JP5246525B2 - Foreign object detection device and foreign object detection method - Google Patents

Description

  The present invention relates to a foreign matter detection apparatus and a foreign matter detection method for detecting foreign matter on a metal foil (including foreign matter contained in an electrode material coated on the metal foil).

  For example, Japanese Patent Application Publication No. 2006-179424 proposes a method for inspecting in a manufacturing process whether or not metal impurity particles that can cause a short circuit in a battery are present in an electrode substrate. In this publication, for example, a transmission electrode is obtained by irradiating a belt-shaped electrode substrate made of nickel foam with X-rays, and metal impurity particles are detected based on the transmission image.

  Japanese Patent Application Publication No. 2008-210784 discloses a method for measuring the amount of silicon or silicon compound deposited per unit area of a current collector. In this method, the active material layer on the current collector is irradiated with X-rays to receive fluorescent X-rays generated from the active material layer.

Japanese Patent Application Publication No. 2006-179424 Japanese Patent Application Publication No. 2008-210784

  By the way, when manufacturing a battery, there is a case where a sheet-like electrode sheet obtained by applying a paste-like electrode material to a current collector made of metal foil is overlapped with a separator interposed therebetween to constitute an electrode body. In this case, if foreign matter is mixed in the electrode body, when the battery is charged or discharged, the foreign matter is deposited, causing a problem. In order to prevent such a problem, it is desirable that no foreign matter is mixed in the battery.

  When X-rays are irradiated so as to pass through the metal foil, the X-rays are attenuated by the metal foil. For this reason, in order to detect the foreign material which exists on metal foil based on the X-ray which permeate | transmitted metal foil, strong X-ray is needed. In addition, since X-rays with high intensity have low spatial resolution, it is difficult to detect minute foreign matter. Moreover, the foreign material which consists of a light metal has a weak effect | action which attenuates an X-ray compared with metal foil. For this reason, when the foreign material which consists of a light metal exists on metal foil, a foreign material may not be detected.

  Therefore, the present invention provides a foreign object detection device and a foreign object detection method suitable for detecting foreign objects on a metal foil (including foreign objects contained in an electrode material coated on the metal foil).

  The foreign matter detection device according to the present invention is a device that detects foreign matter on a strip-shaped metal foil, and transports the metal foil along a curved transport path; for a portion where the metal foil is bent and transported An X-ray irradiator that is arranged in one of the directions in which the metal foil is conveyed and irradiates X-rays along the conveyance path; and the metal foil is conveyed with respect to a portion where the metal foil is bent and conveyed And an X-ray detector that detects the X-rays emitted from the X-ray irradiator.

  According to such a foreign matter detection device, foreign matter can be detected by observing X-rays that have passed through the electrode material without passing through a metal foil. For this reason, the intensity of X-rays can be reduced, the spatial resolution can be increased, and smaller foreign objects can be detected.

  In this case, the foreign object detection apparatus may include a determination unit that determines the presence or absence of a foreign object based on the X-ray detection data detected by the X-ray detector. Moreover, the X-ray detection data detected by the X-ray detector may include a normal value storage unit that stores normal detection data obtained in a state where no foreign matter is present on the metal foil. In this case, the determination unit may determine the presence or absence of foreign matter based on the X-ray detection data detected by the X-ray detector and the normal detection data stored in the normal value storage unit.

  In addition, the foreign object detection device may include an X-ray visualization device that generates image data based on the X-ray detection data detected by the X-ray detector. In this case, for the image data acquired by the X-ray visualization device, a normal value storage unit that stores normal image data obtained in a state where no foreign matter is present on the metal foil; and acquired by the X-ray visualization device A difference processing unit that obtains difference data between the image data and normal image data stored in the normal value storage unit. Moreover, you may provide the determination part which determines the presence or absence of a foreign material based on the difference data obtained by the difference process part.

  Further, the foreign object detection device may include a radiation shielding box that partitions a region where the metal foil is bent and conveyed by the conveying device and divides a region irradiated with X-rays from the X-ray irradiator and shields radiation. Good. In this case, a shielding plate may be disposed along the metal foil transport path at the entrance or exit of the radiation shielding box.

  In addition, the conveying device is configured to bend and convey the first side of the metal foil to the conveyance path of the metal foil with the one side surface bent toward the outside and the other side of the metal foil bent toward the outside. You may have two parts. In this case, an X-ray irradiator and an X-ray detector may be arranged for both the first part and the second part. Thereby, both surfaces of metal foil can be inspected.

  Moreover, the conveying apparatus may have a curved portion that conveys the metal foil while curving it. In this case, the X-ray irradiator may be disposed on one of the tangents of the curved portion, and the X-ray detector may be disposed on the other of the tangents. Further, in this case, the tangent line may be set so as to pass through the top of the curved portion where the metal foil is curved and conveyed in the conveyance path of the metal foil. Moreover, the conveying apparatus may be provided with the roller which guides metal foil to a curved part. Moreover, the foreign material detection apparatus may include a control unit that controls the intensity of X-rays emitted by the X-ray irradiator.

FIG. 1 is a diagram showing a foreign object detection apparatus according to an embodiment of the present invention. FIG. 2 is a view showing an electrode material coating apparatus having a foreign object detection apparatus according to an embodiment of the present invention. FIG. 3 is a view showing an X-ray image obtained by the foreign object detection apparatus according to the embodiment of the present invention. FIG. 4 is a view showing an X-ray image obtained by the foreign object detection apparatus according to the embodiment of the present invention. FIG. 5 is a diagram showing X-ray image difference processing obtained by the foreign object detection apparatus according to the embodiment of the present invention. FIG. 6 is a view showing a foreign object detection apparatus according to an embodiment of the present invention. FIG. 7 is a view showing a foreign object detection device according to another embodiment of the present invention. FIG. 8 is a view showing a foreign object detection apparatus according to another embodiment of the present invention. FIG. 9 is a view showing a foreign object detection device according to another embodiment of the present invention. FIG. 10 is a diagram showing a structural example of a battery. FIG. 11 is a view showing a structural example of a wound electrode body. FIG. 12 is a view showing a structural example of a wound electrode body. FIG. 13 shows an example of a vehicle equipped with a battery.

