WO2023022340A1

WO2023022340A1 - Cap plate for secondary battery having vent structure, and method for manufacturing cap plate

Info

Publication number: WO2023022340A1
Application number: PCT/KR2022/007981
Authority: WO
Inventors: 김종찬
Original assignee: 주식회사 파인디앤씨
Priority date: 2021-08-18
Filing date: 2022-06-07
Publication date: 2023-02-23
Also published as: KR102406193B1; KR20230026899A

Abstract

The present invention relates to a cap plate for a secondary battery having a vent structure that is being manufactured through simplified manufacturing processes by integrally forming a vent portion with the cap plate in a cap plate manufacturing process, a mold for manufacturing the cap plate, and a method for manufacturing the cap plate by using the mold. The cap plate of the present invention is for sealing a case accommodating an electrode assembly and comprises: a main body covering the electrode assembly; and a vent portion formed in the main body, wherein the vent portion and the main body are formed of an identical material through a single press process, the thickness of the vent portion corresponds to the main body, and the vent portion includes an interrupted support portion to be out of line with the plane direction of the main body and a weak structure portion which is formed through shear deformation at the boundary between the interrupted support portion and the main body.

Description

Cap plate for secondary battery having a vented structure and manufacturing method of the cap plate

The present invention relates to a cap plate for a secondary battery having a vented structure, a mold for manufacturing the cap plate, and a method for manufacturing the cap plate using the mold (CAP PLATE FOR SECONDARY BATTERIES HAVING VENT STRUCTURE, AND MANUFACTURING MATHOD OF THE CAP PLATE). More specifically, the present invention relates to a cap plate for a secondary battery having a vent structure in which the manufacturing process is simplified by integrally molding the vent part in the manufacturing process of the cap plate, a mold for manufacturing the cap plate, and a method of manufacturing the cap plate using the mold.

In general, a lithium ion secondary battery includes an electrode plate assembly wound or stacked in a jelly roll form, a substantially hexahedron-shaped can into which the electrode plate assembly is inserted and fixed, and lithium ions filled in the can to allow movement of lithium ions. It consists of an electrolyte solution to do so, and a cap plate that blocks the can on top of the electrode plate assembly and the electrolyte solution.

In such a lithium ion secondary battery, after stacking a positive electrode plate attached with a positive electrode active material, a negative electrode plate attached with a negative electrode active material, and a separator, they are wound or laminated in a jelly roll form, put back into a can, and sealed by welding a cap plate on the top. do. Thereafter, after injecting the electrolyte solution, charging and inspection are performed to complete a bare cell type lithium ion secondary battery. Of course, a normal battery pack is completed by assembling and inspecting after attaching various safety devices and protection circuit boards to the bare cell type lithium ion secondary battery.

Meanwhile, since such a lithium ion secondary battery uses a constant voltage/constant current charging method, there is no overcharging phenomenon when the charging voltage is accurately controlled by the charger. However, there are cases in which the charger is damaged or malfunctions, resulting in abnormal charging. In this case, the battery voltage continues to rise due to the characteristic of the positive electrode active material, for example, lithium baltate (LiCoO2), whose potential continuously rises, and also causes abnormal charging. fever occurs.

Safety measures against this phenomenon include the incorporation of a positive temperature coefficient thermistor, the adoption of a separator with a shutdown function, and a protective circuit board that controls the charging and discharging voltage. There is a safety vent operated by

Here, the vent portion usually refers to a thinner area formed on the cap plate, which ruptures or breaks when the internal pressure of the battery rises due to gas generation and releases gas inside the can to the outside, thereby causing extreme extremes such as explosion of the lithium ion secondary battery. It plays a role in preventing incidents.

The gas is generated as the electrolyte or active material is decomposed when the charging voltage of the lithium ion secondary battery rises above the reference voltage. This gas usually causes the can to swell by increasing the internal pressure of the battery, and the vent part ruptures, ruptures, or ruptures due to the increase in the internal pressure of the battery, thereby preventing extreme explosion or fire of the lithium ion secondary battery. .

As such, the vent unit is designed to operate automatically when the internal pressure of the battery exceeds a predetermined pressure. However, since the conventional vent portion is processed to make a predetermined area of the cap plate relatively thin, there is a problem in that the operating speed of each battery is slightly different.

A vent structure of a battery according to the prior art forms a hole in a cap plate for a vent function, and adopts a method of bonding components having a separately formed vent structure through welding (laser) or thermal fusion.

However, this method has a problem of increasing manufacturing cost due to an increase in the number of parts and manufacturing processes, and a problem in that material management and process time increase because secondary processes necessary for welding and thermal fusion must be performed.

In accordance with this problem, recently, patents for constructing a vent part in a coining method in which a vent having a thickness smaller than that of other parts around the cap plate are formed have been disclosed (see Korean Patent Publication No. 2007-0071232).

However, this prior art has a problem in that the compression rate of the cap plate material is excessive in order to form the vent structure. In the prior art, when the bent structure is integrally formed, the difference between the molding thickness of the bent structure and the thickness of the cap plate is large, resulting in buckling, concentration of stress, and wrinkles caused by rapid changes in the material of the cap plate around the bent structure. There is a problem in that a defect in the cap plate itself occurs due to the occurrence of the cap plate itself. Therefore, these conventional technologies are evaluated as impossible technologies to be applied in practice.

