Self-supporting aerogel electrode, preparation method thereof and packed tower type electrochemical lithium extraction device

Abstract

The invention relates to the technical field of electrochemical lithium extraction, in particular to a self-supporting aerogel electrode, a preparation method of the self-supporting aerogel electrode and a packed tower type electrochemical lithium extraction device.Iron phosphate with the lithium intercalation capacity, a carbon nanomaterial and an adhesive are compounded and dispersed in water, then freeze drying forming is conducted, and the self-supporting aerogel type lithium intercalation electrode is obtained. Redox reaction can be carried out under the action of current, and meanwhile, the lithium-containing raw material solution can be reversibly embedded and emigrated in the electrode material; similarly, preparing the carbon nanomaterial into a self-supporting aerogel type anion adsorption electrode with anion capturing capability by a freeze-drying method; according to the tower type electrochemical lithium extraction device composed of the self-supporting aerogel type lithium intercalation electrode and the self-supporting aerogel type anion adsorption electrode, the solid-liquid contact area of raw material liquid and the self-supporting aerogel electrode is large, and the mass transfer efficiency is high, so that the adsorption efficiency is improved, and the capturing capacity of the device on lithium ions is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical lithium extraction, and particularly relates to a self-supporting aerogel electrode, a preparation method thereof and a packing tower type electrochemical lithium extraction device. BACKGROUND

[0002] At present, the extraction methods for liquid lithium ore include precipitation method, solvent extraction method, ion exchange adsorption method and nanofiltration method, but the above methods have the defects of serious environmental pollution, high energy consumption and long process time. In recent years, electrochemical lithium extraction method as a new type of lithium extraction method has attracted widespread attention. The core of this technology is an electrode material with lithium ion selectivity and lithium ion storage capacity. Its principle is similar to that of aqueous lithium ion battery. First, lithium ion selective binding sites are formed in the electrode material through chemical treatment or electrochemical treatment. Then, a potential is applied to the electrode material, and under the driving of current, the electrode material undergoes oxidation-reduction reaction, and lithium ions in the salt water are reversibly inserted into the electrode material and then migrated out, so as to realize the selective enrichment of lithium ions.

[0003] The existing electrochemical lithium extraction system based on lithium manganate (LMO) and ternary material (LNCM) electrode materials has high adsorption efficiency due to the three-dimensional lithium ion transmission network of the materials themselves, but has poor cycle stability and is prone to transition metal dissolution. The electrochemical lithium extraction system based on iron phosphate (FP) has excellent cycle stability, but the hydrophilicity of the iron phosphate material is poor, and the electrolyte is difficult to infiltrate into the electrode interior, which is not conducive to the transmission of lithium ions. In addition, the crystal structure of iron phosphate contains only one-dimensional lithium ion diffusion channels, and the diffusion coefficient of ions is low, so the adsorption rate of the electrochemical lithium extraction system based on iron phosphate is low.

[0004] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] In view of the above shortcomings of the prior art, the purpose of the present application is to provide a self-supporting aerogel electrode, a preparation method thereof and a packing tower type electrochemical lithium extraction device, which aims to solve the problems of poor cycle stability or low adsorption efficiency of the electrode material of the existing electrochemical lithium extraction system.

[0006] The technical scheme of the present application is as follows:

[0007] A preparation method of a self-supporting aerogel electrode, comprising the steps of:

[0008] mixing carbon nanomaterials and water to obtain a first mixed solution;

[0009] mixing iron phosphate and the first mixed solution to obtain a second mixed solution;

[0010] Mixing the adhesive with the second mixed solution, and performing heating stirring treatment to obtain a third mixed solution;

[0011] Filling the third mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type lithium intercalation electrode;

[0012] Mixing the adhesive with the first mixed solution, and performing heating stirring treatment to obtain a fourth mixed solution;

[0013] Filling the fourth mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type anion adsorption electrode.

[0014] The preparation method of the self-supporting aerogel electrode, wherein the carbon nanomaterials include graphene oxide and carbon nanotubes; the mass ratio of the graphene oxide to the carbon nanotubes is (20-50):(2-5); and the mass concentration of the first mixed solution is 4.4 mg / ml-27.5 mg / ml.

[0015] The preparation method of the self-supporting aerogel electrode, wherein the mass ratio of the iron phosphate to the carbon nanomaterials is (10-20):(22-55); and the mass ratio of the adhesive to the carbon nanomaterials is (20-50):(22-55).