  The foreign object detection device and foreign object detection method according to an embodiment of the present invention will be described above. Note that, in different embodiments, the same reference numerals are given to members and parts having the same action.

  FIG. 1 is a schematic diagram showing a foreign object detection device 10. The foreign object detection device 10 detects a foreign object Z on the metal foil 20 (including a foreign object included in the electrode material applied to the metal foil 20). As shown in FIG. 1, the foreign object detection device 10 includes a transport device 120 that transports the metal foil 20, an X-ray irradiator 14, and an X-ray detector 16. In this embodiment, a metal foil 20 used as a current collector of a battery and coated with an electrode material 20a is an inspection target. Moreover, in this embodiment, the foreign material detection apparatus 10 is integrated in the electrode material coating apparatus 100 which coats the electrode material 20a on the metal foil 20, as shown in FIG. FIG. 2 shows an electrode material coating apparatus 100 that coats the metal foil 20 with the electrode material 20a.

  The metal foil 20 is used as a battery current collector, for example. In a lithium-ion secondary battery, aluminum foil, copper foil, or the like is used as a battery current collector. Aluminum foil is mainly used as a positive electrode current collector, and copper foil is mainly used as a negative electrode current collector.

Further, in a lithium-ion secondary battery, as a positive electrode active material, for example, lithium manganate (LiMn ₂ O ₄ ), lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ) and the like are used. It is used. In addition, as the negative electrode active material, for example, carbon-based materials such as graphite and amorphous carbon, lithium-containing transition metal oxides, transition metal nitrides, and the like are used. The positive electrode active material and the negative electrode active material are mixed in a paste with a solvent, a binder, a conductive material, or the like. And it is coated on the metal foil 20 as a current collector. A configuration example of a battery using the metal foil 20 as a current collector will be described in detail later.

  In this embodiment, the metal foil 20 may have a portion where the electrode material 20a is not applied (hereinafter, this portion is referred to as “uncoated portion”) (see FIG. 11). The foreign object detection device 10 uses, for example, a foreign material contained in the electrode material 20a, a foreign material attached to an uncoated part, a foreign material attached to the surface of the electrode material 20a, etc., for the metal foil 20 coated with the electrode material 20a. Can be detected. The foreign object detection device 10 may be disposed in a subsequent process of a device that applies the electrode material 20a to the metal foil 20, for example.

  As illustrated in FIG. 2, the electrode material coating apparatus 100 includes a feeding unit 101, a coating unit 102, a drying unit 103, a winding unit 104, and a conveyance control unit 105. The feeding unit 101 is a part where the metal foil 20 wound up in a roll shape is set and the metal foil 20 is fed out. The application part 102 is a part which applies the paste-like electrode material 20 a to the metal foil 20. In the example illustrated in FIG. 2, the application unit 102 applies the back roll 112 that guides the back surface of the metal foil 20 to be conveyed, and the back roll 112, and applies the paste-like electrode material 20 a to the surface of the metal foil 20. An application head 114 is provided.

  The drying unit 103 is a part for drying the paste-like electrode material 20 a applied to the metal foil 20 by the application unit 102. The winding unit 104 is a part where the metal foil 20 coated with the electrode material 20a is wound up in a roll shape. As shown in FIG. 2, the metal foil 20 fed from the feeding unit 101 is guided by a plurality of guide rolls 106, and reaches the winding unit 104 through the feeding unit 101 and the drying unit 103 in order. A predetermined conveyance path 12 is formed. The conveyance control unit 105 controls the rotation of the feeding unit 101 and the winding unit 104 to convey the metal foil 20 along the predetermined conveyance path 12. As described above, the electrode material coating apparatus 100 includes the transport device 120 that transports the metal foil 20 along a predetermined path.

  In this embodiment, the foreign object detection device 10 is disposed in a subsequent process of a coating device that coats the metal foil 20 with the electrode material 20a. In other words, in this embodiment, the electrode material 20a is applied to the metal foil 20 and dried, and then disposed in the post-process. In the transport path 12 of the electrode material coating apparatus 100, the drying unit 103 and the winding unit 104 are arranged. It is arranged between.

  In addition, although illustration is abbreviate | omitted, the electrode material coating apparatus 100 is good to provide the well-known means to convey the metal foil 20 with sufficient precision. For example, various devices such as a position detection device that detects the position of the metal foil 20 in the width direction, a correction device that corrects the displacement in the width direction of the metal foil 20, and a tension adjustment device that applies an appropriate tension to the metal foil 20. An apparatus may be provided in the transport path 12. Thereby, the metal foil 20 supplied to the application part 102, the drying part 103, and the foreign material detection apparatus 10 can be conveyed accurately.

  Hereinafter, the foreign object detection device 10 will be described in more detail. In the foreign object detection apparatus 10, as shown in FIG. 1, the conveyance path of the metal foil 20 is bent. In this embodiment, a roller 22 for guiding the metal foil 20 is arranged, and the metal foil 20 is guided by the roller 22 and is conveyed while being curved with a predetermined curvature.

  In this embodiment, as shown in FIG. 1, the electrode material 20 a is applied to one side of the metal foil 20. In order to detect a foreign substance contained in the electrode material 20a, as shown in FIG. 1, the metal foil 20 may be wound around the roller 22 with the surface coated with the electrode material 20a facing outward.

