KR100484104B1 - Secondary battery and method of manufacturing cap plate including safety vent applied the same - Google Patents

Abstract

The present invention discloses a method of manufacturing a cap plate having a secondary battery and a safety valve employed therein. The present invention, the electrode assembly as a power generation element; A can containing an electrode assembly; Cap assembly is provided on the top of the can, the cap plate having a terminal hole formed in the center, and the electrode assembly penetrated into the inside of the can through the terminal through hole and the electrode terminal interposed with a gasket for the insulation of the cap plate on the outer surface ; And a safety valve having a discharge portion formed through a hole on one side of the cap plate, and a fracture portion formed by joining a metal plate to one side of the cap plate in order to block only the discharge portion. This can be done and production costs can be reduced.

Description

Secondary battery and method of manufacturing a cap plate having a safety valve employed therein {Secondary battery and method of manufacturing cap plate including safety vent applied the same}

The present invention relates to a secondary battery having a safety valve, and more particularly, to a secondary battery having an improved safety structure and a manufacturing process thereof, and a manufacturing method of a cap plate having a safety valve employed therein.

In general, a secondary battery refers to a battery that can be charged and discharged, unlike a primary battery that cannot be charged, and is widely used in advanced electronic devices such as a cellular phone, a notebook computer, and a camcorder. In particular, lithium secondary batteries have an operating voltage of 3.6V, which is three times higher than nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as electronic equipment power sources, and is rapidly increasing in terms of high energy density per unit weight. .

The lithium secondary battery mainly uses a lithium-based oxide as a cathode active material and a carbon material as a cathode active material, and may be classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte. That is, a battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery. In addition, lithium secondary batteries are manufactured in various shapes, and typical shapes include cylindrical, rectangular, and pouch types.

In such a lithium secondary battery, in the case of a lithium ion battery, when the battery is overcharged, decomposition of the electrolyte occurs at the positive electrode, and lithium metal is precipitated at the negative electrode. As a result, the characteristics of the battery may deteriorate and heat or ignition may occur. have. In the case of a lithium polymer battery, the battery may be locally overheated during charging and discharging. As a result, the weak polymer electrolyte is partially dissolved or softened due to heat, resulting in a non-uniform current and potential, which causes short circuiting and explosion and explosion of the battery. There is a possibility. In addition, the gas is generated in the battery by the electrochemical reaction, the internal pressure of the battery is increased, thereby causing the battery to expand, which continues until the battery ruptures. These phenomena are fatal to battery safety.

Therefore, many solutions have been proposed to secure the safety of the battery by solving the above problems, and among them, a safety valve is employed to discharge the gas generated in the battery to the outside at a predetermined pressure or more.

As a related art, there is a battery disclosed in Japanese Patent Laid-Open No. 9-223490. According to the disclosure, a safety valve element is provided in a lid portion of a case, and the safety valve element has a structure in which a metal sheet is laminated so as to close the through hole with respect to the metal substrate on which the through hole is formed. With the above structure, when the pressure in the battery rises, the safety valve, which is the weakest part, is broken, so that the gas is discharged to the outside.

As another related art, a battery having a safety valve is disclosed in Japanese Patent Laid-Open No. 11-73935.

However, in the above-described conventional techniques, since the safety valve is manufactured separately and installed in the lid of the battery, the manufacturing process may be complicated. In addition, the safety valve is manufactured by bonding another metal plate to a metal plate having a through hole which is a break point. When the metal plate is bonded to the entire portion other than the through hole, the process may be simplified, but the metal plate to be joined is excessive. There is a problem that the cost is increased by being used.

The present invention is to solve the above problems, to provide a method for manufacturing a cap plate having a secondary battery and a safety valve employed therein, which can simplify the manufacturing process of the safety valve and the production cost can be reduced. have.

Secondary battery according to the present invention for achieving the above object,

An electrode assembly that is a power generation element;

A can containing the electrode assembly;

A cap plate provided at an upper portion of the can, having a terminal hole formed at a center thereof, and penetrating into the can through the terminal hole, and having an electrode terminal interposed with a gasket on the outer surface thereof for insulation with the cap plate; A cap assembly; And

And a safety valve having a discharge part formed as a through hole on one side of the cap plate, and a fracture part formed by joining a metal thin plate to one side of the cap plate to partially block the discharge part.

Cap plate manufacturing method having a safety valve according to the present invention,

Preparing a metal plate for a cap plate;

Perforating the through holes in a predetermined pattern on the metal plate to form respective discharge parts of the safety valves;

Forming a plurality of break portions of safety edges by partially bonding a plurality of metal thin plates to one side of the metal plate so as to close only the through holes; And

It characterized in that it comprises a safety edge comprising a; and each of the safety valve consisting of the discharge portion and the break as described above, and forming a cap plate having a predetermined shape.

