KR100719732B1 - Secondary battery - Google Patents

Abstract

The present invention relates to a secondary battery, and includes a bare cell, a protective circuit board connected to the bare cell, and a lead plate which connects the bare cell and the protective circuit board and has a short prevention portion, so that the molding resin is moved when the lead plate is moved. There is an advantage in reducing the possibility of contact with the mold for injection.

Secondary Battery, Lead Plate, Short Circuit Protection, Chamfer

Description

Secondary Battery {SECONDARY BATTERY}

1 is an exploded perspective view of a secondary battery according to the present invention;

2 is a cross-sectional view of a secondary battery according to the present invention;

3 is a view showing a lead plate of a secondary battery according to the present invention;

4 is a view illustrating a secondary battery according to the present invention.

<Brief Description of Major Codes in Drawings>

100 cap assembly 110 cap plate

111: first terminal through hole 113: electrolyte injection hole

115: stopper 120: gasket

130: first electrode terminal 140: insulating plate

141: second terminal through hole 150: terminal plate

151: third terminal through hole 160: insulated case

200 case 210 first electrode plate

215: first electrode tab 220: second electrode plate

225: second electrode tab 230: separator

250: electrode assembly 300: protective circuit board

310,320: First and second external terminals 410,420: First and second lead plates

The present invention relates to a secondary battery, and more particularly, to a bare cell including an electrode assembly, a can, and a cap assembly, and a secondary battery formed by electrically connecting a protective circuit board to the bare cell.

Secondary batteries have been researched and developed in recent years due to the possibility of recharging and miniaturization and large capacity. Representative examples of the recent development and use include nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium-ion (Li-ion) batteries.

In these secondary batteries, most of the bare cells house electrode assemblies consisting of first and second electrode plates and separators having different polarities, usually in a can made of aluminum or aluminum alloy, and the can is closed with a cap assembly. It is formed by injecting and sealing an electrolyte solution.

By the way, a battery has the possibility of emitting much energy as an energy source. In the case of a secondary battery, energy is stored in itself in a state where it is charged, and in the process of charging, energy is accumulated from other energy sources. When an abnormality of a secondary battery such as an internal short circuit occurs in such a process or state, energy stored in the battery is released in a short time, which may cause safety problems such as ignition and explosion.

Recently used lithium-based secondary battery has a high activity of the lithium itself because of the high risk of fire or explosion when a battery failure occurs. In the case of a lithium ion battery, only lithium in an ionic state exists, not lithium in a metal state, and thus safety is improved compared to a battery using metal lithium. However, materials such as negative electrodes and non-aqueous electrolytes, which are still used in batteries, have a high risk of ignition or explosion when battery abnormalities occur due to flammability.

Accordingly, the secondary battery is equipped with various safety devices to prevent fire or explosion due to an abnormality of the battery itself in the charged state or during the charging process. Safety devices are connected to the positive and negative terminals of the bare cell by a conductor structure, commonly referred to as a lead plate. These safety devices cut off the current when the battery voltage rises rapidly due to a high temperature rise of the battery, excessive charge or discharge, or the like, thereby preventing the battery from rupturing or igniting. The safety devices connected to the bare cell include a protection circuit that senses an abnormal current or voltage and prevents current flow, a positive temperature coefficient (PTC) element operating by overheating due to the abnormal current, and a bimetal.

The secondary battery in a state in which the bare cell and the safety device are combined is stored in a separate case to form a secondary battery having a completed appearance. Alternatively, the safety devices such as the bare cell and the protection circuit board are electrically connected to each other, and the gaps therebetween are filled with the molding resin, and are fixed or coated together to form a secondary battery having a completed appearance.

However, it is common for secondary batteries to vary in composition, form, size, etc., of elements used in manufacturing, by product model for each manufacturer, and the design of an appropriate safety device also varies according to these various factors. In general, manufacturers of secondary batteries form a secondary battery by combining a bare cell and a protection circuit into an integrated package. Secondary batteries are often determined in material and design to form part of the product set on which the secondary batteries are mounted.

In this situation, the secondary battery is not compatible with the product, and it is difficult for the consumer to arbitrarily select the secondary battery to be used in the product set. Even if the battery's operating conditions and functions were the same, no secondary battery could be used other than the exclusively designed product for the product set.

In order to solve this problem, secondary batteries are manufactured to be mounted inside the casing of various product sets when the operation conditions and functions of the batteries are the same as the primary batteries. In this case, the secondary battery may be made of a pack type secondary battery in which a bare cell and a safety terminal such as a protective circuit board are first connected by welding, and a space between them is filled with a molding resin to physically combine the bare cell and the protective circuit. many.

The secondary battery must use a mold to pour the molding resin between the bare cell and the protective circuit board and to harden it. That is, the bare cell and the protective circuit board are formed by receiving a molding resin after being accommodated in a mold.

However, in the secondary battery, when the molding resin is injected into the mold mold, the lead plate connecting the bare cell and the protection circuit board may be turned by the molding resin injected. Thus, when the lead plate is moved, there is a problem that the lead plate may be shorted in contact with the mold frame.

