Aluminum-plastic film, preparation method and application thereof

Abstract

This invention proposes an aluminum-plastic film, its preparation method, and its application. The aluminum-plastic film includes a heat-sealing layer, a barrier layer, a protective layer, and an anti-fouling layer, and also includes a heat-insulating layer, which is disposed on either side of the anti-fouling layer. Through the aluminum-plastic film, its preparation method, and its application proposed in this invention, the heat insulation performance of batteries can be improved, avoiding cascading failures of the battery pack caused by thermal runaway of a single battery, thus enhancing safety.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, specifically to an aluminum-plastic film, its preparation method, and its application. Background Technology

[0002] With the continuous expansion of lithium-ion battery applications, especially in new energy vehicles and large-scale energy storage systems, there is a need to densely integrate a large number of lithium-ion batteries into battery packs to meet the high energy demands of practical applications. In lithium-ion batteries, aluminum-plastic film, as an outer packaging material, can only provide basic functions such as external impact protection, moisture barrier, heat sealing, and pollution prevention. It lacks heat-blocking capabilities, thus failing to quickly block heat transfer when a single battery cell catches fire, making it difficult to meet the safety protection requirements of densely packed battery packs. Summary of the Invention

[0003] This invention proposes an aluminum-plastic film, its preparation method, and its application, which can improve the thermal insulation performance of batteries, avoid the chain reaction of battery pack failure caused by thermal runaway of a single battery, and improve safety.

[0004] To solve the above-mentioned technical problems, the present invention provides an aluminum-plastic film, including a heat-sealing layer, a barrier layer, a protective layer and an anti-pollution layer. The aluminum-plastic film also includes a heat insulation layer, which is disposed on any side of the anti-pollution layer.

[0005] In one embodiment of the present invention, the material of the heat insulation layer includes silica aerogel.

[0006] In one embodiment of the present invention, the heat insulation layer has a porous structure, and the average pore size of the heat insulation layer is 10nm-100nm.

[0007] In one embodiment of the present invention, the porosity of the heat insulation layer is 70%-90%.

[0008] In one embodiment of the present invention, the thickness of the heat insulation layer is 100μm-500μm.

[0009] In one embodiment of the present invention, the thickness ratio of the heat insulation layer to the barrier layer is (1.25-16.67):1.

[0010] In one embodiment of the present invention, the thickness ratio of the heat insulation layer to the anti-pollution layer is (3.33-83.33):1.

[0011] In one embodiment of the present invention, the flexural strength of the heat insulation layer is greater than 0.4 MPa.

[0012] The present invention also provides a method for preparing a diaphragm as described above, characterized in that it includes at least the following steps: The heat-sealing layer, barrier layer, and protective layer are sequentially laminated together to obtain an intermediate. After coating the anti-fouling layer with sol and drying it, a heat-insulating layer is formed on the anti-fouling layer; and The heat insulation layer or the anti-pollution layer is combined with the protective layer to obtain an aluminum-plastic film.

[0013] In one embodiment of the present invention, the sol is obtained by hydrolysis and polycondensation of silanol salts.

[0014] The present invention also provides a battery comprising at least any of the aluminum-plastic film described above, or an aluminum-plastic film obtained by any of the preparation methods described above.

[0015] In summary, this invention proposes an aluminum-plastic film, its preparation method, and its application, which can improve the thermal insulation performance of batteries, prevent heat from spreading from one battery to adjacent batteries, thereby avoiding cascading failures of the battery pack caused by thermal runaway of a single battery and improving safety. Furthermore, the aluminum-plastic film, its preparation method, and its application proposed in this invention can simultaneously achieve both good thermal insulation performance and high mechanical strength. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the aluminum-plastic film in one embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the aluminum-plastic film structure in another embodiment of the present invention.

[0019] Label Explanation: 11. Heat-sealing layer; 12. Barrier layer; 13. Protective layer; 14. Heat insulation layer; 15. Anti-pollution layer. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0021] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0022] The technical solution of the present invention will be further described in detail below with reference to the embodiments. 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.

