KR20090026643A - Cap assembly and secondary battery using the same - Google Patents

Abstract

A cap assembly is provided to improve the binding strength of a resin molding part formed between a cap plate of a cap assembly and a protection circuit part by comprising a subsidiary material between a gasket and an electerode terminal. A cap assembly(300) includes an insulating gasket(360), a terminal plate(330), an insulating plate(340), a cap plate(350), and an electrode terminal(310). A connection plate is equipped between the insulating gasket and the electrode terminal. A secondary battery comprises an electrode assembly(100) consisting of a positive electrode plate(110), a negative electrode plate(120) and a separator(130); a can(200) accommodating the electrode assembly and forming an opening at one end; a cap assembly including a cap plate and a connection plate; a protection circuit part(400) electrically connected to the electrode terminal and the cap plate; and a resin molding part formed between the protection circuit part and the cap assembly.

Description

Cap assembly and secondary battery having the same {Cap assembly and secondary battery using the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery, and more particularly, to a cap assembly including an auxiliary portion between a gasket and a negative electrode terminal to improve a bonding force of a resin molding formed between a cap plate and a protection circuit portion of a cap assembly, and a secondary battery having the same. .

The demand for the development of secondary batteries capable of high capacity, high output, and long-term operation that can be charged and discharged is rapidly increasing with the proliferation of electronic devices, portable computers, portable telephones, PDAs, and the like. As the computer industry develops rapidly, secondary batteries are also becoming thinner and smaller in accordance with the trend of high performance, high stability, and simplification and portability of precision electrical and electronic products.

A battery basically refers to a device that converts chemical energy of a material into electrical energy through an electrochemical reaction. In addition, the secondary battery is a term for a rechargeable battery whose energy conversion can be reversibly, that is, a battery can be recharged after one use (discharge) and continue to be used.

In particular, the lithium secondary battery has an operating voltage of 3.6V and three times better than conventional batteries such as nickel cadmium battery, nickel hydrogen battery, nickel zinc battery and the like, and has excellent energy density characteristics per unit weight. It is increasing rapidly.

A lithium secondary battery is classified into a lithium metal battery using a liquid electrolyte, a lithium ion battery, and a lithium polymer battery using a polymer solid electrolyte according to the type of electrolyte.

Lithium polymer batteries are classified into fully solid lithium polymer batteries containing no organic electrolyte at all and lithium ion polymer batteries using a gel polymer electrolyte containing organic electrolyte according to the type of polymer solid electrolyte.

The lithium secondary battery includes a cathode current collector to which the positive electrode activating material is applied, a negative electrode current collector to which the negative electrode activating material is applied, and an electrode assembly to which the separator interposed therebetween is stacked and wound to accommodate an electrode assembly.

Lithium oxide is used as a positive electrode activation material, and a carbon material is generally used as a negative electrode activation material.

Lithium secondary batteries are divided into cans and pouches according to the shape of the case in which the electrode assembly is accommodated, and the cans may be divided into squares and cylinders.

On the other hand, when the lithium secondary battery is charged to 4.5V or more, the electrolyte inside the battery is decomposed to form gas, which leads to an unstable state. The gas formed increases the internal pressure of the cell, which may involve leakage of the electrolyte. In addition, when the battery is discharged below a certain voltage, copper, which is the current collector of the negative electrode, begins to dissolve into the electrolyte, thereby degrading the performance of the battery.

Therefore, in order to solve such a problem, the lithium secondary battery has a protection circuit for securing safety and reliability by preventing safety accidents caused by overcharge, overdischarge, overcurrent, and the like.

Referring to the conventional secondary battery illustrated in FIG. 1, the secondary battery includes a can 10, an electrode assembly 20 accommodated inside the can 10, and a cap assembly 30 coupled to the can 10. do.

The can 10 is a rectangular case of a hollow metal material, and the electrode assembly 20 is a jelly-roll type in which the positive electrode plate 21, the separator 23, and the negative electrode plate 25 are jelly-roll type. The positive lead 27 and the negative lead 29 are drawn out from the positive electrode plate 21 and the negative electrode plate 25, respectively.

The cap assembly 30 may include a cap plate 31 coupled to an upper portion of the can 10, a negative terminal 33 inserted into the cap plate 31 through a gasket 32, and a cap plate 31. It includes an insulating plate 34 provided on the lower surface, the terminal plate 35 is provided on the lower surface of the insulating plate 34 and is energized with the negative electrode terminal 33.

In addition, the cap plate 31 is provided with an electrolyte injection hole 31a that provides a passage through which the electrolyte is injected into the can 10, and an injection hole stopper 160 is sealed to couple the electrolyte injection hole 111. .

