Flowing electrode particle and preparation method and application thereof

Abstract

The invention provides a flowing electrode particle as well as a preparation method and application thereof. The flowing electrode particle is a composite microsphere comprising a lithium-embedded active substance and a conductive material, the conductivity of the flowing electrode particles is not lower than 4.8 * 10 <-4 > S / m; the contact angle between the flowing electrode particles and water is 60-80 degrees; and the specific surface area of the flowing electrode particles is 30-60m < 2 > / g. The flowing electrode particle provided by the invention has good conductivity and hydrophilicity and good adsorbability to lithium, and flowing electrode slurry prepared from the flowing electrode particle is applied to a flowing electrode lithium extraction device, so that the adsorption capacity and the adsorption rate to lithium can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical lithium extraction, and in particular relates to mobile electrode particles and a preparation method and application thereof. Background Art

[0002] Lithium and its compounds are widely used in glass, ceramics, electronics, new energy vehicles, military defense, and aerospace. In recent years, the rapid development of electronic products and new energy vehicles has led to a growing demand for lithium-ion batteries. Global lithium resource supply and demand analysis suggests that future lithium supply will struggle to meet demand, making lithium resource development a hot topic. The abundance of lithium resources in seawater, salt lake brines, and underground brines, along with their low extraction costs, have become a key development trend in lithium extraction technology.

[0003] Among the many methods of lithium extraction from solutions, the electrochemical method has the advantages of excellent selectivity, environmental friendliness, and low energy consumption, and has become the focus of current research. At present, the electrochemical lithium extraction technology generally uses the fixed electrode lithium extraction technology, which has the following disadvantages: 1. The preparation process of the fixed electrode plate requires the use of N-methylpyrrolidone, which is not environmentally friendly; 2. The proportion of the active material of the electrode plate exposed to the brine contact surface is low, and the utilization rate of the lithium insertion active site is low; 3. The fixed electrode plate has a significant polarization effect in the brine; 4. The regeneration of the fixed electrode plate requires disassembly of the device and re-coating, which is labor-intensive and cumbersome. The mobile electrode lithium extraction technology can solve the above problems, but the mobile electrode particles used in the mobile electrode lithium extraction technology still have problems such as poor conductivity, poor hydrophilicity, and poor adsorption of lithium. Summary of the Invention

[0004] The main purpose of the present invention is to provide a mobile electrode particle, which has good conductivity and hydrophilicity and good adsorption of lithium. The mobile electrode slurry prepared from the mobile electrode particle is applied to a mobile electrode lithium extraction device to improve the adsorption capacity and adsorption rate of lithium.

[0005] The present invention also provides a method for preparing mobile electrode particles. The method can prepare the mobile electrode particles, and has simple process, low cost, and uniform and controllable particle size.

[0006] The present invention also provides a flowing electrode slurry. Since the flowing electrode slurry includes the above-mentioned flowing electrode particles, the flowing electrode slurry can be used in a flowing electrode lithium extraction device to improve the adsorption capacity and adsorption rate of lithium.

[0007] The present invention also provides a mobile electrode lithium extraction device. Since the device includes the mobile electrode slurry, the mobile electrode lithium extraction device can improve the adsorption capacity and adsorption rate of lithium.

[0008] In a first aspect, the present invention provides a mobile electrode particle, wherein the mobile electrode particle is a composite microsphere comprising a lithium-intercalated active material and a conductive material;

[0009] The conductivity of the mobile electrode particles is not less than 4.8×10 -4 S / m;

[0010] The contact angle between the mobile electrode particles and water is 60-80°;

[0011] The specific surface area of ​​the mobile electrode particles is 30-60m 2 / g.

[0012] The mobile electrode particles as described above have an electrical conductivity of not less than 5.0×10 -4 S / m.

[0013] The mobile electrode particles as described above have an average particle size of 3-8 μm.

[0014] In the mobile electrode particles as described above, the lithium-intercalation active material includes at least one of lithium manganese oxide, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and lithium nickel cobalt manganese oxide.

