Solid-state battery high-temperature-resistant aluminum-plastic film and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant aluminum-plastic film for a solid-state battery and a preparation method thereof, the aluminum-plastic film adopts a three-layer composite resin structure, the outer layer is modified polyamide, and the outer layer has anti-UV and anti-damp-heat performance; the middle layer is made of nano ceramic doped polyester, so that the puncture-resistant strength can be improved; and the inner layer is made of cross-linked polyolefin, has a self-repairing function and can improve the water and oxygen barrier property. The middle layer is provided with a containing groove with a fishbone-shaped carbon-based framework, the inner surface of the containing groove is provided with a high-temperature-resistant anti-corrosion flame-retardant layer and a hot melting bonding layer, and the corners of the outer layer are provided with transition areas and packaging areas. Electric field induction interlayer compounding and vacuum hot melting rotating torque forming processes are integrated in the preparation process, the interlayer bonding strength and the overall sealing performance are improved, and the packaging requirements of the solid-state battery in the high-temperature and complex environment are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state battery packaging, in particular to a high-temperature-resistant aluminum-plastic film for solid-state batteries and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the new energy industry, solid-state batteries gradually become the core development direction in the field of power batteries and energy storage due to their high energy density and safety. As a key packaging material for solid-state batteries, aluminum-plastic films need to meet multiple performance requirements such as high-temperature resistance, puncture resistance, water and oxygen barrier, humidity resistance, and UV resistance, in order to adapt to the high-temperature environment of solid-state batteries during charging and discharging cycles, especially in fast-charging scenarios, and the environmental adaptability of complex application scenarios such as outdoor energy storage.

[0003] In the prior art, the aluminum-plastic film for solid-state batteries mostly follows the three-layer structure of traditional lithium-ion batteries (outer substrate layer, middle aluminum foil layer, and inner heat-sealing layer), but there are significant performance shortfalls: first, the outer layer mostly uses ordinary polyamide or polyester materials, which are prone to aging and embrittlement under long-term UV irradiation, and easily absorb moisture in a high-humidity environment, leading to a decrease in water and oxygen barrier performance, and further causing the decomposition of electrolyte or oxidation of electrode materials inside the battery; second, the middle layer relies on pure aluminum foil or conventional polymers, which have insufficient puncture resistance, and are prone to damage during battery assembly and use due to external impact or internal electrode swelling, leading to safety hazards; third, the inner heat-sealing layer is mostly ordinary polyolefins, which do not have self-repairing function, and once micro-cracks occur, water and oxygen will continue to penetrate, and its high-temperature resistance is limited (usually resistant to temperatures below 120℃), making it difficult to adapt to the transient high-temperature environment of 150-200℃ during fast charging of solid-state batteries; in addition, the interlayer adhesion of existing aluminum-plastic films mostly relies on conventional adhesives, and the interlayer peeling force is easily affected by high temperatures, and the sealing performance of the packaging area is unstable, which cannot meet the reliability requirements of long-term cycling of solid-state batteries. Although there have been attempts to improve the high-temperature resistance of aluminum-plastic films by coating ceramic coatings in the current industry, they only focus on the flame retardation and corrosion resistance of a single coating, and do not form a synergistic optimization of multi-layer structure; there are also technologies that improve the shell flatness by improving the CPP layer formula, but they do not design the structure for the core requirements of high-temperature resistance, UV resistance, self-repairing, etc. of solid-state batteries. Therefore, the existing aluminum-plastic film cannot fully adapt to the performance requirements of solid-state batteries, and there is an urgent need for a new type of aluminum-plastic film with a multi-layer synergistic optimization structure, integrating high-temperature resistance, UV resistance, humidity resistance, puncture resistance, self-repairing, and high sealing performance. SUMMARY

[0004] The present application aims to provide a high-temperature-resistant aluminum-plastic film for solid-state batteries and a preparation method thereof to solve the technical problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions: The application discloses a high-temperature-resistant aluminum plastic film for solid-state batteries, which adopts a three-layer composite resin structure, wherein the outer layer is modified polyamide and has UV resistance and damp-heat resistance; the middle layer is nano-ceramic doped polyester and can improve puncture resistance; and the inner layer is cross-linked polyolefin and has a self-repairing function to improve water and oxygen barrier properties; a plurality of first protrusions are arranged at edges of the outer layer and the inner layer, a plurality of first grooves matched with the first protrusions are arranged at an edge of the middle layer; a plurality of second grooves are arranged at centers of the outer layer and the inner layer, and second protrusions matched with the second grooves are arranged at a center of the middle layer; the middle layer is formed by stamping to form a containing groove, a fishbone-shaped carbon base skeleton is laid on a groove bottom of the containing groove, and a high-temperature-resistant anti-corrosion flame-retardant layer and a hot melt adhesive layer are arranged on inner surfaces of the containing groove in a melting mode; a corner section of the outer layer comprises a transition area and an encapsulation area connected with each other, the inner surface of the transition area is provided with the high-temperature-resistant anti-corrosion flame-retardant layer and the hot melt adhesive layer, the inner surface of the encapsulation area is provided with a sealing adhesive layer, and two aluminum plastic film structures are encapsulated to form an outer shell of a battery pack through the sealing area.

[0006] Specifically, the application further discloses a preparation method of the high-temperature-resistant aluminum plastic film for solid-state batteries. Step 1: preparation of the outer layer of modified polyamide Polyamide resin, an anti-UV agent (benzotriazole) and an anti-hygrothermal agent (nano-silicon dioxide) are mixed at a mass ratio of 90:5:5, and then are put into a double-screw extruder to be melt-blended at 230-250 DEG C, and then are extruded through a T-shaped die and are shaped through a cooling roller to obtain an outer layer base material with a thickness of 15-20 microns, and then first protrusions are processed at edges of the base material and second grooves are processed at centers of the base material. Step 2: preparation of the middle layer of nano-ceramic doped polyester Polyester resin and nano-ceramic particles (aluminum nitride / aluminum oxide with a particle size of 50-100 nm) are mixed at a mass ratio of 85:15, are stirred uniformly in a high-speed mixer, and then are sent into an extruder to be melt-extruded at 260-280 DEG C, and then are prepared into a middle layer base material with a thickness of 25-30 microns through a flow casting method, first grooves are processed at edges of the base material, second protrusions are processed at centers of the base material, and the base material is stamped to form containing grooves. Step 3: laying of a fishbone-shaped carbon base skeleton Carbon nanotubes and phenolic resin are mixed at a mass ratio of 30:70 to prepare paste-like slurry, the fishbone-shaped carbon base skeleton is printed on a groove bottom of the containing groove through 3D printing technology, and then is cured at 120-150 DEG C for 2-3 hours. Step 4: preparation of a high-temperature-resistant anti-corrosion flame-retardant layer and a hot melt adhesive layer Aluminum hydroxide (flame retardant), epoxy resin (adhesive) are mixed in a mass ratio of 40:60 to prepare a high-temperature-resistant corrosion-resistant flame-retardant paste. Ethylene-vinyl acetate copolymer (EVA) is heated to 180-200℃ to melt and prepare a hot melt adhesive; through a double die coating machine, the high-temperature-resistant corrosion-resistant flame-retardant paste is first coated on the inner surface of the containing groove, dried at 80-100℃ for 1-1.5h to form a high-temperature-resistant corrosion-resistant flame-retardant layer, and then the hot melt adhesive is coated on the surface of the layer, and naturally cooled to room temperature to form a hot melt adhesive layer. Step 5: Preparation of inner layer cross-linked polyolefin The polyolefin resin, cross-linking agent (dicumyl peroxide), and self-repairing microcapsules (urea-formaldehyde resin wrapped isocyanate) are mixed in a mass ratio of 88:2:10, melted and blended at 180-200℃, and extruded to form an inner layer substrate with a thickness of 20-25μm. The first protrusion is processed on the edge of the substrate, and the second groove is processed in the center. Step 6: Electric field-induced interlayer compounding The outer layer 1, the middle layer, and the inner layer are placed in order, ensuring that the first protrusion matches the first groove and the second protrusion matches the second groove, and then placed in an electric field induction device. A direct current electric field with a strength of 5-10kV / cm is applied at 60-80℃ for 30-40min. The electric field force is used to promote interlayer molecular penetration and enhance the bonding strength. Step 7: Vacuum hot melt rotary torque molding The three-layer structure after compounding is sent to a vacuum hot melt molding machine. The vacuum degree is set to -0.095 to -0.098MPa, the temperature is set to 150-170℃, and a rotary torque (5-8N・m) is applied. The interlayer hot melt adhesive layer is fully flowed, filling the interlayer gap. After 20-30min, it is cooled to room temperature, and the overall molding is completed. Step 8: Sealing glue layer coating and packaging pretreatment Epoxy resin sealant (with 10% nanometer montmorillonite) is coated on the inner surface of the packaging area of the outer layer corner section, with a thickness of 3-5μm. It is cured at 100-120℃ for 1-1.5h. At the same time, the high-temperature-resistant corrosion-resistant flame-retardant layer and the hot melt adhesive layer are coated on the inner surface of the transition area. Finally, a solid-state battery aluminum plastic film resistant to high temperature is prepared.

[0007] Preferably, in step 1, the anti-UV agent is 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, and the anti-humidity and heat agent is hydrophobic modified nano-silica with a particle size of 20-30 nm; the screw rotation speed of the double-screw extruder is controlled at 300-350 r / min, and the cooling roller temperature is set at 40-50°C, so as to ensure that the surface flatness error of the outer layer substrate is ≤0.5 μm, the first protrusion height is 2-3 μm, and the first protrusion spacing is 5-8 mm, and the second groove depth is 1-2 μm, and the second groove diameter is 3-5 mm.

[0008] Preferably, in step 2, the nano-ceramic particles are surface modified by using a silane coupling agent (KH-550), the modification temperature is 80-90°C, and the modification time is 1-1.5 h, so as to improve the compatibility with the polyester resin; when the stamping containing groove is performed, a progressive stamping process is adopted, and the stamping speed is 2-3 mm / s, so as to ensure that the groove wall perpendicularity error is ≤1°, and the groove bottom flatness is ≤0.3 μm, thereby avoiding cracks of the middle layer substrate due to stamping stress.

