Electrode assembly and inspection method thereof

Abstract

The present invention relates to an electrode assembly and an inspection method thereof, whereby the folding and alignment of the electrode tabs can be accurately detected. According to one embodiment, the electrode assembly has a structure in which at least one unit cell is laminated, and the unit cell has a structure of a first electrode / separator / second electrode / separator / third electrode, wherein the first electrode and the third electrode may each include a tab protruding toward the periphery of one side, and the second electrode may include a tab protruding toward the periphery of the other side facing the one side. In addition, the first electrode tab and the third electrode tab each have: a through hole formed in a corner on one side; and an inclined section formed on the corner on the other side, thereby forming a predetermined angle relative to an imaginary extension line formed by extending the peripheries adjacent to each other on both sides in the periphery of the corresponding tab, wherein the through hole of the first electrode tab and the inclined section of the third electrode tab may be placed to overlap.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0056305, filed on May 14, 2019, and the entire contents of the Korean Patent Application are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly and an inspection method thereof, which can easily and accurately detect the folding and alignment of a tab of an electrode by naked eyes. Background Art

[0003] Electric vehicles (EV), hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (Plug-In HEV) have been proposed as solutions to the air pollution problem in diesel vehicles, and secondary batteries that can be charged and discharged are attracting attention as power sources for devices requiring high power and large capacity such as electric vehicles, hybrid electric vehicles and plug-in hybrid electric vehicles.

[0004] Generally, in terms of battery shape, there is a great demand for pouch-type secondary batteries and prismatic secondary batteries that can be applied to products with a small thickness such as mobile phones. In terms of materials, there is a great demand for lithium secondary batteries (such as lithium ion batteries and lithium ion polymer batteries) having advantages such as high energy density, discharge voltage and output stability.

[0005] This secondary battery is classified according to the structure of the electrode assembly having a structure of a positive electrode / separator / negative electrode. Representative examples thereof include: a jelly roll (wound) electrode assembly in which a long sheet-type positive electrode and a negative electrode are wound with a separator interposed therebetween; a stacked electrode assembly in which a plurality of positive electrodes and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator interposed therebetween; and a stacked / foldable electrode assembly in which a double monomer or a full monomer is wound together with a separator, in which a predetermined unit of positive and negative electrodes is stacked with a separator interposed therebetween.

[0006] The secondary battery has a structure in which an electrode assembly made of a positive electrode, a negative electrode and a separator placed therebetween and an electrolyte are stored in a battery case. Since the secondary battery is a device based on an electrochemical reaction, it is inevitably sensitive to environmental factors. In addition, since the secondary battery is manufactured by a series of processes of accurately installing and connecting small parts in a limited space, product quality may also deteriorate due to errors in some devices and incomplete work by some workers. In addition, in the manufacturing process of secondary batteries performed by a mass production system, serious defects may be caused by small defects in the process.

[0007] Therefore, after each manufacturing process step and / or after the finished product is manufactured, the secondary battery should be inspected closely. This inspection is one of the most important parts in the production process of the secondary battery, and is important in quality control to detect whether it provides the desired performance and stability. Here, quality control is used to detect whether the secondary battery has appropriate charge / discharge performance, produce qualified products, and select defective products. By performing such quality control well, high-quality secondary batteries can be produced.

[0008] Figure 1 This is an exploded perspective view schematically showing the overall structure of a conventional dual-monomer. Figure 2 It is a schematic diagram showing the stacking Figure 1 A three-dimensional diagram of the structure of the double monomer.

[0009] refer to Figure 1 , the bi-monomer has a structure in which positive electrodes 11 and 31 and a negative electrode 21 are stacked in sequence, separators 40 and 50 are placed between the positive electrode 11 and the negative electrode 21 and between the positive electrode 31 and the negative electrode 21, respectively, at the positive electrodes 11 and 31, both sides of the positive electrode collector are coated with active materials, and at the negative electrode 21, both sides of the negative electrode collector are coated with negative electrode active materials. In addition, a plurality of positive electrode tabs 12 and 32 and a negative electrode tab 22 protrude at the end of one side of each of the positive electrode collector and the negative electrode collector, respectively, at the positive electrode tab and the negative electrode tab, the positive electrode lead and the negative electrode lead constituting the electrode terminal of the battery are not coated with active materials, so as to be used for electrical connection, respectively.

[0010] The plurality of positive electrode tabs 12 and 32 and the negative electrode tab 22 are made of foil material, and may be as shown in FIG. Figure 2 Tab folding is shown to occur, and when tab folding occurs, the capacity of the secondary battery may decrease, or an internal short circuit may be caused.

[0011] In addition, in the structure in which the electrode units 10 are stacked, internal tab folding cannot be automatically checked in appearance, and internal short circuits caused by tab folding are a significant quality item that may cause stability problems, and rely on manual inspection.

[0012] In particular, as in an electrode assembly in which a double-cell structure having a positive electrode (negative electrode) / separator / negative electrode (positive electrode) / separator / positive electrode (negative electrode) is stacked in sequence and an electrode assembly in which a full-cell structure having a positive electrode (negative electrode) / separator / negative electrode (positive electrode) / separator is stacked in sequence, in an electrode unit formed by a structure in which the positive electrode and the negative electrode are stacked in multiple layers, defects in the position of the internal electrodes cannot be detected, and defects such as folding of the electrode tabs are difficult to find. Summary of the invention

[0013] Technical issues

[0014] In order to solve the problems of the prior art as described above, an object of the present invention is to provide an electrode assembly and an inspection method thereof that can easily and accurately detect folding and alignment of tabs of electrodes without disassembling a stacked electrode assembly.

