A battery aluminum-plastic film composite material applied to a new energy vehicle

Abstract

This invention discloses a battery aluminum-plastic film composite material for new energy vehicles, aiming to solve the problem that existing materials cannot meet the stringent requirements of new energy vehicles. It comprises a three-layer structure from the outside in: an outer protective layer is a high-strength aluminum alloy sheet with a thickness of 20-50 μm containing specific rare earth elements and a Vickers hardness of 80-120 HV, which undergoes micro-arc oxidation treatment to improve corrosion resistance; the middle barrier layer is composed of alternating layers of modified PVA film with a crosslinking degree of 30%-60% and ultra-thin aluminum foil, with a total thickness of 10-30 μm, exhibiting excellent water vapor and oxygen barrier properties; the inner heat-sealing layer is a novel thermoplastic elastomer material incorporating 2%-8% nano-silica, with a thickness of 10-20 μm, providing good heat-sealing performance and electrode compatibility. This material is meticulously prepared with strictly controlled parameters for each layer, making it suitable for various new energy vehicle scenarios such as urban commuting, long-distance highway travel, extreme climate regions, and high-performance sports cars. Its comprehensive performance is outstanding, strongly promoting the development of the new energy vehicle industry.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and in particular to an aluminum-plastic film composite material for use in new energy vehicles. Background Technology

[0002] As the global automotive industry accelerates its transformation towards new energy vehicles, the safety, stability, and lifespan of power batteries, as core components of new energy vehicles, have received significant attention. Battery aluminum-plastic film, as the outer packaging material for power batteries, plays a crucial role in protecting the internal battery cells from external environmental corrosion and mechanical impacts.

[0003] Traditional aluminum-plastic film for batteries reveals numerous shortcomings when facing the complex and varied operating conditions of new energy vehicles. On one hand, ordinary outer materials have limited mechanical strength, making them unable to withstand the frequent vibrations, collisions, and impacts from stones during vehicle operation, easily leading to damage and threatening the safety of the battery cells. On the other hand, the barrier properties of the intermediate layer are insufficient, failing to effectively prevent the long-term penetration of moisture and oxygen, making the internal chemical system of the battery susceptible to interference, resulting in rapid capacity decay and shortened battery life. Furthermore, the heat-sealing effect of the inner heat-sealing layer is unstable, with insufficient heat-sealing strength or poor compatibility with the cell materials, easily causing leakage at the encapsulation point, aging and cracking, seriously affecting the overall performance and reliability of the battery. Therefore, the development of a novel aluminum-plastic film composite material for batteries that can fully meet the stringent requirements of new energy vehicles is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a battery aluminum-plastic film composite material for new energy vehicles. With its unique three-layer structure design and precise control of the material composition and process parameters of each layer, it successfully achieves an excellent balance of barrier performance, mechanical strength and heat sealing performance, thus solving the problem of inconsistent performance of existing battery aluminum-plastic film materials.

[0005] This invention is achieved through the following technical solution:

[0006] The battery aluminum-plastic film composite material of the present invention is carefully designed from the outside to the inside as an outer protective layer, an intermediate barrier layer and an inner heat-sealing layer.

[0007] Outer protective layer:

[0008] Utilizing high-strength aluminum alloy sheets containing aluminum, magnesium, zinc, and trace amounts of rare earth elements, with the rare earth element content precisely controlled at 0.1%-1% of the total alloy weight, and with the outer protective layer's thickness strictly limited to 20-50μm, its Vickers hardness reaches 80-120HV according to professional testing. This unique alloy formula and thickness design endow the outer protective layer with excellent impact resistance and wear resistance, enabling it to effectively resist various external mechanical forces in the complex operating environment of new energy vehicles, providing the battery with a rock-solid first line of defense.

[0009] Intermediate barrier layer:

[0010] The structure is a multilayer composite consisting of alternating layers of modified polyvinyl alcohol (PVA) film and ultrathin metal foil. The crosslinking degree of the modified PVA film is precisely adjusted to 30%-60%, and the ultrathin metal foil is made of aluminum foil with a purity of no less than 99.5%. The total thickness of the intermediate barrier layer is precisely controlled between 10-30 μm. This precise structural and parameter setting ensures that the water vapor transmission rate is less than 0.01 g / (m²). 2 ·d), oxygen permeability is less than 0.001 cm 3 / (m 2 (·d·Pa) creates a highly stable chemical environment inside the battery, greatly extending the battery's lifespan.