[0009] Preferably, in step 3, the 3D printing adopts a fused deposition modeling technology, the printing speed is 10-15 mm / s, and the nozzle diameter is 0.2-0.3 mm; the main bone diameter of the fishbone-shaped carbon-based framework is 0.5-0.8 mm, the branch length is 2-3 mm, the branch spacing is 4-6 mm, and a segmented temperature rise (60°C for 30 min, 120°C for 90 min) is adopted in the solidification process, so as to avoid internal stress of the framework due to temperature difference.

[0010] Preferably, in step 4, the solid content of the high-temperature-resistant, corrosion-resistant and flame-retardant slurry is controlled at 50-60%, the coating speed is 5-8 m / min, the drying process adopts hot air circulation drying, and the air speed is 1-1.5 m / s; the melt index (190°C / 2.16 kg) of the hot melt adhesive is controlled at 8-10 g / 10 min, and the coating thickness error is ≤0.3 μm, so as to ensure that the high-temperature-resistant, corrosion-resistant and flame-retardant layer and the hot melt adhesive layer are free of bubbles and pinholes.

[0011] Preferably, in step 5, the particle size of the self-repairing microcapsule is 5-10 μm, and the capsule wall thickness is 1-1.5 μm, so as to ensure that the microcapsule is not broken in the polyolefin melting process; the crosslinking agent is added in a step-by-step manner (50% is added first, and the remaining 50% is added after 10 min of melting), so as to avoid local over-crosslinking and cause the substrate to become brittle, and the water and oxygen barrier rate of the inner layer substrate needs to reach ≤0.1 cc / (m²·24h·atm).

[0012] Preferably, in step 6, the electrode spacing of the electric field induction device is 10-15 mm, and the surface of the three-layer structure is treated by plasma before the electric field is applied (power 500-600 W, time 3-5 min) to remove surface oil and impurities; the interlayer resistance is monitored in real time during the electric field induction process, and when the resistance value stabilizes at 10^6-10^7 Ω, it is determined that the molecular penetration has reached the optimal state, and the electric field application is stopped.

[0013] Preferably, in step 7, the rotation torque of the vacuum hot melt forming machine adopts a gradient application method (initial 2N・m, increase by 1N・m every 5min to the set value), which avoids the dislocation between layers caused by excessive instantaneous torque; the cooling process adopts segmented cooling (120℃ for 10min, 80℃ for 10min, and room temperature for 10min), and the cooling rate is controlled to be ≤5℃ / min to prevent the structure from deforming due to thermal stress.

[0014] Preferably, in step 8, the nano-montmorillonite in the sealing adhesive layer is organically modified (using hexadecyl trimethyl ammonium bromide) to improve the dispersibility with epoxy resin; when coating the sealing adhesive, a doctor blade is used with an angle of 45-60° to ensure uniform thickness of the adhesive layer; after curing, the sealing performance of the packaging area is tested (using a helium mass spectrometer leak detector with a leak detection sensitivity ≤1×10^-9 Pa・m³ / s) to ensure no leakage points.

[0015] Compared with the prior art, the beneficial effects of the present application are: 1. Multi-layer structure optimization, comprehensive performance adaptation: The outer modified polyamide solves the problems of outdoor aging and moisture absorption of traditional aluminum plastic film by adding anti-UV agents and anti-hygrothermal agents, and the tensile strength retention rate is ≥90% after UV aging for 500h, and the moisture absorption rate is ≤0.5% in a hygrothermal environment (40℃, 90% RH) for 72h; the intermediate layer of nano-ceramic doped polyester improves the puncture resistance to more than 38N, which is 40% higher than the conventional polyester layer; the self-repairing microcapsules of the inner cross-linked polyolefin can repair ≤5μm microcracks, and the water and oxygen barrier rate is significantly reduced, which is suitable for the long-term cycle demand of solid-state batteries.

[0016] 2. Layer positioning and composite process innovation, enhance structural stability: The layers are precisely positioned by the convex and concave grooves, and the molecular penetration is promoted by the electric field induction, and the interlayer peeling force is ≥12N / 15mm, which is 30% higher than the conventional bonding method; the vacuum hot melt rotation torque forming process eliminates the interlayer gap and avoids delamination at high temperature, and there is no interlayer peeling phenomenon after 50 times of high temperature cycle at 180℃, and the structural stability is greatly improved.

[0017] 3. The design of the containing groove and the packaging structure enhances safety and sealing: the fishbone-shaped carbon-based framework in the containing groove enhances impact resistance, and can withstand a 1m drop without damage; the high-temperature corrosion-resistant flame-retardant layer makes the aluminum plastic film flame-retardant grade reach V-0 level, and the sealing glue layer in the packaging area cooperates with the transition area protection, so that the leakage rate of the battery package after packaging is extremely low, meeting the high airtightness requirement of solid-state batteries and further ensuring the safety of the battery.

[0018] 4. Strong process compatibility, conducive to large-scale production: mature extrusion, coating, 3D printing equipment is used in each step, and the electric field induction and vacuum hot melting process parameters are easy to control, the production efficiency is above 5m / min, and the raw material cost is increased by ≤15% compared with conventional aluminum plastic film, which takes into account the economy while ensuring performance, and is convenient for industrialization promotion. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a schematic diagram of the cross-sectional structure of the aluminum plastic film according to the present application; Figure 2 FIG. 2 is a schematic diagram of the intermediate layer structure of the aluminum plastic film according to the present application; Figure 3 FIG. 3 is a flowchart of the preparation method according to the present application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation of the present application.

[0022] Example 1 I. Aluminum plastic film structure The application discloses a high-temperature-resistant aluminum plastic film for solid-state batteries, which adopts a three-layer composite resin structure, wherein an outer layer 1 is modified polyamide and has anti-UV and anti-hygrothermal properties; a middle layer 2 is nano-ceramic doped polyester and can improve puncture resistance; and an inner layer 3 is cross-linked polyolefin and has a self-repairing function to improve water and oxygen barrier properties; a plurality of first protrusions 10 are arranged at edges of the outer layer 1 and the inner layer 3, a plurality of first grooves 20 matched with the first protrusions 10 are arranged at an edge of the middle layer 2; a plurality of second grooves 40 are arranged at centers of the outer layer 1 and the inner layer 3, and a plurality of second protrusions 30 matched with the second grooves 40 are arranged at a center of the middle layer 2; the middle layer 2 is formed with a containing groove 21 through stamping, a fishbone-shaped carbon skeleton 4 is arranged on a groove bottom of the containing groove 21, and a high-temperature-resistant anti-corrosion flame-retardant layer 5 and a hot melt adhesive layer 6 are arranged on inner surfaces of the containing groove 21 in a melting mode; a corner section of the outer layer 1 comprises a transition zone 7 and an encapsulation zone 8 connected in sequence, the high-temperature-resistant anti-corrosion flame-retardant layer 5 and the hot melt adhesive layer 6 are arranged on inner surfaces of the transition zone 7, a sealing adhesive layer 9 is arranged on an inner surface of the encapsulation zone 8, and two aluminum plastic film structures are encapsulated to form an outer shell of a battery pack through a sealing zone.

[0023] II. Preparation method of the aluminum plastic film A preparation method of the high-temperature-resistant aluminum plastic film for solid-state batteries is as follows. Step 1: Preparation of outer layer modified polyamide Polyamide resin, anti-UV agent (benzotriazole) and anti-hygrothermal agent (nano-silicon dioxide) are mixed at a mass ratio of 90:5:5, are put into a double-screw extruder, are melt-blended at 230-250 DEG C, are extruded through a T-shaped die, are shaped through a cooling roller, and thus an outer layer 1 base material with a thickness of 15-20 microns is prepared, and then first protrusions 10 are processed at edges of the base material and second grooves 40 are processed at centers. The anti-UV agent is selected from 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, and the anti-hygrothermal agent is selected from hydrophobically modified nano-silicon dioxide with a particle size of 20-30 nm; the screw rotation speed of the double-screw extruder is controlled to be 300-350 r / min, and the temperature of the cooling roller is set to be 40-50 DEG C, so that the surface flatness error of the outer layer 1 base material is less than or equal to 0.5 microns, the height of the first protrusions 10 is 2-3 microns, the interval of the first protrusions 10 is 5-8 mm, the depth of the second grooves 40 is 1-2 microns, and the diameter of the second grooves 40 is 3-5 mm.

[0024] The core of the step is to build an outer protective barrier with anti-UV, anti-hygrothermal and structural precision by means of "precise compound of functional additives + strict control of forming process parameters", so as to solve the key problems of easy aging and moisture absorption of the outer layer of the traditional aluminum plastic film.

[0025] From the raw material system design, polyamide resin (main substrate), 2-(2'-hydroxy-5'-methylphenyl) benzotriazole (anti-UV agent), and hydrophobic modified nano-silica (anti-humidity agent) are compounded in a mass ratio of 90:5:5, which has clear scientific principle support. Among them, the benzotriazole group in the molecular structure of the anti-UV agent can efficiently absorb 280-400 nm ultraviolet light, avoiding the initiation of polyamide molecular chain rupture by ultraviolet light. After 500h UV aging test, the tensile strength retention rate is ≥90%, which is more than 40% higher than that of ordinary polyamide layer without adding anti-UV agent; the hydrophobic modified nano-silica (particle size 20-30 nm) forms an interface bond with the polyamide matrix through the surface hydrophobic group, which can construct a "micro-nano level hydrophobic channel blocking structure" inside the substrate, greatly reducing the water molecule penetration rate. The moisture absorption rate is ≤0.5% under 40℃, 90% RH humid heat environment for 72h, which is much better than the industry standard (≤1.5%).

[0026] In the forming process control, the parameter combination of the screw rotation speed (300-350r / min) and temperature (230-250℃) of the double screw extruder ensures that the polyamide resin is fully melted (the melt index is stable at 5-7g / 10min), and avoids the high temperature decomposition of the anti-UV agent (the decomposition temperature of the anti-UV agent is ≥260℃); the cooling roller temperature (40-50℃) precisely controls the crystallinity of the substrate, so that the surface flatness error of the outer layer substrate is ≤0.5μm, providing high-quality interface conditions for subsequent interlayer compounding. In addition, the structure design of the first protrusion (height 2-3μm, spacing 5-8mm) and the second groove (depth 1-2μm, diameter 3-5mm) is the first time to introduce the concept of "mechanical interlocking positioning" into the interlayer bonding of aluminum-plastic film. Through the physical fitting of the protrusion and the groove, the interlayer positioning accuracy is initially improved, laying a structural foundation for subsequent electric field-induced molecular penetration, avoiding the risk of interlayer misalignment caused by traditional pure reliance on adhesive.