[0015] Technical Solution

[0016] According to a first embodiment of the present invention, an electrode assembly has a structure in which at least one unit cell of a structure of a first electrode / separator / second electrode / separator / third electrode is stacked, wherein each of the first electrode and the third electrode includes a terminal tab protruding toward an outer periphery on one side, and the second electrode includes a terminal tab protruding toward an outer periphery on the other side facing the one side, and each of the first electrode terminal tab and the third electrode terminal tab includes: a through hole formed in an edge of one side; and an inclined portion in an edge of the other side, the inclined portion forming a predetermined angle relative to a virtual extension line extending from two outer peripheries adjacent to each other in the outer periphery of the terminal tab, and the through hole of the first electrode terminal tab and the inclined portion of the third electrode terminal tab are arranged to overlap each other.

[0017] At this time, the tab of the second electrode may be provided with through holes in an edge of the one side and an edge of the other side facing the one side, respectively.

[0018] In addition, the first electrode and the third electrode may have the same polarity, and the first electrode and the second electrode may have opposite polarities.

[0019] In addition, according to the second embodiment of the present invention, an electrode assembly has a structure in which at least one unit cell of a first electrode / separator / second electrode / separator structure is stacked, wherein the first electrode includes a terminal tab protruding toward an outer periphery of one side, and the second electrode includes a terminal tab protruding toward an outer periphery of the other side facing the one side, and each of the first electrode terminal tab and the second electrode terminal tab includes: a through hole formed in an edge of one side; and an inclined portion in an edge of the other side, the inclined portion forming an inclined portion at a predetermined angle relative to a virtual extension line extending from two outer peripheries adjacent to each other in the outer peripheries of the terminal tabs.

[0020] In addition, in the electrode assembly, two or more unit cells may be stacked, and the through hole of the first electrode tab in one unit cell and the inclined portion of the first electrode tab in an adjacent unit cell may be arranged to overlap each other, and the through hole of the second electrode tab in one unit cell and the inclined portion of the second electrode tab in an adjacent unit cell may be arranged to overlap each other.

[0021] Each of the inclined portions may be formed as a straight line forming a predetermined angle, and the predetermined angle is 10 degrees to 80 degrees.

[0022] Each of the through holes may respectively have a shape selected from the group consisting of a circle, a rectangle, and a square, and the shapes of the through holes may be the same.

[0023] In addition, a method for inspecting an electrode assembly according to a first embodiment of the present invention includes: a step of preparing an electrode assembly; a step of visually inspecting a shape of an inner surface of a through hole of a first electrode tab of the electrode assembly formed when the through hole of the first electrode tab overlaps with an inclined portion of a third electrode tab, and a step of visually inspecting a shape of an inner surface of a through hole of a third electrode tab formed when the inclined portion of the first electrode tab overlaps with the through hole of the third electrode tab; and a step of determining whether the first electrode tab or the third electrode tab is folded based on a result of the visual inspection.

[0024] In the step of determining whether the first electrode tab or the third electrode tab is folded, whether the first electrode tab or the third electrode tab is folded can be determined by determining whether the shape of the inner surface of the through hole of the first electrode tab and the shape of the inner surface of the through hole of the third electrode tab are symmetrical about the longitudinal direction of the tabs.

[0025] Furthermore, if two or more unit cells are stacked in the electrode assembly, the method may further include: a step of measuring an area of ​​an inner surface of the through hole after the visual inspection step; and a step of determining whether a position of the electrode tab is defective based on the measured area.

[0026] In the step of determining whether the position is defective, the electrodes may be arranged to allow areas of inner surfaces of the through holes to coincide with each other.

[0027] Meanwhile, a method for inspecting an electrode assembly according to a second embodiment of the present invention may include: a step of visually inspecting the shapes of inner surfaces of through holes of a plurality of electrode tabs having the same polarity; and a step of determining whether the electrode tabs are folded based on a result of the visual inspection.

[0028] In the determining whether the electrode tab is folded, whether the electrode tab is folded may be determined by determining whether shapes of inner surfaces of the two through holes are symmetrical to each other in a longitudinal direction of the tab.

[0029] Furthermore, after the visual inspection step, the method may further include: a step of measuring an area of ​​an inner surface of the through hole; and a step of determining whether the stack is defective based on the measured area.

[0030] Beneficial effects

[0031] According to an embodiment of the present invention, the electrode assembly according to the present invention has the advantage that the alignment of the electrodes and the folding of the terminal tabs can be easily and accurately detected without disassembling the stacked electrodes and separators. Therefore, during the manufacturing process of the secondary battery, the folding and alignment of the terminal tabs of the electrode assembly can be automatically checked and detected.

[0032] Thus, according to the electrode assembly and inspection method according to the present invention, although the positive electrode and the negative electrode have a multi-layer structure, the internal electrode position can still be inspected, and defects such as folding of the internal electrode tabs can be automatically inspected, thereby improving the ability to identify defective products. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is an exploded perspective view schematically showing the overall structure of a conventional dual-monomer.

[0034] Figure 2 It is a schematic diagram showing the stacking of Figure 1 A perspective view of the structure of the dual monomer is shown.

[0035] Figure 3 FIG. 1 is an exploded perspective view schematically showing an electrode assembly according to an embodiment of the present invention.

[0036] Figure 4 It is shown Figure 3 A plan view of a first electrode, a second electrode and a third electrode.

[0037] Figure 5 It is shown that there are Figure 3 A plan view of the structure of the electrode assembly is shown.

[0038] Figure 6 yes Figure 5 An enlarged plan view of a portion of the.

[0039] Figure 7 It is a plan view schematically showing various shapes in which a through hole and an inclined portion of an electrode terminal tab overlap.

[0040] Figure 8 and 9 is a perspective view showing an electrode assembly in which two unit cells are stacked.

