KR20140061146A - Pouch type secondary battery and method for manufacturing the same - Google Patents

Abstract

Disclosed are a pouch type secondary battery, capable of effectively preventing moisture penetration, and a method for manufacturing the same. A pouch type secondary battery according to the present invention includes an electrode assembly where a separator is arranged between an anode and a cathode; a pouch case which receives the electrode assembly and electrolyte and consists of an upper pouch and an lower pouch; and a moisture adsorption member which includes a moisture adsorption material and is interposed between the upper pouch and the sealing part of the lower pouch.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pouch type secondary battery,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a technique for manufacturing a secondary battery, and more particularly, to a pouch-type secondary battery in which moisture penetration can be effectively blocked and a method for manufacturing the same.

2. Description of the Related Art In recent years, demand for portable electronic products such as notebook computers, video cameras, and portable telephones has been rapidly increased, and electric vehicles, storage batteries for energy storage, robots, and satellites have been developed in earnest. Are being studied actively.

The secondary rechargeable batteries are nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries have almost no memory effect compared to nickel- It is very popular because of its low self-discharge rate and high energy density. Generally, such a secondary battery can be classified into a can-type secondary battery and a pouch-type secondary battery depending on the external appearance and application form.

FIG. 1 is an exploded perspective view showing a configuration of a conventional pouch type secondary battery, and FIG. 2 is a combined view of the pouch type secondary battery of FIG. 1, the pouch type secondary battery includes an electrode assembly 20 including a positive electrode tab 21 and a negative electrode tab 22, and a pouch outer case 10 for accommodating the electrode assembly 20 It is common.

Referring to FIGS. 1 and 2, the pouch exterior member 10 may be composed of an upper pouch 11 and a lower pouch 12, and an inner space formed by the upper pouch 11 and the lower pouch 12 The electrode assembly 20 and the electrolytic solution are accommodated. The upper pouch 11 and the lower pouch 12 are formed with sealing portions on the outer circumferential surface to seal the inner space, and these sealing portions are bonded (sealed) to each other.

The pouch outer cover 10 is provided with an aluminum foil to protect the electrode assembly 20 and internal components such as an electrolyte and to improve the electrochemical properties of the electrode assembly 20 and the electrolyte, . The aluminum thin film is interposed between the insulating layers formed of the insulating material so as to secure electrical insulation between the components inside the secondary battery such as the electrode assembly 20 and the electrolyte, and other components outside the secondary battery.

3 is a cross-sectional view taken along the line A-A 'of FIG. 2, and FIG. 4 is a partially enlarged view of a portion B of FIG.

3 and 4, the upper pouch 11 and the lower pouch 12 are composed of outer insulating layers 11a and 12a, aluminum layers 11b and 12b, and inner insulating layers 11c and 12c, respectively . The sealing portion of the upper pouch 11 and the sealing portion of the lower pouch 12 are bonded to each other by thermal fusion or the like so as to seal the inner space of the upper pouch 11 and the lower pouch 12. [ The inner insulating layer 11c of the upper pouch and the inner insulating layer 12c of the lower pouch 11 are made of polypropylene (PP) and polypropylene It is generally formed of a material having good adhesiveness by heat fusion.

However, even if the upper pouch 11 and the lower pouch 12 are bonded to each other at the sealing portion, it is difficult to completely ensure the hermeticity of the secondary battery. Particularly, the adhesive polymer such as polypropylene tends to be vulnerable to moisture penetration. In the case of the conventional pouch type secondary battery, moisture can permeate between the inner insulating layer 11c of the upper pouch and the inner insulating layer 12c of the lower pouch. There is a problem.

If moisture permeates into the interior of the secondary battery, the secondary battery is damaged and the safety of the secondary battery can be deteriorated. Furthermore, the lithium ion secondary battery uses an electrolyte solution in which an electrolyte and an additive are dissolved in a non-aqueous solvent such as carbonic ester. The electrolyte is a fluoride-based electrolyte having good properties in terms of conductivity, potential window, Electrolytes are often used. However, these fluorides have a property of liberating hydrogen fluoride by hydrolysis, and hydrogen fluoride generated may cause dissolution of the electrode material and corrosion of the current collector, which may deteriorate battery performance. In addition, moisture may cause side reactions to accelerate the deterioration of the battery, thereby reducing its service life and generating gas to cause explosion or the like.

