JP2007066744A - Manufacturing method of coating device and electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating device capable of appropriately controlling a pressure of a coating liquid in a flow passage, and a manufacturing method of an electrode capable of forming the electrode of a high quality with a superior yield by using this. <P>SOLUTION: The coating liquid M is supplied to the flow passage 221 in a coating part 220, and an electrode layer 120 is formed at a current collector 110 by ejecting the liquid from an ejecting hole 222. A retaining groove 241 and a shutoff member 242 are installed at a boundary between the flow passage 221 and the ejecting hole 222. In a process of forming the electrode layer 120, by the contact of a closed face 242A of the shutoff member 242 with the upper wall face 222A of the ejecting hole 222 in the retaining groove 241, shut off is made between the flow passage 221 and the ejecting hole 222. In a process of forming an exposed region 130, by separating the closed face 242A of the shutoff member 242 from the upper wall face 222A, the flow passage 221 and the ejecting hole 222 are communicated. A pressure adjustment valve 252 is opened and closed in cooperation with a shutoff mechanism 240, and the size of a gap between the coating part 220 and the current collector 110 is changed by a moving mechanism 260. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating apparatus for intermittently forming an electrode layer containing an active material on a current collector, and a method for manufacturing an electrode using the coating apparatus.

  In recent years, research and development of secondary batteries used as power sources for portable electronic devices such as mobile phones have been actively promoted. Among these, lithium ion secondary batteries are attracting attention as being capable of realizing a high energy density.

  A lithium ion secondary battery has a configuration in which a positive electrode and a negative electrode are arranged with a separator in between. The positive electrode and the negative electrode are obtained by applying a coating liquid containing an active material to a current collector made of a metal foil to form an electrode layer. Further, the positive electrode and the negative electrode are provided with exposed regions where the electrode layer is not formed and the current collector is exposed. This exposed area is required for attaching a lead for taking out the current to the outside.

FIG. 10 shows an example of a conventional coating apparatus used for forming an electrode layer. This coating apparatus forms the electrode layer 320 on the current collector 310 by discharging the coating liquid M from the coating section (slot die) 420 while conveying the current collector 310 on the holding roll 411. is there. A flow path 421 and a discharge hole (slot) 422 for supplying the coating liquid M are formed inside the coating unit 420. A reciprocating shut-off valve 440 including a valve rod 441 and a drive mechanism 442 is provided at the inlet of the flow path 421. The reciprocating shut-off valve 440 supplies or shuts off the coating liquid M by opening or closing the flow path 421 to form an exposed region 330 where the electrode layer 320 or the current collector 310 is exposed on the current collector 310. Is for.
JP 2003-331830 A

  However, in such a conventional coating apparatus, the thickness of the electrode layer 320 applied immediately after the start of operation is insufficient to a predetermined value, and must be discarded as a defective product, thereby reducing the yield. There was a problem that. That is, when the discharge of the coating liquid M is stopped, the pressure of the coating liquid M in the flow path 421 is in a state balanced with the flow path resistance of the narrow discharge hole 422. When the discharge is resumed here, the pressure of the coating liquid M in the flow path 421 gradually exceeds the flow path resistance pressure of the discharge hole 422, and the discharge starts gradually, as shown in FIG. Continue to rise until it reaches. Therefore, a predetermined coating amount can be obtained from the time when the steady coating pressure is reached, but the electrode layer 320 coated from the start of operation until the steady coating pressure is reached is insufficient. Therefore it becomes thin.

  Further, the conventional coating apparatus has a problem that the thickness of the coating start end portion 320A of the electrode layer 320 is locally increased as shown in FIG. That is, when the flow path 421 is opened by the reciprocating shut-off valve 440 and the coating liquid M is supplied, the pressure of the coating liquid M in the flow path 421 increases. At this time, since the coating liquid M exhibits the behavior of a pseudoplastic fluid, the apparent viscosity of the coating liquid M that is stopped without any shear force acting in the discharge hole 422 is increased in a short time. Therefore, until the shearing force is applied to the coating liquid M in the discharge hole 422 by the pressure of the coating liquid M supplied into the flow path 421 and the flow starts to flow, the flow path resistance in the discharge hole 422 is also high. It is in. Since the pressure of the coating liquid M overcomes the flow path resistance of the discharge hole 422, the coating liquid M is discharged. Therefore, immediately before the start of discharge, the pressure of the coating liquid M in the discharge hole 422 is instantaneously applied to the steady coating. Exceed pressure. After that, the pressure of the coating liquid M in the discharge hole 422 approaches the steady coating pressure as the flow starts, and the coating amount is stabilized. However, an excess of the pressure of the coating liquid M generated at the start of discharge causes an excessive coating amount at the coating start end portion 320A, and the thickness is partially increased.

  Thus, when the thickness of the coating start end portion 320A of the electrode layer 320 is locally thick, as shown in FIG. 12 (B), the electrode layer 320 is pressed with a roller after the electrode layer 320 is formed. In the consolidation step for increasing the density of the coating, strong rolling was locally applied to the coating start end portion 320 </ b> A, resulting in breakage, which could reduce the yield.

  Further, conventionally, since the gap G between the coating section 420 and the current collector 310 is kept constant in advance, the application of the electrode layer 320 is completed as shown in FIG. There has been a problem that the end portion 320B cannot be formed linearly or the splash S of the coating liquid M adheres. This is because even if the flow path 421 is closed by the reciprocating shut-off valve 440 to stop the coating, the coating liquid M cannot be instantaneously blocked due to the residual pressure of the coating liquid M in the discharge hole 422. Because.

