KR100686857B1 - Can type secondary battery and method of fabricating the same - Google Patents

Abstract

Provided are a can type secondary battery which prevents leakage of an electrolytic solution, and a fabricating method thereof which improves a work efficiency by omitting a welding process and a photo-curable resin coating process. The can type secondary battery is manufactured by the steps of: forming an electrode assembly consisting of a positive electrode, a negative electrode, and a separator; inserting the electrode assembly into an opening of a can, and combining a cap assembly with the opening of the can, wherein the cap assembly includes a cap plate(210) having an electrolytic solution injection hole(212) at one side; forming film(211) on the electrolytic solution injection hole(212); injecting an electrolytic solution into the can through the film-formed electrolytic solution injection hole(212); and pressing a ball(260) in the film-formed electrolytic solution injection hole(212) to seal the electrolytic solution injection hole(212).

Description

Can type secondary battery and its manufacturing method {Can type Secondary Battery and Method Of Fabricating The Same}

1 is an exploded perspective view illustrating an example of a lithium ion battery having a rectangular structure as an example of a conventional can type secondary battery.

2 is a top cross-sectional view illustrating an assembled state of a can type secondary battery according to an exemplary embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view illustrating an electrolyte injection hole formed in a cap plate of the can type secondary battery of FIG. 2.

4 is a flowchart illustrating a method of manufacturing a can type secondary battery according to an exemplary embodiment of the present invention.

5A to 5E are partial cross-sectional views of a cap plate for explaining a method of sealing an electrolyte injection hole in a method of manufacturing a can type secondary battery according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

11, 21 can 12, 22 electrode assembly

13, 23: anode 14, 24: separator

15, 25: negative electrode 16, 26: positive electrode tab

17, 27: negative electrode tab 18, 28: insulating tape

110, 210: cap plate 112, 212: electrolyte inlet

120, 220: gasket 130, 230: electrode terminal

140, 240: insulation plate 150, 250: terminal plate

190, 290: insulated cases 191, 291: holes for negative electrode tab

192, 292: electrolyte passing hole 160, 260: stopper

211: film 214: step surface

300: loading

302: liquid solvent

The present invention relates to a secondary battery, and more particularly, to a can-type secondary battery and a method of manufacturing the same, forming a film in the electrolyte injection hole and compressing the ball to seal the electrolyte injection hole.

Secondary batteries are rechargeable and thus are widely used as power sources for portable electric and communication devices. In particular, nickel-hydrogen (Ni-MH) batteries and lithium-ion (Li-ion) batteries and the like are capable of miniaturization and large capacity, and their use is increasing. As these secondary batteries, canned secondary batteries are usually used. The can-type secondary battery has a structure in which an electrode assembly obtained by stacking approximately two electrodes and a separator is stacked together with an electrolyte solution in a metal can, and the inlet is sealed. The tab of the electrode is of course drawn out of the metal can for external electrical connection.

Hereinafter, the case of a lithium ion battery is demonstrated as an example of a can type secondary battery.

Lithium is of high value as an electrode material for batteries due to its high activity and low atomic weight. On the other hand, even in the case of using a liquid electrolyte, a lithium ion battery uses a nonaqueous electrolyte due to the reactivity of lithium and water (H ₂ O). As the non-aqueous electrolyte is used, the lithium ion battery may have a relatively high battery voltage because it is not limited by the decomposition voltage of water during charging.

In the liquid electrolyte, the lithium salt is present in the dissociated state in the organic solvent. As the solvent in which the lithium salt is dissolved, ethylene carbonate or other alkyl group-containing carbonate or similar organic compound is used.

In the case of a can-type lithium ion battery using a liquid electrolyte, preventing leakage is an important problem as in the case of a general chemical battery. The leakage of a lithium ion battery is associated with the penetration of moisture or air into the lithium ion battery because the electrolyte solvent is flammable and may cause safety problems such as a fire. In particular, considering that mobile phones, computers, personal digital assistants, camcorders, etc., in which lithium ion batteries are used as power sources, are expensive and precision devices, the problem of leakage prevention becomes more important for the protection of these devices.

To prevent leakage, the sealing between the cap plate periphery and the top of the can and the sealing between the electrolyte inlet and the surrounding cap plate portion need to be made precisely and reliably. It demonstrates, referring the structure of a normal can type secondary battery.

