JP2013114969A - Method for manufacturing electrode, and electrode manufactured by manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method which can achieve intermittent coating while suppressing protrusion of coating film thickness at a coating start end part, with simple components and a simple method.SOLUTION: The manufacturing method includes: a tank (1) for storing a coating agent; a supply pump (4) for pumping the coating agent in the tank (1); coating agent intermittent supply means (12 and 21) for intermittently shutting a coating agent supply passage (3) which supplies the pumped coating agent; and applying means (2) for applying the coating agent supplied from the coating agent intermittent supply means on a collector (5). The coating agent intermittent supply means (21) has passage cross-sectional area changing means (24) which changes a passage cross-sectional area of the coating agent supply passage (3) from a small side toward a large side until the discharge amount of the coating agent becomes constant from the start of coating.

Description

  The present invention relates to a method for manufacturing an electrode such as an electrode for a lithium ion secondary battery, and an electrode manufactured by the manufacturing method.

  There is an intermittent application method in which a coating agent is supplied to a die head by a coating agent intermittent supply means for intermittently supplying the coating agent, and the supplied coating agent is applied onto a current collector that runs continuously by the die head. In this intermittent application method, the coating film thickness at the coating start end protrudes, causing a drying failure during drying in a subsequent process, or dropping off in a pressing process. For this reason, there has been provided a three-way valve that intermittently supplies the coating agent to the die head and a suction pump that sucks the coating agent inside the die head when application is stopped (see Patent Document 1).

JP 2008-243658 A

  However, in the technique of the above-mentioned Patent Document 1, not only an expensive part such as a suction pump is required, but when forming the coating end portion, the coating agent is returned to the tank simultaneously with the operation of the suction pump. Complex control such as switching the three-way valve is also required.

  Then, an object of this invention is to provide the manufacturing method which can implement | achieve intermittent coating, suppressing the protrusion of the coating film thickness of a coating start edge part with a simple component and a simple method.

  In the electrode manufacturing method of the present invention, a tank for storing the coating agent, a supply pump for pumping the coating agent in the tank, and a coating agent supply passage for supplying the pumped coating agent are intermittently provided. And an application means for applying the coating agent supplied from the intermittent application agent supply means onto the current collector. And in the manufacturing method of the electrode of this invention, the said coating agent intermittent supply means is a passage cross-sectional area of the said coating agent supply path from the small side until the discharge amount of a coating agent becomes constant from the start of coating. It has passage cross-sectional area changing means for changing to the larger side.

  According to the present invention, since the passage cross-sectional area is initially reduced and then increased, the discharge amount at the start of coating is reduced, and changes in the inrush pressure of the coating agent and the discharge amount can be suppressed. As a result, the coating film thickness at the coating start end can be made uniform, and poor drying in the drying process and dropout in the pressing process can be prevented, and a good electrode can be formed. In this case, to achieve intermittent coating while suppressing the protrusion of the coating film thickness at the coating start end with a simple part such as a passage cross-sectional area changing means and a simple method of changing the passage cross-sectional area. Can do.

It is the schematic of the electrode manufacturing apparatus of 1st Embodiment of this invention. It is a partial schematic sectional drawing of the coating valve of 1st Embodiment. It is a partial schematic sectional drawing of the coating valve | bulb of a comparative example. It is a partial schematic sectional drawing of the coating valve | bulb of Examples 1-3. 6 is a partial schematic cross-sectional view of a coating valve of Example 4. FIG. 6 is a partial schematic cross-sectional view of a coating valve of Example 5. FIG. It is the table | surface which put together the protrusion film thickness ratio of the coating start end part by the difference in the step part of a coating valve, and the valve rod stroke amount. It is a distribution figure of the coating film thickness after drying when an electrode is intermittently formed using each coating valve of Example 1 and a comparative example.

  FIG. 1 is a schematic view of an electrode manufacturing apparatus according to a first embodiment of the present invention. The process for manufacturing the electrode includes a coating process, a drying process, a pressing process, and the like. Here, the coating process will be mainly described. In addition, the electrode here is an electrode for lithium ion secondary batteries.

  In FIG. 1, the coating agent tank 1 is filled with a slurry-like coating agent. The coating agent is obtained by kneading and diluting a positive electrode active material of Li metal oxide, a conductive material, and a binder in an organic solvent.

  The coating agent tank 1 and the die head 2 are connected by a coating agent supply passage 3. The coating agent filled in the coating agent tank 1 is continuously supplied to the die head 2 using the supply pump 4. The supply pump 4 discharges a coating agent having a constant pressure.

  The die head 2 has a lip 2a formed in a tapered shape. The paired lips 2a face each other with a gap therebetween, and form a slit-like discharge port 2b. The die head 2 faces one surface of the strip-shaped metal current collector 5, and applies a coating agent to the metal current collector 5 conveyed by the backup roll 6 from the discharge port 2 b of the die head 2.

  The metal current collector 5 is wound from the supply roll 7 to the take-up roll 8 with the backup roll 6 interposed therebetween. A winding roll 8 that is rotated by a motor (not shown) moves the metal current collector 5 while winding the metal current collector 5 from the supply roll 7 that winds the metal current collector 5, and the metal current collector 5 is moved between them. Application of the coating agent to the electric body 5 and drying of the applied coating agent are performed.

  A return passage 11 branched from the coating agent supply passage 3 between the supply pump 4 and the die head 2 and returned to the tank 1 is provided, and a return valve 12 as an open / close valve is provided in the return passage 11. The return valve 12 is for opening and closing the return passage 11. When the return valve 12 is opened, the coating agent is returned to the coating agent pump 1 without being supplied to the die head 2. When the return valve 12 is switched to the closed state, the coating agent is supplied to the die head 2 without being returned to the coating agent pump 1.

  Furthermore, a coating valve 21 is provided in the coating agent supply passage 3 between the branch portion of the retan passage 11 and the die head 2. The coating valve 21 is for opening and closing the coating agent supply passage 3.

