Cap assembly, secondary battery including same, and method of manufacturing secondary battery

Abstract

The present disclosure provides a cap assembly providing improved sealing, a secondary battery including the cap assembly, and a method of manufacturing the secondary battery. The cover assembly includes: an upper cover; the safety exhaust part is arranged below the upper cover and surrounds at least one part of the edge of the upper cover; the lower cover is arranged below the safe exhaust part; an insulator between the safety exhaust part and the lower cover; and an injection molded gasket integral with the safety exhaust portion and surrounding at least a portion of an edge of the safety exhaust portion.

Description

Technical Field

[0001] This disclosure relates to a cover assembly, a secondary battery including the cover assembly, and a method for manufacturing the secondary battery. Background Technology

[0002] Unlike primary batteries, which are not designed for (re)charging, secondary (or rechargeable) batteries are designed to be discharged and recharged. Low-capacity secondary batteries are used in portable small electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for driving motors in hybrid and electric vehicles and for storing electricity (e.g., household and / or utility-scale power storage). A secondary battery typically includes an electrode assembly consisting of positive and negative electrodes, a housing that houses the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] A secondary battery can be manufactured by inserting an electrode assembly into a housing and then sealing the housing with a cover assembly. In some types of secondary batteries, the cover assembly can be secured by forming a rolled portion and a crimped portion within the housing. For example, after inserting the electrode assembly into the housing, the upper end of the housing positioned above the electrode assembly can be bent to form a rolled portion. Then, the gasket and cover assembly are placed on the rolled portion, and a crimped portion can be formed by bending the end portion of the housing to secure the gasket and cover assembly. However, during the process of forming the crimped portion, the cover assembly may be damaged, or the seal between the gasket and the cover assembly may be weak, leading to electrolyte leakage.

[0004] The information disclosed in this background section is intended to enhance the understanding of the background technology of this disclosure, and therefore may contain information that does not constitute related (or prior art). Summary of the Invention

[0005] Embodiments of this disclosure provide a cover assembly, a secondary battery including the cover assembly, and a method for manufacturing the secondary battery.

[0006] These and other aspects and features of this disclosure will be described in the following description of embodiments of this disclosure, or will be apparent from the following description of embodiments of this disclosure.

[0007] One embodiment of this disclosure provides a cover assembly, including: an upper cover; a safety vent portion below the upper cover and surrounding at least a portion of the edge of the upper cover; a lower cover below the safety vent portion; an insulator disposed between the safety vent portion and the lower cover; and an injection-molded gasket integral with the safety vent portion and surrounding at least a portion of the edge of the safety vent portion.

[0008] The safety vent may include: a main body portion below the top cover; a first portion extending upward from the main body portion; and a second portion extending inward from the first portion, the second portion contacting the upper surface of the top cover.

[0009] The safety vent may further include: a first connecting portion, wherein the main body portion and the first portion are connected to the first connecting portion; and a second connecting portion, wherein the first portion and the second portion are connected to the second connecting portion, and the outer surface of each of the first connecting portion and the second connecting portion may be curved.

[0010] At least one of the radius of curvature of the first connecting portion and the radius of curvature of the second connecting portion can be 0.4 mm to 0.8 mm.

[0011] The surfaces of the edges of the main body and / or the surfaces of the second part may be etched or grooved.

[0012] At least a portion of the surface of the edge of the main body portion, all of the surface of the first portion, and / or at least a portion of the surface of the second portion may be nano-coated to form a nano-coating.

[0013] The thickness of the nano-coating can be 5μm to 15μm.

[0014] The liner may include: a first region that contacts the main body portion of the safety vent and is spaced apart from the insulator and the lower cover below the main body portion; a second region that contacts the first portion of the safety vent and is disposed outside the first portion; and a third region that contacts the second portion of the safety vent and is disposed on the second portion.

[0015] The liner may further include an extension that extends downward from the first region and is spaced apart from the insulator and the lower cover.

[0016] The thickness of each of the first, second, and third regions of the pad can be 0.1 mm to 0.6 mm.

[0017] The thickness of the third region can be 50% of the thickness of the first region and the thickness of the second region.

[0018] The thickness of the first region and the thickness of the third region can each be 50% of the thickness of the second region.

[0019] The liner may include one or more of polybutylene terephthalate (PBT), polypropylene (PP), and perfluoroalkoxyalkane (PFA).

[0020] Another embodiment of this disclosure provides a secondary battery, comprising: a housing having an opening; an electrode assembly housed within the housing; and a cover assembly coupled to the housing to close the opening, wherein the cover assembly comprises: an upper cover; a safety vent below the upper cover and surrounding at least a portion of an edge of the upper cover; a lower cover below the safety vent; an insulator between the safety vent and the lower cover; and an injection-molded gasket integral with the safety vent and surrounding at least a portion of an edge of the safety vent.

[0021] Another embodiment of this disclosure provides a method for manufacturing a secondary battery, the method comprising: preparing a housing having an opening; preparing a cover assembly; inserting an electrode assembly into the housing; forming a rolled portion by bending a sidewall portion of the housing; placing the cover assembly on the rolled portion; and forming a crimped portion by bending an end portion of the sidewall portion, thereby sealing the opening with the cover assembly, wherein the cover assembly comprises: an upper cover; a safety vent below the upper cover and bent to surround at least a portion of the edge of the upper cover; a lower cover below the safety vent; an insulator between the safety vent and the lower cover; and a gasket integral with the safety vent and formed by injection molding, the gasket surrounding at least a portion of the edge of the safety vent.

