Soft package and solid-state battery packaging steel plastic film and preparation method thereof

Abstract

The application belongs to the technical field of lithium battery packaging materials, and particularly relates to a soft package and solid-state battery packaging steel-plastic film and a preparation method thereof. The soft package and solid-state battery packaging steel-plastic film comprises, from inside to outside, a polypropylene layer, a hot melt adhesive layer, an ultrathin steel foil layer, a hot melt adhesive layer and a polyethylene terephthalate layer; wherein the ultrathin steel foil layer is an ultrathin steel foil which is etched by reaction particles on both sides. The soft package and solid-state battery packaging steel-plastic film improves the problem that the existing aluminum-plastic film cannot meet the performance thickness requirement of the market for battery soft package packaging, has good packaging effect, is light in weight, can prevent the penetration of air, especially oxygen, has good deformation capacity and strength, can prevent the damage of the outside to the battery cell, and ensures the service life of the battery cell.

Description

Technical Field

[0001] This application belongs to the field of lithium battery packaging material technology, and particularly relates to a steel-plastic film for soft-pack and solid-state battery packaging and its preparation method. Background Technology

[0002] Polymer lithium batteries, with their high energy density and excellent safety performance, are the primary energy providers for digital and IT products. With the development of mobile or small-to-medium-sized energy storage devices and the increasing demand for irregularly shaped and irregularly configured power lithium batteries, pouch batteries and solid-state batteries have become important development directions. In recent years, advancements in pouch battery and solid-state battery technologies have led to a surge in demand for pouch batteries and mass production of solid-state batteries, which is expected to drive explosive growth in the demand for corresponding key materials.

[0003] Currently, pouch cells and solid-state batteries still primarily use aluminum-plastic film as the main encapsulation material to seal and protect the battery cells. However, as pouch cell and solid-state battery manufacturers continue to increase energy density and battery capacity, they have more diverse requirements for the thickness and performance of encapsulation materials. Some requirements, such as reducing the thickness of aluminum foil to below 30µm, inevitably lead to a small amount of air seeping in, which can damage the physicochemical properties of the negative electrode and electrolyte. This reduces the barrier properties of the pouch material, allowing ambient gases and moisture to penetrate and corrode the battery cells, thus affecting the battery's lifespan. Summary of the Invention

[0004] In view of the fact that existing aluminum-plastic films cannot meet the market's performance and thickness requirements for battery pouch packaging, and to prevent impurities from penetrating and damaging the physicochemical properties of electrodes and electrolytes, and to improve the barrier properties of pouch batteries or solid-state batteries, this application provides a steel-plastic film for pouch and solid-state battery packaging and its preparation method.

[0005] In a first aspect, this application provides a steel-plastic film for packaging soft-pack and solid-state batteries, employing the following technical solution:

[0006] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, a hot melt adhesive layer, and a polyethylene terephthalate layer; wherein the ultra-thin steel foil layer is an ultra-thin steel foil with reactive ion etching on both sides.

[0007] By adopting the above technical solutions, the encapsulation of soft-pack and solid-state batteries can improve battery heat dissipation and prevent battery overheating under discharge conditions. The steel-plastic film for soft-pack and solid-state battery encapsulation is composed of five layers bonded together. The outermost layer is a polyethylene terephthalate layer, which has good mechanical properties, high impact strength, good folding resistance, and low gas and water vapor permeability, exhibiting excellent barrier properties against gas, water, oil, and odors. Due to its chemical inertness, the polypropylene layer has better solvent and acid resistance. Through bonding with the hot melt adhesive layer, the electrolyte resistance of the steel-plastic film is improved. On this basis, the ultra-thin steel foil layer is subjected to double-sided reactive ion etching technology to form hydrogen bonds between layers, enhancing interlayer bonding strength. The double-sided coating of the steel foil can greatly improve the insulation and barrier properties of the steel-plastic film, improve the adhesion and corrosion resistance of the steel foil, and enhance the barrier effect against water and oxygen. The steel-plastic film encapsulation of soft-pack and solid-state batteries has good performance, is lightweight, can prevent the penetration of air, especially oxygen, and has good deformation ability and strength, which can prevent external damage to the battery cell.

