Joint forming apparatus for electrode assembly

Abstract

A forming device according to one embodiment of the present invention radially bends an electrode tab exposed through a first electrode of an electrode assembly in which the first electrode, a separator, and a second electrode are laminated and wound around a central axis, the first electrode extending further toward an axial end than the separator, and the second electrode extending further toward an axial end than the separator. The forming apparatus includes a forming jig for bending the electrode tab, in which the forming jig includes an opposing surface facing the electrode assembly, and the opposing surface has a depression depth of the opposing surface that is recessed in a direction opposite to the pressing direction.

Description

Technical Field

[0001] The present disclosure relates to an electrode assembly joint forming apparatus.

[0002] This application is based upon and claims the benefit of priority from Korean Patent Application No. 10-2023-0115853 filed on August 31, 2023, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Background Art

[0003] Secondary batteries, which have high applicability depending on the product group and electrical characteristics such as high energy density, are generally used not only in portable devices but also in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by power supplies. Such secondary batteries are attracting attention as a new energy source that improves eco-friendliness and energy efficiency because they not only have the major advantage of significantly reducing the use of fossil fuels but also do not generate byproducts from the use of energy.

[0004] Currently, widely used secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc. The operating voltage of a unit secondary battery cell (i.e., a unit battery cell) is about 2.5V to 4.5V. Therefore, if a higher output voltage is required, a plurality of battery cells can be connected in series to form a battery pack. In addition, depending on the required charge and discharge capacity of the battery pack, a plurality of battery cells can be connected in parallel to form a battery pack. Therefore, the number of battery cells included in the battery pack can be set differently according to the required output voltage and / or the required charge and discharge capacity.

[0005] Furthermore, conventional cylindrical secondary batteries typically have a structure in which the tabs connecting the winding core and external terminals are welded to the core's foil. However, cylindrical secondary batteries with this structure have limited current paths, and the core itself inevitably has very high resistance. Furthermore, attempts have been made to reduce resistance by increasing the number of tabs connecting the winding core and external terminals, but simply increasing the number of tabs has limitations in reducing resistance to the desired level while ensuring sufficient current paths.

[0006] As the current applied to secondary batteries increases, in order to reduce resistance, a new core structure is being developed in which the uncoated portion exposed to the axial end of the core is connected to the current collecting plate by welding or the like in a state where the uncoated portion is flattened by radially bending the uncoated portion.

[0007] In order to manufacture an electrode assembly having such a structure, a processing step is required to expose uncoated portions at both ends of the electrode assembly in the axial direction and bend the electrode assembly in the radial direction. This bending step is generally performed using a forming jig.

[0008] In the past, an iris shutter type clamp was used to perform the first processing of gathering the ends of the uncoated portion extending straight in the axial direction into a radially inclined shape, then a clamp rotating around a rotation axis corresponding to the axis of the electrode assembly was used to perform the second processing of gathering and pressing the slightly radially inclined uncoated portion, and finally a flat clamp was used to perform the third processing of pressing the inclined electrode as flat as possible.

[0009] Here, if the second processing is performed without performing the first processing of gathering the ends of the uncoated portion so as to tilt radially, the buckling phenomenon in which the uncoated portion collapses cannot be avoided. Therefore, the first processing of gathering the ends of the uncoated portion radially must be performed first.

[0010] Furthermore, even when performing the second process, if the uncoated portion is pressed without rotating the jig, the friction between the jig and the end of the uncoated portion causes the uncoated portion to buckle, causing it to collapse. Therefore, even when performing the second process, the uncoated portion must be pressed while rotating the jig.

[0011] In this manner, the bending forming process for the uncoated portion of the conventional jellyroll type electrode assembly has many steps, and equipment required in each step must have a complicated structure.

[0012] This multi-step process and complex processing equipment limit the ability to shorten the processing cycle and reduce the size of the equipment.

[0013] In addition, in order to solve these problems, a joint forming device has been developed in the past. This joint forming device can reduce the number of processing steps for flattening the uncoated portion by radially bending the uncoated portion exposed at the axial end of the electrode assembly, and can simplify the processing method of each processing step. However, even this forming device does not take into account the overlap amount of the uncoated portion, which leads to the buckling phenomenon of the uncoated portion. In the case of buckling of the uncoated portion as described above, the possibility of internal short circuit of the battery and escalation into a thermal event cannot be ruled out. Summary of the Invention

[0014] Technical issues

[0015] Therefore, the present disclosure aims to effectively prevent the internal short circuit of a battery.