[0016] The preparation method of the self-supporting aerogel electrode, wherein the rotating speed of the heating stirring treatment is 800 rpm-1000 rpm, the temperature of the heating stirring treatment is 60°C-80°C, and the time of the heating stirring treatment is 1 h-2 h.

[0017] The preparation method of the self-supporting aerogel electrode, wherein the freezing is freezing in liquid nitrogen for 5 min-10 min; and the drying is freeze drying at-10°C to-50°C for 24 h-48 h.

[0018] The preparation method of the self-supporting aerogel electrode, wherein the preparation method of the iron phosphate includes the following steps:

[0019] Mixing the lithium iron phosphate after grinding and sieving with water to obtain a lithium iron phosphate solution;

[0020] Performing constant temperature stirring treatment on the lithium iron phosphate solution and sodium persulfate to obtain a fifth mixed solution;

[0021] After performing suction filtration separation treatment on the fifth mixed solution, and performing washing and drying, an iron phosphate is obtained.

[0022] The preparation method of the self-supporting aerogel electrode, wherein the mass ratio of the lithium iron phosphate to the sodium persulfate is (1-2):(1.62-3.24).

[0023] The preparation method of the self-supporting aerogel electrode, wherein the rotation speed of the constant temperature stirring treatment is 550 rpm-800 rpm, the temperature of the constant temperature stirring treatment is 40℃-45℃, and the time of the constant temperature stirring treatment is 1h-2h.

[0024] A self-supporting aerogel electrode is prepared by the preparation method of the self-supporting aerogel electrode.

[0025] A filler column type electrochemical lithium extraction device comprises:

[0026] A tubular shell is provided with the self-supporting aerogel electrode; the self-supporting aerogel electrode comprises symmetrically arranged self-supporting aerogel type lithium intercalation electrodes and self-supporting aerogel type anion adsorption electrodes; and a gap is arranged between the self-supporting aerogel type lithium intercalation electrodes and the self-supporting aerogel type anion adsorption electrodes.

[0027] A conical liquid inlet member and a conical liquid outlet member are arranged at two ends of the tubular shell, respectively; the conical liquid inlet member and the conical liquid outlet member are respectively provided with a liquid inlet and a liquid outlet.

[0028] A power supply is electrically connected to the self-supporting aerogel type lithium intercalation electrodes at the negative electrode and to the self-supporting aerogel type anion adsorption electrodes at the positive electrode.

[0029] Beneficial effects: the application provides a self-supporting aerogel electrode and a preparation method thereof, and a filler column type electrochemical lithium extraction device. The preparation method of the self-supporting aerogel electrode comprises the following steps: mixing graphene oxide, carbon nanomaterial and water to obtain a first mixed solution; mixing iron phosphate with the first mixed solution to obtain a second mixed solution; mixing an adhesive with the second mixed solution, and performing heating and stirring treatment to obtain a third mixed solution; pouring the third mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type lithium intercalation electrode; mixing the adhesive with the first mixed solution, and performing heating and stirring treatment to obtain a fourth mixed solution; pouring the fourth mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type anion adsorption electrode. The self-supporting aerogel type lithium intercalation electrode is obtained by compounding iron phosphate with lithium intercalation capacity, carbon nanomaterial and adhesive, dispersing them in water, and then performing freezing and drying to form the electrode. The electrode can undergo redox reaction under the action of current, and lithium-containing raw material liquid can reversibly intercalate and migrate in the electrode material. The self-supporting aerogel type anion adsorption electrode is obtained by compounding carbon nanomaterial and performing freezing and drying. The column type electrochemical lithium extraction device is composed of the self-supporting aerogel type lithium intercalation electrode and the self-supporting aerogel type anion adsorption electrode. The solid-liquid contact area between the raw material liquid and the self-supporting aerogel electrode is large, and the mass transfer efficiency is high, so that the adsorption efficiency is improved, and the lithium ion capture capacity of the device is improved. In the lithium extraction link, the raw material liquid is replaced by the recovery liquid, and the polarity of the power supply is reversed. The lithium ions intercalated in the self-supporting aerogel type lithium intercalation electrode can be continuously deintercalated into the recovery liquid, and the lithium ion concentration of the recovery liquid gradually increases, so that selective enrichment of lithium ions is realized. The lithium extraction device composed of the self-supporting aerogel electrode has the advantage of high cycle stability. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a process flow diagram of the preparation method of the self-supporting aerogel electrode of the application;

[0031] Figure 2 It is a structure diagram of the filler column type electrochemical lithium extraction device of the application;

[0032] Figure 3 It is a scanning electron microscope image of the self-supporting aerogel type lithium intercalation electrode prepared in Example 1;