The present invention has been made to solve the above problems, and its object is to simplify the manufacturing process of forming a vent structure without deformation of the periphery while integrally molding the vent part together in the manufacturing process of the cap plate. It is to provide a cap plate for a secondary battery having a cap plate, a mold for manufacturing the cap plate, and a manufacturing method of the cap plate using the mold.

According to the present invention, a cap plate for sealing a case accommodating an electrode assembly, comprising: a body portion covering the electrode assembly; and a vent part formed in the main body part. The bent part and the main body part are formed together by a single press process, and the bent part has a thickness corresponding to that of the main body part, and a break support part and the break support part and the main body part are displaced from the planar direction of the main body part. A cap plate for a secondary battery comprising a structurally weak portion formed by shear deformation at a boundary between the cells is provided.

Preferably, the compression rate of the fracture support portion is characterized in that it has a compression rate corresponding to the compression rate of the body portion.

Preferably, the fracture support portion is characterized in that it protrudes in one direction of the vertical direction of the horizontal surface of the body portion.

Preferably, the structurally weak portion is formed with a relatively thin thickness in a portion where the strain is increased due to shear deformation.

Preferably, the structurally weak portion is characterized in that the ductility is smaller than that of the fracture support portion and the main body portion.

Preferably, the weak structural part is molded in a shape surrounding the main body so that its cross-sectional shape is symmetrical.

Preferably, the breakage support part of the bent part has a flat plate shape, and the breakage support part is coupled with the flat plate-shaped body part with a height difference to form a weak structural part surrounding the breakage support part.

Preferably, 10 to 20% of the total vertical length of the coupling side surface surrounding the fracture support portion is connected to the coupling side surface of the body portion, so that the structural soft part is formed so that the fracture support portion and the body portion share 10 to 20% of the coupling side surface. to be characterized

Preferably, 21 to 70% of the total vertical length of the coupling side surface surrounding the fracture support portion is connected to the coupling side surface of the body portion, so that the structural weakness is formed so that the fracture support portion and the body portion share 21 to 70% of the coupling side surface. to be characterized

Preferably, the breakage support part of the bent part has a flat plate shape, the breakage support part has a height difference with the body part of the flat plate shape, and the coupling side surface surrounding the breakage support unit shares the coupling side surface of the body portion and the coupling side surface. It is characterized in that the structurally weak part is formed in a band shape without

Preferably, the fracture support portion is formed including a base portion formed at the same height as the main body portion and a bent portion formed to protrude upward from the base portion in an L-shape, and the bent portion is formed from the base portion Consisting of a first extension portion extending vertically and a second extension portion extending horizontally from the first extension portion, the horizontally formed base portion has the same vertical height as the main body portion, and the upper portion is formed by the first extension portion. The second extension part protruding to is characterized in that it protrudes upward compared to the main body part.

Preferably, the fracture support portion has a shape in which the first and second bends are connected to both ends of the line-shaped straight portion, and the first and second bends are located at the center at both ends of the straight portion It is formed in a 'V' shape extending from the end of the straight part, and the straight part formed horizontally, the first bent part and the second bent part are characterized in that they protrude upward compared to the main body part.

Meanwhile, according to another aspect of the present invention, as a mold for manufacturing the cap plate according to one of the above features, the upper mold and the lower mold are pressed with a metal base material interposed therebetween, so that the body part and the vent part of the cap plate are together. It can be molded, and one side of the upper mold or the lower mold is provided with a protrusion in the direction in which the pressure of the press is applied or in the opposite direction, and a concave portion corresponding to the protrusion is provided on the other side, and the side of the protrusion and the concave portion are provided. A mold for manufacturing a cap plate characterized in that an empty gap portion is formed between the side surfaces to generate a shear force during pressing to form a structurally weak portion.

Preferably, the upper mold and the lower mold, in a pressed state, the distance between the upper mold and the lower mold at the part where the fracture support is formed is a distance corresponding to the distance between the upper mold and the lower mold forming the main body. It is characterized by having

Meanwhile, according to another aspect of the present invention, a method of manufacturing a cap play according to the above-described characteristics includes interposing a raw metal plate between an upper mold and a lower mold; and forming a raw material metal plate into a cap plate comprising a main body part and a vent part by performing press working by applying a predetermined pressure to the base metal material using an upper mold and a lower mold. Including, one side of the upper mold or lower mold is provided with a protrusion in the direction in which the pressure of the press is applied or in the opposite direction, and a concave portion corresponding to the protrusion is provided on the other side, and the side of the protrusion and the side of the concave portion A method for manufacturing a cap plate is provided, wherein an empty gap is formed between the cap plates and a shear force is generated during pressing to form the structurally weak parts.

According to the present invention, it is possible to simplify the manufacturing process by integrally molding the vent part in the manufacturing process of the cap plate, thereby reducing manufacturing cost.

In addition, by forming the vent portion with a thickness corresponding to that of the cap plate, but having a structurally weak portion that is sheared at the boundary, it has a structure and property suitable for rupture or rupture both physically and materially, so that when the internal pressure of the secondary battery rises, it is faster and more accurate. It is possible to form an efficient vent structure that can be effectively ruptured or broken.

In addition, according to the present invention, an effect of increasing productivity by excluding the addition of a separate component other than the cap plate can be expected while resolving the problem of deformation of the peripheral portion caused by excessive compressibility of the material.

1 is a perspective view of a secondary battery according to an embodiment of the present invention.

2 is a perspective view of a cap plate according to an embodiment of the present invention.

3 is a conceptual diagram of a method of manufacturing a cap plate according to an embodiment of the present invention.

4 is a stress-strain curve of aluminum as a metal base material according to an embodiment of the present invention.

