Flowing electrode particles, method for their production and use

Abstract

This invention provides a flow electrode particle, its preparation method, and its application. The flow electrode particle is a composite microsphere comprising a lithium-intercalating active material and a conductive material; the conductivity of the flow electrode particle is not less than 4.8 × 10⁻⁶. ‑4 S / m; the contact angle between the flowing electrode particles and water is 60-80°; the specific surface area of ​​the flowing electrode particles is 30-60 m². 2 / g. The flowing electrode particles provided by this invention have good conductivity and hydrophilicity, and good adsorption of lithium. The flowing electrode slurry prepared from them can be used in flowing electrode lithium extraction devices to improve the adsorption capacity and adsorption rate of lithium.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical lithium extraction technology, and particularly relates to a flow electrode particle, its preparation method and application. Background Technology

[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 surge in demand for lithium-ion batteries. According to global lithium resource supply and demand analysis, future lithium resource supply will be insufficient to meet demand, making lithium resource development a research hotspot. Seawater, salt lake brines, and underground brines are rich in lithium resources and offer low extraction costs, making them a future trend in lithium extraction technology.

[0003] Among numerous solution-based lithium extraction methods, electrochemical methods possess advantages such as excellent selectivity, environmental friendliness, and low energy consumption, making them a current research focus. Currently, the most common electrochemical lithium extraction technology is fixed-electrode lithium extraction, which has the following drawbacks: 1. The preparation process of fixed electrode plates requires the use of N-methylpyrrolidone, which is environmentally unfriendly; 2. The proportion of active material exposed on the brine contact surface of the electrode plate is low, resulting in low utilization of lithium intercalation active sites; 3. Fixed electrode plates exhibit significant polarization effects in the brine; 4. Regeneration of fixed electrode plates requires disassembly of the device and recoating, which is labor-intensive and cumbersome. While flowing electrode lithium extraction technology can solve these problems, the flowing electrode particles used in this technology still suffer from poor conductivity, poor hydrophilicity, and poor lithium adsorption. Summary of the Invention

[0004] The main objective of this invention is to provide a flow electrode particle that has good conductivity and hydrophilicity, and good adsorption capacity for lithium. When the flow electrode slurry prepared from it is applied to a flow electrode lithium extraction device, it can improve the adsorption capacity and adsorption rate of lithium.

[0005] The present invention also provides a method for preparing flowing electrode particles, which can prepare the above-mentioned flowing electrode particles, and the process is simple, low-cost, and the particle size is uniform and controllable.

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

[0008] 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 conductive material;

[0009] The conductivity of the flowing electrode particles is not less than 4.8 × 10⁻⁶. -4 S / m;

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

[0011] The specific surface area of ​​the flowing electrode particles is 30-60 m². 2 / g.

[0012] The flow electrode particles described above have a conductivity of not less than 5.0 × 10⁻⁶. -4 S / m.

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

[0014] The flowing electrode particles described above, wherein 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] Secondly, the present invention provides a method for preparing the above-mentioned flowing electrode particles, comprising the following steps:

[0016] 1) At a rotation speed of 1400-2300 r / min, the raw material system including the element source of lithium intercalation active material and solvent is subjected to ball milling once to obtain a slurry. The time of the first ball milling treatment to the mass ratio of the raw material system is 0.5-1h:50-150g.

[0017] 2) The mixture system comprising primary slurry and conductive material is subjected to ultrasonic treatment to obtain a dispersion system, wherein the ultrasonic treatment time to the mass ratio of the mixture system is 0.5-1h:100-200g;

[0018] 3) The dispersion system is subjected to a second ball milling process at a rotation speed of 1400-2300 r / min to obtain a second slurry. The time of the second ball milling process to the mass ratio of the dispersion system is 0.5-2 h: 100-200 g.

[0019] 4) The secondary slurry is spray-dried to obtain a flow electrode particle precursor. The flow electrode particle precursor is then sintered at 600-850°C under an inert atmosphere at a heating rate of 5-25°C / min to obtain the flow 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 lithium is 40-60 g: 1 mol.

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

[0022] Thirdly, the present invention provides a flow electrode slurry, comprising the flow electrode particles as described above or flow electrode particles prepared by the preparation method described above.

