Method for preparing electrode based on 3D printing and its application in electrochemical lithium extraction

Abstract

The present invention relates to the technical field of the manufacture of electrodes for electrochemical lithium extraction, and particularly to a method for preparing electrodes based on 3D printing technology and its application in electrochemical lithium extraction. The present invention uses a 3D printing device to eject a printing slurry with a specific formulation to form an electrode. The obtained porous electrode has a high loading amount and excellent structural stability, and exhibits excellent lithium separation performance in an aqueous solution containing lithium, overcoming the problems of small loading amount, low processing efficiency, and easy cracking of traditional thin film electrodes during the process of electrochemical lithium extraction.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing electrochemically lithium-extracting electrodes, and particularly relates to a method for preparing an electrode based on 3D printing technology and its application in electrochemically extracting lithium (separating lithium in lithium-containing brine). Background Art

[0002] In the preparation process of electrochemically lithium-extracting electrodes, the preparation and performance of electrode materials directly affect the overall performance of the electrochemically lithium-extracting system. Due to structural limitations of traditional thin-film electrodes, there are usually problems such as small loading capacity, poor electrolyte permeability, and long ion transport paths, resulting in limitations in lithium extraction performance and cycle life. In addition, cracks are easily caused during the production process of thin-film electrodes, thus affecting the mechanical stability and electrochemical performance of the electrodes.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] To solve the above technical problems, the present invention combines the advantages of 3D printing to provide a method for preparing an electrode based on 3D printing technology and applies it to electrochemically extracting lithium from lithium-containing brine.

[0005] Specifically, the technical solution of the present invention is as follows:

[0006] In the first aspect, the present invention provides a method for preparing an electrode based on 3D printing technology, using a 3D printing device to eject a printing slurry to form an electrode; the printing slurry includes a lithium-extracting active material, a binder, a conductive agent, and a solvent; in the printing slurry, the content of the lithium-extracting active material is 50wt% - 95wt%, the content of the binder is 2wt% - 20wt%, and the content of the conductive agent is 3wt% - 30wt%; the ratio of the binder to the solvent is 5:95 - 95:5.

[0007] The electrochemically lithium-extracting electrode obtained by the present invention has pores, high surface density and thickness, as well as good chemical stability and mechanical stability. When used for electrochemically extracting lithium from brine, it has the advantages of high lithium extraction rate and good adsorption selectivity.

[0008] In the present invention, the lithium-extracting active material includes, but is not limited to, lithium manganate, lithium iron phosphate, lithium manganese iron phosphate, aluminum hydroxide hydrotalcite, lithium titanate and its doped compounds, or other metal oxides and their doped compounds; preferably at least one of lithium manganate, lithium iron phosphate, and lithium manganese iron phosphate.

[0009] In the present invention, the conductive agent is preferably at least one of conductive carbon, carbon nanotubes, and graphene.

[0010] In the present invention, the binder includes but is not limited to polyvinylidene fluoride, carboxymethyl cellulose, polyacrylic acid, sodium alginate, polyvinyl alcohol and other organic / inorganic binders; preferably polyvinylidene fluoride.

[0011] In the present invention, the solvent includes but is not limited to water, N-methylpyrrolidone, dimethyl sulfoxide, dichloromethane, ethanol, isopropanol and other organic solvents; preferably N-methylpyrrolidone.

[0012] The present invention does not particularly limit the sources of the above raw materials, and conventional commercially available products in the art can be used.

[0013] Furthermore, in the present invention, after the printing slurry is ejected by the 3D printing device, a drying step is preferably included; the drying temperature is preferably 25~80 °C, and the heat preservation time for drying is preferably 10~720 min.

[0014] Furthermore, in the present invention, the nozzle diameter of the 3D printing device is preferably 0.1~2.0 mm.

[0015] In a second aspect, the present invention provides an electrode prepared by the method described in the first aspect above.

[0016] In a third aspect, the present invention provides the application of the method described in the first aspect above or the electrode described in the second aspect above in electrochemical lithium extraction.

