Current collector plate and battery cell

Abstract

Disclosed are a current collector plate and a battery cell. A current collector plate according to the present invention may comprise: an electrode bonding part having an inner surface bonded to an electrode tab of an electrode assembly; a terminal bonding part disposed inside the electrode bonding part in the radial direction and having an outer surface bonded to the bottom surface of a can housing; and a height adjusting part disposed between the electrode bonding part and the terminal bonding part, configured to electrically connect the electrode bonding part and the terminal bonding part, and configured to adjust the bonding height of the terminal bonding part as same is deformed by an external force.

Description

collector plates and battery cells

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0074366, dated June 7, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a current collector and a battery cell capable of preventing leakage current during resistance welding, ensuring weldability, and performing resistance welding without installing an insulator between an electrode assembly and a bottom member of a can housing.

[0003] Typically, a cylindrical battery cell comprises a can housing and an electrode assembly. The can housing is manufactured by deep-drawing a metal sheet to form a circular bottom portion and a circular, tubular sidewall member connected to the bottom portion. The electrode assembly is housed within the can housing, and the open end of the can housing is sealed by covering it with a cap assembly.

[0004] Figure 1 is a cross-sectional view schematically illustrating a state in which an electrode assembly is inserted into the inside of a can housing in a conventional battery cell.

[0005] Referring to Fig. 1, before accommodating the electrode assembly (20) in the can housing, a current collector plate (30) may be joined to the axial lower portion of the electrode assembly (20). When inserting the electrode assembly (20) into the can housing (10), the current collector plate (30) faces the bottom surface (12) of the can housing (10).

[0006] However, since the central portion of the current collector (30) is blocked, it blocks the hollow portion (29) of the electrode assembly (20). Accordingly, when the electrode assembly (20) is accommodated in the can (10), the current collector (30) prevents air inside the can (10) from being discharged to the outside through the hollow portion (29) of the electrode assembly (20). This phenomenon interferes with the process of inserting the electrode assembly (20) into the can (10).

[0007] Meanwhile, a circular ring-shaped insulator (19) is installed to resistance weld the center portion of the current collector plate (30) and the center portion of the can bottom (12). The insulator (19) is interposed between the can bottom (12) and the current collector plate (30). Since the insulator (19) is formed in the form of a flat plate with a certain thickness, and the current collector plate (30) is also formed in the form of a flat plate, in order to make the current collector plate (30) adhere to the can bottom (12), the current collector plate (30) must be strongly pressed and deformed with a welding electrode.

[0008] During this process, the current collector plate (30) is excessively deformed, and the welded area is pre-tensioned, making it unstable. Furthermore, vibrations or shocks generated during the use of the battery cell may affect the welded area, potentially causing the welded area to fall off or cracks to form in the current collector plate (30). This is because repeated and continuous tension and stress can cause fatigue failure. If this occurs, the electrical connection may be damaged, potentially leading to a loss of function in the battery cell.

[0009] In addition, a ring-shaped insulator (19) may be interposed between the electrode assembly (20) and the can bottom (12) to insulate a portion other than the welding area, thereby preventing leakage current and concentrating the current. When the insulator (19) is installed on the can bottom (12), the height of the electrode assembly (20) is lowered by the thickness of the insulator (19). As the height of the electrode assembly (20) is lowered, the battery capacity may be reduced. In addition, in order to achieve a higher energy density, a technology capable of resistance welding without installing the insulator (19) between the electrode assembly (20) and the can bottom (12) is required.

[0010] The present invention has been devised to solve the above-described problems, and aims to provide a current collector and battery cell capable of preventing leakage current and ensuring weldability.

[0011] The present invention aims to provide a current collector and a battery cell capable of resistance welding a terminal joint and a can housing without installing an insulator between the can housing and the electrode joint.

[0012] The present invention aims to provide a current collector plate and a battery cell capable of manufacturing an electrode assembly with a higher height.

[0013] The present invention aims to provide a current collector plate and a battery cell that do not require strong pressure to press the terminal joint to make the terminal joint close to the bottom member.

[0014] The present invention aims to provide a current collector plate and a battery cell in which a welding portion may not be pre-tensioned after a terminal joint is welded.

[0015] The technical objectives of the present invention are not limited to the aforementioned purposes. Other unmentioned objectives and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0016] In order to solve the above-described problem, a current collector plate according to the present invention may include: an electrode joint portion whose inner surface is joined to an electrode tab of an electrode assembly; a terminal joint portion which is arranged radially inside the electrode joint portion and whose outer surface is joined to a bottom surface of a can housing; and a height adjusting portion which is arranged between the electrode joint portion and the terminal joint portion, electrically connects the electrode joint portion and the terminal joint portion, and adjusts a joining height of the terminal joint portion as it is deformed by an external force.

[0017] The height adjustment unit may include a plurality of through-hole portions arranged on the outside of the terminal joint portion to surround the terminal joint portion; and a plurality of plastic deformation portions arranged between the plurality of through-hole portions, connected to the terminal joint portion and the electrode joint portion, arranged along the circumferential direction of the terminal joint portion, and deformed as the height of the terminal joint portion increases.

[0018] The above plastic deformation portion and the through hole portion may be alternately arranged along the circumferential direction of the terminal joint portion.

[0019] The above plastic deformation portion can be formed in an arc shape with a certain radius from the center of the terminal joint portion.

[0020] The above plastic deformation portion may include an outer inclined portion extending upwardly in a radially inner direction from the electrode joint portion; and an inner inclined portion extending upwardly in a radially outer direction from the terminal joint portion and connected to an end of the outer inclined portion.

[0021] The inclination angle of the inner slope can be formed within a range of 45° from an imaginary vertical line at the end of the outer slope.