[0033] Figure 4 It is a scanning electron microscope image of the self-supporting aerogel type anion adsorption electrode prepared in Example 1;

[0034] Figure 5 It is a top view of the self-supporting aerogel type lithium intercalation electrode prepared in Example 1;

[0035] Figure 6 A physical side view of the self-supporting aerogel type lithium intercalation electrode prepared for Example 1;

[0036] Figure 7 A comparison chart of lithium extraction performance of the lithium extraction device prepared for Example 1 and a conventional flat plate lithium extraction device;

[0037] Explanation of reference numerals: tubular shell 10, self-supporting aerogel electrode 20, self-supporting aerogel type lithium intercalation electrode 21, self-supporting aerogel type anion adsorption electrode 22, gap 30, conical liquid inlet 40, liquid inlet 41, conical liquid outlet 50, liquid outlet 51, negative electrode 60, positive electrode 70. DETAILED DESCRIPTION

[0038] The present application provides a self-supporting aerogel electrode and a preparation method thereof, and a packed column type electrochemical lithium extraction device. To make the purpose, technical solutions and effects of the present application clearer and more explicit, the present application is further described in detail below. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0039] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as such.

[0040] In a conventional electrochemical lithium extraction system, the electrode is a fixed flat plate structure. The electrolyte (containing lithium salt lake brine) has a large penetration and diffusion resistance in the dense flat plate electrode, and the solid-liquid contact area is small, resulting in a low electrochemical lithium extraction rate. The manufacturing method of the flat plate electrode is similar to that of a lithium ion battery electrode. The active material, conductive agent, binder and organic solvent are mixed and stirred to form a slurry, the electrode slurry is coated on a metal current collector, and the flat plate electrode is obtained by volatilizing the organic solvent. This electrode manufacturing method has the disadvantages of high cost, complex preparation method, high requirement for equipment, environmental pollution, etc. Compared with the flat plate electrode, the flow type electrochemical lithium extraction has the advantages of realizing online continuous regeneration of the electrode and stable operation. However, the conductivity inside the flow electrode is poor, and the flow system is highly dependent on ion exchange membranes, further increasing the internal resistance of the system and the operating cost.

[0041] Based on this, as shown in Figure 1 The present application provides a preparation method of a self-supporting aerogel electrode, comprising the steps of:

[0042] Step S10: mixing the carbon nanomaterial and water to obtain a first mixed solution;

[0043] Step S20: mixing the iron phosphate and the first mixed solution to obtain a second mixed solution;

[0044] Step S30: mixing the adhesive and the second mixed solution, and performing heating and stirring treatment to obtain a third mixed solution;

[0045] Step S40: filling the third mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type lithium intercalation electrode;

[0046] Step S50: mixing the adhesive and the first mixed solution, and performing heating and stirring treatment to obtain a fourth mixed solution;

[0047] Step S60: filling the fourth mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type anion adsorption electrode.

[0048] In the embodiment, the iron phosphate having lithium intercalation capacity is compounded with the carbon nanomaterial and the adhesive, dispersed in water, and then formed by freeze-drying to obtain a self-supporting aerogel type lithium intercalation electrode, which can undergo redox reaction under the action of current, and the lithium-containing raw material solution can reversibly intercalate and migrate out in the electrode material. Similarly, the carbon nanomaterial is made into a self-supporting aerogel type anion adsorption electrode having anion capture capacity by the freeze-drying method. The tower type electrochemical lithium extraction device composed of the self-supporting aerogel type lithium intercalation electrode and the self-supporting aerogel type anion adsorption electrode has a large solid-liquid contact area and high mass transfer efficiency between the raw material solution and the self-supporting aerogel electrode, thereby improving the adsorption efficiency and enhancing the capture capacity of the device for lithium ions. In the lithium extraction link, the raw material solution is replaced by the recovery solution and the polarity of the power supply is reversed, so that the lithium ions intercalated in the self-supporting aerogel type lithium intercalation electrode can be continuously deintercalated into the recovery solution, the lithium ion concentration of the recovery solution gradually increases, thereby realizing selective enrichment of lithium ions, and the lithium extraction device composed of the self-supporting aerogel electrode has the advantage of high cycle stability.

