Cylindrical secondary battery and method for manufacturing the same

Abstract

A cylindrical secondary battery and a method for manufacturing the same are provided. The cylindrical secondary battery includes a cylindrical can, an electrode assembly in which a first electrode plate, a second electrode plate, and a separator are wound and is accommodated in the can, and a cap assembly which is insulated from the can and is electrically connected to the electrode assembly, and a degassing hole penetrates the cap assembly to communicate with the inside of the can. According to the embodiment, since a degassing function is applied to remove gas generated before product shipment, deformation of the can and the cap assembly can be reduced. Furthermore, swelling of the electrode assembly due to generation of internal gas can be prevented, thereby reducing performance degradation of the secondary battery.

Description

[0001] This application claims priority and benefit to Korean Patent Application No. 10-2021-0148843, filed on November 2, 2021, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The embodiments relate to a cylindrical secondary battery in which internal gas can be removed and a method for manufacturing the cylindrical secondary battery. Background Technology

[0003] A secondary battery includes a single cell having an electrode assembly and an electrolyte immersed therein, the electrode assembly including a positive electrode, a negative electrode and a separator placed between the positive electrode and the negative electrode.

[0004] Depending on the application, secondary batteries can be configured in various shapes, such as cylindrical, prismatic, and pouch-shaped. Cylindrical secondary batteries typically have an electrode assembly and electrolyte housed inside a cylindrical container, with one end of the container sealed by a cap assembly. Generally, due to repeated charging and discharging, as well as internal chemical factors, gas is generated inside the secondary battery. A limitation is that the cap assembly and container can deform due to gas generation.

[0005] The information disclosed above in the art used as the background art of this invention is only for improving the understanding of the background art of this invention, and therefore may include information that does not constitute related art. Summary of the Invention

[0006] One aspect of this disclosure provides a cylindrical secondary battery with removable internal gas and a method for manufacturing the cylindrical secondary battery.

[0007] According to at least one embodiment, the cylindrical secondary battery includes: a cylindrical can; an electrode assembly having a first electrode plate, a second electrode plate, and a separator wound therein, and the electrode assembly being housed within the can; and a cover assembly insulated from the can and electrically connected to the electrode assembly, with a vent hole passing through the cover assembly to communicate with the interior of the can.

[0008] The cover assembly may include: an exhaust plate, which is attached to one side of the can and spaced apart from the vent hole to provide a notch; a lower cover plate, disposed between the exhaust plate and the electrode assembly for electrical connection to the electrode assembly, and having a plurality of slots passing through the lower cover plate; and a gasket, disposed between the exhaust plate and the can to insulate the exhaust plate and the can from each other.

[0009] The vent plate may include: a first support member that contacts the lower cover plate; an vent portion that is connected to the outside of the first support member to form an integral part with the first support member and has a notch in the vent portion; and a second support member that is connected to the outside of the vent portion to form an integral part with the vent portion and is coupled to the tank by a gasket placed between the second support member and the tank.

[0010] The second support member may include: a first region disposed toward the exhaust portion and having a thickness greater than that of the exhaust portion; and a second region having a thickness relatively smaller than that of the first region.

[0011] The degassing pores can be confined to the first region.

[0012] The lower cover plate may have a smaller diameter than the exhaust plate, and the top surface of the edge of the lower cover plate may be in close contact with and welded to a portion of the bottom surface of the edge of the exhaust plate.

[0013] The cap assembly may also include a resin pin or rubber pin that is press-fitted into the degassing hole after assembly with the can to seal the degassing hole.

[0014] The cap assembly may also include a sealing member that seals the degassing vent after the resin pin or rubber pin is removed when gas is generated inside the can.

[0015] Sealing components may include press-fitted balls or press-fitted resin, or be incorporated into degassing pores in convex and concave structures.

