A preparation device and method for high compaction density lithium iron phosphate

Abstract

The present invention belongs to the technical field of lithium-ion battery material preparation, and in particular to a preparation device and method of high compacted density lithium iron phosphate. In view of the fact that current grinding equipment cannot meet grinding requirements, the following scheme is proposed, including a mixing and grinding box, wherein a grinding table is provided inside the mixing and grinding box, and a grinding assembly is provided on the grinding table, wherein the grinding assembly includes a grinding disc and an outer support disc, and a grinding cavity is provided inside the grinding table, and the grinding disc is located inside the grinding cavity. A preparation device of high compacted density lithium iron phosphate disclosed in the present invention can fully mix and grind the raw materials added to the dispersant, thereby ensuring the particle specifications of the raw materials after mixing, and utilizing the rotary grinding operation between the grinding disc and the inner grinding layer to improve the effect of raw material grinding, thereby ensuring that the raw materials after grinding are more delicate, and avoiding the situation where the particles are uneven due to insufficient grinding of multiple substances, thereby affecting the subsequent production and processing process.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery material preparation, and in particular to a preparation device and a preparation method of high compaction density lithium iron phosphate. Background Art

[0002] Lithium iron phosphate is one of the mainstream positive electrode materials for lithium-ion batteries on the market. Compared with other positive electrode materials, such as lithium cobalt oxide and ternary positive electrode materials, lithium iron phosphate positive electrode material has the advantages of low price, non-toxicity, and environmental friendliness. It also has excellent safety performance and cycle stability, and has great application prospects in the fields of power and energy storage.

[0003] The preparation of high compaction density lithium iron phosphate requires sufficient mixing and grinding of iron phosphate, lithium source, additives, carbon source and solvent in a dispersant to ensure that the obtained precursor particles meet production requirements, but the current grinding equipment cannot meet the grinding requirements. Summary of the invention

[0004] The invention discloses a preparation device and a preparation method of high compaction density lithium iron phosphate, aiming to solve the technical problem in the background technology that the current grinding equipment cannot meet the grinding requirements.

[0005] The present invention proposes a preparation device of high compacted density lithium iron phosphate, comprising a mixing grinding box, a grinding table is arranged inside the mixing grinding box, and a grinding assembly is arranged on the grinding table, the grinding assembly comprises a grinding disc and an outer support disc, and a grinding cavity is opened inside the grinding table, the grinding disc is located inside the grinding cavity, and the upper and lower ends of the grinding disc are movably connected to the interior of the grinding table, an inner grinding layer is arranged inside the grinding cavity, the inner grinding layer is funnel-shaped, and the grinding disc is in the shape of an inverted frustum, and the gap between the grinding disc and the inner grinding layer gradually decreases from top to bottom, a plurality of circumferentially equidistant feed ports are opened above the grinding table, the feed ports are connected to the grinding cavity, and a discharge disc is arranged on the lower side of the grinding table, the outer support disc is located above the grinding table, and three circumferentially equidistant limit rods are fixedly connected to the lower side of the outer support disc and the upper side of the grinding table, and a circular hole is opened in the middle of the outer support disc, and a rotating shaft is movably connected to the interior of the circular hole, and the lower end of the rotating shaft is fixedly connected to the upper side of the grinding disc.

[0006] By providing a grinding component, the raw materials added to the dispersant can be fully mixed and ground by the grinding component, so as to ensure the particle specifications of the raw materials after mixing. The rotary grinding operation between the grinding disc and the inner grinding layer can improve the effect of raw material grinding, so as to ensure that the raw materials after grinding are more delicate, and avoid the situation where the particles of multiple substances are uneven due to insufficient grinding, thereby affecting the subsequent production and processing process.

