Rechargeable battery

Abstract

A rechargeable battery includes: an electrode assembly; a can accommodating the electrode assembly in an inner region of the can; and a cap assembly coupled to the canister to seal the canister. The cover assembly includes a safety vent and a lower cover, the safety vent and the lower cover being stacked with a connecting member interposed between the safety vent and the lower cover. The safety vent includes: a central portion joined to the lower cover; the middle part comprises a step part and a groove; a fusion portion in contact with the connection member; and a wing portion surrounding the fusion portion. At least three of the central portion, the intermediate portion, the fused portion, and the wing portions have different thicknesses.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0077374 filed in the Korean Intellectual Property Office on June 16, 2023 under 35 U.S.C. 119(a)-(d), the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a rechargeable battery, and more particularly, to a rechargeable battery having a safety vent. Background Art

[0004] In general, a rechargeable battery includes an electrode assembly, a can accommodating the electrode assembly therein, and a cap assembly assembled in an opening of the can to seal the can and allow current generated in the electrode assembly to flow to an external device. Summary of the invention

[0005] The present disclosure provides a rechargeable battery capable of easily controlling an operating pressure and a rupture pressure of a safety vent.

[0006] A rechargeable battery according to an embodiment includes: an electrode assembly; a can accommodating the electrode assembly in an inner region of the can; and a cap assembly coupled to the can to seal the can. The cap assembly includes a safety vent and a lower cover, the safety vent and the lower cover are stacked and a connecting member is interposed between the safety vent and the lower cover. The safety vent includes a central portion joined to the lower cover, an intermediate portion including a step portion and a groove, a fusion portion contacting the connecting member, and a wing portion surrounding the fusion portion. At least three of the central portion, the intermediate portion, the fusion portion, and the wing portion have different thicknesses.

[0007] The wing may include a first portion and a second portion overlapping the first portion, and formed by bending the second portion on the first portion, and the thickness of the wing may be the thickness of one of the first portion and the second portion alone. The middle portion may be provided between the central portion and the fusion portion, and the groove may be provided on a first surface of the middle portion between the step portion and the fusion portion, the first surface facing the lower cover. The cap assembly may be coupled to the can via an insulating gasket surrounding the wing.

[0008] The central portion may have a first thickness T1, the middle portion may have a second thickness T2, the fused portion may have a third thickness T3, and the wing portion may have a fourth thickness T4, and the safety vent may satisfy the following condition (1):

[0009] T1 > (T2 = T3) > T4 --- (1).

[0010] On the other hand, the middle portion may include an inner portion and an outer portion, the inner portion includes a step portion, and the outer portion includes a groove. The central portion may have a fifth thickness T5, the inner portion may have a sixth thickness T6, the outer portion may have a seventh thickness T7, the fusion portion may have an eighth thickness T8, the wing portion may have a ninth thickness T9, and the safety vent may satisfy the following condition (2):

[0011] T5 > T6 > (T7 = T8 = T9) --- (2).

[0012] On the other hand, the central portion may have a tenth thickness T10, the middle portion may have an eleventh thickness T11, the fused portion may have a twelfth thickness T12, and the wing portion may have a thirteenth thickness T13, and the safety vent may satisfy the following condition (3):

[0013] (T10 = T12)> T13 > T11 --- (3).

[0014] A rechargeable battery according to another embodiment includes: an electrode assembly; a can accommodating the electrode assembly in an inner area of ​​the can; and a cap assembly coupled to the can to seal the can. The cap assembly includes: a safety vent and a lower cover, the safety vent and the lower cover are stacked and a connecting member is interposed between the safety vent and the lower cover; and an upper cover covering the safety vent. The safety vent includes a central portion joined to the lower cover, an intermediate portion including a step portion and a groove, a fusion portion contacting the connecting member, and an edge portion surrounding the fusion portion. At least three of the central portion, the intermediate portion, the fusion portion, and the edge portion have different thicknesses.

[0015] The intermediate portion may be disposed between the central portion and the fusion portion, and the groove may be disposed on a first surface of the intermediate portion between the step portion and the fusion portion, the first surface facing the lower cover.

[0016] The central portion may have a first thickness T1, the middle portion may have a second thickness T2, the fused portion may have a third thickness T3, and the edge portion may have a fourth thickness T4, and the safety vent may satisfy the following condition (4):

[0017] T1 > (T2 = T3) > T4 --- (4).

[0018] On the other hand, the middle portion may include an inner portion and an outer portion, the inner portion includes a step portion, and the outer portion includes a groove. The central portion may have a fifth thickness T5, the inner portion may have a sixth thickness T6, the outer portion may have a seventh thickness T7, the fusion portion may have an eighth thickness T8, and the edge portion may have a ninth thickness T9, and the safety vent may satisfy the following condition (5):

[0019] T5 > T6 > (T7 = T8 = T9) --- (5).

[0020] On the other hand, the central portion may have a tenth thickness T10, the middle portion may have an eleventh thickness T11, the fused portion may have a twelfth thickness T12, and the edge portion may have a thirteenth thickness T13, and the safety vent may satisfy the following condition (6):

[0021] (T10 = T12)> T13 > T11 --- (6).

