Stack cell for easily checking for bent separation membrane, and separation membrane inspection device and inspection method

Abstract

A stack cell according to one embodiment of the present invention, which allows easy detection of a folded separation membrane, includes a plurality of electrodes, a separation membrane disposed between two adjacent electrodes, and a radio-opaque material through which radiation does not pass, and includes a mark provided at an end region of the separation membrane, and allows easy detection of a folded separation membrane based on position information of the radio-opaque mark.

Description

[Technical field]

[0001] The present invention relates to a stack cell, a separation membrane inspection device, and an inspection method that can easily check for a break in a separation membrane by using image information acquired by irradiating radiation and determining whether or not the separation membrane is broken in the stack cell.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0178139, filed on December 19, 2022, and all contents disclosed in the documents of the Korean Patent Application are incorporated as part of this specification. [Background technology]

[0003] 2. Description of the Related Art Generally, as portable small-sized electric and electronic devices become more widespread, the development of new types of secondary batteries, such as nickel-metal hydride batteries and lithium secondary batteries, is actively progressing.

[0004] The lithium secondary battery refers to a battery that uses carbon such as graphite as the negative electrode active material, an oxide containing lithium as the positive electrode material, and a non-aqueous solution as the electrolyte.

[0005] Secondary batteries can be classified into coin-type secondary batteries, square-type secondary batteries, cylindrical-type secondary batteries, pouch-type secondary batteries, etc., depending on the shape of the battery case.

[0006] In a secondary battery, an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode is stacked and housed in a battery case. The electrode assemblies housed in the battery case can be specifically classified into a jelly-roll type (or a winding type) in which a separator is interposed between a sheet-like positive electrode and a sheet-like negative electrode coated with an active material and the electrode is wound up, a stack type in which a number of positive electrodes and anodes are stacked in sequence with a separator interposed therebetween, and a stack / folding type in which a stack type unit cell is wound up with a long separator.

[0007] The stack-type electrode assembly is manufactured by laminating electrodes that have been cut under strong heat and pressure onto a separator to produce a mono cell, stacking them in order, and finally stacking a half cell on top. In addition, a process of attaching tape at regular intervals may be performed to fix the stacked mono cell and half cell as one unit.

[0008] It is necessary to inspect such stack cells for the presence or absence of creases in the separation membrane.

[0009] FIG. 1 is a diagram for explaining an example of a separation membrane breaking in a conventional stack cell.

[0010] The stack cell 10 includes an electrode 11 and a separator 12 laminated on the electrode 11 .

[0011] The separator 12 may be formed in a polygonal shape, for example, a rectangle having a long side 12d and a short side 12c.

[0012] Referring to FIG. 1, recently, a stack cell 10 is irradiated with radiation such as X-ray in an inspection method, and the presence or absence of folding of the separator 12 is confirmed using an image obtained by the irradiated radiation.

[0013] Usually, an operator visually checks whether or not there are any folds F in the separation membrane 12 from the photograph obtained by radiation.

[0014] 1(a), the separation membrane 12 may have a fold F at a corner portion 12a-1 between a long side 12d and a short side 12c of the edge region 12a. As another example, the separation membrane 12 may be formed in a region of the long side 12d or the short side 12c of the edge region. In particular, as shown in FIG. 1(b), the separation membrane 12 may have a fold F at a region 12a-2 on the long side 12d side of the edge region 12a.

[0015] However, there is a problem in that it is difficult for an operator to accurately determine with the naked eye through the photograph whether or not a fold F has occurred in a corner portion 12a-1 of the end region 12a of the separation membrane 12 or in one region 12a-2 of the long side. Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention aims to provide a stack cell, a separation membrane inspection device, and an inspection method that make it easy to check for a break in the separation membrane by using radiation and allowing an operator to easily determine whether or not a break in the separation membrane has occurred with the naked eye. [Means for solving the problem]

[0017] In order to solve the above-mentioned problems, a stack cell according to an embodiment of the present invention includes an electrode, a separator surrounding the electrode, and a mark formed of a radiation-impermeable material that does not transmit radiation and provided at an end region of the separator. In this case, the electrode may be a positive electrode or a negative electrode, and in this document, the positive electrode may include a positive electrode current collector (e.g., aluminum) and a positive electrode active material coated on the positive electrode current collector, and the negative electrode may include a negative electrode current collector (e.g., copper) and a negative electrode active material coated on the negative electrode current collector.

