Cylindrical secondary battery

Abstract

The technical problem to be solved according to an embodiment of the present invention is to provide a cylindrical secondary battery capable of preventing deformation of parts during the manufacturing process or during use. To this end, an embodiment of the present invention provides a cylindrical secondary battery comprising: a cylindrical can; an electrode assembly accommodated in the cylindrical can; and a cap assembly that seals the electrode assembly by blocking the cylindrical can, wherein the cap assembly comprises a cap-up, a cap-down below the cap-up, and a safety vent between the cap-up and the cap-down, and wherein the mutual contact ratio between the safety vent and the cap-down is 60% to 100%.

Description

Technology Field

[0001] An embodiment of the present invention relates to a cylindrical secondary battery. Background Technology

[0002] Generally, a cylindrical secondary battery includes a cylindrical electrode assembly, a cylindrical can that accommodates the electrode assembly and the electrolyte, and a cap assembly that is coupled to the top opening of the can to seal the can and allow the current generated from the electrode assembly to flow to an external device.

[0003] To prevent movement of the electrode assembly and cap assembly, pressure is applied along the upper outer surface of the can to form beading and crimping sections. Since pressure is applied from the outside to the inside of the can, the cap assembly is prone to deformation. In particular, if deformation occurs in the cap assembly, the sealing performance of the secondary battery is reduced, and the overall height of the secondary battery also changes.

[0004] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art. The problem to be solved

[0005] An embodiment of the present invention provides a cylindrical secondary battery capable of preventing component deformation during the manufacturing process or during use. means of solving the problem

[0006] A cylindrical secondary battery according to an embodiment of the present invention comprises a cylindrical can; an electrode assembly accommodated in the cylindrical can; and a cap assembly that seals the electrode assembly by blocking the cylindrical can, wherein the cap assembly comprises a cap-up, a cap-down below the cap-up, and a safety vent between the cap-up and the cap-down, and the mutual contact ratio between the safety vent and the cap-down may be 60% to 100%.

[0007] The above safety vent may include a vent contact portion that contacts the cap-up, a vent inclined portion inclined downward from the vent contact portion, a vent bottom portion extending parallel to the vent inclined portion, and a vent protrusion portion protruding from the vent bottom portion and contacting the cap-down.

[0008] The diameter of the vent protrusion may be 60% to 100% of the diameter of the vent bottom portion.

[0009] The above-mentioned vent bottom portion may further include a flat vent groove formed on an upper surface opposite to the above-mentioned vent protrusion.

[0010] The above cap-down includes a cap-down through-hole penetrating the cap-down, and the vent protrusion may cover a portion of the cap-down through-hole.

[0011] The above vent protrusion can be welded to the above cap down.

[0012] The above-mentioned vent bottom portion may further include a line-shaped vent groove formed on an upper surface opposite to the above-mentioned vent protrusion.

[0013] The above cap-down further includes a flat cap-down groove formed on the lower surface, and the diameter of the vent protrusion may be larger than the diameter of the flat cap-down groove. Effects of the invention

[0014] Embodiments of the present invention can provide a cylindrical secondary battery capable of preventing deformation of parts during the manufacturing process or during use. In some examples, by making the mutual contact area between the safety vent and the cap down approximately 40% to approximately 100% of the bottom area of ​​the safety vent, deformation of parts such as the cap assembly can be prevented during the manufacturing process or during use, thereby providing a cylindrical secondary battery in which sealing performance is not degraded and there is no change in overall height. Brief explanation of the drawing

[0015] FIGS. 1a, FIGS. 1b, and FIGS. 1c are a perspective view, a cross-sectional view, and an exploded perspective view illustrating a cylindrical secondary battery according to an embodiment of the present invention. FIGS. 2a to 2d are cross-sectional views illustrating a cap assembly of a cylindrical secondary battery according to a comparative example and an embodiment of the present invention. FIG. 3 is a table summarizing whether the cap assembly of a cylindrical secondary battery according to an embodiment and a comparative example of the present invention is deformed. Specific details for implementing the invention

[0016] The embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, and the following embodiments may be modified in various different forms, and the scope of the invention is not limited to the following embodiments. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the spirit of the invention to those skilled in the art.