Furthermore, in recent years, a large number of secondary batteries are electrically connected to constitute a middle- or large-sized battery pack. In such a case, a drop in the performance of some secondary cells may cause a decrease in the performance of the entire middle- or large-sized battery pack.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a pouch type secondary battery and a battery pack including the pouch type secondary battery which can effectively prevent moisture from penetrating into the sealing part adhesion interfaces of the pouch case, And a method for producing the same.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

According to an aspect of the present invention, there is provided a pouch type secondary battery including: an electrode assembly having a positive electrode plate and a negative electrode plate sandwiched by a separator; A pouch exterior member containing the electrode assembly and the electrolytic solution and formed of an upper pouch and a lower pouch; And a moisture adsorbing member interposed between the upper pouch and the sealing portion of the lower pouch.

Preferably, the water adsorption member is formed in a form in which the moisture adsorbing material is dispersed in the polymer material.

Also preferably, the moisture adsorbing material comprises at least one of calcium chloride, alumina and zeolite.

Preferably, the moisture adsorbing member has a hollow square shape so as to be positioned only between the upper pouch and the sealing portion of the lower pouch.

Preferably, the moisture adsorbing member has a smaller width than the sealing portion of the upper pouch and the lower pouch.

According to an aspect of the present invention, there is provided a battery pack including the pouch type secondary battery.

According to another aspect of the present invention, there is provided a method of manufacturing a pouch type secondary battery, the method comprising: preparing a pouch case and an electrode assembly including an upper pouch and a lower pouch; Preparing a moisture adsorbing member comprising a water absorbing material; Storing the electrode assembly in the pouch exterior material; Positioning the moisture adsorption member between the upper pouch and the sealing portion of the lower pouch; And heat sealing the sealing portion of the upper pouch and the lower pouch.

Preferably, the step of preparing the moisture adsorbing member disperses the moisture adsorbing material into the polymer material to form the moisture adsorbing member.

Also preferably, the moisture adsorbing material comprises at least one of calcium chloride, alumina and zeolite.

Also preferably, the step of preparing the moisture adsorbing member prepares the moisture adsorbing member in a hollow square shape.

Preferably, the moisture adsorbing member preparing step includes preparing the moisture adsorbing member to have a smaller width than the sealing portions of the upper pouch and the lower pouch.

According to the present invention, there is provided a pouch-type secondary battery capable of effectively preventing moisture from permeating from the outside to the inside. Particularly, according to the present invention, it is possible to effectively prevent moisture from penetrating into the sealing interface between the sealing portions of the upper pouch and the lower pouch.

Therefore, according to the present invention, it is possible to prevent degradation of performance and deterioration of the secondary battery due to moisture infiltration, and to improve the safety of the secondary battery.

In addition, according to the present invention, an additional member is interposed between the upper pouch and the sealing portion of the lower pouch, thereby preventing the upper pouch or the lower pouch from being exposed during the sealing.

Therefore, according to the present invention, it is possible to prevent the insulation breakdown of the secondary battery due to the exposure of the aluminum layer.

Further, the present invention can be easily applied to a conventional pouch-type secondary battery manufacturing facility, so that the facility investment cost may not be large.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention, And should not be construed as limiting.
1 is an exploded perspective view showing a configuration of a conventional pouch-type secondary battery.
Fig. 2 is a combined view of the pouch type secondary battery of Fig. 1. Fig.
3 is a cross-sectional view taken along the line AA 'in Fig.
4 is a partially enlarged view of a portion B in Fig.
5 is an exploded perspective view showing a configuration of a pouch type secondary battery according to a preferred embodiment of the present invention.
6 is a combined view of the pouch type secondary battery of Fig.
7 is an enlarged cross-sectional view of a portion C in Fig.
8 is an exploded perspective view schematically showing a configuration of a pouch type secondary battery according to another embodiment of the present invention.
9 is an exploded perspective view schematically showing a configuration of a pouch type secondary battery according to another embodiment of the present invention.
10 is a flowchart schematically showing a method for manufacturing a pouch type secondary battery according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

FIG. 5 is an exploded perspective view illustrating the configuration of a pouch type secondary battery according to an embodiment of the present invention, and FIG. 6 is a combined view of the pouch type secondary battery of FIG. 7 is an enlarged cross-sectional view of part C of Fig.