[0017] In a fourth aspect, as a specific form of the application described in the third aspect above, the present invention provides an electrochemical lithium extraction method, in which an electrochemical lithium extraction electrode is assembled in an electro-driven ion exchange device for separating lithium ions in a lithium-containing solution; the electrochemical lithium extraction electrode is the electrode described in the second aspect above.

[0018] Beneficial effects:

[0019] The present invention provides a method for preparing an electrode based on 3D printing technology. A printing slurry with a specific formulation is ejected by a 3D printing device to form an electrode, and it is applied to the electrochemical lithium extraction of lithium-containing brine. It has been verified that the porous electrode obtained by the present invention has a high loading amount and excellent structural stability, and shows excellent lithium separation performance in lithium-containing aqueous solutions, overcoming the problems of small loading amount, low treatment efficiency, and easy cracking of traditional thin film electrodes during the process of electrochemical lithium extraction. Description of the drawings

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will describe the drawings required for use in the examples or the description of the prior art.

[0021] Figure 1Optical picture of the electrochemical lithium extraction electrode (lithium iron phosphate manganese) prepared by 3D printing technology in Example 1 of the present invention.

[0022] Figure 2 Lithium extraction capacity curves of 3D printed electrochemical lithium extraction electrodes with different shape structures in Example 1 of the present invention.

[0023] Figure 3 Bar chart of the total lithium extraction capacity of 3D printed electrochemical lithium extraction electrodes with different shape structures cycled 5 times in Example 1 of the present invention. Detailed implementation manners

[0024] The present invention proposes a method for preparing an electrode based on 3D printing technology and its application in electrochemical lithium extraction.

[0025] 3D printing technology has high flexibility and controllability in structural design and is an important electrode preparation method. By using 3D printing technology, the shape structure of the electrode can be precisely controlled, and electrodes with porous structures such as honeycomb, grid, and linear can be constructed. These porous structures can not only significantly increase the electrode loading, but also optimize the electrolyte permeability and ion transport path, while maintaining good mechanical stability, thereby improving the charge-discharge performance and cycle life of the electrode.

[0026] In the present invention, an active material, a conductive agent, and a binder are mixed to obtain a slurry, and then a direct writing type 3D printing technology is used to construct a porous electrode, followed by drying treatment. The prepared porous electrode has a high loading and excellent structural stability, and exhibits excellent lithium separation performance in an aqueous solution containing lithium, overcoming the problems of small loading, low processing efficiency, and easy cracking of traditional thin film electrodes.

[0027] In one of the more specific and preferred implementation manners provided by the present invention, the technical solution of the present invention includes the following steps:

[0028] 1) Select a 3D printing device, and the 3D printing device includes a body, a 3D printing head, a printing platform, a control system, and a raw material library;

[0029] 2) Modeling, using computer modeling software to design the model of the electrochemical lithium extraction electrode, converting the software instructions of the model into mechanical instructions for 3D printing, thereby controlling the motion data of the 3D printing head and the laser printing head, and controlling the time and height of the laser printing head;

[0030] 3) Configure the printing slurry, mix the lithium extraction active material, the conductive agent, the binder, and the solvent to form a slurry with a certain fluidity and add it to the raw material library;

[0031] 4) Use a 3D printing device to print an electrochemical lithium extraction electrode, so that the slurry is ejected from the 3D printing head onto a glass plate or a conductive substrate, and then the electrode is dried in an oven or at room temperature to prepare an electrochemical lithium extraction electrode;

[0032] 5) Assemble the electrochemical lithium extraction electrode in an electro-driven ion exchange device for separating lithium ions in the lithium-containing brine.

[0033] Among them, the lithium extraction active material in step 3) includes but is not limited to lithium manganate or a lithium manganate compound for doping, lithium iron phosphate or a lithium iron phosphate compound for doping, lithium iron manganese phosphate or a lithium iron manganese phosphate compound for doping, aluminum hydroxide hydrotalcite, lithium titanate and its doped compounds, or other metal oxides and their doped compounds; the conductive agent is specifically conductive carbon, carbon nanotubes, graphene and other conductive carbon materials; the binder is specifically polyvinylidene fluoride, carboxymethyl cellulose, polyacrylic acid, sodium alginate, polyvinyl alcohol and other organic / inorganic binders; the solvent is specifically water, N-methylpyrrolidone, dimethyl sulfoxide, dichloromethane, ethanol, isopropanol and other organic solvents; the content of the lithium extraction active material in the printing slurry is 50wt% - 95wt%, the content of the binder in the printing slurry is 2wt% - 20wt%; the content of the conductive agent in the printing slurry is 3wt% - 30wt%; the ratio of the binder to the solvent is 5:95 - 95:5.

