KR100551050B1 - Cap assembly of secondary battery with shape memory alloy - Google Patents

Abstract

The present invention provides a cap assembly of a secondary battery made of a shape memory alloy, which is improved in a structure in which fatigue is not accumulated even when the shape recovery is repeated when the shape memory alloy is used as an actuator for blocking an internal circuit of the battery. An electrode pin coupled to the opening of the can to penetrate the cap plate to seal the internal space, a tab plate disposed around the lower pillar of the electrode pin, and a shape memory alloy piece interposed between the pillar and the tab plate. The shape memory alloy piece is recovered in shape above the critical point to interrupt the electrical connection between the pillar and the tab plate.

Secondary Battery, Cap Assembly, Shape Memory Alloy

Description

CAP ASSEMBLY OF SECONDARY BATTERY WITH SHAPE MEMORY ALLOY}

1 is a partially enlarged side sectional view showing a configuration according to an embodiment of the present invention cap assembly.

2 is a plan view of the main portion of the shape memory actuator of FIG.

Figure 3 is a side cross-sectional view showing a configuration according to another embodiment of the cap assembly of the present invention.

4 is a perspective view showing the main components of the embodiment shown in Figure 3 in a separated state.

Figure 5 is a side cross-sectional view showing a configuration according to another embodiment of the present invention cap assembly.

FIG. 6 is a partial perspective view showing the appearance of a main part shown in FIG. 5; FIG.

<Description of the symbols for the main parts of the drawings>

2: electrode group 4: cap plate

6: electrode pin 8: pillar

10 gasket 12 cap plate

12a, 12b: member 14: insulator

16: tab 18: shape memory alloy piece

The present invention relates to a cap assembly of a secondary battery, which is capable of blocking an internal circuit by detecting a temperature rise caused by an abnormal reaction inside the battery generated when the secondary battery is overcharged, and more particularly, the temperature inside the battery is above a critical point. The present invention relates to a cap assembly of a secondary battery made of a shape memory alloy, which immediately interrupts an internal circuit.

The secondary battery is wound in a roll shape inside a can of a predetermined shape with a separator interposed between a positive electrode plate and a negative electrode plate coated with an active material, and the inside of the can is filled with a jelly-like electrolyte to generate electricity by a chemical reaction between the positive electrode plate and the negative electrode plate. As a battery having a structure, the battery is widely used as a power source for portable electronic devices because of the advantage that it can be reused through charging.

In the above-described secondary battery, the upper surface of the can is generally covered with an insulating plate, and a center thereof is installed such that a positive electrode derived from the positive electrode plate housed therein protrudes to the outside, and the negative electrode plate is grounded to the can, that is, the bottom of the can exposed to the outside This cathode becomes.

In the secondary battery having such a configuration, when a charger breaks down unexpectedly and an overvoltage is applied during charging or an overdischarge occurs, the electrolyte filled inside the can causes heat generation as a result of a radical chemical reaction. At this time, the internal temperature is increased to 80 ℃ or more, if left unattended, the internal volume of the can is rapidly increased, causing explosive injuries.

In order to solve the above-mentioned problems, the practical secondary battery has a chemical solution that incorporates an additive which suppresses an abnormal reaction in the battery when it is in an abnormal state into an electrolytic material, or a mechanical safety device using a PTC, a thermal fuse, or a bimetal contact. The latter mechanical safety device can be easily installed, and is widely used because of its high reliability because there is no change in the external environment.

The mechanical safety device added to the secondary battery is generally installed at the bottom of the positive electrode which is exposed from the inside of the can to the outside.

For example, Japanese Patent Application Laid-open No. Hei 10-74500 arranges a partition on the inner side of the can and eliminates the pressure increase caused by the volume change in the interior by discharging it through a valve hole installed in the partition. When the internal temperature rises sharply, the shape memory alloy plate having a dome shape causes deformation and breaks the circuit.