5 to 7, the pouch type secondary battery according to the present invention includes an electrode assembly 200, a pouch case 100, and a moisture adsorption member 300.

The electrode assembly 200 is configured in such a manner that a positive electrode plate and a negative electrode plate are disposed with a separator interposed therebetween. At this time, the electrode assembly 200 may have a structure in which one positive electrode plate and one negative electrode plate are wound with a separator interposed therebetween, or a structure in which a plurality of positive electrode plates and a plurality of negative electrode plates are stacked with a separator interposed therebetween. The positive electrode plate and the negative electrode plate may each be formed as a structure in which an active material slurry is applied to an electrode current collector. The slurry is usually formed by stirring a granular active material, an auxiliary conductor, a binder, a plasticizer, .

Meanwhile, the electrode assembly 200 may have an unoccupied portion where no slurry is applied to the electrode plate, and the uncoated portion may include an electrode tab corresponding to each electrode plate. That is, the positive electrode tab 210 is attached to the positive electrode plate of the electrode assembly 200, and the negative electrode tab 220 is attached to the negative electrode plate of the electrode assembly 200. 2, the positive electrode tab 210 and the negative electrode tab 220 protrude to the outside of the pouch case 100 to form a positive electrode terminal and a negative electrode terminal. However, the positive electrode tab 210 and the negative electrode tab 220 are not directly exposed to the outside of the pouch case 100 but are connected to other components such as the positive electrode lead and the negative electrode lead, And may be exposed to the outside of the casing material 100.

The pouch exterior material 100 includes an upper pouch 110 and a lower pouch 120. The upper pouch 110 and the lower pouch 120 have concave inner spaces formed therein to accommodate the electrode assembly 200 and the electrolyte.

In the pouch exterior member 100, the sealing portions S are adhered to each other to maintain the sealed state. That is, the upper pouch 110 and the lower pouch 120 each have a sealing portion S at its rims, and the electrode assembly 200 and the electrolytic solution are accommodated in a storage space formed inside the rim, Are sealed (sealed) with each other. At this time, the seal part S of the upper pouch 110 and the lower pouch 120 may be adhered to each other by heat fusion.

The upper pouch 110 and the lower pouch 120 may include external insulating layers 111 and 121, aluminum layers 112 and 122, and internal insulating layers 113 and 123, respectively. The outer insulating layers 111 and 121 may be formed of an insulating material such as polyethylene terephthalate (PET) resin or nylon resin in order to ensure insulation between the secondary battery and the outside. The inner insulating layers 113 and 123 may be made of a material such as polypropylene (PP) in order to improve adhesion when the upper pouch 110 and the lower pouch 120 are sealed.

The moisture adsorbing member 300 is a member including a water adsorbing material and is interposed between the upper pouch 110 and the sealing portion S of the lower pouch 120.

Here, at least one of calcium chloride, alumina, and zeolite may be included in the water adsorbing material. However, the present invention is not limited to the specific kind of the moisture adsorbing material, and may be employed as the moisture adsorbing material of the present invention if it has a function capable of adsorbing moisture.

Preferably, the moisture adsorbing member 300 may be formed in the form of a dispersion of the moisture adsorbing material in the polymer material. For example, the water adsorption member 300 may be formed by dispersing a moisture adsorbing material powder in a polymer material.

More preferably, the polymer material contained in the moisture adsorbing member 300 may be a polyolefin material. Particularly, the moisture adsorption member 300 may be formed by dispersing moisture adsorbing material powder in polypropylene (PP) such as unstretched polypropylene (CPP). When the polymer material of the moisture adsorption member 300 is formed of polypropylene or the like, the inner insulating layer of the pouch case 100 is often formed of polypropylene in order to secure adhesiveness. Since adhesion with the inner insulating layer can be performed well, the sealing ability of the moisture adsorbing member 300 can be prevented from being reduced.