[0027] Step 2: Preparation of intermediate layer nano-ceramic doped polyester The polyester resin and nano-ceramic particles (aluminum nitride / aluminum oxide, particle size 50-100 nm) are mixed in a mass ratio of 85:15, stirred uniformly in a high-speed mixer, and then sent to an extruder for melting and extrusion at 260-280℃. The intermediate layer 2 substrate with a thickness of 25-30μm is prepared by flow casting. The first groove 20 is processed on the edge of the substrate, the second protrusion 30 is processed in the center, and the substrate is subjected to stamping processing to form a containing groove 21; The nano ceramic particles are surface modified by a silane coupling agent (KH-550), the modification temperature is 80-90℃, and the time is 1-1.5h, which improves the compatibility with the polyester resin; when stamping the containing groove 21, a progressive stamping process is adopted, the stamping speed is 2-3mm / s, the verticality error of the groove wall is ≤1°, the flatness of the groove bottom is ≤0.3μm, and the middle layer 2 substrate is avoided from being cracked due to stamping stress.

[0028] The above technical content is analyzed: this step focuses on "reinforcement surface modification + precise stamping forming", creates a high puncture-resistant and low-stress intermediate support layer, and breaks through the technical bottleneck of insufficient puncture resistance of traditional intermediate layers and easy cracking during stamping.

[0029] On the raw material level, polyester resin and nano ceramic particles (aluminum nitride / aluminum oxide, particle size 50-100nm) are mixed in a mass ratio of 85:15, and the key innovation point is that the nano ceramic particles are surface modified by a silane coupling agent (KH-550) (80-90℃, 1-1.5h). The amino group in the KH-550 molecule can react with the hydroxyl group on the surface of the ceramic particles, and the alkoxyl group at the other end can chemically bond with the polyester resin, greatly improving the interfacial bonding force between the ceramic particles and the polyester matrix, and solving the problem of uneven performance caused by the easy agglomeration of traditional ceramic particles. The modified nano ceramic particles have a dispersion uniformity of ≥95% in the polyester matrix, which can significantly improve the puncture resistance through the "crack deflection" and "energy absorption" mechanisms, and the intermediate layer has a puncture resistance of ≥38N, which is 40% higher than that of a conventional polyester layer without ceramic particles, meeting the needs of external impact resistance and internal electrode expansion during solid-state battery assembly.

[0030] On the forming process, the melt extrusion temperature (260-280℃) matches the melting characteristics (melting point 255-260℃) of the polyester resin (such as PET), ensuring that the resin flows sufficiently; the cast molding process controls the thickness of the substrate (25-30μm) to be ≤±1μm, ensuring the uniformity of the substrate. In particular, the application of a progressive stamping process (stamping speed 2-3mm / s) is first adopted in the processing of an aluminum-plastic film intermediate layer, which slowly applies stamping stress to make the substrate deform uniformly and release, avoiding the generation of cracks caused by instantaneous stress concentration, and finally realizing a high-precision containing groove structure with a verticality error of the groove wall ≤1° and a flatness of the groove bottom ≤0.3μm, providing a flat and stable carrier for subsequent fishbone-shaped carbon-based skeleton laying, and the design of the containing groove can provide a buffer space when the battery is impacted, further improving safety performance.

[0031] Step 3: Fishbone-shaped carbon-based skeleton laying The carbon nanotubes and phenolic resin are mixed in a mass ratio of 30:70 to form a paste slurry, and a fishbone-shaped carbon-based skeleton 4 is printed on the bottom of the containing groove 21 by 3D printing technology, and then cured at 120-150°C for 2-3h; The 3D printing adopts a fused deposition modeling technology, the printing speed is 10-15mm / s, and the nozzle diameter is 0.2-0.3mm; the main bone diameter of the fishbone-shaped carbon-based skeleton 4 is 0.5-0.8mm, the branch length is 2-3mm, and the interval is 4-6mm; and a segmented temperature rise (60°C for 30min, 120°C for 90min) is adopted in the curing process to avoid internal stress of the skeleton due to temperature difference.

[0032] The above technical content is analyzed: this step innovatively adopts "3D printing customization molding + segmented stress control", to build a skeleton structure with high support strength and impact resistance, filling the technical gap of the traditional aluminum plastic film middle layer lacking active impact support.

[0033] In the raw material formula, the carbon nanotubes and phenolic resin are mixed in a mass ratio of 30:70 to form a paste slurry, the carbon nanotubes (diameter 10-20nm, length 5-10μm) have excellent mechanical properties (tensile strength≥30GPa) and can be used as a skeleton reinforcing body; the phenolic resin (tensile strength≥80MPa after curing) is used as a bonding matrix to ensure the bonding force of the skeleton and the middle layer substrate. The 3D printing adopts a fused deposition modeling technology (printing speed 10-15mm / s, nozzle diameter 0.2-0.3mm), which can accurately control the size parameters of the fishbone-shaped structure (main bone diameter 0.5-0.8mm, branch length 2-3mm, interval 4-6mm). This bionic fishbone structure can disperse external impact load to multiple branches, achieving "load shunting", and the impact resistance of the traditional flat skeleton is improved by more than 50%, and there is no damage after 1m drop test, effectively protecting the internal structure of the battery.

[0034] The curing process adopts a segmented temperature rise (60°C for 30min, 120°C for 90min), which is a precise regulation based on the curing reaction characteristics of phenolic resin. The low-temperature stage (60°C) can slowly crosslink the resin to avoid internal stress generated by rapid curing; the high-temperature stage (120°C) promotes complete curing reaction to ensure stable mechanical properties of the skeleton. The final cured fishbone-shaped carbon-based skeleton has a bending strength of≥150MPa and a heat distortion temperature of≥250°C, which can maintain structural stability in the high-temperature working environment (150-200°C) of the solid-state battery, while its porous structure does not affect the gas discharge between the layers, creating conditions for subsequent vacuum hot melt molding.

[0035] Step 4: Preparation of High-temperature-resistant Anti-corrosion and Flame-retardant Layer and Hot Melt Adhesion Layer The aluminum hydroxide (flame retardant), epoxy resin (adhesive) are mixed in a mass ratio of 40:60 to form a high-temperature-resistant corrosion-resistant flame-retardant slurry, and the ethylene-vinyl acetate copolymer (EVA) is heated to 180-200℃ to form a hot melt adhesive; through a double die coating machine, the high-temperature-resistant corrosion-resistant flame-retardant slurry is first coated on the inner surface of the containing groove 21, dried at 80-100℃ for 1-1.5h to form a high-temperature-resistant corrosion-resistant flame-retardant layer 5, and then the hot melt adhesive is coated on the surface of the layer, and naturally cooled to room temperature to form a hot melt adhesive layer 6. The solid content of the high-temperature-resistant corrosion-resistant flame-retardant slurry is controlled to be 50-60%, the coating speed is 5-8m / min, and the drying process adopts hot air circulation drying with a wind speed of 1-1.5m / s; the melting index (190℃ / 2.16kg) of the hot melt adhesive is controlled to be 8-10g / 10min, and the coating thickness error is ≤0.3μm, ensuring that the high-temperature-resistant corrosion-resistant flame-retardant layer 5 and the hot melt adhesive layer 6 are free of bubbles and pinholes.

[0036] The above technical content analysis: this step realizes the functions of high-temperature resistance, corrosion resistance, flame retardance and interlayer adhesion of the intermediate layer through "double-layer functional coating synergistic design + precise coating quality control", solving the problem of single functional coating and poor performance synergy of traditional aluminum-plastic film.

[0037] The high-temperature-resistant corrosion-resistant flame-retardant layer adopts a compound system of aluminum hydroxide (40%) and epoxy resin (60%), and the aluminum hydroxide as an inorganic flame retardant decomposes and absorbs heat and releases water vapor at high temperatures (≥200℃), dilutes flammable gas and forms an Al2O3 protective layer, achieving flame retardation effect (the final aluminum-plastic film flame retardation level reaches V-0 level); the epoxy resin has excellent high-temperature resistance (long-term use temperature ≤180℃) and corrosion resistance, which can isolate external corrosive media (such as electrolyte and moisture) and protect the intermediate layer substrate. The slurry solid content is controlled to be 50-60%, combined with a coating speed of 5-8m / min and hot air circulation drying (wind speed 1-1.5m / s, 80-100℃, 1-1.5h), which can avoid bubbles and pinholes in the coating, ensure the coating density (porosity ≤0.5%), and improve the corrosion and flame retardation reliability.

[0038] The hot melt adhesive layer is selected from ethylene-vinyl acetate copolymer (EVA), the melting temperature (180-200℃) of which matches the subsequent vacuum hot melt forming temperature, the melt index is controlled to be 8-10g / 10min (190℃ / 2.16kg), which can ensure sufficient flow in the forming process and fill the gap between the layers; the coating thickness error is ≤0.3μm, which ensures the uniformity of interlayer adhesion and avoids the delamination caused by insufficient local adhesion strength. In addition, the design of the double-layer coating in sequence makes the flame-retardant layer close to the middle layer substrate to play a protective role, and the adhesive layer is located on the outside to realize the interlayer combination, forming a "protection-adhesion" collaborative system. Compared with the traditional single adhesive layer, there is no interlayer peeling phenomenon after 50 times of high temperature cycle at 180℃, and the structural stability is significantly improved.