[0049] Specifically, the self-supporting aerogel electrode prepared by the above preparation method has lithium ion selectivity and lithium ion storage capacity. Under the action of voltage, the lithium intercalation electrode and the anion adsorption electrode undergo redox reaction under the action of current, and the lithium ions in the lithium-containing raw material solution are reversibly intercalated and deintercalated in the electrode material, thereby realizing selective enrichment of lithium ions. Moreover, the lithium-containing raw material solution can fully infiltrate the self-supporting aerogel electrode, thereby shortening the ion transport distance and improving the electrochemical lithium extraction performance of the self-supporting aerogel electrode. At the same time, the self-supporting aerogel electrode prepared by the preparation method can avoid the use of toxic binders and organic solvents in the production process of traditional flat electrodes, thereby reducing the cost of electrochemical lithium extraction technology and reducing environmental pollution.

[0050] In some embodiments, the carbon nanomaterials include graphene oxide and carbon nanotubes; the mass ratio of the graphene oxide to the carbon nanotubes is (20-50):(2-5); and the mass concentration of the first mixed solution is 4.4 mg / ml-27.5 mg / ml. The lithium intercalation electrode obtained by compounding the graphene oxide and the carbon nanotubes with the iron phosphate according to the above mass ratio has lithium ion selectivity and lithium ion storage capacity, improves the adsorption of lithium ions by the lithium intercalation electrode, and can realize delithiation by replacing the lithium-containing raw material solution with a recovery solution, thereby achieving the purpose of selectively enriching lithium ions.

[0051] In a preferred embodiment, in the step S10, the graphene oxide and the carbon nanotubes are commercially available graphene oxide and carbon nanotubes, the mass ratio of the graphene oxide to the carbon nanotubes is 10:1, the graphene oxide and the carbon nanotubes are mixed with deionized water by ultrasonic dispersion, the ultrasonic dispersion time is greater than 60 min, and the mass concentration of the obtained first mixed solution is 11 mg / ml.

[0052] In some embodiments, the mass ratio of the iron phosphate to the carbon nanomaterials is (10-20):(22-55); and the mass ratio of the adhesive to the carbon nanomaterials is (20-50):(22-55). The compounding of the iron phosphate and the carbon nanomaterials can be realized by mixing the iron phosphate with lithium intercalation capacity, the carbon nanomaterials, and a small amount of adhesive according to the above mass ratio, thereby obtaining a self-supporting aerogel type lithium intercalation electrode with lithium ion selectivity and lithium ion storage capacity. The compounding of the iron phosphate and the carbon nanomaterials to obtain the self-supporting aerogel type lithium intercalation electrode can overcome the poor hydrophilicity problem of the iron phosphate material, so that the lithium-containing raw material solution can infiltrate into the electrode, thereby improving the transport of lithium ions.

[0053] In some embodiments, the adhesive includes one or more of polyvinyl alcohol, polyacrylonitrile, and polyurethane.

[0054] In some embodiments, the rotation speed of the heating stirring treatment is 800 rpm-1000 rpm, the temperature of the heating stirring treatment is 60℃-80℃, and the time of the heating stirring treatment is 1h-2h. The reaction rate of the reaction system can be improved by the heating stirring treatment.

[0055] In a preferred embodiment, the rotation speed of the heating stirring treatment is 900 rpm, the temperature of the heating stirring treatment is 70℃, and the time of the heating stirring treatment is 2h.

[0056] In some embodiments, the freezing is freezing in liquid nitrogen for 5min-10min, and the drying is freeze-drying at-10℃ to-50℃ for 24h-48h. The electrode matching the mold can be prepared by the freeze-drying method, which is convenient for subsequent application in the lithium extraction device.

[0057] Specifically, the third mixed solution and the fourth mixed solution are respectively added to two copper cylindrical containers, the containers are frozen in liquid nitrogen for a period of time, and then the frozen solid is dried in a freeze dryer for a period of time, to obtain the aerogel electrode.

[0058] In some embodiments, the preparation method of the iron phosphate includes the following steps:

[0059] Step S1: After the lithium iron phosphate is ground and sieved, the lithium iron phosphate is mixed with water to obtain a lithium iron phosphate solution;

[0060] Step S2: The lithium iron phosphate solution is subjected to constant temperature stirring treatment with sodium persulfate to obtain a fifth mixed solution;

[0061] Step S3: After the fifth mixed solution is subjected to filtration separation treatment, it is washed and dried to obtain iron phosphate.

[0062] In this embodiment, the iron phosphate with lithium intercalation capacity can be obtained by using the above simple preparation process, and the self-supporting aerogel type lithium intercalation electrode obtained by compounding the iron phosphate with carbon nanomaterials can overcome the problem of poor hydrophilicity of the iron phosphate material, so that the lithium-containing raw material liquid can be infiltrated into the electrode, and the transmission of lithium ions is improved.