The water absorbing member 300 is located only in the sealing portion S of the upper pouch 110 and the lower pouch 120 and is located in the storage space of other portions such as the upper pouch 110 and the lower pouch 120 The upper pouch 110 and the lower pouch 120 may have a shape corresponding to the sealing portion S of the upper pouch 110 and the lower pouch 120, respectively. For this, the moisture adsorbing member 300 may have a rectangular film shape having only a rim and hollow inside as shown in Fig. According to this embodiment, it is possible to prevent the water absorption member 300 from interfering with the reception of the electrode assembly 200 or the electrolyte. Since the moisture adsorption member 300 is formed in accordance with the shape of the sealing portion S, it is preferable that the moisture adsorption member 300 is interposed between the sealing portions S of the upper pouch 110 and the lower pouch 120 It can be very easy. Therefore, the complication of the manufacture of the secondary battery due to the inclusion of the moisture adsorption member 300 can be reduced.

However, the water absorbing member 300 of the present invention is not necessarily limited to a hollow square, and the water absorbing member 300 may have various shapes.

8 is an exploded perspective view schematically showing a configuration of a pouch type secondary battery according to another embodiment of the present invention. 8, the moisture adsorbing member 300 is displayed on the sealing portion S of the lower pouch 120 for convenience of explanation.

Referring to Fig. 8, the water adsorption member 300 is composed of four unit adsorption members, and each unit adsorption member is formed in a long bar shape in one direction. Each of the unit adsorbing members is positioned one by one on each side of the four sides of the sealing portion S of the pouch outer casing 100. According to this embodiment, the handling of the moisture adsorbing member 300 can be made easier, and it is possible to cut the web into a desired length after the water adsorbing member 300 is first made long.

However, in addition to these embodiments, the moisture adsorbing member 300 may be configured in various forms.

The water absorbent member 300 may have a smaller width than the sealing portion S of the upper pouch 110 and the lower pouch 120.

7, when the width of the moisture adsorbing member 300 is W1 and the width of the sealing portion S of the pouch exterior member 100 is W2, moisture adsorption is performed so that W1 is smaller than W2 It is preferable to configure the member 300. According to this embodiment, it is possible to prevent the moisture adsorbing member 300 from being exposed to the outside of the secondary battery and unnecessarily absorbing moisture in the air. In addition, it is possible to reduce the adhesion between the inner insulating layer of the upper pouch 110 and the inner insulating layer of the lower pouch 120 due to the moisture adsorption member 300.

5 to 8 illustrate that the electrode assembly 200 and the electrolyte storage space are formed in both the upper pouch 110 and the lower pouch 120. However, It is not.

9 is an exploded perspective view schematically showing a configuration of a pouch type secondary battery according to another embodiment of the present invention.

9, the pouch case 100 is formed of an upper pouch 110 and a lower pouch 120, and the storage space of the electrode assembly 200 is formed only in the lower pouch 120, and the upper pouch 110, Such a storage space may not be formed. The upper pouch 110 may be formed as a cover covering the storage space of the lower pouch 120 and the upper pouch 110 and the lower pouch 120 may be connected to each other.

In this case, the water adsorption member 300 may be located at the sealing portion S of the lower pouch 120 and may be interposed in the sealing portion of the lower pouch 120 and the adhesive portion of the upper pouch 110 , The water flowing through the bonding interface of the sealing portion (S) is blocked, thereby preventing moisture from penetrating into the secondary battery.

The battery pack according to the present invention includes the above-described pouch-type secondary battery. That is, the battery pack according to the present invention includes one or more pouch-type secondary batteries in which the water adsorption member 300 is interposed between the upper pouch 110 and the sealing portion S of the lower pouch 120.

In addition to the secondary battery, the battery pack according to the present invention may further include various protection devices for controlling charge and discharge of the secondary battery such as a BMS (Battery Management System).

10 is a flowchart schematically showing a method for manufacturing a pouch type secondary battery according to an embodiment of the present invention.

10, in order to manufacture a pouch type secondary battery according to the present invention, first, a pouch outer casing 100 including an upper pouch 110 and a lower pouch 120, and a positive electrode plate and a negative electrode plate are disposed with a separator interposed therebetween The electrode assembly 200 is prepared (S110), and the moisture adsorbing member 300 including the moisture adsorbing material is prepared (S120).