[0015] In a second aspect, the present invention provides a method for preparing the mobile electrode particles, comprising the following steps:

[0016] 1) ball milling a raw material system comprising the element sources of the lithium intercalation active material and a solvent at a rotation speed of 1400-2300 r / min to obtain a primary slurry, wherein the ratio of the time of the primary ball milling to the mass of the raw material system is 0.5-1 h:50-150 g;

[0017] 2) ultrasonically treating the mixed system including the primary slurry and the conductive material to obtain a dispersed system, wherein the ratio of the ultrasonic treatment time to the mass of the mixed system is 0.5-1h:100-200g;

[0018] 3) performing a secondary ball milling treatment on the dispersed system at a rotation speed of 1400-2300 r / min to obtain a secondary slurry, wherein the ratio of the secondary ball milling time to the mass of the dispersed system is 0.5-2 h:100-200 g;

[0019] 4) spray drying the secondary slurry to obtain a mobile electrode particle precursor, heating the mobile electrode particle precursor to 600-850°C at a heating rate of 5-25°C / min under an inert atmosphere, and sintering the mobile electrode particles to obtain the mobile electrode particles. The sintering time is 8-20 hours.

[0020] In the preparation method described above, the mass molar ratio of the conductive material to the lithium element is 40-60 g:1 mol.

[0021] In the preparation method described above, the pressure of the spray drying process is 5.0-8.0 bar, and the nozzle aperture is 0.7-2.0 mm.

[0022] In a third aspect, the present invention provides a mobile electrode slurry comprising the mobile electrode particles as described above or the mobile electrode particles prepared by the preparation method as described above.

[0023] In a fourth aspect, the present invention provides a flowing electrode lithium extraction device, comprising the flowing electrode slurry as described above.

[0024] In a fifth aspect, the present invention provides a use of at least one of the mobile electrode particles, mobile electrode slurry and mobile electrode lithium extraction device as described above in electrochemical lithium extraction from brine.

[0025] The present invention provides a mobile electrode particle, and limits the electrical conductivity, specific surface area, and contact angle with water of the mobile electrode particle, so that the mobile electrode particle has good electrical conductivity and hydrophilicity, and good adsorption of lithium. The mobile electrode slurry prepared from the mobile electrode slurry is used in a mobile electrode lithium extraction device to improve the adsorption capacity and adsorption rate of lithium. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0027] In a first aspect, the present invention provides a flow electrode particle, wherein the flow electrode particle is a composite microsphere comprising a lithium-intercalated active material and a carbon material;

[0028] The conductivity of the mobile electrode particles is not less than 4.8×10 -4 S / m;

[0029] The contact angle between the mobile electrode particles and water is 60-80°;

[0030] The specific surface area of ​​the mobile electrode particles is 30-60m 2 / g.

[0031] It can be understood that the conductivity of the mobile electrode particles can be used to characterize the conductivity of the mobile electrode particles, the contact angle between the mobile electrode particles and water can be used to characterize the hydrophilicity of the mobile electrode particles, and the specific surface area of ​​the mobile electrode particles can be used to characterize the adsorption capacity of the mobile electrode particles for lithium.

[0032] The mobile electrode slurry prepared from the mobile electrode particles is applied to the mobile electrode lithium extraction device to improve the adsorption capacity and adsorption rate of lithium. It is speculated that this may be because the conductivity of the mobile electrode particles is not less than 4.8×10 -4 S / m, has good electrical conductivity, can accelerate the back and forth intercalation and deintercalation of lithium ions in the lithium intercalation active material, so that more lithium ions can be adsorbed into the lithium intercalation active material, thereby increasing the adsorption capacity and adsorption rate of lithium.

[0033] At the same time, the contact angle between the mobile electrode particles and water is 60-80°, which has good hydrophilicity. When using the mobile electrode lithium extraction device to extract lithium from lithium-containing brine, the contact between the mobile electrode particles and the lithium-containing brine is closer, reducing the interface resistance, which is beneficial to the transmission and diffusion of lithium ions, thereby improving the adsorption capacity and adsorption rate of lithium.

[0034] In addition, the specific surface area of ​​the flow electrode particles is 30-60m 2 / g, within a suitable range, on the one hand, it can increase the contact area between lithium ions and the particle surface, provide more lithium ion channels, and promote the embedding of lithium ions into lithium-intercalated active materials; on the other hand, it can optimize the diffusion path of lithium ions, which is beneficial to the rapid diffusion and transmission of lithium ions, thereby improving the adsorption capacity and adsorption rate of lithium.

[0035] In the present invention, the conductivity, specific surface area, and contact angle with water of the mobile electrode particles are limited, so that the mobile electrode particles have good conductivity and hydrophilicity, and good adsorption of lithium. The mobile electrode slurry prepared therefrom is used in a mobile electrode lithium extraction device to improve the adsorption capacity and adsorption rate of lithium.

[0036] In some embodiments of the present invention, the conductivity of the mobile electrode particles is not less than 5.0×10 -4 S / m.

