A paddle-free stirring system and a paddle-free stirring method for negative electrode slurry

Abstract

The invention discloses a paddle-free stirring system and a paddle-free stirring method for negative electrode slurry, comprising a tank body, a heating jacket is provided on the outside of the tank body, a material blocking filter screen is provided in the tank body, a slurry mixed with a water solvent is provided below the material blocking filter screen inside the tank body, a vacuum pump and a condenser are connected in series through a pipeline above the material blocking filter screen, and a material discharge pipeline is provided at the upper end of the tank body. The advantage of the invention is that the vacuum pump is used to evacuate the tank body, and when the air pressure is reduced, the boiling point of the water body is also reduced accordingly. When the heating jacket is heated, the water body in the slurry boils to generate bubbles, and the mechanical energy released by the generation, merging and bursting process of a large number of bubbles generated by the violent boiling of the slurry is used to disperse the slurry, thereby completing the paddle-free stirring of the negative electrode slurry. Because the stirring is achieved by the bubbles generated by the boiling of the water body, there is no high-speed shearing, which can prevent the stirring material from being damaged, and no additional heat will be generated due to shearing, so that the temperature of the stirring environment can be conveniently controlled.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery preparation, in particular to a paddle-free stirring system and a paddle-free stirring method for negative electrode slurry. Background Art

[0002] At present, in order to respond to the national call to reduce carbon emissions, pure electric new energy vehicles are gradually becoming popular and entering thousands of households. As an important part of new energy vehicles, power batteries have seen an exponential growth in the scale of power battery production as new energy vehicles have exploded. The first process in power battery production is mixing. For example, in the Chinese patent literature, the patent number CN202022436591.0 is the "Lithium Battery Negative Electrode Slurry Stirring Device" patent authorized and announced on July 23, 2021. The application discloses a battery negative electrode slurry stirring device, which belongs to the field of lithium batteries, and includes a bracket, a stirring cylinder is arranged on the bracket, and a stirring mechanism is also arranged on the bracket. The stirring mechanism includes a rotating shaft and a driving motor. A plurality of first stirring plates are fixedly arranged on the left side of the rotating shaft from top to bottom in sequence, and a plurality of second stirring plates are arranged on the right side of the rotating shaft corresponding to the first stirring plates. A first elastic plate is fixedly arranged at the left end of the first stirring plate, and the first elastic plate extends upward from the first stirring plate. The front end of the first elastic plate extends forward to abut against the side wall of the stirring cylinder, and the front end of the first elastic plate produces elastic deformation to the right, and a second elastic plate is fixedly arranged at the right end of the second stirring plate, and the second elastic plate extends upward from the second stirring plate. The rear end of the second elastic plate extends backward to abut against the side wall of the stirring cylinder, and the rear end of the second elastic plate produces elastic deformation to the left.

[0003] In the prior art, the double planetary mixer is the most widely used equipment in the mixing process. The main components of the double planetary mixer are the twist paddle, dispersion shaft (dispersion disk installed on the shaft), planetary gearbox, mixing tank, hydraulic lifting system and other mechanisms. Other supporting equipment include cooling water, powder system, vacuum system. During mixing, the motor drives the planetary gearbox, and the planetary gear drives the twist paddle to rotate and revolve. The twist paddle drives the slurry to form a stable flow field. The motor drives the dispersion shaft at high speed, and the dispersion disk is transported at high speed to generate shear force to disperse the agglomerated particles of the slurry. The shortcomings of the prior art are: when the double planetary mixer is stirred, the motor converts electrical energy into mechanical energy, and the mechanical energy is converted into slurry kinetic energy and heat through the twist paddle and dispersion disk. The heat causes the slurry to heat up, and the system needs to cool the slurry through cooling water. In addition, the process of stirring, dispersion motor, cooling water, and vacuum system consume a lot of electricity, which can be high; the stirring process is sheared at high speed, and there is a possibility of stirring and damaging the material. Summary of the invention

[0004] Based on the above-mentioned deficiencies in the prior art, the present invention provides a paddleless stirring system and a paddleless stirring method for negative electrode slurry, which have low energy consumption in the stirring process, no high-speed shearing in the process, and the stirred materials will not be damaged; the waste hot water generated by the factory coating steam can be used to achieve stirring, further reducing energy loss.

