KR102328646B1 - Pouch case and secondary battery including the same - Google Patents

Abstract

A secondary battery according to an embodiment of the present invention includes an electrode assembly; an electrode lead connected to the electrode assembly; a pouch case accommodating the electrode assembly and sealing the electrode assembly in a state in which the electrode lead is drawn out; and a sealant layer positioned on at least one of an edge of the pouch case and between the pouch case and the electrode lead, wherein the sealant layer includes a polymer-matrix composite.

Description

Pouch case and secondary battery including same {POUCH CASE AND SECONDARY BATTERY INCLUDING THE SAME}

The present invention relates to a pouch case and a secondary battery including the same, and more particularly, to a pouch case having high tensile strength and a pouch-type secondary battery.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. Accordingly, a lot of research has been done on secondary batteries that can meet various needs.

Secondary batteries are attracting a lot of attention as an energy source for power devices such as electric magnetrons, electric vehicles, and hybrid electric vehicles, as well as mobile devices such as cell phones, digital cameras, and notebook computers.

A small battery pack in which a single battery cell is packed is used for small devices such as mobile phones and cameras, but a battery pack in which two or more battery cells are connected in parallel and/or in series is used in mid- to large-sized devices such as notebook computers and electric vehicles. Packed medium or large battery packs are used.

The secondary battery has a high demand for a prismatic secondary battery and a pouch-type secondary battery that can be applied to products such as mobile phones with a thin thickness in terms of shape. In the case of a prismatic lithium secondary battery, it is advantageous to protect the electrode assembly from external impact, and while the injection process is easy, it is difficult to reduce the volume because the shape is fixed. On the other hand, in the case of a pouch-type lithium secondary battery, there are no restrictions on shape and size, so it is suitable for manufacturing thin cells, easy assembly through thermal fusion, and easy to release gas or liquid in case of abnormal behavior. It has a high advantage. However, since a thin soft laminate sheet is used as a container compared to a prismatic secondary battery, the physical and mechanical strength is weak and the reliability of sealing is low, so safety against external shocks may be low.

Embodiments are to provide a pouch case having improved tensile strength and a secondary battery including the same in order to increase the safety of the pouch-type secondary battery.

However, the problems to be solved by the embodiments of the present invention are not limited to the above problems and may be variously expanded within the scope of the technical idea included in the present invention.

A pouch case according to an embodiment of the present invention includes an upper case and a lower case, and one of the edges of the upper case and the lower case includes a substrate layer, a metal layer, and a sealant layer sequentially stacked, and the sealant The layer comprises a polymer-matrix composite.

In the sealant layer, a plurality of fiber or mesh matrixes may be dispersed in the thermoplastic resin layer.

The matrix may include at least one of glass fiber, carbon fiber, and aramid fiber.

The carbon fibers may include graphite nanoplatelets.

The thermoplastic resin layer may include polypropylene, polyester, or an epoxy resin.

A secondary battery according to an embodiment of the present invention includes an electrode assembly; an electrode lead connected to the electrode assembly; a pouch case accommodating the electrode assembly and sealing the electrode assembly in a state in which the electrode lead is drawn out; and a sealant layer positioned on at least one of an edge of the pouch case and between the pouch case and the electrode lead, wherein the sealant layer includes a polymer-matrix composite.

In the sealant layer, a plurality of fiber or mesh matrixes may be dispersed in the thermoplastic resin layer.

The matrix may include at least one of glass fiber, carbon fiber, and aramid fiber.

The carbon fibers may include graphite nanoplatelets.

The thermoplastic resin layer may include polypropylene, polyester, or an epoxy resin.

The sealant layer positioned between the pouch case and the electrode lead includes a first sealant layer and a second sealant layer positioned between an upper case and a lower case constituting the pouch case, and between the pouch case and the electrode lead. The sealant layer positioned on the electrode lead may include a third sealant layer and a fourth sealant layer respectively formed on both surfaces of the electrode lead.

