Method for manufacturing electrode stack

Abstract

To provide a manufacturing method for an electrode laminate that can detect tab positions in a plurality of laminated electrodes.SOLUTION: A manufacturing method for an electrode laminate 1 is for manufacturing the electrode laminate 1 formed by laminating a plurality of negative electrodes 3 each having a negative electrode body 31A formed in a sheet shape and a tab 31B protruding in a first direction Z from one side 311 of the negative electrode body 31A in a second direction Y perpendicular to the first direction Z. Light is irradiated onto a tab 31B of the electrode laminate 1 from a third direction X orthogonal to the second direction Y, reflected light of the light irradiated onto the tab 31B is received from a fourth direction R orthogonal to the second direction Y and inclined to the third direction X, and on the basis of the received reflected light, a position of the tab 31B in the third direction X is detected.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for producing an electrode stack. [Background technology]

[0002] Conventionally, there has been known an electrode laminate constituting a secondary battery, which is constructed by alternately stacking sheet-shaped positive and negative electrodes with separators interposed therebetween (see Patent Document 1). In such an electrode laminate, for example, tabs protrude from one side of each of the positive and negative electrodes, and the positive and negative electrodes and separators are stacked in a direction perpendicular to the protruding direction of the tabs.

[0003] Although stacking misalignment may occur in multiple stacked positive electrodes and negative electrodes, the tabs of the positive and negative electrodes are joined to the electrode terminals in an accumulated and welded state, and therefore it is preferable to keep the stacking misalignment that occurs in the tabs within a predetermined range.

[0004] In order to keep the stacking misalignment that occurs in the tab within a predetermined range, it is important to grasp the amount of stacking misalignment of the tab. For example, when grasping the amount of stacking misalignment of the tab in a direction perpendicular to the tab protruding direction and the stacking direction of the positive electrode and negative electrode, it is conceivable to detect the position of the corner of the end side in the protruding direction of the tab or the position of the rising part of the tab from the positive electrode or negative electrode by irradiating light from a direction along the tab protruding direction and receiving light specularly reflected by the tab. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5790576 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when attempting to detect the position of the corner of the edge of a tab as described above, since the tab is made of thin metal foil, it is easily deformed, the edges of adjacent tabs may overlap, and light irradiated onto the edge may not be reflected in a consistent direction, making it difficult to receive reflected light from all tabs, making it difficult to detect the tab position.

[0007] Furthermore, when attempting to detect the position of the rising portion of the tab, the rising portion of the tab is formed in an arc shape, making it difficult to accurately grasp the rising position of the tab, and therefore, detecting the tab position is difficult.

[0008] Therefore, the present invention provides a method for manufacturing an electrode stack that can detect tab positions in a plurality of stacked electrodes. [Means for solving the problem]

[0009] The problem to be solved by the present invention is as described above, and the means for solving this problem will now be described.

[0010] That is, the method for manufacturing an electrode stack is a method for manufacturing an electrode stack in which a plurality of electrodes, each having a sheet-shaped electrode body and a tab protruding in a first direction from one side of the electrode body, are stacked in a second direction perpendicular to the first direction, wherein light is irradiated onto the tab of the electrode stack from a third direction perpendicular to the second direction, and the reflected light of the light irradiated onto the tab is received from a fourth direction perpendicular to the second direction and inclined with respect to the third direction, and the position of the tab in the third direction is detected based on the received reflected light.

[0011] This makes it possible to detect the position of the tab in the third direction and grasp the amount of misalignment of the tab from lamination.

[0012] The light irradiated onto the tab is positioned at the light irradiation side end of the tab in the third direction and is irradiated onto an edge extending along a direction perpendicular to the third direction.

[0013] This makes it possible to receive light reflected from the tab well even if the tab is deformed or the like.

[0014] The angle formed between the third direction and the fourth direction is an acute angle.

[0015] This allows the light reflected from the tab to be received effectively.

