Soft package aluminum plastic film and application thereof

Abstract

The invention belongs to the technical field of aluminum plastic films, and particularly relates to a soft package aluminum plastic film and application thereof. The soft package aluminum plastic film sequentially comprises a protective layer, a first bonding resin layer, a supporting layer, a second bonding resin layer, a blocking layer, a third bonding resin layer and a heat sealing layer from outside to inside. Wherein the weight-average molecular weight of resin used by the first bonding resin layer and the second bonding resin layer is 40000-150000, the glass transition temperature is 5-50 DEG C, and the interface stripping force at 120 DEG C can be more than 3N / 15mm; the weight-average molecular weight of resin used by the third bonding resin layer is 100000-300000, the glass transition temperature is-50 DEG C to 0 DEG C, the melting point is 100 DEG C to 180 DEG C, and the interface stripping force at 120 DEG C can be more than 5N / 15mm; high-melting-point particles with the melting point ranging from 160 DEG C to 230 DEG C are added into the heat sealing layer, and the packaging tension at 120 DEG C can be 50 N / 15 mm or above.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-plastic film technology, specifically relating to a flexible aluminum-plastic film and its applications. Background Technology

[0002] Compared to traditional lead-acid and nickel-metal hydride batteries, lithium-ion batteries, with their core advantages of high energy density, long lifespan, lighter weight, and low self-discharge rate, have been widely used in the fields of power batteries, consumer batteries, and energy storage batteries. Lithium-ion batteries are divided into lithium-ion batteries and solid-state batteries based on the type of electrolyte. Their core structure includes a positive electrode, a negative electrode, an electrolyte, and battery packaging materials. Lithium-ion batteries mostly use liquid or gel-state electrolytes, containing a liquid electrolyte to ensure the transport of lithium ions between the two electrodes. Solid-state batteries have a solid electrolyte and do not contain a liquid electrolyte. Currently, the energy density of lithium-ion batteries is approaching its theoretical limit, making it difficult to meet future demands for ultra-long driving range. These limitations of lithium-ion batteries are forcing the industry to accelerate the shift to solid-state batteries. The core driving force stems from the significant advantages of solid-state batteries in terms of energy density and safety, enabling them to meet the higher performance requirements of lithium-ion batteries in many emerging and traditional fields.

[0003] Soft-pack aluminum-plastic film is one of the most common outer packaging materials for lithium batteries, accounting for approximately 25% of the total battery outer packaging material market. Its structure, from the outside in, includes a protective layer, a support layer, a barrier layer, and a heat-sealing layer, with different types of adhesive resins used to bond the layers together. Compared to lithium-ion batteries, solid-state batteries, because they do not contain electrolyte and have high interfacial steric hindrance between the solid electrolyte and electrode materials, often require higher operating temperatures to achieve high-rate charge and discharge performance. This places higher demands on the temperature resistance of soft-pack aluminum-plastic film.

[0004] Currently available soft-pack aluminum-plastic films are primarily designed for lithium-ion batteries, with an operating temperature generally not exceeding 60℃. When the operating temperature exceeds 80℃, due to the inherent temperature resistance limitations of the bonding resin and heat-sealing layer particles, the following three problems are prone to occur: first, separation of the interface between the protective layer / support layer / barrier layer; second, separation of the interface between the heat-sealing layer and the barrier layer; and third, separation of the interface between heat-sealing layers. Any of these three problems will lead to the failure of the battery cell's normal operation, severely impacting its safety performance. Solid-state batteries do not contain electrolyte; the transport of lithium ions within the cell requires overcoming significant steric hindrance. To achieve high-rate charging and discharging, the operating temperature is generally required to be above 80℃, and sometimes exceeding 100℃. Currently available aluminum-plastic films are unlikely to meet the high-rate charging and discharging requirements of solid-state batteries. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible aluminum-plastic film and its applications to solve the above-mentioned technical problems.