  The X-ray irradiator 14 is arranged on one side in the direction in which the metal foil 20 is conveyed with respect to the portion W where the metal foil 20 is bent and conveyed, and irradiates the X-ray 30 along the conveyance path 12. In this embodiment, the X-ray irradiator 14 applies X-rays to the metal foil along the tangent line L from one of the tangent lines L of the transport path 12 with respect to the curved portion W where the metal foil 20 is curved in the transport path 12. It is arranged to irradiate. Further, in this embodiment, the X-ray irradiator 14 has a curved portion W that irradiates the X-ray 30 so as to irradiate the metal foil 20 along the tangent L from the upstream side of the transport path 12. It is arranged toward the.

  In this embodiment, the X-ray irradiator 14 includes a control unit 14a that controls the intensity of X-rays to be irradiated. As a result, the X-ray 30 is applied to an intensity appropriate for detecting the foreign matter Z on the metal foil 20 (in the example shown in FIG. 1, the foreign matter Z contained in the electrode material 20a applied to the metal foil 20 is included). Can be controlled. For example, the intensity of X-rays to be irradiated may be controlled according to the applied electrode material 20a or the foreign matter Z to be detected. The intensity of X-rays can be controlled, for example, by manipulating a voltage that generates X-rays. Such an X-ray irradiator 14 preferably comprises a low tube voltage and high tube current X-ray source with a smaller focal size. As this X-ray irradiator 14, for example, a commercially available X-ray irradiator having a required function may be adopted.

  Next, the X-ray detector 16 is disposed on the other side in the direction in which the metal foil 20 is conveyed with respect to the portion W where the metal foil 20 is bent and conveyed. The X-ray detector 16 detects X-rays emitted from the X-ray irradiator 14. The X-ray detector 16 is disposed on the opposite side to the X-ray irradiator 14 on the tangent L of the curved portion W of the transport path 12. Further, in this embodiment, the X-ray detector 16 is disposed on the downstream side of the conveyance path 12 with respect to the curved portion W where the metal foil 20 is curved in the conveyance path 12.

  In this embodiment, the X-ray detector 16 includes an X-ray visualization device 16a that generates image data obtained by converting an X-ray image into a visible light image. As the X-ray visualization device 16a, a so-called “X-ray image intensifier” can be used. The X-ray visualization device 16a may employ a device having a required function with respect to high sensitivity, a high number of pixels, an aspect ratio suitable for visualization, and the like.

  In this embodiment, the tangent L is set so as to pass through the apex T of the curved portion W where the metal foil 20 is curved and conveyed in the conveyance path 12 of the metal foil 20. An X-ray irradiator 14 is disposed on one of the tangent lines L, and an X-ray detector 16 is disposed on the other of the tangent lines L. In this embodiment, an X-ray irradiator 14 is disposed on the upstream side of the transport path 12, and an X-ray detector 16 is disposed on the downstream side of the transport path 12.

  According to the foreign object detection device 10, X-rays 30 are emitted from the X-ray irradiator 14 while the metal foil 20 is being conveyed along the conveyance path 12. The X-ray 30 is irradiated from one of the tangents L to the curved portion W where the conveyance path of the metal foil 20 is curved. Then, the X-ray 30 irradiated to the metal foil 20 is observed by the X-ray detector 16 arranged on the other side of the tangent L. In this embodiment, the X-ray detector 16 generates image data obtained by converting an X-ray image into a visible light image.

  In this embodiment, while transporting the strip-shaped metal foil 20 along the curved path, the metal foil is irradiated with X-rays along one of the tangents of the curved transport path along the tangent, and the tangent X-rays are observed on the other side. In this case, X-rays transmitted through the electrode material 20a can be observed without passing through the metal foil 20. That is, as shown in FIG. 3, the X-ray image observed by the X-ray detector 16 includes a part a1 where the X-ray 30 is blocked by the metal foil 20, and a part a2 where the X-ray 30 passes through the electrode material 20a. The X-ray 30 has a portion a3 that does not transmit the metal foil 20 and the electrode material 20a.

  At this time, a dark shadow is generated at a portion a1 where the X-ray 30 is blocked by the metal foil 20. On the other hand, the shadow of the part a2 that transmits the electrode material 20a is lighter than the part a1 where the X-ray 30 is blocked by the metal foil 20. Moreover, in the site | part a3 in which the X-ray 30 does not permeate | transmit the metal foil 20 and the electrode material 20a, the X-ray 30 is not attenuate | damped and a shadow is hardly produced. In the electrode material 20a, an active material (a positive electrode active material or a negative electrode active material), a solvent, a binder, a conductive material, and the like are mixed and applied in a paste form and dried. For this reason, the electrode material 20a is less effective in attenuating the X-rays 30 than the metal foil 20, and the part a2 that transmits the electrode material 20a has a shadow compared to the part a1 where the X-rays 30 are blocked by the metal foil 20. Is thought to be thinner.

  In the part a2 where the X-ray 30 passes through the electrode material 20a, the ratio of the active material (positive electrode active material or negative electrode active material), solvent, binder, conductive material, etc. contained in the electrode material 20a and the degree of mixing Therefore, the shadow density is determined, and a shadow having a substantially constant density is generated. The portion a2 that transmits the electrode material 20a and the portion a1 where the X-ray 30 is blocked by the metal foil 20 can be easily distinguished because there is a significant difference in the darkness of the generated shadow.

  When the foreign material Z is included in the electrode material 20a, a shadow caused by the foreign material Z is observed in the shadow caused by the electrode material 20a as shown in FIG. In particular, in the case of a metallic foreign object that easily attenuates the X-rays 30, a shadow that is significantly darker than the electrode material 20a is likely to occur.