  The splash S adhering to the coating end portion 320B causes the following problems. For example, when the splash S adheres to the coating end portion 320B in the positive electrode, as shown in FIG. 13, the positive electrode 521 and the negative electrode 522 are arranged to face each other with the separator 523 interposed therebetween, thereby constituting a battery. In some cases, there is no electrode layer on the negative electrode 522 side facing the splash S on the positive electrode 521. Therefore, if charging / discharging is performed as it is, lithium ions released from the splash S on the positive electrode 521 side are not occluded in the electrode layer on the negative electrode 522 side, but are deposited as metallic lithium, which causes a short circuit failure through the separator 523. It was a factor of yield reduction.

  In order to solve this problem, for example, Patent Document 1 proposes a method in which the gap G between the coating unit 420 and the current collector 310 is positively controlled to suppress the adhesion of the splash S. . However, in order to realize this method, there is room for further improvement in the apparatus configuration, such as the arrangement relationship between the coating unit 420 and the current collector 310 and the travel path of the current collector 310.

  In addition, conventionally, as shown in FIG. 12B as well, there is a problem that the R-shaped portion 320C is formed at the corners of the coating start end portion 320A and the coating end end portion 320B of the electrode layer 320. there were. This is because both ends of the discharge hole 422 have a large flow path resistance due to the influence of the wall surface, so that the discharge is delayed compared to the center at the start of coating, and the discharge stops earlier than the center at the end of coating. Because. This problem has become more prominent as the winding speed of the current collector 310 is increased in order to increase productivity.

  When such an R-shaped portion 320C is formed, as shown in FIG. 14, when the electrode 300 is cut into a predetermined width and a plurality of electrode strips 340 are formed, The length of layer 320 was short of a predetermined value and had to be discarded. Therefore, the effective coating width W of the electrode layer 320 is reduced, which also causes a decrease in yield.

  The present invention has been made in view of such problems, and an object of the present invention is to appropriately control the pressure of the coating liquid in the flow path, and to improve the coating performance. An object of the present invention is to provide an electrode manufacturing method capable of forming high-quality electrodes with a high yield using a coating apparatus.

  A coating apparatus according to the present invention includes a flow path to which a coating liquid is supplied, a coating portion connected to the downstream end of the flow path and having a discharge hole having a flat wall surface, and the flow path and the discharge hole. A holding groove provided at the boundary between the holding groove, and a blocking member that is displaceable to the first position and the second position in the holding groove and is provided with a closing surface at a part of the portion exposed from the holding groove. The blocking member shuts off between the flow path and the discharge hole when the closed surface is in contact with the wall surface facing the holding groove of the discharge hole at the first position, and the closed surface is separated from the wall surface at the second position. Is provided with a blocking mechanism for communicating the flow path and the discharge hole.

  In this coating apparatus, when the blocking member is in the first position in the holding groove, the closing surface of the blocking member contacts the wall surface facing the holding groove of the discharge hole, and the flow path and the discharge hole are blocked. The coating liquid is not discharged from the discharge hole. When the blocking member is in the second position, the closed surface is separated from the wall surface, the flow path and the discharge hole communicate with each other, and the coating liquid is discharged from the discharge hole.

  An electrode manufacturing method according to the present invention is a method for manufacturing an electrode in which an electrode layer containing an active material on a current collector and an exposed region where the current collector is exposed. In the step of forming the exposed region, the blocking member is displaced to the first position to bring the closing surface into contact with the wall surface facing the holding groove of the discharge hole, thereby blocking between the flow path and the discharge hole. In the step of forming the layer, the blocking member is displaced to the second position so that the closed surface is separated from the wall surface so that the flow path and the discharge hole communicate with each other. Thereby, the electrode which has an electrode layer intermittently is manufactured.

  According to the coating apparatus of the present invention, the holding groove is provided at the boundary between the flow path and the discharge hole, and the closing surface of the blocking member is brought into contact with the wall surface of the discharge hole in the holding groove to thereby form the flow path and the discharge hole. Since the flow path and the discharge hole are made to communicate with each other by separating the gap between them or by separating the closing surface of the blocking member from the wall surface, the pressure of the coating liquid in the flow path can be controlled appropriately. Coating performance can be improved. Therefore, according to the electrode manufacturing method of the present invention using this coating apparatus, high-quality electrodes can be formed with high yield.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 5 shows a cross-sectional structure of a secondary battery manufactured using a coating apparatus according to an embodiment of the present invention. This secondary battery 10 is a so-called cylindrical lithium-ion battery, and has a wound body 20 inside a substantially hollow cylindrical battery can 11. The battery can 11 is made of, for example, iron (Fe) plated with nickel (Ni), and has one end closed and the other end open. Inside the battery can 11, a pair of insulating plates 12 and 13 are arranged perpendicular to the winding peripheral surface so as to sandwich the wound body 20.

  At the open end of the battery can 11, a battery lid 14, a safety valve mechanism 15 provided inside the battery lid 14 and a heat sensitive resistance element (Positive Temperature Coefficient; PTC element) 16 are interposed via a gasket 17. It is attached by caulking, and the inside of the battery can 11 is sealed. The battery lid 14 is made of, for example, the same material as the battery can 11. The safety valve mechanism 15 is electrically connected to the battery lid 14 via the heat sensitive resistance element 16, and the disk plate 15A is reversed when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating. Thus, the electrical connection between the battery lid 14 and the wound body 20 is cut off. When the temperature rises, the heat sensitive resistance element 16 limits the current by increasing the resistance value and prevents abnormal heat generation due to a large current. The gasket 17 is made of, for example, an insulating material, and asphalt is applied to the surface.

