KR101384901B1 - Pouch type Battery - Google Patents

Abstract

The pouch type secondary battery of the present invention comprises an electrode assembly and a pouch-type case in which a first electrode, a second electrode, and a separator interposed between the electrodes are stacked or wound in a stack, and the pouch-type case is an electrode assembly. Forming at least a portion for accommodating and having a first pouch portion having a first metal layer and a second pouch portion forming at least a portion exposed to the outside and having a second metal layer. In this case, the first metal layer of the first pouch part and the second metal layer of the second pouch part may be connected through a portion joined through hot rolling.

According to the present invention, at least a part of the exterior of the pouch may be formed to have a mechanically strong metal layer, so that a part of the exterior of the pouch may be mounted on an electrical and electronic device without forming a hard case. Make sure

Pouch, exterior material, metal layer, case

Description

Pouch type Battery

The present invention relates to a battery, and more particularly, to a pouch-type battery using a pouch as an outer case.

The lithium secondary battery uses a non-aqueous electrolyte because of its reactivity with lithium. This electrolyte may be a solid polymer containing lithium salts, or may be a liquid phase in which lithium salts dissociate in an organic solvent. When the lithium secondary battery is classified according to the electrolyte type, the lithium secondary battery may be classified into a lithium metal battery using a liquid electrolyte, a lithium ion battery, and a lithium ion polymer battery using a polymer electrolyte.

In the case of a completely solid lithium ion polymer battery, there is no problem of leakage of the organic electrolyte, and in the case of a gel type lithium ion polymer battery containing the organic electrolyte, a problem of leakage of the organic electrolyte may occur. However, in the case of a lithium ion polymer battery, the leakage problem of the electrolyte can be prevented in a simpler form as compared with a lithium ion battery using a liquid electrolyte. For example, a lithium ion polymer battery may use a multilayer film pouch consisting of a metal foil and one or more polymer films covering the top and bottom surfaces of the foil in place of the metal can of the lithium ion battery.

When the pouch is used, the weight of the battery can be reduced, the thickness can be made thinner, and the shape can be changed relatively freely than when the metal can is used.

1 is a perspective view showing a state before a pouch is sealed in an example of a conventional pouch type lithium secondary battery.

The conventional pouch type lithium secondary battery includes an electrode assembly 30 and a pouch 20 accommodating the electrode assembly.

Looking at the general formation method of the pouch-type lithium secondary battery with reference to FIG. 1, first, the front side 21 and the rear side 22 of the pouch 20 are formed by folding the middle of the approximately rectangular rectangular pouch film. The rear surface 22 is formed with a groove 223 in which the electrode assembly can be accommodated, for example, by pressing. If the groove is formed, the electrode assembly 30 may be easily installed in a subsequent process, thereby facilitating the process, and since the peripheral sealing portion of the pouch 20 may be arranged around the groove 223, the pouch may be compactly formed. have.

The ordinary electrode assembly 30 is wound into a multi-layer film laminated in the order of the anode 31, the separator 33, and the cathode 35 in a spiral shape to form a jelly roll. When winding up the jelly roll, a separator is added to an electrode surface or an inner electrode surface that is exposed to the outside of the roll to prevent a short circuit between the anode 31 and the cathode 35. The formed jelly roll is placed in the rear groove 223 of the pouch and heat-pressurized in a state in which the front face 21 and the rear face 22 of the pouch 20 are in close contact with each other in the flange-shaped edge portion 225 to perform pouch sealing. Form a cell battery.

In order to electrically connect the positive electrode 31 and the negative electrode 35 of the electrode assembly 30 to the outside of the pouch, electrode tabs 37 and 38 or electrode leads are formed on one side of the positive electrode 31 and the negative electrode 35. . These electrode tabs 37 and 38 are formed to protrude from the jelly roll in the direction perpendicular to the direction in which the jelly roll is wound, and are drawn out through the sealed side of the pouch.

In the pouch sealing process, a specific component is included on the surface of the polymer film in order to enhance adhesion between the polymer film on the inner surface of the pouch and the metal forming the electrode tabs 37 and 38, or the electrode tabs 37 and 38 before sealing the pouch cover material You may further include the insulating tape 39 for preventing the short circuit between 20.

A core cell is formed by attaching an accessory or structure, such as a protective circuit module (PCM) or a positive temperature coefficient (PTC), to a bare cell formed by pouch sealing.

Then, the core cell is integrated into the hard case to form a completed hard pack battery. Recently, in order to save space or simplify the process, a shape of a completed battery shape is being developed by closing both ends of a pouch battery in which a circuit board and other protection devices are attached with a hot melt resin without a hard case.

