KR20240108303A - Pouch film for secondary battery with controlled residual rate and tearing thickness ratio, method for preparing the same, secondary battery using the same, and manufacturing method thereof - Google Patents

Abstract

As a secondary battery pouch film, at least an outer layer, a barrier layer, and a sealant layer are sequentially laminated, and the sealant layer thicknesses T1 and T2 measured according to a predetermined tearing test method satisfy [Equation 1], and the following [Equation 2] A secondary battery pouch film having a residual ratio of 70 to 80, a secondary battery using the same, and a method for manufacturing the same are disclosed.
[Equation 1]
0.6 < T1 / T2 < 0.85
[Equation 2]
Residual rate (%) = [Total sealant layer thickness in the sealing area after sealing / Total sealant layer thickness in the sealing area before sealing] x 100
The pouch film not only has excellent sealing strength at room temperature and high temperature, but also has excellent room temperature sealing strength maintenance characteristics and especially high temperature sealing strength maintenance characteristics.

Description

Pouch film for secondary batteries with controlled residual rate and tearing thickness ratio, method of manufacturing the same, secondary battery using the same, and method of manufacturing the same {Pouch film for secondary battery with controlled residual rate and tearing thickness ratio, method for preparing the same, secondary battery using the same same, and manufacturing method}

This specification relates to a pouch film for secondary batteries with controlled survival rate and tear thickness ratio, a secondary battery using the same, and a method for manufacturing the same. Specifically, the pouch film for secondary batteries has excellent thermal bonding strength, that is, sealing strength, at room temperature and high temperature, and , a pouch film for secondary batteries that has excellent sealing strength retention properties at room temperature and especially high temperatures and thus has excellent high-temperature long-term reliability when manufacturing battery packs, a secondary battery using the same, and a method of manufacturing the same.

Lithium secondary batteries (LiB) are being applied to many applications based on various advantages such as high energy density and excellent output.

Secondary battery pouch film is a packaging laminated film with a multi-layer structure that surrounds the electrode group and electrolyte of these secondary batteries. It is a key component material that determines the safety, life characteristics, and operating sustainability of the battery, and has mechanical flexibility and strength, and a high oxygen/water vapor barrier. Resistance, high thermal adhesive strength, chemical resistance to electrolytes, electrical insulation, and high temperature safety are required.

Secondary battery pouch films usually consist of an outer layer/barrier layer/inner sealant layer.

The outer layer or outermost layer is made of nylon, a blend of nylon and PET (polyethylene terephthalate), OPP (oriented polypropylene), polyethylene, etc. Required properties of this outer layer or outermost layer include heat resistance, pinhole resistance, chemical resistance, moldability, and insulation.

The barrier layer requires formability as well as barrier properties against water vapor and other gases. In this respect, moldable metals such as aluminum (Al), iron (Fe), copper (Cu), and nickel (Ni) are used in the barrier layer, and aluminum is currently used the most.

The sealant layer of the inner layer requires electrolyte resistance, insulation resistance, etc. in that it is a layer in contact with the electrolyte, as well as thermal adhesiveness and formability.

Meanwhile, as the application field of lithium secondary batteries expands from small to medium to large sized for automobiles or ESS, secondary battery pouch films also need characteristics suitable for medium to large sized batteries that require high safety.

Accordingly, it is necessary to maintain not only the sealing strength characteristics at room temperature but also excellent sealing strength at high temperatures (60°C), and further maintain the sealing strength at room temperature and especially high temperatures without deterioration. These characteristics have a significant impact on battery safety. Because it gives. In particular, in the case of pouch films used in medium to large-sized secondary batteries, battery explosions can lead to fatal accidents, so the development of secondary battery pouch films that can achieve battery safety is necessary.

However, it is not easy to secure and maintain high sealing strength at room temperature and high temperature during the actual manufacturing process of pouch films used in medium to large-sized secondary batteries.

In exemplary embodiments of the present invention, in one aspect, the present invention not only has excellent sealing strength at room temperature and high temperature, but also has excellent room temperature sealing strength maintenance characteristics and especially high temperature sealing strength maintenance characteristics. Therefore, the aim is to provide a pouch film for secondary batteries that has excellent high-temperature and long-term reliability when manufacturing battery packs, a secondary battery using the same, and a method for manufacturing the same.

Meanwhile, the thicker the above-mentioned sealant layer, especially the sealant layer using aluminum, the lower the thermal conductivity, especially the thermal conductivity in the vertical direction. Therefore, a pouch film with a thick sealant layer may have limitations in thermal bonding strength and sealing strength.

Accordingly, in exemplary embodiments of the present invention, in another aspect, even when the thickness of the sealant layer is thick, a pouch film for secondary batteries that has excellent sealing strength properties and retention properties at room temperature and high temperature as described above, and a pouch film using the same The object is to provide a secondary battery and a method of manufacturing the same.

In exemplary embodiments of the present invention, as a secondary battery pouch film, at least an outer layer, a barrier layer, and a sealant layer are sequentially laminated, and the sealant layer is extruded and laminated by an extrusion coating layer, according to the tearing test method below. A secondary transfer pouch film and a method for manufacturing the same are provided, wherein the measured sealant layer thicknesses T1 and T2 satisfy [Equation 1] and the residual ratio of [Equation 2] is 70 to 80.

[Equation 1]

0.6 < T1 / T2 < 0.85

[Equation 2]

Residual rate (%) = [Total sealant layer thickness in the sealing area after sealing / Total sealant layer thickness in the sealing area before sealing] x 100

[Tearing test method]

Fold the secondary battery pouch film in half, place the sealant layer in contact, and perform sealing at 200°C for 1.6 seconds. After sealing, the size of the sample is 20 cm wide x 5 cm long, and the sample is cut into 1.5 cm long pieces.

Hold both ends of the sample and pull it with a universal testing device (UTM) (pulling condition is 5 mm/min). After pulling the pouch film so that it is torn by about 5 mm or more from the sealing part, the thickness (T1) of the side where the thickness of the torn area is relatively thin or the same (upper side) and the side where the thickness of the torn area is relatively thick or the same (lower side) Measure the thickness (T2) of each using a thickness gauge. That is, T2 ≥ T1.

In an exemplary embodiment, the secondary battery pouch film may have T1 and T2 satisfying [Equation 3] below.

[Equation 3]

30㎛< T2 - T1 <85㎛

In an exemplary embodiment, the secondary battery pouch film has a maximum room temperature sealing strength measurement value of 140N/15mm or more and 205N/15mm or less in the TD direction when sealed under 220°C sealing conditions measured by the following method, preferably 150N. It can be more than /15mm and less than 205N/15mm.

[Method for measuring maximum room temperature sealing strength when sealed under 220℃ sealing conditions]

After making a secondary battery pouch film of 100mm

The sealing conditions are seal bar width 200mm

Each sealing strength in the MD and TD directions of the specimen is measured at room temperature with a sealing strength meter, and the sealing conditions are measured at a test speed of 10mpm and a grip gap of 30mm.

The maximum value of the sealing strength measurements is the maximum sealing strength.

In an exemplary embodiment, the secondary battery pouch film has a maximum high-temperature sealing strength measurement value (sealing strength measured after being left at 60°C for 3 minutes) when sealed under 220°C sealing conditions measured by the following method: TD It can be more than 115 N/15mm and less than 170 N/15mm in direction.

[Method for measuring maximum high temperature sealing strength when sealed under 220℃ sealing conditions]

After making a secondary battery pouch film of 100mm

The sealing conditions are seal bar width 200mm

With a sealing strength meter, the sealing strength of one or more of the MD and TD directions of the specimen is measured after leaving it for 3 minutes at 60℃, and the sealing conditions are measured at a test speed of 10mpm and a grip gap of 30mm.

The maximum value of the sealing strength measurements is the maximum sealing strength.

In one exemplary embodiment, the secondary battery pouch film may have room temperature energy in the TD direction of 2.0 to 3.0 KN x mm when sealed under 220°C sealing conditions as measured by the following method.

[Measurement of room temperature energy in TD direction when sealed under 220℃ sealing conditions]

After making a secondary battery pouch film of 100mm

The sealing conditions are seal bar width 200mm

Measure the change in sealing strength by pulling the specimen in the TD direction with a sealing strength meter at room temperature, and the measurement conditions are test speed of 10mpm and grip gap of 30mm.

When the Value - is defined as room temperature energy, and the integration is from the stroke range of 0mm to 20mm.

In one exemplary embodiment, the secondary battery pouch film may have a high temperature energy in the TD direction of 1.5 to 2.5 KN x mm when sealed under 220°C sealing conditions as measured by the following method.

[Measurement of high temperature energy in TD direction when sealed under 220℃ sealing conditions]

After making a secondary battery pouch film of 100mm

The sealing conditions are seal bar width 200mm

The change in sealing strength is measured by pulling in the TD direction of the specimen with a sealing strength meter under high temperature conditions measured after leaving at 60℃ for 3 minutes. The measurement conditions are test speed of 10mpm and grip gap of 30mm.

When the The value - is defined as high-temperature energy, and the integration is from the stroke range of 0mm to 20mm.

In an exemplary embodiment, the secondary battery pouch film may have a difference between room temperature energy and high temperature energy in the TD direction of 0.4 to 0.6 KN x mm when sealed under 220°C sealing conditions as measured by the following method.

[Measurement of room temperature energy and high temperature energy in the TD direction when sealed under 220℃ sealing conditions]

After making a secondary battery pouch film of 100mm

The sealing conditions are Seal Bar Width 200mm

Measure the change in sealing strength by pulling the specimen in the TD direction with a sealing strength meter under room temperature conditions or high temperature conditions measured after leaving it for 3 minutes at 60°C. The measurement conditions are test speed of 10mpm and grip gap of 30mm. box

When the Value - is defined as room temperature energy or high temperature energy, and the integral is the integration from the stroke range of 0mm to 20mm.

