KR20100005810A - Pouch having enhanced adhebility, method for manufacturing the same, and secondary battery comprising the same - Google Patents

Abstract

PURPOSE: A pouch for a secondary battery is provided to improve adhesive force of pouch by including a magentic layer, to prevent moisture penetration and leak of electrolyte, and to improve safety of a secondary battery. CONSTITUTION: A pouch for a secondary battery is a laminate in which a heat fusion layer(110), metal layer(120), outer layer(130) are lamintated, and further comprises magnetic layers(140a,140b,140c,140d). The magnetic layer is made of at least one selected from the group consisting of ferrite-based, Ni, Co, W, Fe and their alloy. The magnetic layer is installed between a hot-melting layer and a metal layer, or metal layer and external layer.

Description

Pouch having enhanced adhebility, method for manufacturing the same, and secondary battery comprising the same}

The present invention improves the adhesion of the pouch by forming a magnetic layer by applying a magnetic material to at least one layer constituting the pouch to form a magnetic layer in the manufacture of the pouch of the secondary battery to prevent the penetration of water or leakage of electrolyte solution to improve the safety of the secondary battery It relates to a pouch that can be improved, a method for manufacturing the same, and a secondary battery including the same.

As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is increasing rapidly. Among them, many researches have been conducted and commercialized and widely used for lithium secondary batteries with high energy density and discharge voltage. It is used.

Secondary batteries are rechargeable batteries, and are widely used in advanced electronic devices such as cellular phones, notebook computers, and camcorders, which are called 3C products. In particular, the lithium secondary battery has an operating voltage of 3.6 V, which is three times higher than that of a nickel-cadmium (Ni-Cd) battery or a nickel-hydrogen (Ni-MH) battery, which is widely used as an electronic equipment power source. It is rapidly expanding in that it is excellent.

Lithium secondary batteries are manufactured in various shapes, and typical shapes include cylindrical and square shapes mainly used in lithium-ion batteries. Lithium polymer batteries are more flexible than lithium ion batteries and their shapes are relatively free.

Accordingly, in recent years, lithium-ion batteries and lithium polymer batteries have excellent safety and freedom of shape, are light in weight, and are advantageous for slimmer and lighter portable electronic devices.

The secondary battery has a structure in which an electrode assembly having a separator interposed between a positive electrode and a negative electrode is sealed in a case in which an electrolyte is impregnated. The electrode assembly is a jelly-roll type in which both the positive electrode and the negative electrode are coated on both sides of a long sheet-shaped current collector foil with a separator, and the electrode active material is coated on both sides of the current collector foil having a constant unit size. A plurality of anodes and cathodes are divided into stacks sequentially stacked in an ecological manner through a separator. Among them, the jelly-roll type electrode assembly has advantages of easy manufacturing and high energy density per weight.

Specifically, the jelly-roll is a circular cross-section of the two sheets in a state in which the separator is placed between the negative electrode sheet and the positive electrode sheet to which the active material is applied and another separator is placed on the outer surface of the negative electrode sheet or the outer surface of the positive electrode sheet. It is made of a cylindrical battery by winding in a structure of a built-in cylindrical case, or by forming a rectangular battery by compressing the cylindrical structure and built in a rectangular battery case.

According to the case where the jelly-roll is made of a cylindrical cell or a rectangular cell, the positions of the electrode tabs for the electrical connection are changed. For example, when a jelly-roll is applied to a cylindrical cell, its negative electrode tab is positioned as the outermost negative electrode sheet itself so that it can be directly connected to the cylindrical battery case as the negative electrode terminal, and the positive electrode tab is coated with an active material on the positive electrode sheet. It is located in the form of a protruding welded to a part which is not present. With this structure, a stepped portion is formed at the core portion of the jelly-roll by a positive electrode tab welded to the positive electrode sheet.

Due to the occurrence of the step, when the upper and lower cases made of a multilayer film are joined by heat fusion in the state where the ends of the positive electrode and the negative electrode terminal are drawn out to the outside of the polymer lithium battery, the inside of the polymer lithium battery is incomplete because of adhesiveness. A problem arises that the electrolyte solution flows out or outside air flows into the pouch battery. Due to such a problem, there is a disadvantage in reducing the safety of the pouch battery.

Therefore, the present invention is intended to solve the problems of the prior art in which electrolyte solution is introduced into the pouch battery or moisture is infiltrated, thereby decreasing battery safety.

The inventors of the present invention include a magnetic layer in which magnetic materials are constantly oriented when manufacturing a pouch packaging material of a battery, thereby improving adhesion between pouches, preventing water penetration or leakage of an electrolyte, and thus improving battery safety.

