Apparatus and method for inspecting electrode stack in secondary battery

Abstract

The present invention relates to an apparatus for inspecting a stack of an electrode of a secondary battery, the apparatus comprising: a stacking table on which a stack including a plurality of positive and negative electrodes and a separator disposed between the positive and negative electrodes is placed; a fixing portion configured to fix one surface of the stacked body and including at least one hole for exposing the stacked body; and an imaging unit configured to photograph the stacked body exposed through the hole.

Description

Technical Field

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2022-0184173 filed in the Korean Intellectual Property Office on December 26, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an apparatus and method for inspecting a stack of electrodes of a secondary battery. Background Art

[0003] Generally, a secondary battery refers to a chargeable and dischargeable battery, unlike a non-rechargeable primary battery, and is widely used in the field of high-tech electronic devices such as phones, laptops, and camcorders.

[0004] The stability of the secondary battery may be ensured through a stability test in which one surface is compressed with a press to measure an internal short circuit.

[0005] According to the shape of a battery case, secondary batteries are classified into cylindrical batteries and prismatic batteries in which an electrode assembly is built in a cylindrical or prismatic metal battery case, and pouch-type batteries in which an electrode assembly is built in a pouch-type battery case made of an aluminum stacked sheet.

[0006] Pouch-type batteries are manufactured by heating and pressing a stack of a positive electrode, a separator, and a negative electrode to adhere the positive electrode and the negative electrode to the separator. A problem with pouch-type batteries is that when the stack is pressed, the stack is deformed or misaligned because it is not fixed, so after pressing the stack, the quality of the electrode assembly is checked to verify whether the electrodes are stacked and aligned in a normal order.

[0007] However, according to the quality inspection of the pouch type battery in the related art, the quality of the electrode assembly is inspected after the manufacturing of the electrode assembly is completed. Therefore, if there is a defect in the alignment or sequence of the electrodes, the electrode assembly is discarded, resulting in great economic losses.

[0008] Furthermore, a problem with quality inspection of pouch type batteries in the related art is that it is impossible to detect defects such as electrode plate misalignment and stack warping during the stacking process of electrodes. Summary of the invention

[0009] Technical issues

[0010] The present invention is made in an effort to solve the above-mentioned problems in the related art, and provides an apparatus and method for inspecting a stack of electrodes of a secondary battery for inspecting alignment of electrodes and warping of separators and electrodes during an electrode assembly manufacturing process.

[0011] Technical Solution

[0012] An exemplary embodiment of the present invention provides an apparatus for inspecting a stack of electrodes of a secondary battery, the apparatus comprising: a stacking table on which a stack including a plurality of positive electrodes and negative electrodes and a separator arranged between the positive electrodes and the negative electrodes is placed; a fixing portion configured to fix one surface of the stack and including at least one hole for exposing the stack; and an imaging unit configured to photograph the stack exposed through the hole.

[0013] Another exemplary embodiment of the present invention provides a method for inspecting the stacking of electrodes of a secondary battery, the method comprising: manufacturing a stack by supplying a plurality of positive electrodes and negative electrodes to a stacking table and supplying a separator between the positive electrodes and the negative electrodes; fixing the stack in a stacking direction using a fixing portion including at least one hole for exposing the stack; and photographing the stack exposed through the hole.

[0014] Beneficial Effects

[0015] In the apparatus and method for inspecting the stack of electrodes of a secondary battery according to an exemplary embodiment of the present invention, when inspecting the alignment of the electrodes, the fixing part having a hole for exposing the end of the electrode assembly fixes the electrode assembly. As a result, the warping of the separator and the electrode can be minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 : is a plan view showing a plane on which a fixing part according to an exemplary embodiment of the present invention fixes a stacked body.

[0017] Figure 2 is along Figure 1 A cross-sectional view taken along line AA'.

[0018] Figure 3 is a plan view showing a fixing portion according to an exemplary embodiment of the present invention.

[0019] Figure 4 is a cross-sectional view illustrating an electrode assembly manufacturing apparatus according to an exemplary embodiment of the present invention.

[0020] Figure 5 is a perspective view illustrating a diaphragm supply unit according to an exemplary embodiment of the present invention.

[0021] Figure 6 The nth electrode of each electrode in the stack measured in the comparative example is shown. x The distance is the same as the actual nth measured on the cut cross section of the stack x Fitted line plot of distance.

[0022] Figure 7The nth electrode of each stack measured in the embodiment is shown. x The distance is the same as the actual nth measured on the cut cross section of the stack x Fitted line plot of distance.

[0023] Figure 8 The nth electrode of each stack measured in the embodiment is shown. y The distance and the nth distance actually measured on the cut cross section of the stack y Fitted line plot of distance.