[0022] According to some embodiments, a method for manufacturing a rechargeable battery is provided. The method may include: accommodating an electrode assembly in an inner region of a can; and sealing the can with a cap assembly. The cap assembly may include a safety vent and a lower cover, the safety vent and the lower cover are stacked and a connecting member is interposed between the safety vent and the lower cover, the safety vent includes: a central portion joined to the lower cover; an intermediate portion including a step portion and a groove; a fusion portion in contact with the connecting member; and a wing portion surrounding the fusion portion; and wherein at least three of the central portion, the intermediate portion, the fusion portion, and the wing portion have different thicknesses.

[0023] The wing may include a first portion and a second portion overlapping the first portion and formed by bending the second portion on the first portion; and a thickness of the wing may have a thickness of one of the first portion and the second portion alone.

[0024] The intermediate portion may be disposed between the central portion and the fusion portion; and the groove may be disposed on a first surface of the intermediate portion between the step portion and the fusion portion, the first surface facing the lower cover.

[0025] In some embodiments, sealing the can with the cap assembly may include coupling the cap assembly to the can via an insulating gasket surrounding the wing.

[0026] The center portion may have a first thickness T1, the middle portion may have a second thickness T2, the fused portion may have a third thickness T3, and the wing portion may have a fourth thickness T4, and the safety vent may satisfy the following condition: T1>(T2=T3)>T4.

[0027] The middle portion may include an inner portion and an outer portion, the inner portion including a step portion, and the outer portion including a groove; and the central portion may have a fifth thickness T5, the inner portion may have a sixth thickness T6, the outer portion may have a seventh thickness T7, the fusion portion may have an eighth thickness T8, and the wing portion may have a ninth thickness T9, and the safety exhaust may satisfy the following conditions: T5>T6>(T7=T8=T9).

[0028] The center portion may have a tenth thickness T10, the middle portion may have an eleventh thickness T11, the fusion portion may have a twelfth thickness T12, and the wing portion may have a thirteenth thickness T13, and the safety vent may satisfy the following condition: (T10=T12)>T13>T11.

[0029] In some embodiments, the method may further include forming a safety vent of the cap assembly at least in part by bonding the central portion to the lower cap.

[0030] According to the embodiment, the expansion curve of a single safety vent can be easily controlled by adjusting the shape of the safety vent and the thickness difference of each region, and the operating pressure and rupture pressure in the rechargeable battery to which the safety vent is applied can be easily controlled. In addition, the rechargeable battery according to the embodiment can improve the reliability and safety of the rechargeable battery by minimizing the operational deviation (deviation) of the cap assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a perspective view of a rechargeable battery according to an embodiment.

[0032] Figure 2 According to some embodiments Figure 1 A cross-sectional view of a rechargeable battery is shown in FIG.

[0033] Figure 3 According to some embodiments Figure 2 An enlarged view of a cap assembly of a rechargeable battery is shown in FIG.

[0034] Figure 4 Examples according to some embodiments Figure 3 The safety vent in the cover assembly shown in FIG.

[0035] Figure 5 and Figure 6 is a diagram for describing an operation process of a cover assembly according to some embodiments.

[0036] Figure 7 is an enlarged view of a cap assembly of a rechargeable battery according to a second embodiment.

[0037] Figure 8 Examples according to some embodiments Figure 7 The safety vent in the cover assembly shown in FIG.

[0038] Fig. 9 is an enlarged view of a cap assembly of a rechargeable battery according to a third embodiment.

[0039] Fig.10 Examples according to some embodiments Fig. 9 The safety vent in the cover assembly shown in FIG.

[0040] Fig.11 Graphs illustrating expansion curves of three safety vents according to the first to third embodiments.

[0041] Fig.12 is a partially enlarged cross-sectional view of a rechargeable battery according to a fourth embodiment.

[0042] Fig.13 Examples according to some embodiments Fig.12 A safety vent in a rechargeable battery is shown in FIG.

[0043] Fig.14 is a sectional view of a cap assembly of a rechargeable battery according to a fifth embodiment.

[0044] Fig.15 Examples according to some embodiments Fig.14 The safety vent in the cover assembly shown in FIG.

[0045] Fig.16 is a sectional view of a cap assembly of a rechargeable battery according to a sixth embodiment.

[0046] Fig.17 Examples according to some embodiments Fig.16 The safety vent in the cover assembly shown in FIG. DETAILED DESCRIPTION

[0047] Various aspects of the technology will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art will appreciate, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

[0048] As described herein, a rechargeable battery may include: an electrode assembly; a can that contains the electrode assembly inside; and a cap assembly that is assembled in an opening of the can to seal the can and allow current generated in the electrode assembly to flow to an external device. The cap assembly may include a safety vent to prevent the rechargeable battery from exploding.

[0049] When the internal pressure of the tank increases, the safety vent deforms, blocking the flow of current, and when the pressure continues to increase, the safety vent ruptures, releasing the internal gas. The operating pressure at which the safety vent deforms and blocks the flow of current and the rupture pressure when the internal gas is discharged due to rupture depend on the shape and thickness of the safety vent.

