not suitable for large-scale use. Therefore, in this application, a modular design is carried out for the electrochemical adsorption unit, and an anion exchange membrane is installed in parallel and spaced apart in the electrochemical adsorption unit. The anion exchange membrane separates the unit into a raw liquid chamber and a recovery liquid chamber. The raw liquid chamber and the recovery liquid chamber are arranged alternately, and the raw liquid chamber and the recovery liquid chamber are provided with an inlet and outlet. The electric field between the raw liquid chamber and the recovery liquid chamber is switched by the electrode to achieve lithium separation from the raw material and enrichment in the recovery liquid, which solves the above problems, operates continuously and stably, and achieves the effect of green, continuous and efficient extraction and recovery of lithium from a low lithium concentration solution.

[0011] Furthermore, the modular device in the present application can increase the lithium extraction rate by adding or reducing the raw liquid chamber and the recovery liquid chamber or changing the electrode exchange frequency according to the different lithium concentrations in the raw materials, and increase the lithium enrichment multiple in the recovery liquid by changing the relative flow rates of the raw materials and the recovery liquid.

[0012] In one embodiment, the modular device further includes a raw liquid storage tank and a recovery liquid storage tank, wherein the raw liquid storage tank supplies liquid to the raw liquid chamber via a first driving member, and the recovery liquid storage tank supplies liquid to the recovery liquid chamber via a second driving member.

[0013] It should be noted that the specific shape, size and material of the raw liquid storage tank and the recovered liquid storage tank are not particularly limited in this application, and those skilled in the art can make adaptive adjustments based on actual conditions.

[0014] Optionally, the first driving member and the second driving member are identical. It should be noted that the present application does not impose any particular limitations on the specific structure, shape, size, and material of the first and second driving members, and those skilled in the art may make adaptive adjustments based on actual circumstances. The first driving member may be a peristaltic pump, and further, the peristaltic pump may be configured to adjust the speed of the peristaltic pump to change the flow rate of the pumped solution, thereby achieving maximum lithium ion capture in solutions with different lithium ion concentrations.

[0015] In one embodiment, each of the electrochemical adsorption units is connected via a connector.

[0016] Optionally, the connector is a solid gasket. It should be noted that the specific shape and size of the solid gasket are not particularly limited in this application. It is mainly used to separate each electrochemical adsorption unit to achieve a continuous and stable operation effect. Those skilled in the art can make adaptive adjustments based on actual conditions. The solid gasket can be a solid fluororubber gasket.

[0017] In one embodiment, each of the raw liquid chambers is connected in series or in parallel via a connecting pipe.

[0018] It should be noted that when each raw liquid chamber in the present application is connected in series through a connecting tube, the overall operation increases the extraction rate; when connected in parallel, a higher lithium extraction rate is presented.

[0019] Optionally, each of the recovery liquid chambers is connected in series or in parallel via a pipeline.

[0020] It should be noted that when each recovery liquid chamber in the present application is connected in series through a pipeline, the overall operation achieves a high concentration of lithium in the recovery liquid.

[0021] In one embodiment, on the side of the stock solution chamber facing away from the recovered solution chamber, a first pressing plate, a first gasket, the lithium-depleted electrode, and a second gasket are sequentially stacked along the direction approaching the stock solution chamber.

[0022] It should be noted that the present application does not specifically limit the materials of the first gasket and the second gasket, and those skilled in the art can make adaptive adjustments according to the actual situation. Among them, the materials of the first gasket and the second gasket can be the same or different, and the specific material can be fluororubber.

[0023] Optionally, the first pressing plate, the first gasket, the lithium-depleted electrode, and the second fluorine gasket are fixedly connected through mounting holes.

[0024] Optionally, the lithium-depleted electrode includes a first current collector and a first electrode material that are sequentially stacked along the direction approaching the stock solution chamber.

[0025] Optionally, the first current collector is a cathode current collector.

[0026] Optionally, the material of the first current collector is any one of titanium mesh, titanium foil, and carbon fiber cloth.