In order to solve the problems as described above, an object of the present invention is to provide a secondary battery that reduces the short-circuit in contact with the lead plate member having a different polarity.

The present invention for achieving the above object provides a secondary battery comprising a bare cell, a protective circuit board connected to the bare cell and a lead plate connecting the bare cell and the protective circuit board and having a short prevention portion. .

The short prevention portion may be a short prevention groove formed so that the edge portion of the lead plate is recessed inward, and the short prevention groove may be formed by chamfering.

The chamfer angle may be about 40 ~ 60 °, the chamfer width of the lead plate is preferably 10 to 20% of the width of the lead plate.

The short prevention groove is preferably formed in a curve.

The bare cell includes a case, a cap that is accommodated inside the case and includes an electrode assembly in which the first and second electrode tabs are drawn out, and an electrode terminal and a cap plate that seal the case and are connected to the first and second electrode tabs. It may be an assembly.

The case may be rectangular, and the electrode terminal may have a negative polarity.

Hereinafter, an embodiment of a secondary battery according to the present invention will be described in detail with reference to the drawings.

1 is an exploded perspective view of a secondary battery according to the present invention, Figure 2 is a cross-sectional view of the secondary battery according to the present invention.

3A and 3B illustrate a lead plate of a rechargeable battery according to the present invention, and FIG. 4 illustrates a rechargeable battery according to the present invention.

Referring to these drawings, the secondary battery is coupled to the case 200 having an opening at one side, an electrode assembly 250 accommodated in the case 200, and an opening 201 of the case 200, and the case 200. It has a bare cell consisting of a cap assembly 100 for sealing the top of the.

In the present embodiment, the case 200 is formed of aluminum or an aluminum alloy having a substantially rectangular box shape to accommodate the electrode assembly 250 and the electrolyte through the opening 201 of the case 200. The case 200 may itself serve as an electrode terminal of any one of the first and second electrodes.

The electrode assembly 250 may be formed in a thin plate shape or a film shape and may include a second electrode plate 210 having a first electrode plate 210, a separator 230, and a second electrode tab 225 connected to the first electrode tab 215. The laminate of 220 is wound to form a spiral shape. In this case, the first and second electrode plates 210 and 220 may be a cathode or an anode. Here, the first electrode plate 210 may typically be a cathode.

The negative electrode plate includes a negative electrode current collector made of a conductive metal thin plate, such as a copper foil, and a carbon material coated on both surfaces thereof as a main component. The negative electrode terminal is connected to an area of the negative electrode current collector in which the negative electrode active material layer is not formed on the negative electrode plate and is drawn out upward.

The positive electrode plate includes a positive electrode current collector made of a thin metal plate such as aluminum foil having excellent conductivity, and a positive electrode active material layer coated on both surfaces thereof and having a lithium oxide as a main component. In the positive electrode plate, the positive electrode terminal is electrically connected to a region of the positive electrode current collector in which the positive electrode active material layer is not formed, and is drawn out.

The separator 230 is made of polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene (Co-Polymer), and is formed to be wider than the first and second electrode plates 210 and 220 to form a short circuit between the electrode plates. It is advantageous to prevent this.

The cap assembly 100 is a case 200 covers and seals the opening 201, and is provided with a flat cap plate 110 having a size and a shape corresponding to the opening 201 of the case 200. . An insulating plate 140 is installed on the lower surface of the cap plate 110, and a terminal plate 150 electrically connected to the first electrode tab 215 provided on the first electrode plate 210 on the lower surface of the insulating plate 140. ) Is installed.

The cap plate 110 has a first terminal through-hole 111 connected to the first electrode tab 215 through the first electrode terminal 130 at a central portion thereof, and a first electrode in the first terminal through-hole 111. A tubular gasket 120 is installed to electrically insulate the terminal 130 and the cap plate 110.

In addition, an electrolyte injection hole 113 of a predetermined size is formed at one side of the cap plate 110. The electrolyte injection hole 113 is sealed by the stopper 115 when the cap assembly 100 is assembled to the upper opening 201 of the case 200 and the electrolyte is injected through the electrolyte injection hole 113.

The other side of the cap plate 110 is integrally provided with a protrusion 117 protruding upward to increase deformation strength such as torsion or bending by the molding resin injected between the protective circuit board 300 and the cap plate 110 to be described later. Is formed.

The insulating plate 140 is formed of an insulating material such as the gasket 120 and is coupled to the bottom surface of the cap plate 110. The insulating plate 140 is formed to correspond to and communicate with the first terminal through-hole 111 of the cap plate 110 is a second terminal through-hole 141 is formed.

The terminal plate 150 is formed of Ni metal or an alloy thereof, and is coupled to the lower surface of the insulating plate 140. The terminal plate 150 has a third terminal through hole 151 corresponding to the first terminal through hole 111 of the cap plate 110.

