KR102259159B1 - Cap plate manufacturing mathod for secondary batteries and cap plate for secondary batteries prepared from the same - Google Patents

Abstract

The present invention provides a cap plate manufacturing method for secondary batteries and cap plate for secondary batteries prepared from the same, in which it is broken when an internal pressure of the battery exceeds a set short-circuit pressure to release the internal pressure of the battery to the outside, and a deformation or damage to the cap plate due to external force is suppressed during the manufacturing process to improve stability and reliability of the battery. To this end, the present invention is manufactured by performing: a disc forming step of forming a cap plate disc having a vent portion and a body portion extending to a periphery of the vent portion; a groove forming step of forming a groove in a boundary region between the body portion and the vent portion so that the vent portion is broken from the body portion when a short-circuit pressure is generated; an incision joint forming step of forming an incision joint by filling the groove by pressing the cap plate disc; and a terminal tab forming step of coupling a terminal tab for contact with an external circuit to the other surface of the cap plate disc opposite to the incision joint.

Description

A method for manufacturing a cap plate for a secondary battery and a cap plate for a secondary battery manufactured therefrom {CAP PLATE MANUFACTURING MATHOD FOR SECONDARY BATTERIES AND CAP PLATE FOR SECONDARY BATTERIES PREPARED FROM THE SAME}

The present invention relates to a method for manufacturing a cap plate for a secondary battery and a cap plate for a secondary battery manufactured therefrom, and more particularly, to a method for manufacturing a cap plate for a secondary battery having a safety vent for preventing thermal runaway of a secondary battery, and a method for manufacturing the cap plate for a secondary battery manufactured therefrom It relates to a cap plate for a secondary battery.

A secondary battery has an electrode assembly capable of charging and discharging comprising a positive electrode, a negative electrode, and a separator structure disposed between the positive electrode and the negative electrode.

The secondary battery is a jelly roll type in which a separator is disposed between a positive electrode and a negative electrode of a long sheet type coated with an active material according to the structure of the electrode assembly, and a separator is sequentially disposed between a plurality of positive and negative electrodes of a predetermined size. It can be classified as a stacked stack type.

In addition, the secondary battery is a cylindrical or prismatic secondary battery in which the electrode assembly is embedded in a cylindrical or prismatic metal can depending on the shape of the battery case in which the electrode assembly is embedded, and the electrode assembly is embedded in a pouch-type case of an aluminum laminate sheet. It can be classified as a pouch-type battery.

Among these various types of secondary electrodes, a jelly roll-type electrode assembly is easy to manufacture and has a high energy density per weight. In particular, a cylindrical secondary battery in which a jelly roll-type electrode assembly having a high energy density is embedded in a cylindrical metal can is an electric vehicle. It is widely used in fields requiring high-capacity secondary batteries, such as

1 is a partial cross-sectional view of a cylindrical secondary battery.

Referring to FIG. 1 , first, the secondary battery includes an electrode assembly 10 including a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes, a can 20 into which the electrode assembly 10 is inserted, and a can 20 ) may include a cap assembly 30 coupled to the open upper portion. That is, it can be manufactured by inserting the electrode assembly 10 into the can 20 with an open top, injecting an electrolyte, and then mounting the cap assembly 30 on the open top of the can 20 .

The cap assembly 30 may have a cap plate 31 coupled to the open top of the can 20 .

The cap plate 31 may be made of a material through which current passes, and may serve as a terminal (positive electrode terminal) for connection with an external circuit. The cap plate 31 may be mounted on the open upper part of the can 20 with a gasket 37 for blocking current and maintaining airtightness therebetween.

When the internal pressure of the secondary battery is higher than a set pressure value, the cap plate 31 may be separated while being deformed. Accordingly, the thermal runaway phenomenon of the secondary battery can be prevented. In this case, the separated portion of the cap plate 31 corresponds to the vent portion.

In addition, the cap assembly 30 may have a current blocking filter 35 .

The current blocking filter 35 may be installed such that a portion thereof is closely attached to the lower portion of the cap plate 31 (eg, coupled by welding), and may be made of a material through which current flows. The current blocking filter 35 may be mounted on the open top of the can 20 with the current blocking gasket 38 interposed therebetween.

