KR102504794B1 - Case for rechargeable battery and rechargeable battery comprising the same - Google Patents

Abstract

The present disclosure provides a first thin film layer, a first polymer substrate positioned on the first surface of the first thin film layer, an inner resin layer positioned on the second surface of the first thin film layer, and between the first thin film layer and the inner resin layer. and a first adhesive layer disposed to attach the first thin film layer and the inner resin layer, wherein the first thin film layer has a thickness in the range of 0.001% to 0.5% of the total thickness of the exterior material for a secondary battery, and includes a metal layer and a metal oxide layer. It relates to an exterior material for a secondary battery and a secondary battery including the same.

Description

Exterior material for secondary battery and secondary battery including the same {CASE FOR RECHARGEABLE BATTERY AND RECHARGEABLE BATTERY COMPRISING THE SAME}

The present disclosure relates to an exterior material for a secondary battery and a secondary battery including the same.

A secondary battery includes an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a case in which the electrode assembly is accommodated. The secondary battery case may be made of various types of materials, such as a prismatic or cylindrical case made of metal, an encapsulated case made of polymer, and a pouch type case including both a metal layer and a polymer resin layer.

In particular, the pouch-type case is particularly suitable for manufacturing a cell with a thin thickness and is mainly used because it has the advantage of being easy to manufacture due to its simple structure.

One embodiment of the present disclosure is to provide an exterior material for a secondary battery having a thin thickness and significantly improved moisture barrier properties.

Another embodiment of the present disclosure is to provide a secondary battery including the exterior material for the secondary battery.

In one aspect, the present disclosure provides a first thin film layer, a first polymer substrate located on the first surface of the first thin film layer, an internal resin layer located on the second surface of the first thin film layer, and the first thin film layer and the A first adhesive layer disposed between the inner resin layers to attach the first thin film layer and the inner resin layer, wherein the first thin film layer has a thickness ranging from 0.001% to 0.5% of the total thickness of the exterior material for a secondary battery, and the metal layer and the metal layer An exterior material for a secondary battery including an oxide layer is provided.

In another aspect, the present disclosure provides a secondary battery including an electrode assembly and an exterior material for a secondary battery according to the present invention accommodating the electrode assembly.

An exterior material for a secondary battery according to an embodiment of the present disclosure has excellent moisture barrier properties while having a significantly thinner thickness than the conventional one.

Since the secondary battery according to another embodiment of the present disclosure applies a secondary battery exterior material having excellent durability and a very thin thickness, it is possible to realize a secondary battery with excellent performance by improving the energy density of electrons.

1 to 6 each show an exterior material for a secondary battery according to an embodiment of the present disclosure.
7 is a perspective view of a secondary battery according to an embodiment of the present disclosure.
8 is an exploded perspective view illustrating the secondary battery of FIG. 7 after being disassembled;

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

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to the shown bar.

In addition, throughout the specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

Conventional pouch-type cases are generally composed of an inner resin layer, a water barrier metal layer, and an outer resin layer. However, since the thickness of the water barrier metal layer in a pouch-type case having such a structure is generally in the range of 35 μm to 40 μm, it is difficult to thin the exterior material for a secondary battery.

In addition, the moisture barrier metal layer can be reduced to a thickness smaller than the above thickness range by using a process such as deposition, but in this case, a pin hole or the like is generated in the moisture barrier metal layer, reducing the moisture permeability of the pouch-type case, and the moisture barrier metal layer It is easily damaged even by a light impact from the outside, and moisture penetrates easily into the secondary battery, causing HF gas to be generated, thereby deteriorating the performance of the secondary battery and causing corrosion of the exterior material, resulting in electrolyte leakage.

Moreover, as the demand for wearable electronic devices continues to increase recently, the demand for secondary batteries with excellent flexibility is increasing. However, since the conventional pouch-type case includes a moisture barrier metal layer of a certain thickness or more, deformation such as wrinkling during bending is difficult. There is a problem in that the flexibility of the secondary battery is lowered.