Energy when measured under room temperature conditions is room temperature energy, and energy when measured under high temperature conditions is high temperature energy.

In one exemplary embodiment, the secondary battery pouch film may have a maximum stroke in the TD direction at room temperature of 15 to 25 mm when sealed under 220°C sealing conditions as measured by the following method.

[Measurement of maximum stroke at room temperature in TD direction when sealed under 220℃ sealing conditions]

After making a secondary battery pouch film of 100mm

The sealing conditions are Seal Bar Width 200mm

Measure the change in sealing strength by pulling the specimen in the TD direction with a sealing strength meter at room temperature, and the measurement conditions are test speed of 10mpm and grip gap of 30mm.

When the box

In one exemplary embodiment, the secondary battery pouch film may have a maximum high temperature stroke in the TD direction of 18 to 24 mm when sealed under 220°C sealing conditions as measured by the following method.

[Measurement of high temperature maximum stroke in TD direction when sealed under 220℃ sealing conditions]

After making a secondary battery pouch film of 100mm

The sealing conditions are Seal Bar Width 200mm

The change in sealing strength is measured by pulling in the TD direction of the specimen with a sealing strength meter under high temperature conditions measured after leaving at 60℃ for 3 minutes. The measurement conditions are test speed of 10mpm and grip gap of 30mm.

When the box

Additionally, exemplary embodiments of the present invention provide a secondary battery externally packaged with the above-described secondary battery pouch film.

In an exemplary embodiment, the secondary battery may be used for an electric vehicle or an energy storage device.

Additionally, exemplary embodiments of the present invention provide a method for manufacturing a secondary battery, including the step of packaging the secondary battery with the above-described secondary battery pouch film.

In one aspect, the pouch film of exemplary embodiments of the present invention not only has excellent sealing strength at room temperature and high temperature by controlling the tearing ratio and residual ratio when the sealant layer of the pouch film is torn, but also provides room temperature sealing. It has excellent strength retention characteristics and high temperature sealing strength retention characteristics. In particular, even when the thickness of the sealant layer is thick, the sealing strength characteristics and maintenance characteristics at room temperature and high temperature can be excellent as described above.

In addition, the pouch film of exemplary embodiments of the present invention, in another aspect, additionally adjusts the yield strength of the sealant layer and the thickness of the extruded (EC) layer and polypropylene (PP) layer of the sealant layer, and also has a sealant layer By controlling the glass transition temperature, not only can the sealing strength at room temperature and high temperature be improved, but also the room temperature sealing strength maintenance characteristics and especially the high temperature sealing strength maintenance characteristics can be improved.

In addition, the pouch film of exemplary embodiments of the present invention, in another aspect, has excellent long-term reliability at high temperatures when manufacturing a battery pack by controlling the sealing strength and maximum stroke at room temperature and high temperature, and energy parameters at room temperature and high temperature. do.

These secondary battery pouch films are useful as medium-to-large secondary battery pouches for electric vehicles or energy storage devices that require safety, especially high-temperature safety.

1 is a schematic diagram showing the configuration of a secondary battery pouch film manufactured by the EC method in an exemplary embodiment of the present invention.
Figure 2 is a schematic diagram illustrating a torn portion of the sealant layer when torn in an exemplary embodiment of the present invention.
Figure 3a is a schematic diagram of the jig used in this experimental example, and Figure 3b is a photograph showing the battery pack sample coupled to the jig in this experimental example.

Term Definition

In this specification, when each layer of the secondary battery pouch is included, it does not necessarily consist of only that layer, and additional layers may be included.

In this specification, being formed ‘on’ a specific layer includes not only being formed directly on that layer, but also being formed after interposing another additional layer.

In this specification, the yield strength increases in proportion to the increase in load when the specimen exceeds the elastic limit and begins to increase in proportion to the load. This point is called the yield point, and the force applied to the yield point is called the yield strength.

In this specification, upper yield strength means the maximum value (peak value) of yield strength. In other words, the yield point includes an upper yield point (the point where the yield strength is the maximum among the yield points) and a lower yield point (the point where the yield strength is the minimum among the yield points), and the upper yield strength is the maximum value (peak value) of the yield strength at the yield point. [i.e., yield strength at the upper yield point], and lower yield strength means the minimum value of the yield strength at the yield point [i.e., yield strength at the lower yield point]. Depending on the yield strength measurement target, the upper yield point and lower yield point may be the same.

In this specification, the extrusion coating (EC) layer is an extrusion coating layer of a resin, such as a polyolefin resin, extruded for bonding to the barrier layer among the sealant layers (hereinafter abbreviated as an extrusion layer or an extrusion (EC) layer). means]. The extrusion (EC) layer of the sealant layer is located on the barrier layer side based on the polypropylene-based resin layer below.

In this specification, the polypropylene-based resin layer of the sealant layer is a core resin layer forming the sealant layer, plays a sealing role, and consists of one or more layers. It is contrasted with the aforementioned extruded (EC) layer for bonding with the barrier layer and is located on the inside of the pouch film (i.e., on the opposite side of the barrier layer) based on the aforementioned extruded (EC) layer.

In this specification, the upper side of the torn area refers to the side where the thickness of the torn area is relatively thin or the same when the sealant layer is torn, and the lower side of the torn area refers to the side where the thickness of the torn area when the sealant layer is torn is relatively thick or the same. means side. That is, lower thickness T2 ≥ upper thickness T1.

In this specification, energy is an item that evaluates the sealing strength maintenance characteristics, and is the stroke section of the graph showing the change in sealing strength when measuring the change in sealing strength (Y-axis) value according to the stroke (distance) [X-axis] of pulling the sealing part. It is the integral value for the area in the area (0~20mm), that is, the graph of the change in sealing strength in the corresponding stroke section (0~20mm) and the stroke (distance) axis [X-axis]. Since it is the product of force and distance, it can be expressed as energy. there is.

In this specification, the maximum stroke is also an item that can evaluate the sealing strength maintenance characteristics. As the stroke (distance) pulling the sealing part increases, the sealing strength graph increases, and the stroke (distance) at which the sealing strength value reaches the maximum is called the maximum stroke. .

In this specification, the remaining thickness refers to the total thickness of the sealant layer after sealing in the sealing portion.

In this specification, the residual ratio is a percentage of 100 obtained by dividing the total sealant layer thickness in the sealing portion after sealing (i.e., remaining thickness) by the total sealant layer thickness in the sealing portion before sealing.

Description of Exemplary Implementations

Exemplary implementations of the present invention are described in detail below.

Methods for manufacturing a sealant layer when manufacturing a secondary battery pouch include an extrusion lamination method and a solvent-dry lamination (hereinafter abbreviated as SDL) method.

The solvent dry lamination method is a method of attaching a barrier layer (metal layer) using a solvent-type adhesive on a polypropylene (PP) layer and drying the solvent-type adhesive. The sealant layer produced according to this method is a polypropylene (PP) layer. It is made up of The solvent-type adhesive may remain in the polypropylene (PP) layer after drying, but it exists at a thickness of about 4㎛ or less and is insignificant, so the thickness can be ignored.

Meanwhile, the extrusion lamination method extrudes a polyolefin-based resin, preferably a polypropylene resin, when adhering a polypropylene-based resin layer, preferably a non-stretched polypropylene (CPP) resin layer, mainly used in the sealant layer, to the barrier layer (metal layer). This is the way to do it. As a result, the sealant layer is composed of an extrusion coating (EC) layer (mainly an extruded polypropylene layer) and a polypropylene (PP) layer underneath (inside the pouch film), preferably non-stretched polypropylene (CPP). It is made up of layers (see Figure 1).

In particular, in the extrusion lamination manufacturing method, the present inventors control the relative thickness of the extrusion (EC) layer and the polypropylene (PP) layer of the sealant layer (or adjust the relative thickness occupied by the polypropylene (PP) layer among the sealant layers) By controlling the yield strength of the layer and also controlling the glass transition temperature (Tg) of the sealant layer, surprisingly, the secondary battery pouch film not only has excellent sealing strength characteristics at room temperature, but also has excellent sealing strength characteristics at high temperatures, especially at high temperatures. It was confirmed that the sealing strength maintenance characteristics were also excellent. These control variables are also related to controlling the tear thickness ratio and survival rate, etc., as described later.

Sealing strength characteristics, especially high-temperature sealing strength characteristics, are essential characteristics for the safety of medium-to-large batteries such as automobile batteries. In particular, it is necessary to maintain the high-temperature sealing strength as much as possible to ensure the safety of medium-to-large batteries in high-temperature environments. However, when manufacturing a pouch film, multiple layers are stacked and various manufacturing conditions are involved in the manufacture of the sealant layer, so it is difficult to control the sealing strength characteristics, especially the high-temperature sealing strength characteristics, and especially the maintenance characteristics of the high-temperature sealing strength. As described above, the sealant layer of the pouch film is manufactured to have a predetermined yield strength, the thickness ratio of the polypropylene resin (PP) layer of the sealant layer is controlled, and the sealant layer is manufactured to have a predetermined glass transition temperature (Tg). According to the present invention, it has been found that not only are the lower room temperature sealing strength characteristics and high temperature sealing strength characteristics excellent, but the high temperature sealing strength maintenance characteristics are also excellent. When using the extrusion lamination method, the yield strength of the sealant layer of the pouch film, the thickness ratio of the polypropylene resin (PP) layer of the sealant layer, and the glass transition temperature (Tg) of the sealant layer are important for room temperature and high temperature sealing strength characteristics, especially high temperature sealing strength. It is believed to be related to the maintenance characteristics of .