[0023] Please see Figures 1 to 2 As shown, the present invention provides an aluminum-plastic film, including a heat-sealing layer 11, a barrier layer 12, a protective layer 13, a heat-insulating layer 14, and an anti-fouling layer 15. The thickness of the heat-sealing layer 11 is, for example, 40μm-100μm, and the material of the heat-sealing layer 11 includes at least one of polypropylene (PP) and polyethylene (PE). Thus, when the heat-sealing layer 11 is heated and melted, the edges of the aluminum-plastic film can be thermally bonded, forming a sealed encapsulation cavity for the battery, preventing electrolyte leakage and the intrusion of external moisture and oxygen.

[0024] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, a barrier layer 12 is disposed on one side of the heat-sealing layer 11 to prevent external moisture and oxygen and other impurities from penetrating into the battery, thereby avoiding battery performance degradation or failure caused by chemical reactions between impurities and the cell and electrolyte. The material of the barrier layer 12 includes, for example, aluminum, and the thickness of the barrier layer 12 is, for example, 30μm-80μm.

[0025] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, the protective layer 13 is disposed on the side of the barrier layer 12 away from the heat-sealing layer 11, so that the aluminum-plastic film as a whole has high mechanical strength, tensile strength, impact resistance and bending resistance, which can buffer external mechanical extrusion and impact, and protect the barrier layer 12 from cracking. The material of the protective layer 13 includes, for example, at least one of nylon and polyethylene terephthalate (PET), and the nylon includes, for example, at least one of polycaprolactam and polyhexamethylene adipamide, and the thickness of the protective layer 13 is, for example, 15μm-30μm.

[0026] Please see Figures 1 to 2As shown, in one embodiment of the present invention, the anti-fouling layer 15 is disposed on the side of the protective layer 13 away from the barrier layer 12 to isolate external oil and chemical contamination. The material of the anti-fouling layer 15 includes at least one of PET and polybutylene terephthalate, and the thickness of the anti-fouling layer 15 is, for example, 6 μm-30 μm.

[0027] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, the heat insulation layer 14 is disposed between the anti-fouling layer 15 and the protective layer 13, or disposed on the side of the anti-fouling layer 15 away from the protective layer 13. Specifically, the material of the heat insulation layer 14 includes silica aerogel, etc. Aerogel has an extremely low thermal conductivity and a three-dimensional nanoporous structure, which can significantly block heat conduction and heat convection, possessing excellent heat insulation, flame retardant, and heat-blocking properties. It can suppress heat diffusion when a battery cell catches fire, preventing chain thermal runaway of the battery pack.

[0028] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, the heat insulation layer 14 has a porous structure, and the average pore size of the heat insulation layer 14 is, for example, 10 nm-100 nm. By controlling the average pore size, the heat conduction effect in the heat insulation layer can be regulated. A suitable average pore size can limit gaseous heat conduction, achieving the lowest possible gaseous thermal conductivity, thus giving the heat insulation layer excellent heat insulation performance. Moreover, the porosity of the heat insulation layer 14 is, for example, 70%-90%, and more specifically, 70%-80%. By controlling the porosity of the heat insulation layer 14, solid-state heat conduction can be reduced, and the heat insulation effect and mechanical strength of the heat insulation layer can be balanced.

[0029] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, the thickness of the heat insulation layer 14 is, for example, 100μm-500μm. Further, the thickness ratio of the heat insulation layer 14 to the barrier layer 12 is, for example, (1.25-16.67):1. By controlling the thickness ratio of the heat insulation layer 14 to the barrier layer 12, the aluminum-plastic film can possess both good heat insulation effect and mechanical strength. Increasing the thickness ratio can significantly reduce the thermal conductivity of the aluminum-plastic film and improve the heat insulation effect. However, an excessively large thickness ratio will reduce the overall mechanical strength of the aluminum-plastic film, while an excessively small thickness ratio will worsen the overall heat insulation effect. Moreover, the thickness ratio of the heat insulation layer 14 to the anti-fouling layer 15 is, for example, (3.33-83.33):1. By controlling the thickness ratio of the heat insulation layer 14 to the anti-fouling layer 15, the rigidity and stiffness of the aluminum-plastic film structure can be adjusted.

[0030] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, the bending strength of the heat insulation layer 14 is, for example, greater than 0.4 MPa. By controlling the bending strength of the heat insulation layer 14, the structural stability of the aluminum-plastic film during production and subsequent battery manufacturing processes can be ensured.