[0007] In a preferred scheme, the upper side of the mixing and grinding box is fixedly connected with a box cover, and a top frame is arranged above the box cover, two symmetrical sliding rods are fixedly connected between the top frame and the outer support plate, the sliding rods are movably connected between the box cover, and a first motor is fixedly connected to the top frame, and the output end of the first motor is connected to the top end of the rotating shaft through a coupling; the outside of the mixing and grinding box is fixedly connected with an external accessory sleeve, and two symmetrical supporting legs are fixedly connected to the external accessory sleeve, and a feeding pipe and a plurality of equidistant auxiliary material pipes are arranged on the box cover; a side frame is arranged on one side of the mixing and grinding box, and a support is fixedly connected to the side frame, a slide groove is provided on the support, and a connecting frame is movably connected inside the slide groove, one end of the connecting frame is fixedly connected to the top frame, and a hydraulic cylinder is fixedly connected to the support, and the top end of the hydraulic cylinder is fixedly connected to the lower side of the connecting frame.

[0008] By providing a hydraulic cylinder, the grinding table is driven to move longitudinally by the hydraulic cylinder, so that it can be lifted up and down at a uniform speed during the grinding process, thereby achieving the purpose of improving the mixing effect in the mixing and grinding box. At the same time, the up and down movement state can promote the raw materials in the mixing and grinding box to enter the grinding table, avoiding the accumulation of raw materials in the mixing and grinding box, which causes the raw materials to enter the grinding table unsmoothly and reduces the grinding effect.

[0009] In a preferred embodiment, a rectangular groove is provided at the bottom of the mixing and grinding box, a discharge valve is fixedly connected inside the rectangular groove, three equidistant discharge pipes are arranged below the discharge valve, the lower ends of the three discharge pipes are fixedly connected to the feeding pipes, and the three feeding pipes are provided with a discharge conveying assembly; the discharge conveying assembly comprises a shaft rod and a discharge bin, a cylindrical cavity is provided inside the feeding pipes, the shaft rod is located inside the cylindrical cavity of the feeding pipes, one end of the shaft rod is movably connected to the inner wall of the cylindrical cavity, and the other end of the shaft rod is fixedly connected to a wheel through the feeding pipe; a spiral feeding blade is fixedly connected to the outside of the shaft rod, the three feeding pipes are all tilted, and the discharge bin is fixedly connected to the lower side of the feeding pipe, and the discharge bin is located at the upward end of the feeding pipe; the three feeding pipes are fixedly connected to the same sleeve, the sleeve is fixedly connected to a second motor, and the output end of the second motor is connected to a short shaft through a coupling, the other end of the short shaft is fixedly connected to an active disk, and a belt is arranged between the active disk and the wheel.

[0010] By providing a discharging conveying assembly, the ground material can be initially conveyed for solid-liquid separation, and the material can be conveyed obliquely upwards by means of an inclined conveying pipe and spiral feeding blades and discharged from a lower silo. A simple draining operation can be performed during the process to avoid a large amount of water being mixed into the mixed and ground material, which would be inconvenient for subsequent drying operations.

[0011] In a preferred solution, the lower ends of the three feed pipes are fixedly connected to the same liquid collecting pipe, which is located at one end of the feed pipe away from the lower feed bin, and the outside of the liquid collecting pipe is fixedly connected to a support frame, and a drain pipe is provided at one end of the liquid collecting pipe, which is connected to the external conveying pipeline by a flange; a semicircular mounting groove is provided on the three conveying pipes, and a filtrate seat is fixedly connected to the inside of the mounting groove, and the other end of the filtrate seat passes through the tube wall of the liquid collecting pipe and the inner cavity of the liquid collecting pipe.

[0012] The present invention further provides a method for preparing high compaction density lithium iron phosphate, comprising the following steps:

[0013] S100, using the above-mentioned preparation device to prepare large-sized lithium iron phosphate particles and small-sized lithium iron phosphate particles respectively;

[0014] S200, mixing the large-sized lithium iron phosphate particles with the small-sized lithium iron phosphate particles in a mass ratio of 1:1.5-2.5 to form a lithium iron phosphate positive electrode material.