The first sealant layer, the second sealant layer, the third sealant layer, and the fourth sealant layer are positioned between the pouch case and the electrode lead, and the first sealant layer includes the upper case and the third sealant layer. the second sealant layer is positioned between the lower case and the fourth sealant layer, the third sealant layer is positioned between the first sealant layer and the electrode lead, and the fourth sealant layer is positioned between the first sealant layer and the electrode lead. It may be positioned between the electrode lead and the second sealant layer.

The pouch case includes an upper case and a lower case, and the upper case includes a first base layer, a first metal layer, and a first sealant layer sequentially positioned from the outside to the inside of the upper case, and the lower case may include a second base layer, a second metal layer, and a second sealant layer sequentially positioned from the outside to the inside of the lower case.

The first base layer and the second base layer may each include nylon or polyethylene terephthalate.

The secondary battery is between the first base layer and the first metal layer, between the first metal layer and the first sealant layer, between the second base layer and the second metal layer, and between the second metal layer and the second sealant layer. It may further include adhesive layers respectively positioned therebetween.

The first sealant layer and the second sealant layer may contact each other at an edge of the pouch case.

The pouch case may include an upper case and a lower case, and one sealant layer may be positioned between the upper case and the electrode lead and between the lower case and the electrode lead, respectively.

According to embodiments, by using a polymer composite material as a sealing material for at least one of the pouch case and the electrode lead, it is possible to provide a secondary battery having improved tensile strength without adding a separate reinforcing layer.

1 is an exploded perspective view illustrating a pouch case and a secondary battery including the same according to an embodiment of the present invention.
FIG. 2 is a view showing a pouch-type secondary battery including the pouch case of FIG. 1 .
3 is an enlarged cross-sectional view of part A of FIG. 2 .
4 is a cross-sectional view illustrating a portion B of FIG. 2 .
FIG. 5 is a cross-sectional view concretely illustrating a portion S of FIG. 4 .
6 is a cross-sectional view illustrating a modified example of the secondary battery described with reference to FIG. 5 .
7 is a graph showing tensile strength according to the volume content of glass fibers when glass fibers are mixed with a polypropylene thermoplastic resin layer as a polymer composite material according to an embodiment of the present invention.
8 is a graph showing the tensile strength according to the weight ratio of nanoplatelet graphite when mixing nanoplatelet graphite (graphite nanoplatelets) with a polypropylene thermoplastic resin layer as a polymer composite material according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention, parts irrelevant to the description are omitted, and the same reference numerals are given to the same or similar elements throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily indicated for convenience of description, the present invention is not necessarily limited to the illustrated bar. In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. And in the drawings, for convenience of description, the thickness of some layers and regions are exaggerated.

Also, when a part of a layer, film, region, plate, etc. is said to be “on” or “on” another part, it includes not only cases where it is “directly on” another part, but also cases where another part is in between. . Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle. In addition, to be "on" or "on" the reference part means to be located above or below the reference part, and to necessarily mean to be located "on" or "on" in the direction opposite to the gravity no.

In addition, throughout the specification, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

In addition, throughout the specification, when referring to "planar", it means when the target part is viewed from above, and "in cross-section" means when viewed from the side when a cross-section of the target part is vertically cut.

1 is an exploded perspective view illustrating a pouch case and a secondary battery including the same according to an embodiment of the present invention. FIG. 2 is a view showing a pouch-type secondary battery including the pouch case of FIG. 1 .

1 and 2 , a secondary battery according to an embodiment of the present invention includes a pouch case 100 and an electrode assembly 200 . The pouch case 100 includes an upper case 110 and a lower case 120 . In FIG. 1 , the upper case 110 and the lower case 120 are connected to each other to form an integral body, but the upper case 110 and the lower case 120 may be separated from each other. The shape of the pouch case 100 is not limited to that illustrated in FIG. 1 , and any shape is possible as long as it has a shape capable of accommodating and sealing the electrode assembly 200 . The upper case 110 and the lower case 120 of FIG. 1 each include concave accommodating parts, and the electrode assembly 200 and the electrolyte may be accommodated in these accommodating parts.

