An ultra-high pressure lithium iron phosphate material preparation device

Abstract

This invention discloses an ultra-high pressure lithium iron phosphate material preparation apparatus. First, a lithium source and an iron phosphate source are added to a solvent and stirred to obtain a mixture A. Then, a carbon source and an activator are mixed with a solvent to obtain a mixture B. Next, mixture A from step one and mixture B from step two are mixed and stirred to disperse, obtaining a complete precursor slurry C. Finally, the precursor slurry C from step three is first spray-dried, then sintered and pulverized to obtain the lithium iron phosphate material. The spray drying apparatus uses an additional suspended dry powder discharge pipe II to ensure that the material discharged through this pipe is completely dried. Simultaneously, the bottom discharge pipe is redirected to the slurry-powder separation pipe, separating the air-dried powder from the undried material. Furthermore, a sliding plate automatically triggers and impacts the baffle ring to loosen the attached material and impacts the loosened material in the bottom discharge pipe to discharge it.

Description

Technical Field

[0001] This invention relates to the field of lithium iron phosphate batteries, and more specifically to an ultra-high pressure lithium iron phosphate material preparation apparatus. Background Technology

[0002] In the preparation process of lithium iron phosphate materials, a crucial step is spray drying. Spray drying typically involves first atomizing the raw material using an atomizer, then drying the droplets with hot air, and finally separating the dried powder from the gas.

[0003] Currently, commonly used lithium iron phosphate spray drying equipment atomizes the slurry and sprays it from above. During its fall, it comes into full contact with hot air and dries, then turns into powder and falls to the bottom of the spray drying tank. It is then discharged through a pipe at the bottom of the tank, and finally, a cyclone separator separates the air and the material.

[0004] However, some problems urgently need to be solved in actual production: First, the atomized slurry adheres to the inner wall of the spray drying tank before it is dried into dry powder. The most common solution to this problem is to clean it regularly, but this not only consumes manpower and resources, but also interrupts and affects the production process.

[0005] Secondly, the slurry droplets after atomization may be too large, or multiple small droplets may combine into larger droplets in the air, or the droplets may not have sufficient contact with the hot air. As a result, some of the slurry that falls to the bottom of the tank may not be completely dried into powder, leading to suboptimal drying of the discharged material. The most common solutions to this problem are increasing the hot air temperature and pressure. However, temperature and pressure cannot be increased indiscriminately, as this would also increase production costs. Summary of the Invention

[0006] The purpose of this invention is to provide an ultra-high pressure lithium iron phosphate material preparation device. By additionally setting a suspended dry powder discharge pipe II, the material discharged through this pipe can be ensured to be completely dried. At the same time, the bottom discharge pipe is changed to lead to the slurry-powder separation pipe, so that the air-dried powder and the undried material are separated. In addition, the sliding plate automatically triggers and impacts the baffle ring to loosen the attached material and impacts the loose material in the bottom discharge pipe to discharge it.

[0007] An ultra-high pressure lithium iron phosphate material preparation device includes a spray drying tank, a slurry tank, a centrifugal atomizer, a hot air blower, a jet nozzle, and a cyclone separator. The spray drying tank is provided with a thermal drying reaction chamber. The centrifugal atomizer is fixedly installed on the top of the spray drying tank, and the spray outlet of the centrifugal atomizer is located in the thermal drying reaction chamber. The jet nozzle is fixedly connected to the lower half of the side wall of the spray drying tank, and the air outlet of the jet nozzle is located in the thermal drying reaction chamber and faces obliquely upward.

[0008] The slurry tank is connected to the centrifugal atomizer via a conveying pipe, the hot air blower is connected to the jet nozzle via a hot air pipe, and the cyclone separator is connected to the hot dry reaction chamber via a dry powder discharge pipe.

[0009] Preferably, the bottom of the spray drying tank is also connected to a bottom discharge pipe. The upper and lower ends of the bottom discharge pipe are respectively connected to the slurry-powder separation pipe and the thermal drying reaction chamber. The slurry-powder separation pipe is a vertical long pipe, with its upper end connected to the cyclone separator through the dry powder discharge pipe and its lower end connected to the centrifugal atomizer.

