阅读说明：本技术 二次电池的外壳和具有该外壳的二次电池 (Case for secondary battery and secondary battery having the same ) 是由 郑凡永 于 2019-12-12 设计创作，主要内容包括：公开了一种二次电池的外壳和二次电池。根据本发明的一个方面,其中限定了内部空间的二次电池的外壳包括第一金属部和与第一金属部分隔开的第二金属部,其中第一金属部比第二金属部更靠近内部空间设置,并且第一金属部具有比第二金属部的热导率大的热导率。(Disclosed are a secondary battery case and a secondary battery. According to an aspect of the present invention, a case of a secondary battery in which an internal space is defined includes a first metal part and a second metal part spaced apart from the first metal part, wherein the first metal part is disposed closer to the internal space than the second metal part, and the first metal part has a thermal conductivity greater than a thermal conductivity of the second metal part.)

1. A case for a secondary battery having an internal space defined therein, the case comprising:

a first metal part;

a second metal portion spaced apart from the first metal portion; and

a first adhesive part disposed between the first metal part and the second metal part to be adhered to each of the first metal part and the second metal part,

wherein the first metal part is disposed closer to the inner space than the second metal part, and

the first metal part has a thermal conductivity greater than a thermal conductivity of the second metal part.

2. The housing of claim 1, wherein a flame retardant material is mixed in the first adhesive portion.

3. The enclosure of claim 1, wherein the first metal portion or the second metal portion is made of a clad (clad) material.

4. The enclosure of claim 2, wherein said flame retardant material comprises one or more of a phosphorus-based compound, a nitrogen-based compound, a halogen-based compound, an antimony-based compound, a molybdenum-based compound, a zinc borate-based compound, and a metal hydroxide.

5. The enclosure of claim 1, further comprising:

an insulating part disposed to be spaced apart from the first metal part in a direction of the inner space and having an electrical insulating property; and

a second adhesive part disposed between the first metal part and the insulating part to be adhered to each of the first metal part and the insulating part.

6. The housing of claim 1, wherein the first metal portion comprises:

a first layer comprising a first material; and

a second layer comprising a second material, the second material,

wherein the first layer is disposed closer to the interior space than the second layer, and

the first layer has a thermal conductivity greater than a thermal conductivity of the second layer.

7. The housing of claim 1, wherein the second metal portion comprises:

A third layer comprising a third material; and

a fourth layer comprising a fourth material,

wherein the third layer is disposed closer to the inner space than the fourth layer, and

the third layer has a thermal conductivity greater than a thermal conductivity of the fourth layer.

8. The enclosure of claim 6, wherein said first material comprises copper, and

the second material comprises aluminum.

9. The enclosure of claim 7, wherein said third material comprises copper, and

the fourth material comprises aluminum.

10. The housing of claim 5, wherein each of the first and second adhesive portions comprises acid modified polypropylene (PPa), and

the insulating portion includes cast polypropylene (CPP).

11. The enclosure of claim 1, further comprising:

a first outer surface portion laminated on an outer surface of the second metal portion; and

a second outer surface portion laminated on an outer surface of the first outer surface portion,

wherein the first outer surface portion comprises oriented nylon (O-nylon), and

the second outer surface portion includes polyethylene terephthalate (PET).

12. A secondary battery comprising:

an electrode assembly; and

the secondary battery case according to claim 1, which houses the electrode assembly.

Technical Field

Cross Reference to Related Applications

This application claims the benefit of priority from korean patent application No. 10-2019-0023122, filed on 27.2.2019, which is hereby incorporated by reference in its entirety.

Background

Secondary batteries (secondary batteries) that can be repeatedly charged and discharged may be classified into cylinder type secondary batteries, prismatic type secondary batteries, and pouch type secondary batteries according to a manufacturing method or structure thereof. Among these secondary batteries, such a pouch-type secondary battery generally has a structure in which an electrode assembly, which has a structure in which electrodes and separators are alternately arranged, is accommodated in a pouch case in a sheet shape. In particular, pouch type secondary batteries are widely used due to their relatively simple processes and low manufacturing costs.