The positive lead 27 is directly connected to the lower surface of the cap plate 31, and the negative lead 29 is electrically connected to the negative terminal 33 through the terminal plate 35.

The can 10 is positioned above the electrode assembly 20, and an insulation case 37 is installed to insulate the electrode assembly 20 from the cap assembly 30, and the cathode lead is provided on the insulation case 37. A lead hole 37a through which the 29 is drawn out and an electrolyte inlet 137b through which the electrolyte flows are formed.

In the secondary battery having the above structure, the electrode assembly 20 is inserted into the can 10, and the insulating case 37 is seated on the upper end of the electrode assembly 20. The positive lead 27 and the negative lead 29 drawn from the electrode assembly 20 are welded to the lower surface of the cap plate 31 of the cap assembly 30 and the negative electrode terminal 33, respectively. Next, the cap assembly 30 is seam-welded to the can 10, the electrolyte is injected through the electrolyte inlet 31a, and the electrolyte inlet 31a is sealed with the inlet stopper 31b. do.

The secondary battery is generally connected to the protective circuit unit to form a battery pack, and the cap plate and the negative terminal are electrically connected to the positive lead plate and the negative lead plate, which are part of the protective circuit unit, respectively.

In this case, if the protection circuit part is not fixed, there is a risk of short circuit, so that the resin is melted and then hardened to a part of the cap assembly and the periphery of the protection circuit part to fix and insulate the cap assembly part and the protection circuit part. After the resin is hardened, a resin molding part is formed, and the resin molding part is strongly bound to the upper surface of the cap plate so that a short circuit problem and a product assembly error do not occur.

However, the cap plate or the lead plate in contact with the resin molding part is made of a metal and has a different material from that of the resin molding part.

In order to solve the above problems, the present invention provides a cap assembly including an insulation case, a terminal plate, an insulation plate, a cap plate, an insulation gasket, and an electrode terminal, wherein a coupling plate is provided between the insulation gasket and the electrode terminal. It is done.

In the secondary battery of the present invention for solving the above problems, the secondary battery of the present invention comprises an electrode assembly consisting of a positive electrode plate, a negative electrode plate and a separator, a can accommodating the electrode assembly and forming an opening at one end thereof, and a cap plate covering the opening of the can. And a cap assembly having a coupling plate interposed between the insulating gasket and the electrode terminal, a protective circuit portion electrically connected to the electrode terminal and the cap plate, and a resin molding portion formed between the protective circuit portion and the cap assembly. It is characterized by.

Therefore, as described above, by providing an auxiliary material between the electrode terminal forming the cap assembly and the insulating gasket, it is possible to improve the bonding strength of the resin molding formed between the cap plate and the protective circuit portion of the cap assembly.

Details of the object and the technical configuration of the present invention and the resulting effects will be more clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention. In addition, in the drawings, the length, thickness, etc. of the layer and the region may be processed and expressed for convenience.

2 is an exploded perspective view of a rechargeable battery according to a first exemplary embodiment of the present invention, and FIG. 3 is a cross-sectional view illustrating a combined form of the rechargeable battery of FIG. 2.

Referring to FIGS. 2 and 3, a secondary battery includes an electrode assembly 100 formed by stacking a positive electrode plate having a positive electrode tab, a negative electrode plate having a negative electrode tab, and a cerapater and winding the electrode assembly 100. Can 200 for receiving and forming an opening at one end, the cap assembly 300 serves to seal the opening of the can and electrically connected to the positive and negative electrode tabs of the electrode assembly 100, for a safety device on a printed board. It is composed of a protective circuit portion 400 having an electronic circuit and an electrical terminal electrically connected to the cap assembly and a resin molding portion 500 for coupling a portion of the cap assembly and a portion of the protective circuit portion to the molten resin.

The electrode assembly 100 is interposed between the positive electrode plate 110 formed by applying the positive electrode active material to the positive electrode current collector, the negative electrode plate 120 formed by applying the negative electrode active material to the negative electrode current collector, the positive electrode plate 110 and the negative electrode plate 120. Separator 130, which prevents a short circuit between the two pole plates (110, 120) and allows the movement of ions, a positive electrode tab 140, which is bonded to the positive electrode plate 110 and electrically connected to the cap plate, to the negative electrode plate 120 It is composed of a negative electrode tab 150 is bonded and electrically connected to the electrode terminal.