[0034] Among them, the diameter of the 3D printing head in step 4) is adjustable, and the diameter is 0.1 - 2.0 mm; the movement path of the 3D printing head is determined according to the shape of the required electrochemical lithium extraction electrode; the up, down, left and right movement of the printing head is controlled by software to print an electrochemical lithium extraction electrode with appropriate thickness and shape; the drying temperature is 25 - 80°C, the heat preservation time is 10 - 720 min, and the atmosphere is one of vacuum, air and nitrogen atmosphere.

[0035] Among them, the composition of the electro-driven ion exchange unit in step 5) includes but is not limited to an upper organic glass plate, an electrochemical lithium extraction electrode, a diaphragm, an anion exchange membrane, an activated carbon electrode, and a lower organic glass plate, and the electrode area is 20 - 100 cm 2 ; Assemble a raw material pool, a peristaltic pump, a DC regulated power supply, an electro-driven ion exchange system, a computer, and a recovery liquid pool into an electrochemical lithium extraction device; operate the device and apply a voltage of 0.5 - 2.0 V; the lithium-containing solution in the raw material pool flows to the electro-driven ion exchange unit through the peristaltic pump, and the lithium ions in the lithium-containing solution migrate to the 3D printed electrochemical lithium extraction electrode and are embedded in the electrode; at the same time, the chloride ions migrate to the activated carbon electrode through the anion exchange membrane; the barrier membrane prevents the positive and negative electrodes from being short-circuited.

[0036] Among them, the lithium-containing solution in step 5) includes, but is not limited to, salt lake brine, produced water from oil and gas fields, mother liquor after lithium precipitation, geothermal water or seawater. In a more specific embodiment provided by the present invention, the composition of the lithium-containing solution is: Li + with a concentration of 0.005 - 10 g / L, Mg 2+ being 0.01 - 100 g / L, K + with a concentration of 0.01 - 100 g / L, Na + with a concentration of 0.01 - 100 g / L, Ca 2+ with a concentration of 0 - 200 g / L, Cl - with a concentration of 0.1 - 100 g / L, and the total organic carbon (TOC) content is 0 - 20 g / L.

[0037] The advantages of the present invention are as follows: The prepared porous electrode has a high loading amount and excellent structural stability, and exhibits excellent lithium separation performance in lithium-containing aqueous solutions, overcoming the problems of small loading amount, low treatment efficiency, and easy cracking of traditional thin film electrodes during the electrochemical lithium extraction process.

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0039] In the ranges disclosed in this specification, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0040] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "specific embodiments", or "some specific embodiments" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0041] In the embodiments provided in this specification, for those without specified specific technologies or conditions, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product specifications. For reagents or instruments without specified manufacturers, they are all conventional products that can be obtained through regular channels.

[0042] Example 1

[0043] (1) This example provides a method and product for preparing an electrode based on 3D printing technology. The specific preparation method is as follows:

[0044] Use computer software to design the model of the electrochemical lithium extraction electrode, including the graph, width, thickness, length, filling method, filling density, etc. of the electrode, and set the software parameters as mechanical instructions to control the 3D printing device, so as to control the movement path data of the print head and the laser print head and control the printing time.

[0045] Configure the 3D printing slurry: Add 14 g of lithium iron phosphate manganese, 4 g of polyvinylidene fluoride, 2 g of conductive carbon black, and 1 g of multi-walled carbon nanotubes to a mortar and grind and mix evenly. Then add 8 mL of N-methylpyrrolidone and grind and stir evenly to form a printable slurry with fluidity.