[0010] Preferably, the spray drying tank includes an outer shell wall, an inner shell wall, a baffle ring, and a sliding plate. The outer shell wall and the inner shell wall are fixedly connected by a connecting column to form the tank body of the spray drying tank, and a vacuum cavity is set between the outer shell wall and the inner shell wall. The baffle ring is fixedly connected to the inner shell wall, and the sliding plate is located in the heat drying reaction chamber above the baffle ring and is slidably connected to the inner shell wall.

[0011] The spray drying tank is also equipped with an air hammer. The air hammer output rod is located in the hot drying reaction chamber above the sliding plate. The air hammer is also connected to a hot air pipe. A trigger button is also provided above the sliding plate. The trigger button is connected to the outer shell wall. A vent is also provided on the outer shell wall, which connects the hot drying reaction chamber above the sliding plate to the outside atmosphere.

[0012] Preferably, the spray drying tank is fixedly connected to the support base, and a pump is also provided on the feed pipe between the slurry tank and the centrifugal atomizer.

[0013] Preferably, the upper and lower ends of the cyclone separator are respectively connected to an air discharge pipe and a discharge funnel, and a dry powder material box is provided below the outlet of the discharge funnel.

[0014] A method for preparing lithium iron phosphate material according to an ultra-high pressure lithium iron phosphate material preparation apparatus is characterized by:

[0015] Includes the following steps:

[0016] Step 1: Add the lithium source and the iron phosphorus source to the solvent and stir to mix, to obtain mixture A;

[0017] Step 2: Mix the carbon source and activator with a solvent to obtain mixture B;

[0018] Step 3: Mix the mixture A from Step 1 and the mixture B from Step 2, and stir to disperse them to obtain a complete precursor mixture slurry C;

[0019] Step 4: The precursor mixture C from Step 3 is first spray-dried, then sintered and pulverized to finally obtain lithium iron phosphate material.

[0020] Preferably, in step one, the molar ratio of lithium source to iron phosphorus source is 1 to 1.03;

[0021] In step two, the ratio of carbon source, activator and solvent is 6:1:93;

[0022] In step three, the final mixed slurry C has a phosphorus iron source and carbon source weight ratio of 1:0.08.

[0023] Preferably, in step two, the solvent is water, the activator is sodium dodecylbenzenesulfonate or sodium dodecyl sulfate, and the carbon source is glucose or polyethylene glycol.

[0024] The advantages of this invention are:

[0025] 1. An additional suspended dry powder discharge pipe is installed. This serves two purposes: firstly, to assist in ventilation, and secondly, because the material discharged upwards with the wind has essentially become dry powder. Therefore, the material discharged through this pipe is guaranteed to be completely dried and can be directly connected to the cyclone separator.

[0026] 2. Change the flow direction of the bottom discharge pipe at the bottom of the spray dryer. Instead of directly connecting to the cyclone separator, it first connects to the slurry-powder separation pipe. The slurry-powder separation pipe is a vertical pipe. Therefore, the undried material will fall into the centrifugal atomizer for re-drying due to gravity, while the air and the dry powder carried in the air will rise through the slurry-powder separation pipe and enter the dry powder discharge pipe one, which will directly enter the cyclone separator.

[0027] 3. Undried droplets may adhere to the inner wall of the spray drying tank and the inner wall of the bottom discharge pipe below. As a result, the bottom discharge pipe will become increasingly clogged, which will also make the exhaust increasingly difficult and cause the air pressure in the hot drying reaction chamber to increase. Eventually, the sliding plate will move up and touch the trigger button, triggering the air hammer to strike the sliding plate and make it move down rapidly. The sliding plate will move down rapidly and hit the baffle ring, which will not only loosen the attached material, but also cause the air pressure in the hot drying reaction chamber below to rise rapidly, which will then impact the loosened material in the bottom discharge pipe and make it be discharged.

[0028] 4. The spray drying tank is composed of an outer shell and an inner shell connected by connecting columns, and the gap between the two is set as a vacuum chamber. This not only greatly reduces heat dissipation, but also reduces the vibration of the outer shell when the sliding plate hits the baffle ring. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the spray drying process principle of the present invention;

[0030] Figure 2 This is a schematic diagram illustrating the preparation of the ultra-high pressure lithium iron phosphate material of the present invention;

[0031] Figure 3 This is a schematic diagram of the spray drying device of the present invention;

[0032] Figure 4 This is a front view of the spray drying apparatus of the present invention;

