Tab forming apparatus of electrode assembly

Abstract

A forming device according to one embodiment of the present invention radially bends an electrode tab exposed by a first electrode of an electrode assembly in which the first electrode, a separator and a second electrode are stacked and wound around the circumference of a central axis, the first electrode extending further toward an axial end than the separator, and comprises a forming jig for bending the electrode tab, wherein the forming jig includes an opposing surface that faces the electrode assembly, and the opposing surface has a recess depth of the opposing surface recessed in the direction opposite to the pressing direction.

Description

Electrode assembly tab forming device

[0001] The present invention relates to an electrode assembly tab forming device.

[0002] This application claims priority to Korean Patent Application No. 10-2023-0115853, filed on August 31, 2023, and all contents disclosed in the specification and drawings of the said application are incorporated herein by reference.

[0003] Secondary batteries, which boast high electrical properties such as high energy density and high applicability across a wide range of product categories, are widely used not only in portable devices but also in electric vehicles (EVs) and hybrid electric vehicles (HEVs) powered by electrical power sources. These batteries are attracting attention as a new energy source for environmental friendliness and energy efficiency, not only because they can dramatically reduce fossil fuel use, but also because they produce no byproducts from energy use.

[0004] Currently, widely used types of secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. The operating voltage of these unit secondary battery cells, i.e., unit battery cells, is approximately 2.5 V to 4.5 V. Therefore, when a higher output voltage is required, multiple battery cells are connected in series to form a battery pack. Furthermore, depending on the charge / discharge capacity required for the battery pack, a number of battery cells are connected in parallel to form a battery pack. Therefore, the number of battery cells included in the battery pack can be set in various ways depending on the required output voltage and / or charge / discharge capacity.

[0005] Meanwhile, conventional cylindrical secondary batteries typically have a structure in which tabs connecting the jelly-roll and the external terminal are welded to the foil of the jelly-roll. However, cylindrical secondary batteries with this structure have a limited current path, and the resistance of the jelly-roll itself is bound to be very high. Furthermore, attempts have been made to lower resistance by increasing the number of tabs connecting the jelly-roll and the external terminal, but simply increasing the number of tabs has limitations in lowering resistance to the desired level while securing sufficient current paths.

[0006] As the current applied to the secondary battery increases, a new jelly-roll structure is being developed in which the exposed non-conductive portions of the axial end of the jelly-roll are bent radially to make them flat and connected to a current collector plate by welding or other methods in order to lower the resistance, and the current collector plate is connected to an external terminal.

[0007] To produce an electrode assembly of this type, a machining process is required to expose the non-conductive portions at both axial ends of the electrode assembly and bend them radially. This bending process is typically performed using a forming jig.

[0008] In the past, a first process was performed using an iris shutter type jig to gather the ends of the uncoated portions that were extended straightly in the axial direction so as to be inclined in the radial direction, and then a second process was performed to gather and press the uncoated portions that were inclined in the radial direction a little more using a jig that rotates based on a rotational axis corresponding to the axis of the electrode assembly, and finally, a third process was performed to press the inclined electrodes as flat as possible using a flat jig.

[0009] Here, if the above secondary processing was performed without the primary processing that gathers the ends of the plain portion radially, the buckling phenomenon of the plain portion collapsing could not be avoided. Therefore, the primary processing that gathers the ends of the plain portion radially was essential.

[0010] Also, when performing secondary processing, if the plain part is pressed without rotating the jig, the frictional force between the end of the jig and the plain part causes the plain part to still buckle. Therefore, the process of pressing the plain part while rotating the jig was essential when performing secondary processing.

[0011] In this way, the conventional jelly-roll type electrode assembly's non-woven bending forming process required many steps and the equipment required for each step had to have a complex structure.

[0012] These multi-stage processing processes and complex processing equipment had limitations in reducing the processing cycle and equipment size.

[0013] Meanwhile, to address these issues, a tab forming device has been developed that reduces the number of processing steps required to radially bend and flatten the exposed, uncoated portion of the electrode assembly's axial end, and simplifies the processing methods for each processing step. However, even these forming devices fail to account for the overlap of the uncoated portion, resulting in uncoated portion buckling. If uncoated portion buckling occurs, it is possible that a short circuit may occur within the battery, potentially escalating into a thermal event.

[0014] Accordingly, the present invention aims to effectively prevent internal short circuit of a battery.

