Cylindrical secondary battery

Abstract

A technical problem to be solved by embodiments of the present application is to provide a cylindrical secondary battery which can prevent deformation of components thereof during a manufacturing process or in use. To this end, embodiments of the present application provide a cylindrical secondary battery including a cylindrical can, an electrode assembly received in the cylindrical can, and a cap assembly covering the cylindrical can to seal the electrode assembly, wherein the cap assembly includes an upper cap, a lower cap below the upper cap, and a safety vent hole between the upper cap and the lower cap, and a contact between the safety vent hole and the lower cap is in a range of 60% to 100%.

Description

Technical Field

[0001] Embodiments of the present invention relate to a cylindrical secondary battery. Background Technology

[0002] Typically, a cylindrical secondary battery includes a cylindrical electrode assembly, a cylindrical can containing the electrode assembly and electrolyte, and a cover assembly attached to the top opening of the can to seal the can and allow current generated in the electrode assembly to flow to an external device.

[0003] To prevent the electrode assembly and cap assembly from moving, a crimped edge and a press-fit portion are formed by applying pressure along the upper outer circumferential surface of the can. Here, because pressure is applied to the can from the outside in, deformation of the cap assembly is likely to occur. Specifically, when the cap assembly deforms, the sealing force of the secondary battery decreases, and the overall height of the secondary battery also changes.

[0004] The information disclosed above in the art used as the background of this invention is only for improving the understanding of the background of this invention, and therefore may include information that does not constitute related art. Summary of the Invention

[0005] Technical issues

[0006] Embodiments of the present invention provide a cylindrical secondary battery capable of preventing component deformation during manufacturing or during use.

[0007] Technical solution

[0008] A cylindrical secondary battery according to an embodiment of the present invention includes: a cylindrical can; an electrode assembly housed in the cylindrical can; and a cover assembly configured to cover the cylindrical can to seal the electrode assembly, wherein the cover assembly includes an upper cover, a lower cover below the upper cover, and a safety vent between the upper cover and the lower cover, wherein the mutual contact ratio between the safety vent and the lower cover can be in the range of 60% to 100%.

[0009] The safety vent may include: a vent contact portion that contacts the upper cover; a vent slope portion that slopes downward from the vent contact portion; a vent bottom portion that extends parallel to the vent slope portion; and a vent protrusion that protrudes from the vent bottom portion to contact the lower cover.

[0010] The diameter of the vent protrusion can be 60% to 100% of the diameter of the vent bottom.

[0011] The bottom of the vent may also include a flat vent recess formed in the top surface facing the vent protrusion.

[0012] The lower cover may include a lower cover through-hole, and the vent protrusion may cover a portion of the lower cover through-hole.

[0013] The vent protrusion can be welded to the lower cover.

[0014] The bottom of the vent may also include a linear vent groove formed in the top surface of the vent facing the vent protrusion.

[0015] The lower cover may also include a flat lower cover recess formed in its bottom surface, and the diameter of the vent protrusion may be larger than the diameter of the flat lower cover recess.

[0016] Beneficial effects

[0017] Embodiments of the present invention can provide a cylindrical secondary battery capable of preventing deformation of the components during the manufacturing process or during use. In some examples, the interconnection area between the safety vent and the lower cover is approximately 60% to approximately 100% of the area of ​​the bottom of the safety vent, to prevent deformation of components such as the cover assembly during the manufacturing process or during use, thereby providing a secondary battery in which the sealing performance does not deteriorate and its overall height does not change. Attached Figure Description

[0018] Figure 1a , Figure 1b and Figure 1c These are perspective views, sectional views, and exploded perspective views of a cylindrical secondary battery according to an embodiment of the present invention.

[0019] Figures 2a to 2d This is a cross-sectional view showing the cover assembly of a cylindrical secondary battery according to a comparative example and embodiment of the present invention.

[0020] Figure 3 This is a table summarizing whether the cover assembly of the cylindrical secondary battery according to embodiments and comparative examples of the present invention is deformed. Detailed Implementation

[0021] 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 so that those skilled in the art will have a thorough understanding of 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.

[0022] Additionally, in the following figures, for ease of description and clarity, the thickness or dimensions of each layer are exaggerated, and the same reference numerals in the figures refer to 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, with component C located between component A and component B.

[0023] 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 variations thereof 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.