[0031] Please see Figures 1 to 2 As shown, based on the above-mentioned aluminum-plastic film, the present invention also provides a method for preparing aluminum-plastic film, including steps S11-S13.

[0032] Step S11: The heat-sealing layer 11, the barrier layer 12 and the protective layer 13 are sequentially bonded together to obtain an intermediate.

[0033] Step S12: Apply the sol to one side of the anti-fouling layer 15 and dry it to form a heat insulation layer 14 on the anti-fouling layer 15.

[0034] Step S13: Composite the heat insulation layer 14 or the anti-pollution layer 15 with the protective layer 13 to obtain an aluminum-plastic film.

[0035] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, in step S11, an adhesive is first applied to one side of the barrier layer 12 and then hot-pressed together with the heat-sealing layer 11. Then, an adhesive is applied to the other side of the barrier layer 12 and hot-pressed together with the protective layer 13 to obtain an intermediate of heat-sealing layer 11-barrier layer 12-protective layer 13. The adhesive material includes, for example, at least one of polyurethane and acrylate. The polyurethane includes, for example, at least one of adipic acid-1,4-butanediol polyester polyol, hexamethylene diisocyanate, and diphenylmethane diisocyanate. The acrylate includes, for example, at least one of butyl acrylate, methyl methacrylate, and hydroxyethyl acrylate. The hot-pressing temperature is, for example, 55°C-85°C, and the hot-pressing pressure is, for example, 0.3 MPa-0.8 MPa.

[0036] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, after obtaining the intermediate, in step S12, the silanol, solvent, and deionized water are mixed evenly, and then a catalyst is added and stirred. The silanol and water undergo hydrolysis, and the alkoxy group is replaced by the hydroxyl group to generate an intermediate containing silanol groups, thus obtaining a mixture. Then, an alkaline solution is added dropwise to the mixture to adjust the pH value of the mixture to, for example, 5-6, and stirring continues to induce the silanol groups to undergo dehydration condensation, forming a uniform and coatable silica-based sol. The silanol includes, for example, at least one of tetraethyl orthosilicate and methyl orthosilicate; the solvent includes, for example, at least one of ethanol and methanol; the catalyst includes, for example, at least one of hydrochloric acid and nitric acid; the alkaline solution includes, for example, ammonia and sodium hydroxide; the mass ratio of silanol, solvent, deionized water, and catalyst is, for example, 100:(120-300):(80-180):(0.5-2); and the content of silanol in the mixture is, for example, 5wt%-40wt%.

[0037] Please see Figures 1 to 2As shown, in one embodiment of the present invention, after obtaining the sol, in step S12, the sol is coated on one side of the anti-fouling layer 15 and then allowed to stand and age at room temperature for, for example, 12h-24h. The sol transforms into a wet gel, which is then dried to slowly remove the liquid from the wet gel, forming an aerogel on one side of the anti-fouling layer 15, thus obtaining the heat insulation layer 14. The drying process is, for example, a three-stage gradient drying: the first stage drying temperature is, for example, 40℃-50℃, and the first stage drying time is, for example, 2h-3h; the second stage drying temperature is, for example, 60℃-70℃, and the second stage drying time is, for example, 3h-4h; and the third stage drying temperature is, for example, 80℃-90℃, and the third stage drying time is, for example, 1h-2h.

[0038] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, after forming a heat insulation layer 14 on the anti-fouling layer 15, in step S13, after applying an adhesive to the side of the anti-fouling layer 15 away from the heat insulation layer 14, the side of the anti-fouling layer 15 away from the heat insulation layer 14 is hot-pressed with the protective layer 13 in the intermediate to obtain an aluminum-plastic film. In another embodiment of the present invention, the adhesive can also be applied to the heat insulation layer 14, and then the heat insulation layer 14 and the protective layer 13 in the intermediate can be hot-pressed together to obtain an aluminum-plastic film. The adhesive material includes, for example, at least one of polyurethane and acrylate, the polyurethane including, for example, at least one of adipic acid-1,4-butanediol polyester polyol, hexamethylene diisocyanate, and diphenylmethane diisocyanate, the acrylate including, for example, at least one of butyl acrylate, methyl methacrylate, and hydroxyethyl acrylate, the hot-pressing temperature being, for example, 55°C-85°C, and the hot-pressing pressure being, for example, 0.3MPa-0.8MPa.