[0041] Fig.10 FIG. 4 is an exploded perspective view schematically showing an electrode assembly according to another embodiment of the present invention.

[0042] Fig.11 is a perspective view illustrating an electrode assembly in which two unit cells are stacked according to another embodiment of the present invention.

[0043] Fig.12 It is shown Fig.11 A plan view of a structure in which electrode assemblies are stacked.

[0044] Fig.13 yes Fig.12 An enlarged plan view of portion A of FIG.

[0045] Fig.14 yes Fig.12 An enlarged plan view of portion B. DETAILED DESCRIPTION

[0046] Since the present invention allows various changes and many embodiments, specific embodiments will be shown in the drawings and described in detail in the text. However, this is not intended to limit the invention to the specific form disclosed, and should be understood to include all changes, equivalents and alternatives included in the spirit and scope of the invention.

[0047] When describing the accompanying drawings, similar reference numerals are used for similar elements. In the accompanying drawings, the size of the structure is shown in an enlarged scale for the sake of clarity of the present invention. Terms such as "first" and "second" can be used to describe various components, but these components should not be limited by these terms. These terms are only used for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. Unless the context clearly indicates otherwise, a singular expression includes a plural expression.

[0048] In this application, it should be understood that terms such as "including" or "having" are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and they do not preclude the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts, or combinations thereof. Moreover, when a part such as a layer, film, region, plate, etc. is referred to as being "on" another part, this includes not only the case where the part is "directly" "on" another part, but also the case where another other part is interposed therebetween. On the other hand, when a part such as a layer, film, region, plate, etc. is referred to as being "under" another part, this includes not only the case where the part is "directly" "under" another part, but also the case where another other part is interposed therebetween. In addition, in this application, "placed thereon" may include the case where it is placed at the bottom as well as at the top.

[0049] Hereinafter, an electrode assembly according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0050] Figure 3 is an exploded perspective view schematically showing an electrode assembly according to an embodiment of the present invention, Figure 4 It is shown Figure 3 A plan view of a first electrode, a second electrode and a third electrode.

[0051] like Figure 3 and Figure 4 As shown in , the surface on which the electrodes and separators are stacked is parallel to the surface defined by the first direction DR1 and the second direction DR2. The normal direction of the surface on which the electrodes and separators are stacked is indicated by the third direction DR3. The third direction DR3 indicates the thickness direction of the electrode assembly 1000. The front surface and the rear surface of each electrode and separator are separated in the third direction DR3. However, the directions indicated by the directions DR1, DR3 and DR3 are relative concepts and can be converted into other directions.

[0052] like Figure 3 As shown, the electrode assembly 1000 of the present invention may have a structure in which at least one unit cell of a dual cell structure is stacked, wherein the first electrode 100, the separator 400, the second electrode 200, the separator 500, and the third electrode 300 are sequentially stacked.

[0053] In the present invention, the dimonomer is a concept including A-type dimonomer and C-type dimonomer. A-type dimonomer means a dimonomer having a positive electrode / separator / negative electrode / separator / positive electrode structure, and C-type dimonomer means a dimonomer having a negative electrode / separator / positive electrode / separator / negative electrode structure. In addition, the positive electrode and the negative electrode should be understood as a concept including a double-sided positive electrode coated with a positive electrode active material on both sides of the current collector and a double-sided negative electrode coated with a negative electrode active material on both sides of the current collector.

[0054] refer to Figure 3 and Figure 4 The first electrode 100 is coated with active materials 121 and 122 on both sides of a first electrode current collector 110 to form a first active material layer 120 , and includes a first electrode tab 130 protruding toward the periphery of one side in the first direction DR1 .

[0055] The first electrode tab 130 may be provided with a through hole 131 formed at one edge in the second direction DR2 and an inclined portion 132 at another edge in the second direction DR2. Figure 4 As shown, the inclined portion 132 may have a structure in which the inclined portion 132 forms a predetermined angle (a, b) with respect to virtual extension lines 133 and 134 extending from two outer peripheries adjacent to each other among the outer peripheries of the first electrode tab 130. In addition, the inclined portion 132 is in a straight line shape to form the predetermined angle (a, b), and the predetermined angle may be 10 to 80 degrees.

[0056] The second electrode 200 may have a second active material layer generated by active materials 221 and 222 applied to both surfaces of the second electrode current collector 210, and a second electrode tab 230 protruding toward the other outer periphery in the first direction DR1. In this case, the second electrode tab 230 may be provided with a pair of through holes 231 and 232 formed at both edges in the second direction DR2.

[0057] The third electrode 300 may have a third active material layer generated by active materials 321 and 322 applied to both surfaces of a third electrode current collector 310 , and have a third electrode tab 330 protruding toward one outer periphery in the first direction DR1 .

[0058] As in the first electrode tab, the third electrode tab 330 may have a through hole 331 formed at one edge in the second direction DR2 and an inclined portion 332 at the other edge in the second direction DR2. Figure 4As shown, the inclined portion 332 may have a structure in which the inclined portion 332 forms a predetermined angle (c, d) with respect to virtual extension lines 333 and 334 extending from two outer peripheries adjacent to each other among the outer peripheries of the third electrode tab 330. In addition, the inclined portion 332 is in a straight line shape and forms a predetermined angle (c, d) with respect to the outer periphery of the third electrode tab 330, and the predetermined angle may be 10 degrees to 80 degrees.

[0059] Meanwhile, the first electrode 100 and the third electrode 300 have the same polarity, and the first electrode 100 and the second electrode 200 have opposite polarities.

[0060] In addition, the through holes 131 , 231 , 232 , and 331 formed in the first to third electrode tabs 130 to 330 may each have a shape selected from a circle, a rectangle, and a square, and the shapes of the through holes 131 , 231 , 232 , and 331 may be the same.