[0024] [Explanation of Reference Numbers]

[0025] 100: Equipment for inspecting stacking of electrodes of secondary batteries

[0026] 200: Electrode assembly manufacturing equipment

[0027] 10: Stacking table

[0028] 20: Fixed part

[0029] 21: First hole

[0030] 22: Second hole

[0031] 30: Imaging unit

[0032] 40: Determine the unit

[0033] 50: Diaphragm supply unit

[0034] 51: Diaphragm heating unit

[0035] 52: Diaphragm roller

[0036] 61: First electrode placement station

[0037] 62: First suction head

[0038] 63: First electrode roll

[0039] 64: First Cutter

[0040] 65: First conveyor belt

[0041] 66: First electrode supply head

[0042] 67: First Mobile Unit

[0043] 71: Second electrode placement platform

[0044] 72: Second suction head

[0045] 73: Second electrode roll

[0046] 74: Second Cutter

[0047] 75: Second conveyor belt

[0048] 76: Second electrode supply head

[0049] 77: Second mobile unit

[0050] 1: First electrode

[0051] 2: Second electrode

[0052] 4: Diaphragm

[0053] S: stack

[0054] s1: first end

[0055] s2: Second end

[0056] s3: The third end

[0057] s4: fourth end. DETAILED DESCRIPTION

[0058] The detailed description of the present invention is intended to fully explain the present invention to those skilled in the art. Throughout the application, unless explicitly described to the contrary, when a component "includes (comprising)" another component or "is characterized by" having a certain structure and a certain shape, this means that other components, structures and shapes may be included, but not excluded.

[0059] The present invention can be variously modified and can have various exemplary embodiments, and specific embodiments will be described in detail in the detailed description. However, the description of the embodiments is not intended to limit the content of the present invention, but it should be understood that the present invention will cover all modifications, equivalents and substitutions that fall within the spirit and scope of the present invention.

[0060] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, it should be noted that the accompanying drawings are provided for illustrating the present invention, and the scope of the present invention is not limited by the accompanying drawings.

[0061] Figure 1 is a plan view showing a plane on which the fixing part 20 according to the exemplary embodiment of the present invention fixes the stacked body, Figure 2 is along Figure 1 A cross-sectional view taken along line A-A' of Figure 3 is a plan view showing the fixing part 20 according to the exemplary embodiment of the present invention.

[0062] An apparatus 100 for inspecting a stack of electrodes of a secondary battery according to an exemplary embodiment of the present invention includes a stacking stage 10 , a fixing portion 20 , and an imaging unit 30 .

[0063] On the stacking station 10, the positive electrode, the negative electrode and the separator are supplied and stacked, and the stack is manufactured and placed. For example, a stack in which a plurality of positive electrodes and negative electrodes are stacked on a zigzag separator is placed. Here, the stack S refers to a stack in which the separator, the positive electrode and the negative electrode are simply stacked, and the electrode assembly refers to an electrode assembly in which the separator is attached to or adhered to the positive electrode and the negative electrode by heating and pressing the stack S.

[0064] In addition, the stacked body S of the present invention refers to a stacked body before the separator is attached to the positive electrode and the negative electrode, and the number of stacked positive electrodes and negative electrodes may vary.

[0065] The electrode assembly is a power generating element that includes a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode and can be charged and discharged.

[0066] The electrode assembly may include a stack-folded structure in which a negative electrode and a positive electrode are sequentially stacked between folds of a separator supplied in a zigzag shape.

[0067] The positive electrode may include a positive electrode collector, a positive electrode active material portion, and a positive electrode non-coating portion. The positive electrode collector is a metal thin plate having excellent conductivity and may include, for example, aluminum (Al) foil.

[0068] The positive electrode is coated with a positive electrode active material on one or more of the two surfaces of the positive electrode current collector. The area coated with the positive electrode active material is the positive electrode active material portion, and the area not coated with the positive electrode active material is the positive electrode uncoated portion. Since the positive electrode uncoated portion is not coated with the positive electrode active material layer, the first electrode tab can be bonded to the positive electrode uncoated portion.

[0069] The positive electrode active material may include lithium cobalt oxide having a high operating voltage and excellent capacity characteristics, lithium nickel oxide having a high reversible capacity and being used to easily realize a large-capacity battery, lithium nickel cobalt oxide in which a portion of the nickel is replaced by cobalt, lithium nickel cobalt metal oxide in which a portion of the nickel is replaced by manganese, cobalt or aluminum, lithium manganese-based oxide having excellent thermal stability and low cost, lithium iron phosphate having excellent stability, and the like.

[0070] The negative electrode may include a negative electrode current collector, a negative electrode active material portion, and a negative electrode non-coating portion. The negative electrode current collector may include a metal thin plate having excellent electrical conductivity, for example, copper (Cu) or nickel (Ni) foil.

[0071] The negative electrode is coated with a negative electrode active material on one surface or both surfaces of the negative electrode current collector. The negative electrode active material portion is formed by coating or applying the negative electrode active material, and the negative electrode uncoated portion is a region where the negative electrode active material is not coated or applied and the negative electrode current collector is exposed. Since the negative electrode uncoated portion is not coated with the negative electrode active material, the second electrode sheet can be joined to the negative electrode uncoated portion.