[0050] Figure 1 is a perspective view of a rechargeable battery according to an embodiment. Figure 2 According to some embodiments Figure 1 A cross-sectional view of a rechargeable battery is shown in FIG. Figure 3According to some embodiments Figure 2 An enlarged view of a cap assembly of a rechargeable battery is shown in FIG.

[0051] refer to Figures 1 to 3 , the rechargeable battery 100 according to the present embodiment may include a can 120, an electrode assembly 130 accommodated inside the can 120, and a cap assembly 140 assembled to an opening of the can 120 to seal the can 120. The cap assembly 140 may include a safety vent 20 that prevents the rechargeable battery 100 from exploding. The safety vent 20 may be referred to as a current interrupt device (CID).

[0052] The rechargeable battery 100 of the present embodiment may have a cylindrical shape, but is not limited to this example. The tank 120 may include a bottom portion 121 and a side portion 122. The bottom portion 121 may be a disc, and the side portion 122 may be cylindrical. In the manufacturing process of the rechargeable battery 100, one side of the tank 120 (e.g., the upper portion opposite to the bottom portion 121) is open, and the electrode assembly 130 may be accommodated inside the tank 120 together with the electrolyte. In some embodiments, the tank 120 may be made of steel, steel alloy, aluminum, aluminum alloy, etc.

[0053] The curling portion 123 and the crimping portion 124 may be provided on the side portion 122 of the can 120. The curling portion 123 may be a portion that is concavely deformed toward the inside of the can 120. The crimping portion 124 may be a portion where the edge of the side portion 122 is vertically bent toward the inside of the side portion 122. The movement of the electrode assembly 130 may be suppressed by the curling portion 123, and the cap assembly 140 may be fixed to the can 120 by the curling portion 123 and the crimping portion 124.

[0054] The electrode assembly 130 may include a positive electrode 131, a negative electrode 132, and a separator 133. The positive electrode 131 may include a positive electrode substrate and a positive electrode active material layer disposed on the positive electrode substrate. The negative electrode 132 may include a negative electrode substrate and a negative electrode active material layer disposed on the negative electrode substrate. The positive electrode substrate may include, for example, aluminum foil, and the positive electrode active material may include a transition metal oxide, such as LiCoO2, LiNiO2, LiMn2O4. The negative electrode substrate may include, for example, copper foil or nickel foil, and the negative electrode active material may include, for example, graphite or carbon.

[0055] The separator 133 insulates the positive electrode 131 and the negative electrode 132 while allowing movement of lithium ions. The separator 133 may include, for example, polyethylene or polypropylene.

[0056] The positive electrode 131, the negative electrode 132, and the separator 133 may be wound into a substantially cylindrical shape, and a cylindrical center pin 134 may be disposed at the center of the electrode assembly 130. The center pin 134 may suppress deformation of the electrode assembly 130 during charging and discharging of the rechargeable battery 100, and may serve as a passage for gas generated inside the rechargeable battery 100. In some cases, the center pin 134 may be omitted.

[0057] The positive electrode 131 may include a positive electrode tab 135 attached to the positive electrode substrate, and the negative electrode 132 may include a negative electrode tab 136 attached to the negative electrode substrate. The positive electrode tab 135 and the negative electrode tab 136 may be disposed on opposite sides of each other. For example, the positive electrode tab 135 may be disposed on a side (e.g., an upper side) of the electrode assembly 130 facing the cap assembly 140, and may be fixed to the cap assembly 140. The negative electrode tab 136 may be disposed on a side (e.g., a lower side) of the electrode assembly 130 facing the bottom portion 121 of the can 120, and may be fixed to the bottom portion 121.

[0058] The first insulating plate 151 may be disposed between the electrode assembly 130 and the cap assembly 140, and the second insulating plate 152 may be disposed between the electrode assembly 130 and the bottom portion 121 of the can 120. The first insulating plate 151 may prevent the negative electrode 132 of the electrode assembly 130 from contacting the cap assembly 140, and the second insulating plate 152 may prevent the positive electrode 131 of the electrode assembly 130 from contacting the can 120.

[0059] A hole connected to the inside of the center pin 134, a hole for the positive electrode tab 135 to pass through, and a plurality of holes for electrolyte injection may be provided at the first insulating plate 151. A hole connected to the inside of the center pin 134 and a hole for the negative electrode tab 136 to pass through may be provided at the second insulating plate 152.

[0060] The cap assembly 140 may include: a safety vent 20, which also serves as an upper cap; a lower cap 30, which is disposed on a side (e.g., a lower side) of the safety vent 20 facing the electrode assembly 130; and a connection member 40 disposed between the safety vent 20 and the lower cap 30. The cap assembly 140 may further include an insulating gasket 50 that insulates the safety vent 20 from the side portion 122 of the can 120. The insulating gasket 50 may surround the edge of the safety vent 20 and may be squeezed between the crimping portion 123 and the crimping portion 124 of the can 120.

[0061] Figure 4 Examples according to some embodiments Figure 3 The safety vent in the cover assembly shown in FIG.

[0062] refer to Figure 3 and Figure 4, the safety vent 20 and the lower cover 30 may have a substantially disc shape and may be made of a conductive metal. The diameter of the lower cover 30 may be smaller than the diameter of the safety vent 20, and the respective center portions A10 and 31 of the safety vent 20 and the lower cover 30 may be engaged with each other. The connecting member 40 may have a ring shape and may be made of an insulating material.

