A lithium iron phosphate secondary crushing carbon coating system

Abstract

This invention discloses a lithium iron phosphate secondary pulverization and carbon coating system, belonging to the field of airflow pulverization technology. It includes an air heating component and a pulverization component, with the air heating component connected to the pulverization component and supplying heated air into the pulverization component to pulverize the material. This invention achieves "in-situ coating" through efficient in-situ coating, resulting in strong bonding and uniform distribution; it forms a high-quality conductive network, which can greatly reduce charge transfer resistance during lithium-ion insertion / extraction; and it significantly improves performance, providing a material basis for next-generation high-energy-density, long-cycle-life batteries. It integrates three key processes—secondary pulverization, dynamic coating, and preliminary mixing—into a continuous, closed process, realizing a shift from "intermittent" to "fully continuous" production. Continuous production effectively eliminates batch-to-batch quality fluctuations, significantly improving product consistency and stability.

Description

Technical Field

[0001] This invention belongs to the field of airflow pulverization technology, and particularly relates to a carbon coating system for secondary pulverization of lithium iron phosphate. Background Technology

[0002] Lithium iron phosphate (LFP) is a key cathode material in lithium-ion batteries, and its electrochemical performance directly affects the battery's energy density, rate performance, and cycle life. Traditional manufacturing processes typically involve a "sintering-pulverizing-mixing-secondary sintering" process, with the pulverizing step being crucial for obtaining active materials with suitable particle size and distribution. Currently, air jet milling technology is widely used, which uses a high-speed airflow to carry materials and pulverize them through collisions within a milling chamber. Carbon coating, a key process for improving the conductivity of LFP, is usually performed after the pulverizing step, involving the mechanical mixing of the pulverized material with additives such as carbon sources.

[0003] However, existing processes and technologies have the following obvious drawbacks: 1. Dispersed Process and Poor Coating Effect: Existing airflow milling and carbon coating steps are performed separately. During transportation and storage, the fresh surface of the milled material comes into contact with air, resulting in oxidation or moisture absorption, which reduces surface activity. When subsequent dry mechanical mixing is used for carbon coating, the carbon source struggles to form a strong and uniform bond with the reduced-activity material surface, leading to an incomplete conductive network and affecting material performance. To address this, we propose a lithium iron phosphate secondary milling and carbon coating system.

[0004] 2. Inability to dynamically add materials while the equipment is running: Traditional air jet mills are designed primarily for grinding single materials and do not have the ability to stably, accurately, and continuously add trace additives (such as liquid or powdered carbon sources, titanium, lithium, etc.) while the equipment is running (i.e. during the grinding process). Therefore, they cannot achieve a simultaneous grinding and coating process.

[0005] 3. Limited secondary particle size control: When secondary processing (such as adding supplementary coating agent) is carried out on materials that have undergone primary carbon coating ("first-burning material"), existing equipment has difficulty in effectively controlling the overall particle size of the finished product particles while forming a secondary coating layer, which can easily lead to particle agglomeration or excessively large particle size after coating. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a lithium iron phosphate secondary pulverization and carbon coating system.

[0007] To achieve the above objectives, the present invention proposes a lithium iron phosphate secondary pulverization and carbon coating system, comprising an air heating component and a pulverizing component. The air heating component is connected to the pulverizing component and sends heated air into the pulverizing component to pulverize the material.

[0008] Preferably, the air heating assembly includes a first compressed nitrogen inlet pipe and a compressed air inlet pipe. The bottom of the first compressed nitrogen inlet pipe and the compressed air inlet pipe are connected to a common pipe. A first shut-off valve is provided on the common pipe. A temperature sensor is provided on the left side of the first shut-off valve. A pneumatic valve is provided on the compressed air inlet pipe. An air heater is fixedly connected to one end of the common pipe. A filter is fixedly connected to the side of the air heater away from the pneumatic valve. A first pressure gauge is provided on the other side of the filter. A first thermometer is provided on the right side of the first pressure gauge. A check valve is provided on the right side of the first thermometer.

[0009] Preferably, the crushing assembly includes a support, a crushing chamber is provided on the top of the support, a classifying wheel motor is provided on one side of the crushing chamber, a classifying wheel is provided inside the crushing chamber, a shaft extending out of the crushing chamber is fixedly connected to one end of the classifying wheel, a pulley is fixedly connected to one side of the classifying wheel motor and the shaft, a belt is sleeved on the outside of the pulley, nozzles are provided on both sides of the crushing chamber, and an air bag is connected to the nozzle.