The electrode assembly 200 may be configured in a form in which a positive electrode plate and a negative electrode plate are disposed with a separator interposed therebetween. In this case, 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. Each of the positive and negative plates may be formed as a structure in which an active material slurry is applied to an electrode current collector, and the slurry is typically formed by stirring an active material, a conductive material, a binder, and a plasticizer in a state in which a solvent is added.

In the electrode assembly 200 , there may be an uncoated region to which the slurry is not applied to the electrode plate, and an electrode tab corresponding to each electrode plate may be formed in the uncoated region. Specifically, as shown in FIG. 1 , the positive electrode tab 310 may be attached to the positive electrode plate of the electrode assembly 200 , and the negative electrode tab 410 may be attached to the negative electrode plate of the electrode assembly 200 . The positive electrode tab 310 and the negative electrode tab 410 are electrically connected to the positive electrode lead 320 and the negative electrode lead 420 to form electrode terminals 300 and 400 . At this time, as shown in FIG. 2 , the positive lead 320 and the negative lead 420 may be drawn out of the pouch case 100 .

The pouch-type secondary battery of FIG. 2 exemplifies a pouch-type secondary battery in which the upper case 110 and the lower case 120 shown in FIG. 1 are bonded and sealed.

FIG. 3 is an enlarged cross-sectional view of part A of FIG. 2 .

Referring to FIG. 3 , the upper case 110 and the lower case 120 constituting the pouch case according to an embodiment of the present invention include a pouch case ( 100) including a sealing part formed on the edge. The sealing part is formed along the edge of the pouch case 100 , and all or part of the sealing part may be a bonding area where the upper case 110 and the lower case 120 are joined. The upper case 110 and the lower case 120 may be heat-sealed to seal the pouch case 100 .

Looking at the cross-sectional structure of the pouch case 100 positioned in the bonding area, the upper case 110 and the lower case 120 each including a base layer, a metal layer, and a sealant layer are in contact with each other. The stacking direction of the base layer, the metal layer, and the sealant layer included in the upper case 110 and the stacking direction of the base layer, the metal layer, and the sealant layer included in the lower case 120 are opposite to each other. Specifically, as shown in FIG. 3 , the upper case 110 has a first base layer 112 , a first metal layer 114 , and a first sealant sequentially positioned from the outside to the inside of the upper case 110 . layer 116 . The lower case 120 includes a second base layer 122 , a second metal layer 124 , and a second sealant layer 126 sequentially positioned from the outside to the inside of the lower case 120 . In this case, the first sealant layer 116 and the second sealant layer 126 may contact each other.

Between the first base layer 112 and the first metal layer 114 , between the first metal layer and the first sealant layer 116 , between the second base layer 122 and the second metal layer 124 , and the second metal layer 124 . ) and the second sealant layer 126 , respectively, adhesive layers 113 , 115 , 123 , and 125 may be positioned.

The first base layer 112 and the second base layer 122 may be made of an insulating material such as polyethylene terephthalate (PET) resin or nylon resin to ensure insulation and moldability between the secondary battery and the outside.

The first metal layer 114 and the second metal layer 124 may include one selected from the group consisting of copper, aluminum, nickel, iron, carbon, chromium, manganese, and alloys thereof.

The first sealant layer 116 and the second sealant layer 126 according to the present embodiment may be made of a polymer composite material. Specifically, the polymer composite material included in the first and second sealant layers 116 and 126 may have a structure in which a plurality of fiber or mesh matrixes are dispersed in the thermoplastic resin layers 106 and 206 . As an example, a structure in which a plurality of fiber matrixes 105 and 205 are dispersed in the thermoplastic resin layers 106 and 206 is shown in FIG. 3 . The matrices 105 and 205 according to the present embodiment may include at least one of glass fiber, carbon fiber, and aramid fiber. Here, the carbon fibers may include graphite nanoplatelets, and the thermoplastic resin layers 106 and 206 may include polypropylene, polyester, or epoxy resin.

4 is a cross-sectional view illustrating a portion B of FIG. 2 .