[0011] Inner heat seal layer:

[0012] A novel thermoplastic elastomer material incorporating nano-sized silica particles is selected, with the nano-silica particles accounting for 2%-8% of the total mass of the thermoplastic elastomer material. The thickness of this inner heat-sealing layer is limited to 10-20 μm, the heat-sealing initiation temperature is stable between 120-150℃, and the heat-sealing strength is ensured to be above 30-50 N / 15 mm. This not only ensures good compatibility with the battery electrodes, avoiding chemical reactions that could affect battery performance, but also achieves a reliable and stable heat-sealing effect, ensuring the sealing and safety of the battery encapsulation.

[0013] As a further improvement to the technical solution of the present invention, the present invention also has the following optimizations to the materials of each layer:

[0014] Outer protective layer:

[0015] Its alloy composition, by weight percentage, is 85%-95% aluminum, 2%-6% magnesium, and 1%-3% zinc. Rare earth elements are finely adjusted within the above-mentioned limited proportions according to actual needs. Through rigorous composition control, the overall performance of the alloy is optimized, perfectly adapting to the complex and ever-changing operating conditions of new energy vehicles.

[0016] The aluminum alloy sheet undergoes micro-arc oxidation treatment to form a ceramic film layer with a thickness of 1-3 μm. This additional treatment significantly enhances the corrosion resistance and insulation of the outer protective layer, further improving the battery's safety in complex environments such as high temperature, humidity, and acid / alkali conditions.

[0017] Intermediate barrier layer:

[0018] The modified PVA film and ultrathin metal foil alternate in 3-5 layers, with each layer tightly bonded together using a vacuum hot-pressing composite process. Each layer of modified PVA film is 2-6 μm thick, and the ultrathin metal foil is 4-8 μm thick. This sophisticated structural design and process work together to enhance barrier performance, ensuring an impeccable intermediate barrier layer.

[0019] The modified PVA film incorporates 0.5%-2% nano-montmorillonite by mass during its preparation. Through intercalation and composite processing, the nano-montmorillonite further enhances the film's barrier properties, reducing water vapor permeability by 10%-20% and oxygen permeability by 15%-25%, thus providing superior protection for the battery.

[0020] Inner heat seal layer:

[0021] The novel thermoplastic elastomer material used is selected from one or more of styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), or their modified derivatives, which fully ensures the material's flexibility and heat-sealing performance, meeting the needs of large-scale industrial production.

[0022] During the processing and molding process, an antioxidant with a mass fraction of 0.1%-0.5% is added. The antioxidant is selected from one or more of hindered phenolic antioxidants and phosphite antioxidants. This measure effectively prevents the material from aging and degrading under long-term high-temperature environments, ensuring that the heat-sealing layer maintains stable performance throughout the battery's long service life.

[0023] The present invention has the following beneficial effects:

[0024] The battery aluminum-plastic film composite material of the present invention, with its unique three-layer structure design and precise control of the material composition and process parameters of each layer, has successfully achieved an excellent balance of barrier performance, mechanical strength and heat sealing performance, and has solved the problem of inconsistent performance of existing battery aluminum-plastic film materials.

[0025] The high-strength aluminum alloy sheet of the outer protective layer, combined with the surface micro-arc oxidation treatment, provides the battery with super physical protection, effectively resists external mechanical damage, greatly extends the actual service life of the battery, significantly reduces the risk of failure caused by damage to the battery shell in new energy vehicles, and improves the reliability and safety of vehicle operation.

[0026] The multi-layered composite fine structure of the intermediate barrier layer and the nano-montmorillonite enhancement modification significantly improve the barrier performance against moisture and oxygen, almost perfectly maintaining the stability of the internal chemical environment of the battery, ensuring high consistency and reliability of battery performance, effectively reducing battery capacity decay and safety hazards caused by environmental factors, and extending the battery's driving range.