  As shown in FIG. 1, the foreign object detection apparatus 10 conveys a belt-shaped metal foil 20 along a curved conveyance path 12. And the X-ray 30 is irradiated along the conveyance path 12 from one side with respect to the curved conveyance path 12, and the foreign matter Z (metal foil 20) on the metal foil 20 based on the X-ray 30 observed on the other side. And the foreign material Z included in the electrode material 20a coated on the surface is detected. According to the foreign object detection device 10, the foreign object Z can be detected by observing the X-ray 30 that has passed through the electrode material 20 a without passing through the metal foil 20 as described above. For this reason, the foreign matter Z can be detected even if the intensity of the X-ray 30 is weakened. In addition, since X-rays with low intensity have high spatial resolution, a smaller foreign matter Z can be detected. Further, since X-rays transmitted through the electrode material 20a can be observed without passing through the metal foil 20, it is possible to detect foreign matter having a small effect of attenuating the X-rays 30 such as light metal.

  Moreover, in this embodiment, the metal foil 20 is curved and conveyed in part. Then, the X-ray irradiator 14 is arranged on one side and the X-ray detector 16 is arranged on the other side with respect to the tangent line L set so as to pass through the apex T of the curved portion W. In this case, in the transport path 12 of the metal foil 20, the range in which X-rays transmitted through the electrode material 20a by the X-ray detector 16 are observed is narrow. For this reason, when it is suspected that there is a foreign substance Z on the metal foil 20 based on the X-ray 30 observed by the X-ray detector 16, the position of the foreign substance Z in the metal foil 20 is determined in a narrower range. Can be identified. Thereby, for example, when a battery is assembled by removing a portion where the foreign matter Z is present from the metal foil 20, the range to be removed can be reduced, so that the yield can be improved.

  Further, by changing the radius of curvature of the curved portion W where the metal foil 20 is curved and conveyed, X-rays transmitted through the electrode material 20a by the X-ray detector 16 are observed in the conveyance path 12 of the metal foil 20. The range to be adjusted can be adjusted to an arbitrary length.

  Further, in this foreign object detection device 10, image data obtained by converting an X-ray image into a visible light image is generated by the X-ray detector 16. An X-ray image may be projected on a display based on such image data, and an operator may monitor and determine this. However, the X-ray image observed by the X-ray detector 16 includes a shadow attributed to the metal foil 20 and a shadow attributed to the electrode material 20a.

  In this embodiment, the foreign object detection apparatus 10 includes a determination unit 50 that determines the presence or absence of the foreign object Z based on the X-ray detection data detected by the X-ray detector 16 as shown in FIG.

  The determination unit 50 includes a normal value storage unit 52, a difference processing unit 54, and a determination processing unit 56. The determination unit 50 can be realized, for example, by causing a computer to execute a program set in advance so as to perform a required function. In this case, for example, the computer may be provided with an arithmetic device such as a CPU and a storage device such as a nonvolatile memory, and may be provided with a function capable of processing a required arithmetic operation in accordance with a set program. .

  The normal value storage unit 52 stores normal detection data obtained in a state where the foreign matter Z is not present on the metal foil 20 with respect to the X-ray detection data detected by the X-ray detector 16. In this embodiment, the X-ray detector 16 includes an X-ray visualization device 16a that generates image data obtained by converting an X-ray image into a visible light image. The normal value storage unit 52 stores normal image data obtained in a state where the foreign matter Z does not exist on the metal foil 20 with respect to the image data acquired by the X-ray visualization device 16a.

  The difference processing unit 54 obtains difference data between the image data acquired by the X-ray visualization device 16 a and normal image data stored in the normal value storage unit 52. FIG. 5 schematically shows the processing of the difference processing unit 54. The difference processing unit 54 obtains difference data D3 between the image data D1 acquired by the X-ray visualization device 16a and the normal image data D2 stored in the normal value storage unit 52. In this embodiment, the difference data D3 is obtained by subtracting the normal image data D2 stored in the normal value storage unit 52 from the image data D1 acquired by the X-ray visualization device 16a to extract a shadow caused by the foreign matter Z. doing.

  In this case, after subtracting the normal image data D2 stored in the normal value storage unit 52 from the image data D1 acquired by the X-ray visualization device 16a, noise may be removed as necessary. By removing the noise, it is possible to more appropriately extract the shadow caused by the foreign matter Z as shown in FIG. Thus, in this embodiment, the difference processing unit 54 that obtains the difference data D3 between the image data D1 acquired by the X-ray visualization apparatus 16a and the normal image data D2 stored in the normal value storage unit 52 is provided. ing. Therefore, in the image based on the difference data D3, the shadow caused by the metal foil 20 and the electrode material 20a is deleted, and the shadow caused mainly by the foreign matter Z remains. For this reason, the presence or absence of the foreign material Z can be easily determined. Such a determination may be made by, for example, displaying an image based on the difference data D3 on a display device and monitoring the image displayed on the display device by an operator.

  The foreign object detection device 10 can further make a determination using a computer. That is, in this embodiment, the determination processing unit 56 determines the presence or absence of the foreign matter Z based on the difference data D3 obtained by the difference processing unit 54. For example, the determination processing unit 56 may determine the presence or absence of the foreign matter Z based on whether or not a shadow caused by the foreign matter Z exists in the difference data D3. In this case, for example, it is a problem whether the shadow generated in the difference data D3 obtained by the difference processing unit 54 is actually a shadow caused by the foreign object Z. Further, there is a foreign matter Z that is small enough not to cause a problem even if a battery is assembled. Therefore, the determination processing unit 56 may set a certain threshold value for the shadow generated in the difference data D3, and may determine that there is a foreign substance Z when the threshold value is exceeded.