[0008] In one specific implementation, the steel foil etching gas is selected from one of SF6, CF4, and CHF3.

[0009] By adopting the above technical solution and selecting fluorine-containing plasma gas as the etching gas, the steel foil undergoes double-sided reactive ion etching. This reacts with the high-energy etching particles in a short time, causing stronger hydrogen bonds or interactions such as CF or Si-F bonds to form on the surface of the steel foil. This improves the adhesion between layers and enhances the barrier properties of the steel-plastic film, ensuring that the ultra-thin steel foil layer will not come into contact with the electrolyte and cause corrosion.

[0010] In one specific implementation, the thickness of the ultrathin steel foil layer is 15-60 μm.

[0011] Setting a steel foil layer of a certain thickness can ensure good steel-plastic film encapsulation effect of solid-state battery packaging, prevent air penetration, and prevent external damage to the battery cell.

[0012] In one specific implementation, the thickness of the ultrathin steel foil layer is preferably 20-30 μm.

[0013] The optimal thickness of the ultra-thin steel foil layer ensures that the steel-plastic film encapsulation of soft-pack and solid-state batteries is effective, lightweight, and has good deformation capacity and strength, while effectively preventing external damage to the battery cells.

[0014] In one specific implementation, the hot melt adhesive in the hot melt adhesive layer is one of EVA, PA, PES, and PO, and the thickness of the hot melt adhesive layer is 1-5 μm.

[0015] By adopting the above technical solution and selecting a resin material with high adhesion, the hot melt adhesive has good adhesion and heat sealing performance, preventing the encapsulation film from being easily punctured by electrode metal burrs during encapsulation, which would lead to steel foil corrosion. Moreover, the hot melt adhesive has low cost, relatively small thickness, and good oxygen barrier effect.

[0016] In one specific implementation, the surface of the hot melt adhesive is etched by reactive ion etching, and the etching gas includes one of O2, O3, and CO2.

[0017] By performing reactive ion etching on the surface of hot melt adhesive, using oxygen-containing gas particles as the etching gas, which are easily ionized, the oxygen-containing ions react with a large amount of carbon on the surface of the hot melt adhesive to form chemical bonds or secondary bonds such as CO bonds. This increases the chemical interaction between the hot melt adhesive layer and adjacent layers, making the adhesion between layers stronger and improving the barrier properties of the steel-plastic film.

[0018] In one specific implementation, the thickness of the polypropylene layer is 12-20 μm; the thickness of the polyethylene terephthalate film is 10-30 μm.

[0019] By using an outermost and innermost layer of a certain thickness, the steel-plastic film possesses excellent mechanical properties, high impact strength, good folding resistance, and excellent barrier properties. On the other hand, the inner polypropylene layer of a certain thickness has better solvent and acid resistance, which improves the electrolyte resistance of the steel-plastic film. Together, they ensure the barrier properties and extend the service life of the steel-plastic film.

[0020] In one specific implementation, the hot melt adhesive layer comprises EVA and modified carbon fiber, wherein the mass ratio of EVA to modified carbon fiber is 3-5:1.

[0021] The hot melt adhesive layer is made by mixing EVA and modified carbon fiber, which enhances the roughness of the EVA surface, giving it better wettability and adhesion. The addition of modified carbon fiber gives the steel-plastic film good mechanical properties, improves the material's corrosion resistance and stability, and can also reduce the problem of adhesive overflow during the hot-pressing encapsulation process.

[0022] In one specific implementation scheme, the method for preparing the modified carbon fiber includes: taking concentrated nitric acid with a mass concentration of 33-68%, heating it to 60-80°C, adding carbon fiber for oxidation etching for 2-4 hours, then washing it with tetrahydrofuran 3-5 times, and drying it to obtain oxidized carbon fiber.

