Title of the invention: Packaging for flexible secondary battery and flexible secondary battery including the same
Technical field
[One]
The present invention relates to a flexible secondary battery packaging and a flexible secondary battery including the same, and more particularly, a packaging for a flexible secondary battery capable of preventing the occurrence of cracks due to tensile stress and compressive stress occurring in a repeated bending environment, and It relates to a flexible secondary battery.
[2]
This application claims priority based on Korean Application No. 10-2018-0037437 filed on March 30, 2018, and all contents disclosed in the specification of the application are incorporated in this application.
Background
[3]
As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and among such secondary batteries, many studies have been conducted on lithium secondary batteries with high energy density and discharge voltage, and have been widely commercialized. Is being used.
[4]
Secondary batteries are largely classified into cylindrical batteries, prismatic batteries and pouch-type batteries according to the shape of the battery case containing the positive electrode/separator/cathode electrode assembly. Is increasing significantly.
[5]
In general, for prismatic batteries, a jelly-roll or stacked positive/separator/cathode electrode assembly is placed in a metallic case, and the open top is covered with a top cap. It is produced in the process of doing.
[6]
In addition, the pouch-type battery is manufactured in a structure in which the outer peripheral surface is heat-sealed and sealed while the electrode assembly is accommodated in a pouch case of a laminate sheet.
[7]
On the other hand, as devices to which the above batteries are applied are diversified, batteries are also manufactured in various shapes out of a rectangular parallelepiped shape.
[8]
For example, in the case of a smart phone, the side can be curved to improve the gripping feeling, and when a flexible display is applied, it can be bent or bent. Accordingly, a curved battery or a battery of a flexible structure Research on the topic continues.
[9]
Packaging for protecting such a flexible battery requires both flexibility and moisture barrier properties. When a tube packaging made of a general polymer material is used, moisture or air can penetrate through the micropores of the polymer, and contaminate the electrolyte inside the battery, thereby deteriorating battery performance.
[10]
In order to overcome this problem, packaging formed of a metal foil layer may be used. When the battery is bent due to the stiff properties of the metal foil layer itself, the battery is not completely bent, but the surface of the metal foil layer is bent or wrinkled. There may be problems such as tearing the metal foil layer.
Detailed description of the invention
Technical challenge
[11]
Therefore, the problem to be solved by the present invention is a flexible secondary battery packaging that enables stable driving without breaking the packaging even in a repetitive bending environment, and can prevent cracks due to tensile stress and compressive stress, and a flexible secondary battery including the same. It is to provide a battery.
Means of solving the task
[12]
According to an aspect of the present invention, a packaging for a flexible secondary battery of the following embodiments is provided.
[13]
The first embodiment,
[14]
A first polymer resin layer; A barrier layer formed on the first polymer resin layer and blocking moisture and gas; And a second polymer resin layer formed on the barrier layer, wherein the barrier layer further includes a parylene layer composed of parylene on at least one surface, and the thickness of the parylene layer is 0.1 μm to 2.5 It relates to a flexible secondary battery packaging of ㎛.
[15]
The second embodiment, in the first embodiment,
[16]
The parylene relates to packaging for a flexible secondary battery of parylene-C.
[17]
In the third embodiment, in the first embodiment or the second embodiment,
[18]
The first polymer resin layer is a polyolefin resin, a polyester resin, a polyamide resin, a polyethyleneimine resin, a polyether resin, a cyanoacrylate resin, an organic titanium resin, a polyurethane resin, a polyether. It relates to a packaging for a flexible secondary battery comprising any one selected from the group consisting of a urethane resin, an epoxy resin, an imide resin, an isocyanate resin, and a silicone resin, or a mixture of two or more of them.
[19]
In the fourth embodiment, in any one of the first to third embodiments,
[20]
The barrier layer relates to a packaging for a flexible secondary battery comprising a metal thin film layer, an inorganic material layer, or a composite of a polymer and metal particles.
[21]
In the fifth embodiment, in the fourth embodiment,
[22]
The metal thin film layer relates to a packaging for a flexible secondary battery comprising any one selected from the group consisting of iron, carbon, chromium, manganese, nickel, copper, silver, gold, and aluminum, or an alloy of two or more of them.