[0016] In another aspect, the present disclosure is also directed to preventing a buckling phenomenon of an uncoated portion by providing a jig that considers an overlap amount of the uncoated portion of an electrode assembly.

[0017] However, the technical problems to be solved by the present disclosure are not limited to the above problems, and a person skilled in the art can clearly understand other problems not mentioned herein through the following description of the present disclosure.

[0018] A technical solution for solving the above-mentioned problem is a forming device according to one embodiment of the present disclosure, which is a forming device for a radially bent electrode joint, wherein the electrode joint is exposed by the first electrode of the electrode assembly extending farther to the axial end than the diaphragm, in which the first electrode, the diaphragm and the second electrode are stacked and wound around the central axis, wherein the forming device includes a forming fixture for bending the electrode joint, the forming fixture includes a relative surface facing the electrode assembly, and the relative surface has a recessed depth of the relative surface in a direction opposite to the pressing direction.

[0019] For example, the opposing surface may have a shape curved in a direction opposite to the pressing direction.

[0020] According to one aspect of the present disclosure, a recessed depth of the opposing surface recessed in a direction opposite to the pressing direction may be configured to increase toward the central axis.

[0021] According to another aspect of the present disclosure, a recessed depth of the opposing surface recessed in a direction opposite to the pressing direction may be configured to increase from a center side toward an outer peripheral side and then decrease.

[0022] According to still another aspect of the present disclosure, the recessed depth of the opposing surface recessed in the direction opposite to the pressing direction may be configured to increase from the center side toward the outer peripheral side, then maintain a certain length, and then decrease.

[0023] Preferably, the recessed depth of the opposing surface recessed in the direction opposite to the pressing direction may be configured to linearly increase from the center side toward the outer peripheral side, then maintain a certain length, and then linearly decrease.

[0024] According to one aspect of the present disclosure, at least a portion of an electrode tap of an electrode assembly may be divided into a plurality of independently bendable segments.

[0025] Here, in the electrode assembly, the curved surface area of the curved electrode assembly includes a uniform stacking number interval and a stacking number reduction interval along the radial direction, in which the stacking number uniform interval is equal to or greater than a predetermined stacking number, the stacking number reduction interval is positioned adjacent to the stacking number uniform interval, and in the stacking number reduction interval, the stacking number of the segment decreases as it moves away from the stacking number uniform interval.

[0026] Preferably, in the electrode assembly, a curved surface region of the curved electrode assembly may include a stacking number increasing section in which the stacking number of the segments increases along the radial direction.

[0027] According to another aspect of the present disclosure, the recess depth may be configured to be greater than the stack thickness of the segment.

[0028] According to yet another aspect of the present disclosure, the recess depth may be configured to be equal to the stacking thickness of the segment.

[0029] According to one aspect of the present disclosure, the recess depth may be configured to be 100 um to 875 um.

[0030] According to another aspect of the present disclosure, the recess depth may be configured to be 50 um to 700 um.

[0031] According to yet another aspect of the present disclosure, the forming jig may be configured to include a steel material.

[0032] Beneficial effects

[0033] The present invention can effectively prevent the internal short circuit of the battery.

[0034] On the other hand, according to the present disclosure, by providing a jig considering the overlap amount of the uncoated portion of the electrode assembly, the buckling phenomenon of the uncoated portion may be effectively prevented.

[0035] However, effects obtained by the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned herein can be clearly understood by those having ordinary skill in the art from the following description of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, serve to provide further understanding of the technical features of the present disclosure, and therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0037] Figure 1 is a plan view of a first embodiment of a first electrode having an uncoated portion and a coated portion.

[0038] Figure 2 It is a side view showing a stacked state of electrodes and separators to be wound into a jelly jelly-type electrode assembly.

[0039] Figure 3 This is a front view showing the process of radially bending the electrode portions exposed at both ends of the electrode assembly in the axial direction as electrode tabs and laminating the current collecting plates thereon.

[0040] Figure 4 is a plan view of a second embodiment of a first electrode having an uncoated portion and a coated portion.