[0023] Ethanol and deionized water were mixed at a mass ratio of 1:(1.5-3), and a silane coupling agent was added. The mixture was stirred and mixed thoroughly. The oxidized carbon fiber was then dispersed in the mixture, ultrasonicated, filtered, and dried to obtain modified carbon fiber.

[0024] Oxidizing the carbon fiber surface with concentrated nitric acid increases the surface polarity and roughness of the fiber, improving bonding performance. It also makes the carbon-carbon bonds on the carbon fiber surface more active, which is more conducive to grafting silane coupling agents, resulting in higher bonding strength with EVA, improving the mechanical properties of the material, and reducing glue overflow.

[0025] Secondly, this application provides a method for preparing a steel-plastic film for soft-pack and solid-state battery encapsulation, employing the following technical solution:

[0026] A method for preparing a steel-plastic film for packaging soft-pack and solid-state batteries includes the following steps:

[0027] (1) Reactive ion etching is performed on both sides of the steel foil using reactive ion etching technology;

[0028] (2) Perform reactive ion etching on the surface of the hot melt adhesive;

[0029] (3) Polypropylene and hot melt adhesive are preheated and laminated under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and laminated under double pressure. The preheated layer is then laminated under double pressure hot rollers and formed by double pressure hot rollers.

[0030] (4) Forced air convection cooling and heat dissipation, then winding and obtaining the finished steel-plastic film.

[0031] Based on the properties and valence bond activity of both sides of the steel foil and the hot melt adhesive surface, different reactive ion beams are selected to etch the surface, combining the characteristics of different materials. This greatly improves the insulation and barrier properties of the steel-plastic film, enhances the adhesion and corrosion resistance of the steel foil, and strengthens the barrier effect against water and oxygen. Combined with preheating, double-pressure hot roller composite, and secondary double-pressure hot roller hot pressing, multi-step hot pressing is achieved, which can effectively improve the encapsulation effect and efficiency of the steel-plastic film. This allows for better encapsulation of the cells of pouch or solid-state batteries, providing better barrier and insulation properties, and improving the performance and safety of pouch or solid-state batteries.

[0032] In one specific implementation, the temperature of the double-pressure preheating roller is 80-120°C, the temperature of the double-pressure heating roller is 100-160°C, and the temperature of the secondary double-pressure heating roller is 130-180°C.

[0033] Under different temperature conditions, combined with the structural characteristics of different film layers, preheating and lamination are carried out, followed by hot roller lamination. Secondary double-pressure hot roller lamination can further improve the heat sealing performance of the material.

[0034] In one specific implementation scheme, the combined pressure of the dual-pressure preheating roller, the dual-pressure heating roller, and the secondary dual-pressure heating roller is 1000-2000Kg when the air pressure is 0.5MPa.

[0035] By using a composite pressure range under a certain air pressure, the material's impermeability is further improved, and it also has good deep-drawing performance, preventing material defects such as impact deformation.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. Pouch and solid-state battery encapsulation improves battery heat dissipation and prevents overheating during discharge. The steel-plastic film used for pouch and solid-state battery encapsulation consists of five layers bonded together. The outermost layer is a polyethylene terephthalate (PET) layer, which possesses excellent mechanical properties, high impact strength, good folding resistance, and low gas and water vapor permeability, exhibiting excellent barrier properties against gas, water, oil, and odors. The polypropylene layer, due to its chemical inertness, offers better solvent and acid resistance. Through bonding with the hot melt adhesive layer, it enhances the electrolyte resistance of the steel-plastic film.