[0039] Please see Figures 1 to 2 As shown, based on the above-described aluminum-plastic film and its preparation method, the present invention also provides a battery, which is a lithium-ion battery or a sodium-ion battery, etc. In this embodiment, a lithium-ion battery is used as an example for explanation. Specifically, a lithium-ion battery includes, for example, a positive electrode, a separator, a negative electrode, an electrolyte, and an aluminum-plastic film, etc. The aluminum-plastic film encloses and forms an encapsulation cavity to accommodate the positive electrode, separator, negative electrode, and electrolyte. The aluminum-plastic film is the aluminum-plastic film described above or an aluminum-plastic film obtained according to the above-described preparation method, which will not be elaborated further here. The electrolyte is in direct contact with the heat-sealing layer 11 in the aluminum-plastic film.

[0040] In one embodiment of the present invention, the positive electrode sheet includes a positive current collector and a positive active layer coated on at least one surface of the positive current collector. The positive current collector is, for example, a foil formed by surface treatment of materials such as nickel, titanium, aluminum, silver, stainless steel, or carbon. Besides foil, the positive current collector can also be used in any one or more combinations of various forms such as film, mesh, porous, foam, or non-woven fabric. The thickness of the positive current collector is, for example, 10 μm-20 μm.

[0041] In one embodiment of the present invention, in a lithium-ion battery, the positive electrode active layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder, etc., and the thickness of the positive electrode active layer is, for example, 100μm-110μm. The ratio of the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder can be selected according to actual needs. In this embodiment, the positive electrode active material is, for example, lithium iron phosphate or a ternary material, and the ternary material includes, for example, at least one of nickel cobalt manganese (NCM) and nickel cobalt aluminum (NCA).

[0042] In one embodiment of the present invention, the positive electrode conductive agent is selected from at least one of conductive carbon black (Super P), acetylene black, carbon nanotubes, or graphene, and the positive electrode binder is selected from at least one of polyvinylidene fluoride (PVDF), poly(ethylene oxide) (PEO), polyamide (PA), polyacrylonitrile (PAN), polyacrylate (polyacrylate), polyvinyl ether (polyvinyl ether), polymethyl methacrylate (PMMA), ethylene-propylene-diene terpolymer (EPDM), polyhexanefluoropropylene (polyhexafluoropropylene), or polymerized styrene-butadiene rubber (SBR).

[0043] In one embodiment of the present invention, the positive electrode current collector is, for example, an aluminum foil with a thickness of 15 μm, the positive electrode conductive agent is, for example, Super P, the positive electrode binder is, for example, PVDF, and the chemical formula of the positive electrode active material is, for example, LiNi. 0.5 Co 0.2 Mn 0.3 O2. Specifically, LiNi 0.5 Co 0.2 Mn 0.3O2 positive electrode active material, PVDF, and Super P are mixed in a mass ratio of 98:1:1, dissolved in an organic solvent, and stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is then uniformly coated onto both sides of an aluminum foil, air-dried at room temperature, and then transferred to an oven for drying. After cold pressing and slitting, a positive electrode sheet is obtained, with a thickness of, for example, 120 μm. The organic solvent is, for example, N-methylpyrrolidone (NMP).

[0044] In one embodiment of the present invention, the negative electrode sheet is, for example, an indium sheet, a lithium sheet, an aluminum sheet, or an alloy sheet composed of at least two of the above metals. In other embodiments of the present invention, the negative electrode sheet further includes, for example, a negative current collector and a negative active layer coated at least on one surface of the negative current collector. The negative current collector is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foamed copper current collector, or a stainless steel current collector, etc., and the negative active layer includes a negative active material, a negative conductive agent, a negative thickener, and a negative binder, etc. The proportions of the negative active material, the negative conductive agent, the negative thickener, and the negative binder can be selected according to actual needs. In this embodiment, the negative electrode active material is selected from at least one of graphite, silicon, or lithium metal, the negative electrode conductive agent is selected from at least one of Super P, acetylene black, Ketjen black, carbon nanotubes, or graphene, the negative electrode thickener includes, for example, sodium carboxymethyl cellulose (CMC-Na), and the negative electrode binder is selected from at least one of polypropylene, polyacrylate, polyethylene ether, PMMA, polyhexamethylene propylene, or SBR.

