Current collecting plate and secondary battery including same

Abstract

A secondary battery according to an embodiment of the present invention comprises: a housing that includes a battery can forming an accommodation space therein and a top cap covering one open side of the battery can; an electrode assembly accommodated inside the battery can; and a current collecting plate electrically connected to at least one of the battery can or the top cap. The current collecting plate may include: a current collecting body that connects at least one of the battery can or the top cap to the electrode assembly; and a plating layer, having a greater electrical resistance than the current collecting body, on at least a portion of a welding surface of the current collecting body.

Description

Collector plate and secondary battery including same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0012557, filed January 26, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a current collector connected to a jelly roll type electrode assembly and a secondary battery including the same.

[0005] Common types of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. These batteries are used not only in small products such as digital cameras, DVDs, MP3 players, mobile phones, PDAs, portable game devices, power tools, and e-bikes, but also in larger products requiring high output, such as electric and hybrid vehicles, as well as in power storage devices that store surplus power or renewable energy, and as backup power storage devices.

[0006] To manufacture these secondary batteries, first, an electrode active material slurry is applied to a positive electrode current collector and a negative electrode current collector to manufacture a positive electrode and a negative electrode, and these are laminated on both sides of a separator to form an electrode assembly of a predetermined shape. Then, the electrode assembly is housed in a battery case, filled with electrolyte, and sealed.

[0007] Secondary batteries are classified into pouch type and can type, depending on the material of the case housing the electrode assembly. Pouch type batteries house the electrode assembly in a pouch made of a flexible polymer material. Can type batteries house the electrode assembly in a case made of materials such as metal or plastic.

[0008] In the case of a can-type, i.e., cylindrical secondary battery, a jelly-roll-type electrode assembly is manufactured by winding a separator between the positive and negative electrodes, and the jelly-roll-type electrode assembly is inserted into the inside of a battery can, welded, and accommodated, thereby manufacturing a cylindrical secondary battery.

[0009] Typically, a jelly roll of a cylindrical secondary battery is manufactured by welding conductive tabs to the uncoated portion of the electrode, and the current generated from the positive and negative plates of the jelly roll is directed to the positive and negative terminals, respectively. Cylindrical secondary batteries constructed in this manner utilize multiple tabs for use in various high-power industrial fields. This lowers the battery's resistance, enabling its application in higher-power industrial fields.

[0010] However, there are challenges in designing the tabs as part of the electrode. During the process of electrically connecting and welding the lead tabs to the uncoated portions of the positive and negative electrodes, the narrow width of the lead tabs can cause excessive heat generation due to the concentration of current in the lead tabs. While adjusting the length and width of the tabs can minimize this, this reduces the area covered by the electrode slurry, leading to another problem: lowering the volumetric energy density of the battery. Additionally, there is the challenge of dispersing the steps during the jellyroll winding process.

[0011] Recently, the demand for high-energy density and high-power battery performance has increased for batteries used in various cutting-edge fields, including the electric vehicle industry. To meet these demands, a battery design that not only has high energy density but also low resistance and can withstand high currents is essential. To address this, stripe coating is used instead of pattern coating. This creates a non-coated region at the electrode tip, which is then notched to form a foil tab. This process often involves additionally designing a current collector plate and welding it to the foil tab, and then welding the jelly roll, welded to the current collector plate, to the inner surface of the battery can and the top cap. This numerous tabs form an electrical path, significantly reducing the battery's resistance and enabling high power output.

[0012] However, during the process of applying the current collector plate in this manner, the welding strength of the current collector plate is weak, causing the plate to easily separate from the battery can or top cap. Furthermore, due to the current collector plate covering the entire surface of the electrode assembly, the degree of impregnation of the electrode assembly with electrolyte is often not properly secured during the subsequent process.

[0013] As a result, there is a need for a secondary battery having a collector plate structure that can improve the weldability of the collector plate and increase the electrolyte impregnation property of the electrode assembly while simultaneously applying the collector plate.

[0014] The problem to be solved by the present invention is to provide a current collector plate having improved structure and material to increase weldability and a secondary battery including the same.

[0015] A secondary battery according to an embodiment of the present invention includes a housing including a battery can forming an accommodation space inside and a top cap covering an open side of the battery can, an electrode assembly accommodated inside the battery can, and a current collector plate electrically connected to at least one of the battery can or the top cap, wherein the current collector plate may include a current collector body connecting the electrode assembly to at least one of the battery can or the top cap, and a plating layer having an electrical resistance greater than an electrical resistance of the current collector body on at least a portion of a welding surface of the current collector body.

[0016] The above-mentioned current collector body may include a central portion and a plurality of wing portions formed along the periphery of the central portion and spaced apart from each other at a certain interval.

[0017] The electrode assembly may have a center hole formed along the length direction on the inside, the central portion may be formed to face the center hole, and the plurality of wing portions may be formed to face the end surface of the electrode assembly.