[0038] Building upon this foundation, the ultra-thin steel foil layer undergoes double-sided reactive ion etching (RIE) to form hydrogen bonds between layers, enhancing interlayer adhesion strength. Double-sided lamination of the steel foil significantly improves the insulation and barrier properties of the steel-plastic film, enhances the adhesion and corrosion resistance of the steel foil, and strengthens its ability to block water and oxygen. For soft-pack and solid-state battery encapsulation, the steel-plastic film offers excellent encapsulation performance, is lightweight, effectively prevents air, especially oxygen, from penetrating, and possesses good deformation capacity and strength, preventing external damage to the battery cell.

[0039] 2. By selecting fluorine-containing plasma gas as the etching gas, double-sided reactive ion etching of the steel foil is achieved. The reaction with the high-energy etching particles in a short time causes stronger hydrogen bonds or interaction forces, such as CF or Si-F bonds, to form on the surface of the steel foil. This improves the adhesion between layers and enhances the barrier properties of the steel-plastic film, ensuring that the ultra-thin steel foil layer will not come into contact with the electrolyte and cause corrosion.

[0040] 3. Based on the properties and valence bond activity of both sides of the steel foil and the hot melt adhesive surface, different reactive ion beams are selected to etch the surface. This allows specific types of ion beams to combine with the characteristics of the steel foil material, greatly improving the insulation and barrier properties of the steel-plastic film, enhancing the adhesion and corrosion resistance of the steel foil, and strengthening the barrier effect against water and oxygen. Combined with preheating, double-pressure hot roller composite, and secondary double-pressure hot roller hot pressing, multi-step hot pressing is achieved, which can effectively improve the encapsulation effect and efficiency of the steel-plastic film. This allows for better encapsulation of the solid-state battery cell, providing better barrier and insulation properties, and improving the performance and safety of the solid-state battery. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of a soft-pack and solid-state battery encapsulation steel-plastic film according to Embodiment 1 of this application.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Polypropylene layer; 2. Hot melt adhesive layer; 3. Ultra-thin steel foil layer; 4. Polyethylene terephthalate layer. Detailed Implementation

[0044] The present application will be further described in detail below with reference to the embodiments.

[0045] Some of the raw materials used in the preparation examples and embodiments: polypropylene was purchased from Ningbo Huixiang Plastic Co., Ltd.; polyethylene terephthalate grade: GN071; steel foil was purchased from Wuxi Hongxin Special Steel Co., Ltd.; EVA was purchased from Zhengzhou Xinchun Lining Hot Melt Adhesive Co., Ltd.; PA was purchased from Shanghai Beidaer New Material Co., Ltd.; PES grade: E2010; carbon fiber was purchased from Jiangxi Shuobang New Material Technology Co., Ltd.

[0046] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available products.

[0047] Preparation Example

[0048] Preparation Example 1

[0049] Take 100 ml of concentrated nitric acid with a mass concentration of 33%, heat it to 60°C, add 8 g of carbon fiber and oxidize and etch it for 2 hours. Then wash it three times with 80 ml of tetrahydrofuran and dry it to obtain oxidized carbon fiber.

[0050] Ethanol and deionized water were mixed at a mass ratio of 1:1.5. 150 ml of the mixture was taken and 10 g of silane coupling agent was added. The mixture was stirred and mixed well. The oxidized carbon fiber was dispersed in the mixture, sonicated, filtered and dried to obtain modified carbon fiber.

[0051] Weigh out the modified carbon fiber and EVA according to the mass ratio of EVA to modified carbon fiber of 3:1, and add them to a high-speed mixer. The speed is 300 r / min and the stirring time is 30 min. Stir until uniform. Set the temperature of the extruder to 430℃ to melt and extrude the raw material resin to obtain hot melt adhesive.

[0052] Preparation Example 2

[0053] Take 100 ml of concentrated nitric acid with a mass concentration of 33%, heat it to 60°C, add 8 g of carbon fiber and oxidize and etch it for 2 hours. Then wash it three times with 80 ml of tetrahydrofuran and dry it to obtain oxidized carbon fiber.