In addition, the insulating case 160 is installed on the upper side of the electrode assembly 250 to insulate the electrode assembly 250 and the cap plate 110, is a polymer resin having an insulating property, preferably made of polypropylene, In the embodiment of the present invention, the material is not limited.

On the other hand, the upper surface of the cap plate 110 may be connected to the protective circuit board 300 to be described later, a safety device such as stopping the operation when an abnormal state occurs in the secondary battery may be separately formed and installed.

The safety device 430 is a PTC (Positive Temperature Coefficient) element that can stop the charge and discharge current of the secondary battery when the temperature of the secondary battery exceeds a certain level to increase the electrical resistance to almost infinite, the pressure of the secondary battery increases Breaker (Current Breaker) for blocking the charging current by blocking the electrode lead wire using may be used.

First and second lead plates 410 and 420 which are electrically connected to the protection circuit board 300 are installed in the cap plate 110 serving as the anode and the electrode terminal 130 serving as the cathode.

That is, the protection circuit board 300 is provided with a circuit portion and connection terminals 360 and 370 on the back surface, that is, the inner surface where the external terminals 310 and 320 are formed. The connection terminals 360 and 370 are coupled to the first and second lead plates 410 and 420, and the first and second lead plates 410 and 420 may be made of nickel or a nickel alloy material as usual.

Here, the second lead plate 420 connecting the electrode terminal 130 having a polarity different from that of the cap plate 110 with the protection circuit board 300 may be formed of the insulating member 185 provided on the upper surface of the cap plate 110. It is installed on the upper surface.

At this time, the first lead plate 410 is welded on the upper side of the stopper 115 for sealing the electrolyte injection hole 112 to help seal the stopper, the second lead plate 410 by the fixing member 425 The upper surface of the insulating member 185 is fixed.

In addition, the second lead plate 420 has a short prevention portion. The short prevention part moves the second lead plate 420 little by little by the pressure injected when the molding resin is injected between the cap plate 110 and the protection circuit board 300 to be in contact with the mold frame for completing the bare cell. This is to prevent shorting. That is, the bare cell is inserted into the mold 500 (not shown), and then the molding resin is injected between the cap plate 110 and the protection circuit board 300 to remove the mold 500 when the molding resin is hardened. Is completed. In this case, since the first lead plate 410 is connected to the cap plate 110 and the case 200, which are anodes, the first lead plate 410 is not shorted even when the mold 200 is in contact with the case 200 and has the same polarity. . However, since the second lead plate 420 is connected to the electrode terminal 130 serving as a cathode and has a different polarity from the mold frame 500, the second lead plate 420 may be shorted when contacted.

As a result, as shown in FIG. 3A, the short prevention part may be a short prevention groove 421 formed so that an edge of the second lead plate 420 is recessed inward. That is, when the molding resin is injected into the mold frame 500 in the second lead plate 420 having the short prevention grooves 421, as shown in FIG. 3B, the second lead plate 420 is moved to the original state. Even if the seat is separated, the short prevention groove 421 is formed to be recessed inward, thereby preventing the second lead plate 420 and the mold frame 500 from contacting each other.

At this time, the short prevention groove 421 may be formed by the chamfer, the chamfer angle may be about 40 ~ 60 °. In addition, the chamfer width of the second lead plate 420 may be up to 10-20% of the entire width of the second lead plate 420. And, the short prevention groove 421 is formed to have a curve when formed to be recessed inwards to minimize the possibility of contact between the second lead plate 420 and the mold frame 500.

In the present invention, since the connection between the safety device and the lead plate is not clear, the connection relationship has not been described. Please explain the connection between the lead plate, safety device and protection circuit board, and the installation of the lead plate.

According to the present invention, the lead plate connecting the protective circuit board, the electrode terminal and the cap plate is formed to be recessed inward so that there is a possibility of contact with the mold frame for injecting molding resin when the lead plate is moved. There is an advantage to reduce.

In addition, since the lead plate is less likely to come into contact with the mold, there is an advantage of improving the productivity of the secondary battery.

Claims (9)

Bare cells; A protective circuit board connected to the bare cell; And And a lead plate connecting the bare cell and the protection circuit board and having a short prevention part. The method of claim 1, The short prevention part is a secondary battery, characterized in that the short prevention groove formed so that the corner portion of the lead plate recessed inward. The method of claim 2, The short prevention groove is a secondary battery, characterized in that formed by the chamfer. The method of claim 3, wherein The chamfering angle of the secondary battery, characterized in that about 40 ~ 60 °. The method of claim 3, wherein The chamfer width of the lead plate is a secondary battery, characterized in that 10 to 20% of the width of the lead plate. The method of claim 3, wherein The short prevention groove is a secondary battery, characterized in that formed in a curve. The method of claim 1, The bare cell is a case; An electrode assembly accommodated inside the case and having first and second electrode tabs drawn therethrough; And A secondary battery comprising a cap assembly sealing the case and including an electrode terminal and a cap plate connected to the first and second electrode tabs. The method of claim 7, wherein The case is a secondary battery characterized in that the square. The method of claim 8, The electrode terminal has a negative electrode polarity, characterized in that.

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