[0027] It should be noted that the present application does not specifically limit the specific shape, size, etc. of the first current collector, and those skilled in the art can make adaptive adjustments according to the actual situation.

[0028] Optionally, the active material used in the first electrode material is Li 1-x Mn2O4, Li 1-x Ni y Co z Mn 1-y-z O2 and Li 1-x FePO4, where 0 < x < 1.

[0029] It should be noted that in the present application, "0 < x < 1" is applied to Li 1-x Mn2O4, Li 1-x Ni y Co z Mn 1-y-z O2 and Li 1-x FePO4, that is, multiple chemical formulas share one x, and the selection range of x in different chemical formulas is this range. However, when selecting x in each chemical formula, they are independent of each other, and can be the same or different, and are not restricted by each other.

[0030] In one embodiment, on the side of the recovered solution chamber facing away from the stock solution chamber, a third gasket, the lithium-rich electrode, a fourth gasket, and a second pressing plate are sequentially stacked along the direction away from the recovered solution chamber.

[0031] It should be noted that the present application does not impose any particular restrictions on the materials of the third and fourth gaskets, and those skilled in the art may make adaptive adjustments based on actual conditions. The materials of the third and fourth gaskets may be the same or different, and the specific material may be fluororubber.

[0032] Optionally, the third gasket, the lithium-rich electrode, the fourth gasket and the second pressing plate are fixedly connected through mounting holes.

[0033] Optionally, the lithium-rich electrode includes a second electrode material and a second current collector stacked in sequence in a direction away from the recovery liquid chamber.

[0034] Optionally, the second current collector is an anode current collector.

[0035] Optionally, the second current collector is made of any one of titanium mesh, titanium foil and carbon fiber cloth.

[0036] It should be noted that the specific shape, size, etc. of the second current collector are not particularly limited in this application, and those skilled in the art can make adaptive adjustments based on actual conditions.

[0037] Optionally, the active material used in the second electrode material is LiMn2O4, LiNi x Co y Mn 1-x-y Any one of O2 and LiFePO4, where 0 <x+y<1。

[0038] In one embodiment, both the first gasket and the fourth gasket are hollow structures.

[0039] Optionally, the hollow portion of the first gasket hollow structure and the hollow portion of the fourth gasket hollow structure have the same area.

[0040] Optionally, the area of ​​the hollow portion is greater than or equal to the area of ​​the lithium-poor electrode and / or the lithium-rich electrode.

[0041] In the present application, the area of ​​the hollowed-out portion is greater than or equal to the area of ​​the lithium-poor electrode and / or the lithium-rich electrode because the lithium-poor electrode is sealed at this size, which can prevent water from seeping into the lithium-poor electrode.

[0042] In one embodiment, the thickness of the first gasket is greater than or equal to the thickness of the lithium-deficient electrode.

[0043] It should be noted that the thickness of the first gasket in the present application is greater than or equal to the thickness of the lithium-poor electrode because this structure can be used to seal the lithium-poor electrode to prevent water seepage into the lithium-poor electrode.

[0044] Optionally, the thickness of the fourth gasket is greater than or equal to the thickness of the lithium-rich electrode.

[0045] It should be noted that the thickness of the fourth gasket in the present application is greater than or equal to the thickness of the lithium-rich electrode because this structure can be used to seal the lithium-rich electrode to prevent water seepage into the lithium-rich electrode.

[0046] In one embodiment, the second gasket and the third gasket are both hollow structures.

[0047] Optionally, the hollow portion of the second gasket hollow structure and the hollow portion of the third gasket hollow structure have the same area.

[0048] Optionally, the area of ​​the hollow portion is the same as the cross-sectional area of ​​the raw liquid chamber and / or the recovery liquid chamber.

[0049] Optionally, the area of ​​the hollow portion is smaller than the area of ​​the lithium-poor electrode and / or the lithium-rich electrode.

[0050] The area of ​​the hollowed-out portion in this application is smaller than the area of ​​the lithium-poor electrode and / or the lithium-rich electrode because the gasket fixes the electrode at this size. If it were not for this size, the electrode would be washed by the solution and cause physical damage.