1 is an exploded perspective view showing an example of a lithium ion battery having a rectangular structure as an example of a conventional secondary battery.

Referring to FIG. 1, a conventional rectangular lithium ion battery includes an electrode assembly 12 including a positive electrode 13, a separator 14, and a negative electrode 15, a can 11 containing an electrode assembly, and a can ( 11) includes a cap assembly to which it is coupled. In the electrode assembly 12, positive and negative electrode tabs 16 and 17 connected to each electrode are drawn out. The can 11 is a metal container having an approximately cuboid shape in a rectangular lithium ion battery as shown. The top, which is open for the electrode assembly 12 to be inserted, is sealed by the cap assembly.

The cap assembly is provided with a cap plate 110, and the electrode terminal 130 is mounted in the hollow 111 of the cap plate 110 via a gasket 120. An electrolyte injection hole 112 is formed at one side of the cap plate 110 to inject the electrolyte into the can 11 while the electrode assembly is placed in the can and the inlet is sealed by the cap assembly. After the injection of the electrolyte, a ball having a larger diameter than the electrolyte injection hole is placed in the electrolyte injection hole, and mechanically press-fitted into the electrolyte injection hole to form a stopper 160 to seal the electrolyte injection hole.

The positive electrode tab 16 is electrically connected to the cap plate 110 by welding or the like, and the negative electrode tab 17 is also electrically connected to the electrode terminal 130 insulated from the cap plate 110 by the gasket 120. It is electrically connected by methods, such as welding. The positive and negative electrode tabs 16 and 17 are electrically connected according to polarities, respectively, to a positive temperature coefficient (PTC) and a protection circuit portion (not shown).

The conventional electrolyte injection hole 112 formed on one side of the cap plate 110 is mechanically pressurized into a ball of a soft metal material after the electrolyte is injected, and then the periphery of the electrolyte injection hole 112 for close contact between the ball and the electrolyte injection hole 112. This is welded. However, the external pressure generated when the electrolyte injection hole 112 is mechanically indented into the ball by force may directly affect the cap plate 110 having the electrolyte injection hole 112. Accordingly, a phenomenon in which the electrolyte injected into the can 11 is leaked to the outside through the electrolyte injection hole 112 before the electrolyte injection hole 112 is welded, or excessive sparking occurs during welding due to the leakage electrolyte causes pinholes to be leaked. It is difficult to ensure the sealability of the electrolyte injection hole 112 is formed. In addition, when welding the electrolyte inlet 112, the temperature of the welded portion rises, so that the electrolyte located in the lower part of the electrolyte inlet 112 evaporates, and the sidewall portion of the electrolyte inlet 112 is in contact with the ball. The electrolyte vapor may seep into it and leak the electrolyte. In order to prevent this, the welding site is coated with a photocurable resin. However, even in this case, when the photocurable resin is dropped on the welded portion, it may not fall to a desired position and there is a risk that the hardener may fall off due to a slight external impact even after being cured off at a desired position. Therefore, even in this case, it is difficult to prevent leakage of the electrolyte solution.

As described above, the conventional secondary battery using the welding method to close the electrolyte injection hole of the cap plate has a high possibility of leakage of electrolyte during welding, and a process of coating a photocurable resin has to be added.

The present invention is to solve the above-mentioned problems of the prior art, by forming a coating on the injection hole of the electrolyte solution and by pressing the ball to seal the electrolyte injection port to prevent leakage of the electrolyte solution, in addition to the welding process when the electrolyte injection hole is closed It is an object of the present invention to provide a can-type secondary battery and a method of manufacturing the same, which can reduce the number of steps by omitting the photocured resin coating step that has been performed to increase the work efficiency.

The can-type secondary battery of the present invention for achieving the above object comprises an electrode assembly consisting of a positive electrode, a negative electrode and a separator; A can for accommodating the electrode assembly and the electrolyte solution together; And a cap plate closing the opening of the can and having an electrolyte injection hole formed on one side thereof, wherein an elastic coating is provided between the electrolyte injection hole and a stopper for blocking the electrolyte injection hole.

The coating may be formed to continuously surround the outer wall of the stopper.

The electrolyte injection hole may be formed of an upper portion and a lower portion, and the upper inner diameter may be larger than the lower inner diameter so that there is a step between the upper and lower portions.

The coating may be formed on an inner surface of the upper portion of the electrolyte injection hole and a stepped surface forming a step between the upper and lower portions of the electrolyte injection hole.