[0023] Fourthly, the present invention provides a flowing electrode lithium extraction apparatus, comprising the flowing electrode slurry as described above.

[0024] Fifthly, the present invention provides the application of at least one of the flowing electrode particles, flowing electrode slurry and flowing electrode lithium extraction apparatus as described above in the electrochemical lithium extraction from brine.

[0025] This invention provides a flowing electrode particle, and limits the conductivity, specific surface area, and contact angle with water of the flowing electrode particle, so that the flowing electrode particle has good conductivity and hydrophilicity, and good adsorption of lithium. The flowing electrode slurry prepared therefrom can be used in a flowing electrode lithium extraction device to improve the adsorption capacity and adsorption rate of lithium. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this 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 flowing electrode particles is not less than 4.8 × 10⁻⁶. -4 S / m;

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

[0030] The specific surface area of ​​the flowing electrode particles is 30-60 m². 2 / g.

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

[0032] The flowing electrode slurry prepared from these flowing electrode particles, when applied to a flowing electrode lithium extraction device, can improve the adsorption capacity and rate of lithium. This is presumably because the conductivity of the flowing electrode particles is not less than 4.8 × 10⁻⁶. -4 S / m has good conductivity, which can accelerate the intercalation and deintercalation of lithium ions in lithium-intercalated active materials, allowing more lithium ions to be adsorbed into the lithium-intercalated active materials, thereby improving the adsorption capacity and adsorption rate of lithium.

[0033] Meanwhile, the contact angle between the flowing electrode particles and water is 60-80°, exhibiting good hydrophilicity. When using the flowing electrode lithium extraction device to extract lithium from lithium-containing brine, the contact between the flowing electrode particles and the lithium-containing brine becomes closer, reducing interfacial resistance. This facilitates the transport and diffusion of lithium ions, thereby improving the adsorption capacity and adsorption rate of lithium.

[0034] In addition, the specific surface area of ​​the flowing electrode particles is 30-60 m². 2 Within a suitable range, the concentration of lithium ions per g can, on the one hand, increase the contact area between lithium ions and the particle surface, providing more lithium ion channels and promoting the insertion of lithium ions into the lithium-intercalated active material; on the other hand, it can optimize the diffusion path of lithium ions, which is conducive to the rapid diffusion and transport of lithium ions, thereby improving the adsorption capacity and adsorption rate of lithium.

[0035] In this invention, the conductivity, specific surface area, and contact angle with water of the flowing electrode particles are limited, so that the flowing electrode particles have good conductivity and hydrophilicity, and good adsorption of lithium. The flowing electrode slurry prepared therefrom can be used in a flowing 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 flowing electrode particles is not less than 5.0 × 10⁻⁶. -4 S / m.

[0037] In this embodiment, the conductivity of the flowing electrode particles is limited to not less than 5.0 × 10⁻⁶. -4 S / m, as a preferred option, 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 flowing electrode particles is 3-8 μm.

[0039] In this embodiment, the average particle size of the flowing electrode particles is limited to 3-8 μm. Within this suitable range, on the one hand, it helps to shorten the diffusion path of lithium ions, increase the diffusion rate of lithium ions, and thus improve the adsorption rate of lithium. On the other hand, when these flowing electrode particles are applied to a flowing electrode lithium extraction device, the flowing electrode slurry can have a suitable viscosity and good flowability, and the blockage caused by excessively large particle sizes can also be avoided.

[0040] This embodiment does not limit the testing method for the average particle size of the flowing 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 typically have stable crystal structures, which can reduce structural collapse that may occur during the lithium extraction process, making the lithium extraction process more stable and thereby improving the adsorption capacity and adsorption rate of lithium.

[0043] Secondly, the present invention provides a method for preparing the above-mentioned flowing electrode particles, comprising the following steps:

[0044] 1) At a rotation speed of 1400-2300 r / min, the raw material system including the element source of lithium intercalation active material and solvent is subjected to ball milling once to obtain a slurry. The time of the first ball milling treatment to the mass ratio of the raw material system is 0.5-1h:50-150g.