[0022] The inclination angle of the outer slope can be formed within a range of 45° from an imaginary vertical line at the end of the inner slope.

[0023] The above plastic deformation portion may include an outer inclined portion extending upwardly in a radially inner direction from the electrode joint portion; and an inner inclined portion extending upwardly in a radially outer direction from the terminal joint portion, connected to an end of the outer inclined portion, and formed in a zigzag shape along the radial direction.

[0024] The above inner slope may be formed to slope upward from the radially outer side of the terminal joint.

[0025] The above plastic deformation portion may include an outer inclined portion extending downwardly in a radially inner direction from the electrode joint portion; and an inner inclined portion extending downwardly in a radially outer direction from the terminal joint portion and connected to an end of the outer inclined portion.

[0026] The above plastic deformation portion may include an outer inclined portion extending downwardly in a radially inner direction from the electrode joint portion; and an inner inclined portion extending downwardly in a radially outer direction from the terminal joint portion, connected to an end of the outer inclined portion, and formed in a zigzag shape along the radial direction.

[0027] The above inner slope may be formed to slope downward from the radially outer side of the terminal joint.

[0028] The terminal joint may include a joint panel portion connected to the height adjustment portion and formed flat; and a joint protrusion portion having a plurality of joint protrusions formed to protrude from the joint panel portion.

[0029] The above-mentioned joint projection may include a joint tip of a closed form.

[0030] The above-mentioned joint projection may include an open-shaped joint hole.

[0031] The height of the plastic deformation portion of the height adjustment portion may be formed higher than the height of the joint protrusion portion.

[0032] A battery cell according to the present invention may include: a can housing having a bottom member and a side wall member; an electrode assembly accommodated in the can housing; and a current collector plate welded to the bottom member of the can housing while the electrode assembly is accommodated in the can housing.

[0033] The above can housing can be formed in a cylindrical shape.

[0034] According to the present invention, since the terminal joint is adjusted in height to be spaced apart from the bottom member of the can housing by a certain distance, it is not necessary to install an insulator between the electrode joint and the bottom member to prevent leakage current by insulating a portion other than the resistance welding portion.

[0035] According to the present invention, a terminal joint and a can housing can be resistance welded without installing an insulator between the can housing and the electrode joint.

[0036] According to the present invention, since an insulator is not installed between the electrode joint and the bottom member, the electrode assembly can be manufactured to be as tall as a conventional insulator. Furthermore, as the height of the electrode assembly increases, the battery capacity and energy density can be increased.

[0037] According to the present invention, since the height adjustment part is plastically deformed when the lower welding rod presses upward on the terminal joint, there is no need to strongly press the terminal joint with the lower welding rod to make the terminal joint adhere to the bottom member.

[0038] According to the present invention, since the height adjustment part is plastically deformed when the terminal joint is raised by the welding rod, the welding area may not be pre-tensioned after the terminal joint is welded.

[0039] According to the present invention, since pre-tension is fundamentally eliminated at the welding site, cracks can be prevented from occurring at the welding site due to vibration or impact occurring during use of the battery cell.

[0040] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0041] Figure 1 is a cross-sectional view schematically illustrating a state in which an electrode assembly is inserted into the inside of a can housing in a conventional battery cell.

[0042] Figure 2 is an exploded perspective view schematically illustrating the stacking state of electrodes and separators constituting a battery cell according to the present invention.

[0043] Fig. 3 is a perspective view schematically illustrating the stacking state of the electrode and separator of Fig. 2.

[0044] Figure 4 is a perspective view schematically illustrating a cylindrical electrode assembly according to the present invention.

[0045] Fig. 5 is a perspective view schematically illustrating a state in which a current collector plate is welded to the cylindrical electrode assembly of Fig. 4.

[0046] Figure 6 is a plan view schematically illustrating a first embodiment of a current collector plate according to the present invention.

[0047] Fig. 7 is a perspective view schematically illustrating the collector plate of Fig. 6.

[0048] Fig. 8 is a cross-sectional view schematically illustrating the collector plate of Fig. 6.

[0049] Fig. 9 is an enlarged view schematically illustrating the structure of the plastic deformation portion in the collector plate of Fig. 8.

[0050] Fig. 10 is a cross-sectional view schematically illustrating another example of a bonding protrusion in the collector plate of Fig. 8.

[0051] Fig. 11 is a cross-sectional view schematically illustrating a state in which the height adjustment part of the collector plate of Fig. 6 is deformed by being pressed upward by the lower welding rod.

[0052] Figure 12 is a cross-sectional view schematically illustrating a state in which an electrode assembly according to the present invention is inserted into a can housing.

[0053] Fig. 13 is a cross-sectional view schematically illustrating a state in which a jig pushes up an electrode assembly and a lower welding rod is raised while the can housing according to the present invention is turned over.

[0054] Fig. 14 is a cross-sectional view schematically illustrating a state in which the electrode assembly of Fig. 13 is pushed up and the collector plate is spaced apart from the bottom member of the can housing.

[0055] Fig. 15 is a cross-sectional view schematically illustrating a state in which the upper welding rod and the lower welding rod are in contact with the bottom member and the collector plate of the can housing of Fig. 14.

[0056] Fig. 16 is a cross-sectional view schematically illustrating a state in which a height difference occurs between a terminal joint and an electrode joint in the current collector plate of Fig. 15 as the terminal joint is pushed up by the lower welding rod.

[0057] Fig. 17 is a cross-sectional view schematically illustrating a state in which the terminal joint of Fig. 16 and the bottom member of the can housing are joined.

[0058] Fig. 18 is a cross-sectional view schematically illustrating the can housing of Fig. 17 in a state where it is turned upside down again.

[0059] Fig. 19 is a cross-sectional view schematically illustrating a second embodiment of a current collector plate according to the present invention.