[0037] In this embodiment, the conductivity of the mobile electrode particles is limited to not less than 5.0×10 -4 S / m, as a preferred solution, can further improve the adsorption capacity and adsorption rate of lithium.

[0038] In some embodiments of the present invention, the average particle size of the mobile electrode particles is 3-8 μm.

[0039] In this embodiment, the average particle size of the mobile electrode particles is limited to 3-8 μm. This is within a suitable range. On the one hand, it helps shorten the diffusion path of lithium ions, increase the diffusion rate of lithium ions, and thus improve the rate of lithium adsorption. On the other hand, when used in a mobile electrode lithium extraction device, the mobile electrode particles can ensure that the mobile electrode slurry has an appropriate viscosity and good fluidity, and can also prevent clogging of the lithium extraction device caused by excessively large particles.

[0040] This embodiment does not limit the testing method of the average particle size of the mobile electrode particles. For example, it can be measured by scanning electron microscopy.

[0041] In some embodiments of the present invention, the lithium-intercalation active material includes at least one of lithium manganese oxide, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and lithium nickel cobalt manganese oxide.

[0042] In this embodiment, the types of lithium-intercalating active materials are limited. These materials usually have a stable crystal structure, which can reduce the structural collapse that may occur during the lithium extraction process, making the lithium extraction process more stable, and thus improving the adsorption capacity and adsorption rate of lithium.

[0043] In a second aspect, the present invention provides a method for preparing the mobile electrode particles, comprising the following steps:

[0044] 1) ball milling a raw material system comprising the element sources of the lithium intercalation active material and a solvent at a rotation speed of 1400-2300 r / min to obtain a primary slurry, wherein the ratio of the time of the primary ball milling to the mass of the raw material system is 0.5-1 h:50-150 g;

[0045] 2) ultrasonically treating the mixed system including the primary slurry and the conductive material at a frequency of 35-40 kHz to obtain a dispersed system, wherein the ratio of the ultrasonic treatment time to the mass of the mixed system is 0.5-1 h:100-200 g;

[0046] 3) performing a secondary ball milling treatment on the dispersed system at a rotation speed of 1400-2300 r / min to obtain a secondary slurry, wherein the ratio of the secondary ball milling time to the mass of the dispersed system is 0.5-2 h:100-200 g;

[0047] 4) spray drying the secondary slurry at a feed rate of 5-30 mL / min, an inlet temperature of 200-240°C, and an outlet temperature of 100-120°C to obtain a mobile electrode particle precursor, heating the mobile electrode particle precursor to 600-850°C at a heating rate of 5-25°C / min under an inert atmosphere, and sintering the mobile electrode particles to obtain the mobile electrode particles. The sintering time is 8-20 hours.

[0048] In the present invention, the mixing order of the raw materials and the conditions of each treatment are controlled to finally prepare the mobile electrode particles provided by the first aspect of the present invention.

[0049] Specifically, in step 1), a raw material system including the element sources of the lithium-intercalated active material and a solvent is subjected to a ball milling treatment, the rotation speed of the ball milling treatment is controlled to be 1400-2300 r / min, and the mass ratio of the ball milling treatment time to the raw material system is 0.5-1h:50-150g to obtain a primary slurry. Wherein, the raw material system is a solution, a sol, a suspension or a dispersion. The lithium source is at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium oxalate, and lithium acetate; the manganese source is at least one of manganese carbonate, manganese dioxide, manganese acetate, and manganese hydroxide; the iron source is at least one of ferric hydroxide, ferric acetate, and ferrous oxalate; the phosphorus source is at least one of phosphoric acid, lithium dihydrogen phosphate, and ammonium phosphate; the nickel source is at least one of nickel oxide and nickel hydroxide; and the cobalt source is at least one of cobalt oxide, cobalt trioxide, and cobalt hydroxide. The solvent is water or a mixed solution of water and an organic solvent. When the solvent is a mixed solution of water and an organic solvent, the volume ratio of water to the organic solvent is 1:0.5-3, and the organic solvent includes at least one of ethanol, propanol, and isopropanol.

[0050] In step 2), the mixed system including the primary slurry and the conductive material is subjected to ultrasonic treatment, the ultrasonic treatment frequency is controlled to be 35-40 kHz, and the ultrasonic treatment time to the mass ratio of the mixed system is 0.5-1 hour:100-200g to obtain a dispersed system. The purpose of the ultrasonic treatment is to make the raw materials and the conductive material in the dispersed system more uniformly dispersed. The conductive material is at least one of activated carbon, carbon black, carbon nanotubes, and carbon fibers.