However, even in the field of pouch batteries, it is often required to have a constant mechanical strength in order to reduce the thickness of the pouch packaging material and to prevent damage caused by external force, according to the tendency of miniaturization and high capacity of the battery. In order to satisfy these two conflicting requirements at the same time, there is a case where the battery casing is formed so that a portion of the pouch is extended so that the expanded portion surrounds another portion accommodating the electrode assembly.

Typically, the pouch uses a metal foil such as aluminum as a barrier layer to prevent external moisture and internal ingress of air components. Aluminum is light, ductile and malleable, making it easy to thin into foil.

However, aluminum has a low mechanical strength and hardness, so that when the pouch itself or the pouch extension part is used as an exterior, there is a high risk that the battery will be broken by being scratched or pressed, and the battery will be unusable. However, thickening the aluminum foil in order to prevent damage caused by external force hinders the small capacity of the battery and increases the material cost.

On the other hand, forming the pouch with a steel material has a problem that it is not good to process the portion in which the electrode assembly is to be accommodated in the pouch, such as deep drawing.

An object of the present invention is to provide a pouch type secondary battery having a packaging material that is resistant to damage from the outside while maintaining the pouch part workability in accommodating the electrode assembly in a good state.

It is another object of the present invention to provide a pouch type secondary battery having a packaging material resistant to damage from the outside while maintaining a thin thickness as a whole.

The pouch type secondary battery of the present invention for achieving the above object is made of a first electrode, a second electrode, a separator interposed between these electrodes are laminated or laminated with an electrode assembly and pouch-type case is laminated, The pouch-shaped case may include at least a portion for accommodating the electrode assembly and a first pouch portion having a first metal layer and a second pouch portion forming at least a portion exposed to the outside and having a second metal layer.

In the present invention, the first metal layer of the first pouch part and the second metal layer of the second pouch part may be connected through a portion joined through hot rolling.

In addition, the inner or outer polymer layer laminated on the first metal layer and the second metal layer formed by the first pouch part and the second pouch part may be seamlessly integrated, unlike the metal layer in which the two parts are connected.

In the present invention, the first pouch portion may be a portion that forms a groove for receiving the electrode assembly through processing, and the second pouch portion extends from a cover portion or a cover portion covering the groove and surrounds at least a portion of an outer surface of the first pouch portion. Can be.

In the present invention, the first metal layer may be an aluminum layer, and the second metal layer may be stainless steel or other steel material.

According to the present invention, unlike a conventional pouch, at least a part of the pouch for accommodating the electrode assembly may be formed to have a mechanically strong metal layer, so that a part of the exterior of the pouch is part of the exterior of the battery pack without a separate hard case. To be mounted on the electrical and electronic equipment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

2 to 5 are side cross-sectional views showing a method of forming a pouch used in an embodiment of the present invention.

 Referring to FIG. 2, first, an entire metal layer 130 including two metal layers partially overlapped with a pouch material, for example, an aluminum layer 120 and a stainless steel layer 110 passes through a hot rolling roller 210 while proceeding in a longitudinal direction. do. The overlapped portions of the two metal layers are partially fused under the pressure and heat transmitted from the roller 210, and are combined so that they do not easily fall physically.

3 to 5, resin layer laminating is performed on the upper and lower surfaces of the metal layer 130 which are joined after the bonding of the two metal layers. In order to form the pouch exterior resin layer 150, a material such as nylon or polyethylene terephthalate (PET) may be used on the upper surface of the metal layer 130 and has a high tensile force and is not easily perforated. In order to form the inner resin layer 140 of the pouch to be fused to face each other, the lower surface of the metal layer 130 may be easily fused, and low density polyethylene and polypropylene having excellent insulation and elongation may be used. An adhesive layer may be interposed between the metal layer and the resin layer, and each resin layer may also be a composite layer made of various kinds of resins. The pouch fabric 160 thus formed is cut into a suitable size to form a pouch battery. Each pouch member 170 formed by cutting the pouch fabric 160 has a portion formed of aluminum, a portion formed of stainless steel, and a narrow coupling portion 178 where they overlap.

A portion formed of aluminum of each pouch member is called a lower portion 174, and a groove 176 is formed in the lower portion 174 to receive the electrode assembly through a deep drawing process. The groove is usually in the form of a cuboid and consists of an open space at the top. At this time, since the groove forming portion is made of aluminum having high malleability, ductility, and excellent workability, the metal layer is less likely to rupture at the edge of the groove. In this case, the coupling part 178 overlapping the aluminum layer and the stainless steel layer may form a flange part around the groove 176.

