Secondary battery

Abstract

Embodiments of the present invention relate to a secondary battery and solve a technical problem of providing a secondary battery that can prevent deformation during assembly of a cover assembly. To this end, the present invention discloses a secondary battery comprising: a can; an electrode assembly accommodated in the can; a cap assembly for closing the can and including an upper cap and a safety vent hole; and the fixing device is used for fixing the upper cover and the safety exhaust hole to each other.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a secondary battery. Background Art

[0002] Typically, a cylindrical secondary battery includes an electrode assembly, a can configured to house the electrode assembly and an electrolyte, and a cap assembly coupled to the upper end of the can to seal the can and allow current generated by the electrode assembly to flow to an external device. The cap assembly may include an upper cap, a safety vent, and a lower cap. If the cap assembly is accidentally deformed during the process of assembling these components, the airtightness of the secondary battery is reduced and the overall height of the secondary battery is also changed. Therefore, it is desirable to provide a technology that can prevent such deformation.

[0003] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art. Summary of the Invention

[0004] Technical issues

[0005] Embodiments of the present disclosure provide a secondary battery capable of preventing deformation during assembly of a cap assembly.

[0006] Technical Solution

[0007] A secondary battery according to an embodiment of the present disclosure includes: a can; an electrode assembly accommodated in the can; a cap assembly configured to close the can, the cap assembly including an upper cap and a safety vent; and a fixing device configured to fix the upper cap and the safety vent to each other.

[0008] The upper cover may include an upper cover contact portion contacting the safety vent, an upper cover inclined portion inclined upward from the upper cover contact portion, and an upper cover top extending from the upper cover inclined portion, and the fixing device may be provided at the upper cover contact portion to be adjacent to the upper cover inclined portion.

[0009] The upper cover may include an upper cover contact portion that contacts the safety exhaust hole, an upper cover inclined portion that is inclined upward from the upper cover contact portion, and an upper cover top extending from the upper cover inclined portion, and the fixing device may be arranged in a 1 / 3 area adjacent to the upper cover inclined portion relative to the entire radial range of the upper cover contact portion.

[0010] The upper cover may include an upper cover contact portion contacting the safety vent, an upper cover inclined portion inclined upward from the upper cover contact portion, and an upper cover top extending from the upper cover inclined portion, and the fixing device may be provided at an inner edge of the upper cover contact portion.

[0011] The fixing means may be configured as a recess and a projection, which are formed at the upper cover and the safety vent, respectively, to correspond to each other.

[0012] The protrusions may be formed vertically.

[0013] The projection may be formed to be inclined outward in the radial direction toward an end portion thereof.

[0014] The recesses and projections may be provided in a plurality of pairs.

[0015] The fixing device can be configured as a thermal melt sheet, which is disposed between the upper cover and the safety exhaust hole.

[0016] There may be multiple thermal fuses.

[0017] The fixing device may be provided as a welding portion, which is formed at the upper cover and the safety exhaust hole by welding.

[0018] A welded portion may be formed at a lower surface of the safety vent.

[0019] A plurality of welding portions may be provided.

[0020] The welded portion may be provided in a point shape.

[0021] The welded portion may be provided in a line shape.

[0022] Beneficial effects

[0023] An embodiment of the present disclosure provides a secondary battery, which is constructed so that an upper cover and a safety vent are fixed to each other via a fixing device, thereby preventing a phenomenon caused by stress applied to the upper cover during the process of bending the safety vent so that the edge of the safety vent surrounds the edge of the upper cover to assemble the cover assembly: the upper cover is pushed inward further away from the safety vent, thereby the upper cover and the safety vent are vertically spaced apart from each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a cross-sectional view illustrating a secondary battery according to various embodiments of the present disclosure.

[0025] Figure 2a is a cross-sectional view illustrating a cap assembly in a secondary battery according to an embodiment of the present disclosure.

[0026] Figure 2b It shows Figure 2a Magnified view of part A in FIG.

[0027] Figure 2c Is as Figure 2b Different examples are shown with Figure 2b The corresponding part of the view.

[0028] Figure 3 is a cross-sectional view illustrating a cap assembly in a secondary battery according to another embodiment of the present disclosure.