According to the related art, a sheet-shaped pouch is constructed by a plurality of layers made of different materials. In particular, typically the pouch comprises an aluminium layer. Here, an insulating layer configured to prevent permeation of an electrolyte and moisture is provided on an inner surface of the aluminum layer. The insulating layer is generally used to prevent the aluminum layer from being polarized by preventing the aluminum layer from being electrically connected to the positive electrode or the negative electrode.

However, according to the related art, when the insulating layer is damaged while the secondary battery is manufactured or used, an electrolyte and moisture may permeate through the damaged gap, causing a problem in that the aluminum layer is damaged. In particular, when the insulating layer is damaged in the lithium secondary battery, lithium ions within the electrolyte react with the aluminum layer while the electrolyte penetrates into the aluminum layer, thereby causing oxidation and corrosion of the aluminum layer, resulting in cracks in the aluminum layer, thereby damaging the pouch.

Disclosure of Invention

Technical problem

Accordingly, an object of the present invention devised to solve the problem lies on minimizing damage to a case due to a reaction between an electrolyte and the case during use of a secondary battery.

In particular, the present invention for solving the above problems has an object to minimize damage to an aluminum layer occurring when the aluminum layer is polarized due to damage of an insulating layer.

Technical scheme

In order to achieve the above object, according to one aspect of the present invention, a case of a secondary battery having an internal space defined therein includes: a first metal part; a second metal portion spaced apart from the first metal portion; and a first adhesive part disposed between the first metal part and the second metal part to adhere to each of the first metal part and the second metal part, wherein the first metal part is disposed closer to the internal space than the second metal part, and the first metal part has a thermal conductivity greater than a thermal conductivity of the second metal part.

A flame retardant material may be mixed in the first adhesive part.

The first metal part or the second metal part may be made of a clad (clad) material.

The flame retardant material may include one or more of a phosphorus-based compound, a nitrogen-based compound, a halogen-based compound, an antimony-based compound, a molybdenum-based compound, a zinc borate-based compound, and a metal hydroxide.

The housing may further include: an insulating part disposed to be spaced apart from the first metal part in a direction of the inner space and having an electrical insulating property; and a second adhesive part disposed between the first metal part and the insulating part to be adhered to each of the first metal part and the insulating part.

The first metal part may include: a first layer comprising a first material; and a second layer comprising a second material, wherein the first layer may be disposed closer to the interior space than the second layer, and the first layer may have a thermal conductivity greater than a thermal conductivity of the second layer.

The second metal part may include: a third layer comprising a third material; and a fourth layer comprising a fourth material, wherein the third layer may be disposed closer to the interior space than the fourth layer, and the third layer may have a thermal conductivity greater than a thermal conductivity of the fourth layer.

The first material may include copper and the second material may include aluminum.

The third material may include copper, and the fourth material may include aluminum.

Each of the first and second adhesive parts may include acid-modified polypropylene (PPa), and the insulating part may include cast polypropylene (CPP).

The housing may further include: a first outer surface portion laminated on an outer surface of the second metal portion; and a second outer surface portion laminated on an outer surface of the first outer surface portion, wherein the first outer surface portion may include oriented nylon (O-nylon) and the second outer surface portion may include polyethylene terephthalate (PET).

In order to achieve the above object, according to another aspect of the present invention, a secondary battery includes: an electrode assembly; and a case of a secondary battery, the case accommodating the electrode assembly.

Advantageous effects

According to the present invention, damage to the case, which occurs due to a reaction between the electrolyte and the case during the use of the secondary battery, can be minimized.

In particular, damage to the aluminum layer, which occurs when the aluminum layer is polarized due to damage of the insulating layer, can be minimized.

Drawings

Fig. 1 is an enlarged sectional view illustrating a layered structure of a case of a secondary battery according to the present invention.