The shape memory alloy plate has an advantage of reliably operating at a critical point compared to bimetallic and thermal fuses. However, it is quite difficult to manufacture and expensive.

That is, the shape memory alloy rapidly cools a sample of a certain shape at a higher temperature than a critical temperature to form a martensite phase, and deforms it differently from the initial shape. Is a metal having the function of recovering to the initial shape, and the internal circuit is reliably cut off when the threshold temperature is adjusted to the temperature at the time of abnormal occurrence in the battery.

TiNi-based and copper-based alloys are known as shape memory alloys, and TiNi-based alloys have the best shape recovery characteristics. This is because the temperature of the shape recovery, especially in the case of TiCr alloy drops to 93 ℃, mechanical strength and workability is also good, it can be used as an actuator for blocking the internal circuit of the secondary battery, but it is difficult to manufacture There is this.

Copper-based alloys have a simple melting method, excellent plastic workability and cutting workability, and excellent conductivity, while having low strength and poor resistance compared to TiNi-based alloys. However, Cu 13.5 to 14% Al 4 When 0.96% Ti and 2% Mn are added to the% Ni 5% alloy, the grains become fine and the hot / cold workability of the material is excellent.

The shape recovery characteristics of the shape memory alloy having such characteristics have a shape recovery reliability only when the amount of torsion generated at the time of deformation is constantly limited. Therefore, if the shape is set to a shape that is excessively deformed, the amount of warpage increases, fatigue accumulates during operation, and the service life is shortened.

As mentioned above, the shape memory alloy has many advantages, but its use is limited. However, the shape memory plate disclosed in Japanese Patent Application Laid-open No. Hei 10-74500 is formed in a domed form, and the shape recovery is made to be transformed to 180 degrees. In view of the characteristics of, it is in fact difficult to realize.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to improve the shape of the shape memory alloy as an actuator for blocking the internal circuit of the battery so that fatigue is not accumulated even when the shape recovery is repeated. A cap assembly of a secondary battery made of a memory alloy is provided.

Another object of the present invention to provide a secondary battery having the cap assembly described above.

The cap assembly for a secondary battery according to the present invention is coupled to the can so as to seal the inner space in an opening of a can having an inner space, and is electrically connected to an electrode group housed in the can. An electrode pin coupled to the opening to penetrate the cap plate to seal the internal space, interposed between the tab plate disposed around the lower pillar of the electrode pin and the pillar and the tab plate, and recovering the shape at or above the critical point. And a shape memory alloy piece that blocks the electrical connection between the pillar and the tab plate.

In addition, the square secondary battery according to the present invention,

A rectangular can having an internal space, an electrode group accommodated in the internal space, and a cap assembly coupled to the can to seal the internal space in an opening of the can, and electrically connected to the electrode group,

The cap assembly is interposed between a cap plate coupled to the opening to seal the internal space, an electrode pin penetrating through the cap plate, a tab plate disposed around a lower pillar of the electrode pin, and the pillar and the tab plate. And a shape memory alloy piece that recovers shape above a critical point to block electrical connection between the column and the tab plate.

In the present invention, the tab plate may be provided in a single body or in two parts.

In the case where the tab plate is divided into two parts, the shape memory alloy piece is shaped to recover from a bellows shape to a cylindrical shape and is interposed between the two divided tab plates.

In the case of a single tab plate, the shape memory alloy piece is at least one pair of contact ends provided on the inner circumferential surface of the through hole of the tab plate through which the pillar of the electrode pin passes.

In addition, the contact end may be formed in a form extending in the radial direction from the inner peripheral surface of the through hole.

As another example, the contact end may be arranged to be in contact with the lower side of the electrode pin, in this case, the lower side of the electrode pin is preferably formed in a hemispherical shape.

Hereinafter, with reference to the accompanying drawings the present invention will be described in detail by preferred embodiments.