[0051] It should be noted that the anion exchange membrane in this application can be a standard anion exchange membrane or a monovalent selective anion exchange membrane, among which a 0.13 mm thick monovalent selective anion exchange membrane can be selected. Those skilled in the art can make adaptive adjustments according to actual conditions.

[0052] In one embodiment, the areas of the hollow portions of the first gasket and the fourth gasket are both larger than the areas of the hollow portions of the second gasket and the third gasket.

[0053] Optionally, the areas of the hollow portions of the first gasket and the fourth gasket are both greater than or equal to the areas of the lithium-poor electrode and / or the lithium-rich electrode.

[0054] Compared with the related art, the beneficial effects of this application are:

[0055] In the present application, the modular structure of the electrochemical adsorption unit is set up to reduce the distance between the electrodes, which is beneficial to reducing the solution resistance and the power consumption of lithium extraction; by adjusting the flow rate of the raw liquid and the recovery liquid, high concentration of lithium is achieved; the electrochemical adsorption unit can be controlled according to production needs, and the scale control of the lithium extraction device can be achieved by adding or reducing electrochemical adsorption units. The overall structure and operation are simple, the operation is continuous and stable, and the effect of green, continuous and efficient extraction and recovery of lithium from low lithium concentration solution is achieved.

[0056] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0058] FIG1 is a schematic structural diagram of a modular device provided in one embodiment of the present application;

[0059] FIG2 is a schematic structural diagram of a first pressing plate or a second pressing plate in a modular device provided in a specific embodiment of the present application;

[0060] FIG3 is a schematic structural diagram of a first gasket in a modular device provided in a specific embodiment of the present application;

[0061] FIG4 is a schematic structural diagram of a raw liquid chamber and a recovery liquid chamber in a modular device provided in one embodiment of the present application;

[0062] FIG5 is a schematic structural diagram of a second gasket in a modular device provided in a specific embodiment of the present application;

[0063] FIG6 is a graph showing changes in lithium extraction capacity of the modular device provided in Example 1 at different membrane surface flow rates;

[0064] FIG7 is a schematic structural diagram of a conventional H-type electrolytic cell provided in Comparative Example 1;

[0065] Among them, 1-first compression plate; 2-first current collector; 3-first gasket; 4-second gasket; 5-raw liquid chamber; 6-recovery liquid chamber; 7-third gasket; 8-fourth gasket; 9-second current collector; 10-solid gasket; 11-water outlet pipe; 12-water inlet pipe;

[0066] 13-Raw material chamber; 14-Recovery chamber; 15-Anion exchange membrane; 16-Lithium-poor electrode; 17-Lithium-rich electrode; 18-Power switch. DETAILED DESCRIPTION

[0067] It should be understood that in the description of this application, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, "multiple" means two or more.

[0068] It should be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0069] Those skilled in the art should understand that this application must include necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not belong to the main application point of this application. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and this application does not make special requirements and specific limitations on this.

[0070] The technical solution of the present application will be further explained below with reference to the accompanying drawings and through specific implementation methods.

[0071] In a specific embodiment, the present application provides a modular device for electrochemical lithium extraction, as shown in Figures 1 to 5, the modular device includes at least one electrochemical adsorption unit, each electrochemical adsorption unit is provided with a raw liquid chamber 5 and a recovery liquid chamber 6, and an anion exchange membrane 15 is provided between the raw liquid chamber 5 and the recovery liquid chamber 6; the raw liquid chamber 5 is provided with a lithium-poor electrode 16 on the side facing away from the recovery liquid chamber 6, and the lithium-poor electrode 16 is electrically connected to the negative pole of the power supply, and the recovery liquid chamber 6 is provided with a lithium-rich electrode 17 on the side facing away from the raw liquid chamber 5, and the lithium-rich electrode 17 is electrically connected to the positive pole of the power supply.

