Secondary battery

Abstract

The present disclosure relates to a secondary battery. This secondary battery includes: an electrode assembly; a case accommodating the electrode assembly; a cap plate including a cap center portion and a cap wing portion disposed around the cap center portion, the cap plate sealing an opening formed at one side of the case; and a gasket surrounding at least a portion of outer circumferential surfaces of the cap wing portion, wherein a thickness of the cap wing portion is less than a thickness of the cap center portion.

Description

secondary battery

[0001] The present disclosure relates to a secondary battery.

[0002]

[0003] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0004] Recently, active research has been conducted to improve the rapid charging and capacity of secondary batteries. To meet the demand for rapid charging technology for secondary batteries, the use of a current collector tab, which combines the substrate tabs of a secondary battery, is being considered. However, the use of such a current collector tab reduces the space required to connect the current collector tab and the terminal, thereby reducing the space available for realizing the battery capacity of the secondary battery. This is detrimental to increasing battery capacity.

[0005] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0006]

[0007] The problem that the present disclosure seeks to solve is to provide a secondary battery that solves the above-mentioned problems.

[0008] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0009]

[0010] According to one embodiment of the present invention for solving the above technical problem, a secondary battery comprises: an electrode assembly; a case accommodating the electrode assembly; a cap plate including a cap center and cap wing portions arranged around the cap center, the cap plate sealing an opening formed on one side of the case; and a gasket surrounding at least a portion of the outer peripheral surfaces of the cap wing portions, wherein the thickness of the cap wing portions may be thinner than the thickness of the cap center portion.

[0011] According to one embodiment of the present invention, the processing strain of the thickness of the cap wing portion relative to the thickness of the cap center portion may be 10% or more and 40% or less.

[0012] According to one embodiment of the present invention, the thickness remaining ratio of the cap wing portion may be 50% or more compared to the thickness of the center of the cap.

[0013] According to one embodiment of the present invention, the thickness of the center of the cap may be 0.6 to 1.4 mm.

[0014] According to one embodiment of the present invention, the notch formed at the center of the cap may be perforated at a position that is greater than or equal to 50% and less than or equal to 80% of the diameter of the cap plate.

[0015] According to one embodiment of the present invention, the thickness of the center of the cap remaining after a notch is punched in the center of the cap may be 0.3 mm or less.

[0016] According to one embodiment of the present invention, at least one of the length and thickness of the gasket can be determined based on the thickness of the cap wing portion.

[0017] According to one embodiment of the present invention, the case further includes a beading portion formed so that a gasket is seated, and the curvature of the first gasket seat portion, on which a portion of the cap wing of the gasket is seated, may be less than or equal to the curvature of the second gasket seat portion seated on the beading portion.

[0018] According to one embodiment of the present invention, the curvature of the first gasket seating portion may be 50% or less of the curvature of the second gasket seating portion.

[0019] According to one embodiment of the present invention, the gasket includes first and second gasket mounting portions; a first gasket extension portion extending along a side surface and an upper surface of a cap wing portion from one end of the first and second gasket mounting portions; and a second gasket extension portion extending along a lower surface of the cap wing portion from the other end of the first and second gasket mounting portions, wherein a length of the first gasket extension portion may be 3.7 to 4.2 mm.

[0020] According to one embodiment of the present invention, the gasket further includes a gasket central portion extending in the center direction of the gasket from the second gasket extension portion, and the ratio of the length of the first gasket extension portion to the thickness of the gasket central portion may be 7.0% or more and 8.5% or less.

[0021] According to one embodiment of the present invention, the thickness of the second gasket extension may be 0.55 to 0.65 mm.

[0022] According to one embodiment of the present invention, the ratio of the thickness of the central portion of the gasket to the thickness of the second gasket extension portion may be 46.1% or more and 54.5% or less.

[0023] According to one embodiment of the present invention, the thickness of the first gasket extension may be 0.4 to 0.55 mm.

[0024] According to one embodiment of the present invention, the ratio of the thickness of the second gasket extension to the thickness of the first gasket extension may be 70% or more and 85% or less.

[0025] According to one embodiment of the present invention, the case further includes an electrode terminal installed in an insulated state in a through hole formed on another side of the case; a first collector plate connecting a first electrode formed in the electrode assembly to the electrode terminal; and a second collector plate connecting a second electrode to a beading portion of the case on the inside of the cap plate, wherein the gasket may further include a gasket receiving groove that receives at least a portion of the second collector plate and a convex portion formed convexly on the inside.

[0026] According to one embodiment of the present invention, there is provided an electrode assembly comprising: a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; a case having one side open and accommodating the electrode assembly; a cap plate including a cap center portion and cap wing portions arranged around the cap center portion, the cap plate sealing the opening of the case; and a gasket surrounding at least a portion of the outer peripheral surfaces of the cap wing portions, wherein the thickness of the cap wing portions may be thinner than the thickness of the cap center portion.

[0027] According to one embodiment of the present invention, at least one of the length and thickness of the gasket can be determined based on the thickness of the cap wing portion.

[0028] According to one embodiment of the present invention, the gasket includes a first gasket mounting portion on which a portion of a cap wing portion is mounted; a second gasket mounting portion mounted on a beading portion; a first gasket extension portion extending along a side surface and an upper surface of the cap wing portion from one end of the first and second gasket mounting portions; and a second gasket extension portion extending along a lower surface of the cap wing portion from the other end of the first and second gasket mounting portions, wherein a length of the first gasket extension portion may be 3.7 to 4.2 mm.