[0061] In addition, if Figure 3 and Figure 4 As shown, the first electrode tab 130 and the third electrode tab 330 are formed as a structure protruding in the same direction based on the first direction DR1, and the second electrode tab 230 may have a structure protruding in the opposite direction to the first electrode tab 130 and the third electrode tab 330 based on the first direction DR1.

[0062] Figure 5 It is shown that there are Figure 3 A plan view of the structure of the electrode assembly, and Figure 6 yes Figure 5 An enlarged plan view of a portion of the.

[0063] like Figure 5 and Figure 6 As shown in , the through hole 131 of the first electrode tab 130 may be positioned to overlap the inclined portion 332 of the third electrode tab 330 , and the inclined portion 132 of the first electrode tab 130 may be positioned to overlap the through hole 331 of the third electrode tab 330 .

[0064] As described above, when the through hole 131 of the first electrode tab 130 overlaps with the inclined portion 332 of the third electrode tab 330, the shape of the inner surface of the through hole 131 of the first electrode tab 130 is formed in a semicircular shape. In addition, when the inclined portion 132 of the first electrode tab 130 overlaps with the through hole 331 of the third electrode tab 330, the shape of the inner surface of the through hole 331 of the third electrode tab 330 is formed in a semicircular shape.

[0065] At this time, the shapes of the inner surfaces of the through holes 131 of the first electrode tab 130 and the through holes 331 of the third electrode tab 330 are symmetrical about the first direction DR1. In this case, it can be confirmed that the first electrode tab 130 or the third electrode tab 330 is not folded.

[0066] Therefore, whether the electrode tabs 130 and 330 are folded can be detected by the overlapping shapes of the through holes 131 and 331 and the inclined portions 132 and 332 .

[0067] On the other hand, reference Figure 7 (a) and Figure 7 (b), it can be seen that the inner surface shapes of the through hole of the first electrode tab 130 and the through hole of the third electrode tab 330 are asymmetric based on the first direction DR1, thereby confirming that the first electrode tab 130 is folded.

[0068] In addition, reference Figure 7 (c) and Figure 7 (d) It can be seen that the inner surface shapes of the through hole of the first electrode tab 130 and the through hole of the third electrode tab 330 are asymmetric based on the first direction DR1, thereby confirming that the third electrode tab 330 is folded.

[0069] In addition, refer to Figure 7 (e) An outer periphery of the first electrode tab 130 parallel to the second direction DR2 and an outer periphery of the third electrode tab 330 parallel to the second direction DR2 are shifted from each other in the first direction DR1.

[0070] Hereinafter, a method of inspecting an electrode assembly 1000 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0071] The inspection method of the electrode assembly 1000 may include: preparing the above-mentioned electrode assembly 1000; visually inspecting the shape of the inner surface of the through hole 131 of the first electrode tab 130 formed when the through hole 131 of the first electrode tab 130 of the electrode assembly 1000 overlaps with the inclined portion 332 of the third electrode tab 330 and the shape of the inner surface of the through hole 331 of the third electrode tab 330 using the naked eye; and based on the result of the visual inspection, detecting whether the first electrode tab 130 or the third electrode tab 330 is folded.

[0072] Specifically, the visual inspection may include visually inspecting inner surface shapes of the through holes 131 and 331 of the first and third electrode tabs 130 and 330 from the front based on the third direction DR3 of the first electrode 100 of the electrode assembly 1000 .

[0073] In addition, in the step of detecting whether the first electrode tab 130 or the third electrode tab 330 is folded, it is possible to detect whether the tabs are folded by detecting whether the shape of the inner surface of the through hole 131 of the first electrode tab 130 and the shape of the inner surface of the through hole 331 of the third electrode tab 330 are symmetrical based on the first direction (DR1) which is the longitudinal direction of the tabs.

[0074] At this time, if Figure 6 As shown, when the shape of the inner surface of the through hole 131 of the first electrode tab 130 and the shape of the inner surface of the through hole 331 of the third electrode tab 330 are symmetrical with respect to the first direction DR1, it can be seen that the tabs are normal without any folding.

[0075] On the other hand, Figure 7 As shown in (a)-(e), when the shape of the inner surface of the through hole 131 of the first electrode terminal 130 and the shape of the inner surface of the through hole 331 of the third electrode terminal 330 are asymmetric based on the first direction DR1, it can be seen that the first electrode terminal 130 or the third electrode terminal 330 has been folded.

[0076] Figure 8 is a perspective view of an electrode assembly in which two unit cells are stacked when viewed from one side, and Fig. 9 is viewed from the opposite direction of the side Figure 8 3D diagram of an electrode assembly. Referring to these figures, unit cells having a first electrode / separator / second electrode / separator / third electrode structure are sequentially stacked in the upper portion, and unit cells having a fourth electrode / separator / fifth electrode / separator / sixth electrode structure are sequentially stacked in the lower portion. At this time, the polarity of the first electrode, the third electrode, and the fifth electrode are the same, and the polarity of the second electrode, the fourth electrode, and the sixth electrode are the same.

[0077] refer to Figure 8 , the first electrode tab 130, the third electrode tab 330, and the fifth electrode tab 230' having the same polarity protrude in the same direction. The first electrode tab 130 and the third electrode tab 330 are provided with inclined portions and through holes 131 and 331, respectively, the through holes of the first electrode tab and the inclined portions of the third electrode tab are arranged to overlap each other, and the inclined portions of the first electrode tab and the through holes of the third electrode tab are arranged to overlap each other. In addition, the fifth electrode tab 230' has through holes 231' and 232' at one edge and the other edge facing the one side, respectively.