The positive electrode plate 110 is formed by applying a positive electrode active material to the positive electrode current collector and the positive electrode current collector. The positive electrode active material may be formed of a layered compound including lithium, a binder to improve bonding strength, and a conductive material to improve conductivity. As the positive electrode current collector, aluminum is generally used, and the positive electrode current collector serves as a movement path of charge generated from the positive electrode active material and serves to support the positive electrode active material. One end of the positive electrode plate 110 is formed with a positive electrode non-coating portion is not coated with a positive electrode active material. The positive electrode tab 140 is bonded to the positive electrode non-coating portion.

The negative electrode plate 110 includes a negative electrode current collector and a negative electrode active material applied to the negative electrode current collector. As the negative electrode active material, hard carbon containing graphite, graphite, or the like may be used, and the negative electrode active material may be formed of a binder to improve the bonding force between the negative electrode active materials. As the negative electrode current collector, copper is generally used, and the negative electrode current collector serves as a movement path of charge generated in the negative electrode active material and serves to support the negative electrode active material. One end of the negative electrode plate 120 is formed with a negative electrode non-coating portion is not coated with the negative electrode active material. The negative electrode tab 150 is bonded to the negative electrode uncoated portion.

The separator 130 is interposed between the positive electrode plate 110 and the negative electrode plate 120 to insulate the two plates 110 and 120 and to move lithium ions. In general, the separator 130 may be formed of a polyolefin-based polymer film such as polyethylene (PE), polypropylene (PP), or a multilayer thereof, but the material is not limited thereto. In addition, it may include an electrolyte and may be in a liquid or gel form.

The can 200 may be formed of a metal material having an upper end opening, and accommodates the electrode assembly 100, and accommodates an insulation case inside the opening. In addition, when the separator 130 of the electrode assembly 100 does not include an electrolyte, the electrolyte may be accommodated together with the electrode assembly 100 in the can 200. As the metal material, the can 200 may serve as a terminal by being formed of a material such as light and ductile aluminum, aluminum alloy, or stainless steel.

The shape of the can 200 may be rectangular or oval with rounded corners, and the opening of the can 200 may be sealed by melting or heat fusion with the cap plate. At this time, an insulating case for insulating the positive electrode tab 140 and the negative electrode tab 150 while protruding to the outside is mounted inside the can 200.

The cap assembly 300 includes an electrode terminal 310 for electrically connecting the negative electrode tab 150 of the electrode assembly 100 and the negative electrode lead plate 420, and the can 200 containing the electrode assembly 100. Insulation case 320 seated on the inside of the opening, the terminal plate 330 which is seated on one surface of the insulating case 320 and made of a conductive material to form an electrical path, and insulate the outer surface of the terminal plate 330 and the electrode terminal An insulating plate 340 having a hole for connecting the 310 to the terminal plate 330, a cap plate 350 having an electrolyte injection hole and an electrode terminal hole, and covering an opening of the can 200, and an electrode terminal 310. An insulating gasket 360 coupled to the electrode terminal hole of the cap plate 350 and a hole into which the electrode terminal 310 can be inserted, and an upper surface of the insulating gasket 360 and an electrode terminal ( Coupling plate 370 and cap formed wider than 310 Composed of the electrolyte injection hole stopper 380 sealing the electrolyte injection hole of a rate (350).

The electrode terminal 310 is formed of a body and an upper end having a somewhat larger area than the body, the body through the holes of the coupling plate 370, insulating gasket 360, cap plate 350, insulating plate 340 The upper end portion which is connected to the terminal plate 330 and protrudes outside is connected to the negative electrode lead plate 420 to form an electrical passage from the negative electrode tab 150 of the electrode assembly 100 to the protection circuit portion.

 The insulating case 320 is seated inside the durable portion of the can 200 and covers the top surface of the electrode assembly 100 of the can 200. The insulating case 320 forms a wall around the terminal plate 330 to allow the insulating plate 340 to cover the terminal plate 330. The insulating case 320 is spaced apart from the positive electrode tab and the negative electrode tab by a predetermined distance to prevent a short, and forms a groove protruding the positive electrode tab and the negative electrode tab.

The terminal plate 330 is connected to the electrode terminal 310 through a hole and at the same time the negative electrode tab 150 is connected to the lower surface, the insulating plate 340 is formed in a form surrounding the terminal plate 330, An electrode terminal hole into which the electrode terminal 310 interposed with the insulating gasket 370 may be inserted is formed.

The cap plate 350 is formed to cover the opening of the can 200, and an electrode terminal hole is formed to allow a body portion of the electrode terminal 310 through which the insulating gasket 360 is interposed to pass. An electrolyte injection hole may be formed at one end of the cap plate 350 to inject the electrolyte, and a vent may be formed to prevent an explosion when the internal pressure rises due to the overload of the electrode assembly 100.

