Secondary battery having vent

Abstract

The present invention relates to a secondary battery having a vent, the secondary battery comprising: a main body (10) having an electrode assembly embedded therein; a cap plate (20) coupled to an upper portion of the main body (10); and a vent (30) formed in the cap plate (20). The vent (30) includes: a first breakable portion (31) formed in the center and having a certain length; second breakable portions (32) formed on both sides of the first breakable portion (31); third breakable portions (33) formed orthogonally at both ends of the first breakable portion (32); and absorbing creases (34) formed between the second breakable portions (32) and a boundary portion (40), wherein the vent allows gas to be quickly discharged to the outside through the vent when the gas pressure inside the secondary battery increases, thus preventing the secondary battery from exploding.

Description

Secondary battery with vent

[0001] The present invention relates to a secondary battery having a vent, and more particularly, to a secondary battery having a vent that prevents an explosion of the secondary battery by allowing gas to be quickly discharged to the outside through the vent when the gas pressure inside the secondary battery increases.

[0002] Typically, a secondary battery is a battery that can be charged and discharged, unlike a primary battery that cannot be recharged. It is widely used in advanced electronic devices such as cell phones, laptop computers, and camcorders.

[0003] In particular, lithium secondary batteries have an operating voltage of 3.6 V, which is three times higher than nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as power sources for electronic equipment, and are rapidly expanding due to their high energy density per unit weight.

[0004] These lithium secondary batteries primarily use lithium oxide as the positive active material and carbon as the negative active material. Furthermore, lithium secondary batteries are manufactured in various shapes, with cylindrical, square, and pouch-shaped forms being the most common.

[0005] Among these, the square secondary battery comprises an electrode assembly, a can that accommodates the electrode assembly, and a cap assembly that is coupled to the can.

[0006] The electrode assembly is formed by winding a positive electrode and a negative electrode and a separator interposed between the two electrodes, and positive and negative electrode tabs are respectively drawn out from the positive electrode and the negative electrode.

[0007] A can is a metal container with a roughly rectangular shape for a square secondary battery, and is formed by a processing method such as deep drawing.

[0008] The cap assembly includes a cap plate that is coupled to the upper part of the can, an electrode terminal that is installed through a terminal hole and has a gasket positioned on the outer surface thereof for insulation from the cap plate, an insulating plate that is installed on the lower surface of the cap plate, and a terminal plate that is installed on the lower surface of the insulating plate and is electrically connected to the electrode terminal.

[0009] The negative electrode of the electrode assembly can be electrically connected to the electrode terminal through the negative electrode tab and the terminal plate, and the positive electrode can be electrically connected to the cap plate or can through the positive electrode tab.

[0010] Meanwhile, a vent may be formed on one side of the cap plate. This vent is formed thinner than the surrounding areas, so when the internal pressure of the battery increases due to overcharging or other reasons, it ruptures more quickly than other areas, releasing internal gas, thereby ensuring battery safety. These vents can be categorized into clad-type vents and press-type vents depending on their formation method.

[0011] The present invention relates to a square lithium secondary battery having an improved structure of an insulating means that mutually insulates a cap assembly and a battery unit, thereby preventing short-circuiting of electrodes and having a safety vent that can quickly discharge overheated gas.

[0012] Typically, secondary batteries, unlike primary batteries that cannot be recharged, are capable of initial charging and discharging. They are widely used in advanced electronic devices such as cell phones, laptop computers, and camcorders. In particular, lithium secondary batteries have an operating voltage of 36 V, which is three times higher than nickel-cadmium or nickel-hydrogen batteries, which are widely used as power sources for portable electronic devices. Furthermore, they are rapidly expanding due to their high energy density per unit weight.

[0013] These lithium secondary batteries primarily use lithium oxide as the positive active material and carbon as the negative active material. They are generally classified into liquid electrolyte batteries and polymer electrolyte batteries based on the type of electrolyte used. Batteries using liquid electrolytes are called lithium ion batteries, while those using polymer electrolytes are called lithium polymer batteries. Furthermore, lithium secondary batteries can be manufactured in a variety of shapes, with representative shapes including cylindrical, square, and pouch-shaped.