In the forming of the discharge portion, the through holes are drilled to be arranged in two rows adjacent to each other, and in the forming of the breaking portion, the thin metal plates are arranged in a row direction so that all of the through holes are intermittently occluded every two rows. It is preferable to have a safety valve characterized by bonding together.

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

1 illustrates a secondary battery according to an embodiment of the present invention.

Referring to the drawings, the secondary battery 10 includes a can 11, an electrode assembly 12 which is a power generation element accommodated in the can 11, and a cap assembly coupled to an upper portion of the can 11. 20).

The can 11 is made of a metal material having a substantially rectangular shape, and can itself serve as a terminal.

The negative electrode tab 13 and the positive electrode tab 14 protrude outward from the upper portion of the electrode assembly 12. The negative electrode tab 13 and the positive electrode tab 14 are fixed to the negative electrode plate and the positive electrode plate of the electrode assembly 12, respectively.

The negative electrode tab 13 and the positive electrode tab 14 may be arranged with different polarities. Insulation tapes 15 may be provided at portions where the negative electrode tab 13 and the positive electrode tab 14 protrude to the outside to prevent a short circuit between the electrode plates.

The cap assembly 20 is installed in the upper opening of the can 11. The cap assembly 20 includes a cap plate 21, an insulating plate 24 provided on a lower surface of the cap plate 21, and a terminal plate 25 provided on a lower surface of the insulating plate 24. do.

The cap plate 21 is coupled to the upper end of the can 11, a terminal through-hole 21a is formed in the center, and an electrolyte injection hole 21b into which the electrolyte is injected is formed at one side. In addition, the safety valve 30 is provided on the other side of the cap plate 21.

The safety valve 30 is bonded to the discharge portion 31 formed in the cap plate 21 through holes corresponding to the metal plate of the fracture portion 32 on one side of the cap plate 21 is the discharge portion 31 It consists of a structure that is blocked. On the other hand, the break 32 is formed to a size that can close the discharge portion 31 with respect to the cap plate (21). When the internal pressure rises due to the generation of gas inside the battery 10, the safety valve 30 ruptures the breaking part 32 corresponding to the discharge part 31, thereby smoothing gas to the outside of the battery 10. Can be discharged.

An electrode terminal 22 penetrating into the can 11 is installed in the terminal through hole 21a, and a gasket 23 is installed on an outer surface of the electrode terminal 22. The gasket 23 insulates the electrode terminal 22 from the cap plate 21. The electrode terminal 22 is coupled to the terminal plate 25. Meanwhile, an insulating case 26 may be further installed between the cap assembly 20 and the electrode assembly 12.

The negative electrode tab 13 may be fixed to the electrode terminal 22 through the terminal plate 25, and the positive electrode tab 14 may be directly fixed to the cap plate 21 by welding or the like and electrically connected thereto.

Meanwhile, the positions of the negative electrode tab 13 and the positive electrode tab 14 may be interchanged according to the stacking order of the electrode plates. Accordingly, a battery having a different polarity may be configured by the negative electrode tab 13 being electrically connected to the cap plate 21 and the positive electrode tab 14 respectively with the electrode terminal 22. In addition, the configuration of the cap assembly 20 is not limited to the above.

2 to 4 illustrate an embodiment of a method of manufacturing the safety valve 30 on the cap plate 21 described above.

Referring to FIG. 2, first, through-holes 42 having a predetermined pattern are drilled in the metal plate 41 for cap plate in order to manufacture a plurality of cap plates 21.

The through holes 42 form a discharge part 31 in the safety side 30 of each cap plate 21, which may be formed in the metal plate 41 by a piercing process. The through holes 42 are formed in the metal plate 41 to form a row in the X direction and a column in the Y direction, which is preferable for mass production.

In addition, the position where the through holes 42 are arranged should be determined in consideration of the size of the cap plate 21. Preferably, in the through holes 42 forming a plurality of rows in the Y direction, two rows are arranged adjacent to each other. That is, the through-holes 42 of the first row and the second row are adjacent to each other from the left side, and the through-holes 42 of the third row and the fourth row are adjacent to each other. This allows the metal thin plates 43a and 43b (see Fig. 3) to be bonded to be able to close the through holes 42 of the metal plate 41 to be accurately positioned, while performing the joining process more efficiently. There is an advantage. However, the position where the through holes 42 are arranged is not necessarily limited thereto. In addition, the size and shape of the through hole 42 is not limited to that shown, and may be modified according to the size and shape of the cap plate 21.