[0027] The novel thermoplastic elastomer material of the inner heat-sealing layer, combined with antioxidants, not only ensures excellent heat-sealing performance but also improves compatibility with battery electrodes. This simplifies the encapsulation process, improves encapsulation quality, and reduces production costs, providing a solid technical guarantee for the large-scale industrial production and commercial promotion of new energy vehicle batteries. Detailed Implementation

[0028] The present invention will be described in detail below with reference to embodiments and specific examples. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0029] It should be noted that all directional indications (such as up, down, left, right, front, back, upper end, lower end, top, bottom, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the embodiment). If the specific posture changes, the directional indication will also change accordingly.

[0030] In this invention, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention.

[0032] The present invention will now be described in further detail.

[0033] A battery aluminum-plastic film composite material for new energy vehicles comprises, from the outside to the inside, an outer protective layer, a middle barrier layer, and an inner heat-sealing layer, wherein:

[0034] The outer protective layer is a high-strength aluminum alloy sheet containing aluminum, magnesium, zinc and trace rare earth elements. The content of rare earth elements accounts for 0.1%-1% of the total weight of the alloy. The thickness of the outer protective layer is 20-50μm, and its Vickers hardness reaches 80-120HV.

[0035] The intermediate barrier layer is a multilayer composite structure formed by alternating layers of PVA film and ultrathin metal foil. The degree of crosslinking of the modified PVA film is 30%-60%, and the ultrathin metal foil is aluminum foil with a purity of not less than 99.5%. The total thickness of the intermediate barrier layer is between 10-30 μm.

[0036] The inner heat-sealing layer is a novel thermoplastic elastomer material incorporating nano-sized silica particles. The mass of the nano-silica particles accounts for 2%-8% of the total mass of the thermoplastic elastomer material. The thickness of the inner heat-sealing layer is 10-20μm, its heat-sealing initiation temperature is between 120-150℃, and its heat-sealing strength is above 30-50N / 15mm.

[0037] Specifically, in this embodiment, the alloy composition of the outer protective layer, by weight percentage, is 85%-95% aluminum, 2%-6% magnesium, 1%-3% zinc, and rare earth elements are slightly adjusted within the above-mentioned limited proportion range.

[0038] Specifically, in this embodiment, the intermediate barrier layer consists of 3-5 alternating layers of modified PVA film and ultrathin metal foil, which are tightly bonded together by a vacuum hot-pressing composite process. The thickness of each modified PVA film layer is 2-6 μm, and the thickness of each ultrathin metal foil layer is 4-8 μm.

[0039] Specifically, in this embodiment, the novel thermoplastic elastomer material used in the inner heat-sealing layer is selected from one or more of styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), or their modified derivatives.

[0040] Specifically, in this embodiment, a method for using aluminum-plastic film composite materials for batteries in new energy vehicles includes the following steps:

[0041] Outer protective layer preparation:

[0042] The raw materials are accurately weighed according to the predetermined alloy composition ratio, and then melted in a vacuum melting furnace with a vacuum degree of not less than 1×10-3Pa at a temperature of 700-800℃ for a refining time of not less than 30 minutes.

[0043] The cast slab blanks are rolled in multiple passes, with the reduction rate controlled at 10%-20% per pass, and finally annealed at 300-400℃ for 1-2 hours.

[0044] Preparation of intermediate barrier layer:

[0045] Dissolve PVA powder in a mixed solvent of deionized water and anhydrous ethanol (volume ratio 3-4:1) to prepare a 10%-20% concentration solution. Add crosslinking agents such as glutaraldehyde and react at 50-70℃ for 2-4 hours.

[0046] High-purity aluminum ingots are rolled at room temperature using a multi-roll cold rolling mill at a rolling speed of 10-20 m / min to an ultra-thin thickness specification. Then, the modified PVA film and the ultra-thin metal foil are laminated by vacuum hot pressing at a temperature of 150-200℃, a pressure of 5-10 MPa, and a time of 10-20 seconds.

[0047] Inner heat-sealing layer preparation:

[0048] The thermoplastic elastomer raw material and nano silica particles are mixed in a high-speed mixer at 800-1200 rpm for 30-60 minutes until uniformly dispersed. The mixture is then melt-blended and extruded into granules at 160-180℃ using a twin-screw extruder at a screw speed of 200-300 rpm.

[0049] The obtained masterbatch is used to form an inner heat-sealing film at 140-160℃ and a blow-up ratio of 2-3 through a blow molding process.