[0029] According to one embodiment of the present invention, the gasket further includes an electrode terminal installed in an insulating state in a through hole formed on another side of the case; a first collector plate connecting a first electrode to the electrode terminal; and a second collector plate connecting a second electrode to a beading portion of the case on the inside of the cap plate, wherein the gasket may further include a receiving groove that receives at least a portion of the second collector plate and a convex portion formed convexly on the inside.

[0030]

[0031] According to some embodiments of the present invention, in a secondary battery, the thickness of the wing portion of the cap plate can be reduced to be thinner than the center of the cap plate, thereby reducing the total height and thickness of the gasket, thereby increasing the cell capacity of the secondary battery.

[0032] According to some embodiments of the present invention, the thickness of the gasket can be reduced by the height of the lower jaw formed at the lower portion of the gasket, thereby reducing the total height and thickness of the gasket, thereby increasing the cell capacity of the secondary battery.

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

[0034]

[0035] 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.

[0036] FIG. 1 is a cross-sectional view of a secondary battery according to one embodiment of the present disclosure.

[0037] Fig. 2 is a cross-sectional view of the case of Fig. 1 before the cap plate is joined by inserting the first gasket into the opening.

[0038] FIG. 3 is a cross-sectional view showing an example of a cap plate according to an embodiment of the present disclosure.

[0039] FIG. 4 is a perspective view showing an example of a first gasket according to the first embodiment of the present disclosure.

[0040] FIG. 5 is a cross-sectional view showing an example of a first gasket according to the first embodiment of the present disclosure.

[0041] Fig. 6 is a cross-sectional view showing an example of a state in which a cap plate is joined to an opening of a case through a first gasket.

[0042] FIG. 7 is a cross-sectional view showing an example of a conventional secondary battery and a secondary battery according to the first embodiment of the present disclosure.

[0043] FIG. 8 is a cross-sectional view showing an example of a first gasket according to a second embodiment of the present disclosure.

[0044] Fig. 9 is a cross-sectional view showing an example of a state in which a cap plate is joined to an opening of a case through a first gasket.

[0045] Figure 10 is a cross-sectional view of a secondary battery according to a second embodiment of the present disclosure.

[0046]

[0047] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of this application.

[0048] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0049] Additionally, to facilitate understanding of the invention, the attached drawings may not be drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0050] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0051] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0052] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0053] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0054] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0055] When reference is made throughout the specification to "A and / or B," this means A, B, or A and B, unless otherwise stated. In other words, "and / or" includes all or any combination of the listed items. When reference is made to "C through D," this means C or more and D or less, unless otherwise stated.

[0056] The terminology used herein is for the purpose of describing embodiments of the invention and is not intended to limit the invention.

[0057] FIG. 1 is a cross-sectional view of a secondary battery according to one embodiment of the present disclosure.

[0058] Referring to FIG. 1, a secondary battery of one embodiment may include an electrode assembly (110) that performs charging and discharging, a case (120) that houses the electrode assembly (110), a first collector plate (130) and a second collector plate (140) connected to the electrode assembly (110), an electrode terminal (150), a rivet portion (160), a cap plate (170), and a first gasket (180).

[0059] The electrode assembly (110) can be formed into a jelly roll state by sequentially stacking a first electrode (111), a separator (113), and a second electrode (112) and winding them. Each of the first electrode (111) and the second electrode (112) can include a coated portion (111a, 112a) in which an active material is applied to both sides of a substrate formed of a thin metal plate, and a non-coated portion (111b, 112b) in which the substrate is exposed because the active material is not applied.

[0060] As an example, the first electrode (111) may be formed as a positive electrode by coating a positive electrode active material on an aluminum (Al) substrate, and the second electrode (112) may be formed as a negative electrode by coating a negative electrode active material on a copper (Cu) substrate. The non-coated portions (111b, 112b) of the first and second electrodes (111, 112) are respectively provided at opposite ends in the winding axis direction of the electrode assembly (110), but electrode terminals (150) and cases (120) having different polarities in the same direction may be respectively provided to be electrically connected to the non-coated portions (111b, 112b). A cap plate (170) is positioned on the opposite side of the electrode terminal (150).

[0061] The case (120) is formed in a cylindrical shape to house the electrode assembly (110), and the electrode terminal (150) and the cap plate (170) can be provided at each of the axial ends of the case (120).

[0062] The electrode terminal (150) may be connected to the first electrode (111) through the first collector plate (130) via the rivet portion (160), and the case (120) may be connected to the second electrode (112) through the second collector plate (140). At this time, the cap plate (170) may be electrically separated from the second collector plate (140) and the case (120) and may not have polarity. Of course, it is not limited thereto, and the cap plate (170) may be configured to be electrically connected to the second collector plate (140) or the case (120) and have polarity as needed.

[0063] An electrode terminal (150) connected to a first electrode (111) of an electrode assembly (110) inserted into a case (120) from the outside may be installed on one side of the case. The case (120) may have a partially open through hole (121) on one side.