1 is a partially enlarged view showing a configuration according to an embodiment of a cap assembly according to the present invention, an electrode group accommodated in a can (for example, a square) having a suitable shape by rolling in a roll with a separator interposed between a positive electrode plate and a negative electrode plate ( The upper part of 2) is covered by a cap plate 4 which seals the can.

The cap plate 4 is installed so that the head of the electrode pin 6 is exposed to the outside, and the lower pillar 8 extends inwardly, and the cap plate 4 and the electrode pin 6 are disposed. Interposed therebetween is a gasket 10 for maintaining hermeticity and insulation.

When the cap plate 4 is sealed in the opening of the can, the cap plate 4 is integrally joined by means of welding or the like and is electrically connected to the negative electrode plate of the electrode group 2.

And the tab plate 12 is arrange | positioned in the direction orthogonal to the axis | shaft, and is always in electrical contact with the pillar 8 of the electrode pin 6.

The tab plate 12 is a conductor having a thickness of about 20 μm, which is attached to the underside of the cap plate 4 while being surrounded by the insulating plate 14. Accordingly, between the cap plate 4 and the tab plate 12 is insulated, and is electrically connected to the tab 16 derived from the positive electrode plate included in the electrode group 2, so that the electrode pin 6 ) Acts as an anode.

In the tab plate 12 described above, in the present invention, as shown in FIG. 2, two members 12a and 12b, which are substantially divided into two, are connected in a folding structure by the bridge 12c at one end thereof. The opposing surfaces of the members 12a and 12b are formed of an arcuate contact surface 12d in which the pillar 8 is curved to conform to the outer circumferential surface, and a shape memory alloy piece 18 between the opposite ends of the bridge 12c. ) Is interposed and both members 12a and 12b are located close to each other on the opposite side with the pillar 8 interposed therebetween, so that the circular arc contact surface 12d is pressed against the outer circumferential surface of the pillar 8. The spring 12e is constructed in a temporary construction.

On the other hand, the shape-memory alloy piece 18 has a bellows shape at room temperature in this embodiment, and has a short length, and has a configuration in which the shape recovers to a cylindrical shape at a temperature above the critical point and increases in length.

According to the above configuration, when the inside of the battery is in a normal state, the electrical connection is maintained between the pillar 8 and the tab plate 12. However, when an abnormality occurs, when the internal temperature of the battery rises and reaches a critical point, the shape As the memory alloy piece 18 recovers from a bellows shape to a cylindrical shape, as shown by the dashed-dotted line in the figure, the gap between the two members 12a and 12b is opened so that the outer peripheral surface of the pillar 8 is opened. Both arcuate contact surfaces 12d, which are pressed against each other, are dropped to perform the blocking function of the internal circuit.

In the present invention, the shape memory alloy piece 18 is not limited to the above embodiment, and may be implemented as a single body with the tab plate 12 as shown in FIG.

In Fig. 3, the tab plate 12 is integrally attached to the portion in contact with the pillar 8 in a shape memory alloy piece 18 that is bent to form an approximately oblique direction with respect to the axial direction. 18, as shown by the dashed-dotted line in the figure above the critical point, the shape is restored to act to release the battery contact.

Shape memory alloy piece 18 that is integrally formed with the tab plate 12 as described above, more preferably, as shown in Figure 4, in the inner peripheral surface of the through-hole perforated so that the pillar 8 can penetrate In a radial arrangement, it is preferable that the electrical contact state and the circuit interruption state can be clearly distinguished.

Figure 5 shows a configuration related to another embodiment of the cap assembly of the present invention.

In this embodiment, the bottom surface of the electrode pin 6 forms a hemispherical surface 20, and the tab plate 12 has a plurality of shape memory alloy pieces 18 that are in elastic surface contact with the hemisphere surface 20. It is the same as the above-mentioned embodiment except the structure provided with).

Therefore, also in this embodiment, the internal circuit interruption action of the battery is shown by the shape memory alloy piece 18 being recovered in shape as indicated by the dashed-dotted line in the figure.

