Stack cell that allows easy confirmation of separation membrane folds, 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 in a stack cell by using image information acquired by irradiating radiation.

[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 herein by reference. [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] A secondary battery is formed by stacking electrode assemblies, each including a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes, and housing them in a battery case. The electrode assemblies housed in the battery case can be specifically classified into a jelly-roll type (also known as a winding type) in which a separator is interposed between sheet-like positive and negative electrodes coated with an active material and wound up, a stack type in which multiple positive and negative electrodes are stacked one after the other 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 stacked electrode assembly is manufactured by laminating electrodes that have been cut under strong heat and pressure onto a separator to form a mono cell, stacking these mono cells one by one, and finally stacking a half cell on top. In addition, a tape attachment process may be performed at regular intervals to secure the stacked mono cell and half cell together as a single 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 illustrating 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 stacked on the electrode 11 .

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

[0012] Referring to FIG. 1, recently, a stack cell 10 is irradiated with radiation using an inspection method using radiation such as X-ray, 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 12a-1 between the long side 12d and the 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 to accurately determine with the naked eye whether or not a fold F has occurred in the corner portion 12a-1 of the edge region 12a of the separation membrane 12 or in one region 12a-2 of the long side through the photograph taken by the worker. 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 allow an operator to easily determine whether a separation membrane is broken with the naked eye when checking for a break in the separation membrane using radiation, and that facilitate checking for a break in the separation membrane. [Means for solving the problem]

[0017] To solve the above-mentioned problems, a stack cell according to one embodiment of the present invention includes an electrode, a separator surrounding the electrode, and a mark formed of a radiation-impermeable material and provided in an edge region of the separator. Here, the electrode may be a positive electrode or a negative electrode, and in this document, the positive electrode includes 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 includes a negative electrode current collector (e.g., copper) and a negative electrode active material coated on the negative electrode current collector.

[0018] The electrode and the separator stacked on the electrode may form a unit cell, and a plurality of unit cells may be stacked to form an electrode assembly. 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, the edge region of the separator refers to a portion that is not in contact with the electrode.

[0019] Also, 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 the folding direction of the separation film.

[0022] The mark may be provided at a corner 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] The mark may be formed continuously along the 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 marks may be formed at different positions on the edge region of the isolation film.

[0027] Furthermore, 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 and disposed in an edge 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 the folding direction of the separation film.

[0031] The mark may be provided at a corner 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] The mark may be formed continuously along the edge region of the separation film.

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

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

[0036] Furthermore, a separation membrane inspection device (also referred to as a "stack cell inspection device") according to 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 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 the 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 onto a stack cell including a separation film having a mark formed of a radiation-impermeable material in 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 crease 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] 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] In step (a), the mark may be provided at a corner of the edge region of the separator.

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

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

[0043] As described above, the stack cell, separation membrane inspection device, and separation membrane inspection method that allow easy confirmation of folding of the separation membrane according to an embodiment of the present invention have the following advantages.

[0044] When checking for creases in the separation membrane in an image taken after irradiating it with radiation, creases in the separation membrane can be easily determined based on the position information of the marks that are opaque to radiation.

[0045] Furthermore, defective stack cells with folded separators can be easily inspected, thereby improving the manufacturing reliability of secondary batteries. [Brief explanation of the drawings]

[0046] [Figure 1] FIG. 10 is a diagram illustrating an example of a separation membrane being broken in a conventional stuff cell.

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

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

[0049] [Figure 4] FIG. 10 is a plan view showing an embodiment of a stack cell in which folding of a separation membrane can be easily confirmed.

[0050] [Figure 5] 5 is an enlarged view of an example in which a break occurs in part A shown in FIG. 4. FIG.

[0051] [Figure 6] FIG. 10 is a plan view showing still another embodiment of a stack cell in which folding of a separation membrane can be easily confirmed.

[0052] [Figure 7] FIG. 7 is an enlarged view of an example in which a break occurs at portion B shown in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

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

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

[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 the electrode plates and before the stacking process during the 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 device 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] 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 a larger area than the electrodes 111 (111-1, 111-2), and the electrodes 111 may be in contact with the center of the separator 112. In this document, the edge 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 cell 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 an embodiment of a stack cell in which folding of the separation membrane can be easily confirmed, and FIG. 5 is an enlarged view showing an embodiment in which folding occurs at part 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 part B shown in FIG. 6.

[0064] The separation membrane 112 may have a polygonal shape, for example, may have a roughly rectangular shape having a long side 112d and a short side 112c as shown in Fig. 3. 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 and 1123 may be formed at predetermined positions on the separation membrane 112. The marks 1121 and 1123 may be provided on the separation membrane 112.

[0066] In this case, the marks 1121 and 1123 may be provided in the edge region 112a of the separator 112 where the folds F are most likely 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 separator 112. In this case, the corner portion 112a-1 refers to a boundary region between the long side 112d and the short side 112c of the separator 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 112a-1 formed between the long side 112d and the short side 112c of the edge 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 edge 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 of the edge region 112a of the separation film 112, namely, the corner portion 112a-1 and one region 112a-2 of the long side, but the marks 1121 and 1123 may also be provided at both the corner portion 112a-1 of the edge 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 separator 112. That is, the marks 1121 and 1123 may have a shape extending by a predetermined length, and may have a shape extending 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, which are respectively 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] 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 separators 112 are stacked in the stack cell 110, the marks 1121 and 1123 may be provided on one or more separators 112, or on each of the plurality of separators 112.