[0039] Step 5: Preparation of inner layer cross-linked polyolefin The polyolefin resin and the cross-linking agent (dicumyl peroxide) and the self-repairing microcapsule (urea-formaldehyde resin wrapped isocyanate) are mixed in a mass ratio of 88:2:10, melted and blended at 180-200℃, and extruded to form an inner layer 3 substrate with a thickness of 20-25μm. The first protrusion 10 is processed on the edge of the substrate, and the second groove 40 is processed in the center. The particle size of the self-repairing microcapsule is 5-10μm, and the capsule wall thickness is 1-1.5μm, which ensures that it does not break during the melting process of the polyolefin; the cross-linking agent is added in a step-by-step manner (50% first, then the remaining 50% after 10min of melting), which avoids the local over-crosslinking of the substrate and the brittleness of the substrate. The water and oxygen barrier rate of the inner layer 3 substrate needs to reach ≤0.1cc / (m²・24h・atm).

[0040] Analysis of the above technical content: This step focuses on "cross-linking modification to enhance high temperature resistance + self-repairing microcapsule to give self-healing function", creating an inner layer packaging layer that adapts to the high temperature environment and long-term use requirements of solid-state batteries, breaking through the limitations of traditional inner layer polyolefin poor high temperature resistance and no self-repairing ability.

[0041] The combination of polyolefin resin (main body), dicumyl peroxide (crosslinking agent, 2%) and self-repairing microcapsules (urea-formaldehyde resin wrapped isocyanate, 10%) in the raw material system is the core innovation. The crosslinking agent is added in steps (first add 50%, melt for 10 min, then add the remaining 50%), which can avoid local over-crosslinking and cause the substrate to become brittle. By controlling the crosslinking degree (gel content ≥ 60%), the inner layer substrate can withstand a temperature of 180°C (the conventional polyolefin inner layer can withstand a temperature of ≤120°C), meeting the instantaneous high temperature demand of solid-state battery fast charging. The self-repairing microcapsule particle size is controlled to be 5-10μm, and the capsule wall thickness is 1-1.5μm, which ensures that the capsule wall does not break during the polyolefin melting process (180-200°C) (the capsule wall can withstand a temperature of ≥220°C), and when the substrate has a microcrack (≤5μm), the capsule wall can be broken by the mechanical stress at the crack, releasing isocyanate, which reacts with moisture in the air or hydroxyl groups in the substrate to form a polyurethane elastomer, achieving crack self-repairing (repair efficiency ≥ 80%, and the water and oxygen barrier performance after repair recovers to more than 90% of the initial value).

[0042] The inner layer substrate thickness is controlled to be 20-25μm in the molding process, and the water and oxygen barrier rate is ≤0.1cc / (m²・24h・atm), which is more than 80% higher than that of the conventional polyolefin inner layer (water and oxygen barrier rate ≥0.5cc / (m²・24h・atm)), which can effectively block water and oxygen from penetrating into the battery, prevent electrode material oxidation and electrolyte decomposition, and prolong the battery cycle life (after 1000 cycles, the capacity retention rate of the battery using the inner layer is ≥85%, which is 15% higher than that of the conventional inner layer).

[0043] Step 6: Electric field-induced interlayer compounding The outer layer 1, the middle layer 2 and the inner layer 3 are stacked in order, ensuring that the first protrusion 10 and the first groove 20, and the second protrusion 30 and the second groove 40 are precisely matched, and then placed in an electric field induction device. A direct current electric field with a strength of 5-10kV / cm is applied at 60-80°C for 30-40min to promote molecular penetration between layers and enhance bonding strength by using electric field force; The electrode spacing of the electric field induction device is 10-15mm. The surface of the three-layer structure is treated by plasma before the electric field is applied (power 500-600W, time 3-5min) to remove surface dirt and impurities. The interlayer resistance is monitored in real time during the electric field induction process. When the resistance value stabilizes at 10^6-10^7Ω, it is determined that the molecular penetration has reached the optimal state, and the electric field application is stopped.

[0044] Analysis of the above technical content: This step innovatively introduces the "plasma pretreatment + electric field-induced molecular penetration" process to strengthen the interlayer bonding strength of the three-layer structure, solving the problem of traditional interlayer compounding relying on adhesives and the decrease of bonding strength at high temperatures.

[0045] Plasma treatment before electric field application (power 500-600W, 3-5min) removes surface oil and impurities (cleanliness improved to 99.9%) by high-energy plasma bombardment on the surface of the three-layer structure, and at the same time breaks the surface molecular chain to form active groups (such as hydroxyl and carboxyl groups), increasing the interfacial reaction sites and laying the foundation for subsequent molecular penetration. During the electric field induction process, the synergistic effect of a direct current electric field of 5-10kV / cm and a temperature of 60-80℃ can accelerate the thermal motion and diffusion of interlayer molecules (such as amide groups of outer layer polyamide, carbon-hydrogen bonds of inner layer polyolefin, and ester groups of intermediate layer EVA), promote molecular-level interpenetration and interfacial bonding, and increase the interlayer peeling force by more than 30% compared to traditional pure physical pressing, reaching ≥12N / 15mm.

[0046] In addition, by monitoring the change of interlayer resistance in real time (stopping the electric field when the resistance stabilizes at 10 6 -10 7 Ω), the optimal state of molecular penetration can be accurately judged, avoiding insufficient electric field application leading to insufficient bonding force or excessive application causing substrate damage, realizing intelligent quality control of interlayer compounding, and ensuring the consistency of interlayer bonding performance of each batch of products (deviation ≤5%). The electrode spacing is controlled to be 10-15mm, which can ensure uniform distribution of electric field and avoid interlayer bonding differences caused by uneven local electric field strength.

[0047] Step 7: Vacuum hot melt rotary torque forming The three-layer structure after compounding is sent to a vacuum hot melt forming machine, with a vacuum degree of -0.095 to -0.098MPa, a temperature of 150-170℃, and a rotary torque (5-8N・m) applied to make the interlayer hot melt adhesive layer 6 flow fully, fill the interlayer gap, and cool to room temperature after 20-30min, completing the overall forming; The rotary torque of the vacuum hot melt forming machine is applied in a gradient manner (initial 2N・m, increasing by 1N・m every 5min to the set value), avoiding interlayer misalignment caused by excessive instantaneous torque; the cooling process adopts segmented cooling (120℃ for 10min, 80℃ for 10min, and room temperature for 10min), controlling the cooling rate ≤5℃ / min to prevent structure deformation due to thermal stress.

[0048] Analysis of the above technical content: This step adopts the integrated process of "vacuum environment degassing + gradient torque pressing + segmented cooling shape control", realizing the tight compounding and size stability of the three-layer structure, and solving the technical problems of traditional hot melt forming, such as easy interlayer gap and easy deformation at high temperature.

[0049] The vacuum degree is set to -0.095 to -0.098 MPa, so that the interlayer air and volatile substances can be discharged during the molding process, air bubbles are avoided (the air bubble rate of the final product is ≤0.1%), and the interlayer is tightly attached; the temperature of 150-170°C makes the EVA hot melt adhesive layer fully melt, and the gradient rotation torque (initial 2N·m, increasing by 1N·m every 5min to 5-8N·m) can slowly apply shear force, promote the flow and filling of the molten adhesive to the interlayer micro gap, while avoiding the dislocation of the three-layer structure caused by excessive instantaneous torque (the interlayer dislocation amount is ≤0.1mm). The holding time of 20-30min ensures that the adhesive and the substrate interface fully react, improving the bonding stability.

[0050] The cooling process adopts segmented cooling (120°C for 10min, 80°C for 10min, room temperature for 10min), and the cooling rate is controlled to be ≤5°C / min, which can avoid the structural thermal stress concentration caused by sudden temperature drop (thermal stress value ≤10MPa), and prevent the substrate from warping and cracking (the flatness error of the final product is ≤0.5mm / m). This process first introduces a rotating torque into the aluminum-plastic film hot melt forming, and through the synergistic effect of mechanical force and heat, the interlayer bonding strength and sealing performance are greatly improved. After 50 cycles at 180°C, there is no peeling and no structural deformation between the layers, which meets the reliability requirements of solid-state batteries for long-term high-temperature use.

[0051] Step 8: Sealing adhesive layer coating and packaging pretreatment The epoxy resin sealing adhesive (adding 10% nanometer montmorillonite) is coated on the inner surface of the packaging area 8 of the outer layer 1 corner section, with a thickness of 3-5μm, and cured at 100-120°C for 1-1.5h. At the same time, the high-temperature resistant, corrosion resistant and flame retardant layer 5 and the hot melt adhesive layer 6 are coated on the inner surface of the transition area 7, and finally the solid-state battery high-temperature resistant aluminum-plastic film is obtained. The nanometer montmorillonite of the sealing adhesive layer 9 is organically modified (using hexadecyl trimethyl ammonium bromide) to improve the dispersibility with the epoxy resin; when coating the sealing adhesive, a doctor blade is used, and the angle of the doctor blade is controlled to be 45-60° to ensure the uniform thickness of the adhesive layer; after curing, the sealing performance test (using a helium mass spectrometer leak detector with a leak detection sensitivity of ≤1×10^-9Pa·m³ / s) is performed on the packaging area 8 to ensure that there is no leakage point.

[0052] Analysis of the above technical content: This step builds a high air-tightness protection for the packaging area of the aluminum-plastic film by "modified sealing adhesive system design + precise coating and strict inspection", solving the key problem of unstable sealing performance and easy leakage of traditional packaging area.

[0053] The sealing adhesive layer adopts an epoxy resin added with 10% organically modified nano-montmorillonite system. After modification of the nano-montmorillonite by cetyltrimethylammonium bromide, the interlayer spacing is increased (from 1 nm to 3-5 nm), which can be uniformly dispersed in the epoxy resin matrix to form a "nanoscale barrier network", greatly improving the water and oxygen barrier performance of the sealing adhesive (the water and oxygen transmission rate is reduced by 60% compared with pure epoxy resin); at the same time, the lamellar structure of montmorillonite can enhance the mechanical properties of the sealing adhesive (the tensile strength is improved by 25%), avoiding cracking of the adhesive layer during packaging. With a coating thickness of 3-5 μm and a doctor blade coating (angle 45-60°), the uniformity of the adhesive layer thickness (deviation ≤0.3 μm) can be ensured to ensure that the adhesive layer is fully contacted and forms a continuous sealing surface during packaging.

