KR20060011046A - Cap assembly, secondary battery and module thereof - Google Patents

Abstract

The present invention relates to a secondary battery having improved safety, comprising: an electrode group formed by winding a positive electrode plate and a negative electrode plate centered on a horizontal crimp with a separator interposed therebetween; A case accommodating the electrode group in a state in which the horizontal crimp is parallel; And a cap assembly having a vent portion having a notch that is electrically connected to the electrode group while being sealed to the case and having a negative electrode terminal, and which is broken at a constant pressure.

Secondary Battery, Photo Etch, Etch, Vent, V-shape

Description

CAP ASSEMBLY, SECONDARY BATTERY AND MODULE THEREOF}

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

2 is an exploded perspective view of an electrode group according to an embodiment of the present invention.

3 is a perspective view showing the shape of a rectangular electrode group according to an embodiment of the present invention.

4 is an exploded perspective view of a cap assembly according to an embodiment of the present invention.

5 is a cross-sectional view showing the shape of the notch formed in the vent member.

6 is a schematic diagram illustrating a process of forming a vent by a photolithography process.

The present invention relates to a secondary battery, and more particularly to a secondary battery having improved safety.

In view of its use and battery capacity, a secondary battery is a low-capacity secondary battery (hereinafter, referred to as a "small battery") that uses one or several battery cells, and a motor for driving a pack unit using dozens of battery cells. It can be classified into a large capacity secondary battery (hereinafter referred to as a 'large battery').

Dual batteries are primarily used as power sources for small electronic devices such as cellular phones, notebook computers, and camcorders. Large batteries are used in places such as HEVs (hybrid cars), electric vehicles (EVs), cordless cleaners, electric bicycles, and electric scooters. It is used as a power source for driving a motor.

When a small battery is configured as one cell, it is mainly formed to have a cylindrical or rectangular outer shape, and is wound around a vortex through a separator, which is an insulator, between the two bands and the negative electrode plate to form an electrode group. The battery is inserted into a cylindrical can.

The positive and negative plates each have a conductive tab attached to each of the lead terminals, that is, currents generated from the positive and negative plates when the battery is in operation, and the conductive tabs are attached to the electrode assembly by welding or the like. The current generated in the positive and negative plates respectively is induced to the positive and negative terminals.

When the structure of the small battery configured as described above is applied to a large battery as it is, it does not satisfy the operation characteristics of the large battery in terms of capacity and output, and thus a multi-tap structure in which a plurality of tabs are attached and used between electrode assemblies has been proposed. Furthermore, a secondary battery using a plate on a plate as a tab has been proposed.

On the other hand, the secondary battery is configured to further include a vent (or 'safe side') for preventing the explosion of the battery. The event operates under a predetermined pressure to prevent the battery from exploding.                         

However, the vent used in the square battery has a disadvantage that its cross section is relatively smaller than the cylindrical shape, so that the break pressure at which the vent bursts is high.

In addition, the vent is manufactured in a thin sheet form, but if the vent is manufactured in this way, there is a problem in that the break pressure of the vent is different from each other in the battery under a predetermined pressure. Accordingly, there is a difficulty in securing the stability of the secondary battery.

Accordingly, the present invention is to provide a secondary battery having a vent that operates constantly at low pressure to improve the above problems.

Another object of the present invention is to provide a secondary battery having a vent that operates constantly at a low pressure even in a vent of a rectangular battery having a relatively smaller area than a cylindrical battery.

In order to achieve the above object, the secondary battery provided by the present invention,

An electrode group formed by winding a pole plate composed of a positive electrode plate and a negative electrode plate with a separator interposed therebetween;

A case accommodating the electrode group in a state in which the horizontal crimp is parallel; And,

And a cap assembly having a vent part having a notch broken at a predetermined pressure and provided with a positive and negative electrode terminal electrically connected to the electrode group while sealing the case.                     

In the present invention, the vent part,

Vent holes; And,

It may be formed, including; a vent member of a thin plate formed notch exposed to the vent hole while blocking the vent hole.

In this case, the vent member and the cap assembly are preferably formed of the same material.