Accordingly, an object of the present invention is to provide a pouch of a secondary battery excellent in the adhesive force of the pouch packaging material and a method of manufacturing the same.

In addition, another object of the present invention to provide a secondary battery including the pouch as described above.

When manufacturing the pouch as described in the present invention by applying a magnetic material to at least one layer constituting the pouch to form a magnetic layer to improve the adhesion of the pouch by improving the adhesion of the pouch to prevent the penetration of moisture or leakage of the electrolyte to improve the safety of the secondary battery Can be.

The pouch of the present invention for achieving the above object is characterized in that it further comprises a magnetic layer in the pouch for secondary batteries in which the heat-sealing layer, the metal layer, the outer layer is sequentially stacked.

In addition, the manufacturing method of the pouch to achieve another object of the present invention is characterized in that it comprises the step of applying a magnetic layer on at least one layer of the secondary battery pouch in which the heat sealing layer / metal layer / outer layer is sequentially laminated. .

In addition, a secondary battery for achieving another object of the present invention is characterized in that it comprises the pouch.

Hereinafter, the present invention will be described in more detail.

Next, FIG. 1 illustrates a structure of a pouch case 100 formed of a conventional heat seal layer 10 / metal layer 20 / outer layer 30.

The battery according to the present invention is manufactured by coating an electrode assembly consisting of a positive electrode, a negative electrode, and a separator with a pouch case made of a laminated film having a thickness of about 100 μm. The pouch sheath is generally composed of a heat seal layer / metal layer / outer layer, and may further include a plurality of polymer layers between the heat seal layer and the metal layer and between the metal layer and the outer layer to improve strength and heat resistance. . In the pouch structure as described above, the present invention further includes a magnetic layer in the at least one layer.

In order to form the magnetic layer, a powdery magnetic material may be applied alone, or may be applied in a slurry state in which the magnetic material is dispersed in a binder polymer.

Specific examples of the magnetic material include, for example, at least one selected from the group consisting of ferrite, Ni, Co, W, Fe, and alloys thereof, and are not particularly limited as long as they have magnetic properties.

When the magnetic material is applied in a slurry state, the binder polymer for dispersing the magnetic material may include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, Regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers thereof, etc. It may include, but is not limited to.

When the pouch packaging material has a three-layer structure of thermal bonding layer 10 / metal layer 20 / outer layer 30 = PE / Al / PET as shown in FIG. 1, the magnetic layer 40 is as shown in FIG. The heat seal layer 10 and the metal layer 20 or between the metal layer 20 and the outer layer 30 is configured.

However, in the case of a conventional pouch packaging material, as shown in FIG. 3, the thermal sealing layer 110, the first polymer layer 150a, the metal layer 120, the second polymer layer 150b and the outer layer 130 may be added. It may further comprise a polymer layer (150a, 150b), wherein the magnetic layer according to the present invention as shown in Figure 4 the heat-sealing layer / first polymer layer (140a), the first polymer layer / metal layer (140b), It may be formed between the metal layer / second polymer layer 140c, and the second polymer layer / outer layer 140d.

In addition, each of the added polymer layer may be composed of two or more layers as shown in FIG. 5, wherein the magnetic layer is the following FIG. 6 in addition to the magnetic layers 240a, 240b, 240c and 240d in FIG. 4. As may be configured between the first polymer layer (240e) or between the second polymer layer (240f).

The thickness of the magnetic layer according to the present invention is sufficient to be about the thickness of the polymer layer of one layer, and is not particularly limited.

Examples of the specific configuration of the exterior material, the outer layer / metal layer / heat seal layer = Nylon (Ny) / Al / CPP, PET / Al / CPP, PET / Al / PET / CPP, PET / Ny / Al / CPP, Can be with PET / Ny / Al / Ny / CPP, PET / Ny / Al / Ny / PE, Ny / PE / Al / LLDPE, PET / PE / Al / PET / LDPE or PET / Ny / Al / LDPE / CPP have. In addition, as mentioned above, metal other than aluminum can be used as a metal layer, of course.

The metal layer constituting the pouch sheathing material plays the most important role of protecting the contents by preventing the entry of moisture, oxygen, and light, in addition to improving the strength of the pouch sheathing material, and using stainless steel or nickel-plated iron as a material. However, aluminum (Al) is most preferred in light weight, elongation, cost, and ease of processing.

