Ternary material coating and washing system and process
By designing a ternary material coating and water washing system, the problems of uneven water washing, unclear water temperature control and poor coating effect in the existing technology are solved, and uniform water washing and efficient coating of materials are achieved, which improves the battery Cycle life and safety.
Patent Information
- Application Number
- CN202411643083.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-02-25
AI Technical Summary
In the prior art, the remaining LiOH and Li2CO3 of the ternary material after sintering lead to a slurry jelly, reducing the cycle life, and reacting with HF in the battery electrolyte to generate gas, which is not conducive to battery safety. At the same time, the water washing is uneven and the washing temperature is unclear, the coating equipment is complex, the wet coating solid content is low, the dry coating additive particles are large, and the coating effect is poor.
A ternary material coating and water washing system is designed, including an additive grinding device, a coating and water washing device and a water temperature control device. The sand mill grinds additive particles, and the dual/tri-screw mixer realizes continuous in and outflow and dehydration of materials. The liquid flow sensor and the spiral feeder control the solid-liquid ratio, and the frozen water circulation jacket and temperature sensor ensure the stability of the water washing temperature.
It realizes uniform washing and coating of ternary materials, reduces equipment complexity and production costs, improves the stability and coating effect of washing temperature, extends the circulation life of the material, and improves the safety of the battery.
Smart Images
Figure CN119500031A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of lithium battery positive electrode material preparation, and relates to a ternary material coating, water washing system and process. Background Art
[0002] During the high-temperature sintering process, an excess lithium source is added to the ternary material to balance the lithium volatilization during the sintering process and reduce the lithium-nickel mixing inside the material. However, after sintering, the excess Li will react with CO2 and H2O in the air to produce LiOH and Li2CO3 and remain on the surface of the material. The residual alkali remaining on the surface of the ternary material can easily cause the slurry to become jelly-like during the pulping process, causing an increase in irreversible capacity and reducing the cycle life; at the same time, the residual alkali will react with HF in the electrolyte in the battery to produce a large amount of gas, which is not conducive to the safety of the battery. Therefore, reducing the residual alkali on the surface of the ternary material is of great practical significance.
[0003] Ternary materials reduce the residual alkali of the materials by coating and washing. Prior art In the prior art, when washing ternary materials, a large amount of materials is put into a washing kettle and stirred with pure water. There must be a time difference when the materials enter the washing kettle, which causes the problem of uneven washing of the materials. On the other hand, the washing water temperature is crucial to the washing effect of the ternary materials. The prior art does not specify how to control the washing water temperature. The coating of ternary materials includes wet coating and dry coating. The existing wet coating has a low solid content, a large amount of water, and a long drying time. The additives used in the dry coating have large particles and the coating effect is worse than the wet method. Summary of the invention
[0004] Purpose of the invention: The purpose of the present invention is to provide a ternary material coating, water washing system and process to solve the following problems: first, the prior art coating and water washing require two sets of equipment, and the process equipment is complicated; second, there is a time difference in material input during water washing, which leads to uneven water washing and unclear water temperature control; during coating, the wet coating has a low solid content, a large amount of water, and a long drying time, while the additives used in the dry coating have large particles and poor coating effect.
[0005] Technical solution: A ternary material coating and water washing system, including an additive grinding device, a coating and water washing device and a water temperature control device, wherein:
[0006] The additive grinding device comprises a first storage tank, a sand mill and a second storage tank connected in sequence, the sand mill is used for grinding and refining additive particles during wet coating, and the second storage tank is provided with a jacket;
[0007] The coating and washing device comprises a mixer, a screw feeder and a material metering bin, the material in the material metering bin enters the mixer after the feeding speed is adjusted by the screw feeder, and a liquid flow sensor is provided at the junction of the second storage tank and the mixer;
[0008] The water temperature control device comprises a chilled water storage tank and a refrigerator. The chilled water storage tank is connected to the mixer and the second storage tank, and chilled circulating water is introduced into the mixer and the second storage tank.
[0009] Furthermore, the mixer contains a jacket and is equipped with a temperature sensor, which is connected to the refrigerator to provide real-time feedback on the temperature of the liquid in the mixer so as to control the water temperature through the refrigerator.
[0010] Furthermore, the mixer is a twin / triple screw mixer.
[0011] Furthermore, a dispersion disk is provided on the screw of the twin / triple-screw mixer, and the dispersion disk is used to disperse the powder entering the mixer.