Specifically, in exemplary embodiments of the present invention, a secondary battery pouch film is composed of a laminate in which at least an outer layer, a barrier layer, and a sealant layer are sequentially laminated, and the sealant layer includes at least an extrusion (EC) layer and the It is composed of a polypropylene (PP) layer, which is a sealing resin layer below the extrusion (EC) layer, and the thickness ratio of the polypropylene (PP) layer among the sealant layers is greater than 0.5, and the sealant layer, that is, the extrusion (EC) layer and the poly The upper yield strength (N/mm ² ) in the MD direction of the sealant layer including the propylene (PP) layer is 17.50 to 19.99, preferably 17.50 to 19.80, and the upper yield strength (N/mm ² ) in the TD direction is 17.00. ~19.99, preferably 17.00~19.50, and the glass transition temperature (Tg) of the sealant layer is in the range of -20℃~-10℃.

Meanwhile, the present inventors found that in the secondary battery pouch film manufactured by the extrusion lamination manufacturing method, the upper side (the part where the remaining thickness is the same or relatively less thick) and the lower side (the remaining thickness is the same or less thick) during the tearing test below. The part that remains relatively thicker) is not only different from the thickness, but is torn so that the lower side remains thicker than the upper side, but the upper thickness (T1) and the lower thickness (T2) satisfy the following equation, and are expressed in [Equation 2] below. It was confirmed that when the residual ratio was in the range of 70 to 80, room temperature and high temperature sealing strength was excellent, and in particular, room temperature and high temperature sealing strength maintenance characteristics were excellent.

[Equation 1]

0.6 < T1 / T2 (tearing thickness ratio) < 0.85

[Equation 2]

Residual rate (%) = [Total sealant layer thickness in the sealing area after sealing / Total sealant layer thickness in the sealing area before sealing] x 100

[Tearing test method]

Fold the secondary battery pouch film in half, place the sealant layer in contact, and perform sealing at 200°C for 1.6 seconds. After sealing, the size of the sample is 20 cm wide x 5 cm long, and the sample is cut into 1.5 cm long pieces.

Hold both ends of the sample and pull it with a universal testing device (UTM) (pulling condition is 5 mm/min). After pulling the pouch film to tear it more than about 5 mm from the sealing part, measure the thickness (T1) of the relatively thin side (upper side) and the thickness (T2) of the relatively thick side (lower side) of the torn area using a thickness measuring device, respectively. Measure.

Additionally, in one exemplary embodiment, the secondary battery pouch film may satisfy the tearing thickness difference of [Equation 3] below.

[Equation 3]

T2 - T1 (tear thickness difference) <85㎛

Sealing strength characteristics, especially high-temperature sealing strength characteristics, are essential characteristics for the safety of medium-to-large batteries such as automobile batteries. In particular, it is necessary to maintain the high-temperature sealing strength as much as possible to ensure the safety of medium-to-large batteries in high-temperature environments. However, when manufacturing a pouch film, multiple layers are stacked and various manufacturing conditions are involved in the manufacture of the sealant layer, so it is difficult to control the sealing strength characteristics, especially the high-temperature sealing strength characteristics, and especially the maintenance characteristics of the high-temperature sealing strength.

As described above, by adjusting the tearing thickness T1 and T2 when the pouch film is pulled and further controlling the residual rate, the sealing strength at room temperature and high temperature can be excellent, and the sealing strength maintenance characteristics at room temperature and high temperature can also be excellent. there is.

When using the extrusion lamination method, it is understood that the tear thickness ratio, survival rate, and even tear thickness difference are not only related to room temperature and high temperature sealing strength, but are also related to the maintenance characteristics of high temperature sealing strength.

Figure 2 is a schematic diagram illustrating a torn portion of the sealant layer when torn in an exemplary embodiment of the present invention.

As shown in Figure 2, when sealing is performed on a secondary battery pouch film manufactured through extrusion lamination, the two sealant layers in contact with each other are combined (that is, forming a sealing portion). In this state, when tearing progresses, a crack occurs in a relatively weak part of the joined part and the layer is separated into two layers. At this time, the torn portion may be torn from the PP layer that is in contact with each other among the sealant layers (Figure 2 shows tearing from the PP layer), or may be torn between the EC layer and the PP layer.

In a non-limiting example, when the PP layers in contact with each other among the sealing parts are torn, for example, T1/T2 may become 1 (e.g., T1 = 80㎛, T2 = 80㎛), and at any one of the boundaries between the EC and PP layers. When torn, T1/T2 may be, for example, 0.45 (eg, T1=50㎛, T2=110㎛).

In relation to the control of this floating ratio (T1/T2) or the difference in thickness (T2-T1), or residual ratio, the thickness ratio of the polypropylene (PP) layer in the sealant layer (or the EC constituting the sealant layer) when manufacturing the sealant layer If factors such as the thickness ratio of the layer and the PP layer, the yield strength of the sealant layer, the glass transition temperature (Tg), or the temperature, pressure, and time during sealing are changed, the layer where cracks occur when torn may change. there is. Using this, when a polypropylene (PP) layer, preferably a non-stretched polypropylene (cPP) film, is introduced among the sealant layers, the yield strength is increased, the glass transition temperature (Tg) is increased, and the temperature, pressure, and time during sealing are increased. Through changes, the tearing ratio, residual rate, and even the difference in steaming thickness can be adjusted to the desired range.

For example, in more detail, in the case of the comparative example of Experiment 1 described later, the yield strength and Tg values are relatively small, so tearing occurs near the polypropylene (PP layer) in contact and the sealing strength is weak, whereas in the example, the yield strength and Tg values are It is relatively high, and as the strength of the polypropylene (PP layer) in contact during sealing becomes stronger, tearing occurs at the boundary between the EC layer and the polypropylene (PP) layer, and the sealing strength also increases.

Also, for example, in Experiment 2 described later, if the temperature, pressure, and time during sealing are increased or decreased, the residual rate may be decreased or increased. In other words, as each condition (temperature, time, pressure) increases, the survival rate may decrease, and as each condition (temperature, time, pressure) decreases, the survival rate may increase. Here, temperature, time, and pressure can be adjusted independently.

In a non-limiting example, the residual rate can be changed by independently adjusting the temperature from 160°C to 230°C, the time from 1 second to 4 seconds, and the pressure from 0.1 MPa to 0.6 MPa.

In an exemplary embodiment, T1/T2 (tearing thickness ratio) of [Equation 1] is 0.61 or more, 0.62 or more, 0.63 or more, 0.64 or more, 0.65 or more, 0.66 or more, 0.67 or more, 0.68 or more, 0.69 or more, 0.70 or more. It may be 0.71 or more, 0.72 or more, 0.73 or more, 0.74 or more, 0.75 or more, 0.76 or more, 0.,77 or more, 0.78 or more, 0.79 or more, 0.80 or more, 0.81 or more, 0.82 or more, 0.83 or more, or 0.84 or more. or 0.84 or less, 0.83 or less, 0.82 or less, 0.81 or less, 0.80 or less, 0.79 or less, 0.78 or less, 0.77 or less, 0.76 or less, 0.75 or less, 0.74 or less, 0.73 or less, 0.72 or less, 0.71 or less, 0.70 or less, 0.69 or less, 0.68 or less. It may be 0.67 or less, 0.66 or less, 0.65 or less, 0.64 or less, 0.63 or less, 0.62 or less, or 0.61 or less.

In an exemplary embodiment, the residual ratio (%) of [Equation 2] may be 70 or more, 71 or more, 72 or more, 73 or more, 74 or more, 75 or more, 76 or more, 77 or more, 78 or more, or 79 or more. . Or it may be 80 or less, 79 or less, 78 or less, 77 or less, 76 or less, 75 or less, 74 or less, 73 or less, 72 or less, and 71 or less.

In an exemplary embodiment, T2 - T1 of [Equation 3] is 0㎛ or more, 5㎛ or more, 10㎛ or more, 15㎛ or more, 20㎛ or more, 25㎛ or more, 30㎛ or more, 35㎛ or more, 40㎛ or more. It may be ㎛ or more, 45 ㎛ or more, 50 ㎛ or more, 55 ㎛ or more, 60 ㎛ or more, 65 ㎛ or more, 70 ㎛ or more, 75 ㎛ or more, or 80 ㎛ or more. Or, 80㎛ or less, 75㎛ or less, 70㎛ or less, 65㎛ or less, 60㎛ or less, 55㎛ or less, 50㎛ or less, 45㎛ or less, 40㎛ or less, 35㎛ or less, 30㎛ or less, 25㎛ or less, It may be 20 μm or less, 15 μm or less, 10 μm or less, or 5 μm or less.

If the T1/T2 (tearing thickness ratio) and residual ratio are outside the above-mentioned range, as can be seen from the data described later, the room temperature and high temperature sealing strength characteristics may be deteriorated, and the room temperature and high temperature sealing strength maintenance characteristics may also be deteriorated. there is.

Furthermore, if the T2 - T1 (tear thickness difference) is outside the above-mentioned range, the room temperature and high temperature sealing strength characteristics may be deteriorated, as can be confirmed from the data described later, and the room temperature and high temperature sealing strength maintenance characteristics may also be deteriorated. .

In an exemplary embodiment, the thickness ratio of the polypropylene (PP) layer in the sealant layer is 0.500 or more, 0.525 or more, 0.550 or more, 0.575 or more, 0.600 or more, 0.625 or more, 0.650 or more, 0.675 or more, 0.700 or more, 0.725 or more, It may be 0.750 or higher, or 0.775 or higher. Alternatively, it may be 0.800 or less, 0.775 or less, 0.750 or less, 0.725 or less, 0.700 or less, 0.675 or less, 0.650 or less, 0.625 or less, 0.600 or less, 0.575 or less, 0.550 or less, or 0.525 or less.