[0051] In step 3), the dispersed system is subjected to a secondary ball milling treatment, with the secondary ball milling speed controlled to be 1400-2300 r / min and the secondary ball milling time to dispersed system mass ratio being 0.5-2 hours:100-200g, to obtain a secondary slurry. The purpose of the secondary ball milling treatment is to obtain a secondary slurry with a relatively suitable particle size, so that mobile electrode particles of suitable particle size can be obtained through subsequent spray drying and sintering.

[0052] In step 4), the secondary slurry is spray-dried, the feed rate is controlled to be 5-30 mL / min, the inlet temperature is 200-240°C, and the outlet temperature is 100-120°C to obtain a mobile electrode particle precursor. The spray drying process can be carried out in a spray drying device. By spray drying, the conductive material and the lithium intercalation active material can be uniformly mixed. The mobile electrode particle precursor is sintered under an inert atmosphere, the heating rate of the sintering process is controlled to be 5-25°C / min, the temperature is raised to 600-850°C, and the sintering time is 8-20h. The mobile electrode particles are obtained. The inert atmosphere can be at least one of nitrogen, helium or argon, so as to protect the lithium intercalation active material during the sintering process and better form oxides. In this step, the purpose of the sintering process is to form composite microspheres including lithium intercalation active material and conductive material, so as to better improve the conductivity, hydrophilicity and specific surface area of ​​the mobile electrode particles, thereby improving the adsorption capacity and adsorption rate of lithium.

[0053] According to the preparation method of this embodiment, the conductivity of the prepared -4 S / m, the contact angle with water is 60-80°, and the specific surface area is 30-60m 2 / g of mobile electrode particles. This is presumably due to the spray drying process during the preparation process, combined with other conditions specified in the preparation method, to the formation of composite microspheres comprising a lithium-intercalated active material and a conductive material. The presence of the conductive material can increase the conductivity of the mobile electrode particles, and the resulting composite microspheres can increase the specific surface area of ​​the mobile electrode particles. The surface of the conductive material contains various functional groups, such as hydroxyl and carboxyl groups. These functional groups can form hydrogen bonds with water molecules, enhancing the adsorption and penetration of water molecules on the surface of the mobile electrode particles, thereby increasing the hydrophilicity.

[0054] The preparation method of this embodiment can prepare the above-mentioned mobile electrode particles. The preparation process is simple and easy, the particle size is uniform and controllable, and the prepared mobile electrode particles have good conductivity and hydrophilicity, and good adsorption properties for lithium. The mobile electrode slurry prepared therefrom is used in a mobile electrode lithium extraction device, which can improve the adsorption capacity and adsorption rate of lithium.

[0055] In some embodiments of the present invention, the mass molar ratio of the conductive material to the lithium element is 40-60 g:1 mol.

[0056] In this embodiment, the mass molar ratio of the conductive material to the lithium element is controlled to be 40-60 g:1 mol, which is within a suitable range. This can further improve the conductivity of the mobile electrode particles, thereby increasing the adsorption capacity and adsorption rate of lithium.

[0057] In some embodiments of the present invention, the mass volume ratio of the element sources to the solvent is 80-120 g:150-250 mL.

[0058] In this embodiment, the mass volume ratio of each element source to the solvent is controlled to be 80-120g:150-250mL. Within an appropriate range, a primary slurry with uniform particle size can be formed through a single ball milling process, so that it can be subsequently mixed with a conductive material and spray-dried and sintered to obtain mobile electrode particles with appropriate particle size.

[0059] In some embodiments of the present invention, the pressure of the spray drying process is 5.0-8.0 bar, and the nozzle aperture is 0.7-2.0 mm.

[0060] It is understood that the spray drying pressure and nozzle aperture significantly influence the particle size of the prepared mobile electrode particle precursor, which in turn affects the particle size of the mobile electrode particles obtained during the subsequent sintering process. By limiting the spray drying pressure and nozzle aperture, the particle size and size distribution of the particles can be effectively controlled.

[0061] In this embodiment, the pressure of the spray drying treatment is controlled to be 5.0-8.0 bar, and the nozzle aperture is 0.7-2.0 mm. Within an appropriate range, the particle size of the mobile electrode particle precursor obtained after the spray drying treatment can be more appropriate. The mobile electrode particle precursor is then sintered to obtain mobile electrode particles with an average particle size of 3-8 μm.

[0062] In a third aspect, the present invention provides a mobile electrode slurry comprising the mobile electrode particles as described above or the mobile electrode particles prepared by the preparation method as described above.

[0063] The mobile electrode slurry of the present invention can be obtained by mixing the mobile electrode particles and a solvent, adding the mixture into concentrated brine, and then subjecting the mixture to ultrasonic treatment.