5 to 9 are views for explaining first to fifth embodiments of the vent unit in the cap plate according to the present invention.

100: secondary battery 110: case

120: first electrode terminal 130: second electrode terminal

140: cap plate 141: body part

142: vent part 142a: fracture support part

142b: structural soft part

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1 , a secondary battery 100 includes a case 110 accommodating an electrode assembly (not shown) therein, and a cap plate 140 closing the case 110 accommodating the electrode assembly. do. For example, the cap plate 140 may be coupled to the case 110, and a welding portion may be formed along an edge of the cap plate 140 and the case 110 that come into contact with each other. Such a weld may be formed by laser welding between the cap plate 100 and the case 180 .

At this time, the electrode assembly is formed by winding a separator, which is an insulator, between the positive electrode and the negative electrode. In the present invention, the secondary battery 100 has been illustrated and described as an example of a prismatic lithium ion secondary battery, but it can be applied to various types of batteries such as lithium polymer batteries or cylindrical batteries, and the configuration of the electrode assembly is in this field Various known technologies may be selectively applied.

In such a secondary battery 100, the case 110 forms the overall appearance of the secondary battery 100, and may be formed of a metal material such as aluminum, aluminum alloy, or nickel-plated steel.

The cap plate 140 has a large area over the electrode assembly. The cap plate 140 may be made of a thin metal plate such as aluminum or aluminum alloy.

A pair of

electrode terminals

120 and 130 having opposite polarities, for example, first and

second electrode terminals

120 and 130 may be formed on the cap plate 140 to protrude outward. More specifically, first and

second electrode terminals

120 and 130 may be formed to pass through the cap plate 140 . The first and

second electrode terminals

120 and 130 are installed through the cap plate 140, and a gasket is provided between the first and

second electrode terminals

120 and 130 and the cap plate 140 for insulation and sealing. is installed For example, the first and

second electrode terminals

120 and 130 are electrically connected to an electrode assembly accommodated inside a secondary battery, and each of the first and

second electrode terminals

120 and 130 is an electrode assembly It is electrically connected to the first and second electrode plates to supply discharge power accumulated in the secondary battery to the outside or function as positive and negative terminals to receive charging power from the outside. For example, the first and

second electrode terminals

120 and 130 may be formed on both sides of the secondary battery.

In another embodiment of the present invention, the cap plate 140 of the secondary battery may be electrically connected to the electrode assembly to function as a terminal. At this time, any one of the first and

second electrode terminals

120 and 130 may be One

electrode terminal

120 or 130 may be omitted.

The cap plate 140 is coupled to an upper end of the case 110 in which the electrode assembly is accommodated, and may seal an opening of the case 110 . For example, the cap plate 140 and the case 110 may be welded together along an edge of the cap plate 140 .

The cap plate 140 has a relatively fragile structure, and a vent portion 142 designed to be ruptured or broken is formed to provide a gas discharge path when the pressure inside the secondary battery exceeds a set point. In addition, an electrolyte injection hole for injecting electrolyte into the case 110 may be formed in the cap plate 140, and the electrolyte injection hole may be closed by a sealing stopper 160 after the electrolyte injection is completed.

Although the planar shape of the vent part 142 is approximately elliptical in the drawing, the present invention is not limited to the planar shape of the vent part 142. That is, the planar shape of the vent part 142 can be of various shapes such as a circle, an ellipse, a rectangle, and a pentagon.

The cap plate 140 of the present invention may be formed by applying press working to a plate-shaped metal base material. The metal base material is preferably aluminum or aluminum alloy, and in addition, any material having a certain strength and malleability can be applied. In the present invention, the plate-shaped metal base material may be formed into the cap plate 140 through press working in which the plate-shaped metal base material is interposed between the upper mold and the lower mold and a predetermined pressure is applied.

At this time, the present invention presses the upper mold and the lower mold once against the plate-shaped metal base material to integrally mold the vent portion 142 together in the manufacturing process of the cap plate 140 without deformation of the peripheral portion and effectively when the internal pressure rises. It is possible to manufacture the cap plate 140 having a vent structure that can be ruptured or broken.

The cap plate 140 may include a body portion 141 covering the electrode assembly and a vent portion 142 formed in the body portion 141 .

The main body portion 141 is formed by pressing a plate-shaped base metal material with an upper mold and a lower mold once to have a certain thickness.

An electrode through-hole through which an electrode terminal can penetrate may be formed in the main body 141, an electrolyte injection hole for injecting an electrolyte into the case 110 may be formed, and an internal gas discharge path may be provided. A vent portion 142 designed to be ruptured or breakable may be formed.

Accordingly, the body portion 141 and the vent portion 142 of the cap plate 140 are formed at once by pressing the plate-shaped metal base material with the upper mold and the lower mold once. Of course, in this process, the electrode through hole and the electrolyte injection hole will also be formed together.

In FIG. 2 , the bent portion 142 has a substantially elliptical planar shape, but the present invention is not limited to the shape of the bent portion 142 . That is, the planar shape of the vent part 142 can be of various shapes such as a circle, an ellipse, a rectangle, and a pentagon.

3 is a conceptual diagram of a method of manufacturing a cap plate according to an embodiment of the present invention. 4 is a stress strain curve of aluminum as a metal base material according to an embodiment of the present invention.