[0005] In order to achieve the above-mentioned object of the invention, the present invention proposes the following technical solutions.

[0006] A paddleless stirring system is characterized in that it includes a tank body, a heating jacket is provided on the outside of the tank body, a material blocking filter is provided inside the tank body, a slurry mixed with a water solvent is provided below the material blocking filter inside the tank body, a vacuum pump and a condensation tank are connected in series through a pipeline above the material blocking filter, and a material discharge pipeline is provided at the upper end of the tank body.

[0007] The present application realizes vacuuming inside the tank body by a vacuum pump. When the air pressure decreases, the boiling point of the water body also decreases accordingly. When water is used as the solvent for the negative electrode slurry, when the air pressure inside the stirring tank body is less than 0.005~0.01MPa, the boiling point of the slurry is 32.9~45.8℃. When the vacuum degree and the temperature reach the corresponding range, the slurry boils violently and rolls to achieve slurry mixing and dispersion. When the heating jacket is heated, the water body in the slurry boils to generate bubbles. The mechanical energy released by the generation, merging and bursting of a large number of bubbles generated by the violent boiling of the slurry disperses the slurry, thereby completing the paddle-free stirring of the negative electrode slurry. Because the stirring is achieved by the bubbles generated by the boiling of the water body, there is no high-speed shearing, which can prevent the stirring material from being damaged, and no additional heat will be generated due to shearing, which is convenient for controlling the temperature of the stirring environment. The condensation tank body is used for the gas with solvent extracted by the vacuum pump, which is cooled and condensed to form a solvent for reuse.

[0008] Preferably, the pipeline between the vacuum pump and the tank body is provided with a first control valve, the pipeline between the vacuum pump and the condensing tank is provided with a second control valve, the pipeline between the condensing tank and the tank body is provided with a third control valve, the feed pipeline is provided with a fourth control valve, the vacuum pump is provided with a vacuum pump exhaust port and a stirring process exhaust port, the stirring process exhaust port is connected to the pipeline between the vacuum pump and the condensing tank, the pipeline between the second control valve and the condensing tank is provided with a bypass liquid material discharge port, and the liquid material discharge port is provided with a fifth control valve. Through various control valves, the reliability of the on-off control of the pipelines between the tank body, the vacuum pump and the condensing tank is ensured, the vacuum pump is provided with a vacuum pump exhaust port and a stirring process exhaust port, and the two exhaust ports can be switched, so that the vacuum pump can be used for vacuuming the tank body on the one hand, and can also be used as a delivery pump to realize solvent circulation on the other hand; the liquid material discharge port can realize direct replenishment of materials in the tank body, thereby improving replenishment efficiency.

[0009] Preferably, the heating jacket includes a casing covering the outer bottom and the outer side of the lower end of the tank body, and the casing is provided with a liquid inlet and a liquid outlet. The liquid inlet can be passed through the waste hot water generated by the factory coating steam, and the factory waste heat is used to provide a heating environment to reduce energy consumption.

[0010] Preferably, the tank is provided with a temperature sensor at the lower side of the slurry, and the slurry temperature is detected by the temperature sensor to ensure the reliability of the paddleless stirring.

[0011] Preferably, the bottom of the tank is spherical, and a discharge pipe with a discharge control valve is provided in the middle of the outer side of the bottom of the tank; a plurality of legs are arranged in an array around the circumference of the discharge pipe. The discharge pipe is located at the lowest point of the bottom of the tank, which is convenient for discharge after mixing, and the legs increase the height of the tank, which is convenient for discharge.

[0012] Preferably, the filter screen is lifted and lowered in the tank body. The filter screen can shake off the slurry that evaporates with the water vapor from the lower side of the filter screen, prevent the holes of the filter screen from being blocked, and ensure the reliability of the filter screen; it can also ensure the integrity of the slurry in the tank body and reduce the loss of the slurry.