[0018] The above wing portion may include a radial shape that becomes wider as it goes outward from the center.

[0019] The wing portion may include a plurality of welded portions welded to at least one of the battery can or the electrode assembly.

[0020] The above plurality of welding portions can be formed along a radial direction based on the center.

[0021] The above plurality of welding portions can be formed within an area corresponding to 0.151 to 0.383 times the outer diameter of the electrode assembly in a radial direction from the center of the current collector body.

[0022] The end face of the electrode assembly is provided with a plurality of electrode tabs that are folded to overlap each other, and the plurality of welding portions can be formed in a portion where 10 or more of the electrode tabs overlap.

[0023] The above current collector plate may further include a plurality of protrusions formed protruding on one surface of the current collector body facing the inner side of the housing.

[0024] The above plurality of protrusions may be formed on one surface of the central portion that is welded to the inner surface of the housing.

[0025] The current collector body may include a ring portion, a central portion located on the inner side of the ring portion, and a plurality of wing portions that connect the central portion and the ring portion and are spaced apart from each other at a set interval.

[0026] The above-mentioned current collector body may include at least one plate among a copper plate or a clad plate in which nickel and copper are laminated.

[0027] The above plating layer may include a nickel (Nikcel) material.

[0028] The above clad plate may include a structure in which copper is laminated between nickel.

[0029] The angle formed by the plurality of wing portions may be 36 to 44 degrees.

[0030] Based on the center point of the center, when the radius of the center point is R1 and the radius from the center point to the inner circumference of the ring part is R2, R2 / R1 may be 2.138 to 2.613.

[0031] When the radius from the center point to the inner circumference of the ring part is R2 and the radius from the center point to the outer circumference of the ring part is R3, R3 / R2 may be 1.069 to 1.306.

[0032] The outer diameter of the above ring portion may be 1 mm to 2 mm smaller than the outer diameter of the electrode assembly.

[0033] A current collector according to an embodiment of the present invention may include a current collector body connecting at least one of the battery can or the top cap and the electrode assembly; and a plating layer having an electrical resistance greater than the electrical resistance of the current collector body on at least a portion of a welding surface of the current collector body.

[0034] According to a preferred embodiment of the present invention, the structure and material of the current collector plate can be improved to increase the weldability of the current collector plate to the battery can or top cap.

[0035] According to a preferred embodiment of the present invention, the electrolyte impregnation property of the electrode assembly can be increased by the structural features of the current collector plate.

[0036] In addition, the configurations according to preferred embodiments of the present invention may include effects that can be easily predicted by those skilled in the art.

[0037] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0038] Figure 1 is a perspective view of a secondary battery according to an embodiment of the present invention.

[0039] Figure 2 is a cutaway perspective view of a secondary battery according to an embodiment of the present invention.

[0040] Figure 3 is a perspective view of the electrode assembly illustrated in Figure 2.

[0041] FIG. 4 is a perspective view of an electrode assembly in which a first collector plate and a second collector plate are welded according to an embodiment of the present invention, and is accommodated in a battery can.

[0042] FIG. 5 is a drawing showing the bottom surface of a first collector plate according to an embodiment of the present invention.

[0043] Figure 6 is a plan view of a first collector plate according to an embodiment of the present invention.

[0044] FIG. 7 is a drawing showing the bottom surface of a first collector plate according to another embodiment of the present invention.

[0045] Figure 8 is a plan view of a first collector plate according to another embodiment of the present invention.

[0046] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0047] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0048] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0049] FIG. 1 is a perspective view of a secondary battery (1) according to an embodiment of the present invention, FIG. 2 is a cutaway perspective view of a secondary battery (1) according to an embodiment of the present invention, and FIG. 3 is a perspective view of an electrode assembly (11) illustrated in FIG. 2.

[0050] Referring to FIGS. 1 and 2, a secondary battery (1) according to an embodiment of the present invention stores electrical energy through a chemical reaction of lithium ions and can output the stored electrical energy to the outside according to needs and design. For example, the secondary battery (1) can be manufactured by winding a sheet in which a positive electrode, a negative electrode, and a separator are alternately laminated and housing it inside.

[0051] Specifically, the secondary battery (1) may include a housing (10), an electrode assembly (11), and a current collector plate (12)(13).

[0052] The housing (10) can form the exterior of the secondary battery (1). For example, the housing (10) can include a cylindrical shape, i.e., a can shape, and can accommodate and seal an electrode assembly (11) described later therein. Additionally, the housing (10) can include a battery can (100) forming an accommodation space therein and a top cap (101) covering an open side of the battery can (100).