[0012] A ternary material coating process is provided, wherein the process adopts the above-mentioned ternary material coating and water washing system, and comprises the following steps:
[0013] Step 1. Start the water temperature control device and set the freezing temperature of pure water;
[0014] Step 2. Add the additive and pure water into the first storage tank and stir them evenly, start the sand mill to pump the additive in the first storage tank into the sand mill for grinding, and pump the ground additive liquid into the second storage tank for standby use;
[0015] Step 3. Set the flow rate of the liquid flow sensor and the feeding speed of the screw feeder so that the solid-liquid ratio of the additive liquid to the material to be coated is (4-6):1, start the mixer, and meter the additive liquid in the second storage tank through the liquid flow sensor and the material through the screw feeder into the mixer for coating and mixing. Control the coating time by the speed of the mixer, and the mixed material flows into the subsequent process for drying.
[0016] Furthermore, the freezing temperature range of the pure water in step 1 is 25 to 35°C.
[0017] Furthermore, in step 3, the rotation speed of the mixer is 100 rpm, and the coating time is 5 to 10 minutes.
[0018] A ternary material water washing process is provided, the process adopts the above-mentioned ternary material coating and water washing system, and comprises the following steps:
[0019] Step 1. Start the water temperature control device and set the freezing temperature of pure water;
[0020] Step 2. Pump pure water into the second storage tank and wait for the temperature to stabilize before proceeding to the subsequent steps. During this process, pure water is added in real time to avoid temperature fluctuations caused by intermittent addition;
[0021] Step 3. Set the flow rate of the liquid flow sensor and the feeding speed of the screw feeder so that the solid-liquid ratio of pure water to the material to be washed is (4-7):1. The constant temperature pure water in the second storage tank is simultaneously metered into the mixer through the liquid flow sensor and the material screw feeder for washing and mixing. The washing time is controlled by the speed of the mixer. The washed material directly enters the dehydration equipment for dehydration.
[0022] Furthermore, the freezing temperature range of the pure water in step 1 is 5 to 15°C.
[0023] Furthermore, in step 3, the rotation speed of the mixer is 200 to 500 rpm, and the washing time is 0.5 to 5 min.
[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The ternary material washing and coating system of the present invention can be used for both washing and coating of ternary materials, which can reduce equipment investment and production costs;
[0025] 2. The purpose of water washing of ternary materials is mainly to remove lithium carbonate on the surface of the materials. The solubility of lithium carbonate in pure water increases as the temperature decreases. Therefore, the water washing temperature needs to be controlled to be stable during water washing. The water washing kettle used in the existing process is relatively large in size. When a large amount of material enters the water washing kettle, the temperature fluctuates greatly. Even if the water washing kettle is provided with a jacket, it is difficult to stabilize the water washing temperature in a short time. However, the present invention provides a chilled water circulation jacket on the twin / triple screw mixer and the storage tank, and connects it to the freezer through a temperature sensor on the mixer, ensuring real-time temperature transmission and adjustment, and ensuring the stability of the water washing temperature.
[0026] 3. In the existing process, there is a time difference of 0.5 to 3 minutes when a large amount of material enters the water washing kettle. At the same time, when all the materials enter the water washing kettle for stirring and discharging, the slurry is pumped into the solid-liquid separation equipment, which will also cause a time difference of 1 to 3 minutes, resulting in differences in the materials after water washing. However, the twin / triple screw mixer used in the present invention can realize continuous feeding, discharging and dehydration of materials, avoiding material differences;
[0027] 4. The sand mill can be used to grind and refine large particle additives to avoid uneven coating caused by the dispersion of coarse additives in the material;
[0028] 5. Through the unique screw design, a dispersion disk is set on the screw to break up the material, avoiding the occurrence of local dry powder or even blockage when the powder material comes into contact with the liquid, ensuring the uniformity and stability of water washing / coating; in addition, the screw design has a large shear force, which can increase the ratio of material to liquid and improve the efficiency during production. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 It is a schematic diagram of the system structure of the present invention.
[0030] Figure 2 for Figure 1 Schematic diagram of the local structure at A (screw and dispersion disk). DETAILED DESCRIPTION
[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.
[0032] like Figure 1-2 As shown, a ternary material coating and water washing system of this embodiment includes an additive grinding device, a coating and water washing device, and a water temperature control device, wherein:
[0033] The additive grinding device includes a first storage tank 101, a sand mill 102 and a second storage tank 103 connected in sequence. The sand mill 102 is used to grind and refine the additive particles during wet coating to avoid coarse additives being dispersed in the material and causing uneven coating. The second storage tank 103 is provided with a jacket for controlling the temperature.
[0034] The coating and washing device includes a mixer 104, a screw feeder 106 and a material metering bin 107. The material in the material metering bin 107 enters the mixer 104 after the feeding speed is adjusted by the screw feeder 106. A liquid flow sensor 105 is provided at the junction of the second storage tank 103 and the mixer 104. The solid-liquid ratio of the additive liquid to the material to be coated during coating, and the solid-liquid ratio of pure water to the material to be washed during washing can be controlled by adjusting the feeding speed of the screw feeder 106 and the liquid flow sensor 105.
