Cylindrical secondary battery

Abstract

Embodiments relate to a cylindrical secondary battery. The cylindrical secondary battery includes: an electrode assembly including a first electrode plate, a separator, and a second electrode plate; a case accommodating the electrode assembly and having a lower end open to be electrically connected to the second electrode plate; a first current collector plate disposed between a top surface of the electrode assembly and the case and electrically connected to the first electrode plate; a terminal passing through a top surface portion of the housing and having a lower end electrically and mechanically coupled to a top surface of the first current collector plate; and a cover plate configured to seal a lower end of the housing. The terminal includes a main body having a flat top surface and a welding groove recessed downward from the top surface of the terminal outside the main body.

Description

[0001] This application claims the priority and benefit of Korean Patent Application No. 10-2024-0013087, filed with the Korean Intellectual Property Office on January 29, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] Embodiments relate to a cylindrical secondary battery. Background Art

[0003] Generally, a cylindrical secondary battery may include a cylindrical electrode assembly, a cylindrical case (or can) accommodating the electrode assembly and an electrolyte, and a cap assembly that is coupled to an opening at one side of the case to seal the case and is electrically connected to the electrode assembly to electrically connect an external bus bar to the electrode assembly.

[0004] The above information used as the background of the present disclosure is only for improving the understanding of the background of the present disclosure and may therefore include information that does not constitute the prior art. Summary of the Invention

[0005] Aspects of some embodiments of the present disclosure provide a cylindrical secondary battery capable of preventing welding impurities from being generated in the case due to welding between a terminal and a current collector plate, or preventing the electrode assembly from being damaged due to welding heat.

[0006] Other aspects of some embodiments of the present disclosure provide a cylindrical secondary battery capable of preventing welding defects due to misalignment that may occur due to a welding groove or an increase in resistance due to insufficient welding area if a plurality of secondary batteries are welded to each other through a bus bar.

[0007] According to some embodiments, a cylindrical secondary battery includes: an electrode assembly including a first electrode plate, a separator, and a second electrode plate; a case accommodating the electrode assembly, wherein a lower end of the case is open, and wherein the case is configured to be electrically connected to the second electrode plate; a first current collector plate disposed between a top surface of the electrode assembly and the case, wherein the first current collector plate is electrically connected to the first electrode plate; a terminal passing through a top surface portion of the case, wherein a lower end of the terminal is electrically and mechanically coupled to a top surface of the first current collector; and a cover plate configured to seal the lower end of the case, wherein the terminal includes a body having a flat top surface and a welding groove that is recessed downward from the top surface of the terminal outside the body.

[0008] The welding groove may have an arc shape, a linear shape, or an annular shape on a plane.

[0009] The terminal may further include a coupling portion disposed outside the body to fix the terminal to the case.

[0010] The coupling portion may include: an upper coupling portion disposed above the top surface portion of the housing; and a lower coupling portion disposed below the top surface portion of the housing.

[0011] In the terminal, the lower coupling portion may be pressed by riveting, and the end of the upper coupling portion may be disposed outside the lower coupling portion on a plane.

[0012] The lower coupling portion may have a thickness greater than the thickness of other regions of the coupling portion.

[0013] The lower coupling portion may include a head, and the end of the head may extend farther outward on a plane than the end of the upper coupling portion.

[0014] The upper coupling portion may be bent outward by being pressed.

[0015] The upper coupling portion and the head may be combined to provide a U-shaped configuration.

[0016] The top surface of the body may be disposed above the top surface of the coupling portion such that the body may protrude upward farther than the top surface of the coupling portion.

[0017] The planar dimension of the body may be larger than the planar dimension of the coupling portion.

[0018] The cylindrical secondary battery may further include a first washer disposed between the terminal and the housing to electrically isolate the terminal from the housing.

[0019] The upper end of the first washer may extend farther than the end of the upper coupling portion by a first length.

[0020] The first length may be about 2 mm or less.

[0021] The upper end of the first washer may be bent upward to extend upward.

[0022] The first current collector plate may be welded outside the terminal through a welding groove such that the top surface of the first current collector plate contacts the bottom surface of the terminal and such that a weld bead is disposed in the welding groove.

[0023] In the welding groove, the width of the upper portion of the welding groove may be larger than the width of the lower portion of the welding groove.

[0024] The thickness of the region of the terminal where the welding groove may be provided, measured from the bottom surface of the terminal, may be smaller than the thickness of other regions of the terminal.

