System and method for detecting misalignment of electrodes

Abstract

According to one embodiment of the present invention, a system for detecting misalignment includes: a reference fixture on which an electrode assembly is disposed; a beam generator for irradiating X-rays at a first angle and a second angle relative to the electrode assembly and a corner of the reference fixture; and a calculation unit for calculating the position coordinates of a corner of the electrode assembly located at the corner of the reference fixture.

Description

Technical Field

[0001] The present invention relates to an inspection method of a rechargeable battery, and more particularly, to providing a system and method capable of easily detecting an alignment state of electrodes of a rechargeable battery having a stacked electrode assembly. Background Art

[0002] Unlike primary batteries, rechargeable batteries can be repeatedly charged and discharged. Low-capacity rechargeable batteries are used in small portable electronic devices such as mobile phones, notebook computers, and video cameras, and large-capacity rechargeable batteries are used as power sources for driving motors such as for hybrid vehicles.

[0003] This rechargeable battery includes: an electrode assembly having a structure in which positive electrodes, separators, and negative electrodes are alternately stacked; a case for accommodating the electrode assembly in the case; a cap plate for sealing an opening of the case; and an electrode terminal disposed on the cap plate to be electrically connected to the electrode assembly.

[0004] The electrode assembly may have a jelly roll structure formed by spirally winding a positive electrode, a separator, and a negative electrode in a stacked state, or may have a stack structure in which a positive electrode, a separator, and a negative electrode are individually and repeatedly stacked.

[0005] Among the structures of the electrode assemblies, the structure of a stacked type electrode assembly is formed by repeatedly stacking separately formed positive electrodes, separators, and negative electrodes, and affects safety of a secondary battery according to alignment states with each other.

[0006] Therefore, it is necessary to check their alignment during the manufacturing process, but it is not easy to visually grasp the stacking state of the positive electrode and the negative electrode in the form of thin plates, and the accuracy is poor. Summary of the invention

[0007] Technical issues

[0008] Aspects of the present invention are to provide a system and method for detecting misalignment of electrodes (hereinafter referred to as "misalignment") which can easily grasp the alignment state of electrodes of a stacked electrode assembly.

[0009] Technical Solution

[0010] An exemplary embodiment of the present invention provides a misalignment detection system, which includes: a reference fixture on which an electrode assembly is disposed; a beam generator configured to irradiate X-rays at a first angle and a second angle relative to any one corner of the electrode assembly and the reference fixture; and a calculation unit configured to calculate the position coordinates of a corner of the electrode assembly located at the corner of the reference fixture.

[0011] The reference jig may have a step portion which is spaced apart from a corner of the reference jig by a predetermined distance and protrudes to an upper portion of the reference jig.

[0012] The calculation part may compensate coordinates calculated by comparing position coordinates of a corner of the step portion located at a corner of the reference jig with actually measured position values.

[0013] The electrode assembly may be a stacked electrode assembly.

[0014] An exemplary embodiment of the present invention provides a method for detecting misalignment of electrodes of an electrode assembly, the method comprising: setting the electrode assembly on a reference fixture; obtaining first coordinates of the vertices of each of the positive electrode and the negative electrode located at a first corner of the reference fixture and a first corner of the electrode assembly; calculating a first distance between the vertex of each negative electrode and the vertex of each positive electrode in the electrode assembly set at the first coordinate; and determining the misalignment of the positive electrode and the negative electrode by comparing the first distance with a reference distance.

[0015] The step of obtaining the first coordinates may include: performing a first X-ray imaging of the first corner at a first angle; and performing a second X-ray imaging of the first corner at a second angle, and the first coordinates may be obtained through the first X-ray image and the second X-ray image.

[0016] The method may further include compensating the distance value and coordinates measured by obtaining the measured distance between the vertex of the reference jig located at the first coordinate and the vertex of the step portion of the reference jig and the actual angle irradiated from the actual measured distance during actual imaging.