[0041] Figure 5 It shows that the application Figure 4 Front view of the jelly jelly electrode assembly.

[0042] Figure 6is a graph showing a result of counting the number of stacking segments along a radial direction in a curved surface region formed in an upper portion of an electrode assembly according to an embodiment of the present disclosure.

[0043] Figure 7 is a diagram showing a bending result of an electrode assembly to which a conventional flat jig is applied.

[0044] Figure 8 is a plan view of an electrode assembly and a forming jig of a forming apparatus for bending an electrode tab provided at an axial end of the electrode assembly according to an embodiment of the present disclosure.

[0045] Figure 9 yes Figure 8 A cross-sectional view of the formed fixture.

[0046] Figure 10 FIG. 1 is a diagram for explaining a forming jig according to another embodiment of the present disclosure.

[0047] Figure 11 is a schematic diagram illustrating a cross section of a curved surface area formed when a segment is bent toward the core side of the electrode assembly. DETAILED DESCRIPTION

[0048] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as being limited to general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms for the best interpretation.

[0049] Therefore, the embodiments described in this specification and the configurations shown in the drawings are only some of the most preferred embodiments of the present disclosure and are not intended to fully represent the technical aspects of the present disclosure. Therefore, it should be understood that various equivalents and modifications may be made thereto when this application is filed.

[0050] Additionally, to help understand the present disclosure, the drawings are not shown to scale, but the sizes of some components may be exaggerated.

[0051] Figure 1 is a plan view of a first embodiment of a first electrode having an uncoated portion and a coated portion.

[0052] Figure 2 1 is a side view showing a stacked state of electrodes and separators 16 to be wound into a jelly jelly-type electrode assembly 10 .

[0053] Figure 3 This is a front view showing the process of radially bending the electrode portions exposed at both ends of the electrode assembly 10 as electrode tabs 11 and laminating current collecting plates thereon.

[0054] Figure 4 is a plan view of a second embodiment of a first electrode having an uncoated portion and a coated portion.

[0055] Figure 5 It shows that the application Figure 4 A front view of a jelly jelly granule electrode assembly 10 having an electrode.

[0056] In the following, reference will be made to Figures 1 to 5 An embodiment of the electrode assembly 10 in which the forming apparatus according to the present disclosure can be used is described. However, the forming apparatus of the present disclosure is not necessarily applicable only to the electrode assembly 10 having the structure described later.

[0057] The electrode assembly 10 to which the forming device of the present disclosure is applied is formed by stacking a first electrode 15, a separator 16, and a second electrode 17 in the form of a sheet having a predetermined width in the width direction Y and extending longer 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 the form of coating an active material on a metal foil. The first electrode 15 and / or the second electrode 17 include a coating portion on the metal foil on which the active material is coated and an uncoated portion on which the active material is not coated, exposing the surface of the metal foil. At one end of the first electrode 15 in the width direction Y (that is, the axial direction Y), there is a first electrode tap 11 region which is an uncoated portion on which the active material is not coated. And (or) at the other end of the second electrode 17 in the width direction Y (that is, the axial direction Y), there is a second electrode tap 12 region which is an uncoated portion on which the active material is not coated. The electrode tap 11 can be electrically connected to the electrode terminal provided in the battery can (not shown) in which the electrode assembly 10 will be housed through a current collecting plate.

[0059] When the first electrode 15, the separator 16, the second electrode 17, and the separator 16 are stacked to wind the electrode assembly 10 in a core form, the first electrode tab 11 and the second electrode tab 12 are stacked so that each of them is further exposed (protrudes) in the width direction Y of the separator 16, that is, exposed (protrudes) toward one end and the other end, respectively, in the axial direction Y. And, the electrode assembly 10 can be manufactured by winding the stacked body formed in this manner along the X-axis direction around the Y-axis.

[0060] The electrode assembly 10 applied to the present disclosure may be a wound core 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 coated on one or both surfaces of the first electrode current collector. An uncoated portion of the first electrode current collector, not coated with the first electrode active material, exists at one end in the width direction Y of the first electrode current collector. The uncoated portion serves as the first electrode tab 11. The first electrode tab 11 is disposed at 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 coated on one or both surfaces of the second electrode current collector. At the other end of the second electrode current collector in the width direction Y, there is an uncoated portion that is not coated with the second electrode active material. The uncoated portion serves as a second electrode tab 12. The second electrode tab 12 is disposed at the lower portion of the electrode assembly 10 in the height direction.

