Aluminum-plastic film for high and low temperature resistant solid-state battery

Abstract

The invention discloses an aluminum-plastic film for a high and low temperature resistant solid-state battery. The aluminum-plastic film is sequentially composed of a first nylon layer, a first adhesive layer, a second nylon layer, a second adhesive layer, an aluminum foil layer, a third adhesive layer, a third nylon layer, a fourth adhesive layer and a fourth nylon layer from inside to outside. The first nylon layer adopts a copolymer casting film of PA6, PA66 and PA1010 as a heat sealing layer, so that the brittleness of a material in an extremely low-temperature environment can be avoided, and the low-temperature resistance of a finished product film is improved. The second nylon layer and the third nylon layer adopt PA6 biaxially oriented films as middle supporting layers, so that the stamping resistance of the finished aluminum-plastic film can be further improved. The fourth nylon layer adopts a PA66 biaxially oriented film as an outer protective layer, so that the high-temperature resistance of the finished aluminum-plastic film can be improved, and the problem of scalding in the heat sealing process is avoided. The barrier that a traditional aluminum plastic film is not resistant to low temperature and high temperature is broken through, and the application range is widened.

Description

Technical Field

[0001] This invention relates to aluminum-plastic film, and more particularly to an aluminum-plastic film for high and low temperature resistant solid-state batteries. Background Technology

[0002] Lithium-ion batteries, as an important sustainable new energy source, have been widely used in 3C products, electric vehicles, large-scale energy storage, and aerospace. Currently, commercially available lithium-ion batteries still use organic liquid electrolytes or gel electrolytes. The introduction of flammable and explosive organic liquids poses significant safety hazards to the battery system. Furthermore, the incompatibility of organic liquids with high-energy-density electrode materials such as metallic lithium limits the improvement of battery energy density. Therefore, replacing the liquid electrolyte with a solid-state electrolyte and developing solid-state batteries with high energy density, high safety, and long cycle life is the fundamental way to solve these problems.

[0003] With the development of solid-state lithium batteries, lithium battery packaging films have gradually gained market attention. Commonly used aluminum-plastic packaging films for lithium batteries mainly consist of three layers: an outer nylon layer, a middle aluminum foil layer, and an inner polypropylene film layer. However, for conventional aluminum-plastic films, nylon is often laminated with aluminum foil using adhesives, but due to the limited heat resistance of the adhesives, the aluminum-plastic film is prone to burns during heat sealing. Polypropylene mainly uses PP (polypropylene) copolymer composite films with different structures and aggregation states, but PP is prone to brittleness at low temperatures, thus adversely affecting heat sealing.

[0004] Therefore, solving the problems of the outer layer of aluminum-plastic film being intolerant to high temperatures and the inner layer being intolerant to low temperatures is a necessary way to extend the service life of soft-pack batteries. Summary of the Invention

[0005] The purpose of this invention is to overcome the existing defects and provide an aluminum-plastic film for solid-state batteries that is resistant to high and low temperatures, breaking through the barrier that traditional aluminum-plastic films are not resistant to low and high temperatures, and broadening their application scope.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A high- and low-temperature resistant aluminum-plastic film for solid-state batteries is composed of, from the inside out: a first nylon layer, a first adhesive layer, a second nylon layer, a second adhesive layer, an aluminum foil layer, a third adhesive layer, a third nylon layer, a fourth adhesive layer, and a fourth nylon layer.

[0008] Preferably, the first nylon layer is a cast film of a copolymer of PA6 (polycaprolactam), PA66 (polyhexamethylene adipamide), and PA1010 (polydecanoyl decylamine), composed of the following raw materials in parts by weight:

[0009] 90-95 parts of PA6, PA66 and PA1010 copolymer granules;

[0010] 1.5-3.5 parts of slip agent;

[0011] 1-2.5 parts antioxidant; and

[0012] 2.5-4 parts by weight of plasticizer;

[0013] The mass fractions of PA6, PA66 and PA1010 are 8–15, 7–15 and 0.5–3, respectively.

[0014] Preferably, the slip agent is erucamide or oleamide; the melting point of the PA6, PA66 and PA1010 copolymer granules is 160-170°C, and the melt index is 4-6 g / cm³. 3 .

[0015] Preferably, the thickness of the first nylon layer is 70 μm.

[0016] Preferably, the second nylon layer and the third nylon layer are made of PA6 biaxially oriented film, composed of the following raw materials in parts by weight:

[0017] 98-99.5 parts PA6 granules; and

[0018] 0.5-2 parts of antioxidant.

[0019] Preferably, the heat treatment temperature during the processing of the PA6 biaxially oriented film of the second nylon layer is 160-200°C, and the melting point of the film is 210-215°C.

[0020] The PA6 biaxially oriented film with the third nylon layer is heat-treated at 180-210°C during processing, and the film has a melting point of 220-225°C.

[0021] The thickness of the second nylon layer and the third nylon layer is 15 μm.