[0045] In one embodiment of the present invention, the negative electrode current collector is, for example, copper foil; the negative electrode active material is, for example, graphite; the negative electrode conductive agent is, for example, Super P; the negative electrode thickener is, for example, CMC-Na; and the negative electrode binder is, for example, SBR. Specifically, the negative electrode active material, negative electrode conductive agent, negative electrode thickener, and negative electrode binder are mixed in a mass ratio of 96:1:1:2, and deionized water solvent is added. The mixture is then thoroughly stirred and mixed uniformly under the action of a vacuum mixer to obtain a negative electrode slurry. The negative electrode slurry is coated onto copper foil, and after being dried at room temperature, it is transferred to an oven for drying. After cold pressing and slitting, the negative electrode sheet is obtained.

[0046] In one embodiment of the present invention, a separator is disposed between the positive electrode and the negative electrode. The separator can be, for example, a conventional separator, a ceramic separator, a polymer separator, a non-woven fabric separator, or an inorganic-organic composite separator. Specifically, the separator can be, for example, a single-layer polypropylene (PP) membrane, a single-layer polyethylene (PE) membrane, a double-layer PP / PE membrane, a double-layer PP / PP membrane, or a triple-layer PP / PE / PP membrane. In this embodiment, a single-layer PP membrane is selected as the separator, for example.

[0047] In one embodiment of the present invention, an electrolyte is filled between the positive electrode, the negative electrode, and the separator to conduct ions. The electrolyte comprises at least a solvent and a lithium salt. The solvent includes, for example, at least one selected from diethyl carbonate, fluoroethylene carbonate, difluoroethyl acetate, dimethyl carbonate, ethylene carbonate, propylene carbonate, or methyl ethyl carbonate. The lithium salt includes at least one selected from lithium hexafluorophosphate (LiPF6) and lithium tetrafluoroborate (LiBF4), and the lithium salt content in the electrolyte is, for example, 10wt%-18wt%.

[0048] Please see Figures 1 to 2 As shown, in one embodiment of the present invention, the above-mentioned positive electrode, separator, and negative electrode are stacked or wound in sequence to form a battery cell, with the separator positioned between the positive and negative electrode to act as an separator. The cell is then placed in a closed cavity formed by an aluminum-plastic film. After being transferred to an environment with a dew point of -60°C and a vacuum of -98 kPa, 3.4 g of electrolyte is injected, and the cell is sealed. After being left to stand at room temperature for 48 hours, the cell undergoes electrolyte formation, venting, and aging to obtain a lithium-ion battery. The electrolyte is in direct contact with the heat-sealing layer 11 in the aluminum-plastic film.

[0049] The present invention will be explained in more detail below by referring to embodiments, which should not be construed as limiting. Appropriate modifications can be made within the scope of the present invention, and all such modifications fall within the technical scope of the present invention.

[0050] Example 1 After coating one side of the aluminum foil layer with butyl acrylate adhesive, it is hot-pressed and laminated with the PP layer. Then, butyl acrylate adhesive is coated on the other side of the aluminum foil layer, and it is hot-pressed and laminated with the nylon layer to obtain an intermediate. The hot-pressing temperature is 55℃, and the hot-pressing pressure is 0.3MPa.

[0051] After thoroughly mixing tetraethyl orthosilicate, ethanol, and deionized water, hydrochloric acid (as a catalyst) was added and stirred to obtain a mixture. Ammonia was then added dropwise to adjust the pH of the mixture to 5, and stirring continued to form a sol. The mass ratio of tetraethyl orthosilicate, ethanol, deionized water, and hydrochloric acid was 100:120:80:0.5.

[0052] After coating a sol onto one side of a PET layer, the mixture was allowed to age at room temperature for 12 hours, transforming into a wet gel. This gel was then dried, slowly removing the liquid from the wet gel to form an aerogel layer on one side of the PET layer. The drying process employed a three-stage gradient: the first stage was at 40°C for 2 hours, the second stage at 60°C for 3 hours, and the third stage at 80°C for 1 hour.