The current blocking filter 35 may allow gas inside the secondary battery to pass therethrough, and the current blocking filter 35 may electrically connect the positive electrode of the electrode assembly 10 and the cap plate 31 . And, it is possible to block the current transmitted to the cap plate 31, that is, when the cap plate 31 is deformed and short-circuited, since a part of the current blocking filter 35 is separated and shorted together, the external circuit and the electrode assembly 10 The current between them can be interrupted.

As a result, when the internal pressure of the secondary battery exceeds the set short-circuit pressure due to overcharging, etc., the vent part 32 of the cap plate 31 is separated, so that the internal pressure of the secondary battery can be discharged to the outside, and at the same time By blocking the current, the stability and reliability of the secondary battery can be improved.

On the other hand, when the internal pressure of the secondary battery exceeds the set short-circuit pressure, the notch 33 is formed along the edge of the vent part 32 in order to promote and induce deformation and separation of the cap plate 31 .

However, the conventional cap plate 31 has the following problems.

As described above, the part in which the notch 33 is formed is basically broken by the internal pressure of the battery, thereby securing the safety of the battery. Therefore, there is a risk that cracks may occur or break even with a small external impact.

For example, in the process of ultrasonic wire bonding the upper cap 36 to the cap plate 31 or press-working the cap plate 31 , the rigidity of the portion where the notch 33 is formed is weakened or damaged. That is, in the manufacturing process of the cap plate 31 , the notch or vent portion may be damaged, resulting in deterioration of battery stability and reliability.

Republic of Korea Patent Publication No. 1471958 (2014.12.11. Announcement)

An object of the present invention is to solve the problems of the prior art, and the present invention is not only capable of discharging the internal pressure of the battery to the outside by breaking when the internal pressure of the battery exceeds the set short-circuit pressure, but also preventing the external force during the manufacturing process. An object of the present invention is to provide a method for manufacturing a cap plate for a secondary battery capable of increasing the stability and reliability of a battery by suppressing deformation or damage of the cap plate, and a cap plate for a secondary battery manufactured therefrom.

In order to achieve the above object of the present invention, a method for manufacturing a cap plate for a secondary battery according to an embodiment of the present invention is a method for manufacturing a cap plate for a secondary battery having a vent part that is broken at a set short-circuit pressure, the vent part and the A disk forming step of forming a cap plate disk having a body portion extending to the periphery of the vent portion; a groove forming step of forming a groove on one surface of a boundary region between the main body and the vent so that the vent is broken from the main body when the short-circuit pressure is generated; A cut-out joint forming step of forming a cut-off joint by filling the groove by pressing the cap plate disc; and a terminal tab forming step of coupling a terminal tab for contact with an external circuit to the other surface of the cap plate disc opposite to the cut-out joint, wherein the cut-out joint forming step comprises pressing the cap plate disc , It is characterized in that the cut-out joint is provided in the boundary region between the vent and the main body while filling the void of the groove while the material of the main body flows in the direction of the vent or the material of the vent flows in the direction of the main body. do it with

In the method for manufacturing a cap plate for a secondary battery according to an embodiment of the present invention, the wrinkle forming step is performed after the step of forming the cut-out joint, and forming a wrinkle part around the cut-out joint by bending the cap plate disc; may further include.

In the method for manufacturing a cap plate for a secondary battery according to an embodiment of the present invention, in the step of forming the cut joint and the step of forming the wrinkle, compression and bending may be sequentially performed by a continuous multi-stage press method.

In the method for manufacturing a cap plate for a secondary battery according to an embodiment of the present invention, the thickness of the wrinkle part may be thinner than the thickness of the body part and the vent part.

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In the method for manufacturing a cap plate for a secondary battery according to an embodiment of the present invention, the cut-off joint may be formed to be bent in the direction of the vent as the depth increases.

According to the present invention, after forming a groove portion that promotes deformation and fracture of the vent portion, by filling in the gap of the groove portion to form a cut-out joint, when the internal pressure of the battery exceeds the set short-circuit pressure, it is ruptured to effectively reduce the internal pressure of the battery Not only can it be released, but also it is possible to suppress deformation or damage to the cap plate due to an external force during the manufacturing process, and as a result, reliability and stability of the battery can be improved.