[0016] Furthermore, based on the detected position of the tab in the third direction, the position of the tab in the third direction when the electrodes are next stacked is corrected.

[0017] This makes it possible to reduce the amount of stacking misalignment of the tab in the next electrode to be stacked. [Effects of the Invention]

[0018] According to the present invention, the position of the tab in the third direction can be detected to grasp the amount of misalignment of the tab from stacking. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a perspective view showing an electrode stack. [Figure 2] FIG. 2 is a side view showing an electrode stack. [Figure 3] FIG. 2 is a plan view showing the end portion of the negative electrode tab on the first side edge side. [Figure 4] FIG. 2 is a side view showing the measuring device. [Figure 5] FIG. 2 is a plan view showing the measuring device. [Figure 6] FIG. 10 is a diagram showing an image captured by a camera. [Figure 7] FIG. 10 is a plan view showing another embodiment of an electrode stack. DETAILED DESCRIPTION OF THE INVENTION

[0020] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0021] [Electrode laminate] 1 is an embodiment of an electrode laminate according to the manufacturing method of the present invention, and can be used, for example, in a secondary battery. The electrode laminate 1 includes a positive electrode 2, a negative electrode 3, and a separator 4.

[0022] The positive electrode 2 has a metal foil 21 made of, for example, aluminum foil, and positive electrode active material layers 22 formed on both sides of the metal foil 21. The metal foil 21 has a positive electrode main body 21A formed in the shape of a long sheet, and a tab 21B protruding from one side 211 of the positive electrode main body 21A.

[0023] 1, in the positive electrode main body 21A arranged with the sheet surface facing horizontally, one side 211 is located at the upper end of the positive electrode main body 21A, and the tab 21B protrudes from the side 211 upward in the first direction Z. A plurality of tabs 21B protrude from the side 211. The positive electrode active material layer 22 is formed on the edge of the metal foil 21 on the tab 21B side of the positive electrode main body 21A and in a region excluding the tab 21B.

[0024] The negative electrode 3 has a metal foil 31 made of, for example, copper foil, and a negative electrode active material layer 32 formed on both sides of the metal foil 31. The metal foil 31 has a negative electrode main body 31A formed in the shape of a long sheet, and a tab 31B protruding from one side 311 of the negative electrode main body 31A.

[0025] 1, in the negative electrode main body 31A arranged with the sheet surface facing horizontally, one side 311 is located at the upper end of the negative electrode main body 31A, and the tab 31B protrudes from the side 311 upward in the first direction Z. A plurality of tabs 31B protrude from the side 311. The negative electrode active material layer 32 is formed on the edge of the metal foil 31 on the tab 31B side of the negative electrode main body 31A and in a region excluding the tab 31B.

[0026] The separator 4 is made of, for example, a woven or nonwoven resin material formed into a long sheet shape.

[0027] The electrode laminate 1 is constructed by stacking a positive electrode 2 and a negative electrode 3 so that their sheet surfaces face each other, and then winding the positive electrode 2, negative electrode 3, and separator 4 into an elongated cylindrical shape with the separator 4 interposed between the positive electrode 2 and negative electrode 3. The separator 4 is wound on the outermost layer of the electrode laminate 1. In the electrode laminate 1 shown in FIG. 1, the wound positive electrode 2, negative electrode 3, and separator 4 are stacked in a second direction Y that is perpendicular to the first direction Z.

[0028] In the electrode laminate 1, the multiple tabs 21B of the positive electrode 2 are stacked in the second direction Y. That is, the tabs 21B protruding from the positive electrode main body 21A of the positive electrode 2 are arranged in positions in the longitudinal direction of the positive electrode main body 21A where they will be stacked on top of each other when the positive electrode 2 is wound to form the electrode laminate 1. When the electrode laminate 1 is incorporated into a secondary battery, the multiple stacked tabs 21B are joined to the positive electrode terminal of the secondary battery in an integrated and welded state.