[0017] Additionally, in the drawings below, the thickness or size of each layer is exaggerated for convenience and clarity of explanation, and like reference numerals in the drawings refer to like elements. As used herein, the term "and / or" includes any one of the listed items and all combinations of one or more thereof. Furthermore, in this specification, the meaning of "connected" refers not only to cases where Member A and Member B are directly connected, but also to cases where Member C is interposed between Member A and Member B so that Member A and Member B are indirectly connected.

[0018] The terms used herein are for describing specific embodiments and are not intended to limit the invention. As used herein, the singular form may include the plural form unless the context clearly indicates otherwise. Additionally, as used herein, "comprise, include" and / or "comprising, including" specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups.

[0019] Although terms such as "first," "second," etc. are used in this specification to describe various components, parts, regions, layers, and / or parts, it is obvious that these components, parts, regions, layers, and / or parts should not be limited by these terms. These terms are used solely to distinguish one component, part, region, layer, or part from another region, layer, or part. Accordingly, the first component, part, region, layer, or part described below may refer to the second component, part, region, layer, or part without departing from the teachings of the present invention.

[0020] Spatial terms such as "beneath," "below," "lower," "above," and "upper" may be used to facilitate understanding of one element or feature depicted in the drawings and another element or feature. These spatial terms are intended to facilitate understanding of the invention according to various process or usage conditions of the invention and are not intended to limit the invention. For example, if an element or feature in the drawings is inverted, an element or feature described as "beneath" or "below" becomes "upper" or "on top." Therefore, "beneath" is a concept that encompasses "upper" or "below."

[0022] FIGS. 1a, FIGS. 1b, and FIGS. 1c are a perspective view, a cross-sectional view, and an exploded perspective view illustrating a secondary battery (100) according to various embodiments of the present invention.

[0023] As illustrated in FIGS. 1a, 1b and 1c, a secondary battery (100) according to the present invention comprises a cylindrical can (110), a cylindrical electrode assembly (120), and a cap assembly (140). In some examples, a center pin (130) coupled to the electrode assembly (120) may be further provided.

[0024] A cylindrical can (110) may include a circular bottom portion (111) and a cylindrical side portion (112) extending a certain length upward from the bottom portion (111). During the manufacturing process of a secondary battery, the top of the cylindrical can (110) is open. Therefore, during the assembly process of a secondary battery, an electrode assembly (120) can be inserted into the cylindrical can (110) together with an electrolyte. In some examples, the cylindrical can (110) may be made of steel, a steel alloy, aluminum, an aluminum alloy, or an equivalent thereof. In some examples, a beading part (113) may be formed inwardly recessed at the bottom of the cap assembly (140) so that the electrode assembly (120) and the cap assembly (140) do not deviate outwardly from the cylindrical can (110), and a crimping part (114) may be formed inwardly bent at the top.

[0025] The electrode assembly (120) may be housed inside a cylindrical can (110). The electrode assembly (120) may include a negative plate (121) coated with a negative active material (e.g., graphite, carbon, etc.), a positive plate (122) coated with a positive active material (e.g., a transition metal oxide (LiCoO2, LiNiO2, LiMn2O4, etc.)), and a separator (123) positioned between the negative plate (121) and the positive plate (122) to prevent short circuits and allow only the movement of lithium ions. In some examples, the negative plate (121), the positive plate (122), and the separator (123) may be wound in a roughly cylindrical shape. In some examples, the negative plate (121) may comprise copper (Cu) or nickel (Ni) foil, the positive plate (122) may comprise aluminum (Al) foil, and the separator (123) may comprise polyethylene (PE) or polypropylene (PP). In some examples, a negative tab (124) extending downward by a certain length may be welded to the negative plate (121), and a positive tab (125) extending upward by a certain length may be welded to the positive plate (122), but the opposite is also possible. In some examples, the negative tab (124) may comprise copper or nickel material, and the positive tab (125) may comprise aluminum material.