[0013] Preferably, the material-blocking filter comprises a mounting frame and a filter layer located at the edge and fixedly connected to the mounting frame. The outer periphery of the mounting frame is provided with a plurality of mounting grooves which are recessed, and a sliding ball is fixedly provided in the mounting groove. The interior of the tank body is provided with a plurality of connecting sleeves, and the outer side of the connecting sleeve is provided with a sliding groove with an outer opening. The cross-sectional shape of the sliding groove is circular, and the sliding ball is slidably arranged in the sliding groove. The sliding ball and the sliding groove are in line contact, with a small contact area and small friction, which improves the reliability of the lifting and lowering of the material-blocking filter. The connecting sleeve is a connection structure independent of the tank body, which ensures the stability of the overall structure of the tank body and avoids the occurrence of an area of ​​the tank body that is easily deformed when the tank body is vacuumed.

[0014] Preferably, several sections of vacuum chambers are provided in the installation frame. When the water in the slurry boils, steam is generated. The water vapor cooperates with the suction force of the vacuum pump to form an upward driving force on the material blocking filter, thereby completing the lifting and lowering of the material blocking filter. The lifting and lowering of the material blocking filter can be achieved without other power. The vacuum chamber can reduce the density of the material blocking filter, further ensuring the reliability of the lifting and lowering of the material blocking filter.

[0015] A paddle-free stirring method for negative electrode slurry based on the paddle-free stirring system is characterized by comprising the following steps:

[0016] A. Vacuum the tank, put the powder material in proportion, and then spray the corresponding part of the solvent from the liquid material discharge port; the process controls the powder to be fully infiltrated; add a certain percentage of water in the solvent according to the normal demand ratio;

[0017] B. After the unloading is completed, turn on the vacuum pump. When the vacuum degree inside the tank reaches 0.01MPa, the vacuum exhaust port is switched to the exhaust port during the mixing process;

[0018] C. Hot water is introduced into the heating jacket, and the hot water circulates to heat the slurry inside the tank. The slurry inside the tank boils after being heated, generating a large number of bubbles. The bubbles are generated at the bottom of the tank, and they continue to grow and burst during the rising process, stirring and mixing the slurry. The hot water circulates continuously to control the slurry temperature at 32.9~45.8℃, ensuring that the slurry is always in a boiling state.

[0019] D. The vacuum pump continuously draws vacuum, and the extracted water vapor is pumped into the condenser. The chilled water in the condenser continuously circulates to lower the internal temperature of the condenser; the water vapor extracted from the tank is condensed into liquid water;

[0020] E. After stirring for a certain period of time, water accumulates inside the condensation tank, and the excess solvent added during mixing is discharged according to the weight ratio;

[0021] F. After the slurry is stirred, open the control valve on the pipe connecting the tank body below the condensation tank, a microcirculation is formed inside the tank body, and the stirring process is completed after a certain period of time.

[0022] The present application can realize paddle-free stirring of negative electrode slurry without replacing the stirring paddle, which is conducive to controlling the stirring temperature, can utilize industrial wastewater waste heat, and has environmental protection performance.

[0023] Preferably, in step A, water in the solvent is added by 50% to 120% more than the normal required ratio to ensure the efficiency of stirring bubbles formed by boiling water.

[0024] The beneficial effects of the present invention are: achieving paddle-free stirring of the negative electrode slurry; because the stirring is achieved through bubbles generated by boiling water, there is no high-speed shearing, which can prevent the stirring material from being damaged, and no additional heat will be generated due to shearing, which makes it convenient to control the temperature of the stirring environment; the condensation tank is used for the gas with solvent extracted by the vacuum pump, which is cooled and condensed to form a solvent for repeated use; it can utilize industrial wastewater waste heat and has environmental protection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the principle of the present invention.

[0026] Figure 2 It is a detailed schematic diagram of the appearance of the tank body of the present invention.