The present invention simplifies the manufacturing process by integrally molding the bent portion 142 together in the manufacturing process of the cap plate 140 by pressing the upper mold and the lower mold once with respect to the plate-shaped metal base material, while shear strain is concentrated and the shear strain is reduced. By forming the structurally weak portion 142b in this large area, the cap plate 140 having a bent structure that can be ruptured or broken more quickly and accurately without deformation of the periphery can be manufactured.

3 (a) is a conceptual diagram illustrating an upper mold, (b) a lower mold, and (c) a cap plate having a vent portion.

According to the present invention, the metal base material may be formed into the cap plate 140 having the bent part 142 formed thereon through press working in which a metal base material is interposed between the upper mold (a) and the lower mold (b) and a predetermined pressure is applied thereto. there is.

In addition, the upper mold and the lower mold used for one-time press processing of the cap plate 140 have forming parts capable of forming not only the body part 141 of the cap plate 140 formed in a plate shape, but also the bent part 142 . In the cap plate 140 of the present invention, the body portion 141 and the vent portion 142 are molded together by a pressing process.

In the present invention, the body portion 141 of the cap plate 140 and the fracture support portion 142a are formed by compression molding, and the structurally weak portion 142b is formed by using an upper mold (a) and a lower mold (b) in a press process. It is formed in the area where shear strain is concentrated by the shear force generated at the boundary of Aluminum, aluminum alloy, or other metal materials may be used as the material for the cap plate of the present invention. The metal material has excellent malleability, so that a relatively thin structural weak part can be formed in a region where shear strain is concentrated and strain is increased.

In FIG. 3, A indicates a site where shear force occurs, and B indicates a site where shear strain is concentrated and the strain increases. Referring to FIGS. 3 and 4, when press working in the present invention, the shear stress is increased in the shear strain concentration region (B), and when entering the plastic region, the strain is relatively increased to form a thin structural weak part. You can do it. In the region (B) where shear strain is concentrated, the strain is increased compared to the main body part 141 and the fracture support part 142a due to this shear strain, so that it is molded to a relatively thin thickness, and the crystal structure changes due to shear strain ( slip, twinning, dislocation, etc.) occur and the ductility is relatively reduced. These changes in material properties occur relatively well in the shear deformation area due to shear stress compared to the compression deformation area due to normal stress, and the greater the strain, the better it occurs.

The vent portion of the cap plate should be ruptured or broken when the internal pressure of the battery increases, thereby reducing the internal pressure of the battery and preventing the battery from exploding. However, as in the present invention, in forming such a vent structure with one material and one processing, the area to be physically ruptured or fractured is processed to a relatively thin thickness, so that the stress against internal pressure is reduced compared to other areas. In addition to increasing this size, a more effective vent structure can be formed if the material properties of the corresponding portion are structurally suitable for rupture or fracture. In the present invention, by forming a relatively thin structural weakness in an area where shear strain is concentrated and strain increases, it has a property that is relatively close to brittle fracture compared to other areas, resulting in faster, more accurate and effective rupture in the structural weakness. Alternatively, it can have a vent structure that can be broken. According to the present invention, by forming a structurally weak portion having relatively reduced ductility compared to other portions having relatively high ductility, a more efficient vent structure can be formed in terms of material properties.

On the other hand, in order to effectively form the structurally weak portion 142b in the region where shear strain is concentrated in FIG. It is preferable that the compressive stress at 142a is the same, and it is not preferable that there is a large difference. The compressive stress in the body portion 141 and the fracture support portion 142a will be proportional to their compressibility, so it is preferable that the compression rates of the body portion 141 and the fracture support portion 142a are the same, and a large difference is Not desirable. That is, the compression rate of the fracture support portion 142a must have a compression rate corresponding to that of the body portion 141. .) In the present invention, when the compressive stress received by the main body portion 141 and the fracture support portion 142a are different, the difference in compressive stress interferes with the shear stress acting on the structurally weak portion 142b connected thereto, resulting in effective shear deformation. this won't happen

As a result of application to the actual manufacturing process, it was confirmed that when the difference in compressibility between the body portion 141 and the fracture support portion 142a exceeds 30%, the structurally weak portion 142b is deformed and not formed effectively. Therefore, in the present invention, having a compression rate corresponding to that of the body portion 141 in the compression rate of the fracture support portion 142b means that the difference is 30% or less.

As described above, in order to form the structurally weak portion 142b of the cap plate 140 of the present invention in a region where shear deformation is concentrated by pressing, the mold for manufacturing the cap plate of the present invention has the following structure. should have

Referring to FIG. 3, one side of the upper mold (a) or the lower mold (b) is provided with a protrusion in the direction in which the pressure of the press is applied or in the opposite direction (see FIG. 3 (a)), and the other side has the A concave portion corresponding to the protrusion is provided (see (b) of FIG. 3). During the pressing process, a shear force is generated at one side or both sides of the boundary between the protrusion and the concave portion (part A in FIG. 3), and the shear force concentrates the shear strain by the shear force, resulting in a relatively thin structural weakness in the area (B) where the strain increases. The fracture support portion 142a and the body portion 141 are formed at the portion where the portion 142b is formed and compressed.

In addition, an empty gap portion is formed between the side surface of the protruding portion and the side surface of the concave portion forming the structurally weak portion 142b, to which the vertical pressure of the press is not directly applied, so that the structurally weak portion 142b can be molded. The spacing of the gap portion corresponds to the thickness of the structurally weak portion 142b that may rupture or break when the internal pressure of the battery increases. Therefore, the interval between the gaps is determined according to the rupture characteristics of the secondary battery when the internal pressure is generated, the nature of the parent material, and the like, and is 0.1 mm (based on 20 bar) in one embodiment of the present invention. In this case, aluminum having a thickness of 0.3 mm to 0.6 mm is used as the metal base material.