As a result of repeated research to solve these problems, the inventors of the present invention have found that, when the secondary battery packaging material includes the first thin film layer containing metal and metal oxide, the thickness is in the range of 0.01% to 0.001% of the total thickness of the secondary battery packaging material. The present invention was completed by finding out that an exterior material for a secondary battery having excellent flexibility while improving moisture permeability resistance could be obtained even if the first thin film layer was formed to have.

1 shows a cross section of an exterior material for a secondary battery according to an embodiment of the present disclosure.

Referring to FIG. 1 , an exterior material 130 for a secondary battery according to an embodiment of the present disclosure includes a first polymer substrate 31 positioned on a first surface of a first thin film layer 41 and the first thin film layer 41. An inner resin layer 70 positioned on the second surface and disposed between the first thin film layer 41 and the inner resin layer 70 to attach the first thin film layer 41 and the inner resin layer 70 A first adhesive layer 50 is included.

Here, the first thin film layer 41 may have a thickness in the range of 0.001% to 0.5% of the total thickness of the secondary battery exterior material 130, and more specifically, in the range of 0.01% to 0.4% or 0.05% to 0.3%. there is. When the thickness of the first thin film layer 41 satisfies the above numerical range, the exterior material according to the present disclosure may have excellent moisture permeability resistance while having a significantly thinner thickness than the prior art.

In addition, the first thin film layer 41 acts as a barrier layer capable of preventing leakage of electrolyte or penetration of moisture, etc., and is characterized in that it includes a metal layer and a metal oxide layer.

A thickness ratio (metal layer:metal oxide layer) of the metal layer and the metal oxide layer may be in the range of 1:1 to 5:1. When the thickness ratio of the metal layer and the metal oxide layer satisfies the above numerical range, it is very advantageous in that it is possible to secure excellent resistance to moisture permeability and at the same time secure flexibility of the exterior material for a secondary battery.

The metal layer may include at least one selected from the group consisting of aluminum, stainless steel, and combinations thereof, but is not limited thereto.

In addition, the metal oxide layer may include aluminum oxide (Al ₂ O ₃ ).

In the present disclosure, the metal layer can be formed using chemical vapor deposition (CVD) and/or sputtering, and a metal oxide layer is formed here by atomic layer deposition (ALD). The first thin film layer 41 including a metal layer and a metal oxide layer may be configured.

The first polymer substrate 31 may be an outer layer that protects the exterior material 130 for secondary batteries from the external environment. The first polymer substrate 31 may be, for example, one or more selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, co-polyester, polycarbonate, and nylon film. It may be formed, but is not limited thereto.

Also, the thickness of the first polymer substrate 31 may be 5 μm to 100 μm, 5 μm to 50 μm, 7 μm to 20 μm, or 7 μm to 15 μm. If the thickness of the first polymeric substrate 31 is less than 5 μm, physical properties are poor and can be easily torn, and if it exceeds 100 μm, moldability such as injection and forming may be poor, and the battery capacity per unit volume of the secondary battery this may deteriorate.

In the present disclosure, the ratio between the thickness of the first polymer substrate 31 and the thickness of the first thin film layer 41 (first polymer: first thin film layer) is 10:1 to 500:1, more specifically, 10:1 to 50:1. When the ratio of the thickness of the first polymer substrate 31 and the thickness of the first thin film layer 41 satisfies the above range, forming characteristics are excellent.

Next, the inner resin layer 70 is for improving the insulation and electrolyte resistance of the secondary battery exterior 130, and may be formed of, for example, polyolefin or a copolymer of polyolefin, and more specifically, the above Polyolefin may be polyethylene (PE) or polypropylene (PP), but is not limited thereto.

The inner resin layer 70 may have a thickness of 5 μm to 100 μm, 10 μm to 50 μm, or 15 μm to 30 μm. When the thickness of the inner resin layer 70 satisfies the above range, moldability, adhesiveness, and chemical resistance are excellent.

In addition, a first adhesive layer 51 may be positioned between the first thin film layer 41 and the inner resin layer 70, through which the first thin film layer 41 and the inner resin layer 70 may be attached. .