[0060] Figure 20 is a cross-sectional view schematically illustrating a third embodiment of a current collector plate according to the present invention.

[0061] Fig. 21 is a cross-sectional view schematically illustrating a state in which the terminal joint of the current collector plate of Fig. 20 is height-adjusted.

[0062] Fig. 22 is a cross-sectional view schematically illustrating a fourth embodiment of a current collector plate according to the present invention.

[0063] [Explanation of symbols]

[0064] 10: Can housing 11: Side wall member 12: Bottom member 20: Electrode assembly 21: First electrode 22: Second electrode 23: Metal foil 24: Active material layer 25: Supporting portion 26: Non-coated portion 27: Electrode tab (notched tab) 28: Separator 29: Core portion 30: Collector plate 31: Electrode joint portion 32: Terminal joint portion 33: Joint panel portion 34: Joint protrusion portion 34a: Joint protrusion 34b: Joint tip portion 34c: Joint hole portion 35: Height adjustment portion 36: Through hole portion 37: Plastic deformation portion 38: Outer slope portion 39, 39a, 39b: Inner slope portion B1: First bend portion B2: Second bend portion B3: Third bend portion 41: Upper welding rod 42: Lower welding rod 50: now

[0065] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0066] The present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and with various modifications. However, these embodiments are provided to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. Therefore, the present invention is not limited to the embodiments disclosed below, but should be understood to include all modifications, equivalents, and substitutes included within the technical spirit and scope of the present invention, as well as substitutions or additions of the components of one embodiment with those of another embodiment.

[0067] The attached drawings are merely intended to facilitate understanding of the embodiments disclosed in this specification, and should not be construed as limiting the technical ideas disclosed in this specification, but should be understood to encompass all modifications, equivalents, and substitutes included within the spirit and technical scope of the present invention. In the drawings, the components may be expressed in exaggerated sizes or thicknesses for ease of understanding, but the scope of protection of the present invention should not be construed as being limited thereby.

[0068] The terminology used in this specification is only used to describe specific implementations or examples and is not intended to limit the present invention. In addition, the singular expression includes the plural expression unless the context clearly indicates otherwise. In the specification, terms such as "comprises" and "consists of" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification. In other words, it should be understood that terms such as "comprises" and "consists of" in the specification do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0069] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0070] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0071] When a component is referred to as being "above" or "below" another component, it should be understood that it is not only positioned directly above that other component, but that there may also be other components intervening there.

[0072] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0073] Hereinafter, a battery cell according to an embodiment of the present invention will be described.

[0074] FIG. 2 is an exploded perspective view schematically illustrating a stacked state of electrodes and separators constituting a battery cell according to the present invention, FIG. 3 is a perspective view schematically illustrating a stacked state of electrodes and separators of FIG. 2, FIG. 4 is a perspective view schematically illustrating a cylindrical electrode assembly according to the present invention, and FIG. 5 is a perspective view schematically illustrating a state in which a current collector is welded to the cylindrical electrode assembly of FIG. 4.

[0075] Referring to FIGS. 2 to 5, a cylindrical battery cell according to an embodiment of the present invention includes an electrode assembly (20), a current collector (30) electrically connected to the electrode assembly (20), and a can housing (10) that accommodates the electrode assembly (20) and the current collector (30).

[0076] The can housing is formed in a cylindrical shape. The can housing is formed of a conductive material and can be electrically connected to the negative tab of the electrode assembly (20).

[0077] The electrode assembly (20) includes a first electrode (21), a second electrode (22), and a separator (28) that extend in the longitudinal direction and have a predetermined width, as illustrated in FIG. 2. The electrode assembly (20) is manufactured in the form of a jelly-roll by forming a laminate in the order of the first electrode (21), the separator (28), the second electrode (22), and the separator (28), as illustrated in FIG. 3, and then winding it around a core shaft, as illustrated in FIG. 4. The electrode assembly (20) is formed in a cylindrical shape, and a core portion, which is an empty space, is formed in the center thereof.

[0078] The above first electrode (21) may be an anode, and the above second electrode (22) may be a cathode. Of course, the opposite may also be the case.

[0079] The above first electrode (21) and second electrode (22) are manufactured in the form of sheets. The electrode sheet is manufactured in the form of an active material layer (24) applied to the surface of a metal foil (23). The electrode sheet has a holding portion (25) on which the active material layer (24) is applied, and a non-coated portion (26) on which the active material layer (24) is not applied. The positive electrode sheet may have the non-coated portion (26) on one side in the width direction, and the negative electrode sheet may have the non-coated portion (26) on the other side in the width direction.

[0080] The non-conductive portion (26) is exposed or protrudes in the width direction of the laminate. The non-conductive portion (26) itself functions as an electrode tab (27).

[0081] The above-mentioned non-conductive portion (26) may be provided with notches at predetermined intervals to form flag-shaped notched tabs (27). A plurality of notched tabs (27) may be arranged in a sawtooth shape along the longitudinal direction of the electrode.

[0082] In the embodiment, the notching tabs (27) are exemplified as having an equilateral trapezoidal shape. However, their shapes may be various, such as a semicircle, a semi-ellipse, a triangle, a rectangle, a parallelogram, etc.

[0083] In addition, the embodiment exemplifies a form in which notching tabs (27) arranged along the longitudinal direction have the same width. However, the width of the notching tabs may be gradually or stepwise widened from the core side to the outer periphery side.

[0084] In addition, in the embodiment, a form in which the height of the notching tabs (27) gradually increases from the core side to the outer circumference side is exemplified. However, the height of these notching tabs (27) may be implemented in a form in which they are constant or gradually decrease.

