WO2015046744A1

WO2015046744A1 - Pouch-type battery cell comprising film member for protecting electrode lead-electrode tap joint

Info

Publication number: WO2015046744A1
Application number: PCT/KR2014/007260
Authority: WO
Inventors: 유재훈; 정태윤; 한창민; 조지훈; 남상봉
Original assignee: 주식회사 엘지화학
Priority date: 2013-09-24
Filing date: 2014-08-06
Publication date: 2015-04-02
Also published as: JP6204598B2; CN105684183B; KR101666418B1; CN105684183A; JP2016529683A; KR20150033281A

Abstract

The present invention provides a pouch-type battery cell which is characterized in that: an electrode assembly is embedded in a battery cell case of a laminate sheet comprising a material-barrier metal layer and a heat-fusible first resin layer; the electrode lead is projected to the outside of the battery cell case in a state where electrode taps of the electrode assembly are connected to the electrode lead as an electrode terminal; the outer circumferential surface of the battery cell case is sealed by the thermal fusion of the first resin layer; and a film member of the same material as the first resin layer encloses the joint portion of the electrode tab and the electrode lead.

Description

Pouch-type battery cell including a film member for protecting the electrode lead-electrode tab coupling portion

The present invention relates to a pouch-type battery cell comprising a film member for protecting the electrode lead-electrode tab coupling portion.

With the development of technology and increasing demand for mobile devices, the demand for secondary batteries is also rapidly increasing. Among them, lithium secondary batteries with high energy density, high operating voltage, and excellent storage and life characteristics are used for various mobile devices as well as various electronic products. It is widely used as an energy source.

Lithium secondary batteries are largely classified into cylindrical batteries, square batteries, pouch-type batteries, and the like according to their appearance, and may be classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, and the like depending on the type of electrolyte.

Due to the recent trend toward the miniaturization of mobile devices, there is an increasing demand for thinner rectangular batteries and pouch-type batteries. In particular, for pouch-type batteries that are easy to deform, low in manufacturing cost and light in weight. Interest is high.

Generally, a pouch type battery refers to a battery in which an electrode assembly and an electrolyte are sealed inside a pouch type case of a laminate sheet including a resin layer and a metal layer. The electrode assembly accommodated in the battery case may have a structure of jelly-roll type (wound type), stacked type (stacked type), or complex type (stack / folding type).

1 schematically illustrates a structure of a pouch-type battery cell including a stacked electrode assembly.

Referring to FIG. 1, in the pouch-type battery cell 10, an electrode assembly 30 including an anode, a cathode, and a separator disposed therebetween is formed inside the pouch-type battery case 20. The two electrode leads 40 and 41 electrically connected to the 31 and 32 may be sealed to be exposed to the outside.

The battery case 20 includes a case body 21 including a recess 23 having a concave shape in which the electrode assembly 30 may be seated, and a cover 22 integrally connected to the body 21. Can be.

Although not shown, the battery case may include a lower case including a concave shape receiving portion in which the electrode assembly may be seated, and an upper case sealing the electrode assembly as a cover of the lower case.

The battery case 20 may be formed of a laminate sheet, and may include a barrier metal layer 20a for preventing the penetration of a material, and an inner resin layer 20b for sealing.

In the stacked electrode assembly 30, a plurality of positive electrode tabs 31 and a plurality of negative electrode tabs 32 may be fused to each other and coupled to the electrode leads 40 and 41. In addition, when the upper end 24 of the case body 21 and the upper end of the cover 22 are heat-sealed by a heat sealer (not shown), a short is generated between the heat welder and the electrode leads 40 and 41. The insulating film 50 may be attached to upper and lower surfaces of the electrode leads 40 and 41 in order to prevent it and to secure the sealing property between the electrode leads 40 and 41 and the battery case 20.

However, such a pouch-type battery cell is less susceptible to external impact than a can-type battery, and has an insulation resistance when an external force is applied to a portion where the electrode tab and the electrode lead are coupled, or when the inner resin layer of the laminate sheet constituting the battery case is small. There is a problem that this becomes small or short occurs. In addition, even if an insulating film is attached to the electrode lead, there is a disadvantage that the leakage occurs in this area.