[0064] As an example, the electrode terminal (150) may be installed in a rivet structure in the through hole (121) of the case (120). For this purpose, the electrode terminal (150) may be connected to a rivet portion (160). The rivet portion (160) is welded to the first collector plate (130) at one end and is positioned to penetrate the through hole (121). The electrode terminal (150) is connected to the rivet portion (160) and is positioned on the outside of the case (120). The electrode terminal (150) may be formed to protrude beyond the outer surface of the case (120) around the through hole (121) and may be used as a positive electrode terminal. At this time, the first collector plate (130) becomes a positive electrode collector plate.

[0065] At this time, the first collector plate (130) is electrically connected to the uncoated portion (111b) of the first electrode (111) through the rivet portion (160) and is electrically and mechanically connected to the electrode terminal (150). The first collector plate (130) is electrically connected to the electrode terminal (150) in a structure that reduces resistance by contacting most of the uncoated portion (111b) of the first electrode (111). The electrode terminal (150) and the rivet portion (160) are installed in an electrically insulated state from the case (120) while forming a gastight structure with respect to the electrolyte by interposing a second gasket (123) in the through hole (121).

[0066] In one embodiment, the first collector plate (130) may include a metal plate (131) having at least one bridge (132) formed thereon. The first collector plate (130) may be formed of a conductive metal, specifically, a conductive metal such as nickel, aluminum, copper, silver, zinc, tin, stainless steel (e.g., SUS), nickel-plated steel, or a combination (alloy) thereof. In addition, the metal plate (131) and the bridge (132) constituting the first collector plate (130) may both be integrally formed of the same material.

[0067] The bridge (132) of the first collector plate (130) may be configured to be ruptured when a current exceeding a set value flows. In one embodiment, the bridge (132) normally operates as a part of a circuit through which current flows, but when an excessive amount of current flows, it may function as a fuse that melts due to the generated heat and blocks the circuit.

[0068] An insulating tape (133) may be attached to one side of the first collector plate (130). The insulating tape (133) may be interposed between the first collector plate (130) and the case (120) or between the non-conductive portion (111b) of the first electrode (111) and the case (120), and may serve to electrically insulate each component. In one embodiment, the central portion of the insulating tape (133) may include a perforation (133a) corresponding to the shape of the rivet portion (160) so that the rivet portion (160) may be in contact with the first collector plate (130). In addition, the insulating tape (133) may include a side wall (133b) so as to surround a portion of the electrode assembly (110).

[0069] Additionally, the case (120) may have a completely open opening (122) to allow the electrode assembly (110) to be inserted into the other side. The cap plate (170) may be electrically separated from the case (120) by sealing the opening (122) through the first gasket (180) after the electrode assembly (110) is inserted into the case (120).

[0070] At this time, the second collector plate (140) is electrically connected to the non-conductive portion (112b) of the second electrode (112) and is electrically connected to the case (120). The second collector plate (140) is connected to the case (120) in a structure that reduces resistance by contacting most of the non-conductive portion (112b) of the second electrode (112).

[0071] The cap plate (170) can be electrically isolated from the second collector plate (140) by hermetically contacting only the first gasket (180) and installed in the opening (122) of the case (120) through a crimping process. Due to the connection of the second collector plate (140), the case (120) can be used as a negative terminal. At this time, the second collector plate (140) becomes a negative collector plate.

[0072] The first gasket (180) surrounds at least a portion of the outer circumferential surfaces of the cap wing portion (174) (e.g., at least a portion of the upper surface, at least a portion of the side surface, and at least a portion of the lower surface) and is in hermetically contact with the cap plate (170).

[0073] In one embodiment, the thickness of the cap wing portion (174) may be set thinner than the thickness of the center portion of the cap plate (170). The total height of the first gasket (180) may be shortened compared to the conventional one by the difference between the thickness of the center portion of the cap plate (170) and the thickness of the cap wing portion (174). In addition, as the thickness of the cap wing portion (174) is reduced, the load on the cap wing portion is reduced, so that the thickness of at least a portion of the first gasket (180) may also be thinned. Accordingly, by performing a thinning process on a portion of the cap plate (170) and a portion of the first gasket (180) of the secondary battery, an additional space inside the cell can be secured, thereby increasing the cell capacity.

[0074] Fig. 2 is a cross-sectional view of the state before the cap plate (170) is joined by inserting the first gasket (180) into the opening (122) of the case (120) of Fig. 1.

[0075] Referring to FIGS. 1 and 2, the second collector plate (140) may include a bottom portion (141) welded to the non-conductive portion (112b) of the second electrode (112), a collector plate wing portion (142) formed adjacent to the bottom portion (141) and welded to the beading portion (124), and a through hole (143) provided in the center.

[0076] The second collector plate (140) can be formed by cutting and bending a circular plate. In this case, a plurality of bottom portions (141) and collector plate wing portions (142) are provided along the circumferential direction of the circular plate, and can be arranged alternately along the circumferential direction. The collector plate wing portions (142) can be formed by bending a portion of the circular plate in the axial direction (upward) and repeatedly performing bending along the radial outer side of the circular plate.

[0077] Accordingly, the bottom portion (141) is connected approximately evenly along the circumferential direction in the area of ​​the non-conductive portion (112b), and the collector plate wing portion (142) is connected approximately evenly along the circumferential direction in the area of ​​the beading portion (124). This configuration enables a uniform current flow along the circumferential direction in the entire area of ​​the beading portion (124) of the case (120) from the second electrode (112).

