Secondary battery comprising cap plate and method for manufacturing secondary battery

Abstract

The present disclosure provides a secondary battery comprising a cap plate and a method for manufacturing the secondary battery. The secondary battery, according to the present disclosure, comprises: an electrode assembly formed by winding a first electrode, a separator, and a second electrode; a case accommodating the electrode assembly and an electrolyte; and a cap plate sealing an opening at one side of the case, wherein the cap plate may include an injection port for injecting the electrolyte and a seal pin for sealing the injection port.

Description

Secondary battery including a cap plate and method for manufacturing a secondary battery

[0001] The present disclosure relates to a secondary battery comprising a cap plate and a method for manufacturing the secondary battery.

[0002] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries capable of both charging and discharging. Low-capacity secondary batteries are used in small portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for motor drive systems and power storage batteries in hybrid and electric vehicles. Such secondary batteries include an electrode assembly consisting of a positive electrode and a negative electrode, a case housing the assembly, and electrode terminals connected to the electrode assembly.

[0003] Although rechargeable batteries are used in various environments due to their excellent electrical characteristics, conventional small batteries have had limitations in terms of designable energy density. Since the amount of electrical energy that can be stored is limited relative to the size and weight of the battery, there is a gradually increasing demand for large batteries with higher energy density in applications such as electric vehicles.

[0004] To increase energy capacity and density, the size of secondary batteries is gradually increased, and thin casings can be used. However, in this case, during the manufacturing process or while undergoing repeated charging and discharging over a long period, the battery cells, particularly the cap plates, may gradually deform or warp, potentially causing changes in the overall cell specifications.

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

[0006] The problem that the present invention aims to solve is to provide a secondary battery and a method for manufacturing a secondary battery to solve the above technical problem.

[0007] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems can be clearly understood by those skilled in the art from the description of the invention below.

[0008] A secondary battery according to one embodiment of the present invention for solving the above technical problem comprises an electrode assembly formed by winding a first electrode, a separator, and a second electrode, a case for housing the electrode assembly and an electrolyte, and a cap plate for sealing an opening on one side of the case, wherein the cap plate may include an injection port for injecting an electrolyte and a sealing pin for sealing the injection port.

[0009] According to one embodiment of the present disclosure, the bobby pin and the injection port can be joined by welding.

[0010] According to one embodiment of the present disclosure, the outer diameter of the bobby pin is larger than the inner diameter of the injection port, and the bobby pin can be coupled to the injection port in a press fit manner.

[0011] According to one embodiment of the present disclosure, the height of the outer surface of the bobby pin is the same as the height of the inner surface of the injection port, and the central portion of the bobby pin may include a bottom surface having a step difference with respect to the upper surface of the bobby pin.

[0012] According to one embodiment of the present disclosure, the bobby pin includes a main body portion inserted into an injection port and a flange portion that contacts the periphery of the injection port among the upper surfaces of the cap plate, and the central portion of the bobby pin may include a bottom surface having a step difference with respect to the upper surface of the bobby pin.

[0013] According to one embodiment of the present disclosure, the bobby pin includes a main body portion inserted into the injection port and a flange portion that contacts the periphery of the injection port among the upper surfaces of the cap plate, the central portion of the bobby pin includes a bottom surface having a step difference with respect to the upper surface of the bobby pin, and the injection port may include a seating portion having a step difference with respect to the upper surface of the cap plate and on which the flange portion is seated.

[0014] According to one embodiment of the present disclosure, the bobby pin may include an upper surface with a concave round shape that gradually decreases from the upper surface of the cap plate, and a lower surface with a convex round shape that gradually decreases from the lower end of the outer surface of the bobby pin.

[0015] According to one embodiment of the present disclosure, the bobby pin may include a flat upper surface having the same height as the upper surface of the cap plate, and a convex round lower surface that gradually decreases from the bottom of the outer surface of the bobby pin.

[0016] According to one embodiment of the present disclosure, the injection port is formed to penetrate polygonally from the upper surface to the lower surface of the cap plate, and the bobby pin may have an outer surface shape corresponding to the shape of the inner surface of the injection port.

[0017] According to one embodiment of the present disclosure, the injection port may include an inner wall into which a bobby pin is inserted, and a round-shaped connecting portion connected to the upper surface and the inner wall of the cap plate.

[0018] According to one embodiment of the present disclosure, the diameter of the case may be 40 mm to 50 mm.

[0019] According to one embodiment of the present disclosure, the cap plate may include a welded portion formed by bending the outer periphery of the cap plate in the direction of extension of the case and joining with the inner surface of the opening of the case.

[0020] According to one embodiment of the present disclosure, the terminal of the opening of the case may include a seating portion on which the outer periphery of the cap plate is seated.

[0021] According to one embodiment of the present disclosure, the terminal of the opening of the case may include a rounded side facing the outer periphery of the cap plate.

[0022] According to one embodiment of the present disclosure, the terminal of the opening of the case may include a round-shaped side facing the outer periphery of the cap plate and a seating portion connected to the round-shaped side and on which the outer periphery of the cap plate is seated.

[0023] A cap plate according to one embodiment of the present invention for solving a technical problem is a cap plate that seals an opening on one side of a case that accommodates an electrode assembly formed by winding a first electrode, a separator, and a second electrode, and an electrolyte, and may include an injection port for injecting an electrolyte and a sealing pin for sealing the injection port.

[0024] A method for manufacturing a secondary battery according to an embodiment of the present invention for solving a technical problem comprises the steps of: winding a first electrode, a separator, and a second electrode to form an electrode assembly; inserting the electrode assembly through an opening on one side of a case; sealing the opening of the case with a cap plate; injecting an electrolyte through an injection port of the cap plate; and sealing the injection port with a bobby pin, wherein the outer diameter of the bobby pin is larger than the inner diameter of the injection port, and the bobby pin can be joined to the injection port by press fitting and welding.