In the present invention, the vent member is preferably fixed by welding to the vent member so that the notch faces the inside of the can.

In addition, it is preferable that the cross-sectional shape of the notch is formed as a closed V-shaped closed loop through a photolithography process.

In addition, the cap assembly for a secondary battery provided by the present invention,

In the cap assembly provided with the electrode terminal while sealing the can containing the electrode group,

Vent holes; and,

And a vent part formed of a thin plate vent member having a notch exposed to the vent hole while blocking the vent hole.

And, the battery module provided in the present invention,

In the battery module consisting of a pack unit by connecting a plurality of secondary batteries to each other,

Each secondary battery constituting the battery module includes a vent hole; and a vent member of a thin plate positioned to expose the notch to the vent hole while blocking the vent hole.

The secondary battery provided in this embodiment is preferably composed of a battery module configured in a pack unit by connecting a plurality of secondary batteries to each other. In this case, the plurality of secondary batteries connected to each other are packaged in a housing in a state connected to a battery management system (BMS) that controls and manages operation and temperature.

In addition, the secondary battery (or the battery module) of the present invention is a device that operates by using a motor such as a HEV (hybrid car), an EV (electric vehicle), a wireless cleaner, an electric bicycle, an electric scooter, and the like. Can be used as an energy source for driving

Hereinafter, with reference to the accompanying drawings will be described in the embodiment of the present invention a cylindrical secondary battery consisting of a lead tab with a plate on a plate. However, the present invention may be implemented in various forms in addition to the embodiments described below.

1 is a perspective view illustrating a rechargeable battery according to an exemplary embodiment of the present invention. Referring to this, the secondary battery of the present invention will be described.

The secondary battery of the present embodiment has an electrode assembly formed by winding a positive electrode plate 23 and a negative electrode plate 22 in a case 11 having a cylindrical or hexahedral shape and partly open with a separator 21 interposed therebetween. 20 is inserted, and the open part of the case 11 is sealed with the cap assembly 30.

First, the case 11 is made of a conductive metal material such as aluminum, an aluminum alloy, or nickel plated steel, and the shape of the case 11 is preferably a hexahedral shape having an opening in which the electrode assembly 20 can be inserted and seated. However, the present invention is not limited thereto.

Next, the electrode assembly 20 is formed into a rectangular shape by pressing the electrode group 25 formed by rolling the separator 21 between the positive electrode plate 23 and the negative electrode plate 22 and rolling around the transverse crimp (O). After this, it is made of a structure that is connected to the electrode terminals (301a, 301b) through the lead terminals (50, 70), respectively.

In this case, the electrode assembly 20 is accommodated in the case 11 in a state where the horizontal crimp is horizontal. That is, the electrode assembly 20 of the present embodiment has a structure that is accommodated in the case 11 in the X-axis direction with reference to the drawings.

Meanwhile, in FIG. 1, a case in which the rectangular electrode assembly 20 is positioned in the case 11 is illustrated as an example. Hereinafter, the present invention will be described with reference thereto, but the present invention is not limited thereto.

And, the cap assembly 30 is fixed to the opening of the case 11, the base 301 for sealing the case 11, and the positive and negative, respectively positioned through and through the base 301 across the can and outside The electrode terminals 301a and 301b are respectively fixed to protrude out of the case 11 through the groove h. At this time, the screw thread S is formed in the electrode terminals 301a and 301b protruding to the outside of the case 11, and the screw thread S is interposed between the base 301 and the gasket 303. The electrode terminals 301a and 301b are fixed to the case 11 by fastening the bolt 305.                     

In addition, the cap assembly 30 further includes a vent part 40 which prevents the explosion of the battery by breaking at a set pressure and releasing gas.

The secondary battery of the present embodiment makes it possible to easily configure a battery module for a hybrid electric vehicle by using the electrode terminals 301a and 301b protruding out of the case 11, that is, dozens of batteries are crossed with each other with opposite polarities. The battery pack is configured by arranging them in series and connecting the adjacent batteries in series through a connecting member, and connecting the devices for cooling due to heat generation and the control devices to configure the battery module.