After the through holes 42 are formed in the metal plate 41 as described above, as shown in FIG. 3, the through metals 43a and 43b made of individual sheets are arranged in two rows. 42) are bonded to the metal plate 41 to block. That is, in the metal plate 41, the first metal thin plate 43a is bonded to a position corresponding to the adjacent through holes 42 in the first row and the second row from the left side, and corresponds to the adjacent through holes 42 in the third row and the fourth row. The second metal thin plate 43b is bonded at the position to be.

The first and second metal plates 43a and 43b are spaced apart from each other and have a size sufficient to close only the through-holes 42, respectively. The first and second metal thin plates 43a and 43b are continuously joined along the Y direction, respectively. Meanwhile, the first and second metal thin plates 43a and 43b should have a thickness that can be broken at a predetermined pressure.

As described above, when the metal thin plates 43a and 43b are bonded to the metal plate 41, the amount of unnecessary metal thin plates can be reduced by joining the metal thin plates to the entire metal plate in the related art. Can be reduced. In addition, the metal thin plates 43a and 43b corresponding to the through holes 42 of the metal plate 41 can be bonded at a more precise position, and the joining process can be performed efficiently.

Bonding of the metal plate 41 and the metal thin plates 43a and 43b may be performed by a cladding process. That is, the metal plate 41 and the metal thin plates 43a and 43b are put to face each other between a pair of rollers (not shown) to press and thermocompress them, thereby bonding them together. To this end, the roller may have a structure in which a convex portion is formed so as to press each of the portions where the metal plate 41 and the metal thin plates 43a and 43b are bonded to each other.

As shown in FIG. 4 in the state where the metal thin plates 43a and 43b are bonded to the metal plate 41 as described above, the cap plates 21 are formed.

First, a process of dividing the metal plate 41 to which the metal thin plates 43a and 43b are joined into a predetermined size may be performed. That is, the center portions of the first metal thin plate 43a and the second metal thin plate 43b bonded to the metal plate 41 are cut along the A-A line. After dividing the metal plate 41 as described above, a blanking process is performed to have a shape of a predetermined cap plate 21 with respect to each of the provided metal plates 41. By passing through the blanking process, the cap plate 21 provided with the safety valve 30 having the discharge part 31 and the breaking part 32 may be molded.

On the other hand, the terminal through-hole 21a and the electrolyte injection hole 22b provided in the cap plate 21 may be formed simultaneously with the blanking process or by a separate molding process later. In addition, the process of dividing the said metal plate 41 can be abbreviate | omitted.

After the cap plate 21 is molded as described above, a leak test is performed to determine whether there is a defect.

As described above, in the cap plate having the secondary battery according to the present invention and the safety valve employed therein, by directly forming the safety valve on the cap plate, the manufacturing process can be simplified. In addition, by bonding the metal thin plate to block only the through holes to the metal plate formed through the through holes, there is an effect that can reduce the unnecessary use of the metal thin plate to reduce the cost.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Accordingly, the true scope of protection of the invention should be defined only by the appended claims.

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

2 to 4 is a partial perspective view showing a manufacturing method of a cap plate having a safety valve in the secondary battery of FIG.

<Brief description of the major symbols in the drawings>

11.cans 12.electrode assembly

20. Cap assembly 21. Cap plate

30. Safety valve 31. Discharge part

32. Break 41. Metal plate

42 .. Through hole 43a, 43b ..

Claims (7)

delete delete Preparing a metal plate for a cap plate; Perforating the through holes in a predetermined pattern on the metal plate to form respective discharge parts of the safety valves; Forming a plurality of break portions of safety edges by partially bonding a plurality of metal thin plates to one side of the metal plate so as to close only the through holes; And Forming a cap plate having a predetermined shape and each having a safety edge consisting of the discharge portion and the break as described above; Manufacturing method of a cap plate having a safety edge comprising a. The method of claim 3, wherein In the forming of the discharge portion, the through holes are drilled to be arranged in two rows adjacent to each other, and in the forming of the breaking portion, the thin metal plates are arranged in a row direction so that all of the through holes are intermittently occluded every two rows. Cap plate manufacturing method having a safety valve characterized in that the bonding according. The method of claim 4, wherein After the step of forming the fracture portion, the method of manufacturing a cap plate having a safety valve, characterized in that further comprising the step of dividing the through-hole forming the two rows in the column direction. The method of claim 3, wherein In the forming of the fracture portion, the metal plate is a manufacturing method of the cap plate having a safety side, characterized in that the bonding to the metal plate by a cladding process. The method of claim 3, wherein In the step of forming the cap plate, the cap plate is a manufacturing method of a cap plate having a safety valve, characterized in that each of the cap plate is formed by a blanking process.