KR20080048853A - Rechargeable battery - Google Patents

Abstract

A secondary battery is provided to minimize the twisting of a lead plate on a cap plate in case of welding and to prevent a protection circuit board from separated from a bare cell by external impact or twisting. A secondary battery comprises a protection circuit board; a bare cell provided with a cap plate(50); and a lead plate which electrically connects the protection circuit board and the bare cell, wherein the cap plate and the lead plate are connected by a fixing unit. Preferably the fixing unit comprises a projected part(59) formed at the upper surface of the cap plate and a connecting part(75) formed at the lower surface of the lead plate, wherein the projected part is inserted into the connecting part.

Description

Secondary Battery {RECHARGEABLE BATTERY}

1 is a longitudinal sectional view of a secondary battery according to the present invention;

Figure 2a is a partial perspective view of an embodiment of a cap plate formed with protrusions according to the present invention.

Figure 2b is a partial perspective view of another embodiment of a cap plate formed with protrusions according to the present invention.

Figure 3a is a partial longitudinal cross-sectional view of one embodiment of a cap plate formed with protrusions according to the present invention.

Figure 3b is a partial longitudinal cross-sectional view of another embodiment of a cap plate formed with a protrusion according to the present invention.

Figure 4a is an embodiment of a lead plate formed with a joint according to the present invention.

Figure 4b is another embodiment of the lead plate formed joints according to the present invention.

5 is a perspective view of the cap plate and the lead plate in accordance with the present invention.

<Description of the symbols for the main parts of the drawings>

10: electrode assembly 11: anode plate

13: Separator 15: negative electrode plate

17: positive electrode tab 19: negative electrode tab

20: Can 30: Insulation case

31: Lead through 33: Electrolyte passed through

40: cap assembly 41: electrode terminal

43: gasket 45: insulation plate

47: Terminal plate 50: Cap plate

51: terminal hole 53: electrolyte inlet

55: Stopper 57: Safety band

59: protrusion 59a: recess

59b: Convex part 60: Bear cell

70: lead plate 71: circuit connection board

73: cell connection plate 75: joint

80: laser beam

The present invention relates to a secondary battery, and more particularly to a secondary battery characterized in that the cap plate and the lead plate of the bare cell is connected by a fixing means.

In general, secondary batteries, unlike disposable batteries, are batteries that can be repeatedly used when they are charged. They are mainly used as main power sources for communication, information processing, and audio / video portable devices. The main reason for the recent interest in secondary batteries and rapid development is that secondary batteries are ultralight, high energy density, high output voltage, low self-discharge rate, environmentally friendly battery and long life.

Secondary batteries are divided into nickel-hydrogen (Ni-MH) batteries and lithium-ion (Li-ion) batteries according to electrode active materials. Lithium-ion batteries, in particular, use a liquid electrolyte or a solid polymer electrolyte or gel depending on the type of electrolyte. It can be divided into the case of using the electrolyte of the phase. In addition, according to the shape of the container in which the electrode assembly is accommodated are divided into various types such as can type and pouch type.

Lithium-ion batteries have a much higher energy density per weight than disposable batteries, making it possible to realize ultralight batteries. The average voltage per cell is 3.6V, which is three times the compact effect of 1.2V of other rechargeable batteries such as Ni-Cd batteries or nickel-metal hydride batteries. There is. In addition, the lithium ion battery has a self-discharge rate of less than 5% per month at 20 ° C, which is about one third of that of a nickel-cadmium battery or nickel-metal hydride battery, and is environmentally friendly by not using heavy metals such as cadmium (Cd) or mercury (Hg). In addition, there is an advantage that can be charged and discharged 1000 times or more in a normal state. Therefore, on the basis of these advantages, with the recent development of information and communication technology, the development is rapidly made.

In the conventional secondary battery, an electrode assembly including a positive electrode plate, a negative electrode plate, and a separator is accommodated in a can made of aluminum or an aluminum alloy, the top opening of the can is closed with a cap assembly, and then the bare cell is injected and sealed into the can. To form. When the can is formed of aluminum or an aluminum alloy as described above, the light weight of the aluminum may be reduced, and the battery may not be corroded even when used for a long time under high voltage.

The sealed unit bare cell is housed in a separate hard pack in connection with safety devices such as PTC (Thermal Temperature Coefficient), Thermal Fuse and Protective Circuit Module (PCM) and other battery accessories. Or by using a hot melt resin to form a finished appearance through the mold.

