KR20080082799A - Manufacturing method of pouch for rechargeable battery and pouch of rechargeable battery - Google Patents

Abstract

A method for preparing a pouch for a secondary battery, and a secondary battery prepared by the method are provided to prevent the breakage of an accommodation part due to over-modification by reducing the tensile strength applied when the groove is formed. A method for preparing a pouch for a secondary battery comprises the steps of forming a discontinuous cutting part(310) at the circumference where the accommodation groove(211) of a pouch raw material(300) is formed; and forming a groove to the pouch raw material. Preferably the discontinuous cutting part is formed by press processing in the shear direction of the accommodation part based on the propagation direction of the pouch raw material.

Description

Manufacturing method of secondary battery pouch and secondary battery pouch {MANUFACTURING METHOD OF POUCH FOR RECHARGEABLE BATTERY AND POUCH OF RECHARGEABLE BATTERY}

1 is an exploded perspective view of a pouch type secondary battery to be manufactured using the pouch manufacturing method of the secondary battery of the present invention.

2 is a flow chart of a method for manufacturing a pouch for a secondary battery according to an embodiment of the present invention.

Figure 3a is a plan view of a state in which the incision is formed in the fabric pouch according to an embodiment of the present invention.

Figure 3b is a plan view of the receiving groove and the gas discharge groove is formed in Figure 3a.

Figure 3c is a perspective view showing a state in which a plurality of accommodation grooves are formed in the pouch fabric.

FIG. 3D is a plan view of the incision opened in FIG. 3B.

4A and 4B are plan views of a state in which a plurality of accommodation grooves, gas discharge grooves, and cutouts are formed in a pouch fabric according to an embodiment of the present invention.

5A is a plan view of a state in which a cutout is formed in a sheath of a pouch fabric in which an accommodation groove and a gas discharge groove are formed according to an embodiment of the present invention.

FIG. 5B is a plan view of a state in which the cutout in FIG. 5A is formed with diagonal cuts. FIG.

5C is a plan view of a state where the cutout in FIG. 5A is formed with staggered diagonal cuts.

6 is a plan view of a state in which the cutout formed in FIG. 5A is formed in a plurality of rows.

<Explanation of symbols for main parts of the drawings>

100; Electrode assembly 110; Positive plate

111; Positive electrode tab 120; Negative plate

121; Negative electrode tab 130; Separator

140; Insulation Tape

200; Pouch 210; Bottom film

211; Receiving groove 212; Gas release groove

220; Top film

300; Pouch fabric 310; Incision

The present invention relates to a secondary battery, and more particularly, to a method for manufacturing a pouch for a secondary battery and a secondary battery pouch to more easily form a receiving groove in which an electrode assembly is accommodated in a pouch fabric.

As the use of portable electric products such as video cameras, portable telephones and portable PCs is activated, the importance of secondary batteries mainly used as driving power thereof is increasing. In particular, lithium secondary batteries have higher energy density per unit weight and can be rapidly charged compared to other lead-acid batteries and other secondary batteries such as nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries. It is actively underway.

Lithium oxide is used as a positive electrode active material used for such a lithium secondary battery, and a carbon material is used as a negative electrode active material. Using such an active material, a positive electrode plate having a positive electrode tab connected to a positive electrode current collector on which a positive electrode active material is formed, a negative electrode plate having a negative electrode tab connected to a negative electrode current collector on which a negative electrode active material is formed, and a separator interposed between the positive electrode plate and the negative electrode plate are laminated, To prepare an electrode assembly, wherein the electrode assembly is used in a cylindrical or rectangular metal can or in a pouch.

In addition, the lithium secondary battery may be classified into a lithium ion battery using a liquid electrolyte and a lithium ion polymer battery using a polymer solid electrolyte according to the type of electrolyte. Lithium ion polymer batteries can be classified into fully solid lithium ion polymer batteries containing no electrolyte solution and lithium ion polymer batteries using gel polymer electrolyte containing electrolyte solution, depending on the type of polymer solid electrolyte.