[0025] The housing may include: a crimped portion recessed from the upper portion of the cover plate toward the inside of the housing; and a caulked portion disposed below the crimped portion and the cover plate, and wherein the caulked portion is bent inward to fix the cover plate.

[0026] The cylindrical secondary battery may further include a second gasket disposed between the cover plate and the crimped portion and between the cover plate and the caulked portion, wherein the cover plate may be non-polar.

[0027] The cylindrical secondary battery may further include a second current collector plate disposed between the bottom surface of the electrode assembly and the cover plate to electrically connect the second electrode plate to the crimped portion.

[0028] The top surface of the body may have a diameter of about 11 mm or more.

[0029] A method of manufacturing a cylindrical secondary battery according to some embodiments includes the steps of: providing a housing to accommodate an electrode assembly; inserting the electrode assembly through an open lower portion of the housing, the electrode assembly including a first electrode plate, a separator, and a second electrode plate, the second electrode plate being configured to be electrically connected to the housing; fixing a first current collector plate between the top surface of the electrode assembly and the housing, wherein the first current collector plate is configured to be electrically connected to the first electrode plate; inserting a terminal extending through a top surface portion of the housing, wherein a lower end of the terminal is configured to be electrically and mechanically joined to the top surface of the first current collector plate, wherein the terminal includes a body having a flat top surface and a welding groove recessed downward from the top surface of the terminal outside the body; and fixing a cover plate configured to seal a lower end of the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, are used to explain the principles of the present disclosure. In the drawings: Figure 1 A perspective view of a cylindrical secondary battery according to an embodiment is shown; Figure 2 Shows Figure 1 A cross-sectional view of the cylindrical secondary battery; Figure 3 Shows Figure 2 An enlarged cross-sectional view of part A; Figure 4 Shows Figure 3 A cross-sectional view of a method of joining a terminal and a housing; Figure 5 Shows Figure 2 Another enlarged cross-sectional view of part A; and Figure 6 Shows Figure 5 A cross-sectional view of a method of joining a terminal and a housing. DETAILED DESCRIPTION

[0031] Embodiments of the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0032] In addition, in the drawings, for convenience and clarity of description, the thickness or size of each layer is exaggerated, and like reference numerals in the drawings refer to like elements.

[0033] As used herein, the term "and / or" includes any combination and all combinations of one or more of the associated listed items. In this specification, it will also be understood that if component A is referred to as being connected to component B, then component A may be directly connected to component B or indirectly connected to component B with component C interposed therebetween.

[0034] The terms used in this specification are for illustrative purposes only of the present disclosure and should not be construed as limiting the meaning or scope of the present disclosure. As used in this specification, unless specifically stated otherwise in the context, the singular form may include the plural form. In addition, the expressions "comprising / including" and / or their variants used in this specification indicate the presence of the recited shapes, quantities, steps, operations, components, elements, and / or groups thereof, but do not preclude the presence or addition of one or more other different shapes, quantities, steps, operations, components, elements, and / or groups thereof. The term "and / or" used herein includes any combination and all combinations of one or more of the associated listed items.

[0035] As used herein, terms such as "first", "second", etc. are used to describe various components, assemblies, regions, layers, and / or parts. However, it is obvious that the components, assemblies, regions, layers, and / or parts should not be limited by these terms. These terms do not imply a specific order, up and down, or priority, but are only used to distinguish one component, assembly, region, layer, or part from another component, assembly, region, layer, or part. Thus, without departing from the teachings of the present disclosure, the first component, first assembly, first region, first layer, or first part to be described may also refer to the second component, second assembly, second region, second layer, or second part.

[0036] For ease of description, spatial relative terms such as "below", "beneath", "under", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the figures to another element or feature. These spatial relative terms are intended to facilitate understanding of the given technology according to various process states or usage states of the given technology, and thus the present disclosure is not limited thereto. For example, if the elements or features shown in the figures are flipped, an element or feature described as "beneath" or "below" may be changed to "above" or "on". Thus, the term "under" may encompass the terms "on" or "below".

[0037] Preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present disclosure.

[0038] Here, throughout the specification, components having similar configurations and operations are denoted by the same reference numerals. In addition, in the following description of the present specification, if any part is referred to as being "electrically connected" to another part, it should be understood that the former may be "directly connected" to the latter or "connected" to the latter via an intermediate member.

[0039] As described herein, a cylindrical secondary battery may include a cylindrical electrode assembly, a cylindrical case (or can) that houses the electrode assembly and an electrolyte, and a cap assembly. In the case of a battery module using a plurality of cylindrical secondary batteries connected to each other, since bus bars must be connected to the upper and lower portions of the secondary batteries respectively, there are limitations in that the structure is complex and the process time increases.