  For example, the shadow generated in the difference data D3 may be determined as “there is a foreign matter Z” by comparing with a certain threshold value. For example, a threshold value may be set in advance for the size of a shadow suspected to be caused by the foreign object Z, and it may be determined that “there is a foreign object Z” when the shadow suspected to be caused by the foreign object Z is larger than the threshold value. A shadow smaller than a predetermined size may be removed as noise. As a result, it is possible to ignore a foreign matter Z that is small enough not to cause a problem even if a battery is assembled, and a shadow caused by noise. As a result, more appropriate determination is possible, and determination errors can be eliminated. For example, when such a determination unit 50 determines that “the foreign matter Z is present”, the portion can be prevented from being used for the battery. In this case, by removing shadows smaller than a predetermined size as noise, it is possible to reduce the number of parts that are wasted due to erroneous determination. Thereby, a yield can be improved.

  As shown in FIGS. 1 and 5, the foreign object detection device 10 includes an X-ray visualization device 16a, and acquires image data D1 acquired by the X-ray visualization device 16a. In the determination unit 50, the presence / absence of the foreign matter Z is determined by the computer based on the difference data D 3 between the image data D 1 and the image data D 2 stored in the normal value storage unit 52. In this case, it is possible to determine the presence or absence of the foreign matter Z uniformly according to a predetermined determination criterion without requiring artificial determination.

  In addition, you may combine the determination process by such a computer, and the determination by a person. For example, when the presence or absence of the foreign matter Z is doubtful only by the determination process by the computer, the image data D1 acquired by the X-ray visualization device 16a or the normal image data stored in the image data D1 and the normal value storage unit 52 An operator may determine by viewing an image based on the difference data D3 with respect to D2.

  Moreover, in this embodiment, the foreign material detection apparatus 10 is provided with the radiation shielding box 40 in order to prevent that the X-ray 30 leaks outside as shown in FIG. The radiation shielding box 40 divides a curved portion W where the metal foil 20 is curved in the transport path 12 and a region P where the X-ray 30 is irradiated from the X-ray irradiator 14, and shields radiation in the region P. Yes. The radiation shielding box 40 is open at a portion where the roller 22 is installed. The roller 22 is made of a material that blocks the X-ray 30. The roller 22, the metal foil 20 wound around the roller 22, and the radiation shielding box 40 cooperate to prevent the X-ray 30 from leaking to the outside.

  Moreover, in this embodiment, as shown in FIG. 1, the conveyance path | route 12 of the metal foil 20 is curving. An X-ray irradiator 14 is disposed on one of the tangents L set at the top T of the curved portion W, and an X-ray detector 16 is disposed on the other of the tangents L. In this case, in the conveyance path of the metal foil 20, the gap on the entrance S 1 side of the radiation shielding box 40 is positioned in a direction generally opposite to the direction in which the X-ray detector 16 irradiates the X-ray 30. Further, the X-ray 30 irradiated from the X-ray detector 16 and reflected by the metal foil 20 being conveyed is reflected in the direction opposite to the entrance S <b> 1 of the radiation shielding box 40. For this reason, it is difficult for the X-ray 30 to come out from the gap on the entrance S1 side of the radiation shielding box 40. Moreover, the clearance gap which arises at the exit S2 side of the radiation shielding box 40 becomes the back side of the site | part where the metal foil 20 is conveyed seeing from the position where the X-ray detector 16 is arrange | positioned. For this reason, the X-rays 30 irradiated from the X-ray detector 16 are difficult to exit from the gap on the exit S2 side.

  In this way, in the foreign object detection device 10, the X-ray 30 is irradiated along the transport path 12 from one side with respect to the transport path 12 with the bent metal foil 20. For this reason, when the region P irradiated with the X-ray 30 from the X-ray irradiator 14 is partitioned by the radiation shielding box 40 as described above, the reflection direction of the X-ray 30 is in the direction of the entrance or exit of the metal foil 20. Not suitable. For this reason, it is easy to prevent leakage of the X-ray 30.

  Further, a gap is formed along the conveyance path of the metal foil 20 at the entrance S1 and the exit S2 of the radiation shielding box 40. In this embodiment, in order to prevent leakage of the X-rays 30 from the gap, shielding plates 42 are disposed along the transport path 12 of the metal foil 20 at the entrance S1 and the exit S2 of the radiation shielding box 40. . The shielding plate 42 prevents the X-ray 30 from leaking to the outside along the transport path 12 of the metal foil 20 from the gap between the entrance S1 and the exit S2 of the radiation shielding box 40.

  The shielding plate 42 may be provided as necessary. In the example shown in FIG. 1, the shielding plates 42 are provided at both the entrance S1 and the exit S2 of the radiation shielding box 40, but may be provided at either one. Further, when the X-ray 30 does not leak outside from the entrance S1 and the exit S2 of the radiation shielding box 40, the shielding plate 42 may not be provided. Further, as shown in FIG. 1, the shielding plate 42 extends outside the radiation shielding box 40 along the transport path 12 of the metal foil 20. Although illustration is omitted, the shielding plate 42 may extend along the transport path 12 of the metal foil 20 inside the radiation shielding box 40.

  As mentioned above, although the foreign material detection apparatus which concerns on one Embodiment of this invention was illustrated, the foreign material detection apparatus which concerns on this invention is not limited above.

  For example, in the above-described embodiment, the X-ray visualization device 16 a that generates image data based on the X-ray detection data detected by the X-ray detector 16 is provided. When determining the presence or absence of the foreign matter Z, the X-ray visualization device 16a is not necessarily required particularly when it is not necessary to generate image data. When the X-ray visualization device 16a is not used, the determination unit 50 determines the presence or absence of the foreign matter Z without generating image data based on the X-ray detection data detected by the X-ray detector 16. It is good to configure.

  Also, in the case where the presence / absence of the foreign matter Z is determined without generating image data based on the X-ray detection data detected by the X-ray detector 16, as shown in FIG. It may be provided. About the said X-ray detection data, you may provide the normal value memory | storage part 52 which memorize | stored the normal detection data obtained in the state in which the foreign material does not exist on metal foil. In this case, the determination unit 50 may determine the presence or absence of the foreign substance Z based on the X-ray detection data detected by the X-ray detector 16 and the normal detection data stored in the normal value storage unit 52. .