[0085] In addition, in the embodiment, a structure in which a notching tab (27) is deleted in a predetermined section of the centripetal end of the plain portion (26) and a predetermined section of the centrifugal end is exemplified. However, it is of course possible that the notching tab (27) is not deleted in the centripetal end of the plain portion (26), and that the notching tab (27) is not deleted in the centrifugal end of the plain portion (26).

[0086] In the jelly roll-shaped electrode assembly (20), the notched tabs (27) can be bent radially and flattened as shown in FIG. 4. The notched tabs (27) can be bent radially inward or outward. In the embodiment, a structure in which the notched tabs (27) are bent radially inward is exemplified.

[0087] The above-mentioned notched tabs (27) can be bent one by one during the process of forming a jelly roll-shaped electrode assembly (20) by winding the laminate. Alternatively, the above-mentioned notched tabs (27) can be bent all at once after the laminate is wound to form a jelly roll-shaped electrode assembly (20).

[0088] The notching tabs (27) of the first electrode (21) and the notching tabs (27) of the second electrode (22), which are bent and overlapped in the radial direction in this way, can provide a plane that is substantially perpendicular to the axial direction at each of the axial ends of the electrode assembly (20).

[0089] A current collector plate (30) can be joined to a substantially flat surface provided by bending the notched tabs (27) exposed at both axial ends of the electrode assembly (20), as shown in FIG. 5.

[0090] In an embodiment, the collector plate (30) bonded to one axial end of the electrode assembly (20) may be a negative collector plate (30), and the collector plate (not shown) bonded to the other axial end of the electrode assembly (20) may be a positive collector plate. However, one collector plate (30) may be a positive collector plate, and the other collector plate may be a negative collector plate.

[0091] The above positive electrode collector plate may be made of aluminum, and the above negative electrode collector plate (30) may be made of copper. However, the materials are not limited thereto.

[0092] The above-mentioned collector plate (30) can be manufactured by punching, trimming, piercing, and bending a metal sheet.

[0093] The above can housing (10) includes a bottom member (12), a side wall member (11) connected to the bottom member (12) and extending in the axial direction, and a cap assembly (not shown) covering the open end of the side wall member (11).

[0094] The above-mentioned floor member (12) may have a disc shape, and the above-mentioned side wall member (11) may have a circular tube shape. The floor member and the side wall member may be formed integrally or connected by welding.

[0095] The above-mentioned bottom member (12) and side wall member (11) can be manufactured by forming a metal sheet with a nickel plated surface of steel using a deep drawing process, and trimming the front end of the side wall member (11) with a punch while holding it with a blank holder. Of course, the material of the can housing (10) is not limited to this.

[0096] According to a first embodiment of the cylindrical battery cell, the current collector (30) is joined to one axial end, i.e., the bottom, of the electrode assembly (20). For example, the back surface of the current collector (30) and the electrode tab (27) can be welded by irradiating a laser onto the surface of the current collector (30). The peripheral portion of the current collector (30) corresponds to the electrode tabs (27) of the electrode assembly (20), and the central portion of the current collector (30) is arranged to block the core portion of the electrode assembly (20).

[0097] FIG. 6 is a plan view schematically illustrating a first embodiment of a current collector plate according to the present invention, FIG. 7 is a perspective view schematically illustrating the current collector plate of FIG. 6, FIG. 8 is a cross-sectional view schematically illustrating the current collector plate of FIG. 6, FIG. 9 is an enlarged view schematically illustrating the structure of a plastic deformation portion in the current collector plate of FIG. 8, FIG. 10 is a cross-sectional view schematically illustrating another example of a bonding protrusion in the current collector plate of FIG. 8, and FIG. 11 is a cross-sectional view schematically illustrating a state in which a height adjustment portion in the current collector plate of FIG. 6 is deformed by being pressed upward by a lower welding rod.

[0098] Referring to FIGS. 6 to 11, the current collector (30) includes an electrode contact portion (31), a terminal contact portion (32), and a height adjustment portion (35).

[0099] The electrode joint (31) has an inner surface joined to the notched tab (27) of the electrode assembly (20). The electrode joint (31) may be formed in a circular ring shape surrounding the periphery of the current collector (30). The electrode joint (31) may be formed in a flat plate shape overall. The outer diameter of the electrode joint (31) may be formed smaller than the inner circumference of the can housing (10).

[0100] The terminal joint (32) is positioned radially inward of the electrode joint (31), and its outer surface is joined to the bottom surface of the bottom member (12) of the can housing (10). The terminal joint (32) is formed in a circular shape and can be concentric with the electrode joint (31). The terminal joint (32) can be formed to form the same plane as the electrode joint (31).

[0101] The height adjustment unit (35) is arranged between the electrode joint (31) and the terminal joint (32), electrically connects the electrode joint (31) and the terminal joint (32), and adjusts the joint height of the terminal joint (32) as it is deformed by an external force. The height adjustment unit (35) undergoes plastic deformation, so that it almost maintains the state deformed by the external force and does not return to its original state even when the external force is removed.

[0102] Accordingly, after the electrode assembly (20) is accommodated in the can housing (10), the can housing (10) is turned over. Then, the upper welding rod (41) comes into contact with the upper surface of the bottom member (123) of the can housing (10), the lower welding rod (42) is inserted into the core part of the electrode assembly (20), and the jig (50) pushes up while supporting the lower side of the electrode assembly (20). The lower electrode rod presses up the terminal joint (32) and pushes it up, and the jig (50) pushes up the electrode assembly (20) until a certain distance is spaced between the electrode joint (31) welded to the electrode assembly (20) and the bottom surface of the bottom member (12). Next, as the height adjustment part (35) is deformed, the terminal joint (32) is raised to a level where it comes into contact with the bottom member (12) of the can housing (10), and the electrode joint (31) of the current collector (30) has a height difference equal to the height of the terminal joint (32).