Nylon (Ny), polyethylene terephthalate (PET), polyethylene (PE) are used for the outer layer in terms of appearance beauty, strength, flexibility, etc., and a plurality of them may be selected and used.

In addition, the heat-sealing layer is a part which is melted by heat or ultrasonic wave to be fused to each other. In addition to polyethylene (PE), unstretched polypropylene (CPP), polyethylene terephthalate (PET), nylon (Ny), low density polyethylene (LDPE), High density polyethylene (HDPE) and linear low density polyethylene (LLDPE) can be used, It is also possible to select and use multiple types from these. In addition, it may be replaced with a material layer selected from the group consisting of other polyolefin resins such as polypropylene chloride, ethylene propylene copolymer, polyethylene and acrylic acid copolymer and copolymer of polypropylene and acrylic acid.

The overall thickness of the pouch packaging material is usually 40 to 120 mu m, the outer layer and the heat seal layer have a thickness of 10 to 40 mu m, and the metal layer has a thickness of 20 mu m. The depth of formation of the groove is preferably set to 100 μm corresponding to the normal thickness of the pouch film when the groove is formed over the entire layer of the pouch film. It is suitable to set it as 10-40 micrometers in consideration of the ease of manufacture. The cross-sectional shape of the groove may be a shape that is easy to form a groove, such as a semi-circle or triangle, the width of the entrance can be equal to the depth of the groove.

Since the battery element is thin and thermal welding is carried out under reduced pressure, there is no problem even if the laminated film is used as it is, but in order to effectively use the internal volume of the battery, it is molded to have a recess in advance so that the battery element is included in the recess. You may.

On the other hand, the present invention provides a method for manufacturing a secondary battery pouch comprising the step of applying a magnetic layer on at least one layer of the secondary battery pouch in which the heat sealing layer / metal layer / outer layer is sequentially laminated.

In order to form a magnetic layer according to the present invention, first, dispersing a magnetic material in at least one layer constituting the pouch, applying a magnet to the dispersed magnetic material to orient the magnetic material, and a pouch having different poles Gluing.

When the N-type magnetic material is used as the magnetic material, the final pouch packaging material produced is an N-type pouch, and when the P-type magnetic material is used, a P-type pouch is manufactured. In this case, in the case of a magnet to be applied, a pole having an electrode opposite to the magnetic material is positioned to face the magnetic material.

That is, in FIG. 7, a manufacturing process of the N-type pouch sheathing material is illustrated. At least one layer 111 constituting the pouch sheathing material is disposed at the lower portion of the pouch sheathing material with a magnet 222 composed of the S pole and the N pole. In the drawing, when the N-type magnetic material 444 is dispersed from the hopper 333 including the magnetic material on the aluminum layer, which is a metal layer, the dispersed N-type magnetic material faces the S-pole and moves in the direction of progress ( Arrow)) and the magnetic material is dispersed while having an orientation to form a magnetic layer. Then, when the additional layers having different poles constituting the pouch sheathing material are bonded to both sides of the pouch using high temperature and high pressure, they are bonded with a stronger force depending on the magnitude of the adhesive force of the magnetic material.

Also in the case of manufacturing the S-type pouch packaging material, the same method as the case of manufacturing the N-type pouch packaging material, except that only the electrode of the magnet located under the pouch packaging material is located so that the N-pole faces the S-type magnetic material. You can proceed to.

The supply of the magnetic material may be provided by using a device such as a hopper, and the magnet for orientation of the magnetic material may be particularly formed as long as it can form a magnet having N and S poles, for example, a permanent magnet. It is not limited.

In addition, the configuration of the magnetic layer may be variously formed according to the structure of the pouch packaging material as shown in FIGS. 2, 4, and 6, and the magnetic layer does not necessarily need to include only one layer, and may be variously selected as necessary.

On the other hand, the present invention provides a secondary battery containing an electrode assembly including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode and an electrolyte in a pouch packaging material including a magnetic layer as described above.

In particular, a lithium secondary battery is preferable among secondary batteries, and specific examples thereof include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

The secondary battery according to the present invention may be a cylindrical battery including a circular jelly-roll in a horizontal cross section, or may be a rectangular battery including a jelly-roll in a square shape in a horizontal cross section. Circular jelly-roll that can be applied to the cylindrical battery is prepared by winding roundly on a horizontal cross section as described above. The rectangular jelly-roll that can be applied to the rectangular battery is, for example, in order of the positive electrode sheet, the first separator, the negative electrode sheet, and the second separator so that the rectangular jelly-roll can be mounted on the rectangular battery case forming an anode by itself. After lamination, it can be produced by compressing in a state in which the negative electrode sheet is roundly wound to the inside of the positive electrode sheet.