[0015] From the above, it can be seen that the preparation device of high compacted density lithium iron phosphate provided by the present invention has the ability to fully mix and grind the raw materials added to the dispersant, so as to ensure the particle specifications of the raw materials after mixing. The rotary grinding operation between the grinding disc and the inner grinding layer can improve the effect of raw material grinding, thereby ensuring that the raw materials are more delicate after grinding, and avoiding the situation where uneven particles are caused by insufficient grinding of multiple substances, thereby affecting the subsequent production and processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the overall structure of a preparation device for high compaction density lithium iron phosphate proposed by the present invention;

[0017] Figure 2 This is a schematic cross-sectional view of a device for preparing high compaction density lithium iron phosphate proposed by the present invention;

[0018] Figure 3 A schematic diagram of the structure of a grinding assembly of a device for preparing lithium iron phosphate with high compaction density proposed by the present invention;

[0019] Figure 4 This is a schematic cross-sectional structure diagram of a grinding table of a preparation device for high compaction density lithium iron phosphate proposed by the present invention;

[0020] Figure 5 A schematic diagram of the internal structure of a grinding table of a preparation device for high compaction density lithium iron phosphate proposed by the present invention;

[0021] Figure 6 This is a schematic diagram of the structure of a discharging and conveying assembly of a high compaction density lithium iron phosphate preparation device proposed by the present invention;

[0022] Figure 7 A schematic diagram of the internal structure of a feed pipe of a high compaction density lithium iron phosphate preparation device proposed by the present invention;

[0023] Figure 8 This is a SEM photograph of two carbon-coated mixed high-density lithium iron phosphates provided in an embodiment of the present invention.

[0024] In the figure: 1, mixing and grinding box; 2, grinding table; 3, grinding assembly; 301, grinding disc; 302, outer support disc; 303, grinding chamber; 304, inner grinding layer; 305, feeding port; 306, discharging disc; 307, limiting rod; 308, rotating shaft; 4, box cover; 5, top frame; 6, sliding rod; 7, first motor; 8, outer sleeve; 9, supporting leg; 10, feeding pipe; 11, auxiliary material pipe; 12, side frame; 13. Support; 14. Connecting frame; 15. Hydraulic cylinder; 16. Discharge valve; 17. Discharge pipe; 18. Feed pipe; 19. Discharge conveying assembly; 1901. Second motor; 1902. Shaft; 1903. Discharge bin; 1904. Sleeve; 1905. Spiral feed blade; 1906. Wheel; 1907. Belt; 20. Collecting pipe; 21. Filtrate seat; 22. Drain pipe; 23. Support frame. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0026] The invention discloses a preparation device for high compacted density lithium iron phosphate, which is mainly used in scenarios where the mixing and grinding process efficiency is low.

[0027] Reference Figure 1-5A preparation device of lithium iron phosphate with high compaction density includes a mixing and grinding box 1, a grinding table 2 is arranged inside the mixing and grinding box 1, and a grinding assembly 3 is arranged on the grinding table 2, the grinding assembly 3 includes a grinding disc 301 and an outer support disc 302, and a grinding cavity 303 is opened inside the grinding table 2, the grinding disc 301 is located inside the grinding cavity 303, the upper and lower ends of the grinding disc 301 are rotatably connected with the inside of the grinding table 2 through bearings, an inner grinding layer 304 is arranged inside the grinding cavity 303, the inner grinding layer 304 is funnel-shaped, and the grinding disc 301 is an inverted frustum, and the grinding disc 301 and the inner grinding layer 304 are funnel-shaped. The gap between the inner grinding layers 304 decreases gradually from top to bottom. A plurality of circumferentially equidistant feed ports 305 are provided above the grinding table 2. The feed ports 305 are connected to the grinding chamber 303, and a discharge tray 306 is provided on the lower side of the grinding table 2. The outer support plate 302 is located above the grinding table 2. The lower side of the outer support plate 302 and the upper side of the grinding table 2 are connected by bolts with three circumferentially equidistant limit rods 307, and a circular hole is provided in the middle of the outer support plate 302. A rotating shaft 308 is rotatably connected to the inside of the circular hole through a bearing, and the lower end of the rotating shaft 308 is connected to the upper side of the grinding disc 301 by bolts.