[0063] The safety vent 20 may be divided into four regions according to its position. Specifically, the safety vent 20 may include a central portion A10 provided with a contact portion 21, an intermediate portion A20 provided with a step portion 22 and a groove 23, a fusion portion A30 contacting the connection member 40, and a wing portion A40 forming an edge of the safety vent 20.

[0064] The contact portion 21 may be a portion contacting the lower cover 30 on one surface (eg, the lower surface) of the safety vent 20 facing the lower cover 30, and may be integrally joined to the lower cover 30 by a method such as welding. The central portion A10 provided with the contact portion 21 has a first thickness T1.

[0065] The step portion 22 may be a portion that is inclined toward the outside (e.g., the upper side) of the cap assembly 140 so as to protrude away from the lower cover 30. The groove 23 may be provided at the middle portion A20 of the safety vent 20 on one surface (e.g., the lower surface) of the safety vent 20 facing the lower cover 30, and the thickness of the safety vent 20 may be thinner than other portions. The groove 23 may be V-shaped, and the depth of the groove 23 may be greater than half the thickness of the middle portion A20, but is not limited thereto. The groove 23 may be provided between the step portion 22 and the fusion portion A30. The middle portion A20 has a second thickness T2 except for the portion where the groove 23 is provided.

[0066] The middle portion A20 and the fusion portion A30 may be disposed at a predetermined distance from the lower cover 30, and the connection member 40 may be disposed between the fusion portion A30 and the lower cover 30. The connection member 40 may be integrally coupled with the fusion portion A30 and the lower cover 30 by fusion. The fusion portion A30 has a third thickness T3.

[0067] The wing A40 may include a first portion 24 and a second portion 25 that overlap by bending the safety exhaust member 20. The first portion 24 may be arranged in parallel with the fusion portion A30, and the second portion 25 may be bent from the first portion 24 and overlap with the first portion 24. Compared with the first portion 24, the second portion 25 may be arranged on the outside (e.g., the upper side) of the cover assembly 140. The wing A40 has a fourth thickness T4. At this time, the fourth thickness T4 is the thickness of each of the first portion 24 and the second portion 25, respectively. That is, as Figure 4 As illustrated in FIG. 2 , the fourth thickness T4 is equal to the thickness of the first portion 24 or the second portion 25 alone.

[0068] Since the wing A40 is an edge of the safety vent 20 coupled to the can 120 via the insulating gasket 50, the wing A40 must have high rigidity. Since the first portion 24 and the second portion 25 overlap by bending to form the wing A40, the wing A40 may have high rigidity.

[0069] The lower cover 30 may be divided into two areas according to its position. Specifically, the lower cover 30 may include a central portion 31 overlapping the central portion A10 of the safety vent 20 and a peripheral portion 32 surrounding the central portion 31. One surface (e.g., the upper surface) of the central portion 31 facing the safety vent 20 may be bonded to the contact portion 21, and one surface (e.g., the upper surface) of the peripheral portion 32 may be disposed (e.g., at least partially by the connecting member 40) to be separated from the middle portion A20 and the fusion portion A30.

[0070] The entire surface (e.g., upper surface) of the lower cover 30 facing the safety exhaust member 20 may be a flat surface without curvature, and the thickness of the central portion 31 may be smaller than the thickness of the peripheral portion 32. The diameter of the lower cover 30 may be the same as or similar to the diameter of the fusion portion A30. At least one first through hole 35 may be provided in the central portion 31, and at least one second through hole 36 may be provided in the peripheral portion 32. Each of the first through hole 35 and the second through hole 36 may have an arc shape, and the width of the first through hole 35 may be smaller than the width of the second through hole 36.

[0071] The positive electrode tab 135 of the electrode assembly 130 may be fixed to one surface (e.g., the lower surface) of the lower cover 30, and the lower cover 30 and the safety vent 20 may be positively charged. The safety vent 20 may contact an external device and function as a terminal (positive electrode terminal) that allows current to flow to the external device.

[0072] During use of the rechargeable battery 100 , gas may be generated inside the can 120 due to various reasons, and the internal pressure of the rechargeable battery 100 may increase due to the gas. Figure 5 and Figure 6 FIG. 1 is a diagram illustrating an operation process of a cover assembly according to some embodiments.

[0073] refer to Figure 3 , Figure 5 and Figure 6 When gas is generated, pressure is continuously applied to the safety vent 20 through the first through hole 35 and the second through hole 36 of the lower cover 30. Under a certain internal pressure, the safety vent 20 may be deformed toward the outside (e.g., the upper side) of the cap assembly 140, so that the safety vent 20 and the lower cover 30 may be separated from each other. At this time, the central portion 31 of the lower cover 30 may be disconnected from the peripheral portion 32, and raised together with the safety vent 20 while being attached to the contact portion 21 of the safety vent 20 (e.g., as shown in FIG. 1 ). Figure 5 ). The current may be blocked due to the separation of the safety vent 20 and the lower cover 30. Thereafter, when the pressure continues to increase, the safety vent 20 may rupture around the groove 23, and the internal gas may be discharged (e.g., as shown in FIG. 1 ). Figure 6 ).