[0072] In the present application, by setting up a modular structure of the electrochemical adsorption unit and adjusting the flow rate of the raw material and the recovered liquid, high concentration of lithium is achieved, the distance between the electrodes is reduced, which is beneficial to reducing the solution resistance and reducing the power consumption of lithium extraction. The electrochemical adsorption unit can be controlled according to production needs, and low-carbon extraction of lithium resources can be achieved by adding or reducing electrochemical adsorption units. The overall structure and operation are simple, the operation is continuous and stable, and the effect of green, continuous and efficient extraction and recovery of lithium from low lithium concentration solutions is achieved.

[0073] It should be noted that the relevant technical solution adopts an electrochemical lithium recovery device composed of multiple electrochemical basic unit devices connected in series. However, during the lithium extraction process, the operations of lithium adsorption and desorption are independent and performed alternately in steps. The process is relatively complicated and the lithium extraction effect is not good. There is also a continuous electrochemical element extraction system, but this lithium extraction system has only one electrode that transfers from the extraction tank to the recovery tank. The extraction and recovery are carried out in steps. The lithium extraction efficiency is low and the energy consumption is high, and both are not suitable for large-scale use. Therefore, in this application, a modular design is carried out for the electrochemical adsorption unit, and anion exchange membranes 15 are installed in parallel and at intervals in the electrochemical adsorption unit. The anion exchange membranes 15 separate the unit into a raw liquid chamber 5 and a recovery liquid chamber 6. The raw liquid chamber 5 and the recovery liquid chamber 6 are arranged alternately, and water inlets and outlets are provided on the raw liquid chamber 5 and the recovery liquid chamber 6. The electric field between the raw liquid chamber 5 and the recovery liquid chamber 6 is switched by electrodes to achieve lithium separation from the raw material and enrichment in the recovery liquid, thereby solving the above-mentioned problems, operating continuously and stably, and achieving the effect of green, continuous and efficient extraction and recovery of lithium from low lithium concentration solutions.

[0074] Furthermore, the modular device in the present application can increase the lithium extraction rate by adding or reducing the raw liquid chamber 5 and the recovery liquid chamber 6 or changing the electrode exchange frequency according to the different lithium concentrations in the raw material, and increase the lithium enrichment multiple in the recovery liquid by changing the relative flow rates of the raw material and the recovery liquid.

[0075] Furthermore, the modular device further includes a raw liquid storage tank and a recovery liquid storage tank. The raw liquid storage tank supplies liquid to the raw liquid chamber 5 via a first driving member, and the recovery liquid storage tank supplies liquid to the recovery liquid chamber 6 via a second driving member. It should be noted that the specific shape, size, and material of the raw liquid storage tank and the recovery liquid storage tank are not particularly limited in this application, and those skilled in the art can make adaptive adjustments based on actual conditions.

[0076] Furthermore, the first driving member and the second driving member are identical. It should be noted that the specific structure, shape, size, and material of the first driving member and the second driving member are not particularly limited in this application, and those skilled in the art can make adaptive adjustments based on actual conditions. Among them, the first driving member can be a peristaltic pump. Furthermore, the peristaltic pump can adjust the speed of the peristaltic pump to change the flow rate of the pumped solution to meet the maximum lithium ion capture requirements of original solutions with different lithium ion concentrations.

[0077] Furthermore, each electrochemical adsorption unit is connected by a connector, which is a solid gasket 10. It should be noted that the specific shape and size of the solid gasket 10 are not particularly limited in this application. It is mainly used to separate each electrochemical adsorption unit to form a continuous and stable operation effect. Those skilled in the art can make adaptive adjustments based on actual conditions.

[0078] Furthermore, each raw liquid chamber 5 is connected in series or in parallel via a connecting pipe, and each recovered liquid chamber 6 is connected in series or in parallel via a pipeline.

[0079] Furthermore, on the side of the raw liquid chamber 5 facing away from the recovery liquid chamber 6, a first compression plate 1, a first gasket 3, a lithium-poor electrode 16 and a second gasket 4 are stacked in sequence along the direction close to the raw liquid chamber 5, and the first compression plate 1, the first gasket 3, the lithium-poor electrode 16 and the second gasket 4 are fixedly connected through mounting holes.