[0103] Since the terminal joint (32) is spaced apart from the bottom surface of the bottom member (12) of the can housing (10) by a certain distance (height difference), an insulator (bottom insulation panel) does not need to be installed between the electrode joint (31) and the bottom member (12) to prevent leakage current by insulating a portion other than the resistance welding portion (the electrode joint (31) portion). In addition, the terminal joint (32) and the can housing (10) can be resistance welded without installing an insulator inside the can housing (10).

[0104] In addition, since the insulator is not installed between the electrode joint (31) and the bottom member (12), the electrode assembly (20) can be manufactured as high as the thickness of the existing insulator. As the height of the electrode assembly (20) increases, the battery capacity and energy density can be increased. In particular, when the battery cell of the present invention is applied to a battery pack that loads tens or hundreds of battery cells, the battery capacity and energy density of the battery pack can be significantly increased.

[0105] In addition, since the height adjustment part (35) is plastically deformed when the lower welding rod (42) presses upward on the terminal joint (32), there is no need to strongly press the terminal joint (32) with the lower welding rod (42) to make the terminal joint (32) adhere to the bottom member (12). That is, even if the terminal joint (32) is pressurized with a lower pressure than before, the height adjustment part (35) can be deformed.

[0106] In addition, since the height adjustment part (35) is plastically deformed when the terminal joint (32) is raised, the welding area may not be pre-tensioned after the terminal joint (32) is welded. That is, since the restoring force of the height adjustment part (35) is almost eliminated as the height adjustment part (35) is plastically deformed, the restoring force of the height adjustment part (35) can be prevented from acting on the welding area. Accordingly, cracks can be prevented from occurring at the welding area due to vibration or impact generated during use of the battery cell.

[0107] The above terminal joint (32) may include a joint panel portion (33) and a joint protrusion portion (34).

[0108] The joint panel portion (33) is connected to the height adjustment portion (35) and is formed flat. The joint panel portion (33) may be formed in a circular plate shape. Of course, the joint panel portion (33) may also be formed in a polygonal plate shape.

[0109] The joint protrusion (34) may include a plurality of joint protrusions (34a) formed to protrude from the joint panel portion (33). The plurality of joint protrusions (34a) may be arranged in a matrix shape. The joint protrusions (34a) may be formed in a cone shape with a cross-section that becomes smaller as it goes upward.

[0110] The bonding projection (34a) may include a bonding tip (34b) of a closed shape as illustrated in Fig. 9. The bonding tip (34b) may be in point contact with the bottom member (12) to concentrate current on the bonding tip (34b).

[0111] Additionally, the joining projection (34a) may include an open-shaped joining hole (34c) as illustrated in Fig. 10. The joining hole (34c) may be formed in a circular shape with a very small diameter. The joining hole (34c) may be in line contact with the bottom member (12) to concentrate current at the welding area.

[0112] The height adjustment part (35) includes a plurality of through holes (36) and a plurality of plastic deformation parts (37).

[0113] A plurality of through holes (36) may be arranged on the outside of the terminal joint (32) to surround the terminal joint (32). The through holes (36) may be arranged along the circumference of the terminal joint (32). The through holes (36) may be arranged at equal intervals in the circumference or at slightly different intervals. The through holes (36) may be formed as an isosceles quadrilateral in which the radially outer side is longer than the inner side. Of course, the through holes (36) may be formed as a circle, an oval, a polygon, etc.

[0114] The through hole (36) improves the impregnation of the electrolyte in the electrode assembly (20) as the electrolyte passes through, and reduces the weight of the current collector (30).

[0115] A plurality of plastic deformation portions (37) are respectively arranged between a plurality of through-hole portions (36) and are connected to the terminal joint portion (32) and the electrode joint portion (31). The height (H1) of the plastic deformation portions (37) may be formed higher than the height (H2) of the joint protrusion portion (34) (H1>H2). The plurality of plastic deformation portions (37) are arranged along the circumferential direction of the terminal joint portion (32) and may be deformed as the height of the terminal joint portion (32) increases. The plastic deformation portions (37) may include at least two or more bent portions in the radial direction of the electrode joint portion (31).

[0116] When the terminal joint (32) is pressed upward by the lower welding rod (42), the plastic deformation portion (37) can be spread out or opened by the upward tension and attractive force of the terminal joint (32). At this time, since the through-hole portions (36) are respectively arranged between the plastic deformation portions (37), even if the terminal joint (32) is pressed with a weaker pressing force, the plastic deformation portions (37) can be easily spread out and the height adjusted. That is, the plurality of plastic deformation portions (37) according to the present invention can significantly weaken the reaction force compared to a structure formed in a circular shape around the periphery of the terminal joint (32).

[0117] When the lower welding rod (42) releases the pressure on the terminal joint (32), the plastic deformation portion (37) does not return to its original state but remains in the deformed state. As the terminal joint (32) comes into contact with the bottom member (12) of the can housing (10), it is positioned higher than the electrode joint (31), and the electrode joint (31) is reflexively spaced apart from the bottom member (12) by a certain distance. That is, a sufficient insulation gap required for resistance welding is secured. Accordingly, resistance welding becomes possible without installing an insulator between the electrode assembly (20) and the bottom member (12) of the can housing (10). In addition, since the insulator is not installed between the electrode joint (31) and the bottom member (12), the electrode assembly (20) can be manufactured as high as the thickness of the existing insulator. As the height of the electrode assembly (20) increases, the battery capacity and energy density can be increased.

[0118] In addition, since the plastic deformation portion (37) is not restored to its original state but remains in its deformed state, the welding portion is not pre-tensioned, and the restoring force of the height adjustment portion (35) can be fundamentally eliminated. Accordingly, the possibility of crack occurrence can be significantly reduced by preventing repetitive and continuous tension and stress from being generated at the welding portion.