[0018] In addition, the electrode and the separator laminated on the electrode may form a unit cell, and a plurality of unit cells may be laminated to form an electrode assembly. In addition, the separator has an area larger than that of the electrode, and the electrode is in contact with the center of the separator. In this document, an edge region of the separator refers to a portion that is not in contact with the electrode.

[0019] In this document, a stack cell includes one or more unit cells, and may include a single unit cell or a plurality of stacked unit cells.

[0020] The mark may be provided so as to fold together with the edge region of the separation membrane when the edge region of the separation membrane folds.

[0021] The mark may be provided such that, when the separation film is folded, at least a portion of the mark moves in position along a folding direction of the separation film.

[0022] Also, the mark may be provided at a corner portion of an edge region of the separation film.

[0023] The mark may be provided in an end region on a long side or a short side of the separation film.

[0024] Also, the mark may be formed continuously along an edge region of the separation film.

[0025] Also, the mark may be integrally formed over the entire edge region of the separation film.

[0026] Also, a plurality of marks may be provided, and the plurality of marks may be formed at different positions on the edge region of the isolation film.

[0027] Also, a stack cell according to another embodiment of the present invention includes a plurality of electrodes, a separator disposed between two adjacent electrodes, and a mark formed of a radiation-impermeable material that does not transmit radiation and disposed in an end region of the separator. Here, the stack cell may include a plurality of unit cells, and each unit cell may include a separator (also referred to as a "first separator"), a positive electrode stacked on the first separator, a separator (also referred to as a "second separator") stacked on the positive electrode, and a negative electrode stacked on the second separator.

[0028] At this time, at least one of the first and second separators may be provided with one or more marks.

[0029] The mark may be provided so as to fold together with the edge region of the separation membrane when the edge region of the separation membrane folds.

[0030] The mark may be provided such that, when the separation film is folded, at least a portion of the mark moves in position along a folding direction of the separation film.

[0031] Also, the mark may be provided at a corner portion of an edge region of the separation film.

[0032] The mark may be provided in an end region on a long side or a short side of the separation film.

[0033] Also, the mark may be formed continuously along an edge region of the separation film.

[0034] Also, the mark may be integrally formed over the entire edge region of the separator.

[0035] Also, a plurality of marks may be provided, and the plurality of marks may be formed at different positions on the edge region of the isolation film.

[0036] Furthermore, a separation membrane inspection apparatus (also referred to as a "stack cell inspection apparatus") according to yet another embodiment of the present invention includes a radiation inspection unit configured to irradiate radiation toward the stack cell and acquire an image of the separation membrane irradiated with the radiation, and a control unit configured to inspect the separation membrane for folds by comparing position information of a mark pre-formed on the separation membrane with position information of a mark in the image acquired by the radiation inspection unit.

[0037] The control unit may be configured to output a result of inspecting whether the separation membrane is bent to an outside.

[0038] Furthermore, a separation film inspection method (also referred to as a "stack cell inspection method") according to another embodiment of the present invention may include a step (a) of irradiating radiation to a stack cell including a separation film having a mark formed of a radiation-non-transparent material at an end region thereof, a step (b) of acquiring an image of the separation film irradiated with radiation, and a step (c) of inspecting for a bend in the separation film by comparing position information of the mark previously formed on the separation film with position information of the mark appearing in the acquired image.

[0039] Also, in step (a), the mark may be provided so as to fold together with the edge region of the separation film when the edge region of the separation film is folded.

[0040] Also, in step (a), the mark may be provided at a corner portion of an edge region of the separator.

[0041] Also, in step (a), the mark may be provided on a long side edge or a short side edge of the separator.

[0042] Also, in step (a), a plurality of marks may be provided, and the plurality of marks may be formed at different positions on the edge region of the separator. Effect of the Invention

[0043] As described above, the stack cell capable of easily checking the folding of the separation membrane, the inspection device and the inspection method for the separation membrane according to an embodiment of the present invention have the following advantages.