[0017] The method may also include obtaining second coordinates of vertices located at a second corner of the reference fixture and a second corner of the electrode assembly, and the step of obtaining the second coordinates may include: performing a third X-ray imaging of the second corner at the first angle; and performing a fourth X-ray imaging of the second corner at the second angle.

[0018] The method may further include compensating the distance value and coordinates measured by obtaining the measured distance between the vertex of the reference jig located at the second coordinate and the vertex of the step portion of the reference jig and the actual angle irradiated from the actual measured distance during actual imaging.

[0019] Beneficial Effects

[0020] When using the misalignment detection system according to an exemplary embodiment of the present invention, the coordinates of the corner vertices of the positive electrode and the negative electrode can be easily obtained. Therefore, the relative distance between the positive electrode and the negative electrode can be obtained through the coordinates, thereby easily detecting the misalignment between the positive electrode and the negative electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram illustrating an X-ray imaging apparatus according to an exemplary embodiment of the present invention is shown.

[0022] Figure 2 A schematic top view for describing X-ray imaging is shown.

[0023] Figure 3 A schematic exploded perspective view of an electrode assembly according to an exemplary embodiment of the present invention is shown.

[0024] Figure 4 A method of inspecting alignment of electrodes according to an exemplary embodiment of the present invention is shown.

[0025] Figures 5 to 7 A diagram for describing a coordinate obtaining method according to an exemplary embodiment of the present invention is shown.

[0026] Figure 8 A top view showing a reference fixture and an electrode assembly according to an exemplary embodiment of the present invention is shown.

[0027] Fig. 9 The image is shown at a first angle and a second angle. Figure 8 Schematic cross-sectional view of the reference fixture and electrode assembly.

[0028] Fig.10 and Fig.11 A diagram for describing a method of obtaining distances between vertices according to an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0029] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art will realize, the described embodiments may be modified in various different ways, all without departing from the scope of the present invention.

[0030] In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals denote the same or similar constituent elements throughout the specification.

[0031] Furthermore, since the sizes and thicknesses of constituent members shown in the drawings are arbitrarily given for better understanding and ease of description, the present invention is not limited to the sizes and thicknesses shown in the drawings.

[0032] Throughout this specification and the appended claims, when it is described that an element is “coupled / connected” to another element, the element may be “directly coupled / directly connected” to the other element or “indirectly coupled / indirectly connected” to the other element through a third element. In addition, unless explicitly described to the contrary, the word “comprise” and its various variations will be understood to imply the inclusion of the stated elements but not the exclusion of any other elements.

[0033] In the accompanying drawings, the thickness of layers, films, panels, regions, etc., is exaggerated for clarity. In the accompanying drawings, the thickness of some layers and regions is exaggerated for better understanding and ease of description. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, the element may be directly on the other element, or there may be an intermediate element. In addition, in this specification, the words "on..." or "above..." mean being located on or below an object portion, and do not necessarily mean being located on the upper side of an object portion based on the direction of gravity.

[0034] Hereinafter, a rechargeable battery according to exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0035] Figure 1 shows a schematic diagram showing an X-ray imaging apparatus according to an exemplary embodiment of the present invention, Figure 2 A schematic top view for describing X-ray imaging is shown.

[0036] like Figure 1 As shown in , an X-ray imaging apparatus 1000 according to an exemplary embodiment of the present invention includes: a base 10 on which an object is disposed; an imaging unit 200 for imaging the object; and a reference fixture 300 located on the base 10 .

[0037] The imaging unit 200 includes a beam generator 21 for irradiating X-rays, a calculation section 22 for storing and analyzing images, and a display unit 23 for displaying images or data.

[0038] The calculation part 22 may calculate the corner, distance, and coordinates from a target object to be imaged (such as a reference fixture or an electrode assembly) through an image.

[0039] The reference jig 300 is used to check an irradiation angle of X-rays so that the X-rays may be incident on a target object at a predetermined angle.