When the thickness ratio is less than 0.5, that is, when the thickness of the polypropylene (PP) layer is less than half the thickness of the sealant layer, the yield strength is lowered , and the tear thickness ratio or tear thickness difference is outside the desired range. , the sealing strength may be lowered. On the other hand, when the thickness ratio is greater than 0.8, that is, even when the thickness of the polypropylene (PP) layer is thicker than 80% of the total thickness of the sealant layer, the tear thickness ratio or tear thickness difference etc. are outside the desired range. Sealing strength may be lowered.

Here, the fact that the thickness ratio of the polypropylene (PP) layer among the sealant layers is 0.500 or more means that the thickness of the extrusion (EC) layer must be thinner than the thickness of the polypropylene (PP) layer.

In an exemplary embodiment, the upper yield strength (N/mm ² ) of the sealant layer in the MD direction is within the range of 17.50 to 19.99, and may also have a numerical range between the following values within the range. If the upper yield strength (N/mm ² ) of the sealant layer in the MD direction is outside the above range, not only will the tear thickness ratio or tear thickness difference be outside the desired range, as can be confirmed from the data described later, but also the room temperature and High-temperature sealing strength characteristics, especially high-temperature sealing strength maintenance characteristics, may be deteriorated.

In a non-limiting example, the upper yield strength (N/mm ² ) in the MD direction of the sealant layer is 17.50 or more, 17.51 or less, 17.52 or less, 17.53 or less, 17.54 or less, 17.55 or less. , 17.56 or lower, 17.57 or lower, 17.58 or lower, 17.59 or lower, 17.60 or lower, 17.61 or lower, 17.62 or lower, 17.63 or lower, 17.64 or lower, 17.65 or lower , 17.66 or lower, 17.67 or lower, 17.68 or lower, 17.69 or lower, 17.70 or lower, 17.71 or lower, 17.72 or lower, 17.73 or lower, 17.74 or lower, 17.75 or lower , 17.76 or lower, 17.77 or lower, 17.78 or lower, 17.79 or lower, 17.80 or lower, 17.81 or lower, 17.82 or lower, 17.83 or lower, 17.84 or lower, 17.85 or lower , 17.86 or lower, 17.87 or lower, 17.88 or lower, 17.89 or lower, 17.90 or lower, 17.91 or lower, 17.92 or lower, 17.93 or lower, 17.94 or lower, 17.95 or lower , 17.96 or lower, 17.97 or lower, 17.98 or lower, 17.99 or lower, 18.00 or lower, 18.01 or lower, 18.02 or lower, 18.03 or lower, 18.04 or lower, 18.05 or lower , 18.06 or higher, 18.07 or lower, 18.08 or lower, 18.09 or lower, 18.10 or lower, 18.11 or lower, 18.12 or lower, 18.13 or lower, 18.14 or lower, 18.15 or lower , 18.16 or lower, 18.17 or lower, 18.18 or lower, 18.19 or lower, 18.20 or lower, 18.21 or lower, 18.22 or lower, 18.23 or lower, 18.24 or lower, 18.25 or lower , 18.26 or lower, 18.27 or lower, 18.28 or lower, 18.29 or lower, 18.30 or lower, 18.31 or lower, 18.32 or lower, 18.33 or lower, 18.34 or lower, 18.35 or lower , 18.36 or lower, 18.37 or lower, 18.38 or lower, 18.39 or lower, 18.40 or lower, 18.41 or lower, 18.42 or lower, 18.43 or lower, 18.44 or lower, 18.45 or lower , 18.46 or lower, 18.47 or lower, 18.48 or lower, 18.49 or lower, 18.50 or lower, 18.51 or lower, 18.52 or lower, 18.53 or lower, 18.54 or lower, 18.55 or lower , 18.56 or lower, 18.57 or lower, 18.58 or lower, 18.59 or lower, 18.60 or lower, 18.61 or lower, 18.62 or lower, 18.63 or lower, 18.64 or lower, 18.65 or lower , 18.66 or lower, 18.67 or lower, 18.68 or lower, 18.69 or lower, 18.70 or lower, 18.71 or lower, 18.72 or lower, 18.73 or lower, 18.74 or lower, 18.75 or lower , 18.76 or lower, 18.77 or lower, 18.78 or lower, 18.79 or lower, 18.80 or lower, 18.81 or lower, 18.82 or lower, 18.83 or lower, 18.84 or lower, 18.85 or lower , 18.86 or lower, 18.87 or lower, 18.88 or lower, 18.89 or lower, 18.90 or lower, 18.91 or lower, 18.92 or lower, 18.93 or lower, 18.94 or lower, 18.95 or lower , 18.96 or lower, 18.97 or lower, 18.98 or lower, 18.99 or lower, 19.00 or lower, 19.01 or lower, 19.02 or lower, 19.03 or lower, 19.04 or lower, 19.05 or lower , 19.06 or lower, 19.07 or lower, 19.08 or lower, 19.09 or lower, 19.10 or lower, 19.11 or lower, 19.12 or lower, 19.13 or lower, 19.14 or lower, 19.15 or lower , 19.16 or lower, 19.17 or lower, 19.18 or lower, 19.19 or lower, 19.20 or lower, 19.21 or lower, 19.22 or lower, 19.23 or lower, 19.24 or lower, 19.25 or lower , 19.26 or lower, 19.27 or lower, 19.28 or lower, 19.29 or lower, 19.30 or lower, 19.31 or lower, 19.32 or lower, 19.33 or lower, 19.34 or lower, 19.35 or lower , 19.36 or lower, 19.37 or lower, 19.38 or lower, 19.39 or lower, 19.40 or lower, 19.41 or lower, 19.42 or lower, 19.43 or lower, 19.44 or lower, 19.45 or lower , 19.46 or lower, 19.47 or lower, 19.48 or lower, 19.49 or lower, 19.50 or lower, 19.51 or lower, 19.52 or lower, 19.53 or lower, 19.54 or lower, 19.55 or lower , 19.56 or lower, 19.57 or lower, 19.58 or lower, 19.59 or lower, 19.60 or lower, 19.61 or lower, 19.62 or lower, 19.63 or lower, 19.64 or lower, 19.65 or lower , 19.66 or lower, 19.67 or lower, 19.68 or lower, 19.69 or lower, 19.70 or lower, 19.71 or lower, 19.72 or lower, 19.73 or lower, 19.74 or lower, 19.75 or lower , 19.76 or lower, 19.77 or lower, 19.78 or lower, 19.79 or lower, 19.80 or lower, 19.81 or lower, 19.82 or lower, 19.83 or lower, 19.84 or lower, 19.85 or lower , 19.86 or lower, 19.87 or lower, 19.88 or lower, 19.89 or lower, 19.90 or lower, 19.91 or lower, 19.92 or lower, 19.93 or lower, 19.94 or lower, 19.95 or lower , may be 19.96 or higher, 19.97 or lower, 19.98 or lower, or 19.99 or lower.

In an exemplary embodiment, the upper yield strength (N/mm ² ) of the sealant layer in the TD direction is within the range of 17.00 to 19.99, and may have a numerical range between the following values within the range. If the upper yield strength (N/mm ² ) of the sealant layer in the TD direction is outside the above range, not only will the tear thickness ratio or tear thickness difference be outside the desired range, as can be confirmed from the data described later, but also the room temperature and High-temperature sealing strength characteristics, especially high-temperature sealing strength maintenance characteristics, may be deteriorated.

