KR100968052B1 - Battery Pack Employed with Mechanical Fuse - Google Patents

Abstract

The present invention is a battery pack in which a plate-shaped battery cell is embedded in the pack case, a flexible linear member of low elongation surrounding the outer surface of the battery cell, and the amount so that the tensile force due to the volume change during expansion of the battery cell can be concentrated and cut Provided is a battery pack including a mechanical fuse connected to an electrode terminal with an end connected to the linear member.

Such a battery pack has an effect of securing safety by stopping the operation of the battery is destroyed when the battery cell is expanded with high reliability without increasing the internal resistance.

Description

Battery Pack with Mechanical Fuse {Battery Pack Employed with Mechanical Fuse}

1 is a perspective view of a representative external battery pack;

2 is a perspective view of a representative internal battery pack;

3 is an exploded perspective view of a general internal structure of a small battery pack;

4 and 5 are a plan view and a perspective view of a battery cell in which the mechanical fuse is mounted on the outer surface according to one embodiment of the present invention;

6 is a schematic vertical cross-sectional view of a state in which a mechanical fuse is mounted on an outer surface of a battery cell according to the present invention.

The present invention relates to a battery pack in which a plate-shaped battery cell is embedded in a pack case, and more particularly, to a flexible linear member having a low elongation surrounding an outer surface of a battery cell, and a tensile force due to a volume change when the battery cell is expanded. The present invention provides a battery pack including a mechanical fuse connected to an electrode terminal at both ends connected to the linear member so as to be concentrated and cut.

As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is increasing rapidly. Among them, many researches have been conducted and commercialized and widely used for lithium secondary batteries with high energy density and discharge voltage. It is used.

Lithium secondary batteries are classified into cylindrical batteries, square batteries, pouch-type batteries, and the like according to their appearance, and may be classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, and the like according to the type of electrolyte. Due to the recent trend toward the miniaturization of mobile devices, there is an increasing demand for small square and pouch type batteries.

In portable devices such as mobile phones and digital cameras, small battery packs in which battery cells such as square batteries and pouch-type batteries are incorporated in a pack case are used. Such small battery packs may be classified into external battery packs (hard packs) and internal battery packs (inner packs), depending on the form in which the battery cells are mounted in the pack case.

Representative external battery packs and internal battery packs are schematically illustrated in FIGS. 1 and 2, respectively, and these battery packs have their advantages and disadvantages, respectively.

The external battery pack 10 as shown in FIG. 1 forms an external part of the external device 12 to which it is mounted, and thus has an advantage of being easily mounted to the external device 12 during use, but includes a battery cell (not shown). In one state, the case (housing: 11) has to be designed according to the type of the external device, which is relatively expensive and less compatible.

On the other hand, since the built-in battery pack 20 as shown in Figure 2 is used to cover the cover forming a part of the external device in a state mounted inside the external device, mounting is a relatively cumbersome disadvantage, but easy to design and inexpensive It has the advantage of high compatibility.

A general internal structure of these small battery packs is shown in FIG.

Referring to FIG. 3, the battery pack 30 includes a battery cell 31 having, for example, a positive electrode terminal at one side and a negative electrode terminal at the other side thereof; A PTC element 32 connected to one of the two electrode terminals of the battery cell 31 to block the energization of the battery when overheated; The nickel plate 33 is connected to the electrode terminal (one of the positive electrode terminal and the negative electrode terminal) of the PTC element 32 and the other electrode terminal through the nickel plate 37 to control overcharging, overdischarging, overcurrent, etc. of the battery. A protection circuit module (PCM) 34 having an external input / output terminal formed thereon so as to be connected to a corresponding device (not shown); It consists of an upper case 35 and a lower case 36 surrounding the battery cell 31, the PTC element 32 and the PCM 34.

An insulating sheet 38 is disposed between the side surface of the battery cell 31 and the nickel plate 33, and between the PCM 34 and the nickel plate 37, so that the battery cells adjacent to each of the nickel plates 33 and 37 ( 31) or short circuit is prevented by unnecessary contact between the protection circuit 34.

In addition, a double-sided tape 39 is disposed between the battery cell 31 and the lower case 36 so that the battery cell 31 can be fixed to the bottom surface of the lower case 36. Therefore, when the battery cells 31 are accommodated in the upper and lower cases 35 and 36, the battery cells 31 can be stably fixed in the upper and lower cases 35 and 36.

After the upper case 35 is coupled to the lower case 36 in which the battery cells 31 are stored, in order to further increase the coupling force between the cases 35 and 36 and to prevent foreign substances from entering the coupling site or the inside of the case. The packaging label 40 may also be wrapped.