[0054] Ethanol and deionized water were mixed at a mass ratio of 1:1.5. 150 ml of the mixture was taken and 10 g of silane coupling agent was added. The mixture was stirred and mixed well. The oxidized carbon fiber was dispersed in the mixture, sonicated, filtered and dried to obtain modified carbon fiber.

[0055] Weigh out the modified carbon fiber and EVA according to the mass ratio of EVA to modified carbon fiber of 5:1, and add them to a high-speed mixer. The speed is 300 r / min and the stirring time is 30 min. Stir until uniform. Set the temperature of the extruder to 430℃ to melt and extrude the raw material resin to obtain hot melt adhesive.

[0056] Preparation Example 3

[0057] Take 100 ml of concentrated nitric acid with a mass concentration of 68%, heat it to 80°C, add 8 g of carbon fiber and oxidize and etch it for 4 h, then wash it 5 times with 80 ml of tetrahydrofuran, and dry it to obtain oxidized carbon fiber.

[0058] After mixing ethanol and deionized water at a mass ratio of 1:3, take 150 ml of the mixture, add 10 g of silane coupling agent, stir and mix well, disperse the oxidized carbon fiber in the mixture, sonicate, filter and dry to obtain modified carbon fiber.

[0059] Weigh out the modified carbon fiber and EVA according to the mass ratio of EVA to modified carbon fiber of 3:1, and add them to a high-speed mixer. The speed is 300 r / min and the stirring time is 30 min. Stir until uniform. Set the temperature of the extruder to 430℃ to melt and extrude the raw material resin to obtain hot melt adhesive.

[0060] Preparation Example 4

[0061] Take 100 ml of concentrated nitric acid with a mass concentration of 33%, heat it to 60°C, add 8 g of carbon fiber and oxidize and etch it for 2 hours. Then wash it three times with 80 ml of tetrahydrofuran and dry it to obtain oxidized carbon fiber.

[0062] Ethanol and deionized water were mixed at a mass ratio of 1:1.5. 150 ml of the mixture was taken and 10 g of silane coupling agent was added. The mixture was stirred and mixed well. The oxidized carbon fiber was dispersed in the mixture, sonicated, filtered and dried to obtain modified carbon fiber.

[0063] Weigh the modified carbon fiber and EVA according to the mass ratio of EVA to modified carbon fiber of 3:2, and add them to a high-speed mixer. The speed is 300 r / min and the stirring time is 30 min. Stir until uniform. Set the temperature of the extruder to 430℃ to melt and extrude the raw material resin to obtain hot melt adhesive.

[0064] Example

[0065] Example 1

[0066] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is PES with a thickness of 1 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0067] 1. Double-sided steel foil: First, CHF3 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the CHF3 flow rate is 180sccm.

[0068] (2) Hot melt adhesive surface: O3 is used as working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O3 flow rate is 300sccm.

[0069] (3) At a temperature of 80°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 100°C and the temperature of the secondary double pressure hot roller is 130°C.

[0070] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0071] Example 2

[0072] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0073] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0074] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0075] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0076] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0077] Example 3

[0078] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 20 μm, the hot melt adhesive in the hot melt adhesive layer is PA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 30 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0079] (1) Double-sided steel foil: First, CF4 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the flow rate of CF4 is 180sccm.

[0080] (2) Hot melt adhesive surface: CO2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the CO2 flow rate is 300sccm.

[0081] (3) At a temperature of 120°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 2000 kg when the air pressure is 0.5 MPa. The temperature of the double pressure hot roller is 160°C and the temperature of the secondary double pressure hot roller is 180°C.

[0082] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0083] Example 4

[0084] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 20 μm.

[0085] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0086] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0087] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0088] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0089] Example 5

[0090] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 30 μm.

[0091] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0092] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0093] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0094] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0095] Example 6

[0096] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 45 μm.

[0097] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0098] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0099] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0100] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0101] Example 7

[0102] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 60 μm.