[0016] According to another embodiment, a method for manufacturing a cylindrical secondary battery includes: housing an electrode assembly in a can for electrical connection to the can; electrically connecting a cover assembly to the electrode assembly; assembling the cover assembly with the can; inserting a resin pin or rubber pin into a hole through the cover assembly to close the hole; and attaching a sealing member to the hole through the cover assembly to close the hole after gas is released by removing the resin pin or rubber pin when gas is generated. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view showing a cylindrical secondary battery according to an embodiment;

[0018] Figure 2 It is shown Figure 1 Plan view of the cover assembly;

[0019] Figure 3 It is shown Figure 1 A plan view of the rear surface of the cover assembly;

[0020] Figure 4 It is shown Figure 1 A cross-sectional view of the cover component;

[0021] Figure 5 It is shown Figure 4 A cross-sectional view of the sealing member of the cover assembly; and

[0022] Figure 6 This is a cross-sectional view showing a sealing member according to another embodiment. Detailed Implementation

[0023] However, the invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to enable those skilled in the art to fully understand the invention. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0024] Additionally, in the accompanying drawings, for ease of description and clarity, the thickness or dimensions of each layer have been exaggerated, and the same reference numerals in the drawings denote the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will also be understood in this specification that when component A is referred to as being connected to component B, component A may be directly connected to component B, or indirectly connected to component B via component C located therebetween.

[0025] The terminology used herein is for illustrative purposes only and should not be construed as limiting the meaning or scope of the invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Furthermore, the expressions “comprising / including” and / or “having / containing” as used herein do not limit the shapes, quantities, steps, operations, components, elements, and / or groups thereof mentioned, nor do they exclude the presence or addition of one or more other different shapes, quantities, steps, operations, components, elements, and / or groups thereof. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0026] As used herein, terms such as “first” and “second” are used to describe various components, assemblies, regions, layers, and / or portions. However, it is apparent that components, assemblies, regions, layers, and / or portions should not be limited by these terms. The terms do not imply a specific order, hierarchy, or superiority, but are merely used to distinguish one component, assembly, region, layer, or portion from another. Therefore, without departing from the teachings of the invention, the first component, assembly, region, layer, or portion described may also refer to the second component, assembly, region, layer, or portion.

[0027] For ease of description, spatial relative terms such as "below," "under," "down," "above," and "upper" are used herein to describe the relationship between one element or feature as shown in the accompanying drawings and another element(s). These spatial relative terms are intended to facilitate understanding of the invention in various states of manufacture or use according to the invention, and therefore, the invention is not limited thereto. For example, if an element or feature shown in the drawings is flipped from the inside to the outside, an element or feature described as "below" or "under" may be changed to "above" or "upper." Therefore, the term "down" may encompass the terms "upper" or "under."

[0028] In the following, a cylindrical secondary battery according to an embodiment will be described in detail with reference to the accompanying drawings (for convenience, based on...). Figure 1 The upper side is defined as the upper part, and the lower side is defined as the lower part.

[0029] Figure 1 This is a cross-sectional view showing a cylindrical secondary battery according to an embodiment. Figure 2 It is shown Figure 1 Plan view of the cover component. Figure 3 It is shown Figure 1 A plan view of the rear surface of the cover assembly. Figure 4 It is shown Figure 1 A cross-sectional view of the cover component.

[0030] like Figure 1 As shown, the cylindrical secondary battery 10 according to the embodiment may include a cylindrical can 100, an electrode assembly 200 inserted into the can 100, a first electrode current collector 300 and a second electrode current collector 400 electrically connected to the electrode assembly 200, and a cover assembly 500 coupled to one end of the can 100.

[0031] The can 100 may include a circular bottom 110 and a side 130 extending upward from the bottom 110. The side 130 has a cylindrical shape and its upper end is open to define an opening. The bottom 110 and the side 130 may be integrally formed with each other or may be separately provided to be combined with each other. In the process of manufacturing the secondary battery 10, the electrode assembly 200 and the electrolyte may be received into the can 100 through the opening, and the cap assembly 500 may be combined with the opening to seal the can 100. The can 100 may be made of steel, steel alloy, nickel-plated steel, nickel-plated steel alloy, aluminum, aluminum alloy, or equivalents thereof, but is not limited thereto. A beading part 132 may be recessed inward adjacent to the upper end of the side 130, and a crimping part 134 with a curved end of the side 130 may be provided on the upper portion of the beading part 132. The rolled edge portion 132 supports the lower part of the cover assembly 500, and the pleated portion 134 supports the upper part of the cover assembly 500.