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

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

[0065] In one example, the positive electrode active material may include a x M y ]O 2+z (wherein 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; and the stoichiometric coefficients x, y and z are selected so that the compound remains electrically neutral).

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

[0067] In another example, the positive electrode active material may be a material having the chemical formula Li a M 1 x Fe 1xM 2 y P 1y M 3 z O 4z (where M 1 comprises at least one element selected from Ti, Si, Mn, Co, Fe, V, Cr, Mo, Ni, Nd, Al, Mg, and Al; M 2 comprises 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 comprises halogen elements optionally including F; 0 < a ≤ 2, 0 ≤ x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1; and the stoichiometric coefficients a, x, y, and z are selected such that the compound remains electrically neutral) or Li3M2(PO4)3 (where M comprises at least one element selected from Ti, Si, Mn, Fe, Co, V, Cr, Mo, Ni, Al, Mg, and Al) represents a lithium metal phosphate.

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

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

[0070] The separator 16 can use a porous polymer membrane alone or in a laminated manner. For example, a porous polymer membrane made of a polyolefin polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, ethylene / methacrylate copolymer, etc. As another example, the separator 16 can use a conventional porous non-woven fabric, for example, a non-woven 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. The separator 16 itself may also 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 an adhesive such that there is an interstitial volume between adjacent particles.

[0072] The inorganic particles may be made of an inorganic material having a dielectric constant of 5 or higher. Non-limiting examples of the inorganic particles may include those selected from Pb(Zr,Ti)O3 (PZT), Pb 1x La x Zr 1y Tiy O3(PLZT), PB(Mg3Nb 2 / 3 )At least one material from the group consisting of O3-PbTiO3 (PMN-PT), BaTiO3, hafnium dioxide (HfO2), SrTiO3, TiO2, Al2O3, ZrO2, SnO2, CeO2, MgO, CaO, ZnO and Y2O3.

[0073] The current collecting plates 21 and 22 may be electrically connected to the first electrode tab 11 and the second electrode tab 12, respectively. Figure 3 As shown in the figure, the first current collecting plate 21 and the second current collecting plate 22 are connected by welding or the like in a radially bent state.

[0074] The forming apparatus disclosed herein is a processing apparatus for radially bending the first electrode tab 11 and the second electrode tab 12 .

[0075] The shapes of the first electrode tab 11 and the second electrode tab 12 to which the forming device can be applied are not limited to the above-described structures. Figure 1 The illustrated first electrode tab 11 has a shape in which the first electrode tab 11 extends continuously along the winding direction (length direction) X. However, the first electrode tab 11 may also have a shape in which the first electrode tab 11 extends discontinuously along the winding direction (length direction) X.

[0076] Reference Figure 4 The first electrode tab 11 provided on the first electrode 15 may have a shape cut at predetermined intervals along the longitudinal direction in the axial direction (height direction) Y. Through the cutting line, the first electrode tab 11 may have a shape having a plurality of segments 111 arranged along the longitudinal direction.

[0077] The shape of the segments 111 formed by the cutting lines can be an isosceles trapezoid or a rectangle as shown in the figure, and can also have various other shapes such as a semicircle or a semi-ellipse. In addition, the segments 111 of these various shapes can be used together, and the width and height of the segments 111, the intervals between the segments 111, etc. can be constant or can be changed under a predetermined rule.

[0078] In addition, if Figure 4 As shown, a bottom line BL may be defined as an imaginary line connecting the bottoms of the segments 111. The bottom line BL may be, for example, a straight line or a curved line.

[0079] In addition, if Figure 4 and Figure 5As shown, the segment 111 can be omitted in the predetermined interval B1 near the core. In the interval B2 where the segment 111 is provided, the segment 111 has a height that increases gradually or stepwise from the core toward the periphery in the axial direction. Although not shown, the segment 111 can be deleted in the last interval B3 for the convenience of processing. Alternatively, in another embodiment, Figure 4 and Figure 5 Differently, in the section B2 where the segments 111 are provided, the segments 111 may have a form protruding in the axial direction with the same height.