[0045] 2) At a frequency of 35-40KHz, the mixture system including primary slurry and conductive material is ultrasonically treated to obtain a dispersion system, wherein the ultrasonic treatment time to the mass ratio of the mixture system is 0.5-1h:100-200g;

[0046] 3) The dispersion system is subjected to a second ball milling process at a rotation speed of 1400-2300 r / min to obtain a second slurry. The time of the second ball milling process to the mass ratio of the dispersion system is 0.5-2 h: 100-200 g.

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

[0048] In this invention, by controlling the mixing sequence of raw materials and the conditions of each process, the flow electrode particles provided in the first aspect of this invention are finally prepared.

[0049] Specifically, in step 1), the raw material system, including the element sources of the lithium-intercalating active material and the solvent, undergoes a single ball milling process. The rotation speed of the single ball milling process is controlled at 1400-2300 r / min, and the ratio of the single ball milling time to the mass of the raw material system is 0.5-1 h: 50-150 g, to obtain a single slurry. The raw material system can be a solution, sol, suspension, or 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 iron hydroxide, iron 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 mixture of water and an organic solvent. When the solvent is a mixture of water and an organic solvent, the volume ratio of water to organic solvent is 1:0.5-3. The organic solvent includes at least one of ethanol, propanol, and isopropanol.

[0050] In step 2), the mixture system comprising the above-mentioned primary slurry and conductive material is subjected to ultrasonic treatment. The ultrasonic treatment frequency is controlled at 35-40 kHz, and the ultrasonic treatment time to mass ratio of the mixture system is 0.5-1 h: 100-200 g, resulting in a dispersion system. The purpose of ultrasonic treatment is to make the raw materials and conductive material in the dispersion 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 above dispersion system is subjected to a secondary ball milling process. The rotation speed of the secondary ball milling process is controlled at 1400-2300 r / min, and the ratio of the secondary ball milling time to the mass of the dispersion system is 0.5-2 h: 100-200 g, to obtain a secondary slurry. The purpose of the secondary ball milling process is to obtain a secondary slurry with a suitable particle size, so that subsequent spray drying and sintering processes can yield flow electrode particles with suitable particle sizes.

[0052] In step 4), the above-mentioned secondary slurry is spray-dried, with the feed rate controlled at 5-30 mL / min, the inlet temperature at 200-240℃, and the outlet temperature at 100-120℃, to obtain the flow electrode particle precursor. The spray drying process can be carried out in a spray drying equipment, which allows for the uniform mixing of the conductive material and the lithium-intercalated active material. The above-mentioned flow electrode particle precursor is then sintered under an inert atmosphere, with the sintering heating rate controlled at 5-25℃ / min, reaching a temperature of 600-850℃, and the sintering time at 8-20 h. The above-mentioned flow electrode particles are then obtained. The inert atmosphere can be at least one of nitrogen, helium, or argon to protect the lithium-intercalated active material during the sintering process and to better form oxides. The purpose of the sintering process in this step is to form composite microspheres comprising the lithium-intercalated active material and the conductive material, thereby improving the conductivity, hydrophilicity, and specific surface area of ​​the flow electrode particles, and thus increasing the adsorption capacity and adsorption rate of lithium.

[0053] The preparation method of this embodiment can produce an electrical conductivity of not less than 4.8 × 10⁻⁶. -4 S / m, contact angle with water is 60-80°, specific surface area is 30-60m² 2 / g of flowing electrode particles. It is speculated that this is because the spray drying process during preparation, combined with other conditions specified in the preparation method, forms composite microspheres including lithium-intercalated active materials and conductive materials. The presence of conductive materials can improve the conductivity of flowing electrode particles, and the formed composite microspheres can increase the specific surface area of ​​flowing electrode particles. The surface of conductive materials contains a variety of functional groups, such as hydroxyl and carboxyl groups. These functional groups can form hydrogen bonds with water molecules, improving the adsorption and penetration of water molecules on the surface of flowing electrode particles, thereby improving hydrophilicity.

[0054] The preparation method of this embodiment can prepare the above-mentioned flowing electrode particles. The preparation process is simple and easy, the particle size is uniform and controllable, and the prepared flowing electrode particles have good conductivity and hydrophilicity, and good adsorption of lithium. The flowing electrode slurry prepared therefrom can be used in a flowing electrode lithium extraction device to 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 lithium is 40-60 g: 1 mol.

