KR20130048419A - Secondary battery in pouch type - Google Patents

Abstract

PURPOSE: A pouch type secondary battery is provided to discharge inner gas from a battery through a safety vent when the internal temperature of the secondary battery is abnormally increased, thereby preventing explosion and ignition of the battery. CONSTITUTION: A pouch type secondary battery(1000) comprises a battery assembly(130); a pouch case(140) which accommodates a battery assembly; upper and lower laminate sheets which compose the pouch case; a sealing part(151-154) formed by heat sealing the upper and lower laminate sheets; a positive and negative electrode tab(110,120) exposed to the outside of the sealing part; and a safety vent(170) which is formed to dissolve alloy at a specific temperature by inserting an alloy which has a lower melting point than the sealing part, between the upper and lower laminate sheets.

Description

Pouch type secondary battery {Secondary battery in pouch type}

The present invention relates to a pouch type secondary battery, and more particularly, to a pouch type secondary battery having a safety vent having a lower melting point than the upper and lower laminates constituting the sealing portion to prevent explosion and ignition of the secondary battery. .

In general, secondary batteries are batteries that can be charged and discharged, and are widely used in the field of advanced electronic devices such as mobile phones, notebook computers, and camcorders. In particular, lithium secondary batteries have three times higher operating voltage and better energy density per unit weight than nickel-cadmium (Ni-Cd) batteries or nickel-hydrogen (Ni-MH) batteries, which are widely used as power sources for electronic equipment. Many research and development are in progress.

The lithium secondary battery may be classified into a liquid electrolyte battery and a polymer electrolyte battery according to the type of electrolyte. Generally, a battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery. It's called

A typical lithium ion battery cell includes an electrode assembly having a porous positive electrode current collector, a negative electrode current collector, and a separator alternately overlapping each other, and a cell packaging material containing the electrode assembly and the electrolyte. Such battery cells may be classified into can type battery cells or pouch type battery cells, depending on the shape of the cell exterior material.

In general, unlike the primary battery, the rechargeable battery that is capable of charging and discharging is being actively researched due to the development of high-tech fields such as a digital camera, a cellular phone, a notebook computer, and a hybrid vehicle. Examples of secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-hydrogen batteries, and lithium secondary batteries. Among them, the lithium secondary battery has a working voltage of 3.6 V or more and is used as a power source for portable electronic devices, or a series of several batteries are used in a high-output hybrid vehicle. 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 may be manufactured in various forms, and typical shapes include cylindrical and prismatic types that are mainly used in lithium ion batteries. Lithium polymer batteries, which are in the spotlight in recent years, have been manufactured in a flexible pouched type, and their shapes are relatively free. In addition, the lithium polymer battery has excellent safety and light weight, which is advantageous for slimmer and lighter portable electronic devices.

On the other hand, when the secondary battery is overcharged and the voltage inside thereof increases, gas may be generated to expand and explode. In particular, a lithium ion battery releases gases such as carbon dioxide and carbon monoxide as the liquid electrolyte decomposes due to overcharging, thereby increasing the internal pressure of the battery. In addition, when an overcurrent flows due to over-discharge or short circuit, the temperature inside the battery rises and the liquid electrolyte turns into a gas. Accordingly, the pressure and temperature inside the battery rise. In particular, there is a risk of ignition. come.

In addition, the secondary battery as described above can be safely used by keeping the temperature conditions at the time of charging and the temperature at the time of use. In the case of severe use environment, that is, the temperature at the time of charging / discharging is excessively high, If the operating temperature is too high, such external temperature conditions may increase the temperature of the battery, causing an explosion or fire.

Therefore, various types of safety devices for preventing explosions have been proposed.

For example, Korean Patent Publication No. 10-2004-0017094 (published on February 26, 2004) discloses a configuration of a pouch-type secondary battery having a safety valve to prevent explosion and fire of the battery.