As the first adhesive layer 51, materials well known in the art as having adhesiveness may be used without limitation, and for example, a polyurethane-based adhesive may be used.

2 shows a cross section of an exterior material for a secondary battery according to an embodiment of the present disclosure.

Referring to FIG. 2 , the exterior material 131 for secondary batteries may further include a functional protective layer 60 positioned between the first thin film layer 41 and the first adhesive layer 51 .

The functional protective layer 60 is an electrolyte-improving layer for preventing the leakage of the electrolyte located inside the exterior material 131 for the battery to the outside of the exterior material, for example, chromium (Cr) and manganese (Mn)) It may be formed of metals such as aluminum oxide (Al ₂ O ₃ ), ceramics such as silicon dioxide (SiO ₂ ), and the like. At this time, the functional protective layer 60 may be formed using the above material by a method such as Chemical Vapor Deposition (CVD) and/or sputtering.

In addition, a second adhesive layer 52 may be positioned between the first thin film layer 41 and the functional protective layer 60, through which the first thin film layer 41 and the functional protective layer 60 may be attached. The second adhesive layer 52 may be formed using the same material as the first adhesive layer 51 .

Therefore, in this embodiment, the exterior material 131 for a secondary battery includes a first polymer substrate 31, a first thin film layer 41, a second adhesive layer 52, a functional protective layer 60, a first adhesive layer 51 and The inner resin layer 70 may be sequentially stacked.

3 shows a cross section of an exterior material for a secondary battery according to an embodiment of the present disclosure.

Referring to FIG. 3 , the exterior material 132 for secondary batteries may further include an internal metal layer 80 positioned between the first thin film layer 41 and the first adhesive layer 51 .

When the inner metal layer 80 is included, the formability of the exterior material 132 for a secondary battery according to the present disclosure can be further improved. As the inner metal layer 80, for example, a soft aluminum foil may be used, but an iron-containing aluminum foil may be used to improve formability.

The inner metal layer may have a thickness of 4 μm to 35 μm, 4 μm to 30 μm, or 4 μm to 25 μm. When the thickness of the inner metal layer satisfies the above range, there is an advantage in preventing moisture permeability reduction from being reduced due to the connection of pin holes existing inside the metal layer. In addition, when the first thin film layer and/or the second thin film layer are included, the thickness of the inner metal layer may be further reduced, for example, the thickness of the inner metal layer may be reduced to a range of about 4 μm to about 15 μm. As the thickness of the inner metal layer increases, the forming property improves, and as the thickness of the inner metal layer decreases, it has the advantage that thinning is possible. Therefore, depending on the characteristics of the product to which the lithium secondary battery to which the exterior material for a secondary battery according to the present embodiment is applied is applied, the inner metal layer thickness can be adjusted appropriately.

Therefore, in the present embodiment, the exterior material 132 for a secondary battery includes the first polymer substrate 31, the first thin film layer 41, the inner metal layer 80, the first adhesive layer 51, and the inner resin layer 70 sequentially. It may be a layered structure.

4 shows a cross section of an exterior material for a secondary battery according to an embodiment of the present disclosure.

Referring to FIG. 4 , the secondary battery exterior material 133 includes a second thin film layer 42 and a second polymer substrate ( 32) may have a sequentially stacked structure.

At this time, the material and forming method for forming the second thin film layer 42 are the same as those for the first thin film layer 41, and the material and forming method for forming the second polymer substrate 32 are the same as those for the first polymer substrate 31. Therefore, we will omit it here.

A third adhesive layer 53 may be positioned between the second thin film layer 42 and the first polymer substrate 31, through which the second thin film layer 42 and the first polymer substrate 31 may be attached. The third adhesive layer 53 may be formed using the same material as the first adhesive layer 51 .