[0010] Preferably, material bags are provided on both sides of the crushing chamber, and a stainless steel pipe is provided on one side of the material bag on the right side. A second compressed nitrogen inlet pipe is provided on the stainless steel pipe, and a second thermometer, a second pressure gauge and a flow meter are provided on the stainless steel pipe. A screw conveyor is provided on the side of the flow meter away from the second pressure gauge, and a small material hopper is provided on the screw conveyor.

[0011] Preferably, a third compressed nitrogen inlet pipe is provided on one side of the pulverizing chamber, and a first shut-off valve, a first solenoid valve and a third pressure gauge are sequentially provided on the third compressed nitrogen inlet pipe.

[0012] Preferably, the top of the grinding chamber is provided with a grinding chamber cover plate, the front of the grinding chamber is provided with a first observation window, and one side of the first observation window is provided with an inspection port.

[0013] Preferably, a second observation window is provided on the lower front side of the crushing chamber, and a discharge port is provided at the bottom of the crushing chamber.

[0014] Preferably, the top of the crushing chamber is provided with a feed pipe, and the feed pipe is sequentially provided with a fourth pressure gauge, a second solenoid valve and a second shut-off valve.

[0015] The lithium iron phosphate secondary pulverization and carbon coating system proposed in this invention can bring the following beneficial effects: In-situ high-efficiency coating: Carbon sources and other additives are added in real time and precisely during the crushing process through the screw conveyor and small hopper components. The freshly crushed material particles have extremely high freshness and surface activity, and the additives can immediately come into contact with them to achieve "in-situ coating", with strong binding force and uniform distribution. Formation of a high-quality conductive network: This in-situ coating process facilitates the formation of a complete, dense, and thin conductive carbon layer during subsequent sintering, which can greatly reduce the charge transfer impedance during the lithium-ion insertion / extraction process; Clear performance improvement: This technology directly optimizes the specific capacity, rate performance and cycle stability of lithium iron phosphate cathode materials, providing a material basis for the next generation of high energy density and long cycle life batteries; This system innovatively integrates three key processes—secondary crushing, dynamic coating, and preliminary mixing—into a continuous, closed process, realizing the transformation from "intermittent" to "fully continuous" production. Continuous production effectively eliminates quality fluctuations between batches, significantly improving product consistency and stability. Attached Figure Description

[0016] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0017] In the attached diagram: Figure 1 This is a schematic diagram of the overall assembly structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the crushing component structure of the present invention.

[0019] In the diagram: 1. Air heating assembly; 101. First compressed nitrogen inlet pipe; 102. Compressed air inlet pipe; 103. First shut-off valve; 104. Temperature sensor; 105. Pneumatic valve; 106. Air heater; 107. Filter; 108. First pressure gauge; 109. First thermometer; 110. Check valve; 2. Grinding assembly; 201. Support; 202. Grinding chamber; 203. Grinding chamber cover; 204. Classifying wheel motor; 205. Classifying wheel; 206. Shaft; 207. Belt; 208. First observation window; 2. 09 Inspection port, 210 Second observation window, 211 Nozzle, 212 Air tank, 213 Material bag, 214 Second compressed nitrogen inlet pipe, 215 Second thermometer, 216 Second pressure gauge, 217 Flow meter, 218 Screw conveyor, 219 Small hopper, 220 Third compressed nitrogen inlet pipe, 221 First shut-off valve, 222 First solenoid valve, 223 Third pressure gauge, 224 Feed pipe, 225 Fourth pressure gauge, 226 Second solenoid valve, 227 Second shut-off valve, 228 Discharge port. Detailed Implementation

[0020] To more clearly illustrate the overall concept of the present invention, a detailed description will be provided below with reference to the accompanying drawings and examples.

[0021] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0025] like Figures 1-2As shown, an embodiment of the present invention proposes a lithium iron phosphate secondary crushing and carbon coating system, including an air heating component 1 and a crushing component 2. The air heating component 1 is connected to the crushing component 2 and sends heated air into the crushing component 2 to crush the material.

[0026] like Figure 1 As shown, the air heating assembly 1 includes a first compressed nitrogen inlet pipe 101 and a compressed air inlet pipe 102. The bottom of the first compressed nitrogen inlet pipe 101 and the compressed air inlet pipe 102 are connected to a common pipe. A first shut-off valve 103 is provided on the common pipe. A temperature sensor 104 is provided on the left side of the first shut-off valve 103. A pneumatic valve 105 is provided on the compressed air inlet pipe 102. An air heater 106 is fixedly connected to one end of the common pipe. A filter 107 is fixedly connected to the side of the air heater 106 away from the pneumatic valve 105. A first pressure gauge 108 is provided on the other side of the filter 107. A first thermometer 109 is provided on the right side of the first pressure gauge 108. A check valve 110 is provided on the right side of the first thermometer 109.