[0078] In addition, since the second collector plate (140) has a through hole (143) in the center, it can absorb and alleviate deformation caused by welding of the bottom portion (141) and the non-conductive portion (112b) and vibration and shock that may be transmitted between the collector plate wing portion (142) and the bottom portion (141). The through hole (143) may have a size that can absorb vibration and shock without increasing the current resistance between the collector plate wing portion (142) and the bottom portion (141). Although an embodiment in which the through hole (143) is formed in the second collector plate (140) has been described, it is not limited thereto, and the through hole (143) may not be formed in the second collector plate (140) as needed.

[0079] In addition, the case (120) may further include a beading portion (124) and a crimping portion (125). Through a beading process, the beading portion (124) is formed on the side adjacent to the opening (122) of the case (120), and through a crimping process, the crimping portion (125) connected to the beading portion (124) is formed. The second collector plate (140) connects the second electrode (112) to the beading portion (124) of the case (120).

[0080] The beading portion (124) may be formed in a structure that is sunken from the upper side of the case (120) toward the center of the diameter of the case (120) while the electrode assembly (110) is accommodated in the case (120). The beading portion (124) having this configuration prevents the up-and-down movement of the electrode assembly (110).

[0081] As an example, the beading portion (124) may have a flat portion (124b) formed parallel to a plane formed by the cross-section of the non-conductive portion (111b) on the upper side of the inwardly convex curved portion (124a). The collector plate wing portion (142) of the second collector plate (140) is welded to the flat portion (124b). Therefore, the second collector plate (140) can stably contact and be welded to the beading portion (124) and the case (120), thereby further realizing a uniform flow of current. In addition, the collector plate wing portion (142) extends further in the circumferential direction from the end than the width size connected to the bottom portion (141), thereby further increasing the contact area and welding area with the flat portion (124b), thereby preventing an increase in resistance at the welded portion.

[0082] The crimping portion (125) can be connected to the beading portion (124) in a structure that protrudes relatively more than the beading portion (124) in the diameter direction.

[0083] The first gasket (180) is used in the crimping process. After the crimping process, the first gasket (180) is interposed between the second collector plate (140) and the cap plate (170), and between the case (120) and the cap plate (170), and acts as a seal by the beading portion (124) and the crimping portion (125) connected thereto. In addition, the first gasket (180) forms a gas-tight structure with respect to the electrolyte between the second collector plate (140) and the opening (122) of the case (120).

[0084] FIG. 3 is a cross-sectional view showing an example of a cap plate (170) according to an embodiment of the present disclosure.

[0085] Referring to FIG. 3, the cap plate (170) has an overall circular shape and may include a notch (171), a first cap center portion (172), a second cap center portion (173), and a cap wing portion (174). The notch (171) is formed on the inner surface (or lower surface) of the cap plate (170), and is cut to release internal pressure during a secondary battery event to prevent a secondary explosion.

[0086] The first cap center (172) is formed concavely toward the electrode assembly (110), and the second cap center (173) is formed convexly in a direction away from the electrode assembly (110) on the diametrically outer side of the first cap center (172).

[0087] The cap wing portion (174) forms a plane that is higher than the first cap center portion (172) and lower than the second cap center portion (173) toward the electrode assembly (110) on the diametrically outer side of the second cap center portion (173).

[0088] In addition, an inner slope (175) and an outer slope (176) are formed at each of the portion where the first cap center (172) and the second cap center (173) are connected, and at each portion where the second cap center (173) and the cap wing portion (174) are connected. The inner slope (175) and the outer slope (176) can increase the rigidity of the cap plate (170) against the internal pressure of the secondary battery. As an example, the thickness (T1) of the cap wing portion (174) can be thinner than the thickness (T2) of the first cap center (172) or the second cap center (173).

[0089] A notch (171) is formed on the inner surface of at least one of the second cap center portion (173) and the outer slope (176), so that the internal pressure is concentrated during an event and the notch can be easily cut. The notch (171) may be formed continuously over the entire area along the circumference of the cap plate (170), or may be formed in multiples spaced apart at preset intervals.

[0090] [Table 1] shows the characteristics of the cap plate (170) according to an embodiment of the present disclosure.

[0091] CharacteristicsForging processing strain (Q1)10% ≤ Q1 ≤ 40%Cap wing thickness remaining rate (Q2)Q2 ≥ 50%Thickness of the center of the first or second cap (P2)0.6mm ≤ P2 ≤ 1.4mmNotch punching location (A)50% ≤ A ≤ 80%Residual thickness after notching (P3)P3 ≤ 0.3mmResidual thickness after notching (Q3)Q3 ≤ 30%

[0092] In [Table 1], the forging strain (Q1) is the ratio of the difference in thickness between the second cap center (173) and the cap wing (174) to the thickness (P2) of the second cap center (173), and may have a value of 10% or more and 40% or less compared to the thickness (P2) of the second cap center (173). As an example, the forging strain (Q1) may be calculated by [Mathematical Formula 1].