[23]
In the sixth embodiment, in any one of the first to fifth embodiments,
[24]
The second polymer resin layer is a polyolefin resin, a polyester resin, a polyamide resin, a polyethyleneimine resin, a polyether resin, a cyanoacrylate resin, an organic titanium resin, a polyurethane resin, a polyether. It relates to a packaging for a flexible secondary battery comprising any one selected from the group consisting of a urethane resin, an epoxy resin, an imide resin, an isocyanate resin, and a silicone resin, or a mixture of two or more of them.
[25]
In the seventh embodiment, in any one of the first to sixth embodiments,
[26]
The thickness of the parylene layer relates to a packaging for a flexible secondary battery having a thickness of 2 μm to 2.5 μm.
[27]
In the eighth embodiment, in any one of the first to seventh embodiments,
[28]
It relates to a packaging for a flexible secondary battery in which an adhesive layer is further formed on at least one of a surface in contact with the barrier layer and the first polymer resin layer and a surface in contact with the barrier layer and the second polymer resin layer.
[29]
In the ninth embodiment, in any one of the first to eighth embodiments,
[30]
The rate of change in moisture permeability before and after repeating the 5R bending test 100 times for the flexible secondary battery packaging is 1 to 15%,
[31]
It relates to a packaging for a flexible secondary battery in which the rate of change of the moisture permeability is calculated by the following equation.
[32]
Permeability change rate (%) = [(Moisture permeability after bending-moisture permeability before bending)/(permeability before bending)]×100
[33]
Meanwhile, according to another aspect of the present invention, a flexible secondary battery of the following embodiment is provided.
[34]
The tenth embodiment,
[35]
A flexible secondary battery comprising a flexible electrode assembly and a packaging containing the flexible electrode assembly, wherein the packaging relates to a flexible secondary battery that is a flexible secondary battery packaging according to any one of the first to ninth embodiments.
Effects of the Invention
[36]
According to an embodiment of the present invention, by including a barrier layer that blocks moisture and gas, it is possible to prevent deterioration of the battery performance by preventing contamination of the electrolyte existing inside the flexible secondary battery, and mechanically Can maintain strength.
[37]
In addition, since it further includes a parylene layer that can reinforce the mechanical stiffness and flexibility of the barrier layer, moisture penetration prevention can be further strengthened, and the flexibility of the flexible secondary battery can be further strengthened.
Brief description of the drawing
[38]
The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the contents of the above-described invention, so the present invention is limited to the matters described in such drawings. It is limited and should not be interpreted.
[39]
1 is a schematic cross-sectional view of a packaging for a flexible secondary battery according to a conventional technique.
[40]
2 is a schematic cross-sectional view of a packaging for a flexible secondary battery according to an embodiment of the present invention.
[41]
3 is a schematic cross-sectional view of a packaging for a flexible secondary battery according to another conventional technology.
[42]
4 is a schematic cross-sectional view of a packaging for a flexible secondary battery according to another embodiment of the present invention.
[43]
5 is a schematic cross-sectional view of a packaging for a flexible secondary battery according to another conventional technology.
[44]
6 is a schematic cross-sectional view of a packaging for a flexible secondary battery according to another embodiment of the present invention.
[45]
7 is a photograph of the appearance of the packaging for a flexible secondary battery according to Example 1 after a bending experiment.
[46]
8 is a photograph of the appearance after a bending experiment of the packaging for a flexible secondary battery of Comparative Example 1.
[47]
9 is a photograph of the appearance of the packaging for a flexible secondary battery of Comparative Example 2 after a bending experiment.
[48]
10 is a photograph of the appearance of the packaging for a flexible secondary battery of Comparative Example 3 after a bending experiment.
Mode for carrying out the invention
[49]
Hereinafter, the present invention will be described in detail with reference to the drawings. The terms or words used in the present specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of ​​the present invention based on the principle that there is.
[50]
Accordingly, the embodiments described in the present specification and the configurations described in the drawings are only the most preferred embodiments of the present invention, and do not represent all the technical ideas of the present invention, and thus various It should be understood that there may be equivalents and variations.
[51]
[52]
1, 3, and 5 are views schematically showing a cross-section of a packaging for a flexible secondary battery according to the prior art, and FIGS. 2, 4 and 6 are diagrams schematically showing a cross-section of a packaging for a flexible secondary battery according to an embodiment of the present invention. .