[0080] If the electrode tab 11 is formed in the form of a segment 111 as described above, when the electrode tab 11 can be bent in the radial direction, the lower end of the segment 111 can be bent. Figure 4 The bottom line BL is shown to be curved. Alternatively, the segment 111 may be curved at a Figure 4 The bottom line BL is shown to be curved at a high position.

[0081] Figure 6 is a graph showing a result of counting the number of stacking segments along a radial direction in a curved surface region formed at an upper portion of the electrode assembly 10 according to an embodiment of the present disclosure, Figure 7 is a diagram showing a bending result of the electrode assembly 10 to which a conventional flat jig is applied.

[0082] Reference Figure 6 , showing a segmented uniform stacking number interval b1. The uniform stacking number interval b1 is the radius interval of the flat area in each figure. Outside the uniform stacking number interval b1, a stacking number reduction interval b2 is shown, in which the stacking number of the segment decreases as the radius increases. The stacking number reduction interval b2 is a radius interval in which the stacking number of the segment decreases as the radius of the electrode assembly 10 increases. The uniform stacking number interval b1 and the stacking number reduction interval b2 are adjacent in the radial direction. On the other hand, inside the uniform stacking number interval b1, a stacking number increase interval b3 is shown, in which the stacking number of the segment increases as the radius increases. The stacking number increase interval b3 is a radius interval in which the stacking number of the segment increases as the radius of the electrode assembly 10 increases. As described above, the reason for the change in the stacking number in the electrode assembly 10 is due to the height of the segment, the starting position of the segment, the ending position of the segment, etc. Therefore, according to the stacking number of the segment, the axial height of the curved surface area of the electrode assembly 10 can vary in the radial direction.

[0083] In addition, the conventional flat jig is configured as a jig having a flat shape on a surface facing the electrode tab 11. Since the conventional flat jig has a flat shape regardless of the overlap thickness, the electrode assembly 10 is pressed into a flat shape.

[0084] Therefore, if Figure 7 As shown, multiple electrode tabs 11 are bent. In this case, the possibility of the bent electrode tab 11 contacting an adjacent electrode tab 11 with the opposite electrode increases. Therefore, the possibility of an internal short circuit in the battery increases, and the possibility of it eventually escalating into a thermal event increases.

[0085] The present disclosure is invented to solve these problems, and the following will refer to Figures 8 to 11 The present disclosure is described in detail.

[0086] Figure 8 is a plan view of an electrode assembly 10 and a forming jig 100 of a forming apparatus for bending an electrode tab 11 provided at an axial end of the electrode assembly 10 according to an embodiment of the present disclosure.

[0087] Reference Figure 8 and Figure 9 , the forming apparatus can be configured to radially bend the electrode joint 11, which is exposed by the first electrode in the electrode assembly 10 extending further to the axial end than the separator 16, in which the first electrode, the separator 16 and the second electrode are stacked and wound around the central axis.

[0088] The forming jig 100 and the flattening jig 50 may be made of steel. The forming jig 100 can bend the electrode tab 11 , which extends straight in the axial direction and is arranged in a spiral shape, radially inward without buckling.

[0089] More specifically, the forming device may include a forming jig 100 for bending the electrode tab 11. The forming jig 100 may include an opposing 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 opposing surface S may be configured to have a concave depth in which the opposing surface S is concave in a direction opposite to the pressing direction D.

[0090] According to such a structure, the electrode tab 11 can be bent while taking into account the overlapping thickness of the electrode tab 11, which may be different at each bending position of the electrode tab 11. That is, even if there is a region where the overlapping thickness of the electrode tab 11 is thick, the recessed depth of the opposing surface S can be set to a predetermined depth, thereby preventing the electrode tab 11 from buckling.

[0091] Figure 9 yes Figure 8 A cross-sectional view of the formed jig 100 is shown.

[0092] 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. Figure 9 As in the embodiment, the depth of the depression of the opposing surface S in the direction opposite to the pressing direction D may increase toward the central axis.

[0093] In another embodiment, the opposing surface S may also be configured to have a substantially parabolic shape. That is, the opposing surface S may be configured to have the deepest concave depth at the central axis and decrease in depth toward the periphery.