[0078] refer to Fig. 9, the second electrode tab 230, the fourth electrode tab 130' and the sixth electrode tab 330' having the same polarity protrude in the same direction, and the protruding direction is opposite to the protruding direction of the first electrode tab, the third electrode tab and the fifth electrode tab having opposite polarities to these electrode tabs. The second electrode tab 230 is provided with through holes 231 and 232 at one edge and the other edge facing the one side, respectively. The fourth electrode tab 130' and the sixth electrode tab 330' are provided with inclined portions and through holes 131' and 331', respectively. The through hole 131' of the fourth electrode tab 130' and the inclined portion of the sixth electrode tab 330' are placed to overlap each other, and the inclined portion of the fourth electrode tab 130' and the through hole 331' of the sixth electrode tab are placed to overlap each other.

[0079] At the same time, if Figure 8 and Fig. 9 As shown, in the case of a stacked electrode assembly having two or more stacked unit cells, after the visual inspection step, it may further include a step of measuring the area of ​​the inner surface of the through holes 131 and 331 of the electrode tabs and a step of detecting whether the positions of the electrode tabs 130, 230, 330, 130', 230' and 330' are defective based on the measured areas.

[0080] In the step of measuring the area, a light-transmitting sensor may be used to measure the area of ​​the inner surface of the through holes 131 and 331, but is not limited thereto. When the through hole of one electrode tab overlaps the inclined portion of another electrode tab, the through hole becomes a semicircular shape. At this time, the area of ​​the empty space excluding the area occupied by the inclined portion is referred to as the area of ​​the inner surface. Figure 8 , when viewed from the top of the electrode assembly, based on the width direction DR2 of the electrode tab, the through hole 131 of the first electrode tab is observed on the left side, and the through hole of the second electrode tab is observed on the right side. The through hole 131 of the first electrode tab 130 overlaps with the inclined portion of the adjacent third electrode tab 330, and the area of ​​the inner surface of the through hole 131 is reduced as much as the overlapping portion. At this time, the area of ​​the inner surface of the through hole 131 of the first electrode tab is referred to as D1. In addition, the through hole 331 of the third electrode tab 330 overlaps with the inclined portion of the adjacent first electrode tab 130, and a blank space is formed except for the inclined portion, and the blank space is referred to as D2, which is the area of ​​the inner surface of the through hole 331 of the third electrode tab 330. If the first electrode to the sixth electrode are aligned correctly, the areas of D1 and D2 should be the same, but if the alignment is incorrect, the areas of D1 and D2 will not match. Therefore, in the present invention, by measuring the area of ​​the inner surface of the uppermost through hole, it is possible to detect whether the position of the electrode tab is defective based on the measured area.

[0081] In addition, when the left through hole 231 of the second electrode tab 230 overlaps with the inclined portion of the sixth electrode tab 330', a blank space not including the inclined portion is formed, and the area D3 as the inner surface of the blank space can be measured. In addition, when the right through hole 232 of the second electrode tab 230 overlaps with the inclined portion of the fourth electrode tab 130', a blank space not including the inclined portion is formed, and the area D4 as the inner surface of the blank space can be measured. In addition, whether the position of the electrode tab is defective can be detected according to whether D3 and D4 match.

[0082] Specifically, when light is emitted from the light transmission sensor to the front surface of the first electrode 100 of the electrode assembly 1000 in the third direction DR3, the light passing through the electrode assembly 1000 does not pass through the electrode tab, and passes through the inner surface of the through hole that does not overlap with the inclined portion. In this way, the area of ​​the inner surface of the through hole can be measured.

[0083] Here, in the step of detecting whether the positions of the electrode tabs 130, 230, 330, 130', 230', and 330' are defective based on the measured areas, it is possible to determine whether the positions of the electrodes are defective by detecting whether the inner surface areas of the through hole 131 of the first electrode tab 130 and the through hole 331 of the third electrode tab 330 measured by the light transmission sensor are consistent with each other and whether the inner surface areas of the through holes 231 and 232 of the second electrode tab are consistent with each other. That is, when the inner surfaces of the through holes are consistent with each other, it can be confirmed that the alignment of the electrodes is good. On the other hand, if the inner surfaces of the through holes are inconsistent with each other, the electrodes are misaligned, so that the first electrode to the sixth electrode can be aligned so that the areas of the inner surfaces of the through holes are consistent with each other.

[0084] As described above, the electrode assembly according to the present invention has the following advantages: it is possible to easily and accurately detect the tab folding of the electrode and the misaligned position due to the poor stacking of the unit cells without disassembling the stacked electrodes and separators. Therefore, during the manufacturing process of the secondary battery, the tab folding and alignment of the electrode assembly can be automatically checked and detected.

[0085] Hereinafter, an electrode assembly according to another embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0086] Fig.10 is an exploded perspective view schematically showing an electrode assembly according to another embodiment of the present invention, Fig.12 It is shown Fig.11 A plan view of a structure in which electrode assemblies are stacked, Fig.13 yes Fig.12 is an enlarged plan view of a portion A of Fig.14 yes Fig.12 An enlarged plan view of portion B.

[0087] like Fig.10 and Fig.11 As shown in , the surface on which the electrodes and separators are stacked is parallel to the surface defined by the first direction DR1 and the second direction DR2. The normal direction of the surface on which the electrodes and separators are stacked is indicated by the third direction DR3. The third direction DR3 indicates the thickness direction of the electrode assembly 2000. The front surface and the rear surface of each electrode and separator are separated in the third direction DR3. However, the directions indicated by the directions DR1, DR3 and DR3 are relative concepts and can be converted into other directions.