[0022] The fabrication of the cover assembly may include: sequentially aligning and stacking the upper cover, the safety vent, the insulator, and the lower cover to form the cover assembly; inserting the cover assembly into a mold while maintaining the shape of the cover assembly; and injecting molding material into the mold to injection mold the gasket.

[0023] The safety vent may include: a main body portion disposed below the upper cover; a first portion extending upward from the main body portion; and a second portion extending inward from the first portion, the second portion contacting the upper surface of the upper cover.

[0024] The gasket can be injected and shaped to form at least a portion of the surface of the edge of the main body portion surrounding the safety vent, the entire surface of the first portion, and at least a portion of the surface of the second portion.

[0025] The fabrication of the cover assembly may further include etching or grooving the surface of the edge of the main body portion and / or the surface of the second portion.

[0026] The fabrication of the cover assembly may further include nano-coating at least a portion of the surface of the edge of the body portion, all of the surface of the first portion, and / or at least a portion of the surface of the second portion.

[0027] According to some embodiments of this disclosure, the cover assembly effectively seals the housing containing the electrode assembly, the secondary battery includes the cover assembly, and a method for manufacturing the secondary battery can be provided.

[0028] According to some embodiments of the present disclosure, the cover assembly can seal the housing to prevent electrolyte leakage from the secondary battery, the secondary battery including the cover assembly, and a method of manufacturing the secondary battery can be provided.

[0029] According to some embodiments of this disclosure, by using insert injection to form a gasket between a housing and a cover assembly housing an electrode assembly, the thickness of the gasket can be easily set, thereby improving the sealing performance and energy density of the secondary battery by controlling the thickness of the gasket.

[0030] According to some embodiments of this disclosure, when manufacturing a secondary battery, the manufacturing process can be simplified by sealing the housing with a cover assembly integrally formed with the gasket, thereby reducing manufacturing time and cost.

[0031] However, the aspects and features of this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the detailed description other aspects and features not mentioned. Attached Figure Description

[0032] The accompanying drawings illustrate embodiments of the present disclosure and, together with the detailed description of the present disclosure, further describe aspects and features of the present disclosure. Therefore, the present disclosure should not be construed as limited to the drawings.

[0033] Figure 1 A longitudinal cross-sectional view illustrating an example of a secondary battery according to an embodiment of the present disclosure.

[0034] Figure 2 An example of a safety vent and gasket for a cover assembly according to an embodiment of the present disclosure is shown.

[0035] Figure 3 An example of etching or grooving the surface of a safety vent according to an embodiment of the present disclosure is shown.

[0036] Figure 4 An example of nano-coating the surface of a safety vent according to an embodiment of the present disclosure is shown.

[0037] Figure 5 This illustrates a process for molding a gasket insert onto the edge of a safety vent according to an embodiment of the present disclosure.

[0038] Figure 6 The thickness of each region of the liner according to an embodiment of the present disclosure is illustrated.

[0039] Figure 7 The thickness of each region of the liner according to an embodiment of the present disclosure is illustrated.

[0040] Figure 8 The thickness of each region of the liner according to an embodiment of the present disclosure is illustrated.

[0041] Figure 9 A flowchart illustrating an example of a method for manufacturing a secondary battery according to an embodiment of the present disclosure.

[0042] Figure 10 A flowchart illustrating an example of an insert molding method according to an embodiment of the present disclosure. Detailed Implementation

[0043] The embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The terms or words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings, but should be interpreted in a manner consistent with the technical spirit of this disclosure, based on the principle that the inventor is capable of interpreting his / her invention in the best way possible by appropriately defining the concepts of the terms as his / her own lexicographer.

[0044] The embodiments described in this specification and the configurations shown in the figures are merely some embodiments of this disclosure and do not represent all the technical ideas, aspects, and features of this disclosure. Accordingly, it should be understood that various equivalents and modifications that can replace or modify the embodiments described herein may exist at the time of filing this application.

[0045] It will be understood that when an element or layer is referred to as being "on" another element or layer, "connected to," or "linked to" another element or layer, it can be directly on, connected to, or linked to the other element or layer, or one or more intermediary elements or layers may be present. When an element or layer is referred to as being "directly on" another element or layer, "directly connected to," or "directly linked to" another element or layer, no intermediary element or layer is present. For example, when a first element is described as being "linked" or "connected" to a second element, the first element can be directly linked to or connected to the second element, or the first element can be indirectly linked to or connected to the second element via one or more intermediary elements.

[0046] In the figures, for clarity of illustration, the dimensions of various elements, layers, etc., may be enlarged. The same reference numerals indicate the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, when describing embodiments of this disclosure, the use of "may" refers to "one or more embodiments of this disclosure." Expressions such as "at least one of" and "any one of" modify the entire column of elements, not individual elements of the column, when following a column of elements. When phrases such as "at least one of A, B, and C," "at least one of A, B, or C," "at least one selected from the group of A, B, and C," or "at least one selected from A, B, and C" are used to specify a column of elements A, B, and C, the phrase may refer to any and all suitable combinations or subsets of A, B, and C, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the term "use" may be considered synonymous with the term "utilize." As used herein, the terms “substantially,” “about,” and similar terms are used as approximate terms rather than as terms of degree, and are intended to take into account the inherent variations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art.

[0047] It will be understood that while the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, areas, layers, and / or segments, these elements, components, areas, layers, and / or segments should not be limited by these terms. These terms are used to distinguish one element, component, area, layer, or segment from another. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, area, layer, or segment discussed below may be referred to as the second element, component, area, layer, or segment.