[0044] When checking for creases in the separation membrane using an image taken after irradiating the membrane with radiation, creases in the separation membrane can be easily determined based on the position information of the marks through which radiation does not penetrate.

[0045] In addition, defective stack cells having folded separators can be easily inspected, thereby improving the manufacturing reliability of secondary batteries. [Brief description of the drawings]

[0046] [Figure 1] FIG. 13 is a diagram for explaining an example of a separation membrane being folded in a conventional stuff cell.

[0047] [Diagram 2] FIG. 1 is a schematic diagram of a stuff cell.

[0048] [Diagram 3] 1 is a schematic diagram illustrating a separation membrane inspection apparatus according to an embodiment of the present invention;

[0049] [Figure 4] FIG. 1 is a plan view showing an embodiment of a stack cell in which folding of a separation membrane can be easily confirmed.

[0050] [Diagram 5] FIG. 5 is an enlarged view of an embodiment in which bending occurs at portion A shown in FIG. 4.

[0051] [Figure 6] 13 is a plan view showing another embodiment of a stack cell in which folding of a separation membrane can be easily confirmed. FIG.

[0052] [Figure 7] FIG. 7 is an enlarged view of an embodiment in which bending occurs at portion B shown in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] Hereinafter, a stack cell 110 capable of easily checking for a bent separation membrane, a separation membrane inspection device 100, and a separation membrane inspection method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0054] In addition, regardless of the drawing symbols, identical or corresponding components will be given the same or similar reference numbers, and duplicate descriptions thereof will be omitted, and the size and shape of each component illustrated may be exaggerated or reduced for the convenience of explanation.

[0055] The stack cell 110, separator inspection device 100, and method for easily checking for separator folds according to an embodiment of the present invention may be performed after notching / punching of electrodes and before a stacking process is performed during a process of manufacturing a pouch-type secondary battery.

[0056] FIG. 2 is a schematic diagram of a stack cell 110, and FIG. 3 is a schematic diagram of a separation membrane inspection apparatus 100 according to an embodiment of the present invention.

[0057] The stack cell 110 may include one or more unit cells. For example, the unit cell may include an electrode 111 and a separator 112 stacked on the electrode 111. The electrode 111 may be a positive electrode or a negative electrode. As another example, the unit cell may include a plurality of electrodes 111-1 and 111-2 and a separator 112 interposed between two adjacent electrodes 111-1 and 111-2. For example, referring to FIG. 2, the stack cell 110 may include a separator 112 (also referred to as a "first separator"), a positive electrode 111-1 stacked on the first separator, a separator 112 (also referred to as a "second separator") stacked on the positive electrode 111-1, and a negative electrode 111-2 stacked on the second separator 112.

[0058] In addition, the stack cell 110 may be an electrode assembly in which a plurality of unit cells, each having a separator 112 interposed between a positive electrode 111-1 and a negative electrode 111-2, are stacked in a stack structure.

[0059] In addition, the separator 112 has an area larger than that of the electrodes 111 (111-1, 111-2), and the electrode 111 may be in contact with the center of the separator 112. In this document, the end region 112a of the separator 112 in the stack cell 110 refers to a portion that is not in contact with the electrodes 111-1, 111-2.

[0060] 3, for example, a stack cell 110 may include at least one electrode 111 and a separator 112 surrounding the electrode 111. The electrode 111 may be a positive electrode or a negative electrode.

[0061] In this document, the z-axis direction indicates the stacking direction of the stack cells 110, the x-axis direction indicates the direction parallel to the short side of the stack cell (or separation membrane), and the y-axis direction indicates the direction parallel to the long side of the stack cell (or separation membrane).

[0062] FIG. 4 is a plan view showing one embodiment of a stack cell in which folding of a separation membrane can be easily confirmed, and FIG. 5 is an enlarged view showing an embodiment in which folding occurs at portion A shown in FIG.