[0053] The battery can (100) may include a structure with one side open. For example, the battery can (100) may include a cylindrical shape having an opening formed on the upper side and an accommodation space formed on the inner side. In this case, during the process of manufacturing the secondary battery (1), a jelly-roll-shaped electrode assembly (11) may be inserted into the interior of the battery can (100) through the opening. In addition, an electrolyte may flow into the interior of the battery can (100) through the opening, so that the electrode assembly (11) may be impregnated with the electrolyte.

[0054] The top cap (101) can cover an open side of the battery can (100). That is, the top cap (101) can be combined with the upper side of the battery can (100) to seal the inside of the battery can (100). In other words, the top cap (101) can function to prevent the electrode assembly (11) accommodated inside the battery can (100) from leaking out.

[0055] The electrode assembly (11) can be formed by alternately stacking and winding a positive electrode, a negative electrode, and a separator. That is, the electrode assembly (11) can be accommodated inside a battery can (100) in the form of a jelly roll. In this case, the electrode assembly (11) can form a center hole (110) extending along the axial direction on the inside.

[0056] Referring to Fig. 3, electrode tabs (111)(112) may be provided at both ends in the axial direction of the electrode assembly (11). The electrode tabs (111)(112) may include a first electrode tab (111) and a second electrode tab (112) having different polarities. For example, the first electrode tab (111) may be provided at the lower end of the electrode assembly (11), and the second electrode tab (112) may be provided at the upper end.

[0057] The portions of the positive and negative electrodes of the electrode assembly (11) where the electrode active material is not applied, i.e., the uncoated portion, can be cut into electrode tabs (111)(112). The electrode tabs (111)(112) can have a foil flag shape and can be folded toward the center hole (110). More specifically, a plurality of electrode tabs (111)(112) can be folded to overlap each other.

[0058] The collector plates (12)(13) can be welded to the electrode tabs (111)(112). The collector plates (12)(13) can include a first collector plate (12) and a second collector plate (13) that are welded to the axial end surfaces of the electrode assembly (11). For example, the first collector plate (12) can be welded to the first electrode tab (111), and the second collector plate (13) can be welded to the second electrode tab (112). The first collector plate (12) and the second collector plate (13) can have different polarities.

[0059] As previously described, the plurality of electrode tabs (111)(112) can be folded so as to overlap each other. Accordingly, both end surfaces of the electrode assembly (11) can have an overall flat shape, and the current collector plates (12)(13) can be smoothly welded to both end surfaces of the electrode assembly (11).

[0060] The collector plate (12)(13) can be electrically connected to the battery can (100) or the top cap (101). Hereinafter, an example will be described in which the first collector plate (12) is connected to the battery can (100) and the second collector plate (13) is connected to the top cap (101).

[0061] FIG. 4 is a perspective view showing an electrode assembly (11) in which a first collector plate (12) and a second collector plate (13) are welded according to an embodiment of the present invention, accommodated in a battery can (100).

[0062] The first collector plate (12) and the second collector plate (13) can be joined to the electrode tabs (111) (112) of the electrode assembly (11) through laser welding. In other words, a high-power laser beam can be irradiated to the welding portion between the first collector plate (12) and the second collector plate (13) and the electrode assembly (11). By thermally melting the portion to be welded by the laser beam, the first collector plate (12) and the second collector plate (13) can be welded to the electrode tabs (111) (112) of the electrode assembly (11) with deep welding and high welding speed.

[0063] The current collector plates (12)(13) can be inserted into the inside of the battery can (100) together with the electrode assembly (11) while being welded to the electrode assembly (11). Thereafter, the first current collector plate (12) can be welded to the battery can (100), and the second current collector plate (13) can be welded to the top cap (101). As a result, the battery can (100) and the top cap (101) can be electrically connected to the electrode assembly (11) and can have different polarities.

[0064] The first collector plate (12) can be welded to the inner surface of the battery can (100), more specifically, to the bottom surface. In this case, the first collector plate (12) and the battery can (100) can be welded to each other through resistance welding using a resistance rod (not shown). Specifically, when the first collector plate (12) is in contact with the inner surface of the battery can (100), a resistance rod inserted through the center hole (110) can pressurize the first collector plate (12). Then, a high-power current can flow to the resistance rod. Due to the current of the resistance rod, high heat is generated at the contact portion of the first collector plate (12) and the battery can (100) due to the resistance, and the contact portion of the first collector plate (12) and the battery can (100) can be welded to each other by the high heat.

[0065] The second collector plate (13) can be welded to the top cap (101). For example, after the first collector plate (12) is welded to the inner surface of the battery can (100), the top cap (101) is joined to one open side of the battery can (100), and the second collector plate (13) can be welded to the lower surface of the top cap (101).

[0066] Specifically, after the first collector plate (12) is welded to the inner surface of the battery can (100), a beading portion (100a) may be formed by pressing the outer circumference of the battery can (100) inward through a beading process. This beading portion (100a) may overlap a portion of the outer surface of the electrode assembly (11) with respect to the axial direction of the electrode assembly (11). Therefore, the beading portion (100a) may prevent the electrode assembly (11) accommodated in the inner side of the battery can (100) from being separated from the interior of the battery can (100). In addition, a top cap (101) may be mounted on the beading portion (100a).