[0072] The negative electrode active material may be, for example, a carbon material such as crystalline carbon, amorphous carbon, carbon composite or carbon fiber, lithium metal, lithium alloy, etc. In this case, the negative electrode active material may further include, for example, non-graphite SiO (silica, silicon dioxide), SiC (silicon carbide, silicon carbide), etc. for high capacity design.

[0073] The first electrode tab and the second electrode tab are used to transfer electrons collected in the current collector to an external circuit, and may protrude in opposite directions with reference to the electrode assembly of the jelly-roll structure.

[0074] The separator prevents an internal short circuit that may occur when the positive electrode and the negative electrode contact each other, and may include a porous material to facilitate migration of ions between the electrodes.

[0075] In an exemplary embodiment, the separator may include a substrate layer made of a porous material. The substrate layer may include, for example, any one selected from the group consisting of polyethylene (PE), polystyrene (PS), polypropylene (PP), and a copolymer of polyethylene (PE) and polypropylene (PP).

[0076] In another exemplary embodiment, the separator may include a safety reinforced separator (SRS). That is, the separator may include a substrate layer made of a porous material, and a coating layer coated and formed on the substrate layer by applying a mixed slurry of inorganic particles and a binder polymer. Preferably, in addition to the porous structure of the separator substrate itself, the coating layer also includes ceramic particles and has a uniform porous structure formed by the interstitial volume between the ceramic particles as components of the active layer.

[0077] The coating layer may include ceramic particles selected from the group consisting of alumina, silica, TiO 2 , SiC and MgAl 2 O 4 At least one of the group consisting of. The coating layer is included so that the safety of the electrode assembly can be enhanced. The coating layer may further include a lithium salt.

[0078] The apparatus 100 for inspecting a stack of electrodes of a secondary battery according to an exemplary embodiment of the present invention may be included in an electrode assembly manufacturing apparatus. Figure 42 is a cross-sectional view showing an electrode assembly manufacturing apparatus 200 according to an exemplary embodiment of the present invention. The electrode assembly manufacturing apparatus 200 includes a stacking station 10, a diaphragm supply unit 50, a first electrode supply unit, a second electrode supply unit, and a pressing unit (not shown). Therefore, the stacking station 10 of the apparatus 100 for inspecting the stacking of electrodes of a secondary battery may be the same as the stacking station 10 of the electrode assembly manufacturing apparatus.

[0079] The stacking stage 10 is a stacking stage on which the first electrode 1, the separator 4, and the second electrode 2 are alternately stacked on one side, the stacked stack S is placed on one side, the separator 4 is folded into a Z shape, and the first electrode 1, the separator 4, and the second electrode 2 can be stacked so that the first electrode 1 and the second electrode 2 are alternately arranged between the folds of the separator 4. Here, the first electrode 1 and the second electrode 2 may include a positive electrode and a negative electrode. For example, when the first electrode 1 is a positive electrode, the second electrode 2 may be a negative electrode, and when the first electrode 1 is a negative electrode, the second electrode 2 may be a positive electrode.

[0080] On the stacking stage 10, the first electrode 1 and the second electrode 2 supplied to the stacking stage 10 by rotation may be stacked. Therefore, the electrode assembly manufacturing apparatus 200 according to the exemplary embodiment of the present invention may further include a rotating unit (not shown) for rotating the stacking stage 10.

[0081] In the electrode assembly manufacturing apparatus 200 according to an exemplary embodiment of the present invention, the first electrode supply unit may be located on one side of the stacking stage 10, and the second electrode supply unit may be located on the other side. In this case, the rotating unit may rotate the stacking stage 10 alternately in the direction of the first electrode supply unit and the direction of the second electrode supply unit.

[0082] For example, the membrane supply unit 50 may be located above the stacking stage 10 , ie, in the stacking direction of the stack body S, and based on the stacking direction of the stack body S, the first electrode supply unit is located on the left and the second electrode supply unit may be located on the right.

[0083] When the diaphragm 4 is supplied and placed on the stacking stage 10, and the rotating unit rotates the stacking stage to the left, the first electrode may be supplied to one surface of the diaphragm 4. The rotating unit may rotate the stacking stage 10 to the right as the diaphragm 4 is supplied. In this case, the diaphragm 4 may cover the lower surface, the right surface, and the upper surface of the first electrode 1, and the second electrode 2 may be supplied to the upper surface of the first electrode 1 where the diaphragm 4 is located.

[0084] By repeating the above process, the diaphragm 4 can be arranged in a form in which the left side and the right side are alternately opened to each layer.

[0085] Figure 5is a perspective view showing a diaphragm supply unit 50 according to an exemplary embodiment of the present invention. The diaphragm supply unit 50 may include a diaphragm heating unit 51 that forms a passage through which the diaphragm 4 passes and heats the diaphragm 4 passing therethrough.