At this time, in step S120, it is preferable that the moisture adsorbing material is dispersed in the polymer material to form the moisture adsorbing material 300. [ Preferably, in step S120, the polymer material may include a polyolefin material. More preferably, the polymer material in step S120 includes polypropylene.

In addition, in the step S120, it is preferable that the moisture adsorbing material includes at least one of calcium chloride, alumina and zeolite.

Preferably, the moisture adsorption member 300 prepared in the step S120 has a rectangular plate shape having only a rim and hollow inside, corresponding to the shape of the sealing portion S of the pouch exterior member 100. [

Preferably, the moisture adsorbing member 300 prepared in the step S120 has a smaller width than the sealing portion S of the pouch exterior member 100. [ That is, the width of the moisture adsorption member 300 prepared in step S120 may be smaller than the width of the sealing portion S of the upper pouch 110 or the width of the sealing portion S of the lower pouch 120.

The electrode assembly 200 is then housed in the pouch case 100 in step S130 and the pouch case 100 and the electrode assembly 200 are assembled in the pouch case 100 The water adsorption member 300 is positioned between the sealing portion S of the upper pouch 110 and the sealing portion S of the lower pouch 120 in operation S140.

Then, the sealing portion S of the upper pouch 110 and the sealing portion S of the lower pouch 120 are thermally fused (S150).

In the embodiment of FIG. 10, steps S110 to S150 are shown to be performed in sequence, but the present invention is not necessarily limited to this order. For example, steps S110 and S120 may be performed simultaneously, or step S120 may be performed before step S110. Also, steps S130 and S140 may be performed simultaneously, or step S140 may be performed before step S130.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood that various modifications and changes may be made without departing from the scope of the appended claims.

100: Pouch Exterior Material
110: upper pouch
120: Lower pouch
200: electrode assembly
210: positive electrode tab
220: cathode tab
300: water absorption member
S: sealing part

Claims (15)

An electrode assembly in which a positive electrode plate and a negative electrode plate are disposed with a separator interposed therebetween;
A pouch exterior member containing the electrode assembly and the electrolytic solution and formed of an upper pouch and a lower pouch; And
A moisture adsorbing material interposed between the upper pouch and the sealing part of the lower pouch,
Wherein the pouch type secondary battery comprises a pouch type secondary battery. The method according to claim 1,
Wherein the moisture adsorbing member is formed in a shape in which the moisture adsorbing material is dispersed in a polymer material. 3. The method of claim 2,
Wherein the polymer material is a polyolefin material. The method of claim 3,
Wherein the polyolefin material comprises polypropylene. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 1,
Wherein the moisture adsorbing material comprises at least one of calcium chloride, alumina, and zeolite. The method according to claim 1,
Wherein the moisture adsorbing member has a rectangular hollow shape so as to be positioned only between the upper pouch and the sealing portion of the lower pouch. The method according to claim 1,
Wherein the moisture adsorbing member has a smaller width than a sealing portion of the upper pouch and the lower pouch. A battery pack comprising the pouch type secondary battery according to any one of claims 1 to 7. Preparing a pouch exterior member and an electrode assembly composed of an upper pouch and a lower pouch;
Preparing a moisture adsorbing member comprising a water absorbing material;
Storing the electrode assembly in the pouch exterior material;
Positioning the moisture adsorption member between the upper pouch and the sealing portion of the lower pouch; And
Thermally fusing the sealing portion of the upper pouch and the lower pouch
The method of claim 1, 10. The method of claim 9,
Wherein the step of preparing the moisture adsorbing member comprises dispersing the moisture absorbing material in the polymer material to form the moisture adsorbing member. 11. The method of claim 10,
Wherein the polymer material is a polyolefin material. 12. The method of claim 11,
Wherein the polyolefin material comprises polypropylene. ≪ RTI ID = 0.0 > 11. < / RTI > 10. The method of claim 9,
Wherein the moisture adsorbing material comprises at least one of calcium chloride, alumina, and zeolite. 10. The method of claim 9,
Wherein the step of preparing the moisture adsorbing member comprises preparing the moisture adsorbing member in a hollow square shape. 10. The method of claim 9,
Wherein the moisture adsorbing member preparing step comprises preparing the moisture adsorbing member to have a smaller width than a sealing part of the upper pouch and the lower pouch.

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