[0067] The secondary battery (1) may further include a gasket (14) provided between the battery can (100) and the top cap (101) to block contact between the battery can (100) and the top cap (101). The gasket (14) may prevent the battery can (100) and the top cap (101) having different polarities from contacting each other and causing a short circuit. That is, the gasket (14) may be formed along the inside of the battery can (100) to insulate the battery can (100) and the top cap (101) from each other.

[0068] A gasket (14) may be coupled to the top cap (101) to cover the perimeter of the top cap (101). The gasket (14) may have a closed loop shape extending along the perimeter of the top cap (101).

[0069] The top cap (101) with the gasket (14) attached thereto can be secured to the battery can (100), more specifically, to the beading portion (100a) of the battery can (100). In this state, the upper end of the battery can (100) can be crimped inward to form a crimping portion (100b). This crimping portion (100b) can be positioned on the upper side of the beading portion (100a) described above. By this process, the gasket (14) can be fixed between the beading portion (100a) and the crimping portion (100b) of the battery can (100). As a result, the top cap (101) can be firmly attached to the battery can (100), and the gasket (14) can prevent contact between the battery can (100) and the top cap (101).

[0070] FIG. 5 is a drawing showing the bottom surface of a first collector plate (12) according to an embodiment of the present invention, and FIG. 6 is a plan view of the first collector plate according to an embodiment of the present invention.

[0071] Hereinafter, the first collector plate (12) will be described as the collector plate (12), and the first electrode tab (111) will be described as the electrode tab (111). Unless otherwise specified, those skilled in the art will readily understand that the same description can be applied to the second collector plate (13) and the second electrode tab (112).

[0072] Referring to FIGS. 5 and 6, the current collector plate (12) may include a current collector body (120) that connects at least one of the battery can (100) or the top cap (101) and the electrode assembly (11). The current collector body (120) may face one end surface of the electrode assembly (11) with respect to the axial direction of the electrode assembly (11). That is, the current collector body (120) may cover one end surface of the electrode assembly (11). For example, the current collector body (120) may be welded to the inner surface of the electrode assembly (11) and the battery can (100), thereby connecting the electrode assembly (11) and the battery can (100) to each other.

[0073] The collector body (120) may include a central portion (1200) and a plurality of wing portions (1201).

[0074] The central portion (1200) may be located at the central portion of the current collector body (120). In this case, the central portion (1200) may be located to correspond to the central portion of the end face of the electrode assembly (11). For example, the central portion (1200) may face the center hole (110). In other words, the central portion (1200) may cover one side of the center hole (110).

[0075] The center (1200) can be welded to the housing (10). More specifically, the center (1200) can be welded to the inner surface of the battery can (100) or the inner surface of the tab cap (101).

[0076] A plurality of wing portions (1201) may be formed along the periphery of the central portion (1200). In addition, the plurality of wing portions (1201) may be formed to be spaced apart from each other at a constant interval. In this case, the plurality of wing portions (1201) may be formed to face the axial end surface of the electrode assembly (11). That is, the plurality of wing portions (1201) may be formed to face the end surface of the electrode assembly (11). In other words, the plurality of wing portions (1201) may be welded to one end surface with respect to the axial direction of the electrode assembly (11).

[0077] The wing portion (1201) may include a radial shape that becomes wider as it goes outward from the center (1200). That is, the wing portion (1201) may include a shape that becomes wider as it goes outward from the center (1200) in the radial direction based on the center (1200). According to the structure of the wing portion (1201) having such a radial shape, the current collector plate (12) is stably coupled to the inner surface of the battery can (100) or the top cap (101), and at the same time, does not occupy space unnecessarily, thereby improving the electrolyte impregnation property of the electrode assembly (11).

[0078] For example, in a state where an electrode assembly (11) is accommodated inside a battery can (100), an electrolyte may be injected into the interior of the battery can (100), and the electrode assembly (11) may be immersed in the electrolyte and undergo an activation process. In this process, the electrolyte may flow into the space between the plurality of wing portions (1201) and thus may spread over the end surface of the electrode assembly (11), and the electrode assembly (11) may be smoothly immersed in the electrolyte.

[0079] The wing portion (1201) can be welded to the electrode assembly (11). More specifically, the wing portion (1201) can be welded to the electrode tabs (111) (112) provided on the end surface of the electrode assembly (11).

[0080] A plurality of welding portions (1201a) that are welded to the electrode assembly (11) may be formed on the wing portion (1201). The welding portions (1201a) may be marks left by welding, for example, welding beads.