[0048] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” and “above” may be used herein to describe the relationship between one element or feature illustrated in the figures and another element or feature. It will be understood that spatial relative terms are intended to encompass different orientations of the device in use or operation, other than those depicted in the figures. For example, if the device in the figures is flipped, an element described as “below” or “under” other elements or features would then be oriented as “above” or “above” other elements or features. Therefore, the term “below” can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptive terms used herein should be interpreted accordingly.

[0049] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to limit this disclosure. As used herein, unless the context clearly indicates otherwise, the singular form “a” is also intended to include the plural form. It will be further understood that the terms “comprising” and / or “including” as used in this specification specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0050] Furthermore, any numerical ranges disclosed and / or enumerated herein are intended to include all subranges with the same numerical precision contained within the enumerated ranges. For example, the range “1.0 to 10.0” is intended to include all subranges between (and including) the enumerated minimum value of 1.0 and the enumerated maximum value of 10.0, i.e., a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limit enumerated herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit enumerated herein is intended to include all higher numerical limits contained therein. Accordingly, the applicant reserves the right to amend this specification, including the claims, to expressly enumerate any subranges contained within the scope expressly enumerated herein.

[0051] Referring to two compared elements, features, etc., as “identical” can mean that they are “substantially the same.” Therefore, the phrase “substantially the same” can include cases with a deviation considered low in the art, such as 5% or less. Furthermore, when a parameter is said to be consistent in a given region, this can mean that it is consistent in terms of its mean.

[0052] Throughout this specification, unless otherwise stated, each element may be a single element or a plurality of elements.

[0053] Placing any element "above (or below)" or "on (below)" another element means that the element can be positioned to contact the upper (or lower) surface of the element, and the other element can be positioned between the element and any element positioned on (or below) the element.

[0054] Additionally, it will be understood that when a component is referred to as a “link,” “connect,” or “attached” to another component, these components may be directly “connected,” “linked,” or “attached” to each other, or another component may be “between” these components.

[0055] Throughout this specification, unless otherwise stated, the phrase "A and / or B" means A, B, or A and B. That is, "and / or" includes any or all combinations of the listed items. Unless otherwise stated, the phrase "C to D" means C and above and D and below.

[0056] In this disclosure, for clarity of description, the dimensions and relative dimensions of layers and regions shown in the accompanying drawings may be enlarged. In other words, the dimensions shown in the drawings are for ease of understanding and are not limiting. Throughout the specification, the same reference numerals indicate the same constituent elements.

[0057] Figure 1 A longitudinal cross-sectional view illustrating an example of a secondary battery according to an embodiment of the present disclosure.

[0058] like Figure 1 As shown, the secondary battery 100 includes an electrode assembly 110, a housing 120 therein containing the electrode assembly 110 and an electrolyte, a cover assembly 130 connected to an opening in the housing 120 to seal the housing 120, and an insulating plate 150 located inside the housing 120 between the electrode assembly 110 and the cover assembly 130. In some embodiments, the cover assembly 130 may be connected to the housing 120 to close the opening.

[0059] The electrode assembly 110 may include a diaphragm 114, a first electrode 112, and a second electrode 113, wherein the first electrode 112 and the second electrode 113 are disposed between the diaphragm 114. The electrode assembly 110 may be wound into an electrode core shape relative to the winding axis Y.

[0060] The first electrode 112 includes a first substrate and a first active material layer on the first substrate. A first lead tab 115 can extend outward from a first uncoated portion of the unpositioned first active material layer on the first substrate, and the first lead tab 115 can be electrically connected to the cover assembly 130.

[0061] The second electrode 113 includes a second substrate and a second active material layer on the second substrate. A second lead tab 116 can extend outward from a second uncoated portion of the unpositioned second active material layer on the second substrate, and the second lead tab 116 can be electrically connected to the housing 120. The first lead tab 115 and the second lead tab 116 can extend in opposite directions.

[0062] The first electrode 112 can be used as a positive electrode. In this embodiment, the first substrate can be made of, for example, aluminum foil, and the first active material layer can include, for example, a transition metal oxide. The second electrode 113 can be used as a negative electrode. In this embodiment, the second substrate can be made of, for example, copper foil or nickel foil, and the second active material layer can include, for example, graphite.

[0063] The diaphragm 114 prevents a short circuit between the first electrode 112 and the second electrode 113 while allowing lithium ions to move between them. The diaphragm 114 can be made of, for example, a polyethylene membrane, a polypropylene membrane, or a polyethylene-polypropylene membrane.

[0064] The housing 120 houses the electrode assembly 110 and, together with the cover assembly 130, forms the appearance of the secondary battery 100. The housing 120 may have a substantially cylindrical body portion 124 and a bottom portion 122 connected to one side (e.g., one end) of the body portion 124. An inwardly deformed rolled portion (e.g., a coil) 126 may be formed in the body portion 124, and an inwardly bent crimped portion (e.g., a crimp member) 128 may be formed at the open end of the body portion 124.

[0065] The crimping portion 126 reduces or prevents movement of the electrode assembly 110 within the housing 120 and facilitates the placement of the gasket 139 and the cover assembly 130. The crimping portion 128 presses the edges of the cover assembly 130 to securely fasten it. The housing 120 may be made of, for example, nickel-plated iron. In some embodiments, the housing 120 may be made of steel, steel alloy, aluminum, or aluminum alloy.