[0063] In some embodiments, in step S1, the grinding time is 15min-30min, and the mesh size of the sieve is 300 mesh-400 mesh.

[0064] In some embodiments, the mass ratio of the lithium iron phosphate to the sodium persulfate is (1-2):(1.62-3.24).

[0065] In some embodiments, in the step S1, the mass of the lithium iron phosphate is 1g-2g, the volume of the water is 60ml-120ml, the mixing is performed by ultrasonic dispersion, and the time of the ultrasonic dispersion is 30min-60min.

[0066] In some embodiments, in the step S2, the mass of the sodium persulfate is 1.62g-3.24g.

[0067] In some embodiments, in the step S3, the rotation speed of the constant-temperature stirring treatment is 550rpm-800rpm, the temperature of the constant-temperature stirring treatment is 40℃-45℃, and the time of the constant-temperature stirring treatment is 1h-2h.

[0068] In some embodiments, in the step S3, the washing and drying include the following steps: washing the solid obtained by the suction filtration with deionized water for more than 3 times; and then drying at a vacuum drying temperature of 70℃ for 12 hours to obtain the iron phosphate.

[0069] In addition, the application further provides a self-supporting aerogel electrode prepared by the preparation method.

[0070] In the embodiment, the self-supporting aerogel type lithium intercalation electrode is obtained by compounding the lithium intercalation capable iron phosphate, the carbon nanomaterial and the adhesive, dispersing in water, and then freeze-drying to form, and the electrode material can reversibly realize intercalation and deintercalation of the lithium-containing raw material liquid under the action of the current; the self-supporting aerogel type anion adsorption electrode with anion capturing capability is prepared by the freeze-drying method; the tower type electrochemical lithium extraction device composed of the self-supporting aerogel type lithium intercalation electrode and the self-supporting aerogel type anion adsorption electrode has a large solid-liquid contact area and high mass transfer efficiency between the raw material liquid and the self-supporting aerogel electrode, thereby improving the adsorption efficiency and the lithium ion capturing capacity of the device.

[0071] In addition, as shown in Figure 2 The application further provides a filler tower type electrochemical lithium extraction device, which comprises:

[0072] A tubular shell 10 is provided with a self-supporting aerogel electrode 20; the self-supporting aerogel electrode 20 comprises symmetrically arranged self-supporting aerogel type lithium intercalation electrodes 21 and self-supporting aerogel type anion adsorption electrodes 22; and a gap 30 is arranged between the self-supporting aerogel type lithium intercalation electrodes 21 and the self-supporting aerogel type anion adsorption electrodes 22.

[0073] A conical liquid inlet 40 and a conical liquid outlet 50 are arranged at two ends of the tubular shell 10 respectively, and the conical liquid inlet 40 and the conical liquid outlet 50 are respectively provided with a liquid inlet 41 and a liquid outlet 51.

[0074] A power supply, a negative electrode 60 of the power supply is electrically connected with the self-supporting aerogel lithium intercalation electrode 21, and a positive electrode 70 of the power supply is electrically connected with the self-supporting aerogel anion adsorption electrode 22.

[0075] In the embodiment, the self-supporting aerogel lithium intercalation electrode 21 and the self-supporting aerogel anion adsorption electrode 22 are respectively filled in a tubular electrochemical reactor (i.e. a tubular shell), and a gap is arranged between the self-supporting aerogel lithium intercalation electrode 21 and the self-supporting aerogel anion adsorption electrode 22 without an ion exchange membrane or a diaphragm, and then the self-supporting aerogel lithium intercalation electrode 21 and the self-supporting aerogel anion adsorption electrode 22 are respectively connected with a negative electrode and a positive electrode of an external power supply to assemble a packed column type electrochemical lithium extraction device; wherein the self-supporting aerogel anion adsorption electrode 22 is used for adsorbing anions in a water body and maintaining electrical neutrality of a solution, and the self-supporting aerogel lithium intercalation electrode 21 is used for adsorbing lithium ions in a raw material liquid and intercalating the lithium ions into the self-supporting aerogel lithium intercalation electrode 21. In the device, the raw material liquid (lithium salt lake brine) passes through the aerogel electrode, has the advantages of large solid-liquid contact area and high mass transfer efficiency, and the lithium ion capture performance of the packed column type electrochemical lithium extraction device is significantly improved compared with conventional flat plate electrodes and flow electrodes.