[0025] According to some embodiments of the present disclosure, in a cylindrical secondary battery, when a cap plate including a bend located at the outer periphery is inserted into a case opening, the insertability of the component may be improved by the elasticity derived from the bend structure.

[0026] According to some embodiments of the present disclosure, the problem of the accuracy of the merger between the outer diameter dimension of the cap plate and the case opening can be solved, thereby increasing the process productivity of the entire secondary battery.

[0027] According to some embodiments of the present disclosure, durability can be improved by sealing the injection port of a cap plate using a pin joined by a press fit and welding, and at the same time, the assembly productivity and sealing performance of a secondary battery cell can be increased by improving the structure of the pin.

[0028] According to some embodiments of the present disclosure, by improving the structure of a case with a new structure, particularly the structure of an opening, to correspond to the structure of a new cap plate, it is possible to extend the life of a secondary battery and at the same time provide a more standardized secondary battery cell.

[0029] However, the effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below.

[0030] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0031] FIG. 1 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0032] FIG. 2 is a plan view showing the appearance of a cap plate and a pin before joining according to one embodiment of the present disclosure.

[0033] FIGS. 3 to 7 are plan views showing a bobby pin according to one embodiment of the present disclosure.

[0034] FIG. 8 is a perspective view showing a cap plate according to one embodiment of the present disclosure.

[0035] FIG. 9 is a plan view showing the appearance of the injection port of a cap plate and the seal pin before coupling according to one embodiment of the present disclosure.

[0036] FIG. 10 is a plan view showing the appearance after the injection port of a cap plate and a bobby pin are combined according to one embodiment of the present disclosure.

[0037] FIGS. 11 and FIGS. 12 are cross-sectional views showing a cap plate and a case according to one embodiment of the present disclosure.

[0038] FIG. 13 is a cross-sectional view showing the opening of a cap plate and a case according to one embodiment of the present disclosure.

[0039] FIG. 14 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0040] FIG. 15 is a flowchart illustrating an example of a method for manufacturing a secondary battery according to the present disclosure.

[0041] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor can appropriately define the concepts of terms to best describe their invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. It should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0042] Additionally, as used herein, “comprise, include” and / or “comprising, including” specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups.

[0043] Additionally, to aid in understanding the invention, the attached drawings are not drawn to actual scale, and the dimensions of some components may be exaggerated. Furthermore, the same reference numerals may be assigned to identical components in different embodiments.

[0044] The statement that two subjects of comparison are 'identical' means that they are 'substantially identical'. Therefore, substantial identity may include deviations considered low in the industry, for example, deviations within 5%. Additionally, the statement that a parameter is uniform in a given area may mean that it is uniform from an average perspective.

[0045] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0046] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0047] The statement that any component is positioned on the "upper (or lower) side" or the "upper (or lower) side" of a component implies not only that any component is positioned in contact with the upper (or lower) surface of said component, but also that another component may be interposed between said component and any component positioned on (or below) said component. Additionally, the area between the upper and lower parts of a component depicted in the drawings, or the remaining part excluding the upper and lower parts, may be referred to as a "side" or "lateral side." Furthermore, the direction facing the internal space of the component may be referred to as the "inner side," and the direction protruding into the open external space may be referred to as the "outer side." Such relative terms, such as "upper" and "upper side," may be used to describe the relationship between components depicted in the drawings, and the present disclosure is not limited by such terms.

[0048] Spatial relative terms such as "beneath," "below," "lower," "above," and "upper" may be used herein for ease of explanation to describe the relationship between one element or feature and another element(s) or feature(s) as illustrated in the drawings. Spatially relative positions are to be understood as encompassing different orientations of the device in use or operation, in addition to the orientations depicted in the figures. For example, if the device in the drawing is inverted, an element described as "below" or "below" is understood as "above" or "upper" of another element. Thus, the term "below" may encompass both the up and down directions.

[0049] Furthermore, where one component is described as being "on," "connected to," or "coupled to" another component, it should be understood that while the components may be directly connected or coupled to each other, another component may be "interposed" between each component, or that each component may be "connected," "coupled," or "coupled" through another component.

[0050] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Additionally, the use of “may” when describing embodiments of the present disclosure relates to “one or more embodiments of the present disclosure.” Expressions such as “one or more” preceding a list of elements modify the entire list of elements and do not modify individual elements of the list.

[0051] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less, unless specifically stated otherwise.

[0052] In this specification, terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Accordingly, the first element, component, region, layer, or section discussed below may be named the second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0053] The terms used in this specification are intended to describe embodiments of the present disclosure and are not intended to limit the present disclosure.

[0054] FIG. 1 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0055] Referring to FIG. 1, a secondary battery (100) according to one embodiment of the present invention may include an electrode assembly (110) formed by winding a first electrode, a separator, and a second electrode, a case (120) that accommodates the electrode assembly (110) and an electrolyte, and a cap plate (130) that seals an opening (122) on one side of the case (120).

[0056] A cap plate (130) may be coupled to one side opening (122) of a case (120) to seal the opening (122) after the electrode assembly (110) is inserted into the case (120). The cap plate (130) may include a weld that is welded to at least a portion of the opening (122) of the case (120) to seal the case (120). The shape of the cap plate (130), the weld of the case (120), and the opening (122) will be described later in FIG. 11.

