KR20170007876A - Battery Case Having Alloy of Low Melting Point and Battery Cell Comprising the Same - Google Patents

Abstract

The present invention relates to a battery case having alloy with a low melting point and a battery cell including the same. The battery cell of the present invention includes a pouch type battery case which has an electrode assembly embedded therein and of which the outer circumference surface is sealed by heat fusion. The battery case is formed of a laminated sheet having a structure in which the outer-most layer is made of a polymer resin, a blocking layer made of metal to block the inflow of foreign materials, and a sealant layer including a thermally adhesive resin are sequentially stacked, and includes an electrode assembly receiving unit. At least a portion of the sealant layer includes an alloy venting unit made of an alloy having a lower melting point than a thermally adhesive resin. In a region where the alloy venting unit is placed, a vertical cross section of the laminate resin has a structure in which the polymer resin of the outermost layer, the metal of the blocking layer, and the alloy with a low melting point of the alloy venting unit are sequentially stacked.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery case including a low-melting-point alloy,

The present invention relates to a battery case including a low melting point alloy and a battery cell including the same.

In recent years, the demand for environmentally friendly alternative energy sources has become an indispensable factor for the future, as the increase in the price of energy sources due to depletion of fossil fuels and the interest in environmental pollution are amplified. Various researches on power generation technologies such as nuclear power, solar power, wind power, and tidal power have been continuing, and electric power storage devices for more efficient use of such generated energy have also been attracting much attention.

Particularly, as technology development and demand for mobile devices increase, the demand for batteries as energy sources is rapidly increasing. Recently, the use of secondary batteries as a power source for electric vehicles (EV) and hybrid electric vehicles (HEV) In addition, the use area has been expanded for use as a power auxiliary power source through a grid, and accordingly, a lot of researches on a battery that can meet various demands have been conducted.

Typically, in terms of the shape of a battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a small thickness, and has advantages such as high energy density, discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

In particular, pouch-type batteries are attracting much attention due to their advantages such as small weight, low manufacturing cost and easy shape deformation because aluminum laminate sheets are used as exterior members.

FIG. 1 schematically shows an exploded perspective view showing a general structure of a typical conventional pouch type secondary battery.

1, a pouch type secondary battery 10 includes a stacked electrode assembly 20 having a plurality of electrode tabs 21 and 22 protruding therefrom, two stacked electrode assemblies 20 and 22 connected to the electrode tabs 21 and 22, And a battery case 40 having a structure in which the stacked electrode assembly 20 is received and sealed such that a part of the electrode leads 30 and 31 and a part of the electrode leads 30 and 31 are exposed to the outside.

The battery case 40 includes a lower case 42 including a concave shaped storage portion 41 on which the stacked electrode assembly 20 can be placed and a stacked electrode assembly 20 And an upper case 43 for sealing the upper case 43. The upper case 43 and the lower case 42 are thermally welded together with the stacked electrode assembly 20 built therein to form a sealing portion (not shown) along the outer circumferential surface of the battery case 40.

However, the pouch-type secondary battery 10 is manufactured by mutually thermally fusing the contact portions of the outer circumferential surface of the battery case 20 with the electrode assembly 30 mounted on the receiving portion of the battery case 20, When an abnormal operating condition such as an internal short circuit, an overcharge, or a high temperature is reached, the internal electrolyte is decomposed and a high-pressure gas is generated before the fused sealing portion melts. The generated high-pressure gas may cause deformation of the battery case, shortening the life of the battery, and seriously causing ignition or explosion of the battery.

Therefore, various attempts have been made to prevent the ignition or explosion of the battery and to discharge the gas efficiently when the high-pressure gas is generated. For example, in a battery in which an outer peripheral portion of a laminated film containing an electrode assembly is sealed by heat-sealing, a heat sealing condition is changed on one side of the outer periphery of the laminated film to be thermally fused or a width of a sealing portion to be heat- And a gas release mechanism.

However, this conventional technique merely weakens the sealing force to a specific portion of the sealing portion to which the high-pressure gas is discharged in order to discharge the high-pressure gas. Therefore, in the repeated charging / discharging process, There is a problem that moisture infiltration and electrolyte leakage may occur.

