KR101486840B1 - Pouch for secondary battery and secondary battery using the same - Google Patents

Abstract

The present invention provides a pouch for a secondary electrode which includes a case body and a cover, capable of preventing explosion and ignition. Wherein, the outer side of the case body is bonded to the outer side of the cover. The pouch for the secondary electrode further includes a safety belt which includes a core rod which is arranged to form the direction of a long axis thereof in a transverse direction of the outer side and a thermoplastic resin matrix which surrounds the core rod and has a thermal expansion coefficient which is different from the thermal expansion coefficient of the core rod, on at least one part of the outer side which is bonded.

Description

TECHNICAL FIELD [0001] The present invention relates to a pouch for a secondary battery, and a secondary battery using the same. BACKGROUND OF THE INVENTION [0002]

The present invention relates to a pouch for a secondary battery and a secondary battery using the same.

BACKGROUND ART [0002] Generally, a secondary battery is a battery capable of charging and discharging, and is widely used in high-tech electronic devices such as a mobile phone, a notebook computer, and a camcorder. Particularly, the lithium secondary battery has a three times higher operating voltage than the nickel-cadmium (Ni-Cd) battery and the nickel-hydrogen (Ni-MH) battery which are widely used as power sources for electronic equipment and has excellent energy density per unit weight A lot of research and development is going on.

Such a lithium secondary battery can be classified into a liquid electrolyte cell and a polymer electrolyte cell depending on the type of the electrolytic solution. In general, a battery using a liquid electrolyte is referred to as a lithium ion battery, and a battery using a polymer electrolyte is referred to as a lithium polymer electrolyte It is called.

A general lithium ion battery is composed of an electrode assembly having a porous positive electrode collector and a negative electrode collector and a separator alternately stacked one upon another, and a shell outer shell that accommodates the electrode assembly and the electrolyte. Such a battery cell may be divided into a can type battery cell or a pouch type battery cell depending on the shape of the cell exterior material.

2. Description of the Related Art Unlike a primary battery, a secondary battery capable of charging and discharging is under active research due to development of advanced fields such as a digital camera, a cellular phone, a notebook computer, and a hybrid vehicle. Examples of the secondary battery include a nickel-cadmium battery, a nickel-metal hydride battery, a nickel-hydrogen battery, and a lithium secondary battery. Among them, a lithium secondary battery is used as a power source for portable electronic devices at an operating voltage of 3.6 V or more, or several series are connected in series to be used in a high-output hybrid automobile. In a nickel-cadmium battery or a nickel-metal hydride battery The operating voltage is three times higher and the energy density per unit weight is also excellent. Thus, the use thereof is rapidly increasing.

The lithium secondary battery can be manufactured in various forms. Typical examples of the lithium secondary battery include a cylinder type and a prismatic type, which are mainly used in a lithium ion battery. In recent years, a lithium polymer battery has been manufactured in a pouch type having flexibility and its shape is relatively free. In addition, the lithium polymer battery is excellent in safety and light in weight, which is advantageous for slimmer and lighter weight of portable electronic devices.

As shown in FIG. 1, the pouch type secondary battery includes an electrode assembly 20 for generating a predetermined current, and a pouch 10 for sealing and sealing the electrode assembly 20. A lead 17 serving as an electrical path to the outside is connected to the electrode tab 14 extending from one side of the electrode assembly 20. The lead 17 has an electrode tape 16, And is partially protruded to the outside of the pouch 10.

The pouch 10 includes a case body 12 having an internal space for accommodating the electrode assembly 20 and a lid 11 covering the case body 12. The case body 12 and the outer frame 15 of the lid 11 are bonded to each other to seal the pouch 10.

On the other hand, when the voltage inside the secondary battery rises due to overcharging, gas may be generated, which may cause expansion and explosion. Particularly, the lithium ion battery has a problem that the liquid electrolyte is decomposed by overcharging and releases gas such as carbon dioxide or carbon monoxide, thereby raising the internal pressure of the battery. Further, if an overcurrent flows due to overdischarge or short-circuit, the temperature inside the battery rises and the liquid electrolyte changes into gas, thereby increasing the pressure and temperature inside the battery. Especially, there is a danger of ignition, come.