[0015] In another aspect, the present invention aims to prevent buckling of the non-coated portion by providing a jig that takes into account the amount of overlap of the non-coated portion of the electrode assembly.

[0016] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0017] According to one embodiment of the present invention for solving the above-described problem, a forming device is a forming device that radially bends an electrode tab of an electrode assembly in which a first electrode, a separator, and a second electrode are laminated and wound around a central axis, and the first electrode is extended further in the axial direction than the separator, and is exposed, wherein the forming device includes a forming jig that bends the electrode tab, and the forming jig includes an opposing surface facing the electrode assembly, and the opposing surface has an insertion depth of the opposing surface that is inserted in a direction opposite to a pressing direction.

[0018] For example, the opposing surface may have a shape curved in the opposite direction to the pressing direction.

[0019] In one aspect of the present invention, the depth of penetration of the opposing surface, which is inserted in a direction opposite to the pressing direction, may be configured to increase as it goes toward the central axis.

[0020] In another aspect of the present invention, the depth of the indentation of the opposing surface, which is indented in the direction opposite to the pressing direction, may be configured to increase and then decrease from the center side to the outer periphery side.

[0021] In another aspect of the present invention, the depth of the indentation of the opposing surface, which is indented in the direction opposite to the pressing direction, may be configured to increase from the center side to the outer periphery side, maintain a constant length, and then decrease.

[0022] Preferably, the depth of the indentation of the opposing surface, which is indented in the direction opposite to the pressing direction, may be configured to linearly increase from the center side to the outer periphery side, maintain a constant length, and then linearly decrease.

[0023] In one aspect of the present invention, at least a portion of the electrode tab of the electrode assembly can be divided into a plurality of independently bendable segments.

[0024] Here, the electrode assembly may include a uniform number of stacks section in which the number of stacks of the segments is greater than or equal to a predetermined number of stacks along the radial direction of the folded surface area of ​​the folded electrode assembly, and a stack number decreasing section adjacent to the uniform number of stacks section and in which the number of stacks of the segments decreases as the distance from the uniform number of stacks section increases.

[0025] Preferably, the electrode assembly may include a section in which the number of stacked segments increases along the radial direction in a folded surface area of ​​the folded electrode assembly.

[0026] In another aspect of the present invention, the depth of the insertion may be configured to be greater than the stacking thickness of the segment.

[0027] In another aspect of the present invention, the depth of the insertion can be configured to be equal to the thickness of the laminate of the segment.

[0028] In one aspect of the present invention, the penetration depth may be configured to be 100 um to 875 um.

[0029] In another aspect of the present invention, the penetration depth can be configured to be 50 um to 700 um.

[0030] In another aspect of the present invention, the forming jig may be configured to include a steel material.

[0031] The present invention can effectively prevent internal short circuit of a battery.

[0032] In another aspect, according to the present invention, a jig is provided that takes into account the amount of overlap of the non-coated portion of the electrode assembly, thereby effectively preventing the non-coated portion buckling phenomenon.

[0033] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0034] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0035] Figure 1 is a plan view of a first embodiment of a first electrode having a non-conductive portion and a maintenance portion.

[0036] Figure 2 is a side view showing the laminated state of electrodes and separators for winding into a jelly-roll type electrode assembly.

[0037] Figure 3 is a front view showing the process of bending the exposed electrode portions at both axial ends of the electrode assembly in the radial direction as electrode tabs and stacking the current collector plates.

[0038] Fig. 4 is a plan view of a second embodiment of a first electrode having a non-conductive portion and a maintenance portion.

[0039] Fig. 5 is a front view showing a jelly-roll-shaped electrode assembly using the electrode of Fig. 4.

[0040] FIG. 6 is a graph showing the results of counting the number of stacked segments along the radial direction in the folded surface area formed on the upper portion of electrode assemblies according to one embodiment of the present invention.

[0041] Fig. 7 is a drawing showing the bending result of an electrode assembly using a conventional flat jig.

[0042] FIG. 8 is a plan view of an electrode assembly according to one embodiment of the present invention and a forming jig of a forming device for bending an electrode tab provided at an axial end of the electrode assembly.

[0043] Fig. 9 is a cross-sectional drawing of the forming jig of Fig. 8.

[0044] FIG. 10 is a drawing for explaining a forming jig according to another embodiment of the present invention.

[0045] Figure 11 is a schematic diagram showing a cross-section of a folded surface area formed when a segment is folded toward the core side of an electrode assembly.