[0024] 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 these components, assemblies, regions, layers, and / or portions should not be limited by these terms. These terms do not imply a particular order, hierarchy, or superiority, and are used only to distinguish one component, assembly, region, layer, or portion from another. Therefore, without departing from the teachings of the invention, the first component, first assembly, first region, first layer, or first portion described may also be referred to as a second component, second assembly, second region, second layer, or second portion.

[0025] For ease of description, spatially relative terms such as "below," "under," "down," "above," and "upper" may be used herein to describe the relationship between one element or feature as shown in the accompanying drawings and another (additional) element or feature. These spatially 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 accompanying drawings is flipped from the inside out, an element or feature described as "below" or "under" may become "above" or "upper." Thus, the term "down" may encompass the terms "upper" or "below."

[0026] Figure 1a , Figure 1b and Figure 1c These are perspective views, sectional views, and exploded perspective views of a cylindrical secondary battery 100 according to an embodiment of the present invention.

[0027] Reference Figure 1a , Figure 1b and Figure 1c The secondary battery 100 according to the present invention includes a cylindrical can 110, an electrode assembly 120, and a cap assembly 140. In some examples, a center pin 130 may also be provided for coupling to the electrode assembly 120.

[0028] The cylindrical can 110 may include a circular bottom 111 and a cylindrical side 112 extending upward from the bottom 111 for a predetermined length. During the manufacturing process of the secondary battery, the upper part of the cylindrical can 110 is open. Therefore, during the assembly process of the secondary battery, the electrode assembly 120 can be inserted into the cylindrical can 110 together with the electrolyte. In some examples, the cylindrical can 110 may include steel, steel alloy, aluminum, aluminum alloy, or equivalents thereof. In some examples, an inwardly recessed crimped portion 113 may be formed in the lower part of the cylindrical can 110 relative to the cover assembly 140 to prevent the electrode assembly 120 and the cover assembly 140 from separating from the outside, and an inwardly bent crimped portion 114 may be formed in the upper part of the cylindrical can 110 relative to the cover assembly 140.

[0029] Electrode assembly 120 may be housed inside cylindrical container 110. Electrode assembly 120 may include a negative electrode plate 121 coated with a negative electrode active material (e.g., graphite, carbon, etc.), a positive electrode plate 122 coated with a positive electrode active material (e.g., transition metal oxides (LiCoO2, LiNiO2, LiMn2O4, etc.)), and a separator 123 disposed between the negative electrode plate 121 and the positive electrode plate 122 to prevent short circuits and allow only lithium ion movement. In some examples, the negative electrode plate 121, positive electrode plate 122, and separator 123 may be wound in a substantially cylindrical shape. In some examples, the negative electrode plate 121 may include copper (Cu) foil or nickel (Ni) foil, the positive electrode plate 122 may include aluminum (Al) foil, and the separator 123 may include polyethylene (PE) or polypropylene (PP). In some examples, the negative electrode tab 124, which protrudes downward by a predetermined length, can be soldered to the negative electrode plate 121, and the positive electrode tab 125, which protrudes upward by a predetermined length, can be soldered to the positive electrode plate 122, and vice versa. In some examples, the negative electrode tab 124 may comprise copper or nickel, and the positive electrode tab 125 may comprise aluminum.

[0030] In some examples, the negative electrode tab 124 of the electrode assembly 120 can be soldered to the bottom 111 of the cylindrical can 110. Therefore, the cylindrical can 110 can act as a negative electrode. Conversely, the positive electrode tab 125 can be soldered to the bottom 111 of the cylindrical can 110, in which case the cylindrical can 110 can operate as a positive electrode.

[0031] In some examples, a first insulating plate 126, incorporated into the cylindrical can 110 and having a first hole 126a at its center and a second hole 126b formed outside the first hole 126a, may be positioned between the electrode assembly 120 and the bottom 111. The first insulating plate 126 may be used to prevent electrical contact between the electrode assembly 120 and the bottom 111 of the cylindrical can 110. In some examples, the first insulating plate 126 may be used to prevent the positive electrode plate 122 of the electrode assembly 120 from making electrical contact with the bottom 111. In some examples, when a large amount of gas is generated due to an anomaly in the secondary battery, the first hole 126a may be used to allow the gas to move rapidly upward through the center pin 130, and the second hole 126b may be used to allow the negative electrode tab 124 to pass through it for welding to the bottom 111.

