Cross Citation with Related Applications
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0023122 dated February 27, 2019, and all contents disclosed in the documents of the Korean patent application are incorporated as a part of this specification.
[3]
technical field
[4]
The present invention relates to a secondary battery exterior material and a secondary battery including the exterior material, and more particularly, to a secondary battery exterior material having a structure that can solve the ignition problem of a secondary battery while improving corrosion resistance to an electrolyte, and the exterior material It relates to a secondary battery comprising.
background
[5]
A secondary battery capable of repeatedly charging and discharging may be classified into a cylindrical secondary battery, a prismatic secondary battery, a pouch-type secondary battery, etc. according to its structure or manufacturing method. Among them, the pouch-type secondary battery generally has a structure in which an electrode assembly having a structure in which electrodes and a separator are alternately arranged in a sheet-shaped pouch case is accommodated. In particular, the pouch-type secondary battery is widely used because the manufacturing process is relatively simple and the manufacturing cost is low.
[6]
Meanwhile, according to the prior art, a sheet-shaped pouch is composed of a plurality of layers made of different materials. In particular, the pouch generally includes an aluminum layer, and an insulating layer for preventing penetration of electrolyte and moisture is provided on the inner surface of the aluminum layer. This insulating layer serves to prevent the aluminum layer from being electrically connected to the anode or the cathode so that the aluminum layer does not have polarity in ordinary times.
[7]
However, according to the prior art, when the insulating layer is damaged in the process of manufacturing or using a secondary battery, electrolyte and moisture penetrate into the aluminum layer through the damaged gap, resulting in damage to the aluminum layer. In particular, when the insulating layer is damaged in a lithium secondary battery, lithium ions in the electrolyte react with the aluminum layer in the process of penetrating into the aluminum layer, and the aluminum layer is oxidized or corroded, thereby causing cracks in the aluminum layer, causing damage to the pouch. There was a problem with this.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[8]
Accordingly, the problem to be solved by the present invention is to minimize the problem of damage to the exterior material that may occur due to a reaction between the electrolyte and the exterior material in the course of using the secondary battery.
[9]
In particular, the problem to be solved by the present invention is to minimize the problem of damage to the aluminum layer that may occur when the aluminum layer becomes polar due to damage to the insulating layer.
means of solving the problem
[10]
According to one aspect of the present invention for achieving the above object, there is provided an exterior material for a secondary battery having an internal space, comprising: a first metal part; a second metal part spaced apart from the first metal part; and a first adhesive part provided between the first metal part and the second metal part and being respectively adhered to the first metal part and the second metal part; Including, wherein the first metal part is provided closer to the inner space than the second metal part, and the thermal conductivity of the first metal part is greater than the thermal conductivity of the second metal part is provided.
[11]
A flame retardant material may be mixed in the first adhesive part.
[12]
The first metal part or the second metal part may be made of a clad material.
[13]
The flame retardant material may include at least one of a phosphorus compound, a nitrogen compound, a halogen compound, an antimony compound, a molybdenum compound, a zinc borate compound, and a metal hydroxide.
[14]
an insulating part provided to be spaced apart from the first metal part in the inner space direction and having electrical insulation; and a second adhesive part provided between the first metal part and the insulating part, and being respectively adhered to the first metal part and the insulating part; may further include.
[15]
The first metal part may include: a first layer including a first material; and a second layer comprising a second material; Including, wherein the first layer is provided adjacent to the inner space than the second layer, the thermal conductivity of the first layer may be greater than the thermal conductivity of the second layer.
[16]
The second metal part may include a third layer including a third material; and a fourth layer comprising a fourth material; Including, wherein the third layer is provided adjacent to the inner space than the fourth layer, the thermal conductivity of the third layer may be greater than the thermal conductivity of the fourth layer.
[17]
The first material may include copper, and the second material may include aluminum.
[18]
The third material may include copper, and the fourth material may include aluminum.
[19]
The first adhesive part and the second adhesive part may include acid modified polypropylene (PPa), and the insulating part may include cast polypropylene (CPP).