On the other hand, some prior art discloses a battery cell having a structure in which a protective tape is attached to protect a portion where the electrode lead and the electrode tab are coupled, but such a structure has a portion where the protective tape is attached to the battery case. When the sealing tape is sealed by heat fusion, the protective tape has a problem in that insulation failure occurs due to deformation or breakage due to interference caused by heat.

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

An object of the present invention, by using a structure that wraps the electrode lead-electrode tab connection portion of the battery cell with a film member, a pouch of the structure to improve the safety by solving problems such as reduced insulation resistance, leakage, swelling due to high temperature It is to provide a type battery cell.

Pouch-type battery cell according to the present invention for achieving this object,

The electrode assembly is embedded in a battery cell case of a laminate sheet including a material barrier metal layer and a heat sealable first resin layer,

The electrode lead protrudes out of the battery cell case while the electrode tabs of the electrode assembly are connected to an electrode lead as an electrode terminal.

The outer peripheral surface of the battery cell case is sealed by thermal fusion of the first resin layer,

The film member of the same material as the first resin layer may include a structure surrounding the connection portion between the electrode tab and the electrode lead.

That is, the pouch-type battery cell according to the present invention has a structure of surrounding the film member in a connection portion between the electrode tab and the electrode lead and includes a structure for protecting the connection portion. At this time, the film member is formed of the same material as that of the heat-sealable first resin layer of the laminate sheet, so that problems such as insulation, leakage, and swelling due to high temperature may occur even if interference occurs during the heat-sealing of the battery cell case. It consists of a structure to prevent the occurrence of.

The laminate sheet may be formed in a structure including a second resin layer as an outer coating layer, in addition to the metal layer and the first resin layer. The second resin layer insulates the metal layer from the outside, and may be configured to protect the battery case from the outside by using a material having excellent durability or rigidity.

In one specific example, the material of the first resin layer is not electrically limited as a material capable of thermal fusion without affecting the operation of the battery as an electrically insulating material, for example, stiffness, repeated fatigue resistance, and It may be a polypropylene resin layer excellent in chemical resistance.

Specifically, the first resin layer may be configured to include a non-stretched polypropylene (CPP) excellent in heat sealability among the polypropylene resin. Accordingly, the film member may also be formed in a structure including lead-free polypropylene.

The film member is a structure surrounding the connection portion of the electrode tab and the electrode lead is not limited in shape, for example, consisting of two adhesive films for each of the connection portion of the electrode tab and the electrode lead, The adhesive films may have a structure in which they are attached to each other while surrounding the connection site.

As another example, the film member may be formed of one adhesive film for each of the connection portions of the electrode tab and the electrode lead, and may have a structure in which the one adhesive film is attached to surround the connection portion.

The film member may have a size surrounding the coupling portion of the electrode tab and the electrode lead, and the width of the film member may be formed to be at least the width of the coupling portion of the electrode tab and the electrode lead.

Specifically, the width of the film member may have a size of 100% to 200% of the width of the coupling portion of the electrode tab and the electrode lead. That is, the width of the film member may be formed in a range of 100% to 200% with respect to the width of the coupling portion of the electrode tab and the electrode lead, it may be formed of a structure that completely surrounds the coupling portion of the electrode tab and the electrode lead. have.

Such a film member may be attached to the coupling portion in a structure in which its lower end in the longitudinal direction (height direction) coincides with the lower end of the coupling portion of the electrode tab and the electrode lead or extends downward from the lower end of the coupling portion. In addition, the film member surrounds the coupling portion of the electrode tab and the electrode lead, the upper end in the longitudinal direction (height direction) of the film member is formed to have a structure located above the upper end of the coupling portion of the electrode tab and electrode lead. Can be. Specific examples of such a structure are as follows.

In a first example, an insulating film is interposed between the electrode lead and the sealing portion of the battery cell case, and the film member has a structure in which an upper end of the length direction (height direction) is attached to surround a portion of the insulating film. Can be.