[53]
1, 3, and 5, the packaging for a flexible secondary battery according to the prior art includes a first polymer resin layer 11; A barrier layer 12 formed on the first polymer resin layer 11 to block moisture and gas; And a second polymer resin layer 13 formed on the barrier layer 12, and optionally, the barrier layer 12 may be formed in two layers, or the barrier layer 12 and the second polymer An adhesive layer 14 may be further interposed between the resin layers 13.
[54]
Referring to Figures 2, 4 and 6, the flexible secondary battery packaging 100 according to an aspect of the present invention, a first polymer resin layer 110; A barrier layer 120 formed on the first polymer resin layer 110 and blocking moisture and gas; And a second polymer resin layer 130 formed on the barrier layer 120, wherein a parylene layer 121 made of parylene is formed on at least one surface of the barrier layer 120 It characterized in that it further includes. In addition, an adhesive layer 140 may be further included between the barrier layer 120 and the second polymer resin layer 130.
[55]
Hereinafter, each layer will be described in detail.
[56]
The packaging 100 for a flexible secondary battery according to the present invention includes a barrier layer 120 that blocks moisture and gas, thereby preventing contamination of the electrolyte present in the flexible secondary battery, thereby preventing deterioration of battery performance, The mechanical strength of the flexible secondary battery can be maintained.
[57]
Furthermore, since it further includes a parylene layer 121 that can reinforce the mechanical rigidity and flexibility of the barrier layer 120, it is possible to further enhance prevention of moisture penetration, and further enhance the flexibility of the flexible secondary battery.
[58]
Conventionally, as a protective layer to prevent cracking of the barrier layer, a material such as PET or nylon was attached to one surface of the barrier layer, but it was difficult to prevent other cracks from occurring due to stress in a repeated bending situation. There was a problem in that the battery performance was deteriorated due to moisture penetration. However, in the present invention, it is possible to compensate for this problem by further including the parylene layer 121 on at least one surface of the barrier layer 120.
[59]
Here, the thickness of the parylene layer 121 may be 0.1 µm to 2.5 µm, specifically 0.1 µm to 2 µm, or 0.5 µm to 2 µm, or 2 µm to 2.5 µm, exceeding the numerical range. If it is, it is not preferable because the crystallinity of parylene is improved and it becomes brittle. If it is less than the above numerical range, the purpose of forming the parylene layer cannot be achieved, which is not preferable.
[60]
In addition, the parylene constituting the parylene layer 121 is, parylene-N (parylene-N), parylene-C (parylene-C), parylene-D (parylene-D), and parylene. It may be parylene-HT or the like, and among them, parylene-C having the lowest gas permeability is most preferred.
[61]
In this case, the parylene layer may be formed by a vapor deposition method using a monomer such as p-xylene polymerizable with parylene as a polymer material. Specifically, the step of vaporizing parylene dimer powder (p-xylene, etc.) to generate a gaseous parylene dimer; Pyrolyzing the gaseous dimer to produce a parylene monomer; And supplying the parylene monomer into the deposition chamber to deposit a polymer on the object to be coated in the deposition chamber to form a parylene layer, which is a parylene polymer film.
[62]
According to an embodiment of the present invention, in the evaporation step, the parylene dimer powder is heated to a temperature of 105° C. or higher, or approximately 150° C. under a vacuum of, for example, 10 −3 to 1 torr to melt the parylene dimer. It can be sublimated into a gaseous state without being able to. Thereafter, in the pyrolysis step, the parylene dimer introduced through the vaporization step is pyrolyzed to generate a parylene monomer (such as a highly reactive p-xylene radical as an intermediate product). Specifically, the parylene dimer may be heated to approximately 650° C. or higher for a pyrolysis reaction to obtain a high parylene monomer yield. In the deposition step, a parylene layer, which is a parylene polymer film, may be formed by depositing a parylene monomer introduced through the pyrolysis step on the object to be coated at room temperature and vacuum (for example, at a level of 0.1 to 2 torr).
[63]
According to the present invention, the first polymer resin layer 110 serves to be adhered to the electrode assembly accommodated in the packaging, and is a polyolefin resin, a polyester resin, a polyamide resin, a polyethyleneimine Any selected from the group consisting of resin, polyether resin, cyanoacrylate resin, organic titanium resin, polyurethane resin, polyether urethane resin, epoxy resin, imide resin, isocyanate resin, and silicone resin One or a mixture of two or more of them may be used, and non-stretched polypropylene (CPP) may be preferably used.