[0081] Various welding methods may be applied to the plurality of welding portions (1201a). For example, the plurality of welding portions (1201a) may be welded to the battery can (100) or the electrode assembly (11) using at least one of laser welding, ultrasonic welding, and resistance welding.

[0082] Additionally, the plurality of welding portions (1201a) can be welded within a range where the separator of the electrode assembly (11) is not damaged by high temperature. If the separator of the electrode assembly (11) is damaged, there is a risk of a hard short occurring between the positive and negative electrodes. In order to prevent the phenomenon of the positive and negative electrodes coming into contact in advance, the plurality of welding portions (1201a) can be welded taking into account the degree of damage to the separator when the secondary battery (1) is used.

[0083] As described above, the end face of the electrode assembly (11) to which the current collector plate (12) is welded may be provided with a plurality of electrode tabs (111) that are folded and overlapped with each other. In this regard, in order to prevent the separator of the electrode assembly (11) from being damaged by high temperature, the current collector plate (12) may be welded to the portion where the plurality of electrode tabs (111) overlap. Preferably, the current collector plate (12) may be welded to the portion where 10 or more electrode tabs (111) overlap. That is, the plurality of welding portions (1201a) may be welded to the portion where 10 or more electrode tabs (111) overlap.

[0084] In this way, the plurality of electrode tabs (111) can prevent the high temperature generated during the welding process from damaging the separator of the electrode assembly (11).

[0085] For example, a plurality of welding portions (1201a) may be formed along a radial direction based on the center (1200). Specifically, referring to FIG. 6, a plurality of welding portions (1201a) may be formed along a reference line (S) that crosses the center of the collector plate (12). For example, the reference line (S) may include a vertical line and a horizontal line that pass through the center of the collector plate (12), and the vertical line and the horizontal line may be lines that cross the center of the wing portion (1201). In this case, a plurality of welding portions (1201a) may be formed along the vertical line and the horizontal line.

[0086] The plurality of welded portions (1201a) may form a plurality of rows along the reference line (S). For example, the plurality of welded portions (1201a) may be arranged in a single row along the reference line (S), and the rows in which the plurality of welded portions (1201a) are arranged may be configured in multiple rows. Preferably, the plurality of welded portions (1201a) may be arranged in two rows so as to be positioned on each side of the reference line (S). However, the plurality of welded portions (1201a) are not necessarily arranged in only two rows, and may be arranged in multiple rows or radially, depending on necessity and design.

[0087] According to the structure and characteristics of the plurality of welding portions (1201a) as described above, the tensile strength of the current collector plate (12) is further secured, thereby improving the welding quality. In other words, due to these characteristics, a wider variety of welding methods can be applied to the current collector plate (12).

[0088] Additionally, the current collector plate (12) may further include a plurality of protrusions (122) formed protrudingly on one surface of the current collector body (120) facing the inner surface of the housing (10). For example, the plurality of protrusions (122) may be formed on one surface of the central portion (1200) welded to the inner surface of the housing (10). For example, the plurality of protrusions (122) may be formed protrudingly from the central portion (1200) so as to face the bottom surface of the battery can (100). The plurality of protrusions (122) may have an embossed shape.

[0089] The plurality of protrusions (122) may be a structure formed on the current collector plate (12) before the inner surface of the current collector plate (12) and the battery can (100) are welded. The plurality of protrusions (122) may be a portion that comes into contact with the inner surface of the battery can (100) and is melted and welded.

[0090] Additionally, the ends of the plurality of protrusions (122) may have a smaller cross-sectional area as they get closer to the inner surface of the housing (10). For example, the ends of the plurality of protrusions (122) may have a gently curved shape. That is, the ends of the plurality of protrusions (122) may include blunt surfaces.

[0091] In the resistance welding process, the current of the resistance rod flows to a plurality of protrusions (122) having a small cross-sectional area to generate an overcurrent, and the plurality of protrusions (122) in which the overcurrent is generated can be more effectively melted by the high temperature and welded to the inner surface of the battery can (100). That is, in the process in which the current of the resistance rod flows from the current collector body (120) to the plurality of protrusions (122), the current is more concentrated, so that more heat is generated, and the welding effect can be increased compared to the same current output intensity and output time.

[0092] The current collector plate (12) may further include a plating layer (121) having an electrical resistance greater than the electrical resistance of the current collector body (120) on at least a portion of the welding surface of the current collector body (120). For example, the current collector body (120) may include at least one of a copper plate or a clad plate in which nickel and copper are laminated. The clad plate may include a structure in which copper is laminated between nickel. The plating layer (121) may include a nickel material. The plating layer (121) may be a plate made of nickel.

[0093] By forming a plating layer (121) having a relatively higher electrical resistance than the current collector body (120) on a portion of the welding surface of the current collector body (120), more heat is generated at the welding surface, so that the welding surface can be melted, and the welding bonding property of the current collector plate (12) and the battery can (100) can be further increased.