The coating may be made of fluorine resin or polyolefin resin, and the coating may be made of any one selected from the group consisting of fluorine rubber, butadiene rubber, and butyl rubber (Isobutylene-Isoprene rubber). .

The can-type secondary battery manufacturing method of the present invention comprises the steps of forming an electrode assembly consisting of a positive electrode, a negative electrode and a separator; Accommodating the electrode assembly in an opening of the can, and coupling a cap assembly including a cap plate having an electrolyte injection hole formed at one side thereof to the opening of the can; Forming a film in the electrolyte injection hole; Injecting electrolyte into the can through the electrolyte injection hole in which the film is formed; And sealing the electrolyte injection hole by inserting a ball into the electrolyte injection hole in which the film is formed.

The forming of the film on the electrolyte injection hole may include preparing a dropper having a liquid solvent to be dropped; Focusing the dropper on one end of an upper portion of the electrolyte injection hole formed in an upper portion and a lower portion; Dropping the predetermined liquid solvent from the dropper at one end of the upper portion of the electrolyte injection hole corresponding to the focal point of the dropper; Dropping the liquid solvent while moving the dropping along an edge of the upper portion of the electrolyte injection hole; And drying the liquid solvent applied on the electrolyte injection hole to form the film.

Pressing the ball into the electrolyte injection hole in which the coating is formed to seal the electrolyte injection hole may include inserting a ball into the electrolyte injection hole in which the coating is formed; And sealing the electrolyte inlet by forming a stopper by inserting a ball inserted into the electrolyte inlet.

The liquid solvent may include a material having a high elasticity resin or rubber and a liquid dissolving the material.

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

2 is a top cross-sectional view illustrating an assembled state of a can type secondary battery according to an exemplary embodiment of the present invention.

As shown in FIG. 2, a can type secondary battery according to an exemplary embodiment of the present invention includes a can 21, an electrode assembly 22 accommodated in the can 21, and an open of the can 21. A cap assembly coupled with the top to seal the top of the can.

The can 21 may be formed of a metal material, such as aluminum, an aluminum alloy, or iron, having a substantially rectangular parallelepiped container shape, and may itself serve as a terminal.

The positive electrode 23 includes a positive electrode current collector made of a thin metal plate having excellent conductivity, such as aluminum foil, and a positive electrode active material layer mainly composed of lithium-based oxides coated on both surfaces thereof. The positive electrode tab 26 is electrically connected to a region of the positive electrode current collector in which the positive electrode active material layer is not formed.

The negative electrode 25 includes a negative electrode current collector made of a conductive metal sheet, such as a copper foil, and a negative electrode active material layer mainly composed of a carbon material coated on both surfaces thereof. The negative electrode tab 27 is also connected to an area of the negative electrode current collector in which the negative electrode active material layer is not formed.

The positive electrode 23 and the negative electrode 25 and the positive electrode tabs and the negative electrode tabs 26 and 27 may be arranged with different polarities, and at the boundary where the positive electrode tabs and the negative electrode tabs 26 and 27 are drawn out of the electrode assembly. Insulating tapes 28 are respectively wound to prevent short circuits between the electrodes 23 and 25.

The separator 24 is made of polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene. The separator 24 is formed to be wider than the positive and negative electrodes 23 and 25 to prevent short circuits between the electrode plates.

The cap assembly is provided with a flat cap plate 210 having a size and shape corresponding to the open top of the can 21. The central portion of the cap plate 210 is formed with a through hole for the terminal so that the electrode terminal can pass through. A tube-shaped gasket 220 is installed outside the electrode terminal 230 penetrating the central portion of the cap plate 210 for electrical insulation between the electrode terminal 230 and the cap plate 210. The insulation plate 240 is disposed on the lower surface of the cap plate near the center of the cap plate 210 and the through hole for the terminal. The terminal plate 250 is provided on the lower surface of the insulating plate 240.

The electrode terminal 230 is inserted through the terminal through-hole in the state in which the gasket 220 surrounds the outer circumferential surface. The bottom portion of the electrode terminal 230 is electrically connected to the terminal plate 250 with the insulating plate 240 interposed therebetween.