[0029] Figure 4is a cross-sectional view illustrating a cap assembly in a secondary battery according to still another embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0031] The embodiments of the present disclosure are provided to more fully explain the present disclosure to those skilled in the art. The embodiments may be modified in various other forms, and the scope of the present disclosure is not limited to the embodiments. The embodiments are provided to make the disclosure more credible and complete, and to fully convey the concepts of the present disclosure to those skilled in the art.

[0032] In addition, in the following drawings, for convenience and clarity of description, the thickness or size of each layer is exaggerated, and the same reference numerals in the drawings refer to the same elements. As used herein, the term "and / or" includes any one of the listed items and any combination of one or more of the listed items. In addition, as used herein, the term "connected" refers not only to a direct connection between components A and B, but also to an indirect connection between components A and B when component C is placed between components A and B.

[0033] The terms used in the specification are intended to describe specific embodiments and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form may include the plural form. In addition, as used herein, the term "comprise" (or "comprising") and / or its variations are intended to illustrate the presence of stated figures, quantities, steps, operations, components, elements and / or their groups, without excluding the presence or addition of one or more other figures, quantities, steps, operations, components, elements and / or groups.

[0034] Although terms such as first and second are used herein to describe various members, components, regions, layers, and / or portions, these members, components, regions, layers, and / or portions are not limited by these terms. These terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Thus, a first member, component, region, layer, or portion described below may refer to a second member, portion, region, layer, or portion without departing from the disclosed teachings.

[0035] Spatially related terms such as “under,” “beneath,” “below,” “above,” and “on” may be used to facilitate understanding of an element or feature shown in a drawing as distinct from another element or feature. Spatially related terms are intended to facilitate understanding of the present disclosure in various states of processing or use and are not intended to limit the present disclosure. For example, if an element or feature in a drawing is turned over, an element or feature described as “under” or “below” becomes “above” or “on.” Thus, “under” encompasses the concept of “above” or “under.”

[0036] Figure 1 is a cross-sectional view illustrating a secondary battery 100 according to various embodiments of the present disclosure.

[0037] Reference Figure 1 , a secondary battery 100 according to the present disclosure includes a can 110 , an electrode assembly 120 , and a cap assembly 130 .

[0038] The can 110 may include a circular bottom 111 and a cylindrical side portion 112 extending upward from the bottom 111 to a certain length. The top of the can 110 may be open during the process of assembling the secondary battery. Therefore, during the process of assembling the secondary battery 100, the electrode assembly 120 may be inserted into the can 110 together with the electrolyte. The can 110 may include steel, a steel alloy, aluminum, an aluminum alloy, or an equivalent thereof. The can 110 may include a crimping portion 113 that is recessed inwardly in a portion thereof positioned below the cap assembly 130 to prevent the electrode assembly 120 and the cap assembly 130 from escaping outward, and may include a crimping portion 114 that is bent inwardly in a portion thereof positioned above the cap assembly.

[0039] The electrode assembly 120 may be housed in the can 110. The electrode assembly 120 may include a negative electrode plate 121 coated with a negative electrode active material (e.g., graphite or carbon), a positive electrode plate 122 coated with a positive electrode active material (e.g., a transition metal oxide (LiCoO2, LiNiO2, or LiMn2O4)), and a separator 123 interposed between the negative electrode plate 121 and the positive electrode plate 122 to prevent short circuits and allow only the migration of lithium ions. The negative electrode plate 121, the positive electrode plate 122, and the separator 123 may be wound into a so-called core shape. 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). A negative electrode tab 124, which protrudes downward and extends a certain length, may be welded to the negative electrode plate 121, and a positive electrode tab 125, which protrudes upward a certain length, may be welded to the positive electrode plate 122. The opposite configuration is also possible. Negative electrode tab 124 may include copper or nickel, and positive electrode tab 125 may include aluminum. Negative electrode tab 124 may be welded to bottom 111 of can 110. Thus, can 110 may function as a negative electrode. Positive electrode tab 125 may be welded to bottom 111 of can 110. In this case, can 110 may function as a positive electrode.