[0040] The reference jig 300 has a certain thickness, and the step portion 32 may be formed at an upper portion of a base portion 31 of the reference jig 300 (however, hereinafter, the base portion is not distinguished separately and is referred to as a reference jig). Hereinafter, a point where both sides of the reference jig 300 intersect or a point where both sides of the step portion 32 intersect is referred to as a vertex.

[0041] like Figure 2 As shown in , the X-ray may be irradiated to the first corner C1 and the second corner C2 of the reference fixture at predetermined angles θ (eg, first angle and second angle), in which case the first angle may be 30 degrees and the second angle may be 45 degrees.

[0042] Hereinafter, the use of Figure 1 and Figure 2 An alignment inspection apparatus and a method for inspecting alignment of an electrode plate for a rechargeable battery.

[0043] Figure 3 shows a schematic exploded perspective view of an electrode assembly according to an exemplary embodiment of the present invention, Figure 4 A method of inspecting alignment of electrodes according to an exemplary embodiment of the present invention is shown.

[0044] First, if Figure 1 As shown in FIG. 1 , the electrode assembly 400 to be checked for alignment is disposed in the X-ray imaging apparatus 1000 . In this case, the electrode assembly 400 may be disposed within the boundary line of the step portion 32 .

[0045] Reference Figure 3 , the electrode assembly according to an exemplary embodiment of the present invention is a stack type made by repeatedly stacking the negative electrode 41 and the positive electrode 42 with the separator 43 disposed therebetween. The separator 43 may be a polymer film that allows lithium ions to pass therethrough.

[0046] The negative electrode 41 includes an active layer 41a formed by coating an active material on a current collector of a thin metal plate and an uncoated region 41b where the thin metal plate is exposed because no active material is coated thereon. The thin metal plate of the negative electrode 41 may be a thin copper (Cu) plate.

[0047] The positive electrode 42 includes an active layer 42a formed by coating an active material on a current collector of a thin metal plate and an uncoated region 42b where the thin metal plate is exposed because the active material is not coated thereon. The thin metal plate of the positive electrode 42 may be a thin aluminum (Al) plate.

[0048] The plurality of uncoated regions 41b and 42b having the same polarity may be electrically connected to each other to be electrically connected to an external terminal. The uncoated regions 41b and 42b may protrude in the same direction (see Figure 1 and Figure 3 ), but the present invention is not limited thereto, and may protrude in the opposite direction.

[0049] The electrode assembly 400 may be sealed in a pouch type case (not shown), and may protrude outside the pouch through the uncoated regions 41b and 42b or a connection member (not shown) connected to the uncoated regions 41b and 42b to be connected to an external terminal.

[0050] Hereinafter, for convenience of description, one negative electrode 41 and one positive electrode 42 included in the electrode assembly are illustrated as the electrode assembly.

[0051] Reference Figure 4 , the first X-ray imaging is performed at a first angle θ1, and the second X-ray imaging is performed at a second angle θ2 with respect to the first corner C1 of the reference jig 300. In this case, the first angle θ1 may be 45 degrees, and the second angle θ2 may be 30 degrees.

[0052] Next, with respect to the second corner C2 of the reference jig, the third X-ray imaging is performed at the first angle θ1, and the fourth X-ray imaging is performed at the second angle θ2.

[0053] Then, misalignment of the electrode assembly (hereinafter referred to as "misalignment") is determined through the images.

[0054] Figures 5 to 7 A diagram for describing a coordinate obtaining method according to an exemplary embodiment of the present invention is shown.

[0055] The misalignment can be determined by the x-coordinate and the y-coordinate obtained from the following equation, the calculation can be performed by the calculation section of the imaging unit, and the image and the calculation result can be checked by the display unit.

[0056] Hereinafter, a method of obtaining x-coordinates and y-coordinates of two corners (hereinafter, referred to as first and second corners) of the positive and negative electrodes will be described. In this case, the vertices of the first and second corners C1 and C2 may be located on the same side.

[0057] First, if Figure 5 As shown in , the distance d between two parallel straight lines can be obtained by [Equation 1].