[0035] The water temperature control device includes a chilled water storage tank 109 and a refrigerator 110 . The chilled water storage tank 109 is connected to the mixer 104 and the second storage tank 103 , and chilled circulating water is introduced into the mixer 104 and the second storage tank 103 .
[0036] In a specific embodiment, the mixer 104 has a jacket and is equipped with a temperature sensor 108 . The temperature sensor 108 is connected to a refrigerator 110 , and provides real-time feedback on the temperature of the liquid in the mixer 104 , thereby controlling the water temperature through the refrigerator 110 to ensure temperature stability.
[0037] In a specific embodiment, the mixer is a twin / triple screw mixer. The screw is designed with a large shear force, which can increase the ratio of material to liquid and improve the efficiency during production. A dispersion disk is provided on the screw to break up the material to avoid local dry powder or even blockage when the powder material comes into contact with the liquid, thereby ensuring the uniformity and stability of water washing / coating.
[0038] The following uses a specific embodiment to clearly and completely describe the method of using the ternary material coating and water washing system of the present invention and the coating and water washing process using the system.
[0039] Example 1-2 uses the ternary material coating and water washing system of the present invention for water washing:
[0040] Example 1
[0041] Start the refrigerant 110 and set the water temperature to 10°C. After the water temperature in the chilled water storage tank 109 stabilizes, add pure water to the second storage tank 103 for standby use;
[0042] Set the parameters of the liquid flow sensor 105 and the screw feeder 106 so that the pure water and the LiNi to be washed are 0.83 Co 0.06 Mn 0.11 The solid-liquid ratio of the O2 high-nickel ternary material is 4:1. Start the screw mixer 104 and set the speed to 400 rpm to control the time of the material in the mixer 104 to 60 seconds, and start the water washing operation. The washed material can enter the downstream process for dehydration.
[0043] Example 2
[0044] Compared with Example 1, the water temperature was controlled at 5°C, the solid-liquid ratio was controlled at 7:1, and the rotation speed was set at 200 rpm. Others remained the same.
[0045] Example 3-4 uses the ternary material coating and water washing system of the present invention for coating:
[0046] Example 3
[0047] Add additives and pure water into the first storage tank 101 in advance according to the ratio, start the sand mill 102 for grinding, and the ground material enters the second storage tank 103 for standby use;
[0048] Start the refrigerator 110 and set the water temperature to 25°C. After the water temperature of the chilled water storage tank 109 is stable, the temperature of the additive liquid in the second storage tank 103 is kept constant by controlling the temperature of the jacket;
[0049] The parameters of the liquid flow sensor 105 and the screw feeder 106 are set so that the additive liquid and the LiNi to be coated 0.6 Co0.2 Mn 0.2 The solid-liquid ratio of the O2 ternary material is 4:1. The screw mixer 104 is started and the speed is set to 100 rpm to control the time of the material in the mixer to 300 s. The coating operation is started, and the coated material can enter the downstream process for drying.
[0050] Example 4
[0051] Compared with Example 3, the material to be washed is LiNi 0.5 Co 0.2 Mn 0.3 O2, additive liquid and LiNi to be coated 0.5 Co 0.2 Mn 0.3 The solid-liquid ratio of O2 ternary material is 6:1. Others remain the same.
[0052] Comparative Example 1
[0053] Add 260L of 10℃ chilled water into the washing kettle, and then add 650kg of high nickel ternary material LiNi 0.83 Co 0.06 Mn 0.11 O2 is added into the washing kettle, the rotation speed of the washing kettle is 20rpm, and the washing time is 60s. After the washing is completed, the slurry is pumped into the downstream process for dehydration through a diaphragm pump.
[0054] Comparative Example 2
[0055] The pre-prepared additives and 280L of pure water were measured into the coating reactor, and then 650kg of LiNi 0.6 Co 0.2 Mn 0.2 O2 is added into the coating kettle, the stirring speed is 35rpm, the coating time is 20min, and after the coating is completed, it enters the downstream process for drying operation.
[0056] In order to verify the progressiveness of the embodiments of the present application, the following performance tests were carried out on the above-mentioned embodiments 1-4 and comparative examples 1-2: the above-mentioned materials were mixed with SP, PVDF, NMP, and carbon nanotubes in a ratio of 96:0.5:3:0.5 to prepare positive electrode sheets, and metallic lithium was used as the negative electrode sheet. Half-cells were assembled in a conventional manner, and the half-cells were tested using the Xinwei half-cell test system, and the charge and discharge test voltage was 3.0~4.4V.