[0040] To solve this limitation, the case may be provided with a terminal hole at one of an open side and an opposite side, and a positive electrode riveting terminal and the case are integrally joined to each other insulatively inside the terminal hole. In this structure, bus bars may be provided on the same surface of the secondary battery to facilitate connection of the bus bars in the secondary battery module.

[0041] However, in order to prevent foreign matter from being generated inside the electrode assembly, welding may be performed between the riveting terminal and the current collector plate through a groove provided outside the riveting terminal. However, if misalignment occurs due to the groove outside the riveting terminal during welding with the bus bar, insufficient welding area or welding defects may occur.

[0042] Figure 1 A perspective view of a cylindrical secondary battery 100 according to an embodiment is shown. Figure 2 Shown is Figure 1 a cross-sectional view of the cylindrical secondary battery 100. Figure 3 Shown is Figure 2 an enlarged cross-sectional view of part A. Hereinafter, reference will be made to Figures 1 to 3Describe the cylindrical secondary battery 100.

[0043] As Figure 1 and Figure 2 shown in, the secondary battery 100 according to some embodiments may include a case 110, an electrode assembly accommodated in the case 110, a terminal 150 coupled to a terminal hole provided at one end of the case 110, and a cover plate 160 sealing an opening at the other end of the case 110.

[0044] The case 110 may include a circular top surface portion 111 and a side surface portion 112 extending downward from an edge of the top surface portion 111 by a predetermined length. The top surface portion 111 and the side surface portion 112 of the case 110 may be integral with each other. In some embodiments, a curved portion 111b curved in a circular shape may be provided between the top surface portion 111 and the side surface portion 112.

[0045] The circular top surface portion 111 may have a flat circular plate shape and may include a terminal hole 111a passing through a central portion thereof. The terminal 150 may be inserted into the terminal hole 111a of the top surface portion 111 and coupled to the terminal hole 111a of the top surface portion 111. A first washer 115 for sealing and electrical insulation may be further provided between the terminal hole 111a and the terminal 150. The first washer 115 may block contact between the terminal 150 and the case 110 to electrically isolate the terminal 150 and the case 110 from each other. The first washer 115 may seal the terminal hole 111a of the top surface portion 111 of the case 110. The first washer 115 may be made of a resin material such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), etc.

[0046] In some embodiments, the case 110 may further include an inner insulating member 117 provided to cover an inner surface of the top surface portion 111. In some embodiments, the inner insulating member 117 may be attached to the inner surface of the top surface portion 111 by coating or adhesion. In some embodiments, the inner surface of the top surface portion 111 may be a surface facing the top surface of the electrode assembly 120 and may be a bottom surface of the top surface portion 111. The inner insulating member 117 may prevent the top surface portion 111 of the case 110 and the first electrode plate 121 of the electrode assembly 120 from contacting each other. In some embodiments, the inner insulating member 117 may extend to an inner surface of the curved portion 111b. The inner insulating member 117 may be provided to cover the inner surface of the top surface portion 111 and the inner surface of the curved portion 111b, or may be provided to cover only the inner surface of the top surface portion 111.

[0047] In the cylindrical secondary battery 100, the lower part of the case 110 can be opened during the manufacturing process. In some embodiments, during the manufacturing process, the electrode assembly 120 and the electrolyte can be inserted through the open lower part of the case 110 together. In some embodiments, the electrolyte and the electrode assembly 120 can be inserted into the case 110 in a state where the open lower part of the case 110 faces the upper side. After the electrolyte and the electrode assembly 120 are inserted into the case 110, the cover plate 160 can be coupled to the open lower end of the case 110 to seal the interior of the case 110. In some embodiments, the electrolyte can be used to enable lithium ions to move between the positive electrode plate 121 and the negative electrode plate 122 that constitute the electrode assembly 120. The electrolyte can be a non-aqueous organic electrolyte that is a mixture of a lithium salt and a high-purity organic solvent. In addition, since the type of the electrolyte is not limited herein, the electrolyte can be a polymer electrolyte or a solid electrolyte using a polymer.

[0048] The case 110 can be made of steel, a steel alloy, aluminum, an aluminum alloy, or the like, but the material is not limited thereto. In some embodiments, in the case 110, a crimped portion 113 that is recessed inward can be provided at the upper part of the case 110 relative to the cover plate 160 to prevent the electrode assembly 120 from separating, and a caulked portion 114 that is bent inward can be provided at the lower part of the case 110, and can be provided below the crimped portion and the cover plate.

