KR20080036742A - Rechargeable battery - Google Patents

Abstract

A secondary battery is provided to increase the shear force generated in case of twisting, thereby improving the durability of a secondary battery. A secondary battery comprises a cap plate(50) which seals the open upper end of a can; and a lead plate(70) which is combined with the cap plate, wherein the cap plate is provided with a resistance reinforcing unit(80) for the binding of the lead plate. Preferably the resistance reinforcing unit is formed on the surface of the cap plate, comprises the groove where the lead plate is accommodated, and has the shape corresponding to the lower surface shape of the lead plate.

Description

Secondary Battery {RECHARGEABLE BATTERY}

1 is a longitudinal cross-sectional view of a secondary battery according to an embodiment of the present invention.

Figure 2 is a perspective view of one coupling of the cap plate and the lead plate according to an embodiment of the present invention.

Figure 3a is a partial longitudinal cross-sectional view of an embodiment of a cap plate formed with a resistance strengthening means according to the present invention.

Figure 3b is a partial longitudinal cross-sectional view of another embodiment of a cap plate formed with a resistance strengthening means according to 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

60: Bear cell 70: Lead plate

71: module connection plate 73: cell connection plate

80: resistance strengthening means, recess 81: convex portion

The present invention relates to a secondary battery, and more particularly to a secondary battery with improved durability.

In general, a secondary battery is a battery that can be repeatedly used when recharged, unlike a disposable battery, and is mainly used as a main power source for mobile devices for communication, information processing, and audio / video. The main reason for the recent interest in secondary batteries and the rapid development thereof is that secondary batteries are power sources having ultra-light weight, high energy density, high output voltage, low self discharge rate, environmental friendliness, and long lifespan.

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 connected to safety devices such as PTC (Positive Temperature Coefficient) elements, thermal fuses and protection circuit boards and other battery components, or using hot melt resin. To form a finished appearance through the mold.

Positive / cathode terminals formed on the protective 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 has one surface attached to the cap plate and the other surface attached to the anode 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 a poor mechanical strength or a 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. One side of the lead plate is attached to the cap plate by welding, but the durability is weak. It may be detached from the cap plate by the impact. 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 has been made in order to solve the above-mentioned conventional problems, it is an object of the present invention to minimize the positional shift of the lead plate on the cap plate during welding, and to provide a secondary battery with improved durability when twisting after welding.

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

Still another object of the present invention is to provide a secondary battery which can be easily aligned by welding the lead plate on the cap plate.

In the secondary battery according to the present invention for achieving the above object comprises a cap plate for sealing the open top of the can and a lead plate coupled to the cap plate, the cap plate is the lead plate It characterized in that the resistance strengthening means for coupling is formed.

In addition, the resistance reinforcing means may be formed on the surface of the cap plate may be made of a groove in which the lead plate is seated.

In addition, the resistance enhancing means may be formed of at least one.

In addition, the resistance enhancing means may be formed in a shape corresponding to the bottom shape of the lead plate.

In addition, the resistance reinforcing means may be made of a square groove.

In addition, the resistance reinforcing means may be formed at the same time when forming the cap plate.

The resistance reinforcing means may include a concave portion formed on an upper surface of the cap plate by press compression from an upper portion of the cap plate to a lower portion, and a convex portion formed on a lower surface of the cap plate positioned below the concave portion.

In addition, the lead plate seated on the resistance reinforcing means may be coupled to the cap plate and the laser welding.

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

A preferred embodiment of a secondary battery according to an embodiment of the present invention, as shown in Figure 1, the bare cell 60, the protection circuit module (not shown), the Bessel 60 and the protection circuit module ( It is configured to include a lead plate 70 for electrically connecting.

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 in a jelly roll shape by stacking and winding 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. 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 an electrode may be disposed at a boundary at which the electrode tabs 17 and 19 are drawn out from the electrode assembly 10. Insulating tape may be wound around each of the tabs 17 and 19 to prevent a short circuit between the two electrode plates 11 and 15.

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 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 through hole 31 is formed in the center portion of the insulating case 30 to allow the negative electrode tab 19 to pass therethrough, and an electrolyte passage hole 33 is formed in the side portion thereof.

The can 20 has a substantially rectangular parallelepiped shape and is formed of aluminum or an aluminum alloy. 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 in the center of the cap plate 50, and a tube shape is formed between the electrode terminal 41 and the cap plate 50 penetrating through the terminal through hole 51. The gasket 43 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. A positive electrode tab 17 drawn from the positive electrode plate 11 is welded to the lower surface of the cap plate 50, and a negative electrode tab 19 drawn from the negative electrode plate 15 is zigzag at the lower end of the electrode terminal 41. It is welded with a bend. 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.

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.

In addition, the cap plate 50 has a safety band 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 module (not shown) is provided with a protection circuit for blocking battery overcharge or overdischarge to improve the stability 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 protection circuit module (not shown) may be fixed to the bare cell 60 by a hot melting resin or the like in connection with the bare cell 60.

The lead plate 70 is an L-shaped module connecting plate 71 electrically connected to a protection circuit module (not shown), and a cell connecting plate 73 electrically connected to the cap plate 50. 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 module (not shown).