In the case of a lithium ion battery using a liquid electrolyte, a cylindrical or rectangular metal can is used as a container by welding sealing. Since the can-type secondary battery using the metal can as a container has a fixed shape, there is a disadvantage in restricting the design of an electrical product using the same as a power source, and it is difficult to reduce the volume. Accordingly, a pouch-type lithium polymer battery has been developed and used in which two electrodes, a separator, and an electrolyte are placed in a pouch made of film and sealed.

The pouch of a lithium ion polymer battery that is commonly used has a polyolefin-based resin layer (Polyolepin Layer), which is a heat-adhesive layer that acts as a sealing material with heat adhesiveness as an inner layer, a substrate that maintains mechanical strength as a middle layer, and a barrier between moisture and oxygen. An aluminum layer (AL / Aluminum Layer), which is a metal layer serving as a layer, and a multilayer film structure in which a nylon layer serving as a substrate and a protective layer is laminated as an outer layer.

The method for manufacturing a secondary battery pouch for manufacturing a secondary battery using such a pouch, first to form a receiving groove in the pouch fabric to accommodate the electrode assembly in the receiving groove, and to seal the opening of the receiving groove with a film of another pouch do. Thus, the pouch for accommodating the electrode assembly is divided into a lower layer in which the receiving groove is formed and an upper layer covering the opening of the lower layer.

At this time, in the process of forming an accommodating groove for accommodating the electrode assembly in the pouch, the pouch fabric is subjected to a tensile force while being processed by a press or the like, and the overall state is increased. In particular, the portion forming the edge portion and the side wall portion of the receiving groove is large enough to extend, the tensile force is concentrated to cause excessive deformation.

Therefore, defects such as cracks or pinholes are generated in the sidewalls and the corners of the accommodating grooves, resulting in problems such as battery disposal, performance degradation, and shortened lifespan. In addition, this problem becomes more problematic as the depth of the pouch accommodating groove deepens according to the tendency of increasing the capacity of the battery.

The technical problem of the present invention for solving the above problems is to prevent defects such as cracks or pinholes in the receiving groove when forming the receiving groove in the pouch using the press working.

Method for manufacturing a secondary battery pouch according to the present invention for achieving the above object is an incision forming step of forming a discontinuous incision around the receiving groove of the fabric pouch; And a groove forming step of forming a groove in the pouch fabric.

In addition, the incision forming step may be made by press working.

In addition, the cutout forming step may form the cutout in the shear direction of the receiving groove based on the advancing direction of the pouch fabric.

In addition, the cutout may be further formed at both side ends of the receiving groove in succession to the front end of the receiving groove.

On the other hand, the secondary battery pouch of the present invention in the pouch fabrication of the pouch fabric continuously forming the receiving groove for receiving the electrode assembly, the periphery of the accommodating groove of the pouch fabric to break the receiving groove due to the over deformation of the receiving groove. It is characterized by forming an incision discontinuously to prevent.

In addition, the cutout may be formed of a plurality of sheaths a predetermined distance away from the receiving groove.

In addition, the sheath may form a plurality of rows away from the receiving groove by a predetermined distance.

In addition, the cuts forming one row and the cuts forming another row among the cuts formed by the plurality of rows may be shifted to cover each other.

Referring to FIG. 1, the pouch type secondary battery to be manufactured by the manufacturing method of the present invention may include an electrode assembly 100 and a pouch 200 accommodating the same.

First, the electrode assembly 100 is formed by stacking the positive electrode plate 110 to which the positive electrode tab 111 is connected, the negative electrode plate 120 to which the negative electrode tab 121 is connected, and the separator 130.

The positive electrode plate 110 includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer may be formed of a layered compound containing lithium, a binder to improve bonding strength, and a conductive material to improve conductivity. As the positive electrode current collector, aluminum is generally used, and the positive electrode current collector becomes a passage for the charge generated in the positive electrode active material layer and serves to support the positive electrode active material layer. The positive electrode active material layer is attached to the wide surfaces of the positive electrode current collector, and a positive electrode non-coating portion (not shown) is formed at one end of the positive electrode plate 110, and the positive electrode active material layer is not formed, and the positive electrode tab 111 has a positive electrode tab 111. Is bonded.