[0033] Figure 5 This is a schematic diagram of the internal structure of the spray drying tank in the spray drying apparatus of the present invention;

[0034] Figure 6 This is a schematic diagram of the internal structure of the upper part of the spray drying tank of the present invention;

[0035] Among them, 11. Spray drying tank, 12. Support base, 13. Slurry tank, 14. Pump, 15. Conveying pipe, 16. Centrifugal atomizer, 17. Hot air blower, 18. Hot air pipe, 19. Air hammer, 20. Air nozzle, 21. Bottom discharge pipe, 22. Slurry-powder separation pipe, 23. Dry powder discharge pipe one, 24. Dry powder discharge pipe two, 25. Cyclone separator, 26. Discharge funnel, 27. Air discharge pipe, 28. Dry powder material box, 101. Hot drying reaction chamber, 102. Outer shell wall, 103. Inner shell wall, 104. Connecting column, 105. Vacuum chamber, 106. Baffle ring, 107. Sliding plate, 108. Air hammer output rod, 109. Trigger button, 110. Vent hole. Detailed Implementation

[0036] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0037] like Figures 1 to 6 As shown, the present invention includes the following steps:

[0038] Step 1: Add lithium source and iron phosphorus source to solvent and stir to mix to obtain mixture A, wherein the molar ratio of lithium source and iron phosphorus source is 1 to 1.03;

[0039] Step 2: Mix glucose or polyethylene glycol, sodium dodecylbenzenesulfonate or sodium dodecyl sulfate and water solvent in a ratio of 6:1:93 to obtain mixture B;

[0040] Step 3: Mix the mixture A from Step 1 and the mixture B from Step 2, and stir to disperse them to obtain a complete precursor slurry C, in which the weight ratio of phosphorus iron source to carbon source is 1:0.08.

[0041] Step 4: The precursor mixture slurry C from Step 3 is first spray-dried using a spray drying device, then sintered and pulverized to finally obtain lithium iron phosphate material.

[0042] The spray drying device includes a spray drying tank 11, a slurry tank 14, a centrifugal atomizer 16, a hot air blower 17, a nozzle 20, and a cyclone separator 25. The spray drying tank 11 is provided with a thermal drying reaction chamber 101. The centrifugal atomizer 16 is fixedly installed on the top of the spray drying tank 11, and the spray outlet of the centrifugal atomizer 16 is located in the thermal drying reaction chamber 101. The nozzle 20 is fixedly connected to the lower half of the side wall of the spray drying tank 11, and the air outlet of the nozzle 20 is located in the thermal drying reaction chamber 101 and faces obliquely upward.

[0043] The slurry tank 14 is connected to the centrifugal atomizer 16 through the conveying pipe 15, the hot air blower 17 is connected to the jet nozzle 20 through the hot air pipe 18, and the cyclone separator 25 is connected to the hot dry reaction chamber 101 through the dry powder discharge pipe 24.

[0044] Specifically, the bottom of the spray drying tank 11 is also connected to a bottom discharge pipe 21. The upper and lower ends of the bottom discharge pipe 21 are connected to the slurry-powder separation pipe 22 and the thermal drying reaction chamber 101, respectively. The slurry-powder separation pipe 22 is a vertical long pipe. Its upper end is connected to the cyclone separator 25 through the dry powder discharge pipe 21, and its lower end is connected to the centrifugal atomizer 16.

[0045] The spray drying tank 11 is fixedly connected to the support base 12, and a pump 14 is also provided on the conveying pipe 15 between the slurry tank 14 and the centrifugal atomizer 16. The upper and lower ends of the cyclone separator 25 are respectively connected to an air discharge pipe 27 and a discharge funnel 26, and a dry powder material box 28 is provided below the outlet of the discharge funnel 26.

[0046] Another important feature is that the spray drying tank 11 includes an outer shell wall 102, an inner shell wall 103, a baffle ring 106, and a sliding plate 107. The outer shell wall 102 and the inner shell wall 103 are fixedly connected by a connecting column 104 to form the tank body of the spray drying tank 11. A vacuum chamber 105 is provided between the outer shell wall 102 and the inner shell wall 103. The baffle ring 106 is fixedly connected to the inner shell wall 103. The sliding plate 107 is located in the heat drying reaction chamber 101 above the baffle ring 106 and is slidably connected to the inner shell wall 103.