In a second example, an insulating film is interposed between the electrode lead and the sealing portion of the battery cell case, and the film member is formed to have a structure in which an upper end in a longitudinal direction (height direction) is attached to cover the entirety of the insulating film. Can be.

In a third example, an insulating film is interposed between the electrode lead and the sealing portion of the battery cell case, and the film member is formed in a structure in which an upper end in a length direction (height direction) is attached to contact the lower end of the insulating film. Can be.

The film member may have a thickness of 40 to 60 micrometers. If the thickness of the film member is too thick, the tension during the heat shrinkage can greatly reduce the adhesive strength, on the contrary, if the thickness is too thin, it is not preferable because the physical properties are smaller.

On the other hand, the film member may be added to the adhesive layer on the base material of the same material as the first resin layer in order to improve the adhesion. The adhesive layer is not particularly limited as a material providing adhesiveness without reacting with the electrolyte solution inside the battery cell, and may be formed of, for example, an acrylic resin.

The substrate and the adhesive layer may be formed to an appropriate thickness to effectively exhibit the physical properties of the substrate and the adhesive performance by the adhesive layer. As a specific example, as mentioned above, the thickness of the film member may be formed to 40 to 60 micrometers, wherein the thickness of the substrate may be formed to 35 to 45 micrometers, the thickness of the adhesive layer It may be formed from 5 to 15 micrometers.

The battery cell may be a lithium ion battery or a lithium ion polymer battery cell, but is not limited thereto.

The present invention also provides a battery pack comprising at least one of the battery cells. Specifically, the battery pack may be formed of a structure in which one battery cell is mounted, or a structure of high output or large capacity in which a plurality of battery cells are connected in series and / or in parallel.

The present invention also provides a device including the battery pack. The device is selected from a mobile phone, a portable computer, a smartphone, a tablet PC, a smart pad, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage device. Can be.

1 is an exploded perspective view of a conventional pouch-type battery cell;

2 is a schematic diagram showing a structure in which a film member is added to an electrode tab-electrode lead coupling portion according to an embodiment of the present invention;

3 is an enlarged view of a portion A of FIG. 2;

4 is a cross-sectional view of the battery cell case of Figure 2 and a cross-sectional view of the film member;

5 to 7 are schematic views showing a structure in which a film member is added to an electrode tab-electrode lead coupling portion according to another embodiment of the present invention.

Hereinafter, although described with reference to the drawings according to an embodiment of the present invention, this is for easier understanding of the present invention, the scope of the present invention is not limited thereto.

In the drawings, for convenience of description, the electrode assembly inside the battery cell case and the coupling portion of the electrode tab and the electrode lead are mainly shown.

2 is a schematic view of a structure in which a film member is added to an electrode tab-electrode lead coupling portion according to an embodiment of the present invention, and FIG. 3 is an enlarged view of a portion A of FIG. 4 is a cross-sectional view of the battery cell case of Figure 2 and a cross-sectional view of the film member.

Referring to these drawings, the pouch-type battery cell 100 has a structure in which the electrode assembly 110 is built in the battery cell case 120. The battery cell case 120 of the laminate sheet includes a metal layer 127 and a first resin layer 128, and the outer circumferential surface of the battery cell case 110 is sealed by thermal fusion of the first resin layer 128. It consists of a structure.

In the state where the electrode tabs 112 of the electrode assembly 110 are connected to the electrode leads 130, the electrode leads 130 protrude out of the battery cell case 120, and the electrode tabs 112 and the electrode leads ( The connection portion 130 is attached to the structure wrapped around the film member 140, the connection portion of the electrode tab 112 and the electrode lead 130 is made of a structure that is protected by the film member 140.

The laminate sheet is composed of a structure including a metal barrier material 127, a heat sealable first resin layer 128, and a second resin layer 129 as an outer coating layer. The second resin layer 129 insulates the metal layer 127 from the outside and is formed of a material having excellent durability or rigidity to protect the battery cell case 120 from the outside.

The first resin layer 128 is a polypropylene-based resin layer having excellent repeated fatigue resistance and chemical resistance, and is composed of a structure including unstretched polypropylene (CPP).