  The wound body 20 is formed by laminating a positive electrode 21 and a negative electrode 22 with a separator 23 interposed therebetween, and a center pin 24 made of stainless steel or the like is inserted in the center. The positive electrode 21 is a positive electrode current collector made of, for example, an aluminum foil, and an electrode layer containing a positive electrode active material such as a lithium-containing compound, and the negative electrode 22 is made of, for example, a negative electrode current collector made of copper foil or the like. The body is provided with an electrode layer including a negative electrode active material such as a carbon material capable of inserting and extracting lithium. The separator 23 is made of, for example, a porous film such as polypropylene, and the separator is impregnated with an electrolytic solution in which an electrolyte salt such as a lithium salt is dissolved in a non-aqueous solvent such as carbonate. Yes. A positive electrode lead 25 made of aluminum (Al) or the like is connected to the positive electrode 21 of the wound body 20, and a negative electrode lead 26 made of nickel or the like is connected to the negative electrode 22. The positive electrode lead 25 is electrically connected to the battery lid 14 by being welded to the safety valve mechanism 15, and the negative electrode lead 26 is welded to and electrically connected to the battery can 11.

  FIG. 1 shows an overall configuration of a coating apparatus used for manufacturing the positive electrode 21 or the negative electrode 22 of the secondary battery 10. This coating apparatus forms an electrode layer 120 containing an active material on the current collector 110 and an exposed region 130 where the current collector 110 is exposed, while holding the current collector 110 by a holding roll 211. A transport unit 210 that transports the coating unit 220 is disposed opposite to the current collector 110 on the holding roll 211.

  The transport unit 210 includes an unwinding device and a winding device (both not shown) for the current collector 110, and the current collector 110 is unwound at a constant speed from the unwinding device, After the coating liquid M is applied by the coating unit 220, it is wound around the winding device at a constant speed. The holding roll 211 rotates clockwise as indicated by an arrow A, for example, so as to hold the current collector 110 and convey it upward to pass through the application unit 220. In addition to the holding roll 211, an appropriate number of guide rolls (not shown) are disposed in the transport unit 210 according to the transport path of the current collector 110.

  The coating unit 220 is constituted by, for example, a closed slot die and has a flow path 221 to which a coating liquid M containing an active material is supplied. A discharge hole 222 is connected to the downstream end of the flow path 221. The discharge hole 222 is narrower than the flow path 221 and its wall surface is flat. Further, the discharge hole 222 extends from the downstream end of the flow path 221 in a direction intersecting the flow path 221, and the tip thereof is opened toward the current collector 110 on the holding roll 211. On the other hand, a fixed amount supply pump 230 is connected to the upstream end of the flow path 221 through a pipe 231. The coating amount per unit time is adjusted by the supply amount of the coating liquid M from the fixed amount supply pump 230. Further, a pressure detector 223 for detecting the pressure of the coating liquid M in the flow path 221 is attached in the middle of the flow path 221.

  A blocking mechanism 240 is provided at the boundary between the flow path 221 and the discharge hole 222. The blocking mechanism 240 is for blocking or communicating the flow path 221 and the discharge hole 222. For example, a holding groove 241 having an arcuate cross section provided at a corner where the flow path 221 and the discharge hole 222 intersect with each other, and the holding groove 241. It is comprised with the interruption | blocking member 242 provided. The blocking member 242 can be displaced to the first position and the second position by rotating in the holding groove 241, and the portion that contacts the holding groove 241 during the rotation has, for example, an arc shape in cross section. . Further, the blocking member 242 is provided with a flat closing surface 242A at a part of the portion exposed from the holding groove 241. As shown in FIG. The upper wall surface 222A is contacted to block between the flow path 221 and the discharge hole 222, and the closed surface 242A is separated from the upper wall surface 222A at the second position as shown in FIG. To communicate with. Thereby, in this coating apparatus, the pressure of the coating liquid M in the flow path 221 can be appropriately controlled, and high-quality electrodes can be formed with high yield.

  Further, since the blocking mechanism 240 is provided at the boundary between the flow path 221 and the discharge hole 222, the coating liquid M from the discharge hole 222 is not affected by the pressure of the coating liquid M in the flow path 221. Discharging and stopping thereof can be directly controlled. On the other hand, in the past, since the coating start / interruption was controlled by the reciprocating shut-off valve at the upstream end of the flow path, there is a large pressure loss between the reciprocating shut-off valve and the discharge hole. Due to the presence of pipes and flow paths, there was a time delay in controlling the start and stop of coating, and it was not possible to handle high-speed coating.

  Further, the blocking member 242 has a coating liquid guide portion 242B that gradually narrows the flow path 221 toward the downstream side, upstream of the closed surface 242A of the portion exposed from the holding groove 241. When the coating liquid guide part 242B is not provided, the size of the flow path 221 changes suddenly, so that there is a possibility that the highly viscous coating liquid M will not easily pass. By providing the coating liquid guide portion 242B, a gentle flow path 221 can be formed and introduced into the discharge hole 222 without obstructing the flow of the coating liquid M.

  The coating liquid guiding part 242B may be a curved surface or a flat surface, but is preferably constituted by a flat surface. This is because a flat surface is easier to manufacture than a curved surface.

  In addition, the coating liquid guide portion 242B may be a single plane, but is preferably configured by a plurality of, for example, two planes 242B1 and 242B2. This is because a more gentle flow path 221 can be formed, which is advantageous for stably developing the viscous boundary layer by the wall effect, and the strength of the blocking member 242 can be increased.

  Furthermore, it is preferable that these two flat surfaces 242B1 and 242B2 have larger areas toward the upstream side. In this way, as shown in an enlarged view in FIG. 3, the upstream plane 242B2 has (ab) × Pm [Pa] due to the influence of the pressure Pm of the coating liquid M in the flow path 221. ] The couple F represented by] is applied. The couple F acts in a direction to rotate the blocking member 242 around the rotation axis C in a direction in which the closing surface 242A is in close contact with the upper wall surface 222A. Therefore, it is possible to further improve the shielding property and sealing property between the flow path 221 and the discharge hole 222.