[0053] A butyl acrylate adhesive is coated on the side of the aerogel layer away from the PET layer, and then hot-pressed with an intermediate to obtain an aluminum-plastic film. The aerogel layer is positioned between the PET and nylon layers. The hot-pressing temperature is 55℃, the hot-pressing pressure is 0.3MPa, the PP layer thickness is 40μm, the aluminum foil layer thickness is 30μm, the nylon layer thickness is 15μm, the aerogel layer thickness is 100μm, and the PET layer thickness is 10μm.

[0054] Characterization of the average pore size of the aerogel layer: After mechanically peeling off the aerogel layer from the PET layer, the average pore size of the aerogel layer was characterized using the liquid nitrogen adsorption-desorption method. Specifically, the aerogel layer underwent vacuum high-temperature degassing pretreatment to remove residual moisture and organic solvents from the pores; subsequently, nitrogen adsorption-desorption isotherms were measured at a liquid nitrogen temperature of -196°C. Desorption branch data were selected, and the pore size distribution was calculated using the Barrett-Joyner-Halenda (BJH) mesoporous model to obtain the average pore size of the aerogel layer. In this embodiment, the average pore size was 10 nm.

[0055] Characterization of aerogel layer porosity: After mechanically peeling the aerogel layer off the PET layer, the aerogel layer was gradually pressurized from a low pressure of 0.1 kPa to a high pressure of 200 MPa using a mercury porosimeter, allowing mercury to penetrate the pores in the base film under pressure. The pore size was calculated from the pressure using the Washburn equation. The porosity was calculated by recording the mercury penetration volume and subtracting the dead volume, and finally by the ratio of the mercury penetration volume to the apparent volume of the sample. In this embodiment, the porosity was 70%.

[0056] Characterization of the flexural strength of the aerogel layer: After mechanically peeling the aerogel layer off the PET layer, the flexural strength of the aerogel layer was characterized using the three-point bending method. Specifically, the aerogel layer was cut into standard strip specimens and placed on the three-point bending support of a universal testing machine. A concentrated load was applied perpendicularly to the midpoint of the specimen, and the load-displacement curve and the critical load for specimen fracture were recorded during the loading process. The flexural strength of the aerogel layer was calculated according to the three-point bending strength formula. In this embodiment, the flexural strength was 0.4 MPa.

[0057] Example 2 The difference between this embodiment and Embodiment 1 is that, in the preparation of the aerogel layer, the content of tetraethyl orthosilicate in the mixture is adjusted to 13wt%, and the mass ratio of ethanol, deionized water and hydrochloric acid remains 120:80:0.5, so that the average pore size of the aerogel layer is 50nm.

[0058] Example 3 The difference between this embodiment and Embodiment 1 is that, in the preparation of the aerogel layer, the content of tetraethyl orthosilicate in the mixture is adjusted to 5 wt%, and the mass ratio of ethanol, deionized water and hydrochloric acid remains 120:80:0.5, so that the average pore size of the aerogel layer is 100 nm.

[0059] Example 4 The difference between this embodiment and Embodiment 1 is that, during the preparation of the aerogel layer, the amount of ammonia added is controlled, and the pH of the mixture is adjusted to 5.5 so that the porosity of the aerogel layer is 80%.

[0060] Example 5 The difference between this embodiment and Embodiment 1 is that, during the preparation of the aerogel layer, the amount of ammonia added is controlled, and the pH of the mixture is adjusted to 6 so that the porosity of the aerogel layer is 90%.

[0061] Example 6 The difference between this embodiment and Embodiment 1 is that sodium hydroxide is used instead of ammonia to make the flexural strength of the aerogel layer 0.5 MPa.

[0062] Example 7 The difference between this embodiment and Embodiment 6 is that the thickness of the aerogel layer is 300 μm.

[0063] Example 8 The difference between this embodiment and Embodiment 6 is that the thickness of the aerogel layer is 500 μm.

[0064] Example 9 The difference between this embodiment and Embodiment 6 is that the thickness of the aluminum foil layer is 80 μm and the thickness of the aerogel layer is 100 μm.

[0065] Example 10 The difference between this embodiment and Embodiment 6 is that the thickness of the aluminum foil layer is 40 μm and the thickness of the aerogel layer is 500 μm.