[64]
In this case, the first polymer resin layer 110 may function as a heat shrink tube layer. Heat-shrinkable tubes are tubes that shrink when heated. They tightly wrap terminals or materials of different shapes or sizes. They are usually made of polymer resin and are used for insulation or other purposes. Since such heat shrinkable tubes are commercially available heat shrinkable tubes having various materials and shapes, those suitable for the purpose of the present invention can be easily obtained and used. At this time, in order not to cause thermal damage to the secondary battery, it is necessary to lower the temperature of the shrinkage processing, and in general, it is required to complete the shrinkage at a temperature of 70°C to 200°C or 70°C to 120°C.
[65]
In addition, the thickness of the first polymer resin layer 110 is preferably about 15 to 500 μm. Regarding the thickness of the first polymer resin layer 110, the minimum thickness should be 15 μm or more to maintain the adhesive strength to the sealing material, and 500 μm or less in consideration of the capacity per volume of the battery.
[66]
Meanwhile, the barrier layer 120 may be a metal thin film layer, an inorganic material layer, or a layer made of a composite of a polymer and metal particles.
[67]
In this case, the metal thin film layer may be made of any one selected from the group consisting of iron, carbon, chromium, manganese, nickel, copper, silver, gold, and aluminum, or two or more of them.
[68]
In addition, the inorganic material layer is a layer including inorganic particles such as SiO 2 , Al 2 O 3 , MgO, BaTiO 3 , ZrO 2 and ZnO, and the average particle diameter of the inorganic material particles may be 1 nm to 5 μm. By including the inorganic particles, it is possible to further improve the insulation effect inside the battery, and it is possible to suppress the penetration of moisture into the battery to minimize contamination of the electrolyte component inside the battery, thereby preventing degradation of battery performance. .
[69]
In addition, in the composite of the polymer and metal particles, the polymer is high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene, polyethylene terephthalate, polybutyleneterephthalate, polyester ( polyester), polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, It may be formed of any one selected from the group consisting of polyphenylenesulfide and polyethylenenaphthalate, or a mixture of two or more of them. In addition, the metal particles may be made of any one selected from the group consisting of iron, carbon, chromium, manganese, nickel, copper, silver, gold, and aluminum, or an alloy of two or more of them.
[70]
The thickness of the barrier layer 120 may be 1 to 30 µm, preferably 3 to 20 µm. If the numerical range is satisfied, moisture as a barrier layer can be blocked and at the same time, due to external stimulation. It can prevent cracking.
[71]
In addition, the barrier layer 120 may be formed as one layer between the first polymer resin layer 110 and the second polymer resin layer 130 or may be formed as two or more layers.
[72]
Meanwhile, the second polymer resin layer 130 is a material capable of preventing cracks in the barrier layer 120, and includes polyolefin resins, polyester resins, polyamide resins, polyethyleneimine resins, and polyether resins. Any one selected from the group consisting of resins, cyanoacrylate resins, organic titanium resins, polyurethane resins, polyether urethane resins, epoxy resins, imide resins, isocyanate resins and silicone resins, or 2 of them It may consist of a mixture of more than one species, and preferably nylon resin or PET may be used.
[73]
In addition, the thickness of the second polymer resin layer 130 is preferably about 5 to 50 μm. The second polymer resin layer 130 protects the outside of the packaging material or is elastically restored when deformed to maintain the shape of the battery. If it is less than 5 µm, it cannot maintain rigidity, and if it is 50 µm or more, the capacity per volume of the battery This may decrease, which is not desirable.
[74]
On the other hand, the barrier layer 120 of the present application further including a parylene layer 121, the adhesive layer 140 on the surface in contact with the first polymer resin layer 110 or the second polymer resin layer 130 Since it may be formed further, adhesion between the first and second polymer resin layers 110 and 130 and the barrier layer 120 may be further improved. Although the adhesive layer 140 is interposed between the barrier layer 120 and the second polymer resin layer 130 in FIG. 6, the adhesive layer may be interposed between the parylene layer 121 and the first polymer resin layer 110. May be. In addition, the adhesive layer 140 may be interposed both between the parylene layer 121 and the first polymer resin layer 110 and between the barrier layer 120 and the second polymer resin layer 130.
[75]
As such an adhesive layer, it may be formed using a commonly used adhesive, and for example, a polyacrylate adhesive may be formed by a coating method such as casting.