[0032] Electrode assembly 200 may include a first electrode plate, a second electrode plate, and a separator. The first electrode plate may be a positive electrode plate on which a positive active material layer (e.g., a transition metal oxide (LiCoO2, LiNiO2, LiMn2O4, etc.)) is disposed on each of its two surfaces. An uncoated portion of the first electrode to which the positive active material layer is not applied may be disposed on a portion of the first electrode plate. For example, the uncoated portion of the first electrode may be positioned facing the opening of can 100. Furthermore, the second electrode plate may be a negative electrode plate on which a negative active material layer (e.g., graphite, carbon, etc.) is disposed on each of its two surfaces. An uncoated portion of the second electrode to which the negative active material layer is not applied may be disposed on a portion of the second electrode plate. For example, the uncoated portion of the second electrode may be positioned facing the bottom 110 of can 100. A separator may be placed between the first and second electrode plates to prevent short circuits and allow only lithium ions to move. For example, the first electrode plate can be aluminum (Al) foil, the second electrode plate can be copper (Cu) foil or nickel (Ni) foil, and the diaphragm can be made of polyethylene (PE) or polypropylene (PP), but the embodiments are not limited to the above materials. The first electrode plate, the second electrode plate, and the diaphragm can be wound into a substantially cylindrical shape and housed in the can 100. Here, the uncoated portion of the first electrode can be electrically connected to the first electrode current collector, and the uncoated portion of the second electrode can be electrically connected to the second electrode current collector 400.

[0033] The first electrode current collector 300 can be soldered to the uncoated portion of the first electrode of the positive electrode plate and can be electrically connected to the cover assembly 500 via the first electrode lead 310. Therefore, the first electrode plate and the cover assembly 500 can be electrically connected to each other. The first electrode current collector 300 can have an approximately circular plate shape. Optionally, although not shown in the figures, a substrate material tab can be disposed on the first electrode plate, and the first electrode current collector 300 can be directly soldered to the substrate material tab of the first electrode plate.

[0034] The second electrode current collector 400 can be welded to the uncoated portion of the second electrode of the negative electrode plate and can also be welded to the bottom 110 of the can 100. Therefore, the second electrode plate and the can 100 can be electrically connected to each other. The second electrode current collector 400 can have an approximately circular plate shape. Optionally, although not shown in the figures, a substrate material tab can be disposed on the second electrode plate, and the second electrode current collector 400 can be welded to the substrate material tab of the second electrode plate.

[0035] like Figures 2 to 4 As shown, the cover assembly 500 may include an exhaust plate 510, a lower cover plate 520, and a gasket 530.

[0036] like Figure 2 and Figure 4 As shown, the exhaust plate 510 may have a generally circular plate shape and includes a first support 512 that contacts the lower cover plate 520, an exhaust portion 514 connected to the first support 512 and wherein a notch 514a is provided, and a second support 516 connected to the exhaust portion 514 and coupled to the side portion 130 of the can 100.

[0037] The first support member 512 may be a portion with a predetermined thickness, and the bottom surface of the first support member 512 may contact the top surface of the lower cover plate 520. The first support member 512 may have a thickness that gradually decreases outward. The exhaust portion 514 may be integrally disposed on the outer side of the first support member 512.

[0038] An exhaust portion 514 is disposed between the first support member 512 and the second support member 516, and has a thickness relatively thinner than each of the first support member 512 and the second support member 516. A notch 514a is provided on the exhaust portion 514 in a circular shape, and when gas is generated, if the gas pressure exceeds a predetermined level, the notch 514a ruptures to serve as a gas discharge channel. The notch 514a may be provided on the side close to the second support member 516.

[0039] The second support member 516 may be an edge portion of the exhaust plate 510, connected to the outside of the exhaust portion 514, and integrally formed with the exhaust portion 514. The second support member 516 may include a first region 516a and a second region 516b, where the first region 516a has a thickness similar to or greater than that of the first support member 512, and the second region 516b has a thickness relatively smaller than that of the first region 516a. A venting hole 516c is defined to pass through the first region 516a. To ensure the rigidity used to define the venting hole 516c, the thickness of the first region 516a may be greater than the thickness of the second region 516b or the thickness of the first support member 512. The height of the top surface of the first region 516a may be greater than the height of the edge of the exhaust portion 514. Conversely, the height of the top surface of the second region 516b may be less than the height of the top surface of the first region 516a. The gasket 530 is attached to the outside of the second region 516b, and the vent plate 510 is secured by the pleats 134 of the can 100, with the gasket 530 positioned between the vent plate 510 and the pleats 134. Furthermore, a portion of the lower cover plate 520 is in close contact with the bottom surface of the first region 516a.