However, in the case of a safety valve including an open piece provided with a polyethylene-based resin material, such as Korean Patent Publication No. 10-2004-0017094, it is difficult to predict the point of breakage, and it is impossible to control the melting point of the open piece so that it does not break at a desired temperature. There are disadvantages.

Korean Patent Publication No. 10-2004-0017094

The present invention has been made to solve the above problems, when the internal temperature of the secondary battery rises above the reference value due to overcharge, high temperature use, internal short circuit, etc., the safety vent is opened to discharge the gas inside the battery unexpectedly It is an object of the present invention to provide a pouch-type secondary battery that can prevent unexploded explosion and fire.

A pouch case accommodating a battery assembly and the battery assembly; Upper and lower laminate sheets constituting the pouch case; A sealing part formed by heat-sealing the upper and lower laminate sheets; Positive and negative electrode tabs exposed from the seal; And a safety vent formed so that the alloy having a lower melting point than the upper and lower laminate sheets is inserted between the upper and lower laminate sheets constituting the seal, so that the alloy is melted at a predetermined temperature. Type secondary battery.

In addition, a safety vent formed between the upper or lower laminate sheet and the tab tape is inserted so that the alloy having a lower melting point than the upper or lower laminate sheet is melted at a predetermined temperature; It is a pouch type secondary battery.

In addition, the safety vent is a pouch type secondary battery, characterized in that the inclined form of the width decreases toward the bottom.

In addition, the safety vent is a pouch type secondary battery, characterized in that any one or two or more of an inverted triangle, trapezoidal, V-shaped, U-shaped.

In addition, the melting point of the alloy is a pouch type secondary battery, characterized in that 100 to 250 ℃.

In addition, the alloy is a pouch type secondary battery comprising any one or more of silicon (Si), tin (Sn), zinc (Zn), lead (Pb), bismuth (Bi), indium (In). .

The pouch type secondary battery of the present invention has an advantage that the safety vent is opened when the internal temperature of the secondary battery rises above the reference value, and gas is discharged inside the battery to prevent the battery from igniting or exploding.

In addition, by controlling the melting point of the safety vent has the advantage that can be correctly designed when the safety vent opening.

1 is a plan view of a pouch type secondary battery according to a first embodiment of the present invention.
2 is a plan view of a pouch type secondary battery according to a second embodiment of the present invention.
3 is a plan view of a pouch type secondary battery according to a third embodiment of the present invention.
4 is a cross-sectional view of the pouch type secondary battery according to the first embodiment of the present invention.
5 is a plan view of a pouch type secondary battery according to a fourth embodiment of the present invention.
6 is a cross-sectional view of a pouch type secondary battery according to a fourth embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings the technical spirit of the present invention will be described in more detail.

The accompanying drawings are merely illustrative examples of the present invention in order to more particularly describe the technical idea of the present invention, and thus the technical idea of the present invention is not limited to the drawings.

1 is a plan view illustrating a pouch type secondary battery 1000 according to a first embodiment of the present invention. Referring to FIG. 1, a pouch type secondary battery 1000 according to a first embodiment of the present invention may include a pouch case 140 accommodating a battery assembly 130 and the battery assembly 130; Upper and lower laminate sheets 141 and 142 constituting the pouch case 140; Sealing parts (151, 152, 153, 154) formed by heat-sealing the upper and lower laminate sheets; Positive and negative electrode tabs 110 and 120 exposed from the seals 151, 152, 153 and 154; And an alloy having a lower melting point than the upper and lower laminate sheets 141 and 142 is inserted between the upper and lower laminate sheets 141 and 142 constituting the seals 151, 152, 153 and 154 to melt the alloy at a predetermined temperature. It is configured to include a safety vent (170).

1 and 4, the safety vent 170 is inserted between the upper and lower laminate sheets 141 and 142 constituting the seal 151, and the alloy is melted at a predetermined temperature. The gas inside the battery is discharged.