[0066] According to this embodiment, the cover assembly 130 may include an upper cover 132, a safety vent 134 disposed below the upper cover 132 and bent to surround at least a portion of the edge of the upper cover 132, a lower cover 138 disposed below the safety vent 134, an insulator 136 disposed between the safety vent 134 and the lower cover 138, and a gasket 139 integrally formed by injection molding to surround at least a portion of the edge of the safety vent 134. The insulator 136 may be inserted between the safety vent 134 and the lower cover 138 to isolate a portion of the safety vent 134, except for its central portion, from contact with the lower cover 138. The gasket 139 may insulate the cover assembly 130 from the housing 120. The safety vent 134 may have a central portion that contacts the lower cover 138 and a portion spaced apart from the lower cover 138 and supported by the insulator 136. A notch may be formed in the safety vent 134 such that the notch can rupture when the internal pressure exceeds a certain pressure, thereby allowing gas to escape from the battery.

[0067] The insulating plate 150 may be positioned below the coiled portion 126 to contact the electrode assembly 110. The insulating plate 150 may have a first lead tab 115 extending through its lead tab opening. The cover assembly 130, electrically connected to the first electrode 112 via the first lead tab 115, may face the electrode assembly 110 (with the insulating plate 150 between them) and may be kept insulated (e.g., electrically insulated) from the electrode assembly 110 by the insulating plate 150.

[0068] An electrolyte is injected within the housing 120, and it serves to allow lithium ions generated by electrochemical reactions in the positive and negative electrodes to move during charging / discharging. The electrolyte may be a non-aqueous organic electrolyte, a mixture of lithium salt and a high-purity organic solvent. In some embodiments, the electrolyte may be a polymer formed from a high molecular weight electrolyte or a solid electrolyte. However, the type of electrolyte is not limited to these examples.

[0069] Figure 2 An example is shown of the area of ​​the safety vent and the area of ​​the liner of a cover assembly according to an embodiment of the present disclosure.

[0070] refer to Figure 2 The cover assembly 130 may include an upper cover 132, a safety vent 134 disposed below the upper cover 132 and bent to surround at least a portion of the edge of the upper cover 132, a lower cover 138 disposed below the safety vent 134, an insulator 136 disposed between the safety vent 134 and the lower cover 138, and a gasket 139 integrally formed by injection molding to surround at least a portion of the edge of the safety vent 134. Figure 2 The cover assembly 130 shown can correspond to Figure 1 The cover assembly 130 of the secondary battery 100 shown.

[0071] The top cover 132 may have electrode terminals with an upwardly projecting central portion for electrical connection to an external device. In some embodiments, the top cover 132 may be a positive terminal. A plurality of through holes (not illustrated) formed in the top cover 132 may allow internal gases to escape to the outside of the battery in the event of abnormal internal pressure in the housing 120 due to overcharging or the like. The material of the top cover 132 may include aluminum or an aluminum alloy, but this disclosure is not limited thereto.

[0072] Safety vent 134 may be disposed below the upper cover 132. Safety vent 134 may contact (e.g., in close contact), engage, or connect with the lower portion of the upper cover 132. For example, safety vent 134 may contact (e.g., in close contact), engage, or connect with the edge of the upper cover 132 rather than the central portion projecting upward from the upper cover 132. The material of safety vent 134 may include aluminum or an aluminum alloy, but this disclosure is not limited thereto.

[0073] The safety vent 134 may further include a notch 144 formed to a predetermined depth on its upper surface. The notch 144 may be located at a position corresponding to the through-hole 148 of the lower cover 138. Accordingly, when the internal pressure of the secondary battery exceeds a reference pressure, the notch 144 may rupture due to gas pressure, thus allowing the internal gas of the housing 120 to be released to the outside of the battery through the through-hole of the upper cover 132, thereby making the secondary battery safer.

[0074] According to this embodiment, the safety vent 134 may include a main body portion 134a disposed below the upper cover 132, a first bent portion (also referred to as the first portion) 134b that bends upward from the main body portion 134a, and a second bent portion (also referred to as the second portion) 134c that bends inward from the upper portion of the first bent portion 134b (or in the radial center direction) and contacts the upper surface of the edge of the upper cover 132. In some embodiments, the second bent portion 134c may extend inward from the first bent portion 134b and contact the upper surface of the upper cover 132.

[0075] According to this embodiment, the main body portion 134a is disposed below the upper cover 132 and has a protrusion that protrudes downward from the center of the upper cover 132 to contact the lower cover 138. In some embodiments, the main body portion 134a may contact the lower surface of the edge of the upper cover 132.

[0076] According to this embodiment, the first bent portion 134b can be bent upward from the edge of the main body portion 134a to surround the edge of the upper cover 132. That is, the inner surface of the first bent portion 134b can face and contact the outer surface of the edge of the upper cover 132. In some embodiments, the inner surface of the first bent portion 134b can face the outer surface of the edge of the upper cover 132 and be spaced apart from the outer surface of the edge of the upper cover 132 by a predetermined distance.

[0077] The second bend 134c can be bent horizontally inward from the upper portion of the first bend 134b and extend to cover at least a portion of the upper surface of the edge of the cover 132. The second bend 134c can contact the upper surface of the edge of the cover 132. That is, the safety vent 134 can be connected to the cover 132 by utilizing the first bend 134b and the second bend 134c around the edge of the cover 132. Accordingly, the seal at the edge of the cover assembly 130 is improved, which prevents electrolyte leakage from the secondary battery.

[0078] An insulator 136 may be disposed between the edge of the safety vent 134 and the edge of the lower cover 138. The insulator 136 may insulate the lower cover 138 from the safety vent 134 when the safety vent 134 deforms due to internal gas. The insulator 136 may be made of a resin material such as polyethylene (PE), polypropylene (PP), or polyethylene terephthalate (PET).