Hereinafter, with reference to FIG. 2 and FIG. 3, the electrode group used for a rectangular secondary battery is demonstrated. FIG. 2 is an exploded perspective view of the electrode group, and FIG. 3 is a perspective view showing a state of the electrode group formed in a square shape.

In addition, the electrode group described through this embodiment will be described as a structure in which the electrode terminals are respectively connected to the both ends of the pole plate intersecting the transverse crimp (O) through the uncoated portion where the active material is not coated, but the present invention is intended to be limited thereto. It is not.

In the present embodiment, the electrode group 25 is formed by interposing a separator 21 between the positive electrode plate 23 and the negative electrode plate 22 and rolling them around the transverse crimp (O). At this time, both end portions of the electrode group 25 are formed in the direction in which the uncoated portions 23b and 22b to which the active material is not applied cross each other with respect to the horizontal crimp O.

In more detail, the positive electrode and the negative electrode active materials 23a and 22a are coated on the respective current collectors 231 and 221 to form the positive electrode plate 23 and the negative electrode plate 22, and these are laterally rolled in a jelly roll type. In the state wound along the crimp O, it is pressurized with an apparatus such as a press to form a square (see Fig. 3). That is, a rectangular electrode is formed by pressing the electrode group 25 formed in a circular shape by winding them in a state in which a separator 21 for insulating them is interposed between the positive electrode plate 23 and the negative electrode plate 22. Group 25 is formed.

In this case, the uncoated portions 23b and 22b are positioned at the edge portions (upper and lower sides of the drawings) of the positive electrode plate 23 and the negative electrode plate 22 in the longitudinal direction, that is, the current collectors 231 and 221. ) And the positive and negative electrode uncoated parts 23b and 22b are alternately arranged.

In this state, the electrode plates forming the plain portions 23b and 22b are brought into close contact with each other, and the electrode assembly 20 is completed by joining the positive and negative lead terminals 50 and 70 there.

On the other hand, the electrode terminals 301a and 302b are provided, and the cap assembly 30 for sealing the can containing the electrode assembly 20 forms the vent portion 40 described with reference to FIG. 4.

Vent portion 10 according to the present embodiment is formed in the base 301, the vent hole 41; And a thin sheet vent member 43 formed with a notch 43a exposed to the vent hole 41 while blocking the vent hole 41.

In more detail, at both ends of the base 301 used as the cap assembly 30, holes h1 and h2 are formed to which the electrode terminals 301a and 301b are fastened, respectively, and a vent hole 41 is formed at the center thereof. ) Is formed. Here, the vent hole 41 may provide a passage through which the vent is operated to discharge gas.

And the vent member 43 which is fixed in addition to the vent hole 41 is located. The vent member 43 is a thin sheet metal sheet having a thickness of about 3 millimeters.

In the vent member 43, a notch 43a formed by a photolithography process described later is formed in a closed loop shape. As such, when the notch 43a is formed in a closed loop shape, the vent part 40 may operate under a relatively lower pressure than before, since the unit area of the vent part may be substantially exposed to internal pressure.

The vent member 43 forming such a notch is fixed to cover the vent hole 41 in a direction toward the inside of the can, and is fixed to the base 301 through laser welding. At this time, the notch is substantially positioned inside the vent hole 41.

On the other hand, Figure 5 is a view showing the cross-sectional shape of the notch, it is preferable that the notch formed by the present embodiment is made in the 'V' shape. One way of producing the 'V' shape is the photolithography process described below.

When the vent is formed by the etching process as described above, the vent part may be constantly operated under low pressure because the vent may be manufactured in a thin and fine form.

Practically, when the notch is manufactured with a mold, the width of the notch is formed in the millimeter (mm) level, but when the etching process is used, the notch width can be formed in the nanometer (nm) level. 'There is also an advantage that can be made relatively larger than when manufacturing with a mold.

6 is a schematic diagram illustrating a process of forming a notch by a photolithography process. Referring to this example, a process of forming a notch by a photolithography process is as follows.

The photoresist 103 is applied onto the aluminum film 101 used as the vent member by using photolithography (see (a)).