[0119] The plastic deformation portions (37) and the through-hole portions (36) may be alternately arranged along the circumference of the terminal joint portion (32). A plurality of plastic deformation portions (37) may be formed with the same length. Four plastic deformation portions (37) may be arranged at 90-degree intervals, and four through-hole portions (36) may also be arranged at 90-degree intervals. Since the total length of the plastic deformation portions (37) is shortened by the total length of the through-hole portions (36), even if the terminal joint portion (32) is pressed with a smaller force, the plastic deformation portions (37) can be smoothly opened or spread out. The number of these plastic deformation portions (37) and terminal joint portions (32) may be appropriately changed in consideration of the pressing force of the lower welding rod (42), the thickness of the current collector (30), the ductility of the current collector (30), etc.

[0120] The plastic deformation portion (37) can be formed in an arc shape at a certain radius from the center of the terminal joint portion (32). Of course, the plastic deformation portion (37) can also be formed in a straight line shape.

[0121] The plastic deformation portion (37) may include an outer slope portion (38) and an inner slope portion (39).

[0122] The outer slope (38) may extend upwardly and slantedly from the radially inner side of the electrode joint (31). The outer slope (38) may be formed in an arc shape along the circumference of the electrode joint (31).

[0123] The inner slope (39) extends upwardly from the radially outer side of the terminal joint (32) and can be connected to the end of the outer slope (38). The inner slope (39) and the outer slope (38) converge upwardly in a conical shape. The length of the inner slope (39) and the length of the outer slope (38) may be the same or slightly different.

[0124] The plastic deformation portion (37) includes a first bend portion (B1) in which the electrode joint portion (31) and the outer slope portion (38) are bent, a second bend portion (B2) in which the outer slope portion (38) and the inner slope portion (39) are bent, and a third bend portion (B3) in which the inner slope portion (39) and the terminal joint portion (32) are bent (see Fig. 9). The second bend portion (B2) is arranged above the first bend portion (B1) and the third bend portion (B3).

[0125] Referring to Fig. 11, when the terminal joint (32) is pushed up by the lower welding rod (42), the first bend (B1) moves upward, the inner slope (39) is turned to form a nearly flat surface with the terminal joint (32), the second bend (B2) moves outward relative to the third bend (B3), and the outer slope (38) is turned outward at a predetermined angle with respect to the third bend (B3). Accordingly, even if the external force applied to the terminal joint (32) is removed, the inner slope (39) and the outer slope (38) do not return to their original state but remain in an unfolded state almost as is. In the unfolded state of the inner slope (39) and the outer slope (38), the restoring force on the plastic deformation portion (37) is almost eliminated.

[0126] In addition, when the terminal joint (32) is pushed up, the electrode joint (31) is positioned at a certain height (H) lower than the terminal joint (32) (see Fig. 11). Accordingly, since the electrode joint (31) maintains a sufficient insulating distance (H) with the bottom member (12) of the can housing (10), an insulator does not need to be installed between the terminal joint (32) and the bottom member (12) to prevent leakage current during resistance welding. In addition, the battery capacity can be increased as the insulator is omitted.

[0127] The angle of inclination (θ1) of the inner slope (39) can be formed within a range of 45° from an imaginary vertical line at the end of the outer slope (38). If the angle of inclination (θ1) of the inner slope (39) is less than the vertical line (located to the left of the vertical line), it is difficult for the inner slope (39) to smoothly unfold when the terminal joint (32) is raised. In addition, if the angle of inclination (θ1) of the inner slope (39) exceeds 45°, the length of the inner slope (39) is too short, making it difficult for the terminal joint (32) to be raised to a sufficient height. If the height of the terminal joint (32) is too low, it is difficult for the distance (height) between the electrode joint (31) and the floor member (12) to secure a sufficient insulation distance, and thus, it may be difficult to prevent current leakage.

[0128] The inclination angle (θ2) of the outer slope (38) can be formed within a range of 45° from an imaginary vertical line at the end of the inner slope (39). If the inclination angle (θ2) of the outer slope (38) is less than the vertical line (located to the right of the vertical line), when the terminal joint (32) is raised, the outer slope (38) is laid down too much, and the height of the terminal joint (32) becomes too low. In addition, if the inclination angle (θ2) of the outer slope (38) exceeds 45°, the length of the outer slope (38) is too short, making it difficult for the terminal joint (32) to be raised to a sufficient height. If the height of the terminal joint (32) is too low, it is difficult to secure a sufficient insulation distance between the electrode joint (31) and the floor member (12), and thus, it may be difficult to prevent current leakage.

[0129] The welding process of the current collector plate according to the present invention configured as described above will be described.

[0130] FIG. 12 is a cross-sectional view schematically illustrating a state in which an electrode assembly according to the present invention is inserted into a can housing, FIG. 13 is a cross-sectional view schematically illustrating a state in which a jig pushes up the electrode assembly and the lower welding rod is raised in a state in which the can housing according to the present invention is turned over, FIG. 14 is a cross-sectional view schematically illustrating a state in which the electrode assembly of FIG. 13 is pushed up and the collector plate is spaced apart from the bottom member of the can housing, FIG. 15 is a cross-sectional view schematically illustrating a state in which the upper welding rod and the lower welding rod are in contact with the bottom member and collector plate of the can housing of FIG. 14, FIG. 16 is a cross-sectional view schematically illustrating a state in which a height difference occurs between a terminal joint and an electrode joint as the terminal joint is pushed up by the lower welding rod in the collector plate of FIG. 15, FIG. 17 is a cross-sectional view schematically illustrating a state in which the terminal joint of FIG. 16 and the bottom member of the can housing are joined, and FIG. 18 is a cross-sectional view schematically illustrating a state in which the can housing of FIG. 17 is turned upside down again. This is a cross-sectional drawing.

