KR100795681B1 - Secondary battery - Google Patents

Abstract

The secondary battery of the present invention includes a cap assembly having an electrode assembly, a conductive can containing the electrode assembly, and a conductive cap plate coupled to an open upper portion of the can, and at any one electrode of the electrode assembly. The drawn electrode tab penetrates through the tab hole formed in the cap plate, and an insulating member is interposed between the cap plate and the electrode tab.

Accordingly, by providing a structure in which electrode tabs drawn from one electrode of an electrode assembly inside a metal can can be directly connected to a terminal outside the can, the space inside the can is reduced, process time and cost are reduced, and the structure is improved. Simplification can reduce the number of parts.

Description

Secondary Battery {SECONDARY BATTERY}

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

Figure 2a is a front sectional view of a secondary battery according to an embodiment of the present invention,

2B is a plan view of the secondary battery of FIG. 2A;

3 is a front sectional view of a secondary battery according to another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: secondary battery 11: can

12, 12 ': electrode assembly 16, 16': positive electrode tab

17, 17 ': negative electrode tabs 27, 26', 27 ': first insulating member

100, 100 ': cap assembly 111: tap through

110, 110 ': Cap plate 127, 117', 127 ': Second insulating member

190: insulation case 300, 300 ': protective circuit board

The present invention relates to a secondary battery, and more particularly, to a secondary battery having a structure in which an electrode tab drawn from an electrode of an electrode assembly inside a metal can is directly connected to a terminal outside the can.

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. In addition, although lithium secondary batteries are manufactured in various shapes, typical shapes include cylindrical, square, and pouch types.

Among these, the rectangular secondary battery includes an electrode assembly, a can containing 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. As a material of the can, aluminum or an aluminum alloy, which is a lightweight conductive metal, may be used. The can becomes a container of the electrode assembly and the electrolyte solution, and the upper part opened to insert the electrode assembly is sealed by the cap assembly.

The cap assembly is formed of a metal 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 the outer surface thereof, and an insulating plate installed on the lower surface of the cap plate. And a terminal plate provided on the lower surface of the insulating plate and energizing the electrode terminal. The lower portion of the terminal plate is provided with an insulating case for insulation between the terminal plate and the electrode assembly.

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. Of course, it is also possible to design by changing the polarity.

The secondary battery having the above structure is also called a bare cell, and the bare cell is a safety device such as a PTC (positive temperature coefficient) device, a thermal fuse, a protective circuit board (PCB), and the like. It is stored in a separate hard pack while being connected to other battery parts, or forms a finished appearance through a mold using a hot melt resin.

However, there is a continuing need to develop a battery having a larger battery capacity and a smaller volume than the existing product or the same volume as a conventional product according to the demand for lighter weight and higher capacity of the secondary battery.

However, in the conventional secondary battery, a considerable portion of empty space and various components are required to connect the electrode tab drawn from one electrode of the electrode assembly to a terminal outside the can.

In particular, the negative electrode tab may be connected to a terminal external to the can through the terminal plate and the electrode terminal. The negative electrode tab is welded to the terminal plate has a sand shape or Z-shape, which is inevitable because the cap assembly is welded to the can after the negative electrode tab is welded to the terminal plate. Such a dead or z-shape will result in significant void space.

In addition, since the terminal plate and the cap plate have different polarities, an insulating plate must be placed between the two parts. In addition, an insulating case is required between the terminal plate and the electrode assembly to insulate the two.

Such empty spaces and various components may be inevitable for safety and defect avoidance of the existing battery, but may be considered unnecessary space in view of battery capacity.

The present invention is to solve this problem, by providing a structure in which the electrode tab drawn from one electrode of the electrode assembly inside the metal can is directly connected to the terminal outside the can, reducing the consumption of space in the can, process The goal is to reduce time and cost, and to simplify the structure to reduce the number of parts.