The film member 140 includes an unstretched polypropylene layer, and is formed to have a size surrounding the connection portion S of the electrode tab 112 and the electrode lead 130, and the electrode tab 112 and the electrode lead ( It is attached to the connection site S of 130, respectively. The film member 140 is composed of two adhesive films for each of the connection portion S of the electrode tab 112 and the electrode lead 130, the two adhesive films are mutually enclosing the connection portion (S) Attached.

In addition, the film member 140 is formed with an adhesive layer 144 made of an acrylic resin on the unstretched polypropylene layer 142 to improve adhesion. The thickness (W) of the film member 140 has a size of 50 micrometers, the thickness of the unstretched polypropylene layer 142 is 40 micrometers, the thickness of the acrylic adhesive layer 144 is formed to a size of 10 micrometers It is.

5 and 7 are schematic views showing a structure in which a film member is added to an electrode tab-electrode lead coupling portion according to another embodiment of the present invention.

Referring to these drawings, the film member is attached so that the lower end in its longitudinal direction (height direction) surrounds the lower end of the coupling portion of the electrode tab and the electrode lead, and the upper end of the film member in the longitudinal direction (height direction) of the electrode It is formed in a structure located above the upper end of the coupling portion of the tab and the electrode lead.

First, referring to FIG. 5, an insulating film 150 disposed between the electrode lead 130 and the sealing portion of the battery cell case is interposed therebetween, and the film member 240 has an insulating film having an upper end in a length direction (height direction). It is formed in the structure attached so that a part of 150 may be enclosed.

Referring to FIG. 6, an insulating film 150 is disposed between the electrode lead 130 and the sealing portion of the battery cell case, and the film member 340 has an insulating film at an upper end in a length direction (height direction). It is formed in a structure attached to contact with the lower end of the (150).

Referring to FIG. 7, an insulating film 150 is disposed between the sealing portions of the battery cell case, and the film member 440 has an upper end in the longitudinal direction (height direction) of the insulating film 150. It is formed in a structure that is attached to surround.

Experimental Example 1

A non-stretched polypropylene (CPP) was used as the material of the film member, and the structure of the film member attached to the electrode tab-electrode lead connecting portion S as shown in FIG. 3 (attachment position a), as shown in FIG. Attached structure of the film member to surround the tab-electrode lead connection part S (attachment position b), Attached structure of the film member to surround the electrode tab-electrode lead connection site S as shown in FIG. c) and the structure (attachment position d) of the film member is manufactured to surround the electrode tab-electrode lead connecting portion S, respectively, as shown in FIG. 7, and swelling in insulation resistance, leakage, and high temperature and high humidity environment, respectively. The test was performed.

Comparative Example 1

Polyimide (PI) was used as the material of the film member, and the structure of the film member attached to the electrode tab-electrode lead connecting portion S as shown in FIG. 3 (attachment position a), and the electrode tab- as shown in FIG. Attached structure of the film member to surround the electrode lead connection site (S) (attachment position b), Attached structure of the film member to surround the electrode tab-electrode lead connection site (S) as shown in FIG. , And as shown in FIG. 7, the fabricated structure (attachment position d) of the film member was formed to surround the electrode tab-electrode lead connection portion S, respectively, and the insulation resistance, the leakage, and the swelling test in the high temperature and high humidity environment, respectively. Was performed.

Comparative Example 2

Biaxially stretched polypropylene (OPP) was used as the material of the film member, and the structure of the film member attached to surround the electrode tab-electrode lead connection portion S as shown in FIG. 3 (attachment position a), as shown in FIG. The structure of attaching the film member to surround the electrode tab-electrode lead connection site S (attachment position b), the structure of the film member to enclose the electrode tab-electrode lead connection site S as shown in FIG. Position c) and the attached structure (attachment position d) of the film member so as to surround the electrode tab-electrode lead connecting portion S as shown in FIG. 7, respectively, and swell in insulation resistance, leakage, and high temperature and high humidity environment, respectively. Ring test was performed.

And, the experimental results of Experimental Example 1, Comparative Example 1, and Comparative Example 2 are shown in Table 1 below.