[0131] Referring to Fig. 12, the electrode assembly (20) is inserted into the can housing (10) with the opening of the can housing (10) facing upward (see Fig. 12). At this time, an insulator for preventing current leakage is not installed on the bottom member (12) of the can housing (10).

[0132] Referring to FIGS. 13 and 14, the can housing (10) containing the electrode assembly (20) is turned upside down. At this time, the opening of the can housing (10) is positioned on the lower side. The jig (50) is raised while supporting the lower end of the electrode assembly (20), and the lower welding rod (42) is raised through the core portion of the electrode assembly (20). When the current collector plate (30) welded to the electrode assembly (20) is spaced apart from the bottom member (12) of the can housing (10) by a certain distance, the rising of the electrode assembly (20) is stopped. At this time, the terminal joint (32) of the current collector plate (30) is spaced apart from the bottom member (12) by a sufficient insulating distance, so that resistance welding is possible without interposing an insulator between the terminal joint (32) and the bottom member (12). That is, even if an insulator is not installed, an insulating distance is secured between the terminal joint (32) and the floor member (12), so that current leakage is prevented at the terminal joint (32), enabling resistance welding, and weak welding between the terminal joint (32) and the floor member (12) can be prevented.

[0133] Referring to FIGS. 15 to 17, the lower welding rod (42) continues to rise and pushes up the terminal joint (32) of the current collector plate (30). The joint projection (34) of the terminal joint (32) comes into contact with the bottom member (12) of the can housing (10). At this time, the upper welding rod (41) comes into contact with the upper surface of the bottom member (12), and the lower welding rod (42) comes into contact with the lower surface of the terminal joint (32). In this state, when current is applied to the upper welding rod (41) and the lower welding rod (42), the joint projection (34) of the terminal joint (32) melts due to the resistive heat and is joined to the bottom member (12).

[0134] Referring to Fig. 18, after the terminal joint (32) and the bottom member (12) are welded, the can housing (10) is turned over to its original state. At this time, since the terminal joint (32) and the bottom member (12) are positioned on the lower side of the can housing (10), the load of the electrode assembly (20) is applied to the terminal joint (32). The height adjustment part (35) of the current collector (30) is folded flat by the load of the electrode assembly (20).

[0135] Next, a second embodiment of a current collector plate according to the present invention will be described. Since the second embodiment is substantially identical to the first embodiment except for the plastic deformation portion, the same components will be given the same reference numerals and their descriptions will be omitted.

[0136] Fig. 19 is a cross-sectional view schematically illustrating a second embodiment of a current collector plate according to the present invention.

[0137] Referring to FIG. 19, the plastic deformation portion (37) of the current collector plate (30) according to the second embodiment may include an outer slope portion (38) and an inner slope portion (39a).

[0138] The outer slope (38) may extend upwardly and slantedly from the radially inner side of the electrode joint (31). The outer slope (38) may be formed in an arc shape along the circumference of the electrode joint (31).

[0139] The inner slope (39a) extends upwardly from the radially outer side of the terminal joint (32) and can be connected to the end of the outer slope (38). The inner slope (39a) and the outer slope (38) converge upwardly. The length of the inner slope (39) and the length of the outer slope (38) may be the same or slightly different.

[0140] The inner slope (39a) is formed in a zigzag shape along the radial direction. The inner slope (39a) has a structure that is bent at least once. The inner slope (39a) elastically stretches and resolves the local pressure deviation of the plastic deformation section (37).

[0141] The plastic deformation portion (37) includes a first bend portion (B1) where the electrode joint portion (31) and the outer slope portion (38) are bent, a second bend portion (B2) where the outer slope portion (38) and the inner slope portion (39a) are bent, and a third bend portion (B3) where the inner slope portion (39a) and the terminal joint portion (32) are bent. The inner slope portion (39a) can be elastically deformed between the first bend portion (B1) and the second bend portion (B2) when the terminal joint portion (32) moves upward. In addition, when a height deviation occurs where the terminal joint portion (32) does not come into contact with the bottom member (12), the height deviation of the terminal joint portion (32) can be resolved when the inner slope portion (39a) is elastically deformed by the pressing force of the lower welding rod (42).

[0142] Next, a third embodiment of a current collector plate according to the present invention will be described. Since the third embodiment is substantially identical to the first embodiment except for the plastic deformation portion, the same reference numerals will be used for the identical components and their descriptions will be omitted.

[0143] FIG. 20 is a cross-sectional view schematically illustrating a third embodiment of a current collector plate according to the present invention, and FIG. 21 is a cross-sectional view schematically illustrating a state in which a terminal joint is height-adjusted in the current collector plate of FIG. 20.

[0144] Referring to FIGS. 20 and 21, the plastic deformation portion (37) of the current collector plate (30) according to the third embodiment may include an outer slope portion (38) and an inner slope portion (39).

[0145] The outer slope (38) may extend downwardly in a radially inner direction from the electrode joint (31). The outer slope (38) may be formed in an arc shape along the circumference of the electrode joint (31).

[0146] The inner slope (39) extends downwardly from the radially outer side of the terminal joint (32) and can be connected to the end of the outer slope (38). The inner slope (39) and the outer slope (38) converge downward. The length of the inner slope (39) and the length of the outer slope (38) may be the same or slightly different.

[0147] The plastic deformation portion (37) includes a first bend portion (B1) where the electrode joint portion (31) and the outer slope portion (38) are bent, a second bend portion (B2) where the outer slope portion (38) and the inner slope portion (39) are bent, and a third bend portion (B3) where the inner slope portion (39) and the terminal joint portion (32) are bent. The second bend portion (B2) is arranged below the first bend portion (B1) and the third bend portion (B3). Since the bend portions of the plastic deformation portion (37) are structurally similar to the bend portions (B1, B2, B3) illustrated in Fig. 9, their illustration is omitted.