That is, the jelly-roll, the end of the positive electrode sheet which is located at the outermost side in the wound state is directly connected to the rectangular battery case as a positive electrode tab, the negative electrode tab is protruded to the uncoated portion of the active material of the negative electrode sheet As a result, a structure for electrical connection with the outside can be achieved.

The secondary battery according to the present invention can be manufactured according to a conventional method known in the art, for example, by assembling the electrode and the separator through the intervening (hole), and then injected into the assembly is prepared by injecting an electrolyte solution . The negative electrode, the positive electrode, and the electrolyte of the present invention are not particularly limited, and conventional ones that may be used in a conventional secondary battery may be used.

1 is a structure of a conventional pouch packaging material consisting of three layers of heat-sealing layer / metal layer / outer layer,

Figure 2 is a structure of a pouch case of an embodiment according to the present invention provided with a magnetic layer in a pouch case having a three-layer structure,

3 is a structure of the pouch packaging material further comprising an additional polymer layer in the pouch packaging material of the three-layer structure as shown in FIG.

Figure 4 is a structure of the pouch packaging material of an embodiment according to the present invention provided with a magnetic layer in the pouch packaging material having a structure as shown in FIG.

5 is a structure of the pouch packaging material having two or more polymer layers further included in the pouch packaging material of FIG.

6 is a structure of a pouch case according to an embodiment of the present invention in which a magnetic layer is additionally provided between polymer layers in a pouch case having a structure as shown in FIG. 5,

7 is a schematic diagram illustrating a manufacturing process of a pouch case including a magnetic layer.

<Description of Drawing>

100, 200, 300, 400, 500, 600: Pouch Exterior

10, 110, 210: heat seal layer

20, 120, 220: metal layer

30, 130, 230: outer layer

40, 140a, 140b, 140c, 140d, 240a, 240b, 240c, 240d, 240e, 240f: magnetic layer

150a, 150b, 250a, 250b, 250c, 250d: polymer layer

111: metal layer

222: Magnet

333 hopper

444: magnetic material

555: polymer layer coating

Claims (15)

A secondary battery pouch in which a heat seal layer, a metal layer, and an outer layer are sequentially stacked, the secondary battery pouch further comprising a magnetic layer. The pouch for a secondary battery of claim 1, wherein the magnetic layer is made of at least one magnetic material selected from the group consisting of ferrite, Ni, Co, W, Fe, and alloys thereof. The pouch for the secondary battery of claim 1, wherein the magnetic layer comprises a slurry in which at least one magnetic material selected from the group consisting of ferrite, Ni, Co, W, Fe, and alloys thereof is dispersed in a polymer binder. The method of claim 3, wherein the polymer binder is polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrroli At least one selected from the group consisting of don, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, and various copolymers thereof Secondary battery pouch characterized in that. According to claim 1, wherein the magnetic layer is a secondary battery pouch, characterized in that configured between the heat sealing layer and the metal layer or the metal layer and the outer layer. The pouch for secondary batteries according to claim 1, wherein the pouch is composed of a heat seal layer, a first polymer layer, a metal layer, a second polymer layer, and an outer layer. The pouch for secondary battery according to claim 6, wherein the first polymer layer and the second polymer layer are one or more layers. 7. The secondary layer of claim 6, wherein the magnetic layer in the pouch is formed between a heat seal layer / first polymer layer, a first polymer layer / metal layer, a metal layer / second polymer layer, and a second polymer layer / outer layer. Battery pouch. The pouch for the secondary battery according to claim 7, wherein the magnetic layer in the pouch is configured between at least one first polymer layer and a second polymer layer. A method of manufacturing a secondary battery pouch, comprising applying a magnetic layer to at least one layer of a secondary battery pouch in which a heat seal layer, a metal layer, and an outer layer are sequentially stacked. The secondary layer of claim 10, wherein the magnetic layer in the pouch is formed between a heat-sealing layer / first polymer layer, a first polymer layer / metal layer, a metal layer / second polymer layer, and a second polymer layer / outer layer. Method for producing a battery pouch. The method of claim 10, wherein the first polymer layer and the second polymer layer are one or more layers. 13. The method of claim 12, wherein the magnetic layer in the pouch is configured between one or more first polymer layers and between second polymer layers. A secondary battery comprising the pouch according to any one of claims 1 to 9. The secondary battery of claim 15, wherein the battery is a lithium secondary battery.

Images