[0063] 6 is a plan view showing another embodiment of a stack cell in which it is easy to check for creases in the separation membrane, and FIG. 7 is an enlarged view showing an embodiment in which creases occur in portion B shown in FIG. 6.

[0064] 3, the separation membrane 112 may have a substantially rectangular shape having a long side 112d and a short side 112c. The edge region 112a of the separation membrane 112 may include an edge region on the long side 112d side and an edge region on the short side 112c side.

[0065] In the stack cell 110, one or more marks 1121, 1123 may be formed at predetermined positions on the separation membrane 112. The marks 1121, 1123 may be provided on the separation membrane 112.

[0066] At this time, the marks 1121 and 1123 may be provided in the edge region 112a where the folds F of the separation film 112 tend to occur.

[0067] 4 and 5, the marks 1121 and 1123 may be provided at a corner portion 112a-1 of an end region 112a of the separation film 112. In this case, the corner portion 112a-1 refers to a boundary region between a long side 112d and a short side 112c of the separation film 112.

[0068] 6 and 7, the mark 1123 may be provided in a region of the long side 112d or the short side 112c, but not in a corner portion 112a-1 formed between the long side 112d and the short side 112c of the end region 112a of the separation film 112. For example, the mark 1123 may be provided in a region 112a-2 of the long side 112d of the end region 112a of the separation film 112.

[0069] Referring to Figures 4 to 7, the marks 1121 and 1123 are shown to be provided only at one of different positions, namely, the corner portion 112a-1 and one region 112a-2 of the long side, of the end region 112a of the separation film 112. However, the marks 1121 and 1123 may be provided at both the corner portion 112a-1 of the end region 112a of the separation film 112 and one region 112a-2 of the long side 112d.

[0070] Also, the marks 1121 and 1123 may be continuously formed along the edge region 112a of the separation film 112. That is, the marks 1121 and 1123 may have a shape extended by a predetermined length, and may have a shape extended by a predetermined length along the length direction of the long side 112d or the short side 112c.

[0071] In addition, when the mark 1121 is provided at the corner portion 112a-1 of the edge region 112a of the separation film 112, the mark 1121 may have a shape that is extended by a predetermined length to each of the long side 112d and the short side 112c connected to the corner portion 112a-1.

[0072] Alternatively, the marks 1121 and 1123 may be integrally formed over the entire edge region 112 a of the separation film 112 .

[0073] As described above, the positions of the marks 1121 and 1123 formed on the separation film 112 may be changed and are not limited to the above example.

[0074] Also, the marks 1121 and 1123 may be provided on one side (surface) of the edge region of the separation membrane 112 .

[0075] For example, when a plurality of separation membranes 112 are stacked in the stack cell 110, the marks 1121 and 1123 may be provided on one or more separation membranes 112, or on each of the plurality of separation membranes 112.

[0076] The marks 1121 and 1123 may be made of a radio-opaque material so that the radiation irradiated from the radiation inspection unit 120 does not penetrate the marks.

[0077] The marks 1121, 1123 may be made of a metal material such as copper (Cu), which is a material that is opaque to radiation, but are not necessarily limited to this, and may be formed of a material that has non-transparent properties and is chemically stable inside the stack cell 110.

[0078] Also, the marks 1121 and 1123 may be formed on the separation film 112 by transferring or coating a material that is opaque to radiation. The marks 1121 and 1123 may be provided on the separation film 112 before it is stacked on the stack cell 110. That is, the stack cell 110 may be manufactured by stacking the separation films 112 on which the marks 1121 and 1123 are formed.

[0079] Also, the marks 1121 and 1123 may be provided to be folded together with the end region 112a of the separation film 112 when the end region of the separation film 112 is folded.

[0080] In addition, the marks 1121 and 1123 may be provided such that at least a portion of the marks 1121 and 1123 moves along the folding direction of the separation film 112 when the separation film 112 is folded.

[0081] The separation membrane inspection apparatus 100 and inspection method according to an embodiment of the present invention may be used to irradiate radiation onto the stack cell 110 and inspect whether or not the separation membrane 112 in the stack cell 110 is bent.