[0054] The curing process (100-120℃, 1-1.5h) makes the epoxy resin fully crosslinked to form a stable three-dimensional network structure, ensuring the sealing performance of the sealing adhesive layer at high temperatures (≤180℃); the high-temperature resistant, corrosion-resistant and flame-retardant layer and the hot melt adhesive layer in the transition zone can avoid performance discontinuity between the packaging area and the non-packaging area, forming a "high air tightness in the packaging area + high protection in the transition zone" synergistic structure. In addition, after curing, a helium mass spectrometer (sensitivity ≤1×10⁻ 9 Pa・m³ / s) is used for sealing performance test, which is the first time to apply ultra-high sensitivity leak detection technology to the packaging area of aluminum-plastic film, which can accurately identify small leakage points (leakage rate ≤1×10⁻ 0 Pa・m³ / s), ensuring that each piece of aluminum-plastic film is leak-free after packaging, and the leakage rate of the final battery pack is much lower than the industry standard (≤1×10⁻ 6 Pa・m³ / s), providing protection for the long-term safe operation of solid-state batteries.

[0055] Working principle: The scheme focuses on the packaging requirements of solid-state batteries under high temperature and complex environment, and takes "multi-layer structure synergistic protection + innovative process to enhance performance" as the core logic. Through the deep integration of material design, structure optimization and process innovation, the comprehensive performance of aluminum-plastic film is improved.

[0056] From the principle of material action, the outer layer uses modified polyamide, and the added 2-(2'-hydroxy-5'-methylphenyl) benzotriazole can efficiently absorb ultraviolet rays of 280-400 nm to prevent the ultraviolet rays from causing the molecular chain of polyamide to break. At the same time, the hydrophobically modified nano-silicon dioxide (20-30 nm) forms a "micro-nano hydrophobic channel blocking structure" to reduce water molecule penetration, solving the traditional outer layer aging and moisture absorption problems. In the middle layer, the aluminum nitride / aluminum oxide particles (50-100 nm) modified by silane coupling agent (KH-550) form a strong interface with the polyester resin, and through the "crack deflection" mechanism, the puncture strength is improved. The fishbone-shaped carbon skeleton (carbon nanotube and phenolic resin composite) in the containing groove utilizes the bionic structure to realize impact load diversion and enhance the impact resistance. In the inner layer, the moderate cross-linked structure (gel content ≥ 60%) is formed by stepwise addition of dicumyl peroxide cross-linking agent in the cross-linked polyolefin, which improves the high temperature resistance. When micro-cracks occur, the self-repairing microcapsules (urea-formaldehyde resin wrapped isocyanate) can release isocyanate through capsule wall rupture, and react with water or hydroxyl to form polyurethane elastomer to realize self-repairing. At the same time, the low water and oxygen barrier rate (≤0.1 cc / (m²・24h・atm)) blocks the penetration of water and oxygen.

[0057] From the structural synergy principle, the interlayer is positioned by "edge first protrusion - first groove + center second protrusion - second groove" mechanical interlocking, which preliminarily ensures the alignment accuracy between layers and lays a foundation for subsequent compounding. The high-temperature-resistant, corrosion-resistant and flame-retardant layer (aluminum hydroxide and epoxy resin composite, high-temperature decomposition and heat absorption to form a protective layer) and the hot melt adhesive layer (EVA, filling the gap after melting) are sequentially arranged in the containing groove of the middle layer, realizing the "protection - adhesion" dual function. The flame-retardant and adhesive layers in the outer layer corner transition area and the modified epoxy resin sealant (with organic modified nano-montmorillonite) in the packaging area form a gradient protection, ensuring high air tightness after packaging.

[0058] From the process action principle, the electric field induced interlayer compounding is accelerated by 5-10 kV / cm direct current electric field and 60-80°C temperature synergy, which accelerates the interlayer molecular penetration, combined with plasma pretreatment (500-600W, 3-5min) to remove surface impurities and activate the interface, greatly improving the interlayer bonding strength. Vacuum hot melt rotary torque forming (vacuum degree -0.095 to -0.098 MPa, 150-170°C, 5-8N・m gradient torque) uses vacuum degassing, hot melt flow and gradient torque to eliminate interlayer gaps, and cooperates with segmented cooling (≤5°C / min) to avoid thermal stress deformation. Precise parameter control (such as extrusion temperature, coating speed, curing time, etc.) ensures that the material performance and structural accuracy can be stably played, and finally realizes the reliable packaging of aluminum plastic film in high temperature and complex environment.

[0059] The core innovation of the present scheme is: 1. Propose a "three-layer composite resin functional design + gradient protection structure" scheme to solve the problem of single performance of traditional aluminum-plastic film and its inability to adapt to the multiple needs of solid-state batteries. The outer layer of traditional aluminum-plastic film is prone to aging and moisture absorption, the middle layer is insufficient in puncture resistance, and the inner layer has no self-repairing and poor high temperature resistance. The present scheme uses functional design of outer layer modified polyamide (UV resistance + moisture resistance), middle layer nanoceramic doped polyester + fishbone-shaped carbon skeleton (high puncture resistance + impact resistance), and inner layer cross-linked polyolefin (self-repairing + high water and oxygen barrier), combined with double-layer functional coating in the middle layer containing groove and gradient protection structure in the outer layer corners, to achieve full performance coverage of "UV resistance - moisture resistance - puncture resistance - impact resistance - self-repairing - high temperature resistance - high airtightness", filling the gap in the industry that single structure cannot meet the complex needs of solid-state batteries.

[0060] 2. Through the integrated process of "mechanical interlocking positioning + electric field induced molecular penetration + vacuum hot melt rotary torque forming", solve the problem of poor interlayer adhesion and easy delamination of traditional layers. The traditional process relies on conventional adhesives, and the interlayer peeling force is easily affected by high temperature and decreases. The present scheme first realizes preliminary positioning through convex - concave mechanical interlocking, then activates the interface through plasma pretreatment, and then promotes molecular level penetration (interlayer resistance is stabilized at 10 6 -10 7 Ω Stop to ensure optimal bonding), and finally through vacuum hot melt rotary torque forming (gradient torque to avoid misplacement, vacuum degassing to eliminate bubbles), the interlayer peeling force is ≥12N / 15mm, which is 30% higher than conventional adhesion, and there is no delamination after 50 times of high temperature cycle at 180°C, significantly improving the structural stability.

[0061] 3. For the first time, "fishbone-shaped carbon skeleton 3D printing customization" is introduced into the middle layer of aluminum-plastic film to achieve precise strengthening of impact resistance. Existing technologies do not design active impact resistance structures for the middle layer of aluminum-plastic film. The present scheme uses carbon nanotubes and phenolic resin to make a slurry at a ratio of 30:70, uses fused deposition modeling technology (printing speed 10-15mm / s, nozzle 0.2-0.3mm) to customize fishbone-shaped skeleton (main bone 0.5-0.8mm, branch 2-3mm), and uses segmented curing (60°C for 30min + 120°C for 90min) to avoid internal stress, so that the aluminum-plastic film can withstand 1m drop without damage, and the impact resistance is improved by more than 50% compared with traditional structures, providing active protection for the battery.

[0062] 4. First time to apply "electric field induced molecular penetration combined with vacuum hot melt rotary torque forming" to aluminum plastic film interlayer compounding, realizing seamless and tight interlayer combination. Traditional hot melt forming only relies on heat to make the adhesive flow, which is easy to leave gaps. This scheme innovatively combines electric field induction (promotes molecular penetration) and vacuum hot melt rotary torque (gradient torque pressure + vacuum degassing), through the synergistic effect of electric field force, mechanical force and heat, to make the hot melt adhesive layer fully fill the interlayer micro gap. The final product has a bubble rate of ≤0.1%, an interlayer misalignment of ≤0.1mm, and solves the problem of interlayer gaps and poor sealing in traditional processes.

[0063] 5. Propose an inner layer preparation scheme of "step-by-step dispersion of self-repairing microcapsules + gradient addition of crosslinking agent", which solves the problem of difficult to balance self-repairing and high temperature resistance. Existing inner layers either have no self-repairing function, or the self-repairing microcapsules are easily broken during processing, and excessive crosslinking leads to brittleness. This scheme mixes self-repairing microcapsules (particle size 5-10μm, capsule wall 1-1.5μm) with polyolefin resin to ensure that they are not broken during processing, and crosslinking agent is added in steps (first 50%, then add the remaining 50% after 10min of melting), to avoid excessive local crosslinking. The inner layer has both ≤5μm microcrack self-repairing capability (repair efficiency ≥80%) and can withstand 180℃ high temperature, with a water and oxygen barrier rate of ≤0.1cc / (m²・24h・atm), suitable for long-term cycling requirements of solid-state batteries.

[0064] The technical effects generated by implementing this scheme are: 1. Overall improve the environmental adaptability and durability of aluminum plastic film, meet the needs of complex application scenarios of solid-state batteries. The outer layer of modified polyamide retains ≥90% of its tensile strength after 500h of UV aging, which is an increase of more than 40% compared with conventional polyamide layers, and the moisture absorption rate is ≤0.5% in a 40℃, 90% RH humid heat environment, which is much better than the industry's conventional standard (≤1.5%), effectively avoiding aging and moisture absorption problems when used outdoors; The intermediate layer of nanoceramic doped polyester has an anti-puncture strength of ≥38N, which is an increase of 40% compared with conventional polyester layers, and cooperates with the fishbone-shaped carbon skeleton to make the aluminum plastic film resistant to 1m drop without damage, greatly enhancing the impact resistance and coping with external impact and internal pole piece expansion during battery assembly and use; The inner layer of self-repairing microcapsules can repair ≤5μm microcracks, and the water and oxygen barrier performance after repair recovers to ≥90% of the initial value, and the water and oxygen barrier rate is ≤0.1cc / (m²・24h・atm), which is an increase of 80% compared with conventional inner layers (≥0.5cc / (m²・24h・atm)), which can effectively prevent water and oxygen from penetrating, and the battery cycle 1000 times after using this aluminum plastic film has a capacity retention rate of ≥85%, which is an increase of 15% compared with conventional aluminum plastic film encapsulated batteries, significantly prolonging the battery life.

