KR20070056428A - Secondary battery - Google Patents

Abstract

The secondary battery of the present invention is an electrode assembly; A can containing the electrode assembly; And a cap plate coupled to an open upper portion of the can, a pin portion penetrating upward through a terminal hole formed in the cap plate, and a bottom plate integrally formed with a lower plate of the pin portion. And an electrode tab drawn from one electrode of the electrode assembly is bonded to the bottom surface of the bottom plate of the electrode terminal. Therefore, the electrical resistance can be reduced by reducing the path of the current from the electrode tab to the electrode terminal.

Description

Secondary Battery {SECONDARY BATTERY}

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

FIG. 2 is a schematic front sectional view of the secondary battery shown in FIG. 1;

3 is a partially enlarged view of a cap assembly of a secondary battery illustrated in FIG. 2;

4 is a perspective view of an electrode terminal used in a secondary battery according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: secondary battery 11: can

12: electrode assembly 16: anode tab

17: negative electrode tab 100: cap assembly

110: cap plate 120: first insulating member

130: electrode terminal 132: pin portion

134: bottom plate 140: second insulating member

150: terminal plate

The present invention relates to a secondary battery, and more particularly, to a secondary battery having a structure for directly welding an electrode tab to an electrode terminal.

In general, a secondary battery refers to a battery that can be charged and discharged, unlike a primary battery that cannot be charged, and is widely used in the field of advanced electronic devices such as a cellular phone, a notebook computer, a camcorder, and the like. In particular, lithium secondary batteries have an operating voltage of 3.6V, which is three times higher than nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as electronic equipment power sources, and are rapidly increasing in terms of high energy density per unit weight.

Such lithium secondary batteries mainly use lithium-based oxides as positive electrode active materials and carbon materials as negative electrode active materials. Moreover, although lithium secondary batteries are manufactured in various shapes, typical shapes include cylindrical shape, square shape, and pouch type.

Among these, the rectangular secondary battery includes an electrode assembly, a can of a rectangular shape accommodating the electrode assembly, and a cap assembly coupled to the can.

In the electrode assembly, a positive electrode and a negative electrode and a separator interposed between these two electrodes are wound, and the positive and negative electrode tabs are drawn out from the positive and negative electrodes, respectively.

The can is a metal container having a substantially rectangular parallelepiped shape in a rectangular secondary battery, and is formed by a processing method such as deep drawing. It is therefore possible for the can itself to act as a terminal.

The cap assembly includes a cap plate coupled to an upper portion of the can, an electrode terminal provided through a terminal hole, and a gasket for insulating the cap plate on an outer surface thereof, an insulation plate installed on a lower surface of the cap plate, It is provided on the bottom surface of the insulating plate and comprises a terminal plate that is energized with the electrode terminal.

The negative electrode of the electrode assembly is electrically connected to the electrode terminal through the negative electrode tab and the terminal plate, and the positive electrode is electrically connected to the cap plate or the can through the positive electrode tab connected thereto. Of course, the polarity may be changed.

In order to manufacture such a cap assembly, the electrode terminal is inserted downward into the terminal through-hole formed in the cap plate and the hole formed in the insulating plate and the terminal plate, and then the end of the electrode terminal fitted to the terminal plate is rotated and pressed.

However, the conventional cap assembly has the following problems.

First, the lower end portion of the electrode terminal inserted into the hole formed in the terminal plate is compressed below the lower surface of the surrounding terminal plate, and it is difficult to directly weld or contact the electrode tab to the lower end portion of the electrode terminal.

Therefore, one side of the terminal plate needs to be extended for welding with the electrode tab. The one side and the opposite side of the terminal plate to be welded to the electrode tab around the electrode terminal has an electrode tab (anode tab) having a polarity opposite to the electrode tab (anode tab) need to contact the cap plate, so that the terminal plate It cannot be extended. As a result, asymmetrical terminal plates and insulating plates are used around the electrode terminals. Accordingly, even when there is a structure that fixes the left and right sides of the insulating plate when the electrode terminal is inserted and then rotated and crimped, there is a possibility of being rotated together due to a weak resistance to rotation, which may cause a short circuit between the cap plate and the terminal plate. .