1 is a partial cross-sectional view of a cylindrical secondary battery.
2 is a flowchart illustrating a method for manufacturing a cap plate according to an embodiment of the present invention.
3 is an exemplary view showing a cap plate manufacturing method according to an embodiment of the present invention.
FIG. 4 is a comparative view for explaining an operation during the terminal tab forming step of FIG. 3 .
5 is a partial cross-sectional view of a cylindrical secondary battery to which a cap plate manufactured according to an embodiment of the present invention is applied.

Hereinafter, preferred embodiments of the present invention in which the above-described problems to be solved can be specifically realized will be described with reference to the accompanying drawings. In describing the present embodiments, the same names and reference numerals may be used for the same components, and an additional description thereof may be omitted.

2 is a flowchart illustrating a cap plate manufacturing method according to an embodiment of the present invention, and FIG. 3 is an exemplary view showing a cap plate manufacturing method according to an embodiment of the present invention.

2 and 3, in the method for manufacturing a cap plate for a secondary battery according to an embodiment of the present invention, the disc forming step (S110), the groove forming step (S120), the cutting joint forming step (S130) and the terminal tab forming step (S150) may be included.

The disc forming step (S110) may be a step of forming the cap plate disc 100A. (See Fig. 3 (a))

The cap plate disc 100A may include a central vent part 110 and a body part 130 extending around the vent part 110 .

After the disk forming step ( S110 ), the body portion 130 may have a first thickness T1 , and the vent portion 110 may have a second thickness T2 .

At this time, the second thickness T2 may be thicker than the first thickness T1, and the second thickness ( T2) may be formed to have a thickness thinner than the first thickness T1. Accordingly, the vent unit 110 may have strong durability from external impact.

The cap plate disc 100A may be molded into a container shape by using the drawing process of the press working method to form the cap plate disc 100A of the plate member, in which case the edge end 131 of the main body 130 is the upper part. direction to form a recess. As shown in FIGS. 3 (f) and 5 , the recessed end 131 of the main body 130 may be folded while being bent during mounting on the open upper part of the can 20 .

The groove forming step ( S120 ) may be a step of forming the groove 150 in the cap plate disk 100A. (See Fig. 3 (b))

The groove 150 may be formed in a boundary region between the main body 130 and the vent 110 , and may be formed on one surface facing the inner space of the battery in which the electrode assembly 10 is embedded.

Since the boundary region between the body part 130 and the vent part 110 in which the groove part 150 is formed has a thickness smaller than the thickness of the body part 130 and the vent part 110, the internal pressure of the battery is set short circuit. When the pressure is exceeded, it may deform and break.

The groove part 150 may form a closed curve structure connecting the boundary region of the body part 130 and the vent part 110 , and an open curve structure connecting the boundary region of the body part 130 and the vent part 110 . can be achieved

The groove portion 150 may be concavely formed in a V-shape on one surface of the cap plate disc 100A by using a notch mold of a press working method.

The cutting joint forming step ( S130 ) may be a step of filling the groove 150 . (See Fig. 3 (c))

That is, the gap of the groove part 150 can be filled by crimping the cap plate disc 100A, and accordingly, the gap of the groove part 150 disappears while the boundary area between the body part 130 and the vent part 110 is A cut-out joint 160 may be provided.

The cut joint 160 may be formed by compressing the cap plate disc 100A using a forging process of a press working method.

As the cap plate disk 100A is pressed several times in the process of filling the groove 150 and forming the cut-out joint 160 , the material of the main body 130 flows in the direction of the vent 110 , or the vent The material of the part 110 may flow in the direction of the body part 130 , and thus the void of the groove part 150 may be filled. In addition, in this process, the peripheral portion of the cut-out joint 160 may have a thickness thinner than the thickness of the body portion 130 and the vent portion 110 .

In addition, in the process in which the groove 150 is filled by compression processing to form the cut-out joint 160 , the cut-out joint 160 may be formed to be bent in the direction of the vent 110 as the depth increases. When the cut-out joint 160 is formed by compression processing, the material of the main body 130 may flow in the vent 110 direction, or the material of the vent 110 may flow in the body 130 direction. By controlling the lateral flow of the material of the cap plate disk 100A during compression processing, the degree of bending of the cut-out joint 160 can be formed.