[0050] Composite molding:

[0051] A dry lamination process is used to bond the outer protective layer, the intermediate barrier layer, and the inner heat-sealing layer with an adhesive application rate of 2-4 g / m². 2 Bonding is performed under composite pressure of 0.2-0.4MPa and temperature of 50-70℃.

[0052] Specifically, in this embodiment, the surface of the aluminum alloy sheet of the outer protective layer is subjected to micro-arc oxidation treatment to form a ceramic film layer with a thickness of 1-3μm.

[0053] Specifically, in this embodiment, the modified PVA film of the intermediate barrier layer is prepared with 0.5%-2% nano-montmorillonite by mass.

[0054] Specifically, in this embodiment, the novel thermoplastic elastomer material of the inner heat-sealing layer is mixed with an antioxidant of 0.1%-0.5% by mass during the processing and molding process. The antioxidant is selected from one or more of hindered phenolic antioxidants and phosphite antioxidants.

[0055] Specifically, in this embodiment, the outer protective layer is rolled using an emulsion lubrication and cooling process, with an emulsion flow rate of 5-10 L / min and an emulsion temperature controlled at 20-30℃.

[0056] Specifically, in this embodiment, the battery aluminum-plastic film composite material after composite molding needs to be subjected to electron beam irradiation treatment, with an irradiation dose of 10-30 kGy.

[0057] The following is a precise preparation method for the battery aluminum-plastic film composite material of the present invention:

[0058] Outer protective layer preparation:

[0059] First, the raw materials are accurately weighed using a high-precision electronic scale according to the predetermined alloy composition ratio, ensuring that the content error of each element is controlled within a very small range. The raw materials are then placed in a vacuum melting furnace with a vacuum degree of not less than 1×10⁻³ Pa, and heated to 700-800℃ for melting. The refining time is no less than 30 minutes, during which the furnace is continuously monitored to ensure thorough impurity removal. For example, in one actual preparation, 90 kg of high-purity aluminum ingots, 4 kg of magnesium ingots, 2 kg of zinc ingots, and 1 kg of a rare earth element-containing intermediate alloy were weighed and added to the melting furnace.

[0060] The cast slab blanks undergo multi-pass rolling, with the reduction rate per pass strictly controlled between 10% and 20% to ensure the uniformity and mechanical properties of the sheet. Finally, annealing at 300-400℃ for 1-2 hours eliminates rolling stress, producing high-strength aluminum alloy sheets that meet the required thickness and mechanical properties. During the rolling process, an emulsion lubrication and cooling process is employed, with the emulsion flow rate precisely controlled at 5-10 L / min and the emulsion temperature stably maintained at 20-30℃. For example, in a certain production batch, the emulsion flow rate was set to 8 L / min, and the temperature was maintained at 25℃, effectively improving the surface quality and flatness of the aluminum alloy sheets and reducing rolling energy consumption.

[0061] Aluminum alloy sheets undergo micro-arc oxidation treatment to form a ceramic film layer with a thickness of 1-3 μm. Taking the outer protective layer of a new energy vehicle as an example, a ceramic film layer with a hardness of not less than 1500 HV was successfully prepared by applying a voltage of 300-500V in a specific electrolyte system and processing for 10-20 minutes using micro-arc oxidation equipment, significantly improving corrosion resistance and insulation.

[0062] Preparation of intermediate barrier layer:

[0063] PVA powder was dissolved in a mixed solvent of deionized water and anhydrous ethanol (volume ratio 3:1-4:1) and continuously stirred with a magnetic stirrer to prepare a 10%-20% concentration solution. Then, crosslinking agents such as glutaraldehyde were added, and the reaction was carried out at 50-70℃ for 2-4 hours. During this time, the reaction process was monitored in real time using online monitoring equipment to ensure optimal crosslinking modification. For example, in one experimental preparation, 150g of PVA powder was dissolved in a mixed solvent of 750ml of deionized water and 250ml of anhydrous ethanol, and 5g of glutaraldehyde was added. The reaction was carried out at 60℃ for 3 hours to obtain a modified PVA solution with excellent performance.