[0014]

[0015] However, conventional vents have the following problems:

[0016] Typically, the thickness of the cap plate is 0.8 to 1.0 mm, the thickness of the cap plate where the vent is formed is 70 μm, and the thickness of the fracture area, where fracture is expected to occur within the vent in the event of an internal abnormality in the battery, is only 20 to 30 μm.

[0017] As mentioned above, the vent originally serves to ensure the safety of the battery by being ruptured by the internal gas pressure of the battery. However, since the thickness of the ruptured portion within the vent is only several to several tens of micrometers, there is a risk that even a small external impact may cause a crack to form in the ruptured portion or cause the ruptured portion to break. In other words, if the vent is damaged, the reliability of the battery decreases.

[0018]

[0019] The present invention has been devised to solve the above problems, and the purpose of the present invention is to provide a secondary battery having a vent that forms an absorbing wrinkle between a second rupture portion and a boundary portion to absorb external impact, and when the pressure due to internal gas of the secondary battery increases due to overcharging, etc., the first, second, and third rupture portions are preferentially ruptured compared to other portions to release the internal gas, thereby ensuring the stability of the secondary battery.

[0020] The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the description below.

[0021] A secondary battery having a vent according to the present invention for solving the above problem comprises a main body having an electrode assembly built therein, a cap plate coupled to an upper portion of the main body, and a vent formed in the cap plate, wherein the vent comprises a first break portion formed at a central portion with a predetermined length; second break portions formed on both sides centered on the first break portion; third break portions formed orthogonally to both ends of the first break portion; and an absorption fold formed between the second break portion and a boundary portion.

[0022] The above first, second, and third fracture sections are formed in a straight line.

[0023] The ends of the second and third fracture portions are separated from each other by a certain distance.

[0024] The above absorption wrinkles are formed to protrude convexly outward.

[0025] The third fracture portion includes an extended fracture portion extending in the opposite direction to the first fracture portion in the central portion thereof.

[0026] It includes a sub-break portion formed between the third break portion and the extended break portion.

[0027] The above sub-break portion is formed obliquely on a line connecting the end portion of the third break portion and the end portion of the extended break portion.

[0028] The above sub-break portion is formed at a certain distance from the end portion of the third break portion and the extended break portion.

[0029] According to the present invention, an absorbing wrinkle is formed between the second fracture portion and the boundary portion to absorb external impact, and when the pressure due to internal gas of the secondary battery increases due to overcharging, etc., the first, second, and third fracture portions are preferentially fractured over other portions to release the internal gas, thereby securing the stability of the secondary battery.

[0030] FIG. 1 is a perspective view of a secondary battery having a vent according to an embodiment of the present invention.

[0031] Figure 2 is a plan view of a cap plate having a vent formed therein according to one embodiment of the present invention.

[0032] Figure 3 is a plan view of a vent according to one embodiment of the present invention.

[0033] Figure 4 is a cross-sectional view taken along line A-A' of Figure 3.

[0034] Figure 5 is a plan view of a third break section according to the present invention in which an extended break section and a sub-break section are formed.

[0035] Figure 6 is a plan view of a state in which a fourth break portion is formed in an extended break portion according to the present invention.

[0036] The following detailed description of the present invention refers to the accompanying drawings, which illustrate specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention, while different from each other, are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention. Furthermore, it should be understood that the positions or arrangements of individual components within each disclosed embodiment may be modified without departing from the spirit and scope of the present invention. Accordingly, the following detailed description is not intended to be limiting, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly described. Like reference numerals in the drawings designate the same or similar functionality throughout the several aspects.

[0037] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

[0038] First, FIG. 1 is a perspective view of a secondary battery having a vent according to an embodiment of the present invention, FIG. 2 is a plan view of a vent according to an embodiment of the present invention, and FIG. 3 is a plan view of a vent according to an embodiment of the present invention.

[0039] A secondary battery having a vent according to an embodiment of the present invention comprises a main body (10) having an electrode assembly built therein, a cap plate (20) coupled to an upper portion of the main body (10), and a vent (30) formed in the cap plate (20), wherein the vent (30) comprises: a first break portion (31) formed at a central portion with a predetermined length; second break portions (32) formed on both sides centered on the first break portion (31); third break portions (33) formed orthogonally to both ends of the first break portion (31); and an absorption fold (34) formed between the second break portion (32) and a boundary portion (40).