[0057] The cap plate (130) is configured to cover the opening (122) of the case (120) and seals the interior of the secondary battery (100) from the external environment to prevent leakage of electrolyte, etc., protects the internal components of the secondary battery (100) from external moisture or dust, and provides a welding area or contact area for connection to an external component (e.g., an external terminal) to electrically connect the external component and the secondary battery cell.

[0058] The cap plate (130) may include an injection port (132) for injecting an electrolyte and a seal pin (140) for sealing the injection port (132). The injection port (132) may be a hole penetrating a part of the cap plate (130). The shape of the injection port (132) and the cap plate (130) will be described later in FIG. 8.

[0059] According to one embodiment of the present disclosure, the bobby pin (140) and the injection port (132) may be joined by welding. Specifically, the inner surfaces of the bobby pin (140) and the injection port (132) may be welded using any one of ultrasonic welding, laser welding, resistance welding, TIG welding (Tungsten Inert Gas Welding), or a combination thereof. The welding method is not limited to the types of welding listed above, and various methods generally used for welding two materials may be used at the choice of those skilled in the art.

[0060] The first electrode of the electrode assembly (110) may be an electrode corresponding to a positive or negative electrode in a secondary battery. The second electrode may be an electrode corresponding to a pole opposite to the first electrode. For example, if the first electrode is a positive electrode, the second electrode may be a negative electrode. Conversely, if the first electrode is a negative electrode, the second electrode may be a positive electrode.

[0061] In one embodiment, the electrode assembly (110) is formed into a jelly roll state by sequentially stacking a first electrode, a separator, and a second electrode and then winding them. The first electrode and the second electrode each include a coated portion in which an active material is applied to both sides of a substrate formed from a thin metal plate, and an uncoated portion in which the substrate is exposed because no active material is applied. As an example, the first electrode may form a positive electrode by coating a positive active material on an aluminum (Al) substrate, and the second electrode may form a negative electrode by coating a negative active material on a copper (Cu) substrate. The first electrode, the second electrode, and the separator may be impregnated with an electrolyte (not shown).

[0062] The outer surface of the electrode assembly (110) may include a separator or a substrate layer constituting the electrode. Specifically, the outer surface of the electrode assembly (110) may be one end of a separator that extends from the separator to prevent the active material constituting the first electrode or the second electrode from being exposed to the outside. In another example, the outer surface of the electrode assembly (110) may be one end of a substrate layer formed by extending a blank portion of the substrate layer on which the active material constituting the first electrode or the second electrode is not coated.

[0063] For the purpose of explaining the invention, the secondary battery (100) in FIGS. 1 to 14 below is shown in the form of a cylindrical secondary battery, but the scope of the present disclosure is not limited thereto. The secondary battery (100) of the present invention is not limited to a cylindrical secondary battery and includes secondary batteries of any shape, such as a prismatic secondary battery, a pouch secondary battery, or a coin secondary battery.

[0064] The case (120) forms the overall exterior of the secondary battery (100) and may be formed of a conductive metal such as aluminum, aluminum alloy, stainless steel (e.g., SUS), or nickel-plated steel. Additionally, the case (120) may provide a space for accommodating the electrode assembly (110). For example, if the secondary battery (100) is a cylindrical secondary battery, the case (120) may have the shape of a cylinder. The case (120) may have a fully open opening (122) to allow the electrode assembly (110) to be inserted on one side.

[0065] A secondary battery (100) according to one embodiment of the present disclosure may further include a current collector plate (150) that electrically connects a first electrode and a cap plate (130). The shape of the current collector plate (150) will be described later in FIG. 14.

[0066] FIG. 2 is a plan view showing the appearance of a cap plate and a pin before joining according to one embodiment of the present disclosure.

[0067] Referring to FIG. 2, according to one embodiment of the present disclosure, the outer diameter (A) of the bobby pin (240) is formed to be larger than the inner diameter (B) of the injection port (232), so that the bobby pin (240) can be coupled to the injection port (232) in a press fit manner. For example, when the inner diameter (B) of the injection port (232) is 4 mm, the outer diameter (A) of the bobby pin (240) may be 4.05 mm to 4.1 mm. With such a press fit, the bobby pin (240) can be configured to maintain close contact with the injection port (232) even when the cap plate (230) moves or twists. Specifically, the inner diameter (B) of the injection port (232) may be 3.5 mm to 4.5 mm, preferably 3.9 mm to 4.1 mm, and the outer diameter (A) of the bobby pin (240) may be 3.55 mm to 4.6 mm, preferably 3.95 mm to 4.2 mm.

[0068] Here, the bobby pin (240) may be made of the same material as the cap plate (230). Through this, the bobby pin (240) can be inserted into the injection port (232) of the cap plate (230) by a press fit method, and then the boundary portion between the bobby pin (240) and the injection port (232) can be sealed and joined by welding.

[0069] According to one embodiment of the present disclosure, the height of the outer surface (242) of the bobby pin (240) may be the same as the height of the inner surface (234) of the injection port (232). For example, the height of the inner surface (234) of the injection port (232) may be 0.8 mm, which is the same as the average thickness of the cap plate (230), and the height of the outer surface (242) of the bobby pin (240) may also be 0.8 mm.

[0070] In one embodiment, the central portion (244) of the bobby pin (240) may include a bottom surface having a step difference with the upper surface of the bobby pin (240). The central portion of the bobby pin (240) will be described later in FIGS. 3 to 7.

[0071] FIGS. 3 to 7 are plan views showing the shape of a bobby pin according to one embodiment of the present disclosure.

