A device for rapidly synthesizing a uniform carbon-coated lithium iron phosphate anode material

Abstract

The device for rapidly synthesizing uniform carbon-coated lithium iron phosphate anode material comprises a lithium iron phosphate precursor bin, a material temporary storage tank, a material nitrogen sending tank, a high-temperature fluidized bed device and a bag type collector; the material temporary storage tank inlet is connected with the lithium iron phosphate precursor bin discharge port, the material nitrogen sending tank inlet is connected with the material temporary storage tank outlet, and the material nitrogen sending tank outlet is connected with a nitrogen gas interface; the high-temperature fluidized bed device comprises a high-temperature furnace body and a spraying device, the high-temperature furnace body bottom is provided with a nitrogen gas interface, the high-temperature furnace body top outlet is connected with the material cooler inlet, and the material cooler outlet is connected with the bag type collector; the spraying device comprises a spraying pipe network, the spraying pipe network inlet is connected with a gaseous carbon source, and the multiple spraying pipe network outlets are all connected with gas carbon source nozzles. The device effectively solves the long synthesis cycle difficulty of the existing lithium iron phosphate, integrates feeding, synthesis reaction, carbon coating, material conveying and material collecting, has simple preparation process and is suitable for industrialization amplification.

Description

Technical Field

[0001] This utility model relates to the field of battery materials, specifically to an apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode materials. Background Technology

[0002] Lithium iron phosphate (LiFePO4) is a cathode material used in lithium-ion batteries. Its key characteristics are that it does not contain precious elements such as cobalt and nickel, resulting in lower raw material costs. Furthermore, phosphorus, iron, and lithium are abundant resources in the Earth's crust, sufficient to meet market demand exceeding one million tons annually. As a cathode material, lithium iron phosphate offers a moderate operating voltage (3.2V), high specific capacity (170mAh / g), high discharge power, fast charging capability, long cycle life, and good stability under high temperature and high-heat environments.

[0003] There are two main processes for preparing lithium iron phosphate (LFP) materials: solid-phase and liquid-phase methods. Solid-phase methods include carbothermal reduction and high-temperature solid-phase methods; liquid-phase methods include hydrothermal methods, sol-gel methods, and co-precipitation methods. High-temperature solid-phase methods, due to their low equipment requirements, mature technology, and ease of industrialization, have become the mainstream technology for cathode material synthesis in recent years, thanks to continuous advancements in synthesis process control technology that enable precise control of particle morphology, composition, and size.

[0004] The most widely used lithium iron phosphate (LFP) synthesis equipment in the cathode material industry consists of roller kilns and rotary kilns. Roller kilns are automated systems comprised of preheating, synthesis, cooling, and external circulation sections. During production, the saggers move along the rollers, requiring precise control of their speed and position. Errors or improper operation can lead to roller breakage and halt the synthesis line. Rotary kilns transport materials at high temperatures through an inclined converter. The constant friction between the material and the converter wall during rotation can damage the carbon coating. Both roller kilns and rotary kilns offer advantages such as high capacity and ease of industrialization; however, they also suffer from drawbacks including long processes, high energy consumption, and long material synthesis cycles.

[0005] The poor conductivity of lithium iron phosphate cathode materials is a major drawback. Most companies choose to coat the surface of lithium iron phosphate with a layer of carbon to improve the conductivity of the material. The carbon source is mainly organic carbon source such as glucose, sucrose, and polyethylene glycol, which is formed by coking in a roller kiln. However, the material is in a relatively static state in the sagger, which leads to uneven carbon coating of lithium iron phosphate cathode material in the upper and lower parts of the sagger, which needs to be solved. Summary of the Invention

[0006] To address the shortcomings of the aforementioned background technology, this utility model proposes a device for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode materials. This device effectively solves the problems of long equipment processes, high energy consumption, and long material synthesis cycles, effectively reducing production costs. Furthermore, the preparation process is simple and suitable for industrial scale-up.