[0040] Here, the above boundary (40) refers to the boundary between the area where the benz (30) is formed on the cap plate (20) and the area where it is not formed.

[0041] The above body (10) is a metal container having a shape roughly similar to a rectangular parallelepiped in a square secondary battery. The material forming the body (10) may be aluminum or an aluminum alloy, which is a lightweight conductive metal.

[0042] Since the main body (10) is formed by a deep drawing processing method, the main body (10) itself can also serve as a terminal.

[0043] An electrode assembly is built into the body (10) above, and the open upper part is sealed with a cap plate (20).

[0044] The above electrode assembly is typically formed by forming the positive and negative electrodes into a wide plate shape to increase the electric capacity, then interposing a separator between the positive and negative electrodes to insulate them from each other, stacking them, and winding them into a spiral shape to form a so-called 'jelly roll'.

[0045] The negative electrode and the positive electrode can be formed by coating a negative electrode active material such as carbon and a positive electrode active material such as lithium cobalt oxide on a current collector made of copper and aluminum foil, respectively.

[0046] The above cap plate (20) seals the opened upper part of the main body (10) and can be formed of the same material as the main body (10).

[0047] The above cap plate (20) can be joined to the main body (10) by laser welding.

[0048] The upper sides of the cap plate (20) include a first terminal (21) and a second terminal (22), and the first terminal (21) and the second terminal (22) can be arranged with different polarities.

[0049] The above secondary battery may have a vent (30) formed on the cap plate (20) that is thinner than other surrounding parts.

[0050] The above vent (30) plays a role in ensuring the safety of the secondary battery by breaking prior to other parts to release the internal gas when the pressure due to the internal gas of the battery increases due to overcharging, etc.

[0051] The above vent (30) includes a first fracture portion (31), a second fracture portion (32), a third fracture portion (33), and an absorption wrinkle (34).

[0052] The above first break portion (31) can be formed to a certain length in the center of the vent (30).

[0053] The above first fracture portion (31) has a total length of 13 to 18 mm and a thickness determined in the range of 0.005 to 0.01 mm.

[0054] The above first fracture portion (31) has the thinnest thickness within the vent (30), and is therefore the portion where fracture occurs first due to the internal gas pressure of the secondary battery.

[0055] The above first breaking portion (31) may be a press-type vent structure, and the breaking pressure may be determined by the thickness of the first breaking portion (31).

[0056] The first breaking portion (31) is formed as a groove on the outer or inner surface of the vent (30).

[0057] In addition, the second fracture portion (32) is formed at a certain distance on both sides with the first fracture portion (31) as the center.

[0058] Here, the second fracture portion (32) forms a parallel line with the first fracture portion (31).

[0059] The total length of the above second breaking portion (32) can be formed to be 13 to 18 mm.

[0060] The third fracture portion (33) is formed on both ends of the first fracture portion (32) and is formed orthogonal to the first fracture portion (31).

[0061] The above third broken portion (33) has a total length of 7 to 9 mm, and the end of the third broken portion (33) is not connected to the second broken portion (32) and forms a gap of 0.5 to 1.5 mm.

[0062] The internal pressure of the secondary battery varies depending on the gap between the second rupture portion (32) and the third rupture portion (33), and the larger the gap, the greater the degree to which the internal pressure can be withstood.

[0063] Here, when the thicknesses of the first fracture portion, the second fracture portion (32), and the third fracture portion (33) are the same, the fracture pressure value can be adjusted by changing the gap difference.

[0064] Additionally, the above absorption wrinkles (34) can be formed to protrude convexly toward the outside of the vent (30).

[0065] The above absorbent wrinkles (34) serve to absorb external impact applied to the vent (30) and prevent damage to the vent (30).

[0066] That is, this absorption wrinkle (34) prevents damage to the vent (30) due to causes other than the internal gas pressure of the secondary battery.

[0067] The above absorption wrinkle (34) is formed between the second fracture portion (32) and the boundary portion (40).