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

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

[0058] In this embodiment, the mass-volume ratio of each element source to the solvent is controlled to be 80-120g:150-250mL. Within a suitable range, a slurry with uniform particle size can be formed through a single ball milling process. This slurry can then be mixed with conductive materials and subjected to spray drying and sintering processes to obtain flow electrode particles with suitable 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 orifice diameter is 0.7-2.0 mm.

[0060] It is understandable that the pressure and nozzle orifice diameter of the spray drying process have a significant impact on the particle size of the prepared flow electrode precursor, which in turn affects the particle size of the flow electrode particles obtained from subsequent sintering. Limiting the pressure and nozzle orifice diameter of the spray drying process can effectively control the particle size and particle size distribution.

[0061] In this embodiment, the spray drying pressure is controlled at 5.0-8.0 bar and the nozzle orifice diameter is 0.7-2.0 mm. Within a suitable range, the particle size of the flow electrode particle precursor obtained after spray drying is relatively suitable. Then, the flow electrode particle precursor is sintered to obtain flow electrode particles with an average particle size of 3-8 μm.

[0062] Thirdly, the present invention provides a flow electrode slurry, comprising the flow electrode particles as described above or flow electrode particles prepared by the preparation method described above.

[0063] The flow electrode slurry of the present invention can be obtained by mixing the above-mentioned flow electrode particles with a solvent and adding them to concentrated brine and then ultrasonically treating them.

[0064] The present invention does not specifically limit the type of solvent, and solvents commonly used in the art can be selected, such as at least one of water and ethanol.

[0065] Fourthly, the present invention provides a flowing electrode lithium extraction apparatus, comprising the flowing electrode slurry as described above.

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

[0067] Fifthly, the present invention provides the application of at least one of the flowing electrode particles, flowing electrode slurry and flowing electrode lithium extraction apparatus as described above in the electrochemical lithium extraction from brine.

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

[0069] Example 1

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

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

[0072] 2) Add 15g of activated carbon to the above slurry to obtain a mixed system. Control the frequency at 40KHz and perform ultrasonic treatment for 1.5h. The ratio of ultrasonic treatment time to the mass of the mixed system is 1h:200g, which is recorded as ratio 2. The molar ratio of conductive material to lithium element is 45g:1mol, which is recorded as ratio 3. A dispersion system is obtained.

[0073] 3) Place the above dispersion system into a ball mill and control the rotation speed at 2000 r / min for a second ball milling treatment for 1.5 h. The ratio of the second ball milling treatment time to the mass of the dispersion system is 1 h: 200 g, which is recorded as ratio 4, to obtain the second slurry.

[0074] 4) The above secondary slurry is added to a spray dryer for spray drying. The feed rate is controlled at 25 mL / min, the inlet temperature is 200℃, the outlet temperature is 110℃, the pressure is 6.5 bar, and the nozzle orifice diameter is 1.4 mm to obtain the flow electrode particle precursor.

[0075] 5) The above-mentioned flow electrode particle precursor was sintered at 750°C for 10 h under nitrogen protection at a heating rate of 10°C / min to obtain flow electrode particles with LiFePO4 as the lithium intercalation active material.

[0076] Example 2

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

[0078] 1) Add 20.98g LiOH·H2O, 43.45g MnO2, 66g (NH4)2HPO4 and 260mL water to a ball mill, control the speed at 2000r / min, and perform a ball milling process for 1.95h to obtain a primary slurry;

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

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

[0081] 4) The above secondary slurry is added to a spray dryer for spray drying. The feed rate is controlled at 10 mL / min, the inlet temperature is 200℃, the outlet temperature is 110℃, the pressure is 6.5 bar, and the nozzle orifice diameter is 1.4 mm to obtain the flow electrode particle precursor.

[0082] 5) The above-mentioned flow electrode particle precursor was sintered at 800°C for 10 hours under nitrogen protection at a heating rate of 10°C / min to obtain flow electrode particles with LiMnPO4 as the lithium intercalation active material.