In addition, in the mold for manufacturing the cap plate of the present invention, the gap between the upper mold and the lower mold at the portion where the breakage supporting portion 142a is formed in a pressed state through the metal base material is the upper part forming the body portion 141. It should have a gap corresponding to the gap between the mold and the lower mold. This is because, as described above, in order to effectively form the weak structural portion 142b due to shear deformation, the compression rate of the fracture support portion 142a must have a compression rate corresponding to that of the body portion 141.

Since the vertical pressure of the press is not directly applied to the gap portion by the protrusions and concave portions of the upper or lower mold, shear force will be generated (see (c) of FIG. 3). In addition, in the pressed state, the compression rate of the fracture support portion 142a has a compression rate corresponding to that of the main body portion 141, so that shear force is efficiently generated through the gap portion. By applying the structural shear force of the mold, the structurally weak portion 142b is formed relatively thin in the portion where the shear deformation is concentrated and the strain increases compared to the fracture support portion 142a or the body portion 141, and as described above, In addition to the increased stress for internal pressure compared to other parts, the material properties of the corresponding part have structurally suitable properties for rupture or fracture due to the increase in strain due to shear deformation. It is possible to form an efficient vent structure that can be broken.

In addition, since a separate process for forming the vent portion is not added in the manufacturing process of the cap plate, the manufacturing process can be reduced through component unification, thereby reducing manufacturing cost.

In addition, it will be possible to create safety vents with various specifications by adjusting the gap for the empty gap of the mold.

Now, with reference to FIGS. 5 to 9 , first to fifth embodiments of the vent unit according to the present invention will be described in detail.

5 to 9, (a) is a perspective view showing the cap plate on which the vent part and the main body part are formed, (b) is a cross-sectional view showing the fracture support part of the vent part and structurally weak parts, and (c) is a structural weakness due to an increase in battery internal pressure. It is a cross-sectional view for explaining the state in which the part is broken.

The fracture support portion 142a of the vent portion 142 includes the fracture support portion 142a having the same thickness as the main body portion 141 and displaced from the planar direction of the body portion 141, the fracture support portion 142a and the main body portion. It includes a structurally weak portion 142b formed by shear deformation at the boundary between (141).

The fracture support portion 142a has a thickness corresponding to that of the body portion 141 of the cap plate 140 as a whole. That is, the thickness of the fracture support portion 142a may be determined to be the same as or to a degree that does not significantly differ from the thickness of the main body portion 141 .

As a result of application to the actual manufacturing process as described above, it was confirmed that when the difference in compressibility between the body part 141 and the fracture support part 142a exceeds 30%, the structurally weak part 142b is deformed and is not formed effectively. It became. Since the compressibility is proportional to the thickness when using a metal base material of the same thickness, in the present invention, the thickness of the fracture support portion 142b having a thickness corresponding to the thickness of the main body portion 141 means that the difference is 30% or less. it means.

The fracture supporting portion 142a is molded together in a single pressing process by an upper mold and a lower mold that mold the entire cap plate 140 . Accordingly, the compression rate of the fracture support portion 142a has a compression rate corresponding to that of the body portion 141 . That is, it is preferable that the compressibility of the fracture support portion 142a is the same as that of the main body portion 141 or the difference is determined to be 30% or less.

Since the fracture supporting portion 142a is also molded together in one pressing process by the upper and lower molds that mold the entire cap plate 140, its thickness is thicker or longer than other parts (the entire cap plate). Thin control is not easy. When the thickness of the actual breakage support 142a is increased, the compressibility is low and the mechanical robustness is deteriorated, which may lead to breakage of the breakage support 142a itself, which is an area where breakage is not expected. Conversely, when the thickness of the fracture support 142a is thinned, if the compressibility of the fracture support 142a is excessive in the pressing process, buckling occurs due to rapid material change in the fracture support 142a or its surroundings, and concentration of stress occurs. Defects may occur in the fracture support 142a itself due to the occurrence of wrinkles or the like. In addition, if the compressibility of the fracture supporting portion 142a is excessive, shear deformation of the structurally weak portion 142b is hindered, and thus the structurally weak portion 142b having a desired thickness and shape may not be formed.

In the present invention, the thickness of the fracture support portion 142a is formed to a thickness corresponding to that of the body portion 141 of the cap plate 140, thereby inducing desirable shear deformation of the weak structural portion 142b, thereby having effective fracture characteristics. A weak portion 142b may be formed, and unexpected breakage of the fracture support portion 142a may be prevented, and structural defects of the fracture support portion 142a that may occur in a pressing process may be prevented.

In addition, the breakage support portion 142a has a feature of being displaced from the planar direction of the main body portion 141 . In the body part 141 formed to have a flat horizontal surface as a whole, the breakage support part 142a protrudes in one of the vertical directions of the horizontal plane, so that when the structural weakness part 142b is broken, the broken part is easily lifted and broken. The fracture support 142a can be easily rotated by internal pressure around the structurally weak portion 142b of the unsupported portion. In this way, the fractured portion is easily lifted, and the rotation of the fracture support portion 142a centered on the structurally weak portion 142b of the non-fractured portion prevents the internal gas discharge path from being blocked after the structurally weak portion 142b is fractured. will make sure not

Various forms of the fracture support 142a will be described in detail with reference to the drawings in FIGS. 3 to 7 below.