[0046] Use a dispensing syringe as the raw material library. Assemble the dispensing needle onto the dispensing syringe (with a diameter of 0.26 mm), and connect the other end of the syringe to the control system. Start the air compressor to provide high-pressure air flow as the power for slurry printing. Connect the air outlet of the air compressor to the dispensing syringe, control the outlet pressure at 0.6 MPa, and realize the printing of the slurry according to the set model and printing path to obtain a printed pre-treated electrode.

[0047] Place the printed pre-treated electrode in a blast drying oven, heat it to 60 °C, keep it warm for 600 min, take it out after cooling, and obtain a lithium iron phosphate manganese 3D printed electrochemical lithium extraction electrode.

[0048] (2) This example tests the lithium extraction performance of the electrode prepared above. The steps are as follows:

[0049] Configure 30 mmol / L LiCl, NaCl, KCl, MgCl2, CaCl2 solutions as simulated brine (the concentration of each component is 30 mmol / L), and 10 mmol / L LiCl as the recovery liquid. Install the electro-driven ion exchange unit in sequence: plexiglass upper plate, lithium iron phosphate manganese 3D printed electrochemical lithium extraction electrode, diaphragm, anion exchange membrane, activated carbon electrode, plexiglass lower plate. The electrode area is 25 cm 2; Assemble a raw material pool, a peristaltic pump, a DC regulated power supply, an electro-driven ion exchange system, a computer, and a recovered liquid pool into an electrochemical lithium extraction device; operate the device and apply a voltage of 1.0 V; the 30 mmol / L simulated brine in the raw material pool flows through the peristaltic pump to the electro-driven ion exchange unit, and lithium ions in the lithium-containing solution migrate to the 3D printed electrochemical lithium extraction electrode and are embedded in the electrode; at the same time, chloride ions migrate to the activated carbon electrode through the anion exchange membrane. Optical photos of the electrodes in triangular, linear, grid, and honeycomb shapes are shown in the appendix Figure 1 as shown. The lithium extraction capacities of the 3D printed triangular, linear, grid, honeycomb, and traditional thin film-shaped electrochemical lithium extraction electrodes are 27, 32, 19, 26, and 13 mg / g respectively, and the results are shown in the appendix Figure 2 as shown. After 5 cycles, the cumulative extraction capacities of the 3D printed triangular, linear, grid, honeycomb, and traditional thin film-shaped electrodes are 134, 143, 94, 138, and 83 mg / g respectively, as shown in the appendix Figure 3 as shown. Experimental data show that the method of preparing an electrochemical lithium extraction electrode by 3D printing can effectively improve the lithium separation capacity and extraction efficiency and overcome the mass transfer problem of traditional thick film electrodes.

[0050] Example 2

[0051] (1) This example provides a method and product for preparing an electrode based on 3D printing technology. The specific preparation method is as follows:

[0052] Use computer software to design the model of the electrochemical lithium extraction electrode, including the shape, width, thickness, length, filling method, filling density, etc. of the electrode, and set the software parameters as mechanical instructions to control the 3D printing device, so as to control the movement path data of the print head and the laser print head and control the printing time.

[0053] Prepare 3D printing slurry: Add 14 g of lithium manganate, 2 g of polyvinylidene fluoride, 2 g of graphene, and 1 g of multi-walled carbon nanotubes to a mortar and grind them evenly. Then add 10 mL of N-methylpyrrolidone and grind and stir evenly to form a flowing printing slurry.

[0054] Use a dispensing syringe as the raw material reservoir, assemble the dispensing needle onto the dispensing syringe (with a diameter of 0.26 mm), and connect the other end of the syringe to the control system. Start the air compressor to provide high-pressure air flow as the power for slurry printing. Connect the air outlet of the air compressor to the dispensing syringe, control the outlet pressure at 0.5 MPa, and achieve slurry printing according to the set model and printing path to obtain a printed pre-treated electrode.

[0055] Place the printed pre-treated electrode in a vacuum drying oven, heat it to 60°C, keep it warm for 600 min, take it out after cooling, and obtain a 3D printed electrochemical lithium extraction electrode of lithium manganate.