[0006] To address the aforementioned technical problems, this invention provides a flexible aluminum-plastic film, comprising: The layers arranged sequentially from the outside in are: a protective layer, a first adhesive resin layer, a support layer, a second adhesive resin layer, a barrier layer, a third adhesive resin layer, and a heat-sealing layer; wherein... The protective layer and the support layer are bonded together by a first adhesive resin layer; The support layer and the barrier layer are bonded together with a second adhesive resin layer; The heat-sealing layer and the barrier layer are bonded together with a third adhesive resin layer; The weight-average molecular weight of the resins used in the first and second adhesive resin layers is 40,000 to 150,000, and the glass transition temperature is 5°C to 50°C. The weight-average molecular weight of the resin used in the third adhesive resin layer is 100,000 to 300,000, the glass transition temperature is -50℃ to 0℃, and the melting point is 100℃ to 180℃. The heat-sealing layer contains high-melting-point particles with a melting point of 160℃ to 230℃.

[0007] In one embodiment of this application, the protective layer is polyethylene terephthalate, polybutylene terephthalate, or a modified material thereof; preferably, the protective layer is polyethylene terephthalate, and the thickness of the protective layer is 3µm to 50µm.

[0008] In one embodiment of this application, the first adhesive resin layer and the second adhesive resin layer are one of polyurethane resin, acrylic resin, epoxy resin, or a modified material thereof; preferably, the first adhesive resin layer and the second adhesive resin layer are polyurethane resin; and the thickness of the first adhesive resin layer and the second adhesive resin layer is 1µm to 6µm.

[0009] In one embodiment of this application, the weight-average molecular weight of the first adhesive resin layer and the second adhesive resin layer is 40,000 to 100,000, and the glass transition temperature is 10°C to 30°C.

[0010] In one embodiment of this application, the support layer is one of PA6 (i.e., nylon 6), PA66 (i.e., nylon 66), polyethylene terephthalate, polybutylene terephthalate, or a modified material thereof; preferably, the support layer is PA6; and the thickness of the support layer is 10um to 50um.

[0011] In one embodiment of this application, the barrier layer is an aluminum foil or a stainless steel foil; preferably, the barrier layer is an aluminum foil; and the thickness of the barrier layer is 20µm to 100µm.

[0012] In one embodiment of this application, both sides of the barrier layer are coated with an anti-corrosion coating; the anti-corrosion coating is a trivalent chromium anti-corrosion coating or an inorganic nano-metal oxide anti-corrosion coating.

[0013] In one embodiment of this application, the weight-average molecular weight of the resin used in the third adhesive resin layer is 100,000 to 200,000, the glass transition temperature is -30°C to 0°C, and the melting point is 100°C to 150°C; the thickness of the third adhesive resin layer is 2µm to 50µm.

[0014] In one embodiment of this application, the reactive monomer of the third adhesive resin layer is a copolymer of one, two, or three of maleic anhydride-grafted propylene, ethylene, and butene; the third adhesive resin layer is applied by solvent dissolution and dilution, or by casting extrusion molding.

[0015] In one embodiment of this application, the heat-sealing layer is a copolymer of one, two, or three of propylene, ethylene, and butene; the thickness of the heat-sealing layer is 10 μm to 100 μm; and the high-melting-point particles are one of PA6, PMMA (polymethyl methacrylate), and PS (polystyrene).

[0016] Accordingly, the present invention provides an application of the soft-pack aluminum-plastic film as described above in solid-state batteries.

[0017] The beneficial effects of this invention are that the flexible aluminum-plastic film of this invention comprises, from the outside to the inside, a protective layer, a first adhesive resin layer, a support layer, a second adhesive resin layer, a barrier layer, a third adhesive resin layer, and a heat-sealing layer. Specifically, the first and second adhesive resin layers use resins with a weight-average molecular weight of 40,000–150,000 and a glass transition temperature of 5°C–50°C, achieving an interfacial peel force of 3N / 15mm or more at 120°C; the third adhesive resin layer uses resins with a weight-average molecular weight of 100,000–300,000, a glass transition temperature of -50°C–0°C, and a melting point of 100°C–180°C, achieving an interfacial peel force of 5N / 15mm or more at 120°C; and the heat-sealing layer contains high-melting-point particles with a melting point of 160°C–230°C, achieving a sealing pull force of 50N / 15mm or more at 120°C.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the flexible aluminum-plastic film of the present invention.