The cap plate 50 to facilitate alignment of the lead plate 70 on the cap plate 50, to minimize the positional shift of the lead plate 70, and to improve the durability of the secondary battery during the twist test ) Is formed to strengthen the resistance means for coupling the lead plate (70).

The resistance reinforcing means 80 is formed on the surface of the cap plate 50 and consists of a groove in which the lead plate 70 is seated. Specifically, the resistance reinforcing means 80 corresponds to the shape of the cell connecting plate 73 which is the bottom shape of the lead plate 70 so that the lead plate 70 is seated on the upper surface of the cap plate 50. It is made of a groove of the shape. At this time, the resistance reinforcement means 70 is formed on at least one or more on the cap plate 50, the cell connecting plate 73 of the lead plate 70 is the resistance reinforcement means of the cap plate 50 ( 80) and mounted by welding.

The lead plate 70 seated on the resistance reinforcement means 80 is minimized because the side wall of the resistance reinforcement means 80 acts as a stopper during welding, and the position distortion phenomenon is minimized. The lead plate 70 is prevented from escaping out of the bare cell 60 during the twist action.

As shown in FIG. 2, the resistance reinforcing means 80 may be formed in a rectangular groove in the same shape as that of the cell connecting plate 73 so that the cell connecting plate 73 of the lead plate 70 is seated. Do. On the other hand, the groove shape of the resistance reinforcing means 80 may be formed in various ways depending on the shape of the cell connecting plate 73.

As shown in FIG. 3A, the resistance reinforcing means 80 may be formed at the same time as the concave portion 80 may be formed at the time of forming the cap plate 50. Also, as shown in FIG. 3B, the cap plate 50 may be formed. 50 can be formed by press compression from top to bottom. That is, the upper surface of the cap plate 50 is formed with a recess 80 on which the lead plate 70 is seated, that is, the resistance reinforcing means 80 is formed, and the lower surface of the cap plate positioned below the recess is convex. The part 81 may be formed.

The lead plate 70 is inserted into the resistance reinforcement means 80 so that the side surfaces of the lead plate 70 are joined to the inner surface of the resistance reinforcement means 80, and then welded to each other to be firmly fixed. At this time, the lead plate 70 and the resistance strengthening means 80 is 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.

In order to perform the function of the secondary battery, the lead plate 70 is connected to the cap plate 50 and the protection circuit module (not shown) provided in the bare cell 60, respectively, to the bare cell 60 and the protection circuit module. Electrically connect (not shown).

First, as shown in Figure 1, the lead plate 70 is composed of a module connecting plate 71 and a cell connecting plate 73 bent at an angle, preferably 90 °, the module connecting plate 71 is electrically connected to the positive terminal or the negative terminal of the protective circuit module (not shown), and the cell connecting plate 73 is electrically connected to the resistance reinforcing means 80 formed on the cap plate.

The resistance reinforcing means 80 is formed as a square groove so that the cell connecting plate 73 of the rectangular shape is seated. At this time, when the cell connecting plate 73 is formed in a circular shape, an ellipse shape or a polygonal shape, the resistance reinforcing means 80 is, of course, to be formed as a circle groove, an elliptical groove or a polygonal groove.

The resistance reinforcing means 80 is formed on at least one upper surface of the cap plate 50 is seated on the lead plate 70. Therefore, the lead plate 70 is easily aligned on the cap plate 50, and then, the lead plate 70 is coupled to the cap plate 50 by irradiating a laser beam. On the other hand, the position shift phenomenon of the lead plate 70 caused by the external force transmitted to the welding site is minimized by the joining structure of the resistance enhancing means 80 and the lead plate 70, by the joining structure of the secondary battery Durability is improved.

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, according to the present invention, the shear stress generated at the time of twisting by the resistance strengthening means is increased, thereby improving durability of the secondary battery.

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

Another effect of the present invention is that the lead plate can be easily aligned and welded on the cap plate.

Claims (8)

In the secondary battery comprising a cap plate for sealing the open top of the can and a lead plate coupled to the cap plate, Secondary battery, characterized in that the cap plate is formed with resistance strengthening means for coupling the lead plate. The method of claim 1, The resistance reinforcing means is formed on the surface of the cap plate, the secondary battery, characterized in that consisting of a groove on which the lead plate is seated. The method according to claim 1 or 2, Secondary battery, characterized in that formed by at least one resistance enhancing means. The method of claim 3, wherein The resistance reinforcing means is a secondary battery, characterized in that formed in a shape corresponding to the bottom shape of the lead plate. The method of claim 4, wherein The resistance reinforcing means is a secondary battery, characterized in that consisting of a square groove. The method according to claim 1 or 2, The resistance reinforcing means is a secondary battery, characterized in that formed at the same time when forming the cap plate. The method according to claim 1 or 2, The resistance reinforcing means is a secondary portion characterized in that the concave portion formed on the upper surface of the cap plate by pressing the pressing from the cap plate to the lower portion, and the convex portion formed on the lower surface of the cap plate located below the concave portion battery. The method according to claim 1 or 2, The secondary battery seated on the resistance reinforcing means is coupled to the cap plate by laser welding.

Images