If the internal pressure of the battery matches the short-circuit pressure, the vent unit 110 undergoes a process of being convexly deformed to the outside without breaking. At this time, when the depth of the cut-out joint 160 is formed to be bent in the direction of the vent 110, the vent 110 is deformed and convexly deformed to the outside to prevent deformation and damage of the cut-out joint 160. can

That is, the cut-out joint 160 naturally induces a convex deformation of the vent part 110 before the internal pressure of the battery matches the short-circuit pressure, and at the exact point when the internal pressure of the battery matches the short-circuit pressure, the cut-out joint is formed. Deformation and fracture may occur at 160 . Accordingly, the reliability of the unique role of the safety vent can be increased.

In addition, the cut-out joint 160 may be formed to be bent in the direction of the vent 110 as the depth increases even during a bending process for forming the wrinkle portion 170 to be described later.

Meanwhile, the method for manufacturing a cap plate for a secondary battery according to the present invention may further include a wrinkle forming step (S140).

The wrinkle forming step ( S140 ) may be a step of forming the wrinkled part 170 around the cut-out joint 160 . (See Fig. 3 (d))

That is, the body part 130 and the vent part 110 may be connected by the wrinkle part 170 , and the cut-out joint part 160 may be formed on the wrinkle part 170 .

The wrinkle part 170 may serve to absorb an external shock applied from the vent part 110 or the body part 130 to prevent the vent part 110 from being damaged. That is, the wrinkle portion 170 may prevent damage to the vent portion 110 due to causes other than the internal pressure of the battery.

If an external impact is applied from the outside to the inside of the vent part 110 or the body part 130 , the impact is transmitted to the cut-out joint 160 through the wrinkle part 170 . Therefore, since the external impact is not directly applied to the cut-out joint 160 and the impact is buffered at the wrinkle 170 , it is possible to prevent the part where the cut-out joint 160 is formed from being damaged by external impact.

As such, the cap plate 100 having the wrinkle portion 170 may have excellent impact resistance while normally performing the inherent role of the safety vent.

The wrinkle portion 170 may be formed by bending the peripheral portion where the cut-out joint 160 is formed, that is, the connection portion between the body portion 130 and the vent portion 110 using a bending process of the press processing method.

The thickness T3 of the wrinkle portion 170 formed by the bending process may be thinner than the thickness of the body portion 130 and the vent portion 110 .

In addition, during the bending process for forming the wrinkle portion 170 , the cut-out joint 160 may be formed to be bent in the direction of the vent portion 110 as the depth increases. That is, as the depth of the cut-out joint 160 increases from the entrance side to the inside, as the depth increases, the cut-out joint 160 may be bent in the direction of the vent unit 110 as the depth increases from the entrance side inward.

The shape of the wrinkle portion 170 may be formed to have various curvatures under conditions that do not interfere with the inherent role of the cut-out joint 160 , that is, the deformation and breaking action caused by the internal pressure of the battery.

On the other hand, the cutting joint forming step (S130) and the wrinkle forming step (S140) may be made by a progressive mold in which a series of processes are continuously performed in one mold. That is, as the cap plate disc 100A is compressed and bent simultaneously with a single mold, the groove 150 is filled to form the cut-out joint 160, and then the wrinkle 170 is sequentially formed on the periphery of the cut-out joint 160. can be formed with

The terminal tab forming step ( S150 ) may be a step of coupling the terminal tab 180 to the other surface of the cap plate disk 100A opposite to the cut-out joint 160 . (See Fig. 3 (e))

The terminal tab 180 may be in contact with an external circuit.

The terminal tab 180 may be fixedly coupled to the cap plate disk 100A using an ultrasonic wire bonding device. Ultrasonic wire bonding involves attaching a small wire between the object and an object, and bonding the wire while vibrating the wire at a high frequency of about 60,000 Hz or more. That is, as in ultrasonic wire bonding, an external force such as vibration may be applied to the cap plate disc 100A in the process of coupling the terminal tab 180 to the cap plate disc 100A.

FIG. 4 is a comparative view for explaining an operation during the terminal tab forming step of FIG. 3 .

As shown in Fig. 4 (a), if the terminal tab 180 is ultrasonic wire-bonded to the cap plate disc having the groove portion 150A, vibration is applied to the cap plate disc in the bonding process, and accordingly, the The thin groove 150A may be deformed or damaged.

