Aluminum-plastic film suitable for solid-state battery

Abstract

The utility model discloses an aluminum-plastic film suitable for a solid-state battery, which sequentially comprises a first metal film layer, a first adhesive layer, a first polypropylene film layer, a second adhesive layer, a second metal film layer, a third adhesive layer and a second polypropylene film layer from outside to inside, and the second metal film layer is an aluminum foil. According to the utility model, the stainless steel foil or the copper foil is used as the protective layer of the aluminum-plastic film, so that the purposes of improving the heat resistance, the puncture resistance and the high moisture resistance of the aluminum-plastic film can be achieved by utilizing the characteristics of high strength, puncture resistance, high moisture resistance, high heat conductivity coefficient and the like of stainless steel and copper; and meanwhile, the first polypropylene film layer is arranged between the first metal film layer and the second metal film layer, so that the effect of improving the moisture resistance of the aluminum-plastic film can be achieved through the characteristic of low water vapor transmittance of polypropylene.

Description

Technical Field

[0001] The utility model relates to the technical field of battery materials, and particularly relates to an aluminum-plastic film applicable to a solid-state battery. Background Art

[0002] In the manufacturing process of soft-pack lithium-ion batteries, it is necessary to isolate the battery cell from the external environment through heat sealing of the aluminum-plastic film to ensure the normal charging and discharging environment of the lithium battery. The aluminum-plastic film is usually composed of an outer protective layer (nylon film, polyester film), an intermediate aluminum foil layer, and an inner heat-sealing layer (polypropylene film).

[0003] The solid-state battery has no liquid electrolyte. During use, high temperature and pressure are required. To solve the problems of heat resistance, water vapor barrier property, and impact resistance of the solid-state battery, higher requirements for heat conduction, moisture resistance, puncture resistance, etc. are put forward for the soft-pack aluminum-plastic film. To improve the related properties of the aluminum-plastic film, the main method currently adopted is to add heat-conducting fillers such as heat-conducting carbon powder and heat-conducting graphite to the protective layer and the heat-sealing layer. Although this method can improve the heat resistance of the aluminum-plastic film, since the heat-conducting filler is incompatible with the protective layer and the heat-sealing layer, it will inevitably affect the bonding effect between the protective layer and the aluminum foil, and also affect the bonding effect between the heat-sealing layers during heat sealing of the aluminum-plastic film, resulting in a decrease in the top-side seal tensile strength of the soft-pack battery cell; moreover, the used heat-conducting filler does not rule out having a certain electrical conductivity, and the heat-conducting filler with electrical conductivity will also affect the insulation performance of the aluminum-plastic film. Therefore, it is necessary to develop an aluminum-plastic film more suitable for solid-state batteries. Summary of the Utility Model

[0004] Aiming at the deficiencies of the existing technology, the utility model provides an aluminum-plastic film applicable to a solid-state battery, which can improve the heat resistance, high moisture barrier property, and puncture resistance of the aluminum-plastic film, so as to meet the use requirements of the solid-state battery.

[0005] To achieve the above object, the utility model adopts the following technical solutions:

[0006] An aluminum-plastic film applicable to a solid-state battery sequentially includes a first metal film layer, a first adhesive layer, a first polypropylene film layer, a second adhesive layer, a second metal film layer, a third adhesive layer, and a second polypropylene film layer from outside to inside. The first metal film layer is a stainless steel foil or a copper foil, and the second metal film layer is an aluminum foil. By using a stainless steel foil or a copper foil as the protective layer of the aluminum-plastic film, the characteristics of high strength, puncture resistance, high moisture barrier property, and high heat conduction coefficient of stainless steel and copper can be utilized to achieve the purpose of improving the heat resistance, puncture resistance, and high moisture barrier property of the aluminum-plastic film. At the same time, by arranging a first polypropylene film layer between the first metal film layer and the second metal film layer, the moisture barrier property of the aluminum-plastic film can be improved through the characteristic of low water vapor transmission rate of polypropylene.

[0007] As a preferred technical solution, the thickness of the first metal thin film layer is 15 - 30 μm.

[0008] As a preferred technical solution, the first adhesive layer, the second adhesive layer, and the third adhesive layer are all acid-modified polyolefin adhesives.