[0027] Figure 3 It is a schematic diagram of the material blocking filter screen and its installation in the tank body in the present invention.

[0028] Figure 4 It is a structural schematic diagram of the material blocking filter screen in the present invention.

[0029] In the figure: tank body 1 discharge control valve 100 discharge pipe 101 foot 102 heating jacket 11 jacket body 111 liquid inlet 112 liquid outlet 113 material blocking filter 12 mounting frame 121 filter layer 122 mounting groove 123 sliding ball 124 connecting sleeve rod 125 sliding groove 126 slurry 2 temperature sensor 3 vacuum pump 4 vacuum pump exhaust port 401 stirring process exhaust port 402 condensation tank 5 liquid material discharge port 501 discharge pipeline 6 first control valve 71 second control valve 72 third control valve 73 fourth control valve 74 fifth control valve 75. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0031] Embodiment 1,

[0032] like Figures 1 to 4As shown, a paddleless stirring system includes a tank body 1, the overall structure of the tank body 1 is cylindrical, the bottom shape of the tank body 1 is spherical, and a discharge pipe 101 with a discharge control valve 100 is provided in the middle position of the outer side of the bottom of the tank body 1; in addition to the discharge method applied in this embodiment, the discharge can also be achieved by providing a discharge hatch on the side of the tank body 1. Three legs 102 arranged in a circular array around the discharge pipe 101 are provided on the outer side of the bottom of the tank body 1. A heating jacket 11 is provided on the outer side of the tank body 1, and the heating jacket 11 includes a sleeve 111 covering the outer bottom and the outer side of the lower end of the tank body 1, and the sleeve 111 is provided with a liquid inlet 112 and a liquid outlet 113. A material blocking filter 12 is provided in the tank body 1, and a slurry 2 mixed with a water solvent is provided below the material blocking filter 12 inside the tank body 1, and a temperature sensor 3 is provided on the lower side of the slurry 2 of the tank body 1. The tank body 1 is provided with a vacuum pump 4 and a condensing tank 5 in series through a pipeline above the material blocking filter 12, and a material discharge pipeline 6 is provided at the upper end of the tank body 1. A first control valve 71 is provided on the pipeline between the vacuum pump 4 and the tank body 1, a second control valve 72 is provided on the pipeline between the vacuum pump 4 and the condensing tank 5, a third control valve 73 is provided on the pipeline between the condensing tank 5 and the tank body 1, a fourth control valve 74 is provided on the material discharge pipeline 6, a vacuum pump exhaust port 401 and a stirring process exhaust port 402 are provided on the vacuum pump 4, the stirring process exhaust port 402 is connected to the pipeline between the vacuum pump 4 and the condensing tank 5, a bypass liquid material discharge port 501 is provided on the pipeline between the second control valve 72 and the condensing tank 5, and a fifth control valve 75 is provided on the liquid material discharge port 501. The material blocking filter 12 is set up and down in the tank body 1. The material blocking filter 12 includes a mounting frame 121 and a filter layer 122 located at the edge and fixedly connected to the mounting frame 121. Four mounting grooves 123 are provided on the outer circumference of the mounting frame 121. The mounting frame 121 is in the shape of a circular ring. The four mounting grooves 123 are arranged in a circular array around the axis of the mounting frame 121. A sliding ball 124 is fixedly provided in the mounting groove 123. A cylindrical section is provided on one side of the sliding ball 124 to achieve a fixed connection with the mounting frame 121. Four connecting rods 125 are provided inside the tank body 1. The connecting rods 125 are a connecting structure independent of the tank body 1 to ensure the stability of the overall structure of the tank body 1 and avoid areas that are easily deformed when the tank body 1 is vacuumed. The connecting rods 125 are fixed to the inner wall of the tank body 1 by screws. The outer side of the connecting sleeve rod 125 is provided with a sliding groove 126 with an outer opening, and the upper and lower ends of the connecting sleeve rod 125 close the upper and lower ends of the sliding groove 126. A stopper is provided at the upper end of the connecting sleeve to correspond to the upper end of the sliding groove 126. The stopper and the connecting sleeve are fixed by screws. The sliding ball 124 is installed in the sliding groove 126 and then the stopper is installed to improve the installation efficiency of the material blocking filter 12. The cross-sectional shape of the sliding groove 126 is circular, and the sliding ball 124 is slidably arranged in the sliding groove 126. The sliding ball 124 and the sliding groove 126 are in line contact, with a small contact area and small friction, which improves the reliability of the lifting and lowering of the material blocking filter 12. Four vacuum chambers are provided in the installation frame 121.The vacuum chamber corresponds to the installation frame 121 between adjacent sliding grooves 126 .