In addition, the structurally weak part 142b surrounds the breakable support part 142a as a whole and is formed at the boundary between the breakage support part 142a and the body part 141, and the breakage support part 142a can induce breakage by an external force. ) and the body portion 141, it is sheared and formed in a region where the strain increases, so that it has efficient breaking characteristics not only physically but also materially.

One of these structurally weak parts 142b may be broken in a point or line shape.

The structurally weak portion 142b is molded together with the fracture support portion 142a in a single pressing process by an upper mold and a lower mold that mold the entire cap plate 140 .

In addition, the weak structural portion 142b is formed in a shape surrounding the body portion 141 so that its cross-sectional shape is symmetrical. Therefore, when the internal pressure of the secondary battery rises, it is possible to prevent rapid rupture or breakage only in a specific direction.

In the present invention, since the weak structural portion 142b is formed with a relatively thin thickness at a portion where the strain is increased due to shear deformation, stress concentration can be physically induced when the internal pressure of the secondary battery is increased, as well as material properties of the corresponding portion. This structurally has a property suitable for rupture or fracture, so that efficient rupture or fracture can be induced.

In addition, the cross-sectional shape of the structurally weak portion 142b is symmetrical so that the fractured portion can be easily lifted, and the fracture support portion 142a is resistant to internal pressure around the structurally weak portion 142b of the non-broken portion. makes it easy to rotate. In this way, the fractured portion is easily lifted, and the rotation of the fracture support portion 142a centered on the structurally weak portion 142b of the non-fractured portion prevents the internal gas discharge path from being blocked after the structurally weak portion 142b is fractured. will make sure not

5 is a diagram for explaining the first embodiment of the present invention.

As shown in (a) of FIG. 5 , the vent portion 142 is formed together with the body portion 141 of the cap plate 140 through a single pressing process.

Referring to (b) of FIG. 5 , in the first embodiment, the fracture support portion 142a of the bent portion 142 is generally formed in an elliptical shape and has a flat plate shape. In addition, as the fracture support portion 142a is coupled with the flat plate-shaped main body portion 141 with a height difference, the shear deformation at the boundary surrounding the fracture support portion 142a causes structural weakness with a relatively thin thickness in the region where the strain is increased. A portion 142b is formed together.

10 to 20% of the total vertical length of the coupling side surface surrounding the fracture support portion 142a is connected to the coupling side surface of the body portion 141, thereby forming the structurally weak portion 142b. That is, the fracture support 142a and the main body 141 share 10 to 20% of the coupling side.

The structurally weak portion 142b is broken when the internal pressure of the battery rises due to gas generation, and becomes a portion for discharging internal gas to the outside. The lower this is, the rupture will occur even at a lower internal pressure, and the higher the ratio of the joint surfaces that are shared, the higher the internal pressure will be endured.

Here, the fracture support portion 142a has a plate shape and has a thickness corresponding to that of the body portion 141 of the cap plate 140 to effectively form the shear-deformed structurally weak portion 142b, and the fracture support portion ( In 142a), unexpected breakage can be prevented.

In addition, it will be possible to create safety vents of various specifications through simple and intuitive ratio adjustment of the coupling surface shared by the fracture support portion 142a constituting the structurally weak portion 142b and the main body portion 141.

6 is a diagram for explaining a second embodiment of the present invention.

As shown in (a) of FIG. 6 , the vent portion 142 is formed together with the body portion 141 of the cap plate 140 by a single pressing process.

Referring to (b) of FIG. 6 , in the second embodiment, the fracture support portion 142a of the bent portion 142 is generally formed in an elliptical shape and has a flat plate shape. In addition, as the fracture support portion 142a is coupled with the flat plate-shaped main body portion 141 with a height difference, the shear deformation at the boundary surrounding the fracture support portion 142a causes structural weakness with a relatively thin thickness in the region where the strain is increased. A portion 142b is formed together.

21 to 70% of the total vertical length of the coupling side surface surrounding the fracture support portion 142a is connected to the coupling side surface of the body portion 141, thereby forming the structurally weak portion 142b. That is, the fracture support portion 142a and the main body portion 141 share 21 to 70% of the coupling side.

In particular, compared to the structurally weak portion 142b of the first embodiment, in the structurally weak portion 142b of the second embodiment, since the ratio of the coupling side shared by the fracture support portion 142a and the body portion 141 is high, the corresponding structurally weak portion ( 142b) will withstand high internal pressure. In addition, compared to the first embodiment, the fracture support 142a of the second embodiment has a small amount of protrusion in the vertical direction, enabling a compact configuration and improving assemblyability.

7 is a diagram for explaining a third embodiment of the present invention.

As shown in (a) of FIG. 7 , the vent portion 142 is formed together with the body portion 141 of the cap plate 140 through a single pressing process.

Referring to (b) of FIG. 7 , in the third embodiment, the fracture support portion 142a of the bent portion 142 is generally formed in an elliptical shape and has a flat plate shape. In addition, as the fracture support portion 142a is coupled with the flat plate-shaped main body portion 141 with a height difference, the shear deformation at the boundary surrounding the fracture support portion 142a causes structural weakness with a relatively thin thickness in the region where the strain is increased. A portion 142b is formed together.

The coupling side surface surrounding the fracture support portion 142a does not share the coupling side surface with the coupling side surface of the body portion 141, and the weak structural portion 142b is formed in a thin belt shape by a pressing process.

Such a structurally weak portion 142b is broken when the internal pressure of the battery rises due to gas generation, and becomes a portion for discharging internal gas to the outside.