Accordingly, it is possible to prevent the battery cells from igniting or exploding by efficiently discharging the high-pressure gas that may occur due to unexpected situation development while preventing water infiltration and leakage of the electrolytic solution, There is a high need for a technique capable of ensuring the quality of the product.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments. As described later, at least a part of the sealant layer of the battery case is composed of an alloy venting portion of a low melting point alloy having a melting point lower than that of the heat- The vertical cross-sectional shape of the laminate sheet at the position where the alloy venting portion is located is a structure in which the polymer resin of the outermost layer, the metal of the barrier layer, and the low melting point alloy of the alloy venting portion are sequentially laminated, The high voltage gas inside the battery cell, which is generated due to side reaction of the electrode surface or part of the electrolyte component vaporizes during abnormal operation such as high temperature exposure, is efficiently discharged through the alloy venting portion, thereby reducing the risk of ignition or explosion of the battery It is confirmed that the safety is improved by intercepting in advance, and the present invention is completed Groups reached.

According to an aspect of the present invention, there is provided a battery cell comprising:

A battery cell in which an electrode assembly is embedded in a pouch-shaped battery case and an outer circumferential surface of the battery case is sealed by heat sealing,

The battery case is composed of a laminate sheet laminated in the order of an outermost layer made of a polymer resin, a barrier layer made of a metal that blocks the inflow of foreign substances, and a sealant layer containing a heat-sealable resin, ≪ / RTI >

Wherein at least a part of the sealant layer is made of an alloy venting portion of a low melting point alloy having a melting point lower than that of the heat-sealable resin, and a vertical sectional shape of the laminate sheet at a position where the alloy venting portion is located is formed of a polymer resin of the outermost layer, , And a low-melting-point alloy of an alloy venting portion are sequentially stacked.

Therefore, the battery cell according to the present invention is characterized in that at least a part of the sealant layer of the battery case is made of an alloy venting portion of a low melting point alloy having a melting point lower than that of the heat-sealable resin, When the shape is a structure in which the polymer resin of the outermost layer, the metal of the barrier layer, and the low-melting-point alloy of the alloy venting portion are sequentially stacked, in the abnormal operation of the secondary battery such as internal short circuit, overcharge, It is possible to effectively discharge the high-pressure gas inside the battery cell due to side reaction or vaporization of a part of the electrolytic solution component through the alloy venting portion, thereby preventing the risk of ignition or explosion of the battery, thereby improving safety .

In one specific example, the battery case may include an upper cover and a lower body made of a laminate sheet, and more particularly, the upper cover may be formed as a flat sheet, and the lower body includes an electrode assembly And the battery case may be integrally formed with one end of each of the upper cover and the lower body being connected to each other.

In one specific example, the polymer resin of the outermost layer may include at least one selected from the group consisting of ONy (stretched nylon) and polyethylene terephthalate (PET), and the blocking layer may be made of aluminum or an aluminum alloy And the heat sealable resin of the sealant layer may include at least one selected from the group consisting of polyethylene resin, ionomer resin and CPP (unleaded polypropylene).

In one specific example, the heat-sealable resin may have a melting point of from 130 degrees Celsius to 180 degrees Celsius, more specifically from 160 degrees Celsius to 170 degrees Celsius, and more specifically, 165 degrees Celsius.

Meanwhile, in the prior art pouch-shaped battery cell field, a technique for discharging gas generated inside the battery due to overheating to the outside, a chip-shaped alloy having a low melting point between the upper and lower sealant layers of the laminate sheet of the battery case The inserted structure has been disclosed.

However, in the structure in which a chip-shaped alloy having a low melting point is inserted between the upper and lower sealant layers of the prior art, it is very difficult to control the temperature at which the gas can be discharged. That is, even if the low melting point alloy located between the upper and lower sealant layers is melted at a predetermined temperature, the melt-bonded upper and lower sealant layers must be separated in order to discharge gas. For example, Even if an alloy having a melting point close to that of the sealant layer is used, gas discharge may occur when a large amount of gas is generated so that the sealant layers can be separated and the internal pressure of the cell is increased to a predetermined pressure. There is a problem.

On the other hand, the present invention replaces a portion of the sealant layer with an alloy venting portion of a low melting point alloy having a melting point lower than that of the heat-sealable resin, so that gas can be discharged at a specific temperature at which the gas is generated. The melting point of the low melting point alloy is melted and the bonding of the melted alloy venting portion is released, so that the internal gas can be discharged. In conclusion, the battery cell of the present invention is superior in temperature reliability to the prior art.