[0148] Next, a fourth embodiment of a current collector plate according to the present invention will be described. Since the fourth embodiment is substantially identical to the third embodiment except for the plastic deformation portion, the same components will be given the same drawing reference numerals and their descriptions will be omitted.

[0149] Fig. 22 is a cross-sectional view schematically illustrating a fourth embodiment of a current collector plate according to the present invention.

[0150] Referring to FIG. 22, the plastic deformation portion (37) of the current collector plate (30) according to the fourth embodiment may include an outer slope portion (38) and an inner slope portion (39a).

[0151] The outer slope (38) may extend downwardly in a radially inner direction from the electrode joint (31). The outer slope (38) may be formed in an arc shape along the circumference of the electrode joint (31).

[0152] The inner slope (39a) extends downwardly from the radially outer side of the terminal joint (32) and can be connected to the end of the outer slope (38). The inner slope (39a) and the outer slope (38) converge downward. The length of the inner slope (39a) and the length of the outer slope (38) may be the same or slightly different.

[0153] The inner slope (39a) is formed in a zigzag shape along the radial direction. The inner slope (39a) has a structure that is bent at least once. The inner slope (39a) elastically stretches and resolves the local pressure deviation of the plastic deformation section (37).

[0154] The plastic deformation portion (37) includes a first bend portion where the electrode joint portion (31) and the outer slope portion (38) are bent, a second bend portion where the outer slope portion (38) and the inner slope portion (39a) are bent, and a third bend portion where the inner slope portion (39a) and the terminal joint portion (32) are bent. Referring to Fig. 9, the inner slope portion (39a) can be elastically deformed between the first bend portion (B1) and the second bend portion (B2) when the terminal joint portion (32) moves upward.

[0155] Although the present invention has been described with reference to the drawings exemplified above, it is to be understood that the present invention is not limited to the embodiments and drawings disclosed herein, and that various modifications may be made by those skilled in the art within the scope of the technical idea of ​​the present invention. Furthermore, even if the operational effects according to the configuration of the present invention have not been explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be acknowledged.

Claims

1. An electrode joint whose inner surface is joined to the electrode tab of the electrode assembly; A terminal joint disposed radially inside the electrode joint and having an outer surface joined to the bottom surface of the can housing; and A current collector plate, comprising a height adjusting member disposed between the electrode joint and the terminal joint, electrically connecting the electrode joint and the terminal joint, and adjusting the joint height of the terminal joint as it is deformed by an external force.

2. In the first paragraph, the height adjustment unit, A plurality of through holes arranged on the outside of the terminal joint to surround the terminal joint; and A current collector plate comprising a plurality of plastic deformation portions, each of which is arranged between the plurality of through-hole portions, connected to the terminal joint portion and the electrode joint portion, arranged along the circumferential direction of the terminal joint portion, and deformed as the height of the terminal joint portion increases.

3. A current collector plate in the second paragraph, wherein the plastic deformation portion and the through hole portion are alternately arranged along the circumferential direction of the terminal joint portion.

4. In the third paragraph, the plastic deformation portion is formed in an arc shape with a certain radius from the center of the terminal joint portion.

5. In the second paragraph, the plastic deformation part is An outer inclined portion extending upwardly and slantingly from the radially inner side of the electrode joint; and A current collector plate including an inner inclined portion extending upwardly in an inclined manner from the radially outer side of the terminal joint and connected to an end of the outer inclined portion.

6. In the fifth paragraph, the angle of inclination of the inner slope is formed within a range of 45° from an imaginary vertical line at the end of the outer slope.

7. In the 6th paragraph, the angle of inclination of the outer slope is formed in a range of 45° with respect to an imaginary vertical line at the end of the inner slope.

8. In the second paragraph, the plastic deformation part is An outer inclined portion extending upwardly and slantingly from the radially inner side of the electrode joint; and A current collector plate including an inner inclined portion extending upward from the radially outer side of the terminal joint, connected to an end of the outer inclined portion, and formed in a zigzag shape along the radial direction.

9. In the 8th paragraph, the inner inclined portion is formed to be inclined upward from the radially outer side of the terminal joint portion.

10. In the second paragraph, the plastic deformation part is An outer inclined portion extending downwardly in a radial direction from the inner side of the electrode joint; and A current collector plate including an inner inclined portion extending downwardly in a radial direction from the outer side of the terminal joint and connected to an end of the outer inclined portion.

11. In the second paragraph, the plastic deformation part is An outer inclined portion extending downwardly in a radial direction from the inner side of the electrode joint; and A current collector plate including an inner inclined portion extending downwardly from the radially outer side of the terminal joint, connected to an end of the outer inclined portion, and formed in a zigzag shape along the radial direction.

12. A current collector plate in accordance with claim 11, wherein the inner slope is formed to slope downward from the radially outer side of the terminal joint.

13. In the first paragraph, the terminal joint is, A joint panel portion connected to the height adjustment portion and formed flat; and A current collector plate including a bonding projection portion having a plurality of bonding projections formed to protrude from the bonding panel portion.

14. A current collector plate according to claim 13, wherein the bonding projection includes a bonding tip having a closed shape.

15. A current collector plate in accordance with claim 13, wherein the bonding projection includes a bonding hole of an open shape.

16. In the 13th paragraph, the height of the plastic deformation portion of the height adjustment portion is formed higher than the height of the joint protrusion portion.

17. Can housing having a bottom member and a side wall member; An electrode assembly accommodated in the above can housing; A battery cell comprising a current collector plate according to any one of claims 1 to 16, which is welded to a bottom member of the can housing while the electrode assembly is accommodated in the can housing.

18. A battery cell according to claim 17, wherein the can housing is formed in a cylindrical shape.

Images