[0022] In the picture: The protective layer 1, the first adhesive resin layer 2, the support layer 3, the second adhesive resin layer 4, the barrier layer 5, the third adhesive resin layer 6, and the heat-sealing layer 7. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions 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, 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.

[0024] Example 1 See Figure 1 This embodiment provides a flexible aluminum-plastic film, which comprises a protective layer 1, a first adhesive resin layer 2, a support layer 3, a second adhesive resin layer 4, a barrier layer 5, a third adhesive resin layer 6, and a heat-sealing layer 7; wherein the protective layer and the support layer are bonded together with the first adhesive resin layer; the support layer and the barrier layer are bonded together with the second adhesive resin layer; and the heat-sealing layer and the barrier layer are bonded together with the third adhesive resin layer.

[0025] The manufacturing process of the flexible aluminum-plastic film in this embodiment is as follows: (1) The protective layer is polyethylene terephthalate (PET) with a thickness of 6 μm; the support layer is PA6 film with a thickness of 15 μm; the first adhesive resin layer is polyurethane resin with a weight average molecular weight of 50,000 and a glass transition temperature of 25°C; the first adhesive resin layer is coated on the surface of the support layer by gravure roller coating, with a dry coating thickness of 3.5 μm, and then thermally bonded with the protective layer. (2) The barrier layer is aluminum foil with a thickness of 40 μm; the anti-corrosion coating is an inorganic nano-cerium dioxide coating; the anti-corrosion coating is evenly coated on both sides of the barrier layer by gravure roller coating and then dried in a high-temperature oven. (3) The second adhesive resin layer is made of polyurethane resin with a weight average molecular weight of 50,000 and a glass transition temperature of 25°C. The second adhesive resin layer is coated on the other side of the support layer by gravure roller coating. The dry coating thickness is 3.5 μm. Then it is thermally bonded with the barrier layer. After that, it is cured at 80°C for 4 days. (4) The third adhesive resin layer is made of maleic anhydride-grafted propylene resin with a weight average molecular weight of 200,000, a glass transition temperature of -25°C, and a melting point of 100°C; the heat-sealing layer is a copolymer of propylene, ethylene, and butene, containing PMMA particles with a melting point of 190°C and a thickness of 80 μm; the third adhesive resin layer is coated on the other side of the barrier layer by gravure roller coating, with a dry coating thickness of 3.0 μm, and then thermally bonded with the heat-sealing layer; then cured at 40°C for 4 days to obtain a soft-pack aluminum-plastic film.

[0026] Example 2 See Figure 1 This embodiment provides a flexible aluminum-plastic film, which comprises a protective layer 1, a first adhesive resin layer 2, a support layer 3, a second adhesive resin layer 4, a barrier layer 5, a third adhesive resin layer 6, and a heat-sealing layer 7; wherein the protective layer and the support layer are bonded together with the first adhesive resin layer; the support layer and the barrier layer are bonded together with the second adhesive resin layer; and the heat-sealing layer and the barrier layer are bonded together with the third adhesive resin layer.