[0094] In addition, the plating layer (121) may be formed on a portion of the current collector body (120) on which a plurality of protrusions (122) are formed. However, this is only one embodiment of the plating layer (121), and various forms of the plating layer (121) may be implemented to increase weldability. For example, the plating layer (121) may be formed on a portion of the wing portion (1201) on which a plurality of welding portions (1201a) are formed. Alternatively, the plating layer (121) may be formed on the outer surface of the plurality of protrusions (122). In addition, when the current collector plate (12) and the electrode assembly (11) are welded together, the plating layer (121) may be formed on a portion of the current collector body (120) facing the electrode assembly (11). Finally, the plating layer (121) may be formed on the entire lower surface of the current collector plate (12).

[0095] Fig. 7 is a bottom view of a first collector plate (12) according to another embodiment of the present invention, and Fig. 8 is a plan view of a first collector plate according to another embodiment of the present invention.

[0096] Below, the structure of a current collector plate (12) according to another embodiment of the present invention will be described. Any description that overlaps with the description of the structure of the first current collector plate (12) described above will be omitted.

[0097] Referring to FIGS. 7 and 8, a current collector (12) according to another embodiment of the present invention includes a current collector body (120) that connects at least one of a battery can (100) or a top cap (101) and an electrode assembly (11), and the current collector body (120) may include a ring portion (1202), a central portion (1200), and a plurality of wing portions (1201).

[0098] The ring portion (1202) may be a portion forming the periphery of the current collector plate (12). That is, when the current collector body (120) faces the end surface of the electrode assembly (11), the ring portion (1202) may be a portion formed along the periphery of the end surface of the electrode assembly (11). For example, the ring portion (1202) may have a closed loop shape.

[0099] The ring portion (1202) can be formed along the inner circumference of the battery can (100). The ring portion (1202) can be formed along the circumference of the end surface of the electrode assembly (11).

[0100] Specifically, the ring portion (1202) may include a circular ring shape. For example, the battery can (100) may include a cylindrical shape, and the ring portion (1202) may include a circular ring shape to correspond to the inner circumference of the battery can (100). In other words, the ring portion (1202) may include a circular ring shape formed along the circumference of the jelly roll-shaped electrode assembly (11).

[0101] The central portion (1200) may be located on the inner side of the ring portion (1202), and a plurality of wing portions (1201) may connect the central portion (1200) and the ring portion (1202). The plurality of wing portions (1201) may be spaced apart from each other at a predetermined interval in the circumferential direction of the central portion (1200). The interval formed between the plurality of wing portions (1201) may function as an opening through which an electrolyte may pass.

[0102] The ring portion (1202) and the center portion (1200) can be integrally connected to a plurality of wing portions (1201).

[0103] According to the structure of the ring portion (1202) as described above, when the current collector body (120) is welded to the electrode assembly (11), it can be welded in a more aligned state at the center of the electrode assembly (11). In other words, since the current collector plate (12) includes the ring portion (1202) in the shape of a circular ring, the concentricity of the electrode assembly (11) and the concentricity of the current collector body (120) can be more precisely matched. As a result, the welding precision of the current collector body (120) can be further increased, and the current collector plate (12) can be more stably combined with the battery can (100).

[0104] The outer diameter of the ring portion (1202) may be smaller than the outer diameter of the electrode assembly (11). This may be to provide a safety margin in the concentricity between the current collector plate (12) and the electrode assembly (11). Preferably, the outer diameter of the ring portion (1202) may be 1 mm to 2 mm smaller than the outer diameter of the electrode assembly (11). Accordingly, even if the concentricity of the current collector plate (12) and the electrode assembly (11) is not completely aligned, the ring portion (1202) may not protrude outward from the electrode assembly (11). If the difference between the outer diameter of the ring portion (1202) and the outer diameter of the electrode assembly (11) is less than 1 mm, there is a risk that a part of the ring portion (1202) may protrude outward from the electrode assembly (11), and in this case, a defect may occur when the electrode assembly (11) to which the current collector plate (12) is welded is inserted into the battery can (100). Conversely, if the difference between the outer diameter of the ring portion (1202) and the outer diameter of the electrode assembly (11) is greater than 2 mm, the size of the current collector (11) becomes unnecessarily small, and thus the resistance of the current collector (11) may increase.

[0105] The welding portion (1201a) of the current collector plate (12) can be formed within an area corresponding to 0.151 to 0.383 times the outer diameter of the electrode assembly (11) in the radial direction from the center of the current collector body (120). For example, when the outer diameter of the electrode assembly (11) is approximately 20.5 mm, the welding portion (1201a) of the current collector plate (12) can be formed within an area corresponding to 3.10 to 7.85 mm in the radial direction from the center of the current collector body (120).

