JP5999000B2 - Stirring apparatus and stirring method - Google Patents

Description

  The present invention relates to a stirring device that stirs a paste-like liquid with a stirring member.

  A battery mounted on a hybrid vehicle, an electric vehicle, or the like includes a positive electrode plate, a negative electrode plate, and an electrolyte. Generally, a battery is manufactured through various manufacturing processes. For example, the manufacturing process of a lithium ion secondary battery includes a paste kneading process. The paste kneading step is a step of kneading a paste that becomes an electrode mixture layer (a positive electrode mixture layer and a negative electrode mixture layer) that causes an electrode reaction. That is, in the paste kneading step, for example, a positive electrode active material, a conductive agent, a binder, a binder, and a solvent are mixed in the container and stirred by a stirring member. Thereby, a positive electrode paste is produced | generated. Further, the negative electrode paste is similarly prepared.

  In the paste kneading step, stirring proceeds by shearing force acting on the paste, and bubbles are generated as a by-product. The bubbles are generated by nitrogen or oxygen contained in the solution, gas components adhering to the surface of the powder, or air taken into the paste during stirring.

  Thus, when stirring is advanced, bubbles are always generated in the paste. For this reason, when the paste is applied to the electrode core material with a lot of bubbles, pinholes and cracks are generated in the active material layer of the electrode plate, and the performance of the electrode is impaired. Moreover, if there are many bubbles contained in the paste, it causes a measurement error in the coarse particle inspection by the paste particle gauge.

  Patent Document 1 includes a stirring member including a U-shaped stirring rod assembled in a frame shape in a state of being close to the inner wall surface of the tank and a defoaming arm assembled to the stirring rod, and has a high viscosity. A technique for defoaming bubbles in the vicinity of the liquid surface of a viscous liquid is disclosed.

JP 05-115706 A Japanese Utility Model Publication No. 07-041508

  However, the technique of Patent Document 1 has a problem that the processing time becomes long because the defoaming treatment cannot be performed unless the liquid level of the paste rises to the vicinity of the defoaming arm. Further, since the defoaming arm becomes a resistance during stirring, there is a problem that excessive torque is applied to the stirring member.

  Then, this invention aims at suppressing the increase in the torque added to a stirring member, shortening the processing time of a defoaming process.

In order to solve the above problems, the stirring method according to the present invention is a stirring method in which a paste-like liquid is stirred using a stirring device . The stirring device is capable of storing the liquid, and is disposed in a container in which a supply port for allowing the liquid to flow is formed in a side wall, a decompression device that decompresses the internal pressure of the container, and the container. And a stirring member for stirring the liquid in a state where the internal pressure of the container is reduced by the pressure reducing device. The stirring member extends along the side wall portion of the container from the container bottom side toward the container upper side, and rotates in a state where the tip portion extends from the liquid level toward the container upper side. And a second stirring section extending along the bottom of the container. A plurality of flow holes are formed in the first stirring section at positions different from each other in the extending direction. A plurality of flow holes are formed in the second stirring unit. In the stirring method, the internal pressure of the container is reduced until it reaches a predetermined pressure, the internal pressure of the container is reduced to the predetermined pressure, and then the stirring member is rotated while supplying the liquid to the container, When the supply amount of the liquid reaches a predetermined amount, the supply of the liquid is stopped and the stirring by the stirring member is stopped.

  According to the present invention, an increase in torque applied to the stirring member can be suppressed while shortening the processing time of the defoaming process.

It is a schematic block diagram of a paste stirring apparatus. It is a flowchart of a defoaming process. It is the experimental result which verified the effect of the defoaming process. It is a graph of the experimental result of FIG.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a paste stirrer, which is illustrated through a stirring member. The X axis, the Y axis, and the Z axis are three axes orthogonal to each other, and the Z axis corresponds to the height direction of the container (corresponding to the extending direction). The paste stirrer 100 includes a container unit 10, a stirring member 20, a decompression device 30, and a motor 40, and generates the electrode paste A by so-called batch processing. The electrode paste A may be a positive electrode paste or a negative electrode paste applied to the electrode core material of the battery.