  The two valves 12 and 21 are both electrically operated, and their opening / closing is controlled by the control circuit 15.

  In the control circuit 15, when the coating is not performed, the return valve 12 is switched to the fully open state, and the coating agent fed by the supply pump 4 is quickly returned to the coating agent tank 1. When the intermittent coating is started, the return valve 12 is switched to the fully closed state and the coating valve 21 is opened to feed the coating agent to the die head 2 by pressure. The coating agent is discharged from the discharge port 2b of the die head 2 onto the metal current collector 5 flowing on the rotating backup roll 6 and applied. When the intermittent coating is finished, the coating valve 14 is fully closed, the return valve 12 is switched to the fully open state, and the coating agent is returned to the coating agent tank 1.

  In the present embodiment, the coating agent is discharged onto the metal current collector 5 from the discharge port 2b of the die head 2 only while the coating valve 21 is open. As shown in the upper part, the coating agent is applied intermittently (discontinuously) at predetermined intervals. The coating agent applied intermittently is dried in the drying step, and in the pressing step, the coating film thickness is adjusted to a predetermined value by applying a roller of a constant pressure to the coating agent on the metal current collector. The coating agent dried and shaped as described above functions as the positive electrode active material layer 9. In the step after the positive electrode active material layer 9 is formed on one surface of the metal current collector 5, the positive electrode active material layer 9 is also formed on the other surface of the metal current collector in the same manner as described above. In this case, the positive electrode active material layer 9 is formed at the same position on the front and back of the metal current collector, and the positive electrode (electrode) is completed.

  FIG. 2 is a partial schematic cross-sectional view of the coating valve 21 of the first embodiment. 2 shows the fully closed state of the coating valve 21 of the first embodiment, the center of FIG. 2 shows the half-opened state of the coating valve 21 of the first embodiment, and the right side of FIG. 2 shows the coating valve 21 of the first embodiment. The fully open state is shown.

  The coating valve 21 is mainly composed of a valve flange 22, a valve body 23, a stepped portion 24, a valve rod 27, and a valve rod drive motor unit 28.

  First, the cylindrical valve flange 22 uses an internal passage 22 b formed on the inner surface 22 a as a part of the coating agent supply passage 3. The coating agent enters, for example, from the lower opening end 22c of the internal passage 22b of the valve flange 22, and is discharged to the outside from the upper opening end 22d. A disc-shaped valve body 23 is provided to the valve flange 22 to cut off and open the upper opening end 22d of the valve flange 22 from above.

  A valve rod 27 is provided at the center of the valve flange 22, and the upper end of the valve rod passes through the center of the valve body. The upper end portion of the valve rod 27 is fixed to the valve main body 23, and the valve main body 23 blocks and opens the upper open end 22d of the valve flange 22 when the valve rod 27 strokes in the vertical direction. Here, the “stroke” of the valve rod 27 means that the valve rod 27 reciprocates in the vertical direction.

  Further, the valve body 23 includes a columnar stepped portion 24 (passage cross-sectional area changing means) protruding into the valve flange 22 in a state where the valve body 23 is in contact with the upper opening end 22d of the valve flange 22. . Since the stepped portion 24 is spatially overlapped with the valve rod 27, the stepped portion 24 may be formed integrally with the valve rod 27.

  The cylindrical side surface 24a of the stepped portion 24 and the inner surface of the valve flange from when the valve body 23 that moves integrally with the valve rod 27 starts to open the upper open end 22d until the stepped portion 24 exits the upper open end 22d. The coating agent passes through the internal passage 22b between 22a. On the other hand, after the valve rod 27 further strokes upward and the stepped portion 24 exits the upper opening end 22d, the coating agent passes through the internal passage 22b between the valve flange inner surface 22a and the cylindrical side surface 27a of the valve rod 27. Passing through, the discharge amount of the coating agent becomes constant.

  Here, the passage cross-sectional area of the internal passage 22b between the cylindrical side surface 24a of the stepped portion 24 and the valve flange inner surface 22a is equal to the internal passage 22b between the valve flange inner surface 22a and the cylindrical side surface 27a of the valve rod 27. Smaller than the cross-sectional area of the passage. That is, by providing the stepped portion 24, the passage sectional area of the coating agent supply passage is changed in two steps from the small side to the large side until the discharge amount of the coating agent becomes constant from the start of coating. Can do.

  In order to make the flow of the coating agent smooth, tapered portions 25 and 26 are provided on the lower surfaces of the valve body 23 and the stepped portion 24, respectively. Below, it demonstrates as what does not have the taper parts 25 and 26. FIG.

  The lower end of the valve rod 27 is connected to the valve rod drive motor unit 28. Although details of the valve rod drive motor unit 28 are not shown, a motor that rotates upon receipt of electricity from a power supply facility, an electric circuit that switches the rotation direction of the motor between forward rotation and reverse rotation, and a rotational movement of the motor in a straight line. And a mechanism that converts it into motion. For example, when a current is passed through the motor to rotate the motor forward, the valve rod 27 strokes (moves) upward at a substantially constant speed, and the valve body 23 opens the upper open end 22 d of the valve flange 22. Conversely, when a reverse current is passed through the motor to reverse the motor, the valve rod 27 strokes (moves) downward at a substantially constant speed so that the valve body 23 contacts the upper open end 22d of the valve flange 22. The valve rod 25 strokes downward until the upper opening end 22d is cut off. The speed at which the valve rod 27 is stroked upward and the speed at which the valve rod 27 is stroked downward may be the same or different.

  By providing the stepped portion 24, the maximum stroke amount of the valve rod 27 is set so that the flow of the coating agent exiting the upper opening end 22d does not become worse than when the stepped portion 24 is not provided. This maximum stroke amount is hereinafter referred to as “a full-open stroke amount” (see the right side of FIG. 2).