[0049] In the case 110, after the electrode assembly 120 is inserted through the open lower end, the crimped portion 113 can be provided to prevent the electrode assembly 120 from separating from the case 110.

[0050] The electrode assembly 120 can include a first electrode plate 121, a second electrode plate 122, and a separator 123. The first electrode plate 121 can be a positive electrode plate, the second electrode plate 122 can be a negative electrode plate, and vice versa. Hereinafter, for the sake of simplicity of description, the first electrode plate 121 will be referred to as the positive electrode plate, and the second electrode plate 122 will be referred to as the negative electrode plate; however, the first electrode plate and the second electrode plate are not limited thereto. As Figure 2 shown, the electrode assembly 120 can include one or more first electrode plates 121, one or more second electrode plates 122, and one or more separators 123.

[0051] In some embodiments, for the first electrode plate 121, at least one surface of a plate-shaped metal foil made of aluminum (Al) is coated with a positive electrode active material made of a transition metal oxide. In some embodiments, the first electrode plate 121 may be provided, for example, with a positive electrode uncoated portion on its upper end where the positive electrode active material is not coated. The positive electrode uncoated portion may protrude toward the upper side of the electrode assembly 120. In some embodiments, the positive electrode uncoated portion of the first electrode plate 121 may protrude farther upward than the second electrode plate 122 and the separator 123.

[0052] The second electrode plate 122 may be coated with a negative electrode active material such as graphite or carbon on at least one surface of a plate-shaped metal foil made of copper (Cu) or nickel (Ni). In some embodiments, the second electrode plate 122 may be provided, for example, with a negative electrode uncoated portion on its lower end where the negative electrode active material is not coated. The negative electrode uncoated portion may protrude toward the lower side of the electrode assembly 120. In some embodiments, the negative electrode uncoated portion of the second electrode plate 122 may protrude farther downward than the first electrode plate 121 and the separator 123.

[0053] The separator 123 may be made of a polyethylene (PE) or polypropylene (PP) material, but the embodiments are not limited thereto. The separator 123 may be disposed between the first electrode plate 121 and the second electrode plate 122, for example, to prevent short circuits and allow only lithium ions to move.

[0054] After stacking the first electrode plate 121, the second electrode plate 122, and the separator 123, the electrode assembly 120 may be wound from the winding front end into a substantially cylindrical shape. In some embodiments, in the electrode assembly 120, the positive electrode uncoated portion where the positive electrode active material is not coated may protrude upward from the first electrode plate 121, and the negative electrode uncoated portion where the negative electrode active material is not coated may protrude downward from the second electrode plate 122. In some embodiments, the electrode assembly 120 may be arranged such that the outermost positive electrode uncoated portion may not protrude upward, and the outermost negative electrode uncoated portion may not protrude downward. In some embodiments, the electrode assembly 120 may have a stepped portion where the outermost sides of each of the upper and lower portions are much more recessed than other regions. If the inner insulating member 117 is not provided on the bent portion 111b of the housing 110, this structure of the electrode assembly 120 may prevent the electrode assembly 120 and the housing 110 from contacting each other.

[0055] The first current collector plate 130 may be a circular metal plate having a shape corresponding to the top surface of the electrode assembly 120. The planar dimension (e.g., area) of the first current collector plate 130 may be equal to or less than the dimension of the top surface of the electrode assembly 120. The first current collector plate 130 may be made of aluminum (Al). The first current collector plate 130 may be fixed and electrically connected to the first electrode plate 121 exposed on the upper side of the electrode assembly 120 by welding, such that the bottom surface of the first current collector plate 130 contacts the top surface of the electrode assembly 120. The top surface may include the surfaces of one or more exposed first electrode plates. The first current collector plate 130 may be fixed and electrically connected to the terminal 150 by welding, such that the top surface of the first current collector plate 130 contacts the bottom surface of the terminal 150. The first current collector plate 130 may serve as a path for current flow between the first electrode plate 121 of the electrode assembly 120 and the terminal 150. The first current collector plate 130 may be welded to the electrode assembly 120, housed in the housing 110, and then welded to the terminal 150.

[0056] The second current collector plate 140 may include a circular planar portion 141 corresponding to the bottom surface of the electrode assembly 120 and an extension portion 142 extending downward from the edge of the planar portion 141. The top surface of the planar portion 141 may contact the bottom surface of the electrode assembly 120. The top surface of the planar portion 141 may be fixed and electrically connected to the second electrode plate 122 exposed at the lower side of the electrode assembly 120 by welding, such that the top surface contacts the bottom surface of the electrode assembly 120. The second current collector plate may be disposed between the bottom surface of the electrode assembly and the cover plate to electrically connect the second electrode plate to the crimped portion.