[0046] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, it should be noted that the terms and words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention, they should be interpreted in a way that conforms to the technical spirit of the present invention.

[0047] Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, so it should be understood that there may be various equivalents and modified examples that can replace them at the time of this application.

[0048] Additionally, to aid understanding of the invention, the attached drawings are not drawn to scale and the dimensions of some components may be exaggerated.

[0049]

[0050] Figure 1 is a plan view of a first embodiment of a first electrode having a non-conductive portion and a maintenance portion.

[0051] Figure 2 is a side view showing the stacking state of an electrode and a separator (16) for winding into a jelly-roll-shaped electrode assembly (10).

[0052] Figure 3 is a front view showing the process of bending the electrode portion exposed at both axial ends of the electrode assembly (10) in the radial direction as an electrode tab (11) and stacking a current collector plate.

[0053] Fig. 4 is a plan view of a second embodiment of a first electrode having a non-conductive portion and a maintenance portion.

[0054] Fig. 5 is a front view showing a jelly-roll-shaped electrode assembly (10) to which the electrode of Fig. 4 is applied.

[0055]

[0056] Hereinafter, with reference to FIGS. 1 to 5, embodiments of electrode assemblies (10) in which the forming device according to the present invention can be used will be described. However, the forming device of the present invention is not necessarily applicable only to electrode assemblies (10) having the structure described below.

[0057] The electrode assembly (10) to which the forming device of the present invention is applied is formed by stacking a first electrode (15), a separator (16), and a second electrode (17) in the form of sheets having a predetermined width in the width direction (Y) and extending long in the length direction (X) in the order of the first electrode (15), the separator (16), the second electrode (17), and the separator (16) at least once, and winding them around the winding axis (Y).

[0058] The first electrode (15) and / or the second electrode (17) are manufactured in a form in which an active material is coated on a metal foil. The first electrode (15) and / or the second electrode (17) includes a holding region in which the active material is coated on the metal foil, and a non-coated region in which the surface of the metal foil is exposed because the active material is not coated. At one end in the width direction (Y), i.e., the axial direction (Y), of the first electrode (15), there is a first electrode tab (11) region, which is a non-coated region in which the active material is not coated. And / or at the other end in the width direction (Y), i.e., the axial direction (Y), of the second electrode (17), there is a second electrode tab (12) region, which is a non-coated region in which the active material is not coated. The electrode tab (11) can be electrically connected to an electrode terminal and a current collector plate provided in a battery can (not shown) in which the electrode assembly (10) is to be accommodated.

[0059] In order to roll up the electrode assembly (10) in a jelly-roll shape, when stacking the first electrode (15), the separator (16), the second electrode (17), and the separator (16), the first electrode tab (11) and the second electrode tab (12) are stacked so that each of the width direction (Y) of the separator (16) and one end and the other end in the axial direction (Y) are further exposed (protruded), respectively. Then, by rolling up the laminate formed by stacking in this manner in the X-axis direction with the Y-axis as the center, the electrode assembly (10) can be manufactured.

[0060] The electrode assembly (10) applied to the present invention may be of the jelly-roll type. In this case, an additional separator (16) may be provided on the outer peripheral surface of the electrode assembly (10) for insulation from the battery can.

[0061] The first electrode (15) includes a first electrode current collector (metal foil) and a first electrode active material (151) applied on one or both sides of the first electrode current collector. A non-coated portion on which the first electrode active material is not applied exists at one end in the width direction (Y) of the first electrode current collector. The non-coated portion functions as a first electrode tab (11). The first electrode tab (11) is provided on the upper portion of the electrode assembly (10) in the height direction (Y).

[0062] The second electrode includes a second electrode current collector (metal foil) and a second electrode active material applied to one or both surfaces of the second electrode current collector. A non-coated portion on which the second electrode active material is not applied exists on the other end of the second electrode current collector in the width direction (Y). The non-coated portion functions as a second electrode tab (12). The second electrode tab (12) is provided at the lower portion in the height direction of the electrode assembly (10).

[0063] The above first electrode tab (11) and the above second electrode tab (12) may be, for example, a positive electrode tab and a negative electrode tab or vice versa.

[0064] In the present invention, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate can be used without limitation as long as they are active materials known in the art.