[0080] Furthermore, the lithium-deficient electrode 16 includes a first current collector 2 and a first electrode material stacked sequentially along a direction close to the stock solution chamber 5. The first current collector 2 is a cathode current collector and is made of any one of titanium mesh, titanium foil, and carbon fiber cloth. It should be noted that the specific shape and size of the first current collector 2 are not particularly limited in this application, and those skilled in the art may make adaptive adjustments based on actual conditions.

[0081] Furthermore, the active material used in the first electrode material is Li 1-x Mn2O4、Li 1-x Ni y Co z Mn 1-y-z O2 and Li 1-x Any one of FePO4, where 0 <x<1。

[0082] Furthermore, on the side of the recovery liquid chamber 6 facing away from the original liquid chamber 5, a third gasket 7, a lithium-rich electrode 17, a fourth gasket 8 and a second pressure plate are stacked in sequence along the direction away from the recovery liquid chamber 6, and the third gasket 7, the lithium-rich electrode 17, the fourth gasket 8 and the second pressure plate are fixedly connected through the mounting holes.

[0083] Furthermore, the lithium-rich electrode includes a second electrode material and a second current collector 9 stacked sequentially in a direction away from the recovery liquid chamber 6. The second current collector 9 is an anode current collector and is made of any one of titanium mesh, titanium foil, and carbon fiber cloth. It should be noted that the specific shape and size of the second current collector 9 are not particularly limited in this application, and those skilled in the art may make adaptive adjustments based on actual circumstances.

[0084] Furthermore, the active material used in the second electrode material is LiMn2O4, LiNi x Co y Mn 1-x-y Any one of O2 and LiFePO4, where 0 <x+y<1。

[0085] Furthermore, the first gasket 3 and the fourth gasket 8 are both hollow structures, and the area of ​​the hollow part of the hollow structure of the first gasket 3 and the hollow part of the hollow structure of the fourth gasket 8 are the same, and the area of ​​the hollow part is greater than or equal to the area of ​​the lithium-poor electrode 16 and / or the lithium-rich electrode 17.

[0086] Furthermore, the thickness of the first gasket 3 is greater than or equal to the thickness of the lithium-poor electrode 16. It should be noted that the thickness of the first gasket 3 is greater than or equal to the thickness of the lithium-poor electrode 16 in this application because this structure can be used to seal the lithium-poor electrode 16 to prevent water seepage.

[0087] Furthermore, the thickness of the fourth gasket 8 is greater than or equal to the thickness of the lithium-rich electrode 17. It should be noted that the thickness of the fourth gasket 8 is greater than or equal to the thickness of the lithium-rich electrode 17 in this application because this structure can be used to seal the lithium-rich electrode 17 to prevent water seepage.

[0088] Furthermore, the second gasket 4 and the third gasket 7 are both hollow structures, the area of ​​the hollow part of the hollow structure of the second gasket 4 is the same as the area of ​​the hollow part of the hollow structure of the third gasket 7, the area of ​​the hollow part is the same as the cross-sectional area of ​​the original liquid chamber 5 and / or the recovery liquid chamber 6, and the area of ​​the hollow part is smaller than the area of ​​the lithium-poor electrode 16 and / or the lithium-rich electrode 17.

[0089] Furthermore, the anion exchange membrane 15 is an anion selective permeable membrane. It should be noted that the anion exchange membrane 15 in the present application can be a common anion exchange membrane or a monovalent selective anion exchange membrane, wherein a 0.13 mm thick monovalent selective anion exchange membrane can be selected. Those skilled in the art can make adaptive adjustments according to actual conditions.

[0090] The hollow areas of the first gasket 3 and the fourth gasket 8 are larger than those of the second gasket 4 and the third gasket 7. The hollow areas of the first gasket 3 and the fourth gasket 8 are larger than or equal to the area of ​​the lithium-poor electrode 16 and / or the lithium-rich electrode 17.