[0058] [Equation 1]

[0059]

[0060] Therefore, as [Equation 1] and Figure 5 As shown in , the minimum distance between two parallel straight lines passing through two vertices seen by X-ray imaging can be expressed as distance d.

[0061] In this case, if Figure 6 As shown in , the position of the first vertex at the first corner imaged by X-ray at the first angle θ1 and the second angle θ2 according to the present invention can be represented by a straight line with a slope m1 and a straight line with a slope m2, respectively. Then, as Figure 7 As shown in , since the vertices of the first corner and the second corner are located at opposite sides with respect to one side of the electrode, the straight lines of the second corner with respect to the first angle θ1 and the second angle θ2 may have opposite slopes.

[0062] Therefore, it can be obtained from Figure 8 The straight line shown in derives the coordinates of the first vertex P1 of the reference jig 300 at the first corner and the coordinates of the second vertex P2 of the step portion 32 .

[0063] This will be described in more detail below.

[0064] Figure 8 1 shows a top view of a reference fixture and an electrode assembly according to an exemplary embodiment of the present invention, Fig. 9 The image is shown at a first angle and a second angle. Figure 8 Schematic cross-sectional view of the reference fixture and electrode assembly, Fig.10 and Fig.11 A diagram for describing a method of obtaining distances between vertices according to an exemplary embodiment of the present invention is shown.

[0065] like Figure 8 and Fig. 9 As shown in FIG. 1 , at the first corner, the vertex of the reference jig 300 is referred to as the first vertex P1, the vertex of the step portion 32 is referred to as the second vertex P2, the vertex of the negative electrode 41 is referred to as the third vertex P3, and the vertex of the positive electrode 42 is referred to as the fourth vertex P4. Then, at the second corner, the vertex of the reference jig 300 is referred to as the fifth vertex P5, the vertex of the step portion 32 is referred to as the sixth vertex P6, the vertex of the negative electrode 41 is referred to as the seventh vertex P7, and the vertex of the positive electrode 42 is referred to as the eighth vertex P8.

[0066] First, by using the first straight line YY1 and the second straight line YY2 of the slope m1 parallel at the first angle θ1 and the third straight line YO1 and the fourth straight line YO2 of the slope m2 parallel at the second angle, the coordinates of the first vertex P1 of the reference jig 300 located at the first corner and the coordinates of the second vertex P2 of the step portion 32 can be obtained. Hereinafter, the straight line passing through the vertex of the negative electrode and the straight line passing through the vertex of the positive electrode at the first angle θ1 are referred to as Y1, Y2, ... (the negative electrode and the positive electrode are alternately 1, 2, 3, 4, ..., and this is also the case hereinafter), and the straight line passing through the vertex of the negative electrode and the straight line passing through the vertex of the positive electrode at the second angle θ2 are referred to as W1, W2, .... At the second corner, the straight line passing through the vertex of the negative electrode and the straight line passing through the vertex of the positive electrode at the first angle θ1 are referred to as Y1', Y2', ..., and the straight line passing through the vertex of the negative electrode and the straight line passing through the vertex of the positive electrode at the second angle θ2 are referred to as W1', W2', ....

[0067] in this case, Figure 8 and Fig. 9 The distance between the first vertex P1 and the third vertex P3 shown in FIG. 1 at the first angle θ1 is referred to as h i , at the second angle θ2 is called (i=1, 2, 3, . . . and this also applies hereinafter). The distance between the first vertex P1 and the fourth vertex P4 at the first angle θ1 is referred to as e i , at the second angle θ2 is called f i The distances between the first vertex P1 and the second vertex P2 as references are referred to as r1 and r2 at the first angle θ1 and the second angle θ2, respectively.

[0068] Figure 8 The distance between the two parallel straight lines shown in can be obtained from [Equation 1]. For example, a method for obtaining the distance between the first vertex P1 and the third vertex P3 will be described. As can be seen, the values ​​of |ba| in the above [Equation 1] are a and b when the slopes are m1 and m2, respectively. Figure 8 and Fig.10 The first straight line YY1, the second straight line Y1, the third straight line YO1 and the fourth straight line W1 are y=m1x, y=m1x+a i , y = m2x and y = m1x + b i Therefore, the a of the first straight line YY1 and the second straight line Y1 is obtained as follows i , and obtain the b of the third straight line YO1 and the fourth straight line W1 i .