[0106] Due to these limitations, the welding portion (1201a) of the current collector (12) can be welded to a portion of the end face of the electrode assembly (11) where a plurality of electrode tabs (111), preferably 10 or more electrode tabs (111), overlap. As described above, the plurality of electrode tabs (111) can prevent high temperatures generated during the welding process from damaging the separator of the electrode assembly (11).

[0107] In an experimental example related to this, when the outer diameter of the electrode assembly (11) is 20.64 mm, it was confirmed through simulation that when the welding portion (1201a) of the current collector (12) deviates from an area corresponding to approximately 3.18 mm to 7.66 mm in the radial direction from the center of the current collector body (120), less than 10 electrode tabs (111) of the electrode assembly (11) are welded to the overlapping portion.

[0108] The welding portion (1201a) of the current collector (12) may be formed with a margin of 1 mm or more from the opening formed between the plurality of wing portions (1201). That is, the gap between the opening and the welding portion (1201a) may be 1 mm or more. If the gap is less than 1 mm, there is a risk that the laser or the like used for welding may interfere with the opening, causing damage to the electrode assembly (11).

[0109] The angle (θ) formed by the plurality of wing parts (1201) with respect to each other may be 36 degrees to 44 degrees. In other words, with respect to the center of the current collector body (120), the angle (θ) formed by the adjacent wing parts (1201) among the plurality of wing parts (1201) may be 36 degrees to 44 degrees.

[0110] If the angle (θ) formed by the adjacent wing portions (1201) is less than 36 degrees, the opening formed between the plurality of wing portions (1201) may become too small. Accordingly, the electrolyte impregnation property of the electrode assembly (11) may be reduced, and at the same time, the energy density of the secondary battery (1) may be reduced due to an increase in the volume and weight of the wing portions (1201), and the manufacturing cost of the secondary battery (1) may be increased, which may be disadvantageous.

[0111] Conversely, if the angle (θ) formed by the wings (1201) that are close to each other exceeds 44 degrees, the area of ​​the wings (1201) becomes narrow, which may reduce the weldability of the current collector body (120), and there may be an increased risk of damage to the wings (1201).

[0112] When the center of the collector body (120), i.e., the midpoint of the center (1200), is taken as the standard, and the radius of the center (1200) is R1, and the radius from the center to the inner circumference of the ring portion (1202) is R2, R2 / R1 can be 2.138 to 2.613.

[0113] When R2 / R1 is less than 2.138, the gap between the center (1200) and the ring portion (1202) becomes significantly narrow, so that during the activation process of the electrode assembly (11), a problem of reduced electrolyte impregnation of the electrode assembly (11) may occur. Conversely, when R2 / R1 exceeds 2.613, the gap between the center (1200) and the ring portion (1202) becomes significantly wide, so that the structural stability of the current collector body (120) deteriorates, and even if the current collector body (120) is welded, a problem of reduced weldability may occur.

[0114] In addition, through an experimental example, it was confirmed that when R2 / R1 is within the range of 2.138 to 2.613, the welding portion (1201a) of the current collector (12) can be welded to a portion of the end face of the electrode assembly (11) where a plurality of electrode tabs (111), preferably 10 or more electrode tabs (111), overlap.

[0115] More specifically, in the experimental example, a current collector plate (12) having R1 of 3.5 mm, R2 of 7.5 mm, and R3 of 9.5 mm was welded to the electrode assembly (11). More specifically, a current collector plate (12) having a thickness of 0.1 mm was welded by applying a 5.5 V laser for 3.2 ms while applying a pressure of 40 N toward the electrode assembly (11). As a result of performing the welding twice, the tensile strength of the welded portion was 3.53 kgf / cm. 2 , 2.66 kgf / cm 2 It was measured and confirmed to be within the normal range.

[0116] Meanwhile, when the radius from the center point (1200) to the inner circumference of the ring portion (1202) is R2, and the radius from the center point to the outer circumference of the ring portion (1202) is R3, R3 / R2 may be 1.069 to 1.306.

[0117] When R3 / R2 is less than 1.069, the width of the ring portion (1202) becomes excessively narrow, and thus the durability of the ring portion (1202) decreases, and thus the ring portion (1202) may be damaged when the current collector body (120) is welded or the secondary battery (1) is used. Conversely, when R3 / R2 exceeds 1.306, the width of the ring portion (1202) becomes significantly wide, and thus the inner space of the battery can (100) is unnecessarily occupied, which lowers the energy density of the secondary battery (1), and the space between the center portion (1200) and the ring portion (1202) becomes narrow, which may cause a problem in that the electrolyte impregnation property of the electrode assembly (11) decreases.

[0118] In addition, through an experimental example, it was confirmed that when R3 / R2 is within the range of 1.069 to 1.306, the current collector plate (12) is smoothly formed without damage to the ring portion (1202), and concentric alignment and electrolyte impregnation with respect to the electrode assembly (11) are smoothly achieved.