  While the coating is not performed, the valve rod drive motor unit 28 is in an inoperative state. At this time, as shown in the left side of FIG. 2, in the coating valve 21, the valve body 23 blocks the upper opening end 22d of the valve flange 22 (in a fully closed state), and the coating agent does not flow.

  When starting intermittent coating, the valve body 23 opens the upper opening end 22d of the valve flange 22 by operating the valve rod drive motor unit 28 to stroke (push up) the valve rod 27 upward. Then, the coating agent tends to be discharged through an internal passage 22b formed between the valve body 23 and the upper opening end 22d of the valve flange 22. At this time, since the stepped portion 24 is present in the internal passage 22b, the discharge of the coating agent is obstructed, so that the passage through which the coating agent passes is the cylinder of the inner surface 22a of the valve flange 22 and the stepped portion 24. Only the ring-shaped internal passage 22b formed between the cylindrical side surface 24a is provided. That is, when compared with a coating valve not provided with the stepped portion 24, the passage sectional area of the internal passage 22b is reduced by the sectional area of the stepped portion 24. This reduction in the cross-sectional area of the passage includes the half-open state shown in the center of FIG. 2 and continues until the valve rod 27 strokes upward and the stepped portion 24 exits the upper open end 22 d of the valve flange 22.

  In order to quantify how much the cross-sectional area of the internal passage 22b decreases, when the inner diameter of the inner surface 22a of the valve flange 22 is ΦDmm and the outer diameter of the cylindrical side surface 24a of the stepped portion 24 is Φdmm, The passage cross-sectional area ratio of the internal passage 22b with respect to 21 is defined by the following equation.

Passage cross-sectional area ratio [%] = (D ^ 2-d ^ 2) / D ^ 2) (1)
The passage sectional area ratio of (1) is the passage sectional area of the internal passage 22b for the coating valve 21 of the first embodiment relative to the passage sectional area of the internal passage 22b for the coating valve 21 without the stepped portion 24. The ratio of is displayed as a percentage. From the equation (1), the passage cross-sectional area ratio of the internal passage 22b for the coating valve 21 becomes smaller than 100 [%] as the outer diameter d of the cylindrical side surface 24a of the stepped portion 24 is increased. If the passage cross-sectional area of the internal passage 22b is reduced, the discharge amount of the coating agent passing through the passage cross section of the internal passage 22b with respect to the coating valve 21 is reduced in proportion thereto.

  After that, the valve rod 25 further strokes upward, and after the stroke amount of the valve rod 25 reaches the length L in the axial direction (vertical direction) of the stepped portion 24, the stepped portion 24 moves above the valve flange 22. Exit through the open end 22d. In this state, the stepped portion 24 does not obstruct the discharge of the coating agent that passes through the internal passage 22b, so that the stroke of the valve rod 25 reaches the internal passage from before reaching the axial length L of the stepped portion 24. The discharge amount of the coating agent passing through 22b increases. In terms of the passage cross-sectional area ratio of the internal passage 22b, in the first embodiment, the passage cross-sectional area ratio of the internal passage 22b is changed from a ratio smaller than 100 [%] to 100 [%], that is, from a smaller side. It is changed in two steps to the larger side.

  Actually, in a state where the stepped portion 24 has just come out of the upper opening end 22d of the valve flange 22, the stepped portion 24 obstructs the flow of the coating agent coming out of the internal passage 22b and becomes a resistance. Therefore, the valve rod 25 is stroked further upward to a position where the stepped portion 24 hardly obstructs the flow of the coating agent. Then, a stroke amount up to a position where the stepped portion 24 hardly obstructs the flow of the coating agent is determined as a fully open stroke amount Ls. In other words, as shown on the right side of FIG. 2, after the stroke amount of the valve rod 25 reaches the fully open stroke amount Ls, the coating agent that has exited the internal passage 22b flows around the stepped portion 24 and flows. . In this state, the stepped portion 24 hardly obstructs the flow of the coating agent that has exited the internal passage 22b, and the maximum amount (a constant amount) flows.

  On the other hand, when the intermittent coating is finished, the valve rod drive motor unit 26 is operated and the valve rod 25 is stroked (pulled) downward, so that the valve body 23 comes into contact with the upper opening end 22d of the valve flange 22, The upper opening end 22d is blocked. As a result, the internal passage 22b, that is, the coating agent supply passage 3 is closed.

  FIG. 3 is a partial schematic cross-sectional view of a coating valve 21 of a comparative example. The left side of FIG. 3 shows the fully closed state of the coating valve 21 of the comparative example, and the right side of FIG. 3 shows the fully opened state of the coating valve 21 of the comparative example. The coating valve 21 of the comparative example is obtained by removing the stepped portion 24 from the coating valve 21 of the first embodiment.

  Even in the coating valve 21 of the comparative example, while the coating is not performed, the coating valve 21 is in the fully closed state as shown on the left side of FIG. 3, and the coating agent does not flow.

  When starting intermittent coating, the valve rod drive motor unit 28 is operated and the valve rod 27 is stroked upward, so that the valve body 23 opens the upper open end 22 of the valve flange 22. Then, it passes through a passage formed between the valve main body 23 and the upper open end 22d of the valve flange 22, that is, an interior formed between the inner surface 22a of the valve flange 22 and the cylindrical side surface 27a of the valve rod 27. The coating agent is discharged through the passage 22b. This state continues until the stroke amount of the valve rod 27 coincides with the fully open stroke amount.

  Since the passage sectional area ratio of the internal passage 22b for the coating valve 21 of the comparative example may be d = 0 in the above equation (1), the passage sectional area of the internal passage 22b for the coating valve 21 of the comparative example. The ratio is 100 [%]. During the stroke of the valve rod 27, the passage cross-sectional area ratio of the internal passage 22b remains 100 [%] and does not change.