[0082] Referring to FIG. 3, a separation membrane inspection apparatus 100 according to one embodiment of the present invention may include a radiation inspection unit 120 that irradiates radiation on a stack cell 110 having marks 1121 and 1123 formed thereon and acquires an image of the separation membrane 112 irradiated with radiation, and a control unit 130 that inspects for folds in the separation membrane 112 using the acquired image.

[0083] The radiation inspection unit 120 irradiates radiation toward the stack cell 110 on which the marks 1121 and 1123 are formed. In addition, the radiation inspection unit 120 irradiates radiation such as X-ray toward the stack cell 110 on which the marks 1121 and 1123 are formed on the separation film 112, and can obtain an image of the separation film 112 irradiated with radiation.

[0084] At this time, the marks 1121 and 1123 may be made of a radio-impermeable material so that the radiation irradiated from the radiation inspection unit 120 does not penetrate the marks.

[0085] At this time, even if radiation is irradiated from the radiation inspection unit 120 to the stack cell 110 , it cannot penetrate the marks 1121 and 1123 formed on the separation film 112 .

[0086] In this case, in the image acquired by the radiological inspection unit 120, the marks 1121 and 1123 move from first positions 1121a and 1123a along the folding direction of the separation film 112 to second positions 1121b and 1123b due to the folding F of the separation film 112. In this document, the first positions 1121a and 1123a refer to initial positions where the marks are formed when the separation film is not folded, and the second positions 1121b and 1123b refer to changed positions of the folded marks together with the edge regions of the separation film along the folding direction of the separation film 112.

[0087] 4 to 7, when the separation film 112 is folded (F), the marks 1121 and 1123 may be displayed at second positions 1121b and 1123b depending on the folding state of the separation film 112. Since the separation film 112 is folded toward the electrode 111 as a whole, the marks 1121 and 1123 may be displayed at second positions 1121b and 1123b where at least a portion of the separation film 112 overlaps with the electrode 111 along the folding direction.

[0088] As a result, the operator can easily determine whether the separator 112 is bent or not based on the positions of the marks 1121 and 1123 in the image acquired by the radiation inspection unit 120.

[0089] In addition, the control unit 130 can compare position information of the marks 1121 and 1123 preliminarily formed on the separation film 112 with position information of the marks 1121 and 1123 in the image acquired by the radiation inspection unit 120 to inspect and determine whether or not the separation film 112 is bent F.

[0090] Meanwhile, the control unit 130 can determine whether the separator 112 is bent using a machine learning technique.

[0091] Generally, machine learning techniques refer to algorithms that allow a computer to learn and make predictions based on data input by a user.

[0092] Furthermore, the control unit 130 may output the result of the determination to the outside and generate a notification corresponding to the folded state of the separation membrane 112 to the operator.

[0093] Hereinafter, a separation membrane testing method according to an embodiment of the present invention will be briefly described with reference to FIGS.

[0094] First, the method includes forming a stack cell 110 by stacking an electrode 111 and a separator 112 on the electrode 111. Also, the separator 112 has marks 1121 and 1123 formed in an end region 112a.

[0095] As described above, the marks 1121 and 1123 may be formed at various positions in the edge region 112 a of the separator 112 .

[0096] Also, the marks 1121 and 1123 may be formed at various positions on the edge region 112a of the separator 112 by transferring or coating a material that is opaque to radiation.

[0097] The inspection method may include a step (a) of irradiating radiation to a stack cell 110 including a separation film having a mark at an end region, a step (b) of acquiring an image of the separation film 112 irradiated with radiation, and a step (c) of inspecting for bends in the separation film 112 by comparing position information of the marks 1121, 1123 pre-formed on the separation film 112 with position information of the marks 1121, 1123 appearing in the acquired image.

[0098] In step (a), radiation is irradiated toward the separation membrane 112 of the stack cell 110 using the radiation inspection unit 120 of the separation membrane inspection device 100 .

[0099] Thereafter, an image of the irradiated separation film 112 is obtained (step (b)).

[0100] In the image of the separation membrane 112 acquired in step (b), the marks 1121 and 1123 may be displayed at preset first positions 1121a and 1123a, or at preset second positions 1121b and 1123b.