[0079] The gasket 139 can be injection molded to integrally form and attach to at least a portion of the cover assembly 130. For example, the gasket 139 can be integrally formed with the edge of the safety vent 134 of the cover assembly 130. In some embodiments, the gasket 139 can be integral with the safety vent 134. This will be referenced to... Figure 5Detailed description.

[0080] The gasket 139 may include a first region 139a that contacts the main body portion 134a of the safety vent 134 and is spaced apart from the insulator 136 and the lower cover 138 below the main body portion 134a. In some embodiments, the gasket 139 may include a second region 139b that contacts a first bent portion 134b of the safety vent 134 and is disposed outside the first bent portion 134b. In some embodiments, the gasket 139 may include a third region 139c that contacts a second bent portion 134c of the safety vent 134 and is disposed on the second bent portion 134c.

[0081] According to an embodiment, a first region 139a is disposed below the main body portion 134a and can contact the lower surface of the edge of the main body portion 134a of the safety vent 134. Furthermore, the first region 139a is spaced a predetermined distance from the insulator 136 and the lower cover 138.

[0082] The second region 139b may extend upward from the edge of the first region 139a to surround the first bent portion 134b of the safety vent 134. The inner surface of the second region 139b may face and contact the outer surface of the first bent portion 134b of the safety vent 134.

[0083] According to this embodiment, the third region 139c can extend horizontally inward from the upper portion of the second region 139b, and the third region 139c covers at least a portion of the upper surface of the second bent portion 134c of the safety vent 134. The third region 139c can extend inward and contact the upper surface of the second bent portion 134c of the safety vent 134. For example, the gasket 139 can be attached to the safety vent 134 by utilizing the second region 139b and the third region 139c around the edge of the safety vent 134. Accordingly, after the cover assembly 130, in which the gasket 139 is integrally formed, is disposed on the rolled portion 126 of the housing 120, the housing 120 can be sealed even with a small compressive force during the process of bending the end portion of the side wall portion of the housing 120 (i.e., in the crimping process). Since the compressive force applied to the cover assembly 130 is reduced, the deformation of the constituent elements of the cover assembly 130 is reduced, thereby avoiding defects in the secondary battery. In some embodiments, when manufacturing a secondary battery, a cover assembly 130 integrally formed with the gasket 139 is used to seal the housing 120, thereby simplifying the secondary battery manufacturing process and reducing manufacturing time and cost.

[0084] According to an embodiment, the gasket 139 may further include an extension 139d extending downward from the first region 139a and spaced apart from the insulator 136 and the lower cover 138. When the housing 120 is deformed due to an impact, the extension 139d can prevent the housing 120 and the lower cover 138 from contacting and causing a short circuit.

[0085] Figure 3 An example is shown of etching or slotting the surface of a safety vent according to an embodiment of the present disclosure, and Figure 4 An example of nano-coating the surface of a safety vent according to an embodiment of the present disclosure is shown.

[0086] refer to Figure 3 The safety vent 134 may include a main body portion 134a and a first bending portion 134b connected to a first connecting portion r1, and a first bending portion 134b and a second bending portion 134c connected to a second connecting portion r2. As shown in the figure, the outer surface of each of the first connecting portion r1 and the second connecting portion r2 may be curved.

[0087] According to an embodiment, at least one of the radius of curvature of the first connecting portion r1 and the radius of curvature of the second connecting portion r2 of the safety vent 134 can be 0.4 mm to 0.8 mm. With this configuration, when the molded gasket 139 is injected at the edge of the safety vent 134, the connecting portion can be integrally formed without any gap between the gasket 139 and the safety vent 134.

[0088] In the safety vent 134, the surface of the edge of the main body portion 134a and / or the surface of the second bent portion 134c may be etched or grooved to form a rough portion 135. Similarly, the surface of the first bent portion 134b may be etched or grooved to form a rough portion 135.

[0089] More specifically, the surface of the safety vent 134 can be roughened with a roughened portion 135 using a laser etching process, and the roughened portion 135 can be formed using a mold in a grooving process. The surface of the safety vent 134 can be further textured using either etching or grooving processes. With this configuration, when a molded gasket 139 is injected at the edge of the safety vent 134, the bonding strength and sealing performance between the gasket 139 and the safety vent 134 can be improved.

[0090] refer to Figure 4At least a portion of the surface of the main body portion 134a (e.g., the surface of the edge of the main body portion 134a), the entire surface of the first bent portion 134b, and / or at least a portion of the surface of the second bent portion 134c can be nano-coated to form a nano-coating 137. For example, the nano-coating 137 can be formed by nano-coating a portion of the surface of the main body portion 134a and a portion of the surface of the second bent portion 134c. The nano-coating 137 can be formed by coating nanoparticles using chemical vapor deposition and / or liquid phase synthesis methods.

[0091] Table 1 below shows the results of measuring the sealing pressure between the gasket 139 and the safety vent 134 relative to the thickness of the nano-coating 137. To reduce the amount of error in the data, the sealing pressure was measured three times for each thickness of the nano-coating 137.

[0092] Table 1

[0093] thickness of nano coating 0μm 5~10μm 10~15μm <![CDATA[Sealing pressure 1 (kgf / cm 2 )]]> 18 25 30 <![CDATA[Sealing pressure 2 (kgf / cm 2 )]]> 20 26 30 <![CDATA[Sealing pressure 3 (kgf / cm 2 )]]> 21 27 30

[0094] The thickness of the nano-coating 137 can be set by taking into account the sealing pressure between the gasket 139 and the safety vent 134. For example, as shown in Table 1, the sealing pressure increases with the increase of the thickness of the nano-coating 137, so the thickness of the nano-coating 137 can be set to 5 μm to 15 μm. Accordingly, when the gasket 139 is injected and molded onto the nano-coating 137 of the safety vent 134, the seal between the gasket 139 and the safety vent 134 can be improved.