Fig. 2 is an enlarged sectional view illustrating a layered structure of a first metal part in a case of a secondary battery according to the present invention.

Fig. 3 is an enlarged sectional view illustrating a layered structure of a second metal part in a case of a secondary battery according to the present invention.

Fig. 4 is a sectional view illustrating an initial state when a first metal part and an electrolyte meet each other in a case of a secondary battery according to the present invention.

Fig. 5 is a sectional view illustrating a later state when the first metal part and the electrolyte meet each other in the case of the secondary battery according to the present invention.

Detailed Description

Hereinafter, the structures of the secondary battery and the case of the secondary battery according to the present invention will be described with reference to the accompanying drawings.

Secondary battery case and secondary battery

Fig. 1 is an enlarged sectional view illustrating a layered structure of a case of a secondary battery according to the present invention.

The case 10 (hereinafter, referred to as "case") of the secondary battery according to the present invention may have a layered structure including a plurality of layers made of different materials, as shown in fig. 1. Further, the housing 10 may be a thin housing having a sheet shape. Further, an inner space may be defined in the housing 10. The inner space may be a space in which an electrode assembly composed of an electrode and a separator is accommodated. Further, the case 10 according to the present invention may be a case used in a pouch type secondary battery.

As shown in fig. 1, the case 10 may include a first metal part 100 and a second metal part 200 spaced apart from the first metal part 100.

Further, a first adhesive part 300 may be disposed between the first metal part 100 and the second metal part 200, the first adhesive part 300 being adhered to each of the first metal part 100 and the second metal part 200 to prevent the first metal part 100 and the second metal part 200 from being relatively moved with respect to each other. The first adhesive part 300 may include acid modified polypropylene (PPa). PPa may refer to a material having a structure in which maleic acid is bonded to polypropylene.

As described above, an inner space may be defined in the housing 10. The first metal part 100 may be disposed closer to the inner space than the second metal part 200.

Further, the case 10 according to the present invention may further include an insulation part 400 disposed to be spaced apart from the first metal part 100 in a direction of the inner space of the case 10 and having an electrical insulation property, and a second adhesive part 500 disposed between the first metal part 100 and the insulation part 400. The second adhesive part 500 may be configured to prevent the first metal part 100 and the insulating part 400 from relatively moving with respect to each other, similar to the case of the first adhesive part 300. Thus, the second adhesive part 500 may be adhered to each of the first metal part 100 and the insulating part 400. Similar to the first adhesive part 300, the second adhesive part 500 may also include acid modified polypropylene (PPa). The insulation part 400 may include cast polypropylene (CPP). Alternatively, the insulation part 400 may be made of CPP.

With continued reference to fig. 1, the exterior can 10 according to the present invention may further include a first outer surface portion 600 laminated on the outer surface of the second metal part 200 and a second outer surface portion 700 laminated on the outer surface of the first outer surface portion 600. The "outer surface of the second metal part and the outer surface of the first outer surface part" may refer to a surface (the top surface in fig. 1) that does not face the inner space defined in the case 10, among two surfaces (the top surface and the bottom surface in fig. 1) of the second metal part and the first outer surface part. First outer surface portion 600 may comprise oriented nylon (O-nylon) and second outer surface portion 700 may comprise polyethylene terephthalate (PET). Alternatively, the first outer surface portion 600 may be made of O-nylon and the second outer surface portion 700 may be made of PET.

Here, according to the present invention, the first metal part 100 may have a thermal conductivity greater than that of the second metal part 200. In addition, the first metal part 100 and the second metal part 200 may have the same thickness. Further, the thicknesses of the first and second metal parts 100 and 200 may be selected according to the elongation of the first and second metal parts 100 and 200 and the depth of forming a cup (cup) in the housing by pressing a portion of the housing.