[0027] The manufacturing process of the flexible aluminum-plastic film in this embodiment is as follows: (1) The protective layer is polyethylene terephthalate (PET) with a thickness of 12 μm; the support layer is PA6 film with a thickness of 25 μm; the first adhesive resin layer is polyurethane resin with a weight average molecular weight of 100,000 and a glass transition temperature of 25°C; the first adhesive resin layer is coated on the surface of the support layer by gravure roller coating, with a dry coating thickness of 3.5 μm, and then thermally bonded with the protective layer. (2) The barrier layer is aluminum foil with a thickness of 60um; the anti-corrosion coating is an inorganic nano cerium dioxide coating; the anti-corrosion coating is evenly coated on both sides of the barrier layer by gravure roller coating and then dried in a high-temperature oven. (3) The second adhesive resin layer is made of polyurethane resin with a weight average molecular weight of 100,000 and a glass transition temperature of 25°C. The second adhesive resin layer is coated on the other side of the support layer by gravure roller coating. The dry coating thickness is 3.5 μm. Then it is thermally bonded with the barrier layer. After that, it is cured at 80°C for 4 days. (4) The third adhesive resin layer is made of maleic anhydride-grafted propylene resin with a weight average molecular weight of 200,000, a glass transition temperature of -25°C, and a melting point of 100°C; the heat-sealing layer is a copolymer of propylene, ethylene, and butene, containing PMMA particles with a melting point of 190°C and a thickness of 80 μm; the third adhesive resin layer is coated on the other side of the barrier layer by gravure roller coating, with a dry coating thickness of 3.0 μm, and then thermally bonded with the heat-sealing layer; then cured at 40°C for 4 days to obtain a soft-pack aluminum-plastic film.

[0028] Example 3 See Figure 1 This embodiment provides a flexible aluminum-plastic film, which comprises a protective layer 1, a first adhesive resin layer 2, a support layer 3, a second adhesive resin layer 4, a barrier layer 5, a third adhesive resin layer 6, and a heat-sealing layer 7; wherein the protective layer and the support layer are bonded together with the first adhesive resin layer; the support layer and the barrier layer are bonded together with the second adhesive resin layer; and the heat-sealing layer and the barrier layer are bonded together with the third adhesive resin layer.

[0029] The manufacturing process of the flexible aluminum-plastic film in this embodiment is as follows: (1) The protective layer is polyethylene terephthalate (PET) with a thickness of 12 μm; the support layer is PA6 film with a thickness of 15 μm; the first adhesive resin layer is an acrylic resin with a weight average molecular weight of 80,000 and a glass transition temperature of 15°C; the first adhesive resin layer is coated on the surface of the support layer by gravure roller coating, with a dry coating thickness of 4.5 μm, and then thermally bonded with the protective layer. (2) The barrier layer is aluminum foil with a thickness of 40 μm; the anti-corrosion coating is an inorganic nano-cerium dioxide coating; the anti-corrosion coating is evenly coated on both sides of the barrier layer by gravure roller coating and then dried in a high-temperature oven. (3) The second adhesive resin layer is an acrylic resin with a weight average molecular weight of 80,000 and a glass transition temperature of 15°C. The second adhesive resin layer is coated on the other side of the support layer by gravure roller coating. The dry coating thickness is 4.5 μm. Then it is thermally bonded with the barrier layer. After that, it is cured at 80°C for 4 days. (4) The third adhesive resin layer is made of maleic anhydride-grafted propylene resin with a weight average molecular weight of 100,000, a glass transition temperature of -10℃, and a melting point of 115℃; the heat-sealing layer is a copolymer of propylene, ethylene, and butene, containing PMMA particles with a melting point of 220℃ and a thickness of 80µm; the third adhesive resin layer is coated on the other side of the barrier layer by gravure roller coating, with a dry coating thickness of 3.0µm, and then thermally bonded with the heat-sealing layer; then cured at 40℃ for 4 days to obtain a soft-pack aluminum-plastic film.

[0030] Example 4 See Figure 1 This embodiment provides a flexible aluminum-plastic film, which comprises a protective layer 1, a first adhesive resin layer 2, a support layer 3, a second adhesive resin layer 4, a barrier layer 5, a third adhesive resin layer 6, and a heat-sealing layer 7; wherein the protective layer and the support layer are bonded together with the first adhesive resin layer; the support layer and the barrier layer are bonded together with the second adhesive resin layer; and the heat-sealing layer and the barrier layer are bonded together with the third adhesive resin layer.