[0091] Example 1

[0092] This embodiment provides a modular device for electrochemical lithium extraction, wherein:

[0093] The modular device includes an electrochemical adsorption unit, which is provided with a raw liquid chamber 5 and a recovery liquid chamber 6, and an anion exchange membrane 15 is provided between the raw liquid chamber 5 and the recovery liquid chamber 6; the raw liquid chamber 5 is provided with a lithium-poor electrode 16 on the side facing away from the recovery liquid chamber 6, and the lithium-poor electrode 16 is electrically connected to the negative pole of the power supply; the recovery liquid chamber 6 is provided with a lithium-rich electrode 17 on the side facing away from the raw liquid chamber 5, and the lithium-rich electrode 17 is electrically connected to the positive pole of the power supply.

[0094] The electrochemical adsorption unit is installed as follows: a 30mm thick first compression plate 1 is placed, followed by a 0.4mm thick first gasket 3, a first current collector 2, a first electrode material, a 1mm thick second gasket 4, a raw liquid chamber 5, a first monovalent anion exchange membrane 15, a recovery liquid chamber 6, a 1mm thick third gasket 7, a second electrode material, a second current collector 9, a 0.4mm thick fourth gasket 8, and finally a 30mm thick second compression plate. At this point, the raw liquid chamber 5 is 10mm thick, and the recovery liquid chamber 6 is 10mm thick. Each component is compressed and secured with a matching nut using a screw rod with a length of 145mm and a diameter of 3.5mm.

[0095] The electrochemical lithium extraction process of the above-mentioned modular device includes: connecting the electrochemical adsorption unit to the external pipeline, and using the electrochemical adsorption method to treat the mixed solution with a high magnesium-to-lithium ratio and low lithium concentration, wherein the raw liquid volume is 200mL, the lithium concentration is 0.0072mol / L, and the magnesium concentration is 1mol / L; the recovery liquid volume is 200mL, and the concentration is 0.05mol / L KCl solution. Under different membrane surface flow rates as the investigation conditions, the raw liquid lithium concentration and the recovery liquid lithium concentration are sampled and analyzed, and the lithium extraction capacity and current efficiency are calculated.

[0096] Furthermore, the specific calculation methods of ion electrochemical adsorption capacity, average ion electrochemical adsorption rate, current efficiency and electrochemical adsorption energy consumption are as follows:

[0097] (1) Ion electrochemical adsorption capacity

[0098] The electrochemical adsorption capacity of ions (EM) is the electrochemical adsorption capacity of target ions per unit effective mass of electrode material. The calculation formula is as follows:

[0099] Among them, E M is the electrochemical adsorption capacity of the electrode material for the target metal ion (mg / g); C R is the target metal ion concentration in the recovery solution (mg / L); V R is the volume of the recovery solution (mL); C i is the target metal ion concentration in the sample taken for the i-th time (mg / L); V i is the volume of the sample taken for the i-th time (mL); w is the active material in the electrode.

[0100] (2) Average ion electrochemical adsorption rate

[0101] Average electrochemical adsorption rate of metal ions M ) is the electrochemical adsorption capacity of ions per unit effective mass of electrode material per unit time. The calculation formula is as follows:

[0102] Among them, r M is the electrochemical adsorption rate of the target metal ion (mg / (g·min)); E M is the electrochemical adsorption capacity of the electrode material for the target metal ion (mg / g); t is the electrochemical adsorption time (min).

[0103] (3) Current efficiency

[0104] Current efficiency (η) is the percentage of the charge required for lithium ions to migrate out of the electrode material as a percentage of the total charge applied to the electrode material by the power source. The calculation formula is as follows:

[0105] Where, η is the current efficiency (%); F is the Faraday constant (96485C / moL); E Li is the electrochemical adsorption lithium capacity of the electrode material (mg / g); w is the effective mass of the active material in the electrode (g); M Li is the molar mass of Li (6.941 g / moL); t is the electrochemical adsorption time (s); I(t) is the current corresponding to time t during the electrochemical adsorption process (A).

[0106] (4) Electrochemical adsorption energy consumption

[0107] Specific energy consumption (E sec ) is the electrical energy required for electrochemical adsorption of lithium ions per unit mole. The calculation formula is as follows:

[0108] Among them, E sec is the electrical energy consumed by electrochemical adsorption of unit mole of lithium ions (Wh / mol Li); M Li is the molar mass of Li (6.941 g / moL); U is the voltage applied between the two electrodes (V); t is the electrochemical adsorption time (s); I(t) is the current corresponding to time t during the electrochemical adsorption process (A). Li is the electrochemical adsorption lithium capacity of the electrode material (mg / g); w is the effective mass of the active material in the electrode (g).