In a non-limiting example, the upper yield strength (N/mm ² ) in the TD direction of the sealant layer is 17.00 or more, 17.01 or less, 17.02 or less, 17.03 or less, 17.04 or less, 17.05 or less. , 17.06 or lower, 17.07 or lower, 17.08 or lower, 17.09 or lower, 17.10 or lower, 17.11 or lower, 17.12 or lower, 17.13 or lower, 17.14 or lower, 17.15 or lower , 17.16 or lower, 17.17 or lower, 17.18 or lower, 17.19 or lower, 17.20 or lower, 17.21 or lower, 17.22 or lower, 17.23 or lower, 17.24 or lower, 17.25 or lower , 17.26 or lower, 17.27 or lower, 17.28 or lower, 17.29 or lower, 17.30 or lower, 17.31 or lower, 17.32 or lower, 17.33 or lower, 17.34 or lower, 17.35 or lower , 17.36 or lower, 17.37 or lower, 17.38 or lower, 17.39 or lower, 17.40 or lower, 17.41 or lower, 17.42 or lower, 17.43 or lower, 17.44 or lower, 17.45 or lower , 17.46 or lower, 17.47 or lower, 17.48 or lower, 17.49 or lower, 17.50 or lower, 17.51 or lower, 17.52 or lower, 17.53 or lower, 17.54 or lower, 17.55 or lower , 17.56 or lower, 17.57 or lower, 17.58 or lower, 17.59 or lower, 17.60 or lower, 17.61 or lower, 17.62 or lower, 17.63 or lower, 17.64 or lower, 17.65 or lower , 17.66 or lower, 17.67 or lower, 17.68 or lower, 17.69 or lower, 17.70 or lower, 17.71 or lower, 17.72 or lower, 17.73 or lower, 17.74 or lower, 17.75 or lower , 17.76 or lower, 17.77 or lower, 17.78 or lower, 17.79 or lower, 17.80 or lower, 17.81 or lower, 17.82 or lower, 17.83 or lower, 17.84 or lower, 17.85 or lower , 17.86 or lower, 17.87 or lower, 17.88 or lower, 17.89 or lower, 17.90 or lower, 17.91 or lower, 17.92 or lower, 17.93 or lower, 17.94 or lower, 17.95 or lower , 17.96 or lower, 17.97 or lower, 17.98 or lower, 17.99 or lower, 18.00 or lower, 18.01 or lower, 18.02 or lower, 18.03 or lower, 18.04 or lower, 18.05 or lower , 18.06 or higher, 18.07 or lower, 18.08 or lower, 18.09 or lower, 18.10 or lower, 18.11 or lower, 18.12 or lower, 18.13 or lower, 18.14 or lower, 18.15 or lower , 18.16 or lower, 18.17 or lower, 18.18 or lower, 18.19 or lower, 18.20 or lower, 18.21 or lower, 18.22 or lower, 18.23 or lower, 18.24 or lower, 18.25 or lower , 18.26 or lower, 18.27 or lower, 18.28 or lower, 18.29 or lower, 18.30 or lower, 18.31 or lower, 18.32 or lower, 18.33 or lower, 18.34 or lower, 18.35 or lower , 18.36 or lower, 18.37 or lower, 18.38 or lower, 18.39 or lower, 18.40 or lower, 18.41 or lower, 18.42 or lower, 18.43 or lower, 18.44 or lower, 18.45 or lower , 18.46 or lower, 18.47 or lower, 18.48 or lower, 18.49 or lower, 18.50 or lower, 18.51 or lower, 18.52 or lower, 18.53 or lower, 18.54 or lower, 18.55 or lower , 18.56 or lower, 18.57 or lower, 18.58 or lower, 18.59 or lower, 18.60 or lower, 18.61 or lower, 18.62 or lower, 18.63 or lower, 18.64 or lower, 18.65 or lower , 18.66 or lower, 18.67 or lower, 18.68 or lower, 18.69 or lower, 18.70 or lower, 18.71 or lower, 18.72 or lower, 18.73 or lower, 18.74 or lower, 18.75 or lower , 18.76 or lower, 18.77 or lower, 18.78 or lower, 18.79 or lower, 18.80 or lower, 18.81 or lower, 18.82 or lower, 18.83 or lower, 18.84 or lower, 18.85 or lower , 18.86 or lower, 18.87 or lower, 18.88 or lower, 18.89 or lower, 18.90 or lower, 18.91 or lower, 18.92 or lower, 18.93 or lower, 18.94 or lower, 18.95 or lower , 18.96 or lower, 18.97 or lower, 18.98 or lower, 18.99 or lower, 19.00 or lower, 19.01 or lower, 19.02 or lower, 19.03 or lower, 19.04 or lower, 19.05 or lower , 19.06 or lower, 19.07 or lower, 19.08 or lower, 19.09 or lower, 19.10 or lower, 19.11 or lower, 19.12 or lower, 19.13 or lower, 19.14 or lower, 19.15 or lower , 19.16 or lower, 19.17 or lower, 19.18 or lower, 19.19 or lower, 19.20 or lower, 19.21 or lower, 19.22 or lower, 19.23 or lower, 19.24 or lower, 19.25 or lower , 19.26 or lower, 19.27 or lower, 19.28 or lower, 19.29 or lower, 19.30 or lower, 19.31 or lower, 19.32 or lower, 19.33 or lower, 19.34 or lower, 19.35 or lower , 19.36 or lower, 19.37 or lower, 19.38 or lower, 19.39 or lower, 19.40 or lower, 19.41 or lower, 19.42 or lower, 19.43 or lower, 19.44 or lower, 19.45 or lower , 19.46 or lower, 19.47 or lower, 19.48 or lower, 19.49 or lower, 19.50 or lower, 19.51 or lower, 19.52 or lower, 19.53 or lower, 19.54 or lower, 19.55 or lower , 19.56 or lower, 19.57 or lower, 19.58 or lower, 19.59 or lower, 19.60 or lower, 19.61 or lower, 19.62 or lower, 19.63 or lower, 19.64 or lower, 19.65 or lower , 19.66 or lower, 19.67 or lower, 19.68 or lower, 19.69 or lower, 19.70 or lower, 19.71 or lower, 19.72 or lower, 19.73 or lower, 19.74 or lower, 19.75 or lower , 19.76 or lower, 19.77 or lower, 19.78 or lower, 19.79 or lower, 19.80 or lower, 19.81 or lower, 19.82 or lower, 19.83 or lower, 19.84 or lower, 19.85 or lower , 19.86 or lower, 19.87 or lower, 19.88 or lower, 19.89 or lower, 19.90 or lower, 19.91 or lower, 19.92 or lower, 19.93 or lower, 19.94 or lower, 19.95 or lower , may be 19.96 or higher, 19.97 or lower, 19.98 or lower, or 19.99 or lower.

In an exemplary embodiment, the sum of the upper yield strength (N/mm ² ) in the MD direction and the upper yield strength (N/mm ² ) in the TD direction of the sealant layer is 34.5 or more and 39.9 or less, preferably 34.5 or more. Below, more preferably 34.61 to 38.85.

In an exemplary embodiment, the upper yield strength (N/mm ² ) of the sealant layer in the MD direction may be greater than the upper yield strength (N/mm ² ) of the sealant layer in the TD direction. Due to the nature of the extrusion coating (EC) process and the nature of the process of laminating the sealant layer with a PP layer, slight stretching may occur in the MD direction (Machine Direction, longitudinal direction). Accordingly, it is believed that the upper yield strength in the MD direction is greater than in the TD direction (transverse direction), where stretching does not occur.

In an exemplary embodiment, the glass transition temperature (Tg) of the sealant layer has a value within the range of -20°C to -10°C, preferably -19°C to -11°C, and the following values within that range are It can have a range of values. If the glass transition temperature (Tg) of the sealant layer is outside the range of -20℃ to -10℃, not only will the tearing thickness ratio or tearing thickness difference be outside the desired range, as can be seen from the data described later, but also the room temperature and High-temperature sealing strength characteristics, especially high-temperature sealing strength maintenance characteristics, may be deteriorated.

In non-limiting examples, the glass transition temperature (Tg) of the sealant layer is -20°C or higher, -19.5°C or higher, -19°C or higher, -18.5°C or higher, -18°C or higher, -17.5°C or higher, -17°C or higher. or higher, -16.5℃ or higher, -16℃ or higher, -15.5℃ or higher, -15℃ or higher, -14.5℃ or higher, -14℃ or higher, -13.5℃ or higher, -13℃ or higher, -12.5℃ or higher, -12℃ or higher It may be above, -11.5°C or above, -11°C or above, or -10.5°C or above. or -10℃ or lower, -10.5℃ or lower, -11℃ or lower, -11.5℃ or lower, -12℃ or lower, -12.5℃ or lower, -13℃ or lower, -13.5℃ or lower, -14℃ or lower, -14.5℃ or lower , -15℃ or lower, -15.5℃ or lower, -16℃ or lower, -16.5℃ or lower, -17℃ or lower, -17.5℃ or lower, -18℃ or lower, -18.5℃ or lower.

In an exemplary embodiment, the room temperature measurement value of the maximum sealing strength (unit N/15mm) of the secondary battery pouch film when sealed under 220°C sealing conditions measured by the following method is 140 N/15mm or more in the TD direction. It may be less than N/15mm.

In a non-limiting example, the room temperature measurement value of the maximum sealing strength when sealing under the 220°C sealing condition is 140 N/15mm or more, 145 N/15mm or more, 150 N/15mm or more, 155 N/15mm or more in the TD direction. , 160 N/15mm or more, 165 N/15mm or more, 170 N/15mm or more, 175 N/15mm or more, 180 N/15mm or more, 185 N/15mm or more, 190 N/15mm or more, 195 N/15mm or more, 200 It can be more than N/15mm.

In an exemplary embodiment, the high temperature measurement value of the maximum sealing strength (unit N/15mm) when the secondary battery pouch film was sealed under 220°C sealing conditions measured by the following method (value measured after leaving at 60°C for 3 minutes) ) is 115 N/15mm or more and 170 N/15mm or less in the TD direction.

In a non-limiting example, the high-temperature measurement value of the maximum sealing strength when sealing under the 220°C sealing conditions (value measured after leaving for 3 minutes at 60°C) is 115 N/15mm or more in the TD direction, and 120 N/15mm or more. , 125 N/15mm or more, 130 N/15mm or more, 135 N/15mm or more, 140 N/15mm or more, 145 N/15mm or more, 150 N/15mm or more, 155 N/15mm or more, 160 N/15mm or more, 165 It can be more than N/15mm.

[Method for measuring maximum sealing strength when sealed under 220℃ sealing conditions]

Make a secondary battery pouch film of 100mm

The sealing conditions are Seal Bar Width 200mm

Each sealing strength (load) is measured by pulling the specimen in the MD and/or TD directions with a sealing strength measuring device (e.g., SHIMADZU's AGS-X model UTM equipment), and the measurement conditions are test speed of 10mpm and grip gap. ) Measured at 30mm.

In the case of room temperature measurement, the value was measured at room temperature, and in the case of high temperature measurement, the value was measured after being left for 3 minutes under 60°C conditions. When measuring the sealing strength while pulling the sealing area, the maximum strength is indicated as the maximum sealing strength.

In one exemplary embodiment, the room temperature energy of the secondary battery pouch film measured by the method below is 2.0 to 3.0 KN x mm.

In an exemplary embodiment, the high-temperature energy of the secondary battery pouch film measured by the method below is 1.5 to 2.5 KN x mm.

In one exemplary embodiment, the difference between the room temperature energy and the high temperature energy of the secondary battery pouch film measured by the method below is 0.4 to 0.6 KN x mm.

[Measurement of room temperature energy and high temperature energy]

Measure in the same manner as the sealing strength measurement method described above, except that room temperature energy or high temperature energy is measured at room temperature or high temperature (high temperature is measured after leaving at 60°C for 3 minutes), with the When , it is the area between the sealing strength graph according to the stroke and the stroke X-axis (i.e., the integral value between the sealing strength graph and the

In one exemplary embodiment, the maximum stroke of the secondary battery pouch film at room temperature is 15 to 25 mm, as measured by the method below.