  As such a blocking member 242, for example, a member having a circular cross section, preferably a cylinder, with chamfered surfaces 242 </ b> B <b> 1 and 242 </ b> B <b> 2 of the coating surface 242 </ b> A and the coating liquid guiding part 242 </ b> B is preferable.

  Further, as shown in FIG. 1, the coating apparatus has an adjustment path 251 connected to the flow path 221, and a pressure adjustment valve 252 is provided in the adjustment path 251. For example, the adjustment path 251 is provided by branching from a pipe 231 connected to the flow path 221. The pressure adjustment valve 252 controls the pressure of the coating liquid M in the flow path 221 by opening or closing the adjustment path 251 in cooperation with the blocking mechanism 240, and is provided directly connected to the flow path 221. Therefore, the pressure of the coating liquid M in the flow path 221 can be controlled with high reactivity and high reproducibility. In addition, the coating liquid M discharged | emitted from the adjustment path 251 is collect | recovered, and is supplied again to the coating part 220. FIG.

  Such a coating part 220 is fixed to a moving mechanism 260 constituted by, for example, an air cylinder. The moving mechanism 260 changes the size of the gap G between the coating unit 220 and the current collector 110 by moving the coating unit 220 in the direction of arrow B parallel to the extension direction of the discharge hole 222. Is. For example, the moving mechanism 260 sets the size of the gap G to a constant coating gap G1 corresponding to the target thickness of the electrode layer 120 in the step of forming the electrode layer 120, as described later, and the exposed region 130 In the forming step, the non-coating gap G2 is larger than the steady coating gap G1. The non-coating gap G2 may be equal to the steady coating gap G1.

  Further, the moving mechanism 260 can arbitrarily change the size of the gap G even during the formation of the electrode layer 120. For example, in the period immediately after the start of the step of forming the electrode layer 120, the size of the gap G is set to a coating start gap G3 that is smaller than the steady coating gap G1. On the other hand, in the period immediately before the end of the step of forming the electrode layer 120, the size of the gap G is set to a coating end gap G4 smaller than the steady coating gap G1. By doing in this way, in this coating apparatus, while being able to improve the local dispersion | variation in the thickness of the electrode layer 120, it can raise a shape precision. The coating start time gap G3 may be equal to the steady coating gap G1. Further, the coating end gap G4 may be equal to the steady coating gap G1.

  The steady coating gap G1, the non-coating gap G2, the coating start gap G3, and the coating end gap G4 vary depending on the type of the coating liquid M and the winding speed of the current collector 110. It is set within a range of 0.01 ≦ G ≦ 1.00 [mm].

  FIG. 4 is a timing chart for explaining an electrode manufacturing method using the coating apparatus. In this electrode manufacturing method, the operation is stopped at time t1 and the preliminary operation process is performed until time t2. The first step of forming the electrode layer 120 is performed from time t2 to time t3, and the step of forming the exposed region 130 is performed from time t3 to time t4. From time t4 to time t5, the step of forming the electrode layer 120 is performed again, and from time t5 to time t6, the step of forming the exposed region is performed again. Thereafter, similarly, the step of forming the electrode layer 120 and the step of forming the exposed region 130 are alternately performed.

  When the operation is stopped, the pressure of the coating liquid M in the flow channel 221 of the coating unit 220 is in a state balanced with the flow channel resistance in the flow channel 221. At this time, the blocking member 242 of the blocking mechanism 240 is set to the first position, and the closing surface 242A is brought into contact with the upper wall surface 222A to block between the flow path 221 and the discharge hole 222 (blocking mechanism; closing). Further, the adjustment path 251 is closed by the pressure adjustment valve 252 (pressure adjustment valve; closed), and the metering pump 230 is stopped. The size of the gap G is set to the non-coating gap G2.

  In the preliminary operation step, the operation of the fixed amount supply pump 230 is started and the adjustment path 251 is opened by the pressure adjustment valve 252 (pressure adjustment valve; release), and the supply of the coating liquid M to the flow path 221 is started (time). t1). The pressure of the coating liquid M in the flow path 221 is detected by the pressure detector 223, and the blocking member 242 of the blocking mechanism 240 is set to the first position until the predetermined steady coating pressure P is reached. The space between the holes 222 is blocked (blocking mechanism; closing). As a result, the electrode layer 120 can be formed after sufficiently increasing the pressure of the coating liquid M in the flow channel 221, and the electrode layer 120 can be formed with a desired thickness from the first time. Insufficient thickness of the electrode layer 120 can be eliminated. In the preliminary operation step, the size of the gap G is maintained as the non-coating gap G2.

  Here, the steady coating pressure P varies depending on the type of the coating liquid M and the winding speed of the current collector 110, but is set within a range of 0.02 ≦ P ≦ 0.10 [MPa], for example.

  When the pressure of the coating liquid M in the flow path 221 reaches the steady coating pressure P, before starting the process of forming the electrode layer 120, the blocking member 242 of the blocking mechanism 240 is displaced to the second position. After the closed surface 242A is separated from the upper wall surface 222A, the flow path 221 and the discharge hole 222 are communicated (time t11, blocking mechanism; open), and then the adjustment path 251 is closed by the pressure adjustment valve 252 (time t12, (Pressure adjusting valve; closed), coating of the coating liquid M is started (time t2), and the step of forming the electrode layer 120 is performed.