Referring to FIG. 4 , the electrode assembly 200 includes a positive electrode plate 211 , a negative electrode plate 213 , a separator 212 , and an electrode tab 410 . In FIG. 4 , the electrode assembly 200 is illustrated as a stacked electrode assembly formed by interposing a separator 212 between the positive electrode plate 211 and the negative electrode plate 213 , but the electrode assembly 200 may be formed in a jelly roll type.

The positive electrode plate 211 may be formed by coating a positive electrode active material on a current collector made of aluminum, and the negative electrode plate 213 may be formed by coating a negative electrode active material on a current collector made of copper. The electrode tab 410 may be integrally formed with the electrode plates 211 and 213 , and corresponds to an uncoated region of the electrode plates 211 and 213 to which the electrode active material is not applied.

The electrode lead 420 may be connected to the electrode tab 410 , and may be drawn out of the upper case 110 and the lower case 120 . The electrode lead 420 may be made of aluminum or copper. A third sealant layer 133 and a fourth sealant layer 134 are positioned at both ends of the electrode lead 420 . The third sealant layer 133 is positioned between the distal end of the upper case 110 and the electrode lead 420 , and the fourth sealant layer 134 is positioned between the distal end of the lower case 120 and the electrode lead 420 . . Hereinafter, with reference to FIG. 5, a case for a pouch-type secondary battery according to an embodiment of the present invention will be described in detail.

FIG. 5 is a cross-sectional view concretely illustrating part S of FIG. 4 .

Referring to FIG. 5 , the upper case 110 and the lower case 120 are positioned around the electrode lead 420 . The electrode lead 420 and the upper case 110 and the lower case 120 may be bonded to each other by thermal fusion. Since the components of the upper case 110 and the lower case 120 are the same as those described in FIG. 3 , a detailed description thereof will be omitted. The third sealant layer 133 is positioned between the first sealant layer 116 of the upper case 110 and the electrode lead 420 , and the second sealant layer 126 of the lower case 120 and the electrode lead 420 are disposed. A fourth sealant layer 134 is positioned therebetween.

Like the first and second sealant layers 116 and 126 , the third sealant layer 133 and the fourth sealant layer 134 according to the present embodiment may be made of a polymer composite material. A detailed description of the polymer composite material is the same as that of the first and second sealant layers 116 and 126 described with reference to FIG. 3 , and this description may also be applied to the third and fourth sealant layers 133 and 134 . .

5, the first sealant layer 116, the second sealant layer 126, the third sealant layer 133, and the fourth sealant layer 134 were all made of a polymer composite material. As a modification of the embodiment described in 5, at least one of the first, second, third, and fourth sealant layers 116, 126, 133, and 134 may be made of polypropylene, polyester, or an epoxy resin.

6 is a cross-sectional view illustrating a modified example of the secondary battery described with reference to FIG. 5 .

Since the embodiment of FIG. 6 is mostly the same as the embodiment described with reference to FIG. 5 , only the parts with differences will be described, and the contents described in the embodiment of FIG. 5 may be applied to the remaining parts.

Referring to FIG. 6 , the first sealant layer 116 included in the upper case 110 described in FIG. 5 and the third sealant layer 133 positioned on one end surface of the electrode lead 420 are merged into the In the embodiment, one sealant layer 137 is formed, and the second sealant layer 126 included in the lower case 120 described with reference to FIG. 5 and a fourth sealant layer positioned on the other end surface of the electrode lead 420 . 134 are merged to form one sealant layer 138 in the embodiment of FIG. 6 .

The pouch case and the secondary battery including the same according to the embodiments of the present invention described above, by using a polymer composite material instead of the conventional polypropylene as an exterior material of the pouch case or electrode lead, tensile strength of the pouch case or electrode lead itself strength can be improved. Accordingly, the tensile strength of the electrode lead and the pouch case after the thermal fusion process can also be improved.

7 is a graph showing tensile strength according to volume content of glass fibers when glass fibers are mixed with a polypropylene thermoplastic resin layer as a polymer composite material according to an embodiment of the present invention.

Referring to FIG. 7 , it can be seen that the tensile strength is increased when the volume content of the glass fiber is changed to 0%, 20%, or 30% while using the composite material of polypropylene and glass fiber at room temperature.