[0028] Specifically, the raw materials are added into the mixing and grinding box 1, the device is started, the grinding table 2 moves slowly up and down, and the grinding assembly 3 mixes and grinds the raw materials in the mixing and grinding box 1. The process is as follows: as the rotating shaft 308 rotates, the raw materials in the mixing and grinding box 1 rotate due to the centripetal force of the rotation, and the raw materials enter the grinding table 2 from the feed port 305. Since the grinding disc 301 is always in a rotating state, the raw materials will flow downward after entering from the feed port 305 and be discharged from the discharge disc 306 at the bottom. In the process of flowing downward, the grinding disc 301 and the inner grinding layer 304 will continuously rotate and grind the raw materials.

[0029] Specifically, in one embodiment, the raw materials include a mixture of iron phosphate, lithium carbonate and an organic carbon source, and then ground to 200-500 nm in a deionized water medium (achieved by the preparation device);

[0030] Then spray drying, sintering and finally air flow crushing are performed to form large-sized lithium iron phosphate particles with a particle size of 600-1000nm; wherein the organic carbon source is one or more of sucrose, polybutadiene, polyethylene glycol, etc., and the organic carbon source is 6%-9%wt of the total mixture weight.

[0031] Among them, the molar ratio of Fe / P in the iron phosphate is preferably 0.95~0.98:1; and the molar ratio of Li / Fe in the lithium carbonate is preferably 1~1.06:1.

[0032] Preferably, the Li ratio is generally slightly excessive, which can inhibit the growth of grains during high-temperature sintering, but it should not be too excessive, otherwise it will lead to increased alkalinity of the product, making it difficult to store and process.

[0033] As a further improvement, the temperature of the spray drying is between 150-300°C; the temperature of the atmosphere sintering is controlled between 700-850°C. Preferably, the temperature of the spray drying is between 160-180°C; the temperature of the atmosphere sintering is controlled between 750-780°C. Since the organic carbon source also has a high content of other groups such as hydroxyl groups, a higher temperature is required to carbonize it. In one embodiment, the temperature of the atmosphere sintering is controlled at about 770°C.

[0034] As a further improvement, the step of finally performing air flow crushing to form large-sized lithium iron phosphate particles with a particle size of 600-1000 nm comprises:

[0035] Finally, air flow crushing is performed to form large-sized lithium iron phosphate particles with a particle size of 850-950 nm. In one embodiment, air flow crushing is performed to form large-sized lithium iron phosphate particles with a particle size of 890 nm-910 nm.

[0036] In another embodiment, the raw material includes a mixture of iron phosphate, lithium carbonate and an inorganic carbon source, which is then ground to 100-300 nm in a deionized water medium (achieved by the preparation device), and then spray dried, sintered, and finally air flow crushed to form small-sized lithium iron phosphate particles with a particle size of 300-500 nm, wherein the inorganic carbon source is carbon black, acetylene black and a mixture thereof, and the inorganic carbon source is 4%-6%wt of the total mixture weight. The molar ratio of Fe / P in the iron phosphate is preferably 0.95-0.98:1; and the molar ratio of Li / Fe in lithium carbonate is preferably 1-1.06:1. In one embodiment, the molar ratio of Fe / P in the iron phosphate is preferably 0.965:1; and the molar ratio of Li / Fe in lithium carbonate is preferably 1.03:1.

[0037] As a further improvement, the temperature of the spray drying is between 150-300°C; the temperature of the atmosphere sintering is controlled between 650-700°C. Preferably, the temperature of the spray drying is between 160-180°C; the temperature of the atmosphere sintering is controlled between 660-680°C. Since the carbon content in the inorganic carbon source is relatively high, the sintering temperature can be lowered. In one embodiment, the temperature of the atmosphere sintering is controlled at about 670°C. The sintering temperature should not be too high. If it is too high, the inorganic carbon source will be adsorbed on the surface of the small-sized lithium iron phosphate, and a grafted flocculent structure will not be formed, which will make it difficult to form a good conductive bridge between the large size and the small size.

[0038] As a further improvement, the step of finally performing air flow crushing to form small-sized lithium iron phosphate particles with a particle size of 300-500 nm includes:

[0039] Finally, air flow crushing is performed to form small-sized lithium iron phosphate particles with a particle size of 350-450 nm. In one embodiment, air flow crushing is performed to form small-sized lithium iron phosphate particles with a particle size of 380-400 nm.