[0103] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0104] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0105] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0106] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0107] Example 8

[0108] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 10 μm.

[0109] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0110] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0111] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0112] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0113] Example 9

[0114] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0115] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0116] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0117] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200 kg when the air pressure is 0.5 MPa. The temperature of the double pressure hot roller is 200°C and the temperature of the secondary double pressure hot roller is 150°C.

[0118] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0119] Example 10

[0120] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0121] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0122] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0123] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. Subsequently, the preheated layer is composited under double pressure and hot-pressed by double pressure rollers. The composite pressure of the double pressure preheating roller, double pressure hot roller, and secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C.

[0124] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0125] Example 11

[0126] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0127] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0128] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0129] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure roller, and the secondary double pressure roller is 800 kg when the air pressure is 0.5 MPa. The temperature of the double pressure roller is 140°C and the temperature of the secondary double pressure roller is 150°C.

[0130] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0131] Example 12

[0132] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0133] (1) Double-sided steel foil: Ar2 was used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power was 5kW, the processing time was 80s, and the Ar2 flow rate was 180sccm.

[0134] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0135] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. Subsequently, the preheated layer is composited under double pressure and hot roller, and then hot-pressed and formed by a second double pressure and hot roller. Wherein, the composite pressure of the double pressure preheating roller, the double pressure and the second double pressure and hot roller is 1200Kg when the air pressure is 0.5MPa; the temperature of the double pressure and hot roller is 140°C and the temperature of the second double pressure and hot roller is 150°C.

[0136] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0137] Example 13

[0138] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is the hot melt adhesive obtained in Preparation Example 1 with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0139] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0140] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0141] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0142] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0143] Example 14

[0144] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is the hot melt adhesive obtained in Preparation Example 2 with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0145] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0146] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0147] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0148] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0149] Example 15

[0150] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is the hot melt adhesive obtained in Preparation Example 3 with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0151] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0152] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0153] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0154] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0155] Example 16

[0156] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is the hot melt adhesive obtained in Preparation Example 4 with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0157] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0158] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0159] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0160] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0161] Comparative Example

[0162] Comparative Example 1

[0163] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0164] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0165] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0166] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure, steel foil is preheated, polyethylene terephthalate is preheated and composited, and then the preheated layer is composited under double pressure hot rollers and hot-pressed by a secondary double pressure hot roller; wherein, the composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa; the temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0167] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0168] Comparative Example 2

[0169] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0170] (1) Hot melt adhesive surface: O2 is used as working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0171] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The steel foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure hot roller, and the secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0172] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0173] Comparative Example 3

[0174] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, a polypropylene layer, a hot melt adhesive layer, an ultra-thin aluminum foil layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin aluminum foil layer has a thickness of 15 μm.

[0175] (1) Double-sided aluminum foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0176] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0177] (3) At a temperature of 100°C, polypropylene and hot melt adhesive are preheated and composited under double pressure. The aluminum foil is preheated, and then hot melt adhesive and polyethylene terephthalate are preheated and composited under double pressure. The preheated layer is then composited under double pressure rollers and hot-pressed through a secondary double pressure roller. The composite pressure of the double pressure preheating roller, the double pressure roller, and the secondary double pressure roller is 1200 kg when the air pressure is 0.5 MPa. The temperature of the double pressure roller is 140°C and the temperature of the secondary double pressure roller is 150°C.

[0178] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0179] Comparative Example 4

[0180] A steel-plastic film for packaging soft-pack and solid-state batteries comprises, from the inside out, an ultra-thin steel foil layer, a hot melt adhesive layer, and a polyethylene terephthalate layer; wherein, in this steel-plastic film, the polypropylene layer has a thickness of 12 μm, the hot melt adhesive in the hot melt adhesive layer is EVA with a thickness of 5 μm, the polyethylene terephthalate layer has a thickness of 10 μm, and the ultra-thin steel foil layer has a thickness of 15 μm.