On the other hand, as shown in FIG. 4(b), when the terminal tab 180 is ultrasonically wire-bonded to the cap plate disc having the cut joint 160, even if vibration is applied to the cap plate disc in the bonding process, the cut joint is Since 160 maintains a solid structure without a space, it is possible to suppress the problem that the peripheral portion of the cut-out joint 160 is deformed or damaged. As a result, the present invention can increase the reliability of the product as well as the stability of the battery.

When the manufacturing of the cap plate integrating the terminal tab 180 is completed, as shown in FIG. 3(f) , the edge end 131 of the main body 130 may be bent to reinforce it.

In addition, when the cap plate 100 integrating the terminal tab 180 is manufactured, the current cut-off filter 200 (refer to FIG. 5 ) may be additionally welded to the lower surface of the vent part 110 of the cap plate 100 . .

5 is a partial cross-sectional view of a cylindrical secondary battery to which a cap plate manufactured according to an embodiment of the present invention is applied.

First, the electrode assembly 10 is inserted into the can 20 with an open top, the electrolyte is injected, and then the cap assembly 30 is mounted on the open top of the can 20 .

That is, the cap plate 100 including the current blocking filter 200 is mounted on the open upper part of the can 20 with the gaskets 37 and 38 for blocking and airtightness therebetween.

When the internal pressure of the battery rises close to the set short-circuit pressure, the vent part 110 of the cap plate 100 together with the current cut-off filter 200 may be convexly deformed upward. Here, if the internal pressure of the battery exceeds the set short-circuit pressure, the cut-out joint 160 of the cap plate 100 is broken and the vent part 110 is separated from the body part 130, along with the current cut-off filter ( 200) may be broken together. Therefore, while blocking the current connected to the external circuit, the internal pressure of the battery is effectively released to the outside, thereby greatly improving the stability and reliability of the battery.

On the other hand, since the cap plate 100 manufactured by this embodiment integrates the terminal tab 180 coupled to the upper surface, the existing upper cap 36 is excluded as shown in FIG. 1 to reduce the size of the secondary battery and The manufacturing process of the cap assembly 30 can be further simplified.

Although the preferred embodiment of the present invention has been described with reference to the drawings as described above, those skilled in the art may vary the present invention in various ways without departing from the spirit and scope of the present invention as set forth in the following claims. may be modified or changed.

100: cap plate
110: vent unit
130: body part
150: groove
160: cut-out joint
170: wrinkles
180: terminal tab

Claims (7)

A method for manufacturing a cap plate for a secondary battery having a vent part that is broken at a set short-circuit pressure, comprising:
a disk forming step of forming a cap plate disk having the vent portion and a body portion extending in a periphery of the vent portion;
a groove forming step of forming a groove on one surface of a boundary region between the main body and the vent so that the vent is broken from the main body when the short-circuit pressure occurs;
A cut-out joint forming step of forming a cut-off joint by filling the groove by pressing the cap plate disc; and
a terminal tab forming step of coupling a terminal tab for contact with an external circuit to the other surface of the cap plate disc opposite to the cut-out joint;
In the cutting joint forming step, as the cap plate disc is pressed and processed, the material of the body part flows in the direction of the vent part or the material of the vent part flows in the direction of the body part while filling the void of the groove part, and the vent part and the cap plate manufacturing method for a secondary battery, characterized in that the cut-out joint is provided in a boundary region of the main body. The method of claim 1,
It is carried out after the step of forming the incision joint,
The method of manufacturing a cap plate for a secondary battery further comprising; forming a wrinkle part around the cut-out joint by bending the cap plate disc to form a wrinkle part. The method of claim 2,
The method for manufacturing a cap plate for a secondary battery, characterized in that in the step of forming the cut joint and the step of forming the wrinkle, compression and bending are sequentially performed by a continuous multi-stage press method. The method of claim 2,
The thickness of the wrinkle portion is a cap plate manufacturing method for a secondary battery, characterized in that formed thinner than the thickness of the body portion and the vent portion. delete The method of claim 1,
The method for manufacturing a cap plate for a secondary battery, characterized in that the cut-off joint is formed to be bent in the direction of the vent portion as the depth increases. A cap plate for a secondary battery manufactured by the method for manufacturing a cap plate for a secondary battery according to any one of claims 1 to 4 and 6 .

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