[0026] In some examples, the negative tab (124) of the electrode assembly (120) may be welded to the bottom portion (111) of the cylindrical can (110). Thus, the cylindrical can (110) can operate as a negative electrode. Conversely, the positive tab (125) may be welded to the bottom portion (111) of the cylindrical can (110), in which case the cylindrical can (110) can operate as a positive electrode.

[0027] In some examples, a first insulating plate (126) may be interposed between an electrode assembly (120) and a bottom portion (111), with a first hole (126a) formed in the center and a second hole (126b) formed on the outside thereof, which is coupled to a cylindrical can (110). This first insulating plate (126) may prevent the electrode assembly (120) from making electrical contact with the bottom portion (111) of the cylindrical can (110). In some examples, the first insulating plate (126) may prevent the positive plate (122) of the electrode assembly (120) from making electrical contact with the bottom portion (111). In some examples, the first hole (126a) can allow the gas to move quickly upward through the center pin (130) when a large amount of gas is generated due to a malfunction of the secondary battery, and the second hole (126b) can allow the negative tab (124) to pass through and be welded to the bottom part (111).

[0028] In some examples, a second insulating plate (127) may be interposed between an electrode assembly (120) and a cap assembly (140), which is coupled to a cylindrical can (110) and has a first hole (127a) formed in the center and a plurality of second holes (127b) formed on the outside thereof. This second insulating plate (127) may prevent the electrode assembly (120) from making electrical contact with the cap assembly (140). In some examples, the second insulating plate (127) may prevent the negative plate (121) of the electrode assembly (120) from making electrical contact with the cap assembly (140). In some examples, the first hole (127a) can be used to allow the gas to move quickly to the cap assembly (140) when a large amount of gas is generated due to a malfunction of the secondary battery, and the second hole (127b) can be used to allow the positive tab (125) to pass through and be welded to the cap assembly (140). Additionally, the remaining second hole (127b) can be used to allow the electrolyte to flow quickly into the electrode assembly (120) during the electrolyte injection process.

[0029] In some examples, the diameter of the first hole (126a, 127a) of the first and second insulating plates (126, 127) is formed to be smaller than the diameter of the center pin (130), so that the center pin (130) does not come into electrical contact with the bottom part (111) of the cylindrical can (110) or the cap assembly (140) due to external impact.

[0030] In some examples, the center pin (130) is in the form of a hollow circular pipe and can be attached approximately to the center of the electrode assembly (120). In some examples, the center pin (130) may comprise steel, steel alloy, aluminum, aluminum alloy, or polybutylene terepthalate. This center pin (130) serves to suppress deformation of the electrode assembly (120) during charging and discharging of the battery and serves as a passage for gases generated inside the secondary battery. In some cases, the center pin (130) may be omitted.

[0031] The cap assembly (140) may include a cap-up (141) having a plurality of through holes (141a), a safety vent (142) located below the cap-up (141), a connecting ring (143) located below the safety vent (142), and a cap-down (144) located below the safety vent (142) and the connecting ring (143), having a plurality of through holes (144a), and electrically connected to an anode tab (125). In some examples, the cap assembly (140) may further include an insulating gasket (145) that insulates the cap-up (141), the safety vent (143), and the cap-down (144) from the side (111) of the cylindrical can (110).

[0032] In some examples, the insulating gasket (145) may be substantially compressed between the beading portion (113) and the crimping portion (114) formed on the side (111) of the cylindrical can (110). In some examples, the through hole (141a) of the cap-up (141) and the through hole (144a) of the cap-down (144) may discharge internal gas to the outside when abnormal internal pressure occurs inside the cylindrical can (110). In some examples, internal gas may invert the safety vent (143) upward through the through hole (144a) of the cap-down (144), electrically disconnecting the safety vent (143) from the cap-down (144), and then the safety vent (144) may be torn, allowing the internal gas to be discharged to the outside through the through hole (141a) of the cap-up (141).