[0064] The present invention does not particularly limit the specific type of solvent, and the solvent commonly used in the art can be selected, for example, at least one of water and ethanol.

[0065] In a fourth aspect, the present invention provides a flowing electrode lithium extraction device, comprising the flowing electrode slurry as described above.

[0066] The mobile electrode slurry can be used as the cathode mobile electrode slurry in a mobile electrode lithium extraction device. The mobile electrode lithium extraction device of the present invention includes, in addition to the cathode mobile electrode slurry, an anode mobile electrode slurry, a cation exchange membrane, and an anion exchange membrane. The anode mobile electrode slurry can be composed of activated carbon, a conductive additive, deionized water, and an electrolyte salt. The cation exchange membrane and anion exchange membrane can also be conventional exchange membranes used in the art, such as organic polymers, inorganic materials, and composite materials.

[0067] In a fifth aspect, the present invention provides a use of at least one of the mobile electrode particles, mobile electrode slurry and mobile electrode lithium extraction device as described above in electrochemical lithium extraction from brine.

[0068] The technical solution of the present invention is further described below with reference to specific embodiments.

[0069] Example 1

[0070] The method for preparing the mobile electrode particles of this embodiment includes the following steps:

[0071] 1) adding 12.59 g of LiOH·H2O, 40.39 g of (FeNO3)3·9H2O, 39.62 g of (NH4)HPO4, and 200 mL of water to a ball mill and controlling the speed to 2000 r / min for a single ball milling process for 1.45 h. The ratio of the single ball milling time to the mass of the raw material system is 0.5 h:100 g, which is recorded as a ratio of 1, to obtain a primary slurry;

[0072] 2) adding 15 g of activated carbon to the primary slurry to obtain a mixed system, controlling the frequency to 40 kHz, and performing ultrasonic treatment for 1.5 h, wherein the mass ratio of ultrasonic treatment time to mixed system is 1 h:200 g, recorded as ratio 2, and the mass molar ratio of conductive material to lithium element is 45 g:1 mol, recorded as ratio 3, to obtain a dispersed system;

[0073] 3) The dispersed system was placed in a ball mill at a speed of 2000 r / min and subjected to a secondary ball milling treatment for 1.5 h. The ratio of the secondary ball milling time to the mass of the dispersed system was 1 h:200 g, recorded as a ratio of 4, to obtain a secondary slurry;

[0074] 4) The secondary slurry was added to a spray dryer for spray drying at a feed rate of 25 mL / min, an inlet temperature of 200° C., an outlet temperature of 110° C., a pressure of 6.5 bar, and a nozzle aperture of 1.4 mm to obtain a mobile electrode particle precursor;

[0075] 5) The mobile electrode particle precursor is heated to 750° C. at a heating rate of 10° C. / min under nitrogen protection and sintered for 10 h to obtain mobile electrode particles whose lithium-intercalated active material is LiFePO 4 .

[0076] Example 2

[0077] The method for preparing the mobile electrode particles of this embodiment includes the following steps:

[0078] 1) Add 20.98 g of LiOH·H2O, 43.45 g of MnO2, 66 g of (NH4)2HPO4, and 260 mL of water into a ball mill at a speed of 2000 rpm for 1.95 h to obtain a primary slurry;

[0079] 2) Add 30 g of activated carbon to the primary slurry, control the frequency to 40 kHz, and perform ultrasonic treatment for 1.05 h to obtain a dispersed system;

[0080] 3) Place the above dispersion system into a ball mill, control the speed to 2100 r / min, and perform a secondary ball milling treatment for 3 hours to obtain a secondary slurry;

[0081] 4) The secondary slurry was added to a spray dryer for spray drying at a feed rate of 10 mL / min, an inlet temperature of 200° C., an outlet temperature of 110° C., a pressure of 6.5 bar, and a nozzle aperture of 1.4 mm to obtain a mobile electrode particle precursor;

[0082] 5) The mobile electrode particle precursor is heated to 800° C. at a heating rate of 10° C. / min under nitrogen protection and sintered for 10 h to obtain mobile electrode particles whose lithium-intercalated active material is LiMnPO 4 .