[0094] This structure allows bending to be performed while taking into account the contour of the reduced-stack region b2. Specifically, since the shape of the opposing surface S is configured to correspond to the contour of the reduced-stack region b2 located on the outer periphery of the electrode assembly 10, buckling of the electrode tab 11 located in the reduced-stack region b2 can be prevented. Furthermore, the monotonous shape of the fixture can be advantageous in fixture manufacturing.

[0095] Figure 10 1 is a diagram for describing a forming jig 100 according to another embodiment of the present disclosure.

[0096] In another embodiment of the present disclosure, the recessed depth of the opposing surface S recessed in the direction opposite to the pressing direction D may be configured to increase from the center side toward the outer peripheral side and then decrease.

[0097] For example, refer to Figure 10 , the depth of the opposing surface S is configured to increase from the center side toward the outer peripheral side and then decrease.

[0098] With this structure, bending can be performed while taking into account the contours of the stacking number reduction section b2 and the stacking number increase section b3. In other words, because the shape of the opposing surface S is configured to correspond to the contours of the stacking number reduction section b2 located on the outer periphery of the electrode assembly 10 and the contours of the stacking number increase section b3 located on the central side of the electrode assembly 10, respectively, buckling of the electrode tab 11 in the stacking number reduction section b2 and the stacking number increase section b3 can be effectively prevented.

[0099] In still another embodiment of the present disclosure, the recessed depth of the opposing surface S recessed in the direction opposite to the pressing direction D may be configured to be constant, then increase from the center side toward the outer peripheral side, and then decrease.

[0100] For example, with Figure 10Differently, the recessed depth of the opposing surface S may be configured to increase from the center side toward the outer peripheral side starting from the point where the electrode tab 11 is started to be formed, and then decrease.

[0101] This structure allows for bending to be performed with more accurate consideration of the contours of the interval b2 where the number of stacked layers decreases and the interval b3 where the number of stacked layers increases. Specifically, because the shape of the opposing surface S is configured to correspond to the contours of the interval b2 where the number of stacked layers decreases, located on the outer periphery of the electrode assembly 10, and the interval b3 where the number of stacked layers increases, located on the central side of the electrode assembly 10, respectively, buckling of the electrode tab 11 in the interval b2 where the number of stacked layers decreases and the interval b3 where the number of stacked layers increases can be effectively prevented.

[0102] In still another embodiment of the present disclosure, the recessed depth of the opposing surface S recessed in the direction opposite to the pressing direction D may be configured to increase from the center side toward the outer peripheral side, then maintain a certain length, and then decrease.

[0103] For example, refer again to Figure 6 From the center side toward the outer peripheral side, the stacking number increasing section b3, the stacking number uniform section b1 and the stacking number decreasing section b2 appear in sequence.

[0104] Therefore, according to this embodiment, bending can be performed while comprehensively considering the contours of the increasing stacking number section b3, the uniform stacking number section b1, and the decreasing stacking number section b2. That is, because the shape of the opposing surface S is configured to correspond to the contours of the decreasing stacking number section b2 located on the outer periphery of the electrode assembly 10, the contour of the increasing stacking number section b3 located on the central side of the electrode assembly 10, and the contour of the uniform stacking number section b1 located between the decreasing stacking number section b2 and the increasing stacking number section b3, buckling of the electrode tab 11 in the increasing stacking number section b3, the uniform stacking number section b1, and the decreasing stacking number section b2 can be effectively prevented. Furthermore, because the electrode tab 11 bends only by an amount corresponding to the thickness of the stacked layers at all radial positions, the electrode tabs 11 can be reliably in contact with each other without buckling.

[0105] More preferably, the recessed depth of the opposing surface S recessed in the direction opposite to the pressing direction D may be configured to linearly increase from the center side toward the outer peripheral side, then maintain a certain length, and then linearly decrease.

[0106] For example, Figure 6As shown, the number of stacked electrode tabs 11 can be increased and decreased linearly. Therefore, according to the structure configured so that the depth of the recess of the opposing surface S increases linearly from the center side toward the outer peripheral side, then maintains a certain length, and then decreases linearly, it is possible to achieve a result in which the electrode tabs 11 are reliably in contact with each other without buckling, especially at all radial positions.