[0072] Referring to FIG. 3, the central portion of a bobby pin (340) according to one embodiment of the present disclosure may include an upper surface (342) of the bobby pin and a bottom surface (344) having a step (346). In one embodiment, the height of the step (346) between the upper surface (342) of the bobby pin and the bottom surface (344) may be 0.05 mm to 0.2 mm. For example, the gap between the upper surface (342) and the lower surface (349) of the bobby pin (340) (corresponding to the height of the outer surface (242) in FIG. 2) may be 0.8 mm, which is the same as the average thickness of the cap plate (330), whereas the gap between the bottom surface (344) located in the center of the bobby pin (340) and the lower surface (349) may be 0.7 mm.

[0073] Referring to FIG. 4, a bobby pin (440) according to one embodiment of the present disclosure includes a main body portion (441) inserted into a liquid injection port (432) and a flange portion (448) that contacts the periphery of the liquid injection port (432) among the upper surface (434) of the cap plate (430), and the central portion of the bobby pin (440) may include a bottom surface (444) having a step (446) with the upper surface (442) of the bobby pin (440).

[0074] In one embodiment, the outer diameter of the flange portion (448) may be 0.1 mm to 0.5 mm larger than the outer diameter of the main body portion (441). For example, the outer diameter of the flange portion (448) may be 4.2 mm, and the outer diameter of the main body portion (441) may be 4.1 mm, which is 0.1 mm smaller than that. Due to the step created by the difference in outer diameter between the flange portion (448) and the main body portion (441), the bobby pin (440) may be prevented from passing through the injection port (432) and entering the interior of the case. Additionally, the welding area between the bobby pin (440) and the injection port (432) or the surrounding area may be increased by the area secured by the difference in outer diameter between the flange portion (448) and the main body portion (441). In one embodiment, the thickness of the flange portion (448) may be 0.05 mm to 0.2 mm.

[0075] In addition, the description of the configuration of the pin (440), including the bottom surface (444), is the same as the description above with reference to FIG. 3.

[0076] Referring to FIG. 5, a bobby pin (540) according to one embodiment of the present disclosure includes a main body portion (541) inserted into a liquid injection port (532) and a flange portion (548) that contacts the periphery of the liquid injection port (532) among the upper surface (534) of the cap plate (530), and the central portion of the bobby pin (540) may include a bottom surface (544) having a step (546) with the upper surface (542) of the bobby pin (540).

[0077] In one embodiment, the injection port (532) may include a seating portion (536) that has a step difference with the upper surface (534) of the cap plate (530) and on which the flange portion (548) of the bobby pin (540) is seated. Here, the thickness of the flange portion (548) is 0.05 mm to 0.2 mm, and the depth of the seating portion (536) may correspond to the thickness of the flange portion (548). Additionally, the outer diameter of the flange portion (548) may be 0.1 mm to 0.5 mm larger than the outer diameter of the main body portion (541), and the width of the seating portion (536) may correspond to the outer diameter of the flange portion (548).

[0078] In addition, the description of the configuration and function of the bobby pin (540), including the bottom surface (544), is the same as the description given above with reference to FIGS. 3 and FIGS. 4.

[0079] Referring to FIG. 6, a pin (640) according to one embodiment of the present disclosure may include an upper surface (642) with a concave round shape that gradually decreases from the upper surface (634) of the cap plate (630), and a lower surface (649) with a convex round shape that gradually decreases from the lower end of the outer surface (645) of the pin (640).

[0080] Here, the degree of protrusion of the lower side surface (649) of the pin (640) can be varied according to selection within a range where the lower side surface (649) does not come into contact with the electrode assembly. For example, the lower side surface (649) of the pin (640) may protrude 0.1 mm to 0.3 mm relative to the lower side surface (636) of the cap plate (630). Specifically, the height gap between the inflection point on the convex round-shaped lower side surface (649) and the lower side surface (636) of the cap plate (630) may be 0.1 mm to 0.3 mm. The concave round-shaped upper side surface (642) may have the same curvature as the lower side surface (649).

[0081] The concave rounded upper surface (642) and the convex rounded lower surface (649) disperse the pressure inside the case applied to the cap plate (630) or the seal pin (640), thereby preventing the seal pin (640) that seals the injection port from detaching or breaking due to the gas generated during the charging and discharging of the secondary battery.

[0082] Referring to FIG. 7, a pin (740) according to one embodiment of the present disclosure may include a flat upper surface (742) having the same height as the upper surface (734) of the cap plate (730), and a convex round lower surface (749) that gradually decreases from the bottom of the outer surface (745) of the pin (740).

[0083] In addition, the description of the configuration and function of the bobby pin (740) is the same as the description above with reference to FIG. 6.

[0084] FIG. 8 is a perspective view showing a cap plate according to one embodiment of the present disclosure.

[0085] Referring to FIG. 8, according to one embodiment of the present disclosure, the injection port (832) may be formed to penetrate in a polygonal shape from the upper side surface (834) to the lower side surface (836) of the cap plate (830). In addition, in one embodiment, the outer side surface (845) of the bobby pin (840) may have a shape corresponding to the shape of the inner side surface (838) of the injection port (832). Specifically, the shape formed by the outer side surface (845) of the bobby pin (840) may be a polygon with the same shape as the injection port (832).

[0086] In one embodiment, the injection port (832) is configured in a square, pentagon, hexagon, heptagon, octagon, nonagon, decagon, decagon, or dodecagonal shape, and the shape of the bobby pin (840) inserted according to the shape of the injection port (832) may also be the same as the shape. Since the injection port (832) and the bobby pin (840) have shapes that include angles rather than being circular, the bobby pin (840) is prevented from becoming misaligned while inserted into the injection port (832), and the fixation precision of the bobby pin (840) to the injection port (832) is improved, thereby improving weldability and safety.