In the pouch type secondary battery, the insulating part disposed at the innermost side of the case may prevent the electrolyte, moisture, etc. from penetrating into the case. Thus, the metal inside the case can be prevented from contacting the electrolyte or the like. However, when a cup portion (cup) having a concave shape is formed by pressing a portion of the case or when the secondary battery is used, the insulating portion may be broken due to impact or the like. In this case, the electrolyte may permeate through the cracks generated in the insulating portion to meet the metal portion inside the case.

In particular, in the case of a lithium secondary battery, lithium ions are present, and a potential may also be generated in the metal part inside the case during the operation of the secondary battery. For example, (i) when an electrode lead (not shown) protruding to the outside in the secondary battery is excessively sealed with a case, (ii) when the shape of the electrode lead is deformed, and (iii) when an electrode in the secondary battery is biased to one side to contact the case, a metal part inside the case may be electrically connected to the electrode assembly, thereby generating an electric potential in the metal part.

Here, as the potential generated in the metal portion changes, a process in which lithium ions are intercalated and then deintercalated is repeated, thereby generating cracks in the metal portion. A crack generated in a portion of the metal part due to a reaction between the lithium ions and the metal part may extend into the entire region of the metal part, resulting in rapid deterioration of durability of the case.

However, according to the present invention, the metal parts inside the case 10 may be the first metal part 100 and the second metal part 200. Here, the first and second metal parts 100 and 200 may be spaced apart from each other. As a result, when a crack is generated in the insulating part 400, even if a crack is generated in the first metal part 100 that first meets the electrolyte, the crack can be prevented from spreading to the second metal part 200. Thus, the crack can be prevented from spreading to the entire area of the metal part of the case 10, thereby minimizing damage to the case 10. That is, according to the present invention, even if the crack C is first generated in a portion of the first metal part 100 after the first metal part 100 and the electrolyte L meet each other to react in the case of the secondary battery according to the present invention as shown in fig. 4, the crack C may be limited to only the first metal part 100 as shown in fig. 5, thereby preventing the crack C generated in the first metal part 100 from spreading to the second metal part 200.

The temperature within the secondary battery may increase due to overcharge, internal short circuit, or continuous long-term use of the secondary battery during the use of the secondary battery. In this case, it is necessary to rapidly release heat in the secondary battery to the outside. In particular, in a region adjacent to the electrode assembly that generates heat, it is necessary to generate such heat dissipation more rapidly. This is done because, when heat dissipation in a region adjacent to the electrode assembly is not rapidly generated, the temperature of the electrode assembly continues to increase, thereby causing explosion of the secondary battery.

However, according to the present invention, since the first metal part 100 disposed adjacent to the electrode assembly in the pouch type secondary battery has a thermal conductivity greater than that of the second metal part 200 disposed relatively far from the electrode assembly, heat can be more rapidly discharged from the region adjacent to the electrode assembly. Thus, it is possible to solve the safety problem of the secondary battery, which may occur when the temperature of the electrode assembly continues to increase.

With continued reference to fig. 1, according to another embodiment of the present invention, the first adhesive part 300 of the case 10 may include a flame retardant material. For example, a flame retardant material may be mixed in the first adhesive part 300. Thus, according to the present invention, even if a fire occurs inside the secondary battery, such a fire can be prevented from spreading to the outside of the secondary battery by the flame retardant material mixed in the first adhesive part 300. The flame retardant material may include one or more of a phosphorus-based compound, a nitrogen-based compound, a halogen-based compound, an antimony-based compound, a molybdenum-based compound, a zinc borate-based compound, and a metal hydroxide.

Examples of the principle that the flame retardant material performs a flame retardant function include: (i) the principle of consuming the thermal energy used in the combustion process to suppress combustion; (ii) a principle of condensing a combustible material into a solid or a gas to form a protective film so that the combustible material does not contact the gas; (iii) non-flammable gas is generated in the combustion process to provide the principle of fire extinguishing effect; and (iv) a principle of suppressing radical absorption reaction in radical chain reaction (radial chain reaction) during the combustion reaction. Principle (i) may be performed by a metal hydroxide, principle (ii) may be performed by a phosphorus-based compound, principle (iii) may be performed by a metal hydroxide or an antimony-based compound, and principle (iv) may be performed by a halogen-based compound.