Secondary battery according to the present invention for achieving this object,

A cap assembly having an electrode assembly, a conductive can containing the electrode assembly, and a conductive cap plate coupled to an open upper portion of the can,

The electrode tab drawn from any one electrode of the electrode assembly penetrates through the tab hole formed in the cap plate, and an insulating member is interposed between the cap plate and the electrode tab.

Here, the electrode tab drawn from one electrode of the electrode assembly penetrates through the tab through hole, and the electrode tab drawn from the other electrode may be bonded to the bottom surface or can of the cap plate.

Alternatively, both electrode tabs drawn from the two electrodes of the electrode assembly may pass through the two tab holes formed in the cap plate, respectively.

In this case, the electrode tab penetrating the tab hole may be electrically connected to the connection terminal of the protective circuit board.

The insulating member may include a first insulating member surrounding at least a portion of the electrode tabs passing through the tab through hole, and a second insulating member surrounding a sidewall of at least the tab hole among the cap plates.

In this case, the first insulating member and the second insulating member may be sealed by heat fusion or adhesive.

In addition, an insulating case may be installed between the electrode assembly and the cap plate to insulate the two.

The insulating member is selected from polypropylene (PP), tedra fluoroethylene-perfluoro alkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), and tedra fluoroethylene-hexafluoropropylene copolymer (FEP). It may be made of a material which is either one or a combination thereof.

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. An 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 part opened to the electrode assembly 12 is sealed by the cap assembly 100.

The cap assembly 100 includes a conductive cap plate 110 and an insulating member 127. In addition, an insulating case 190 may be installed between the cap plate 110 and the electrode assembly 12 to insulate the two.

A vent (not shown) may be formed at one side of the cap plate 110. The vent is first broken when the internal pressure of the battery increases due to overcharging, etc., thereby ensuring the safety of the battery by releasing the internal gas. Do it.

An electrolyte injection hole 112 for injecting an electrolyte into the can 11 is formed at the other 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.

1 and 2A and 2B, a secondary battery according to an embodiment of the present invention may include any one of the positive and negative electrode tabs 16 and 17 of the electrode assembly 12, for example, a negative electrode tab ( 17 penetrates through the tab hole 111 formed in the cap plate 110, and an insulating member is interposed between the cap plate 110 and the negative electrode tab 17 drawn out.

More specifically, the negative electrode tab 17 of the electrode assembly 12 penetrates through the tab through hole 111, and the positive electrode tab 16 is welded to the lower surface of the cap plate 110. The positive electrode tab 16 may be welded to the can 11. An insulating case may be located between the cap plate 110 and the electrode assembly 12, but this is omitted in FIG. 2A.

Compared with the internal structure of the conventional secondary battery, the secondary battery according to the exemplary embodiment of the present invention does not require the electrode terminal, the insulation plate, and the terminal plate of the conventional secondary battery. Accordingly, the process of welding the electrode tab to the terminal plate is also unnecessary, and the process of inserting the electrode terminal into a hole formed in the cap plate, the insulating plate, and the terminal plate to assemble the cap assembly, and then rotationally crimping (spinning) the end thereof It is unnecessary and there is no need to consider a separate configuration for preventing a short circuit caused by rotating the parts of the cap assembly together during spinning. In addition, according to the present invention, the electrode tab can be straightly extended in a straight line so as not to occupy unnecessary space inside the battery.

Although not shown, the negative electrode tab 17 penetrating through the tab hole 111 may be electrically connected to a connection terminal of a protective circuit board (not shown).

The structure or method of sealing between the conductive cap plate 110 and the negative electrode tab 17 simultaneously with insulation will be described.

The insulating member that insulates between the cap plate 110 and the negative electrode tab 17 includes a first insulating member 27 surrounding the portion passing through the tab through hole 111 of the negative electrode tab 17, and a cap plate ( And a second insulating member 127 surrounding at least one sidewall of the tab through hole 111.

The first and second insulating members 27 and 127 may be made of polypropylene (PP), tedra fluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tedra fluoroethylene- It may be made of a material which is any one selected from hexafluoropropylene copolymer (FEP) or a combination thereof.