[0040] A first insulating plate 126 having a first hole 126a formed at its center and a second hole 126b formed on its outer side may be interposed between the electrode assembly 120 and the bottom 111 of the can 110. The first insulating plate 126 may prevent electrical contact between the electrode assembly 120 and the bottom 111. The first insulating plate 126 may prevent electrical contact between the positive electrode plate 122 of the electrode assembly 120 and the bottom 111. If a large amount of gas is generated due to an abnormality of the secondary battery, the first hole 126a may allow the gas to quickly move upward through the winding center of the electrode assembly 120, and the second hole 126b may allow the negative electrode tab 124 to extend therethrough and be welded to the bottom 111.

[0041] Similarly, a second insulating plate 127 having a first hole 127a formed at its center and a plurality of second holes 127b formed on its outer side may be interposed between the electrode assembly 120 and the cap assembly 130. The second insulating plate 127 may prevent electrical contact between the electrode assembly 120 and the cap assembly 130. The second insulating plate 127 may prevent electrical contact between the negative electrode plate 121 of the electrode assembly 120 and the cap assembly 130. If a large amount of gas is generated due to an abnormality of the secondary battery, the first hole 127a may allow the gas to quickly move therethrough to the cap assembly 130, and one of the second holes 127b may allow the positive electrode tab 125 to extend therethrough and be welded to the cap assembly 130. The remaining second holes 127b may allow the electrolyte to quickly penetrate the electrode assembly 120 therethrough during the electrolyte injection process.

[0042] The cap assembly 130 may include an upper cap 131 having a plurality of through-holes 131 a, a safety vent 132 disposed below the upper cap 131, a connecting ring 133 disposed below the safety vent 132, and a lower cap 134 disposed below the safety vent 132 and the connecting ring 133, having a plurality of through-holes 134 a and electrically connected to the positive electrode tab 125. The cap assembly 130 may also include an insulating gasket 135 configured to insulate the upper cap 131, the safety vent 132, and the lower cap 134 from the side 112 of the cylindrical can 110. The insulating gasket 135 may be pressed between the crimping portion 113 and the crimping portion 114 formed on the side 112 of the can 110.

[0043] If a large amount of gas is generated due to an abnormality of the secondary battery, the through-holes 131a of the upper cover 131 and the through-holes 134a of the lower cover 134 can allow the internal gas to be discharged to the outside through them. The internal gas can turn the safety vent 132 upward through the through-holes 134a of the lower cover 134, and the safety vent 132 can be electrically disconnected from the lower cover 134. The safety vent 132 can also be torn open, thereby allowing the internal gas to be released to the outside through the through-holes 131a of the upper cover 131.

[0044] An electrolyte (not shown) may be injected into the tank 110. The electrolyte (not shown) may allow lithium ions generated by electrochemical reactions at the negative electrode plate 121 and the positive electrode plate 122 in the battery to move during charging and discharging. The electrolyte may include a non-aqueous organic electrolyte that is a mixture of a lithium salt and a high-purity organic solvent, or may include a polymer electrolyte or a solid electrolyte using a polymer.

[0045] The secondary battery 100 according to the present disclosure includes a fixing device provided between the upper cover 131 and the safety vent 132. The fixing device may be provided in the form of a recess 131e and a protrusion 132f (see FIG. Figures 2a to 2c ) in the form of a heat-melting sheet 236 (see Figure 3 ) or can be constructed in the form of a welded portion 336 (see Figure 4 ) in the form of structures, each of which will be described in detail below.

[0046] Figure 2a is a cross-sectional view illustrating a cap assembly 130 in a secondary battery according to an embodiment of the present disclosure.

[0047] Reference Figure 2a The cover assembly 130 may include an upper cover 131 , a safety vent 132 disposed below the upper cover 131 , a connecting ring 133 disposed below the safety vent 132 , and a lower cover 134 disposed below the safety vent 132 and the connecting ring 133 .

[0048] The upper cover 131 may include an upper cover contact portion 131b contacting the safety vent 132, an upper cover inclined portion 131c inclined upward from the upper cover contact portion 131b and having a plurality of through holes 131a, and an upper cover top 131d extending from the upper cover inclined portion 131c. External devices may be electrically connected to the upper cover top 131d.