[0040] Finally, the large-sized lithium iron phosphate particles and the small-sized lithium iron phosphate particles are mixed in a mass ratio of 1:1.5-2.5 to form a lithium iron phosphate positive electrode material.

[0041] The present invention prepares two kinds of nano-sized lithium iron phosphate materials, and by coating the large particles with an organic carbon source, the organic carbon source will decompose into highly graphitized carbon and evenly distribute on the surface of the lithium iron phosphate particles under high temperature environment. The small particles of lithium iron phosphate are coated with an inorganic carbon source, and the inorganic carbon source is distributed between the particles as a flocculent continuous carbon source. At the same time, the lithium iron phosphate material as a small particle is distributed with the large particle lithium iron phosphate material coated with the organic carbon source, and a conductive bridge is constructed. The large particle lithium iron phosphate material and the small particle lithium iron phosphate material form a good inter-particle electron conduction. At the same time, due to the presence of the small particle material, the transmission distance of lithium ions is reduced, and the ionic conductivity of the material itself is increased. And the mixing of large and small particles further improves the compaction density of the material. Preferably, the large-sized lithium iron phosphate particles and the small-sized lithium iron phosphate particles are mixed in a mass ratio of 1:1.8~2.2 to form a lithium iron phosphate positive electrode material. In one embodiment, the large-sized lithium iron phosphate particles and the small-sized lithium iron phosphate particles are mixed in a mass ratio of 1:2 to form a lithium iron phosphate positive electrode material. It can be understood that by mixing the large-sized lithium iron phosphate particles with the small-sized lithium iron phosphate particles, the final product can have good electrical conductivity (resistivity) and compaction density at the same time. Figure 8 When the ratio of large-sized lithium iron phosphate particles to small-sized lithium iron phosphate particles is about 1:2.0, it has the highest compaction density of 2.77g / cm 3 , and the lowest resistivity reaches 11.5Ω*cm.

[0042] In a specific application scenario, the grinding component 3 is suitable for the preliminary mixing and grinding operation of the raw materials in the mixing and grinding box 1, that is, the grinding component 3 can be used to fully mix and grind the raw materials added with the dispersant, so as to ensure the particle specifications of the raw materials after mixing. The rotating grinding operation between the grinding disc 301 and the inner grinding layer 304 can improve the effect of raw material grinding, thereby ensuring that the raw materials are more delicate after grinding, and avoiding the situation where uneven particles are caused by insufficient grinding of multiple substances, thereby affecting the subsequent production and processing process.

[0043] It should be noted that the gap between the grinding disc 301 and the inner grinding layer 304 decreases from top to bottom. The wider upper part can facilitate the normal entry of granular raw materials of different specifications, avoiding the situation where the raw materials are too large to enter the grinding area, thereby causing insufficient overall grinding. The narrower lower part can adjust the gap size according to actual needs, so as to obtain the finished product of raw material grinding of the required specifications.

[0044] Reference Figure 1 , Figure 2 and Figure 3 , the upper side of the mixing and grinding box 1 is connected with a box cover 4 by bolts, and a top frame 5 is arranged above the box cover 4. Two symmetrical sliding rods 6 are connected between the top frame 5 and the outer support plate 302 by bolts. The sliding rods 6 are slidably connected between the box cover 4, and a first motor 7 is connected to the top frame 5 by bolts, and the output end of the first motor 7 is connected to the top of the rotating shaft 308 by a coupling; the outside of the mixing and grinding box 1 is connected with an outer sleeve 8 by bolts, and two symmetrical supporting legs 9 are connected to the outer sleeve 8 by bolts, and a feeding pipe 10 and a plurality of equidistant auxiliary material pipes 11 are arranged on the box cover 4; a side frame 12 is arranged on one side of the mixing and grinding box 1, and a support 13 is connected to the side frame 12 by bolts, and a slide groove is opened on the support 13, and a connecting frame 14 is slidably connected to the inside of the slide groove, and one end of the connecting frame 14 is connected to the top frame 5 by bolts, and a hydraulic cylinder 15 is connected to the support 13 by bolts, and the top of the hydraulic cylinder 15 is connected to the lower side of the connecting frame 14 by bolts.