The first insulating member 27 may seal and insulate between the negative electrode tab 17 and the first insulating member 27 by taping the negative electrode tab 17 with the above-described material.

The second insulating member 127 is formed slightly larger than the tab through hole 111 to be inserted into the tab through hole 111 using the elasticity of the material to seal and insulate the cap plate 110 and the second insulating member 127 from each other. You can.

As shown in FIG. 1, the shape of the second insulating member 127 is in contact with the body portion fitted into the tab through hole 111 and the upper surface of the cap plate 110 at the outer periphery of the tab through hole 111. It may be made of wealth. Alternatively, as shown in FIG. 2A, the body portion fitted into the tab through hole, the head portion in close contact with the upper surface of the cap plate 110 at the outer periphery of the tap through inlet side, and the cap plate 110 around the outer periphery of the tab through hole are provided. It may be made of a bottom in close contact with the lower surface. However, the content of the present invention is not limited to the above shape.

The first insulating member 27 and the second insulating member 127 may be hermetically sealed using elasticity of the material, but may be heat-sealed between the first insulating member 27 and the second insulating member 127, or Or it is preferable to seal using an adhesive or the like.

Meanwhile, referring to FIG. 3, in the secondary battery according to another embodiment of the present invention, both of the electrode tabs 16 ′ and 17 ′ drawn from the two electrodes of the electrode assembly 12 ′ may be attached to the cap plate 110 ′. It penetrates each of the two formed tab holes. An insulating case may be located between the cap plate 110 ′ and the electrode assembly 12 ′, but this is omitted in FIG. 3. Hereinafter, only differences from the embodiment shown in FIGS. 2A and 2B will be described.

The first insulating members 26 'and 27' enclose portions of the electrode tabs 16 'and 17' passing through the respective tab holes, and the second insulating members 117 'and 127' are sidewalls of the respective tab holes. Wrapping.

The first insulating members 26 'and 27' and the second insulating members 117 'and 127' may be sealed by heat fusion or by using an adhesive or the like.

The electrode tabs 16 ′ and 17 ′ may be directly welded to two connection terminals 316 ′ and 317 ′ of the protection circuit board 300 ′ as shown in the figure, and other elements such as a PTC element or a thermal fuse may be illustrated. It may be joined with the terminals of the safety device.

The secondary battery according to the present invention provides a structure in which an electrode tab drawn from one electrode of an electrode assembly inside a metal can can be directly connected to a terminal outside the can, thereby reducing consumption of space in the can, and a process time and cost. The number of parts can be reduced by reducing the number of parts and simplifying the structure.

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 (8)

In the secondary battery comprising a cap assembly having an electrode assembly, a conductive can for receiving the electrode assembly, and a conductive cap plate coupled to an open upper portion of the can, An electrode tab drawn from any one electrode of the electrode assembly penetrates through a tab through hole formed in the cap plate, and an insulating member is interposed between the cap plate and the electrode tab. The insulating member may include a first insulating member covering at least a portion of the electrode tabs passing through the tab through hole, and a second insulating member covering a sidewall of at least the tab hole among the cap plates. . The method of claim 1, The electrode tab drawn from one electrode of the electrode assembly penetrates through the tab through hole, and the electrode tab drawn from the other electrode is bonded to the bottom surface or can of the cap plate. The method of claim 1, Both electrode tabs drawn from the two electrodes of the electrode assembly, respectively, characterized in that penetrates through the two tab holes formed in the cap plate. The method of claim 2 or 3, And the electrode tab penetrating the tab hole is electrically connected to a connection terminal of the protective circuit board. delete The method of claim 1, The secondary battery, characterized in that the sealing between the first insulating member and the second insulating member by heat sealing or adhesive. The method of claim 1, Secondary battery, characterized in that the insulating case is installed between the electrode assembly and the cap plate to insulate the two. The method of claim 1, The insulating member is selected from polypropylene (PP), tedra fluoroethylene-perfluoro alkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), and tedra fluoroethylene-hexafluoropropylene copolymer (FEP). Secondary battery, characterized in that made of a material of any one or a combination thereof.

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