Table 1

Referring to Table 1, the structure using the polyimide and biaxially stretched polypropylene as the film member was confirmed to be a risk or a defect as a result of insulation resistance, leakage, and swelling test when the insulation film was partially or completely enclosed.

In addition, in the case of using the polyimide as the film member, when the upper end of the film member was attached so as to contact the lower end of the insulating film, it was confirmed that the insulation resistance test results are poor.

However, in the case of the structure using the non-stretched polypropylene as the film member, it was confirmed that it is a good judgment in the insulation resistance, leakage, and swelling test irrespective of the position and the range of attachment.

Those skilled in the art to which the present invention pertains will be able to add various applications and modifications within the scope of the present invention based on the above contents.

As described above, the pouch-type battery cell according to the present invention includes a structure surrounding the film member at the connection portion between the electrode tab and the electrode lead, thereby providing an effect of protecting the connection portion by the film member.

In addition, the pouch-type battery cell according to the present invention forms the film member with the same material as the material of the heat-sealable first resin layer of the laminate sheet, so that even if interference occurs during thermal fusion of the battery cell case, insulation, leakage, It provides an effect of improving safety by preventing problems such as swelling caused by high temperature.

Claims

The electrode assembly is embedded in a battery cell case of a laminate sheet including a material barrier metal layer and a heat sealable first resin layer,

The electrode lead protrudes out of the battery cell case while the electrode tabs of the electrode assembly are connected to an electrode lead as an electrode terminal.

The outer peripheral surface of the battery cell case is sealed by thermal fusion of the first resin layer,

A pouch-type battery cell, wherein a film member of the same material as the first resin layer surrounds a connection portion between an electrode tab and an electrode lead.
The pouch type battery cell according to claim 1, wherein the laminate sheet further includes a second resin layer as an outer coating layer in addition to the metal layer and the first resin layer.
The pouch type battery cell according to claim 1, wherein the material of the first resin layer is a polypropylene resin.
The pouch-type battery cell of claim 3, wherein the polypropylene-based resin comprises unstretched polypropylene (CPP).
The pouch of claim 1, wherein the film member comprises two adhesive films for each of the connection portions of the electrode tab and the electrode lead, and the two adhesive films are attached to each other while surrounding the connection portion. Type battery cell.
The pouch type battery of claim 1, wherein the film member comprises one adhesive film for each of the connection portions of the electrode tab and the electrode lead, and the one adhesive film is attached to surround the connection portion. Cell.
The pouch type battery cell of claim 1, wherein the film member is formed to have a width equal to or greater than a width of a coupling portion between the electrode tab and the electrode lead.
The pouch type battery cell of claim 7, wherein the film member has a width of 100% to 200% with respect to the width of the coupling portion between the electrode tab and the electrode lead.
The method of claim 1, wherein an insulating film is interposed between the electrode lead and the sealing portion of the battery cell case, wherein the film member is attached so that an upper end in the longitudinal direction (height direction) surrounds a portion of the insulating film. Pouch type battery cell.
The method of claim 1, wherein an insulating film is interposed between the electrode lead and the sealing portion of the battery cell case, wherein the film member is attached so that the upper end in the longitudinal direction (height direction) surrounds the entire insulating film. Pouch type battery cell.
The method of claim 1, wherein an insulating film is interposed between the electrode lead and the sealing portion of the battery cell case, the film member is attached so that the upper end in the longitudinal direction (height direction) is in contact with the lower end of the insulating film. Pouch type battery cell.
The pouch type battery cell of claim 1, wherein the film member has a thickness of 40 to 60 micrometers.
The pouch type battery cell according to claim 1, wherein the film member has a structure in which an adhesive layer is added on a substrate of the same material as the first resin layer.
The pouch type battery cell according to claim 13, wherein the adhesive layer is made of acrylic resin.
The pouch type battery cell of claim 13, wherein the substrate has a thickness of 35 to 45 micrometers and the adhesive layer has a thickness of 5 to 15 micrometers.
The battery cell according to claim 1, wherein the pouch-type battery cell is a lithium secondary battery.
A battery pack comprising one or more battery cells according to claim 1.
A device comprising a battery pack according to claim 17.