[0065] In one example, the positive electrode active material has the general chemical formula A[A x M y ]O 2+z (A includes at least one element selected from Li, Na, and K; M includes at least one element selected from Ni, Co, Mn, Ca, Mg, Al, Ti, Si, Fe, Mo, V, Zr, Zn, Cu, Al, Mo, Sc, Zr, Ru, and Cr; x ≥ 0, 1 ≤ x+y ≤ 2, 0.1 ≤ z ≤ 2; stoichiometric coefficients x, y, and z are selected such that the compound maintains electrical neutrality) may include an alkali metal compound represented by the following formula:

[0066] In another example, the positive electrode active material is an alkali metal compound xLiM as disclosed in US6,677,082, US6,680,143, etc. 1 O2(1x)Li2M 2 O3(M 1 contains at least one element having an average oxidation state of 3; M 2 contains at least one element having an average oxidation state of 4; 0 ≤ x ≤ 1).

[0067] In another example, the positive electrode active material has the general chemical formula Li a M 1 x Fe 1­x M 2 y P 1­y M 3 z O 4­z (M 1 Contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg and Al; M 2 contains at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, Al, As, Sb, Si, Ge, V and S; M 3 may be a lithium metal phosphate represented by Li3M2(PO4)3 [M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg and Al], wherein the compound comprises a halogen element optionally including F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; the stoichiometric coefficients a, x, y and z are selected so that the compound remains electrically neutral].

[0068] Preferably, the positive electrode active material may include primary particles and / or secondary particles in which primary particles are aggregated.

[0069] In one example, the negative active material may be carbon, lithium metal or a lithium metal compound, silicon or a silicon compound, tin or a tin compound, etc. Metal oxides such as TiO2 and SnO2 with a potential of less than 2 V can also be used as the negative active material. Carbon materials such as low-crystalline carbon and high-crystalline carbon can all be used.

[0070] The separator (16) may be a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, etc., which may be used alone or in a laminated manner. As another example, the separator (16) may be a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc.

[0071] At least one surface of the separator (16) may include a coating layer of inorganic particles. Furthermore, the separator (16) itself may be formed of a coating layer of inorganic particles. The particles constituting the coating layer may have a structure in which they are combined with a binder such that an interstitial volume exists between adjacent particles.

[0072] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or higher. As a non-limiting example, the inorganic particles may be Pb(Zr,Ti)O3(PZT), Pb 1­x La x Zr 1­y Ti y O3(PLZT), PB(Mg3Nb 2 / 3 )O3PbTiO3(PMNPT), BaTiO3, hafnia(HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO and Y2O3.

[0073]

[0074] The first electrode tab (11) and the second electrode tab (12) may be electrically connected to the collector plates (21, 22), respectively. The first electrode tab (11) and the second electrode tab (12) may be joined to the first collector plate (21) and the second collector plate (22), respectively, by welding or the like, in a state where they are bent in the radial direction, as illustrated in FIG. 3.

[0075]

[0076] The forming device of the present invention is a processing device for bending the first electrode tab (11) and the second electrode tab (12) in the radial direction.

[0077] The shapes of the first electrode tab (11) and the second electrode tab (12) to which the above forming device can be applied are not limited to the structure described above. The first electrode tab (11) illustrated in Fig. 1 has a shape in which the first electrode tab (11) extends continuously in the winding direction (longitudinal direction) (X). However, the first electrode tab (11) may also have a shape that is discontinuous in the winding direction (longitudinal direction) (X).

[0078]

[0079] Referring to Fig. 4, the first electrode tab (11) provided on the first electrode (15) may be cut in the axial direction (height direction) (Y) at predetermined intervals along the longitudinal direction. By this cutting line, the first electrode tab (11) may have a form in which a plurality of segments (111) are arranged along the longitudinal direction.

[0080] The shape of the segment (111) formed by the above-described cutting line may be an equilateral trapezoid or a rectangle as illustrated, and may also have various other shapes such as a semicircle or a semi-ellipse. In addition, segments (111) of various shapes may be used together, and the width and height of the segments (111) and the spacing between the segments (111) may be constant or may vary under certain rules.

[0081] Meanwhile, as illustrated in Fig. 4, a bottom line (BL), which is a virtual line connecting the bottoms of the segments (111), can be defined. The bottom line (BL) may be, for example, a straight line or a curved line.

[0082] Also, as illustrated in FIGS. 4 and 5, the segment (111) may be omitted in a predetermined section (B1) near the core, and within the section (B2) where the segment (111) is provided, the segment (111) may have a shape in which the height protruding in the axial direction gradually or stepwise increases from the core toward the outer periphery. Although not illustrated in the drawings, the segment (111) may be deleted in the last single turn section (B3) for convenience of processing, etc. Or, as another embodiment, unlike FIGS. 4 and 5, within the section (B2) where the segment (111) is provided, the segment (111) may have a shape in which the height protruding in the axial direction is the same.