Therefore, the small battery pack ensures the safety of the battery by controlling overcharge, overdischarge, overcurrent, etc. in the PCM and, in some cases, the safety during overheating by the PTC element.

Nevertheless, the battery cells may be in a dangerous state due to various causes such as abnormal operation of the safety devices, sudden external shocks, and in some cases, the decomposition of the electrolyte may be rapidly promoted, resulting in a risk of explosion. In addition, since the expansion of the battery cell may be caused by a slow process not detected by the safety devices, such safety devices alone do not fundamentally solve this problem. The ignition and explosion of the battery cell is the most serious problem that impairs the safety of the battery, and many studies have been conducted to solve it.

In general, the cylindrical battery is easy to secure the internal space for mounting the device for releasing it when the internal pressure rises, the square or pouch type battery cell is not easy because of the structure of the battery pack. Thus, several attempts have been made to solve this problem.

For example, in Korean Patent Registration No. 369,069, one terminal of a pouch-type battery cell extends to cover the outer surface of the battery cell, and a notch is formed in the middle of the battery cell so that the notch ruptures when the battery cell is expanded. The art of making is disclosed. However, this configuration has several problems, firstly, the internal resistance is greatly increased due to the increase in the length of the terminal, and second, the risk of short circuit is high because the electrode terminal wraps the outer surface of the battery cell. Although the tensile force of is concentrated on the notch, the electrode terminal surrounding the battery cell itself is made of the same material, resulting in overall tension, and has a problem that it is difficult to rupture reliably at a predetermined critical pressure (expansion degree).

In addition, U.S. Patent No. 6,136,464 forms a recess indented on the battery cell case, places a cutting member in the recess, and passes the terminal on the upper portion thereof so that the recess is raised during expansion of the battery cell. Disclosed is a technique in which a cutting member is configured to cut a weak portion of a terminal. However, such a configuration is based on a complex structure has a disadvantage of high manufacturing cost and failing to provide reliable safety.

Accordingly, there is a high demand for a technology capable of securing battery safety with high reliability due to a simpler structure.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

The inventors of the present application have described a battery pack having a low elongation linear member that surrounds the outer surface of a battery cell and has a mechanical fuse mounted in the middle of the linear member. It was confirmed that reliability can be improved by stopping operation of the battery as reliability, and the present invention has been completed.

Accordingly, the battery pack according to the present invention is a battery pack in which a plate-shaped battery cell is embedded in a pack case, and has a low elongation, a flexible linear member covering an outer surface of the battery cell, and a tensile force due to a volume change when the battery cell is expanded. It comprises a mechanical fuse connected to the electrode terminal in a state in which both ends are connected to the linear member so as to be concentrated and cut.

That is, the battery pack according to the present invention achieves a short circuit by the tension force is concentrated in the mechanical fuse during expansion due to the abnormal operation of the battery cell, while ensuring the safety of the battery with high reliability while suppressing the increase in the internal resistance due to the installation of the fuse It is characterized by the fact that it can be done.

The plate-shaped battery cell is a battery cell having a plate-like structure in which the electrode assembly of the anode / separation membrane / cathode is embedded in a case, and preferably, a rectangular battery cell and a pouch-type battery cell are mentioned. A rectangular battery cell is generally a battery in which an electrode assembly is enclosed in a rectangular metal can and sealed, and a pouch type battery cell is an electrode assembly in a pouch type case of a laminate sheet (for example, an aluminum laminate sheet) including a resin layer and a metal layer. It is a battery sealed by the built-in. The pouch-type battery cell is particularly preferable for the battery pack of the present invention, in addition to the advantages of low weight, low manufacturing cost, and easy deformation, since the pouch-type battery cell has low resistance to expansion compared to a rectangular metal can.

Since the linear member is made of a material having a low elongation, the linear member hardly experiences a change in length when the battery cell is expanded. On the other hand, since the member is flexible in a linear form, it can be wrapped in a state of being in close contact with the outer surface of the battery cell, and can be maintained in a close state according to the outer surface shape of the battery cell even when the battery cell is expanded. Therefore, when the volume increases due to the expansion of the battery cell, the tensile force can be concentrated in the mechanical fuse.

In one preferred embodiment, the linear member is a band made of a low elongation and a flexible linear electrically insulating material, the mounting position is set to horizontally wrap the middle portion of the battery cell. The area with the largest volume change during expansion of the battery cell may be sensitive to expansion because it is an intermediate portion.

As described above, the mechanical fuse is connected to the electrode terminal with both ends thereof connected to the preceding member. Such a connection method may vary. One of the electrode terminals of the battery cell (positive electrode terminal or negative electrode terminal) is connected to the protection circuit module (PCM) after passing through a mechanical nickel fuse, or the positive terminal of the battery cell. The anode and the cathode of the PCM may be connected via a mechanical fuse while the and cathode terminals are connected to the PCM, respectively.