[0086] The diaphragm heating unit 51 may include a pair of bodies (not shown) and a diaphragm heater (not shown) that heats the bodies. The pair of bodies may be arranged to be spaced a certain distance from each other so that the diaphragm 4 can pass therethrough. Here, the diaphragm 4 may pass through the diaphragm heating unit 71 in a non-contact manner, for example, so that the diaphragm 4 can be heated in a non-contact manner. Note that the body may be formed in the shape of, for example, a square block.

[0087] Note that the membrane supply unit 50 may further include a membrane roller 52 on which the membrane 4 is wound. Here, the membrane 4 wound on the membrane roller 52 may be supplied to the stacking stage 10 while being gradually unwound and passing through the membrane heating unit 51.

[0088] For example, the membrane supply unit 50 may be located above the stacking station 10. The membrane supply unit 50 may further include a membrane roller 52 on which the membrane 4 is wound. Here, the membrane 4 wound on the membrane roller 52 may be supplied to the stacking station 10 by gravity while being gradually unwound and passing through the membrane heating unit 51.

[0089] The first electrode supply unit may supply the first electrode 1 to the stacking stage 10 and stack the first electrode 1 on the stacking stage 10 .

[0090] The first electrode supply unit may include a first electrode placement stage 61 on which the first electrode 1 is placed before being stacked on the stacking stage 10 .

[0091] The first electrode supply unit may further include a first electrode roll 63 , a first cutter 64 , a first conveyor belt 65 , and a first electrode supply head 66 .

[0092] In the first electrode supply unit, the first electrode 1 wound on the first electrode roll 63 in the form of a sheet can be supplied to the first electrode placement stage 61 while being gradually unwound, and the first cutter 64 can cut the first electrode 1 supplied from the first electrode roll 63 into a preset length.

[0093] The first electrode 1 cut by the first cutter 64 is supplied to the first conveyor belt 65, and the first conveyor belt 65 can move the first electrode 1 to the side of the first electrode placement table 61. The first electrode supply head 66 can vacuum-absorb the first electrode 1 placed on the first conveyor belt 65 and place the first electrode 1 on the first electrode placement table 61.

[0094] Here, the first cutter 64 may cut the sheet-shaped first electrode 1 so that the first electrode tab 1 a is formed to protrude at the end.

[0095] In addition, the first electrode supply unit may include a first suction head 62 and a first moving part 67 .

[0096] The first suction head 62 may vacuum-adsorb the first electrode 1 placed on the first electrode placement stage 61. The first suction head 62 has a vacuum suction port (not shown) formed in the bottom surface, and may adsorb the first electrode 1 through the vacuum suction port to fix the first electrode 1 to the bottom surface of the first suction head 62. Here, the first suction head 62 may have a channel formed therein that connects the vacuum suction port and a vacuum suction device (not shown).

[0097] The first moving portion 67 may move the first suction head 62 to the stacking stage 10 so that the first suction head 62 may stack the first electrode 1 placed on the first electrode placement stage 61 on the stacking stage 10 .

[0098] The second electrode supply unit may supply the second electrode 2 to the stacking stage 10 and stack the second electrode 2 on the stacking stage 10 .

[0099] The second electrode supply unit may include a second electrode placement stage 71 on which the second electrode 2 is placed before being stacked on the stacking stage 10 .

[0100] The second electrode supply unit may further include: a second electrode roll 73, on which the second electrode 2 is wound in sheet form; a second cutter 74, which cuts the second electrode 2 at regular intervals to form a second electrode 2 having a predetermined size when the second electrode 2 wound in sheet form on the second electrode roll 73 is unfolded and supplied; a second conveyor belt 75, which moves the second electrode 2 cut by the second cutter 74; and a second electrode supply head 76, which vacuum-adsorbs the second electrode 12 conveyed by the second conveyor belt 75 to place it on the second electrode placement table 71.

[0101] Here, the second cutter 74 may cut the sheet-shaped second electrode 2 so that the second electrode tab 2 a is formed to protrude at the end.

[0102] In addition, the second electrode supply unit may include: a second suction head 72, which vacuum adsorbs the second electrode 2 placed on the second electrode placing table 71; and a second moving part 77, which can move the second suction head 72 to the stacking table 10, so that the second suction head 72 can stack the second electrode 2 placed on the second electrode placing table 71 on the stacking table 10.

[0103] The second suction head 72 may include a vacuum suction port (not shown) formed in a bottom surface on which the second electrode 2 is placed and configured to suck air and fix the second electrode 2 to the bottom surface of the second suction head 72 .

[0104] In this case, the rotating unit according to the exemplary embodiment of the present invention may rotate the stacking stage 10 so that the stacking stage 10 faces the first suction head 62 when stacking the first electrode 1 , and rotate the stacking stage 10 so that the stacking stage 10 faces the second suction head 72 when stacking the second electrode 2 .

[0105] The fixing part 20 fixes the stacked bodies S and includes at least one hole 21, 22 for exposing the stacked bodies S. The fixing part 20 may fix the stacked bodies S by pressing the stacked bodies S on one side in a stacking direction of the stacked bodies S.