[0029] Furthermore, in the electrode laminate 1, the multiple tabs 31B of the negative electrode 3 are stacked in the second direction Y. That is, the tabs 31B protruding from the negative electrode main body 31A of the negative electrode 3 are arranged in positions in the longitudinal direction of the negative electrode main body 31A where they will be stacked on top of each other when the negative electrode 3 is wound to form the electrode laminate 1. When the electrode laminate 1 is incorporated into a secondary battery, the stacked multiple tabs 31B are joined in an integrated and welded state to the negative electrode terminal of the secondary battery.

[0030] 2, the tab 21B of the positive electrode 2 has an upper edge 212 that is the edge on the protruding side of the tab 21B along the first direction Z, a first side edge 213 that is the edge on one side in a direction perpendicular to the first direction Z and the second direction Y, and a second side edge 214 that is the edge on the other side in a direction perpendicular to the first direction Z and the second direction Y. In this embodiment, the direction perpendicular to the first direction Z and the second direction Y is defined as a third direction X.

[0031] The top edge 212 extends along a third direction X, which is perpendicular to the first direction Z and the second direction Y. The first side edge 213 and the second side edge 214 extend along the first direction Z, which is perpendicular to the third direction X.

[0032] A first arc portion 215 formed in an arc shape is formed at the rising portion of the first side edge 213 from the side 211 of the positive electrode main body 21A, and a second arc portion 216 formed in an arc shape is formed at the rising portion of the second side edge 214 from the side 211 of the positive electrode main body 21A.

[0033] As shown in FIG. 2 , tab 31B of negative electrode 3 has a top edge 312 that is an edge on the protruding side of tab 31B along first direction Z, a first side edge 313 that is an edge on one side in third direction X that is perpendicular to first direction Z and second direction Y, and a second side edge 314 that is an edge on the other side in third direction X that is perpendicular to first direction Z and second direction Y. Top edge 312 extends along third direction X, which is a direction perpendicular to first direction Z and second direction Y. First side edge 313 and second side edge 314 extend along first direction Z, which is a direction perpendicular to third direction X.

[0034] A first arc portion 315 formed in an arc shape is formed at the rising portion of the first side edge 313 from the side 311 of the negative electrode main body 31A, and a second arc portion 316 formed in an arc shape is formed at the rising portion of the second side edge 314 from the side 311 of the negative electrode main body 31A.

[0035] In the electrode laminate 1, the tabs 21B and 31B are each stacked in the second direction Y. However, due to variations in the winding pressure when winding the positive electrode 2 and the negative electrode 3, stacking misalignment may occur in the tabs 21B and 31B in the third direction X.

[0036] Since tabs 21B and 31B are joined to the electrode terminals of the secondary battery in an accumulated and welded state, it is preferable that the stacking misalignment occurring in tabs 21B and 31B falls within a predetermined range. In order to keep the stacking misalignment occurring in tabs 21B and 31B within the predetermined range, it is important to understand the amount of stacking misalignment of tabs 21B and 31B.

[0037] As shown in FIG. 3, for example, when stacked tabs 31B are viewed from above, stacking misalignment may occur among the stacked tabs 31B, and the position of the end of the top edge 312 on the first side edge 313 side in the third direction X may vary for each tab 31B.

[0038] In this case, if an attempt is made to measure the position of the end of the top edge 312 on the first side edge 313 side by irradiating light from above the tab 31B along the first direction Z and receiving the light reflected specularly from the tab 31B, deformation or undulation occurs in the tab 31B, which is formed from a thin metal foil, causing adjacent tabs 31B to overlap (see the area indicated by arrow A in Figure 3), or the light irradiated to the top edge 312 not to be reflected in a consistent direction, making it difficult to detect the positions of all of the tabs 31B.

[0039] Furthermore, when attempting to detect the position in the third direction X of the rising portion of the tab 31B from one side 311 of the first side edge 313, it is difficult to accurately grasp the rising position of the tab 31B because the rising portion of the first side edge 313 is formed with a first arc portion 315 having an arc shape.