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

[0077] The marks 1121 and 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 made of a material that has non-transparent properties and is chemically stable inside the stack cell 110.

[0078] In addition, the marks 1121 and 1123 may be formed on the separator 112 by transferring or coating a material that is opaque to radiation. The marks 1121 and 1123 may be provided on the separator 112 before being stacked on the stack cell 110. That is, the stack cell 110 may be manufactured by stacking the separators 112 on which the marks 1121 and 1123 are formed.

[0079] In addition, the marks 1121 and 1123 may be formed to bend together with the end region 112a of the separation film 112 when the end region of the separation film 112 is bent.

[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 device 100 and inspection method according to an embodiment of the present invention can be used to irradiate the stack cell 110 with radiation 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 device 100 according to an embodiment of the present invention may include a radiation inspection unit 120 that irradiates radiation onto 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 acquire 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-opaque material so that the radiation irradiated from the radiation inspection unit 120 does not penetrate therethrough.

[0085] At this time, even if radiation is irradiated from the radiation inspection unit 120 onto the stack cell 110 , it cannot pass through 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 the initial positions where the marks were formed when the separation film was not folded, and the second positions 1121b and 1123b refer to the changed positions of the folded marks along the folding direction of the separation film 112 together with the edge regions of the separation film.

[0087] 4 to 7, when the separator 112 is folded (F), the marks 1121 and 1123 may appear at second positions 1121b and 1123b depending on the folding state of the separator 112. Since the separator 112 is folded toward the electrode 111 as a whole, the marks 1121 and 1123 may appear at second positions 1121b and 1123b where at least a portion of the separator 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 radiological inspection unit 120.

[0089] In addition, the control unit 130 can compare the position information of the marks 1121 and 1123 pre-formed on the separation film 112 with the 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 determination result to the outside and issue a notification corresponding to the folding 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 stack cell 110 is formed by stacking an electrode 111 and a separator 112 on the electrode 111. Also, the separator 112 has marks 1121 and 1123 formed on an end region 112a thereof.

[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 onto a stack cell 110 including a separation film having a mark formed in 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 folds 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 onto 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 acquired (step (b)).

[0100] In the image of the separator 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 separator 112 is bent (step (c)).

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

[0103] In this case, since the radiation irradiated through the radiation inspection unit 120 cannot pass through the marks 1121 and 1123 pre-formed on the separation film 112, when the separation film 112 is broken, the image information acquired by the radiation inspection unit 120 may appear as if the marks 1121 and 1123 are displayed at second positions 1121b and 1123b, rather than first positions 1121a and 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 determines whether the separator 112 is bent based on the compared position information, thereby identifying defects in the separator 112.

[0105] For example, if the image acquired by the radiography 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 can be identified as normal. Conversely, if the image acquired by the radiography 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 can be 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 with ordinary skill in the art may make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions must be considered to fall 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 break in a separation membrane can easily determine whether a separation membrane is broken from an object photographed by irradiating it with radiation.

Claims

1. a plurality of electrodes; a separator disposed between two adjacent electrodes; and The separator is made of a radiopaque material that does not transmit radiation, and includes a mark provided in an edge region of the separator; 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.

2. A stack cell as described in claim 1, wherein the mark is arranged so that when the separation membrane is folded, at least a portion of the mark moves in position along the folding direction of the separation membrane.

3. A plurality of electrodes; a separator disposed between two adjacent electrodes; and The separator is made of a radiopaque material that does not transmit radiation, and includes a mark provided in an edge region of the separator; The mark is provided at a corner portion of the end region of the separation membrane.

4. A plurality of electrodes; a separator disposed between two adjacent electrodes; and The separator is made of a radiopaque material that does not transmit radiation, and includes a mark provided in an edge region of the separator; The mark is provided in the end region on the long side or short side of the separation membrane.

5. A plurality of electrodes; a separator disposed between two adjacent electrodes; and The separator is made of a radiopaque material that does not transmit radiation, and includes a mark provided in an edge region of the separator; The mark is formed continuously along the edge region of the separation film.

6. A plurality of electrodes; a separator disposed between two adjacent electrodes; and The separator is made of a radiopaque material that does not transmit radiation, and includes a mark provided in an edge region of the separator; A stack cell, wherein the mark is integrally formed over the entire end region of the separation membrane.

7. A plurality of electrodes; a separator disposed between two adjacent electrodes; and The separator is made of a radiopaque material that does not transmit radiation, and includes a mark provided in an edge region of the separator; The mark is provided in plural, The stack cell, wherein the plurality of marks are formed at different positions in the edge region of the separation film.

8. a radiation inspection unit configured to irradiate radiation toward the stack cell according to any one of claims 1 to 7 and acquire 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 membrane with position information of the mark in an image acquired by the radiation inspection unit to inspect for folds in the separation membrane.

9. The separation membrane inspection device according to claim 8 , wherein the control unit is configured to output a result of inspecting the separation membrane for creases to an external device.

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

11. The separation membrane inspection method according to claim 10 , 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.

12. The method of claim 10 , wherein in step (a), the mark is provided at a corner of the edge region of the separation membrane.

13. The method of claim 10, wherein in step (a), the mark is provided on a long side edge or a short side edge of the separation membrane.

14. In step (a), the mark is provided in a plurality of marks, The separation membrane inspection method according to claim 10 , wherein the plurality of marks are formed at different positions in the edge region of the separation membrane.

Images