[0093]

[0094]

[0095]

[0096] In the past, the thickness of the first cap center (172) and the thickness of the cap wing portion (174) were set to be the same. In contrast, in the present disclosure, the thickness (P1) of the cap wing portion (174) is thinner than the thickness (P2) of the first cap center (172). Therefore, the forging strain (Q1) of [Mathematical Formula 1] may represent a ratio in which the thickness (P1) of the cap wing portion (174) is reduced compared to the thickness (P2) of the first cap center (172).

[0097] The cap wing thickness remaining ratio (Q2) is the ratio of the thickness (P1) of the cap wing (174) remaining compared to the original thickness after the thickness (P1) of the cap wing (174) is thinned, and may have a value of 50% or more compared to the thickness (P2) of the second cap center (173). As an example, the cap wing thickness remaining ratio (Q2) may be calculated by [Mathematical Formula 2].

[0098]

[0099]

[0100]

[0101] The sum of the forging strain (Q1) and the cap wing thickness residual ratio (Q2) can be up to 100%.

[0102] The thickness (P2) of the first cap center (172) and the second cap center (173) may be the same and may be 0.6 to 1.4 mm.

[0103] The notch (171) is formed by punching in the second cap center (173), and the position (A) at which the notch (171) is punched can be any position between 50% and 80% of the diameter of the cap plate (170). That is, the notch (171) formed in the second cap center (173) can be punched in a position that is 50% or more and 80% or less from both ends of the diameter of the cap plate (170). The notch punching position (A) can be calculated by [Mathematical Formula 3].

[0104]

[0105]

[0106]

[0107] Referring to [Mathematical Formula 3], A is a position at which a notch (171) is punched, and D1 is the length of the diameter of the cap plate (170). If the notch (171) is formed over the entire area along the circumferential direction of the cap plate (170), D2 may be the diameter of the notch (171). Alternatively, if the notches (171) are formed spaced apart along the circumferential direction of the cap plate (170), D2 may be the maximum distance between the notch (171) and another notch (not shown) (for example, the distance between two notches facing each other located at both ends of the diameter of the cap plate (170).

[0108] The residual thickness (P3) after notch processing refers to the thickness (P3) of the second cap plate (170) remaining after the notch (171) is punched at the position (A) of the center of the second cap (173). The residual thickness (P3) after notch processing may be 0.3 mm or less.

[0109] The thickness remaining rate (Q3) after notching is the thickness remaining rate of the second cap center (173) located at the upper end of the notch (171) after the notch is punched at position (A) in the second cap center (173), and may be 30% or less compared to the thickness of the second cap center (173). As an example, the thickness remaining rate (Q3) after notching can be calculated by [Mathematical Formula 4].

[0110]

[0111]

[0112]

[0113] According to one embodiment, in [Table 1], Q1 may be 30%, Q2 may be 70%, P1 may be 0.7 mm, P2 may be 1 mm, the position of A may be 63 to 73% from both ends of the diameter of the cap plate (170), P3 may be 0.18 mm, and Q3 may be 18%.

[0114] FIG. 4 is a perspective view showing an example of a first gasket (180) according to a first embodiment of the present disclosure, FIG. 5 is a cross-sectional view showing an example of a first gasket (180) according to a first embodiment of the present disclosure, and FIG. 6 is a cross-sectional view showing an example of a state in which a cap plate (170) is coupled to an opening (122) of a case (120) through a first gasket (180).

[0115] Referring to FIGS. 4 to 6, the first gasket (180) includes a first gasket mounting portion (181), a second gasket mounting portion (182), a first gasket extension portion (183), a second gasket extension portion (184), a gasket central portion (185), a gasket receiving groove (186), and a gasket convex portion (187). When the first gasket (180) illustrated in FIG. 4 is cut in the AA' direction, the second gasket extension portion (184) and the gasket central portion (185) of the first gasket (180) illustrated in FIG. 5 may appear.

[0116] A portion of the cap wing portion (174) is seated on the outer surface of the first gasket mounting portion (181), and the outer surface of the second gasket mounting portion (182) is seated on the beading portion (124). The first gasket extension portion (183) extends from one end of the first gasket mounting portion (181) and the second gasket mounting portion (182) so as to come into contact along the side and upper surfaces of the cap wing portion (174).

[0117] The second gasket extension (184) extends from the other end of the first gasket mounting portion (181) and the second gasket mounting portion (182) so as to come into contact along the lower surface of the cap wing portion (174). The gasket central portion (185) extends from the second gasket extension (184) toward the center of the first gasket (180) and is formed at the center of the first gasket (180), and the second gasket extension portions (184) are respectively connected to both sides of the gasket central portion (185).

[0118] The gasket receiving groove (186) receives the collector plate wing portion (142), and the groove is formed by the gasket convex portion (187) and the second gasket seating portion (182). That is, the gasket convex portion (187) and the second gasket seating portion (182) are formed in a chin shape on the lower surface of the second gasket extension portion (184).

[0119] The gasket receiving groove (186) reduces deformation of the first gasket (180) between the collector wing (142) and the cap plate (170) during the crimping process, thereby increasing the stability of the first gasket (180). The second gasket seating portion (182) contacts the flat portion (124b) on the radially outer side of the gasket receiving groove (186) to perform a compressive sealing action. Despite the gasket receiving groove (186), the second gasket seating portion (182) implements a sufficient sealing action between the flat portion (124b) and the cap plate (170).