[20]
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; Including, the first outer surface portion may include O-nylon (oriented nylon), and the second outer surface portion may include PET (polyethylene terephthalate).
[21]
According to another aspect of the present invention for achieving the above object, the electrode assembly; and an exterior material for the secondary battery accommodating the electrode assembly; There is provided a secondary battery comprising a.
Effects of the Invention
[22]
According to the present invention, it is possible to minimize the problem of damage to the exterior material that may occur due to a reaction between the electrolyte and the exterior material in the process of using the secondary battery.
[23]
In particular, according to the present invention, it is possible to minimize the problem of damage to the aluminum layer that may occur when the aluminum layer becomes polar due to damage to the insulating layer.
Brief description of the drawing
[24]
1 is an enlarged cross-sectional view illustrating a layered structure of a secondary battery packaging material according to the present invention.
[25]
2 is an enlarged cross-sectional view illustrating the layered structure of the first metal part in the secondary battery packaging material according to the present invention.
[26]
3 is an enlarged cross-sectional view illustrating the layered structure of the second metal part in the secondary battery packaging material according to the present invention.
[27]
4 is a cross-sectional view showing an initial state when the first metal part and the electrolyte meet and react in the packaging material for a secondary battery according to the present invention.
[28]
5 is a cross-sectional view showing a later state when the first metal part and the electrolyte meet and react in the packaging material for a secondary battery according to the present invention.
Modes for carrying out the invention
[29]
Hereinafter, the structure of the secondary battery packaging material and secondary battery according to the present invention will be described with reference to the drawings.
[30]
[31]
External materials for secondary batteries and secondary batteries
[32]
1 is an enlarged cross-sectional view illustrating a layered structure of a secondary battery packaging material according to the present invention.
[33]
[34]
The exterior material for a secondary battery according to the present invention (hereinafter, referred to as an 'exterior material') may have a layered structure having a plurality of layers made of different materials as shown in FIG. 1 . Also, the exterior material 10 may be a sheet-shaped exterior material having a thin thickness. In addition, an inner space may be formed in the exterior material 10 , and the inner space may be a space in which an electrode assembly composed of an electrode and a separator is accommodated. In addition, the packaging material 10 according to the present invention may be a packaging material used in a pouch-type secondary battery.
[35]
As shown in FIG. 1 , the exterior material 10 may include a first metal part 100 and a second metal part 200 spaced apart from the first metal part 100 .
[36]
In addition, between the first metal part 100 and the second metal part 200 , the first metal part 100 and the second metal part 200 do not cause a relative movement between the first metal part 100 and the second metal part 200 . The first adhesive part 300 that is respectively adhered to the second metal part 200 may be provided. The first adhesive part 300 may include acid modified polypropylene (PPa). PPa may mean a material having a structure in which maleic acid is grafted onto polypropylene.
[37]
As described above, an internal space may be formed in the exterior material 10 , and the first metal part 100 may be provided closer to the internal space than the second metal part 200 .
[38]
In addition, the exterior material 10 according to the present invention is provided spaced apart from the first metal portion 100 in the inner space direction of the exterior material 10 , the insulating portion 400 having electrical insulation, and the first metal portion 100 . and a second bonding unit 500 provided between the insulating unit 400 and the insulating unit 400 . Similar to the case of the first adhesive part 300 , the second adhesive part 500 may be configured to prevent relative movement between the first metal part 100 and the insulating part 400 from occurring. Accordingly, the second adhesive part 500 may be adhered to each of the first metal part 100 and the insulating part 400 . Also, similarly to the first adhesive part 300 , the second adhesive part 500 may also include acid modified polypropylene (PPa). Also, the insulating part 400 may include cast polypropylene (CPP). Alternatively, the insulating part 400 may be made of CPP.