[0007] The technical solution of this utility model is as follows: it includes a lithium iron phosphate precursor silo for storing nano-lithium iron phosphate precursors, a material storage tank, a material nitrogen sending tank, a high-temperature fluidized bed device, and a bag collector; the outlet of the lithium iron phosphate precursor silo is connected to the inlet of the material storage tank via a pneumatic valve A, the outlet of the material storage tank is connected to the inlet of the material nitrogen sending tank via a pneumatic valve B, and the outlet of the material nitrogen sending tank is connected to the nitrogen interface of the high-temperature fluidized bed device; the high-temperature fluidized bed device includes a high-temperature furnace body and a spraying device for spraying carbon-containing gas into the high-temperature furnace body; the bottom of the high-temperature furnace body is provided with a nitrogen interface for connecting to a nitrogen source, the top outlet of the high-temperature furnace body is connected to the inlet of a material cooler, and the outlet of the material cooler is connected to the bag collector; the spraying device includes a spraying pipe network, the inlet of the spraying pipe network located outside the high-temperature furnace body is connected to a gaseous carbon source, and the spraying pipe network located inside the high-temperature furnace body has multiple outlets, each of which is connected to a gaseous carbon source nozzle.

[0008] The gas carbon source nozzles are divided into two symmetrically arranged groups of gas carbon source nozzles. Each group of gas carbon source nozzles includes three or more gas carbon source nozzles. The gas carbon source nozzles in each group are equidistantly distributed along the direction parallel to the axial direction of the high-temperature furnace body.

[0009] The spraying network includes two main vertical pipes, the upper ends of which are connected to a gaseous carbon source via pipes. A pulse valve C is installed on the pipe at the outlet of the gaseous carbon source. There are three or more horizontal branch pipes that are vertically connected from top to bottom along the inner side of each main vertical pipe. The spacing between each horizontal branch pipe is the same. The gaseous carbon source nozzle is installed at the end of the horizontal branch pipe. The axial direction of both main vertical pipes is parallel to the axial direction of the high-temperature furnace body.

[0010] The carbon-containing gas in the gaseous carbon source is one or more of methane, acetylene, ammonia, hydrogen, and silicon tetrachloride.

[0011] The lower part of the lithium iron phosphate precursor silo is equipped with a weighing module for quantitative material release. The weighing module, pneumatic valve A, pneumatic valve B, and pulse valve C are all connected to a controller.

[0012] Both the gaseous carbon source nitrogen and the gas source outlet pipeline are equipped with flow meters and pressure gauges, which are connected to the controller.

[0013] The lithium iron phosphate precursor silo is connected to a material storage tank via a screw feeder.

[0014] The bag collector has a material collection bin at the bottom.

[0015] This invention involves feeding a measured amount of lithium iron phosphate precursor yellow material into a high-temperature fluidized bed reactor via nitrogen gas. By adjusting the nitrogen flow rate and pressure, the material is suspended in the reactor and reaches a dynamic equilibrium. Under high temperature, the lithium iron phosphate precursor rapidly nucleates and grows to form a highly crystalline lithium iron phosphate cathode material. During the synthesis process, atomized carbon source is sprayed periodically to quickly form a uniformly thick carbon coating layer. After synthesis, the material is transported to a baghouse receiver for gas-solid separation after the nitrogen flow rate is adjusted again, thereby collecting the lithium iron phosphate material.

[0016] This invention integrates feeding, synthesis reaction, carbon coating, material conveying, and material collection into a single process, with multiple steps carried out continuously throughout. By adjusting the nitrogen flow rate, this invention achieves dynamic equilibrium and material conveying within the furnace chamber by forming a fluidized bed of material, thus facilitating material transport and transfer. Its ingenious structural design ensures good compatibility with the reaction chamber and the material bag collector, enhancing the flexibility of material handling. Attached Figure Description

[0017] To more clearly illustrate the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the device of this utility model;

[0019] Figure 2 yes Figure 1 A magnified view of a portion of the image. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] Figure 1 , 2 This utility model includes a lithium iron phosphate precursor silo 3, a material storage tank 7 below the lithium iron phosphate precursor silo 3, a material nitrogen delivery tank 8, a high-temperature fluidized bed device 1, a material cooler 9, and a bag collector 4. A weighing module and valve A are installed between the lithium iron phosphate precursor silo 3 and the material storage tank 7 to precisely control the weight of the material being released. A valve B is installed between the material storage tank 7 and the material nitrogen delivery tank 8.

[0022] Valves A and B, configured between the lithium iron phosphate precursor silo 3 and the nitrogen gas delivery tank 8, are interconnected by an automatic control system to accurately control the feeding and delivery cycle. The precursor yellow material in the lithium iron phosphate precursor silo 3 has a particle size of 12-40 micrometers, preferably 20-30 micrometers. The weighing module 10, pneumatic valves A and B, and pulse valve C are all connected to the controller. Flow meters and pressure gauges are installed on the gaseous carbon source nitrogen and the gas source outlet pipelines, and these flow meters and pressure gauges are connected to the controller.