[0106] Reference Figure 1 and Figure 3 , the fixing portion 20 may include a first hole 21 for exposing a line along which the diaphragm 4 is folded, and a second hole 22 for exposing a line orthogonal to the line along which the diaphragm 4 is folded.

[0107] The stacked body S according to the exemplary embodiment of the present invention may include two long sides, which are side surfaces or ends where the separator is folded, and two short sides, which are side surfaces or ends orthogonal to the long sides and from which the electrode tabs protrude.

[0108] In the exemplary embodiment, the diaphragm 4 or the stack S stacked on the stacking stage 10 has a first end, a second end opposite to the first end, a third end connecting the first end and the second end, and a fourth end.

[0109] The first hole 21 of the fixing part 20 may expose the first end s1 or the second end s2 as the long side of the stack S, and the second hole 22 may expose the third end s3 or the fourth end s4 as the short side of the stack S.

[0110] The fixing part 20 may be provided in plural. The fixing part 20 may extend along the length direction of the stacked body S to fix the stacked body S. In addition, two of the fixing parts 20 may be provided in pairs.

[0111] One of the pair of fixing portions 20 may extend from the third end s3 in the length direction of the stacked body S, and the other fixing portion 20 may extend from the fourth end s4 in the length direction of the stacked body S. The pair of fixing portions 20 may be spaced apart from each other.

[0112] The fixing portion 20 may include two pairs. One pair of fixing portions 20 may be disposed adjacent to the first end s1, and the other pair of fixing portions 20 may be disposed adjacent to the second end s2. Alternatively, one pair of fixing portions 20 may have one end located on the same line as the first end s1, and the other pair of fixing portions 20 may have one end located on the same line as the second end s2.

[0113] The shape of the first hole 21 is not limited as long as it can expose the line along which the diaphragm is folded, but may be, for example, a square or rectangular shape. The shape of the second hole 22 is not limited as long as it can expose a line orthogonal to the line along which the diaphragm is folded, but may be, for example, a circular shape.

[0114] The imaging unit 30 can photograph the stacked body S exposed through the holes 21 and 22, and the stacking table, and the device 100 for inspecting the stack of electrodes of a secondary battery according to an exemplary embodiment of the present invention may further include a determination unit 40, which receives data photographed by the imaging unit 30 and analyzes the positions of the positive electrode, the negative electrode and the separator 4 to determine the misalignment (miss align) of the positive electrode, the negative electrode and the separator 4.

[0115] The imaging unit 30 may photograph the first hole 21 and the second hole 22 together with the stacking stage, or photograph the first hole 21, the second hole 22 and the stacking stage together. In addition, whenever the separator 4 is stacked on one surface of each of the plurality of positive and negative electrodes, the imaging unit 30 may photograph the first hole 21 and the second hole 22 to check the alignment of the positive electrodes, negative electrodes and separators of each layer.

[0116] The determination unit 40 measures a distance between the first end s1 or the second end s2 of the diaphragm located in the first hole 21 and an end of the stacking stage 10 parallel to the first end s1 or the second end s2 .

[0117] Alternatively, the determination unit 40 measures the distance between the third end s3 or the fourth end s4 of the diaphragm located in the second hole 22 and the end of the stacking stage 10 parallel to the third end s3 or the fourth end s4.

[0118] Alternatively, the determination unit 40 measures the distance between the first end s1 or the second end s2 and an end of the stacking table 10 parallel to the first end s1 or the second end s2, and the distance between the third end s3 or the fourth end s4 and an end of the stacking table 10 parallel to the third end s3 or the fourth end s4.

[0119] In an exemplary embodiment, the apparatus 100 for inspecting a stack of electrodes of a secondary battery includes two fixing parts 20 arranged as a pair, the first pair of fixing parts 20 being arranged adjacent to the first end s1 to fix the negative electrode and the separator, and the second pair of fixing parts 20 being arranged adjacent to the second end s2 to fix the positive electrode and the separator.

[0120] After the stacking of the negative electrodes, the stacking and folding of the separators, the first pair of fixing parts 20 fixes the stacked body S, and the imaging unit 30 photographs the first hole 21 and the second hole 22 formed in the first pair of fixing parts 20. Then, the determination unit 40 receives the image photographed by the imaging unit 30, and measures the distance between the first end s1 photographed together with the first hole 21 and the end of the stacking stage parallel to the first end s1 on the photographed image. Then, the determination unit 40 measures the distance between the third end s3 photographed together with the second hole and the end of the stacked body parallel to the third end s3.

[0121] The determination unit 40 may check the alignment of the positive electrode, the negative electrode, or the separator 4 by comparing the measured distance between the separator 4 and the end of the stacking stage with a pre-stored reference value.