[0083] When the electrode tab (11) is formed in the form of a segment (111) as described above, the lower end of the segment (111) can be bent when the electrode tab (11) is bent in the radial direction. For example, the segment (111) can be bent along the bottom line (BL) illustrated in FIG. 4. Alternatively, the segment (111) can be bent at a position higher than the bottom line (BL) illustrated in FIG. 4.

[0084]

[0085] FIG. 6 is a graph showing the result of counting the number of stacked segments along the radial direction in the bending surface area formed on the upper portion of electrode assemblies (10) according to one embodiment of the present invention, and FIG. 7 is a drawing showing the result of bending of an electrode assembly (10) to which a conventional flat jig is applied.

[0086] Referring to FIG. 6, a section (b1) of the number of stacks of the segments is shown. The section (b1) of the number of stacks is a radial section of a flat area in each graph. Outside of the section (b1) of the number of stacks, a section (b2) of decreasing stacks in which the number of stacks of the segments decreases as the radius increases appears. The section (b2) of decreasing stacks is a radial section in which the number of stacks of the segments decreases as the radius of the electrode assembly (10) increases. The section (b1) of the number of stacks and the section (b2) of decreasing stacks are adjacent in the radial direction. Meanwhile, inside the section (b1) of the number of stacks, a section (b3) of increasing stacks in which the number of stacks of the segments increases as the radius increases appears. The section (b3) of increasing stacks in which the number of stacks of the segments increases as the radius of the electrode assembly (10) increases. The reason why the number of stacked sections in the electrode assembly (10) changes is due to the height of the segments, the starting position of the segments, the ending position of the segments, etc. As a result, depending on the number of stacked sections, the axial height of the folded surface area of ​​the electrode assembly (10) may vary in the radial direction.

[0087] Meanwhile, the conventional flat jig was configured as a jig having a flat surface facing the electrode tab (11). Since the conventional flat jig has a flat shape that does not take into account the overlapping thickness, the electrode assembly (10) is pressed into a flat shape.

[0088] As a result, multiple electrode tabs (11) are buckled, as shown in Fig. 7. In this case, the likelihood of the buckled electrode tabs (11) coming into contact with the electrode tabs (11) having adjacent opposing electrodes increases. Therefore, the likelihood of an internal short circuit occurring in the battery increases, which ultimately leads to a thermal event.

[0089] The present invention was created to solve these problems, and will be described in detail with reference to FIGS. 8 to 11 below.

[0090]

[0091] FIG. 8 is a plan view of an electrode assembly (10) according to one embodiment of the present invention and a forming jig (100) of a forming device for bending an electrode tab (11) provided at an axial end of the electrode assembly (10).

[0092] Referring to FIGS. 8 and 9, the forming device may be configured to bend the exposed electrode tab (11) in a radial direction so that the first electrode of the electrode assembly (10) in which the first electrode, the separator (16), and the second electrode are laminated and wound around the central axis extends further in the axial direction than the separator (16).

[0093] The forming jig (100) and the flattening jig (50) can be made of steel. The forming jig (100) can bend the electrode tabs (11) that extend straightly in the axial direction and are arranged in a spiral shape radially inward without buckling.

[0094] More specifically, the forming device may include a forming jig (100) for bending the electrode tab (11). The forming jig (100) may include a facing surface (S) facing the electrode assembly (10). In particular, the forming jig (100) may face the electrode tab (11) of the electrode assembly (10). Here, the facing surface (S) may be configured to have an indentation depth of the facing surface (S) that is indented in a direction opposite to the pressing direction (D).

[0095] According to this structure, bending can be performed considering the different overlapping thickness of the electrode tabs (11) at each bending position of the electrode tabs (11). That is, even if there is a region where the overlapping thickness of the electrode tabs (11) is thick, since the depth of the facing surface (S) is set to a predetermined depth, buckling of the electrode tabs (11) can be prevented.

[0096]

[0097] Fig. 9 is a cross-sectional drawing of the forming jig (100) of Fig. 8.

[0098] In one embodiment, the opposing surface (S) may be configured to have a shape that is curved in a direction opposite to the pressing direction (D). For example, the opposing surface (S) may have a convex curved shape in a direction opposite to the pressing direction (D). For example, as in the embodiment of FIG. 9, the indentation depth of the opposing surface (S) that is indented in a direction opposite to the pressing direction (D) may have a shape that increases toward the central axis.