[0074] Reference again Figure 3 and Figure 4 , the safety vent 20 may include a portion formed by forging a raw material to have a thickness less than that of the original raw material. As described herein, the safety vent 20 may be divided into four regions: A10, A20, A30, and A40 according to the location of the region. The four regions A10, A20, A30, and A40 each have first to fourth thicknesses T1, T2, T3, and T4, and at least three of the first to fourth thicknesses T1, T2, T3, and T4 may have different values. In the rechargeable battery 100 of the first embodiment, the safety vent 20 may satisfy the following equation 1.

[0075] (Equation 1)

[0076] T1>(T2=T3)>T4

[0077] In the safety vent 20, the thickness T1 of the center portion A10 may be the largest, and the thickness T4 of the wing portion A40 may be the smallest. The thickness T2 of the middle portion A20 and the thickness T3 of the fusion portion A30 may be smaller than the thickness T1 of the center portion A10 and larger than the thickness T4 of the wing portion A40. The safety vent 20 generally has a smaller thickness as it moves away from the center portion A10, and the wing portion A40 may be made of a first portion 24 and a second portion 25 overlapped by bending.

[0078] The pressure at which the safety vent 20 deforms and blocks the flow of current is referred to as the operating pressure (see, for example, Figure 5 ), and the pressure when the safety vent 20 ruptures around the groove 23 to discharge the internal gas is called the rupture pressure (see, for example, Figure 6 ). The operating pressure and the bursting pressure depend largely on the shape and thickness of the safety vent 20. In the present embodiment, due to the various thickness differences in each area of ​​the safety vent 20, the operating pressure and the bursting pressure can be easily controlled.

[0079] For example, assuming that the safety vent of the comparative example has one thickness or only one thickness difference, the variables that can control the operating pressure and the rupture pressure are not diverse, so it is not easy to control the operating pressure and the rupture pressure. On the other hand, in the rechargeable battery 100 according to the present embodiment, the safety vent 20 can change the variables that can control the operating pressure and the rupture pressure by using the thickness difference of each region, so the operating pressure and the rupture pressure can be easily controlled.

[0080] Next, a modification of the cap assembly 140 will be described. Hereinafter, configurations different from those of the first embodiment will be mainly described, and repeated descriptions of configurations the same as those of the first embodiment will be omitted.

[0081] Figure 7 is an enlarged view of a cap assembly of a rechargeable battery according to a second embodiment. Figure 8 Examples according to some embodiments Figure 7 The safety vent in the cap assembly shown in FIG. 2. The rechargeable battery of the second embodiment has the same or similar configuration as that of the first embodiment described above, except for aspects of the safety vent described below.

[0082] refer to Figure 7 and Figure 8 , the safety vent 201 of the cap assembly 141 may include a central portion A11 provided with a contact portion 211, a middle portion A21 provided with a step portion 221 and a groove 231, a fusion portion A31 contacting the connection member 40, and a wing portion A41 forming an edge of the safety vent 201. At this time, the middle portion A21 may be divided into an inner portion A211 provided with a step portion 221 and an outer portion A212 provided with a groove 231. The wing portion A41 may include a first portion 241 and a second portion 251 overlapped by bending.

[0083] The center portion A11, the inner portion A211, the outer portion A212, the fusion portion A31 and the wing portion A41 have fifth thickness T5, sixth thickness T6, seventh thickness T7, eighth thickness T8 and ninth thickness T9, respectively. In the rechargeable battery of the second embodiment, the safety vent 201 may satisfy Equation 2 below.

[0084] (Equation 2)

[0085] T5>T6>(T7=T8=T9)

[0086] In the safety vent 201, the thickness T5 of the central portion A11 may be the largest, and the thickness T7 of the outer portion A212, the thickness T8 of the fusion portion A31, and the thickness T9 of the wing portion A41 may be the smallest. The thickness T6 of the inner portion A211 may be smaller than the thickness T5 of the central portion A11, and may be larger than the thickness T7 of the outer portion A212, the thickness T8 of the fusion portion A31, and the thickness T9 of the wing portion A41.

[0087] The width of the inner portion A211 provided with the step portion 221 may be greater than the width of the outer portion A212 provided with the groove 231, and the groove 231 may be provided closer to the connection member 40 (e.g., provided closer to the connection member 40 than the step portion 221). The safety vent 201 according to the present embodiment also generally has a smaller thickness as it moves away from the center portion A11, and has a total of three different thicknesses.

[0088] Fig. 9 is an enlarged view of a cap assembly of a rechargeable battery according to a third embodiment. Fig.10 Examples according to some embodiments Fig. 9 The safety vent in the cap assembly shown in FIG. 2 . The rechargeable battery of the third embodiment has the same or similar configuration as that of the first embodiment described above, except for aspects of the safety vent described below.

[0089] refer to Fig. 9 and Fig.10 The safety vent 202 of the cap assembly 142 may include a central portion A12 provided with a contact portion 212, an intermediate portion A22 provided with a step portion 222 and a groove 232, a fusion portion A32 contacting the connection member 40, and a wing portion A42 forming an edge of the safety vent 202. The wing portion A42 may include a first portion 242 and a second portion 252 overlapped by bending.