The first metal part 100 of the housing 10 may be made of a single metal. However, according to another embodiment of the present invention, the first metal part 100 may be constructed by a plurality of layers made of different materials.

Fig. 2 is an enlarged sectional view illustrating a layered structure of a first metal part in a case of a secondary battery according to the present invention.

As shown in fig. 2, according to another embodiment of the present invention, the first metal part 100 may include a first layer 110 and a second layer 120. The first layer 110 may be a layer disposed relatively close to the inner space of the housing 10, compared to the second layer 120. Here, the first layer 110 may have a thermal conductivity greater than that of the second layer 120.

Fig. 3 is an enlarged sectional view illustrating a layered structure of a second metal part in a case of a secondary battery according to the present invention.

Similarly to the case of the first metal part 100, the second metal part 200 may also have a layered structure according to another embodiment of the present invention. That is, the second metal part 200 may include a third layer 210 and a fourth layer 220. The third layer 210 may be a layer disposed relatively close to the inner space of the case 10, compared to the fourth layer 220. Here, the third layer 210 may have a thermal conductivity greater than that of the fourth layer 220.

As described above, when the temperature inside the secondary battery increases, heat dissipation must be more rapidly generated in the region adjacent to the electrode assembly generating heat, thereby rapidly releasing the heat inside the secondary battery to the outside. Thus, when the thermal conductivity of the first layer 110 is greater than that of the second layer 120, heat can be rapidly discharged to the outside through the first layer 110, which is relatively close to the electrode assembly, compared to the second layer 120. Also, when the thermal conductivity of the third layer 210 is greater than that of the fourth layer 220, heat can be rapidly discharged to the outside through the third layer 210 relatively close to the electrode assembly as compared to the fourth layer 220.

The first layer 110 of the first metal part 100 may include a first material, and the second layer 120 may include a second material. In addition, the third layer 210 of the second metal part 200 may include a third material, and the fourth layer 220 may include a fourth material.

Here, as described above, the thermal conductivity of the first layer 110 may be greater than that of the second layer 120, and the thermal conductivity of the third layer 210 may be greater than that of the fourth layer 220. Thus, the first material may have a thermal conductivity greater than a thermal conductivity of the second material, and the third material may have a thermal conductivity greater than a thermal conductivity of the fourth material.

For example, each of the first material and the third material may include copper, and each of the second material and the fourth material may include aluminum. Alternatively, each of the first material and the third material may be made of copper, and each of the second material and the fourth material may be made of aluminum.

Copper has a thermal conductivity about 1.5 times greater than aluminum. Thus, when each of the first layer 110 disposed relatively closer to the electrode assembly than the second layer 120 and the third layer 210 disposed relatively closer to the electrode assembly than the fourth layer 220 includes or is made of copper, heat within the secondary battery may be more rapidly released to the outside.

The first metal part 100 or the second metal part 200 according to the present invention may be made of a clad (clad) material.

The clad layer is a material capable of exerting the advantages of each metal by bonding two or more metals to each other, and bonding between two or more metals in the clad layer can be achieved by rolling (rolling). When the first layer 110 and the second layer 120 of the first metal part 100 are made of copper and aluminum, respectively, the first metal part 100 made of the clad material may be prepared due to bonding between copper and aluminum by rolling. Similarly, when the third layer 210 and the fourth layer 220 of the second metal part 200 are made of copper and aluminum, respectively, the second metal part 200 made of the clad material may be prepared due to bonding between copper and aluminum by rolling. This can be applied to the case where the first to fourth layers are made of different materials.

The secondary battery according to the present invention may include: an electrode assembly having a structure in which electrodes and separators are alternately disposed; and a case of the secondary battery housing the electrode assembly. The above description is used instead of the description of the structure of the case of the secondary battery.

Although embodiments of the present invention have been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.