The insulating gasket 360 has a hole formed at a center thereof to cover the electrode terminal 310. When the coupling plate 370 is formed of a conductive material, the cap plate 350 and the coupling plate 370 are insulated from each other. Let's do it. The insulating gasket 360 forms a wider upper end portion rather broadly than the portion inserted into the hole of the cap plate 350.

The coupling plate 370 is an auxiliary material interposed between the electrode terminal 310 and the insulating gasket 360. The coupling plate 370 forms a hole into which the electrode terminal 310 can be inserted, and covers an entire area of the insulating gasket 360. And wider than the electrode terminal 310.

Since the coupling plate 370 is wider than the insulating gasket 360, a space that does not contact the insulating gasket 360 is formed on the outer side of the lower surface of the coupling plate 370, and the cap plate 350 and the protection circuit part 400 are formed. When the molding part is formed of a resin, the resin is also filled in the space.

Therefore, since the coupling plate 370 serves to hold the resin molding part, the resin molding part in which the protection circuit part 400 is molded is increased in strength to be attached to the cap plate 350.

The coupling plate 370 may be conductive to insulating material. FIG. 2, which is an embodiment of the present invention, illustrates a case in which the coupling plate 370 is formed of an insulating material. However, the coupling plate 370 is formed of a conductive material to form a PTC on the coupling plate 370. Alternatively, the coupling plate 370 material may be formed using a PTC material.

Although the shape of the coupling plate 370 is a rectangular flat plate in the present embodiment, a model such as a circle, an ellipse, or a polygon may be a shape to achieve the object of the present invention for firmly attaching the resin molding.

In addition, various modifications of the coupling plate 370 are possible, such as having a plurality of grooves at the bottom of the coupling plate 370 filled with resin.

The protection circuit unit 400 is located on the upper side of the cap assembly 300 and has a circuit for blocking charging and discharging when abnormal operation occurs by checking the state of overcharge, overdischarge, overcurrent, etc. of the secondary battery. Provides stability and reliability of secondary batteries.

The protection circuit unit 400 includes a protection circuit board 410 including a circuit for managing all operations of the secondary battery, a positive lead plate 420, and a cathode for connecting the cap assembly 300 to the protection circuit board 410. The lead plate 430, the protection circuit board 410 is formed of a positive electrode terminal 440 and a negative electrode terminal 450 protruding.

The protection circuit board 410 is formed by mounting a plurality of electrical elements on a printed circuit board on which a wiring pattern is formed, and a positive terminal 440 and a negative terminal 450 are formed on one surface thereof to form a positive lead plate and a negative lead plate ( 420 and 430, respectively, to be electrically formed with the cap assembly 300. In addition, a terminal portion for connecting to an external device is formed on one surface opposite to the surface on which the positive and negative terminals 440 and 450 are formed.

The positive lead plate 420 is connected to the cap plate 350 on one side thereof and the positive electrode terminal 420 to one side thereof, and the negative lead plate 430 is connected to the electrode terminal 310 one side thereof and the negative terminal ( 450 is connected to the cap assembly 300 and the protection circuit unit 400 is electrically connected. In this case, an insulator is formed between the negative lead plate 430 and the cap plate 350 to insulate the negative lead plate 430 and the cap plate 350.

Secondary protection devices may be formed on the negative lead plate 430 and the protection circuit board 410, and a positive temperature protection (PTC) device, a bimetal or a thermal fuse may be used as the second protection device. When the PTC element is used, it should not be shorted to the cap plate 350.

The resin molding part 500 includes the protection circuit part 400 including all of the positive lead plate and the negative lead plate 420 and 430, the positive electrode terminal and the negative electrode terminal 440 and 450, so that only a part of the external connection terminal part protrudes. The cap assembly 300 is formed by molding a portion of the upper surface of the cap plate 350 on which the electrode terminal 310 is formed.

At this time, since the coupling plate 370 is formed to be wider than the insulating gasket 360, a space that does not come into contact with the insulating gasket 360 is formed outside the lower surface of the coupling plate 370, so that the resin is filled in the space. do.

Therefore, since the coupling plate 370 serves to hold the resin molding part, the resin molding part in which the protection circuit part 400 is molded is increased in strength to be attached to the cap plate 350.

Referring to Figure 4 showing a cross-sectional view of a portion of the cap assembly of the second embodiment of the present invention, a step is formed in the coupling plate (370 ') to improve the bonding force.