[0090] The center portion A12, the middle portion A22, the fusion portion A32, and the wing portion A42 have a tenth thickness T10, an eleventh thickness T11, a twelfth thickness T12, and a thirteenth thickness T13, respectively. In the rechargeable battery of the third embodiment, the safety vent 202 may satisfy Equation 3 below.

[0091] (Equation 3)

[0092] (T10=T12)>T13>T11

[0093] In the safety vent 202, the thickness T10 of the center portion A12 and the thickness T12 of the fusion portion A32 may be the largest, and the thickness T11 of the middle portion A22 may be the smallest. The thickness T13 of the wing portion A42 may be smaller than the thickness T10 of the center portion A12 and the thickness T12 of the fusion portion A32, and may be larger than the thickness T11 of the middle portion A22. The safety vent 202 according to the present embodiment has three different thicknesses. Unlike the first and second embodiments described above, the safety vent 202 has the smallest thickness at the middle portion A22.

[0094] Fig.11 Graphs illustrating expansion curves of three safety vents according to the first to third embodiments.

[0095] refer to Fig.11 , the expansion curve is a curve of the change in deformation amount in response to the pressure applied to the safety vent, and is based on the measurement results of a single safety vent before being applied to a rechargeable battery. The thickness of each region of each of the safety vents of the first to third embodiments used in the experiment is shown in Table 1 below.

[0096] (Table 1)

[0097]

[0098] Due to the difference in shape and thickness of each region, the three types of safety vents according to the first to third embodiments achieve different expansion curves. Specifically, compared with the safety vent of the first embodiment, the safety vent of the second embodiment has a different groove position, and the thickness of the portion provided with the groove is less than that of the first embodiment. Compared with the safety vents of the first and second embodiments, the safety vent of the third embodiment has the smallest difference in thickness in the middle portion provided with the step portion and the groove in the entire safety vent.

[0099] Due to these differences, the safety vent of the first embodiment shows the smallest deformation under the same pressure conditions, and the safety vent of the third embodiment shows the largest deformation under the same pressure conditions. In this way, the expansion curve of the safety vent can be easily controlled by adjusting the shape of the safety vent and the thickness difference of each area.

[0100] Next, the operating pressure and rupture pressure of eight samples of each rechargeable battery of the first to third embodiments were measured and are shown in the following Table 2. The thickness of each area of ​​the safety vent applied to the rechargeable battery is the same as Table 1, and the target specification of the operating pressure of all rechargeable batteries according to the first to third embodiments is 16.0±2.0Kgf / cm 2, and the target specification of burst pressure is 25.0±4.0Kgf / cm 2 .

[0101] (Table 2)

[0102]

[0103]

[0104] The fact that the operating pressure and the rupture pressure are the same in the rechargeable battery of the third embodiment means that the deformation of the safety vent member separating from the lower cover and the rupture centered on the groove occur simultaneously. It can be seen that in the case of the rechargeable batteries of the first and second embodiments, the operating pressure and the rupture pressure of the eight samples are all within the target specification, and in the case of the rechargeable battery of the third embodiment, the operating pressure of the eight samples is within the target specification.

[0105] According to the above-described embodiment, the expansion curve of a single safety vent can be easily controlled by adjusting the shape of the safety vent and the thickness difference of each region of the safety vent, and the operating pressure and rupture pressure in a rechargeable battery to which the safety vent is applied can be easily controlled. In addition, the rechargeable battery according to the embodiment can improve the reliability and safety of the rechargeable battery by minimizing the operational deviation (deviation) of the cap assembly.

[0106] Fig.12 is a partially enlarged cross-sectional view of a rechargeable battery according to a fourth embodiment. Fig.13 Examples according to some embodiments Fig.12 The safety vent in the rechargeable battery shown in FIG. 2. The rechargeable battery of the fourth embodiment has the same structure as the first embodiment described above, except for the aspects of the cap assembly described herein.

[0107] refer to Fig.12 and Fig.13 , the cap assembly 143 may further include an upper cap 60 covering the safety vent 203, and the safety vent 203 may include a flat edge portion A50 instead of a wing portion. The upper cap 60 may be disposed on the outside (e.g., the upper side) of the safety vent 203, and may contact the safety vent 203 and may be electrically connected to the safety vent 203. The upper cap 60 may contact an external device and function as a terminal (e.g., a positive electrode terminal) that allows current to flow to the external device.

[0108] The upper cover 60 may include a terminal portion 61 for contacting an external device, an inclined portion 62 surrounding the terminal portion 61, and a coupling portion 63 surrounding the inclined portion 62 and contacting the safety vent 203. At least one third through hole 65 for exhaust may be provided in the inclined portion 62, and the coupling portion 63 may be bent to cover both one surface (e.g., the upper surface) and the side surface of the edge portion A50.

[0109] The safety vent 203 may include a flat edge portion A50 having a fourth thickness T4 instead of a wing portion. The safety vent 203 may have the same configuration as the safety vent 20 of the first embodiment described above, except that the wing portion is replaced by the edge portion A50. In the rechargeable battery of the fourth embodiment, the safety vent 203 may satisfy the condition of the above-mentioned equation 1.