[0032] In some examples, a second insulating plate 127, incorporated into the cylindrical tank 110 and having a first hole 127a at its center and a plurality of second holes 127b formed outside the first hole 127a, can be positioned between the electrode assembly 120 and the cover assembly 140. The second insulating plate 127 can be used to prevent electrical contact between the electrode assembly 120 and the cover assembly 140. In some examples, the second insulating plate 127 can be used to prevent the negative electrode plate 121 of the electrode assembly 120 from making electrical contact with the cover assembly 140. In some examples, when a large amount of gas is generated due to an anomaly in the secondary battery, the first hole 127a can be used to allow the gas to move rapidly into the cover assembly 140, and the second holes 127b can be used to allow the positive electrode tab 125 to pass through it for welding to the cover assembly 140. Additionally, the remaining second holes 127b can be used to allow electrolyte to flow rapidly into the cylindrical tank 110 during the electrolyte injection process.

[0033] In some examples, each of the first hole 126a in the first insulating plate 126 and the first hole 127a in the second insulating plate 127 may have a smaller diameter than the diameter of the center pin 130, such that the center pin 130 does not make electrical contact with the bottom 111 of the cylindrical can 110 or the cover assembly 140 due to external impact.

[0034] In some examples, the center pin 130 may have a hollow circular tube shape and may be coupled to approximately the center of the electrode assembly 120. In some examples, the center pin 130 may comprise steel, a steel alloy, aluminum, an aluminum alloy, or polybutylene terephthalate. The center pin 130 serves to suppress deformation of the electrode assembly 120 during battery charging and discharging and acts as a channel for gases generated inside the secondary battery. In some cases, the center pin 130 may be omitted.

[0035] The cover assembly 140 may include an upper cover 141 having multiple through holes 141a, a safety vent 142 disposed below the upper cover 141, a connecting ring 143 disposed below the safety vent 142, and a lower cover 144 disposed below the safety vent 142 and the connecting ring 143, having multiple through holes 144a and electrically connected to the positive electrode terminal block 125. In some examples, the cover assembly 140 may also include an insulating washer 145 that insulates the upper cover 141, the safety vent 142, and the lower cover 144 from the side 112 of the cylindrical container 110.

[0036] In some examples, the insulating gasket 145 may be substantially compressed between the crimped portion 113 and the crimped portion 114 formed on the side of the cylindrical can 110. In some examples, the through-hole 141a of the upper cover 141 and the through-hole 144a of the lower cover 144 may be configured to vent internal gas to the outside when abnormal internal pressure is generated inside the cylindrical can 110. In some examples, internal gas can reverse the upward direction of the safety vent 142 through the through-hole 144a of the lower cover 144, electrically disconnecting the safety vent 142 from the lower cover 144, and then, when the safety vent 142 is torn, internal gas can be vented to the outside through the through-hole 141a of the upper cover 141.

[0037] In some examples, an electrolyte (not shown in the figures) may be injected inside the cylindrical container 110 to allow lithium ions generated during charging and discharging via electrochemical reactions in the negative electrode plate 121 and positive electrode plate 122 inside the battery to be mobile. The electrolyte may include a non-aqueous organic electrolyte as a mixture of a lithium salt and a high-purity organic solvent. In some examples, the electrolyte may include a polymer using a polymer electrolyte or a solid electrolyte.

[0038] Figures 2a to 2d This is a cross-sectional view showing the cover assembly 140 of a cylindrical secondary battery 100 according to a comparative example and embodiment of the present invention. Figure 3 This is a table summarizing whether the cover assembly 140 of the cylindrical secondary battery 100 according to embodiments and comparative examples of the present invention is deformed. Here, Figure 2a and Figure 3 Corresponding to Example 1, Figure 2b and Figure 3 Corresponding to Example 2, Figure 2c and Figure 3 Corresponding to Example 2, Figure 2d and Figure 3 This corresponds to Example 3.

[0039] like Figures 2a to 2dAs shown, the cover assembly 140 may include an upper cover 141, a safety vent 142 disposed below the upper cover 141, a connecting ring disposed below the safety vent 142, and a lower cover disposed below the connecting ring 143. In some examples, the mutual contact (connection) ratio between the safety vent 142 and the lower cover 144 may be in the range of approximately 60% to approximately 100%.

[0040] In some examples, the cover 141 may include a cover contact portion 141b that contacts the safety vent 142, a cover inclined portion 141c that slopes upward from the cover contact portion 141b and has a plurality of through holes 141a, and a cover top 141d that extends parallel to the cover inclined portion 141c. In some examples, an external device may be electrically connected to the cover top 141d.