[0045] Specifically, the first motor 7 drives the rotating shaft 308 to rotate, so that the rotating shaft 308 drives the grinding disc 301 in the grinding table 2 to rotate, and performs the raw material grinding operation; during the grinding process, the hydraulic cylinder 15 drives the connecting frame 14 to move up and down at a uniform speed, so that the grinding table 2 moves longitudinally in the mixing and grinding box 1; iron phosphate, lithium source and carbon source are added from the feeding pipe 10, and additives, co-solvents and dispersants are added from the auxiliary material pipe 11; the hydraulic cylinder 15 is used to drive the grinding table 2 to move longitudinally, so that it can be lifted up and down at a uniform speed during the grinding process, so as to achieve the purpose of improving the mixing effect in the mixing and grinding box 1. At the same time, the up and down movement state can promote the raw materials in the mixing and grinding box 1 to enter the grinding table 2, and avoid the accumulation of raw materials in the mixing and grinding box 1, which causes the raw materials to enter the grinding table 2 unsmoothly, thereby reducing the grinding effect.

[0046] Reference Figure 2 , Figure 6 and Figure 7A rectangular groove is provided at the bottom of the mixing and grinding box 1, and a discharge valve 16 is connected to the inside of the rectangular groove by bolts. Three equidistant discharge pipes 17 are provided below the discharge valve 16, and the lower ends of the three discharge pipes 17 are connected to a delivery pipe 18 by bolts, and a discharge conveying assembly 19 is provided on the three delivery pipes 18; the discharge conveying assembly includes a shaft 1902 and a discharge bin 1903, and a cylindrical cavity is provided inside the delivery pipe 18, and the shaft 1902 is located inside the cylindrical cavity of the delivery pipe 18, one end of the shaft 1902 is rotatably connected to the inner wall of the cylindrical cavity by a bearing, and the other end of the shaft 1902 passes through the delivery pipe 18. A wheel disc 1906 is connected by bolts; a spiral feeding blade 1905 is connected to the outside of the shaft rod 1902 by bolts, the three feeding pipes 18 are all placed at an angle, and the lower bin 1903 is connected to the lower side of the feeding pipe 18 by bolts, and the lower bin 1903 is located at the upward end of the feeding pipe 18; the three feeding pipes 18 are connected to the same sleeve 1904 by bolts, and the sleeve 1904 is connected to the second motor 1901 by bolts, and the output end of the second motor 1901 is connected to a short shaft through a coupling, and the other end of the short shaft is connected to a driving disk by bolts, and a belt 1907 is arranged between the driving disk and the wheel disc 1906.

[0047] Specifically, after the mixing and grinding is completed, the discharge valve 16 is opened to allow the ground raw materials to enter the feed pipe 18 from the discharge pipe 17. At the same time, the discharge conveying component in the feed pipe 18 conveys the material upward. The process is: the ground raw materials enter the feed pipe 18 from top to bottom, the second motor 1901 uses the belt 1907 to drive the wheel 1906 to rotate, the shaft 1902 rotates, and the spiral feeding blade 1905 conveys the material in the feed pipe 18 upward. During the conveying process, the solid material will move upward until it is discharged from the discharge bin 1903, so as to be collected and transported for the subsequent drying process.

[0048] In a specific application scenario, the discharge conveying component 19 is suitable for the initial conveying of the ground material, that is, the discharge conveying component 19 can be used to perform preliminary solid-liquid separation and conveying of the ground material, and the inclined conveying pipe 18 and the spiral feeding blade 1905 can be used to convey the material obliquely upward and discharge it from the lower hopper 1903. A simple drainage operation can be performed during the process to avoid a large amount of water being mixed into the mixed and ground material, which is inconvenient for subsequent drying operations.