[0027] like Figure 2 As shown, the crushing assembly 2 includes a support 201, a crushing chamber 202 is provided on the top of the support 201, a classifying wheel motor 204 is provided on one side of the crushing chamber 202, a classifying wheel 205 is provided inside the crushing chamber 202, a shaft 206 extending out of the crushing chamber 202 is fixedly connected to one end of the classifying wheel 205, a pulley is fixedly connected to one side of both the classifying wheel motor 204 and the shaft 206, a belt 207 is sleeved on the outside of the pulley, and nozzles 211 are provided on both sides of the crushing chamber 202, with an air bag 212 connected to the nozzle 211.

[0028] like Figure 2 As shown, the crushing chamber 202 is provided with material bags 213 on both sides. A stainless steel pipe is provided on one side of the material bag 213 on the right side. A second compressed nitrogen inlet pipe 214 is provided on the stainless steel pipe. A second thermometer 215, a second pressure gauge 216 and a flow meter 217 are provided on the stainless steel pipe. A screw conveyor 218 is provided on the side of the flow meter 217 away from the second pressure gauge 216. A small hopper 219 is provided on the screw conveyor 218.

[0029] like Figure 1 As shown, a third compressed nitrogen inlet pipe 220 is provided on one side of the crushing chamber 202. A first shut-off valve 211, a first solenoid valve 222 and a third pressure gauge 223 are sequentially provided on the third compressed nitrogen inlet pipe 220.

[0030] like Figure 1 As shown, the top of the crushing chamber 202 is provided with a crushing chamber cover plate 203, the front of the crushing chamber 202 is provided with a first observation window 208, and one side of the first observation window 208 is provided with an inspection port 209.

[0031] like Figure 1 As shown, a second observation window 210 is provided on the lower front side of the crushing chamber 202, and a discharge port 228 is provided at the bottom of the crushing chamber 202.

[0032] like Figure 1 As shown, the top of the crushing chamber 202 is provided with a feed pipe 224, and the feed pipe 224 is provided with a fourth pressure gauge 225, a second solenoid valve 226 and a second shut-off valve 227 in sequence.

[0033] Working principle: When starting the system, inert gas or air can be selected as the pulverizing medium according to process requirements. When air is selected, open the pneumatic valve 105 on the compressed air inlet pipe 102. When nitrogen is selected, use the first compressed nitrogen inlet pipe 101.

[0034] The gas enters the air heater 106 through a common pipe and is heated to a set temperature. It then passes through the filter 107 to remove impurities, in order to meet the requirements of specific materials for airflow dryness or chemical reactivity. The gas temperature and pressure are monitored by the temperature sensor 104, the first thermometer 109, and the first pressure gauge 108, respectively.

[0035] The purified hot gas is transported to the crushing component 2 and ejected through nozzles 211 distributed on both sides of the crushing chamber 202, forming a high-speed flow field inside the chamber.

[0036] The lithium iron phosphate main material to be pulverized (such as "first-burn material") is added to the pulverizing chamber through the feed pipe 224 and is pulverized by collision with each other due to the impact of high-speed airflow.

[0037] Meanwhile, the carbon source and other additives (liquid or micro powder) pre-placed in the small hopper 219 are precisely metered and conveyed by the screw conveyor 218 under the carrying and pushing of the second compressed nitrogen (provided through the second compressed nitrogen inlet pipe 214). The flow meter 217 monitors the carrier gas flow rate in real time to ensure stable additive feeding.

[0038] The additives fed from the screw conveyor 218 immediately come into contact with the fresh, fine lithium iron phosphate particles with highly active surfaces generated during the crushing process upon entering the crushing chamber. The high-speed collision and turbulent environment of the materials promote the uniform coating of the additives on the surface of the new particles, achieving simultaneous completion of secondary crushing and carbon coating.

[0039] The grading wheel 205, driven by the grading wheel motor 204 through the belt 207 and the shaft 206, rotates at high speed, creating a forced centrifugal force field in its vicinity.

[0040] The particles move under the influence of airflow in the crushing and classifying zones. Fine particles that meet the particle size requirements overcome centrifugal force under the action of airflow and pass through the classifying wheel into the collection system.