[0087] According to one embodiment, the cap plate (830) may further include a notch (850) configured to break when pressure exceeding a set value is applied. Specifically, the notch (850) may function as a vent that deforms or ruptures when the internal pressure of the secondary battery exceeds a certain pressure (operating pressure) to release gas generated inside the secondary battery to the outside of the secondary battery.

[0088] The location or shape of the notch (850) may vary. For example, the cap plate (830) may include a circumferential notch (850) as shown in FIG. 8. The notch (850) may be formed continuously over the entire area along the circumferential direction of the cap plate (830), or it may be formed in multiple places spaced apart at predetermined intervals. Additionally, the notch (850) may be formed on the upper side (834) or the lower side (836) of the cap plate (830).

[0089] The longitudinal section of the injection port (832) may be rectangular or gradually narrowing wedge-shaped, but is not limited thereto. Also, the transverse section of the injection port (832) and the bobby pin (840) is depicted as a regular polygon, but is not limited thereto.

[0090] FIG. 9 is a plan view showing the appearance (901) before the connection of the injection port of a cap plate and the bobby pin according to one embodiment of the present disclosure. FIG. 10 is a plan view showing the appearance (902) after the connection of the injection port of a cap plate and the bobby pin according to one embodiment of the present disclosure.

[0091] Referring to FIG. 9 and FIG. 10, an injection port (932) according to one embodiment of the present disclosure may include an inner wall (938) into which a pin (940) is inserted, and a round-shaped connecting portion (939) connected to the upper surface (934) and the inner wall (938) of a cap plate (930).

[0092] According to one embodiment of the present disclosure, the outer diameter of the bobby pin (940) is formed to be larger than the inner diameter of the injection port (932), so that the bobby pin (940) can be coupled to the injection port (932) in a press-fit manner. Specifically, as the bobby pin (940) is inserted into the injection port (932) under pressure, it can be naturally compressed along the round-shaped connecting portion (939) and press-fitted.

[0093] FIGS. 11 and FIGS. 12 are cross-sectional views showing a cap plate and a case according to one embodiment of the present disclosure.

[0094] Referring to FIG. 11, a cap plate (1130) according to one embodiment of the present disclosure may include a welded portion (1190) formed by bending the outer periphery (1134) of the cap plate (1130) in the extension direction (D) of the case (1120) to be joined to the inner surface of the opening (1122) of the case (1120). As the outer periphery (1134) is bent, the contact area between the welded portion (1190) and the inner surface of the opening (1122) increases, allowing for a stronger weld.

[0095] Specifically, the outer diameter of the cap plate (1130) formed along the welded portion (1190) may correspond to the inner diameter of the opening (1122) of the case (1120). Even if the outer diameter of the cap plate (1130) is slightly larger than the inner diameter of the opening (1122) of the case (1120), the insertability is improved due to the bent outer periphery (1134), so the cap plate (1130) can be fitted and easily inserted.

[0096] FIG. 12 is a drawing showing the periphery of the weld (1190) of FIG. 11 in more detail. Referring to FIG. 12, the end of the opening (1122) of the case (1120) according to one embodiment may include a seating portion (1126) on which the outer periphery (1134) of the cap plate (1130) is seated.

[0097] Specifically, the length of the seating portion (1126) corresponds to the length of the weld portion (1190), and the thickness of the seating portion (1126) may be less than or equal to the thickness of the weld portion (1190). The seating portion (1126) may be formed in a circular shape that is cut along the opening (1122) of the case (1120) corresponding to the shape of the weld portion (1190) of the cap plate (1130).

[0098] Through this, the mounting portion (1126) can guide the cap plate (1130) to be fixed in close contact with the case (1120) at a predetermined position, thereby allowing it to be placed at a designed position.

[0099] In addition, the description of the configuration of the cap plate (1130), including the injection port (1132) and the notch (1138), is the same as the description given above with reference to FIG. 8.

[0100] FIG. 13 is a cross-sectional view showing the opening of a cap plate and a case according to one embodiment of the present disclosure.

[0101] Referring to FIG. 13, the end of the opening (1322) of the case (1320) according to one embodiment of the present disclosure may include a rounded side (1324) facing the outer periphery of the cap plate (1330). The cap plate (1330) can be fitted into the interior of the case (1320) along the rounded side (1324) and easily inserted.

[0102] According to one embodiment, the terminal of the opening (1322) of the case (1320) is connected to a round-shaped side (1324) and may include a seating portion (1326) on which the outer periphery of the cap plate (1330) is seated. Specifically, the seating portion (1326) may be a step formed on the inner surface of the terminal of the opening (1322) of the case (1320). The seating portion (1326) may be formed in a circular shape carved along the opening (1322) of the case (1320) corresponding to the outer periphery (1334) of the cap plate (1330).

[0103] The description of the other components is the same as the description above with reference to Fig. 12.

[0104] FIG. 14 is a cross-sectional view showing an example of a secondary battery according to one embodiment of the present disclosure.

[0105] Referring to FIG. 14, a secondary battery according to one embodiment of the present disclosure includes an electrode assembly (1410) that performs charging and discharging, a case (1420) that houses the electrode assembly (1410), a first current collector plate (1430) and a second current collector plate (1450) connected to the electrode assembly (1410), an electrode terminal (1441), a cap plate (1442), and a gasket (1460). Here, the cap plate (1442) may correspond to the cap plate described above in FIG. 1 to FIG. 13.

[0106] For example, a cap plate (1442) according to one embodiment is a cap plate (1442) that seals one side opening of an electrode assembly (1410) formed by winding a first electrode (1411a, 1411b), a separator (1413), and a second electrode (1412a, 1412b) and a case (1490) that accommodates an electrolyte, and may include an injection port for injecting an electrolyte and a seal pin (1448) for sealing the injection port.