Accordingly, the battery cell according to the present invention may be an alloy having a melting point of 94 ° C. or more and less than 130 ° C., and the low melting point alloy may be an element Bi, Pb, Si, Sn, Zn , And In may be included.

More specifically, the low melting point alloy may be composed of the elements Bi and Pb, the content ratio of the element Bi: Pb may be 50:50 to 60:40, more specifically 55.5: 44.5, The melting point of the low melting point alloy may be 124 deg.

In another specific example, the low melting point alloy may be composed of the elements Pb, Sn and Bi, and the content ratio of the element Pb: Sn: Bi may be 25: 25: 50 to 28: 22: 50 , Wherein the melting point of the low melting point alloy can be from 94 to 98 degrees Celsius.

In one specific example, the forming area of the alloy venting portion may be formed to be 50% or more based on the total area of the sealing planned portion, which is the outer circumferential surface of the electrode assembly receiving portion, when the silane layer is viewed in a plan view before the heat fusion And more specifically may be formed to be 80% to 95% based on the total area of the sealing planned portion which is the outer circumferential surface of the electrode assembly receiving portion. In addition, the alloy venting portion may be formed so as to extend from the outer peripheral end of the sealant layer toward the electrode assembly receiving portion.

In another specific example, the alloy venting portion may be formed in the entirety of the sealing planned portion, which is the outer circumferential surface of the electrode assembly receiving portion, when the silane layer is viewed in a plan view before the heat fusion.

In another specific example, the alloy venting portion may be a structure formed continuously in a range of 5% to 30% of the entire peripheral length of the outer circumferential surface of the electrode assembly receiving portion. At this time, the alloy venting portion may be formed in a plane in the width direction of a portion to be sealed, which is an outer circumferential surface of the electrode assembly receiving portion.

In another specific example, the alloy venting portion may be a structure formed continuously to one side end of the battery case at a corresponding position between the positive electrode lead and the negative electrode lead.

In yet another specific example, the alloy venting portion may be located at one end of the battery case extending vertically from one end of the battery case in which the positive electrode lead and the negative electrode lead are respectively formed.

The present invention also provides a battery pack comprising the battery cell.

The present invention also provides a device including the battery pack as a power source. Specifically, the device can be, for example, a mobile phone, a portable computer, a wearable electronic device, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, And a storage device.

The structure and manufacturing method of such a device are well known in the art, so a detailed description thereof will be omitted herein.

As described above, in the battery cell of the present invention, at least a part of the sealant layer of the battery case is made of an alloy venting portion of a low melting point alloy having a melting point lower than that of the heat-sealable resin, and a portion of the laminate sheet The vertical cross section is formed in a structure in which the polymer resin in the outermost layer, the metal in the barrier layer, and the low melting point alloy of the alloy venting section are sequentially stacked. Thus, in the abnormal operation of the secondary battery such as internal short circuit, overcharge, It is possible to efficiently discharge the high-pressure gas inside the battery cell due to side reaction of the surface or vaporization of a part of the electrolyte components, thereby effectively preventing the ignition or explosion of the battery from being ignited, I will exert.

1 is an exploded perspective view showing a general structure of a typical pouch type secondary battery of the related art;
2 is a schematic plan view showing a battery cell having an alloy venting part according to one embodiment of the present invention;
3 is a schematic cross-sectional view showing a part of the battery cell of FIG. 2;
4 is a schematic cross-sectional view of the battery cell of FIG. 2;
5 is a schematic plan view showing a battery cell having an alloy venting portion according to another embodiment of the present invention;
FIG. 6 is a schematic sectional view showing a part of the battery cell of FIG. 5; FIG.
7 is a schematic plan view showing a battery cell according to another embodiment of the present invention;
8 is a schematic plan view showing a battery cell according to another embodiment of the present invention.

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

FIG. 2 is a schematic plan view of a battery cell having an alloy venting portion according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a portion of the battery cell of FIG. 4 schematically shows a cross-sectional view of the battery cell of Fig. 2.

2, an electrode assembly (not shown) is embedded in a pouch-type battery case 110, and an outer circumferential surface of the battery case 110 is heat-sealed to form a sealing part (not shown) 125 are formed.