[0109] Ultimately, the lithium extraction capacity reached 35.72 mg / g, the lithium extraction rate was 0.21 mg / g·min, and the energy consumption was only 3.03 Wh / mol Li.

[0110] As shown in Figure 6, different membrane surface flow rates lead to different thicknesses of the boundary layer between the electrode and the solution. When the membrane surface flow rate is too small, the boundary layer between the electrode and the aqueous solution is thicker, and the solution in the chamber suffers from concentration polarization during the electrochemical adsorption process, resulting in low lithium extraction capacity and efficiency. Appropriate membrane surface flow rate will make the electrode interface boundary layer thinner, effectively suppressing the concentration polarization phenomenon and achieving a better adsorption effect.

[0111] Comparative Example 1

[0112] This comparative example provides a traditional H-type electrolytic cell, as shown in FIG7 , wherein:

[0113] The H-type electrolytic cell includes a recovery chamber 14 and a raw material chamber 13 , an anion exchange membrane 15 is provided between the recovery chamber 14 and the raw material chamber 13 , a lithium-rich electrode 17 is provided in the recovery chamber 14 , and a lithium-poor electrode 16 is provided in the raw material chamber 13 .

[0114] The specific installation method of the above-mentioned H-type electrolytic cell includes: a positive ion exchange membrane 15 is used to separate the positive ion recovery chamber 14 and the feed chamber 13. The positive ion exchange membrane 15 is provided in the positive ion recovery chamber 14, and the feed chamber 13 is provided with a lithium-poor electrode 16 ... potassium chloride solution. The mixed solution of high magnesium-lithium ratio and low lithium concentration is provided in the feed chamber 13. During the experiment, the solution in the feed chamber 13 is in a stirring state to eliminate concentration polarization.

[0115] The operating steps of the above-mentioned H-type electrolytic cell include: placing a lithium-rich lithium manganate membrane electrode in the recovery chamber 14, placing a lithium-poor lithium manganate membrane electrode in the raw material chamber 13, applying a constant electric field between the two electrodes, and completing the electrochemical lithium adsorption experiment through control by the electrode switch 18.

[0116] As can be seen from Table 1 below, compared with the traditional H-type electrolytic cell, the modular device of the present application has lower energy consumption and higher lithium extraction capacity for electrochemical adsorption lithium extraction.

[0117] Table 1 Performance data results of examples and comparative examples

[0118] In summary, the present application reduces the distance between electrodes through the modular structure setting of the electrochemical adsorption unit, which is beneficial to reducing the solution resistance and reducing the power consumption of lithium extraction; by adjusting the flow rate of the raw liquid and the recovery liquid, high concentration of lithium is achieved; the electrochemical adsorption unit can be controlled according to production needs, and the scale control of the lithium extraction device can be achieved by adding or reducing electrochemical adsorption units. The overall structure and operation are simple, the operation is continuous and stable, and the effect of green, continuous and efficient extraction and recovery of lithium from low lithium concentration solution is achieved.

[0119] The above description is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application fall within the protection scope and disclosure scope of the present application.

Claims

1. A modular device for electrochemical lithium extraction, wherein: The modular device comprises at least one electrochemical adsorption unit, each of which is provided with a raw liquid chamber and a recovery liquid chamber, and an anion exchange membrane is provided between the raw liquid chamber and the recovery liquid chamber; The raw liquid chamber is provided with a lithium-poor electrode on the side facing away from the recovery liquid chamber, and the lithium-poor electrode is electrically connected to the negative electrode of the power supply. The recovery liquid chamber is provided with a lithium-rich electrode on the side facing away from the raw liquid chamber, and the lithium-rich electrode is electrically connected to the positive electrode of the power supply.