The coupling plate 370 ′ interposed between the electrode terminal 310 and the insulating gasket 360 is formed to be wider than the insulating gasket 360, and a portion of the coupling plate 370 ′, that is, an insulating gasket provided at a lower portion thereof. By forming the step 372 at the edge of the portion not in contact with the 360, the resin molding part may be attached to the cap plate 350 with a stronger bonding force. In this example, the step is formed in a right-angled step, but the step may be formed in multiple steps, and the shape may be variously modified.

Referring to Fig. 5A, which shows a cross-sectional view of a part of the cap assembly of the third embodiment of the present invention, the coupling plate 370 " is formed with a groove for increasing the bonding force with the resin molding portion.

The coupling plate 370 ″ interposed between the electrode terminal 310 and the insulating gasket 360 has a diameter larger than that of the insulating gasket 360, and is provided at a portion of the coupling plate 370 ″, that is, the insulation provided at the bottom thereof. By forming the groove 374 in the portion not in contact with the gasket 360, the bonding force between the resin molding portion and the cap plate can be improved.

5B and 5C showing cross-sectional views when the coupling plate 370 ″ is in the form of a disc, the coupling plate 370 ″ of FIG. 5B forms a central hole that serves as a passage for the electrode terminal at the center thereof. A ring-shaped groove 374 having an outer circumference and an outer circumference is formed in the coupling plate 370 ″, and the coupling plate 370 ″ in FIG. The plurality of grooves 374 may be provided to have a shape that is formed to the edge in the center of the coupling plate 370 ", or to be formed to elongate in the arc direction.

The shape and number of grooves 374 formed in the coupling plate 370 ″ are not limited to this example, and various modifications may be made by those skilled in the art.

The present invention shows a preferred embodiment as described above, but is not limited to the above-described embodiment and various modifications made by those skilled in the art to which the present invention pertains without departing from the spirit of the present invention. Modifications and variations are possible.

1 is a cross-sectional view of a conventional secondary battery.

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

3 is a cross-sectional view illustrating a coupling state of the rechargeable battery of FIG. 2.

4 is a cross-sectional view of a portion of a cap assembly with a coupling plate forming a step according to a second embodiment of the present invention.

FIG. 5A is a cross-sectional view of a portion of a cap assembly having a coupling plate with a groove formed in accordance with a third embodiment of the present invention. FIG.

5B and 5C are plan views showing examples of the coupling plate of FIG. 5A.

[Description of Major Reference Code]

100 electrode assembly 110 positive electrode plate

120: negative electrode plate 130: separator

140: positive electrode tab 150: negative electrode tab

200: can 300: cap assembly

310: electrode terminal 320: insulated case

330: terminal plate 340: insulation plate

350: cap plate 360: insulated gasket

370, 370 ′, 370 ″: mating plate

372: step 374: groove

380: electrolyte injection hole cap 400: protection circuit

410: protection circuit board 420: anode lead plate

430: negative electrode lead plate 440: positive terminal

450: negative terminal

Claims (12)

A cap assembly comprising an insulating case, a terminal plate, an insulating plate, a cap plate, an insulating gasket, and an electrode terminal, And a coupling plate between the insulating gasket and the electrode terminal. The method of claim 1, And the coupling plate forms a hole into which the electrode terminal can be inserted. The method of claim 2, And the coupling plate is formed to have a larger cross-sectional area than the insulating gasket and the electrode terminal. The method of claim 3, wherein The coupling plate cap assembly, characterized in that forming a step or a multi-step in the edge of the lower surface. The method of claim 3, wherein Cap assembly, characterized in that the coupling plate has one or a plurality of grooves in the lower surface. The method of claim 5, wherein The groove of the cap assembly is characterized in that the elongated form along the edge at the center, or along the arc. An electrode assembly comprising a positive electrode plate, a negative electrode plate, and a separator; A can receiving the electrode assembly and forming an opening at one end thereof; A cap assembly having a cap plate covering the opening of the can and a coupling plate interposed between the insulating gasket and the electrode terminal; A protection circuit part electrically connected to the electrode terminal and the cap plate; And And a resin molding part formed between the protection circuit part and the cap assembly. The method of claim 7, wherein The cap assembly further comprises an insulating case, a terminal plate and an insulating plate. The method of claim 7, wherein The coupling plate is a secondary battery, characterized in that formed wider than the cross-sectional area of the electrode terminal and the insulating gasket. The method of claim 9, The coupling plate is a secondary battery, characterized in that forming a step of one or multi-stage at the edge of the lower surface. The method of claim 9, The coupling plate has a secondary battery, characterized in that provided with one or a plurality of grooves on the lower surface. The method of claim 11, The groove is a secondary battery characterized in that it is formed long in the center or the edge along the arc.

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