In one exemplary embodiment, the maximum stroke at high temperature of the secondary battery pouch film measured by the method below is 18 to 24 mm.

[Measurement of maximum stroke at room temperature and maximum stroke at high temperature]

Measure in the same manner as the sealing strength measurement method described above, but at room temperature or high temperature (high temperature is measured after leaving for 3 minutes at 60°C). When the As the sealing strength increases, the stroke (distance) at which the sealing strength value reaches its maximum is evaluated as the maximum stroke. If evaluated at room temperature, it is the maximum stroke at room temperature, and if evaluated at high temperature, it is the maximum stroke at high temperature.

In an exemplary embodiment, the outer layer may be composed of nylon, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), a mixed layer of nylon and PET (laminated film of nylon and PET), etc.

In an exemplary embodiment, the nylon film of the outer layer preferably has a thickness of 20 ㎛ or more, and more preferably 25 ㎛ or more, in terms of formability. However, if the nylon film thickness exceeds 30 ㎛, the breakdown voltage may decrease. Accordingly, a preferred nylon film thickness may be 20 μm to 30 μm, preferably 25 μm to 30 μm.

In an exemplary embodiment, the thinner the PET film and the thicker the nylon film among the outer layers are, the more advantageous it is for moldability. However, the thinner the PET film thickness, the more disadvantageous it may be in terms of breakdown voltage, so from this point of view, it is preferable that the PET film is 7㎛ to 12㎛.

In one exemplary embodiment, the metal layer may be composed of a metal such as aluminum, SUS, or copper.

In an exemplary embodiment, the non-stretched polypropylene (CPP) layer or the non-stretched polypropylene (CPP) film of the sealant layer may contain various additives (rubber, elastomer, slip agent, etc.) depending on the required physical properties.

In an exemplary embodiment, the total thickness of the secondary battery pouch film may be, for example, 60 to 185 μm. In one embodiment, the secondary battery pouch film may be 153 ㎛ or more or 113 ㎛ or less.

In an exemplary embodiment, the metal layer thickness may be, for example, 20 to 80 μm, preferably 40 to 60 μm or 60 to 80 μm .

In an exemplary embodiment, the sealant layer thickness may be, for example, 20 to 80 μm.

In an exemplary embodiment, the thickness of the non-stretched polypropylene (CPP) layer of the sealant layer may be, for example, 20 to 80 μm.

In an exemplary embodiment, the thickness of the extruded polypropylene (PP) layer, which is the extruded (EC) layer of the sealant layer, may be, for example, 0 to 60 μm.

Meanwhile, in the method of manufacturing a secondary battery pouch film of exemplary embodiments of the present invention, at least an outer layer, a barrier layer, and a sealant layer are sequentially stacked, and the sealant layer includes an extruded (EC) layer and a polypropylene (PP) layer. A method of manufacturing a secondary battery pouch film, comprising the step of manufacturing the polypropylene (PP) layer in the sealant layer so that the thickness ratio of the polypropylene (PP) layer in the sealant layer is greater than 0.5 when forming an extrusion (EC) layer on the polypropylene (PP) layer in the sealant layer. Includes, the upper yield strength (N/mm ² ) of the sealant layer in the MD direction is 17.50 to 19.99, preferably 17.50 to 19.80, and the upper yield strength (N/mm ² ) in the TD direction is 17.00 to 19.99, preferably Typically, it is 17.00 to 19.50, and the glass transition temperature (Tg) of the sealant layer is within the range of -20℃ to -10℃.

The thickness ratio of the polypropylene (PP) layer among the sealant layers can be obtained by selecting the thickness of the polypropylene (PP) layer itself and controlling the thickness of the extrusion layer (EC) layer when extruding the extrusion resin.

The upper yield strength and glass transition temperature can also be easily adjusted at the skill level of an ordinary technician. As is known, the upper yield strength and glass transition temperature can be determined depending on the type of polypropylene (PP) resin in the sealant layer, properties such as softness, and the content of elastomer-based additives used in the sealant layer. there is. Therefore, the upper yield strength and glass transition temperature can be adjusted by selecting polypropylene and elastomer additives of known appropriate types and properties to have the desired upper yield strength and glass transition temperature.

Meanwhile, exemplary embodiments of the present invention provide secondary batteries externally packaged with the above-described secondary battery pouch film. These secondary batteries may typically be lithium secondary batteries, and in particular, they may be medium to large-sized secondary batteries such as electric vehicles (EV) or energy storage systems (ESS).

Additionally, exemplary embodiments of the present invention provide a secondary battery manufacturing method including the step of packaging the secondary battery with the above-described secondary battery pouch film.

Exemplary embodiments of the present invention are explained in more detail through the following examples. The embodiments disclosed herein are illustrated for illustrative purposes only, and the embodiments of the present invention may be implemented in various forms and should not be construed as limited to the embodiments described herein.

[Experiment 1]

[Examples and Comparative Examples]

In the examples and comparative examples, the outer layer was composed of a composite layer of nylon (25㎛) and PET (12㎛), and the metal layer was made of aluminum foil (60㎛), but as shown in Table 1 below, the extruded layer of the sealant layer and the poly The thickness of the propylene (CPP, non-stretched polypropylene) layer was adjusted and the yield strength and Tg values shown in the table below were used. In addition, each yield strength, Tg, and sealing strength were evaluated by the method described later. The total thickness is 183㎛.

<Strength of surrender>

The specimen is manufactured by peeling off the sealant layer of the pouch film and making it 15mm wide x 100mm long.

The yield strength was measured using SHIMADZU's AGS-X model UTM equipment, and the conditions were 50mpm test speed and 30mm grip gap.

The specimen stretches in proportion to the increase in load, but when it exceeds its elastic limit, it begins to stretch out of proportion to the load, which is called the yield point. In the case of CPP, there is no lower yield point, so the yield point is the upper yield point.

<Tg measurement method>

TA's DSC250 equipment was used. Conditions were measured over a temperature range of -50℃ to 200℃, with a heating rate of 10℃/min and a cooling rate of -20℃/min. The Tg value was calculated using an analysis program (TRIOS) at -50℃~0℃, which is the approximate Tg value range of PP.

<Evaluation of tearing test method and residual rate, etc.>

Fold the secondary battery pouch film in half, place the sealant layer in contact, and perform sealing at 200°C for 1.6 seconds. After sealing, the size of the sample is 20 cm wide x 5 cm long, and the sample is cut into 1.5 cm long pieces.

Both ends of the sample were held and pulled with a universal testing device (UTM) (pulling conditions were 5 mm/min). After pulling the pouch film to tear it more than about 5 mm from the sealing part, measure the thickness (T1; unit ㎛) of the relatively thin side (upper side) and the thickness (T2; unit ㎛) of the relatively thick side (lower side) of the torn area. Each was measured using a thickness gauge. As defined, the survival rate is evaluated as a percentage of the total sealant layer thickness in the sealing area after sealing divided by the total sealant layer thickness in the sealing area before sealing. That is, the residual rate (%) = [Total sealant layer thickness in the sealing area after sealing / Total sealant layer thickness in the sealing area before sealing] x 100.

For each example and comparative example, a total of 10 samples (N=1 to 10) were torn.

Tables 1 to 3 below show the tearing thickness ratio (T1/T2) and tearing thickness difference (T2-T1) of each Example and Comparative Example.

Each Example 1 (1-1 to 1-10) is 10 samples with the same PP layer thickness ratio, phase yield strength, and glass transition temperature among the sealant layers, but the tearing characteristics are also somewhat different because heat is not applied uniformly during sealing. is displayed. The same applies to the 10 samples of Comparative Example 1 (1-1 to 1-10) and the 10 samples of Comparative Example 2 (2-1 to 2-10).

Sealant layer CPP layer (film)/sealant layer thickness ratio direction yield strength MD yield strength+
TD yield strength Sealant layer Tg value Sealant layer
thickness extruded layer CPP layer (film) Example 1 80 30 50 0.625 M.D. 19.22 36.53 -13.41℃ TD 17.31 Comparative Example 1 80 80 0 0 M.D. 17.03 33.76 -22.64℃ TD 16.73 Comparative Example 2 80 30 50 0.625 M.D. 21.91 42.1 -8.68℃ TD 20.19

Example 1 T1
(Thickness of thinner side, ㎛) T2
(Thick side thickness, ㎛) T1/T2 T2-T1 (㎛) Survival rate (%)*
N=1
(Example
1-1) 124 206 0.60 82 77.5 N=2
(Example
1-2) 136 195 0.70 59 78.1 N=3
(Example
1-3) 146 176 0.83 30 72.5 N=4 (Example
1-4) 133 194 0.69 61 75.6 N=5 (Example
1-5) 135 193 0.70 58 76.2 N=6 (Example
1-6) 128 199 0.64 71 75.6 N=7 (Example
1-7) 139 191 0.73 52 77.5 N=8 (Example
1-8) 127 202 0.63 75 76.9 N=9 (Example
1-9) 131 195 0.67 64 75 N=10 (Example
1-10) 131 196 0.67 65 75.6

*Residual rate (%) = [Total sealant layer thickness in the sealing area after sealing / Total sealant layer thickness in the sealing area before sealing] x 100