[0120] The gasket receiving groove (186) is formed at a right angle on the side of the second gasket mounting portion (182) to stably receive the end of the collector plate wing (142) and prevent misalignment of the collector plate wing (142) and the first gasket (180). The gasket receiving groove (186) is formed at an obtuse angle on the radially inner side to induce engagement of the folded structure of the collector plate wing (142) and stably receive the folded structure of the collector plate wing (142). The collector plate wing (142) can be bent in response to the obtuse angle structure of the gasket receiving groove (186).

[0121] The gasket convex portion (187) is formed convexly at the lower portion of the second gasket extension portion (184) to prevent the folded structure of the collector plate wing portion (142) from being pushed toward the cap plate (170).

[0122] The second gasket extension (184) is formed corresponding to the cap wing (174) of the cap plate (170), so that the inner side of the first gasket (180), which is compressed and deformed by the crimping process, can be prevented from interfering with the second collector plate (140).

[0123] [Table 2] shows the characteristics of the first gasket (180) according to an embodiment of the present disclosure.

[0124] Characteristics of the first gasket seat and the second gasket seat Curvature design conditions R1 ≤ R2 Curvature ratio R3 ≤ 50% Total height of the first gasket (H1) 3.7 mm ≤ H1 ≤ 4.2 mm Ratio of the total height to the thickness of the center of the gasket (R4) 7.0% ≤ R4 ≤ 8.5% Thickness of the second gasket extension (bottom thickness of the first gasket, T2) 0.55 mm ≤ T2 ≤ 0.65 mm Ratio of the thickness of the second gasket extension to the center of the gasket (R5) 46.1% ≤ R5 ≤ 54.5% Thickness of the first gasket extension (side thickness of the first gasket, T3) 0.4 mm ≤ T3 ≤ 0.55 mm Ratio of the thickness of the second gasket extension to the first gasket extension (R6) 70% ≤ R6 ≤ 85%

[0125] In [Table 2], the curvature (R1) of the first gasket mounting portion (181) has a size less than or equal to the curvature (R2) of the second gasket mounting portion (182). The curvature ratio (R3) is the ratio of R1 to R2, and is as shown in [Mathematical Formula 5].

[0126]

[0127]

[0128]

[0129] According to [Mathematical Formula 5], the curvature (R1) of the first gasket mounting portion (181) is less than 50% of the curvature (R2) of the second gasket mounting portion (182).

[0130] The total height (H1) of the first gasket (180) is the length of the first gasket extension (183) based on the bottom surface of the second gasket mounting portion (182), including the thickness (T2) of the second gasket extension (184). The total height (H1) of the first gasket (180) is 3.7 to 4.2 mm.

[0131] The ratio (R4) of the total height (H1) of the first gasket (180) and the thickness (T1) of the gasket central portion (185) is the ratio of the thickness (T1) of the gasket central portion (185) to the total height (H1) of the first gasket (180), and the thickness (T1) of the gasket central portion (185) may have a value of 7% or more and 8.5% or less of the total height (H1) of the first gasket (180). As an example, the ratio (R4) may be calculated by [Mathematical Formula 6].

[0132]

[0133]

[0134]

[0135] The thickness ratio (R5) of the gasket central portion (185) and the second gasket extension portion (184) is the ratio of the thickness (T1) of the gasket central portion (185) to the thickness (T2) of the second gasket extension portion (184), and the thickness (T1) of the gasket central portion (185) may have a value of 46.1% or more and 54.5% or less of the thickness (T2) of the second gasket extension portion (184). As an example, the ratio (R5) may be calculated by [Mathematical Formula 7].

[0136]

[0137]

[0138]

[0139] In [Mathematical Formula 7], the thickness (T2) of the second gasket extension (184) may be 0.8 mm or less, and T1 may be 0.3 mm or less. T1 may also have a fixed value of 0.3 mm.

[0140] The thickness (T3) of the first gasket extension (183) may be 0.4 mm or more and 0.55 mm or less.

[0141] The thickness ratio (R6) of the second gasket extension (184) and the first gasket extension (183) is the ratio of the thickness (T3) of the first gasket extension (183) to the thickness (T2) of the second gasket extension (184), and the thickness (T3) of the first gasket extension (183) may have a value of 70% or more and 85% or less of the thickness (T2) of the second gasket extension (184). As an example, the ratio (R6) may be calculated by [Mathematical Formula 8].

[0142]

[0143]

[0144]

[0145] According to one embodiment, in [Table 2], R1 may be 0.2, R2 may be 0.5, R3 may be 40%, H1 may be 4 mm, R4 may be 7.5%, T1 may be 0.3 mm, T2 may be 0.6 mm, R5 may be 50%, T3 may be 0.5 mm, and R6 may be 83.3%.

[0146] According to one embodiment, the total height (H1) of the first gasket (180) can be shortened compared to the conventional one by the difference between the thickness (P2) of the first cap center (172) and the thickness (P1) of the cap wing portion (174). In addition, as the thickness (P1) of the cap wing portion (174) is thinned, the load of the cap wing portion (174) is reduced, and thus the thickness (T3) of the first gasket extension portion (183) and the thickness (T2) of the second gasket extension portion (184) can also be thinned compared to the conventional one. Accordingly, by performing a thinning process on a part of the cap plate (170) and a part of the first gasket (180) of the secondary battery compared to the conventional one, an additional space inside the cell can be secured, thereby increasing the cell capacity.