[0033] Embodiment 2,

[0034] A paddle-free stirring method for negative electrode slurry based on the paddle-free stirring system comprises the following steps:

[0035] A. Vacuum the tank 1, feed the powder material into the feed pipe 6 in proportion, and then spray the corresponding part of the solvent into the liquid material feed port 501; during the process, the powder material can be fully wetted; the water in the solvent is increased by a certain percentage according to the normal demand ratio; in this embodiment, the water in the solvent is increased by 100% according to the normal demand ratio.

[0036] B. After the unloading is completed, the vacuum pump 4 is turned on. When the vacuum degree inside the tank body 1 reaches 0.01 MPa, the vacuum exhaust port is switched to the mixing process exhaust port 402;

[0037] C. Hot water is introduced into the heating jacket 11, and the hot water circulates to heat the slurry 2 inside the tank body 1; the slurry 2 inside the tank body 1 boils after being heated, generating a large number of bubbles; the bubbles are generated at the bottom of the tank body 1, and the bubbles continue to grow and burst during the rising process, stirring and mixing the slurry 2; the hot water circulates continuously, and the temperature of the slurry 2 is controlled at 32.9~45.8℃, ensuring that the slurry 2 is always in a boiling state;

[0038] D. The vacuum pump 4 continuously draws a vacuum, and the extracted water vapor is drawn to the condenser 5. The condenser pipe in the condenser 5 realizes continuous circulation of chilled water to reduce the internal temperature of the condenser 5; the water vapor drawn from the inside of the tank body 1 is condensed into liquid water;

[0039] E. After stirring for a certain period of time, water accumulates inside the condensation tank 5, and the excess solvent added during mixing is discharged according to the weight ratio;

[0040] F. After the slurry 2 is stirred, the third control valve 73 on the pipe below the condensation tank 5 connected to the tank body 1 is opened, and a microcirculation is formed inside the tank body 1. After a certain period of time, the stirring process is completed.

[0041] The present application can complete the paddle-free stirring of the negative electrode slurry 2; the stirring is achieved by bubbles generated by boiling water, without high-speed shearing, which can prevent the damage and replacement of stirring materials such as stirring paddles. In the prior art, damage to the stirring paddle will directly affect the use of the entire tank of slurry 2, causing serious material waste. The present application can avoid this problem. In addition, the paddle-free stirring will not generate additional heat due to shearing, which makes it convenient to control the temperature of the stirring environment; the condensation tank 5 is used for the solvent-containing gas extracted by the vacuum pump 4, which is cooled and condensed to form a solvent for repeated use; it can utilize industrial wastewater waste heat and has environmental protection performance.

Claims

1. A paddleless stirring system, characterized in that: The tank body comprises a tank body, a heating jacket is arranged on the outside of the tank body, a material blocking filter screen is arranged inside the tank body, a slurry mixed with a water solvent is arranged below the material blocking filter screen inside the tank body, a vacuum pump and a condensation tank are connected in series through a pipeline above the material blocking filter screen, and a material discharge pipeline is arranged at the upper end of the tank body; The material blocking filter screen comprises a mounting frame and a filter screen layer located at the edge and fixedly connected to the mounting frame. A plurality of mounting grooves are arranged inwardly on the outer circumference of the mounting frame. The mounting grooves are arranged in a circular array around the axis of the mounting frame. A sliding ball is fixedly arranged in the mounting groove. A cylindrical section is arranged on one side of the sliding ball to realize fixed connection with the mounting frame. A plurality of connecting rods are arranged inside the tank body, a sliding groove is arranged outside the connecting rod, and a sliding ball is slidably arranged in the sliding groove; The vacuum pump is provided with a vacuum pump exhaust port and a stirring process exhaust port, and the stirring process exhaust port is connected to a pipeline between the vacuum pump and the condensation tank.