[76]
According to an embodiment of the present invention, the packaging for a flexible secondary battery further includes a parylene layer capable of reinforcing mechanical stiffness and flexibility of the barrier layer, and thus moisture penetration prevention properties are further enhanced.
[77]
The excellent moisture penetration prevention characteristics of the flexible secondary battery packaging can be confirmed by the rate of change in moisture permeability before and after repeating the 5R bending test 100 times. The moisture permeability change rate before and after repeating the 5R bending test of the packaging for the flexible secondary battery 100 times may be 1 to 15%, or 5 to 15%, or 5.6 to 14.8%, or 5.6 to 9.2%. When the change in the moisture permeability satisfies this range, the packaging for the flexible secondary battery has excellent mechanical stiffness and flexibility, so that almost no cracks occur on the packaging surface even after 100 bending tests, indicating an excellent moisture penetration prevention effect. it means.
[78]
At this time, the 5R bending test is a test in which the packaging for a flexible secondary battery is bent along the circumference of the bar using a bar having a circular cross section of 5 mm, and then unfolded again as one time and repeated a predetermined number of times.
[79]
The moisture permeability change rate is calculated by the following equation.
[80]
Permeability change rate (%) = [(Moisture permeability after bending-moisture permeability before bending)/(permeability before bending)]×100
[81]
[82]
On the other hand, a flexible secondary battery according to another aspect of the present invention includes a flexible electrode assembly and a packaging containing the flexible electrode assembly, and the packaging is a packaging for a flexible secondary battery according to the present invention. .
[83]
In the present invention, the flexible electrode assembly may be configured in a form in which an anode and a cathode are disposed with a separator therebetween. In this case, the flexible electrode assembly may have a structure in which one positive electrode and one negative electrode are wound with a separator therebetween, or a structure in which a plurality of positive electrodes and a plurality of negative electrodes are stacked with the separator therebetween. In addition, the flexible electrode assembly may be a flexible electrode assembly including an internal electrode, a separator, and an external electrode.
[84]
[85]
Hereinafter, examples will be described in detail to illustrate the present invention in detail. However, the embodiments according to the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art.
[86]
[87]
Example 1
[88]
A 20 μm-thick non-stretched polypropylene (CPP) film was prepared as a first polymer resin layer, and a 2 μm-thick polyacrylate-based adhesive was cast on the non-stretched polypropylene (CPP) film by a casting method. After coating to form an adhesive layer, an aluminum (Al) foil having a thickness of 15 μm was attached as a barrier layer. Thereafter, a 2 μm-thick parylene layer (parylene-C) was formed on the aluminum foil using a deposition chamber. At this time, the parylene layer is loaded with p-xylene dimer in a vaporizer of a deposition chamber, vaporized at 150°C and 1 torr to generate parylene dimer, and the gaseous dimer is pyrolyzed at 680°C and 0.5 torr to paryl. To generate a ren monomer, it was formed through a vapor deposition step at 25° C. and 0.1 torr for 20 minutes. Thereafter, a 2 μm-thick polyacrylate-based adhesive casting method was applied on the parylene layer to form an adhesive layer, and then a 25 μm-thick nylon film was attached to the second polymer resin layer to prepare a packaging for a flexible secondary battery. I did.
[89]
[90]
Example 2
[91]
A packaging for a flexible secondary battery was manufactured in the same manner as in Example 1, except that a 0.1 μm-thick parylene layer was formed through a vapor deposition step for 1 minute.
[92]
[93]
Example 3
[94]
A packaging for a flexible secondary battery was manufactured in the same manner as in Example 1, except that a 2.5 μm-thick parylene layer was formed through a vapor deposition step for 25 minutes.
[95]
[96]
Comparative Example 1
[97]
A packaging for a flexible secondary battery was manufactured in the same manner as in Example 1, except that a parylene layer was not formed.
[98]
[99]
Comparative Example 2
[100]
A packaging for a flexible secondary battery was manufactured in the same manner as in Example 1, except that a parylene layer having a thickness of 0.05 μm was formed through a vapor deposition step for 30 seconds.
[101]
[102]
Comparative Example 3
[103]
A packaging for a flexible secondary battery was manufactured in the same manner as in Example 1, except that a 5 μm-thick parylene layer was formed through a vapor deposition step for 50 minutes.