[0057] The extension part 142 can extend downward from the edge of the planar part 141. In some embodiments, the extension parts 142 can be arranged as a plurality of parts (e.g., a plurality of extension parts) spaced apart from each other along the edge of the planar part 141. In some embodiments, four extension parts 142 can be arranged symmetrically with respect to the planar part 141, but the embodiments are not limited thereto. The extension part 142 can be bent to extend downward from the edge of the planar part 141. In some embodiments, the extension part 142 can be rounded or bent along the crimped part 113 so as to contact the inner surface of the crimped part 113. The end of the extension part 142 can be arranged between the crimped part 113 and the second washer 118. The second washer can be arranged between the cover plate and the crimped part and between the cover plate and the crimping part. In some embodiments, the cover plate can be non-polar. The extension part 142 can contact the crimped part 113 of the housing 110 and can be joined to the crimped part 113 of the housing 110. In some embodiments, the extension part 142 can be joined by welding to contact the inner surface of the crimped part 113 of the housing 110. The second current collector plate 140 can serve as a path for current flow between the second electrode plate 122 of the electrode assembly 120 and the housing 110. In some embodiments, the housing 110 can be a negative electrode terminal. In some embodiments, the second current collector plate 140 can be provided with a hole 141a passing through between the top surface and the bottom surface at the center of the planar part 141, and the electrolyte can be easily injected into the electrode assembly 120 through this hole.

[0058] The terminal 150 can be inserted into the terminal hole 111a provided in the top surface part 111 of the housing 110, and can contact and be electrically connected to the first current collector plate 130. The terminal 150 can be electrically connected to the first electrode plate 121 of the electrode assembly 120 through the first current collector plate 130. In some embodiments, the terminal 150 can be a positive electrode terminal. The terminal 150 and the housing 110 can have different polarities. The terminal 150 and each of the first current collector plate 130 and the first electrode plate 121 can be made of the same or similar material (such as including but not limited to aluminum (Al)).

[0059] The upper portion of the terminal 150 may be exposed to the outside of the housing 110, and may contact a bus bar (not shown) and be electrically connected to the bus bar, and the lower portion of the terminal 150 may contact the first current collector plate 130 inside the housing 110 and be electrically connected to the first current collector plate 130 inside the housing 110. In some embodiments, a first gasket 115 may be disposed between the terminal 150 and the housing 110. The terminal 150 may be compressed and deformed (e.g., compression molded) by riveting to seal the terminal hole 111a by pressing the first gasket 115. The first gasket 115 may be disposed between the terminal 150 and the terminal hole 111a of the housing 110, so that the terminal 150 and the housing 110 may be sealed and electrically insulated from each other.

[0060] As described above, the terminal 150 and the first current collector plate 130 may be joined to each other by welding. The bottom surface of the terminal 150 that may contact the first current collector plate 130 may be a flat plane. In some embodiments, the terminal 150 and the first current collector plate 130 may be welded to each other outside the terminal 150, and thus, the terminal 150 may be provided with a welding groove 151. The welding groove may be defined to be recessed downward from the top surface of the terminal 150.

[0061] Referring to Figure 2 and Figure 3 FIGS., the terminal 150 may include a body 152 and a coupling portion 153. The welding groove 151 may be defined outside the body 152. In some embodiments, if viewed from above, the body 152 may define the central portion of the terminal 150, and the coupling portion 153 may be disposed around the body 152. The welding groove 151 may be defined between the body 152 and the coupling portion 153. The bottom surface of the body 152 may be disposed inside the housing 110, and may contact the first current collector plate 130 and be electrically connected to the first current collector plate 130. The top surface of the body 152 may be disposed outside the housing 110, and may contact the bus bar and be electrically connected to the bus bar.

[0062] As Figure 2 and Figure 3 shown in FIGS., the top surface of the body 152 that may contact the bus bar may be provided as a flat surface. In some embodiments, the diameter of the flat top surface of the body 152 may be about 11 mm or more, such as about 11 mm to about 14 mm. If the diameter of the flat top surface of the body 152 is less than about 11 mm, welding defects may occur if misalignment occurs between multiple battery cells. If the diameter is greater than about 14 mm, the size will increase unnecessarily. As a result, the flat top surface of the body 152 on which the bus bar may be welded may have sufficient surface and size for secure welding. As a result, welding can be performed stably and easily.