The positive electrode tab 26 drawn from the positive electrode 23 is welded to the lower surface of the cap plate 210, and the negative electrode tab 27 drawn from the negative electrode 25 is folded in a meander at the lower end of the electrode terminal 230. Welded at

On the other hand, an insulating case 290 is provided on the upper surface of the electrode assembly 22 to cover the upper end of the electrode assembly 22 for electrical insulation between the electrode assembly 22 and the cap assembly. The insulating case 290 is an insulating polymer resin, preferably made of polypropylene. A negative electrode tab hole 291 is formed to allow the center portion of the electrode assembly 22 and the negative electrode tab 27 to pass therethrough, and an electrolyte passage hole 292 is formed at the other side. The electrolyte passage hole may not be formed separately.

One side of the cap plate 210 is formed of an upper and a lower, and the electrolyte injection hole 212 has a larger inner diameter than the lower inner diameter is formed so that the step between the upper and lower. The electrolyte inlet 212 is provided with a stopper 260 to seal the electrolyte inlet after the electrolyte is injected. The stopper 260 is usually formed by placing a ball made of aluminum or an aluminum-containing metal on the electrolyte injection hole and press-fit into the electrolyte injection hole.

FIG. 3 is an enlarged cross-sectional view illustrating an electrolyte injection hole formed in a cap plate of the can type secondary battery of FIG. 2.

As shown in FIG. 3, the electrolyte injection hole 212 located at one side of the cap plate 210 has a film at a predetermined position, and a stopper 260 formed by compressing a ball on the formed film 211. It is sealed by. The coating film 211 is formed on the inner surface of the upper portion of the electrolyte inlet 212 and the stepped surface 214 forming a step between the upper and lower portions of the electrolyte inlet 212 so as to continuously surround the outer wall of the stopper 260. . Here, the film 211 is formed by drying a solvent of a liquid solvent of resin or rubber material. The resin contained in the liquid solvent is made of fluorine resin or polyolefin resin, and the rubber contained in the liquid solvent is made of fluorine rubber, butadiene rubber or butyl rubber (Isobutylene-Isoprene rubber). A ball is pressed into the film thus formed to seal the electrolyte injection hole 212.

4 is a flowchart illustrating a method of manufacturing a can type secondary battery according to an exemplary embodiment of the present invention.

Referring to FIG. 4, a method of manufacturing a can type secondary battery according to an embodiment of the present invention is as follows.

First, in the step (S1) of forming the electrode assembly, the positive electrode, the separator, and the negative electrode are arranged in this order, and wound in a jelly-roll type to form an electrode assembly.

Thereafter, the electrode assembly thus formed is accommodated in the opening of the can (S2).

Then, the cap assembly including the cap plate on which the electrolyte injection hole is formed is coupled with the can by welding (S3).

Next, the electrolyte is injected through the electrolyte injection hole formed in the cap plate. (S4)

Finally, the ball is pressed into the electrolyte injection hole where the film is formed and compressed to seal the electrolyte injection hole (S5).

5A to 5E are partial cross-sectional views of a cap plate for explaining a method of sealing an electrolyte injection hole in a method of manufacturing a can type secondary battery according to an embodiment of the present invention.

As shown in FIG. 5A, a dropper 300 containing a load 302 is first prepared and positioned on an upper portion of the electrolyte injection hole 212 to be sealed. At this time, the focal point of the dropper 300 is adjusted to one end of the electrolyte injection hole 212.

Then, as shown in FIG. 5B, the dripping material 302 is dropped from the dropping 300 focused on one end of the electrolyte injection hole 212. Here, the load 302 is a liquid solvent including a resin or rubber material having a large elasticity and a liquid dissolving the material. After dropping a predetermined liquid solvent 302 at one end of the electrolyte inlet 212, the dropping 300 is the edge of the upper portion of the electrolyte inlet 212 to form a coating that continuously surrounds the outer wall of the stopper to be described later. The liquid solvent 302 is dropped while moving along. Here, the resin contained in the liquid solvent is made of fluorine-based resin or polyolefin (polyolefin) resin, etc., the rubber is made of fluorine-based rubber, butadiene rubber (Butadiene rubber) or butyl rubber (Isobutylene-Isoprene rubber).

Next, as shown in FIG. 5C, the liquid solvent dropped to the electrolyte injection hole 212 is dried. Then, only a resin or rubber material remains on the inner surface of the upper portion of the electrolyte injection hole 212 and the upper surface of the electrolyte injection hole 212 and the lower portion of the electrolyte injection hole 212 so that the film 211 is formed. Is formed.