[0041] In some examples, the safety vent 142 may include a vent contact 142a that contacts the cover contact 141b of the cover 141, a vent slope 142b that slopes downward from the vent contact 142a, a vent bottom 142c that extends parallel to the vent slope 142b, and a vent protrusion 142d that protrudes from the vent bottom 142c to contact (connect) with the lower cover 144.

[0042] In some examples, the diameter (length or width) of the vent protrusion 142d can be in the range of approximately 60% to approximately 100% of the diameter (length or width) of the vent bottom 142c. In some examples, the vent protrusion 142d can be laser- or ultrasonically welded to the lower cover 144, so that the vent protrusion 142d and the lower cover 144 can contact (connect) each other.

[0043] In some examples, the vent contact 142a can be bent multiple times to contact each of the bottom, side, and top surfaces of the cover contact 141b. In some examples, the vent bottom 142c may also include a substantially flat vent recess 142e formed in its top surface facing the vent protrusion 142d. In some examples, the flat vent recess 142e can be formed by pressing a mold for forming the vent protrusion 142d in the vent bottom 142c. In some examples, the vent bottom 142c of the safety vent 142 may also include a substantially linear vent recess 142f formed in its top surface facing the vent protrusion 142d. In some examples, when the pressure inside the battery exceeds a preset pressure, the linear vent recess 142f can rupture to release internal gas to the outside.

[0044] In some examples, the lower cover 144 may include a lower cover contact portion 144b that contacts the connecting ring 143, a lower cover inclined portion 144c that slopes downward from the lower cover contact portion 144b, and a lower cover bottom 144d that extends parallel to the lower cover inclined portion 144c. In some examples, the connecting ring 143 may be positioned between the vent contact portion 142a and the lower cover contact portion 144b. In some examples, each of the upper cover 141, the safety vent 142, and the lower cover 144 may include a metallic material (e.g., copper, nickel, or aluminum), but the connecting ring 143 may include an insulating material (e.g., polypropylene or polyethylene).

[0045] In some examples, the bottom cover 144d may also include a through-hole 144a extending through the bottom cover 144d. In some examples, the vent protrusion 142d may cover a portion of the through-hole 144a (see...). Figure 2d In some examples, the lower cover 144 may also include a flat lower cover recess 144e formed in its bottom surface. Here, the diameter (length or width) of the vent protrusion 142d may be larger than the diameter (length or width) of the flat lower cover recess 144e. In some examples, the negative electrode tab 124 (see...) Figure 1b It can be welded to the bottom 144d of the lower cover, which is the outside of the flat lower cover recess 144e.

[0046] For example, in Figure 2a (Comparison Example 1) The diameter (length) of the bottom vent 142c can be approximately 11.04 mm, and the diameter (length) of the vent protrusion 142d can be approximately 3.28 mm. Therefore, the mutual contact length (diameter) between the bottom vent 142c and the bottom of the lower cover 144d can be approximately 3.28 mm, and the mutual contact (connection) ratio can be approximately 29.7%.

[0047] For example, in Figure 2b (Comparative Example 2) The diameter (length) of the bottom vent 142c can be approximately 11.04 mm, and the diameter (length) of the vent protrusion 142d can be approximately 4.5 mm. Therefore, the mutual contact length (diameter) between the bottom vent 142c and the bottom of the lower cover 144d can be approximately 4.5 mm, and the mutual contact (connection) ratio can be approximately 40.8%.

[0048] For example, in Figure 2c In Example 2, the diameter (length) of the bottom vent 142c can be approximately 11.04 mm, and the diameter (length) of the vent protrusion 142d can be approximately 7.5 mm. Therefore, the mutual contact length (diameter) between the bottom vent 142c and the bottom vent 144d of the lower cover can be approximately 7.5 mm, and the mutual contact (connection) ratio can be approximately 67.9%.

[0049] For example, in Figure 2d In Example 3, the diameter (length) of the bottom vent 142c can be approximately 11.04 mm, and the diameter (length) of the vent protrusion 142d can be approximately 9.6 mm. Therefore, the mutual contact length (diameter) between the bottom vent 142c and the bottom vent 144d of the lower cover can be approximately 9.6 mm, and the mutual contact (connection) ratio can be approximately 87.0%.

[0050] like Figure 3 As shown, when the amount of contact between the bottom of the cover 144d and the bottom of the vent 142c (or the amount of contact between the bottom of the vent 142c and the bottom of the cover 144d) is less than approximately 60% (i.e., Comparative Examples 1 to 5), deformation is found in the cover assembly 140 after the edge-rolling and pressing processes of the secondary battery 100.