In addition, since the electrode tab is not directly welded to the lower end of the electrode terminal is welded to one side of the terminal plate, there is a problem that the electrical resistance is increased because the path of the current generated in the battery unit is long.

The present invention is to solve this problem, by forming a wide plate-shaped bottom surface of the electrode terminal penetrating the cap plate by directly welding the electrode tab drawn from one electrode of the electrode assembly to the bottom surface of the electrode terminal, The purpose of the present invention is to provide a cap assembly symmetrical with respect to the electrode terminal and to reduce resistance by reducing a path of a current from the electrode tab to the electrode terminal.

In order to achieve this object, the secondary battery according to the present invention,

Electrode assembly; A can containing the electrode assembly; And a cap plate coupled to an open upper portion of the can, a pin portion penetrating upward through a terminal hole formed in the cap plate, and a bottom plate integrally formed with a lower plate of the pin portion. And an electrode tab drawn from one electrode of the electrode assembly is bonded to the bottom surface of the bottom plate of the electrode terminal.

Here, when the cap plate is a conductive material, a first insulating member may be positioned between the electrode terminal and the cap plate to insulate the two.

In addition, it may include a terminal plate coupled to the upper end of the electrode terminal. In this case, when the cap plate is a conductive material, a second insulating member may be positioned between the terminal plate and the cap plate to insulate the two.

In addition, the upper end portion of the pin portion is preferably located below the upper surface of the terminal plate or on the same plane so that the conductive plate can be welded to the upper surface of the terminal plate.

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

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

Referring to the drawings, the secondary battery includes an electrode assembly 12, a can 11 accommodating the electrode assembly 12, and a cap assembly 100 coupled to the can 11.

The electrode assembly 12 typically forms a wide plate shape of the positive electrode 13 and the negative electrode 15 to increase the capacitance, and then interposes a separator 14 between the positive electrode 13 and the negative electrode 15 to insulate them from each other. It is then laminated, rolled up into a vortex to form a so-called 'Jelly Roll'. The negative electrode 15 and the positive electrode 13 may be formed by coating carbon as the negative electrode active material and lithium cobalt as the positive electrode active material, respectively, on a current collector made of copper and aluminum foil. The separator 14 is made of polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene. Separator 14 is formed to be wider than the positive electrode 13 and the negative electrode 15 is advantageous to prevent short circuit between the electrode plates. In the electrode assembly 12, positive and negative electrode tabs 16 and 17 connected to each electrode are drawn out. Insulating tape 18 is wound around the positive and negative electrode tabs 16 and 17 to prevent a short circuit between the electrode plates 13 and 15 at the boundary portion drawn out of the electrode assembly 12.

The can 11 is a metal container having a substantially rectangular parallelepiped shape in a rectangular secondary battery as shown, and formed by a processing method such as deep drawing. It is therefore possible for the can itself to act as a terminal. As the material for forming the can, aluminum or aluminum alloy, which is a lightweight conductive metal, is preferable. The can 11 becomes a container of the electrode assembly 12 and the electrolyte solution, and the upper portion opened to the electrode assembly 12 is sealed by the cap assembly 100.

The cap assembly 100 may include a cap plate 110, a first insulating member 120, an electrode terminal 130, a second insulating member 140, and a terminal plate 150. This will be described later.

The negative electrode tab 17 drawn from the negative electrode 15 of the electrode assembly 12 may be directly bonded to the electrode terminal 130. In the case of the positive electrode 13 of the electrode assembly 12, the positive electrode tab 16 may be formed. The cap plate 110 may be welded to the can 11. An insulating case 190 may be further installed below the electrode terminal 130. On the other hand, the battery may be designed by changing the polarity.

An electrolyte injection hole 112 for injecting an electrolyte into the can 11 is formed at one side of the cap plate 110, and a sealing unit 160 for sealing the electrolyte injection hole 112 after electrolyte injection is provided. Is formed.

The structure of the cap assembly 100 is as follows.