[0065] 2. Significantly enhance the stability and high-temperature resistance of the aluminum-plastic film structure, adapt to the high-temperature working condition of solid-state batteries. Through the electric field induction and vacuum hot melt rotary torque forming process, the interlayer peeling force is ≥12 N / 15 mm, which is 30% higher than the conventional bonding method, and there is no interlayer peeling phenomenon after 50 cycles at 180℃ high temperature, solving the problem of delamination of traditional aluminum-plastic film at high temperature; the inner cross-linked structure makes the high-temperature resistance improve to 180℃, far exceeding the conventional polyolefin inner layer (≤120℃), and can withstand the instantaneous high temperature of 150-200℃ during fast charging of solid-state batteries; the middle layer fishbone-shaped carbon skeleton has a thermal deformation temperature ≥250℃, and the high-temperature corrosion-resistant and flame-retardant layer makes the aluminum-plastic film flame-retardant grade reach V-0 level, which can maintain structural stability under high temperature or fire risk, avoid safety accidents caused by damage of the aluminum-plastic film, and greatly improve the safety of solid-state batteries.

[0066] 3. Realize high-airtightness packaging of aluminum-plastic film, and guarantee long-term reliability of the battery. The outer packaging area uses epoxy resin sealant with 10% organic modified nano-montmorillonite, which is coated by a doctor blade (45-60° angle) and cured at 100-120℃ for 1-1.5h, and the water and oxygen transmission rate of the glue layer is reduced by 60% compared with pure epoxy resin. Combined with helium mass spectrometer (sensitivity ≤1×10⁻ 9 Pa・m³ / s) detection, it is ensured that the leakage rate of the packaging area is ≤1×10⁻ 0 Pa・m³ / s, which is much lower than the industry standard (≤1×10⁻ 6 Pa・m³ / s); the high-temperature corrosion-resistant and flame-retardant layer and the hot melt adhesive layer of the transition area avoid performance discontinuity between the packaging area and the non-packaging area, form a complete protection system, effectively isolate external water and oxygen, corrosion medium into the battery, prevent electrolyte decomposition and electrode material oxidation, ensure the performance stability of solid-state batteries in long-term use, and reduce the risk of battery failure caused by packaging failure.

[0067] 4. Consider process compatibility and economy, conducive to large-scale production promotion. The steps of this scheme use mature extrusion, coating, 3D printing equipment such as double-screw extruders, double-die coaters, fused deposition modeling 3D printers, etc., and the equipment investment cost is controllable; the electric field induction and vacuum hot melt process parameters (such as electric field strength, vacuum degree, torque, etc.) are easy to control, and the production efficiency is above 5m / min, which can meet the industrial production demand; the raw material cost increases by ≤15% compared with the conventional aluminum-plastic film, which greatly improves the performance without significantly increasing the production cost, solves the problem that some high-performance materials are difficult to promote due to high cost, and provides a feasible solution for the industrial application of solid-state battery packaging materials, promoting the landing and popularization of solid-state battery technology in the new energy industry.

[0068] Note: In combination with the core technical requirements of the solid-state battery high-temperature-resistant aluminum-plastic film in the application file, such as high-temperature resistance, mechanical strength, interlayer adhesion stability, and electrolyte compatibility, the specific types of each raw material are given as follows: I. Polyamide resin (adapted to the outer protective layer, considering heat resistance and punching toughness) Specific types: Nylon 6 (PA6), Nylon 66 (PA66), m-xylylenediamine adipamide (MXD6) Matching basis: This scheme clearly requires the outer protective layer of the aluminum-plastic film to withstand processing and punching and resist external impact. The above types are all mainstream polyamide raw materials for the outer layer of the aluminum-plastic film. Among them, PA6 has good mechanical balance and is the core component of biaxially oriented polyamide (BOPA) film, which can meet the basic heat resistance and toughness requirements; PA66 is more rigid and can improve the puncture resistance of the film material; MXD6 has excellent barrier properties and high-temperature resistance, which can enhance the resistance of the outer protective layer to environmental factors. All of the above meet the goal of "high-temperature resistance and stable mechanical properties".

[0069] II. Polyester resin (adapted to the bonding layer / composite layer, requiring strong adhesion and thermal stability) Specific types: Biaxially oriented polyester (BOPET) resin, thermoplastic polyester elastomer (TPEE), acid anhydride modified polyester composite glue Matching basis: This scheme requires the bonding layer to be delamination-free at high temperatures and resistant to electrolyte corrosion. BOPET resin is a common polyester base material for the outer layer of the aluminum-plastic film, with a heat resistance temperature of over 150°C and excellent dimensional stability; TPEE combines rubber elasticity and plastic heat resistance, which can enhance the flexibility of interlayer bonding; acid anhydride modified polyester composite glue is designed specifically for the composite of aluminum foil and high molecular film, with high adhesion strength and outstanding chemical resistance, fully meeting the requirement of "firm interlayer composite".

[0070] III. Carbon nanotubes (adapted to the functional enhancement layer, requiring improved thermal conductivity and mechanical properties) Specific types: Multi-walled carbon nanotubes (MWCNTs), carboxylated multi-walled carbon nanotubes (COOH-MWCNTs) Matching basis: This scheme requires the use of nanofillers to optimize the thermal conductivity and mechanical strength of the film material. Multi-walled carbon nanotubes have a diameter of 10-20 nm and a length of 5-10 μm, with good dispersibility, which can effectively build a heat conduction network and improve the heat dissipation efficiency of the aluminum-plastic film. Carboxylated carbon nanotubes can enhance the compatibility with the resin matrix and avoid agglomeration, further strengthening the tensile strength and impact resistance of the film material, fully matching the goal of "functional enhancement layer".

[0071] IV. Phenolic resin (adapted to the high-temperature-resistant crosslinked layer, requiring enhanced thermal stability and flame retardance) Specific types: boron-modified phenolic resin, phenol-resorcinol-formaldehyde co-condensation resin Matching basis: This scheme requires the aluminum-plastic film to maintain its shape stability in a high-temperature environment. The boron-modified phenolic resin improves the cross-linking density by introducing boron elements, has a heat-resistant temperature exceeding 200°C, and excellent flame retardancy; the phenol-resorcinol-formaldehyde co-condensation resin has high reactivity, and the network structure formed after curing has strong thermal stability, can resist long-term immersion in electrolyte, and meets the requirements of "high-temperature resistance and chemical corrosion resistance".

[0072] Five, epoxy resin (adapt to the bonding layer / high-temperature resistant layer, need to consider adhesion and heat resistance) Specific types: bisphenol A type epoxy resin (E-51), hydroxyl-terminated polyether sulfone epoxy resin, phenolic epoxy resin (F-44) Matching basis: In this scheme, the epoxy resin needs to meet the requirements of firm bonding and high-temperature resistance. Bisphenol A type epoxy resin (E-51) has strong bonding force and is the basic raw material for interlayer adhesion of aluminum-plastic film; hydroxyl-terminated polyether sulfone epoxy resin has heat resistance and toughness, which can improve the anti-cracking performance of the film material under high temperature; phenolic epoxy resin (F-44) can further improve the thermal stability of the cross-linked system when used with phenolic resin, and adapt to the performance requirements of "high-temperature resistant layer".

[0073] Six, polyolefin resin (adapt to the heat-sealing layer, need to consider sealing and electrolyte resistance) Specific types: homopolymer polypropylene (PP), unsaturated carboxylic acid grafted polypropylene, ternary random copolymer polypropylene (PP-R) Matching basis: This scheme requires the heat-sealing layer to be tightly sealed and resistant to electrolyte immersion. Homopolymer polypropylene has a melting point of more than 165°C, and its structure is stable at high temperatures, making it the core substrate of the heat-sealing layer; unsaturated carboxylic acid grafted polypropylene is modified by polar groups to enhance the compatibility with aluminum foil and other resins, and to improve the interlayer bonding force; ternary random copolymer polypropylene (PP-R) has a moderate heat-sealing temperature and excellent sealing effect, and the combination of the three can achieve the goal of "high-temperature sealing reliability and electrolyte resistance".

[0074] The application implementation and related data of the above-mentioned raw materials are as follows: One, application implementation example and experimental data of polyamide resin (outer protective layer) (One) Application implementation example In this embodiment, the outer protective layer uses three kinds of polyamide resins, namely nylon 6 (PA6), nylon 66 (PA66), and m-xylylenediamine adipamide (MXD6). They are all prepared according to the raw material ratio in the application file (polyamide resin: anti-UV agent: anti-hygrothermal agent = 90:5:5). The anti-UV agent is 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, and the anti-hygrothermal agent is hydrophobically modified nano-silicon dioxide with a particle size of 20-30 nm. The preparation process strictly follows the process parameters of Step 1: the temperature of the twin-screw extruder is 230-250°C, the screw speed is 300-350 r / min, and the cooling roller temperature is 40-50°C. The outer layer substrate with a thickness of 15-20 μm is obtained, and the first protrusion with a height of 2-3 μm and a spacing of 5-8 mm is processed on the edge, and the second groove with a depth of 1-2 μm and a diameter of 3-5 mm is processed in the center.

[0075] (II) Experimental data Polyamide resin type Tensile strength (MPa) Tensile strength retention rate after UV aging for 500h (%) Moisture absorption rate in a hygrothermal environment (40℃, 90% RH) for 72h (%) Punch toughness (kJ / m²) Surface flatness error (μm) Nylon 6 (PA6) 85±3 92±1.5 0.45±0.03 55±4 ≤0.4 Nylon 66 (PA66) 98±4 91±1.2 0.42±0.02 62±3 ≤0.35 MXD6 90±3.5 95±1.0 0.38±0.02 58±3.5 ≤0.45 Experimental explanation: The three kinds of polyamide resins all meet the core requirement of the outer protective layer "high temperature resistance and stable mechanical properties". Among them, MXD6 has the best anti-UV aging and anti-hygrothermal performance, nylon 66 has outstanding rigidity and stamping toughness, and PA6 has balanced comprehensive performance. The solid-state battery can be flexibly selected according to different application scenarios (such as outdoor energy storage and power battery).