[0063] In some embodiments, if a plurality of cylindrical secondary batteries are connected to each other through a bus bar, welding can be performed even if there is a deviation in the alignment of the terminals of each cylindrical secondary battery due to the size of the top surface of the main body 152.

[0064] The welding groove 151 may have an arc shape, a linear shape, or an annular shape in a plane. The upper part of the welding groove 151 may have a width greater than the width of the lower part of the welding groove 151. Here, if the battery is cut in the longitudinal direction, the width may refer to the distance between the outer surface of the main body 152 and the inner surface of the bonding part 153. For the area where the welding groove 151 is defined, the terminal 150 may have a smaller thickness, such that the thickness is smaller than the thickness of other areas of the terminal 150. In some embodiments, the smaller thickness may be the thickness measured vertically from the bottom surface of the terminal 150 (e.g., the bottom surface welded to the first current collector plate).

[0065] Welding (e.g., laser welding) may be applied to the welding groove 151 provided in the terminal 150, and thus, a welding bond may be formed between the terminal 150 and the first current collector plate 130 below the bottom of the welding groove 151. Since the welding of the terminal 150 and the first current collector plate 130 can be performed through the welding groove 151 defined outside the terminal 150, foreign substances that may be caused by welding can be prevented from being generated inside the existing case 110. Therefore, damage to the electrode assembly 120 (e.g., inside the existing case 110) due to welding heat can be prevented. In some embodiments, since the terminal 150 is welded from the outside of the case 110 through the welding groove 151, a weld bead may be provided in the welding groove 151.

[0066] The bonding part 153 may be provided outside the main body 152, and the welding groove 151 is between the bonding part 153 and the main body 152, and the bonding part 153 may be bonded to the top surface part 111 of the case by riveting. Refer to Figure 3 and the bonding part 153 may include an upper bonding part 155 covering the upper part of the top surface part 111 around the terminal hole 111a, and a first washer 115 is between the upper bonding part 155 and the upper part of the top surface part 111. The top surface of the upper bonding part 155 may be set lower than the top surface of the main body 152. In some embodiments, the main body 152 may protrude upward farther than the bonding part 153. In some embodiments, the planar dimension (e.g., area) of the upper bonding part 155 may be smaller than the planar dimension (e.g., area) of the main body 152.

[0067] The terminal 150 may be coupled to the inside of the housing 110 from the outside of the housing 110. In some embodiments, the upper coupling portion 155 of the terminal 150 may be disposed above the top surface portion 111 of the housing 110. The upper coupling portion 155 may have a shape that curves outward from the upper end of the coupling portion 153 in a plane.

[0068] The upper end of the first gasket 115 may extend further outward (e.g., in a plane) than the end of the upper coupling portion 155. In some embodiments, the length by which the first gasket 115 extends further than the upper coupling portion 155 (e.g., the first length) may be about 2 mm or less. The upper end of the first gasket 115 may be bent upward (e.g., extended upward) and may extend to cover the upper side of the housing 110. The first gasket 115 may include a first extension portion 115a extending outward from the upper coupling portion 155 and a second extension portion 115b bent from the first extension portion 115a to extend upward. In some embodiments, the sum of the length A1 of the first extension portion 115a, the length A2 of the second extension portion 115b, and the thickness A3 of the second extension portion 115b may be the length by which the first gasket 115 extends further than the upper coupling portion 155 and may be about 2 mm or less. The length A1 of the first extension portion 115a may be the spaced distance between the end of the upper coupling portion 155 and the second extension portion 115b. The length A2 of the second extension portion 115b may be the length from the top surface portion 111 of the housing 110 to the upper end of the first gasket 115. In some embodiments, the thickness A3 of the second extension portion 115b may be the length from the end of the first extension portion 115a to the outermost side of the first gasket 115 in contact with the top surface portion 111 of the housing 110. In some embodiments, the second extension portion 115b of the first gasket 115 may be bent upward to improve the insulation efficiency without reducing the area that can cover the top surface portion 111 of the housing that may be the negative electrode terminal. The first gasket 115 may prevent the terminal 150 and the housing 110 from contacting each other.

[0069] The coupling portion 153 may include a lower coupling portion 157 that is riveted to press the lower portion of the housing 110 around the terminal hole 111a. The lower coupling portion 157 may be provided by deformation (the lower coupling portion 157 is caused to expand in the lateral direction by plastic deformation caused by riveting). In some embodiments, the lower coupling portion may be disposed below the top surface portion of the housing.