[0083] Example 3

[0084] The method for preparing the mobile electrode particles of this embodiment includes the following steps:

[0085] 1) Add 20.98 g of LiOH·H2O, 43.45 g of MnO2, and 85 mL of water to a ball mill at a speed of 2000 rpm for 1 h to obtain a primary slurry;

[0086] 2) Add 30 g of activated carbon to the primary slurry to obtain a mixed system, control the frequency to 40 kHz, and perform ultrasonic treatment for 1 hour to obtain a dispersed system;

[0087] 3) Place the above dispersion system into a ball mill, control the speed to 2000 r / min, and perform a secondary ball milling treatment for 2 hours to obtain a secondary slurry;

[0088] 4) The secondary slurry was added to a spray dryer for spray drying at a feed rate of 10 mL / min, an inlet temperature of 200° C., an outlet temperature of 110° C., a pressure of 6.8 bar, and a nozzle aperture of 1.4 mm to obtain a mobile electrode particle precursor;

[0089] 5) The mobile electrode particle precursor is heated to 650° C. at a heating rate of 10° C. / min under nitrogen protection and sintered for 10 h to obtain mobile electrode particles whose lithium-intercalated active material is LiMn 2 O 4 .

[0090] Example 4

[0091] The preparation method of the mobile electrode lithium extraction particles of this embodiment includes the following steps:

[0092] 1) Add 20.98 g of LiOH·H2O, 88.94 g of FeC2O4·2H2O, 66 g of (NH4)2HPO4, and 255 mL of water into a ball mill at a speed of 2000 rpm for 1.4 h to obtain a primary slurry;

[0093] 2) Add 20 g of carbon nanotubes to the primary slurry, control the frequency to 40 kHz, and perform ultrasonic treatment for 1.8 hours to obtain a dispersed system;

[0094] 3) Place the above dispersion system into a ball mill, control the speed to 2000 r / min, and perform a secondary ball milling treatment for 3 hours to obtain a secondary slurry;

[0095] 4) The secondary slurry was added to a spray dryer for spray drying at a feed rate of 20 mL / min, an inlet temperature of 240° C., an outlet temperature of 120° C., a pressure of 7.0 bar, and a nozzle aperture of 1.4 mm to obtain a mobile electrode particle precursor;

[0096] 5) The mobile electrode particle precursor is heated to 750° C. at a heating rate of 15° C. / min under nitrogen protection and sintered for 12 hours to obtain mobile electrode particles whose lithium-intercalated active material is LiFePO 4 .

[0097] Example 5

[0098] The method for preparing the mobile electrode particles of this embodiment includes the following steps:

[0099] 1) Add 20.98 g of LiOH·H2O, 54.00 g of FeC2O4·2H2O, 17.39 g of MnO2, 60.08 g of 81.55% H3PO4, and 300 mL of water into a ball mill at a speed of 2000 rpm for 1.5 h to obtain a primary slurry;

[0100] 2) adding 30 g of carbon black to the primary slurry, controlling the frequency to 40 kHz, and performing ultrasonic treatment for 1.5 h to obtain a dispersed system;

[0101] 3) Place the above dispersion system into a ball mill, control the speed to 2000 r / min, and perform a secondary ball milling treatment for 2 hours to obtain a secondary slurry;

[0102] 4) The secondary slurry was added to a spray dryer for spray drying at a feed rate of 11 mL / min, an inlet temperature of 240°C, an outlet temperature of 100°C, a pressure of 6.5 bar, and a nozzle aperture of 1.4 mm to obtain a mobile electrode particle precursor;

[0103] 5) The mobile electrode particle precursor was heated to 700°C under nitrogen protection at a heating rate of 20°C / min and sintered for 10 hours to obtain a lithium-intercalated active material of LiFe 0.6 Mn 0.4 PO4 flow electrode particles.

[0104] Example 6

[0105] The method for preparing the mobile electrode particles of this embodiment includes the following steps:

[0106] 1) Add 41.96 g of LiOH·H2O, 37.35 g of NiO, 15.00 g of CoO, 26.08 g of MnO2, and 240 mL of water into a ball mill at a speed of 2000 rpm for 1.5 h to obtain a primary slurry;

[0107] 2) adding 40 g of carbon black to the primary slurry, controlling the frequency to 40 kHz, and performing ultrasonic treatment for 1 hour to obtain a dispersed system;

[0108] 3) Place the above dispersion system into a ball mill, control the speed to 2000 r / min, and perform a secondary ball milling treatment for 2 hours to obtain a secondary slurry;

[0109] 4) The secondary slurry was added to a spray dryer for spray drying at a feed rate of 15 mL / min, an inlet temperature of 200° C., an outlet temperature of 120° C., a pressure of 6.5 bar, and a nozzle aperture of 1.4 mm to obtain a mobile electrode particle precursor;

[0110] 5) The mobile electrode particle precursor was heated to 650°C under nitrogen protection at a heating rate of 10°C / min and sintered for 10 hours to obtain a lithium-intercalated active material.