[0033] In some examples, an electrolyte (not shown in the drawing) may be injected into the inside of a cylindrical can (110), which allows lithium ions generated by electrochemical reactions in the negative plate (121) and positive plate (122) inside the battery to move during charging and discharging. This electrolyte may include a non-aqueous organic electrolyte which is a mixture of a lithium salt and a high-purity organic solvent. In some examples, the electrolyte may include a polymer or solid electrolyte using a polymer electrolyte.

[0035] FIGS. 2a to 2d are cross-sectional views illustrating a cap assembly (140) of a cylindrical secondary battery (100) according to a comparative example and an embodiment of the present invention, and FIG. 3 is a table summarizing whether the cap assembly (140) of a cylindrical secondary battery (100) according to an embodiment and a comparative example of the present invention is modified. Here, FIG. 2a corresponds to Comparative Example 1 of FIG. 3, FIG. 2b corresponds to Comparative Example 2 of FIG. 3, FIG. 2c corresponds to Embodiment 2 of FIG. 3, and FIG. 2d corresponds to Embodiment 3 of FIG. 3.

[0036] As illustrated in FIGS. 2a through 2d, the cap assembly (140) may include a cap-up (141), a safety vent (142) positioned below the cap-up (141), a connecting ring (143) positioned below the safety vent (142), and a cap-down (144) positioned below the connecting ring (143). In some examples, the mutual contact (connection or connection) ratio between the safety vent (142) and the cap-down (144) may be approximately 60% to approximately 100%.

[0037] In some examples, the cap-up (141) may include a cap-up contact portion (141b) in contact with a safety vent (142), a cap-up inclined portion (141c) inclined upward from the cap-up contact portion (141b) and having a plurality of through holes (141a), and a cap-up ceiling portion (141d) extending parallel from the cap-up inclined portion (141c). In some examples, an external device may be electrically connected to the cap-up ceiling portion (141d).

[0038] In some examples, the safety vent (142) may include a vent contact portion (142a) that contacts the cap-up contact portion (141b) of the cap-up (141), a vent slope portion (142b) that slopes downward from the vent contact portion (142a), a vent bottom portion (142c) that extends parallel from the vent slope portion (142b), and a vent protrusion portion (142d) that protrudes from the vent bottom portion (142c) and contacts (connects or links) the cap-down (144).

[0039] In some examples, the diameter (length or width) of the vent protrusion (142d) may be approximately 60% to approximately 100% of the diameter (length or width) of the vent bottom (142c). In some examples, the vent protrusion (142d) and the cap-down (144) may come into contact (connect or link) with each other by welding the vent protrusion (142d) to the cap-down (144) by laser or ultrasonic welding.

[0040] In some examples, the vent contact portion (142a) may be folded multiple times to contact the lower, side, and upper surfaces of the cap-up contact portion (141b), respectively. In some examples, the vent bottom portion (142c) may further include a roughly flat vent groove portion (142e) formed on the upper surface facing the vent protrusion (142d). In some examples, the flat vent groove portion (142e) may be formed by pressing it with a mold to form the vent protrusion (142d) on the vent bottom portion (142c). In some examples, the vent bottom portion (142c) of the safety vent (142) may further include a roughly line-shaped vent groove (142f) formed on the upper surface facing the vent protrusion (142d). In some examples, the line-shaped vent groove (142f) can be broken when the pressure inside the battery is higher than a preset pressure, thereby releasing the internal gas to the outside.