[0056] (2) In this embodiment, the above-prepared electrode is used for lithium extraction, and the steps are as follows:

[0057] Build an electrochemical lithium extraction platform to extract lithium from the brine of Xitieshan Salt Lake. Use 10 mmol / L LiCl as the recovery solution, and install the electro-driven ion exchange unit in sequence: plexiglass upper plate, lithium iron phosphate manganese 3D printed electrochemical lithium extraction electrode, separator, anion exchange membrane, activated carbon electrode, plexiglass lower plate. The electrode area is 25 cm 2 ; Assemble the raw material pool, peristaltic pump, DC regulated power supply, electro-driven ion exchange system, computer, and recovery solution pool into an electrochemical lithium extraction device; Run the device and apply a voltage of 1.0 V; The brine of Xitieshan Salt Lake in the raw material pool flows to the electro-driven ion exchange unit through the peristaltic pump. Lithium ions in the lithium-containing solution migrate to the 3D printed electrochemical lithium extraction electrode and are embedded in the electrode; At the same time, anions migrate to the activated carbon electrode through the anion exchange membrane. Electrochemical lithium extraction electrodes with 3D printed 7, 9, 11, 13, 15, 17, 19, 21-layer grid structures are used, and the hourly lithium ion concentration change amounts of the brine of Xitieshan Salt Lake are 4, 5, 7, 10, 12, 14, 17, 18 mmol / L respectively. Experimental data show that the multi-layer thick electrode prepared by 3D printing can effectively improve the lithium separation efficiency in salt lake brine, and the increase in thickness does not affect the mechanical strength and stability of the electrode.

[0058] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrochemical lithium extraction method, characterized in that, An electrochemical lithium extraction electrode is assembled in an electro-driven ion exchange device for separating lithium ions from a lithium-containing solution. The preparation method of the electrochemical lithium extraction electrode includes: using a 3D printing device to eject a printing paste to form the electrochemical lithium extraction electrode; the printing paste includes a lithium extraction active material, a binder, a conductive agent, and a solvent; in the printing paste, the content of the lithium extraction active material is 50wt% - 95wt%, the content of the binder is 2wt% - 20wt%, and the content of the conductive agent is 3wt% - 30wt%; the ratio of the binder to the solvent is 5:95 - 95:5; the 3D printing device adopts a direct writing type 3D printing technology; the electrochemical lithium extraction electrode has a porous structure in a triangular shape, a honeycomb shape, or a linear shape.

2. The electrochemical lithium extraction method according to claim 1, characterized in that The lithium extraction active material includes lithium manganate, lithium iron phosphate, lithium manganese iron phosphate, aluminum hydroxide hydrotalcite, lithium titanate, and their doped compounds.

3. The electrochemical lithium extraction method according to claim 2, wherein, The lithium extraction active material is selected from at least one of lithium manganate, lithium iron phosphate, and lithium manganese iron phosphate.

4. The electrochemical lithium extraction method according to claim 1 or 2, wherein The conductive agent is selected from at least one of conductive carbon, carbon nanotubes, and graphene.

5. The electrochemical lithium extraction method according to claim 1 or 2, wherein The binder includes polyvinylidene fluoride, carboxymethyl cellulose, polyacrylic acid, sodium alginate, and polyvinyl alcohol.

6. The electrochemical lithium extraction method according to claim 5, wherein, The binder is polyvinylidene fluoride.

7. The electrochemical lithium extraction method according to claim 1 or 2, characterized in that, The solvent includes water, N-methylpyrrolidone, dimethyl sulfoxide, dichloromethane, ethanol, and isopropanol.

8. The electrochemical lithium extraction method according to claim 7, wherein The solvent is N-methylpyrrolidone.

9. The electrochemical lithium extraction method according to claim 1 or 2, characterized in that, After using the 3D printing device to eject the printing paste, it includes drying; the drying temperature is 25 - 80°C, and the drying heat preservation time is 10 - 720 min.

10. The electrochemical lithium extraction method according to claim 1 or 2, characterized in that, The nozzle diameter of the 3D printing device is 0.1 - 2.0 mm.

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