[0051] However, when the amount of contact between the bottom of the cover 144d and the bottom of the vent 142c (or the amount of contact between the bottom of the vent 142c and the bottom of the cover 144d) is approximately 60% to 100% (i.e., Examples 1 to 4), no deformation is found in the cover assembly 140 after the edge rolling and pressing processes of the secondary battery 100.

[0052] exist Figure 3 In this context, the length (mm) of the bottom of the vent hole can represent the diameter of the bottom of the vent hole 142c, and the contact length (mm) can represent the contact diameter between the vent hole protrusion 142d and the bottom of the lower cover 144d. Additionally, the usage amount (%) can represent the ratio of the contact length between the vent hole protrusion 142d and the bottom of the lower cover 144d to the length of the bottom of the vent hole 142c.

[0053] In some examples, such as Figure 3 As shown, the length of the bottom 142c of the exhaust port can be approximately 11.04 mm, and the contact length (i.e., the length of the exhaust port protrusion 142d) can be 3.28 mm, 4.5 mm, 5.5 mm, 6.0 mm, and 6.5 mm in Comparative Examples 1 to 5, respectively, and 7.0 mm, 7.5 mm, 9.6 mm, and 11.0 mm in Examples 1 to 4, respectively. Furthermore, the usage amounts in Comparative Examples 1 to 5 can be 29.7%, 40.8%, 49.8%, 54.3%, and 58.9%, respectively, and the usage amounts in Examples 1 to 4 can be 63.4%, 67.9%, 87.0%, and 100.0%, respectively.

[0054] like Figure 3As shown, in Comparative Examples 1 to 5, deformation occurred in the cover assembly during the battery manufacturing process, while in Examples 1 to 4, no deformation occurred in the cover assembly during the battery manufacturing process. Therefore, the mutual contact ratio between the safety vent and the lower cover can preferably be 60% to 100%.

[0055] In this way, embodiments of the invention can provide a cylindrical secondary battery 100 capable of preventing deformation of the cover assembly 140 during manufacturing or use. In some examples, the mutual contact ratio between the safety vent 142 and the lower cover 144 relative to the area of ​​the vent bottom 142c can be in the range of approximately 60% to approximately 100% to prevent deformation of the cover assembly 140 during manufacturing or use, thereby providing a secondary battery in which the sealing performance is not degraded and its overall height remains unchanged.

[0056] The above embodiments are merely examples, and therefore, the present invention is not limited to the foregoing embodiments. Furthermore, those skilled in the art will understand that various changes in form and detail may be made therein 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: Cylindrical can; The electrode assembly is housed in the cylindrical container; as well as A cover assembly is configured to cover the cylindrical can to seal the electrode assembly. The cover assembly includes an upper cover, a lower cover below the upper cover, and a safety vent between the upper cover and the lower cover, wherein the contact ratio between the safety vent and the lower cover is in the range of 60% to 100%. The safety vent includes: a vent contact portion that contacts the upper cover; a vent inclined portion that slopes downward from the vent contact portion; a vent bottom that extends parallel to the vent inclined portion; and a vent protrusion that protrudes downward from the vent bottom to contact the lower cover. The mutual contact ratio refers to the ratio of the contact length between the vent protrusion and the lower cover to the length of the bottom of the vent.

2. The cylindrical secondary battery according to claim 1, wherein, The cover assembly also includes a connecting ring below the safety vent, and The lower cover includes: The lower cover contact portion contacts the connecting ring; The lower cover inclined portion slopes downward from the lower cover contact portion; and The bottom of the lower cover extends parallel to the inclined portion of the lower cover.

3. The cylindrical secondary battery according to claim 1, wherein, The diameter of the vent protrusion is 60% to 100% of the diameter of the bottom of the vent.

4. The cylindrical secondary battery according to claim 1, wherein, The bottom of the vent also includes a flat vent groove formed in the top surface of the vent facing the vent.

5. The cylindrical secondary battery according to claim 1, wherein, The lower cover includes a lower cover through-hole, and The vent protrusion covers a portion of the through hole in the lower cover.

6. The cylindrical secondary battery according to claim 1, wherein, The vent protrusion is welded to the lower cover.

7. The cylindrical secondary battery according to claim 1, wherein, The bottom of the vent also includes a linear vent groove formed in the top surface of the vent that faces the vent.

8. The cylindrical secondary battery according to claim 1, wherein, The lower cover includes a flat lower cover recess formed in its bottom surface, and The diameter of the vent protrusion is larger than the diameter of the flat lower cover groove.

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