In the pouch member 170 in which the groove 176 is formed, the stainless steel portion is referred to as the upper portion 172 so that the pouch member 170 is folded so that the upper portion 172 covers the open portion of the groove 176 formed in the lower portion 174. All. The folded portion that may be formed in the coupling portion 178 may be formed before or with the groove formation. At this time, the electrode assembly not shown is accommodated in the groove.

In the above embodiment, the area of the pouch member 170 forming the secondary battery is substantially the same area as the lower portion 174 of which the metal layer is made of aluminum and the groove is formed, and the upper portion 172 of which the metal layer is made of stainless steel and covering the groove 176. Was formed. However, as shown in FIG. 6, the width of the upper portion 172 ′ forming the cover of the groove is longer than the width of the lower portion 174 ′ so that the portion remaining after sealing the pouch by covering the groove of the lower portion 174 ′ Sealed pouches can be wound to complement the lower aluminum layer, which is relatively weak in mechanical strength. When the upper portion 172 'is wide enough to cover the entire portion of the lower aluminum layer with only the upper portion 172', the pouch is covered with a stainless steel layer. Therefore, the battery can be efficiently protected from damage from the outside without a separate resin hard pack forming packaging material.

In FIG. 7, a lower portion 184, which is an aluminum metal layer portion, is formed in the pouch member 180, and an upper portion 182, which is a stainless steel layer 110 portion, is formed on both sides of the aluminum layer 120.

The upper portion 182, which is a portion of the stainless steel layer 110, is bent upward from the lower portion 184, which is a portion of the aluminum layer 120, to cover the groove 186 of the lower portion 184, which is the portion of the aluminum layer 120. . The terminal portions of the grooves 186 are attached to each other by the polypropylene layer fusion in a state in which the polypropylene layers face each other with the resin layer 140 that meets each other to form an inner surface of the pouch. In this state, when the front and rear ends of the opened pouch member are sealed by thermocompression, a sealed pouch bare cell containing the electrode assembly is formed.

8 to 11 are perspective views showing in more detail how the pouch member shown in the cross-sectional view of FIG. 7 forms a pouch.

In the illustrated embodiment, the pouch member reverses the viewing direction so that, generally, the lower portion of the aluminum metal layer is shown as the rear portion and the upper portion of the stainless steel layer is represented as the front portion, and the rear portion faces the sidewalls of the groove in which the electrode assembly is placed and the bottom of the groove and around the groove. And a flange portion extending from the pair of first side edges, wherein the front portion covers the electrode assembly located in the groove at the flange side side connected with the other pair of second side edges and the second side edge facing the groove. It has two extensions formed so as to extend. A portion of the ends of the two extensions of the front portion overlap each other and the front portion overlapping the flange portion is also welded to the flange portion at least in part to form a totally sealed pouch.

On the other hand, in the pouch type battery of the present invention, when the two end portions of the back portion are fusion-bonded, it is preferable to apply a constant tensile force to the two ends so that the pulling forces act on each other. In this case, it is easy to form the short side surface with the second side edge corresponding to the outer surface of the corresponding part of the electrode assembly, and the tension force is applied to the pouch case in the pouch bare cell in a direction surrounding the outer periphery of the electrode assembly. Becomes

8 illustrates a state in which the electrode assembly 30 is positioned in the grooved pouch member 40. The groove 43 consists of a pouch wall of the bottom and four sides. The edge where the bottom and the side meet forms a groove 43 through deep drawing to form a smooth curved surface. The groove 43 has a planar rectangle, and flange portions 42 and 44 are formed at the groove which is an aluminum layer portion and at two short sides (first side edge) of the periphery thereof. On both sides of the groove 43 and the flanges 42 and 44 (parts connected to the second side edges), two portions 46 and 48 having stainless steel layers are located. The two extensions 46 and 48 may be formed in the same width. This form may be formed by deep drawing the groove 43 portion of the flat quadrangular pouch packaging material 40.

The first electrode tab 37 and the second electrode tab 38 are drawn out through the upper flange portion 42 of the pouch sheath 40, and may be electrically connected to a protection circuit module (not shown) outside the pouch. .

Where the electrode tab is drawn out, the electrode tab crosses the upper flange portion. At this time, a resin tape (insulating tape) is provided at a portion where the electrode tab is pulled out so as not to short-circuit with each other through the metal foil of the pouch film and to help pouch sealing.