More specifically, the plurality of shape memory alloy pieces 18 may be arranged in a shape corresponding to the hemispherical shape, as shown in Figure 6, in this case the deformation direction of the shape memory alloy piece 18 is a hemispherical surface ( In the radial direction of Fig. 20), even with light deformation, the connection and disconnection action of the internal circuit of the battery are evident.

  Shape memory alloy piece 18 having such a small amount of shape recovery has the advantage that the manufacturing is also simple.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and the present invention can be modified in various forms within the scope of the claims and the detailed description of the invention and the accompanying drawings.

In addition, in the above-described embodiment of the present invention, the shape of the shape memory alloy piece 18 may be manufactured using a TiNi-based copper alloy.

As described above, the present invention has a shape recovery deformation amount that is small so that fatigue does not accumulate in the operation part even when the operation of the secondary battery is interrupted by using the shape memory alloy. As it is formed, it has the advantage of ensuring the reliability of the operation while properly using all the characteristics of the shape memory alloy.

Therefore, it is possible to apply practically to secondary batteries, in particular square secondary batteries.

Claims (12)

In the cap assembly for secondary batteries coupled to the can so as to seal the inner space in the opening of the can having an inner space, and electrically connected to the electrode group housed in the can, An electrode pin coupled to the opening to penetrate the cap plate to seal the internal space; A tab plate disposed around the lower pillar of the electrode pin; And Is interposed between the pillar and the tab plate, and includes a shape memory alloy piece for restoring the shape above the critical point to block the electrical connection between the pillar and the tab plate, The tab plate is formed in two parts, the tension spring is installed on one side end of the members arranged opposite to each other and the shape memory alloy piece is interposed on the opposite end, so that the space between the two members is formed while recovering the shape above the critical point of the battery Cap assembly for secondary battery to cut off the internal circuit. delete delete The method of claim 1, The tab plate is formed of a single body, and having a shape memory alloy piece on the inner circumferential surface through which the pillar of the electrode pin penetrates, the secondary battery cap assembly having a configuration installed as a contact end that is an electrical passage with the electrode pin. The method of claim 4, wherein The contact end is a secondary battery cap assembly is formed in a plurality extending in the radial direction from the inner peripheral surface of the through hole. The method of claim 1, The lower end of the electrode pin is formed into a hemispherical surface, the shape memory alloy piece of the tab plate is a secondary battery cap assembly having a configuration arranged in a plurality of forms to match the hemisphere. A rectangular can having an inner space; An electrode group accommodated in the internal space; And A cap assembly coupled to the can and electrically connected to the electrode group to seal the internal space in the opening of the can, The cap assembly, A cap plate coupled to the opening to seal the internal space; An electrode pin penetrated through the cap plate; A tab plate disposed around the lower pillar of the electrode pin; And Is interposed between the pillar and the tab plate, and includes a shape memory alloy piece for restoring the shape above the critical point to block the electrical connection between the pillar and the tab plate, The tab plate is formed in two parts, the tension spring is installed on one side end of the members arranged opposite to each other and the shape memory alloy piece is interposed on the opposite end, so that the space between the two members is formed while recovering the shape above the critical point of the battery Rectangular secondary battery to cut off the internal circuit. delete delete The method of claim 7, wherein The tab plate is formed of a single body, and has a shape memory alloy piece on the inner circumferential surface of the through-hole through which the pillar of the electrode pin has a rectangular secondary battery having a configuration installed as a contact end that is an electrical passage with the electrode pin. The method of claim 10, The contact end is a rectangular secondary battery is formed in a form extending in the radial direction from the inner peripheral surface of the through hole. The method of claim 7, wherein The lower end of the electrode pin is formed in a hemispherical surface, the shape memory alloy piece of the tab plate is a rectangular secondary battery having a configuration arranged in plurality in a shape corresponding to the hemisphere.

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