  For example, as a configuration for determining the presence or absence of the foreign matter Z, a difference processing unit 54 and a determination processing unit 56 may be provided in the foreign matter detection apparatus 10 as shown in FIG. In this case, the difference processing unit 54 obtains difference data between the X-ray detection data detected by the X-ray detector 16 and the normal X-ray detection data stored in the normal value storage unit 52. Then, the determination processing unit 56 determines the presence or absence of the foreign matter Z based on the difference data obtained by the difference processing unit 54. The foreign object detection device 10 may be configured to determine the presence or absence of the foreign object Z without generating image data.

  Moreover, in embodiment mentioned above, although the metal foil 20 has illustrated the form with which the electrode material 20a was coated, as shown in FIG. 6, the electrode material 20a is applied to the metal foil 20 as a test object. It does not have to be. Thus, the foreign object detection device 10 can be used to detect the foreign object Z attached to the metal foil 20.

  Moreover, the electrode material 20a may be coated on both surfaces of the metal foil 20. The foreign object detection device 10 can also be configured to detect the foreign object Z on both surfaces of the metal foil 20. FIG. 7 shows a foreign object detection device 10 </ b> A configured to detect the foreign object Z on both surfaces of the metal foil 20. In this foreign matter detection apparatus 10A, the conveyance path 12 of the metal foil 20 is formed such that the first portion W1 that is bent and conveyed with the surface F1 on one side of the metal foil 20 outward, and the surface F2 on the opposite side of the metal foil is outward. And a second portion W2 that is bent and conveyed. In the foreign matter detection apparatus 10A, X-ray irradiators 14A and 14B and X-ray detectors 16A and 16B are provided in both the first portion W1 and the second portion W2, respectively.

  Thereby, by irradiating the surface F1 on one side of the metal foil 20 with the X-ray 31 in the first portion W1 that is bent and conveyed toward the outside, the surface F1 on one side of the metal foil 20 is formed. Foreign matter Z1 can be detected. Further, by continuously irradiating the opposite surface F2 of the metal foil 20 with the X-rays 32 in the second portion W2 that is bent and conveyed toward the outside, the surface F2 on the opposite side of the metal foil 20, The foreign matter Z2 on the surface F2 can be detected. According to this foreign matter detection device 10A, both surfaces F1 and F2 of the metal foil 20 can be inspected in order. Further, when configured to detect the foreign matter Z on both surfaces of the metal foil 20, the foreign matter detection device can be configured in a compact manner.

  In the above-described embodiment, as illustrated in FIG. 1, the X-ray irradiator 14 is disposed on the upstream side of the conveyance path 12 with respect to the curved portion W where the metal foil 20 is curved in the conveyance path 12. 12, an X-ray detector 16 is arranged on the downstream side. For example, as illustrated in FIG. 8, an X-ray irradiator 14 is disposed on the downstream side of the conveyance path 12 with respect to the curved portion W where the metal foil 20 is curved in the conveyance path 12. The X-ray detector 16 may be arranged on the upstream side.

  Further, in the above-described embodiment, the X-ray irradiator 14 is arranged on one side with respect to the tangent line L set so as to pass through the top portion T of the curved portion W to which the metal foil 20 is curved and conveyed, and on the other side. An X-ray detector 16 is arranged. The arrangement of the X-ray irradiator 14 and the X-ray detector 16 is not limited to such a form. Although illustration is omitted, a tangent line L is set at a position shifted in the circumferential direction from the apex T of the curved portion W where the metal foil 20 is curved and conveyed, and the X-ray irradiator 14 is disposed on one of the tangent lines L. However, the X-ray detector 16 may be disposed on the other side.

  Moreover, in embodiment mentioned above, the conveying apparatus 120 has illustrated the form with the curved part W which conveys the metal foil 20, curving. The conveyance path 12 of the metal foil 20 formed by the conveyance device 120 is not limited to such a form. That is, the conveyance path 12 of the metal foil 20 does not necessarily have the curved portion W curved with a certain curvature. Although illustration is omitted, in the foreign object detection device 10, the conveyance path 12 of the metal foil 20 bent by a plurality of rollers may be formed at a site irradiated with the X-ray 30.

  For example, as illustrated in FIG. 9, the foreign object detection device 10 </ b> B may convey the belt-shaped metal foil 20 along the curved conveyance path 12. In the form shown in FIG. 9, a portion where the conveyance path of the metal foil 20 is bent by the two rollers 22 a and 22 b and the metal foil 20 is conveyed along the straight line L <b> 1 between the two rollers 22 a and 22 b. W3 is formed.

  In this embodiment, the X-ray irradiator 14 is disposed on one side of the straight line L1, and the X-ray detector 16 is disposed on the other side of the straight line L1. The X-ray irradiator 14 irradiates the X-ray 30 along the straight line L1, and the X-ray detector 16 detects the X-ray 30 irradiated along the straight line L1.

  And based on the X-ray 30 observed by the X-ray detector 16, the foreign material Z on the metal foil 20 is detected. In this case, the foreign matter Z on the metal foil 20 (including the foreign matter Z contained in the electrode material 20a coated on the metal foil 20) can be detected on the straight line L1 between the two rollers 22a and 22b. it can.

  In this method, the shadow of the X-ray 30 caused by the foreign matter Z is observed while the foreign matter Z passes the straight line L1 between the two rollers 22a and 22b. For this reason, even when the conveyance speed of the metal foil 20 is the same, the time during which the foreign matter Z can be captured becomes longer, so the foreign matter Z can be detected more reliably. In this case, the distance between the two rollers 22a and 22b may be appropriately adjusted so that the foreign matter Z can be reliably detected.