[104]
[105]
Property evaluation
[106]
Evaluation of water vapor transmission rate (WVTR) before and after bending
[107]
(1) Evaluation of moisture permeability before bending
[108]
After cutting the packaging for flexible secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 3 into a size of 108 mm×108 mm, each of them installed inside the moisture permeability tester (manufacturer: Sejin Testing Technology, model name: SJTM-014) I did. Then, dry nitrogen gas without water vapor was introduced into one side of the packaging for the flexible secondary battery, and water vapor was introduced into the other side. In this case, the two spaces into which the gases are introduced are isolated from each other so that the gases flowing into both sides of the flexible secondary battery packaging are not mixed. Meanwhile, during the experiment, the temperature was set to 38° C. and the humidity was set to 100% RH and maintained. And for 24 hours, the amount of water vapor was measured on the one side of which dry nitrogen gas was introduced using a humidity sensor. The amount of water vapor was divided by the area of ​​one side, and the amount of water vapor per unit area that passed through the pouch film for 24 hours was derived, and this was evaluated as a moisture permeability (WVRT). The results are shown in Table 1.
[109]
[110]
(2) Evaluation of moisture permeability after bending
[111]
After repeating the 5R bending test 100 times for the packaging for flexible secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 3, the moisture permeability was evaluated again under the above-described conditions. The results are shown in Table 1. Here, the 5R bending test is a test in which the packaging for a flexible secondary battery is bent along the circumference of the bar using a bar having a circular cross section of 5 mm, and then unfolded again as one time and repeated a predetermined number of times.
[112]
[113]
(3) Permeability change rate
[114]
The moisture permeability change rate was calculated by the following equation, and is shown in Table 1.
[115]
Permeability change rate (%) = [(Moisture permeability after bending-moisture permeability before bending)/(permeability before bending)]×100
[116]
[117]
[Table 1]
Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3
Water permeability before bending (g/m 2 ·day) 0.00392 0.00384 0.00372 0.00383 0.00386 0.00394
Moisture permeability after bending (g/m 2 ·day) 0.00428 0.00441 0.00393 0.00628 0.00621 0.00647
Permeability change rate (%) 9.2 14.8 5.6 64.0 60.9 64.2
[118]
Referring to Table 1, in the packaging for flexible secondary batteries of Examples 1 to 3, after 100 bending tests, the rate of change in moisture permeability before and after bending was about 15% or less, but the packaging for flexible secondary batteries of Comparative Examples 1 to 3 was bent. It can be seen that the rate of change of moisture permeability before and after was very large, over 60%. That is, the packaging for flexible secondary batteries of Examples 1 to 3 provided with a parylene layer at an optimum thickness, thereby reinforcing the mechanical stiffness and flexibility of the barrier layer, and there was almost no cracking on the packaging surface after the bending test 100 times. Water penetration prevention could be further strengthened. However, in the case of Comparative Examples 1 to 3, when there is no pyrene layer or is out of the optimum thickness range, a number of cracks are generated on the packaging surface after the bending test, thereby remarkably increasing the moisture permeability.
[119]
[120]
(4) Observation of appearance after bending
[121]
A flexible secondary battery was prepared by using the packaging for flexible secondary batteries of Example 1 and Comparative Examples 1 to 3, and the results of observing the appearance after 10 5R bending tests were performed are shown in FIGS. 7 to 10.
[122]
At this time, the flexible secondary battery was manufactured as follows.
[123]
A slurry consisting of Graphite/Denka black/PVdF (=70/5/25wt%) was prepared on a 250 μm Cu wire, and then coated to prepare a wire-type electrode with a graphite electrode layer formed thereon. Four prepared wire electrodes were wound to form an open structure internal electrode part in which the lithium ion supply core part could exist because the inside was empty in the form of a spring, and a separator was wound around it to form a separation layer. After forming LiCoO 2 /Denka black/PVdF (=85/5/15 wt%) on the Al foil , coating the conductive layer slurry (Denka black/PVdF=40/60 wt%) on the electrode layer while coating the conductive layer slurry A sheet-shaped external electrode was prepared by placing a nonwoven fabric as a porous polymer substrate thereon and drying. The prepared sheet-shaped external electrode was cut to have a width of 2 mm, and then a sheet-shaped external electrode was wound around the internal electrode/separation layer to prepare an electrode assembly.