In addition, such a secondary battery can be used safely in accordance with a temperature condition at the time of charging and a temperature condition at the time of use. In a case where the environment for use is severe, that is, when the temperature at the time of charging / discharging is excessively high, If the operating temperature is too high, this external temperature condition may increase the temperature of the battery and cause explosion or ignition.

Accordingly, various types of safety devices capable of preventing explosion have been proposed in the secondary battery.

For example, Korean Patent Laid-Open No. 2004-0017094 discloses a pouch-type secondary battery having a safety valve to prevent explosion and ignition of the battery.

However, in the case of a safety valve including an opening provided with a polyethylenic resin material disclosed in Korean Patent Laid-Open Publication No. 2004-0017094, it is difficult to predict the breaking point, the melting point of the open piece can not be controlled, There is a drawback that a vent may not actually be formed at a portion where the opening is present.

Korean Patent Publication No. 2004-0017094

An object of the present invention is to provide a pouch for a secondary battery which can prevent unexpected explosion and ignition when the internal temperature of the secondary battery rises above a reference value, the safety vent portion is opened and the gas inside the battery is discharged.

Another object of the present invention is to provide a pouch for a secondary battery, which has a safety vent portion capable of providing a consistent vent when the battery is overheated.

It is still another object of the present invention to provide a pouch for a secondary battery having a safety vent portion that can be installed without limitation in position.

Claims [1] A method of manufacturing a semiconductor device, comprising: a case body and a lid each of which is connected to each other at an outer portion thereof, wherein at least a portion of the outer frame portion to be joined includes a core rod having a major axis direction disposed in a width direction of the outer frame portion, Further comprising a safety vent portion including a thermoplastic resin matrix having a coefficient of thermal expansion different from that of the rod.

2. The pouch for a secondary battery according to 1 above, wherein the core rod has a melting point higher than that of the thermoplastic resin matrix.

3. The pouch for a secondary battery as in 1 above, wherein the core rod comprises at least one material selected from the group consisting of metals, ceramics, polymers and glass.

4. The pouch for a secondary battery according to 1 above, wherein the core rod has a circular, elliptical or polyhedral cross-section.

5. The pouch for a secondary battery as in 1 above, wherein the thickness of the core rod is equal to or smaller than the thickness of the thermoplastic resin matrix.

6. The pouch for a secondary battery as in 1 above, wherein the length of the core rod is equal to or smaller than the length in the width direction of the outer frame to be joined.

7. The pouch for a secondary battery as in 1 above, wherein the core rod is provided in the thermoplastic resin matrix in plurality.

8. The pouch for a secondary battery according to 1 above, wherein the thermoplastic resin matrix has a melting point lower than that of the material forming the case body and the lid.

9. The pouch for a secondary battery as described in 1 above, wherein, when the internal temperature of the pouch is equal to or higher than a preset vent operating temperature, a gap between the core rod of the safety vent and the thermoplastic resin matrix is communicated with the inside and the outside of the pouch.

10. The secondary battery according to claim 1, wherein, when the internal temperature of the pouch is equal to or higher than a predetermined vent operating temperature and the pressure inside the pouch reaches the vent pressure, the thermoplastic resin matrix of the safety vent is melted and the core rod is discharged to the outside of the pouch. pouch.

11. A pouch type secondary battery comprising a pouch of any one of items 1 to 10 and an electrode assembly housed inside the pouch.

Since the core pouch and the thermoplastic resin matrix have different thermal expansion coefficients, the core rod and the surrounding thermoplastic resin are separated from each other when the inside of the pouch becomes hot, From this, the gas inside the pouch is discharged to prevent explosion, ignition, etc. of the battery.

In addition, the pouch for a secondary battery according to the present invention has an advantage that a safety vent can be installed regardless of the position of the pouch in an outer portion of the pouch.

Further, in the secondary battery pouch according to the present invention, when the pressure inside the battery rises at a high temperature, the core rod is released to the outside of the pouch by the internal pressure, so that a more reliable vent can be realized.