  At this time, coating is started while the pressure of the coating liquid M in the flow path 221 is maintained at the steady coating pressure P by appropriately setting the timing at which the adjustment path 251 is closed by the pressure regulating valve 252. Can do. Thereby, when the pressure of the coating liquid M in the flow path 221 is lower than the steady coating pressure P, the R shape that is likely to occur at the corner of the coating start end 120A is suppressed, and the effective coating of the electrode layer 120 is performed. The width can be increased. The proper closing timing of the pressure regulating valve 252 varies depending on the type of the coating liquid M and the winding speed of the current collector 111.

  In addition, appropriately setting the timing for closing the adjustment path 251 by the pressure adjustment valve 252 in this way suppresses the pressure of the coating liquid M in the flow path 221 from exceeding the steady coating pressure P, and the coating is performed. The amount of the coating liquid M present in the gap G between the working part 220 and the current collector 110 is also suppressed. In addition to this, during the period immediately after the start of the step of forming the electrode layer 120 (time t2 to time t21), the coating unit 220 is moved by the moving mechanism 260 so that the size of the gap G is set to the steady coating gap. The coating start time gap G3 is smaller than G1. By the above, it can suppress that the thickness of the coating start end part 120A of the electrode layer 120 becomes large locally, and strong rolling is applied locally to the coating start end part 120A in the subsequent consolidation step. Breaking can be prevented.

  In the step of forming the electrode layer 120, the blocking member 242 of the blocking mechanism 240 is set to the second position so that the flow path 221 and the discharge hole 222 are communicated (blocking mechanism: open), and the adjustment path 251 is closed by the pressure adjustment valve 252. (Pressure regulating valve; closed). The size of the gap G is a steady coating gap G1.

  Before the step of forming the electrode layer 120 is completed, the blocking member 242 of the blocking mechanism 240 is displaced to the first position to block between the flow path 221 and the discharge hole 222 (time t22, blocking mechanism; closing) ) After opening the adjustment path 251 with the pressure adjustment valve 252 (time t23, pressure adjustment valve; release), the application of the coating liquid M is completed (time t3), and the step of forming the electrode layer 120 is completed. .

  At this time, by appropriately setting the timing at which the adjustment path 251 is opened by the pressure adjustment valve 252, the coating is completed while the pressure of the coating liquid M in the flow path 221 is maintained at the steady coating pressure P. Can do. Thereby, when the pressure of the coating liquid M in the flow path 221 is lower than the steady coating pressure P, the R shape that tends to occur at the corner of the coating end edge 120B is suppressed, and the effective coating of the electrode layer 120 is performed. The width can be increased.

  In addition, by appropriately setting the timing for opening the adjustment path 251 by the pressure adjustment valve 252 in this way, it is possible to suppress the pressure of the coating liquid M in the flow path 221 from exceeding the steady coating pressure P, and to apply the coating. The amount of the coating liquid M present in the gap G between the working part 220 and the current collector 110 can also be suppressed. In addition to this, during a period immediately before the end of the step of forming the electrode layer 120 (time t24 to time t3), the coating unit 220 is moved by the moving mechanism 260 so that the size of the gap G is changed to the steady coating. The coating end gap G4 is smaller than the gap G1. As described above, the coating liquid M present in the gap G between the coating part 220 and the current collector 110 is cut off on the current collector 110 to improve the linearity of the coating end edge 120B and at the same time the coating liquid M. Can be prevented from adhering.

  The coating end gap G4 and the coating start gap G3 can be set independently. For example, the coating end gap G4 may be narrower than or equal to the coating start gap G3. Or it may be wider. Note that the coating start gap G3 may be equal to the steady coating gap G1. Alternatively, the coating end gap G4 may be made equal to the steady coating gap G1.

  In the process of forming the exposed region 130, the blocking member 242 of the blocking mechanism 240 is set to the first position to block between the flow path 221 and the discharge hole 222 (blocking mechanism; closing), and the adjustment path 251 is opened by the pressure adjustment valve 252. Open (pressure regulating valve; open). The size of the gap G is the non-coating gap G2. The non-coating gap G2 may be made equal to the steady coating gap G1.

  Before starting the process of forming the electrode layer 120 again, the flow path 221 and the discharge hole 222 are made to communicate with each other by displacing the blocking member 242 of the blocking mechanism 240 to the second position (time t31, blocking mechanism; open). Subsequently, after the adjustment path 251 is closed by the pressure adjustment valve 252 (time t32, pressure adjustment valve; closure), the application of the coating liquid M is started (time t4) to form the electrode layer 120. Do.

  Since the subsequent steps are the same as the initial step of forming the electrode layer 120 and the subsequent step of forming the exposed region 130, detailed description thereof will be omitted.

  Thus, in the present embodiment, the holding groove 241 is provided at the boundary between the flow path 221 and the discharge hole 222, and the closing surface 242A of the blocking member 242 is brought into contact with the upper wall surface 222A of the discharge hole 222 in the holding groove 241. Accordingly, the flow path 221 and the discharge hole 222 are blocked, or the closing surface 242A of the blocking member 242 is separated from the upper wall surface 222A so that the flow path 221 and the discharge hole 222 communicate with each other. The pressure of the inner coating liquid M can be appropriately controlled, and the coating performance can be enhanced. Therefore, by manufacturing the positive electrode 21 or the negative electrode 22 of the secondary battery 10 using this coating apparatus, the high-quality positive electrode 21 or the negative electrode 22 can be formed with a high yield.

  In particular, since the coating liquid guide 242B that gently narrows the flow path 221 toward the downstream side is provided on the upstream side of the closing surface 242A of the blocking member 242, the discharge is performed without hindering the flow of the coating liquid M. It can be discharged from the hole 222.