  On the other hand, when the intermittent coating is finished, the valve rod drive motor unit 28 is operated and the valve rod 27 is stroked (pulled) downward, so that the valve body 23 comes into contact with the upper opening end 22d of the valve flange 22, The upper opening end 22d is blocked. As a result, the internal passage 22b, that is, the coating agent supply passage 3 is closed.

  Although not described, the configuration of the return valve 12 is the same as that of the coating valve 21 of the comparative example shown in FIG.

  Here, the function and effect of the first embodiment will be described.

  In the first embodiment, a tank 1 for storing a coating agent, a supply pump 4 for pumping the coating agent in the tank, and a coating agent supply passage 3 for supplying the pumped coating agent are intermittently provided. The return valve 12 and the coating valve 21 (coating agent intermittent supply means) that are interrupted to each other, and the die head 2 that applies the coating agent supplied from these valves 12 and 21 onto the metal current collector 5 (current collector). The coating valve 21 (coating agent intermittent supply means) is provided in the internal passage 22b (coating agent supply passage 3) from the start of coating until the discharge amount of the coating agent becomes constant. It has a stepped portion 24 (passage cross-sectional area changing means) that changes the cross-sectional area of the passage from the small side to the large side in two steps. According to the first embodiment, since the passage cross-sectional area of the internal passage 22b is initially reduced and then increased, the discharge amount at the start of coating is reduced, and the change in the inrush pressure and the discharge amount of the coating agent can be suppressed. it can. As a result, the coating film thickness at the coating start end can be made uniform, and poor drying in the drying process and dropout in the pressing process can be prevented, and a good electrode can be formed. In this case, the protrusion of the coating film thickness at the coating start end is made by a simple part such as the stepped portion 24 (passage cross-sectional area changing means) and a simple method of changing the cross-sectional area of the internal passage 22b. Intermittent coating can be realized while suppressing. When a suction pump is used as in the conventional apparatus, there may be a problem that the equipment investment including maintenance and durability of the coating equipment increases, but according to the first embodiment adopting simple parts and a simple method. Thus, capital investment can be suppressed.

  According to the first embodiment, the valve flange 22 having the internal passage 22b formed in the inner surface 22a as the coating agent supply passage 3, and the open end 22d (one open end) of the valve flange 22 above the internal passage 22b. ), A valve rod 27 fixed to the valve body 23, and a valve rod drive motor unit 28 (actuator) for driving the valve rod 27 in the cutoff / opening direction. Since the cross-sectional area changing means is a stepped portion 24 that moves integrally with the valve main body 23 and protrudes into the internal passage 22b leaving a space between the inner surface 22a, a stepped portion is provided on the valve main body 23 and the valve rod 27. It is only necessary to design and set 24, thereby obtaining a passage cross-sectional area changing means that is inexpensive and has high reproducibility of changing the cross-sectional area of the flow path. It is possible.

(Example)
Next, Examples 1 to 5 will be described.

  FIG. 4 is a partial schematic cross-sectional view of the coating valve 21 of Examples 1-3. The left side of FIG. 4 shows the fully opened state of the coating valve 21 of Example 1, the center of FIG. 4 shows the fully opened state of the coating valve 21 of Example 2, and the right side of FIG. 4 shows the fully opened state of the coating valve 21 of Example 3. Show. The same parts as those in FIG.

Example 1
In Example 1, as shown on the left side of FIG. 4, the ratio Φd / ΦD = 0.864 of the outer diameter of the cylindrical side surface 24a of the stepped portion 24 and the inner diameter of the valve flange inner surface 22a is set. In addition, the ratio L / Ls = 60 [%] between the axial length of the stepped portion 24 and the fully open stroke amount of the valve rod 27 is set.

(Example 2)
In the second embodiment, as shown in the center of FIG. 4, the ratio Φd / ΦD = 0.864 of the outer diameter of the cylindrical side surface 24a of the stepped portion 24 and the inner diameter of the valve flange inner surface 22a is set to 0.864. And the axial length L of the stepped portion 24 is longer than that of the first embodiment. That is, the ratio L / Ls = 80 [%] between the axial length of the stepped portion 24 and the fully open stroke amount of the valve rod 27 is 20 [%] larger than that of the first embodiment.

(Example 3)
As shown in the right side of FIG. 4, the third embodiment increases the outer diameter d of the cylindrical side surface 24 a of the stepped portion 24 and the axial length L of the stepped portion 24 as compared to the second embodiment. It is a shortened one. That is, the ratio Φd / ΦD = 0.886 between the outer diameter of the cylindrical side surface 24a of the stepped portion 24 and the inner diameter of the valve flange inner surface 22a is 0.022 larger than the second embodiment, and the stepped portion 24 The ratio L / Ls = 40 [%] between the axial length and the fully open stroke amount of the valve rod 27 is reduced to half that of the second embodiment.

Example 4
FIG. 5 is a partial schematic sectional view of the coating valve 21 of the fourth embodiment. The left side of FIG. 5 shows the fully closed state of the coating valve 21 of Example 4, the center of FIG. 5 shows the half-opened state of the coating valve 21 of Example 4, and the right side of FIG. 5 shows the fully opened state of the coating valve 21 of Example 4. Is shown. The same parts as those in FIG.

  In the fourth embodiment, a columnar stepped portion 31 having a smaller diameter than the outer diameter of the cylindrical side surface 24a of the stepped portion 24 is additionally provided on the lower surface 24b of the stepped portion 24 with respect to the third embodiment. Is. Here, since there are two stepped portions, the large-diameter stepped portion 24 is distinguished from the first stepped portion, and the small-diameter stepped portion 31 is distinguished as the second stepped portion. The axial length of the first stepped portion 24 is L1, and the axial length of the first stepped portion 31 is L2.