[0147] FIG. 7 is a cross-sectional view showing an example of a conventional secondary battery and a secondary battery according to the first embodiment of the present disclosure.

[0148] The cross-sectional view (710) of a conventional secondary battery illustrated in FIG. 7 shows a state in which a cap plate is coupled to an opening of a case (714) via a first gasket, and the thickness of the cap wing portion (711) of the cap plate and the thickness of the second cap center portion (715) are the same. Accordingly, the mating thickness (L1) of the secondary battery is formed by the sum of the thickness of the cap wing portion (711), the thickness of the first gasket extension portion (712), and the thickness of the second gasket extension portion (713).

[0149] Meanwhile, a cross-sectional view (720) of a large-diameter cell of a secondary battery according to the first embodiment of the present disclosure shows a state in which a cap plate is coupled to an opening of a case (724) via a first gasket, and the current collector wing portion (726) is received in the receiving groove of the first gasket. For example, the thickness of the cap wing portion (721) of the cap plate is thinner than the thickness of the second cap center portion (725). As the thickness of the cap wing portion (721) is thinner than that of the second cap center portion (725), the total height of the first gasket is also shortened, and the thickness of the first gasket extension portion (722) and the thickness of the second gasket extension portion (723) can also be processed to be thin. Accordingly, the mating thickness (L2) of the secondary battery is formed by the sum of the thickness of the cap wing portion (721), the thickness of the first gasket extension portion (722), and the thickness of the second gasket extension portion (723), which has a reduced length (L3) compared to the conventional mating thickness (L1), and as a result, the width of the electrode can be increased by the reduced length (L3). That is, the height of the internal space can be additionally secured by the reduced length (L3) of the mating thickness compared to the conventional one, so that the width of the electrode can be formed larger by the reduced length (L3) of the mating thickness, thereby increasing the cell capacity.

[0150] Fig. 8 is a cross-sectional view showing an example of a first gasket (800) according to a second embodiment of the present disclosure, and Fig. 9 is a cross-sectional view showing an example of a state in which a cap plate (170) is coupled to an opening (122) of a case (120) through a first gasket (180). In Figs. 8 and 9, configurations described or duplicated in Figs. 4 to 6 are omitted.

[0151] Referring to FIGS. 8 and 9, the first gasket (800) includes a first gasket mounting portion (881), a second gasket mounting portion (882), a first gasket extension portion (883), a second gasket extension portion (884), and a gasket central portion (885).

[0152] A portion of the cap wing portion (174) is seated on the outer surface of the first gasket mounting portion (881), and the outer surface of the second gasket mounting portion (882) is seated on the beading portion (124). The curvature (R3) of the first gasket mounting portion (881) and the curvature (R4) of the second gasket mounting portion (882) may be the same as the curvature (R1) of the first gasket mounting portion (181) and the curvature (R2) of the second gasket mounting portion (182) according to the first embodiment.

[0153] The first gasket extension (883) extends from one end of the first gasket mounting portion (881) and the second gasket mounting portion (882) to contact the side and upper surfaces of the cap wing portion (174).

[0154] The second gasket extension (884) extends from the other end of the first gasket mounting portion (881) and the second gasket mounting portion (882) so as to come into contact along the lower surface of the cap wing portion (174). The gasket central portion (885) extends from the second gasket extension portion (884) toward the center of the first gasket (800) and is formed at the center of the first gasket (800), and the second gasket extension portions (884) are respectively connected to both sides of the gasket central portion (885). The collector wing portion (142) is interposed between a portion of the lower surface of the second gasket extension portion (884) and the beading portion (124) during the crimping process.

[0155] As a result, the gasket convex portion (187) and the gasket receiving groove (186) in the shape of the lower jaw as shown in FIG. 4 are removed, and the thickness (T5) of the second gasket extension (884), the thickness (T4) of the gasket central portion (885), and the total height (H2) of the first gasket extension (883) can be reduced by the height of the lower jaw compared to T2, T1, and H1, respectively, and as a result, additional space for increasing the cell capacity of the secondary battery can be secured. The thickness (T6) of the first gasket extension (883) can be the same as or thinner than the thickness (T3) of the first gasket extension (183) according to the first embodiment. As an example, since the lower jaw height, i.e., the step difference between the gasket convex portion (187) and the gasket receiving groove (186), is 0.05 mm to 0.15 mm, the total height (H2) of the first gasket extension portion (881), the thickness (T5) of the second gasket extension portion (884), and the thickness (T4) of the gasket central portion (885) can be reduced by the lower jaw height. At this time, the design conditions or characteristics of the first gasket (800) can be the same as in [Table 2].

[0156] Figure 10 is a cross-sectional view of a secondary battery according to a second embodiment of the present disclosure.