[0022] Preferably, the aluminum foil layer is made of 8021 soft aluminum foil or 8079 soft aluminum foil, with a thickness of 50 μm.

[0023] Preferably, the fourth nylon layer is made of PA66 biaxially oriented film, composed of the following raw materials in parts by weight:

[0024] 95-98 parts of PA66 granules;

[0025] 1-2.5 parts of slip agent;

[0026] 0.5-1 part antioxidant; and

[0027] 0.5-1.5 parts of plasticizer;

[0028] Preferably, the thickness of the fourth nylon layer is 20 μm; the melting point of the PA66 biaxially oriented film is 260–270 °C.

[0029] Preferably, the first adhesive layer, the second adhesive layer, the third adhesive layer and the fourth adhesive layer are polyurethane adhesives, and each has a thickness of 3 μm.

[0030] Compared with existing technologies, the beneficial effects of this invention are as follows: The first nylon layer, using a PA6, PA66, and PA1010 copolymer cast film as a heat-sealing layer, avoids material embrittlement under extreme low-temperature conditions, improving the low-temperature resistance of the finished film. The second and third nylon layers, using PA6 biaxially oriented film as intermediate support layers, further enhance the impact resistance of the finished aluminum-plastic film. The fourth nylon layer, using PA66 biaxially oriented film as an outer protective layer, improves the high-temperature resistance of the finished aluminum-plastic film, avoiding burns during the heat-sealing process. This overcomes the limitations of traditional aluminum-plastic films in terms of low and high temperature resistance, broadening their application range. Attached Figure Description

[0031] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0032] Figure 1 This is a schematic diagram of the structure of the aluminum-plastic film of the present invention;

[0033] Figure 2 This is a schematic diagram comparing the high-temperature resistance test results of the conventional sample and the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] like Figure 1 As shown, the aluminum-plastic film for high and low temperature resistant solid-state batteries of the present invention comprises, from the inside out: a first nylon layer, a first adhesive layer, a second nylon layer, a second adhesive layer, an aluminum foil layer, a third adhesive layer, a third nylon layer, a fourth adhesive layer, and a fourth nylon layer. Wherein,

[0036] The first nylon layer is a cast film made of a copolymer of PA6, PA66, and PA1010, composed of the following raw materials by weight: 90-95 parts of PA6, PA66, and PA1010 copolymer granules; 1.5-3.5 parts of slip agent; 1-2.5 parts of antioxidant; and 2.5-4 parts by weight of plasticizer. The mass percentages of PA6, PA66, and PA1010 are 8-15, 7-15, and 0.5-3, respectively. The slip agent is erucamide or oleamide; the melting point of the PA6, PA66, and PA1010 copolymer granules is 160-170℃, and the melt index is 4-6 g / cm³. 3 .

[0037] In this embodiment, the first nylon layer is a 70μm thick PA6, PA66 and PA1010 copolymer cast film, comprising 95 parts by weight of PA6, PA66 and PA1010 copolymer granules, 1.5 parts by weight of slip agent, 1 part by weight of antioxidant, and 2.5 parts by weight of plasticizer. The copolymer granules PA6, PA66 and PA1010 are present in parts by weight of 10, 8 and 1.5 respectively, and the slip agent is erucamide.

[0038] The second and third nylon layers are made of PA6 biaxially oriented film, composed of the following raw materials by weight: 98-99.5 parts PA6 granules; 0.5-2 parts antioxidant. The heat treatment temperature for the second nylon layer is 160-200℃, and the melting point of the film is 210-215℃; the heat treatment temperature for the third nylon layer is 180-210℃, and the melting point of the film is 220-225℃; the thickness of each of the second and third nylon layers is 15μm.

[0039] The aluminum foil layer uses 8021 soft aluminum foil or 8079 soft aluminum foil, with a thickness of 50μm.

[0040] In this embodiment, the second nylon layer is a 15μm thick biaxially oriented PA6 film, comprising 99 parts by weight of PA6 granules and 1 part by weight of antioxidant, with a heat treatment temperature of 180°C during film processing. The third nylon layer is a 15μm thick biaxially oriented PA6 film, comprising 98 parts by weight of PA6 granules and 2 parts by weight of antioxidant, with a heat treatment temperature of 200°C during film processing.

[0041] The fourth nylon layer is made of PA66 biaxially oriented film, composed of the following raw materials in parts by weight: 95-98 parts PA66 granules; 1-2.5 parts slip agent; 0.5-1 part antioxidant; and 0.5-1.5 parts plasticizer. The melting point of PA66 biaxially oriented film is 260-270℃.

[0042] In this embodiment, the fourth nylon layer is a 20μm thick PA66 biaxially oriented film, comprising 97 parts of PA66 granules, 1.5 parts by weight of slip agent, 1 part by weight of antioxidant, and 0.5 parts by weight of plasticizer.

[0043] The composite process is a dry composite process.

[0044] The first, second, third, and fourth adhesive layers are made of polyurethane adhesive, each with a thickness of 3 μm.