[0095] Figure 5 This illustrates a process for molding a gasket insert onto the edge of a safety vent according to an embodiment of the present disclosure.

[0096] refer to Figure 5 As described above, the cover assembly 130 may include an upper cover 132, a safety vent 134, an insulator 136, and a lower cover 138. A gasket 139 may be integrally formed with the cover assembly 130 by injection molding. Specifically, the gasket 139 may be integrally formed with the edge of the safety vent 134 of the cover assembly 130 by insert injection molding.

[0097] Insert injection molding of the gasket 139 can be performed by inserting the cap assembly 130 into the mold 180, injecting plastic resin, and cooling / curing the injected plastic resin to integrate the gasket 139 with the cap assembly 130. The mold 180 may include an injection port 180a, an upper mold 180b, and a lower mold 180c. The injection port 180a may be formed as a through-hole connected to the outside of the mold 180 for injecting plastic resin. The upper mold 180b may form an area for providing the upper cap 132, and the lower mold 180c may form an area for providing the lower cap 138. The injection port 180a and the cavity connected to the injection port 180a may be formed by the upper mold 180b and the lower mold 180c, and the shape of the gasket 139 may be determined according to the shape of the cavity.

[0098] According to embodiments, the plastic resin used for insert injection can be based on molding considerations. Thermoplastics that melt at high temperatures are suitable for molding. In particular, the material of the liner can include one or more of polybutylene terephthalate (PBT), polypropylene (PP), and perfluoroalkoxyalkane (PFA). Polybutylene terephthalate (PBT) is a thermoplastic that exhibits excellent flowability during molding, making it suitable for manufacturing delicate parts. After molding, PBT has high durability, high strength, and high heat resistance, and is therefore stable at high temperatures. In some embodiments, PBT has excellent electrical insulation properties, which can facilitate insulation between the housing 120 and the cover assembly 130 when PBT is used as the material for the liner 139. Polypropylene (PP) is a thermoplastic with excellent processability. After molding, PP has excellent chemical resistance, low moisture absorption, and excellent electrical insulation properties. Therefore, PP can facilitate insulation between the housing 120 and the cover assembly 130 when used as the material for the liner 139. Perfluoroalkoxyalkanes (PFAs) are thermoplastics with excellent processing properties. After molding, PFAs can possess excellent chemical, electrical, and mechanical properties.

[0099] Due to these characteristics, the gasket 139, formed by insert injection, can easily adhere to the edge of the safety vent 134. As a result, the housing 120 can be sealed with small compressive forces during the process of bending the end portion of the sidewall of the housing 120 (e.g., in a crimping process). In this embodiment, because the gasket 139 is formed by insert injection, it provides an excellent seal between the gasket 139 and the edge of the safety vent 134, regardless of the thickness of the edge of the safety vent 134.

[0100] Figure 6 The thickness of each region of the liner according to an embodiment of the present disclosure is illustrated.

[0101] refer to Figure 6The thicknesses t1, t2, and t3 of the first to third regions 139a to 139c of the gasket 139 can be set taking into account the sealing performance and energy density of the secondary battery. As the thicknesses t1, t2, and t3 of the first to third regions 139a to 139c of the gasket 139 decrease, the energy density of the secondary battery can increase, but the sealing performance may decrease. Conversely, as the thicknesses t1, t2, and t3 of the first to third regions 139a to 139c of the gasket 139 increase, the energy density of the secondary battery may decrease, but the sealing performance may improve.

[0102] According to an embodiment, the thicknesses t1, t2, and t3 of the first to third regions 139a to 139c of the gasket 139 can be from 0.1 mm to 0.6 mm. By setting the thicknesses t1, t2, and t3 of the first to third regions 139a to 139c of the gasket 139 within such a range, sufficient sealing can be achieved to prevent electrolyte leakage in the secondary battery, while also improving the energy density of the secondary battery.

[0103] Figure 7 The thickness of each region of the liner according to an embodiment of the present disclosure is illustrated.

[0104] refer to Figure 7 The thickness t3 of the third region 139c of the pad 139 can be less than the thickness t1 of the first region 139a and the thickness t2 of the second region 139b. The thickness t1 of the first region 139a and the thickness t2 of the second region 139b of the pad 139 can be approximately the same. In particular, the thickness t3 of the third region 139c of the pad 139 can be 50% of the thickness t1 of the first region 139a and the thickness t2 of the second region 139b. Figure 6 Compared to the previous embodiment, the thickness t1 of the first region 139a and the thickness t2 of the second region 139b of the pad 139 are increased, therefore Figure 7 The embodiments depicted can have improved sealing performance. Therefore, electrolyte will not leak from the housing 120. In some embodiments, the thickness t3 of the third region 139c of the gasket 139 is... Figure 6 The same principles are maintained in the embodiments, thereby maintaining the energy density of the secondary battery 100.

[0105] Figure 8 The thickness of each region of the liner according to an embodiment of the present disclosure is illustrated.

[0106] refer to Figure 8The thickness t1 of the first region 139a and the thickness t3 of the third region 139c of the pad 139 can be less than the thickness t2 of the second region 139b. The thickness t1 of the first region 139a and the thickness t3 of the third region 139c of the pad 139 can be approximately the same. Specifically, the thickness t1 of the first region 139a and the thickness t3 of the third region 139c of the pad 139 can be 50% of the thickness t2 of the second region 139b. Figure 6 Compared to the previous embodiment, in Figure 8 In the embodiment depicted, only the thickness t2 of the second region 139b of the pad 139 is increased, thereby allowing the secondary battery to be manufactured without changing the outer diameter of the casing. As a result, the manufacturing time and cost of the secondary battery can be reduced. Figure 6 Compared to the previous embodiment, the thickness t1 of the first region 139a and the thickness t3 of the third region 139c of the pad 139 are reduced, thereby maintaining the energy density of the secondary battery 100. However, it should be noted that the thickness of each region of the pad in this disclosure is not limited to... Figures 6 to 8 The embodiment shown.