[0040] [Electrode laminate manufacturing method and measuring device] Therefore, in the present invention, when manufacturing the electrode laminate 1, the positions of the tabs 21B and 31B are detected using a measuring device 5 shown in Figures 4 and 5, making it possible to grasp the amount of lamination misalignment of the tabs 21B and 31B. In the following explanation, a method for manufacturing the electrode laminate 1 when detecting the position of the tab 31B on the negative electrode 3 will be described, but the same applies to a method for manufacturing the electrode laminate 1 when detecting the position of the tab 21B on the positive electrode 2.

[0041] The measuring device 5 includes an irradiator 51, a camera 52, and a controller 53. The irradiator 51 is an irradiator that irradiates laser light and is configured to irradiate the laser light from one side in the third direction X to the first side edges 313 of the stacked tabs 31B. The laser light is an example of light. The laser light from the irradiator 51 is a line-shaped light that spreads in the second direction Y, and is irradiated to the first side edges 313 of all the stacked tabs 31B in the second direction Y. The first side edges 313 are located at the end of the tabs in the third direction that is irradiated with light, and are an example of an edge extending along the first direction.

[0042] When the measuring device 5 detects the position of the tab 31B in the third direction, the electrode stack 1 is positioned, for example, with the winding axis aligned in the vertical direction. In this case, the third direction X, which is the direction of irradiation of the laser light from the irradiator 51, is a direction along the horizontal direction, and the first direction Z, which is the direction in which the tab 31B protrudes, is a vertical direction perpendicular to the third direction X. Furthermore, the second direction Y, which is the stacking direction of the tabs 31B, is a horizontal direction perpendicular to the third direction X. The laser light from the irradiator 51 is irradiated, for example, to a portion midway in the vertical direction of the first side edge 313 of the stacked tabs 31B.

[0043] Camera 52 is an imaging device that captures an image of first side edge 313 of stacked tabs 31B from a fourth direction R that is inclined with respect to the third direction X, and receives reflected light of laser light irradiated onto first side edge 313 from fourth direction R. The reflected light from first side edge 313 received by camera 52 is mainly diffuse reflected light that is irregularly reflected at first side edge 313.

[0044] The fourth direction R is perpendicular to the second direction Y and inclined with respect to the third direction X, and is inclined upward by an angle θ with respect to the third direction X. In other words, the angle formed by the third direction X and the fourth direction R is θ. In this embodiment, the angle θ is an angle at which the angle formed by the third direction X and the fourth direction R is an acute angle.

[0045] The controller 53 controls the operations of the irradiator 51 and the camera 52 and processes the images captured by the camera 52 .

[0046] When the measuring device 5 configured in this manner is used and the irradiator 51 irradiates the first side 313 of the tab 31B with laser light, an image G as shown in FIG.

[0047] When laser light is irradiated onto the first side edge 313 of the tab 31B, the reflected light of the irradiated laser light scattered at the first side edge 313 is received by the camera 52, and in Figure 6, the reflected light of the received laser light is captured as a bright spot P.

[0048] In this embodiment, the angle θ formed by the third direction X, which is the direction in which the laser light is emitted, and the fourth direction R, which is the light receiving direction of the camera 52, can be appropriately set to an angle that allows the camera 52 to properly receive the reflected light from the first side edge 313.

[0049] The vertical position of the bright spot P in the image G shown in Figure 6 changes depending on the position of the first side edge 313 of the tab 31B in the third direction X, and the closer the first side edge 313 is to the illuminator 51 in the third direction X, the lower the bright spot P is located in Figure 6.

[0050] For example, as shown in FIG. 3, if the first side edge 313b located at the laser light irradiation end of the upper side 312b in the third direction X is located closer to the laser light irradiation side than the first side edge 313a located at the laser light irradiation end of the upper side 312a, the bright spot Pb appearing on the first side edge 313b in FIG. 6 will be located lower than the bright spot Pa appearing on the first side edge 313a.