[0049] The safety vent 132 may include a vent contact portion 132a that contacts the upper cover contact portion 131b of the upper cover 131, a vent inclined portion 132b that is inclined downward from the vent contact portion 132a, a vent bottom portion 132c that extends from the vent inclined portion 132b, and a vent protruding portion 132d that protrudes downward from the vent bottom portion 132c and is disposed in contact with the lower cover 134. The vent protruding portion 132d is welded to the lower cover 134 by laser welding or ultrasonic welding so that the vent protruding portion 132d and the lower cover 134 can be electrically connected to each other.

[0050] Vent contact portion 132a may be bent multiple times to contact the lower, side, and upper surfaces of upper cover contact portion 131b. For example, vent contact portion 132a may be formed to have a radius greater than that of upper cover contact portion 131b. Vent contact portion 132a may be positioned to contact the lower surface of upper cover contact portion 131b. A portion of vent contact portion 132a extending beyond the edge of upper cover contact portion 131b may be bent upward to surround the side surfaces of upper cover contact portion 131b, and this portion may be bent inward to contact the upper surface of upper cover contact portion 131b, thereby enabling assembly. In this case, the stress applied to upper cover contact portion 131b during the bending of vent contact portion 132a as described above may cause upper cover contact portion 131b to be pushed further inward relative to vent contact portion 132a, thereby vertically separating the lower surface of upper cover contact portion 131b and vent contact portion 132a.

[0051] To prevent this phenomenon, in the secondary battery 100 according to an embodiment of the present disclosure, a fixing device in the form of a recess 131e and a protrusion 132f is provided between the upper cover 131 and the safety vent 132. For example, the recess 131e is formed in the lower surface of the upper cover contact portion 131b, and the protrusion 132f, which is configured to engage with the recess 131e, is formed on the vent contact portion 132a. The recess can be formed in the vent contact portion 132a, and the protrusion, which is configured to engage with the recess, can be formed on the lower surface of the upper cover contact portion 131b. Therefore, as a result of the engagement between the recess 131e and the protrusion 132f, it is possible to prevent the phenomenon in which the upper cover contact portion 131b is pushed further inward relative to the vent contact portion 132a, thereby vertically separating the lower surface of the upper cover contact portion 131b and the vent contact portion 132a.

[0052] In some examples, such as Figure 2b As shown in , the protrusion 132f can be formed vertically. In this case, the recess 131e can also be formed vertically to correspond to the protrusion 132f.

[0053] In another example, Figure 2c As shown in FIG, protrusion 132f' can be formed to be inclined outward in the radial direction toward its end. In this case, recess 131e' can also be formed in an inclined state to correspond to protrusion 132f'. This reverse inclined structure can more effectively prevent the phenomenon in which the lower surface of upper cover contact portion 131b and exhaust port contact portion 132a are vertically spaced apart from each other.

[0054] Although the recess 131 e and the projection 132 f are shown in the drawings as being formed as a pair, the recess 131 e and the projection 132 f may be provided in a plurality of pairs spaced apart from each other by a certain distance in the radial direction.

[0055] The fixture is preferably positioned at the upper cover contact portion 131b so as to be adjacent to the upper cover inclined portion 131c. For example, the fixture is preferably positioned within a 1 / 3 region adjacent to the upper cover inclined portion 131c relative to the entire radial extent of the upper cover contact portion 131b. Table 1 below shows measurement data regarding the extent to which the lower surface of the upper cover contact portion 131b and the exhaust port contact portion 132a are vertically spaced apart from each other according to the position of the fixture. The total radius of the upper cover contact portion 131b is 3.0 mm, and the test was performed while the fixture was moved 0.5 mm at a time from the innermost edge of the upper cover contact portion 131b.

[0056] [Table 1]

[0057]

[0058] The test results show that if the fixing device deviates from the 1 / 3 region adjacent to the upper cover inclined portion 131c relative to the entire radial range of the upper cover contact portion 131b, a phenomenon occurs in which the lower surface of the upper cover contact portion 131b and the exhaust port contact portion 132a are vertically spaced apart from each other. From the perspective of preventing the phenomenon in which the lower surface of the upper cover contact portion 131b and the exhaust port contact portion 132a are vertically spaced apart from each other, it is preferable that the fixing device be provided at the innermost edge of the upper cover contact portion 131b (Test #1).