[0066] Example 11 The difference between this embodiment and Embodiment 6 is that the thickness of the PET layer is 6 μm and the thickness of the aerogel layer is 500 μm.

[0067] Example 12 The difference between this embodiment and Embodiment 6 is that the thickness of the PET layer is 30 μm and the thickness of the aerogel layer is 100 μm.

[0068] Example 13 The difference between this embodiment and Embodiment 1 is that the aerogel layer is disposed on the side of the PET layer away from the nylon layer.

[0069] Comparative Example 1 The difference between this comparative example and Example 1 is that there is no aerogel layer in the aluminum-plastic film.

[0070] Comparative Example 2 The difference between this comparative example and Example 1 is that, in the preparation of the aerogel layer, the content of tetraethyl orthosilicate in the mixture was adjusted to 45 wt%, and the mass ratio of ethanol, deionized water and hydrochloric acid remained at 120:80:0.5, so that the average pore size of the aerogel layer was 5 nm.

[0071] Comparative Example 3 The difference between this comparative example and Example 1 is that, in the preparation of the aerogel layer, the content of tetraethyl orthosilicate in the mixture was adjusted to 3wt%, and the mass ratio of ethanol, deionized water and hydrochloric acid remained at 120:80:0.5, so that the average pore size of the aerogel layer was 150nm.

[0072] Comparative Example 4 The difference between this comparative example and Example 1 is that the amount of ammonia added during the preparation of the aerogel layer was controlled, and the pH of the mixture was adjusted to 6.5 so that the porosity of the aerogel layer was 95%.

[0073] Comparative Example 5 The difference between this comparative example and Example 1 is that, during the preparation of the aerogel layer, the amount of ammonia added was controlled, and the pH of the mixture was adjusted to 4 so that the porosity of the aerogel layer was 60%.

[0074] Comparative Example 6 The difference between this comparative example and Example 1 is that urea was used instead of ammonia to make the flexural strength of the aerogel layer 0.3 MPa.

[0075] Comparative Example 7 The difference between this comparative example and Example 6 is that the thickness of the aerogel layer is 550 μm.

[0076] Comparative Example 8 The difference between this comparative example and Example 6 is that the thickness of the aerogel layer is 30 μm.

[0077] Comparative Example 9 The difference between this comparative example and Example 6 is that the thickness of the aerogel layer is 12 μm.

[0078] Comparative Example 10 The difference between this comparative example and Example 6 is that the thickness of the PET layer is 6 μm and the thickness of the aerogel layer is 550 μm.

[0079] In this invention, the aluminum-plastic films in Examples 1-13 and Comparative Examples 1-10 were subjected to performance tests.

[0080] Please refer to Table 1. In one embodiment of the present invention, the formability of the aluminum-plastic film is measured, for example. Specifically, the aluminum-plastic film is cut into 10 standard samples of the same size, and each of the 10 samples is subjected to a fixed depth stamping operation of 8mm. After forming, each sample is observed to see if cracks are generated, and the number of samples with cracks is counted.

[0081] Please refer to Table 1. In one embodiment of the present invention, the thermal insulation performance of an aluminum-plastic film is measured, for example. Specifically, two aluminum-plastic films are overlapped with their aerogel layers facing each other. The temperature-sensing end of a thermocouple is inserted between the two films, and the entire assembly of the two films is heat-sealed to enclose the temperature-sensing end of the thermocouple between the aerogel layers. The sealed assembly is then placed in a 150°C oven for 1 hour, and the temperature detected by the thermocouple is recorded.

[0082] Table 1 shows the parameters and test results of the aluminum-plastic films in Examples 1-13 and Comparative Examples 1-10.

[0083] Please refer to Table 1. By comparing Example 1, Example 13 and Comparative Example 1, it can be seen that after adding a heat insulation layer to the aluminum-plastic film, although the formability of the aluminum-plastic film is not optimal, the heat insulation performance is significantly improved.

[0084] Please refer to Table 1. Comparing Examples 1-3 and Comparative Examples 2-3, it can be seen that by controlling the average pore size of the insulation layer to 10nm-100nm, the insulation performance of the aluminum-plastic film can be improved.