[0023] The high-temperature fluidized bed equipment 1 consists of a high-temperature furnace body, a gaseous carbon source nozzle 5, and a nitrogen inlet. The gaseous carbon source is pressurized and delivered to the gaseous carbon source nozzle (i.e., atomizing nozzle) 5 inside the high-temperature fluidized bed equipment 1, achieving uniform spraying onto the material surface. The gaseous carbon source includes one or more of methane, acetylene, ammonia, hydrogen, and silicon tetrachloride. The furnace body inside the high-temperature fluidized bed equipment 1 is equipped with a high-temperature heating module capable of achieving a maximum temperature of 1700℃. The set temperature of the high-temperature fluidized bed is between 600-1500℃, preferably 800-1300℃. A nitrogen source is located at the bottom of the furnace body inside the high-temperature fluidized bed equipment 1. The material is pneumatically fed into the furnace body, and nitrogen supplementation achieves a suspended distribution of the material within the furnace body, achieving dynamic equilibrium. The nitrogen supplementation pressure is adjusted according to the particle size and distribution of the precursor material, preferably within a range of 0.1-0.3 MPa. The material cooler 9 cools the material by exchanging heat between chilled water and the high-temperature material in the coil. The temperature after cooling is <95℃, preferably 60-90℃. The bag collector 4 is equipped with a bag filter to separate the material and gas, thus collecting the lithium iron phosphate cathode material.

[0024] The spraying device consists of a spraying pipe network and gas carbon source nozzles 5. The spraying pipe network includes two main vertical pipes, the upper ends of which are connected to a gaseous carbon source via pipes 2. A pulse valve C is installed on the pipe at the outlet of the gaseous carbon source. There are three or more horizontal branch pipes that are vertically connected from top to bottom along the inner side of each main vertical pipe. The spacing between each horizontal branch pipe is the same. The gas carbon source nozzles 5 are installed at the ends of the horizontal branch pipes. The axial direction of the two main vertical pipes is parallel to the axial direction of the high-temperature furnace body.

[0025] Example 1: An apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode materials includes a material storage tank 7 below a lithium iron phosphate precursor silo 3, a nitrogen gas delivery tank 8, a high-temperature fluidized bed device 1, and a bag collector 4. This invention uses a 2-cubic-meter lithium iron phosphate precursor silo 3 to store nano-lithium iron phosphate precursors. A pneumatic valve is installed in a pipe below the silo, connecting the silo and the material storage tank 7. The effective volume of the storage tank is 3L. A pneumatic valve is installed between the material storage tank 7 and the nitrogen sending tank 8. The sending chamber has a volume of 2L, and the sending gas is nitrogen with a purity of 99.99%. After the material is quantitatively fed into the sending chamber, it is sent to the bottom of the high-temperature fluidized bed equipment by nitrogen. After nitrogen is replenished, the material gradually suspends in the fluidized bed equipment cavity under nitrogen pressure. The high-temperature fluidized bed equipment 1 is a hollow vertical furnace heated to 1300℃ by resistance wire. Under the action of high temperature, the nano-lithium iron phosphate precursor material rapidly nucleates and grows to form a highly crystalline lithium iron phosphate cathode material. The synthesis time is 30 minutes. During the lithium iron phosphate synthesis process, a gaseous nitrogen source is introduced at regular intervals and sprayed evenly into the lithium iron phosphate cathode material through 10 atomizing nozzles evenly arranged in the high-temperature fluidized bed equipment 1, quickly forming a carbon coating layer of uniform thickness. After the reaction synthesis, the nitrogen flow rate at the bottom of the high-temperature fluidized bed equipment is increased. The prepared lithium iron phosphate cathode material is carried away by the nitrogen and transported to the bag collector ④4. After bag filtration, the nitrogen is separated from the material. The material is collected at the bottom of the bag filter, thus completing the synthesis of lithium iron phosphate.