[0059] Return to reference Figure 2aIn the cap assembly 130, the vent bottom 132c of the safety vent 132 may further include a vent recess 131e. If the internal pressure of the secondary battery exceeds a predetermined pressure, the vent recess 131e may rupture, thereby allowing internal gas to be released to the outside.

[0060] The lower cover 134 may include a lower cover contact portion 134b that contacts the connecting ring 133, a lower cover inclined portion 134c that slopes downward from the lower cover contact portion 134b, and a lower cover bottom portion 134d that extends from the lower cover inclined portion 134c. The connecting ring 133 may be positioned between the vent contact portion 132a and the lower cover contact portion 134b. Each of the upper cover 131, the safety vent 132, and the lower cover 134 may include a metal (e.g., copper, nickel, or aluminum), and the connecting ring 133 may include an insulating material (e.g., polypropylene or polyethylene).

[0061] Figure 3 is a cross-sectional view illustrating a cap assembly in a secondary battery according to another embodiment of the present disclosure.

[0062] In the previous reference Figure 1 and Figures 2a to 2c In the embodiment described, the fixing means are constructed in the form of recesses 131e and projections 132f, but in Figure 3 In another embodiment shown in FIG, the fixing means is configured in the form of a heat-melting piece 236. This other embodiment is substantially the same as the aforementioned embodiment, except that the recess 131e and the protrusion 132f are omitted and the heat-melting piece 236 is added. Therefore, redundant descriptions of the same configuration will be omitted, and the same reference numerals will be used in the drawings.

[0063] The heat-melting sheet 236 is provided between the upper cover contact portion 131b and the exhaust port contact portion 132a and fixes them to each other by heat fusion. Therefore, it is possible to prevent the stress applied to the upper cover contact portion 131b during the bending of the upper cover contact portion 131b as described above from causing the upper cover contact portion 131b to be pushed further inward relative to the exhaust port contact portion 132a, thereby vertically separating the lower surface of the upper cover contact portion 131b and the exhaust port contact portion 132a from each other.

[0064] In the drawing, the heat fuse sheet 236 is shown to be provided in one, but the heat fuse sheet 236 may be provided in plural in such a manner as to be arranged at a certain distance from each other in the radial direction.

[0065] Heat-sensitive adhesive sheet 236 is preferably provided on upper cover contact portion 131b adjacent to upper cover inclined portion 131c, and preferably, is provided within the 1 / 3 region adjacent to upper cover inclined portion 131c relative to the entire radial extent of upper cover contact portion 131b. The effects of this configuration have been described with reference to Table 1. To prevent the lower surface of upper cover contact portion 131b and exhaust port contact portion 132a from becoming vertically spaced apart from each other, heat-sensitive adhesive sheet 236 is preferably provided at the innermost edge of upper cover contact portion 131b.

[0066] A recess configured to allow the thermal fuse 236 to be positioned therein may be formed in at least one of the upper cover contact portion 131 b and the vent contact portion 132 a .

[0067] Figure 4 is a cross-sectional view illustrating a cap assembly in a secondary battery according to still another embodiment of the present disclosure.

[0068] In the previous reference Figure 1 and Figures 2a to 2c In the embodiment described, the fixing means are constructed in the form of recesses 131e and projections 132f, but in Figure 4 In another embodiment shown in FIG, the fixing means is configured in the form of a welding portion 336. This further embodiment is substantially the same as the aforementioned embodiment, except that the recess 131e and the protrusion 132f are omitted and the welding portion 336 is added. Therefore, redundant descriptions of the same configuration will be omitted, and the same reference numerals will be used in the drawings.