[0064] After the reaction, a film was formed by casting and quickly transferred to a constant temperature and humidity oven for drying at 80-100℃ for 1-2 hours to remove residual solvent. The film was then biaxially stretched 2-3 times to improve its mechanical and barrier properties. One batch of modified PVA film, after drying at 90℃ for 1.5 hours, showed a 2.5-fold biaxial stretch and a water vapor permeability reduced to 0.005 g / (m²). 2 ·d) and below.

[0065] High-purity aluminum ingots are rolled at room temperature using a multi-roll cold rolling mill at a precisely controlled rolling speed of 10-20 m / min to achieve ultra-thin thicknesses. Modified PVA films are then laminated with ultra-thin metal foils via vacuum hot pressing. The hot pressing temperature is set at 150-200℃, the pressure is controlled at 5-10 MPa, and the time is controlled at 10-20 seconds. These layers are alternately stacked to form an intermediate barrier layer, ensuring a tight bond between each layer without defects such as bubbles or delamination. Taking one intermediate barrier layer sample as an example, aluminum ingots with a purity of 99.8% are used, rolled at a speed of 15 m / min to produce an ultra-thin metal foil 6 μm thick. This foil is then alternately stacked with four layers of modified PVA film (each 4 μm thick) and vacuum hot-pressed. After lamination, the oxygen permeability is as low as 0.0005 cm⁻¹. 3 / (m 2 ·d·Pa).

[0066] Inner heat-sealing layer preparation:

[0067] Thermoplastic elastomer raw materials and nano-silica particles are mixed in a high-speed mixer at 800-1200 rpm for 30-60 minutes, with particle dispersion monitored in real time using a laser particle size analyzer to ensure uniform dispersion. Then, the mixture is melt-blended and extruded into granules at 160-180℃ using a twin-screw extruder, with the screw speed stabilized at 200-300 rpm, to produce high-performance masterbatch. For example, 90 kg of SBS thermoplastic elastomer raw material is mixed with 5 kg of nano-silica particles and stirred in a high-speed mixer at 1000 rpm for 45 minutes. After processing by a twin-screw extruder, a stable masterbatch is obtained.

[0068] The obtained masterbatch was used to form an inner heat-sealable layer film through a blow molding process at 140-160℃ and a blow-up ratio of 2-3. During the process, process parameters were adjusted in real time using an online thickness monitoring instrument to ensure the uniformity of film thickness. In one production example, the blow molding temperature was set at 150℃ and the blow-up ratio was 2.5. The thickness of the prepared inner heat-sealable layer film was uniformly controlled at about 15μm, the heat-sealing initiation temperature was 135℃, and the heat-sealing strength reached 40N / 15mm.

[0069] Composite molding:

[0070] A dry lamination process is used to bond the outer protective layer, the middle barrier layer, and the inner heat-sealing layer with an adhesive application rate of 2-4 g / m². 2 The composite material is bonded under a pressure of 0.2-0.4 MPa and a temperature of 50-70℃. During the bonding process, high-precision pressure and temperature sensors are used to monitor the composite parameters in real time to ensure that each layer is tightly bonded and free from defects such as delamination and bubbles, resulting in the final battery aluminum-plastic film composite material. Taking one batch of products as an example, the adhesive application amount is controlled at 3g / m³. 2 The composite material prepared under a composite pressure of 0.3 MPa and a temperature of 60℃ exhibits tight bonding between its layers and excellent performance.

[0071] The composite aluminum-plastic film for batteries, after molding, requires electron beam irradiation treatment, with the irradiation dose precisely controlled between 10-30 kGy. Irradiation cross-linking enhances the bonding force between different parts, improving the overall mechanical properties and temperature resistance of the material, increasing tensile strength by 5%-10% and raising the thermal decomposition temperature by 10-20℃. For example, after irradiating a certain type of aluminum-plastic film composite for batteries with a 20 kGy electron beam, the tensile strength increased from 200 MPa to 210 MPa, and the thermal decomposition temperature increased from 300℃ to 320℃.

[0072] Application scenarios

[0073] Urban commuting scenario: During daily urban driving, new energy vehicles frequently start and stop, subjecting the battery pack to constant vibration and impact. The battery aluminum-plastic film of this invention, with its high-strength aluminum alloy sheet outer protective layer, effectively resists these vibrations, preventing internal cell displacement or casing damage caused by prolonged vibration. Simultaneously, the stable barrier performance of the intermediate barrier layer prevents moisture and oxygen from invading the battery in the complex temperature and humidity environment of the city, maintaining stable battery performance. This ensures that battery capacity degradation is effectively controlled during frequent charging and discharging in congested traffic, allowing drivers to complete their daily commute smoothly without frequent range anxiety.