  Since the first stepped portion 24 is the same as that of the third embodiment, the ratio Φd / ΦD = 0 of the outer diameter of the cylindrical side surface 24a of the first stepped portion 24 and the inner diameter of the valve flange inner surface 22a = 0. 886. Ratio L1 / Ls = 40 [%] between the axial length of the stepped portion 24 of the first step and the full-open stroke amount. For the second stepped portion 31, the ratio Φd / ΦD = 0.818 of the outer diameter of the cylindrical side surface 31 a of the second stepped portion 31 and the inner diameter of the valve flange inner surface 22 a is set to the second step. The ratio L2 / Ls = 20 [%] between the axial length of the stepped portion 31 and the full-open stroke amount is set.

  A tapered portion 32 is provided on the lower surface 31 b of the second stepped portion 31.

  Here, how the coating bar 21 of Example 4 works will be described.

  The operation of the coating valve 21 of the fourth embodiment is the same as that of the third embodiment until the valve rod 27 is stroked upward and the first stepped portion 24 comes out of the upper opening end 22d of the valve flange 22. That is, when intermittent coating is started, the valve rod drive motor unit 28 is operated to stroke (push up) the valve rod 27 upward, so that the valve body 23 opens the upper opening end 22 d of the valve flange 22. Then, the coating agent tends to be discharged through an internal passage 22b formed between the valve body 23 and the upper opening end 22d of the valve flange 22. At this time, since the stepped portion 24 is present in the internal passage 22b, the discharge of the coating agent is obstructed, so that the passage through which the coating agent passes is the cylinder of the inner surface 22a of the valve flange 22 and the stepped portion 24. Only the ring-shaped internal passage 22b formed between the cylindrical side surface 24a is provided. That is, when compared with a coating valve not provided with the stepped portion 24, the passage sectional area of the internal passage 22b is reduced by the sectional area of the stepped portion 24. As shown in the center of FIG. 5, this reduction in the passage cross-sectional area causes the valve rod 27 to stroke upward by the axial length L1 (= 0.4Ls) of the first stepped portion 24, The first stepped portion 24 continues until it exits the upper opening end 22d of the valve flange 22.

  In the coating valve 21 of the fourth embodiment, since the second stepped portion 31 is provided, the valve rod 27 strokes upward, and the first stepped portion 24 connects the upper open end 22d of the valve flange 22. The operation after exiting is different from the third embodiment. That is, even after the first stepped portion 24 exits the upper opening end 22d of the valve flange 22, the second stepped portion 31 exists in the internal passage 22b. For this reason, the passage through which the coating agent passes is a ring-shaped internal passage 22b formed between the inner surface 22a of the valve flange 22 and the cylindrical side surface 31a of the second stepped portion 31. The passage sectional area of the internal passage 22b at this time is slightly larger than the passage sectional area of the internal passage 22b when the first stepped portion 24 is present in the internal passage 22b. The gradual increase in the cross-sectional area of the passage is caused by the valve rod 27 stroking upward by the axial length L2 (= 0.2Ls) of the second stepped portion 31 and the second stepped portion. 31 continues until it exits the upper open end 22d of the valve flange 22.

  After the valve rod 25 strokes further upward and the second stepped portion 31 exits the upper opening end 22d of the valve flange 22, the passage cross-sectional area ratio of the internal passage 22b becomes 100 [%]. The process continues until the full open stroke amount Ls is reached.

  From the state where the stroke has been reached to reach the sum (= 0.6 Ls) of the axial length L1 of the first stepped portion 24 and the axial length L2 of the second stepped portion 31, the valve When the rod 25 strokes by 0.4 Ls, the full opening stroke amount Ls is reached.

(Example 5)
FIG. 6 is a partial schematic cross-sectional view of the coating valve 21 of the fifth embodiment. The left side of FIG. 6 shows the fully closed state of the coating valve 21 of Example 5, the center of FIG. 6 shows the half-opened state of the coating valve 21 of Example 5, and the right side of FIG. 6 shows the fully opened state of the coating valve 21 of Example 5. Is shown. The same parts as those in FIG.

  In the fifth embodiment, on the premise of the third embodiment, the stepped portion 34 is provided in the direction away from the valve body 23 (downward). Here, in order to distinguish from the stepped portion 24 of the third embodiment, the stepped portion 34 provided with a predetermined space from the lower surface of the valve body 23 is referred to as an “intermediate stepped portion”.

  Since the shape of the intermediate stepped portion 34 is the same as the shape of the stepped portion 24 of the third embodiment, the ratio Φd / between the outer diameter of the cylindrical side surface 34a of the intermediate stepped portion 34 and the inner diameter of the valve flange inner surface 22a. ΦD = 0.886. Further, if the axial length of the intermediate stepped portion 34 is L3, the ratio of the axial length of the intermediate stepped portion 34 and the fully open stroke amount of the valve rod 27 is L3 / Ls = 40 [%] (FIG. 6). See right).

  Further, the stroke amount of the valve rod 27 when the upper surface 34b of the intermediate stepped portion 34 reaches the upper opening end 22d of the valve flange 22 is 50% of the fully open stroke amount Ls as shown in the center of FIG. Sometimes.

  Tapered portions 35 and 36 are respectively provided on the upper surface 34b and the lower surface 34c of the intermediate stepped portion 34 (see the left side of FIG. 6).

  Here, how the coating bar 21 of Example 5 works will be described.

  When starting intermittent coating, the valve body 23 opens the upper opening end 22d of the valve flange 22 by operating the valve rod drive motor unit 28 to stroke (push up) the valve rod 27 upward. Then, the coating agent tends to be discharged through an internal passage 22b formed between the valve body 23 and the upper opening end 22d of the valve flange 22. At this time, unlike the coating valve 21 of the third embodiment, there is no stepped portion 24, so that the discharge of the coating agent passing through the internal passage 22b is not obstructed, and the passage through which the coating agent passes. Is an internal passage 22 b formed between the inner surface 22 a of the valve flange 22 and the cylindrical side surface 27 a of the valve rod 27. In other words, the passage cross-sectional area ratio of the internal passage 22b is 100 [%] as in the coating valve 21 in which the stepped portion 24 is not provided.