[0088] refer to Fig.10 , the electrode assembly 2000 of the present invention may be a full monomer in which the first electrode 600, the separator 410, the second electrode 700, and the separator 420 are sequentially stacked. Fig.11 In the electrode assembly of the present invention, two or more full monomers may be stacked. In this way, the electrode assembly may have a structure in which the first electrode 600, the separator 410, the second electrode 700, the separator 420, the first electrode 800, and the separator 430, the second electrode 900, and the separator 440 are sequentially stacked.

[0089] exist Fig.10 In the fully monolithic electrode assembly 2000 , the first electrode 600 may coat active materials 621 and 622 on both sides of a first electrode current collector 610 to form a first active material layer 620 , and may include a first electrode tab 630 protruding toward one outer periphery in the first direction DR1 .

[0090] The first electrode tab 630 may be provided with a through hole 631 formed at one edge in the second direction DR2 and an inclined portion 632 at the other edge in the second direction DR2. Here, the inclined portion 632 may have a structure in which the inclined portion 632 forms a predetermined angle with respect to virtual extension lines (not shown) respectively extending from two outer peripheries adjacent to each other among the outer peripheries of the first electrode tab 630. In addition, the inclined portion 632 is in a straight line shape to form a predetermined angle, and the predetermined angle may be 10 to 80 degrees.

[0091] The second electrode 700 may have a second active material layer generated by active materials 721 and 722 applied to both surfaces of the second electrode current collector 710, and a second electrode tab 730 protruding toward the other outer periphery in the first direction DR1. That is, the first electrode tab 630 and the second electrode tab 730 are structures protruding in opposite directions based on the first direction DR1.

[0092] At this time, the second electrode tab 730 may be provided with a through hole 731 formed at one edge in the second direction DR2 and an inclined portion 732 at the other edge in the second direction DR2. Here, the inclined portion 732 may have a structure in which the inclined portion 732 forms a predetermined angle with respect to virtual extension lines (not shown) respectively extending from two outer peripheries adjacent to each other among the outer peripheries of the second electrode tab 730. In addition, the inclined portion 732 is in a straight line shape to form a predetermined angle, and the predetermined angle may be 10 degrees to 80 degrees.

[0093] At the same time, by stacking two electrode assemblies 2000 having a full monomer structure, Fig.11 The electrode assembly 3000 , and the first electrode 600 and the second electrode 700 located at the top of the whole monomer are described as above.

[0094] The first electrode 800 as a full cell unit cell located at the bottom is coated with active materials 821 and 822 on both sides of a first electrode collector 810 to form a first active material layer 820 , and includes a first electrode tab 830 protruding toward an outer periphery of one side in the first direction DR1 .

[0095] The first electrode tab 830 may be provided with a through hole 831 formed at one edge in the second direction DR2 and an inclined portion 832 at the other edge in the second direction DR2. Here, the inclined portion 832 may have a structure in which the inclined portion 832 forms a predetermined angle with respect to virtual extension lines (not shown) respectively extending from two outer peripheries adjacent to each other among the outer peripheries of the first electrode tab 830. In addition, the inclined portion 832 is in a straight line shape to form a predetermined angle, and the predetermined angle may be 10 to 80 degrees.

[0096] The second electrode 900 as a full cell of a unit cell located at the bottom is coated with active materials 921 and 922 on both sides of a second electrode collector 910 to form a second active material layer 920 , and includes a second electrode tab 930 protruding toward an outer periphery of one side in the first direction DR1 .

[0097] At this time, the second electrode tab 930 may be provided with a through hole 931 formed at one edge in the second direction DR2 and an inclined portion 932 at the other edge in the second direction DR2. Here, the inclined portion 932 may have a structure in which the inclined portion 932 forms a predetermined angle with respect to virtual extension lines (not shown) respectively extending from two outer peripheries adjacent to each other among the outer peripheries of the second electrode tab 930. In addition, the inclined portion 932 is in a straight line shape to form a predetermined angle, and the predetermined angle may be 10 degrees to 80 degrees.

[0098] At the same time, the first electrode 600 has the same polarity as the first electrode 800 in the adjacent unit monomer (full monomer), the second electrode 700 has the same polarity as the second electrode 900 in the adjacent unit monomer (full monomer), and the first electrodes 600 and 800 have opposite polarities to the second electrodes 700 and 900.

[0099] In addition, the through holes 631 , 731 , 831 , and 931 formed in the first to second electrode tabs 630 to 930 may each have a shape selected from a circle, a rectangle, and a square, and the shapes of the through holes 631 , 731 , 831 , and 931 may be the same.

[0100] refer to Fig.12 , the first electrode tabs 630 and the first electrodes 830 of adjacent unit cells are formed to protrude in the same direction based on the first direction DR1, and the second electrode tabs 730 and the second electrode tabs 930 of adjacent unit cells are formed to protrude in opposite directions based on the first direction DR1.

[0101] refer to Figure 12 to Figure 14 In the electrode assembly 3000 of the present invention, the through hole 631 of the first electrode terminal tab 630 is positioned to overlap with the inclined portion 832 of the first electrode terminal tab 830 of the adjacent unit cell, and the inclined portion 632 of the first electrode terminal tab 630 is positioned to overlap with the through hole 831 of the first electrode terminal tab 830 of the adjacent unit cell.

[0102] In addition, the through hole 731 of the second electrode tab 730 protruding in the direction opposite to the first electrode tab can be positioned to overlap with the inclined portion 932 of the first electrode tab 930 of the adjacent unit cell, and the inclined portion 732 of the second electrode tab 730 can be positioned to overlap with the through hole 931 of the second electrode tab 930 of the adjacent unit cell.