[0057] Table 1:
[0058]
[0059] It can be seen from the data in Table 1 that Examples 1 and 2 and Comparative Example 1 are both water washing processes. Although the residual alkali content of the materials after water washing is consistent, the electrical properties of the materials are quite different. This is because the materials in Comparative Example 1 are not uniformly washed, and the temperature fluctuates during the water washing process, resulting in the deterioration of the performance of some materials after water washing. The consistent residual alkali content is because the low residual alkali materials of the over-washed materials and the high residual alkali materials of the under-washed materials exist at the same time in Comparative Example 1. Examples 3 and 4 and Comparative Example 2 are both coating processes. It can be seen that the various indicators of Comparative Example 2 are lower than those of Examples 3 and 4.
Claims
1. A ternary material coating and washing system, characterized in that: It includes an additive grinding device, a coating and water washing device, and a water temperature control device, wherein: The additive grinding device comprises a first storage tank (101), a sand mill (102) and a second storage tank (103) which are connected in sequence, the sand mill (102) is used for grinding and refining additive particles during wet coating, and the second storage tank (103) is provided with a jacket; The coating and washing device comprises a mixer (104), a screw feeder (106) and a material metering bin (107); the material in the material metering bin (107) enters the mixer (104) after the feeding speed is adjusted by the screw feeder (106); a liquid flow sensor (105) is provided at the junction of the second storage tank (103) and the mixer (104); The water temperature control device comprises a chilled water storage tank (109) and a refrigerator (110); the chilled water storage tank (109) is connected to a mixer (104) and a second storage tank (103); and chilled circulating water is introduced into the mixer (104) and the second storage tank (103).
2. The ternary material coating and washing system according to claim 1 is characterized in that: The mixer (104) contains a jacket and is equipped with a temperature sensor (108). The temperature sensor (108) is connected to the refrigerator (110) to provide real-time feedback on the temperature of the liquid in the mixer (104) so as to control the water temperature through the refrigerator (110).
3. The ternary material coating and washing system according to claim 1 is characterized in that: The mixer (104) is a twin / triple screw mixer.
4. The ternary material coating and washing system according to claim 3 is characterized in that: A dispersion disk (111) is arranged on the screw of the twin / triple screw mixer.
5. A ternary material coating process, characterized in that: The process adopts the ternary material coating and water washing system according to any one of claims 1 to 4, and comprises the following steps: Step 1. Start the water temperature control device and set the freezing temperature of pure water; Step 2. Add the additive and pure water into the first storage tank (101) and stir them evenly, start the sand mill (102) to pump the additive in the first storage tank (101) into the sand mill (102) for grinding, and pump the ground additive liquid into the second storage tank (103) for standby use; Step 3. Set the flow rate of the liquid flow sensor (105) and the feeding speed of the screw feeder (106) so that the solid-liquid ratio of the additive liquid to the material to be coated is (4-6):1, start the mixer (104), and meter the additive liquid in the second storage tank (103) through the liquid flow sensor (105) and the material through the screw feeder (106) into the mixer (104) for coating and mixing. The coating time is controlled by the rotation speed of the mixer (104), and the mixed material flows into the subsequent process for drying.
6. The ternary material coating process according to claim 5, characterized in that: The freezing temperature range of the pure water in step 1 is 25-35°C.
7. The ternary material coating process according to claim 5, characterized in that: In step 3, the rotation speed of the mixer (104) is 100 rpm, and the coating time is 5 to 10 minutes.
8. A ternary material washing process, characterized in that: The process adopts the ternary material coating and water washing system according to any one of claims 1 to 4, and comprises the following steps: Step 1. Start the water temperature control device and set the freezing temperature of pure water; Step 2. Pump pure water into the second storage tank (103) and wait until the temperature is stable before proceeding to the subsequent steps. During this process, pure water is added in real time to avoid temperature fluctuations caused by intermittent addition; Step 3. Set the flow rate of the liquid flow sensor (105) and the feeding speed of the screw feeder (106) so that the solid-liquid ratio of pure water to the material to be washed is (4-7):
1. The pure water at a constant temperature in the second storage tank (103) is simultaneously metered through the liquid flow sensor (105) and the material screw feeder (106) into the mixer (104) for washing and mixing. The washing time is controlled by the rotation speed of the mixer (104). The washed material directly enters the dehydration equipment for dehydration treatment.
9. The ternary material coating and washing process according to claim 8, characterized in that: The freezing temperature range of the pure water in step 1 is 5 to 15°C.
10. The ternary material coating and washing process according to claim 8, characterized in that: In step 3, the rotation speed of the mixer (104) is 200-500 rpm, and the washing time is 0.5-5 min.