  After that, when the valve rod 25 further strokes upward and the intermediate stepped portion 34 approaches the upper opening end 22d of the valve flange 22, the intermediate stepped portion 34 discharges the coating agent passing through the internal passage 22b. disturbed by. When the valve rod 25 further strokes upward and the stroke amount of the valve rod 25 becomes half of the full-open throttle amount Ls, the state shown in the center of FIG. 6 is obtained. The passage through which the coating agent passes in this state is only the ring-shaped internal passage 22b formed between the inner surface 22a of the valve flange 22 and the cylindrical side surface 34a of the intermediate stepped portion 34. The state in which the passage through which the coating agent passes is only the ring-shaped internal passage 22b formed between the inner surface 22a of the valve flange 22 and the cylindrical side surface 34a of the intermediate stepped portion 34 is an intermediate step. This continues until the portion 34 exits the upper open end 22d of the valve flange 22.

  After the valve rod 25 has been stroked upward by the axial length L3 (= 0.4 Ls) of the intermediate stepped portion 34 from the state in the center of FIG. The end passage 22d exits and the cross-sectional area ratio of the internal passage 22b is 100%.

  If the valve rod 25 is further stroked upward by 0.1 Ls from the stroke length of the intermediate stepped portion 34 in the axial direction L3 (= 0.4 Ls), the stroke amount of the valve rod 27 is changed to the fully open stroke amount Ls. To reach.

  The electrode formed intermittently using each coating valve 21 of the comparative example and Examples 1 to 5 is an electrode for a lithium ion secondary battery. For this reason, Li metal oxide was used as the positive electrode active material, carbon black was used as the conductive material, and PVDF was used as the binder, and these were kneaded and diluted in an organic solvent NMP to obtain a coating agent having a solid content of 60 wt%. In addition, an aluminum current collector was used as the metal current collector 5. Using each of the coating valves 21 of the comparative example and Examples 1 to 5, the coating agent (positive electrode) was intermittently coated on the aluminum current collector, and passed through a continuous drying furnace. Each positive electrode of Examples 1-5 was formed.

  It should be noted that the positive electrode formed here is merely formed by intermittently forming a positive electrode active material layer on one side of the current collector, and in fact, intermittently on the other side of the current collector. A positive electrode active material layer is formed. In this way, a positive electrode having a positive electrode active material layer formed on both sides of the current collector is completed. The subsequent battery manufacturing steps are as follows. Although not shown, a negative electrode in which a negative electrode active material layer is formed on both sides of the current collector is completed in the same manner as the positive electrode. A power generation element is configured by laminating a positive electrode, a separator, and a negative electrode in this order, and the power generation element is covered with an aluminum laminate film and filled with an electrolytic solution to manufacture a flat laminated battery.

(Summary)
FIG. 7 summarizes the protruding film thickness ratios at the coating start end when intermittent coating is performed using the coating valves 21 of the comparative example and Examples 1 to 5 described above. Here, the “protrusion film thickness ratio at the coating start end” shown in the rightmost column of FIG. 7 is 3 mm from the point where the coating start end becomes the maximum thickness toward the coating end in the coating direction. It is a value (percent display) obtained by dividing the coating film thickness in the range up to the point where it has passed by the film thickness of the general coating part. The “film thickness of the general coating part” refers to the film thickness of the remaining coating part excluding the coating start end part and the coating end part.

  When the coating valve 21 of the comparative example is used, the coating film thickness ratio at the coating start end portion is large as +6.3 [%], which means that the coating start end portion projects greatly ( (See broken line in FIG. 8). On the other hand, when the coating valve 21 of Example 1 is used, the “protrusion film thickness ratio at the coating start end” is +1.3 [%], which is more positive than when the coating valve 21 of the comparative example is used. Smallness indicates that the coating start end protrudes only small (see the solid line in FIG. 8). FIG. 8 shows the distribution of the coating film thickness after drying when electrodes are formed intermittently using the coating valves of Example 1 and Comparative Example.

  In the coating valve 21 of the comparative example, coating is started by switching the passage cross-sectional area ratio of the internal passage 22b from zero [%] in the fully closed state to 100 [%] in the fully opened state. In such a binary switching operation of the passage cross-sectional area ratio of the internal passage 22b, the inrush pressure of the coating agent increases, resulting in an increase in the discharge amount at the coating start end, and the coating start end. The film thickness of the portion increases as shown by the broken line in FIG. The coating agent applied on the metal current collector 5 becomes the positive electrode active material layer 9. After the coating is completed, in order to increase the adhesive strength between the positive electrode active material layer 9 and the metal current collector 5 or to improve the density of the positive electrode active material layer 9, the positive electrode active material layer is used in the press step after the treatment in the drying step. A process of applying a constant pressure by rolling the roller 9 is performed. The coating start end that protrudes during the processing in the pressing process is likely to peel off locally.

  On the other hand, in the coating bulbs 21 of the first to third embodiments, the passage cross-sectional area ratio of the internal passage 22b is changed in two steps from the small side to the large side.

  For example, in the coating valve 21 of Example 1, the passage cross-sectional area ratio of the internal passage 22b is 25.4 [%] until the stroke amount of the valve rod 27 reaches 60 [%] of Ls. In the range where the stroke amount of the valve rod 27 is 60 [%] to 100 [%] of Ls, the passage cross-sectional area ratio of the internal passage 22b changes to 100 [%].

  In the coating bulb 21 of Example 2, the passage cross-sectional area ratio of the internal passage 22b is 25.4 [%] until the stroke amount of the valve rod 27 reaches 80 [%] of Ls. In the range where the stroke amount of the valve rod 27 is 80 [%] to 100 [%] of Ls, the passage cross-sectional area ratio of the passage 22b changes to 100 [%].