  The container part 10 is a kneading container for kneading the electrode paste A. The container portion 10 includes a bottomed cylindrical container body 11 and a lid member 12 that closes an opening of the container body 11. The Mono pump 14 is a liquid feed pump that feeds the electrode paste A, and the fed electrode paste A flows into the container portion 10 through the inflow pipe 13 (corresponding to a supply port). As the electrode paste A, a mixture of an active material, a conductive material, a binder, a binder, and a solvent can be used. The stirred electrode paste A is discharged from the discharge pipe 15 to the outside of the container unit 10.

  The stirring member 20 is formed in a so-called U-shape, and extends along the side wall portion 11 b of the container main body 11 (extending in the Z-axis direction) and along the bottom wall portion 11 a of the container main body 11. And a second agitation part 22 extending in the direction. The continuous portion of the first stirring unit 21 and the second stirring unit 22 is formed in an R shape. The 1st stirring part 21 and the 2nd stirring part 22 can be formed integrally.

  The shaft portion 23 extends in the Z-axis direction and is positioned at the substantially axial center of the container body 11. A lower end portion of the shaft portion 23 is connected to the second stirring portion 22. The shaft portion 23 is connected to the motor 40, and by rotating the motor 40, the first stirring portion 21 and the second stirring portion 22 connected to the shaft portion 23 are integrally formed around the Z-axis direction. Can be rotated. And thereby, the electrode paste A can be stirred. The rotational speed of the shaft portion 23 may be 40 to 60 rpm.

  A plurality of flow holes 21a are formed in the first stirring unit 21, and these flow holes 21a are formed at different positions along the Z-axis direction. A plurality of flow holes 22 a are formed in the second stirring unit 22.

  The decompression device 30 includes a vacuum pump 31 that exhausts air from the inside of the container unit 10 and a valve 32 that controls the discharge of air. The decompression device 30 decompresses the inside of the container portion 10 to promote defoaming of the electrode paste A. That is, when the inside of the container part 10 is depressurized, the bubbles contained in the electrode paste A are likely to float on the interface that is the boundary between the liquid phase and the gas layer, and the bubbles that have floated on the interface are easily repelled. Therefore, the defoaming efficiency is improved.

  Next, a method for stirring the electrode paste A will be described with reference to the flowchart of FIG. Note that the processing shown in this flowchart is executed by a controller (not shown). In step S101, the decompression device 30 is operated to decompress the container 10. In step S102, it is determined whether or not the internal pressure of the container part 10 has reached a predetermined pressure. Here, the predetermined pressure can be set to an appropriate value lower than the atmospheric pressure from the viewpoint of promoting defoaming.

  When the internal pressure of the container part 10 reaches a predetermined pressure (step S102 Yes), the process proceeds to step S103. When the internal pressure of the container part 10 has not reached the predetermined pressure (No in step S102), the process returns to step S101.

  In step S103, the MONO pump 14 is driven to start supplying the electrode paste A, and the motor 40 is driven to rotate the stirring member 20. The electrode paste A injected into the container part 10 is sequentially stirred and defoamed by the rotating stirring member 20.

  Here, the first stirring unit 21 always protrudes from the liquid surface of the electrode paste A. In other words, the upper end portion of the first stirring unit 21 is always positioned higher than the liquid level of the electrode paste A. The first stirring unit 21 has a plurality of flow holes 21a, and these flow holes 21a are formed at different positions along the Z-axis direction. According to the above-described configuration, in the process in which the electrode paste A flows into the container part 10, the liquid level height changes every moment, and the bubbles 21 generated in the liquid level are located near the liquid level. While being able to pass through and extending, the bubble in a liquid can be similarly defoamed. Thereby, since a defoaming process is implemented timely, processing time can be shortened.

  Further, if the processing of the electrode paste A is continued in a state where the defoaming process does not proceed, bubbles generated on the liquid surface come into contact with a liquid level sensor (not shown), and erroneous detection occurs, or the vacuum pump 31 causes bubbles to be generated. Inhalation may cause problems such as equipment failure. On the other hand, in this embodiment, since the defoaming process is sequentially performed with respect to the supplied electrode paste A, the said malfunction can be prevented.

  Furthermore, in this embodiment, since the turbulent flow is generated when the electrode paste A passes through the flow holes 21a and 22a, the stirring effect can be enhanced.