[0119] More specifically, in an experimental example, 6.3 g of electrolyte was injected into a housing (10) containing an electrode assembly (11) welded with a collector plate (12) having R1 of 3.5 mm, R2 of 7.5 mm, and R3 of 9.5 mm, according to a predetermined process for 610 seconds. At this time, the vacuum pressure of the vacuum chamber used for electrolyte injection was set to -0.9 kPa. Since the process of injecting electrolyte into a cylindrical battery is a well-known process, its description is omitted. As a result, it was confirmed that each electrode of the electrode assembly (11) was sufficiently impregnated with the electrolyte.

[0120] The above description is merely an example of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention.

[0121] Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of ​​the present invention but to explain it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments.

[0122] The scope of protection of the present invention should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0123] [Explanation of symbols]

[0124] 1: Secondary battery 10: Housing

[0125] 11: Electrode assembly 12: First collector plate

[0126] 13: Second collector plate 14: Gasket

[0127] 100: Battery Can 101: Top Cap

[0128] 120: Current collector body 121: Plating layer

[0129] 122: Multiple protrusions 1200: Center

[0130] 1201: Wing 1202: Ring

[0131] 110: Injection hole 1201a: Multiple welding parts

Claims

1. A housing including a battery can forming a receiving space inside and a top cap covering an open side of the battery can; An electrode assembly accommodated inside the battery can; and A current collector plate electrically connected to at least one of the battery can and the top cap, The above collector plate, A current collector body connecting at least one of the battery can or the top cap and the electrode assembly; and A secondary battery comprising a plating layer having an electrical resistance greater than the electrical resistance of the current collector body on at least a portion of the welding surface of the current collector body.

2. In paragraph 1 The above-mentioned collector body, central; and A secondary battery comprising a plurality of wing portions formed along the circumference of the central portion and spaced apart from each other at regular intervals.

3. In paragraph 2 The above electrode assembly forms a center hole formed along the length direction on the inside, A secondary battery, wherein the central portion is formed to face the center hole, and the plurality of wing portions are formed to face the end surface of the electrode assembly.

4. In paragraph 3 A secondary battery, wherein the wing portion includes a radial shape that becomes wider from the center toward the outside.

5. In paragraph 2 A secondary battery, wherein the wing portion includes a plurality of welded portions welded to at least one of the battery can and the electrode assembly.

6. In paragraph 5 A secondary battery, wherein the plurality of welding portions are formed along a radial direction based on the center.

7. In paragraph 5, A secondary battery, wherein the plurality of welding portions are formed within an area corresponding to 0.151 to 0.383 times the outer diameter of the electrode assembly in a radial direction from the center of the current collector body.

8. In paragraph 5, The end face of the above electrode assembly is provided with a plurality of electrode tabs that are folded to overlap each other, A secondary battery, wherein the plurality of welding portions are formed in a portion where the electrode tabs overlap by 10 or more.

9. In paragraph 2 The above collector plate, A secondary battery further comprising a plurality of protrusions formed protruding on one surface of the current collector body facing the inner side of the housing.

10. In paragraph 9 A secondary battery, wherein the plurality of protrusions are formed on one side of the central portion that is welded to the inner surface of the housing.

11. In paragraph 1 The main body of the collector is Goribu; A central portion located on the inner side of the above ring portion; and A secondary battery comprising a plurality of wing parts that are formed at regular intervals and connect the central portion and the ring portion.

12. In paragraph 1 A secondary battery, wherein the above-mentioned current collector body includes at least one plate among a copper plate or a clad plate in which nickel and copper are laminated.

13. In paragraph 12 A secondary battery, wherein the plating layer comprises a nickel (Nikcel) material.

14. In paragraph 12 The above clad plate is a secondary battery including a structure in which copper is laminated between nickel.

15. In paragraph 2 or paragraph 11, A secondary battery wherein the angle formed by the plurality of wing parts is 36 to 44 degrees.

16. In paragraph 11, A secondary battery, wherein, based on the center point of the center, the radius of the center point is R1, and the radius from the center point to the inner circumference of the ring part is R2, R2 / R1 is 2.138 to 2.

613.

17. In paragraph 11, A secondary battery, wherein, based on the center point of the above-mentioned center, when the radius to the inner circumference of the ring part is R2 and the radius from the center point to the outer circumference of the ring part is R3, R3 / R2 is 1.069 to 1.

306.

18. In paragraph 11, A secondary battery wherein the outer diameter of the ring portion is 1 mm to 2 mm smaller than the outer diameter of the electrode assembly.

19. A current collector body connecting at least one of the battery can or the top cap and the electrode assembly; and A current collector plate comprising a plating layer having an electrical resistance greater than the electrical resistance of the current collector body on at least a portion of the welding surface of the current collector body.

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