[0111] LiNi 0.5 Co 0.2 Mn 0.3 O2 flow electrode particles.

[0112] Examples 7-20

[0113] The preparation methods of the mobile electrode particles of Examples 7-20 are basically the same as those of Example 1, except that one or more of the preparation conditions in steps 1) to 5) are changed. Specific parameters are shown in Table 1.

[0114] Comparative Example 1

[0115] The preparation method of the mobile electrode particles of Comparative Example 1 comprises the following steps:

[0116] 1) lithium manganate, activated carbon, and deionized water were mixed in a ratio of 10:1:180 by weight, and stirred at 700 rpm for 24 hours using a magnetic stirrer at room temperature to obtain a uniform lithium manganate flowable electrode slurry;

[0117] 2) The lithium manganate mobile electrode slurry was pumped into a mobile electrode capacitive deionization device (FCDI) at a constant speed of 30 mL / min using a peristaltic pump, connected to a positive electrode (mounted with a titanium mesh), and electrolyzed under constant voltage mode (1 V) for 24 h for pre-lithiation treatment by electro-etching;

[0118] 3) The solution after the electro-etching pre-delithiation treatment is filtered through a Buchner funnel to obtain a crude lithium manganate product, and the crude lithium manganate product on the filter paper is continued to be washed with deionized water in the Buchner funnel until the deionized water is neutral to obtain the pretreated lithium manganate material, which is dried in a 60° C. blower drying oven for 24 h to obtain the LiMn2O4 powder after electro-etching.

[0119] Comparative Example 2

[0120] The preparation method of the mobile electrode particles of Comparative Example 2 comprises the following steps:

[0121] 1) Add a certain proportion of LiOH, MnO2, and water into a ball mill, control the speed to 2000 r / min, and perform a ball milling process for 3 hours to obtain a primary slurry;

[0122] 2) drying the primary slurry at high temperature and grinding it for 30 minutes to obtain a dry powder;

[0123] 3) sintering the dried powder in a box-type resistance furnace at 800° C. for 12 h to obtain LiMn2O4 particles;

[0124] 4) subjecting the LiMn2O4 particles to a secondary ball milling process to crush them into nano-sized particles;

[0125] 5) 0.72 g of activated carbon and 11.28 g of LiMn2O4 nanoparticles were dispersed in distilled water, spray-dried at 180°C, and then dried at high temperature to prepare composite microspheres containing LiMn2O4 as the lithium-intercalated active material.

[0126] Test example

[0127] 1. Electrical conductivity: The electrical conductivity of the flowable electrode particles of each embodiment and comparative example was tested using a powder resistivity meter MCP-PD51 at a pressure of 8 MPa. The results are shown in Table 1.

[0128] 2. Contact Angle: The mobile electrode particles in each embodiment and comparative example were tested using a Data Physics OCA-40Micro surface contact angle meter. The contact angles of the mobile electrode particles in that batch were obtained. The results are shown in Table 1.

[0129] 3. Adsorption capacity: In the adsorption stage, the mobile electrode particles obtained above are mixed with water, wherein the mass ratio of the mobile electrode particles to water is 85:15, and added to a 1 mol / L lithium chloride solution and ultrasonically dispersed to obtain a mobile electrode slurry (solid content of 20-40%), which is used as the cathode mobile electrode slurry (lithium insertion and extraction mobile electrode slurry) and connected to the negative pole of the power supply. The cathode mobile electrode slurry is also covered with a cation exchange membrane and separated from the lithium-containing brine feed. The lithium ions in the feed enter the cathode mobile electrode slurry through the cation exchange membrane. The anode mobile electrode slurry is obtained by mixing carbon particles, conductive carbon black, and water in a mass ratio of 80:10:10 and adding them to a 1 mol / L lithium chloride solution. Its solid content is 20-40%. The anode mobile electrode slurry is connected to the positive pole of the power supply and separated from the lithium-containing brine feed using an anion exchange membrane. The negative ions (such as chloride ions) in the feed enter the anode mobile electrode slurry through the anion exchange membrane.