  Furthermore, in this embodiment, since the stirring member 20 can be rotated while letting the electrode paste A escape from the flow holes 21a and 22a, the stirring resistance can be lowered. Thereby, it can suppress that an excessive torque is added to the stirring member 20. FIG.

  In step S104, it is determined whether or not the supply process of the electrode paste A is completed. In the present embodiment, since the batch processing is performed, the supply processing is completed when the supply amount of the electrode paste A reaches a predetermined amount. When supply processing of electrode paste A is completed (Step S104 Yes), processing progresses to Step S105. When supply processing of electrode paste A is not completed (Step S104 No), processing returns to Step S103.

  In step S105, the decompression device 30 is operated to return the internal pressure of the container part 10 to atmospheric pressure, and the motor 40 is stopped to stop the stirring process by the stirring member 20. In step S106, the electrode paste A after the defoaming process is discharged from the discharge pipe 15, and the process ends.

  According to this embodiment, since the number of bubbles contained in the electrode paste A can be reduced, it is possible to suppress the occurrence of poor coating in the coating process in which the electrode paste A is applied to the electrode core material. Thereby, the yield of a battery can be improved.

  Next, an Example is shown and this invention is demonstrated more concretely. The table of FIG. 3 is the experimental data of each of Comparative Example 1, Comparative Example 2, and Example 1, and FIG. 4 is a graph of the experimental data of FIG. In Comparative Example 1, the electrode paste A was supplied to the inside of the container portion 10 with the stirring member 20 stopped. In Comparative Example 2, the stirring member 20 was rotated at a rotation speed of 60 rpm in a state where the upper end portion of the first stirring unit 21 was allowed to settle 10 cm below the liquid level. In Example 1, the stirring member 20 was rotated at a rotation speed of 60 rpm in a state where the upper end portion of the first stirring unit 21 was projected 3 cm from the liquid surface. In any of Comparative Example 1, Comparative Example 2, and Example 1, the supply of the electrode paste A was performed in a state where the internal pressure of the container part 10 was reduced to -0.085 KPa. In Comparative Example 1, since the stirring member 20 is stopped, the position of the blade is omitted. The flow rate when supplying the electrode paste to the container part 10 was set to 0.85 L / min. The viscosity of the electrode paste supplied to the container part 10 was 1500 mPa · S.

    In Comparative Example 1 and Comparative Example 2, an infinite number of bubbles on the liquid surface were confirmed, but in Example 1, the number could be limited to 80. In Comparative Examples 1 and 2, the number of bubbles in the liquid was confirmed to be 56 and 20, respectively, but in Example 1, it was limited to 2. Thus, in Example 1, it turned out that the total number of bubbles is restrict | limited to 100 or less, and a big defoaming effect is acquired.

DESCRIPTION OF SYMBOLS 10: Container part 11: Container main body 11a: Bottom wall part 11b: Side wall part 12: Lid member 13: Inflow duct 14: Mono pump 15: Discharge pipe 20: Stirring member 21: 1st stirring part 21a: Flow hole 22: 2nd Stirring section 22a: flow hole 23: shaft section 30: decompression device 31: vacuum pump
32: Valve 40: Motor

Claims (1)

Using 攪拌device, a stirring method for stirring the pasty liquid,
The stirring device is capable of storing the liquid, and is disposed in a container in which a supply port for allowing the liquid to flow is formed in a side wall, a decompression device that decompresses the internal pressure of the container, and the container. A stirring member that stirs the liquid in a state where the internal pressure of the container is reduced by the pressure reducing device,
The stirring member extends along the side wall portion of the container from the container bottom side toward the container upper side, and rotates in a state where the tip portion extends from the liquid level toward the container upper side. And a second stirring part extending along the bottom of the container,
In the first stirring section, a plurality of flow holes are formed at positions different from each other in the extending direction, and in the second stirring section, a plurality of flow holes are formed,
The stirring method is:
Depressurize until the internal pressure of the container reaches a predetermined pressure,
After reducing the internal pressure of the container to the predetermined pressure, rotating the stirring member while supplying the liquid to the container,
When the supply amount of the liquid reaches a predetermined amount, the supply of the liquid is stopped and the stirring by the stirring member is stopped.

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