[0069] m1 and m2 can be obtained by using tan(θ1) and tan(θ2), respectively.

[0070]

[0071]

[0072] (for h>0)(i=1, 2, ..., n)

[0073] (For h<0)

[0074] (for l>0)(i=1, 2, ..., n)

[0075] (For l<0)

[0076] Thereafter, when these equations are summed for x and y, the intersection of the following two straight lines becomes the coordinates of the vertex.

[0077]

[0078]

[0079]

[0080]

[0081] Using the same method, the coordinates from vertex P1 of the corner of the reference fixture to vertices P2, P3 and P4 and the coordinates from vertex P5 to vertices P6, P7 and P8 at the first angle θ1 and the second angle θ2 can be calculated, and the calculated coordinates can be used to calculate the distances of vertices P2, P3, P4, P6, P7 and P8 from the vertices P1 and P5 of the corner of the reference fixture.

[0082] Meanwhile, the distance of the vertex calculated from the actual X-ray image may be different from the actual measured distance. Thus, there may be various factors that may cause the calculated distance of the vertex to be different from the actual measured distance, but the main factor is that when performing actual X-ray imaging, imaging is performed at a certain angle (hereinafter, referred to as the actual angle) rather than at a predetermined angle.

[0083] Even when a specific angle (eg, 30 degrees) is set in the X-ray imaging apparatus and imaging is performed, the actual imaging angle may be different from the predetermined angle. Therefore, it is necessary to verify the imaging angle of the X-ray imaging apparatus through the reference jig 300.

[0084] Therefore, when the actual imaging angle is different from the predetermined angle, the coordinates of each vertex obtained based on the predetermined angle are also different. That is, in the reference coordinates obtained according to the reference distance of the reference fixture 300, the coordinates of the first vertex may be (0, 0) and the coordinates of the second vertex may be (10, 10), but the coordinates of the first vertex according to the first distance r1 obtained by measuring the distance from the actually captured image may be (0, 0) and the coordinates of the second vertex may be (11, 12).

[0085] Thus, when the predetermined angle and the imaging angle are different, by using Fig.11 The trigonometric function shown in obtains the actual angle between the actual distance between the first vertex P1 and the second vertex P2 separated by a specific distance and the distance between the first vertex P1 and the second vertex P2 measured by X-ray imaging. For example, by performing imaging with the imaging angle set to 30 degrees, the actual imaging angle obtained by the first distance measured from the actual image may be 32 degrees.

[0086] By obtaining the coordinates of the third vertex P3 and the fourth vertex P4 from the coordinates calculated according to the above method, the distance G1 between the third vertex P3 and the fourth vertex P4 can be obtained, and thus the distance G2 between the seventh vertex and the eighth vertex can be obtained by the coordinates of the seventh vertex P7 and the eighth vertex P8. In this case, the distances G1 and G2 between the vertices are relative distances between the vertices.

[0087] Since the third vertex P3 and the seventh vertex P7 are the vertices of the negative electrode 41, and the fourth vertex P4 and the eighth vertex P8 are the vertices of the positive electrode 42, the relative position between the positive electrode and the negative electrode and the distance between the positive electrode and the negative electrode can be identified through these coordinates.

[0088] Since the negative electrode 41 and the positive electrode 42 have a substantially rectangular shape, xy coordinates can be obtained for two corners (C1, C2), and predetermined horizontal or vertical lengths of the positive and negative electrodes can be added to identify the positions of the remaining two corners (C3, C4).

[0089] Meanwhile, in the stacked electrode assembly 400, the misalignment is determined according to the relative stacking position of the positive electrode and the negative electrode. Due to the characteristics of the battery, the positive electrode should be formed smaller than the negative electrode, and the boundary line of the positive electrode should be stacked so that the boundary line does not protrude outside the negative electrode. When the boundary line (or vertex) of the positive electrode is located outside the boundary line of the negative electrode, the positive electrode and the negative electrode are misaligned and determined to be defective.