Comparative Example 1 T1
(Thickness of thinner side, ㎛) T2
(Thick side thickness, ㎛) T1/T2 T2-T1 (㎛) Survival rate (%)*
N=1
(Comparative example
1-1) 96 235 0.41 139 78.1 N=2 (Comparative example
1-2) 95 229 0.41 134 73.8 N=3 (comparative example
1-3) 100 228 0.44 128 76.3 N=4 (comparative example
1-4) 95 232 0.41 137 75.6 N=5 (comparative example
1-5) 94 238 0.39 144 78.8 N=6 (Comparative example
1-6) 98 229 0.43 131 75.6 N=7
(Comparative example
1-7) 98 226 0.43 128 73.8 N=8
(Comparative example
1-8) 100 230 0.43 130 77.5 N=9 (Comparative example
1-9) 99 231 0.43 132 77.5 N=10
(Comparative example
1-10) 97 231 0.42 134 77.5

*Residual rate (%) = [Total sealant layer thickness in the sealing area after sealing / Total sealant layer thickness in the sealing area before sealing] x 100

Comparative Example 2 T1
(Thickness of thinner side, ㎛) T2
(Thick side thickness, ㎛) T1/T2 T2-T1 (㎛) Survival rate (%)*
N=1
(Comparative example
2-1) 102 221 0.46 119 73.3 N=2 (Comparative example
2-2) 110 217 0.51 107 75.6 N=3 (comparative example
2-3) 116 210 0.55 94 75 N=4 (comparative example
2-4) 111 214 0.52 103 74.4 N=5 (comparative example
2-5) 112 214 0.52 102 75 N=6 (Comparative example
2-6) 109 220 0.50 111 76.9 N=7 (Comparative example
2-7) 107 218 0.49 111 74.4 N=8 (comparative example
2-8) 114 210 0.54 96 73.8 N=9 (Comparative example
2-9) 115 211 0.55 96 75 N=10 (comparative example
2-10) 105 223 0.47 118 76.3

*Residual rate (%) = [Total sealant layer thickness in the sealing area after sealing / Total sealant layer thickness in the sealing area before sealing] x 100

<Measurement of maximum sealing strength when sealed under 220℃ sealing conditions>

Examples and Comparative Examples The pouch film was manufactured by cutting a specimen of 100 mm

The sealing conditions were 200mm seal bar width x 10mm seal thickness, 2.0 seconds, 0.2Mpa, and a temperature of 220°C.

The method of measuring the sealing strength is to measure each sealing strength (load) by pulling the specimen in the TD direction with a sealing strength meter (e.g. SHIMADZU's AGS-X model UTM equipment), and the measurement conditions are test speed of 10mpm and grip gap. ) was measured at 30 mm.

In the case of room temperature measurement, it was measured at room temperature, and in the case of high temperature measurement, it was measured after being left for 3 minutes under 60°C conditions.

The maximum value among the measured sealing strength values was taken as the maximum sealing strength. That is, when measuring the sealing strength while pulling the sealing part, the maximum strength was indicated as the maximum sealing strength.

Tables 5 to 7 below show the maximum sealing strength at room temperature and high temperature and the degree of decrease in maximum sealing strength between high temperature and room temperature for each Example and Comparative Example.

Example 1 TD direction
Maximum sealing strength at room temperature
(N/15mm) TD direction
High temperature maximum sealing strength
(N/15mm) Degree of decrease in sealing strength (%)
100 - [(TD direction
Maximum sealing strength at room temperature -
TD direction
high temperature maximum sealing strength)/ (TD direction
Maximum sealing strength at room temperature) N=1
(Example
1-1) 155 130 83.87 N=2 (Example
1-2) 140 126 90.00 N=3 (Example
1-3) 148 127 85.81 N=4 (Example
1-4) 142 120 84.51 N=5 (Example
1-5) 140 127 90.71 N=6 (Example
1-6) 145 125 86.21 N=7 (Example
1-7) 141 122 86.52 N=8 (Example
1-8) 140 123 87.86 N=9 (Example
1-9) 149 128 85.91 N=10 (Example
1-10) 144 126 87.50

Comparative Example 1 TD direction
Maximum sealing strength at room temperature
(N/15mm) TD direction
High temperature maximum sealing strength
(N/15mm) Degree of decrease in sealing strength (%)
100 - [(TD direction
Maximum sealing strength at room temperature -
TD direction
high temperature maximum sealing strength)/ (TD direction
Maximum sealing strength at room temperature) N=1
(Comparative example
1-1) 85 40 47.06 N=2 (Comparative example
1-2) 80 41 51.25 N=3 (comparative example
1-3) 77 44 57.14 N=4 (comparative example
1-4) 82 40 48.78 N=5 (comparative example
1-5) 80 46 57.50 N=6 (Comparative example
1-6) 79 42 53.16 N=7 (Comparative example
1-7) 83 41 49.40 N=8 (comparative example
1-8) 81 43 53.09 N=9 (Comparative example
1-9) 81 44 54.32 N=10 (comparative example
1-10) 78 42 53.85

Comparative Example 2 TD direction
Maximum sealing strength at room temperature
(N/15mm) TD direction
High temperature maximum sealing strength
(N/15mm) Degree of decrease in sealing strength (%)
100 - [(TD direction
Maximum sealing strength at room temperature -
TD direction
high temperature maximum sealing strength)/ (TD direction
Maximum sealing strength at room temperature) N=1
(Comparative example
2-1) 85 62 72.94 N=2 (Comparative example
2-2) 90 62 68.89 N=3 (comparative example
2-3) 94 65 69.15 N=4 (comparative example
2-4) 88 67 76.14 N=5 (comparative example
2-5) 92 62 67.39 N=6 (Comparative example
2-6) 91 63 69.23 N=7 (Comparative example
2-7) 91 65 71.43 N=8 (comparative example
2-8) 87 63 72.41 N=9 (Comparative example
2-9) 94 62 65.96 N=10 (comparative example
2-10) 94 66 70.21

<Measurement of room temperature energy, high temperature energy, and maximum stroke at room temperature and high temperature in the TD direction when sealing under 220℃ sealing conditions>

Room temperature energy and high temperature energy were evaluated to determine the maintenance characteristics of the sealing strength in the TD direction. For this purpose, measure the sealing strength in the same way as the sealing strength measurement method when sealing under the 220℃ sealing condition described above, but at room temperature or high temperature (high temperature is measured after leaving at 60℃ for 3 minutes) with a stroke ( distance), and when the Y axis is the sealing strength, the area between the graph of the change in sealing strength according to the stroke and the energy) or high-temperature energy (energy measured after being left at 60°C for 3 minutes), and when integrated, the stroke is integrated from 0 mm to 20 mm.

Meanwhile, the maximum stroke was measured at room temperature and high temperature to determine the maintenance characteristics of the sealing strength in the TD direction.

That is, measure the sealing strength in the same way as the above-mentioned sealing strength measurement method when sealing under the above-mentioned 220℃ sealing conditions, but by pulling the sealing part in the TD direction with the When the stroke (distance) is set as the sealing strength on the Y axis, the sealing strength increases as the stroke increases, and the stroke (distance) at which the sealing strength value reaches the maximum is evaluated as the maximum stroke. If evaluated at room temperature, it is the maximum stroke at room temperature, and if evaluated at high temperature, it is the maximum stroke at high temperature.

As mentioned above, the above maximum stroke and energy (integral value between the stroke axis and the sealing strength graph) can be said to be important items in evaluating the maintenance characteristics (reliability) of the sealing strength. In other words, even if the maximum sealing strength, which is the peak value, is large, the sealing strength maintenance characteristics cannot be determined based on the maximum sealing strength alone. However, depending on the maximum stroke, it is possible to know how quickly the maximum sealing strength reaches the maximum value and then falls, and also depending on the stroke This is because it is possible to evaluate whether the sealing strength is well maintained, that is, whether it is reliable, through the area (integral value) formed by the and sealing strength curves.

In the case of medium to large-sized batteries such as electric vehicles, there are many molded models in the MD direction, and the sealing properties in the MD direction are generally better than those in the TD direction, so the sealing properties in the TD direction are relatively weaker than sealing in the MD direction (Tap to Pouch sealing). In sealing (pouch to pouch sealing), maintaining the sealing strength becomes a more important measurement interest. Accordingly, the change in sealing strength according to the change in stroke in the TD direction was measured and displayed below.

Example 1 TD direction room temperature maximum stroke (mm) TD direction high temperature maximum stroke (mm) room temperature energy
(KN x mm) high temperature energy
(KN x mm) N=1
(Example
1-1) 22.7 20.6 3.52 2.68 N=2 (Example
1-2) 21.1 21.3 2.95 2.28 N=3 (Example
1-3) 19.8 21.1 2.93 2.68 N=4 (Example
1-4) 21.4 19.7 3.04 2.36 N=5 (Example
1-5) 20.2 19.5 2.83 2.48 N=6 (Example
1-6) 21.9 19.5 3.18 2.43 N=7 (Example
1-7) 22.1 20.8 3.12 2.53 N=8 (Example
1-8) 21.0 20.1 2.94 2.47 N=9 (Example
1-9) 22.4 19.8 3.34 2.53 N=10 (Example
1-10) 20.5 21.0 2.95 2.65

Comparative Example 2 TD direction room temperature maximum stroke (mm) TD direction high temperature maximum stroke (mm) room temperature energy
(KN x mm) high temperature energy
(KN x mm) N=1
(Comparative example
2-1) 15.4 13.8 1.31 0.55 N=2 (Comparative example
2-2) 15.1 13.5 1.21 0.55 N=3 (comparative example
2-3) 14.7 13.2 1.13 0.58 N=4 (comparative example
2-4) 15.2 14.0 1.25 0.56 N=5 (comparative example
2-5) 16.1 14.1 1.29 0.65 N=6 (Comparative example
2-6) 15.3 13.3 1.21 0.56 N=7 (Comparative example
2-7) 14.9 14.3 1.24 0.59 N=8 (comparative example
2-8) 15.3 12.6 1.24 0.54 N=9 (Comparative example
2-9) 15.3 13.7 1.24 0.60 N=10 (comparative example
2-10) 15.8 13.0 1.23 0.54

Comparative Example 2 TD direction room temperature maximum stroke (mm) TD direction high temperature maximum stroke (mm) room temperature energy
(KN x mm) high temperature energy
(KN x mm) N=1
(Comparative example
2-1) 16.1 17.4 1.37 1.08 N=2 (Comparative example
2-2) 17.1 16.2 1.54 1.00 N=3 (comparative example
2-3) 16.5 16.0 1.55 1.04 N=4 (comparative example
2-4) 18.0 15.7 1.58 1.05 N=5 (comparative example
2-5) 17.4 17.1 1.60 1.06 N=6 (Comparative example
2-6) 16.8 17.5 1.53 1.10 N=7 (Comparative example
2-7) 18.1 16.7 1.65 1.09 N=8 (comparative example
2-8) 17.5 16.8 1.52 1.06 N=9 (Comparative example
2-9) 17.6 15.9 1.65 0.99 N=10 (comparative example
2-10) 17.2 16.7 1.62 1.10

As seen above, the examples showed superior characteristics than the comparative examples in terms of maximum sealing strength at room temperature and maximum sealing strength at high temperature. In addition, room temperature energy, high temperature energy, room temperature maximum stroke, and high temperature maximum stroke were all superior to the comparative examples.