[0047] The spray drying tank 11 is also equipped with an air hammer 19. The air hammer output rod 108 of the air hammer 19 is located in the hot drying reaction chamber 101 above the sliding plate 107. The air hammer 19 is also connected to the hot air pipe 18. A trigger button 109 is also provided above the sliding plate 107. The trigger button 109 is connected to the outer shell wall 102. A vent hole 110 is also provided on the outer shell wall 102, which connects the hot drying reaction chamber 101 above the sliding plate 107 to the outside atmosphere.

[0048] Detailed implementation methods and principles:

[0049] After mixing and dispersing the materials in proportion, a complete precursor mixture slurry C is obtained. The mixture slurry C is placed in the slurry tank 14, and then the spray drying device is started for spray drying.

[0050] First, the slurry enters the centrifugal atomizer 16 through the feed pipe 15. The centrifugal atomizer 16 atomizes the slurry and sprays it from top to bottom into the hot drying reaction chamber 101 below the sliding plate 107. At the same time, the hot air blower 17 delivers high-speed hot air through the hot air pipe 18 and blows it from bottom to top into the hot drying reaction chamber 101 below the sliding plate 107 through the nozzle 20. Therefore, the atomized slurry droplets will come into full contact with the hot air and dry during the falling process.

[0051] Once the droplets are completely dried, they become dry powder. Some of this dry powder will be discharged directly into the cyclone separator 24 through the suspended dry powder discharge pipe 24 with the hot air. The material that can be discharged upward with the wind has basically become dry powder. Therefore, the material discharged through this pipe can be ensured to be completely dried. The other part of the dry powder will fall to the bottom of the spray drying tank 11 and enter the bottom discharge pipe 21.

[0052] In addition, some incompletely dried droplets will fall to the bottom of the spray drying tank 11 and enter the bottom discharge pipe 21. Due to the limited exhaust rate of the dry powder discharge pipe 24, air will also flow through the bottom discharge pipe 21 to the slurry-powder separation pipe 22, thus carrying a large portion of the dried dry powder and incompletely dried droplets into the slurry-powder separation pipe 22. Since the slurry-powder separation pipe 22 is a vertical pipe, the incompletely dried droplets will fall into the centrifugal atomizer 16 for re-drying due to gravity. The air and the dry powder carried in the air will rise through the slurry-powder separation pipe 22 into the dry powder discharge pipe 23, directly entering the cyclone separator 25. The diameters of the slurry-powder separation pipe 22 and the dry powder discharge pipe 23 are larger than the diameter of the bottom discharge pipe 21. Therefore, the air velocity will slow down after reaching the slurry-powder separation pipe 22, causing the droplets and dry powder to separate. This greatly improves the material drying effect.

[0053] Because undried droplets may adhere to the inner wall 103 of the spray drying tank 11 and the inner wall of the bottom discharge pipe 21 below, the bottom discharge pipe 21 will become increasingly clogged. This will also make the exhaust increasingly difficult, and cause the air pressure in the thermal drying reaction chamber 101 below the sliding plate 107 to increase. As a result, the sliding plate 107 will eventually move upward and touch the trigger button 109. The trigger button 109 will trigger the air hammer 19 to act, and the air hammer output rod 108 will hammer the sliding plate 107, causing it to move downward rapidly. The sliding plate 107 will eventually hit the baffle ring 106. The impact of the sliding plate 107 on the baffle ring 106 will loosen the attached material, and the rapid downward movement of the sliding plate 107 will act like a piston compressing air, causing the air pressure in the thermal drying reaction chamber 101 below to rise rapidly, forming a strong impact airflow. This impact airflow will impact the loosened material in the bottom discharge pipe 21 and expel it. Ultimately, it achieves automatic and periodic vibration to loosen and remove attached materials, greatly extending the cycle of manual cleaning.

[0054] After spray drying, air and material are separated by a cyclone separator 25. The material is then sintered and pulverized to obtain lithium iron phosphate material, which is then used to make lithium battery cathode material.

[0055] Based on the above, the present invention provides an additional suspended dry powder discharge pipe II, which ensures that the material discharged through this pipe is completely dried; at the same time, it changes the connection of the bottom discharge pipe to the slurry-powder separation pipe, so that the air-dried powder and the undried material are separated; in addition, the sliding plate automatically triggers and impacts the baffle ring to loosen the attached material, and impacts the loosened material in the bottom discharge pipe to discharge it.