  In addition, the coating liquid guide portion 242B is configured by two planes 242B1 and 242B2, and the area of the two planes 242B1 and 242B2 is increased toward the upstream side, so the couple F applied to the upstream plane 242B2 As a result, it is possible to further improve the shielding property and sealing property between the flow path 221 and the discharge hole 222.

  Further, in the preliminary operation step before the first step of forming the electrode layer 120, after the supply of the coating liquid M to the flow path 221 is started, the pressure of the coating liquid M in the flow path 221 is constantly applied. Since the blocking mechanism 240 blocks the flow path 221 and the discharge hole 222 until the working pressure P is reached, the pressure of the coating liquid M in the flow path 221 is sufficiently increased before the electrode 120 is moved. The electrode layer 120 can be formed with a desired thickness from the first time, and the thickness shortage of the electrode layer 120 immediately after the start of operation can be eliminated.

  In addition, the pressure of the coating liquid M in the flow path 221 is controlled by opening or closing the adjustment path 251 by the pressure control valve 252 in cooperation with the shutoff mechanism 240, and the size of the gap G by the moving mechanism 260. Since the thickness of the coating start end 120A of the electrode layer 120 is prevented from being locally increased, the electrode is prevented from being broken during the consolidation process, or the coating end end 120B is straight. It is possible to suppress the adhesion of splashes by increasing the property, and to prevent the R-shaped portion from being formed at the corners of the coating start end portion 120A and the coating end end portion 120B.

  Further, specific embodiments of the present invention will be described in detail.

(Example)
The positive electrode 21 was produced by the coating apparatus described in the above embodiment. At that time, according to the manufacturing method shown in FIG. 4, the current collector 110 made of an aluminum foil having a thickness of 18 μm, the electrode layer 120 containing lithium-cobalt composite oxide (LiCoO ₂ ) as a positive electrode active material, and the current collector 110 The exposed region 130 was exposed.

  As a comparative example with respect to the present embodiment, this embodiment is used except that a conventional coating apparatus in which the start / end of coating is controlled by a reciprocating shut-off valve 440 as shown in FIG. 10 is used. In the same manner, a positive electrode was formed.

  About each of an Example and a comparative example, transition of the average coating amount by coating time was investigated. The result is shown in FIG. In addition, for the positive electrodes of the obtained Examples and Comparative Examples, after drying the electrode layer, the relationship between the distance from the coating start end and the thickness, the shape of the coating end, and the coating start end The shape of the corners of the part and the end of the coating end were examined. The results are shown in FIGS. 7, 8 and 9, respectively. FIG. 8 and FIG. 9 are photographs of the corresponding part.

  As can be seen from FIG. 6, in the example, a stable average coating amount was obtained immediately after the start of operation, whereas in the comparative example, the average coating amount immediately after the start of operation was small and gradually increased. It took time to reach a stable value. That is, if the coating apparatus described in the above embodiment is used and the preliminary operation process is performed to sufficiently increase the pressure of the coating liquid M in the flow path 221, the formation of the electrode layer 120 is started. It was found that the average coating amount can be kept constant from the start to the end of the operation, and an insufficient thickness of the electrode layer 220 immediately after the start of operation can be suppressed.

  Further, in the example, as can be seen from FIG. 7, compared with the comparative example, the variation in the thickness of the coating start end portion 120A of the electrode layer 120 is reduced, and as shown in FIG. The splash S did not adhere to 120B, and the linearity was improved. Furthermore, as shown in FIG. 9, the corners of the coating start end portion 120A and the coating end end portion 120B are rectangular, and no R-shaped portion is formed. That is, the pressure of the coating liquid M in the flow path 221 is controlled and moved by opening or closing the pressure control valve 252 in cooperation with the blocking mechanism 240 using the coating apparatus described in the above embodiment. It was found that if the size of the gap G is appropriately controlled by the mechanism 260, local variations in the thickness of the electrode layer 120 can be suppressed and the shape accuracy can be improved.

  As the negative electrode 22, a current collector 110 made of a copper foil having a thickness of 13 μm, an electrode layer 120 containing a carbon material as a negative electrode active material, and an exposed region 130 where the current collector 110 is exposed are the same as in the above example. As a result, the same results as in the above example were obtained.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, the configuration of the coating apparatus has been specifically described, but the configuration of the coating apparatus is not limited to the above-described embodiments and examples. For example, in the above embodiments and examples, the blocking mechanism 240 is provided on the lower wall surface side of the discharge hole 222 and the closing surface 242A of the blocking member 242 is brought into contact with the upper wall surface 222A of the discharge hole 222. As described above, the position where the blocking mechanism 240 is provided is not particularly limited as long as the closing surface 242A of the blocking member 242 can be brought into contact with the wall surface facing the holding groove 241 of the discharge hole 222. Therefore, for example, the blocking mechanism 240 may be provided on the upper wall surface side of the discharge hole 222, and the closing surface 242A of the blocking member 242 may be brought into contact with the lower wall surface of the discharge hole 222.

  Further, for example, in the above-described embodiment and examples, the case where the pressure adjustment valve 252 is connected to the pipe 231 that supplies the coating liquid M from the constant supply pump 230 to the coating unit 220 has been described. The regulating valve 252 may be connected by, for example, an independent piping path that is directly connected to the flow path 221.

  Further, for example, in the above embodiment and examples, the closing surface 242A is a flat surface, and the closing surface 242A and the upper wall surface 222A are in surface contact with each other, thereby blocking between the flow path 221 and the discharge hole 222. However, the closing surface 242A only needs to be able to block between the flow path 221 and the discharge hole 222, and at that time, the closing surface 242A and the upper wall surface 222A do not necessarily need to be in surface contact. Line contact may be used. Further, if the contact portion of the blocking member 242 with the upper wall surface 222A is made of a flexible elastic deformation material, the closing surface 242A may not be a completely flat surface but may be a rough flat surface. Further, the blocking member 242 may have a corrugated cross-sectional shape as long as it has a shape that follows the upper wall surface 222A.