[0069] Welding portion 336 is configured to secure upper cover contact portion 131b and exhaust vent contact portion 132a and is formed by welding upper cover contact portion 131b and exhaust vent contact portion 132a while they are stacked. Welding methods include laser welding, resistance welding, and ultrasonic welding. While welding the upper surface of upper cover contact portion 131b is not excluded, welding the lower surface of exhaust vent contact portion 132a is preferably performed. Securement of upper cover contact portion 131b and exhaust vent contact portion 132a by welding portion 336 prevents stress applied to upper cover contact portion 131b during bending, preventing the upper cover contact portion 131b from being pushed further inward relative to exhaust vent contact portion 132a, thereby vertically separating the lower surface of upper cover contact portion 131b and exhaust vent contact portion 132a.

[0070] In the drawing, the welding portion 336 is shown as a single point, but the welding portion 336 may be provided in plural in the form of being arranged to be spaced apart from each other by a certain distance in the radial direction, linearly arranged in the radial direction, or linearly arranged in the circumferential direction.

[0071] Welding portion 336 is preferably provided on upper cover contact portion 131b adjacent to upper cover inclined portion 131c, and preferably, is provided within the 1 / 3 region adjacent to upper cover inclined portion 131c relative to the entire radial extent of upper cover contact portion 131b. The effects of this configuration have been described with reference to Table 1. To prevent the lower surface of upper cover contact portion 131b and exhaust port contact portion 132a from becoming vertically spaced apart from each other, it is preferred that welding portion 336 be provided at the innermost edge of upper cover contact portion 131b.

[0072] The above are merely embodiments for realizing the secondary battery according to the present disclosure, the present disclosure is not limited to the above embodiments, and ordinary technicians in the field to which the present disclosure belongs will recognize the technical spirit of the present disclosure to such an extent that various modifications can be made without departing from the concept of the present disclosure as claimed in the appended claims.

Claims

1. A secondary battery, comprising: Can; an electrode assembly housed in the can; a cap assembly configured to close the can, the cap assembly comprising an upper cap and a safety vent; as well as A fixing device is configured to fix the upper cover and the safety vent to each other.

2. The secondary battery according to claim 1, wherein The upper cover includes an upper cover contact portion contacting the safety vent, an upper cover inclined portion inclined upward from the upper cover contact portion, and an upper cover top portion extending from the upper cover inclined portion, and The fixing device is provided at the upper cover contact portion to be adjacent to the upper cover inclined portion.

3. The secondary battery according to claim 1, wherein The upper cover includes an upper cover contact portion contacting the safety vent, an upper cover inclined portion inclined upward from the upper cover contact portion, and an upper cover top portion extending from the upper cover inclined portion, and The fixing device is arranged in a 1 / 3 region adjacent to the upper cover inclined portion relative to the entire radial range of the upper cover contact portion.

4. The secondary battery according to claim 1, wherein The upper cover includes an upper cover contact portion contacting the safety vent, an upper cover inclined portion inclined upward from the upper cover contact portion, and an upper cover top portion extending from the upper cover inclined portion, and The fixing device is arranged at the inner edge of the upper cover contact portion.

5. The secondary battery according to claim 1, wherein The fixing device is configured as a recess and a projection, and the recess and the projection are formed at the upper cover and the safety vent, respectively, to correspond to each other.

6. The secondary battery according to claim 5, wherein The protrusions are formed vertically.

7. The secondary battery according to claim 5, wherein The protrusion is formed to be inclined outward in a radial direction toward an end portion of the protrusion.

8. The secondary battery according to claim 5, wherein The recesses and protrusions are provided in pairs.

9. The secondary battery according to claim 1, wherein The fixing device is configured as a thermal fuse, and the thermal fuse is disposed between the upper cover and the safety exhaust hole.

10. The secondary battery according to claim 9, wherein The thermal fuse is provided in plurality.

11. The secondary battery according to claim 1, wherein The fixing device is configured as a welding portion, and the welding portion is formed at the upper cover and the safety exhaust hole by welding.

12. The secondary battery according to claim 11, wherein The welding portion is formed at a lower surface of the safety vent.

13. The secondary battery according to claim 11, wherein The welding portion is provided in plurality.

14. The secondary battery according to claim 11, wherein The welding portion is provided in a point shape.

15. The secondary battery according to claim 11, wherein The welding portion is provided in a line shape.

Images