2. A paddleless stirring system according to claim 1, characterized in that: The pipeline between the vacuum pump and the tank body is provided with a first control valve, the pipeline between the vacuum pump and the condensation tank is provided with a second control valve, the pipeline between the condensation tank and the tank body is provided with a third control valve, the discharge pipeline is provided with a fourth control valve, the vacuum pump is provided with a vacuum pump exhaust port and a stirring process exhaust port, the stirring process exhaust port is connected to the pipeline between the vacuum pump and the condensation tank, a bypass liquid material discharge port is provided on the pipeline between the second control valve and the condensation tank, and the liquid material discharge port is provided with a fifth control valve.

3. A paddleless stirring system according to claim 1, characterized in that: The heating jacket comprises a sleeve body covering the outer bottom and the outer side of the lower end of the tank body, and the sleeve body is provided with a liquid inlet and a liquid outlet.

4. A paddleless stirring system according to claim 1, characterized in that: The tank is provided with a temperature sensor at the lower side of the slurry.

5. A paddleless stirring system according to claim 1, characterized in that: The bottom of the tank body is spherical in shape, and a discharge pipe with a discharge control valve is arranged in the middle of the outer side of the bottom of the tank body; and a plurality of legs arranged in an array around the circumference of the discharge pipe are arranged on the outer side of the bottom of the tank body.

6. A paddleless stirring system according to claim 1, characterized in that: The material blocking filter is arranged to be lifted and lowered in the tank body; The lifting and lowering blocking filter screen can shake off the slurry that evaporates along with the water vapor on the lower side of the blocking filter screen.

7. The paddleless stirring system according to claim 1, characterized in that: The cross-sectional shape of the sliding groove is circular.

8. The paddleless stirring system according to claim 1, characterized in that: A plurality of vacuum chambers are arranged in the installation frame.

9. A method for stirring negative electrode slurry without a paddle based on the paddle-free stirring system according to any one of claims 1 to 8, characterized in that: The following steps are involved: A. Vacuum the tank, put the powder material in proportion, and then spray the corresponding part of the solvent from the liquid material discharge port; the process controls the powder to be fully infiltrated; add a certain percentage of water in the solvent according to the normal demand ratio; B. After the unloading is completed, turn on the vacuum pump. When the vacuum degree inside the tank reaches 0.01MPa, the vacuum exhaust port is switched to the exhaust port during the mixing process; C. Hot water is introduced into the heating jacket, and the hot water circulates to heat the slurry inside the tank. The slurry inside the tank boils after being heated, generating a large number of bubbles. The bubbles are generated at the bottom of the tank, and they continue to grow and burst during the rising process, stirring and mixing the slurry. The hot water circulates continuously to control the slurry temperature at 32.9~45.8℃, ensuring that the slurry is always in a boiling state. D. The vacuum pump continuously draws vacuum, and the extracted water vapor is pumped into the condenser. The chilled water in the condenser continuously circulates to lower the internal temperature of the condenser. The water vapor extracted from the tank is condensed into liquid water. E. After stirring for a certain period of time, water accumulates inside the condensation tank, and the excess solvent added during mixing is discharged according to the weight ratio; F. After the slurry is stirred, open the control valve on the pipe connecting the tank body below the condensation tank, a microcirculation is formed inside the tank body, and the stirring process is completed after a certain period of time.

10. The method for stirring negative electrode slurry without a paddle according to claim 9, characterized in that: In step A, water in the solvent is added by 50% to 120% according to the normal demand ratio.

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