Thereafter, the electrolyte is injected, and as shown in FIG. 5D, a ball having a diameter equal to or larger than the diameter of the electrolyte injection hole 212 is inserted into the electrolyte injection hole 212 to be press-fitted. Then, as illustrated in FIG. 5E, a ball is compressed to the electrolyte injection hole 212 having the coating 211 and a stopper 260 is formed to seal the electrolyte injection hole 212.

In this way, the electrolyte injection hole is formed by using a liquid solvent containing a resin or rubber material, and the method of sealing the ball by pressing the ball occurs due to a poor welding when using a conventional method of welding after injecting a ball. Leakage of the electrolyte solution can be prevented, and the photocuring resin coating step, which was additionally necessary due to the conventional welding method, can be omitted.

 As described above, the can-type secondary battery according to the present invention is provided with a film formed by drying a solvent after a liquid solvent containing a resin or rubber material is buried in an electrolyte inlet, and a ball is pressed into the film to remain. Sealing is ensured by compressing the coating film. Accordingly, leakage of the electrolyte solution, which has occurred due to poor welding, can be prevented when the electrolyte injection port is sealed by welding after pressing the ball.

In addition, the can-type secondary battery according to the present invention forms a film in the electrolyte injection hole and press-fits the ball to seal the electrolyte injection hole, so that the ball injection process, welding process, photocuring resin coating process, etc., which are conventionally performed when the electrolyte injection hole is sealed. The process can be simplified by omitting a process such as welding or photocuring resin coating in a complicated process. Accordingly, the manufacturing method of the can type secondary battery of the present invention can increase the work efficiency.

As described above, the present invention is not limited to the specific preferred embodiments described above, and any person having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Various modifications are possible, of course, and such changes are within the scope of the claims.

Claims (10)

An electrode assembly comprising an anode, a cathode, and a separator; A can for accommodating the electrode assembly and the electrolyte solution together; And In the secondary battery closing the opening of the can, having a cap plate formed with an electrolyte injection hole on one side, A can-type secondary battery, characterized in that an elastic coating is provided between the electrolyte injection hole and the stopper blocking the electrolyte injection hole. The method of claim 1, And the coating is formed so as to continuously surround the outer wall of the stopper. The method of claim 1, The electrolyte injection hole may be formed of an upper portion and a lower portion, and the upper inner diameter may be larger than the lower inner diameter so that a step is formed between the upper portion and the lower portion. The method of claim 3, The film is a can-type secondary battery, characterized in that formed on the inner surface of the upper portion of the electrolyte injection hole and the step surface forming a step between the upper and lower electrolyte injection hole. The method of claim 1, The film is a can-type secondary battery, characterized in that the fluorine resin or polyolefin resin. The method of claim 1, The film is a can-type secondary battery, characterized in that made of any one selected from the group consisting of fluorine-based rubber, butadiene rubber (Butadiene rubber) and butyl rubber (Isobutylene-Isoprene rubber). Forming an electrode assembly consisting of an anode, a cathode, and a separator; Accommodating the electrode assembly in an opening of the can, and coupling a cap assembly including a cap plate having an electrolyte injection hole formed at one side thereof to the opening of the can; Forming a film in the electrolyte injection hole; Injecting electrolyte into the can through the electrolyte injection hole in which the film is formed; And And inserting a ball into the electrolyte injection hole in which the coating is formed to seal the electrolyte injection hole. The method of claim 7, wherein Forming a film in the electrolyte injection hole is Preparing a dropper with a liquid solvent to be loaded; Focusing the dropper on one end of an upper portion of the electrolyte injection hole formed in an upper portion and a lower portion; Dropping the predetermined liquid solvent from the dropper at one end of the upper portion of the electrolyte injection hole corresponding to the focal point of the dropper; Dropping the liquid solvent while moving the dropping along an edge of the upper portion of the electrolyte injection hole; And And drying the liquid solvent applied to the upper portion of the electrolyte injection hole to form the coating film. The method of claim 7, wherein Pressing the ball into the electrolyte injection hole in which the film is formed to seal the electrolyte injection hole is Inserting a ball into the electrolyte injection hole in which the coating is formed; And And inserting a ball inserted into the electrolyte injection hole to form a stopper to seal the electrolyte injection hole. The method of claim 9, The liquid solvent is a manufacturing method of a can-type secondary battery, characterized in that it comprises a material of high elastic resin or rubber material and a liquid dissolving the material.

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