[0056] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

Claims

1. A device for preparing ultra-high pressure lithium iron phosphate materials, characterized in that, The system includes a spray drying tank (11), a slurry tank (13), a centrifugal atomizer (16), a hot air blower (17), a nozzle (20), and a cyclone separator (25). The spray drying tank (11) is provided with a thermal drying reaction chamber (101). The centrifugal atomizer (16) is fixedly installed on the top of the spray drying tank (11), and the spray outlet of the centrifugal atomizer (16) is located in the thermal drying reaction chamber (101). The nozzle (20) is fixedly connected to the lower half of the side wall of the spray drying tank (11), and the air outlet of the nozzle (20) is located in the thermal drying reaction chamber (101) and faces obliquely upward. The slurry tank (13) is connected to the centrifugal atomizer (16) through the conveying pipe (15), the hot air blower (17) is connected to the jet nozzle (20) through the hot air pipe (18), and the cyclone separator (25) is connected to the hot dry reaction chamber (101) through the dry powder discharge pipe (24). The bottom of the spray drying tank (11) is also connected to a bottom discharge pipe (21). The upper and lower ends of the bottom discharge pipe (21) are connected to the slurry-powder separation pipe (22) and the hot drying reaction chamber (101) respectively. The slurry-powder separation pipe (22) is a vertical long pipe. Its upper end is connected to the cyclone separator (25) through the dry powder discharge pipe (23), and its lower end is connected to the centrifugal atomizer (16). The spray drying tank (11) includes an outer shell wall (102), an inner shell wall (103), a baffle ring (106), and a sliding plate (107). The outer shell wall (102) and the inner shell wall (103) are fixedly connected by a connecting column (104) to form the tank body of the spray drying tank (11). A vacuum chamber (105) is set between the outer shell wall (102) and the inner shell wall (103). The baffle ring (106) is fixedly connected to the inner shell wall (103). The sliding plate (107) is located in the heat drying reaction chamber (101) above the baffle ring (106), and the sliding plate (107) is slidably connected to the inner shell wall (103). The spray drying tank (11) is also equipped with an air hammer (19). The air hammer output rod (108) of the air hammer (19) is located in the hot drying reaction chamber (101) above the sliding plate (107). The air hammer (19) is also connected to the hot air pipe (18). A trigger button (109) is also provided above the sliding plate (107). The trigger button (109) is connected to the outer shell wall (102). A vent hole (110) is also provided on the outer shell wall (102). The vent hole (110) connects the hot drying reaction chamber (101) above the sliding plate (107) to the outside atmosphere.

2. The ultra-high pressure lithium iron phosphate material preparation apparatus according to claim 1, characterized in that: The spray drying tank (11) is fixedly connected to the support base (12), and a pump (14) is also provided on the conveying pipe (15) between the slurry tank (13) and the centrifugal atomizer (16).

3. The ultra-high pressure lithium iron phosphate material preparation apparatus according to claim 1, characterized in that: The upper and lower ends of the cyclone separator (25) are respectively connected to an air discharge pipe (27) and a discharge funnel (26), and a dry powder material box (28) is provided below the outlet of the discharge funnel (26).

4. A method for preparing lithium iron phosphate materials using the apparatus of claim 1, characterized in that: Includes the following steps: Step 1: Add the lithium source and the iron phosphorus source to the solvent and stir to mix, to obtain mixture A; Step 2: Mix the carbon source and activator with a solvent to obtain mixture B; Step 3: Mix the mixture A from Step 1 and the mixture B from Step 2, and stir to disperse them to obtain a complete precursor mixture slurry C; Step 4: The precursor mixture C from Step 3 is first spray-dried, then sintered and pulverized to finally obtain lithium iron phosphate material.

5. The method for preparing lithium iron phosphate material according to claim 4, characterized in that: In step one, the molar ratio of lithium source to iron phosphorus source is 1 to 1.03; In step two, the ratio of carbon source, activator and solvent is 6:1:93; In step three, the final mixed slurry C has a phosphorus iron source and carbon source weight ratio of 1:0.

08.

6. The method for preparing lithium iron phosphate material according to claim 4, characterized in that: In step two, the solvent is water, the activator is sodium dodecylbenzenesulfonate or sodium dodecyl sulfate, and the carbon source is glucose or polyethylene glycol.

Images