[0130] During the desorption stage, a reverse voltage is applied to the mobile electrode lithium extraction device, and the above-mentioned mobile electrode slurry (lithium insertion and extraction mobile electrode slurry) serves as the anode mobile electrode slurry and is connected to the positive pole of the power supply. The surface of the anode mobile electrode slurry is also covered with an anion exchange membrane, which is separated from the lithium-containing brine feed. The lithium ions in the anode mobile electrode slurry pass through the anion exchange membrane into the recovery liquid; the cathode mobile electrode slurry is connected to the negative pole of the power supply and is separated from the lithium-containing brine feed by a cation exchange membrane. The negative ions (such as chloride ions) in the cathode mobile electrode slurry pass through the cation exchange membrane into the recovery liquid; the recovery liquid forms a lithium-rich recovery liquid during the desorption stage.

[0131] The adsorption and desorption cycles are repeated, and the lithium ion concentration of the lithium-containing brine decreases during the process. Fresh brine is replaced as the process progresses, and lithium ions are continuously enriched in the lithium-rich recovery liquid. As the lithium ion concentration in the recovery liquid increases, fresh recovery liquid is replaced to continuously obtain lithium-rich recovery liquid.

[0132] Adsorption capacity formula:

[0133]

[0134] Where C0 represents the initial concentration of lithium ions in lithium-containing brine, C e It represents the lithium ion concentration of lithium-containing brine after passing through the lithium extraction device, V represents the volume of lithium-containing brine, and m represents the mass of the mobile electrode particles.

[0135] Table 1

[0136]

[0137]

[0138] As can be seen from Table 1, compared with the comparative example, the mobile electrode particles provided by the present invention have good conductivity and hydrophilicity, and better adsorption of lithium. The mobile electrode slurry prepared therefrom is used in a mobile electrode lithium extraction device to improve the adsorption capacity and adsorption rate of lithium.

[0139] From the comparison between Example 1 and Comparative Examples 1-2, it can be seen that the mobile electrode particles provided by the present invention have good conductivity and hydrophilicity, and have good adsorption properties for lithium. The mobile electrode slurry prepared therefrom is used in a mobile electrode lithium extraction device to improve the adsorption capacity and adsorption rate of lithium.

[0140] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mobile electrode particle, characterized in that: The mobile electrode particles are composite microspheres comprising a lithium-intercalated active material and a conductive material; The conductivity of the mobile electrode particles is not less than 4.8×10 -4 S / m; The contact angle between the mobile electrode particles and water is 60-80°; The specific surface area of ​​the mobile electrode particles is 30-60m 2 / g.

2. The mobile electrode particle according to claim 1, characterized in that The conductivity of the mobile electrode particles is not less than 5.0×10 -4 S / m.

3. The mobile electrode particle according to claim 1 or 2, characterized in that: The average particle size of the mobile electrode particles is 3-8 μm.

4. The mobile electrode particle according to any one of claims 1 to 3, characterized in that: The lithium-intercalation active material includes at least one of lithium manganese oxide, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and lithium nickel cobalt manganese oxide.

5. A method for preparing mobile electrode particles according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) ball milling a raw material system comprising the element sources of the lithium intercalation active material and a solvent at a rotation speed of 1400-2300 r / min to obtain a primary slurry, wherein the ratio of the time of the primary ball milling to the mass of the raw material system is 0.5-1 h:50-150 g; 2) ultrasonically treating the mixed system including the primary slurry and the conductive material to obtain a dispersed system, wherein the ratio of the ultrasonic treatment time to the mass of the mixed system is 0.5-1h:100-200g; 3) performing a secondary ball milling treatment on the dispersed system at a rotation speed of 1400-2300 r / min to obtain a secondary slurry, wherein the ratio of the secondary ball milling time to the mass of the dispersed system is 0.5-2 h:100-200 g; 4) spray drying the secondary slurry to obtain a mobile electrode particle precursor, heating the mobile electrode particle precursor to 600-850°C at a heating rate of 5-25°C / min under an inert atmosphere, and sintering the mobile electrode particles to obtain the mobile electrode particles. The sintering time is 8-20 hours.

6. The preparation method according to claim 5, characterized in that The mass molar ratio of the conductive material to the lithium element is 40-60g:1mol.

7. The preparation method according to claim 5 or 6, characterized in that: The pressure of the spray drying process is 5.0-8.0 bar, and the nozzle aperture is 0.7-2.0 mm.

8. A flowing electrode slurry, characterized in that The mobile electrode particles include the mobile electrode particles according to any one of claims 1 to 4 or the mobile electrode particles prepared by the preparation method according to any one of claims 5 to 7.

9. A mobile electrode lithium extraction device, characterized in that: Comprising the flowing electrode slurry according to claim 8.

10. Use of at least one of the mobile electrode particles, mobile electrode slurry and mobile electrode lithium extraction device according to any one of claims 1 to 4 or 8 to 9 in electrochemical lithium extraction from brine.

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