[39]
Continuing to refer to FIG. 1 , the exterior material 10 according to the present invention includes a first outer surface portion 600 laminated on the outer surface of the second metal portion 200 , and an outer side of the first outer surface portion 600 . It may further include a second outer surface portion 700 laminated on the surface. 'The outer surface of the second metal part and the outer surface of the first outer surface part' means that the inner space formed in the exterior material 10 among both surfaces of the second metal part and the first external surface part (the upper surface and the lower surface based on FIG. 1) is not facing. It can be seen as meaning a surface that does not (the upper surface with reference to FIG. 1). The first outer surface portion 600 may include oriented nylon (O-nylon), and the second outer surface portion 700 may include polyethylene terephthalate (PET). Alternatively, the first outer surface portion 600 may be formed of O-nylon, and the second outer surface portion 700 may be formed of PET.
[40]
At this time, according to the present invention, the thermal conductivity of the first metal part 100 may be greater than the thermal conductivity of the second metal part 200 . Also, the thickness of the first metal part 100 and the thickness of the second metal part 200 may be the same as each other. In addition, the thickness of the first metal part 100 and the second metal part 200 is determined by the elongation of the first metal part 100 and the second metal part 200, and the cup ( cup) may be selected according to the depth at which the cup is formed in the process of forming the cup.
[41]
In the pouch-type secondary battery, the insulator provided on the innermost side of the casing is prevented from penetrating the electrolyte and moisture into the casing. Accordingly, the metal in the packaging material is prevented from coming into contact with the electrolyte or the like. However, cracks may occur in the insulating portion due to a process of forming a cup having a recessed shape by pressing a partial region of the exterior material or an impact during use of the secondary battery. In this case, the electrolyte or the like penetrates between the cracks formed in the insulating part, so that the metal part in the exterior material and the electrolyte meet each other.
[42]
In particular, in the case of a lithium secondary battery, lithium ions are present in the electrolyte, and at the same time, a potential may be formed in the metal part inside the exterior material during the operation of the secondary battery. For example, (i) when the sealing between the electrode lead (not shown) protruding to the outside from the secondary battery and the exterior material becomes excessive, (ii) when the shape of the electrode lead is deformed, and (iii) the inside of the secondary battery When the electrode is brought into contact with the casing by tilting the electrode to one side, the metal part inside the casing is electrically connected to the electrode assembly, so that an electric potential may be formed in the metal part.
[43]
At this time, as the electric potential formed in the metal part changes, lithium ions in the electrolyte are inserted into the metal part and then the process of desorption is repeated, thereby generating a crack in the metal part. Cracks generated in a part of the metal part due to the reaction between lithium and the metal part spread to the entire area of ​​the metal part, and as a result, the durability of the exterior material is rapidly reduced.
[44]
However, according to the present invention, the metal part in the exterior material 10 is divided into the first metal part 100 and the second metal part 200 , and the first metal part 100 and the second metal part 200 are spaced apart from each other. can Therefore, when a crack occurs in the insulating part 400 , even if a crack occurs in the first metal part 100 that first meets the electrolyte, the crack may be prevented from spreading to the second metal part 200 . Therefore, according to the present invention, it is possible to prevent cracks from spreading to the entire area of ​​the metal part of the exterior material 10 , so that damage to the exterior material 10 can be minimized. That is, according to the present invention, as shown in FIG. 4 , after the first metal part 100 and the electrolyte L meet and react in the secondary battery packaging material according to the present invention, a part of the first metal part 100 initially Even if a crack (C) occurs in the region, since the crack (C) is limited only to the first metal part 100 as shown in FIG. 5 , the crack C formed in the first metal part 100 is It is possible to prevent diffusion into the metal part 200 .
[45]
Meanwhile, in the course of using the secondary battery, the temperature inside the secondary battery may rise due to overcharging, internal short circuit, or continuous use for a long time. In particular, such heat dissipation needs to occur more rapidly in an area adjacent to the electrode assembly where heat is generated. This is because, when heat dissipation does not occur rapidly in the region adjacent to the electrode assembly, the temperature of the electrode assembly continues to rise, which may cause problems such as explosion of the secondary battery.