In particular, compared to the structurally weak portions 142b of the first and second embodiments, since the structurally weak portion 142b of the third embodiment is molded into a thin strip shape, it will be easily broken even at a low internal pressure.

8 is a diagram for explaining a fourth embodiment of the present invention.

As shown in (a) of FIG. 8 , the vent portion 142 is formed together with the body portion 141 of the cap plate 140 by a single pressing process.

Referring to (b) of FIG. 8 , in the fourth embodiment, the fracture support portion 142a of the bent portion 142 is formed in an oval shape as a whole, has a flat plate shape, and has a thickness corresponding to that of the body portion 141. It is formed, and is formed including a base portion 142a1 formed at the same height as the body portion 141 and a bent portion 142a2 formed to protrude upward from the base portion 142a1 in an L-shape. . Here, the bent part 142a2 is composed of a first extension part 142a3 extending vertically from the base part 142a1 and a second extension part 142a4 extending horizontally from the first extension part 142a3. . And the base part 142a1 formed horizontally has the same vertical height as the body part 141, and the second extension part 142a4 protruding upward by the first extension part 142a3 is the main body part ( 141), it protrudes upward. In addition, the coupling side surface surrounding the second extension portion 142a4 does not share the coupling side surface with the coupling side surface of the main body portion 141, and the weak structural portion 142b is formed in a thin strip shape by a pressing process. do.

Here, the fracture support portion 142a has a thickness corresponding to the thickness of the body portion 141 of the cap plate 140 as a whole, thereby effectively forming the shear-deformed structurally weak portion 142b and breaking support portion 142a. Unexpected breakage can be prevented.

In particular, compared to the first to third embodiments in which the fracture support portion 142a is formed in a substantially flat shape, since the outer portion of the fracture support portion 142a has an arc shape protruding upward, the internal pressure can be concentrated at the corresponding portion. Therefore, compared to the structurally weak portions 142b of the first to third embodiments, the structurally weak portion 142b of the fourth embodiment is easily broken even at a low internal pressure.

Fig. 9 is a diagram for explaining a fifth embodiment of the present invention.

As shown in (a) of FIG. 9 , the vent portion 142 is formed together with the body portion 141 of the cap plate 140 through a single pressing process.

Referring to (b) of FIG. 9 , in the fifth embodiment, the fracture support portion 142a of the bent portion 142 is formed in a generally linear shape, has a flat plate shape, and has a thickness corresponding to that of the main body portion 141. is formed

At this time, as shown in (a) of FIG. 9, the breakage support part 142a has a shape in which the first bent part 142a6 and the second bent part 142a7 are connected to both ends of the line-shaped straight part 142a5. am. Specifically, the straight portion 142a5 is formed in the horizontal direction at the center of the body portion 141 . The first bent portion 142a6 and the second bent portion 142a7 extend from both ends of the straight portion 142a5 toward the outside of the straight portion 142a5 and have a 'V' shape. That is, the 'V'-shaped central portion extends to the end of the straight portion 142a5. The linear portion 142a5, the first bent portion 142a6, and the second bent portion 142a7 may be broken together by transmission of the fracture when broken.

In addition, the straight portion 142a5 formed horizontally, the first bent portion 142a6 and the second bent portion 142a7 protrude upward compared to the body portion 141 . And the coupling side surfaces surrounding the straight portion 142a5, the first bent portion 142a6, and the second bent portion 142a7 do not share the coupling side surface with the coupling side surface of the body portion 141, thin strip shape As a result, the structurally weak portion 142b is molded by a pressing process.

The cap plate 140 of the first to fifth embodiments described above may be formed by applying press working to a plate-shaped metal base material using an upper mold and a lower mold as shown in FIG. 3 .

Specifically, the raw metal plate may be formed into the cap plate 140 through press working in which the raw metal plate is interposed between the upper mold and the lower mold and a predetermined pressure is applied.

In addition, in the upper and lower molds used for press processing of the cap plate 140 once, not only the main body 141 of the cap plate 140 formed in a plate shape, but also those of the first to fifth embodiments described above are formed. A forming portion capable of forming the bent portion 142 is included, so that the bent portion 142 is molded together with the main body portion 141 of the cap plate 140 by a pressing process.

That is, a protrusion in the shape of the breakage support 142a of the bent part 142 is formed on one side of the upper mold or the lower mold (see FIG. 8(a)), and a concave portion corresponding to the protrusion is formed on the other side (FIG. 8 (b) of) it is possible to mold the fracture support portion 142a.

In addition, an empty gap is formed between the side surface of the protruding portion and the side surface of the concave portion, so that the structurally weak portion 142b can be formed.

Since the vertical pressure of the press is not directly applied to the gap portion by the protrusions and concave portions of the upper or lower mold, shear force will be generated (see (c) of FIG. 3). In addition, in the pressed state, the compression rate of the fracture support portion 142a has a compression rate corresponding to that of the main body portion 141, so that shear force is efficiently generated through the gap portion. By applying the structural shear force of the mold, the structurally weak portion 142b is formed relatively thinly in the area where the shear deformation is concentrated and the strain increases compared to the fracture support portion 142a or the main body portion 141, not only physically but also In terms of materials, it has a structure and property suitable for rupture or fracture, so that an efficient vent structure capable of being ruptured or ruptured more quickly and accurately when the internal pressure of a secondary battery rises can be formed.

In particular, it is possible to easily and intuitively set the breaking pressure of the entire vent part 142 through the adjustment of the gap between the hollow gaps of the mold, so that safety vents with various specifications can be made.