[0103] As described above, when the through hole 631 of the first electrode tab 630 overlaps with the inclined portion 832 of the first electrode tab 830 of the adjacent unit cell, the shape of the inner surface of the through hole 631 of the first electrode tab 630 is formed in a semicircular shape. In addition, when the inclined portion 632 of the first electrode tab 630 overlaps with the through hole 831 of the first electrode tab 830 of the adjacent unit cell, the shape of the inner surface of the through hole 831 of the first electrode tab 830 is formed in a semicircular shape.

[0104] At this time, the shape of the inner surface of the through hole 631 of the first electrode tab 630 and the shape of the inner surface of the through hole 831 of the first electrode tab 830 of the adjacent unit cell are symmetrical about the first direction DR1. In this case, it can be confirmed that the fourth electrode tab 630 or the sixth electrode tab 630 is not folded.

[0105] The second electrode tabs 730 and 930 of the adjacent unit cells are opposite to the first electrode tabs 630 and 830 only in their directions, but the shapes in which the through holes and the inclined portions overlap are the same as described above.

[0106] Therefore, whether the electrode tabs 630 , 730 , 830 , and 930 are folded can be detected by the shape in which the through holes 631 , 731 , 831 , and 931 overlap the inclined portions 632 , 732 , 832 , and 932 .

[0107] Hereinafter, a method of inspecting the electrode assembly 3000 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0108] The method for inspecting the electrode assembly 3000 may include the following steps: preparing the electrode assembly 3000; visually inspecting the shape of the inner surface of the through hole 631 of the first electrode tab 630 formed when the through hole 631 of the first electrode tab 630 of the electrode assembly 3000 overlaps with the inclined portion 832 of the first electrode tab 830 of the adjacent unit cell; and determining whether the first electrode tab to the second electrode tab 630, 730, 830 and 930 are folded based on the result of the visual inspection.

[0109] Specifically, the step of visually inspecting with the naked eye may include visually inspecting inner surface shapes of through holes 631, 731, 831, and 931 from the first electrode tab to the second electrode tab 630, 730, 830, and 930 from the front based on the third direction DR3 of the first electrode 600 of the electrode assembly 3000.

[0110] In addition, in the step of determining whether tab folding has occurred, whether tab folding has occurred can be determined by determining whether the shape of the inner surface of the through hole 631 of the first electrode tab 630 and the shape of the inner surface of the through hole 831 of the first electrode tab 830 of the adjacent unit cell are symmetrical to each other based on the first direction DR1 as the longitudinal direction of the tab, and whether the shape of the inner surface of the through hole 731 of the second electrode tab 730 and the shape of the inner surface of the through hole 931 of the second electrode tab 930 of the adjacent unit cell are symmetrical to each other in the first direction as the longitudinal direction of the tab.

[0111] At this time, if Fig.13As shown, when the shape of the inner surface of the through hole 631 of the first electrode terminal 630 and the shape of the inner surface of the through hole 831 of the first electrode terminal 830 of the adjacent unit cell are symmetrical about the first direction DR1, it can be seen that the terminal is normal and has no folding. Fig.14 As shown, when the shape of the inner surface of the through hole 731 of the second electrode tab 730 and the shape of the inner surface of the through hole 931 of the second electrode tab 930 of the adjacent unit cell are symmetrical about the first direction DR1, it can be seen that the tabs are normal without any folding.

[0112] On the other hand, when the shape of the inner surface of the through hole 631 of the first electrode tab 630 and the shape of the inner surface of the through hole 831 of the first electrode tab 830 of the adjacent unit cell are asymmetric with respect to the first direction DR1, it can be confirmed that the first electrode tab 630 or the first electrode tab 630 of the adjacent unit cell is folded. This also applies to the shape of the inner surface of the through hole 731 of the second electrode tab 730 and the shape of the inner surface of the through hole 931 of the second electrode tab 930 of the adjacent unit cell.

[0113] In addition, after the visual inspection step, the steps may further include measuring the areas of the inner surfaces of the through holes 631, 731, 831 and 931 of the first electrode tabs 630 and 830 and the second electrode tabs 730 and 930; and determining whether the positions of the first electrode tabs 630 and 830 and the third electrode tabs 730 and 930 are defective based on the measured areas.

[0114] In the step of measuring the areas, areas of inner surfaces of the through holes 631 , 731 , 831 , and 931 of the first and second electrode tabs 630 and 830 and 730 and 930 may be measured using a light transmission sensor, but is not limited thereto.

[0115] In the step of detecting whether the position is defective, poor stacking or poor positioning of the electrodes can be detected by detecting whether the inner surface areas of the through holes 631, 731, 831 and 931 of the first electrode tabs 630 and 830 and the second electrode tabs 730 and 930 measured by the light transmittance sensor match each other.

[0116] Specifically, when the inner surface areas of through holes 631 and 831 are consistent with each other and the inner surface areas of through holes 731 and 931 are consistent with each other, it can be confirmed that the alignment of the electrodes is good. On the other hand, if the inner surfaces of the through holes are inconsistent with each other, the electrodes are misaligned, so that the electrodes can be aligned so that the areas of the inner surfaces of the through holes are consistent with each other.

[0117] As described above, the electrode assembly according to the present invention has the advantage that the alignment of the electrodes and the folding of the tabs can be easily and accurately detected without disassembling the stacked electrodes and separators. Therefore, during the manufacturing process of the secondary battery, the tab folding and alignment of the electrode assembly can be automatically checked and detected.

[0118] Thus, according to the electrode assembly and inspection method according to the present invention, although the positive electrode and the negative electrode have a multi-layer structure, it is still possible to inspect the internal electrode position and automatically inspect defects such as folding of the internal electrode tabs, thereby improving the ability to identify defective products.

[0119] Although the present invention has been described above with reference to the preferred embodiments, it will be appreciated that those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the invention as set forth in the appended claims.