[0041] Coarse particles that do not meet the particle size requirements are thrown against the grinding chamber wall by strong centrifugal force and descend along the wall, re-entering the nozzle spray zone below to be further crushed by high-speed airflow until the particle size meets the requirements. This classification process ensures that the final product particles have a concentrated and uniform particle size distribution.

[0042] Before the end of batch production or material change, nitrogen is introduced through the third compressed nitrogen inlet pipe 220 to purge the crushing chamber 202 and pipelines to ensure no residual material and avoid cross-contamination.

[0043] The qualified material, after being fully crushed and coated and reaching the set fineness, is finally discharged from the discharge port 228 at the bottom of the crushing chamber 202 with the airflow, and enters downstream equipment such as cyclone separators and bag filters for gas-solid separation and collection.

[0044] Operators can observe the situation inside the chamber in real time through the first observation window 208 and the second observation window 210. All pressure gauges, thermometers and valves ensure that the system operates safely and stably under preset parameters. The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0045] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A lithium iron phosphate secondary pulverization and carbon coating system, characterized in that, It includes an air heating component (1) and a crushing component (2). The air heating component (1) is connected to the crushing component (2) and sends heated air into the crushing component (2) to crush the material.

2. The lithium iron phosphate secondary pulverization and carbon coating system according to claim 1, characterized in that, The air heating assembly (1) includes a first compressed nitrogen inlet pipe (101) and a compressed air inlet pipe (102). The bottom of the first compressed nitrogen inlet pipe (101) and the compressed air inlet pipe (102) are connected to a common pipe. A first shut-off valve (103) is provided on the common pipe. A temperature sensor (104) is provided on the left side of the first shut-off valve (103). A pneumatic valve (105) is provided on the compressed air inlet pipe (102). An air heater (106) is fixedly connected to one end of the common pipe. A filter (107) is fixedly connected to the side of the air heater (106) away from the pneumatic valve (105). A first pressure gauge (108) is provided on the other side of the filter (107). A first thermometer (109) is provided on the right side of the first pressure gauge (108). A check valve (110) is provided on the right side of the first thermometer (109).

3. The lithium iron phosphate secondary pulverization and carbon coating system according to claim 1, characterized in that, The crushing assembly (2) includes a support (201), a crushing chamber (202) is provided on the top of the support (201), a classifying wheel motor (204) is provided on one side of the crushing chamber (202), a classifying wheel (205) is provided inside the crushing chamber (202), a shaft (206) extending out of the crushing chamber (202) is fixedly connected to one end of the classifying wheel (205), a pulley is fixedly connected to one side of both the classifying wheel motor (204) and the shaft (206), a belt (207) is sleeved on the outside of the pulley, and nozzles (211) are provided on both sides of the crushing chamber (202), and an air bag (212) is connected to the nozzle (211).

4. The lithium iron phosphate secondary pulverization and carbon coating system according to claim 3, characterized in that, The crushing chamber (202) is provided with material bags (213) on both sides. A stainless steel pipe is provided on one side of the material bag (213) on the right side. A second compressed nitrogen inlet pipe (214) is provided on the stainless steel pipe. A second thermometer (215), a second pressure gauge (216) and a flow meter (217) are provided on the stainless steel pipe. A screw conveyor (218) is provided on the side of the flow meter (217) away from the second pressure gauge (216). A small hopper (219) is provided on the screw conveyor (218).

5. The lithium iron phosphate secondary pulverization and carbon coating system according to claim 3, characterized in that, The pulverizing chamber (202) is provided with a third compressed nitrogen inlet pipe (220) on one side, and the third compressed nitrogen inlet pipe (220) is provided with a first shut-off valve (211), a first solenoid valve (222) and a third pressure gauge (223) in sequence.

6. The lithium iron phosphate secondary pulverization and carbon coating system according to claim 3, characterized in that, The top of the crushing chamber (202) is provided with a crushing chamber cover plate (203), and the front of the crushing chamber (202) is provided with a first observation window (208), and an inspection port (209) is provided on one side of the first observation window (208).

7. The lithium iron phosphate secondary pulverization and carbon coating system according to claim 3, characterized in that, The crushing chamber (202) has a second observation window (210) on the lower front side and a discharge port (228) at the bottom.

8. The lithium iron phosphate secondary pulverization and carbon coating system according to claim 3, characterized in that, The top of the crushing chamber (202) is provided with a feed pipe (224), and the feed pipe (224) is provided with a fourth pressure gauge (225), a second solenoid valve (226) and a second shut-off valve (227) in sequence.

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