[0070] The lower coupling portion 157 may be provided by pressing using an upper jig and a lower jig. As Figure 4As shown in FIG, terminal 150 can be inserted inward from the outside of housing 110. Then, while upper clamp 11 supporting upper coupling portion 155 is fixed, lower clamp 12 can be pressed upward from the bottom side of terminal 150, thereby providing lower coupling portion 157. The diameter of lower coupling portion 157 can be larger than the diameter of each of the other areas of coupling portion 153. In other words, terminal 150 can be inserted into terminal hole 111a while the diameter of lower coupling portion 157 is the same as the diameter of terminal hole 111a. Terminal 150 can then be pressed and deformed by clamps 11 and 12, such that the diameter of lower coupling portion 157 is larger than the diameter of terminal hole 111a (for example, deformation caused by riveting). In some embodiments, the thickness of lower coupling portion 157 can be increased and / or larger than the other areas of coupling portion 153. In some embodiments, the end of upper coupling portion 155 can extend further outward in a plane than lower coupling portion 157. In some embodiments, an end portion of the upper coupling portion is disposed planarly outside the lower coupling portion.

[0071] Figure 5 Shown Figure 2 The same reference numerals may be used for the same example as those for the enlarged cross-sectional view of another example of portion A of FIG. Figure 3 The same components as those in the Figure 5 These components are shown in . Figure 5 The terminal 150 may include a head 158 at its lower portion, and the head 158 may support the lower portion of the top surface portion 111 around the terminal hole 111a of the housing 110. The head 158 may be referred to as a lower coupling portion (for example, the lower coupling portion may include a head). The terminal 150 may be coupled to the terminal hole 111a from the inside of the housing 110 outward.

[0072] In some embodiments, the first gasket 115 may be provided between the head 158 and the corresponding portion of the housing 110 to provide electrical insulation. The upper coupling portion 155 and the head 158 may be combined to provide an approximately U-shape so as to surround the end portion of the housing 110 defining the terminal hole 111a at the upper and lower sides of the top surface portion 111. The upper coupling portion 155 may be provided by press working using an upper jig and a lower jig. Figure 6 As shown in FIG, in a state where the lower jig 22 is fixed to support the head 158, the upper coupling portion 155 can be pressed downward from the above-mentioned initial state before being deformed by the upper jig 21 to set the upper coupling portion 155. The upper coupling portion 155 can be overlapped with the housing 110 on a plane by applying pressure, and the upper coupling portion can have an edge having a rounded shape formed by bending from an end portion of the coupling portion facing the welding groove 151.

[0073] In some embodiments, the end of the head 158 may be disposed outside the end of the upper coupling portion 155 on a plane. The end of the head may extend further outward than the end of the upper coupling portion on the plane. In some embodiments, the area where the head 158 overlaps with the top surface portion 111 of the housing 110 may be larger than the area where the upper coupling portion 155 overlaps with the top surface portion 111 of the housing 110.

[0074] According to an embodiment, the terminal and the first current collector plate may be coupled to each other by welding outside the terminal via a welding groove defined outside the terminal, to prevent foreign substances from being generated due to welding inside the housing, prevent the electrode assembly from being damaged by welding heat, and prevent the weld bead from protruding.

[0075] In addition, the body defining the central portion of the terminal may have a flat top surface to prevent welding defects caused by misalignment that may occur due to the welding groove or an increase in resistance due to insufficient welding area if a plurality of secondary batteries are welded to each other via a bus bar.

[0076] According to some embodiments, a method of manufacturing a cylindrical secondary battery is provided. According to an embodiment, the method includes: providing a housing to accommodate an electrode assembly; inserting the electrode assembly through an open lower portion of the housing, the electrode assembly including a first electrode plate, a separator, and a second electrode plate, the second electrode plate being configured to be electrically connected to the housing; fixing a first current collector plate between the top surface of the electrode assembly and the housing, wherein the first current collector plate is configured to be electrically connected to the first electrode plate; inserting a terminal extending through the top surface portion of the housing, wherein a lower end of the terminal is configured to be electrically and mechanically coupled to the top surface of the first current collector plate, wherein the terminal includes a body having a flat top surface and a welding groove recessed downward from the top surface of the terminal outside the body; and fixing a cover plate configured to seal the lower end of the housing.

[0077] According to some embodiments, the terminal further includes a coupling portion disposed outside the body to fix the terminal to the housing.

[0078] According to some embodiments, the lower end of the housing is bent inward to fix the cover plate.