Then, a mask 105 having a notched pattern is disposed on the photoresist 103, and the photoresist 103 is exposed and developed through the mask 105 to form a mask pattern of the photoresist 103. Transfer to (see (b)).

Then, using the patterned photoresist 103 as a mask, the aluminum film 101 exposed to the lower layer is selectively etched (see (c)). At this time, by adjusting the etching solution and the etching time, the depth of the vent may be adjusted to form a notch of a fine deep groove.

Thereafter, the photoresist 103 is selectively removed using a release agent to form a notch according to the present embodiment (see (d)).

After the notch is formed through the photolithography process, the vent member 43 is attached to the base 31 to prepare a cap assembly.

Then, as described above, a rectangular electrode group is prepared and stored in a can in a state in which a lead terminal is attached to each uncoated portion. At this time, the electrode group is accommodated in the can with the horizontal crimp horizontal.

Therefore, as described above, the uncoated portions 23b and 22b are disposed at both ends of the electrode group 25, and intersect the transverse crimps O of the electrode group 25 on the uncoated portions 23b and 22b. When the lead terminals 50 and 70 are connected to each other, the space between the case 11 and the electrode group 25 can be reduced, and the unit volume of the electrode group can be increased for the case having the same size as in the related art. Since the number is high, the energy density per unit volume of the battery can be increased.

In this state, the cap assembly 30 is positioned so that the electrode terminals having the same polarity as the lead terminals 50 and 70 of the electrode group 25 protruding in the height direction of the case 11 are positioned. Laser welding is performed on the joining surface where the electrode terminals abut to connect the electrode group and the cap assembly to each other.

After the cap assembly 11 is joined to the opening of the case, laser welding is performed along the joining surface to seal between the cap assembly and the case to complete the secondary battery of this embodiment.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

According to the present invention, there is an advantage that can be formed in the most ideal shape to solve the above problems. Accordingly, since the vent can be constantly operated under low pressure, there is an effect of ensuring the stability of the secondary battery.

Claims (18)

An electrode group formed by winding a pole plate composed of a positive electrode plate and a negative electrode plate with a separator interposed therebetween; A case accommodating the electrode group in a state in which the horizontal crimp is parallel; And, A cap assembly having a vent part having a notch broken at a predetermined pressure and having a positive and negative electrode terminal electrically connected to the electrode group while sealing the case; A secondary battery formed by including. The method of claim 1, The vent portion, Vent holes; And, And a thin sheet vent member formed with a notch exposed to the vent hole while blocking the vent hole. The method of claim 2, The vent member and the cap assembly are formed of the same material. The method of claim 2, The vent member is fixed to the vent member by welding so that the notch faces inside the can. The method of claim 1, A secondary battery having a cross-sectional shape of the notch having a 'V' shape. The method of claim 5, The notch is formed by a photolithography process secondary battery. The method of claim 5, A secondary battery in which the notch is formed as a closed loop. The method according to any one of claims 1 to 7, Secondary battery is the case is formed in a square. The method of claim 8, A secondary battery, wherein the secondary battery is for driving a motor. In the cap assembly provided with the electrode terminal while sealing the can containing the electrode group, Vent holes; and, And a vent part formed of a thin plate vent member formed with a notch exposed to the vent hole while blocking the vent hole. The method of claim 10, And the vent member is fixed to the vent member by welding in a can in which the electrode group is accommodated. The method of claim 10, Cap assembly having a cross-sectional shape of the notch 'V' shape. The method of claim 12, And the notch is formed by a photolithography process. The method of claim 10, A cap assembly in which the notch is formed as a closed loop. In the battery module consisting of a pack unit by connecting a plurality of secondary batteries to each other, Each secondary battery constituting the battery module includes a vent hole; and a vent member formed of a thin plate positioned to expose the notch to the vent hole while blocking the vent hole. The method of claim 15, A battery module having a cross-sectional shape of the notch having a 'V' shape. The method of claim 16, The notch is formed by a photolithography process battery module. The method of claim 15, A battery module in which the notch is formed as a closed loop.

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