8 is a graph showing the tensile strength according to the weight ratio of nanoplatelet graphite when mixing nanoplatelet graphite (graphite nanoplatelets) with a polypropylene thermoplastic resin layer as a polymer composite material according to an embodiment of the present invention.

Referring to FIG. 8, while using a composite material of maleic anhydride grafted polypropylene and nanoplatelet graphite, as the weight ratio of nanoplatelet graphite is increased, the tensile strength increases to approximately 15wt% and then at 20wt% It can be seen that there is a slight decrease.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

110: pouch case
105, 205: matrix
116: first sealant layer
126: second sealant layer
133: third sealant layer
134: fourth sealant layer
200: electrode assembly
420: electrode lead

Claims (18)

comprising an upper case and a lower case;
One of the edges of the upper case and the lower case includes a substrate layer, a metal layer and a sealant layer sequentially stacked,
The sealant layer includes a polymer composite material,
The sealant layer includes a thermoplastic resin layer and a matrix,
The matrix is a pouch case comprising at least one of carbon fiber and aramid fiber. In claim 1,
The sealant layer is a pouch case in which a plurality of the matrix in the form of fibers or meshes are dispersed in the thermoplastic resin layer. delete In claim 1,
The carbon fiber is a pouch case comprising nanoplate-shaped graphite. In claim 1,
The thermoplastic resin layer is a pouch case comprising a polypropylene, polyester or epoxy resin. In claim 1,
The pouch case further comprising adhesive layers respectively positioned between the base layer and the metal layer and between the metal layer and the sealant layer. electrode assembly;
an electrode lead connected to the electrode assembly;
a pouch case accommodating the electrode assembly and sealing the electrode assembly in a state in which the electrode lead is drawn out; and
and a sealant layer positioned on at least one of an edge of the pouch case and between the pouch case and the electrode lead,
The sealant layer includes a polymer composite material,
The sealant layer includes a thermoplastic resin layer and a matrix,
The matrix is a secondary battery comprising at least one of carbon fiber and aramid fiber. In claim 7,
The sealant layer is a secondary battery in which a plurality of the matrix in the form of fibers or meshes are dispersed in the thermoplastic resin layer. delete In claim 7,
The carbon fiber is a secondary battery comprising nano-plate-shaped graphite. In claim 7,
The thermoplastic resin layer is a secondary battery comprising polypropylene, polyester, or an epoxy resin. In claim 7,
The sealant layer positioned at the edge of the pouch case includes a first sealant layer and a second sealant layer positioned between an upper case and a lower case constituting the pouch case, and positioned between the pouch case and the electrode lead. and the sealant layer includes a third sealant layer and a fourth sealant layer respectively formed on both surfaces of the electrode lead. In claim 12,
The first sealant layer, the second sealant layer, the third sealant layer, and the fourth sealant layer are positioned between the pouch case and the electrode lead,
The first sealant layer is positioned between the upper case and the third sealant layer, the second sealant layer is positioned between the lower case and the fourth sealant layer, and the third sealant layer is the first sealant layer. and the electrode lead, and the fourth sealant layer is positioned between the electrode lead and the second sealant layer. In claim 12,
The pouch case includes an upper case and a lower case, and the upper case includes a first base layer, a first metal layer and a first sealant layer sequentially positioned from the outside to the inside of the upper case, and the lower case is, a secondary battery comprising a second base layer, a second metal layer, and a second sealant layer sequentially positioned from the outside to the inside of the lower case. 15. In claim 14,
A secondary battery wherein the first base layer and the second base layer each include nylon or polyethylene terephthalate. 15. In claim 14,
between the first base layer and the first metal layer, between the first metal layer and the first sealant layer, between the second base layer and the second metal layer, and between the second metal layer and the second sealant layer, respectively. A secondary battery further comprising an adhesive layer. 15. In claim 14,
A secondary battery in which the first sealant layer and the second sealant layer are in contact with an edge of the pouch case. In claim 7,
The pouch case includes an upper case and a lower case, and one sealant layer is positioned between the upper case and the electrode lead and between the lower case and the electrode lead, respectively.

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