[0009] As a preferred technical solution, the thicknesses of the first adhesive layer, the second adhesive layer, and the third adhesive layer are all 2 - 3 μm.

[0010] As a preferred technical solution, the aluminum foil is an annealed 0-series 8 aluminum foil.

[0011] As a preferred technical solution, the thickness of the aluminum foil is 30 - 60 μm.

[0012] As a preferred technical solution, the first polypropylene thin film layer is co-extruded and cast formed by a first bonding layer, a first base material layer, and a second bonding layer, and the second polypropylene thin film layer is co-extruded and cast formed by a third bonding layer, a second base material layer, and a heat-sealing layer.

[0013] As a preferred technical solution, the first base material layer and the second base material layer are both elastomer-modified block polypropylene, the first bonding layer, the second bonding layer, and the third bonding layer are all maleic anhydride-modified polypropylene resins, and the heat-sealing layer is elastomer-modified polypropylene. The elastomer is an ethylene-propylene block copolymer or a propylene-butene block copolymer.

[0014] As a preferred technical solution, the thickness of the first polypropylene thin film layer is 10 - 40 μm.

[0015] As a preferred technical solution, the thickness of the second polypropylene thin film layer is 40 - 80 μm.

[0016] Compared with the prior art, the present utility model has obvious advantages and beneficial effects. Specifically, by using a stainless steel foil or a copper foil as the protective layer of the aluminum-plastic film, the characteristics of high strength, puncture resistance, high moisture barrier, and high thermal conductivity of stainless steel and copper can be utilized to achieve the purpose of improving the heat resistance, puncture resistance, and high moisture barrier of the aluminum-plastic film; at the same time, by arranging a first polypropylene thin film layer between the first metal thin film layer and the second metal thin film layer and bonding the first polypropylene thin film layer to the first metal layer, the effect of improving the moisture barrier of the separator can be achieved through the low water vapor transmission rate characteristic of polypropylene.

[0017] To more clearly illustrate the structural features, technical means, and the specific purposes and functions achieved by the present utility model, the following further details the present utility model with reference to the drawings and specific embodiments: Description of the Drawings

[0018] Figure 1 is a schematic cross-sectional structure diagram of an embodiment of the present utility model;

[0019] Figure 2 is a schematic cross-sectional structure diagram of the first polypropylene film layer of an embodiment of the present utility model;

[0020] Figure 3 is a schematic cross-sectional structure diagram of the second polypropylene film layer of an embodiment of the present utility model.

[0021] Explanation of the attached drawing reference numerals:

[0022] 10. First metal film layer 20. First adhesive layer 30. First polypropylene film layer

[0023] 31. First bonding layer 32. First base material layer 33. Second bonding layer

[0024] 40. Second adhesive layer 50. Second metal film layer 60. Third adhesive layer

[0025] 70. Second polypropylene film layer 71. Third bonding layer 72. Second base material layer

[0026] 73. Heat-sealing layer. Detailed implementation manners

[0027] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the indicated position or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0028] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0029] Such as Figures 1 - 3As shown in the figure, an aluminum-plastic film applicable to a solid-state battery includes, from outside to inside, a first metal film layer 10, a first adhesive layer 20, a first polypropylene film layer 30, a second adhesive layer 40, a second metal film layer 50, a third adhesive layer 60, and a second polypropylene film layer 70. The first metal film layer 10 is a stainless steel foil or a copper foil, and the second metal film layer 50 is an aluminum foil.

[0030] In the present utility model, the thickness of the first metal film layer 10 is 15 - 30 μm. The thicknesses of the first adhesive layer 20, the second adhesive layer 40, and the third adhesive layer 60 are all 2 - 3 μm. The thickness of the aluminum foil is 30 - 60 μm. The thickness of the first polypropylene film layer 30 is 10 - 40 μm. The thickness of the second polypropylene film layer 70 is 40 - 80 μm.