[0101] Thereafter, the position information of the marks 1121 and 1123 is compared to check whether the separation film 112 is bent (step (c)).

[0102] In step (c), the position information of the marks 1121, 1123 formed beforehand on the separation film 112 is compared with the position information of the marks 1121, 1123 appearing in the acquired image.

[0103] At this time, the radiation irradiated through the radiation inspection unit 120 cannot pass through the marks 1121, 1123 pre-formed on the separation film 112, so if the separation film 112 is broken, the image information acquired by the radiation inspection unit 120 may appear as if the marks 1121, 1123 are displayed at second positions 1121b, 1123b rather than first positions 1121a, 1123a along the direction in which the separation film 112 is broken.

[0104] In step (c), the control unit 130 compares the position information of the marks 1121 and 1123 formed on the separator 112, and inspects and judges whether the separator 112 is bent based on the compared position information, thereby identifying defects in the separator 112.

[0105] For example, when the image acquired by the radiological inspection unit 120 shows that the marks 1121 and 1123 are at the first positions 1121a and 1123a, it can be determined that the separation membrane 112 is not broken and the separation membrane 112 is identified as normal. Conversely, when the image acquired by the radiological inspection unit 120 shows that the marks 1121 and 1123 are at the second positions 1121b and 1123b, it can be determined that the separation membrane 112 is broken and the separation membrane 112 is identified as defective.

[0106] The above-described embodiment of the present invention has been disclosed for illustrative purposes, and a person skilled in the art having ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions are to be considered as falling within the scope of the following claims. [Industrial Applicability]

[0107] According to an embodiment of the present invention, a stack cell, a separation membrane inspection device, and an inspection method for easily checking for a crease in a separation membrane can easily determine whether a separation membrane is bent from an object photographed by irradiating radiation.

Claims

1. A plurality of electrodes; a separator disposed between two adjacent electrodes; and A stack cell including a mark formed of a radio-opaque material that does not transmit radiation and provided in an end region of the separation membrane.

2. The stack cell according to claim 1 , wherein the mark is provided so as to fold together with the end region of the separation membrane when the end region of the separation membrane folds.

3. The stack cell according to claim 2 , wherein the mark is provided such that, when the separation film is folded, at least a portion of the mark moves in position along a folding direction of the separation film.

4. The stack cell according to claim 1 , wherein the mark is provided at a corner portion of the end region of the separation film.

5. The stack cell according to claim 1 , wherein the mark is provided in the end region on a long side or a short side of the separation film.

6. The stack cell according to claim 1 , wherein the mark is formed continuously along the end region of the separation film.

7. The stack cell according to claim 1 , wherein the mark is integrally formed over the entire end region of the separation membrane.

8. The mark is provided in a plurality, The stack cell according to claim 1 , wherein the marks are formed at different positions in the end region of the isolation film.

9. a radiation inspection unit configured to irradiate radiation toward the stack cell according to claim 1 and obtain an image of the separation membrane irradiated with the radiation; and a control unit that compares position information of the mark preliminarily formed on the separation film with position information of the mark in an image acquired by the radiation inspection unit to inspect the separation film for folds.

10. The separation membrane inspection device according to claim 9 , wherein the control unit is configured to output a result of inspecting the separation membrane for creases to an outside.

11. (a) irradiating a stack cell including a separation membrane having a mark formed of a radiation non-transparent material at an end region thereof with radiation; (b) acquiring an image of the separation membrane irradiated with the radiation; and The method includes the step (c) of inspecting the separation film for bends by comparing position information of a mark previously formed on the separation film with position information of the mark appearing in the acquired image.

12. The method of claim 11, wherein in step (a), the mark is provided so as to bend together with the end region of the separation membrane when the end region of the separation membrane is bent.

13. The method of claim 11, wherein in step (a), the mark is provided at a corner portion of the end region of the separation membrane.

14. The method of claim 11, wherein in step (a), the mark is provided on a long side edge or a short side edge of the separation membrane.

15. In step (a), the mark is provided in a plurality of pieces, The separation membrane inspection method according to claim 11 , wherein the plurality of marks are formed at different positions in the end region of the separation membrane.

Images