  In the coating bulb 21 of Example 3, the passage cross-sectional area ratio of the internal passage 22b is 21.4 [%] until the stroke amount of the valve rod 27 reaches 40 [%] of Ls. In the range where the stroke amount of the valve rod 27 is 40 [%] to 100 [%] of Ls, the passage cross-sectional area ratio of the internal passage 22b changes to 100 [%].

  Thus, according to the coating valve 21 of Examples 1 to 3, the passage cross-sectional area ratio of the internal passage 22b is changed in two stages from the small side to the large side.

  Next, in the coating bulb 21 of the fourth embodiment, the passage cross-sectional area ratio of the internal passage 22b is changed to three stages of small, medium and large. That is, in the coating valve 21 of Example 4, the passage cross-sectional area ratio of the internal passage 22b is 21.4 [%] until the stroke amount of the valve rod 27 reaches 40 [%] of Ls. In the range where the stroke amount of the valve rod 27 is 40 [%] to 60 [%] of Ls, the passage cross-sectional area ratio of the internal passage 22b changes to 33 [%]. And the passage cross-sectional area ratio of the internal passage 22b becomes 100 [%] in the range of the stroke amount of the valve rod 27 from 60 [%] to 100 [%] of Ls. According to the coating valve 21 of the fourth embodiment, the passage cross-sectional area ratio of the internal passage 22b is changed in three stages, small, medium, and large.

On the other hand, in the coating valve 21 of Example 5, the passage cross-sectional area ratio of the internal passage 22b is 100 [%] until the stroke amount of the valve rod 27 reaches 50 [%] of Ls. When the stroke amount Ls of the valve rod 27 is in the range from 50 [%] to 90 [%], the passage cross-sectional area ratio of the internal passage 22b changes to 21.4 [%]. The passage cross-sectional area ratio of the internal passage 22b is 100 [%] when the stroke amount of the valve rod 27 is in the range of 90 [%] to 100 [%] of Ls. According to the coating valve 21 of the fifth embodiment, the passage cross-sectional area ratio of the internal passage 22b is changed to three stages, large, small, and large. The coating valve 21 of the fifth embodiment is a passage of the internal passage 22b. The cross-sectional area ratio of the internal passage 22b is set to the large side before the cross-sectional area ratio is changed in two stages from the small side to the large side. Even in such a case, as a result, the protruding film thickness ratio at the coating start end is the same level as in the other Examples 1 to 4.

  In this way, if the electrode is manufactured by intermittent application using the application valve 21 of Examples 1 to 4, the passage cross-sectional area ratio is applied so that the discharge amount at the start of application is reduced. Small at the beginning, then larger. That is, by reducing the passage cross-sectional area ratio at the beginning of coating, it is possible to suppress changes in the inrush pressure and discharge amount of the coating agent, so as shown in the rightmost column of FIG. The protruding film thickness ratio can be made uniform in the range of -0.2 [%] to +1.5 [%]. Based on 100 [%], the protruding film thickness ratio at the coating start end is in the range of 99.8 [%] to 101.5 [%]. As a result, poor drying in the subsequent drying process and dropout in the pressing process can be prevented, and a good electrode can be formed.

  The coating valve 21 of the first to third embodiments has the passage cross-sectional area ratio of the internal passage 22b in two stages from the small side to the large side, and the coating valve 21 of the fourth embodiment has a small passage cross-sectional area ratio of the internal passage 22b. However, the number of stages of change is not limited to this. Not only the passage cross-sectional area ratio of the internal passage 22b is changed stepwise (discontinuously) from the small side to the large side, but the passage cross-sectional area ratio of the internal passage 22b is continuously changed from the small side to the large side. It doesn't matter if it does.

  In the coating valve 21 of Examples 1 to 3, the passage cross-sectional area ratio of the internal passage 22b from when the valve body 23 starts to open the upper opening end 22d to just before the stepped portion 24 exits the upper opening end 22d is 25. 4 [%] and 21.4 [%]. In the fourth embodiment, 21.4 [%] and 33 [%] are set, but the present invention is not limited to this. For example, the passage cross-sectional area ratio of the internal passage 22b from when the valve body 23 starts to open the upper opening end 22d to just before the stepped portion 24 exits the upper opening end 22d may be 40% or less. According to the first to fourth embodiments, the passage cross-sectional area ratio of the internal passage 22b when the valve body 23 blocks the upper opening end 22d (opening end) is 0%, and the stepped portion 24 (fourth embodiment). Then, when the passage cross-sectional area ratio of the internal passage 22b after the second stepped portion 31) exits the upper opening end 22d is 100 [%], the valve body 23 starts to open the upper opening end 22d. Since the passage cross-sectional area ratio of the internal passage 22b until the stepped portion 24 just before exiting the upper opening end 22d is 40% or less, it is possible to suppress the change in the projected film thickness ratio at the coating start end. The effective electrode area can be increased. Here, “electrode area” means the area of the positive electrode active material layer when the positive electrode active material layer 9 formed on the planar metal current collector 5 is viewed from a direction orthogonal to the planar metal current collector 5. That is. If the coating film thickness at the coating start edge protrudes from the film thickness of the general coating part, if this protruding part peels off in the subsequent press process, this peeling site will be It becomes thinner than the film thickness, and the battery reaction is lower than the general coating part. Thus, having an area where the battery reaction is lower than the general coating part is said to reduce the effective electrode area. Therefore, according to the embodiment that can suppress the change in the coating film thickness ratio at the coating start end, the effective electrode area can be increased.

  In the coating valve 21 of Examples 1 to 4, when the valve rod 27 strokes at a substantially constant speed to the full opening stroke amount Ls, the axial length of the stepped portion 24 is set to 40 [%] to 80 of the full opening stroke amount Ls. Although it is in the range of [%], it is not limited to this. For example, the axial length of the stepped portion 24 may be in a range from 30 [%] to 95 [%] of the full opening stroke amount Ls. According to the first to fourth embodiments, when the valve rod 27 strokes to the full opening stroke amount Ls, the axial length of the stepped portion 24 is in the range from 30 [%] to 95 [%] of the full opening stroke amount Ls. Therefore, the change in the coating film thickness ratio at the coating start end can be suppressed as compared with the comparative example. As a result, the length of the slope portion of the coating film thickness change at the coating start end becomes shorter than that of the comparative example, so that the effective electrode area can be increased. Here, as shown in FIG. 8, the “slope portion” is a portion where the coating film thickness changes from the coating start end portion without being constant.