[0120] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims

1. An electrode assembly having a structure in which at least one unit cell having a structure of a first electrode / separator / second electrode / separator / third electrode is stacked, a surface on which the first electrode / separator / second electrode / separator / third electrode is stacked is parallel to a surface defined by a first direction and a second direction, in, Each of the first electrode and the third electrode includes a tab protruding toward an outer periphery on one side in the first direction, and the second electrode includes a tab protruding toward an outer periphery on another side opposite to the one side in the first direction, Wherein, each of the terminal tab of the first electrode and the terminal tab of the third electrode comprises: a through hole formed in one edge of the wiring sheet located in the second direction; and an inclined portion located in the other edge of the terminal piece in the second direction, the inclined portion forming a predetermined angle with respect to a virtual extension line extending from two outer peripheries adjacent to each other among the outer peripheries of the terminal piece, and Wherein, the through hole of the terminal tab of the first electrode and the inclined portion of the terminal tab of the third electrode are arranged to overlap each other, so that the shape of the inner surface of the through hole of the terminal tab of the first electrode and the shape of the inner surface of the through hole of the terminal tab of the third electrode are symmetrical about the first direction.

2. The electrode assembly according to claim 1, wherein: Through holes are respectively provided in one edge of the tab of the second electrode in the second direction and another edge opposite to the one edge.

3. The electrode assembly according to claim 1, wherein: The first electrode and the third electrode have the same polarity, and the first electrode and the second electrode have opposite polarities.

4. The electrode assembly according to claim 1, wherein: Each of the inclined portions is formed as a straight line forming the predetermined angle, and the predetermined angle is 10 degrees to 80 degrees.

5. The electrode assembly according to claim 1, wherein: Each of the through holes has a shape selected from a circle, a rectangle and a square, and the shapes of the through holes are the same.

6. An electrode assembly, the electrode assembly having a structure: wherein: Two or more unit cells having a structure of a first electrode / separator / second electrode / separator are stacked, and a surface on which the first electrode / separator / second electrode / separator is stacked is parallel to a surface defined by a first direction and a second direction, wherein the first electrode includes a tab protruding from an outer periphery on one side of the first direction, and the second electrode includes a tab protruding from an outer periphery on another side opposite to the one side of the first direction, and Wherein, each of the terminal tab of the first electrode and the terminal tab of the second electrode comprises: a through hole formed in one edge of the wiring sheet located in the second direction; and an inclined portion located in the other edge of the connecting piece located in the second direction, the inclined portion forming a predetermined angle with respect to a virtual extension line extending from two outer peripheries adjacent to each other among the outer peripheries of the connecting piece, wherein the through hole of the terminal tab of the first electrode in one unit cell and the inclined portion of the terminal tab of the first electrode in an adjacent unit cell are arranged to overlap each other, so that the shape of the inner surface of the through hole of the terminal tab of the first electrode in the one unit cell and the shape of the inner surface of the through hole of the terminal tab of the first electrode in the adjacent unit cell are symmetrical about the first direction, and In which, the through hole of the terminal tab of the second electrode in one unit cell and the inclined portion of the terminal tab of the second electrode in an adjacent unit cell are arranged to overlap each other, so that the shape of the inner surface of the through hole of the terminal tab of the second electrode in the one unit cell and the shape of the inner surface of the through hole of the terminal tab of the second electrode in the adjacent unit cell are symmetrical about the first direction.

7. The electrode assembly according to claim 6, wherein: Each of the inclined portions is formed as a straight line forming the predetermined angle, and the predetermined angle is 10 degrees to 80 degrees.

8. The electrode assembly according to claim 6, wherein: Each of the through holes has a shape selected from a circle, a rectangle and a square, and the shapes of the through holes are the same.

9. A method for inspecting an electrode assembly, the method comprising the steps of: Prepare an electrode assembly according to any one of claims 1 to 5; visually inspecting a shape of an inner surface of the through hole of the first electrode tab of the electrode assembly formed when the through hole of the first electrode tab overlaps with the inclined portion of the third electrode tab and a shape of an inner surface of the through hole of the third electrode tab formed when the inclined portion of the first electrode tab overlaps with the through hole of the third electrode tab; as well as Determine whether the terminal tab of the first electrode or the terminal tab of the third electrode is folded based on the result of the visual inspection, wherein, in the step of determining whether the terminal tab of the first electrode or the terminal tab of the third electrode is folded, determine whether the terminal tab of the first electrode or the terminal tab of the third electrode is folded by determining whether the shape of the inner surface of the through hole of the terminal tab of the first electrode and the shape of the inner surface of the through hole of the terminal tab of the third electrode are symmetrical about the longitudinal direction of the terminal tab.

10. The method according to claim 9, wherein: If two or more unit cells are stacked in the electrode assembly, the following steps are further included: After the visual inspection step, measuring the area of ​​the inner surface of the through hole; and Whether a position of the electrode tab is defective is determined based on the measured area.

11. The method according to claim 10, wherein: In the step of determining whether the position is defective, the electrodes are arranged to allow areas of the inner surfaces of the through holes to coincide with each other.

12. A method for inspecting an electrode assembly, the method comprising the steps of: Prepare an electrode assembly according to any one of claims 1 to 8; visually inspecting the shapes of inner surfaces of through holes of tabs having a plurality of electrodes of the same polarity; and Determining whether the electrode tab is folded according to the result of the visual inspection, wherein: In the step of determining whether the tab of the electrode is folded, whether the tab of the electrode is folded is determined by determining whether shapes of the inner surfaces of two through holes are symmetrical to each other in a longitudinal direction of the tab.

13. The method according to claim 12, further comprising the steps of: measuring the area of ​​the inner surface of the through hole; and Whether the stack is defective is determined based on the measured area.

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