1 is a perspective view showing a schematic structure of a conventional pouch type secondary battery.
2 is a perspective view schematically showing an embodiment of a secondary battery including the pouch and the pouch according to the present invention.
3 is a schematic view showing an embodiment of the operation mechanism of the safety vent according to the present invention.
4 is a cross-sectional view (a), a front view (b) and a side sectional view (c) schematically showing one embodiment of the safety vent portion according to the present invention.
5 is a view schematically showing another embodiment of the operation mechanism of the safety vent according to the present invention.

The present invention relates to a method of manufacturing a semiconductor device, which comprises a case body and a cover in which respective outer portions are mutually bonded, and at least one portion of the outer frame portions to be joined surrounds a core rod whose major axis direction is arranged in the width direction of the outer frame portion, And a safety vent portion including a thermoplastic resin matrix having a thermal expansion coefficient different from that of the core rod. Thus, the present invention provides a pouch for a secondary battery that can prevent explosion and ignition.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. And shall not be construed as limited to such matters.

FIG. 2 is a schematic view of an embodiment of a pouch 100 according to the present invention and an electrode assembly 200 accommodated therein.

After the electrode assembly 200 is housed in the pouch 100, the pouch type secondary battery is constructed by sealing the case body 110 and the outer shell of the lid 120 by sealing. The pouch 100 is provided with a safety vent portion 150 on at least one portion of the outer frame to be joined.

The safety vent portion 150 includes a core rod 151 and a thermoplastic resin matrix 152 surrounding the core rod 151. Under normal conditions the thermoplastic resin matrix 152 seals the pouch together with the outer shell portion The core rod 151 binds the core rod 151 and contributes to maintaining the mechanical rigidity of the safety vent portion 150.

FIG. 3 schematically shows an embodiment of the operation mechanism of the safety vent unit 150 according to the present invention. Referring to FIG. 3, the core rod 151 and the thermoplastic resin matrix 152 having different thermal expansion coefficients have a temperature rise inside the pouch 151, and the core rod 151 and the thermoplastic resin matrix 152 have different thermal expansion coefficients. (Or shrinkage) is different from each other, a gap is generated at the interface which is in contact with each other. At this time, since the core rod 151 is disposed so as to be parallel to the width direction of the outer frame portion, the gap is formed in the outer direction inside the pouch. Accordingly, it is possible to prevent the explosion and ignition of the battery by providing a vent that can exhaust the generated gas and heat to the outside of the pouch.

The thermal expansion coefficient of each of the core rod 151 and the thermoplastic resin matrix 152 can be determined by selecting a suitable material or the like. In addition to the type of the thermoplastic resin used, the thermoplastic resin matrix 152 may have thermal expansion Coefficient or melting point may vary.

Thus, the vent operating temperature at which the safety vent 150 according to the present invention operates can be preset in accordance with the adjustment of the thermal expansion coefficient and the melting point of the core rod 151 and the thermoplastic resin matrix 152. Accordingly, when the temperature inside the pouch becomes equal to or higher than the vent operating temperature, the gap between the core rod 151 and the thermoplastic resin matrix 152 can be formed to communicate with the inside and the outside of the pouch, So that the generated gas and heat can be discharged to the outside.

In this respect, it may be preferable that the core rod 151 has a melting point higher than that of the thermoplastic resin matrix 152. For example, the core rod 151 may include at least one material selected from the group consisting of metals, ceramics, polymers, and glass. The material of the core rod 151 is not particularly limited and may be used as a material of the core rod 151. For example, But is not limited thereto.

Fig. 4 shows a cross-sectional view (a), a front view (b) and a side sectional view (c) schematically showing an embodiment of the safety vent portion of the present invention.

The cross-sectional shape of the core rod 151 is not particularly limited, and may be, for example, a circle, an ellipse or a polyhedron. Specific examples of the polyhedron include triangles, squares, pentagons, hexagons, and octagons.

