KR20060011664A - Cap assembly, secondary battery and module thereof - Google Patents

Abstract

The secondary battery having improved safety provided by the present invention includes: 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 part which is electrically connected to the electrode group while sealing the case and is provided with a negative electrode terminal, and a part of a notch broken at a predetermined pressure is formed in a 'V' shape. It is formed to include.

Secondary battery, groove, safety valve, 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 and 6 show the cross-sectional shape of the notch.

The present invention relates to a secondary battery, and more particularly to an invention that improves the safety of the secondary battery.

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

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 composed of one cell, it is mainly formed in a cylindrical or rectangular shape, and is wound around a vortex through a separator, which is an insulator, between the two bands and the negative electrode 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, large batteries have a risk of explosion due to the pressure inside the battery generated by the electrochemical reaction. Therefore, a large battery is generally configured to further include a vent (or 'safe side') for preventing the explosion of the battery. At this time, the vent is formed in a notch shape, and the vent is broken under a predetermined pressure to prevent the battery from being exploded.

However, the vent used in the rectangular secondary battery has a disadvantage that its cross-sectional area 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.

Vents, on the other hand, are more likely to break at lower pressures as they are made in the form of fine and fine cracks. However, since the conventional vent is formed by pressing into a mold, there is a limit in that the cross section is formed into a half moon shape, and thus there is a problem that the breaking pressure is relatively high without being constant.

Therefore, the vent does not break properly under a predetermined pressure, and thus represents a dangerous problem such as an explosion of a 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 in which the electrode terminal for the cathode and the cathode, which are electrically connected to the electrode group while being sealed to the case, is formed at a predetermined pressure and partially formed in a 'V' shape. Is formed.

In the present invention, it is preferable that the notch is formed of a first groove and a second 'V'-shaped groove formed in the first groove.

In this case, the first groove is more preferably formed larger than the second groove.

The first groove may be formed by pressing molding, and the second groove may be formed by cutting molding.

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,

Blocking the vent hole, the shape of the notch that is broken at a constant pressure is formed in part of the 'V' shape.

In addition, the battery module provided by 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 has a vent hole; and a vent part having a shape of a notch broken at a constant pressure while partially blocking the vent hole is formed in a 'V' shape.

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. By fastening the bolts 305, the electrode terminals 301a and 301b are fixed to the case 11.

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 roll-wound in a jelly roll type. In the state wound according to (O), it is pressurized by the apparatus like a press, and formed in square shape (refer 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 40 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 mm (mm).

The vent member 43 is provided with a notch 43a formed by a method described later. At this time, the notch 43a is preferably formed as a closed loop.

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 43a is substantially positioned inside the vent hole 41.

5 and 6 show cross-sectional shapes of the notches, the vent part 40 of the present embodiment discharges the pressure that is filled inside the battery as the vent member 43 breaks along the notch 43a. To work.

In the present embodiment, the cross-sectional shape of the notch 43a is preferably formed as a 'V' shaped groove as shown in the figure. That is, the wall surface of the notch 43a has the shape of an inverted triangle in a tapered state. When the notch 43a is formed in this way, the pressure applied to the notch 43a becomes constant, and there is an advantage in that the fracture occurs accurately by the pressure under a predetermined condition, that is, the depth and the shape of the notch.

As an example, the notch 43a having such a cross-sectional shape may be formed by using a milling cutter for grooving. The vent member 43 is mounted and fixed on a lathe, and the vent is formed by a sharp milling tab. The member 43 can be formed by cutting to a certain depth.

As another embodiment of the present invention, a notch having a cross-sectional shape as shown in FIG. 6 may be preferably used.

That is, in the state where the notches are formed by pressing the first grooves 431 as before, the second grooves 433 may be formed by adding the second grooves 433 to the first grooves 431 in a 'V' shape. In this case, the first groove 431 is preferably formed larger than the second groove 433.

When the notch 43a is formed in this manner, the first groove 431 guides the breaking pressure of the notch to the second groove 433, so that the notch 43a is accurately broken even at a lower pressure than before. There is an advantage that can secure the stability of the battery preferably.

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 (17)

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 which is electrically connected to the electrode group while sealing the case and is provided with a negative electrode terminal, and a part of a notch that is broken at a constant pressure is formed in a 'V' shape; A secondary battery formed by including. The method of claim 1, The notch is formed of a first groove and a second 'V'-shaped groove formed in the first groove. The method of claim 2, The secondary battery has the first groove is formed larger than the second groove. The method of claim 2, A secondary battery in which the first groove is formed by pressing molding. The method of claim 2, The secondary battery is the second groove is formed by cutting molding. The method according to any one of claims 1 to 5, Secondary battery is the case is formed in a square. The method according to any one of claims 1 to 5, 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, A vent part in which a shape of a notch broken at a predetermined pressure is partially formed in a 'V' shape while blocking the vent hole; Cap assembly formed to include. The method of claim 8, And the notch is formed of a first groove and a second 'V' groove formed in the first groove. The method of claim 9, The cap assembly of claim 1, wherein the first groove is formed larger than the 'V' groove. The method of claim 9, A cap assembly in which said first groove is formed by pressing molding. The method of claim 9, A cap assembly in which said second groove is formed by cutting molding. The method according to any one of claims 9 to 12, A cap assembly wherein said notch is substantially positioned within said vent hole. 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 is a vent hole; and the vent portion is formed in the 'V' shape of the notch to be broken at a constant pressure while blocking the vent hole; The method of claim 14, And the notch is formed of a first groove and a second 'V' groove formed in the first groove. The method of claim 15, The battery module wherein the first groove is formed by pressing molding. The method of claim 15, The battery module of the second groove is formed by cutting molding.

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