[0157] Referring to FIG. 10, a large-diameter cell die (1010) of a secondary battery according to a second embodiment of the present disclosure is a state in which a cap plate is coupled to an opening of a case (1014) via a first gasket, and the thickness of the cap wing portion (1011) of the cap plate is thinner than the thickness of the second cap center portion (1015). As the thickness of the cap wing portion (1011) is thinner than that of the second cap center portion (1015), the total height of the first gasket is also shortened, and the thickness of the first gasket extension portion (1012) and the thickness of the second gasket extension portion (1013) can also be processed to be thinner. In addition, since the gasket convex portions provided on both sides of the receiving groove in which the current collector wing portion is received are removed, the thickness of the second gasket extension portion (1013) can be thinner than that of the first embodiment of the present disclosure. Accordingly, the mating thickness (L4) of the secondary battery is composed of the sum of the thickness of the cap wing portion (1011), the thickness of the first gasket extension portion (1012), and the thickness of the second gasket extension portion (1013), which has a reduced length compared to the existing mating thickness.

[0158] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. Electrode assembly; A case accommodating the electrode assembly; A cap plate including a cap center, a cap wing portion arranged around the cap center, and sealing an opening formed on one side of the case; and A gasket surrounding at least a portion of the outer surface of the cap wing portion Including, A secondary battery in which the thickness of the cap wing portion is thinner than the thickness of the center portion of the cap.

2. In paragraph 1, A secondary battery, wherein the processing strain of the thickness of the cap wing portion relative to the thickness of the center of the cap is 10% or more and 40% or less.

3. In paragraph 1, A secondary battery, wherein the thickness remaining ratio of the cap wing portion is 50% or more compared to the thickness of the center portion of the cap.

4. In paragraph 1, A secondary battery, wherein the thickness of the center of the cap is 0.6 to 1.4 mm.

5. In paragraph 1, A secondary battery, wherein the notch formed at the center of the cap is punched at a position greater than or equal to 50% and less than or equal to 80% of the diameter of the cap plate.

6. In paragraph 5, A secondary battery, wherein the thickness of the center of the cap remaining after a notch is punched in the center of the cap is 0.3 mm or less.

7. In paragraph 1, A secondary battery, wherein at least one of the length and thickness of the gasket is determined based on the thickness of the cap wing portion.

8. In paragraph 7, A beading portion formed in the case so that the gasket is seated therein. Including more, A secondary battery, wherein the curvature of the first gasket mounting portion, on which a portion of the cap wing portion is mounted, among the above gaskets, is less than or equal to the curvature of the second gasket mounting portion, on which the beading portion is mounted.

9. In paragraph 8, A secondary battery, wherein the curvature of the first gasket mounting portion is 50% or less of the curvature of the second gasket mounting portion.

10. In paragraph 8, The above gasket, The first and second gasket mounting portions; A first gasket extension extending along the side and upper surface of the cap wing portion from one end of the first and second gasket mounting portions; and A second gasket extension extending along the lower surface of the cap wing portion from the other end of the first and second gasket mounting portions. Including, A secondary battery, wherein the length of the first gasket extension is 3.7 to 4.2 mm.

11. In paragraph 10, The above gasket has a central portion of the gasket extending from the second gasket extension portion toward the center of the gasket. Including more, A secondary battery, wherein the ratio of the length of the first gasket extension to the thickness of the central portion of the gasket is 7.0% or more and 8.5% or less.

12. In paragraph 10, A secondary battery, wherein the thickness of the second gasket extension is 0.55 to 0.65 mm.

13. In paragraph 10, A secondary battery, wherein the ratio of the thickness of the central portion of the gasket to the thickness of the second gasket extension portion is 46.1% or more and 54.5% or less.

14. In paragraph 10, A secondary battery, wherein the thickness of the first gasket extension is 0.4 to 0.55 mm.

15. In paragraph 10, A secondary battery, wherein the thickness ratio of the second gasket extension to the thickness of the first gasket extension is 70% or more and 85% or less.

16. In paragraph 10, An electrode terminal installed in an insulated state in a through hole formed on the other side of the case; A first collector plate connecting the first electrode formed in the electrode assembly to the electrode terminal; and A second collector plate connecting the second electrode to the beading portion of the case on the inside of the cap plate Including more, The above gasket has a gasket receiving groove that receives at least a portion of the second collector plate, and a convex portion formed convexly on the inside. A secondary battery further comprising:

17. An electrode assembly comprising a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; A case having one side open and accommodating the electrode assembly; A cap plate including a cap center and a cap wing portion arranged around the cap center, and sealing the opening of the case; and A gasket surrounding at least a portion of the outer surface of the cap wing portion Including, A secondary battery in which the thickness of the cap wing portion is thinner than the thickness of the center portion of the cap.

18. In paragraph 17, A secondary battery, wherein at least one of the length and thickness of the gasket is determined based on the thickness of the cap wing portion.

19. In paragraph 17, The above gasket, A first gasket mounting portion on which a portion of the cap wing portion is mounted; A second gasket mounting portion that is mounted on the beading portion; A first gasket extension extending along the side and upper surface of the cap wing portion from one end of the first and second gasket mounting portions; and A second gasket extension extending along the lower surface of the cap wing portion from the other end of the first and second gasket mounting portions. Including, A secondary battery, wherein the length of the first gasket extension is 3.7 to 4.2 mm.

20. In paragraph 17, An electrode terminal installed in an insulated state in a through hole formed on the other side of the case; A first collector plate connecting the first electrode to the electrode terminal; and A second collector plate connecting the second electrode to the beading portion of the case on the inside of the cap plate Including more, The above gasket has a receiving groove that receives at least a portion of the second collector plate, and a convex portion formed convexly on the inside. A secondary battery further comprising:

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