[0040] A vent 516c is a hole that penetrates from the top surface of the first region 516a to the bottom surface of the first region 516a. The vent 516c may be positioned adjacent to a recess 514a in the first region 516a. For example, the vent 516c may have a shape in which its diameter gradually decreases from top to bottom. A portion of the lower part of the vent 516c may have a shape that maintains the decreasing diameter. The vent 516c communicates with the interior of the can 100 via a lower cover plate 520. When gas is generated inside the secondary battery 10, the gas can be discharged between the exhaust plate 510 and the lower cover plate 520 through a slot 524 defined in the lower cover plate 520, and then discharged to the outside through the vent 516c. The bottom surface of the first support member 512 may protrude downward from the bottom surface of the second support member 516.

[0041] like Figure 3 and Figure 4 As shown, the lower cover plate 520 is disposed below the exhaust plate 510 and is electrically connected to the exhaust plate 510 and the first electrode current collector 300. Although Figure 1 The diagram shows a lower cover plate 520 electrically connected to a first electrode current collector 300 via a first electrode lead 310, but the lower cover plate 520 can be directly connected to the first electrode current collector 300 by welding. The lower cover plate 520 can have an approximately circular shape and a diameter smaller than that of the exhaust plate 510. The top surface of the edge of the lower cover plate 520 is in close contact with the bottom surface of the second support member 516 of the exhaust plate 510. This portion is defined as a third support member 526. The height of the top surface of each of the other portions of the third support member 526 can be smaller than the height of the top surface of the third support member 526. That is, the top surface of the lower cover plate 520, excluding the third support member 526, can be recessed toward the first electrode current collector 300. A plurality of slots 524, serving as channels when gas is generated, can be defined to extend through the plate surface of the lower cover plate 520. The slots 524 can be defined between the central portion of the lower cover plate 520 and the third support member 526.

[0042] The top surface of the lower cover plate 520 is in close contact with the bottom surface of the first support member 512, and the top surface of the third support member 526 is in close contact with the bottom surface of the second support member 516. The portions where the second and third supports 526 are in close contact with each other can be welded to provide a welded section. Because the second and third supports 516 are welded together, even if the notch 514a breaks and a portion of the first support member 512 is removed when gas is generated inside the secondary battery 10, the connection between the vent plate 510 and the lower cover plate 520 can be maintained, thus preserving the electrical connection between the electrode assembly 200 and the cover assembly 500.

[0043] Reference Figure 1The gasket 530 has a generally annular shape and may have a predetermined width. The gasket 530 may be configured to surround a portion or the entirety of the second region 516b of the second support member 516. The cover assembly 500 is insulated from the can 100 by the gasket 530 and is electrically connected to the first electrode current collector 300. Therefore, when the first electrode current collector 300 is a positive electrode current collector, the cover assembly 500 can be used as a positive electrode.

[0044] The manufacturing method of a secondary battery having the above structure will be briefly described below.

[0045] Figure 5 It is shown Figure 4 A cross-sectional view of the sealing component of the cover assembly.

[0046] After welding each of the first electrode current collector 300 and the second electrode current collector 400 to the electrode assembly 200, the electrode assembly 200 can be inserted into the tank 100 with the first electrode current collector 300 facing upwards, and then electrolyte is injected. After welding the vent plate 510 and the lower cover plate 520 and attaching the gasket 530 to form the cover assembly 500, the cover assembly 500 is placed on the rolled edge portion 132 of the side portion 130. Thereafter, a pleat portion 134 is formed to assemble the cover assembly 500 into the tank 100.

[0047] In this state, a resin pin (e.g., PP, PE, etc.) or a rubber pin is temporarily pressed into the degassing hole 516c to seal the secondary battery 10. That is, during the assembly process of the secondary battery 10, the degassing hole 516c is temporarily sealed by the resin pin or rubber pin.

[0048] When gas is generated inside the secondary battery 10 during charging and discharging before the secondary battery is discharged, the resin pin or rubber pin can be removed to allow the internal gas to be discharged through the venting hole 516c. When the gas is completely discharged, as... Figure 5 As shown, a sealing member can be press-fitted into the degassing hole 516c to seal the degassing hole 516c. For example, the sealing member 540 may include a press-fitted ball or press-fitted resin. To perform the press-fitting process, the sealing member 540 may have dimensions larger than the size of the degassing hole 516c.