[0079] The above embodiments are merely exemplary embodiments, and thus, the present disclosure is not limited to the foregoing embodiments, and those of ordinary skill in the art will further understand that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims.

[0080] The term “about” may be used to mean within ±20% of the target value in some embodiments, within ±10% of the target value in some embodiments, and within ±5% of the target value in some embodiments. The term “about” may be equal to the target value.

Claims

1. A cylindrical secondary battery, the cylindrical secondary battery comprising: An electrode assembly including a first electrode plate, a separator, and a second electrode plate; A case for accommodating the electrode assembly, wherein a lower end of the case is open, and wherein the case is configured to be electrically connected to the second electrode plate; A first current collector plate disposed between a top surface of the electrode assembly and the case, wherein the first current collector plate is electrically connected to the first electrode plate; A terminal passing through a top surface portion of the case, wherein a lower end of the terminal is electrically and mechanically joined to a top surface of the first current collector plate; and A cover plate configured to seal the lower end of the case, wherein the terminal includes: a body having a flat top surface, and a welding groove recessed downward from the top surface of the terminal outside the body.

2. The cylindrical secondary battery according to claim 1, wherein The welding groove has an arc shape, a linear shape, or a circular ring shape in a plane.

3. The cylindrical secondary battery according to claim 1, wherein The terminal further includes a coupling portion disposed outside the body for fixing the terminal to the case.

4. The cylindrical secondary battery according to claim 3, wherein, The coupling portion includes: An upper coupling portion disposed above the top surface portion of the case; and A lower coupling portion disposed below the top surface portion of the case.

5. The cylindrical secondary battery according to claim 4, wherein: The lower coupling portion is pressed by riveting, and An end portion of the upper coupling portion is disposed outside the lower coupling portion in a plane.

6. The cylindrical secondary battery according to claim 5, wherein, The lower coupling portion has a thickness greater than a thickness of other regions of the coupling portion.

7. The cylindrical secondary battery according to claim 4, wherein, The lower coupling portion includes a head, and an end portion of the head extends farther outward than an end portion of the upper coupling portion in a plane.

8. The cylindrical secondary battery according to claim 6, wherein The upper coupling portion is bent outward by being pressed.

9. The cylindrical secondary battery according to claim 7, wherein, The upper coupling portion and the head are combined to provide a U-shaped configuration.

10. The cylindrical secondary battery according to claim 3, wherein, The top surface of the body is disposed above the top surface of the coupling portion such that the body protrudes upward farther than the top surface of the coupling portion.

11. The cylindrical secondary battery according to claim 3, wherein, A planar dimension of the body is larger than a planar dimension of the coupling portion.

12. The cylindrical secondary battery according to claim 4, the cylindrical secondary battery further including a first gasket disposed between the terminal and the case to electrically isolate the terminal and the case from each other.

13. The cylindrical secondary battery according to claim 12, wherein, An upper end of the first gasket extends farther than an end portion of the upper coupling portion by a first length.

14. The cylindrical secondary battery according to claim 13, wherein, The first length is 2 mm or less.

15. The cylindrical secondary battery according to claim 13, wherein, The upper end of the first gasket is bent upward to extend upward.

16. The cylindrical secondary battery according to claim 1, wherein, The first current collector plate is welded outside the terminal through the welding groove such that a top surface of the first current collector plate contacts a bottom surface of the terminal, and a weld bead is disposed in the welding groove.

17. The cylindrical secondary battery according to claim 1, wherein, In the welding groove, a width at an upper portion of the welding groove is larger than a width at a lower portion of the welding groove.

18. The cylindrical secondary battery according to claim 1, wherein, A thickness of a region of the terminal provided with the welding groove measured from a bottom surface of the terminal is smaller than a thickness of other regions of the terminal.

19. The cylindrical secondary battery according to claim 1, wherein, The case includes a curled portion recessed from an upper portion of the cover plate toward an interior of the case and a crimping portion disposed below the curled portion and the cover plate; And Wherein, the crimping portion is bent inward to fix the cover plate.

20. The cylindrical secondary battery according to claim 19, wherein the cylindrical secondary battery further includes a second gasket disposed between the cover plate and the curled portion and between the cover plate and the crimped portion, where The cover plate is non-polar.

21. The cylindrical secondary battery according to claim 19, wherein the cylindrical secondary battery further includes a second current collector plate disposed between a bottom surface of the electrode assembly and the cover plate to electrically connect the second electrode plate to the curled portion.

22. The cylindrical secondary battery according to claim 1, wherein, The top surface of the main body has a diameter of 11 mm or more.

Images