[0041] In some examples, the cap-down (144) may include a cap-down contact portion (144b) that contacts the connecting ring (143), a cap-down inclined portion (144c) that slopes downward from the cap-down contact portion (144b), and a cap-down bottom portion (144d) that extends parallel to the cap-down inclined portion (144c). In some examples, the connecting ring (143) may be interposed between the vent contact portion (142a) and the cap-down contact portion (144b). In some examples, the cap-up (141), safety vent (142), and cap-down (144) may be made of a metal material (e.g., copper, nickel, or aluminum), while the connecting ring (143) may be made of an insulating material (e.g., polypropylene or polyethylene).

[0042] In some examples, the cap-down bottom portion (144d) may further include a through hole (144a) penetrating the cap-down bottom portion (144d). In some examples, a vent protrusion (142d) may cover part of the through hole (144a) (see FIG. 2d). In some examples, the cap-down (144) may further include a flat cap-down groove (144e) formed on the lower surface, and the diameter (length or width) of the vent protrusion (142d) may be larger than the diameter (length or width) of the flat cap-down groove (144e). In some examples, a cathode tab (125) (see FIG. 1b) may be welded to the cap-down bottom portion (144d) outside the flat cap-down groove (144e).

[0043] For example, in FIG. 2a (Comparative Example 1), the diameter (length) of the vent bottom portion (142c) may be approximately 11.04 mm, and the diameter (length) of the vent protrusion (142d) may be approximately 3.28 mm. Accordingly, the mutual contact length (diameter) between the vent bottom portion (142c) and the cap-down bottom portion (144d) may be approximately 3.28 mm, and the mutual contact ratio (connection or linkage) may be approximately 29.7%.

[0044] For example, in FIG. 2b (Comparative Example 2), the diameter (length) of the vent bottom portion (142c) may be approximately 11.04 mm, and the diameter (length) of the vent protrusion (142d) may be approximately 4.5 mm. Accordingly, the mutual contact length (diameter) between the vent bottom portion (142c) and the cap-down bottom portion (144d) may be approximately 4.5 mm, and the mutual contact ratio (connection or linkage) may be approximately 40.8%.

[0045] For example, in FIG. 2c (Example 2), the diameter (length) of the vent bottom portion (142c) may be approximately 11.04 mm, and the diameter (length) of the vent protrusion (142d) may be approximately 7.5 mm. Accordingly, the mutual contact length (diameter) between the vent bottom portion (142c) and the cap-down bottom portion (144d) may be approximately 7.5 mm, and the mutual contact ratio (connection or linkage) may be approximately 67.9%.

[0046] For example, in FIG. 2d (Example 3), the diameter (length) of the vent bottom (142c) may be approximately 11.04 mm, and the diameter (length) of the vent protrusion (142d) may be approximately 9.6 mm. Accordingly, the mutual contact length (diameter) between the vent bottom (142c) and the cap-down bottom (144d) may be approximately 9.6 mm, and the mutual contact ratio (connection or linkage) may be approximately 87.0%.

[0047] As illustrated in FIG. 3, when the amount of contact (or amount of contact) of the cap-down bottom portion (144d) relative to the vent bottom portion (142c) (or the amount of contact of the vent bottom portion (142c) relative to the cap-down bottom portion (144d)) is less than approximately 60% (i.e., Comparative Examples 1 to 5), deformation is found in the cap assembly (140) after the beading and crimping process of the secondary battery (100).

[0048] However, when the amount of contact (or amount of contact) of the cap-down bottom portion (144d) with respect to the vent bottom portion (142c) (or the amount of contact) of the vent bottom portion (142c) with respect to the cap-down bottom portion (144d) is approximately 60% to 100% (i.e., Examples 1 to 4), no deformation was found in the cap assembly (140) after the beading and crimping process of the secondary battery (100).

[0049] In FIG. 3, the vent bottom length (mm) may include the diameter of the vent bottom (142c), and the contact length (mm) may include the contact diameter between the vent protrusion (142d) and the cap-down bottom (144d). Additionally, the usage amount (%) may include the ratio of the contact length between the vent protrusion (142d) and the cap-down bottom (144d) to the length of the vent bottom (142c).