  The reason why the axial length of the stepped portion 24 is in the range from 30 [%] to 95 [%] of the fully open stroke amount Ls as described above is to change the passage cross-sectional area ratio of the internal passage 22b to a smaller side. Although time is prescribed | regulated by the axial direction length of the step part 24, it is not restricted to this. For example, when the valve rod 27 is stroked to Ls at a substantially constant speed, the time for changing the passage cross-sectional area ratio of the internal passage 22b to a smaller side is set to 30 [of the time until the stroke amount of the valve rod 27 reaches Ls [ %] To 95 [%]. This also provides the same effect. That is, according to the first to fourth embodiments, when the valve rod 27 is stroked at a substantially constant speed to the full opening stroke amount Ls, the stroke amount of the valve rod 27 is the full opening stroke for the time to change the passage cross-sectional area ratio to the smaller side. Since it is in the range from 30 [%] to 95 [%] of the time to reach the amount Ls, the change in the coating film thickness ratio at the coating start end can be suppressed as compared with the comparative example. As a result, the length of the slope portion of the coating film thickness change at the coating start end becomes shorter than that of the comparative example, so that the effective electrode area can be increased.

  In the coating valve 21 according to the first to fourth embodiments, the valve rod 27 is stroked upward (open side) at a substantially constant speed. However, the present invention is not limited to this. For example, it is conceivable to change the stroke speed when the valve rod 27 strokes to the fully open stroke amount Ls in two or more steps or in a stepless manner (continuously). Specifically, the upward stroke speed of the valve rod 27 is increased initially after opening the valve rod 27, or decreased thereafter, or conversely, it is decreased initially after opening the valve rod 27 and increased thereafter. According to this, it is possible to handle multiple manufacturing conditions with the same equipment without changing the valve structure etc. of the coating valve by simply changing the stroke speed of the valve rod. Improves.

  In the coating valve 21 of Examples 1 to 4, the protruding film thickness ratio at the coating start end is within the range of 99.8 [%] to 101.5 [%] based on 100 [%]. However, it may actually fall within the range of 98 [%] to 102 [%]. According to Examples 1-4, it is an electrode for lithium ion batteries, Comprising: The coating film of the range of 3 mm in the coating direction from the place where it became the maximum thickness of the coating start edge part toward the coating terminal part Since the thickness is in the range of 98% to 102% of the general coating portion, an effective electrode can be manufactured from the coating start portion, and thus a low-cost and high-performance battery can be provided.

  Although the electrode formed using the coating valve 21 of the embodiment and the coating valve 21 of the example has been described as an electrode for a lithium ion secondary battery, it is limited to an electrode for a lithium ion secondary battery. Not a thing.

1 Coating agent tank 2 Die head (application means)
3 coating agent supply passage 4 supply pump 5 metal current collector 6 backup roll 12 return valve (intermittent coating agent supply means)
21 Coating valve (intermittent coating agent supply means)
22 Valve flange 22b Internal passage 22d Upper open end (open end)
23 Valve body 24 Stepped portion (first stepped portion, passage cross-sectional area changing means)
24a Cylindrical side surface 27 Valve rod 28 Valve rod drive motor unit (actuator)
31 Stepped portion of second step 31a Cylindrical side surface

Claims (7)

A tank for storing the coating agent;
A supply pump for pumping the coating agent in the tank;
Coating agent intermittent supply means for intermittently blocking the coating agent supply passage for supplying the coating agent to be pumped,
Coating means for applying the coating agent supplied from the coating agent intermittent supply means on the current collector,
The intermittent application agent supply means changes the passage sectional area of the coating agent supply passage from a smaller side to a larger side until the discharge amount of the coating agent becomes constant from the start of coating. A method for producing an electrode, comprising: A valve flange having an internal passage formed on the inner surface as the coating agent supply passage;
A valve body that blocks and opens one open end of the internal passage of the valve flange;
A valve rod fixed to the valve body;
An actuator for driving the valve rod in the shut-off / opening direction, wherein the passage cross-sectional area changing means moves integrally with the valve body and leaves a space between the inner surface and projects into the internal passage. The method of manufacturing an electrode according to claim 1, wherein the electrode is a part.   The passage cross-sectional area ratio of the internal passage when the valve body blocks the opening end is 0%, and the passage cross-sectional area ratio of the internal passage after the stepped portion exits the opening end is 100%. The passage cross-sectional area ratio of the internal passage from when the valve body starts to open the opening end to just before the stepped portion exits the opening end is 40% or less. 2. The method for producing an electrode according to 2.   When the valve rod strokes to a fully open stroke amount at a substantially constant speed, the time for changing the passage cross-sectional area ratio of the internal passage to a smaller side is the time until the stroke amount of the valve rod reaches the fully open stroke amount. The method for producing an electrode according to claim 3, wherein the range is from 30% to 95%.   The axial length of the stepped portion is in a range from 30% to 95% of the full open stroke amount when the valve rod strokes at a substantially constant speed to the full open stroke amount. A method for producing the electrode according to 1. The method of manufacturing an electrode according to claim 3, wherein a stroke speed when the valve rod is stroked to a fully open stroke amount is changed. An electrode for a lithium ion battery manufactured by the method for manufacturing an electrode according to any one of claims 1 to 6,
The coating film thickness in the range of 3 mm in the coating direction from the maximum thickness at the coating start end to the coating end must be in the range of 98% to 102% of the general coating. An electrode for a lithium ion battery.

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