[0090] In an exemplary embodiment of the present invention, by finding the coordinates of two corners of the positive electrode and the negative electrode, the shape of the positive and negative electrode stack (ie, the relative position between the positive and negative electrodes adjacent to each other) can be easily identified.

[0091] Therefore, not only the positive electrode protruding beyond the boundary line of the negative electrode and misaligned can be determined, but also the degree of misalignment with respect to the relative distance between the positive electrode and the negative electrode can be easily recognized.

[0092] For ease of description, one positive electrode and one negative electrode have been described, but when using an X-ray imaging device according to an exemplary embodiment of the present invention, the coordinates of each vertex of all positive electrodes and negative electrodes included in the electrode assembly can be obtained by using only images imaged at different angles for each corner to determine the misalignment of each electrode.

[0093] In this way, when the positions of all positive electrodes and negative electrodes are identified, the position of the layer on which the misaligned positive electrode or negative electrode is stacked can be identified. Therefore, an electrode assembly including positive electrodes and negative electrodes that are not misaligned can be manufactured by modifying only the stacking process of the misaligned electrodes.

[0094] While the invention has been described in conjunction with what are presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the purview of the appended claims.

Claims

1. A misalignment detection system, the misalignment detection system comprising: a reference jig having a step portion which is spaced a predetermined distance from a corner of the reference jig and protrudes to an upper portion of the reference jig, the electrode assembly being disposed on the step portion; a beam generator configured to irradiate X-rays at a first angle and a second angle relative to any one corner of the electrode assembly and the reference fixture; as well as The calculation unit is configured to calculate position coordinates of a corner of the electrode assembly located at a corner of the reference jig, and determine misalignment of the positive electrode and the negative electrode of the electrode assembly based on the calculated position coordinates of the corner.

2. The misalignment detection system according to claim 1, wherein: The calculation section compensates coordinates calculated by comparing position coordinates of a corner of the step portion located at a corner of the reference jig with actually measured position values.

3. The misalignment detection system according to claim 1, wherein: The electrode assembly is a stacked electrode assembly.

4. A method for detecting misalignment of an electrode assembly by using a misalignment detection system according to any one of claims 1 to 3, the method comprising the following steps: placing the electrode assembly on the stepped portion of the reference fixture; obtaining first coordinates of a vertex of each of the positive electrode and the negative electrode located at a first corner of the reference fixture and a first corner of the electrode assembly; calculating a first distance between a vertex of each negative electrode and a vertex of each positive electrode in the electrode assembly disposed at a first coordinate; as well as The misalignment of the positive electrode and the negative electrode is determined by comparing the first distance with a reference distance.

5. The misalignment detection method according to claim 4, wherein: The steps of obtaining the first coordinates include: performing a first X-ray imaging of a first corner at a first angle; and performing a second X-ray imaging of the first corner at a second angle, The first coordinates are obtained through the first X-ray image and the second X-ray image.

6. The misalignment detection method according to claim 5, further comprising the following steps: Compensating the measured distance value and coordinates measured by obtaining a measured distance between a vertex of the reference jig at the first coordinate and a vertex of the step portion of the reference jig and an actual angle irradiated from the actual measured distance during actual imaging.

7. The misalignment detection method according to claim 6, further comprising the following steps: obtaining second coordinates of vertices located at a second corner of the reference fixture and a second corner of the electrode assembly, in, The steps of obtaining the second coordinates include: performing a third X-ray imaging of the second corner at the first angle; and A fourth X-ray imaging of the second corner is performed at a second angle.

8. The misalignment detection method according to claim 7, further comprising the following steps: Compensating the measured distance value and coordinates measured by obtaining a measured distance between a vertex of the reference jig located at the second coordinate and a vertex of the step portion of the reference jig and an actual angle irradiated from the actual measured distance during actual imaging.

Images