[0049] Reference Figure 1 , Figure 2 and Figure 6The lower ends of the three feed pipes 18 are connected to the same collecting pipe 20 by bolts. The collecting pipe 20 is located at one end of the feed pipe 18 away from the lower bin 1903, and the outside of the collecting pipe 20 is connected to a support frame 23 by bolts. A drain pipe 22 is provided at one end of the collecting pipe 20, and the drain pipe 22 is connected to the external conveying pipeline by a flange; a semicircular mounting groove is provided on the three conveying pipes, and the inside of the mounting groove is connected to a filtrate seat 21 by bolts, and the other end of the filtrate seat 21 passes through the pipe wall of the collecting pipe 20 and the inner cavity of the collecting pipe 20.

[0050] Specifically, during the process of the material being transported obliquely upward in the transport pipe, liquid will flow downward from the filtrate seat 21 and be collected in the liquid collecting pipe 20, and finally be discharged from the liquid drain pipe 22 for centralized recovery and treatment.

[0051] Working principle: When in use, add iron phosphate, lithium source and carbon source from the feeding tube 10, and add additives, co-solvent and dispersant from the auxiliary material tube 11;

[0052] After the raw materials are added into the mixing and grinding box 1, the device is started, and the first motor 7 drives the rotating shaft 308 to rotate, so that the rotating shaft 308 drives the grinding disc 301 in the grinding table 2 to rotate, and the raw materials are ground. At the same time, during the grinding process, the hydraulic cylinder 15 drives the connecting frame 14 to move up and down at a uniform speed, and the grinding table 2 moves longitudinally in the mixing and grinding box 1. The grinding process is as follows: as the rotating shaft 308 rotates, the raw materials in the mixing and grinding box 1 are rotated by the centripetal force of the rotation, and the raw materials enter the grinding table 2 from the feed port 305. Since the grinding disc 301 is always in a rotating state, the raw materials will flow downward after entering from the feed port 305 and be discharged from the discharge disc 306 at the bottom. In the process of flowing downward, the grinding disc 301 and the inner grinding layer 304 will continuously rotate and grind the raw materials;

[0053] After the mixing and grinding is completed, the discharge valve 16 is opened to allow the ground raw materials to enter the feed pipe 18 from the discharge pipe 17. At the same time, the discharge conveying component in the feed pipe 18 conveys the material upward. The process is: the ground raw materials enter the feed pipe 18 from top to bottom, and the second motor 1901 uses the belt 1907 to drive the wheel 1906 to rotate, the shaft 1902 rotates, and the spiral feeding blade 1905 conveys the material in the feed pipe 18 upward. During the transportation process, the solid material will move upward until it is discharged from the discharge bin 1903, so as to be collected and transported for the subsequent drying process. The liquid will flow downward from the filtrate seat 21 and be collected in the collecting pipe 20, and finally discharged from the drain pipe 22 for centralized recovery and treatment.

[0054] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for preparing high compacted density lithium iron phosphate, comprising a mixing and grinding box (1), characterized in that: A grinding table (2) is arranged inside the mixing and grinding box (1), and a grinding assembly (3) is arranged on the grinding table (2), the grinding assembly (3) comprises a grinding disc (301) and an outer support disc (302), and a grinding chamber (303) is opened inside the grinding table (2), the grinding disc (301) is located inside the grinding chamber (303), the upper and lower ends of the grinding disc (301) are movably connected to the inside of the grinding table (2), an inner grinding layer (304) is arranged inside the grinding chamber (303), the inner grinding layer (304) is funnel-shaped, and the grinding disc (301) is inverted truncated cone shape, and the grinding disc (301) and the inner grinding layer (304) are interlocked. The gap between the two decreases gradually from top to bottom; a plurality of circumferentially equidistant feed ports (305) are provided above the grinding table (2); the feed ports (305) are connected to the grinding chamber (303); a discharge tray (306) is provided on the lower side of the grinding table (2); the outer support tray (302) is located above the grinding table (2); three circumferentially equidistant limit rods (307) are fixedly connected to the lower side of the outer support tray (302) and the upper side of the grinding table (2); a circular hole is provided in the middle of the outer support tray (302); a rotating shaft (308) is movably connected to the inside of the circular hole; and the lower end of the rotating shaft (308) is fixedly connected to the upper side of the grinding disc (301); The mixing and grinding box (1) is fixedly connected to a box cover (4) on the upper side, and a top frame (5) is arranged above the box cover (4). Two symmetrical sliding rods (6) are fixedly connected between the top frame (5) and the outer support plate (302). The sliding rods (6) are movably connected to the box cover (4), and a first motor (7) is fixedly connected to the top frame (5). The output end of the first motor (7) is connected to the top of the rotating shaft (308) via a coupling; and a feeding pipe (1) is arranged on the box cover (4). 0) and a plurality of equally spaced auxiliary material pipes (11); a side frame (12) is provided on one side of the mixing and grinding box (1), a support (13) is fixedly connected to the side frame (12), a slide groove is provided on the support (13), a connecting frame (14) is movably connected inside the slide groove, one end of the connecting frame (14) is fixedly connected to the top frame (5), and a hydraulic cylinder (15) is fixedly connected to the support (13), and the top end of the hydraulic cylinder (15) is fixedly connected to the bottom side of the connecting frame (14).