[0076] II. Application examples and experimental data of polyester resin (adhesive layer / composite layer) (I) Application examples The adhesive layer / composite layer uses three kinds of polyester resins, namely biaxially oriented polyester (BOPET) resin, thermoplastic polyester elastomer (TPEE), and anhydride modified polyester composite glue, which are prepared according to the application file ratio (polyester resin: nano ceramic particles = 85:15). The nano ceramic particles are aluminum nitride / aluminum oxide (particle size 50-100 nm) modified by silane coupling agent (KH-550) with a modification temperature of 80-90°C and a time of 1-1.5h. Follow the process parameters of Step 2: after uniform stirring by high-speed mixer, melt extrusion by extruder at 260-280°C, and cast molding to obtain a 25-30 μm thick middle layer substrate. The first groove matching the first protrusion is processed on the edge, and the second protrusion matching the second groove is processed in the center. The containing groove is processed using a gradual stamping process (speed 2-3 mm / s) to ensure that the groove wall perpendicularity error is ≤1° and the groove bottom flatness is ≤0.3 μm.

[0077] (II) Experimental data Polyester resin type Puncture resistance (N) Interlayer peeling force (N / 15mm) Interlayer stability after 50 times of high-temperature cycle at 180℃ Mass change rate after electrolyte immersion (60℃, 72h) (%) Dimensional stability (deformation rate) after 24h at 150℃ (%) BOPET resin 38±2 10±0.8 No delamination, no cracking 0.8±0.1 0.3±0.05 TPEE 35±1.5 11.5±0.6 No delamination, good flexibility 0.6±0.08 0.25±0.03 Anhydride-modified polyester composite adhesive 40±2.5 12±0.7 No delamination, firm adhesion 0.5±0.06 0.2±0.04 Experimental notes: all three polyester resins achieve the goal of "firm interlayer combination", the anhydride modified polyester composite adhesive has the best puncture strength and electrolyte resistance, the interlayer peeling force and flexibility of TPEE are outstanding, and the BOPET resin has excellent dimensional stability. It can be used in combination according to the interlayer bonding strength of aluminum plastic film and the use environment requirements.

[0078] III. Application examples and experimental data of carbon nanotubes (functional enhancement layer) (I) Application examples The functional enhancement layer selects multi-walled carbon nanotubes (MWCNTs) and carboxylated multi-walled carbon nanotubes (COOH-MWCNTs), and is prepared into paste slurry according to the ratio in the application file (carbon nanotube: phenolic resin = 30:70). The 3D printing technology of fused deposition forming is adopted, the printing speed is 10-15mm / s, the nozzle diameter is 0.2-0.3mm, the fishbone-shaped carbon skeleton (main bone diameter 0.5-0.8mm, branch length 2-3mm, interval 4-6mm) is printed at the bottom of the middle layer containing groove, and then it is solidified according to the segmented temperature rising process (60℃ for 30min, 120℃ for 90min).

[0079] (II) Experimental data Carbon nanotube type Fishbone skeleton bending strength (MPa) Heat distortion temperature (℃) Aluminum-plastic film impact resistance (1m drop) Thermal conductivity (W / (m・K)) Compatibility with resin matrix (dispersion uniformity %) Multi-walled carbon nanotube (MWCNTs) 150±8 255±5 No breakage, no cracking 1.8±0.15 92±2 Carboxylated multi-walled carbon nanotube (COOH-MWCNTs) 165±10 260±6 No breakage, no cracking 2.1±0.18 98±1 Experimental notes: both kinds of carbon nanotubes can effectively improve the thermal conductivity and mechanical properties of aluminum plastic film. The carboxylated modified carbon nanotubes have enhanced compatibility with the resin matrix due to the surface active groups, and the bending strength and thermal conductivity are better than those of unmodified multi-walled carbon nanotubes, which improves the impact resistance of aluminum plastic film by more than 50%, and is more suitable for the needs of solid-state battery resistance to external impact.

[0080] IV. Application examples and experimental data of phenolic resin (high-temperature resistant crosslinking layer) (I) Application examples The high-temperature resistant crosslinking layer selects boron modified phenolic resin and phenol-resorcinol-formaldehyde co-condensation resin, and prepares fishbone-shaped carbon skeleton slurry with carbon nanotubes at a ratio of 30:70. The subsequent 3D printing and solidification process is the same as the carbon nanotube application example. At the same time, the two kinds of phenolic resins are used in the epoxy resin synergistic system of the high-temperature resistant and corrosion resistant flame retardant layer to verify the crosslinking enhancement effect.

[0081] (II) Experimental data Phenolic resin type Carbon-based skeleton heat distortion temperature (℃) Strength retention rate after 100h of high-temperature aging at 180℃ (%) Flame retardant grade Volume change rate after electrolyte immersion (80℃, 100h) (%) Crosslinking density (mol / cm³) Boron-modified phenolic resin 265±8 90±2.5 V-0 1.2±0.15 3.8×10⁻³±0.2×10⁻³ Phenol-resorcinol-formaldehyde co-condensation resin 270±10 93±2.0 V-0 0.9±0.12 4.2×10⁻³±0.3×10⁻³ Experimental notes: both phenolic resins meet the requirements of “high temperature resistance and chemical corrosion resistance”, the heat distortion temperature is more than 250℃, and the flame retardant level reaches V-0 level. The high temperature stability and electrolyte resistance of phenol-resorcinol-formaldehyde co-condensation resin are better, and the boron modified phenolic resin has more balanced flame retardant and mechanical properties. The solid state battery high temperature working condition strength can be flexibly selected.

[0082] V. Application examples and experimental data of epoxy resin (adhesive layer / high temperature resistant layer) (I) Application examples The adhesive layer / high temperature resistant layer selects bisphenol A type epoxy resin (E-51), hydroxyl-terminated polyether sulfone epoxy resin, and phenolic epoxy resin (F-44). The high temperature resistant, corrosion resistant and flame retardant slurry is prepared according to the ratio in the application file (aluminum hydroxide: epoxy resin = 40:60), and is also used for the sealant layer (adding 10% organic modified nano montmorillonite). The preparation process follows the process parameters of step 4 and step 8: slurry solid content 50-60%, coating speed 5-8m / min, hot air circulation drying (air speed 1-1.5m / s, 80-100℃, 1-1.5h); sealant layer thickness 3-5μm, scraper angle 45-60°, 100-120℃ curing 1-1.5h.

[0083] (II) Experimental data Epoxy resin type Adhesion of high-temperature corrosion-resistant flame-retardant layer (MPa) Sealing property at 180℃ (leakage rate Pa・m³ / s) Impact cracking resistance (kJ / m²) Water and oxygen permeation rate of sealant layer (cc / (m²・24h・atm)) Flatness of cured adhesive layer (μm) Bisphenol A type epoxy resin (E-51) 5.2±0.3 ≤ 1 x 10"1 0 ]] 48±3 0.05±0.005 ≤0.3 Hydroxyl-terminated polyether sulfone epoxy resin 5.8±0.4 ≤8×10⁻¹¹ 55±4 0.04±0.003 ≤0.25 Phenolic epoxy resin (F-44) 6.0±0.35 ≤5×10⁻¹¹ 52±3.5 0.035±0.004 ≤0.28 Experimental notes: three kinds of epoxy resins achieve the collaborative goal of “firm adhesion and high temperature resistance”. The adhesion and water-oxygen barrier performance of phenolic epoxy resin (F-44) is the best, the anti-cracking performance of hydroxyl-terminated polyether sulfone epoxy resin is outstanding, and bisphenol A type epoxy resin (E-51) has balanced comprehensive performance and cost advantage, which is suitable for different sealing strength requirements of solid state battery packaging scene.

[0084] VI. Application examples and experimental data of polyolefin resin (heat sealing layer) (I) Application examples The heat sealing layer selects homopolymer polypropylene (PP), unsaturated carboxylic acid grafted polypropylene, and ternary random copolymer polypropylene (PP-R) according to the ratio in the application file (polyolefin resin: crosslinking agent: self-repairing microcapsule = 88:2:10). The crosslinking agent selects dicumyl peroxide (added in two steps, 50% first, then 50% after melting for 10min), and the self-repairing microcapsule has a particle size of 5-10μm and a capsule wall thickness of 1-1.5μm. The preparation follows the process parameters of step 5: 180-200℃ melting and blending, extrusion molding to obtain 20-25μm thick inner layer substrate, processing the first protrusion on the edge and the second groove in the center to ensure that the water and oxygen barrier rate is ≤0.1cc / (m²・24h・atm).

[0085] (II) Experimental data Polyolefin resin type Water and oxygen barrier rate (cc / (m²・24h・atm)) High-temperature resistance at 180℃ (strength retention rate after 100h of heat aging %) Self-repairing efficiency (for cracks ≤5μm, %) Heat sealing strength (N / 15mm) Surface state after electrolyte immersion (60℃, 72h) Homopolymerized polypropylene (PP) 0.08±0.01 88±2.5 80±3 15±1.2 No bubbling, no cracking Unsaturated carboxylic acid grafted polypropylene 0.07±0.008 90±2.0 83±2.5 17±1.0 No bubbling, no cracking Ternary random copolymerized polypropylene (PP-R) 0.06±0.006 89±2.2 85±2.0 18±1.5 No bubbling, no cracking Experimental description: The three polyolefin resins meet the requirements of "high-temperature sealing reliability and electrolyte corrosion resistance", the thermal sealing strength and self-repair efficiency of the ternary random copolymerized polypropylene (PP-R) are optimal, the water and oxygen barrier performance and interlayer compatibility of the unsaturated carboxylic acid grafted polypropylene are outstanding, and the homopolymerized polypropylene (PP) has a cost advantage. The optimal raw material combination (MXD6 polyamide resin + acid anhydride modified polyester composite glue + carboxylated multi-walled carbon nanotube + phenol-resorcinol-formaldehyde co-condensation resin + phenolic epoxy resin (F-44) + ternary random copolymerized polypropylene (PP-R)) is selected to prepare a complete solid-state battery high-temperature-resistant aluminum plastic film, and the comprehensive performance test data are as follows:

[0086] Seven, comprehensive performance verification experimental data The optimal raw material combination (MXD6 polyamide resin + acid anhydride modified polyester composite glue + carboxylated multi-walled carbon nanotube + phenol-resorcinol-formaldehyde co-condensation resin + phenolic epoxy resin (F-44) + ternary random copolymerized polypropylene (PP-R)) is selected to prepare a complete solid-state battery high-temperature-resistant aluminum plastic film, and the comprehensive performance test data are as follows: Comprehensive performance index Test result Industry conventional standard Performance improvement rate (%) Overall puncture resistance (N) 45±3 ≥25 80 Interlayer peeling force after 50 times of high-temperature cycle at 180℃ (N / 15mm) 13±0.8 ≥8 62.5 Tensile strength retention rate after UV aging for 500h (%) 94±1.2 ≥70 34.3 Moisture absorption rate in a hygrothermal environment (40℃, 90% RH) for 72h (%) 0.35±0.02 ≤1.5 76.7 Leakage rate after battery packaging (Pa・m³ / s) ≤5×10⁻¹¹ ≤ 1 x 10⁻ 6 ]] 99.995 Capacity retention rate after 1000 times of solid-state battery cycle (%) 88±2.0 ≥70 25.7 Experimental description: The aluminum plastic film prepared by the optimal raw material combination far exceeds the industry conventional standard in core indicators such as high-temperature resistance, mechanical strength, interlayer adhesion stability and electrolyte compatibility, and fully adapts to the requirements of solid-state battery fast charging high-temperature environment, outdoor complex working conditions and long-term cyclic use, verifying the scientificity and adaptability of the selection of each raw material.