In addition, the sum of the thicknesses of the first thin film layer 41 and the second thin film layer 42 may be 0.001% to 0.7% of the total thickness of the secondary battery packaging material 133, and more specifically, 0.01% to 0.6% or 0.1%. % to 0.5%. When the sum of the thicknesses of the first thin film layer 41 and the second thin film layer 42 satisfies the above ratio with respect to the total thickness of the exterior material 133 for secondary batteries, the exterior material 133 according to the present disclosure has a significantly thinner thickness than the prior art. It can have excellent moisture permeability while having.

The thickness ratio of the second polymer substrate and the second thin film layer (second polymer substrate: second thin film layer) may be in the range of 10:1 to 200:1, and more specifically, in the range of 50:1 to 100:1. there is. When the ratio between the thickness of the second polymer substrate 32 and the thickness of the second thin film layer 42 satisfies the above range, there is an advantage in that the second thin film layer is easily formed.

Therefore, in this embodiment, the secondary battery exterior material 133 includes the second polymer substrate 32, the second thin film layer 42, the third adhesive layer 53, the first polymer substrate 31, and the first thin film layer 41. , The first adhesive layer 51 and the inner resin layer 70 may be sequentially stacked.

5 and 6 show cross-sections of an exterior material for a secondary battery according to an embodiment of the present disclosure.

Referring to FIG. 5 , the exterior material 134 for a secondary battery includes a second polymer substrate 32, a second thin film layer 42, a third adhesive layer 53, a first polymer substrate 31, and a first thin film layer 41. , The second adhesive layer 52, the functional protective layer 60, the first adhesive layer 51 and the inner resin layer 70 may be sequentially laminated structure.

Referring to FIG. 6 , the secondary battery exterior material 135 includes a second polymer substrate 32, a second thin film layer 42, a third adhesive layer 53, a first polymer substrate 31, and a first thin film layer 41. , The second adhesive layer 52, the inner metal layer 80, the functional protective layer 60, the first adhesive layer 51 and the inner resin layer 70 may be sequentially stacked.

Since each component using the same reference numeral is the same as the above, it will be omitted here.

In the present disclosure, since the first and second thin metal layers 41 and 42 include a metal layer and a metal oxide layer as described above, each of the first and second thin metal layers 41 and 42 is a secondary battery exterior material 130 and 131 , 132, 133, 134, 135) Even if it is formed thin to have a thickness in the range of 0.01% to 0.001% based on the total thickness, it is possible to implement an exterior material with excellent moisture permeability resistance.

Accordingly, since thinning of the exterior material for secondary batteries is possible through this, it is possible to implement an exterior material for secondary batteries that has excellent flexibility and can be easily applied to a flexible battery.

Next, a configuration of a secondary battery according to an embodiment of the present disclosure will be described.

FIG. 7 is a perspective view illustrating a secondary battery according to an exemplary embodiment of the present disclosure, and FIG. 8 is an exploded perspective view illustrating the secondary battery of FIG. 7 after being disassembled.

7 and 8 , a secondary battery 200 according to an embodiment of the present disclosure includes an electrode assembly 10 and an exterior material 130 accommodating the electrode assembly 10, and the exterior material 130 ) May be the exterior materials (130, 131, 132, 133) according to the present invention described above.

First, the electrode assembly 10 performs charging and discharging functions, and is manufactured in a form in which a separator 13 is interposed between a positive electrode 11 as a first electrode and a negative electrode 12 as a second electrode. At this time, the polarities of the first electrode and the second electrode are not particularly limited. That is, the first electrode may be the cathode 12 and the second electrode may be the anode 11 .

On the other hand, the positive electrode 11 is made of a positive electrode current collector made of a thin metal plate such as aluminum and a positive electrode active material layer formed on the positive electrode current collector, and the negative electrode 12 is made of a negative electrode current collector made of a thin metal plate such as copper and a negative electrode current collector. It consists of a negative electrode active material layer formed on it.

In addition, the electrode assembly 10 may be formed into a flat structure by interposing the separator 13 between the strip-shaped positive electrode 11 and the negative electrode 12, then winding it and then pressing it.