[0122] The distance between the first end s1 or the second end s2 exposed by the first hole 21 of the fixing portion 20 fixing the positive electrode and separator 4 or the negative electrode and separator 4 of the nth stack and the end of the stacking stage is nth x The distance between the first end s1 or the second end s2 exposed by the first hole 21 of the fixing part 20 fixing the positive electrode and the separator 4 or the negative electrode and the separator 4 of the (n+1)th stack and the end of the stacking stage is x distance.

[0123] The distance between the third end s3 or the fourth end s4 exposed by the second hole 21 of the fixing portion 20 fixing the positive electrode and the separator 4 or the negative electrode and the separator 4 of the nth stack and the end of the stacking stage is nth y The distance between the third end s3 or the fourth end s4 exposed by the second hole 21 of the fixing portion 20 fixing the positive electrode and the separator 4 or the negative electrode and the separator 4 of the (n+1)th stack and the end of the stacking stage is the (n+1)th y distance.

[0124] The determination unit 40 can be configured by x Distance, (n+1) x Distance, nth y Distance and (n+1)th y The distance is compared with a pre-stored reference value to check the alignment of the positive electrode, the negative electrode or the separator 4. Specifically, when the nth x Distance and (n+1) xThe difference between the distances or the nth y Distance and (n+1) y When the difference between the distances is equal to or less than the reference value, the determination unit 40 may determine that the alignment is normal, and when the nth x Distance and (n+1) x The difference between the distances or the nth y Distance and (n+1) y When the difference between the distances exceeds the reference value, the determination unit 40 may determine that the alignment is misaligned.

[0125] Or, when the nth x Distance and nth y When the distance is equal to or less than the pre-stored reference value, the determination unit 40 may determine that the alignment is normal, and when the nth x Distance and nth y When the distance exceeds the reference value, the determination unit 40 may determine the alignment as misalignment. That is, the pre-stored reference value may be the distance between the first end s1 or the second end s2 and the end of the stacking station, or the nth x Distance and (n+1) x The difference between the distances or the nth y Distance and (n+1) y The error value of the normal range of the difference between the distances.

[0126] In the exemplary embodiment, when the reference value is the distance between the end of the positive electrode, the negative electrode, or the separator 4 and the end of the stacking stage, the nth x The reference value of the distance may be 5 mm or less. x The reference value of the distance may be 3 mm or less, more preferably 2 mm or less. y The reference value of the distance may be 10 mm or less. y The reference value of the distance may be 6 mm or less, more preferably 4 mm or less.

[0127] When the nth x Distance and nth y When one or more of the distances exceeds a reference value, the determination unit 40 may determine the alignment of the electrode and the diaphragm as misaligned.

[0128] The apparatus 100 for inspecting a stack of electrodes of a secondary battery according to an exemplary embodiment of the present invention may further include a control unit (not shown). The control unit may control the fixing part 20, the imaging unit 30, the stacking stage, and the like.

[0129] For example, the control unit may control the fixing and unfixing of the fixing portion 20 of the stacked body S and may control the imaging position of the imaging unit 30 .

[0130] When the apparatus 100 for inspecting a stack of electrodes of a secondary battery according to the exemplary embodiment of the present invention is included in an electrode assembly manufacturing apparatus, the electrode assembly manufacturing apparatus may further include an electrode realignment unit (not shown).

[0131] When the determination unit 40 determines that the stacking of the electrodes is defective, the electrode realignment unit may restack the electrodes determined to be defective. In an exemplary embodiment, the control unit may release the fixation of the fixing portion 20 for the battery stack S and move the stacking stage to the electrode realignment unit. Alternatively, the control unit may move the electrode realignment unit to the stacking stage to restack the electrodes.

[0132] A method for inspecting the stacking of electrodes of a secondary battery, comprising: a stacking body manufacturing step (S10), supplying a plurality of positive electrodes and negative electrodes to a stacking table and supplying a separator between the positive electrodes and the negative electrodes to manufacture a stacking body; a stacking body fixing step (S20), fixing the stacking body in a stacking direction using a fixing portion including at least one hole for exposing the stacking body; and a photographing step (S30), photographing the stacking body exposed through the hole.

[0133] In the stack fixing step ( S20 ), after the positive electrode or the negative electrode is supplied to the stacking stage, the stack may be fixed whenever a separator is stacked on one surface of the positive electrode or the negative electrode.

[0134] In the photographing step (S30), the holes of the fixing part and the stacking stage may be photographed. In this case, the holes may include a first hole for exposing a line where the diaphragm is folded, and a second hole for exposing a line orthogonal to the line where the diaphragm is folded.

[0135] In the photographing step ( S30 ), the first hole and the stacking stage, and the second hole and the stacking stage may be photographed separately, or the first hole, the second hole, and the stacking stage may be photographed simultaneously.

[0136] The method for inspecting a stack of electrodes of a secondary battery further includes a determination step ( S40 ) of determining whether the stack of the positive electrode, the negative electrode, and the separator is defective based on the data photographed in the photographing step ( S30 ).