[0107] Furthermore, as described above, the distribution of the number of stacked layers of the electrode tab 11 can 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 layers of the electrode tab 11 can increase and / or decrease in a curved shape. When the distribution of the number of stacked layers differs from that described above, the corresponding jig shape can obviously be changed.

[0108] In addition, at least a portion of the electrode tab 11 of the electrode assembly 10 may be divided into a plurality of independently bendable segments.

[0109] For example, refer again to Figure 4 At least a portion of the electrode connector 11 of the electrode assembly 10 may be divided into a plurality of independently bendable segments, and the curved surface area of the curved electrode assembly 10 may include a uniform stacking number interval b1 and a stacking number reduction interval b2 along the radial direction. In the uniform stacking number interval b1, the stacking number of the segments is equal to or greater than a predetermined stacking number, and the stacking number reduction interval b2 is located adjacent to the uniform stacking number interval b1. In the stacking number reduction interval b2, the stacking number of the segments decreases as they move away from the uniform stacking number interval b1. In addition, the curved surface area of the curved electrode assembly 10 may include a stacking number increasing interval b3, in which the stacking number of the segments increases along the radial direction.

[0110] In one aspect of the present disclosure, the recess depth may be configured to be greater than the stacking thickness of the segments. If the recess depth is configured to be less than the stacking thickness of the segments, the electrode tab 11 may be over-pressed by the forming jig 100 and thus buckling of the electrode tab 11 may be unavoidable.

[0111] Therefore, according to the above-described structure of the present disclosure, the recess depth is configured to be greater than the stacking thickness of the segments, so that excessive pressing and buckling of the electrode tab 11 can be effectively prevented.

[0112] In another aspect of the present disclosure, the recess depth can be configured to be equal to the stacking thickness of the segments. According to this structure, the recess depth is configured to be greater than the stacking thickness of the segments, so that excessive compression and buckling of the electrode tabs 11 can be effectively prevented. At the same time, the electrode tabs 11 can reliably contact and overlap each other without buckling.

[0113] In one aspect of the present disclosure, the recess depth may be determined as follows:

[0114] Depth of depression ≤ foil thickness * maximum number of foil layers

[0115] That is, the recess depth may be less than or equal to the maximum laminate thickness of the foil at a specific point in the radial direction.

[0116] Specifically, the electrode may be the first electrode 15. At this time, the thickness of the positive electrode current collector (foil) constituting the first electrode 15 may be 10 μm to 25 μm. Therefore, the curved surface area F of the positive electrode may include an area where the total stack thickness of the segment is 100 μm to 875 μm.

[0117] In one aspect of the present disclosure, the recess depth can be configured to be between 100 μm and 875 μm. For example, when electrode tab 11 is a positive electrode tab, the total stack thickness of the segment can be between 100 μm and 875 μm. Therefore, when the recess depth is such that the total stack thickness of the segment is between 100 μm and 875 μm, unnecessary buckling and short circuiting can be prevented.

[0118] In addition, the electrode may be the second electrode 17. In this case, the thickness of the negative electrode current collector (foil) constituting the second electrode 17 may be 5 to 20 μm. Therefore, the curved surface area F of the negative electrode may include an area where the total stacked thickness of the segment is 50 to 700 μm.

[0119] In another aspect of the present disclosure, the recess depth can be configured to be between 50 μm and 700 μm. For example, when electrode tab 11 is a negative electrode tab, the total stack thickness of the segment can be between 50 μm and 700 μm. Therefore, when the recess depth is such that the total stack thickness of the segment is between 50 μm and 700 μm, unnecessary buckling and short circuiting can be prevented.

[0120] Figure 11 is a schematic diagram illustrating a cross section of a curved surface area formed when a segment is bent toward the core side of the electrode assembly 10 .

[0121] Reference Figure 11 , the curved surface region F has a structure in which segments 111 overlap 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-omitted section without segments (first section B1), and sections ② and ③ are sections in which the winding turns containing segments 111 are located (second section B2). More specifically, section ② is a uniform height section in which the height of the segments remains consistent, and section ③ is a variable height section in which the height of the segments 111 is variable. Here, the radial lengths of sections ② and ③ may vary depending on the embodiment.