2 is a schematic sectional front view of the secondary battery shown in FIG. 1, FIG. 3 is a partially enlarged view of a cap assembly of the secondary battery shown in FIG. 2, and FIG. 4 is used in the secondary battery according to an embodiment of the present invention. It is a perspective view of an electrode terminal.

3 and 4, the cap assembly 100 of the secondary battery according to an embodiment of the present invention includes a cap plate 110 coupled to an open upper portion of the can 11, and the cap plate 110. A conductive electrode terminal 130 including a pin portion 132 penetrating upward through the terminal through-hole formed in the) and a bottom plate 134 formed integrally with the lower end of the pin portion 132, one of the electrode assembly The electrode tab 17 drawn out from the electrode (eg, the cathode) is directly bonded to the bottom surface of the bottom plate 134 of the electrode terminal 130.

Here, the cap plate 110 may be made of an insulating material such as a synthetic resin. In this case, the electrode tab drawn from another electrode (eg, an anode) of the electrode assembly may be welded to the can to extract electricity generated from the battery unit to the outside. Can be.

Even if the cap plate 110 is made of an insulating material or a conductive material, if the cap plate 110 has the same polarity as that of the electrode terminal 130, the first and second insulating members shown by reference numerals 120 and 140 in FIG. 3 are unnecessary. . However, since the cap plate 110 and the can need to have different polarities, a separate insulating member is required between the cap plate and the can.

Typically, the cap plate 110 is made of a conductive material and the polarity of the cap plate 110 and the electrode terminal 130 is different, in this case between the electrode terminal 130 and the cap plate 110 as shown It is necessary to position the first insulating member 120 to insulate the two.

In addition, the terminal plate 150 coupled to the upper end of the electrode terminal 130 may be positioned on the cap plate 110.

When the cap plate 110 is made of a conductive material and the polarities of the cap plate 110 and the electrode terminal 130 are different, the insulating plate between the terminal plate 150 and the cap plate 110 is insulated. 2 The insulating member 140 needs to be located.

The first insulating member 120 may be formed to completely cover the upper surface of the bottom plate 134 of the electrode terminal 130 and the outer surface of the fin part 132. In this case, the second insulating member 140 may be formed so as to surround only the bottom surface of the terminal plate 150. Alternatively, the first insulating member 120 may be formed to surround only the top surface of the bottom plate 134 of the electrode terminal 130. In this case, the second insulating member 140 needs to be formed to surround the bottom surface of the terminal plate 150 and the outer surface of the pin portion 132 of the electrode terminal 130. However, the content of the present invention is not limited to the shapes of the first and second insulating members described above.

Looking at the assembly process of the cap assembly according to the invention briefly, the terminal terminal of the cap plate 110 and the second insulating member 140 while the electrode terminal 130 is located on the outer surface of the first insulating member 120 And an upper end of the electrode terminal 130 inserted into the hole formed in the terminal plate 150 and rotationally compressing the end (upper end) of the electrode terminal 130 penetrating the hole to couple the upper end of the electrode terminal 130 to the terminal plate 150. .

When rotating the end of the electrode terminal 130, the other parts of the cap assembly, for example, the insulating member (120, 140) or the terminal plate 150 also rotates together between the cap plate 110 and the electrode terminal 130 , Or there is a risk that a short circuit occurs between the cap plate 110 and the terminal plate 150.

In order to prevent this, a first mounting groove in which the bottom plate 134 of the electrode terminal 130 may be seated may be formed on the bottom surface of the first insulating member 120. In addition, a binding groove is formed on the bottom surface of the cap plate 110, and a protrusion 123 is formed on an upper surface of the first insulating member 120, and the binding groove and the protrusion 123 are coupled to prevent rotation. Can be. In addition, a second mounting groove may be formed on the upper surface of the second insulating member 140 on which the terminal plate 150 may be mounted.

In the conventional cap assembly structure, the electrode terminal is inserted downward, so that the head portion having a wide plate is positioned outside the battery. However, in the cap assembly structure according to the present invention, the electrode terminal 130 is inserted upward, and thus the wide bottom plate 134 is disposed. ) Can be located inside the battery.