[0107] In FIG. 14, the cap plate (1442) is shown positioned on the upper part of the secondary battery and the electrode terminal (1441) is shown positioned on the lower part of the secondary battery, but this is not limited thereto. Depending on the usage environment or requirements of the secondary battery, the cap plate (1442) and the electrode terminal (1441) may be changed to be positioned on the lower part and the upper part of the secondary battery, respectively.

[0108] The electrode assembly (1410) is formed into a cylindrical jelly roll state with an empty core by winding the first electrode (1411a, 1411b), separator (1413), and second electrode (1412a, 1412b). The first electrode (1411a, 1411b) and the second electrode (1412a, 1412b) each include a coated portion (1411a, 1412a) in which an active material is applied to both sides of a substrate formed by a thin metal plate, and an uncoated portion (1411b, 1412b) in which the substrate is exposed and the active material is not applied.

[0109] The first electrode (1411a, 1411b) may be an electrode corresponding to a positive or negative electrode in a secondary battery. The second electrode (1412a, 1412b) may be an electrode corresponding to a pole opposite to the first electrode (1411a, 1411b). For example, if the first electrode (1411a, 1411b) is a positive electrode, the second electrode (1412a, 1412b) may be a negative electrode. Conversely, if the first electrode (1411a, 1411b) is a negative electrode, the second electrode (1412a, 1412b) may be a positive electrode.

[0110] For example, the first electrode (1411a, 1411b) may be formed as a positive electrode by coating a positive active material on an aluminum (Al) substrate, and the second electrode (1412a, 1412b) may be formed as a negative electrode by coating a negative active material on a copper (Cu) substrate. The uncoated portion (1411b) of the first electrode and the uncoated portion (1412b) of the second electrode are respectively provided at both ends in the winding axis direction of the electrode assembly (1410), but electrode terminals (1441) and cases (1420) having different polarities are provided together in the same direction. A cap plate (1442) is located on the opposite side of the electrode terminal (1441).

[0111] The case (1420) is formed as a cylinder to house the electrode assembly (1410), and the electrode terminal (1441) and the cap plate (1442) are respectively provided at both ends of the case (1420) in the axial direction so as to face each other.

[0112] According to one embodiment of the present disclosure, the diameter of the case (1420) may be 40 mm to 50 mm.

[0113] The electrode terminal (1441) is connected to the first electrode (1411a, 1411b) via the first current collector plate (1430) through a rivet (1443), and the case (1420) is connected to the second electrode (1412a, 1412b) via the second current collector plate (1450). At this time, the cap plate (1442) is electrically separated from the second current collector plate (1450) and the case (1420) and does not have polarity.

[0114] An electrode terminal (1441) connected to the first electrode (1411a, 1411b) of the electrode assembly (1410) inserted into the case (1420) from the outside is installed on one side of the case. The case (1420) has a through hole (1421) that is partially open on one side.

[0115] For example, the electrode terminal (1441) may be installed in a through hole (1421) of the case (1420) in a rivet structure. To this end, the electrode terminal (1441) may be connected to a rivet (1443). One end of the rivet (1443) is welded to the first current collector plate (1430) and positioned to pass through the through hole (1421). The electrode terminal (1441) is connected to the rivet (1443) and positioned on the outside of the case (1420). The electrode terminal (1441) may be formed to protrude above the outer surface of the case (1420) around the through hole (1421) and used as an anode terminal. At this time, the first current collector plate (1430) becomes an anode current collector plate.

[0116] At this time, the first current collector plate (1430) is electrically connected to the unoccupied portion (1411b) of the first electrode through a rivet (1443) and is electrically and mechanically connected to the electrode terminal (1441). The first current collector plate (1430) is electrically connected to the electrode terminal (1441) in a structure that reduces resistance by contacting most of the unoccupied portion (1411b) of the first electrode. The rivet (1443) included in the electrode terminal (1441) is installed in a state of electrical insulation from the case (1420) while forming a hermetic structure against the electrolyte by interposing an insulator (1423) in the through hole (1421).

[0117] Here, the insulator (1423) may be made of a polymer comprising ethylene propylene rubber (EPDM), polypropylene (PP), polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), or a combination thereof.

[0118] As another example, the insulator (1423) may be made of a ceramic material including epoxy resin, alumina (Al2O3), zirconia (ZrO2), aramid fiber, Nomex, or a combination thereof. However, the material of the insulator (1423) is not limited to the materials listed above and may include various materials with excellent plasticity and insulation properties depending on the choice.

[0119] In one embodiment, the first current collector plate (1430) may include a metal plate (1431) comprising at least one bridge (1432). For example, the first current collector plate (1430) may be composed of a conductive metal, specifically a conductive metal such as nickel, aluminum, copper, silver, zinc, tin, stainless steel (e.g., SUS), or nickel-plated steel or a combination thereof (alloy). Additionally, the metal plate (1431) and the bridge (1432) constituting the first current collector plate (1430) may all be made of the same material to form a single unit.

[0120] Here, the bridge (1432) of the first collector plate (1430) can be configured to break if a current exceeding a set value flows. For example, the bridge (1432) normally operates as part of a circuit through which current flows, but if a current exceeding what is needed flows, it can act as a fuse that melts due to the heat generated to cut off the circuit.

[0121] An insulating tape (1445) may be attached to one side of the first current collector plate (1430). The insulating tape (1445) may be interposed between the first current collector plate (1430) and the case (1420) or between the uninsulated portion (1411b) of the first electrode and the case (1420) to electrically insulate each component. In one embodiment, the central portion of the insulating tape (1445) may include a perforation (1446) corresponding to the shape of a rivet (1443) so that the rivet (1443) can come into contact with the first current collector plate (1430). Additionally, the insulating tape (1445) may include a side wall (1447) to wrap around a part of the electrode assembly (1410).