[0076] Specifically, the self-supporting aerogel type lithium intercalation electrode 21 and the self-supporting aerogel type anion adsorption electrode 22 are respectively filled in the tubular shell, and are spaced apart; the liquid inlet of the conical liquid inlet member is inserted into the water body to be extracted for lithium, and the liquid outlet of the conical liquid outlet member is connected with a circulating pump, so that the water body to be extracted for lithium flows in the device, while the self-supporting aerogel type lithium intercalation electrode 21 and the self-supporting aerogel type anion adsorption electrode 22 are respectively connected with the negative electrode and the positive electrode of an external power supply, so that the device continuously selectively extracts lithium from the water body to be extracted for lithium. In the lithium extraction section, the water body to be extracted for lithium is replaced with a recovery liquid (such as a dilute lithium chloride solution), and at the same time, the polarity of the power supply is reversed, then the device can continuously deintercalate lithium ions intercalated in the self-supporting aerogel type lithium intercalation electrode into the recovery liquid, and the lithium ion concentration of the recovery liquid gradually increases, thereby realizing selective enrichment of lithium ions. Moreover, the flow type lithium extraction device formed by the tubular shell, the conical liquid inlet member, the conical liquid outlet member and the self-supporting aerogel electrode promotes the diffusion of lithium ions and improves the serious concentration polarization phenomenon of the traditional thick electrode, thereby realizing high adsorption capacity and high adsorption rate, which are respectively increased by more than 2 times and more than 2.5 times compared with the traditional flat plate type lithium extraction technology. In addition, the concentration of the lithium chloride concentrated solution produced by the filler tower type electrochemical lithium extraction device reaches more than 99%, which can meet the production demand of subsequent lithium carbonate products.

[0077] In some embodiments, the gap 30 between the self-supporting aerogel type lithium intercalation electrode 21 and the self-supporting aerogel type anion adsorption electrode 22 is 1 mm-3 mm; preferably, the gap is 1 mm.

[0078] In some embodiments, the device can not only be applied to the recovery of lithium resources in seawater, but also can be extended to the recovery of all liquid mineral lithium resources, including but not limited to salt lake water, salt lake old brine, oil and gas field exploitation wastewater, waste lithium ion battery leaching solution, etc.

[0079] In some embodiments, by changing the internal filling electrode material, selective extraction of other kinds of anions and cations, such as strontium ions, cesium ions, cobalt ions, ammonium ions, nickel ions, uranyl ions, phosphate ions, etc. can be realized.

[0080] In some embodiments, the flow rate of the feed liquid treated by the filler tower type electrochemical lithium extraction device ranges between 5 mL / min and 1 L / min, and in this flow rate range, the capture rate and capture capacity of the electrode to lithium ions reach the optimal values.

[0081] In some embodiments, a porous diaphragm is arranged between the tubular shell 10 and the conical liquid inlet member 40 and between the tubular shell 10 and the conical liquid outlet member 50; the porous diaphragm is used to filter the water body to be extracted for lithium.

[0082] The following further illustrates the embodiments in detail. It should also be understood that the following embodiments are only used to further illustrate the present application and cannot be understood as limiting the scope of the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application are within the protection scope of the present application.

[0083] Example 1

[0084] The present embodiment provides a filler tower type electrochemical lithium extraction device, wherein the preparation steps of the self-supporting aerogel type lithium intercalation electrode and the self-supporting aerogel type anion adsorption electrode in the filler tower type electrochemical lithium extraction device include the following steps:

[0085] 1) Grind 8g of lithium iron phosphate with a mortar for 20 minutes and sieve with a 300 mesh sieve to obtain lithium iron phosphate powder;

[0086] 2) Weigh 2g of lithium iron phosphate powder and mix with 80ml of deionized water. After 40min of ultrasonic dispersion, a lithium iron phosphate solution is obtained;

[0087] 3) Add 2g of sodium persulfate to the lithium iron phosphate solution at a rotation speed of 700rpm and stir in a 40℃ constant temperature water bath for 2h to obtain a mixed solution;

[0088] 4) Use a conventional vacuum filtration device to separate the mixed solution obtained in step 3) to obtain a solid product. After washing with deionized water for 3-4 times, vacuum drying at 70℃ for 12h, lithium phosphate solid is obtained;

[0089] 5) Weigh 200mg of graphene oxide and 20mg of carbon nanotubes into 30ml of deionized water, ultrasonic dispersion for 60min to obtain a first mixed solution;

[0090] 6) Weigh 100mg of lithium phosphate obtained in step 4) into the first mixed solution, ultrasonic dispersion for 50min to obtain a second mixed solution;

[0091] 7) Weigh 0.2g of polyvinyl alcohol into the second mixed solution, stir at 900rpm, water bath temperature of 70℃, and reaction time of 2h to obtain a third mixed solution;