In the state shown in FIG. 8, the extension portions 46 and 48 are grooves 43 along the boundary between the two extensions 46 and 48 and the portion consisting of the grooves 43 and the flanges 42 and 44 of the pouch sheath 40. It is folded to cover the electrode assembly (30) placed in the). 9A in which the upper sealing portion 52 and the front sealing portion 51 are formed by fusion between the two end portions 461 and 481 that meet each other and the upper flange portion 42 where the electrode tabs 37 and 38 are drawn out. And the state shown in Fig. 9B. The two ends of the extension parts 46 and 48 are fused so that the heat-sealable resin layers located inside the pouch film face each other, and the other front ends of the pouch are folded by folding the fused front sealing part 51 as shown in FIG. 9B. Touch the part.

On the other hand, when the two ends 461 and 481 of the extensions 46 and 48 are fused, the two ends are pulled toward the center of the pouch width to perform fusion. In the process of pulling the two ends, the two ends 461 and 481 face the outside of the pouch width. Therefore, the angular shape of the portion where the long side and the extension portions 46 and 48 of the pouch groove are formed while forming the groove in the pouch exterior material is expanded. At the same time, the outer surface of the electrode assembly as the support reference surface is formed on the long side portion of the pouch groove is formed in the same shape as the outer surface of the electrode assembly, the narrow side surface 53 of the pouch bare cell forms the entire curved surface.

Referring to FIG. 10, a second sealing part is also provided on the opposite side of the first sealing part 52, which is an upper sealing part from which the electrode tab is drawn out, and the second sealing part is not thermally fused in the state of FIG. 9A to the internal electrode assembly. It may be a passage for supplying the electrolyte 60. The electrolyte 60 is injected into the pouch through the open second sealing part.

Therefore, the upper or lower surface of the electrode assembly, in which the gap between the electrode plate and the separator is visible, is exposed to face the direction in which the electrolyte is injected. Therefore, electrolyte solution can be easily introduced into the electrode assembly. According to the exemplary embodiment, a part of the first sealing part 52 from which the electrode tab is drawn out is opened, and the opposite second sealing part is sealed so that the electrolyte is injected through the first sealing part 52 of the pouch 50. You may.

Referring to FIG. 11, heat sealing is performed on the flange portion opened in the state of FIG. 10 in which the electrolyte is injected to form the lower sealing portion 57 of the pouch, and the pouch is completely sealed from the outside. The lower sealing portion 57 may be bent to cover the lower surface 55 of the pouch 50.

When using the pouch type bare cell formed as in the above embodiments, the resin assembly including the hot melt resin layer or the circuit board is combined with only the upper and lower parts of the bare cell to form a finished battery pack as it is or wrapped with a thin resin tube. can do. That is, since the pouch itself has a strong resistance to external damage, the configuration of the battery pack can be simplified.

1 is a perspective view showing a state before a pouch is sealed in an example of a conventional pouch type lithium secondary battery.

2 to 5 are schematic side cross-sectional views showing a method of forming a pouch used in an embodiment of the present invention.

Figure 6 is a schematic side cross-sectional view showing the form of the battery packaging pouch of another embodiment according to the present invention.

Fig. 7 is a schematic side cross-sectional view showing a battery exterior pouch member according to still another embodiment of the present invention.

8 to 11 are perspective views showing in more detail how the pouch member shown in the cross-sectional view of FIG. 7 forms a pouch.

Claims (7)

An electrode assembly having a separator between the two electrodes and the two electrodes to prevent shorting of the two electrodes; It is provided with a pouch-type case for receiving the electrode assembly, The pouch-type case has a first pouch portion forming at least a portion of a space for accommodating the electrode assembly and having a first metal layer, and a second pouch portion forming at least a portion exposed to the outside and having a second metal layer. , The first metal layer and the second metal layer are connected through a seam at one side, A subsequent pouch type secondary battery, wherein the inner resin layer or outer resin layer laminated on the first metal layer and the second metal layer is seamless. The method according to claim 1, The first metal layer and the second metal layer is a pouch type secondary battery, characterized in that continued through the portion joined by hot rolling. delete The method according to claim 1, The inner surface resin layer is made of a polypropylene material, the outer surface resin layer is a pouch type secondary battery, characterized in that made of a nylon layer. The method according to claim 1, The first pouch part is formed with a groove for accommodating the electrode assembly through processing, and the second pouch part is a cover part covering the groove or a portion extending from the cover part to surround at least a part of an outer surface of the first pouch part. A pouch type secondary battery characterized by the above-mentioned. The method according to claim 1, The first pouch part is formed with a groove for accommodating the electrode assembly through processing, and the second pouch part extends from the cover part covering the groove or the cover part and covers the entire side of the pouch. Secondary battery. The method according to claim 1, The first metal layer is an aluminum layer, The second metal layer is a pouch type secondary battery, characterized in that the stainless steel layer.

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