However, the present invention is not limited thereto, and the electrode assembly 10 has a structure in which a plurality of positive electrodes 11 and negative electrodes 12 formed in a rectangular sheet shape are alternately stacked with a separator 13 interposed therebetween. can be made with At this time, the separator 13 is interposed between the positive electrode 11 and the negative electrode 12 to insulate the positive electrode 11 and the negative electrode 12 while providing a passage through which ions move.

Next, in the electrode assembly 10, the positive electrode uncoated portion and the negative electrode uncoated portion are located at one end, the positive terminal 21 is attached to the anode uncoated portion by welding, and the negative electrode terminal 22 is welded to the negative electrode uncoated portion. attached

In the secondary battery according to an embodiment of the present invention, the exterior material 130 may include a housing part 15 in which the electrode assembly 10 is embedded and an opening formed on one side thereof, and a cover part 25 sealing the opening. can

At this time, the housing unit 15 may be manufactured in a form in which an opening is formed on one side of a wide surface of a hexahedron by, for example, injection, forming, or the like.

The electrode assembly 10 described above is inserted into this opening, and the opening is sealed by the cover part 25 .

Here, the cover part 25 may be sealed by bonding using an adhesive along a line on one side where the opening of the housing part 15 is located.

Alternatively, in the present invention, the cover part 25 may be sealed by a method such as heat fusion after directly attaching the inner resin layers 70 of the packaging material constituting the housing part 15 without a separate adhesive.

The secondary battery 200 according to the present disclosure has very excellent durability while acting as a thin film exterior material, and since a secondary battery exterior material having a significantly thinner thickness than the conventional one is applied, the energy density of the lithium secondary battery is reduced by approximately 1.6% to 3.2%. degree can be improved.

The present invention will be examined in detail through the following examples.

Example One

A first polymer substrate made of polyethylene terephthalate (PET) with a thickness of 9 μm, a first thin film layer with a thickness of 0.1 μm, an internal metal layer made of aluminum with a thickness of 7 μm, a first adhesive layer with a thickness of 2.5 μm, and a thickness of 25 μm An inner resin layer made of polyethylene (PE) was sequentially laminated to prepare a laminate having the structure shown in FIG. 3 . At this time, the first thin film layer includes a metal layer made of aluminum and a metal oxide layer made of aluminum oxide, and was formed using sputtering and atomic layer deposition, and the inner metal layer was laminated using lamination.

Example 2

A first polymer substrate made of polyethylene terephthalate (PET) with a thickness of 9 μm, a first thin film layer with a thickness of 0.1 μm, a first adhesive layer with a thickness of 2.5 μm, and an inner water layer made of polyethylene (PE) with a thickness of 25 μm Layers were stacked sequentially. At this time, the first thin film layer includes a metal layer made of aluminum and a metal oxide layer made of aluminum oxide, and was formed using sputtering and atomic layer deposition methods.

Next, a second thin film layer having a thickness of 0.1 μm is attached to the opposite side of the first polymer substrate to which the first thin film layer is laminated, with a third adhesive layer having a thickness of 2.5 μm interposed therebetween, and the second thin film layer is made of PET with a thickness of 9 μm. A laminate having the structure shown in FIG. 4 was prepared by laminating two polymer substrates.

Example 3

A laminate having the structure shown in FIG. 5 in the same manner as in Example 2, except that a 1 μm-thick electrolyte solution improving layer (functional protective layer) made of chromium (Cr) was attached between the first thin film layer and the first adhesive layer. was manufactured. The electrolyte solution improving layer was attached through a second adhesive layer having a thickness of 2.5 μm.

Example 4

A laminate having the structure shown in FIG. 6 was manufactured in the same manner as in Example 3, except that an internal metal layer made of aluminum having a thickness of 7 μm was laminated on the internal electrolyte solution improving layer using lamination.

comparative example One

A resin layer made of PET with a thickness of 15 μm, a first adhesive layer with a thickness of 2.5 μm, a metal layer made of aluminum with a thickness of 25 μm, a second adhesive layer with a thickness of 2.5 μm, and a resin layer made of polypropylene with a thickness of 20 μm are sequentially laminated and laminated. sieve was prepared.