3, the battery case 110 includes the outermost layers 130 and 131 made of a polymer resin, the barrier layers 132 and 133 made of a metal that blocks the inflow of foreign materials, And sealant layers 134 and 135 including a sealant layer 144 are stacked in this order.

At least a part of the sealant layers 134 and 135 is composed of an alloy venting part 200 of a low melting point alloy having a melting point lower than that of the heat sealable resin 144. In a region where the alloy venting part 200 is located, The vertical sectional shape of the sheet has a structure in which the polymer resin of the outermost layers 130 and 131, the metal of the barrier layers 132 and 133, and the low melting point alloy of the alloy venting portion 200 are sequentially stacked .

Therefore, the battery cell 100A according to the present invention can be manufactured by using a low-melting-point alloy before the sealant layers 134 and 135 as the heat of the battery becomes worse during abnormal operation such as internal short-circuiting, overcharging, The generated alloy venting portion 200 is melted and the generated gas is discharged while the fusion of the melted alloy venting portion is released due to the internal pressure of the high-pressure gas generated due to side reaction of the surface of the electrode or vaporization of a part of the electrolyte component.

Referring to FIG. 4, the battery case 110 includes an upper cover 116 and a lower body 117, which are laminated sheets. At this time, the upper cover 116 has a flat sheet shape, 117 are formed with a receiving portion 115 for receiving the electrode assembly 220. [

3, the polymer resin of the outermost layers 130 and 131 of the battery case 100 of FIG. 3 is ONy (stretched nylon), the barrier layers 132 and 133 are made of aluminum, The thermally fusible resin of the layers 134 and 135 is made of CPP (unleaded polypropylene). At this time, the melting point of CPP (unleaded polypropylene) is 165 degrees Celsius.

The low melting point alloy of the alloy venting part 200 formed on the sealant layers 134 and 135 is composed of the elements Bi and Pb, and the content ratio of the element Bi: Pb is 55.5: 44.5. The melting point of the low- Is 124 degrees Celsius.

The alloy venting portion 200 of the battery cell 100A shown in Fig. 2 has a structure in which when the silane layer 134 is viewed in a plan view before the thermal fusion, Is formed in the first half (Y).

With this structure, the low melting point alloy is melted at a specific temperature at which the gas is generated, and the discharge of the internal gas can be performed while the bonding of the molten alloy venting portion is separated.

5 is a plan view schematically showing a battery cell having an alloy venting portion according to another embodiment of the present invention, and FIG. 6 is a schematic cross-sectional view of a portion of the battery cell of FIG. 5 have.

5 and 6, the area A ₁ of the alloy venting part 200 of the battery cell 100B is set such that when the sealant layer 134 is viewed in a plane before the heat fusion, And the alloy venting portion 200 is formed to have a thickness of 50% based on the total area A ₂ of the sealable portion P which is the outer peripheral surface of the filler portion 115. Further, To the electrode assembly accommodating portion 115. As shown in Fig.

At this time, the low melting point alloy of the alloy venting portion 200B is composed of the elements Pb, Sn and Bi, and the ratio of the content of the element Pb: Sn: Bi is 28: 22: 50, and the melting point of the low melting point alloy is 100 degrees centigrade to be.

7 is a plan view schematically showing a battery cell according to another embodiment of the present invention.

7, the alloy venting portion 200C of the battery cell 100C is continuously formed in a range of 5% to 30% of the entire peripheral length S of the outer peripheral surface of the electrode assembly receiving portion 115, And the alloy venting portion 200C is formed in a plane in the width direction W of the planned sealing portion which is the outer circumferential surface of the electrode assembly receiving portion 115 and the alloy venting portion 200C is formed on the anode lead 112 And the negative electrode lead 113. The negative electrode lead 113 is made of a conductive material.

8 is a plan view schematically showing a battery cell according to another embodiment of the present invention.

8, the alloy venting portion 200D of the battery cell 100D is vertically extended from one end 114 of the battery case 110 in which the positive electrode lead 112 and the negative electrode lead 113 are formed, respectively, And is located at one side end 119 of the battery case 110 which is provided.

The battery cells 100C and 100D shown in FIGS. 7 and 8 are formed by forming the alloy venting portions 200C and 200D at specific positions where gas is required to be discharged. When the heat generation is increased due to abnormal operation of the battery cells, The alloy venting portion is melted at a temperature lower than the melting temperature, whereby the generated gas can be discharged while the bonding of the molten alloy venting portion is released.