[0049] Other types can be used to replace the sealing components mentioned above.

[0050] Figure 6 This is a cross-sectional view showing a sealing member according to another embodiment.

[0051] like Figure 6As shown, according to another embodiment, the sealing member 540' can be inserted into the vent hole 516c' by means of insertion rather than press fitting. That is, the sealing member 540' is manufactured to have a shape and size corresponding to the shape and size of the vent hole 516c', thereby sealing the vent hole 516c'. In this case, the sealing member 540' and the vent hole 516c' can be provided with convex and concave structures, such that the sealing member 540' is separated from the vent hole 516c', or that gas does not leak. Various structures can be applied to the convex and concave structures, such as threaded and threaded groove structures, concave-convex structures, and tapered hook and tapered hook-groove structures.

[0052] According to the embodiment, since a degassing function is applied to remove gases generated before product transportation, deformation of the can and cap assembly can be reduced. Furthermore, expansion of the electrode assembly due to the generation of internal gases can be prevented, thereby reducing performance degradation of the secondary battery.

[0053] The above embodiments are merely one example. Therefore, the present invention is not limited to the foregoing embodiments, and those skilled in the art will also understand that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A cylindrical secondary battery, the cylindrical secondary battery comprising: A cylindrical jar; An electrode assembly, comprising a first electrode plate, a second electrode plate, and a diaphragm wound within the electrode assembly, and the electrode assembly being housed within the can; as well as A cap assembly, insulated from the can and electrically connected to the electrode assembly, has a degassing hole passing through the cap assembly to communicate with the interior of the can. The cover assembly includes an exhaust plate attached to one side of the can. The exhaust plate includes: a first support member; an exhaust section connected to the outside of the first support member; and a second support member connected to the outside of the exhaust section. The second support member includes: a first region disposed toward the exhaust portion and having a thickness greater than that of the exhaust portion; and a second region having a thickness relatively smaller than that of the first region. The degassing pores are defined in the first region.

2. The cylindrical secondary battery according to claim 1, wherein, The exhaust plate includes a notch spaced apart from the degassing hole, and The cover assembly further includes: A lower cover plate, disposed between the exhaust plate and the electrode assembly for electrical connection to the electrode assembly, and a plurality of slots passing through the lower cover plate; and A gasket is disposed between the exhaust plate and the canister to insulate the exhaust plate and the canister from each other.

3. The cylindrical secondary battery according to claim 2, wherein: The first support member is in contact with the lower cover plate; The exhaust portion is integrally formed with the first support member, and the recess is provided in the exhaust portion; and The second support member is integral with the exhaust section and is attached to the tank by the gasket placed between the second support member and the tank.

4. The cylindrical secondary battery according to claim 3, wherein, The lower cover plate has a diameter smaller than that of the exhaust plate, and the top surface of the edge of the lower cover plate is in close contact with a portion of the bottom surface of the edge of the exhaust plate and is welded to that portion of the bottom surface of the edge of the exhaust plate.

5. The cylindrical secondary battery according to claim 4, wherein, The cap assembly also includes a resin pin or a rubber pin, which is press-fitted into the degassing hole after being assembled with the can to seal the degassing hole.

6. The cylindrical secondary battery according to claim 5, wherein, The cap assembly also includes a sealing member that, when gas is generated inside the can, seals the degassing hole after the resin pin or rubber pin is removed.

7. The cylindrical secondary battery according to claim 6, wherein, The sealing component includes a press-fit ball or press-fit resin, or is incorporated into the degassing pore in a convex or concave structure.

8. A method for manufacturing a cylindrical secondary battery, the method comprising: The electrode assembly is housed in a container for electrical connection to the container; Electrically connect the cover assembly to the electrode assembly; Assemble the lid assembly with the can; Insert a resin pin or rubber pin into the hole passing through the cover assembly to seal the hole; as well as After the gas is vented by removing the resin pin or rubber pin when it is generated, a sealing member is engaged with the hole passing through the cover assembly to close the hole. The cover assembly includes an exhaust plate attached to one side of the can. The exhaust plate includes: a first support member; an exhaust section connected to the outside of the first support member; and a second support member connected to the outside of the exhaust section. The second support member includes: a first region disposed toward the exhaust portion and having a thickness greater than that of the exhaust portion; and a second region having a thickness relatively smaller than that of the first region. The hole is defined in the first region.

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