Meanwhile, the positive / negative terminals of the protection circuit board are electrically connected to the bare cell through a separate lead plate. That is, the cap plate provided in the bare cell and the positive terminal of the protective circuit board are connected by the positive lead plate, and the negative terminal of the bare cell and the negative terminal of the protective circuit board are connected by the negative electrode lead plate.

The anode lead plate is mainly composed of a 'b' shape, one side is attached to the cap plate and the other side is attached to the positive terminal of the protective circuit board. The protective circuit board is electrically connected to the bare cell and then fixed to the bare cell by hot melting resin.

On the other hand, the cap plate and the lead plate are generally joined by welding, and since the lead plates aligned on the cap plate before welding are easily distracted in spite of a small external force, the manufacturer has made great efforts to rearrange the lead plates. There is a problem that is consumed and cost.

In addition, during welding, a charging phenomenon and an electric shock are generated by laser beam irradiation, and an external force is transmitted to the welding portion, thereby causing a distortion of the lead plate. If the cap plate and the lead plate are not welded properly, the lead plate may not function properly, resulting in poor mechanical strength or poor electrical connection to the finished secondary battery.

In addition, when the hot-melting resin portion is warped or impacted from the outside after welding, the force is transmitted to the lead plate, but one side of the lead plate is attached to the cap plate by welding, but by external impact It may be detached from the cap plate. Therefore, when the welding part is detached, the lead plate and the cap plate may be electrically connected only by contact. In this case, the contact resistance between the lead plate and the cap plate may increase, and a lot of heat may be generated. In addition, when the lead plate is completely separated from the cap plate, the electric circuit is disconnected, and thus a secondary battery may not be used anymore. .

The present invention devised to solve such a conventional problem, an object of the present invention is to provide a secondary battery that can be easily welded by aligning the lead plate on the cap plate when welding the cap plate and the lead plate. .

Another object of the present invention is to provide a secondary battery capable of minimizing the positional shift of the lead plate on the cap plate during welding.

It is still another object of the present invention to provide a secondary battery which is advantageous in terms of twist strength of a battery pack due to a large shear stress generated during twisting after welding.

Still another object of the present invention is to provide a secondary battery in which a phenomenon in which the protective circuit board is separated from the bare cell by an external impact or a torsional force is prevented.

In order to achieve the above object, a secondary battery according to the present invention includes a protective circuit board, a bare plate provided with a cap plate, and a lead plate configured to electrically connect the protective circuit board and the bare cell. In this case, the cap plate and the lead plate is characterized in that connected by the fixing means.

In addition, the fixing means may be formed of a protrusion formed on the upper surface of the cap plate, the joint portion is formed on the lower surface of the lead plate is inserted into the protrusion.

In addition, the protrusion and the joint may be formed in at least one or more.

In addition, the protrusion and the joint may have a circular cross section or a polygon.

In addition, the protrusion may be integrally formed when the cap plate is formed.

In addition, the protrusion may be formed by press compression from the lower surface of the cap plate to the upper surface may be formed in the concave portion and the convex portion at the bottom.

In addition, the joint may be formed as a hole through which the protrusion passes.

In addition, the protrusion and the joint may be coupled by laser welding.

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

A preferred embodiment of the secondary battery according to the present invention, as shown in Figure 1, the bare cell 60, the protection circuit board (not shown), the Bessel 60 and the protection circuit board (not shown) Lead plate 70 for electrically connecting is included.

The bare cell 60 includes an electrode assembly 10, a can 20 in which the electrode assembly 10 is accommodated, and a cap assembly 40 sealing an upper end of the can 20. .

The electrode assembly 10 is formed by winding or stacking a laminate of a positive electrode plate 11 formed in a thin plate shape or a film shape, and a separator 13 and a negative electrode plate 15.

The positive electrode tab 17 is electrically connected to an area of the positive electrode current collector in which the positive electrode active material layer is not formed, and the negative electrode tab is formed in the area of the negative electrode current collector in which the negative electrode active material layer is not formed in the negative electrode plate 15. 19 is electrically connected. In this case, the positive electrode plate 11 and the negative electrode plate 15 and the electrode tabs 17 and 19 may be arranged with different polarities, and a boundary portion from which the electrode tabs 17 and 19 are drawn out from the electrode assembly 10. Insulation tapes may be wound on the tabs 17 and 19 to prevent a short circuit between the two electrode plates 11 and 15, respectively.

In addition, it is advantageous to form the separator 13 in a wider width than the positive electrode plate 11 and the negative electrode plate 15 to prevent a short circuit between the electrode plates.