As described above with reference to the drawings, the battery cell according to the present invention is characterized in that at least a part of the sealant layer of the battery case is composed of an alloy venting portion of a low melting point alloy having a melting point lower than that of the heat- When the vertical cross-sectional shape of the laminate sheet is a structure in which the polymer resin of the outermost layer, the metal of the barrier layer, and the low melting point alloy of the alloy venting portion are sequentially laminated, abnormal operation such as internal short circuit, overcharging, The high voltage gas inside the battery cell, which is generated due to side reaction of the electrode surface or vaporization of a part of the electrolytic solution component, is efficiently discharged through the alloy venting portion, thereby improving the safety by preventing the ignition or explosion of the battery from occurring. Effect.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (21)

A battery cell in which an electrode assembly is embedded in a pouch-shaped battery case and an outer circumferential surface of the battery case is sealed by heat sealing,
The battery case is composed of a laminate sheet laminated in the order of an outermost layer made of a polymer resin, a barrier layer made of a metal that blocks the inflow of foreign materials, and a sealant layer containing a heat-sealable resin, ≪ / RTI >
Wherein at least a part of the sealant layer is composed of an alloy venting portion of a low melting point alloy having a melting point lower than that of the heat-sealable resin, and the vertical sectional shape of the laminate sheet at the position where the alloy venting portion is located is a metal resin of the outermost layer, , And a low-melting-point alloy of an alloy venting portion are laminated in this order. The battery cell according to claim 1, wherein the battery case includes an upper cover and a lower body, which are laminated sheets. The battery cell according to claim 1, wherein the polymer resin in the outermost layer comprises at least one selected from the group consisting of ONy (stretched nylon) and polyethylene terephthalate (PET). The battery cell according to claim 1, wherein the barrier layer is made of aluminum or an aluminum alloy. The battery cell according to claim 1, wherein the heat sealable resin of the sealant layer comprises at least one selected from the group consisting of polyethylene resin, ionomer resin and CPP (unleaded polypropylene). The battery cell according to claim 1, wherein the heat-sealable resin has a melting point of at least 130 degrees Celsius and not more than 180 degrees Celsius. The battery cell according to claim 1, wherein the low melting point alloy has a melting point of at least 94 degrees Celsius and less than 130 degrees Celsius. The battery cell according to claim 1, wherein the low melting point alloy includes at least two elements selected from the group consisting of Bi, Pb, Si, Sn, Zn, and In. The battery cell according to claim 8, wherein the low melting point alloy is composed of elements Bi and Pb. The battery cell according to claim 9, wherein the content ratio of the element Bi: Pb is 50:50 to 60:40. The battery cell according to claim 8, wherein the low melting point alloy is composed of elements Pb, Sn and Bi. 12. The battery cell according to claim 11, wherein the content ratio of the element Pb: Sn: Bi is 25: 25: 50 to 28: 22: 50. 2. The method according to claim 1, wherein the forming area of the alloy venting portion is 50% or more based on the total area of the sealed portion, which is the outer circumferential surface of the electrode assembly receiving portion, when the silane layer is viewed in a plan view before the thermal fusion And the battery cell. The battery cell according to claim 1, wherein the alloy venting portion is formed in the entirety of a sealing scheduled portion, which is an outer circumferential surface of the electrode assembly receiving portion, when the silane layer is viewed in a plan view before heat fusion. The battery cell according to claim 1, wherein the alloy venting portion has a structure extending from the outer peripheral end of the sealant layer toward the electrode assembly receiving portion. The battery cell according to claim 1, wherein the alloy venting portion is formed continuously in a range of 5% to 30% of the entire circumferential length of the outer circumferential surface of the electrode assembly receiving portion. 17. The battery cell according to claim 16, wherein the alloy venting portion is formed continuously to one side end of the battery case at a position corresponding to a position between the positive electrode lead and the negative electrode lead. 17. The battery cell according to claim 16, wherein the alloy venting portion is located at one end of the battery case extending vertically from one end of the battery case in which the positive electrode lead and the negative electrode lead are respectively formed. A battery pack comprising a battery cell according to any one of claims 1 to 18. A device comprising the battery pack according to claim 19 as a power source. 21. The device of claim 20, wherein the device is a mobile phone, a portable computer, a wearable electronic device, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, And a storage device.

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