[0122] As mentioned above, application Figures 8 to 10 The result of the forming device pressing the electrode tab 11 of the electrode assembly 10 is as follows Figure 11 As shown, it is possible to achieve reliable contact and overlap of the electrode tabs 11 with each other while maintaining the electrode stack thickness distribution without buckling.

[0123] That is, according to various embodiments as described above, the present disclosure can effectively prevent internal short circuits in batteries. In addition, according to the present disclosure, a jig can be provided that takes into account the overlap amount of the uncoated portion of the electrode assembly 10, thereby effectively preventing the buckling phenomenon of the uncoated portion.

[0124] Furthermore, terms indicating directions such as upper and lower as used herein are only used for convenience of description, and it is obvious to those skilled in the art that the terms may be changed according to the position of the elements or observers.

[0125] The present disclosure has been described above with respect to a limited number of embodiments and drawings, but the present disclosure is not limited thereto, and various modifications and variations will be possible to those skilled in the art to which the present disclosure pertains within the technical aspects of the present disclosure and the scope of the appended claims and their equivalents.

[0126] [Explanation of Reference Numerals]

[0127] 10: Electrode assembly

[0128] r: radius

[0129] 11: Electrode connector (first electrode connector)

[0130] 111: Segment

[0131] 12: Electrode connector (second electrode connector)

[0132] 15: First electrode

[0133] 151: First electrode active material

[0134] 16: Diaphragm

[0135] 17: Second electrode

[0136] H1: Winding hole (hollow part)

[0137] X: length direction, circumferential direction, winding direction

[0138] Y: width direction, winding axis, axial direction, center axis, height direction

[0139] Z: radial direction, normal direction

[0140] 21: Collector plate (first collector plate)

[0141] 22: Collector plate (second collector plate)

[0142] 100: Forming a fixture

[0143] S: relative surface

[0144] D: Pressing direction

Claims

1. A forming apparatus for a radially curved electrode tab, wherein the electrode tab is exposed by a first electrode of an electrode assembly extending further toward an axial end than a separator, wherein the first electrode, the separator, and the second electrode are stacked and wound around a central axis, in, The forming device includes a forming jig for bending the electrode tab, the forming jig including an opposing surface facing the electrode assembly, and the opposing surface has a concave depth of the opposing surface concave in a direction opposite to a pressing direction.

2. The forming device according to claim 1, in, The opposing surface has a shape curved in a direction opposite to the pressing direction.

3. The forming device according to claim 1, in, The recessed depth of the opposing surface, which is recessed in a direction opposite to the pressing direction, increases toward the central axis.

4. The forming device according to claim 1, in, The recessed depth of the opposing surface, which is recessed in a direction opposite to the pressing direction, increases from a center side toward an outer peripheral side and then decreases.

5. The forming device according to claim 1, in, The recessed depth of the opposing surface, which is recessed in the direction opposite to the pressing direction, increases from a center side toward an outer peripheral side, then maintains a certain length, and then decreases.

6. The forming device according to claim 1, in, The recessed depth of the opposing surface, which is recessed in the direction opposite to the pressing direction, increases linearly from a center side toward an outer peripheral side, then maintains a certain length, and then decreases linearly.

7. The forming device according to claim 1, in, At least a portion of the electrode connector of the electrode assembly is divided into a plurality of independently bendable segments, and The curved surface area of the curved electrode assembly includes a uniform stacking number interval and a stacking number reduction interval along the radial direction, wherein in the uniform stacking number interval, the stacking number of the segment is equal to or greater than the predetermined stacking number, and the stacking number reduction interval is positioned adjacent to the uniform stacking number interval, and in the stacking number reduction interval, the stacking number of the segment decreases as it moves away from the uniform stacking number interval.

8. The forming device according to claim 7, in, In the electrode assembly, the curved surface region of the curved electrode assembly includes a stacking number increasing section in which the stacking number of the segments increases along the radial direction.

9. The forming device according to claim 7, in, The recess depth is greater than the stacking thickness of the segments.

10. The forming device according to claim 7, in, The recess depth is equal to the stacking thickness of the segments.

11. The forming device according to claim 1, in, The depth of the recess is 100 μm to 875 μm.

12. The forming device according to claim 1, in, The depth of the recess is 50 μm to 700 μm.

13. The forming device according to claim 1, in, The forming jig includes a steel material.

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