[0099] In another embodiment, the opposing surface (S) may be configured to have an approximately parabolic shape. That is, it may be configured to have the deepest indentation depth at the central axis and to have the depth decrease toward the outer periphery.

[0100] With this structure, bending can be made possible by considering the profile of the laminated number reduction section (b2). That is, since the shape of the opposing surface (S) is configured to correspond to the profile of the laminated number reduction section (b2) located on the outer circumference of the electrode assembly (10), buckling of the electrode tab (11) located in the laminated number reduction section (b2) can be prevented. In addition, since the jig shape is monotonous, it can be advantageous in terms of jig manufacturing.

[0101]

[0102] FIG. 10 is a drawing for explaining a forming jig (100) according to another embodiment of the present invention.

[0103] In another embodiment of the present invention, the depth of the facing surface (S) inserted in the direction opposite to the pressing direction (D) may be configured to increase and then decrease from the center toward the outer periphery.

[0104] For example, referring to Fig. 10, the depth of the indentation of the opposing surface (S) is configured to increase and then decrease from the center toward the outer periphery.

[0105] According to a structure like this, bending can be made possible by considering the profiles of the stacking number reduction section (b2) and the stacking number increase section (b3). That is, since the shape of the opposing surface (S) is configured to correspond to the profile of the stacking number reduction section (b2) located on the outer circumference of the electrode assembly (10) and the profile of the stacking number increase section (b3) located on the center side of the electrode assembly (10), buckling of the electrode tab (11) located in the stacking number reduction section (b2) and the stacking number increase section (b3) can be effectively prevented.

[0106]

[0107] In another embodiment of the present invention, the depth of penetration of the opposing surface (S) inserted in the direction opposite to the pressing direction (D) may be configured to be constant, increase, and then decrease from the center toward the outer periphery.

[0108] For example, unlike FIG. 10, from the point where the electrode tab (11) begins to be formed, the depth of the indentation of the opposing surface (S) can be configured to increase and then decrease from the center toward the outer periphery.

[0109] According to a structure like this, bending can be made possible by more accurately considering the profiles of the stacking number reduction section (b2) and the stacking number increase section (b3). That is, since the shape of the opposing surface (S) is configured to correspond to the profile of the stacking number reduction section (b2) located on the outer periphery of the electrode assembly (10) and the profile of the stacking number increase section (b3) located on the center side of the electrode assembly (10), buckling of the electrode tab (11) located in the stacking number reduction section (b2) and the stacking number increase section (b3) can be effectively prevented.

[0110]

[0111] In another embodiment of the present invention, the depth of the facing surface (S) inserted in the direction opposite to the pressing direction (D) may increase from the center toward the outer periphery, maintain a constant length, and then decrease.

[0112] For example, referring again to Figure 6, from the center to the outer periphery, a section with an increasing number of layers (b3), a section with a uniform number of layers (b1), and a section with a decreasing number of layers (b2) appear in that order.

[0113] Therefore, according to the present embodiment, bending can be achieved by comprehensively considering the profiles of the stacking number increasing section (b3), the stacking number uniform section (b1), and the stacking number decreasing section (b2). That is, since the shape of the opposing surface (S) is configured to correspond to the profile of the stacking number decreasing section (b2) located on the outer circumference of the electrode assembly (10), the profile of the stacking number increasing section (b3) located on the central side of the electrode assembly (10), and the stacking number uniform section (b1) located between the stacking number decreasing section (b2) and the stacking number increasing section (b3), buckling of the electrode tabs (11) located in the stacking number increasing section (b3), the stacking number uniform section (b1), and the stacking number decreasing section (b2) can be effectively prevented. Furthermore, since the electrode tabs (11) are bent only by an amount corresponding to the stacking layer thickness at all radial positions, a result in which the electrode tabs (11) are reliably in contact with each other can be achieved without buckling.

[0114]

[0115] More preferably, the depth of penetration of the opposing surface (S) inserted in the direction opposite to the pressing direction (D) may be configured to linearly increase from the center toward the outer periphery, maintain a constant length, and then linearly decrease.