[0110] Fig.14 is a sectional view of a cap assembly of a rechargeable battery according to a fifth embodiment. Fig.15 Examples according to some embodiments Fig.14 The safety vent in the cap assembly shown in FIG. 2. The rechargeable battery of the fifth embodiment has the same structure as the second embodiment described above, except for the aspect of the cap assembly described next.

[0111] refer to Fig.14 and Fig.15 , the cap assembly 144 may further include an upper cap 60 covering the safety vent 204, and the safety vent 204 may include a flat edge portion A51 having a ninth thickness T9 instead of a wing portion. The upper cap 60 may be the same as the upper cap of the fourth embodiment, and the safety vent 204 may have the same configuration as the safety vent 201 of the above-described second embodiment except that the wing portion is replaced by the flat edge portion A51. In the rechargeable battery of the fifth embodiment, the safety vent 204 may satisfy the condition of the above-described equation 2.

[0112] Fig.16 is a sectional view of a cap assembly of a rechargeable battery according to a sixth embodiment. Fig.17 Examples according to some embodiments Fig.16 The safety vent in the cap assembly shown in FIG. The rechargeable battery of the sixth embodiment has the same configuration as the third embodiment described above, except for aspects of the cap assembly described next.

[0113] refer to Fig.16 and Fig.17, the cap assembly 145 may further include an upper cap 60 covering the safety vent 205, and the safety vent 205 may include a flat edge portion A52 having a thirteenth thickness T13 instead of a wing portion. The upper cap 60 may be the same as the upper cap of the fourth embodiment, and the safety vent 205 may have the same configuration as the safety vent 202 of the third embodiment described above, except that the wing portion is replaced by the flat edge portion A52. In the rechargeable battery of the sixth embodiment, the safety vent 205 may satisfy the condition of the above equation 3.

[0114] According to some embodiments, a method for manufacturing a rechargeable battery is provided. The method may include accommodating an electrode assembly in an inner region of a can; and sealing the can with a cap assembly. The cap assembly may include a safety vent and a lower cover, the safety vent and the lower cover are stacked and a connecting member is interposed between the safety vent and the lower cover, the safety vent including: a central portion joined to the lower cover; an intermediate portion including a step portion and a groove; a fusion portion in contact with the connecting member; and a wing portion surrounding the fusion portion; and wherein at least three of the central portion, the intermediate portion, the fusion portion, and the wing portion have different thicknesses.

[0115] The wing may include a first portion and a second portion overlapping the first portion and formed by bending the second portion on the first portion; and a thickness of the wing may individually have a thickness of one of the first portion and the second portion.

[0116] The intermediate portion may be disposed between the central portion and the fusion portion; and the groove may be disposed on a first surface of the intermediate portion between the step portion and the fusion portion, the first surface facing the lower cover.

[0117] In some embodiments, sealing the can with the cap assembly may include coupling the cap assembly to the can via an insulating gasket surrounding the wing.

[0118] The center portion may have a first thickness T1, the middle portion may have a second thickness T2, the fused portion may have a third thickness T3, and the wing portion may have a fourth thickness T4, and the safety vent may satisfy the following condition: T1>(T2=T3)>T4.

[0119] The middle portion may include an inner portion and an outer portion, the inner portion including a step portion, and the outer portion including a groove; and the central portion may have a fifth thickness T5, the inner portion may have a sixth thickness T6, the outer portion may have a seventh thickness T7, the fusion portion may have an eighth thickness T8, and the wing portion may have a ninth thickness T9, and the safety exhaust may satisfy the following conditions: T5>T6>(T7=T8=T9).

[0120] The center portion may have a tenth thickness T10, the middle portion may have an eleventh thickness T11, the fusion portion may have a twelfth thickness T12, and the wing portion may have a thirteenth thickness T13, and the safety vent may satisfy the following condition: (T10=T12)>T13>T11.

[0121] In some embodiments, the method may further include forming a safety vent of the cap assembly at least in part by bonding the central portion to the lower cap.

[0122] While the present disclosure has been described in connection with what are presently considered to be practical embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but on the contrary is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A rechargeable battery, include: Electrode assembly; a can housing the electrode assembly in an interior region of the can; as well as A cap assembly coupled to the can to seal the can and comprising a safety vent and a lower cap, the safety vent and the lower cap being stacked with a connecting member between the safety vent and the lower cap, the safety vent comprising: a central portion joined to the lower cover; a middle portion including a step portion and a groove; a fusion portion in contact with the connection member; and a wing portion surrounding the fusion portion; and At least three of the central portion, the middle portion, the fusion portion and the wing portion have different thicknesses.

2. The rechargeable battery according to claim 1, in: The wing portion includes a first portion and a second portion overlapping the first portion and formed by bending the second portion on the first portion; and The thickness of the wing portion is solely the thickness of one of the first portion and the second portion.

3. The rechargeable battery according to claim 2, in: The intermediate portion is disposed between the central portion and the fused portion; and The groove is provided on a first surface of the intermediate portion between the step portion and the fusion portion, the first surface facing the lower cover.