2. The modular device according to claim 1, wherein: The modular device also includes a raw liquid storage tank and a recovery liquid storage tank. The raw liquid storage tank supplies liquid to the raw liquid chamber through a first driving member, and the recovery liquid storage tank supplies liquid to the recovery liquid chamber through a second driving member.

3. The modular device according to claim 2, wherein: The first drive member and the second drive member are identical.

4. A modular device according to any one of claims 1 to 3, wherein: Each of the electrochemical adsorption units is connected via a connector; Optionally, the connecting member is a solid gasket.

5. A modular device according to any one of claims 1 to 4, wherein: Each of the raw liquid chambers is connected in series or in parallel via a connecting pipe.

6. A modular device according to any one of claims 1 to 5, wherein: Each of the recovery liquid chambers is connected in series or in parallel via a pipeline.

7. A modular device according to any one of claims 1 to 6, wherein: On one side of the raw liquid chamber facing away from the recovery liquid chamber, a first pressing plate, a first gasket, the lithium-deficient electrode and a second gasket are sequentially stacked along a direction close to the raw liquid chamber; Optionally, the first pressing plate, the first gasket, the lithium-deficient electrode and the second gasket are fixedly connected via mounting holes.

8. A modular device according to any one of claims 1 to 7, wherein: The lithium-deficient electrode comprises a first current collector and a first electrode material which are sequentially stacked along a direction close to the original solution chamber; Optionally, the first current collector is a cathode current collector; Optionally, the first current collector is made of any one of titanium mesh, titanium foil and carbon fiber cloth.

9. A modular device according to claim 8, wherein: The active material used in the first electrode material is Li 1-x Mn2O4、Li 1-x Ni v Co z Mn 1-y-z O2 and Li 1-x Any one of FePO4, wherein 0<x<1.

10. A modular device according to any one of claims 7 to 9, wherein: On one side of the recovery liquid chamber facing away from the original liquid chamber, a third gasket, the lithium-rich electrode, a fourth gasket, and a second pressing plate are sequentially stacked in a direction away from the recovery liquid chamber; Optionally, the third gasket, the lithium-rich electrode, the fourth gasket and the second pressing plate are fixedly connected via mounting holes.

11. A modular device according to any one of claims 7 to 10, wherein: The lithium-rich electrode comprises a second electrode material and a second current collector which are sequentially stacked in a direction away from the recovery liquid chamber; Optionally, the second current collector is an anode current collector; Optionally, the material of the second current collector is any one of titanium mesh, titanium foil and carbon fiber cloth; Optionally, the active material used in the second electrode material is LiMn2O4, LiNi x Co v Mn 1-x-v Any one of O2 and LiFePO4, wherein 0<x+y<1.

12. A modular device according to claim 10 or 11, wherein: The first gasket and the fourth gasket are both hollow structures; Optionally, the hollow portion of the first gasket hollow structure and the hollow portion of the fourth gasket hollow structure have the same area; Optionally, the area of ​​the hollow portion is greater than or equal to the area of ​​the lithium-poor electrode and / or the lithium-rich electrode. area.

13. A modular device according to any one of claims 10 to 12, wherein: The thickness of the first gasket is greater than or equal to the thickness of the lithium-poor electrode; Optionally, the thickness of the fourth gasket is greater than or equal to the thickness of the lithium-rich electrode.

14. A modular device according to any one of claims 10 to 13, wherein: The second gasket and the third gasket are both hollow structures; Optionally, the hollow portion of the second gasket hollow structure and the hollow portion of the third gasket hollow structure have the same area; Optionally, the area of ​​the hollow portion is the same as the cross-sectional area of ​​the raw liquid chamber and / or the recovery liquid chamber; Optionally, the area of ​​the hollow portion is smaller than the area of ​​the lithium-poor electrode and / or the lithium-rich electrode.

15. A modular device according to claim 14, wherein: The areas of the hollow parts of the first gasket and the fourth gasket are both larger than the areas of the hollow parts of the second gasket and the third gasket; Optionally, the areas of the hollow parts of the first gasket and the fourth gasket are both greater than or equal to the areas of the lithium-poor electrode and / or the lithium-rich electrode.

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