  As described above, the foreign object detection apparatus may convey the belt-shaped metal foil 20 along the curved conveyance path 12. In this case, the X-ray irradiator 14 is applied to one of the directions in which the metal foil 20 is transported so as to irradiate the X-ray 30 along the transport path 12 with respect to the portion where the metal foil 20 is bent and transported. It is good to be arranged. Moreover, the X-ray detector 16 is good to be arrange | positioned with respect to the direction where the metal foil 20 is conveyed with respect to the part where the metal foil 20 is bent and conveyed. The X-ray detector 16 may detect the X-rays 30 emitted from the X-ray irradiator 14. Thereby, the foreign material Z (including the foreign material Z included in the electrode material 20a coated on the metal foil 20) on the metal foil 20 can be detected while the metal foil 20 is being conveyed. As described above, various methods can be adopted to bend the conveyance path of the metal foil 20.

  Moreover, in embodiment mentioned above, the lithium ion secondary battery was mentioned as an application for which this metal foil 20 is used. Applications in which such metal foil 20 is used are not limited to lithium ion secondary batteries. Such metal foil 20 can be used for current collectors of various batteries, and can be used for various batteries. Here, the “battery” refers to a general power storage device that can extract electric energy. For example, a secondary battery (storage battery) such as a lithium ion secondary battery, a metal lithium secondary battery, a nickel metal hydride battery, or a nickel cadmium battery. , And a concept including a storage element such as an electric double-layer capacitor and a primary battery.

  The foreign matter detection apparatus and foreign matter detection method described above can be incorporated into such a battery manufacturing method. Hereinafter, an example is given about the manufacturing method of the battery which used metal foil as a collector.

  For example, the battery 1000 is configured as a rectangular metal battery case 300 as shown in FIG. The battery case 300 accommodates a wound electrode body 310.

  In this embodiment, the wound electrode body 310 includes a positive electrode sheet 311 and a negative electrode sheet 313 as band-like electrodes, as shown in FIGS. 11 and 12. Moreover, the 1st separator 312 and the 2nd separator 314 are provided as a strip | belt-shaped separator. The positive electrode sheet 311, the first separator 312, the negative electrode sheet 313, and the second separator 314 are stacked and wound in this order.

  The positive electrode sheet 311 is coated with an electrode material 311d containing a positive electrode active material on both surfaces of an aluminum foil (corresponding to the metal foil 20 (see FIG. 1)) as the current collector sheet 311c. The negative electrode sheet 313 is coated with an electrode material 313d containing a negative electrode active material on both sides of a copper foil (corresponding to the metal foil 20 (see FIG. 1)) as the current collector sheet 313c. The separators 312 and 314 are membranes that are permeable to ionic substances. In this embodiment, polypropylene microporous membranes are used.

  In this embodiment, the electrode materials 311d and 313d are applied so as to be biased to one side in the width direction of the current collector sheets 311c and 313c. The electrode materials 311d and 313d are not applied to the edge of the current collector sheets 311c and 313c on the opposite side in the width direction. Of the positive electrode sheet 311 and the negative electrode sheet 313, portions where the current collector sheets 311c and 313c are coated with the electrode material 311d and 313d are referred to as coating portions 311a and 313a, and the current collector sheets 311c and 313c have the electrode material 311d. A portion where 313d is not applied is referred to as an uncoated portion 311b or 313b.

  FIG. 11 is a cross-sectional view in the width direction showing a state in which the positive electrode sheet 311, the first separator 312, the negative electrode sheet 313, and the second separator 314 are sequentially stacked. The coating part 311a of the positive electrode sheet 311 and the coating part 313a of the negative electrode sheet 313 are opposed to each other with the separators 312 and 314 interposed therebetween. As shown in FIGS. 11 and 12, the uncoated portions 311 b and 313 b of the positive electrode sheet 311 and the negative electrode sheet 313 are separators on both sides in a direction (winding axis direction) orthogonal to the winding direction of the wound electrode body 310. It protrudes from 312 and 314, respectively. The uncoated portions 311b and 313b of the positive electrode sheet 311 and the negative electrode sheet 313 form positive and negative current collectors 311b1 and 313b1 of the wound electrode body 310, respectively.

As shown in FIG. 10, the battery case 300 is provided with a positive terminal 301 and a negative terminal 303. The positive electrode terminal 301 is electrically connected to the positive electrode current collector 311b1 of the wound electrode body 310. The negative electrode terminal 303 is electrically connected to the negative electrode current collector 313b1 of the wound electrode body 310. An electrolytic solution is injected into the battery case 300. The electrolytic solution can be composed of a nonaqueous electrolytic solution such as a mixed solvent such as diethyl carbonate and ethylene carbonate containing an appropriate amount of an appropriate electrolyte salt (for example, a lithium salt such as LiPF ₆ ).

  The foreign matter detection apparatus 10 (see FIGS. 1 and 2) described above can detect the foreign matter Z contained in the positive electrode sheet 311 and the negative electrode sheet 313. By incorporating such foreign object detection device 10 into the manufacturing process of battery 1000, foreign substance Z contained in battery 1000 can be reduced.

  In this case, for example, the foreign object detection device 10 may be incorporated in the manufacturing process of the battery 1000 so as to detect the foreign substance Z contained in the positive electrode sheet 311 and the negative electrode sheet 313 in the process before the battery 1000 is assembled. In the embodiment described above, as shown in FIG. 2, the foreign object detection device 10 is incorporated in the electrode material application device 100 that applies the electrode material to the current collector sheets 311 c and 313 c (metal foil). The form is not limited. For example, the foreign object detection device 10 may be incorporated in a pre-process of a process in which the positive electrode sheet 311, the first separator 312, the negative electrode sheet 313, and the second separator 314 are stacked and wound in this order. Further, the foreign matter detection device 10 may be used as a device that detects foreign matter attached on the current collector sheets 311c and 313c before the electrode materials 311d and 313d are applied to the current collector sheets 311c and 313c. (See FIG. 6).