[0137] In the determination step (S40), the distance between the first end or the second end of the diaphragm located in the first hole and the end of the stacking stage parallel to the first end or the second end is measured, or the distance between the third end or the fourth end of the diaphragm located in the second hole and the end of the stacking stage parallel to the third end or the fourth end is measured. Alternatively, in the determination step (S40), the distance between the first end or the second end and the end of the stacking stage parallel to the first end or the second end, and the distance between the third end or the fourth end and the end of the stacking stage parallel to the third end or the fourth end are measured.

[0138] In the determining step (S40), the nth distance between the first end or the second end of the nth stacked diaphragm and the end of the stacking stage may be x The distance is compared with a pre-stored reference value to determine whether the negative electrode, the positive electrode and the separator are misaligned, or the nth distance between the third end or the fourth end of the nth stacked separator and the end of the stacking stage can be y The distance is compared with the pre-stored reference value to determine whether the negative electrode, positive electrode and separator are misaligned.

[0139] The method for inspecting a stack of electrodes of a secondary battery may refer to the description of the apparatus for inspecting a stack of electrodes of a secondary battery.

[0140] Although the present invention has been described with reference to preferred exemplary embodiments, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the technical spirit and scope of the present invention.

[0141] Invention Mode

[0142] [Comparative Example]

[0143] In a comparative example, a device and method for inspecting the stacking of electrodes of a secondary battery of the related art are used, and the fixing portion included in the device for inspecting the stacking of electrodes of a secondary battery does not include a hole. In the method for inspecting the stacking of electrodes of a secondary battery, after stacking the electrodes and the separator, four fixing portions are used to fix the four corners of the stacking body. Before photographing the stacking state of the electrodes with an imaging unit, the fixation by the fixing portions is released and the stacking body is photographed. The determination unit measures the nth x Distance and nth y distance, the nth x Distance and nth y The distance is compared with a reference value and it is determined whether the stack of electrodes is defective.

[0144] [Example]

[0145] In an embodiment, an apparatus and method for inspecting a stack of electrodes of a secondary battery according to an exemplary embodiment of the present invention is used to determine whether the stack of electrodes is defective.

[0146] Figure 6 The nth electrode of each electrode in the stack measured in the comparative example is shown. x The distance is the same as the actual nth measured on the cut cross section of the stack x Fitted line plot of distance, Figure 7 The nth electrode of each stack measured in the embodiment is shown. xThe distance is the same as the actual nth measured on the cut cross section of the stack x A fitted line plot of the distances, and Figure 8 The nth electrode of each stack measured in the embodiment is shown. y The distance and the nth distance actually measured on the cut cross section of the stack y Fitted line plot of distance.

[0147] The nth x Distance. x Distance measurement location according to Figure 6 and Figure 7 The order of the upper right, lower right, upper left and lower left of the stack shown in FIG is referred to as x1, x2, x3 and x4. The nth y distance, and press Figure 8 The order of upper right, lower right, upper left and lower left of the stack shown in FIG. 1 is referred to as y1, y2, y3 and y4.

[0148] By plotting the nth x distance, and plotting on the y-axis the nth distance actually measured by cutting a cross section of the stack x Distance to create Figure 6 and Figure 7 Then, using the above variables, the regression equation is calculated by linear regression analysis. The calculated regression equation is different for each position, and the regression equation is written on the graph for each position. The R-squared value (R 2 ) are also written on the diagram for each position.

[0149] Reference Figure 6 , it can be seen that in the comparative example, x The distance is relative to the nth measured by the determined unit x The distribution of distances is widely spread around the fitting line. That is, the reliability of the fitting line of the comparative example, in other words, the R-squared value (R 2 ) is less than 60%, indicating low reliability.

[0150] Reference Figure 7 and Figure 8 It can be seen that the R square value (R 2 ) exceeds 64%, indicating that the reliability of the fitting line is high. That is, it can be confirmed that the nth x Distance and nth y The distance to the actual measured nth x Distance and nthy The distance values ​​are similar and reliable.

[0151] [Table 1]

[0152]

[0153] [Table 2]

[0154]

[0155] Tables 1 and 2 above show the nth measured values ​​using the apparatus for inspecting a stack of electrodes of a secondary battery according to an exemplary embodiment of the present invention. x Distance and nth y distance, and the nth distance actually measured by cutting a cross section of the stack x Distance and nth y The mean, standard deviation (σ) and process capability (Cp, Cpk) of the distance.

[0156] Cp (Capability of Process) refers to how much the group measurement results between the upper and lower limits are dispersed from the median. In Tables 1 and 2, the upper and lower limits of Cp refer to the nth x Distance and nth y The median is the y-axis value (the number of measurements of the central value) relative to the central value (the average value) of the x-axis. When the Cp value exceeds 1, it means that the population measurements are concentrated at the median.

[0157] Cpk (Capability of Process Katayori) refers to the degree of deviation from the median. In other words, Cpk refers to the degree to which the median shifts toward the upper limit or the lower limit.