[0181] (1) Double-sided steel foil: First, SF6 is used as the working gas to perform reactive ion etching on both sides of the steel foil. The plasma discharge power is 5kW, the processing time is 80s, and the SF6 flow rate is 180sccm.

[0182] (2) Hot melt adhesive surface: O2 is used as the working gas to perform reactive ion etching on the hot melt adhesive surface. The plasma discharge power is 3kW, the processing time is 100s, and the O2 flow rate is 300sccm.

[0183] (3) The steel foil is preheated at a temperature of 100°C under double pressure preheating roller, and then hot melt adhesive and polyethylene terephthalate are double pressure preheated and composited. Subsequently, the preheated layer is composited with double pressure hot roller and hot-pressed by a secondary double pressure hot roller. The composite pressure of the double pressure preheating roller, double pressure hot roller, and secondary double pressure hot roller is 1200Kg when the air pressure is 0.5MPa. The temperature of the double pressure hot roller is 140°C and the temperature of the secondary double pressure hot roller is 150°C.

[0184] (4) Forced 8°C cold air convection cooling and heat dissipation, then rolled up to obtain the finished steel-plastic film.

[0185] Performance testing

[0186] The performance testing of the soft-pack and solid-state battery encapsulation steel-plastic film prepared in the examples and comparative examples was carried out using the following methods: a. Peel strength test: The test was conducted in accordance with the test method specified in GB / T2792-2014 "Test method for peel strength of pressure-sensitive adhesive tape at 180°"; wherein, peel angle: 180°, peel speed: 150mm / min.

[0187] b. Permeability test: Immersed in water at 60℃ for 14 days, no delamination occurred, and the weight change was less than 0.03 grams; c. Deep drawing performance: The deep drawing performance of the sample was tested according to Q / 320507LD001-2016 "Lithium Battery Packaging Aluminum-Plastic Film"; d. Heat sealing performance: Under the condition of heat sealing temperature of 200℃, the heat sealing strength reached more than 85N / 15mm. The comparison results are shown in Table 1 below:

[0188] Table 1 Performance Test Results

[0189]

[0190]

[0191] As shown in Table 1, the steel-plastic films for soft-pack and solid-state battery encapsulation obtained in the above embodiments all meet the requirements for thickness and performance of encapsulation materials in terms of peel strength, impermeability, deep drawing performance, and heat sealing performance.

[0192] Compared with Examples 2 and 5-8, the peel strength, impermeability, deep drawing performance, and heat sealing performance of the steel-plastic film for soft-pack and solid-state battery packaging prepared in Examples 5-8 are all superior to those of Example 2. It is believed that the thickness of the ultra-thin steel foil layer is preferably in the range of 20-30um, which makes the steel-plastic film for soft-pack and solid-state battery packaging have a good packaging effect, lighter weight, good deformation ability and strength, and effectively prevents external damage to the battery cell.

[0193] Comparing Examples 1-16 with Comparative Example 3, it can be seen that the peel strength, impermeability, deep drawing performance, and heat sealing performance of the steel-plastic film for soft-pack and solid-state battery packaging prepared in Examples 1-16 are all superior to those of Comparative Example 3. It is believed that the ultra-thin steel foil has excellent rigidity and corrosion resistance. By using reactive ion etching technology to perform reactive ion etching, hydrogen bonds are formed between layers, which improves the interlayer bonding strength. The steel-plastic film has excellent barrier properties, insulation and chemical stability.

[0194] Comparing Examples 2 and 12-16, it can be seen that the peel strength, impermeability, deep drawing performance, and heat sealing performance of the steel-plastic film for soft-pack and solid-state battery packaging prepared in Examples 12-16 are all superior to those of Example 2. It is believed that the hot melt adhesive layer, by mixing EVA and modified carbon fiber, enhances the roughness of the EVA surface, giving it better wettability and adhesion. Furthermore, the addition of modified carbon fiber endows the steel-plastic film with good mechanical properties and improves the material's corrosion resistance and stability. It also has good barrier and insulation properties, thus improving the performance and safety of solid-state batteries.