[0085] Please refer to Table 1. By comparing Example 1, Example 4-5 and Comparative Example 4-5, it can be seen that by controlling the porosity of the insulation layer to 70%-90%, the insulation performance and formability of the aluminum-plastic film can be improved.

[0086] Please refer to Table 1. By comparing Example 1, Example 6 and Comparative Example 6, it can be seen that by controlling the bending strength of the heat insulation layer to 0.4 MPa or above, the formability of the aluminum-plastic film can be improved.

[0087] Please refer to Table 1. Comparing Examples 6-8 and Comparative Examples 7-8, it can be seen that by controlling the thickness of the insulation layer to 100μm-500μm, the aluminum-plastic film can have both good insulation performance and formability.

[0088] Please refer to Table 1. Comparing Examples 6-9 and Comparative Examples 7-9, it can be seen that when the thickness ratio of the insulation layer to the barrier layer is greater than 16.67:1, the formability of the aluminum-plastic film is poor; when the thickness ratio of the insulation layer to the barrier layer is less than 1.25:1, the insulation performance of the aluminum-plastic film is poor. Therefore, by controlling the thickness ratio of the insulation layer to the barrier layer to be (1.25-16.67):1, the aluminum-plastic film can have both good insulation effect and mechanical strength.

[0089] Please refer to Table 1. Comparing Examples 10-12 and Comparative Examples 9-10, it can be seen that when the thickness ratio of the heat insulation layer to the anti-pollution layer is greater than 83.3:1, the formability of the aluminum-plastic film is poor; when the thickness ratio of the heat insulation layer to the anti-pollution layer is less than 3.3:1, the heat insulation performance of the aluminum-plastic film is poor. Therefore, by controlling the thickness ratio of the heat insulation layer to the anti-pollution layer to be (3.33-83.33):1, the aluminum-plastic film can have both good heat insulation effect and mechanical strength.

[0090] In summary, this invention proposes an aluminum-plastic film, its preparation method, and its application. By forming a heat-insulating layer on the aluminum-plastic film, the heat insulation performance of the battery can be improved, preventing heat from spreading from the battery to adjacent batteries. This avoids a chain reaction of battery pack failure caused by thermal runaway of a single battery, thus improving safety. Moreover, the aluminum-plastic film, its preparation method, and its application proposed in this invention can simultaneously achieve both heat insulation performance and mechanical strength.

[0091] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0092] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. An aluminum-plastic film comprising a heat-seal layer, a barrier layer, a protective layer, and a contamination prevention layer, characterized in that, The aluminum-plastic film also includes a heat insulation layer, which is disposed on either side of the anti-pollution layer.

2. The aluminum laminate film according to claim 1, characterized by The material of the insulation layer includes silica aerogel.

3. The AIF according to claim 1, wherein, The heat insulation layer has a porous structure, and the average pore size of the heat insulation layer is 10nm-100nm.

4. The aluminum laminate film according to claim 1, wherein The porosity of the insulation layer is 70%-90%.

5. The AIF according to claim 1, wherein, The thickness of the insulation layer is 100μm-500μm.

6. The aluminum laminate film according to claim 1, wherein The thickness ratio of the heat insulation layer to the barrier layer is (1.25-16.67):

1.

7. The aluminum laminate film according to claim 1, wherein The thickness ratio of the heat insulation layer to the anti-pollution layer is (3.33-83.33):

1.

8. The aluminum laminate film according to claim 1, wherein The flexural strength of the insulation layer is greater than 0.4 MPa.

9. A method for preparing an aluminum-plastic film as described in any one of claims 1-8, characterized in that, At least the following steps are included: The heat-sealing layer, barrier layer, and protective layer are sequentially laminated to obtain an intermediate; The sol is coated onto one side of the anti-fouling layer and then dried to form a heat insulation layer on the anti-fouling layer; as well as The heat insulation layer or the anti-pollution layer is combined with the protective layer to obtain an aluminum-plastic film.

10. The method for preparing aluminum-plastic film according to claim 9, characterized in that, The sol is obtained by hydrolysis and condensation of silanol salts.

11. A battery, characterized by It includes at least the aluminum-plastic film according to any one of claims 1-8, or the aluminum-plastic film obtained by the preparation method according to any one of claims 9-10.

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