[0068] Looking at the order in which external impact is applied to the vent (30), the impact is applied from the outside to the inside of the vent (30) and at the same time, the impact is applied to the second fracture portion (32) and the first fracture portion (31) through the absorption wrinkle (34).

[0069] That is, by forming the above-mentioned absorption wrinkles (34), the external impact is not directly applied to the second fracture portion (32) and the first fracture portion (31) but passes through a buffer zone called the absorption wrinkles (34), so that the fracture portion can be prevented from being fractured by the external impact.

[0070] In addition, as shown in FIG. 5, the third fracture portion (33) may further include an extension fracture portion (35) extending in the opposite direction of the first fracture portion (31) in the central portion.

[0071] The above-mentioned extended fracture portion (35) can be formed to extend 2 to 6 mm further outward from the second fracture portion (33), and the total length of the first fracture portion (31) and the extended fracture portion (35) combined can be formed to be 20 to 28 mm.

[0072] The extended fracture portion (35) extends between the third fracture portion (33) and the absorbent fold (34) and serves to cushion external impact.

[0073] Here, the first, second, and third fracture portions (31)(32)(33) and the extended fracture portion (35) are formed on the inside of the absorption wrinkle (34), and by forming the first, second, and third fracture portions (31)(32)(33) and the extended fracture portion (35), an embossing portion (36) can be formed between them.

[0074] Additionally, a sub-break portion (37) may be further included between the third break portion (33) and the extended break portion (35).

[0075] The above sub-break portion (37) is formed to be individually separated from the ends of the third break portion (33) and the extended break portion (35) by a certain distance.

[0076] That is, the sub-break portion (37) can be formed slantedly on a line connecting the end portion of the third break portion (33) and the end portion of the extended break portion (35).

[0077] In addition, as shown in FIG. 6, the end of the extended broken portion (35) may further include a fourth broken portion (38) extending in a direction perpendicular to the extended broken portion (35).

[0078] The fourth fracture portion (38) has the same overall length of 7 to 9 mm as the third fracture portion (33) and is formed between the third fracture portion (33) and the absorption wrinkle (34).

[0079] Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and various modifications may be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims. Furthermore, such modifications should not be understood individually from the technical idea or prospect of the present invention.

[0080] 10: Body

[0081] 20: Cap plate

[0082] 30: Vent

[0083] 31: First fracture

[0084] 32: Second fracture

[0085] 33: Third Break

[0086] 34: Absorption wrinkles

[0087] 35: Extension break

[0088] 36: Embossing section

[0089] 37: Sub-break

[0090] 38: The 4th Break

Claims

1. In a secondary battery including a main body (10) having an electrode assembly built into the inside, a cap plate (20) coupled to the upper portion of the main body (10), and a vent (30) formed in the cap plate (20), The above vent (30) is, A first break portion (31) formed in a certain length in the central portion; Second fracture portions (32) formed on both sides centered on the first fracture portion (31); A third breaking portion (33) formed orthogonally to both ends of the first breaking portion (32); A secondary battery having a vent including an absorption wrinkle (34) formed between the second fracture portion (32) and the boundary portion (40).

2. In claim 1, The above first, second, and third break sections (31), (32), and (33) are secondary batteries having vents formed in a straight line.

3. In claim 1, A secondary battery having vents in which the ends of the second rupture portion (32) and the third rupture portion (33) are separated from each other by a certain distance.

4. In claim 1, The above absorption wrinkle (34) is a secondary battery having a vent that protrudes convexly outward.

5. In claim 1, A secondary battery having a vent including an extended fracture portion (35) extending in the opposite direction of the first fracture portion (31) in the central portion of the third fracture portion (33).

6. In claim 5, A secondary battery having a vent including a sub-break portion (37) formed between the third break portion (33) and the extended break portion (35).

7. In claim 6, A secondary battery having a vent formed obliquely on a line connecting the end of the third break portion (33) and the end of the extended break portion (35), wherein the above sub-break portion (37) is formed.

8. In claim 6, A secondary battery having a vent formed at a certain distance from the ends of the third fracture portion (33) and the extended fracture portion (35), wherein the above-mentioned sub-fracture portion (37) is a secondary battery.

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