[0050] In some examples, as illustrated in FIG. 3, the length of the vent bottom portion (142c) may be approximately 11.04 mm, and the contact length, i.e., the length of the vent protrusion (142d), may 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 may be 7.0 mm, 7.5 mm, 9.6 mm, and 11.0 mm in Examples 1 to 4, respectively. Additionally, the usage amount may be 29.7%, 40.08%, 49.8%, 54.3%, and 58.9% in Comparative Examples 1 to 5, respectively, and may be 63.7%, 67.9%, 87.0%, and 100.0% in Examples 1 to 4, respectively.

[0051] As shown in FIG. 3, in Comparative Examples 1 to 5, deformation occurred in the cap assembly during the battery manufacturing process, whereas in Examples 1 to 4, no deformation occurred in the cap assembly during the battery manufacturing process. Therefore, it can be said that the mutual contact ratio between the safety vent and the cap down is preferably 60% to 100%.

[0052] In this way, an embodiment of the present invention can provide a cylindrical secondary battery (100) capable of preventing deformation of the cap assembly (140) during the manufacturing process or during use. In some examples, by making the mutual contact ratio between the safety vent (142) and the cap down (144) approximately 40% to approximately 100% with respect to the area of ​​the vent bottom portion (142c), deformation of the cap assembly (140) is prevented during the manufacturing process or during use, thereby providing a cylindrical secondary battery (100) in which sealing performance is not degraded and there is no change in overall height.

[0054] The above description is merely one embodiment for implementing the present invention, and the present invention is not limited to the above-described embodiment. The technical spirit of the present invention extends to the scope in which various modifications can be made by anyone with ordinary knowledge in the field to which the invention belongs, without departing from the essence of the invention as claimed in the following patent claims. Explanation of the symbols

[0055] 100; secondary battery 110; can 120; electrode assembly 140; cap assembly 141; Cap-up 141a; Through hole 141b; Cap-up contact portion 141c; Cap-up inclined portion 141d; Cap-up ceiling part 142; Safety vent 142a; Vent contact portion 142b; Vent slope portion 142c; Vent bottom 142d; Vent protrusion 142e; vent groove 142f; vent groove 143; connecting ring 144; cap down 144a; through hole 144b; cap-down contact part 144c; Cap-down slope 144d; Cap-down bottom 144e; Cap-down groove

Claims

Claim 1 A cylindrical secondary battery comprising: a cylindrical can; an electrode assembly accommodated in the cylindrical can; and a cap assembly that seals the electrode assembly by closing the cylindrical can, wherein the cap assembly comprises a cap-up, a cap-down below the cap-up, and a safety vent between the cap-up and the cap-down, wherein the mutual contact ratio between the safety vent and the cap-down is 60% to 100%, and the safety vent comprises a vent contact portion that contacts the cap-up, a vent inclined portion inclined downward from the vent contact portion, a vent bottom portion extending parallel to the vent inclined portion, and a vent protrusion portion protruding from the vent bottom portion and contacting the cap-down, wherein the diameter of the vent protrusion portion is 60% to 100% of the diameter of the vent bottom portion. Claim 2 delete Claim 3 delete Claim 4 A cylindrical secondary battery according to claim 1, wherein the vent bottom portion further comprises a flat vent groove formed on an upper surface opposite to the vent protrusion. Claim 5 A cylindrical secondary battery according to claim 1, wherein the cap-down includes a cap-down through-hole penetrating the cap-down, and the vent protrusion covers a portion of the cap-down through-hole. Claim 6 A cylindrical secondary battery according to claim 1, wherein the vent protrusion is welded to the cap-down. Claim 7 A cylindrical secondary battery according to claim 1, wherein the vent bottom portion further comprises a line-shaped vent groove formed on an upper surface opposite to the vent protrusion. Claim 8 A cylindrical secondary battery according to claim 1, wherein the cap-down further includes a flat cap-down groove formed on the lower surface, and the diameter of the vent protrusion is larger than the diameter of the flat cap-down groove.

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