[0107] Figure 9 This is a flowchart of a method for manufacturing a secondary battery according to an embodiment of the present disclosure.

[0108] The method of manufacturing a secondary battery (S900) may include preparing a cylindrical housing having an opening on one side and a cover assembly that seals the opening (S910). Here, as described above, the cover assembly may include: an upper cover; a safety vent disposed below the upper cover and bent to surround at least a portion of the edge of the upper cover; a lower cover disposed below the safety vent; an insulator disposed between the safety vent and the lower cover; and a gasket integrally formed by injection molding to surround at least a portion of the edge of the safety vent.

[0109] In an embodiment, fabricating the cover assembly with a sealed opening (S910) may include: forming the cover assembly by sequentially aligning and stacking an upper cover, a safety vent, an insulator, and a lower cover; inserting the cover assembly into a mold while maintaining the shape of the cover assembly; and injecting a gasket injection molding material into the mold to inject molding a gasket around the edge of the cover assembly. This will refer to Figure 10 Detailed description.

[0110] The electrode assembly can be inserted into the housing (S920). In some embodiments, a rolled portion can be formed by bending a side wall portion of the housing (S930). Thereafter, a cover assembly can be placed on the rolled portion of the housing (S940). Finally, the end portion of the side wall portion of the housing can be bent to form a crimped portion, thereby sealing the opening using the cover assembly (S950).

[0111] As a comparative example of this disclosure, it can be assumed that after the gasket is placed on the rolled portion of the housing and the cover assembly is placed on the gasket, the end portion of the sidewall portion of the housing and the gasket are bent. In this case, the gasket and the cover assembly can be formed separately. In the comparative example, during the process of bending the end portion of the sidewall portion of the housing, an increased compressive force may be applied to the cover assembly to additionally bend the gasket. In this case, during the process of bending the end portion of the sidewall portion of the housing, the constituent elements of the cover assembly may deform. As a result, defects may exist in the secondary battery.

[0112] According to an embodiment, after the cover assembly, in which the gasket is integrally formed, is placed on the rolled portion of the housing, the end portion of the sidewall portion of the housing can be bent. Because no additional force is required for bending the gasket, a lower compressive force can be applied to the cover assembly during the process of bending the end portion of the sidewall portion of the housing. Accordingly, deformation of the constituent elements of the cover assembly can be reduced, thereby reducing defects in the secondary battery. In some embodiments, using the cover assembly 130 integrally formed with the gasket 139 simplifies the secondary battery manufacturing process, thereby reducing manufacturing time and cost.

[0113] Figure 10 This is a flowchart illustrating an example of an insert molding method according to an embodiment of the present disclosure. The insert injection method (S1000) may be... Figure 9 The sub-step of preparing the cover assembly with a sealed opening (S910).

[0114] The insert injection method (S1000) may include sequentially aligning and stacking a top cover, a safety vent, an insulator, and a bottom cover to form a cover assembly (S1010). Here, the safety vent may include a main body portion disposed below the top cover, a first bent portion bending upward from the main body portion, and a second bent portion bending inward from the upper portion of the first bent portion, wherein the second bent portion contacts the upper surface of the edge of the top cover.

[0115] Subsequently, the cover assembly can be inserted into the mold while maintaining its shape (S1020). Then, a liner surrounding the edge of the cover assembly can be injection molded by injecting liner injection molding material into the mold (S1030). Injecting liner surrounding the edge of the cover assembly by injecting liner injection molding material into the mold (S1030) can include injection molding the liner to at least a portion of the surface surrounding the edge of the main body portion of the safety vent, the entire surface of the first bent portion, and at least a portion of the surface of the second bent portion.

[0116] In an embodiment, insert injection molding of the gasket can be performed by inserting a cap assembly into a mold, injecting plastic resin, and then cooling / curing the injected plastic resin to integrate the gasket with the cap assembly in the mold. The mold may include an injection port, an upper mold, and a lower mold. The injection port may be formed as a through-hole for injecting plastic resin. The upper mold may form a region for positioning the upper cap, and the lower mold may form a region for positioning the lower cap. The injection port and the cavity connected to the injection port may be formed by the upper and lower molds, and the shape of the molded gasket may be the shape of the cavity.

[0117] As discussed above, the injection molding material used for insert injection can be selected based on the molding process, and thermoplastics that melt at high temperatures can be suitable. As an example, the material of the insert may include one or more of polybutylene terephthalate, polypropylene, and perfluoroalkoxyalkanes.

[0118] In one embodiment, fabricating the cover assembly for sealing the opening may include etching or grooving the surface of the edge of the main body portion of the safety vent and / or the surface of the second bent portion. Furthermore, in another embodiment, fabricating the cover assembly for sealing the opening may include nano-coating at least a portion of the surface of the edge of the main body portion of the safety vent, all of the surface of the first bent portion, and / or at least a portion of the surface of the second bent portion.

[0119] Figure 9 and Figure 10 The flowcharts and descriptions above are merely examples of this disclosure, and the scope of this disclosure is not limited to... Figure 9 and Figure 10 The flowchart and the above description are as follows. For example, one or more steps in the flowchart and the above description can be added, modified, or deleted; the order of one or more steps can be changed; and multiple steps can be executed simultaneously.