[0092] 8) Put the third mixed solution into a copper cylindrical container with a volume of 50ml, freeze the container in liquid nitrogen for 10min, then dry the frozen solid in a freeze dryer for 36h to obtain a self-supporting aerogel type lithium intercalation electrode;

[0093] 9) Weigh 0.2g of polyvinyl alcohol into the first mixed solution, stir at 900rpm, water bath temperature of 70℃, and reaction time of 2h to obtain a fourth mixed solution;

[0094] 10) The fourth mixed solution is added to a copper cylindrical container with a volume of 50 ml, the container is frozen in liquid nitrogen for 10 minutes, and then the frozen solid is dried in a freeze dryer for 36 hours to obtain a self-supporting aerogel type anion adsorption electrode.

[0095] The prepared self-supporting aerogel type lithium intercalation electrode and self-supporting aerogel type anion adsorption electrode are characterized, and the scanning electron microscope images thereof are shown in Figure 3 and Figure 4 It can be seen that the aerogel is formed by a porous network of iron phosphate particles with a diameter of about 100 nm mixed with graphene, and this structure gives it self-supporting ability; in addition, the actual image of the self-supporting aerogel type lithium intercalation electrode is shown in Figure 5 (top view) and Figure 6 (side view).

[0096] The self-supporting aerogel type lithium intercalation electrode and self-supporting aerogel type anion adsorption electrode prepared above are used to assemble a packed column type electrochemical lithium extraction device, the self-supporting aerogel type lithium intercalation electrode and self-supporting aerogel type anion adsorption electrode are filled into a tubular shell and spaced 1 mm apart; a conical liquid inlet and a conical liquid outlet are fixed at both ends of the tubular shell, then the negative electrode of the power supply is electrically connected to the self-supporting aerogel type lithium intercalation electrode, and the positive electrode of the power supply is electrically connected to the self-supporting aerogel type anion adsorption electrode, and the structure is shown in Figure 2 .

[0097] The inlet of the device is inserted into lithium-containing salt lake brine, and the outlet is connected to a circulating pump to make the lithium-containing salt lake brine flow in the device, and the device can continuously and selectively extract lithium from the lithium-containing salt lake brine; then the lithium-containing salt lake brine is replaced with a dilute lithium chloride solution, and the polarity of the power supply is reversed, then the device can continuously deintercalate lithium ions embedded in the self-supporting aerogel type lithium intercalation electrode into the dilute lithium chloride solution, and the lithium ion concentration of the dilute lithium chloride solution gradually increases, thereby realizing selective enrichment of lithium ions.

[0098] The lithium extraction performance of the lithium extraction device of the present embodiment is compared with that of a traditional flat plate lithium extraction device as a control group, and the comparison chart is shown in Figure 7 It can be seen that the flow design of the present embodiment promotes lithium ion diffusion and improves the serious concentration polarization phenomenon of traditional thick electrodes, thereby realizing high adsorption capacity (5 mmol / g) and high adsorption rate (6 mmol / g / h), which are 2 times and 2.5 times higher than those of traditional flat plate lithium extraction technology, respectively. In addition, the purity of the lithium chloride concentrate produced based on this device reaches more than 99%, which can meet the production needs of subsequent lithium carbonate products.

[0099] In summary, the self-supporting aerogel electrode and the preparation method thereof and the filler tower type electrochemical lithium extraction device provided by the application, the preparation method of the self-supporting aerogel electrode comprises the following steps: mixing graphene oxide, carbon nanomaterial and water to obtain a first mixed solution; mixing iron phosphate with the first mixed solution to obtain a second mixed solution; mixing an adhesive with the second mixed solution, and performing heating and stirring treatment to obtain a third mixed solution; pouring the third mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type lithium intercalation electrode; mixing an adhesive with the first mixed solution, and performing heating and stirring treatment to obtain a fourth mixed solution; pouring the fourth mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type anion adsorption electrode. The self-supporting aerogel type lithium intercalation electrode is obtained by compounding iron phosphate with lithium intercalation capacity, carbon nanomaterial and an adhesive, dispersing them in water, and then performing freezing and drying to form a shape. The self-supporting aerogel type lithium intercalation electrode can undergo an oxidation-reduction reaction under the action of an electric current, and lithium-containing raw material liquid can be reversibly intercalated and deintercalated in the electrode material. The self-supporting aerogel type anion adsorption electrode with anion capture capacity is obtained by the freezing and drying method. The tower type electrochemical lithium extraction device composed of the self-supporting aerogel type lithium intercalation electrode and the self-supporting aerogel type anion adsorption electrode has a large solid-liquid contact area and high mass transfer efficiency between the raw material liquid and the self-supporting aerogel electrode, thereby improving the adsorption efficiency and enhancing the lithium ion capture capacity of the device. In the lithium extraction link, the raw material liquid is replaced by a recovery liquid, and the polarity of the power supply is reversed. The device can continuously deintercalate lithium ions in the self-supporting aerogel type lithium intercalation electrode into the recovery liquid, and the lithium ion concentration of the recovery liquid gradually increases, thereby realizing selective enrichment of lithium ions. The lithium extraction device composed of the self-supporting aerogel electrode has the advantage of high cycle stability.