[0045] Comparative example:

[0046] A standard aluminum-plastic film has the following structure from the inside out: a heat-sealing layer, an adhesive layer, an aluminum foil layer, another adhesive layer, and a nylon layer. The heat-sealing layer is made of 70μm thick polypropylene cast film, the aluminum foil layer is made of 50μm thick 8021 flexible aluminum foil, the nylon layer is made of 15μm thick PA6 biaxially oriented film (composition and properties are the same as the third nylon layer), and the adhesive is a polyurethane adhesive. The lamination process is dry lamination.

[0047] A surface burn resistance test was conducted to compare the examples and conventional aluminum-plastic films.

[0048] For both the example and conventional aluminum-plastic film, prepare one 12mm × 24mm sample sheet with uniform thickness, free of creases and wrinkles. Fold the long side in half and heat seal it using a heat sealer. The heat sealing temperature is 215℃, the sealing blade width is 2mm, the heat sealing time is 3s, and the heat sealing pressure is 0.2MPa. Observe whether there is any adhesion when the sealing edge detaches from the sealing blade, and whether there is any damage or delamination at the sealing edge.

[0049] Test results are available Figure 2 The experimental results show that conventional aluminum-plastic film heat sealing results in burns, while the edge sealing in the example is intact.

[0050] Low-temperature resistance tests were conducted to compare the examples and the comparative examples.

[0051] Five samples of 12mm×24mm thickness with uniform thickness, no creases or wrinkles, were prepared for both the example and conventional aluminum-plastic film. They were placed at -30℃ for 24 hours, then removed and heat-sealed using a heat sealer at a temperature of 175℃, a sealing blade width of 10mm, a heat sealing time of 3s, and a heat sealing pressure of 0.2MPa. A 15mm wide strip was cut perpendicular to the sealing edge direction using a cutting blade, and the heat seal strength was measured.

[0052]

[0053] Table 1

[0054] The test results in Table 1 show that the aluminum-plastic film for high and low temperature solid-state batteries of the present invention exhibits higher heat-sealing strength than conventional aluminum-plastic film after being placed at low temperatures, demonstrating superior low-temperature resistance. This is because the use of PA (copolyamide) in the heat-sealing layer can effectively prevent the PP layer from becoming brittle and the heat-sealing strength from deteriorating in low-temperature environments, and prevent the PP thickness from being too low due to excessive extrusion during the heat-sealing process, thereby avoiding battery short circuits.

[0055] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An aluminum-plastic film for high and low temperature resistant solid-state batteries, characterized in that, From the inside out, it consists of: a first nylon layer, a first adhesive layer, a second nylon layer, a second adhesive layer, an aluminum foil layer, a third adhesive layer, a third nylon layer, a fourth adhesive layer, and a fourth nylon layer.

2. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 1, characterized in that, The first nylon layer is a cast film made of a copolymer of PA6, PA66 and PA1010, and is composed of the following raw materials in parts by weight: 90-95 parts of PA6, PA66 and PA1010 copolymer granules; 1.5-3.5 parts of slip agent; 1-2.5 parts antioxidant; and 2.5-4 parts by weight of plasticizer; The mass fractions of PA6, PA66 and PA1010 are 8–15, 7–15 and 0.5–3, respectively.

3. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 2, characterized in that, The slip agent is erucamide or oleamide; the melting point of the PA6, PA66 and PA1010 copolymer granules is 160-170℃, and the melt index is 4-6 g / cm³. 3 .

4. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 2, characterized in that, The thickness of the first nylon layer is 70 μm.

5. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 1, characterized in that, The second nylon layer and the third nylon layer are made of PA6 biaxially oriented film and are composed of the following raw materials in parts by weight: 98-99.5 parts PA6 granules; and 0.5-2 parts of antioxidant.

6. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 5, characterized in that, The heat treatment temperature during the processing of the PA6 biaxially oriented film with the second nylon layer is 160-200℃, and the melting point of the film is 210-215℃. The PA6 biaxially oriented film with the third nylon layer is heat-treated at 180-210°C during processing, and the film has a melting point of 220-225°C. The thickness of the second nylon layer and the third nylon layer is 15 μm.

7. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 1, characterized in that, The aluminum foil layer is made of 8021 soft aluminum foil or 8079 soft aluminum foil, with a thickness of 50μm.

8. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 1, characterized in that, The fourth nylon layer is made of PA66 biaxially oriented film, and is composed of the following raw materials in parts by weight: 95-98 parts of PA66 granules; 1-2.5 parts of slip agent; 0.5-1 part antioxidant; and 0.5-1.5 parts of plasticizer.

9. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 8, characterized in that, The thickness of the fourth nylon layer is 20 μm; the melting point of the PA66 biaxially oriented film is 260–270 °C.

10. The aluminum-plastic film for high and low temperature resistant solid-state batteries according to claim 1, characterized in that, The first adhesive layer, the second adhesive layer, the third adhesive layer and the fourth adhesive layer are made of polyurethane adhesive, and each has a thickness of 3μm.

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