[0120] While this disclosure has been described above with reference to embodiments thereof, it is not limited thereto. Various modifications and variations can be made to it within the spirit of this disclosure by those skilled in the art.

[0121] Explanation of reference numerals in the attached figures

[0122] 100: Secondary battery

[0123] 110: Electrode assembly

[0124] 120: Casing

[0125] 130: Cover component

[0126] 132: Top Cover

[0127] 134: Safety Exhaust Unit

[0128] 134a: Main body

[0129] 134b: First bend

[0130] 134c: Second bend

[0131] r1: First connection part

[0132] r2: Second connection part

[0133] 136: Insulator

[0134] 138: Bottom Cover

[0135] 139: Padding

[0136] 139a: First Region

[0137] 139b: Second Region

[0138] 139c: Third Region

[0139] 139d: Extension

Claims

1. A cover assembly comprising: an upper cover; a safety vent portion below the upper cover and surrounding at least a portion of an edge of the upper cover; a lower cover below the safety vent portion; an insulator between the safety vent portion and the lower cover; and an injection-molded gasket integral with the safety vent portion and surrounding at least a portion of an edge of the safety vent portion. 2.The cover assembly of claim 1, wherein the safety vent portion comprises: a main portion below the upper cover; a first portion extending upward from the main portion; and a second portion extending inward from the first portion, the second portion in contact with an upper surface of the upper cover. 3.The cover assembly of claim 2, wherein the safety vent portion further comprises: a first connecting portion to which the main portion and the first portion are connected; and a second connecting portion to which the first portion and the second portion are connected, and wherein an outer surface of each of the first connecting portion and the second connecting portion is curved. 4.The cover assembly of claim 3, wherein at least one of a radius of curvature of the first connecting portion and a radius of curvature of the second connecting portion is 0.4 mm to 0.8 mm. 5.The cover assembly of claim 2, wherein a surface of the main portion and / or a surface of the second portion is etched or slotted. 6.The cover assembly of claim 2, wherein at least a portion of a surface of an edge of the main portion, all of a surface of the first portion, and / or at least a portion of a surface of the second portion is nano-coated to form a nano-coating. 7.The cover assembly of claim 6, wherein a thickness of the nano-coating is 5 μm to 15 μm. 8.The cover assembly of claim 2, wherein the gasket comprises: a first region in contact with the main portion of the safety vent portion and spaced apart from the insulator and the lower cover below the main portion; a second region in contact with the first portion of the safety vent portion and disposed outside of the first portion; and a third region in contact with the second portion of the safety vent portion and disposed on the second portion. 9.The cover assembly of claim 8, wherein the gasket further comprises an extension portion extending downward from the first region and disposed spaced apart from the insulator and the lower cover. 10.The cover assembly of claim 8, wherein a thickness of each of the first region, the second region, and the third region is 0.1 mm to 0.6 mm. 11.The cover assembly of claim 8, wherein a thickness of the third region is 50% of each of a thickness of the first region and a thickness of the second region. 12.The cover assembly of claim 8, wherein each of a thickness of the first region and a thickness of the third region is 50% of a thickness of the second region. ​ ​ ​ ​ 13. The cap assembly of any one of claims 1 to 12, wherein the gasket comprises one or more of polybutylene terephthalate, polypropylene, and perfluoroalkoxy alkane.

14. A secondary battery comprising: a case having an opening; an electrode assembly housed in the case; and a cap assembly coupled to the case to close the opening, wherein the cap assembly is the cap assembly of any one of claims 1 to 13.

15. A method of manufacturing a secondary battery, the method comprising: preparing a case having an opening; preparing a cap assembly; inserting an electrode assembly into the case; forming a crimped portion by bending an end portion of a side wall portion of the case; positioning the cap assembly on the crimped portion; and forming a crimping portion by bending the end portion of the side wall portion to seal the opening with the cap assembly, wherein the cap assembly comprises: an upper cap; a safety vent portion below the upper cap and bent to surround at least a portion of an edge of the upper cap; a lower cap below the safety vent portion; an insulator between the safety vent portion and the lower cap; and a gasket integral with the safety vent portion and formed by injection molding, the gasket surrounding at least a portion of an edge of the safety vent portion.

16. The method of manufacturing a secondary battery of claim 15, wherein the preparing the cap assembly comprises: aligning and stacking the upper cap, the safety vent portion, the insulator, and the lower cap in sequence to form the cap assembly; inserting the cap assembly into a mold while maintaining a shape of the cap assembly; and injecting a molding material into the mold to injection mold the gasket.

17. The method of manufacturing a secondary battery of claim 16, wherein the safety vent portion comprises: a main body portion disposed below the upper cap; a first portion extending upward from the main body portion; and a second portion extending inward from the first portion, the second portion in contact with an upper surface of the upper cap.

18. The method of manufacturing a secondary battery of claim 17, wherein the gasket is injection molded to surround at least a portion of a surface of an edge of the main body portion, an entire surface of the first portion, and at least a portion of a surface of the second portion of the safety vent portion.

19. The method of manufacturing a secondary battery of claim 17, wherein the preparing the cap assembly further comprises etching or slitting a surface of an edge of the main body portion and / or a surface of the second portion.

20. The method of manufacturing a secondary battery of claim 17, wherein the preparing the cap assembly further comprises nano-coating at least a portion of a surface of an edge of the main body portion, an entire surface of the first portion, and / or at least a portion of a surface of the second portion. ​ ​ ​ ​

Images