  In this way, by incorporating the foreign object detection device 10 in the battery manufacturing process, foreign substances contained in the battery can be reduced. As a result, a secondary battery with less foreign matter in the battery can be manufactured, the quality of the secondary battery is improved, the performance of the secondary battery is prevented from being deteriorated, and the life of the secondary battery is extended. be able to.

  A plurality of such lithium-ion secondary batteries are combined to form an assembled battery 1000, which is mounted as a power source of a vehicle 2000, for example, as shown in FIG. The present invention contributes to the stability of the performance of the battery for vehicles and the extension of the life. For example, the vehicle 2000 can be applied as a power source (secondary battery) of an automobile including an electric motor such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle.

10, 10A, 10B Foreign matter detection device 12 Transport path 14, 14A, 14B X-ray irradiator 14a Control unit 16, 16A, 16B X-ray detector 16a X-ray visualization device 20 Metal foil 20a Electrode material 22, 22a, 22b Roller 30 , 31, 32 X-ray 40 Radiation shielding box 42 Shielding plate 50 Determination unit 52 Normal value storage unit 54 Difference processing unit 56 Determination processing unit 100 Electrode material coating apparatus 101 Delivery unit 102 Application unit 103 Drying unit 104 Winding unit 105 Control unit 106 Guide roll 112 Back roll 114 Coating head 120 Conveying device 300 Battery case 301 Positive electrode terminal 303 Negative electrode terminal 310 Winding electrode body 311 Positive electrode sheet 311a Coating part 311b Uncoated part 311b1 Positive electrode current collector 311c Current collector sheet (Metal foil)
311d Electrode material 312, 314 Separator 313 Negative electrode sheet 313a Coated part 313b Uncoated part 313b1 Negative electrode current collector 313c Current collector sheet (metal foil)
313d Electrode material 1000 Battery (assembled battery)
2000 Vehicle L, L1 Tangent W, W1, W2, W3 Curved part (part where metal foil is bent and conveyed)
Z, Z1, Z2 Foreign matter T Top

Claims (16)

A foreign matter detection device for detecting foreign matter contained in an electrode material coated on a strip-shaped metal foil,
A transport device for transporting the metal foil along a curved transport path;
An X-ray irradiator that is arranged in one of the directions in which the metal foil is conveyed with respect to a portion where the metal foil is bent and conveyed, and irradiates X-rays along the conveyance path;
And an X-ray detector that detects an X-ray emitted from the X-ray irradiator, arranged on the other side of the direction in which the metal foil is conveyed with respect to a portion where the metal foil is bent and conveyed;
Foreign object detection device comprising:   The foreign matter detection device according to claim 1, further comprising: a determination unit that determines the presence or absence of foreign matter based on X-ray detection data detected by the X-ray detector. Wherein the X-ray detection data detected by the X-ray detector, the normal value storage unit for storing a normal detection data obtained in a state in which the foreign substance is not present; provided with,
3. The determination unit according to claim 2, wherein the determination unit determines the presence or absence of a foreign substance based on X-ray detection data detected by the X-ray detector and normal detection data stored in the normal value storage unit. Foreign object detection device.   The foreign object detection device according to claim 1, further comprising: an X-ray visualization device that generates image data based on X-ray detection data detected by the X-ray detector. Wherein the image data acquired by X-ray visualization device, the normal value storage unit that stores a normal image data obtained in a state in which the foreign substance is not present;
And a difference processing unit that obtains difference data between the image data acquired by the X-ray visualization apparatus and normal image data stored in the normal value storage unit. Detection device.
  The foreign object detection device according to claim 5, further comprising: a determination unit that determines presence / absence of a foreign object based on difference data obtained by the difference processing unit.   The radiation shielding box which partitions off the area | region where X-rays are irradiated from the said X-ray irradiator with respect to the part by which the metal foil bends and is conveyed by the said conveying apparatus, and comprises the said radiation. The foreign object detection device described in any one of items 6 to 6.   The foreign object detection device according to claim 7, wherein a shielding plate is disposed along a conveyance path of the metal foil at an entrance or an exit of the radiation shielding box. The conveyance device bends and conveys a first portion of the metal foil that is bent and conveyed on one side of the metal foil toward the outer side, and an opposite surface of the metal foil that is bent toward the outer side. A second part,
The foreign matter detection device according to any one of claims 1 to 8, wherein the X-ray irradiator and the X-ray detector are arranged for both the first portion and the second portion, respectively.   The transport device has a curved portion that transports the metal foil while curving, the X-ray irradiator is disposed on one of the tangents of the curved portion, and the X-ray detector is disposed on the other of the tangents. The foreign object detection device according to any one of claims 1 to 9.   The foreign object detection device according to claim 10, wherein the tangent line is set so as to pass through a top portion of a curved portion in which the metal foil is curved and conveyed in a conveyance path of the metal foil.   The foreign material detection device according to claim 10, wherein the transport device includes a roller that guides the metal foil to the curved portion.   The foreign object detection device according to claim 1, further comprising: a control unit that controls intensity of X-rays emitted by the X-ray irradiator.   An electrode material coating apparatus, wherein the foreign matter detection apparatus according to any one of claims 1 to 13 is disposed in a subsequent process of a coating apparatus that coats the metal foil with an electrode material. While the belt-shaped metal foil coated with the electrode material was transported along the curved transport path, the curved transport path was irradiated with X-rays along the transport path from one side, and was observed on the other side. A foreign matter detection method for detecting foreign matter contained in an electrode material coated on the metal foil based on the X-ray. A method for manufacturing a battery having a current collector sheet in which an electrode material is coated on a metal foil, comprising the foreign matter detection method according to claim 15.

Images