[0031] The manufacturing process of the flexible aluminum-plastic film in this embodiment is as follows: (1) The protective layer is polybutylene terephthalate (PBT) with a thickness of 25 μm; the support layer is PA6 film with a thickness of 25 μm; the first adhesive resin layer is polyurethane resin with a weight average molecular weight of 80,000 and a glass transition temperature of 30°C; the first adhesive resin layer is coated on the surface of the support layer by gravure roller coating, with a dry coating thickness of 4.5 μm, and then thermally bonded with the protective layer. (2) The barrier layer is aluminum foil with a thickness of 80um; the anti-corrosion coating is a trivalent chromium passivation coating; the anti-corrosion coating is evenly coated on both sides of the barrier layer by gravure roller coating and then dried in a high-temperature oven. (3) The second adhesive resin layer is made of polyurethane resin with a weight average molecular weight of 80,000 and a glass transition temperature of 30°C. The second adhesive resin layer is coated on the other side of the support layer by gravure roller coating. The dry coating thickness is 4.5 μm. Then it is thermally bonded with the barrier layer. After that, it is cured at 80°C for 4 days. (4) The third adhesive resin layer is made of maleic anhydride-grafted propylene resin with a weight average molecular weight of 150,000, a glass transition temperature of -25°C, and a melting point of 140°C; the heat-sealing layer is a copolymer of propylene and ethylene, containing PMMA particles with a melting point of 200°C; the third adhesive resin layer and the heat-sealing layer are extruded together on the other side of the barrier layer through a casting co-extrusion process, with the thickness of the third adhesive resin layer being 40 μm and the thickness of the heat-sealing layer being 40 μm; and then a soft-pack aluminum-plastic film is obtained after hot roller treatment.

[0032] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the first and second adhesive resin layers in Comparative Example 1 have a weight-average molecular weight of 30,000 and a glass transition temperature of 10°C. The types and proportions of other materials and the preparation method of the coating are exactly the same as those in Example 1.

[0033] Comparative Example 2 The only difference between Comparative Example 2 and Example 2 is that the third adhesive resin layer in Comparative Example 2 has a weight-average molecular weight of 80,000, a glass transition temperature of -25°C, and a melting point of 85°C. The types and proportions of other materials and the preparation method of the coating are exactly the same as those in Example 2.

[0034] Comparative Example 3 The only difference between Comparative Example 3 and Example 3 is that the heat-sealing layer of Comparative Example 3 does not contain high-melting-point particle components. The types and proportions of other materials and the preparation method of the coating are exactly the same as those in Example 3.

[0035] Using the flexible aluminum-plastic films obtained in Examples 1-3 and Comparative Examples 1-3 above, the high-temperature strength of the support layer / barrier layer, heat-sealing layer / barrier layer, and heat-sealing interface was compared and evaluated.

[0036] Evaluation of peel strength of support layer / barrier layer: After punching the soft-pack aluminum-plastic film, take a 15mm wide test strip from the bottom of the shell. First, manually peel out a 2-3mm separation interface, and then place it in a high-temperature tensile testing chamber for peel testing. The test temperatures are 25℃, 100℃, and 120℃. After the temperature reaches the set temperature, stabilize for 3 minutes, and the tensile speed is 50mm / min.

[0037] Evaluation of peel strength of heat-sealing layer / barrier layer: After punching the soft-pack aluminum-plastic film, take a 15mm wide test strip from the bottom of the shell. First, manually peel out a 2-3mm separation interface, and then place it in a high-temperature tensile testing chamber for peel testing. The test temperatures are 25℃, 100℃, and 120℃. After the temperature reaches the set temperature, stabilize for 3 minutes, and the tensile speed is 50mm / min.

[0038] Evaluation of heat-sealed interface strength: The flexible aluminum-plastic film was folded in half (with the heat-sealing layer on the inside), and then heat-sealed using a heat-sealing machine at 190℃ for 3 seconds, maintaining approximately 70% of the heat-sealed layer remaining. A 15mm wide sample was then cut and placed in a high-temperature tensile testing chamber for peel testing. The test temperatures were 25℃, 100℃, and 120℃. After reaching the set temperature, the temperature was stabilized for 3 minutes, and the tensile speed was 50mm / min.