4. The rechargeable battery according to claim 2, in: The cap assembly is coupled to the can via an insulating gasket surrounding the wing.

5. The rechargeable battery according to claim 2, in: The central portion has a first thickness T1, the middle portion has a second thickness T2, the fused portion has a third thickness T3, and the wing portion has a fourth thickness T4, and the safety vent satisfies the following condition: T1>(T2=T3)>T4.

6. The rechargeable battery according to claim 2, in: The intermediate portion includes an inner portion and an outer portion, the inner portion includes the step portion, and the outer portion includes the groove; and The central portion has a fifth thickness T5, the inner portion has a sixth thickness T6, the outer portion has a seventh thickness T7, the fusion portion has an eighth thickness T8, and the wing portion has a ninth thickness T9, and the safety vent satisfies the following conditions: T5>T6>(T7=T8=T9).

7. The rechargeable battery according to claim 2, in: The central portion has a tenth thickness T10, the middle portion has an eleventh thickness T11, the fusion portion has a twelfth thickness T12, and the wing portion has a thirteenth thickness T13, and the safety vent meets the following conditions: (T10=T12)>T13>T11.

8. A rechargeable battery, include: Electrode assembly; a can housing the electrode assembly in an interior region of the can; as well as a cap assembly coupled to the can to seal the can and comprising: Safety exhaust parts; a lower cover stacked with a connecting member interposed between the safety exhaust member and the lower cover; and an upper cover, covering the safety exhaust member, The safety exhaust component comprises: a central portion joined to the lower cover; a middle portion including a step portion and a groove; a fusion portion in contact with the connection member; and an edge portion surrounding the fusion portion; and wherein At least three of the central portion, the middle portion, the fusion portion, and the edge portion have different thicknesses.

9. The rechargeable battery according to claim 8, in: The intermediate portion is disposed between the central portion and the fused portion; and The groove is provided on a first surface of the intermediate portion between the step portion and the fusion portion, the first surface facing the lower cover.

10. The rechargeable battery according to claim 8, in: The central portion has a first thickness T1, the middle portion has a second thickness T2, the fused portion has a third thickness T3, and the edge portion has a fourth thickness T4, and the safety vent meets the following conditions: T1>(T2=T3)>T4.

11. The rechargeable battery according to claim 8, in: The intermediate portion includes an inner portion and an outer portion, the inner portion includes the step portion, and the outer portion includes the groove; and The central portion has a fifth thickness T5, the inner portion has a sixth thickness T6, the outer portion has a seventh thickness T7, the fusion portion has an eighth thickness T8, and the edge portion has a ninth thickness T9, and the safety vent meets the following conditions: T5>T6>(T7=T8=T9).

12. The rechargeable battery according to claim 8, in: The central portion has a tenth thickness T10, the middle portion has an eleventh thickness T11, the fusion portion has a twelfth thickness T12, and the edge portion has a thirteenth thickness T13, and the safety vent meets the following conditions: (T10=T12)>T13>T11.

13. A method for manufacturing a rechargeable battery, the method include: housing an electrode assembly within an interior region of the can; as well as The can is sealed with a cap assembly, the cap assembly comprising a safety vent and a lower cap, the safety vent and the lower cap being stacked with a connecting member interposed therebetween, the safety vent comprising: a central portion joined to the lower cover; a middle portion including a step portion and a groove; a fusion portion in contact with the connection member; and a wing portion surrounding the fusion portion; and At least three of the central portion, the middle portion, the fusion portion and the wing portion have different thicknesses.

14. The method according to claim 13, in: The wing portion includes a first portion and a second portion overlapping the first portion and formed by bending the second portion on the first portion; and The thickness of the wing portion is solely the thickness of one of the first portion and the second portion.

15. The method according to claim 14, in: The intermediate portion is disposed between the central portion and the fused portion; and The groove is provided on a first surface of the intermediate portion between the step portion and the fusion portion, the first surface facing the lower cover.

16. The method according to claim 14, in: Sealing the can with the cap assembly includes coupling the cap assembly to the can via an insulating gasket surrounding the wing.

17. The method according to claim 14, in: The central portion has a first thickness T1, the middle portion has a second thickness T2, the fused portion has a third thickness T3, and the wing portion has a fourth thickness T4, and the safety vent satisfies the following condition: T1>(T2=T3)>T4.

18. The method according to claim 14, in: The intermediate portion includes an inner portion and an outer portion, the inner portion includes the step portion, and the outer portion includes the groove; and The central portion has a fifth thickness T5, the inner portion has a sixth thickness T6, the outer portion has a seventh thickness T7, the fusion portion has an eighth thickness T8, and the wing portion has a ninth thickness T9, and the safety vent satisfies the following conditions: T5>T6>(T7=T8=T9).

19. The method according to claim 14, wherein The central portion has a tenth thickness T10, the middle portion has an eleventh thickness T11, the fusion portion has a twelfth thickness T12, and the wing portion has a thirteenth thickness T13, and the safety vent meets the following conditions: (T10=T12)>T13>T11.

20. The method of claim 13, further comprising forming the safety vent of the cap assembly at least in part by bonding the center portion to the lower cap.

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