[0116] For example, as can be seen in Fig. 6, the increase and decrease in the number of stacked electrode tabs (11) can be linearly achieved. Accordingly, by a structure in which the indentation depth of the opposing surface (S) linearly increases from the center toward the outer periphery, maintains a constant length, and then linearly decreases, a result in which the electrode tabs (11) are reliably in contact with each other without buckling at any radial position in particular can be achieved.

[0117] Meanwhile, as described above, the number of stacked electrode tabs (11) may vary depending on the height of the segment, the starting position of the segment, and the ending position of the segment. For example, the number of stacked electrode tabs (11) may increase and / or decrease in a curved shape. If the number of stacked electrode tabs varies in this way, it is of course possible to change the jig shape accordingly.

[0118]

[0119] Meanwhile, at least a portion of the electrode tab (11) of the electrode assembly (10) may be divided into a plurality of independently bendable segments.

[0120] For example, referring back to FIG. 4, at least a portion of the electrode tab (11) of the electrode assembly (10) may be divided into a plurality of independently bendable segments, and the bending surface area of ​​the bent electrode assembly (10) may include a uniform number of stacks section (b1) in which the number of stacks of the segments is equal to or greater than a predetermined number of stacks along the radial direction, and a decreasing number of stacks section (b2) adjacent to the uniform number of stacks section (b1) and in which the number of stacks of the segments decreases as they move away from the uniform number of stacks section (b1). In addition, the bending surface area of ​​the bent electrode assembly (10) may include a increasing number of stacks section (b3) in which the number of stacks of the segments increases along the radial direction.

[0121] In one aspect of the present invention, the depth of the insertion may be configured to be greater than the laminated thickness of the segment. If the depth of the insertion is configured to be less than the laminated thickness of the segment, the electrode tab (11) is excessively pressed by the forming jig (100), and thus, a buckling phenomenon of the electrode tab (11) cannot be avoided.

[0122] Therefore, according to the above structure of the present invention, since the depth of insertion is configured to be greater than the laminated thickness of the segment, excessive pressurization and buckling of the electrode tab (11) can be effectively prevented.

[0123]

[0124] In another aspect of the present invention, the depth of the insertion may be configured to be equal to the laminated thickness of the segments. With this structure, since the depth of the insertion is configured to be greater than the laminated thickness of the segments, excessive pressing and buckling of the electrode tabs (11) can be effectively prevented. At the same time, the electrode tabs (11) can be reliably brought into contact and overlap each other without buckling.

[0125]

[0126] In one aspect of the present invention, the penetration depth can be determined as follows.

[0127] Embedding depth ≤ foil thickness * maximum number of foil layers

[0128] That is, the above-mentioned indentation depth may be less than or equal to the indentation depth of the maximum laminated thickness of the foil at a specific point in the radial direction.

[0129] Specifically, the electrode may be a first electrode (15). At this time, the thickness of the positive electrode current collector (foil) constituting the first electrode (15) may be 10 um to 25 um. Accordingly, the folded surface area (F) of the positive electrode may include an area in which the total laminated thickness of the segments is 100 um to 875 um.

[0130] In one aspect of the present invention, the penetration depth may be configured to be between 100 um and 875 um. For example, when the electrode tab (11) is a positive electrode tab, the total laminated thickness of the segments may be between 100 um and 875 um. Accordingly, when the penetration depth is between 100 um and 875 um, the total laminated thickness of the segments can be prevented from unnecessary buckling and short circuiting.

[0131]

[0132] Meanwhile, the electrode may be a second electrode (17). At this time, the thickness of the negative electrode current collector (foil) constituting the second electrode (17) may be 5 um to 20 um. Accordingly, the folded surface area (F) of the negative electrode may include an area in which the total laminated thickness of the segments is 50 um to 700 um.

[0133] In another aspect of the present invention, the penetration depth may be configured to be between 50 um and 700 um. For example, when the electrode tab (11) is a negative tab, the total laminated thickness of the segments may be between 50 um and 700 um. Accordingly, when the penetration depth is between 50 um and 700 um, the total laminated thickness of the segments can be prevented from unnecessary buckling and short circuits.

[0134]

[0135] Figure 11 is a schematic diagram showing a cross-section of a folded surface area formed when a segment is folded toward the core side of an electrode assembly (10).

[0136] Referring to Fig. 11, the bending surface area (F) has a structure in which segments (111) are overlapped in multiple layers in the direction of the winding axis. The overlapping direction is the direction of the winding axis (Y). Section ① is a segment-omitting section (first part B1) without a segment, and sections ② and ③ are sections (second part B2) in which a winding turn including a segment (111) is located. More specifically, section ② is a uniform-height section in which the height of the segment is maintained uniform, and section ③ is a variable-height section in which the height of the segment (111) is variable. Here, the radial lengths of sections ② and ③ may vary depending on the embodiment.