[0122] Additionally, the case (1420) is provided with a fully open opening (1422) to allow the electrode assembly (1410) to be inserted on the other side. The cap plate (1442) seals the opening (1422) after the electrode assembly (1410) is inserted into the case (1420) and is electrically separated from the case (1420).

[0123] At this time, the second current collector plate (1450) is electrically connected to the non-contact portion (1412b) of the second electrode and is electrically connected to the case (1420) or the cap plate (1442). The second current collector plate (1450) is connected to the case (1420) or the cap plate (1442) in a structure that reduces resistance by contacting most of the non-contact portion (1412b) of the second electrode.

[0124] The second current collector plate (1450) includes a bottom portion (1451) welded to the non-removable portion (1412b) of the second electrode and a wing portion (1452) formed adjacent to the bottom portion (1451) and welded to the cap plate (1442). The second current collector plate (1450) is formed by cutting and bending a circular plate, and may have a plurality of bottom portions (1451) and wing portions (1452), respectively, and may be arranged alternately along the circumferential direction. In one embodiment, the wing portion (1452) may repeatedly form an axial (upward) bend and a radial (outer) bend of the electrode assembly (1410).

[0125] In one embodiment, when the uncoated portion (1412b) of the second electrode and the bottom portion (1451) of the second current collector plate (1450) are welded, the bottom portion (1451) can form a weld line in the diameter direction of the second current collector plate (1450). Thus, the bottom portion (1451) can be evenly connected along the circumferential direction in the area of ​​the uncoated portion (1412b) of the second electrode, and the wing portion (1452) can be evenly connected along the circumferential direction in the area of ​​the beading portion (1429). This enables a uniform current flow along the circumferential direction from the uncoated portion (1412b) of the second electrode to the entire area of ​​the beading portion (1429) of the case (1420).

[0126] Additionally, the second collector plate (1450) is provided with a hole (1453) in the center, so it can absorb and mitigate deformation caused by welding between the bottom part (1451) and the non-welded part (1412b) of the second electrode, as well as vibrations and shocks that may be transmitted between the wing part (1452) and the bottom part (1451). The hole (1453) may have a size within a range that can absorb vibrations and shocks without increasing current resistance between the wing part (1452) and the bottom part (1451).

[0127] The cap plate (1442) is electrically connected to the second current collector plate (1450) and installed in the opening (1422) of the case (1420) through a welding process. Due to the connection of the second current collector plate (1450), the case (1420) and the cap plate (1442) can be used as negative terminals. At this time, the second current collector plate (1450) becomes a negative current collector plate. The cap plate (1442) may have the same or similar configuration as the cap plates (130, 230, 330, 430, 530, 630, 730, 830, 930, 1130, 1330) described with reference to FIGS. 1 to 13.

[0128] The sealing tape (1490) can be attached to wrap the outer surface of the jelly roll of the electrode assembly (1410) at least once. Additionally, the electrode assembly (1410) is inserted into the case (1420) with the sealing tape (1490) attached, and the sealing tape (1490) can be positioned between the electrode assembly (1410) and the case (1420). Thus, the secondary battery assembled is prevented from moving the electrode assembly (1410) up and down or forward and backward within the case (1420), thereby preventing the separation of terminals or damage to the components, and can suppress cracks in the case (1420) or the electrode assembly (1410) caused by excessive expansion of the electrode assembly (1410) even when the electrode assembly (1410) expands due to charging and discharging.

[0129] A secondary battery according to one embodiment of the present invention may be applied to automobiles, mobile phones, and / or various types of electric devices, etc., but the present invention is not limited thereto.

[0130] FIG. 15 is a flowchart illustrating an example of a method for manufacturing a secondary battery according to the present disclosure.

[0131] A method for manufacturing a secondary battery (1500) according to one embodiment of the present invention may be disclosed by winding a first electrode, a separator, and a second electrode to form an electrode assembly (S1510). Here, the diameter of the electrode assembly may be 40 mm to 50 mm.

[0132] Subsequently, the electrode assembly can be inserted through an opening on one side of the case (S1520). Here, the diameter of the case may be 40 mm to 50 mm. According to one embodiment, the end of the opening of the case may include a seating portion on which the outer periphery of the cap plate is seated. Also, according to one embodiment, the end of the opening of the case may include a round-shaped side facing the outer periphery of the cap plate. According to another embodiment, the end of the opening of the case may include a round-shaped side facing the outer periphery of the cap plate and a seating portion connected to the round-shaped side and on which the outer periphery of the cap plate is seated.

[0133] Then, the opening of the case can be sealed with a cap plate (S1530). A cap plate according to one embodiment is a cap plate that seals an opening on one side of a case that accommodates an electrode assembly formed by winding a first electrode, a separator, and a second electrode, and an electrolyte, and may include an injection port for injecting the electrolyte and a sealing pin for sealing the injection port. Additionally, the cap plate may include a welded portion formed by bending the outer periphery of the cap plate in the direction of extension of the case to be joined to the inner surface of the opening of the case.

[0134] Afterward, the electrolyte can be injected through the injection port of the cap plate (S1540). Here, the injection port may include an inner wall into which a bobby pin is inserted, and a round-shaped connecting portion connected to the upper surface and the inner wall of the cap plate. According to one embodiment, the injection port is formed to penetrate polygonally from the upper surface to the lower surface of the cap plate, and the bobby pin may have an outer surface shape corresponding to the shape of the inner surface of the injection port.