Therefore, since a separate process for forming the vent portion 142 is not added in the overall manufacturing process of the cap plate 140, the manufacturing process can be reduced through unifying parts, and manufacturing cost can be reduced through this.

As described above, the optimal embodiment has been disclosed in the drawings and specifications. Although specific terms have been used herein, they are only used for the purpose of describing the present invention and are not used to limit the scope of the present invention described in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims

A cap plate for sealing a case accommodating an electrode assembly,

a body portion covering the electrode assembly; and

a vent part formed in the body part; Including,

The vent portion and the body portion are formed together by a single press process,

The cap plate for a secondary battery of claim 1 , wherein the vent portion includes a breakage support portion having a thickness corresponding to that of the body portion and displaced from a planar direction of the body portion, and a structurally weak portion formed by shear deformation at a boundary between the breakage support portion and the body portion. .
According to claim 1,

A cap plate for a secondary battery, characterized in that the compressibility of the breakage supporting part has a compression ratio corresponding to that of the main body part.
According to claim 1,

The cap plate for a secondary battery, characterized in that the breakage support part protrudes in one of the vertical directions of the horizontal surface of the body part.
According to claim 1,

The cap plate for a secondary battery, characterized in that the structurally weak portion is formed with a relatively thin thickness in a portion where the strain is increased due to shear deformation.
According to claim 1,

The cap plate for a secondary battery, characterized in that the structurally weak portion has less ductility than the fracture support portion and the main body portion.
According to claim 1,

The cap plate for a secondary battery, wherein the structurally weak portion is formed in a shape surrounding the fracture support portion so that the cross-sectional shape thereof is symmetrical.
According to claim 1,

The breakage support part of the vent part has a flat plate shape, and the breakage support part is coupled with the flat plate-shaped body part with a height difference, so that it is formed together with a structurally weak part surrounding the breakage support part. plate.
According to claim 7,

Secondary characterized in that 10 to 20% of the total vertical length of the coupling side surface surrounding the fracture support portion is connected to the coupling side surface of the main body portion, thereby forming a structural weak portion, so that the fracture support portion and the body portion share 10 to 20% of the coupling side surface. Cap plate for batteries.
According to claim 7,

Secondary characterized in that 21 to 70% of the total vertical length of the coupling side surface surrounding the fracture support portion is connected to the coupling side surface of the main body part, thereby forming a structural weak part, so that the fracture support portion and the main body share 21 to 70% of the coupling side surface. Cap plate for batteries.
According to claim 1,

The fracture support portion of the bent portion has a flat plate shape, the fracture support portion has a height difference from the flat plate-shaped body portion, and the coupling side surface surrounding the fracture support portion does not share the coupling side surface of the main body portion and is band-shaped. A cap plate for a secondary battery, characterized in that a structurally weak portion is formed by the.
According to claim 10,

The fracture support portion is formed including a base portion formed at the same height as the main body portion and a bent portion formed to protrude upward from the base portion in an L-shape,

The bent part is composed of a first extension part extending vertically from the base part and a second extension part extending horizontally from the first extension part,

The cap plate for a secondary battery of claim 1 , wherein the horizontally formed base portion has the same vertical height as the main body portion, and the second extension portion protrudes upward compared to the main body portion.
According to claim 10,

The fracture support has a shape in which a first bent part and a second bent part are connected to both ends of a line-shaped straight part,

The first bent part and the second bent part are formed in a 'V' shape having a form in which the center portion extends to the end of the straight part at both ends of the straight part,

The cap plate for a secondary battery, characterized in that the horizontally formed straight part, the first bent part and the second bent part protrude upward compared to the body part.
A mold for manufacturing the cap plate according to any one of claims 1 to 12,

The upper mold and the lower mold may be pressed with a metal base material interposed therebetween to mold the body part and the vent part of the cap plate together.

One side of the upper mold or the lower mold is provided with a protrusion in the direction in which the press pressure is applied or in the opposite direction, and a concave portion corresponding to the protrusion is provided on the other side,

A mold for manufacturing a cap plate, characterized in that an empty gap is formed between a side surface of the protruding part and a side surface of the concave part to form a structurally weak part by generating a shear force during pressing.
According to claim 13,

The upper mold and the lower mold,

A mold for manufacturing a cap plate, characterized in that a gap between an upper mold and a lower mold in a region where the breakage support part is formed in a pressed state corresponds to a gap between the upper mold and the lower mold forming the main body part.
According to claim 13,

The mold for manufacturing a cap plate, characterized in that the structurally weak portion is formed with a relatively thin thickness in a portion where the strain is increased due to shear deformation.
A method of manufacturing the cap plate according to any one of claims 1 to 12,

Interposing a raw material metal plate between the upper mold and the lower mold; and

forming a raw metal plate into a cap plate composed of a body part and a vent part by performing press working by applying a predetermined pressure to a metal base material using an upper mold and a lower mold; Including,

One side of the upper mold or the lower mold is provided with a protrusion in the direction in which the press pressure is applied or in the opposite direction, and a concave portion corresponding to the protrusion is provided on the other side,

A method of manufacturing a cap plate, characterized in that an empty gap is formed between the side surface of the protruding part and the side surface of the concave part to form a structurally weak part by generating a shear force during pressing.
According to claim 16,

The method of manufacturing a cap plate, characterized in that the structurally weak portion is formed with a relatively thin thickness in a portion where the strain is increased due to shear deformation.