KR100346386B1 - Safety apparatus used in secondary battery - Google Patents

Abstract

Disclosed is a safety device for a secondary battery. The present invention relates to a safety device of a secondary battery that prevents an increase in internal pressure due to abnormal operation or overcharging of a battery by blocking current flow, and prevents heat generation and explosion, and can accurately operate at a set operating pressure. A safety device for a secondary battery formed by stacking a safety plate, an insulator, and a current blocking disk in an upper opening of the safety device, comprising: a safety plate having an extended margin, a current blocking disk having a variable part, and the safety plate and the variable part contacting each other. By the current, the expansion margin is expanded when the internal pressure of the battery rises, it is configured to block the current by pushing up and breaking the variable part. According to the present invention, the safety plate and the current blocking disk can be operated precisely at the set operating pressure by simply contacting each other instead of joining by welding or the like, thereby ensuring high safety against abnormal operation and explosion of the battery.

Description

Safety apparatus used in secondary battery

The present invention relates to a secondary battery, and in particular, when the internal pressure of the battery rises above the prescribed pressure due to abnormal operation of the battery, it blocks the flow of current and releases the internal gas to prevent explosion to ensure the safety of the battery. It relates to a safety device of a secondary battery.

Rechargeable batteries can be recharged, miniaturized, and large-capacity, and are representative of nickel hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) batteries.

Lithium-ion batteries, well known as such secondary batteries, are lithium-transition metal oxides used as positive electrode active materials, carbon or carbon composite materials are used as negative electrode active materials, and a liquid electrolyte in which lithium salt is dissolved in an organic solvent is injected therebetween. Lithium ions are moved between the negative electrode and the negative electrode to generate an electromotive force so that charge and discharge are performed.

4 shows a lithium ion battery having a conventionally known spiral-wound electrode portion. The electrode part 2 wound together with the positive electrode and the negative electrode is housed inside the can 4 connected with the negative electrode together with the liquid electrolyte, and the upper part of the can 4 is insulated through the gasket 6 and the The cap assembly 8 which connects with a positive electrode is provided.

The cap assembly 8 is laminated from the top in the order of the cap cover 10, the current limiter 12, and the safety plate 14, and the lower part of the safety plate 14 is interposed with an insulator 16. 16) The current blocking disk 18 is attached to the lower part, and the upper part of the can 4 is assembly sealed by crimping and other methods. The current blocking disk 18 is welded with the positive electrode tab 20 before assembly for connection with the positive electrode.

The lithium ion battery configured as above may cause decomposition of the liquid electrolyte in the positive electrode and short-circuit due to the deposition of lithium metal at the negative electrode during abnormal operation or overload of the battery. Will accompany.

For this reason, in the related art, the safety plate 14 is formed by forming a groove 14A having a constant depth or mechanically etched by a mechanical method or an etching method, or relatively weakly deformed, so that when the pressure inside the battery rises above the specified pressure, the current is first. The welding bond with the blocking disk 18 is dropped and the weak portion of the groove 14A is broken, thereby preventing the explosion by blocking the flow of current and reducing the internal pressure.

However, in the safety device up to now, the safety plate 14 and the current blocking disk 18 is coupled by mutual welding, the operating pressure is determined by the welding force, it is technically difficult to accurately match the operating pressure, In particular, there was a problem that the risk of explosion of the battery during malfunction.

The present invention was devised to solve the above problems, so that the operating pressure of the safety plate and the current blocking disk is always kept constant without being influenced by the influence of the assembling process or material, and ultimately the abnormal operation of the battery. The purpose of the present invention is to provide a safety device for secondary batteries that can ensure safety against explosions.

1 is a cross-sectional view showing the configuration of a cap assembly of a secondary battery according to an embodiment of the present invention;

2 is a perspective view of a safety plate according to an embodiment of the present invention,

Figure 3a, 3b is an operating state of the safety device according to the present invention,

4 is a cross-sectional view showing the configuration of a cap assembly of a secondary battery according to the prior art.