[0039] The evaluation results are shown in Table 1.

[0040] Table 1 As can be seen from Table 1, the flexible aluminum-plastic film of the present invention exhibits superior high-temperature resistance at temperatures of 100°C and 120°C, with respect to the composite interface of the support layer / barrier layer, the composite interface of the heat-sealing layer / barrier layer, and the heat-sealing interface.

[0041] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.

Claims

1. A flexible aluminum-plastic film, characterized in that, include: The layers arranged from the outside to the inside are: a protective layer, a first adhesive resin layer, a support layer, a second adhesive resin layer, a barrier layer, a third adhesive resin layer, and a heat-sealing layer. in The protective layer and the support layer are bonded together by a first adhesive resin layer; The support layer and the barrier layer are bonded together with a second adhesive resin layer; The heat-sealing layer and the barrier layer are bonded together with a third adhesive resin layer; The weight-average molecular weight of the resins used in the first and second adhesive resin layers is 40,000 to 150,000, and the glass transition temperature is 5°C to 50°C. The weight-average molecular weight of the resin used in the third adhesive resin layer is 100,000 to 300,000, the glass transition temperature is -50℃ to 0℃, and the melting point is 100℃ to 180℃. The heat-sealing layer contains high-melting-point particles with a melting point of 160℃ to 230℃.

2. The flexible aluminum-plastic film according to claim 1, characterized in that, The protective layer is one of polyethylene terephthalate, polybutylene terephthalate, or a modified material thereof; and The thickness of the protective layer is 3µm to 50µm.

3. The flexible aluminum-plastic film according to claim 1, characterized in that, The first adhesive resin layer and the second adhesive resin layer are one of polyurethane resin, acrylic resin, epoxy resin, or a modified material thereof; as well as The thickness of the first adhesive resin layer and the second adhesive resin layer is 1µm to 6µm; The weight-average molecular weight of the first and second adhesive resin layers is 40,000 to 100,000, and the glass transition temperature is 10°C to 30°C.

4. The flexible aluminum-plastic film according to claim 1, characterized in that, The support layer is one of PA6, PA66, polyethylene terephthalate, and polybutylene terephthalate, or a modified material thereof; and The thickness of the support layer is 10um to 50um.

5. The flexible aluminum-plastic film according to claim 1, characterized in that, The barrier layer is aluminum foil or stainless steel foil; and The thickness of the barrier layer is 20um to 100um.

6. The flexible aluminum-plastic film according to claim 1, characterized in that, Both sides of the barrier layer are coated with an anti-corrosion coating. The anti-corrosion coating is a trivalent chromium anti-corrosion coating or an inorganic nano-metal oxide anti-corrosion coating.

7. The flexible aluminum-plastic film according to claim 1, characterized in that, The weight-average molecular weight of the resin used in the third adhesive resin layer is 100,000 to 200,000, the glass transition temperature is -30℃ to 0℃, and the melting point is 100℃ to 150℃. The thickness of the third adhesive resin layer is 2µm to 50µm.

8. The flexible aluminum-plastic film according to claim 1, characterized in that, The reactive monomer of the third adhesive resin layer is a copolymer of one, two, or three of maleic anhydride-grafted propylene, ethylene, and butene. The third adhesive resin layer is applied after being dissolved and diluted with a solvent, or it is formed by casting and extrusion.

9. The flexible aluminum-plastic film according to claim 1, characterized in that, The heat-sealing layer is a copolymer of one, two, or three of propylene, ethylene, and butene. The thickness of the heat-sealing layer is 10µm to 100µm; The high-melting-point particles are one of PA6, PMMA, and PS.

10. The application of a soft-pack aluminum-plastic film as described in any one of claims 1-9 in a solid-state battery.

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