The negative electrode plate 120 includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer may be formed of a binder which contains carbon and improves bonding strength between hard carbon, which is commonly used, or graphite and active material particles. As the negative electrode current collector, copper is generally used, and the negative electrode current collector becomes a movement path of charge generated in the negative electrode active material layer and serves to support the negative electrode active material layer. The negative electrode active material layer is formed on a wide surface of the negative electrode plate, wherein a negative electrode non-coating portion (not shown) is formed at one side end of the negative electrode plate 120, in which the negative electrode active material layer is not formed. The negative electrode tab 121 is bonded to the negative electrode non-coating portion.

The separator 130 is interposed between the positive electrode plate 110 and the negative electrode plate 120 to insulate the positive electrode plate 110 and the negative electrode plate 120, and the charges of the positive electrode plate 110 and the negative electrode plate 120 pass therethrough. Generally, the material of the separator 130 is polyethylene (PE) or polypropylene (PP), but the material is not limited thereto. The separator 130 may include an electrolyte and may be formed in a liquid or gel form.

At this time, the material of the positive electrode tab 111 and the negative electrode tab 121 may be formed of an alloy containing aluminum or aluminum, or an alloy containing nickel or nickel, in the present invention, the positive electrode tab 111 and the negative electrode tab 121. ) Is not limited to the material.

The pouch 200 accommodates the electrode assembly 100 and exposes the positive electrode tab 111 and the negative electrode tab 121 to the outside. The pouch 200 may be used in the form of a multilayer film by stacking a plurality of layers. The multilayer film is formed of CPP (Casted Polypropylene), and an inner barrier layer is formed of an aluminum layer, and an outer protective film is nylon. It can be formed in layers. In addition, the pouch 200 may be formed of a lower layer 210 having a receiving groove 211 for accommodating the electrode assembly 100 and an upper layer 220 closing an opening of the lower layer 210. The lower layer 210 and the upper layer 200 may be bonded to each other by applying heat to a heat-adhesive layer that is in contact with each other. In this case, the insulating tape 140 interposed between the lower layer 210 and the upper layer 220 to insulate the positive / negative electrode tabs 111 and 121 may also be adhered to the pouch 200 by heat. However, the present invention does not limit the material and its configuration.

Referring to FIG. 2, the method of manufacturing a pouch according to the present invention for accommodating the electrode assembly may include a cutout forming step S1 and a groove forming step S2.

Referring to FIG. 3A, the cutout forming step S1 forms the cutout 310 discontinuously at the periphery where the receiving groove (not shown) of the pouch fabric 300 is to be formed. The reason for discontinuously forming the cutout 310 is to prevent the pouch fabric from being separated from each other. In addition, a plurality of pouch type secondary batteries are simultaneously manufactured by forming a plurality of accommodation grooves (not shown) in the pouch fabric 300. To this end, the pouch fabric 300 is to allow the other processes to proceed at the same time.

At this time, the incision forming step (S1) may be made by press working. By using the press working, pressing the pouch fabric with a bundle (not shown) having a blade matching the shape of the cutout 310 can form the cutout 310 at a time.

Referring to FIG. 3B, the groove forming step S2 forms the receiving groove 211 at the center of the portion where the cutout 310 is formed. At this time, as shown in Figure 3c the receiving groove 211 may be formed in a plurality of pouch fabric 300, the gas discharge groove 212 smaller than the receiving groove 211 is further around the receiving groove 211 Can be formed. The gas discharge groove 212 may be formed to receive the electrode assembly (not shown) in the receiving groove 211, and then to remove the gas generated during the initial charging from the receiving groove 211. When the grooves are formed, as shown in FIG. 3D, the cutout portion 310 is opened, and the edge portion 213 of the accommodation groove 211 is over-deformed and broken due to the cutout portion 310 being opened. It is prevented beforehand.

In addition, referring to Figure 4a, the cutout 310 may be formed in the front end direction of the receiving groove based on the traveling direction of the pouch fabric (300). First, the pouch fabric 300 is moved in the direction of the arrow as shown. The receiving groove 211 is formed by press working. At this time, if the incision 310 is formed discontinuously in the direction of the shear on the basis of the arrow direction, which is the traveling direction of the pouch fabric 300, the receiving groove 211 is over-deformed and the corner portion of the receiving groove 211 To prevent tearing. Thus, even if the cutout 310 is formed in one side of the receiving groove 211 in one direction, it is possible to prevent the edge portion of the receiving groove from being broken due to over deformation.