[0083] Example 3

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

[0085] 1) Add the raw material system consisting of 20.98g LiOH·H2O, 43.45g MnO2, and 85mL water into a ball mill, control the speed at 2000r / min, and perform a ball milling process for 1h to obtain a slurry;

[0086] 2) Add 30g of activated carbon to the above slurry to obtain a mixed system. Control the frequency at 40KHz and perform ultrasonic treatment for 1h to obtain a dispersion system.

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

[0088] 4) The above secondary slurry is added to a spray dryer for spray drying. The feed rate is controlled at 10 mL / min, the inlet temperature is 200℃, the outlet temperature is 110℃, the pressure is 6.8 bar, and the nozzle orifice diameter is 1.4 mm to obtain the flow electrode particle precursor.

[0089] 5) The above-mentioned flow electrode particle precursor was sintered at 650°C for 10 h under nitrogen protection at a heating rate of 10°C / min to obtain flow electrode particles with LiMn2O4 as the lithium intercalation active material.

[0090] Example 4

[0091] The method for preparing lithium extraction particles using a flowing electrode in this embodiment includes the following steps:

[0092] 1) Add 20.98g LiOH·H2O, 88.94g FeC2O4·2H2O, 66g (NH4)2HPO4, and 255mL of water to a ball mill, control the speed at 2000r / min, and perform a ball milling process for 1.4h to obtain a primary slurry;

[0093] 2) Add 20g of carbon nanotubes to the above slurry, control the frequency at 40KHz, and perform ultrasonic treatment for 1.8h to obtain a dispersion system;

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

[0095] 4) The above secondary slurry is added to a spray dryer for spray drying. The feed rate is controlled at 20 mL / min, the inlet temperature is 240℃, the outlet temperature is 120℃, the pressure is 7.0 bar, and the nozzle orifice diameter is 1.4 mm to obtain the flow electrode particle precursor.

[0096] 5) The above-mentioned flow electrode particle precursor was sintered at 750°C for 12 hours under nitrogen protection at a heating rate of 15°C / min to obtain flow electrode particles with LiFePO4 as the lithium intercalation active material.

[0097] Example 5

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

[0099] 1) Add 20.98g LiOH·H2O, 54.00g FeC2O4·2H2O, 17.39g MnO2, 60.08g H3PO4 with a mass fraction of 81.55%, and 300mL of water to a ball mill, control the speed at 2000r / min, and perform a ball milling treatment for 1.5h to obtain a primary slurry;

[0100] 2) Add 30g of carbon black to the above primary slurry, control the frequency at 40KHz, and perform ultrasonic treatment for 1.5h to obtain a dispersion system;

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

[0102] 4) The above secondary slurry was added to a spray dryer for spray drying. The feed rate was controlled at 11 mL / min, the inlet temperature was 240℃, the outlet temperature was 100℃, the pressure was 6.5 bar, and the nozzle orifice diameter was 1.4 mm to obtain the flow electrode particle precursor.

[0103] 5) The above-mentioned flow electrode particle precursor was sintered at 700℃ for 10 hours under nitrogen protection at a heating rate of 20℃ / min to obtain the lithium intercalation active material LiFe. 0.6 Mn 0.4 PO4 flow electrode particles.

[0104] Example 6

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

[0106] 1) Add 41.96g LiOH·H2O, 37.35g NiO, 15.00g CoO, 26.08g MnO2 and 240mL water to a ball mill, control the speed at 2000r / min, and perform a ball milling process for 1.5h to obtain a primary slurry;

[0107] 2) Add 40g of carbon black to the above primary slurry, control the frequency at 40KHz, and perform ultrasonic treatment for 1h to obtain a dispersion system;

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

[0109] 4) Add the above secondary slurry to a spray dryer for spray drying, control the feed rate to be 15 mL / min, the inlet temperature to be 200℃, the outlet temperature to be 120℃, the pressure to be 6.5 bar, and the nozzle orifice diameter to be 1.4 mm, to obtain the flow electrode particle precursor.

[0110] 5) The above-mentioned flow electrode particle precursor was sintered at 650°C for 10 hours under nitrogen protection at a heating rate of 10°C / min to obtain the lithium-intercalating active material.