  Further, for example, in the above-described embodiment and examples, the discharge hole 222 extends from the downstream end of the flow path 221 in the direction intersecting the flow path 221, and the holding groove 241 is formed at the corner where both intersect. Although the case where it is provided has been described, the flow path 221 and the discharge hole 222 may be formed on the same straight line, and the holding groove 241 may be provided at the boundary between them.

  In addition, for example, in the above-described embodiments and examples, the holding groove 241 has an arc shape in cross section, and the portion that contacts the holding groove 241 when the blocking member 242 rotates is also in an arc shape in cross section. Although described, the shapes of the holding groove 241 and the blocking member 242 are not limited to the examples described in the above embodiments and examples. That is, the shape of the portion that contacts the holding groove 241 when the blocking member 242 rotates is set so that the coating liquid M does not enter the holding groove 241 from the gap between the holding groove 241 and the blocking member 242. There is a need. For this purpose, at least the portion that contacts both ends of the arc of the holding groove 241 at the time of rotation only needs to have a circular arc cross section, and the other portion may be a plane or a polygon. On the other hand, the holding groove 241 is not particularly limited to a circular arc shape as long as it has a shape that does not prevent the blocking member 242 from rotating inside.

  Furthermore, for example, in the above-described embodiments and examples, the case where the coating liquid M is continuously supplied by the constant supply pump 230 has been described. However, in parallel with the above-described electrode manufacturing method, the flow path by the pump is used. You may enable it to control the pressure of the coating liquid M in 221. FIG.

  In addition, in the above-described embodiment and example, the holding roll 211 of the transport unit 210 rotates clockwise as indicated by the arrow A, so that the current collector 110 is transported upward while being retained. Although the case where the coating unit 220 is passed has been described, the rotation direction of the holding roll 211 and the conveyance direction of the current collector 110 are not particularly limited. For example, the holding roll 211 may convey the current collector 110 downward by rotating counterclockwise.

  Furthermore, the positional relationship between the coating unit 220 and the current collector 110, the discharge direction of the coating liquid M, the travel route of the current collector 110, and the like are not limited to the examples described in the above embodiments and examples. .

  In addition, for example, in the above-described embodiment, the configuration of the secondary battery has been specifically described, but the configuration of the secondary battery is not limited to the above-described embodiment. For example, in the above embodiment, a cylindrical secondary battery has been described, but the present invention can also be applied to secondary batteries of other shapes. Further, for example, in the above embodiment, the case where the wound body 20 has a structure in which the positive electrode 21 and the negative electrode 22 are stacked and wound is described. However, the positive electrode 21 and the negative electrode 22 are folded or stacked. May be.

  Furthermore, for example, in the above-described embodiments and examples, the lithium ion secondary battery has been described as an example. However, the present invention can be applied to other secondary batteries other than the lithium ion secondary battery. it can.

  In addition, for example, in the above-described embodiments and examples, the case where the positive electrode 21 and the negative electrode 22 of the secondary battery 10 are manufactured by the coating apparatus of the present invention has been described. However, the present invention is not necessarily limited thereto. It is also possible to manufacture a positive electrode and a negative electrode of a primary battery having the same structure as the secondary battery 10.

  Furthermore, for example, in the above-described embodiment, the case where an electrolytic solution that is a liquid electrolyte is used as a solvent has been described. However, another electrolyte may be used instead of the electrolytic solution. Other electrolytes include, for example, a gel electrolyte in which an electrolyte is held in a polymer compound, a solid electrolyte having ionic conductivity, a mixture of a solid electrolyte and an electrolyte, or a solid electrolyte and a gel electrolyte. And a mixture thereof.

  In addition, for example, in the above-described embodiments and examples, the case where lithium is used as the electrode reactant has been described. However, other groups in the long-period periodic table such as sodium (Na) or potassium (K) are used. The present invention can also be applied to the case of using elements, Group 2 elements in the long-period periodic table such as magnesium or calcium (Ca), other light metals such as aluminum, lithium, or alloys thereof. The same effect can be obtained. At that time, a negative electrode active material, a positive electrode active material, a solvent, or the like that can occlude and release the electrode reactant is selected according to the electrode reactant.

  Furthermore, for example, in the above-described embodiment, the case where both the positive electrode 21 and the negative electrode 22 are manufactured by the coating apparatus and the manufacturing method of the present invention has been described. However, at least one of the positive electrode 21 and the negative electrode 22 is the present invention. You may make it manufacture with the coating apparatus and manufacturing method of these.

  In addition, in the above-described embodiments and examples, the coating apparatus of the present invention is applied to the production of battery electrodes, and the current collector 110 is coated with a coating liquid M containing an active material, and the electrode layer 120 and Although the case where the exposed region 130 is formed has been described, the present invention is not limited to the manufacture of a battery, and can be widely applied when it is necessary to intermittently apply a coating liquid to an object.