[46]
However, according to the present invention, in the pouch-type secondary battery, the thermal conductivity of the first metal part 100 provided in the region adjacent to the electrode assembly is higher than the thermal conductivity of the second metal part 200 provided in the region relatively far from the electrode assembly. Because of its size, heat can be dissipated more quickly in the region adjacent to the electrode assembly. Accordingly, it is possible to solve the safety problem of the secondary battery that may occur when the temperature of the electrode assembly continues to rise.
[47]
Continuing to refer to FIG. 1 , according to another embodiment of the present invention, the first adhesive part 300 of the exterior material 10 may include a flame retardant material. For example, a flame retardant material may be mixed in the first adhesive part 300 . Therefore, according to the present invention, even if a fire occurs inside the secondary battery, it is possible to prevent the fire 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 at least one of a phosphorus compound, a nitrogen compound, a halogen compound, an antimony compound, a molybdenum compound, a zinc borate compound, and a metal hydroxide.
[48]
The principle of flame-retardant action of flame-retardant materials is (i) the principle of suppressing combustion by consuming thermal energy used in the combustion process, (ii) condensing the combustible materials into solid or gas to prevent them from contacting the gas and then a barrier (iii) the principle of fire-extinguishing by generating incombustible gas during combustion, (iv) the principle of suppressing the radical absorption reaction in the radical chain reaction in the combustion reaction, etc. . wherein the principle (i) is carried out by a metal hydroxide, the principle (ii) is performed by a phosphorus compound, the principle (iii) is performed by a metal hydroxide or antimony compound, and the principle (iv) is carried out by a halogen compound. can
[49]
Meanwhile, the first metal part 100 of the exterior material 10 may be made of a single metal. On the other hand, according to another embodiment of the present invention, the first metal part 100 may include a plurality of metal parts made of different materials. It may consist of layers.
[50]
2 is an enlarged cross-sectional view illustrating the layered structure of the first metal part in the secondary battery packaging material according to the present invention.
[51]
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 . Compared to the second layer 120 , the first layer 110 may be a layer provided relatively adjacent to the inner space of the exterior material 10 . In this case, the thermal conductivity of the first layer 110 may be greater than that of the second layer 120 .
[52]
3 is an enlarged cross-sectional view illustrating the layered structure of the second metal part in the secondary battery packaging material according to the present invention.
[53]
Similar to the case of the first metal part 100 , according to another embodiment of the present invention, the second metal part 200 may also have a layered structure. That is, the second metal part 200 may include a third layer 210 and a fourth layer 220 . Compared to the fourth layer 220 , the third layer 210 may be a layer provided relatively adjacent to the inner space of the exterior material 10 . In this case, the thermal conductivity of the third layer 210 may be greater than that of the fourth layer 220 .
[54]
As described above, when the temperature inside the secondary battery rises, in order to rapidly dissipate the heat inside the secondary battery to the outside, it is necessary to more rapidly occur in a region adjacent to the electrode assembly where heat is generated. Accordingly, when the thermal conductivity of the first layer 110 is greater than the thermal conductivity of the second layer 120 , heat is rapidly transferred to the outside through the first layer 110 adjacent to the electrode assembly compared to the second layer 120 . can be emitted. Likewise, even when the thermal conductivity of the third layer 210 is greater than the thermal conductivity of the fourth layer 220 , heat is transferred to the outside through the third layer 210 relatively adjacent to the electrode assembly compared to the fourth layer 220 . can be released quickly.
[55]
Meanwhile, 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. Also, 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.
[56]
At this time, as described above, the thermal conductivity of the first layer 110 may be greater than the thermal conductivity of the second layer 120, and the thermal conductivity of the third layer 210 may be greater than the thermal conductivity of the fourth layer 220, The thermal conductivity of the first material may be greater than that of the second material, and the thermal conductivity of the third material may be greater than the thermal conductivity of the fourth material.
[57]
Meanwhile, for example, the first material and the third material may include copper, and the second material and the fourth material may include aluminum. Alternatively, the first material and the third material may be made of copper, and the second material and the fourth material may be made of aluminum.