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

[0112] Examples 7-20

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

[0114] Comparative Example 1

[0115] The method for preparing the flow electrode particles of Comparative Example 1 includes the following steps:

[0116] 1) Mix lithium manganese oxide, activated carbon and deionized water in a mass ratio of 10:1:180 and stir at 700 r / min for 24 h at room temperature using a magnetic stirrer to obtain a uniform lithium manganese oxide flow electrode slurry.

[0117] 2) The above-mentioned lithium manganese oxide flow electrode slurry was pumped into the flow electrode capacitor deionization (FCDI) device at a constant speed of 30 mL / min using a peristaltic pump and connected to positive voltage (with titanium mesh installed). Electrolysis was performed for 24 hours in constant voltage mode (1V) for pre-lithiation treatment.

[0118] 3) The solution that has undergone pre-lithiation treatment by electro-etching is filtered through a Buchner funnel to obtain crude lithium manganese oxide. The crude lithium manganese oxide on the filter paper is then washed with deionized water in the Buchner funnel until the deionized water is neutral, thus obtaining the pre-treated lithium manganese oxide material. The material is then dried in a forced-air drying oven at 60°C for 24 hours to obtain electro-etched LiMn2O4 powder.

[0119] Comparative Example 2

[0120] The method for preparing the flow electrode particles of Comparative Example 2 includes the following steps:

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

[0122] 2) The above-mentioned primary slurry is subjected to high-temperature drying and then ground for 30 minutes to obtain a dry powder;

[0123] 3) The above-mentioned dried powder was sintered in a box-type resistance furnace at 800°C for 12 hours to obtain LiMn2O4 particles;

[0124] 4) The above LiMn2O4 particles were subjected to a second ball milling process to pulverize them into nano-sized particles;

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

[0126] Test case

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

[0128] 2. Contact Angle: The contact angle of the flowing electrode particles in each embodiment and comparative example was measured using a Data Physics OCA-40Micro surface contact angle meter. The results are shown in Table 1.

[0129] 3. Adsorption Capacity: During the adsorption stage, the obtained mobile electrode particles are mixed with water at a mass ratio of 85:15 and added to a 1 mol / L lithium chloride solution. The mixture is then ultrasonically dispersed to obtain a mobile electrode slurry (solid content 20-40%), which serves as the cathode mobile electrode slurry (lithium intercalation / deintercalation mobile electrode slurry). This slurry is connected to the negative electrode of the power supply. The cathode mobile electrode slurry is also covered with a cation exchange membrane to separate it from the lithium-containing brine feed. Lithium ions in the feed pass through the cation exchange membrane into the cathode mobile electrode slurry. The anode mobile electrode slurry is obtained by mixing carbon particles, conductive carbon black, and water at 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 electrode of the power supply and separated from the lithium-containing brine feed using an anion exchange membrane. Negative ions (such as chloride ions) in the feed pass through the anion exchange membrane into the anode mobile electrode slurry.

[0130] During the desorption stage, a reverse voltage is applied to the lithium extraction device of the flowing electrode. The aforementioned flowing electrode slurry (lithium insertion / deintercalation flowing electrode slurry) serves as the anode flowing electrode slurry and is connected to the positive terminal of the power supply. The surface of the anode flowing electrode slurry is also covered with an anion exchange membrane, separating it from the lithium-containing brine feed. Lithium ions in the anode flowing electrode slurry pass through the anion exchange membrane into the recovery solution. The cathode flowing electrode slurry is connected to the negative terminal of the power supply and is separated from the lithium-containing brine feed using a cation exchange membrane. Negative ions (such as chloride ions) in the cathode flowing electrode slurry pass through the cation exchange membrane into the recovery solution. The recovery solution forms a lithium-rich recovery solution during the desorption stage.

[0131] The adsorption and desorption cycles repeatedly. During this process, the lithium ion concentration in the lithium-containing brine decreases. As the process progresses, fresh brine is replaced, and lithium ions continuously accumulate in the lithium-rich recovery solution. As the lithium ion concentration in the recovery solution increases, fresh recovery solution is replaced, and lithium-rich recovery solution is continuously obtained.