[0137] As a result of applying the forming device of FIGS. 8 to 10 as described above and pressing the electrode tabs (11) of the electrode assembly (10), it was possible to achieve a result in which the electrode tabs (11) were firmly in contact with and overlapped with each other while maintaining the electrode lamination thickness profile without buckling, as shown in FIG. 11.

[0138] That is, the present invention can effectively prevent internal short circuits in a battery according to various embodiments as described above. Furthermore, according to the present invention, a jig is provided that takes into account the amount of overlap of the non-coated portion of the electrode assembly (10), thereby effectively preventing the non-coated portion buckling phenomenon.

[0139]

[0140] Meanwhile, although terms indicating directions such as up and down are used in this specification, it is obvious to those skilled in the art that these terms are only for convenience of explanation and may vary depending on the location of the target object or the location of the observer.

[0141] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0142]

[0143] [Explanation of symbols]

[0144] 10: Electrode assembly

[0145] r: radius

[0146] 11: Electrode tab (first electrode tab)

[0147] 111: Segmentation

[0148] 12: Electrode tab (second electrode tab)

[0149] 15: First electrode

[0150] 151: First electrode active material

[0151] 16: Membrane

[0152] 17: Second electrode

[0153] H1: Winding hole (hollow part)

[0154] X: longitudinal, circumferential, winding direction

[0155] Y: width direction, winding axis, axial direction, central axis, height direction

[0156] Z: Radial, Normal

[0157] 21: Collector board (first collector board)

[0158] 22: Collector plate (second collector plate)

[0159] 100: Forming Jig

[0160] S: Opposite side

[0161] D: Pressurization direction

Claims

1. A forming device for bending an exposed electrode tab in a radial direction by extending the first electrode of an electrode assembly in which a first electrode, a separator, and a second electrode are laminated and wound around a central axis, and the first electrode is extended further in the axial direction than the separator. A forming device, characterized in that the forming device includes a forming jig for bending the electrode tab, the forming jig includes an opposing surface facing the electrode assembly, and the opposing surface has an insertion depth of the opposing surface inserted in a direction opposite to a pressing direction.

2. In paragraph 1, A forming device characterized in that the opposing surface has a shape curved in the opposite direction to the pressing direction.

3. In paragraph 1, A forming device characterized in that the depth of penetration of the opposing surface, which is inserted in a direction opposite to the pressing direction, increases as it goes toward the central axis.

4. In paragraph 1, A forming device characterized in that the depth of penetration of the opposing surface, which is penetrated in the direction opposite to the pressing direction, increases and then decreases from the center side to the outer periphery side.

5. In paragraph 1, A forming device characterized in that the depth of penetration of the opposing surface, which is penetrated in the direction opposite to the pressing direction, increases from the center side to the outer periphery side, maintains a constant length, and then decreases.

6. In paragraph 1, A forming device characterized in that the depth of penetration of the opposing surface, which is penetrated in the direction opposite to the pressing direction, increases linearly from the center to the outer periphery, maintains a constant length, and then linearly decreases.

7. In paragraph 1, At least a portion of the electrode tab of the electrode assembly is divided into a plurality of independently bendable segments, A forming device characterized in that the bending surface area of ​​the bent electrode assembly includes a uniform number of laminates section in which the number of laminates of the segments is greater than or equal to a predetermined number of laminates along the radial direction and a decreasing number of laminates section located adjacent to the uniform number of laminates section and in which the number of laminates of the segments decreases as they move away from the uniform number of laminates section.

8. In paragraph 7, The above electrode assembly, A forming device characterized in that the bending surface area of ​​the bent electrode assembly includes a stacking number increasing section in which the number of stacked segments increases along the radial direction.

9. In paragraph 7, A forming device characterized in that the above-mentioned depth is greater than the laminated thickness of the segment.

10. In paragraph 7, A forming device characterized in that the above-mentioned depth is the same as the laminated thickness of the segment.

11. In paragraph 1, A forming device characterized in that the above-mentioned penetration depth is 100 um to 875 um.

12. In paragraph 1, A forming device characterized in that the above-mentioned penetration depth is 50 um to 700 um.

13. In paragraph 1, A forming device characterized in that the forming jig comprises a steel material.

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