Experimental example One - moisture permeability evaluation

Using the laminates according to Examples 1 to 4 and Comparative Example 1, a square shape of 60 mm in width and 120 mm in length was made into a bag, and a basic electrolyte was added, and then sealed to a thickness of 2 mm, and then put into a chamber at 60 degrees and RH 90%. After being allowed to stand for a week, the moisture content of the electrolyte was measured. The results are shown in Table 1 below.

division H ₂ O moisture vapor (ppm) Example 1 148 Example 2 167 Example 3 169 Example 4 89 Comparative Example 1 178

As shown in Table 1, an embodiment including a thin film layer having a thickness range of 0.01% to 0.001% based on the total thickness of the exterior material as in one embodiment of the present invention, wherein the thin film layer is composed of a metal layer and a metal oxide layer It can be seen that the laminate according to 1 to 4 has very excellent moisture permeability resistance when compared to the laminate according to Comparative Example 1 including a thin film layer made of only a metal layer.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and is easily changed from the embodiments of the present invention by those skilled in the art to which the present invention belongs, so that the same It includes all changes within the scope recognized as appropriate.

31: first polymer substrate
32: second polymer substrate
41: first thin film layer
42: second thin film layer
51: first adhesive layer
52: second adhesive layer
53: third adhesive layer
60: functional protective layer
70, 80: inner metal layer
130, 131, 132, 133, 134, 135: exterior material for secondary batteries
200: secondary battery
10: electrode assembly
21: positive terminal
22: negative terminal
15: storage unit
25: cover part
11: anode
12: cathode
13: separator

Claims (14)

a first thin film layer;
a first polymer substrate positioned on a first surface of the first thin film layer;
an inner resin layer positioned on the second surface of the first thin film layer; and
a first adhesive layer disposed between the first thin film layer and the inner resin layer to adhere the first thin film layer and the inner resin layer;
including,
The first thin film layer has a thickness in the range of 0.17% to 0.5% of the total thickness of the secondary battery casing, and the first thin film layer includes a metal layer and a metal oxide layer. According to claim 1,
The thickness ratio of the metal layer and the metal oxide layer is in the range of 1:1 to 5:1. According to claim 2,
The metal layer is at least one exterior material for a secondary battery selected from the group consisting of aluminum, stainless steel, and combinations thereof. According to claim 2,
The metal oxide layer is an exterior material for a secondary battery including aluminum oxide (Al ₂ O ₃ ). According to claim 1,
The exterior material for a secondary battery wherein the thickness ratio of the first polymer substrate and the thickness of the first thin film layer is in the range of 10:1 to 500:1. According to claim 1,
An exterior material for a secondary battery further comprising a functional protective layer positioned between the first thin film layer and the first adhesive layer. According to claim 6,
The exterior material for a secondary battery further comprising a second adhesive layer disposed between the first thin film layer and the functional protective layer to attach the first thin film layer and the functional protective layer. According to claim 1,
An exterior material for a secondary battery further comprising an inner metal layer positioned between the first thin film layer and the first adhesive layer. According to claim 8,
The inner metal layer has a thickness of 4 μm to 35 μm. According to claim 1,
The first polymer substrate,
An exterior material for a secondary battery, further comprising a second thin film layer and a second polymer substrate, which are located on the opposite side to which the first thin film layer is located and are sequentially stacked. According to claim 10,
An exterior material for a secondary battery comprising a third adhesive layer disposed between the second thin film layer and the first polymer substrate to adhere the second thin film layer to the first polymer substrate. According to claim 10,
The sum of the thicknesses of the first thin film layer and the second thin film layer is in the range of 0.17% to 0.7% of the total thickness of the exterior material for secondary batteries. According to claim 10,
The thickness ratio of the second polymer substrate and the second thin film layer is in the range of 10:1 to 200:1. an electrode assembly, and
The exterior material for a secondary battery according to any one of claims 1 to 13 accommodating the electrode assembly.
A secondary battery comprising a.

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