[0132] Adsorption capacity formula:

[0133]

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

[0135] Table 1

[0136]

[0137]

[0138] As shown in Table 1, compared with the comparative example, the flow electrode particles provided by the present invention have good conductivity and hydrophilicity, and good adsorption of lithium. The flow electrode slurry prepared therefrom can improve the adsorption capacity and adsorption rate of lithium when applied in a flow electrode lithium extraction device.

[0139] As can be seen from the comparison between Example 1 and Comparative Examples 1-2, the flow electrode particles provided by the present invention have good conductivity and hydrophilicity, and good adsorption of lithium. The flow electrode slurry prepared therefrom can be used in a flow 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, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 type of flowing electrode particle, characterized in that, The flowing electrode particles are composite microspheres comprising lithium-intercalated active materials and conductive materials; The conductivity of the flowing electrode particles is not less than 4.8 × 10⁻⁶. -4 S / m; The contact angle between the flowing electrode particles and water is 60-80°; The specific surface area of ​​the flowing electrode particles is 30-60 m². 2 / g; The average particle size of the flowing electrode particles is 3-8 μm; The flowing electrode particles are prepared by a method comprising the following steps: 1) At a rotation speed of 1400-2300 r / min, the raw material system including the element source of lithium intercalation active material and solvent is subjected to ball milling once to obtain a slurry. The time of the first ball milling treatment to the mass ratio of the raw material system is 0.5-1 h: 50-150 g. 2) The mixture system comprising primary slurry and conductive material is subjected to ultrasonic treatment to obtain a dispersion system, wherein the ultrasonic treatment time to the mass ratio of the mixture system is 0.5-1h:100-200g; 3) The dispersion system is subjected to a second ball milling process at a rotation speed of 1400-2300 r / min to obtain a second slurry. The time of the second ball milling process to the mass ratio of the dispersion system is 0.5-2 h: 100-200 g. 4) The secondary slurry is spray-dried to obtain a flow electrode particle precursor. The flow electrode particle precursor is then sintered at 600-850°C under an inert atmosphere at a heating rate of 5-25°C / min to obtain the flow electrode particles. The sintering time is 8-20 hours.

2. The flowing electrode particles according to claim 1, characterized in that, The conductivity of the flowing electrode particles is not less than 5.0 × 10⁻⁶. -4 S / m.

3. The flowing electrode particles according to claim 1 or 2, 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.

4. A method for preparing flowing electrode particles as described in any one of claims 1-3, characterized in that, Includes the following steps: 1) The raw material system, including the element sources of lithium intercalation active material and solvent, is subjected to ball milling at a speed of 1400-2300 r / min to obtain a primary slurry. The time of the primary ball milling is 0.5-1 h: 50-150 g of the raw material system. 2) The mixture system comprising primary slurry and conductive material is subjected to ultrasonic treatment to obtain a dispersion system, wherein the ultrasonic treatment time to the mass ratio of the mixture system is 0.5-1h:100-200g; 3) The dispersion system is subjected to a second ball milling process at a rotation speed of 1400-2300 r / min to obtain a second slurry. The time of the second ball milling process to the mass ratio of the dispersion system is 0.5-2 h: 100-200 g. 4) The secondary slurry is spray-dried to obtain a flow electrode particle precursor. The flow electrode particle precursor is then sintered at 600-850°C under an inert atmosphere at a heating rate of 5-25°C / min to obtain the flow electrode particles. The sintering time is 8-20 hours.

5. The preparation method according to claim 4, characterized in that, The mass molar ratio of the conductive material to lithium is 40-60 g: 1 mol.

6. The preparation method according to claim 4 or 5, characterized in that, The spray drying process is performed at a pressure of 5.0-8.0 bar and a nozzle orifice diameter of 0.7-2.0 mm.

7. A flowable electrode slurry, characterized in that, It includes the flow electrode particles according to any one of claims 1-3 or the flow electrode particles prepared by the preparation method according to any one of claims 4-6.

8. A flowing electrode lithium extraction device, characterized in that, Includes the flow electrode slurry as described in claim 7.

9. The use of at least one of the flowing electrode particles, flowing electrode slurry and flowing electrode lithium extraction apparatus according to any one of claims 1-3 or 7-8 in the electrochemical lithium extraction of brine.

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