Referring to FIG. 4B, the cutout 310 may be further formed at both side ends 313 of the accommodation groove 111 in a row in front of the accommodation groove 211. As shown, discontinuous cutouts 310 are formed in the advancing direction and the shearing direction of the pouch fabric 300, and cutouts 310 are formed on both side ends of the receiving grooves 211 to press the process. The corner portion of the receiving groove 211 is formed can be further prevented from being broken due to over deformation.

Hereinafter, an embodiment according to the secondary battery pouch of the present invention will be described in detail with reference to the accompanying drawings.

First, referring to FIG. 5A, the cutout 310 may be formed of a plurality of sheaths having a dotted line shape away from the receiving groove 2110. In the method of forming the cutout 310, the cutout 310 may be easily formed by cutting a pouch fabric using a sharp blade. In this case, the plurality of sheaths may be formed in a straight line as shown, as shown in Figure 5b, may be formed in an oblique shape. In addition, as shown in FIG. 5C, shapes in which diagonal lines are alternate with each other may be repeatedly formed. Such a plurality of sheaths may be formed by dipping at a time using a press process, or may be formed using a rotating saw blade.

Referring to FIG. 6, the sheath may be formed by forming a plurality of rows away from the receiving groove 211 by a predetermined distance. As shown, since the cutout 310 is spaced apart from the receiving groove by a predetermined distance, the cutout 310 is pushed to the receiving groove 211 due to the process of forming the receiving groove 211 by pressing. In addition, the sheath is formed in a plurality of rows to further prevent the lower layer 210 forming the receiving groove 211 from being separated from the pouch fabric. At this time, the sheath may be formed by forming a plurality of rows of diagonal sheaths, as shown in Figure 5b or 5c.

At this time, the scabbar 311a constituting one row of the plurality of scabbard and the scabbar 311b constituting another row may be shifted to cover each other. When cuts forming different rows are shifted from each other, the lower layer 210 of the pouch is further prevented from being separated from the pouch fabric 300 in the process of forming the receiving groove 211 by pressing.

The present invention is not limited to the technical spirit of the specific embodiments or drawings described above, and those skilled in the art without departing from the gist of the invention claimed in the claims Various modifications are possible, of course, and such changes are within the scope of the claims of the present invention.

According to the present invention, before forming the accommodating groove in which the electrode assembly is accommodated in the pouch fabric, the incision is formed in the periphery of the accommodating groove in advance to reduce the tensile force acting when the accommodating groove is formed. By blocking the occurrence of the battery, there is an effect of preventing the disposal of the battery and performance degradation and shortening the life of the battery or abnormalities.

Claims (8)

An incision forming step of forming a discontinuous incision around the accommodation groove of the pouch fabric; And Secondary battery pouch manufacturing method characterized in that the groove forming step of forming a groove in the pouch fabric. The method of claim 1, The cutout forming step is a secondary battery pouch manufacturing method, characterized in that made by pressing. The method of claim 1, The cutout forming step of the secondary battery pouch manufacturing method, characterized in that for forming the cutout in the shear direction of the receiving groove based on the advancing direction of the pouch fabric. The method of claim 3, wherein The cutout is a secondary battery pouch manufacturing method characterized in that it is further formed in both side ends of the receiving groove in the continuous front of the receiving groove. In the pouch fabric continuously forming a receiving groove for receiving the electrode assembly in the fabric, The pouch for the secondary battery, characterized in that to form a discontinuous portion in the periphery of the accommodating groove of the pouch fabric to prevent the break of the accommodating groove due to the over deformation of the accommodating groove. The method of claim 5, wherein The cutout part of the secondary battery pouch, characterized in that formed in a plurality of sheath away a predetermined distance from the receiving groove. The method of claim 6, The sheath is a secondary battery pouch, characterized in that to form a plurality of rows away from the receiving groove a predetermined distance. The method of claim 7, wherein The pouch for secondary batteries, characterized in that the scabbard forming one row and the scabbard forming another row of the sheath formed by forming a plurality of rows are shifted to cover each other.

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