It is a figure which represents roughly the structure of the coating device which concerns on one embodiment of this invention. It is a figure for demonstrating operation | movement of the interruption | blocking member shown in FIG. It is a figure which expands and represents a blocking member. It is a figure for demonstrating the manufacturing method of the electrode by a coating device. It is sectional drawing showing the structure of the secondary battery manufactured using the coating device. It is a figure showing the result of the Example of this invention. It is a figure showing the result of the Example of this invention. It is a figure for demonstrating the shape of the coating completion end part of the electrode layer manufactured in the Example of this invention contrasting with a comparative example. It is a figure for demonstrating the shape of the edge of the coating start edge part of the electrode layer manufactured in the Example of this invention, and the coating completion edge part, making it a comparative example. It is a figure which represents roughly the structure of the conventional coating apparatus. It is a figure for demonstrating the change of the pressure of the coating liquid in the flow path in the conventional coating apparatus. It is a figure for demonstrating the shape of the electrode layer formed with the conventional coating apparatus, and its problem. It is a figure for demonstrating the problem at the time of comprising a battery using the positive electrode formed with the conventional coating apparatus. It is a figure for demonstrating the other problem of the electrode layer formed with the conventional coating apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Battery can, 12, 13 ... Insulation board, 14 ... Battery cover, 15 ... Safety valve mechanism, 16 ... Heat sensitive resistance element, 17 ... Gasket, 20 ... Electrode body, 21 ... Positive electrode, 22 ... Negative electrode, 23 ... Separator, 24 ... Center pin, 25 ... Positive electrode lead, 26 ... Negative electrode lead, 110 ... Current collector, 120 ... Electrode layer, 120A ... Coating start end, 120B ... Coating end end, 130 ... Exposed area, 210 ... Conveyance , 211, holding roll, 220, coating unit, 221, flow path, 222, discharge hole, 223, pressure detector, 230, metering pump, 240, blocking mechanism, 241, holding groove, 242, blocking member, 242A ... closed surface, 242B ... coating solution guide, 242B1, 242B2 ... flat surface, 251 ... adjustment path, 252 ... pressure regulating valve, 260 ... moving mechanism, M ... coating solution.

Claims (12)

A flow path through which the coating liquid is supplied, and a coating section connected to the downstream end of the flow path and having a discharge hole having a flat wall surface;
A holding groove provided at the boundary between the flow path and the discharge hole, and can be displaced to a first position and a second position in the holding groove, respectively, and a part of a portion exposed from the holding groove A blocking member provided with a closing surface, wherein the blocking member is in a first position between the flow path and the discharge hole by contacting the closing surface with a wall surface facing the holding groove of the discharge hole. And a blocking mechanism that allows the flow path and the discharge hole to communicate with each other when the closed surface is separated from the wall surface at the second position. An adjustment path connected to the flow path;
A pressure regulating valve that is provided in the regulation path and controls the pressure of the coating liquid in the channel by opening or closing the regulation path in cooperation with the blocking mechanism. The coating apparatus according to claim 1. The coating apparatus according to claim 1, further comprising a moving mechanism that moves the coating unit in parallel with an extension direction of the discharge hole. The said interruption | blocking member has a coating liquid guide part which narrows the said flow path toward a downstream in the upstream from the said closing surface of the part exposed from the said holding groove. Coating equipment. The coating apparatus according to claim 4, wherein the coating liquid guide section is configured by a plurality of planes, and the plurality of planes have an area that increases toward the upstream side. An electrode manufacturing method comprising an electrode layer containing an active material in a current collector and an exposed region where the current collector is exposed,
A flow path to which a coating liquid containing an active material is supplied, a coating section connected to the downstream end of the flow path and having a discharge wall having a flat wall surface; the flow path and the discharge hole; And a blocking member that is displaceable to a first position and a second position in the holding groove, and is provided with a closing surface at a part of the portion exposed from the holding groove. Using a coating device equipped with a blocking mechanism including
In the step of forming the exposed region, the blocking member is displaced to the first position to bring the closing surface into contact with the wall surface facing the holding groove of the discharge hole, so that the gap between the flow path and the discharge hole is reached. Shut off
In the step of forming the electrode layer, the flow path and the discharge hole are communicated with each other by displacing the blocking member to the second position to separate the closed surface from the wall surface. . Including a preliminary operation step before performing the first step of forming the electrode layer,
In the preliminary operation step, after the supply of the coating liquid to the flow path is started, the blocking mechanism causes the flow path and the discharge hole to flow until the pressure of the coating liquid in the flow path reaches a predetermined value. The method for producing an electrode according to claim 6, wherein the gap is blocked. In the step of providing a pressure adjustment valve in the adjustment path branched from the flow path and forming the exposed region, the adjustment path is opened by the pressure adjustment valve, and in the step of forming the electrode layer, the pressure adjustment valve is used. The said adjustment path is closed. The manufacturing method of the electrode of Claim 6 characterized by the above-mentioned. Before starting the step of forming the electrode layer, the flow path and the discharge hole are made to communicate with each other by the blocking mechanism, and then the adjustment path is closed by the pressure adjustment valve, and then the coating liquid The process of starting the coating and forming the electrode layer,
Before the step of forming the electrode layer is completed, the blocking mechanism cuts off the flow path and the discharge hole, and then the pressure adjusting valve opens the adjustment path, and then the coating is performed. The method for producing an electrode according to claim 8, wherein the step of forming the electrode layer is finished by finishing the application of the working liquid. In the step of forming the electrode layer, the size of the gap between the coating portion and the current collector is changed by moving the coating portion in parallel with the extension direction of the discharge hole. The electrode according to claim 6, wherein a constant coating gap corresponding to a target thickness of the layer is formed, and in the step of forming the exposed region, the non-coating gap is larger than the steady coating gap. Manufacturing method. The electrode manufacturing method according to claim 10, wherein in the period immediately after the start of the step of forming the electrode layer, the size of the gap is set to a coating start gap smaller than the steady coating gap. Method. The electrode manufacturing method according to claim 10, wherein, in a period immediately before the end of the step of forming the electrode layer, the size of the gap is a gap at the end of coating smaller than the steady coating gap. Method.

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