Referring to FIG. 1, the battery assembly 130 as described above is accommodated in the pouch case 140. The pouch case 140 includes an upper laminate sheet 141 and a lower laminate sheet 142 to seal the battery assembly 130. The battery assembly 130 is placed on the lower laminate sheet 142, the upper laminate sheet 141 is covered on the battery assembly 130, and then the upper laminate sheet 141 and the lower laminate sheet 142 are bonded to each other. Seals 151, 152, 153, 154 are formed. The seals 151, 152, 153, and 154 may be four as shown in FIG. 1. However, the shape of the pouch case 140 is not necessarily limited thereto.

2 is a plan view illustrating a pouch type secondary battery 1000 according to a second exemplary embodiment of the present invention. As shown in FIG. 2, a space portion for accommodating the battery assembly 130 is formed in the lower laminate sheet 142, and an upper laminate sheet 142 is formed by extending from the space portion of the lower laminate sheet 142. The upper laminate sheet 141 and the lower laminate sheet 142 are bonded to each other around the space to form the sealing portions 151, 152, and 153. In this case, three sealing parts 151, 152, and 153 are provided.

3 is a plan view illustrating a pouch type secondary battery 1000 according to a third embodiment of the present invention. As illustrated in FIG. 3, the battery assembly 130 may be accommodated in a bag-shaped pouch case 140 having one surface open and the surface thereof may be sealed. At this time, one sealing unit 151 is formed.

1 to 3, the safety vent 170 may be disposed on the sealing part 151 of the electrode tabs 110 and 120. However, the present invention is not limited thereto, and although not illustrated, the safety vent 170 may be formed in the entire sealing part 151, 152, 153, and 154, and in any one of the sealing parts 151, 152, 153, and 154. A plurality of safety vents 170 may be arranged.

The safety vent 170 shown in FIGS. 1 to 3 is disposed in the seal 151 and is made of an alloy having a lower melting point than the upper and lower laminate sheets 141 and 142. When the internal temperature of the secondary battery 1000 rises above the reference value due to overcharging, internal short circuiting, or the like, the safety vent 170 melts the alloy constituting the safety vent 170 to open the safety vent 170. do. At this time, the gas inside the battery is discharged to prevent explosion and fire. According to the present invention in detail, when the internal temperature of the secondary battery 1000 rises above a predetermined temperature and reaches the melting point of the safety vent 170, the safety vent 170 melts, whereby the safety vent 170 is present. Bonding strength of the sealing portion 151 is lower than other portions. Therefore, the sealing part 151 having the safety vent 170 is more vulnerable to pressure than the other sealing parts 152, 153, and 154, and the sealing part 151 having the safety vent 170 is ruptured. The gas inside the battery 1000 is discharged through the portion of the ruptured seal 151 to prevent the battery 1000 from igniting or exploding.

The upper and lower laminate sheets 141 and 142 forming the pouch case 140 of FIGS. 1 to 3 may be formed of a thin plate mixed with a metal material and a resin material as shown in FIG. 4. In detail, the upper laminate sheet 141 may be configured by laminating in order from the top to the bottom of the outermost coating layer 141a, the outer coating layer 141b, the barrier layer 141c of the metal foil, and the heat adhesive layer 141d. The lower laminate sheet 142 may be formed by laminating in order from the bottom to the outermost coating layer 142a, the outer coating layer 142b, the barrier layer 142c of metal foil, and the thermal adhesive layer 142d. Referring to the manufacturing process of the laminate sheet, the outermost coating layer, the outer coating layer, the barrier layer of the metal foil, the heat-adhesive layer is sequentially laminated, and then dried by interposing an adhesive between each of the one material and the other material using a heating roll Each material may be formed through a dry lamination method in which the material is bonded by a temperature and pressure higher than room temperature. Alternatively, the adhesive may be formed by an extrusion lamination method of interposing the one material and the other material between each other and then bonding each material by a predetermined pressure at room temperature using a pressing roll.

Since the respective constituent layers of the upper laminate sheet 141 and the respective constituent layers of the lower laminate sheet 142 are laminated in reverse, the heat adhesive layers 141d and 142d of the upper and lower laminate sheets 141 and 142 face each other. The upper and lower laminate sheets 141 and 142 are sealed by thermal compression while the thermal adhesive layers 141d and 142d of the upper and lower laminate sheets 141 and 142 are brought into contact with each other to seal the seals 151, 152, 153 and 154. ).