[0135] Subsequently, the injection port can be sealed with a bobby pin (S1550). Specifically, the outer diameter of the bobby pin is larger than the inner diameter of the injection port, and the bobby pin can be attached to the injection port by a press fit. The height of the outer surface of the bobby pin is the same as the height of the inner surface of the injection port, and the central part of the bobby pin may include a bottom surface having a step difference with the upper surface of the bobby pin.

[0136] Other descriptions regarding the configuration are as described above with reference to Figures 1 to 14.

[0137] Although the present invention has been described above by means of 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 spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Since various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention without departing from it, by those skilled in the art to which the present invention belongs, the present invention is not limited by the aforementioned embodiments and attached drawings.

Claims

1. An electrode assembly formed by winding a first electrode, a separator, and a second electrode; A case accommodating the electrode assembly and electrolyte; and Cap plate for sealing one side opening of the above case Includes, The above cap plate is An injection port for injecting the above electrolyte; and A bobby pin sealing the above injection port A secondary battery including 2. In Paragraph 1, A secondary battery in which the above bobby pin and the above injection port are joined by welding.

3. In Paragraph 1, A secondary battery in which the outer diameter of the above-mentioned bobby pin is larger than the inner diameter of the above-mentioned injection port, and the above-mentioned bobby pin is coupled to the above-mentioned injection port by a press fit method.

4. In Paragraph 1, The height of the outer surface of the above-mentioned bobby pin is the same as the height of the inner surface of the above-mentioned injection port, and The central portion of the above-mentioned bobby pin includes a bottom surface having a step difference with the upper surface of the above-mentioned bobby pin, and a secondary battery.

5. In Paragraph 1, The above-mentioned pin includes a main body portion inserted into the injection port and a flange portion that contacts the periphery of the injection port among the upper surfaces of the cap plate, and The central portion of the above-mentioned bobby pin includes a bottom surface having a step difference with the upper surface of the above-mentioned bobby pin, and a secondary battery.

6. In Paragraph 1, The above-mentioned pin includes a main body portion inserted into the injection port and a flange portion that contacts the periphery of the injection port among the upper surfaces of the cap plate, and The central portion of the above bobby pin includes a bottom surface having a step difference with the upper surface of the above bobby pin, and The above injection port has a step difference with the upper surface of the cap plate and includes a seating portion on which the flange portion is seated, in a secondary battery.

7. In Paragraph 1, The above-mentioned bobby pin comprises an upper surface with a concave round shape that gradually decreases from the upper surface of the cap plate, and a lower surface with a convex round shape that gradually decreases from the lower end of the outer surface of the bobby pin. The above secondary battery.

8. In Paragraph 1, A secondary battery, wherein the above-mentioned pin comprises a flat upper surface having the same height as the upper surface of the cap plate, and a convex round lower surface that gradually decreases from the bottom of the outer surface of the pin.

9. In Paragraph 1, The above injection port is formed to penetrate polygonally from the upper surface to the lower surface of the cap plate, and The above-mentioned bobby pin is a secondary battery having an outer surface shape corresponding to the shape of the inner surface of the injection port.

10. In Paragraph 1, The above injection port comprises an inner wall into which the above pin is inserted, and a round-shaped connecting portion connected to the upper surface of the cap plate and the inner wall, in a secondary battery.

11. In Paragraph 1, A secondary battery having a case diameter of 40 mm to 50 mm.

12. In Paragraph 1, The above cap plate is, A secondary battery comprising a welded portion formed by bending the outer periphery of the cap plate in the extension direction of the case and joining with the inner surface of the opening of the case.

13. In Paragraph 12, A secondary battery in which the terminal of the opening of the above case includes a seating portion on which the outer periphery of the cap plate is seated.

14. In Paragraph 1, A secondary battery in which the terminal of the opening of the above case includes a round-shaped side facing the outer periphery of the cap plate.

15. In Paragraph 1, The terminal of the opening of the above case has a round-shaped side facing the outer periphery of the cap plate; and A secondary battery comprising a seating portion connected to the side of the above-mentioned round shape and on which the outer periphery of the above-mentioned cap plate is seated.

16. A cap plate that seals one side opening of a case accommodating an electrode assembly formed by winding a first electrode, a separator, and a second electrode, and an electrolyte, An injection port for injecting the above electrolyte; and A bobby pin sealing the above injection port A cap plate including 17. In Paragraph 16, The outer diameter of the above-mentioned bobby pin is larger than the inner diameter of the above-mentioned injection port, and The above-mentioned bobby pin is joined to the above-mentioned injection port by a press fit and welding, and the cap plate.

18. In Paragraph 16, The above injection port is formed to penetrate polygonally from the outer surface to the inner surface of the cap plate, and The above-mentioned bobby pin is a cap plate having an outer surface shape corresponding to the shape of the inner surface of the injection port.

19. In Paragraph 18, The above-mentioned pin comprises a main body portion having an outer surface shape corresponding to the shape of the inner surface of the injection port, and a flange portion in contact with the periphery of the injection port among the upper surfaces of the cap plate, a cap plate.

20. A step of forming an electrode assembly by winding the first electrode, the separator, and the second electrode; A step of inserting the above electrode assembly through an opening on one side of the case; A step of sealing the opening of the above case with a cap plate; The step of injecting an electrolyte through the injection port of the cap plate; and Step of sealing the injection port with a bobby pin Includes, The outer diameter of the above-mentioned bobby pin is larger than the inner diameter of the above-mentioned injection port, and A method for manufacturing a secondary battery, wherein the above-mentioned bobby pin is joined to the above-mentioned injection port by press fitting and welding.

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