[0158] Referring to Table 1 and Table 2, it can be seen that the nth x Distance and nth y Distance (visual measurement) vs. actual measurement of the nth distance through the cross section of the stack x Distance and nth y The distance is similar.

[0159] In addition, it can be seen that the standard deviation and Cpk values ​​are low and Cp is high, so the nth x Distance and nth y The distances are concentrated around the standard value.

Claims

1. An apparatus for inspecting a stack of electrodes of a secondary battery, the apparatus comprising: a stacking table on which a stack including a plurality of positive electrodes and negative electrodes and a separator disposed between the positive electrodes and the negative electrodes is placed; a fixing portion configured to fix one surface of the stacked body and including at least one hole for exposing the stacked body; as well as An imaging unit is configured to photograph the stacked body exposed through the hole. 2 . The apparatus according to claim 1 , wherein the imaging unit is configured to perform photographing whenever each of the plurality of positive electrodes and negative electrodes is stacked.

3. The device according to claim 1, wherein the diaphragm includes a first end, a second end facing the first end, and a third end and a fourth end connecting the first end and the second end, and The fixing portion includes a first hole for exposing the first end portion or the second end portion, and a second hole for exposing the third end portion or the fourth end portion. 4 . The apparatus according to claim 3 , wherein the imaging unit is configured to photograph the first hole, the second hole, and the stacking stage.

5. The device according to claim 3 further comprises a determination unit, which is configured to receive data captured by the imaging unit and is configured to analyze the positions of the positive electrode, the negative electrode and the separator to determine whether there is a miss align among the positive electrode, the negative electrode and the separator. 6 . The apparatus according to claim 5 , wherein the determination unit is configured to measure a distance between the first end or the second end of the diaphragm exposed through the first hole and an end of the stacking stage parallel to the first end or the second end.

7. The device according to claim 6, wherein the determining unit is configured to determine the nth x The distance is compared with a pre-stored reference value to determine whether there is misalignment between the negative electrode, the positive electrode and the separator, and the nth x The distance is the distance between the first end or the second end of the n-th stacked diaphragm and an end of the stacking stage.

8. The apparatus according to claim 5, wherein the determination unit is configured to measure a distance between the third end or the fourth end of the diaphragm exposed through the second hole and an end of the stacking stage parallel to the third end or the fourth end.

9. The device according to claim 8, wherein the determining unit is configured to determine the nth y The distance is compared with a pre-stored reference value to determine whether there is misalignment between the negative electrode, the positive electrode and the separator, and the nth y The distance is the distance between the third end or the fourth end of the n-th stacked diaphragm and the end of the stacking stage. 10 . The apparatus according to claim 1 , wherein the fixing portion is provided in plural, and two of the fixing portions are provided in a pair along a length direction of the stacked body. 11 . The apparatus according to claim 10 , wherein the fixing portion comprises two pairs of fixing portions, and the two pairs of fixing portions alternately fix the stacked body.

12. A method for inspecting a stack of electrodes of a secondary battery, the method comprising: manufacturing a stacked body by supplying a plurality of positive electrodes and negative electrodes to a stacking stage and supplying a separator between the positive electrodes and the negative electrodes; fixing the stacked body in a stacking direction using a fixing portion including at least one hole for exposing the stacked body; as well as The stacked body exposed through the hole is photographed. 13 . The method according to claim 12 , wherein during fixing the stacked body and the photographing, whenever the separator is supplied to one surface of each of the positive electrode and the negative electrode, the stacked body is fixed and the hole of the fixing portion and the stacking stage are photographed.

14. The method according to claim 12, wherein the diaphragm includes a first end, a second end facing the first end, and a third end and a fourth end connecting the first end and the second end, and In the fixing, the fixing portion includes a first hole for exposing the first end or the second end and a second hole for exposing the third end or the fourth end. The method of claim 14 , wherein the photographing includes photographing the first hole, the second hole, and the stacking stage. 16 . The method according to claim 14 , further comprising determining whether there is misalignment of the positive electrode, the negative electrode, and the separator by analyzing positions of the positive electrode, the negative electrode, and the separator through photographed data. 17 . The method of claim 16 , wherein during the determining, a distance between the first end or the second end of the diaphragm exposed through the first hole and an end of the stacking stage parallel to the first end or the second end is measured.

18. The method according to claim 17, wherein during the determining, by x The distance is compared with a pre-stored reference value to determine whether there is misalignment between the negative electrode, the positive electrode and the separator, and the nth x The distance is the distance between the first end or the second end of the n-th stacked diaphragm and an end of the stacking stage.

19. The method of claim 16, wherein during the determining, a distance between the third end or the fourth end of the diaphragm exposed through the second hole and an end of the stacking stage parallel to the third end or the fourth end is measured.

20. The method of claim 19, wherein during the determining, by y The distance is compared with a pre-stored reference value to determine whether there is misalignment between the negative electrode, the positive electrode and the separator, and the nth y The distance is the distance between the third end or the fourth end of the n-th stacked diaphragm and the end of the stacking stage.

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