[0100] It should be understood that the application of the application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the claims of the application.

Claims

1. A method of making a self-supporting aerogel electrode, characterized by, The method comprises the steps of: mixing carbon nanomaterials and water to obtain a first mixed solution; mixing iron phosphate and the first mixed solution to obtain a second mixed solution; mixing an adhesive and the second mixed solution, and performing heating and stirring treatment to obtain a third mixed solution; filling the third mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type lithium intercalation electrode; mixing an adhesive and the first mixed solution, and performing heating and stirring treatment to obtain a fourth mixed solution; filling the fourth mixed solution into a mold, and performing freezing and drying to obtain a self-supporting aerogel type anion adsorption electrode.

2. The method of claim 1, wherein the self-supporting aerogel electrode is prepared by the steps of: The carbon nanomaterials comprise graphene oxide and carbon nanotubes, and the mass ratio of the graphene oxide to the carbon nanotubes is (20-50):(2-5); the mass concentration of the first mixed solution is 4.4 mg / ml-27.5 mg / ml.

3. The method of claim 1, wherein the self-supporting aerogel electrode is prepared by the steps of: The mass ratio of the iron phosphate to the carbon nanomaterials is (10-20):(22-55), and the mass ratio of the adhesive to the carbon nanomaterials is (20-50):(22-55).

4. The method of claim 1, wherein the self-supporting aerogel electrode is prepared by the steps of: The rotating speed of the heating and stirring treatment is 800 rpm-1000 rpm, the temperature of the heating and stirring treatment is 60℃-80℃, and the time of the heating and stirring treatment is 1h-2h.

5. The method of claim 1, wherein the self-supporting aerogel electrode is prepared by the steps of: The freezing is performed in liquid nitrogen for 5 min-10 min, and the drying is performed by freeze drying at-10℃ to-50℃ for 24h-48h.

6. The method of claim 1, wherein the self-supporting aerogel electrode is prepared by the steps of: The method for preparing the iron phosphate comprises the steps of: mixing lithium iron phosphate which is ground and sieved with water to obtain a lithium iron phosphate solution; performing constant temperature stirring treatment on the lithium iron phosphate solution and sodium persulfate to obtain a fifth mixed solution; performing suction filtration separation treatment on the fifth mixed solution, and performing washing and drying to obtain the iron phosphate.

7. The method of claim 6, wherein the self-supporting aerogel electrode is prepared by the steps of: The mass ratio of the lithium iron phosphate to the sodium persulfate is (1-2):(1.62-3.24).

8. The method of claim 6, wherein the self-supporting aerogel electrode is prepared by the steps of: The rotating speed of the constant temperature stirring treatment is 550 rpm-800 rpm, the temperature of the constant temperature stirring treatment is 40℃-45℃, and the time of the constant temperature stirring treatment is 1h-2h.

9. A self-supporting aerogel electrode, characterized in that, The self-supporting aerogel electrode is prepared by using the method.

10. An electrochemical lithium extraction device of the packed column type, characterized in that, The method comprises: a tubular shell, wherein the tubular shell is provided with the self-supporting aerogel electrode according to claim 9; the self-supporting aerogel electrode comprises symmetrically arranged self-supporting aerogel type lithium intercalation electrodes and self-supporting aerogel type anion adsorption electrodes, and a gap is arranged between the self-supporting aerogel type lithium intercalation electrodes and the self-supporting aerogel type anion adsorption electrodes; a conical liquid inlet and a conical liquid outlet, wherein the conical liquid inlet and the conical liquid outlet are arranged at two ends of the tubular shell respectively, and the conical liquid inlet and the conical liquid outlet are respectively provided with a liquid inlet and a liquid outlet; a power supply, wherein a negative electrode of the power supply is electrically connected with the self-supporting aerogel type lithium intercalation electrodes, and a positive electrode of the power supply is electrically connected with the self-supporting aerogel type anion adsorption electrodes.

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