2. The device for preparing high compaction density lithium iron phosphate according to claim 1, characterized in that: An external sleeve (8) is fixedly connected to the outside of the mixing and grinding box (1), and two symmetrical supporting legs (9) are fixedly connected to the external sleeve (8).

3. The device for preparing high compaction density lithium iron phosphate according to claim 2, characterized in that: The bottom of the mixing and grinding box (1) is provided with a rectangular groove, a discharge valve (16) is fixedly connected inside the rectangular groove, three discharge pipes (17) are arranged at equal distances below the discharge valve (16), the lower ends of the three discharge pipes (17) are fixedly connected to a feed pipe (18), and the three feed pipes (18) are provided with a discharge conveying assembly (19).

4. The device for preparing high compaction density lithium iron phosphate according to claim 3, characterized in that: The discharging conveying assembly (19) comprises a shaft (1902) and a lower bin (1903), and a cylindrical cavity is provided inside the conveying pipe (18). The shaft (1902) is located inside the cylindrical cavity of the conveying pipe (18), one end of the shaft (1902) is movably connected to the inner wall of the cylindrical cavity, and the other end of the shaft (1902) passes through the conveying pipe (18) and is fixedly connected to a wheel disc (1906).

5. The device for preparing high compaction density lithium iron phosphate according to claim 4, characterized in that: The outside of the shaft (1902) is fixedly connected to a spiral feeding blade (1905), the three feeding pipes (18) are all placed at an angle, and the lower feeding bin (1903) is fixedly connected to the lower side of the feeding pipe (18), and the lower feeding bin (1903) is located at the upward end of the feeding pipe (18).

6. The device for preparing high compaction density lithium iron phosphate according to claim 5, characterized in that: The three conveying pipes (18) are fixedly connected to a same sleeve (1904), the sleeve (1904) is fixedly connected to a second motor (1901), and the output end of the second motor (1901) is connected to a short shaft via a coupling, the other end of the short shaft is fixedly connected to a driving disk, and a belt (1907) is provided between the driving disk and the wheel (1906).

7. The device for preparing high compaction density lithium iron phosphate according to claim 6, characterized in that: The lower ends of the three feed pipes (18) are fixedly connected to the same liquid collecting pipe (20), the liquid collecting pipe (20) is located at one end of the feed pipe (18) away from the lower material bin (1903), and the outside of the liquid collecting pipe (20) is fixedly connected to a support frame (23), and a drain pipe (22) is provided at one end of the liquid collecting pipe (20), and the drain pipe (22) is connected to the external conveying pipeline via a flange.

8. A method for preparing high-density lithium iron phosphate, characterized in that: The following steps are involved: Using the preparation device as claimed in claim 1 to prepare large-sized lithium iron phosphate particles and small-sized lithium iron phosphate particles respectively; The large-sized lithium iron phosphate particles and the small-sized lithium iron phosphate particles are mixed in a mass ratio of 1:1.5-2.5 to form a lithium iron phosphate positive electrode material.

Images