Accordingly, as shown in FIG. 3, the electrode tab 17 drawn from one electrode (eg, the cathode) of the electrode assembly may be directly welded to the center portion of the bottom surface of the bottom plate 134 of the electrode terminal 130. Conventionally, a terminal plate is separately placed inside a battery and an electrode tab is welded to one side of the terminal plate. However, in the present invention, a separate terminal plate is not required inside the battery.

Accordingly, the cap assembly parts may be symmetrically assembled around the electrode terminal, such that the protrusions 123 formed on the left and right sides of the first insulating member 120 serve as a rotational resistance support when the electrode terminal ends are rotationally compressed. I can do it faithfully. In addition, the path of the electric current from the electrode tab 17 to the electrode terminal 130 is reduced, thereby reducing the resistance.

On the other hand, a third mounting groove may be formed on the upper surface of the terminal plate 150 may be the upper end of the pin portion 132 of the electrode terminal 130.

At this time, the upper end of the pin portion 132 is preferably located below the top surface of the terminal plate 150 or on the same plane. The upper end portion of the fin portion 132 formed by rotationally pressing the end of the pin portion 132 of the electrode terminal 130 is too small to be suitable for directly welding the conductive plate to the upper portion. Here, the conductive plate may be a terminal or a lead plate of a PTC element, a thermal breaker, or the like. By coupling the terminal plate 150 to the pin portion 132 of the electrode terminal 130, the conductive plate may be welded to the terminal plate 150, and the upper end of the pin portion 132 is connected to the terminal plate 150. The upper end of the pin portion 132 needs to be located below or on the same plane as the upper surface of the terminal plate 150 because it may interfere with welding between the terminal plate 150 and the conductive plate if protruded upward. .

In the secondary battery according to the present invention, the bottom surface of the electrode terminal penetrating the cap plate is formed in a wide plate shape to directly weld the electrode tab drawn from one electrode of the electrode assembly to the bottom surface of the electrode terminal. By reducing the path of the current to the electrode terminal it is possible to reduce the electrical resistance. In addition, since a symmetrical terminal plate and an insulating member can be obtained, the resistance against rotation of the structure that fixes both sides of the insulating member increases when the electrode terminals are rotated and crimped, so that the insulating member cannot be rotated together. It is possible to prevent a short circuit between the electrode terminal or the terminal plate.

Although the present invention has been described with reference to the illustrated embodiments, it is merely exemplary, and the present invention may encompass various modifications and equivalent other embodiments that can be made by those skilled in the art. Will understand.

Claims (9)

Electrode assembly; A can containing the electrode assembly; And Cap assembly having a cap plate coupled to the open top of the can, a pin portion penetrating upward through the terminal through-hole formed in the cap plate and a bottom plate formed integrally with the lower end of the pin portion Including; And a electrode tab drawn from one electrode of the electrode assembly is bonded to a bottom surface of the bottom plate of the electrode terminal. The method of claim 1, When the cap plate is a conductive material, the secondary battery, characterized in that the first insulating member is insulated between the electrode terminal and the cap plate. The method of claim 2, Secondary battery, characterized in that the bottom surface of the first insulating member is formed with a first mounting groove for mounting the bottom plate of the electrode terminal. The method of claim 2, A binding groove is formed on a bottom surface of the cap plate, and a protrusion is formed on an upper surface of the first insulating member, and the binding groove and the protrusion are coupled to each other. The method of claim 1, A secondary battery comprising a terminal plate coupled to the upper end of the electrode terminal. The method of claim 5, And the cap plate is a conductive material, wherein a second insulating member is disposed between the terminal plate and the cap plate to insulate the cap plate. The method of claim 6, Secondary battery, characterized in that the second mounting groove is formed on the upper surface of the second insulating member is seated on the terminal plate. The method of claim 5, Secondary battery, characterized in that the upper surface of the terminal plate is formed with a third mounting groove that can be mounted on the upper end of the pin portion of the electrode terminal. The method of claim 8, Secondary battery, characterized in that the upper end of the pin portion is located below the upper surface of the terminal plate or on the same plane so that the conductive plate can be welded to the upper surface of the terminal plate.

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