[0031] Specifically, the first adhesive layer 20, the second adhesive layer 40, and the third adhesive layer 60 are all acid-modified polyolefin adhesives. The aluminum foil is an annealed 0-state 8-series aluminum foil. The first polypropylene film layer 30 is formed by co-extrusion casting of a first bonding layer 31, a first substrate layer 32, and a second bonding layer 33. The second polypropylene film layer 70 is formed by co-extrusion casting of a third bonding layer 71, a second substrate layer 72, and a heat-sealing layer 73. The first substrate layer 32 and the second substrate layer 72 are both elastomer-modified block polypropylenes. The first bonding layer 31, the second bonding layer 33, and the third bonding layer 71 are all maleic anhydride-modified polypropylene resins. The heat-sealing layer 73 is an elastomer-modified polypropylene. The elastomer is an ethylene-propylene block copolymer or a propylene-butene block copolymer.

[0032] In the present utility model, the mechanical properties of the stainless steel foil are: tensile strength 200 - 500 MPa / 5 mm, elongation at break 12% - 40%; the grade of the stainless steel is SUS304 or SUS316; the thermal conductivity of the stainless steel is 35 - 65 W / (mK). The mechanical properties of the copper foil are: tensile strength 200 - 400 MPa / 15 mm, elongation at break 12% - 40%. The thermal conductivity is 360 - 450 W / (mK).

[0033] In summary, the present utility model uses a stainless steel foil or a copper foil as the first metal film layer 10 and adopts the first metal film as the protective layer of the outer layer of the aluminum-plastic film, so as to exert the characteristics of high strength, high puncture resistance, high moisture barrier, high thermal conductivity, etc. of the metal material, and achieve the purpose of improving the heat resistance, moisture barrier, puncture resistance, etc. of the aluminum-plastic film; by using the first polypropylene film layer 30 with acid-modified polypropylene on both sides to bond the first metal layer and the first polypropylene film layer 30, the characteristic of low water vapor transmission rate of the first polypropylene film layer 30 can be utilized to improve the moisture barrier property of the separator.

[0034] The above are only the preferred embodiments of the present utility model, and are not intended to limit the present utility model. Therefore, any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the actual technology of the present utility model still fall within the scope of the technical solution of the present utility model.

Claims

1. An aluminum-plastic film applicable to a solid-state battery, characterized in that, It sequentially includes a first metal thin film layer, a first adhesive layer, a first polypropylene thin film layer, a second adhesive layer, a second metal thin film layer, a third adhesive layer and a second polypropylene thin film layer from outside to inside. The first metal thin film layer is a stainless steel foil or a copper foil, and the second metal thin film layer is an aluminum foil.

2. The aluminum-plastic film applicable to a solid-state battery according to claim 1, wherein The thickness of the first metal thin film layer is 15 - 30 μm.

3. The aluminum-plastic film applicable to a solid-state battery according to claim 1, wherein The first adhesive layer, the second adhesive layer and the third adhesive layer are all acid-modified polyolefin adhesives.

4. The aluminum-plastic film applicable to a solid-state battery according to claim 1 or 3, characterized in that, The thicknesses of the first adhesive layer, the second adhesive layer and the third adhesive layer are all 2 - 3 μm.

5. The aluminum-plastic film applicable to a solid-state battery according to claim 1, wherein, The aluminum foil is an annealed 0-state 8-series aluminum foil.

6. The aluminum-plastic film applicable to a solid-state battery according to claim 1 or 5, characterized in that, The thickness of the aluminum foil is 30 - 60 μm.

7. The aluminum-plastic film applicable to a solid-state battery according to claim 1, wherein The first polypropylene thin film layer is co-extruded and cast formed by a first bonding layer, a first substrate layer and a second bonding layer, and the second polypropylene thin film layer is co-extruded and cast formed by a third bonding layer, a second substrate layer and a heat-sealing layer.

8. The aluminum-plastic film applicable to a solid-state battery according to claim 7, wherein The first substrate layer and the second substrate layer are both elastomer-modified block polypropylene, the first bonding layer, the second bonding layer and the third bonding layer are all maleic anhydride-modified polypropylene resins, and the heat-sealing layer is elastomer-modified polypropylene.

9. The aluminum-plastic film applicable to a solid-state battery according to claim 1, wherein The thickness of the first polypropylene thin film layer is 10 - 40 μm.

10. The aluminum-plastic film applicable to a solid-state battery according to claim 1, characterized in that, The thickness of the second polypropylene thin film layer is 40 - 80 μm.

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