[0026] Example 2: This invention includes a 1 cubic meter lithium iron phosphate precursor silo 3 for storing nano-lithium iron phosphate precursors. A pneumatic valve is installed on a pipe below the lithium iron phosphate precursor silo 3, connecting the silo to a material storage tank 7. The effective volume of the storage tank is 2L. The sending chamber has a volume of 1L, and the sending gas is nitrogen with a purity of 99.99%. After the material is quantitatively fed into the sending chamber, it is sent to the bottom of the high-temperature fluidized bed equipment by nitrogen. After nitrogen is replenished, the material gradually suspends in the fluidized bed equipment cavity under nitrogen pressure. The high-temperature fluidized bed equipment 1 is a hollow vertical furnace heated to 1250℃ by resistance wire. Under the action of high temperature, the nano-lithium iron phosphate precursor material rapidly nucleates and grows to form a highly crystalline lithium iron phosphate cathode material. The synthesis time is 20 minutes. During the synthesis of lithium iron phosphate, a gaseous nitrogen source is periodically introduced and sprayed evenly onto the lithium iron phosphate cathode material through 10 atomizing nozzles evenly arranged within the high-temperature fluidized bed equipment 1, rapidly forming a uniformly thick carbon coating layer. After the reaction synthesis, the nitrogen flow rate at the bottom of the high-temperature fluidized bed equipment is increased, and the prepared lithium iron phosphate cathode material is carried away by the nitrogen gas and transported to the bag collector 4. After bag filtration, the nitrogen gas is separated from the material, and the material is collected at the bottom of the bag filter, completing the synthesis of lithium iron phosphate.

[0027] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode material, characterized in that: The system includes a lithium iron phosphate precursor silo (3) for storing nano-lithium iron phosphate precursors, a material storage tank (7), a material nitrogen delivery tank (8), a high-temperature fluidized bed device (1), and a bag collector (4); the outlet of the lithium iron phosphate precursor silo (3) is connected to the inlet of the material storage tank (7) via a pneumatic valve A, the outlet of the material storage tank (7) is connected to the inlet of the material nitrogen delivery tank (8) via a pneumatic valve B, and the outlet of the material nitrogen delivery tank (8) is connected to the nitrogen interface of the high-temperature fluidized bed device (1); The high-temperature fluidized bed equipment (1) includes a high-temperature furnace body and a spraying device for spraying carbon-containing gas into the high-temperature furnace body. The bottom of the high-temperature furnace body is provided with a nitrogen interface for connecting to a nitrogen source. The top outlet of the high-temperature furnace body is connected to the inlet of a material cooler (9), and the outlet of the material cooler (9) is connected to a bag collector (4). The spraying device includes a spraying pipe network. The inlet of the spraying pipe network located outside the high-temperature furnace body is connected to a gaseous carbon source. The spraying pipe network located inside the high-temperature furnace body has multiple outlets, and each outlet is connected to a gaseous carbon source nozzle (5).

2. The apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode material according to claim 1, characterized in that: The gas carbon source nozzles (5) are divided into two groups of gas carbon source nozzles arranged symmetrically. Each group of gas carbon source nozzles includes three gas carbon source nozzles (5). The gas carbon source nozzles (5) in each group of gas carbon source nozzles are equidistantly distributed along the direction parallel to the axial direction of the high-temperature furnace body.

3. The apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode material according to claim 2, characterized in that: The spraying network includes two main vertical pipes, the upper ends of which are connected to a gaseous carbon source via pipe (2). A pulse valve C is installed on the pipe at the outlet of the gaseous carbon source. There are three or more horizontal branch pipes that are vertically connected from top to bottom along the inner side of each main vertical pipe. The spacing between each horizontal branch pipe is the same. The gaseous carbon source nozzle (5) is installed at the end of the horizontal branch pipe. The axial direction of the two main vertical pipes is parallel to the axial direction of the high-temperature furnace body.

4. The apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode material according to claim 3, characterized in that: The carbon-containing gas in the gaseous carbon source is one or more of methane, acetylene, ammonia, hydrogen, and silicon tetrachloride.

5. The apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode material according to claim 3, characterized in that: The lower part of the lithium iron phosphate precursor silo (3) is equipped with a weighing module (10) for quantitative material release. The weighing module (10), pneumatic valve A, pneumatic valve B, and pulse valve C are all connected to the controller.

6. The apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode material according to claim 5, characterized in that: Both the gaseous carbon source nitrogen and the gas source outlet pipeline are equipped with flow meters and pressure gauges, which are connected to the controller.

7. The apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode material according to claim 1, characterized in that: The lithium iron phosphate precursor silo (3) is connected to the material storage tank (7) via a screw feeder.

8. The apparatus for rapidly synthesizing uniform carbon-coated lithium iron phosphate cathode material according to claim 1, characterized in that: The bag collector (4) has a collection bin at the bottom.

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