[0195] Comparing Example 2 and Example 11, it can be seen that the peel strength, impermeability, deep drawing performance, and heat sealing performance of the steel-plastic film for soft-pack and solid-state battery packaging prepared in Example 2 are all superior to those in Example 11. It is believed that compared with inert gas, by selecting fluorine-containing plasma gas as the etching gas, the steel foil can be subjected to double-sided reactive ion etching. The reaction with the high-energy etching particles in a short time causes stronger hydrogen bonds or interaction forces such as CF or Si-F bonds to be formed on the surface of the steel foil, which improves the adhesion between layers and enhances the barrier performance of the steel-plastic film, ensuring that the ultra-thin steel foil layer will not come into contact with the electrolyte and cause corrosion.

[0196] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A steel-plastic film for packaging soft-pack and solid-state batteries, characterized in that: From the inside out, it includes a polypropylene layer, a hot melt adhesive layer, an ultra-thin steel foil layer, another hot melt adhesive layer, and a polyethylene terephthalate layer; wherein, the ultra-thin steel foil layer is an ultra-thin steel foil etched on both sides by reactive particles; the thickness of the ultra-thin steel foil layer is 30um; The hot melt adhesive layer comprises EVA and modified carbon fiber in a mass ratio of 3-5:

1. The preparation method of the modified carbon fiber includes: taking concentrated nitric acid with a mass concentration of 33-68%, heating it to 60-80℃, adding carbon fiber for oxidation etching for 2-4 hours, then washing it with tetrahydrofuran 3-5 times, and drying it to obtain oxidized carbon fiber; mixing ethanol and deionized water in a mass ratio of 1:(1.5-3), adding silane coupling agent, stirring and mixing, dispersing the oxidized carbon fiber in it, ultrasonicating, filtering and drying to obtain modified carbon fiber.

2. The steel-plastic film for packaging soft-pack and solid-state batteries according to claim 1, characterized in that: The etching gas for the steel foil is selected from one of SF6, CF4, and CHF3.

3. The steel-plastic film for packaging soft-pack and solid-state batteries according to claim 1, characterized in that: The thickness of the hot melt adhesive layer is 1-5 μm.

4. The steel-plastic film for packaging soft-pack and solid-state batteries according to claim 1, characterized in that: The thickness of the polypropylene layer is 12-20 μm; the thickness of the polyethylene terephthalate film is 10-30 μm.

5. A method for preparing a steel-plastic film for packaging soft-pack and solid-state batteries according to any one of claims 1-4, characterized in that: The process includes the following steps: (1) Reactive ion etching is performed on both sides of the steel foil using reactive ion etching technology; (2) Reactive ion etching is performed on the surface of the hot melt adhesive; (3) Polypropylene and hot melt adhesive are double-pressed and preheated together, the steel foil is preheated, the hot melt adhesive and polyethylene terephthalate are double-pressed and preheated together, and then the above preheated layer is composited by double-pressed hot rollers and hot-pressed through a second double-pressed hot roller; (4) Forced air convection is used to cool and dissipate heat, and the film is wound up to obtain the finished steel-plastic film.

6. The method for preparing a steel-plastic film for soft-pack and solid-state battery encapsulation according to claim 5, characterized in that: The temperature of the dual-pressure preheating is 80-120℃, the temperature of the dual-pressure hot roller is 100-160℃, and the temperature of the secondary dual-pressure hot roller is 130-180℃.

7. The method for preparing a steel-plastic film for soft-pack and solid-state battery encapsulation according to claim 5, characterized in that: The combined pressure of the dual-pressure preheating, dual-pressure hot roller, and secondary dual-pressure hot roller is 1000-2000Kg.

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