Meanwhile, an insulating case 30 may be installed on the upper surface of the electrode assembly 10 to cover the electrical insulation between the electrode assembly 10 and the cap assembly 40 and to cover the upper end of the electrode assembly 10. , The insulating case 30 is made of a polymer resin having insulation. In addition, a lead cylinder hole 31 is formed in the center portion of the insulating case 30 so that the negative electrode tab 19 can pass therethrough, and an electrolyte passage hole 33 is formed at the other side.

The can 20 is formed of aluminum or an aluminum alloy having a substantially rectangular parallelepiped shape. The electrode assembly 10 is accommodated through the open top of the can 20 so that the can 20 serves as a container for the electrode assembly 10 and the electrolyte. The can 20 may itself play a terminal role.

The cap assembly 40 is provided with a flat cap plate 50 having a size and shape corresponding to the open top of the can 20. In this case, a terminal through hole 51 is formed at the center of the cap plate 50, and a tube-shaped gasket 43 is formed between the electrode terminal 41 and the cap plate 50 penetrating through the terminal through hole 51. ) Is installed. The insulating plate 45 is disposed on the lower surface of the cap plate 50, and the terminal plate 47 is provided on the lower surface of the insulating plate 45. In addition, the bottom portion of the electrode terminal 41 is electrically connected to the terminal plate 47. The positive electrode tab 17 drawn from the positive electrode plate 11 is welded to the lower surface of the cap plate 50, and the negative electrode tab 19 drawn from the negative electrode plate 15 is zigzag bent at the lower end of the electrode terminal 41. Welded with

The cap plate 50 has an electrolyte injection hole 53 formed at one side thereof, and a cap 55 is installed to seal the electrolyte injection hole 53 after the electrolyte is injected. The stopper 55 is a ball-shaped base material formed of aluminum or an aluminum-containing metal, and is placed on the electrolyte injection hole 53 and mechanically press-fitted into the electrolyte injection hole 53. In addition, the stopper 55 is welded to the cap plate 50 around the electrolyte inlet 53 for sealing.

On the other hand, the cap assembly 40 is coupled to the can 20 by welding the peripheral portion of the cap plate 50 to the side wall of the can 20 opening.

In addition, the cap plate 50 has a safety vent 57 is formed on the other side. The safety vent 57 is damaged when the pressure inside the battery rises above a predetermined pressure, thereby preventing ignition and explosion of the battery.

The protection circuit board (not shown) is provided with a protection circuit for blocking the battery overcharge or over-discharge to improve the safety of the battery, the positive terminal and the negative terminal is formed.

The positive electrode terminal is electrically connected to the cap plate 50 through the positive electrode lead plate 70. In addition, the negative electrode terminal is electrically connected to the electrode terminal 41 through a negative electrode lead plate (not shown). The protective circuit board (not shown) may be fixed to the bare cell 60 by a hot melting resin or the like.

The lead plate 70 includes a circuit connecting plate 71 electrically connected to a protective circuit board (not shown) and a cell connecting plate 73 electrically connected to a cap plate 50 in a '-' shape. Is formed. In this case, the lead plate 70 is formed of nickel or a nickel alloy, or stainless steel plated with nickel.

Meanwhile, the cap plate 50 and the lead plate 70 are coupled to electrically connect the bare cell 60 and the protection circuit board (not shown).

The cap plate 50 and the lead plate 70 by the fixing means to facilitate the alignment of the lead plate 70 on the cap plate 50, and to minimize the positional shift of the lead plate 70 Connected.

The fixing means includes a protrusion 59 formed on an upper surface of the cap plate 50 and a lower portion of the lead plate 70, that is, a joint 75 formed on the cell connecting plate 73. At this time, the joint portion 75 is preferably formed in a shape complementary to the protrusion portion 59 so that the protrusion portion 59 is inserted.

As illustrated in FIGS. 2A and 2B, at least one protrusion 59 may be formed on the cap plate 50 in a column shape to be coupled to the joint 75. In addition, it is a matter of course that the cross section may be formed in a circular shape or an elliptical shape or a polygonal shape.

In addition, the protrusion 59 is preferably formed integrally at the time of forming the cap plate 50. In this case, the thickness of the protrusion 59 is formed thicker than other portions of the cap plate 50, as shown in Figure 3a. In addition, the protrusion 59 may be formed by pressing by pressing, as shown in FIG. 3B. That is, the protruding portion 59 exerts a force from the lower surface of the cap plate 50 to the upper surface direction, so that the concave portion 59a is formed on the lower surface of the cap plate 50, and the convex portion 59b is formed on the upper surface. At this time, the thickness of the protrusion 59 is formed the same or similar to the thickness of the other portion of the cap plate 50.