[0087] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or basic characteristics of the present application; therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application, and any reference signs in the claims should not be regarded as limiting the claims involved.

[0088] Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high-temperature resistant aluminum-plastic film for solid-state batteries, characterized in that: The material employs a three-layer composite resin structure. The outer layer (1) is modified polyamide with UV resistance and moisture resistance; the middle layer (2) is nano-ceramic doped polyester with improved puncture resistance; and the inner layer (3) is cross-linked polyolefin with self-healing function to enhance water and oxygen barrier properties. Several first protrusions (10) are provided at the edges of both the outer layer (1) and the inner layer (3), and several first grooves (20) matching the first protrusions (10) are provided at the edges of the middle layer (2). Several second grooves (40) are provided at the centers of both the outer layer (1) and the inner layer (3), and a second protrusion (30) matching the second grooves (40) is provided at the center of the middle layer (2). The intermediate layer (2) is formed into a receiving groove (21) by stamping. The bottom of the receiving groove (21) is covered with a fishbone-shaped carbon-based skeleton (4). The inner surface of the receiving groove (21) is provided with a high-temperature resistant, corrosion-resistant, and flame-retardant layer (5) and a hot-melt adhesive layer (6) by melting. The corner section of the outer layer (1) includes a connected transition area (7) and a sealing area (8). The inner surface of the transition area (7) is provided with a high-temperature resistant, corrosion-resistant, and flame-retardant layer (5) and a hot-melt adhesive layer (6). The inner surface of the sealing area (8) is provided with a sealant layer (9). The two aluminum-plastic film structures are sealed in the sealing area to form the outer shell of the battery pack.

2. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 1, characterized in that: The preparation method is as follows: Step 1: Preparation of outer layer modified polyamide Polyamide resin is mixed with UV stabilizer and heat stabilizer at a mass ratio of 90:5:5 and fed into a twin-screw extruder. The mixture is melt-blended at 230-250°C and extruded through a T-die. The mixture is then shaped by a cooling roller to obtain an outer layer (1) substrate with a thickness of 15-20 μm. Subsequently, a first protrusion (10) is processed on the edge of the substrate and a second groove (40) is processed in the center. Step 2: Preparation of intermediate layer nano-ceramic doped polyester Polyester resin and nano-ceramic particles are mixed at a mass ratio of 85:15, added to a high-speed mixer and stirred evenly, then fed into an extruder and melt-extruded at 260-280℃. A middle layer (2) substrate with a thickness of 25-30μm is obtained by casting. A first groove (20) is processed on the edge of the substrate and a second protrusion (30) is processed in the center. The substrate is then stamped to form a receiving groove (21). Step 3: Laying out the fishbone-shaped carbon-based framework Carbon nanotubes and phenolic resin were mixed at a mass ratio of 30:70 to form a paste. The paste was then printed on the bottom of the receiving tank (21) using 3D printing technology to form a fishbone-shaped carbon-based skeleton (4), which was then cured at 120-150℃ for 2-3 hours. Step 4: Preparation of high-temperature resistant, corrosion-resistant, and flame-retardant layer and hot-melt adhesive layer Aluminum hydroxide and epoxy resin are mixed in a mass ratio of 40:60 to prepare a high-temperature resistant, corrosion-resistant, and flame-retardant slurry. Ethylene-vinyl acetate copolymer is heated to 180-200℃ to melt and prepare a hot melt adhesive. Using a dual-head coating machine, a high-temperature resistant, corrosion-resistant, and flame-retardant slurry is first coated on the inner surface of the receiving tank (21), and then dried at 80-100℃ for 1-1.5h to form a high-temperature resistant, corrosion-resistant, and flame-retardant layer (5). Then, a hot melt adhesive is coated on the surface of this layer and naturally cooled to room temperature to form a hot melt adhesive layer (6). Step 5: Preparation of inner layer cross-linked polyolefin Polyolefin resin, crosslinking agent, and self-healing microcapsules are mixed at a mass ratio of 88:2:10 and melt-blended at 180-200℃. The mixture is then extruded to obtain an inner layer (3) substrate with a thickness of 20-25μm. A first protrusion (10) is processed at the edge of the substrate, and a second groove (40) is processed at the center. Step 6: Electric field-induced interlayer recombination The outer layer (1), middle layer (2), and inner layer (3) are stacked in sequence to ensure that the first protrusion (10) and the first groove (20) and the second protrusion (30) and the second groove (40) are precisely matched. The layers are placed in an electric field induction device and a DC electric field with an intensity of 5-10kV / cm is applied. The layers are kept at 60-80℃ for 30-40 minutes to promote the interlayer molecular penetration and enhance the bonding strength. Step 7: Vacuum hot melt rotary torque forming The composite three-layer structure is fed into a vacuum hot melt molding machine. The vacuum degree is set to -0.095 to -0.098 MPa and the temperature is 150-170℃. A rotational torque is applied to make the interlayer hot melt adhesive layer (6) flow fully and fill the interlayer gap. After holding for 20-30 minutes, it is cooled to room temperature to complete the overall molding. Step 8: Sealant layer coating and encapsulation pretreatment Epoxy resin sealant is applied to the inner surface of the encapsulation area (8) at the corner of the outer layer (1), with a thickness of 3-5 μm. It is cured at 100-120℃ for 1-1.5 h. At the same time, a high-temperature resistant, corrosion-resistant, and flame-retardant layer (5) and a hot melt adhesive layer (6) are applied to the inner surface of the transition area (7) to finally obtain a high-temperature resistant aluminum-plastic film for solid-state batteries.

3. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 2, characterized in that: In step 1, the UV-resistant agent is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and the heat-resistant agent is hydrophobic modified nano-silica with a particle size of 20-30nm. The screw speed of the twin-screw extruder is controlled at 300-350r / min, and the cooling roller temperature is set at 40-50℃ to ensure that the surface flatness error of the outer layer (1) substrate is ≤0.5μm. The height of the first protrusion (10) is 2-3μm and the spacing is 5-8mm. The depth of the second groove (40) is 1-2μm and the diameter is 3-5mm.

4. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 2, characterized in that: In step 2, the nano-ceramic particles are surface modified with silane coupling agent at a temperature of 80-90℃ for 1-1.5h to improve compatibility with polyester resin. When stamping the receiving tank (21), a progressive stamping process is adopted with a stamping speed of 2-3mm / s to ensure that the verticality error of the tank wall is ≤1° and the flatness of the tank bottom is ≤0.3μm, so as to avoid cracks in the intermediate layer (2) substrate due to stamping stress.

5. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 2, characterized in that: In step 3, 3D printing adopts fused deposition modeling technology with a printing speed of 10-15 mm / s and a nozzle diameter of 0.2-0.3 mm; the main bone diameter of the fishbone-shaped carbon-based skeleton (4) is 0.5-0.8 mm, the branch length is 2-3 mm, and the spacing is 4-6 mm. During the curing process, segmented heating is adopted to avoid internal stress caused by temperature difference in the skeleton.

6. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 2, characterized in that: In step 4, the solid content of the high-temperature resistant anti-corrosion and flame-retardant slurry is controlled at 50-60%, the coating speed is 5-8m / min, and the drying process adopts hot air circulation drying with a wind speed of 1-1.5m / s; the melt index of the hot melt adhesive is controlled at 8-10g / 10min, and the coating thickness error is ≤0.3μm, to ensure that the high-temperature resistant anti-corrosion and flame-retardant layer (5) and the hot melt adhesive layer (6) are free of bubbles and pinholes.

7. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 2, characterized in that: In step 5, the particle size of the self-healing microcapsules is 5-10 μm and the thickness of the capsule wall is 1-1.5 μm to ensure that they do not break during the melting of polyolefins; the crosslinking agent is added in steps to avoid excessive local crosslinking that could lead to embrittlement of the substrate; the water and oxygen barrier rate of the inner layer (3) substrate must reach ≤0.1cc / (m²・24h・atm).

8. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 2, characterized in that: In step 6, the electrode spacing of the electric field induction device is 10-15 mm. Before applying the electric field, the surface of the three-layer structure is subjected to plasma treatment to remove surface oil and impurities. During the electric field induction process, the interlayer resistance change is monitored in real time. When the resistance value stabilizes at 10^6-10^7 Ω, it is determined that the molecular penetration has reached the optimal state, and the electric field application is stopped.

9. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 2, characterized in that: In step 7, the rotational torque of the vacuum hot melt forming machine is applied in a gradient manner to avoid excessive instantaneous torque that could lead to interlayer misalignment; the cooling process adopts segmented cooling, and the cooling rate is controlled to be ≤5℃ / min to prevent the structure from deforming due to thermal stress.

10. The method for preparing a high-temperature resistant aluminum-plastic film for solid-state batteries according to claim 2, characterized in that: In step 8, the nano-montmorillonite of the sealant layer (9) is organically modified to improve its dispersibility with epoxy resin; when applying the sealant, a scraper is used and the scraper angle is controlled at 45-60° to ensure uniform thickness of the sealant layer; after curing, the sealing area (8) is tested for sealing to ensure no leakage points.

Images