[0051] Conversely, as shown in Figure 3, if the first side edge 313c located at the laser light irradiation side end of the upper edge 312c in the third direction X is located farther from the laser light irradiation side than the first side edge 313b, the bright spot Pc appearing on the first side edge 313c in Figure 6 will be located higher than the bright spot Pb appearing on the first side edge 313b.

[0052] Furthermore, for example, the amount of deviation La in the third direction X between the position of the laser light irradiation side end of upper side 312a and the position of the laser light irradiation side end of upper side 312b can be found by correcting the vertical dimension Da between bright points Pa and Pb in image G shown in Fig. 6 based on the angle θ formed between the third direction X in which upper side 312a extends and the fourth direction R in which camera 52 receives reflected light. This makes it possible to find the relationship between the position of tab 31B having upper side 312a in the third direction X and the position of tab 31B having upper side 312b in the third direction X.

[0053] Similarly, the amount of deviation Lb in the third direction X between the position of the laser light irradiation side end of upper side 312b and the position of the laser light irradiation side end of upper side 312c can be found by correcting the vertical dimension Db between bright points Pb and Pc in image G shown in Fig. 6 based on the angle θ formed between the third direction X in which upper side 312b extends and the fourth direction R in which camera 52 receives reflected light. This makes it possible to find the relationship between the position of tab 31B having upper side 312b in the third direction X and the position of tab 31B having upper side 312c in the third direction X.

[0054] In this way, the amount of stacking misalignment of the tabs 31B can be grasped by detecting the positions of the stacked tabs 31B based on the bright points P shown in Fig. 6. In particular, by detecting the position of each stacked tab 31B, it is possible to grasp the tendency of the amount of positional misalignment of the tabs 31B in the third direction X relative to the position in the second direction Y.

[0055] Furthermore, when detecting the position of the tab 31B, the laser light is irradiated onto the first side edge 313 located at the end of the tab 31B on which the laser light is irradiated and extending along the first direction Z, so that even if the tab 31B, which is made of a thin metal foil, is deformed or the like, it is possible to receive the reflected light from the tab 31B well.

[0056] Furthermore, by making the angle between the third direction X in which the laser light is irradiated onto the first side edge 313 and the fourth direction R in which the reflected light from the first side edge 313 is received an acute angle, it is possible to effectively receive the reflected light from the tab 31B.

[0057] Furthermore, the detection of the position of the stacked tabs 31B by the measuring device 5 can be performed during the manufacturing process in which the positive electrode 2, the negative electrode 3, and the separator 4 are wound to manufacture the electrode laminate 1, and the detection of the position of the tabs 31B can be performed for the electrode laminate 1 manufactured in the manufacturing process, and the detection result of the position of the tabs 31B can be fed back when manufacturing the next or next lot of electrode laminates 1, etc.

[0058] For example, if the amount of stacking misalignment of the tab 31B determined based on the detected position of the tab 31B exceeds a predetermined standard value, the detection result of the tab 31B position can be fed back to the winding conditions when winding and stacking the positive electrode 2, negative electrode 3, and separator 4 during the manufacture of the next electrode laminate 1, thereby making it possible to reduce the amount of stacking misalignment of the tab 31B of the next electrode laminate 1 and make it fall within the standard value. This allows the tabs 31B to be well welded when the stacked tabs 31B are stacked and welded together.

[0059] In this embodiment, the third direction X, which is the irradiation direction of the laser light, is defined as a direction that is perpendicular to the second direction Y, which is the stacking direction of the positive electrode 2, the negative electrode 3, and the separator 4, and is also perpendicular to the first direction Z, which is the protruding direction of the tab 31B, and a case has been described in which the laser light is irradiated to the first side edge 313 extending along the first direction Z.

[0060] However, the third direction X, which is the irradiation direction of the laser light, can also be defined as a direction other than the direction perpendicular to the first direction Z, which is the protruding direction of the tab 31B, as long as it is a direction perpendicular to the second direction Y, which is the stacking direction of the positive electrode 2, the negative electrode 3, and the separator 4.