The joint portion 75 is preferably formed as a hole (hole) so that the protrusion portion 59 penetrates, it is made of a shape equivalent to the protrusion portion 59 so as to complementary to the cross section of the protrusion portion (59). desirable. That is, the joint portion 75 may be formed in a circular shape or an elliptic shape or a polygonal shape, as shown in FIGS. 4A and 4B along the cross section of the protrusion 59.

The protrusions 59 are inserted into the joints 75 so that the side surfaces of the protrusions 59 are joined to the inner surface of the joints 75 and then welded to each other to be firmly fixed. In this case, the protrusion 59 and the joint 75 are preferably welded by laser beam irradiation.

Next, the operation of the secondary battery according to the present invention configured as described above will be described.

The bare plate 60 and the protection circuit board (not shown) are electrically connected to the cap plate provided with the lead plate 70 in the bare cell 60 to perform a function of a secondary battery that supplies power to an external device. Electrically connected to 50 and the protection circuit board (not shown), respectively.

First, as shown in FIG. 5, the lead plate 70 is composed of a circuit connecting plate 71 and a cell connecting plate 73 bent at a predetermined angle, preferably 90 °. 71 is electrically connected to the positive terminal or the negative terminal of the protective circuit board (not shown).

In addition, the cell connecting plate 73 is formed with a hole-shaped joint 75 having a through-hole. At this time, the joint portion 75 is preferably formed of at least one or more.

The joint portion 75 is formed to have a shape complementary to the shape of the protrusion 59 so that the protrusion 59 formed in the cap plate 50 is inserted. Therefore, when the protrusion 59 is formed of a cylinder, an elliptic cylinder, or a polygonal pillar, the joint portion 75 should be formed in a circular, elliptical or polygonal cross section correspondingly.

The protrusion 59 is formed on at least one upper surface of the cap plate 50 is inserted into the joint portion 75. Therefore, the lead plate 70 is easily aligned on the cap plate 50, and then irradiates the laser beam 80 to couple the protrusion 59 inserted into the joint portion 75. On the other hand, the position shift phenomenon of the lead plate 70 generated by the external force transmitted to the welding portion is minimized by the mating structure of the protrusion and the joint.

The present invention is not limited to the technical spirit of the specific embodiments or drawings described above, and those skilled in the art without departing from the gist of the invention claimed in the claims Various modifications are possible, of course, and such changes are within the scope of the claims of the present invention.

As described above, the present invention has a structure in which the joint of the lead plate and the protrusion of the cap plate are naturally fastened so that when welding the cap plate and the lead plate, the lead plate can be easily aligned on the cap plate and easily welded. It can be effective.

Another effect of the present invention is to minimize the displacement of the lead plate on the cap plate during welding.

Another effect of the present invention is that the shear stress generated at the time of twist after welding is advantageous in terms of the twist strength of the battery pack.

Another effect of the present invention is that the protection circuit board from being separated from the bare cell by an external impact or twisting force is prevented.

Claims (9)

A secondary battery comprising a protective circuit board, a bare cell provided with a cap plate, and a lead plate electrically connecting the protective circuit board and the bare cell, The cap plate and the lead plate is characterized in that the secondary battery is connected by a fixing means. The method of claim 1, The fixing means, A secondary battery comprising a protrusion formed on an upper surface of the cap plate and a joint portion formed on a lower surface of the lead plate and into which the protrusion is inserted. The method of claim 2, Secondary battery, characterized in that formed in at least one protrusion and the joint. The method of claim 2 or 3, Secondary battery, characterized in that the protrusion and the joint portion is formed in a circular cross-section. The method of claim 2 or 3, The protrusion and the joint portion of the secondary battery, characterized in that the cross section is formed in a polygon. The method of claim 2 or 3, The protrusion may be integrally formed when the cap plate is formed. The method of claim 2 or 3, The protruding portion is formed by press compression from the lower surface of the cap plate to the upper surface to form a concave portion and a convex portion at the bottom thereof. The method of claim 2 or 3, The joint part is a secondary battery, characterized in that formed by a hole (hole) through which the projecting portion passes. The method of claim 2 or 3, The protrusion and the joint portion are secondary batteries, characterized in that coupled to the laser welding.

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