The structure of the mechanical fuse may also vary, for example, a metal sheet having a relatively thin thickness, a metal flake having a notch or a slit formed in an intermediate portion thereof, and the like. Fuses of this structure are distinguished from thermal fuses in that they are mechanically broken when a tensile force is applied.

The mechanical fuse may be mounted on the outer surface of the battery cell as its both ends are connected to the linear member, and in some cases, it can be more stably attached to the outer surface of the battery cell using a double-sided tape.

Mechanical fuses may be included in two or more in order to increase the sensitivity to the expansion of the battery cell, for example, may be connected to the linear member in the state positioned in the center of the front and rear of the battery cell, respectively.

Hereinafter, the present invention will be further described with reference to the drawings according to embodiments of the present invention, but the scope of the present invention is not limited thereto.

4 and 5 schematically show a plan view and a perspective view, respectively, of a structure in which a mechanical fuse is attached to the front center of a battery cell according to one embodiment of the present invention.

Referring to these drawings, first, the pouch type battery cell 100 is manufactured by sealing an electrode assembly in a pouch type case of an aluminum laminate sheet. In the sealing process, both sealing parts 110 and the upper sealing part 120 are formed, and both sealing parts 110 are bent vertically upward to closely contact the main body 130, and the upper sealing part 120 has a PCM ( 200) is mounted. The PCM 200 includes electrode terminals of the battery cell 100 and includes external input / output terminals.

The mechanical fuse 300 is mounted on an outer surface of the battery cell 100 in a state of being connected to a band 310 which horizontally surrounds an intermediate portion of the battery cell 100.

The electrode terminals (not shown) of the battery cell 100 are connected to the PCM 200, and the positive terminal 210 and the negative terminal 220 of the PCM 200 are mechanically connected through the wires 320 and 322. It is connected via the fuse 300. Therefore, when the mechanical fuse 300 is destroyed, the operation of the battery is stopped.

6 schematically shows a vertical cross-sectional view of a linear member surrounding the outer surface of a battery cell and a mechanical fuse connected thereto according to the present invention.

Referring to FIG. 6, the band 310 as a linear member surrounds the entire lower surface of the battery cell 100 and a part of both sides and the upper surface thereof, and the mechanical fuse 300 has both ends thereof connected to the band 310. In the state is located in the center of the upper surface of the battery cell 100.

Since the band 310 is a linear member made of a thin material, it is flexible and closely adhered to the outer surface of the battery cell 100. However, the band 310 is made of a material having a very low elongation. Maintaining close contact while changing according to the outer surface shape of). Therefore, the tensile force due to the expansion of the battery cell 100 is concentrated on the mechanical fuse 300, the destruction occurs.

The foregoing has been described above with reference to some embodiments according to the present invention, but those skilled in the art to which the present invention pertains to various applications and modifications within the scope of the present invention based on the above information. It will be possible.

As described above, the battery pack according to the present invention has an effect of securing safety by stopping the operation of the battery is destroyed when the battery cell is expanded with high reliability without increasing the internal resistance.

Claims (8)

A battery pack in which a plate-shaped battery cell is embedded in a pack case, the flexible linear member surrounding the outer surface of the battery cell, and both ends connected to the linear member so that the tensile force is concentrated and cut according to the volume change when the battery cell is expanded. It consists of a mechanical fuse connected to the electrode terminal in a state, the linear member of the elongation and flexible linear to maintain a close state while changing according to the outer shape of the battery cell without changing the length when the battery cell expansion A band made of an electrically insulating material, characterized in that the battery pack is mounted to horizontally wrap the middle portion of the battery cell. The battery pack according to claim 1, wherein the plate-shaped battery cell is a square battery cell or a pouch-type battery cell. delete The battery pack according to claim 1, wherein one of the electrode terminals of the battery cell is connected to a protection circuit module (PCM) after passing through a mechanical fuse. The battery pack according to claim 1, wherein the positive electrode and the negative electrode of the PCM are connected via a mechanical fuse while the positive terminal and the negative terminal of the battery cell are connected to the PCM, respectively. The battery pack as claimed in claim 1, wherein the mechanical fuse is a metal sheet or a metal flake having a notch or a slit formed at an intermediate portion thereof. The method of claim 1, wherein the mechanical fuse is a battery pack, characterized in that attached to the outer surface of the battery cell using a double-sided tape. The method of claim 1, wherein the mechanical fuse is a battery pack, characterized in that connected to the linear member at the center of the front and rear of the battery cell.

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