[0061] For example, the third direction X, which is the direction of laser light irradiation, can be defined as a direction that is perpendicular to the second direction Y, which is the stacking direction of the positive electrode 2, the negative electrode 3, and the separator 4, and that is along the first direction Z, which is the protruding direction of the tab 21B. In this case, the third direction X is a direction parallel to the first direction Z.

[0062] When the third direction X is defined as a direction perpendicular to the second direction Y and parallel to the first direction Z, the position of the upper side 312 in the direction along the third direction X can be detected by irradiating the upper side 312, which extends in a direction perpendicular to the third direction X, with laser light. This makes it possible to grasp the amount of stacking misalignment in the first direction Z, which is the protruding direction of the tab 21B.

[0063] [Another embodiment of the electrode laminate] In this embodiment, an electrode stack 1 constructed by winding a long positive electrode 2, a negative electrode 3, and a separator 4 has been described. However, the method for manufacturing an electrode stack according to the present invention can also be applied to an electrode stack 101 constructed by stacking a strip-shaped positive electrode 102, a negative electrode 103, and a separator 104.

[0064] 7, the electrode laminate 101 includes a positive electrode 102, a negative electrode 103, and a separator 104. The positive electrode 102 is made of, for example, aluminum foil and has a metal foil 121 with a positive electrode active material layer formed on both sides, and the metal foil 121 has a rectangular positive electrode main body 121A and a tab 121B protruding from one side of the positive electrode main body 121A.

[0065] The negative electrode 103 has a metal foil 131 made of, for example, copper foil with negative electrode active material layers formed on both sides, and the metal foil 131 has a rectangular negative electrode main body 131A and a tab 131B protruding from one side of the negative electrode main body 131A. The separator 104 is made of, for example, a woven or nonwoven fabric made of a resin member formed into a rectangular shape.

[0066] The electrode stack 101 is formed by stacking the positive electrode 102, the negative electrode 103, and the separator 104 in the following order from the bottom up: separator 104, negative electrode 103, separator 104, positive electrode 102, separator 104, negative electrode 103, etc. In the electrode stack 101 configured in this manner, the positions in the third direction X of the tabs 121B and 131B stacked in the second direction Y can also be detected using the measuring device 5. [Explanation of symbols]

[0067] 1, 101 Electrode laminate 2, 102 positive electrode 3, 103 negative electrode 4, 104 Separator 21, 121 Metal foil 21A, 121A positive electrode body 21B, 121B tab 31, 131 Metal foil 31A, 131A negative electrode body 31B, 131B tab 211 (Positive electrode body) One side 213 (of tab 21B) first side edge 311 (Anode body) One side 313 (of tab 31B) first side edge R 4th direction X 3rd direction Y Second direction Z 1st direction θ (the angle between the third and fourth directions)

Claims

1. A method for manufacturing an electrode stack, comprising stacking a plurality of electrodes, each electrode having a sheet-shaped electrode body and a tab protruding in a first direction from one side of the electrode body, in a second direction perpendicular to the first direction, the method comprising: irradiating the tab of the electrode stack with light from a third direction perpendicular to the second direction; receiving reflected light of the light irradiated onto the tab from a fourth direction that is orthogonal to the second direction and inclined with respect to the third direction; detecting a position of the tab in the third direction based on the received reflected light; A method for manufacturing an electrode stack.

2. The light irradiated onto the tab is the light is irradiated onto an edge of the tab that is located at an end of the tab that is irradiated with the light in the third direction and that extends along a direction perpendicular to the third direction; The method for producing the electrode stack according to claim 1 .

3. The angle between the third direction and the fourth direction is an acute angle. The method for producing the electrode stack according to claim 2 .

4. correcting the position of the tab in the third direction when the electrodes are next stacked, based on the detected position of the tab in the third direction; A method for producing the electrode stack according to any one of claims 1 to 3.

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