Referring to FIG. 4, the outermost coating layers 141a and 142a may be made of a polymer resin material such as PE, PP, and polyethylene terephthalate (PET). The outer coating layers 141b and 142b may be made of polyethylene naphthalate (PEN) or nylon (ONY). The barrier layers 141c and 142c of the metal foil may be made of aluminum or an aluminum alloy. The thermal adhesive layers 141d and 142d may be formed of cast polypropylene (CPP) or poly phthalamide (PPA).

Referring to FIG. 5, the pouch type secondary battery 1000 according to the fourth embodiment of the present invention may have a top laminate sheet 141 or a lower laminate sheet in the pouch type secondary battery 1000 of the first to third embodiments. A safety vent formed between the 142 and the tab tapes 161 and 162 by inserting an alloy having a lower melting point than the upper laminate sheet 141 or the lower laminate sheet 142 to melt the alloy at a predetermined temperature. 171) may be further included. Of course, the sealing part may be composed of four parts 151, 152, 153 and 154 as shown in FIG. 5, and three parts 151, 152 and 153 as shown in FIG. 2, and one part 151 as shown in FIG. 3. May be

The configuration of the upper and lower laminate sheets 142 and the sealing parts 151, 152, 153, and 154 is described above, and detailed description thereof will be omitted.

5, the tab tapes 161 and 162 are attached to prevent a short circuit between the pouch case 140 and the electrode tabs 110 and 120. Since the pouch type secondary battery 1000 uses a non-aqueous electrolyte solution therein, the electrode tabs 110 and 120, which serve to connect the battery elements to the outside, are sufficiently sealed at a portion where the electrode tabs 110 and 120 are bonded to the exterior material. It must be secured to prevent leakage of the electrolyte to the outside. In order to secure the sealing property of the pouch-type secondary battery 1000, the tab tapes 161 and 162 are adhered to the electrode tabs 110 and 120 to secure the sealing property. Preferably, the tab tapes 161 and 162 may be three-layer adhesive adhesive tab tapes 161 and 162 to which an adhesive is applied. In addition, in order to prevent short circuit of the electrode tabs 110 and 120, the tab tapes 161 and 162 have insulation. Preferably, the tab tapes 161 and 162 have a three-layer structure, and an outer layer is an adhesive surface to which an adhesive is applied, and a middle layer between the adhesive surfaces is made of an insulator of insulating material. The tab tapes 161 and 162 may be made of any one of polyethylene, polyacetylene, PTFE, nylon, polyacetylene, polyimide, polyethylene terephthalate, and polypropylene.

5, the safety vent 171 is formed of an alloy having a lower melting point than the upper laminate sheet 141 or the lower laminate sheet 142, and includes tab tapes 161 and 162 and a pouch case 140. It is disposed between the seal 151 of the). The safety vent 171 may be disposed on the negative electrode tab 110, or may be disposed on the positive electrode tab 110, and may be disposed on both the negative electrode and the positive electrode tabs 110 and 120. More specifically, referring to FIG. 6, the safety vent 170 may be disposed between the heat adhesive layer 141d of the upper laminate sheet 141 and the negative electrode tab tape 162. Or it may be disposed between the heat-adhesive layer 142d of the lower laminate sheet 142 and the negative electrode tab tape 162. Alternatively, the thermal bonding layer 141d of the upper laminate sheet 141 may be disposed between the positive electrode tab tape 161. Or it may be disposed between the heat-adhesive layer 142d of the lower laminate sheet 142 and the positive electrode tab tape 161.

5 and 6, when the internal temperature of the secondary battery 1000 rises above the reference value due to overcharging, high temperature use, internal short circuiting, and the like, gas is generated in the battery. Will expand. In severe cases, fire or explosion may occur inside the battery. Therefore, the gas inside the battery must be discharged before ignition and explosion occur.