It is desirable that the thickness of the core rod 151 does not exceed the thickness of the thermoplastic resin matrix 152. Therefore, the thickness of the thermoplastic resin matrix 152 may be equal to or less than the thickness of the thermoplastic resin matrix 152, and more preferably, it may be less than the thickness of the thermoplastic resin matrix 152. When the thickness of the core rod 151 is smaller than the thickness of the thermoplastic resin matrix 152, the contact area with the thermoplastic resin matrix 152 can be maximized, thereby making it possible to more effectively form the vent.

The length (long axis direction) of the core rod 151 may be equal to or less than the length of the outer frame 121 to be joined (the direction in which the outer frame portion crosses the outside from the inside of the pouch). Preferably the same as the length in the width direction of the outer frame 121, may be more effective for forming the vent.

If necessary, a plurality of core rods 151 may be provided in the thermoplastic resin matrix. In the case where a plurality of core rods 151 are provided, it may be preferable to strengthen the mechanical strength of the safety vent 150 in a steady state, and more vent may be formed during operation of the safety vent, It may be preferable to the soot.

The thermoplastic resin matrix 152 contributes to the sealing of the pouch together with the outer shell 121 under normal conditions. Since the joining of the outer frame part 121 is usually performed by press bonding the joining surfaces of the case body 110 and the lid 120, the thermoplastic resin matrix 152 according to the present invention, Not only can it be used for joining the part 121, but also can be arranged irrespective of the position of the outer frame 121. Accordingly, the safety vent 150 according to the present invention can be disposed at the outer frame 121 regardless of the position, and can be disposed at two or more locations, if necessary.

The thermoplastic resin forming the thermoplastic resin matrix 152 is not particularly limited as long as it is a thermoplastic resin known in the art. For example, polyethylene, polypropylene and the like can be used, but the present invention is not limited thereto.

The melting point of the thermoplastic resin matrix 152 is preferably lower than that of the material forming the case body 110 and the lid 120. The melting point of the thermoplastic resin matrix 152 is set so that the metal layer of the case body 110 and the metal layer of the cover 120 and the polymeric resin layer are laminated. A lower melting point than the ground layer is preferable from the viewpoint that the safety vent portion 150 can operate before the pouch 100 is damaged.

FIG. 5 schematically shows another embodiment of the operation mechanism of the safety vent portion 150 according to the present invention.

Generally, the heat generation inside the pouch may be accompanied by an increase in the internal pressure. The increase in the internal pressure of the pouch is mostly caused by the generation of gas due to decomposition of the electrolytic solution or electrolyte contained therein. When the temperature and the pressure inside the pouch are elevated at the same time, the safety vent portion 150 according to the present invention can realize an effective explosion and ignition prevention mechanism.

5, when the internal temperature of the pouch 100 is equal to or higher than a preset vent operating temperature and the pressure inside the pouch reaches the vent pressure, the thermoplastic resin matrix 152 of the safety vent 150 is melted, The rod 151 can be discharged outside the pouch.

If the internal temperature of the pouch is above the vent operating temperature, the vent operating mechanism is as described above. That is, the gap formed between the core rod 151 and the thermoplastic resin matrix 152 lowers the bonding force between the thermoplastic resin matrix 152 and the core rod 151, and in this embodiment in which the pouch internal pressure increases accordingly The core rod 151 can be discharged to the outside of the pouch by the internal pressure. The empty space of the safety vent 150 generated as the core rod 151 is discharged can more effectively cope with heat generation inside the pouch and resolution of the internal pressure.

The vent pressure of the safety vent 150 can be appropriately determined by selecting the specific material type of each of the core rod 151 and the thermoplastic resin matrix 152, the thickness of the core rod 151, and the like. Therefore, it is possible to control the vent pressure according to the specific use of the battery to be used.

Other than the safety vent portion 150 of the pouch 100 according to the present invention, configurations other than those known in the art can be adopted without any particular limitation.

The case body 110 and the cover 120 may include a metal layer, a heat-sealable layer formed on one surface of the metal layer, and an insulating layer formed on the other surface of the metal layer.