Therefore, it can be seen that the Example not only has excellent sealing strength characteristics at room temperature and high temperature compared to the Comparative Examples, but also has excellent sealing strength maintenance characteristics at room temperature and high temperature. In addition, as a result of the liquid leak test, the number of liquid leaks was significantly less than that of the comparative examples, showing that the battery pack has excellent long-term reliability at high temperatures and thus has excellent battery safety.

[Experiment 2]

In this experiment 2, it was manufactured as in Example 1 of the above-mentioned experiment 1, but the sealing conditions (temperature, pressure, time) were changed so that the residual rate was as shown in the table below.

The following table lists the survival rate, tearing thickness ratio (T1/T2), and sealing strength. The evaluation method for this item is the same as Experiment 1.

item of experiment 2
Example 1 of experiment 2
Comparative Example 1 of experiment 2
Comparative example 2 of experiment 2
Comparative Example 3 of experiment 2
Comparative example 4 Total thickness/sealant layer thickness 183/80 183/80 183/80 183/80 183/80 Survival rate 76.0 84.7 64.5 62.5 82.3 Tear thickness ratio 0.7 0.68 0.63 0.68 0.6 Room temperature sealing strength in TD direction 144 130 140 138.3 114.7

As can be seen from the above, even if the tear thickness ratio is similar, the sealing strength is superior when the residual ratio is in the range of 70 to 80%.

Although non-limiting and exemplary embodiments of the present invention have been described above, the technical idea of the present invention is not limited to the accompanying drawings or the above description. It is obvious to those skilled in the art that various forms of modification are possible without departing from the technical spirit of the present invention, and such modifications will fall within the scope of the patent claims of the present invention.

Claims (12)

As a secondary battery pouch film,
At least the outer layer, barrier layer, and sealant layer are sequentially laminated,
The sealant layer is extrusion laminated by an extrusion coating layer,
The sealant layer thicknesses T1 and T2 measured according to the tearing test method below satisfy [Equation 1],
A secondary transfer pouch film characterized in that the residual ratio of [Formula 2] below is 70 to 80.
[Equation 1]
0.6 < T1 / T2 < 0.85
[Equation 2]
Residual rate (%) = [Total sealant layer thickness in the sealing area after sealing / Total sealant layer thickness in the sealing area before sealing] x 100
[Tearing test method]
Fold the secondary battery pouch film in half, place the sealant layer in contact, and perform sealing at 200°C for 1.6 seconds. After sealing, the size of the sample is 20 cm wide x 5 cm high, and the sample is cut into 1.5 cm long pieces.
Hold both ends of the sample and pull it with a universal testing device (UTM) (pulling condition is 5 mm/min). After pulling the pouch film so that it is torn by about 5 mm or more from the sealing part, the thickness (T1) of the side where the thickness of the torn area is relatively thin or the same (upper side) and the side where the thickness of the torn area is relatively thick or the same (lower side) Measure the thickness (T2) of each using a thickness gauge. That is, T2 ≥ T1.
According to claim 1,
The secondary battery pouch film is a secondary battery pouch film, wherein T1 and T2 satisfy [Equation 3] below.
[Equation 3]
T2 - T1 <85㎛
According to claim 1,
The secondary battery pouch film is characterized in that the maximum room temperature sealing strength measurement value when sealed under 220°C sealing conditions measured by the following method is 140N/15mm or more and 205N/15mm or less in the TD direction.
[Method for measuring maximum room temperature sealing strength when sealed under 220℃ sealing conditions]
After making a secondary battery pouch film of 100mm
The sealing conditions are Seal Bar Width 200mm
Each sealing strength in the MD and TD directions of the specimen is measured at room temperature with a sealing strength meter, and the sealing conditions are measured at a test speed of 10mpm and a grip gap of 30mm.
The maximum value of the sealing strength measurements is the maximum sealing strength.
According to claim 1,
The maximum high-temperature sealing strength measurement value of the secondary battery pouch film when sealed under 220°C sealing conditions measured by the following method (sealing strength measured after leaving at 60°C for 3 minutes) is 115N/15mm or more 170N in the TD direction. / Secondary battery pouch film characterized in that it is 15 mm or less.
[Method for measuring maximum high temperature sealing strength when sealed under 220℃ sealing conditions]
After making a secondary battery pouch film of 100mm
The sealing conditions are seal bar width 200mm
With a sealing strength meter, the sealing strength of one or more of the MD and TD directions of the specimen is measured after leaving it for 3 minutes at 60℃, and the sealing conditions are measured at a test speed of 10mpm and a grip gap of 30mm.
The maximum value of the sealing strength measurements is the maximum sealing strength.
According to claim 1,
The secondary battery pouch film is characterized in that the room temperature energy in the TD direction when sealed under 220°C sealing conditions measured by the following method is 2.0 to 3.0 KN x mm.
[Measurement of room temperature energy in TD direction when sealed under 220℃ sealing conditions]
After making a secondary battery pouch film of 100mm
The sealing conditions are seal bar width 200mm
Measure the change in sealing strength by pulling the specimen in the TD direction with a sealing strength meter at room temperature, and the measurement conditions are test speed of 10mpm and grip gap of 30mm.
When the Value - is defined as room temperature energy, and the integration is from the stroke range of 0mm to 20mm.
According to claim 1,
The secondary battery pouch film is characterized in that the high temperature energy in the TD direction when sealed under 220°C sealing conditions measured by the following method is 1.5 to 2.5 KN x mm.
[Measurement of high temperature energy in TD direction when sealed under 220℃ sealing conditions]
After making a secondary battery pouch film of 100mm
The sealing conditions are Seal Bar Width 200mm
The change in sealing strength is measured by pulling in the TD direction of the specimen with a sealing strength meter under high temperature conditions measured after leaving at 60℃ for 3 minutes. The measurement conditions are test speed of 10mpm and grip gap of 30mm.
When the The value - is defined as high-temperature energy, and the integration is from the stroke range of 0mm to 20mm.
According to claim 1,
The secondary battery pouch film is characterized in that the difference between room temperature energy and high temperature energy in the TD direction when sealed under 220°C sealing conditions measured by the following method is 0.4 to 0.6 KN x mm.
[Measurement of room temperature energy and high temperature energy in the TD direction when sealed under 220℃ sealing conditions]
After making a secondary battery pouch film of 100mm
The sealing conditions are Seal Bar Width 200mm
Measure the change in sealing strength by pulling the specimen in the TD direction with a sealing strength meter under room temperature conditions or high temperature conditions measured after leaving it for 3 minutes at 60°C. The measurement conditions are test speed of 10mpm and grip gap of 30mm. box
When the The value - is defined as room temperature energy or high temperature energy, and the integral is the integration from the stroke range of 0mm to 20mm.
Energy when measured under room temperature conditions is room temperature energy, and energy when measured under high temperature conditions is high temperature energy.
According to claim 1,
The secondary battery pouch film is characterized in that the maximum stroke at room temperature in the TD direction when sealed under 220°C sealing conditions as measured by the following method is 15 to 25 mm.
[Measurement of maximum stroke at room temperature in TD direction when sealed under 220℃ sealing conditions]
After making a secondary battery pouch film of 100mm
The sealing conditions are Seal Bar Width 200mm
Measure the change in sealing strength by pulling the specimen in the TD direction with a sealing strength meter at room temperature, and the measurement conditions are test speed of 10mpm and grip gap of 30mm.
When the box
According to claim 1,
The secondary battery pouch film is characterized in that the high temperature maximum stroke in the TD direction when sealed under 220°C sealing conditions measured by the following method is 18 to 24 mm.
[Measurement of high temperature maximum stroke in TD direction when sealed under 220℃ sealing conditions]
After making a secondary battery pouch film of 100mm
The sealing conditions are Seal Bar Width 200mm
The change in sealing strength is measured by pulling in the TD direction of the specimen with a sealing strength meter under high temperature conditions measured after leaving at 60℃ for 3 minutes. The measurement conditions are test speed of 10mpm and grip gap of 30mm.
When the box
A secondary battery, characterized in that it is exteriorized with the secondary battery pouch film of any one of claims 1 to 9.
According to claim 10,
The secondary battery is characterized in that the secondary battery is for an electric vehicle or an energy storage device.
As a secondary battery manufacturing method,
A secondary battery manufacturing method comprising: packaging the secondary battery with the secondary battery pouch film of any one of claims 1 to 9.