According to the fourth embodiment of the present invention, when the internal temperature of the secondary battery 1000 rises above a predetermined temperature to reach the melting point of the safety vent 170, the safety vents 170 and 171 are melted, and thus the safety Bonding strength of the sealing part 151 having the vents 170 and 171 is lower than that of the other sealing parts 152, 153 and 154. The part with the safety vents 170 and 171 becomes more vulnerable to pressure than other parts inside the battery, and the part of the sealing part with the safety vents 170 and 171 is ruptured. The gas inside the battery is discharged through the portion of the broken seal so that the battery does not ignite or explode.

1 to 3 and 5, the safety vents 170 and 171 are configured in an inclined form in which the width decreases downwards. Preferably, the safety vents 170 and 171 have an inverted triangle, a trapezoid, and a V shape. It may be composed of any one or more of the form, U-shape, parabolic form. As described above, when the safety vents 170 and 171 are configured to be inclined, stress is concentrated in a narrow range, so that the seal is easily broken.

Preferably the alloy constituting the safety vent (170, 171) has a melting point of 100 to 250 ℃, the alloy is silicon (Si), tin (Sn), zinc (Zn), lead (Pb), bismuth (Bi) , Indium (In) may be formed including any one or more. As described above, when the safety vents 170 and 171 are formed of an alloy instead of a resin material, the dimensional strain is significantly reduced, and in the process of forming the safety vents 170 and 171, the process of injecting into the mold and solidifying the molding The post-processing process is much easier.

In addition, when the safety vent (170, 171) is composed of an alloy instead of a resin material as described above, since the melting point is determined according to the type and ratio of the metal material constituting the alloy, the alloy can be melted at a desired temperature. That is, the safety vents 170 and 171 are melted at a predetermined predetermined temperature, and thus a part of the sealing part 151 with the safety vents 170 and 171 is ruptured at a predetermined predetermined temperature, thereby discharging gas inside the battery. This prevents the battery from igniting or exploding. Therefore, by controlling the melting point of the safety vent (170, 171) there is an advantage that can accurately design the opening timing of the safety vent (170, 171)

1000: pouch type secondary battery.
110: positive electrode tab 120: negative electrode tab
130: battery assembly
140: pouch case
141: top laminate sheet
141a: outermost coating layer
141b: outer coating layer
141c: barrier layer of metal foil
141d: thermal adhesive layer
142: lower laminate sheet
142a: outermost coating layer
142b: outer coating layer
142c: barrier layer of metal foil
142d: thermal adhesive layer
151, 152, 153, 154: sealing portion
161, 162: tab tape
170: safety vent
171: safety vent

Claims (6)

A pouch case accommodating a battery assembly and the battery assembly;
Upper and lower laminate sheets constituting the pouch case;
A sealing part formed by heat-sealing the upper and lower laminate sheets;
Positive and negative electrode tabs exposed from the seal; And
A safety vent formed so that the alloy having a lower melting point than the upper and lower laminate sheets is inserted between the upper and lower laminate sheets constituting the seal, and the alloy is melted at a predetermined temperature. Secondary battery.
The method of claim 1,
And a safety vent formed between the upper or lower laminate sheet and the tab tape so that the alloy having a lower melting point than the upper or lower laminate sheet is inserted to melt the alloy at a predetermined temperature. Type secondary battery. The method according to claim 1 or 2,
The safety vent is a pouch type secondary battery, characterized in that the inclined form the width decreases toward the bottom. 4. The method of claim 3,
The safety vent is a pouch type secondary battery, characterized in that any one or two or more of an inverted triangle, trapezoidal, V-shaped, U-shaped, parabolic form. The method according to claim 1 or 2,
Pouch type secondary battery, characterized in that the melting point of the alloy is 100 to 250 ℃. The method according to claim 1 or 2,
The alloy is a pouch type secondary battery comprising any one or more of silicon (Si), tin (Sn), zinc (Zn), lead (Pb), bismuth (Bi), indium (In).

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