[58]
Copper has about 1.5 times greater thermal conductivity than aluminum. Accordingly, the third layer 210 provided relatively adjacent to the electrode assembly compared to the first layer 110 and the fourth layer 220 provided relatively adjacent to the electrode assembly compared to the second layer 120 is When copper is included or made of copper, heat inside the secondary battery may be discharged to the outside more quickly.
[59]
Meanwhile, the first metal part 100 or the second metal part 200 according to the present invention may be made of a clad material.
[60]
The clad is a material capable of exhibiting the advantages of each metal by bonding two or more metals. In the clad, bonding between two or more metals may be achieved by rolling. When the first layer 110 and the second layer 120 of the first metal part 100 are copper and aluminum, respectively, the first metal part 100 made of a clad material is formed by rolling bonding between copper and aluminum. can be manufactured. Similarly, when the third layer 210 and the fourth layer 220 of the second metal part 200 are copper and aluminum, respectively, the second metal part made of a clad material due to rolling bonding between copper and aluminum. (200) can be prepared. This can also be applied to the case where the first to fourth layers are made of other metals.
[61]
[62]
Meanwhile, the secondary battery according to the present invention may include an electrode assembly having a structure in which electrodes and a separator are alternately disposed, and a secondary battery casing for accommodating the electrode assembly. The description of the exterior material for the secondary battery is replaced with the above-mentioned content.
[63]
[64]
In the above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is described below with the technical idea of ​​the present invention by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various implementations are possible within the equivalent scope of the claims.
Claims
[Claim 1]
An exterior material for a secondary battery having an internal space, comprising: a first metal part; a second metal part spaced apart from the first metal part; and a first adhesive part provided between the first metal part and the second metal part and being respectively adhered to the first metal part and the second metal part; Including, wherein the first metal part is provided closer to the inner space than the second metal part, and the thermal conductivity of the first metal part is greater than the thermal conductivity of the second metal part.
[Claim 2]
The packaging material for a secondary battery as set forth in claim 1 , wherein a flame retardant material is mixed in the first adhesive part.
[Claim 3]
The packaging material for a secondary battery of claim 1 , wherein the first metal part or the second metal part is made of a clad material.
[Claim 4]
The packaging material of claim 2 , wherein the flame retardant material includes at least one of a phosphorus compound, a nitrogen compound, a halogen compound, an antimony compound, a molybdenum compound, a zinc borate compound, and a metal hydroxide.
[Claim 5]
The method according to claim 1, It is provided to be spaced apart from the first metal portion in the inner space direction, the insulating portion having electrical insulation; and a second adhesive part provided between the first metal part and the insulating part, and being respectively adhered to the first metal part and the insulating part; A secondary battery exterior material further comprising a.
[Claim 6]
The method according to claim 1, wherein the first metal portion, a first layer including a first material; and a second layer comprising a second material; Including, wherein the first layer is provided closer to the inner space than the second layer, and the thermal conductivity of the first layer is greater than the thermal conductivity of the second layer.
[Claim 7]
The method according to claim 1, wherein the second metal portion, a third layer including a third material; and a fourth layer comprising a fourth material; Including, wherein the third layer is provided closer to the inner space than the fourth layer, and the thermal conductivity of the third layer is greater than the thermal conductivity of the fourth layer.
[Claim 8]
The packaging material for a secondary battery of claim 6 , wherein the first material includes copper and the second material includes aluminum.
[Claim 9]
The packaging material for a secondary battery of claim 7 , wherein the third material includes copper, and the fourth material includes aluminum.
[Claim 10]
The packaging material for a secondary battery of claim 5 , wherein the first adhesive part and the second adhesive part include acid modified polypropylene (PPa), and the insulating part includes cast polypropylene (CPP).
[Claim 11]
The method according to claim 1, A first outer surface portion laminated on the outer surface of the second metal portion; and a second outer surface portion laminated on an outer surface of the first outer surface portion; and, wherein the first outer surface portion includes O-nylon (oriented nylon), and the second outer surface portion includes polyethylene terephthalate (PET).
[Claim 12]
electrode assembly; and a secondary battery packaging material according to claim 1 for accommodating the electrode assembly; A secondary battery comprising a.