The metal layer functions to prevent moisture from entering the battery from the outside and to maintain the phenomenon after forming. The metal layer may be, for example, aluminum, stainless steel, iron, copper or nickel. Of these, aluminum is light in weight and excellent in the function of blocking moisture. The metal layer may be formed of one kind of metal, or may be formed by integrating two or more types of metal layers.

The heat-sealable layer may be formed of CPP (Cast Polypropylene) or PPA (Poly Phthal Amide). The case body 110 and the lid 120 are arranged such that the heat-sealable layers are in contact with each other, and the heat-sealable layers are bonded (heat-sealed) to each other to realize sealing of the pouch.

The insulating film layer may be made of any one of nylon and polyethylene terephthalate, but is not limited thereto. If necessary, the insulating film layer may be formed of a plurality of layers. In this case, a resin layer such as polyethylene, polypropylene, or polyethylene terephthalate may be further provided on the outside of nylon or polyethylene terephthalate.

The present invention provides a pouch type secondary battery including the above-described pouch and an electrode assembly housed therein.

The electrode assembly 200 is disposed in the order of a positive electrode plate, a separator, and a negative electrode plate, and wound in one direction, or a plurality of positive electrode plates, a separator, and a negative electrode plate laminated. Each electrode plate of the electrode assembly 200 is electrically connected to the positive and negative electrode tabs 211 and 212.

In the electrode plate, one end of the positive electrode tab 211 and the negative electrode tab 212 protrude outwardly through a lead 230. One end of the protruded lead 230 is connected to an external terminal not shown.

Each electrode tape 220 is attached to the outer surface of the lead 230 in order to prevent electrical short-circuiting between the case body 110 and the lid 120 and the lead 230 at a portion contacting the outer frame 121 It is wound.

The pouch type secondary battery according to the present invention can be coupled to a battery pack. The battery pack may include a power tool; Electric vehicles such as Electric Vehicle (EV), Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV); An electric motorcycle such as an E-bike or an Escooter; Electric golf cart; Electric truck; And electric commercial vehicles.

100: Pouch 110: Case body
120: cover 150: safety vent
151: core rod 152: thermoplastic resin matrix part
210: electrode tab 220: electrode tape
230: Leads

Claims (11)

A case body and a cover in which respective outer portions are mutually bonded,
And a safety vent portion surrounding the core rod and including a thermoplastic resin matrix having a thermal expansion coefficient different from that of the core rod, at least a portion of the outer circumferential portion to be joined, the core rod having a major axis direction disposed in the width direction of the outer frame portion , Pouch for secondary battery.
The pouch for a secondary battery according to claim 1, wherein the core rod has a melting point higher than that of the thermoplastic resin matrix.
The secondary battery pouch of claim 1, wherein the core rod comprises at least one material selected from the group consisting of metal, ceramic, polymer, and glass.
The pouch for a secondary battery according to claim 1, wherein the core rod has a circular, elliptical or polyhedral cross-section.
The secondary battery pouch according to claim 1, wherein a thickness of the core rod is equal to or smaller than a thickness of the thermoplastic resin matrix.
The secondary battery pouch according to claim 1, wherein a length of the core rod is equal to or smaller than a length in the width direction of the outer frame to be joined.
The secondary battery pouch according to claim 1, wherein the core rod is provided in the thermoplastic resin matrix in plurality.
The pouch for a secondary battery according to claim 1, wherein the thermoplastic resin matrix has a melting point lower than that of the material forming the case body and the lid.
The secondary battery pouch according to claim 1, wherein when the internal temperature of the pouch is equal to or higher than a preset vent operating temperature, the core rod of the safety vent portion and the thermoplastic resin matrix are separated from each other so as to communicate the inside and the outside of the pouch.
The secondary battery pouch of claim 1, wherein the thermoplastic resin matrix of the safety vent is melted and the core rod is discharged outside the pouch when the internal temperature of the pouch is equal to or higher than a preset vent operating temperature and the internal pressure of the pouch reaches the vent pressure.
A pouch type secondary battery comprising a pouch according to any one of claims 1 to 10 and an electrode assembly housed inside the pouch.

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