[124]
After surrounding the flexible secondary battery packaging of Example 1 and Comparative Examples 1 to 3 on the outer surface of the prepared electrode structure, the first polymer resin layer was bonded by heating and pressing for 3 seconds at 150° C. and 50 kg. Keep the inlet unsealed). Using a non-sealed part, a non-aqueous electrolyte (1M LiPF 6 , EC/PC/DEC) was injected into the center of the open structure of the inner electrode support using a syringe to form a lithium ion supply core part, and the unsealed part was completely Sealed. Thereafter, by heating at a temperature of 130° C. for 1 minute, the second polymer resin layer serving as a heat-shrink tube was shrunk and tightly sealed to prepare a flexible secondary battery.
[125]
Referring to FIG. 7, it was found that the flexible secondary battery manufactured by using the packaging for the flexible secondary battery of Example 1 did not generate any cracks on the surface even after the 5R bending test 10 times, indicating excellent flexibility. On the other hand, referring to Figs. 8 to 10, it was confirmed that in the flexible secondary battery using the packaging for flexible secondary batteries of Comparative Examples 1 to 3, the flexibility of the packaging was poor, and a considerable crack occurred on the surface after 10 5R bending tests.
[126]
[127]
The above description is merely illustrative of the technical idea of ​​the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of ​​the present invention, but to explain the technical idea, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.
[128]
[Explanation of code]
[129]
10, 100: packaging
[130]
11, 110: first polymer resin layer
[131]
12, 120: barrier layer
[132]
121: parylene layer
[133]
13, 130: second polymer resin layer
[134]
14, 140: adhesive layer
Claims
[Claim 1]
A first polymer resin layer; A barrier layer formed on the first polymer resin layer and blocking moisture and gas; And a second polymer resin layer formed on the barrier layer, further comprising a parylene layer made of parylene on at least one surface of the barrier layer, wherein the parylene layer has a thickness of 0.1 μm to 2.5 μm Packaging for flexible secondary batteries.
[Claim 2]
The packaging for a flexible secondary battery according to claim 1, wherein the parylene is parylene-C.
[Claim 3]
The method of claim 1, wherein the first polymer resin layer is a polyolefin resin, a polyester resin, a polyamide resin, a polyethyleneimine resin, a polyether resin, a cyanoacrylate resin, an organotitanium resin, and a poly Packaging for a flexible secondary battery comprising any one selected from the group consisting of urethane resin, polyether urethane resin, epoxy resin, imide resin, isocyanate resin, and silicone resin, or a mixture of two or more of them.
[Claim 4]
The packaging for a flexible secondary battery according to claim 1, wherein the barrier layer is a metal thin film layer, an inorganic material layer, or a layer made of a composite of a polymer and metal particles.
[Claim 5]
The packaging for a flexible secondary battery according to claim 4, wherein the metal thin film layer is made of any one selected from the group consisting of iron, carbon, chromium, manganese, nickel, copper, silver, gold, and aluminum, or two or more alloys thereof.
[Claim 6]
The method of claim 1, wherein the second polymer resin layer is a polyolefin resin, a polyester resin, a polyamide resin, a polyethyleneimine resin, a polyether resin, a cyano acrylate resin, an organotitanium resin, and a poly Packaging for a flexible secondary battery comprising any one selected from the group consisting of urethane resin, polyether urethane resin, epoxy resin, imide resin, isocyanate resin, and silicone resin, or a mixture of two or more of them.
[Claim 7]
The packaging for a flexible secondary battery according to claim 1, wherein the parylene layer has a thickness of 2 µm to 2.5 µm.
[Claim 8]
The packaging for a flexible secondary battery according to claim 1, wherein an adhesive layer is further formed on at least one of a contact surface between the barrier layer and the first polymer resin layer and a surface contact between the barrier layer and the second polymer resin layer.
[Claim 9]
The packaging for a flexible secondary battery according to claim 1, wherein the rate of change in moisture permeability before and after repeating the 5R bending test 100 times is 1 to 15%, and the rate of change in moisture permeability is calculated by the following equation. Permeability change rate (%) = [(Moisture permeability after bending-moisture permeability before bending)/(permeability before bending)]×100
[Claim 10]
A flexible secondary battery comprising a flexible electrode assembly and a packaging containing the flexible electrode assembly, wherein the packaging is a flexible secondary battery packaging according to any one of claims 1 to 9.