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

12: current limiter 100: safety plate

120: insulator 140: current blocking disk

140A: protrusion 140B: expansion clearance

140C: Notch

In order to solve the above problems, a safety device of a secondary battery according to an aspect of the present invention includes an electrode part in which a positive electrode, a negative electrode, and a separator are wound together with a liquid electrolyte, and the inside of the can, and a gasket in the upper opening of the can. In the safety device of the secondary battery formed by sealing in the order of a safety plate, an insulator, a current blocking disk and a current limiter from below, a safety plate having an extended margin, a current blocking disk having a variable portion and When the safety plate and the variable portion are in contact with each other, the current flows, and when the internal pressure of the battery increases, the expansion margin is expanded, and the variable portion is pushed up and broken to block the current.

The variable portion of the safety plate and the current blocking disk is characterized in that it is connected only by contact, not a method such as welding.

In addition, it is preferable to form notches on both bottom surfaces of the current blocking disk so that the safety plate is easily lifted by the pushing force and broken.

Best Mode for Carrying Out the Invention Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

For reference, in describing the present invention, the same reference numerals will be used for the clarity of description for the configuration of the present invention that is the same as the drawings cited in the prior art.

1 is a cross-sectional view showing the configuration of a cap assembly of a secondary battery according to an embodiment of the present invention, Figure 2 is a perspective view of a safety plate according to an embodiment of the present invention.

As shown in detail in FIG. 1, the secondary battery of the present invention includes a can 4 through which a positive electrode, a negative electrode, and a separator are wound together, and a gasket 6 inserted into an opening of the can 4. The cap assembly 80 is coupled in an insulated state.

The cap assembly 80 is stacked in the order of the cap cover 10, the current limiter 12 and the current blocking disk 100, the insulator 120 and the safety plate 140.

In the cap assembly 80 configured as described above, the safety plate 140 has a protrusion 140A having a central protrusion and an expansion clearance 140B having a periphery recessed therein, and the protrusion 140A having the current blocking disk ( 100, it is configured to be connected to the protrusion 140A of the safety plate 140 by a simple contact rather than by a combination of the prior art welding or the like.

In addition, the protruding protrusion 140A of the safety plate 140 in contact with the current blocking disk 100 is configured to have a flat surface, and the periphery of the protrusion 140A forms an expanded clearance 140B recessed in the battery. The expansion margin 140B is expanded when the internal pressure increases. In addition, by forming the notches 140C at both ends of the safety plate 140 by etching or a mechanical method, the safety plate 140 can be easily raised when the internal pressure of the battery rises above a prescribed pressure. do.

By constructing the assembly 80 as described above, when the internal pressure of the battery rises above the prescribed pressure, the safety plate 140 rises due to the pressure inside the battery, so that the variable portion 100A of the current blocking disk 100 is increased. The current is interrupted by pushing up and causing it to break at the set pressure.

3A and 3B illustrate a process until the current blocking disk 100 is broken. As shown in FIG. 3A, the safety plate 140 deformed upward by the internal pressure primarily pushes the variable portion 100A of the current blocking disk 100 as shown in FIG. , Secondly, the notch 140C of the safety plate 140 is broken at a predetermined pressure or more, thereby releasing the gas inside the battery, thereby preventing a danger due to an explosion.

According to such a configuration, the safety device of the present invention may be generated in the case of joining by welding or the like by simply contacting the variable portion 100A of the current blocking disk 100 and the protrusion 140A of the safety plate 140. Solving the problem of malfunction can increase the safety of the battery.

In addition, by simply contacting the current blocking chisk 100 and the safety plate 140, it is possible to improve the productivity by reducing the bonding step such as welding.

As described above, the safety device of the secondary battery according to the present invention substantially solves the problems of the prior art.

The safety device of the secondary battery of the present invention can be operated accurately at the set pressure by simply contacting the variable plate of the safety plate and the current blocking disk to ensure high battery safety, and can improve productivity by reducing the welding process.

The present invention is not limited to the above-described embodiment, and it is apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (3)

In the safety device of a secondary battery formed by laminating a safety plate, an insulator and a current blocking disk in the upper opening of the can, A safety plate having an expansion margin, a current blocking disk having a variable section, a current through the contact with the safety plate and the variable section, and when the internal pressure of the battery rises, the expansion margin is expanded and the variable section is pushed up and broken Safety device of a secondary battery, characterized in that to cut off the current. The safety device of claim 1, wherein the safety plate and the variable part are connected by a simple contact, not by a welding method. The safety device of a secondary battery according to claim 1, wherein notches are formed on bottom surfaces of both ends of the current blocking disk.