[0074] High-speed long-distance driving scenario: When new energy vehicles travel at high speeds, the battery pack faces greater wind resistance and strong impacts from road bumps. At this time, the outer protective layer of the battery's aluminum-plastic film not only withstands the impact with its own high strength, but its surface micro-arc oxidation ceramic film layer also resists the erosion of sand, rain, and other substances carried by high-speed airflow, protecting the battery's internal components from damage. During prolonged high-speed driving, the battery generates significant heat. The excellent heat-sealing performance and anti-aging properties of the inner heat-sealing layer ensure the battery's sealing, preventing gaps caused by thermal expansion and contraction. Combined with the efficient barrier layer in the middle, the battery maintains a stable chemical environment under high-temperature and high-speed conditions, providing reliable power support for long-distance travel. Drivers do not need to frequently stop for rest due to battery performance fluctuations.

[0075] Applications in extreme climates: New energy vehicle batteries face severe challenges in the cold winters of the north or the hot, humid summers of the south. At extremely low temperatures, battery materials become more brittle. The outer protective layer of the aluminum-plastic film in this invention buffers against external cold impacts, preventing the battery casing from cracking. The middle barrier layer's near-perfect ability to block moisture and oxygen eliminates the risk of short circuits caused by moisture condensation at low temperatures. In the hot and humid south, its barrier performance also ensures the stability of the battery's internal chemical system, delaying battery aging. This allows new energy vehicles to adapt to the needs of different climate zones, expanding the vehicle's application range. Whether in the icy, snowy Northeast or the sweltering, humid Hainan, the vehicle can operate normally.

[0076] Applications in high-performance sports cars: For new energy sports cars that pursue ultimate performance, powerful output means that the battery needs to withstand higher instantaneous current surges and more intense inertial forces from acceleration and braking. The aluminum-plastic film composite material for batteries in this invention works synergistically across its layers: the outer high-strength protective layer provides mechanical protection, the middle barrier layer maintains battery chemical stability, and the inner heat-sealing layer ensures reliable encapsulation. This meets the extremely high safety and stability requirements of sports cars, ensuring that the battery remains in optimal working condition during high-speed racing or high-speed driving, providing a solid foundation for ultimate speed and handling experience.

[0077] The battery aluminum-plastic film composite material, obtained through the meticulous design and rigorous preparation process described above, underwent a series of professional and stringent performance tests. In terms of barrier properties, its water vapor permeability was less than 0.01 g / (m²). 2 ·d), oxygen permeability is less than 0.001 cm 3 / (m 2 In terms of mechanical strength, the tensile strength reaches over 210MPa, and the heat-sealing performance is good, with a heat-sealing strength of over 30-50N / 15mm. It fully meets the usage requirements of new energy vehicle batteries under various harsh working conditions, providing strong support for the development of the new energy vehicle industry.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] The battery aluminum-plastic film composite material of the present invention, with its unique three-layer structure design and precise control of the material composition and process parameters of each layer, has successfully achieved an excellent balance of barrier performance, mechanical strength and heat sealing performance, and has solved the problem of inconsistent performance of existing battery aluminum-plastic film materials.

[0080] The high-strength aluminum alloy sheet of the outer protective layer, combined with the surface micro-arc oxidation treatment, provides the battery with super physical protection, effectively resists external mechanical damage, greatly extends the actual service life of the battery, significantly reduces the risk of failure caused by damage to the battery shell in new energy vehicles, and improves the reliability and safety of vehicle operation.

[0081] The multi-layered composite fine structure of the intermediate barrier layer and the nano-montmorillonite enhancement modification significantly improve the barrier performance against moisture and oxygen, almost perfectly maintaining the stability of the internal chemical environment of the battery, ensuring high consistency and reliability of battery performance, effectively reducing battery capacity decay and safety hazards caused by environmental factors, and extending the battery's driving range.

[0082] The novel thermoplastic elastomer material of the inner heat-sealing layer, combined with antioxidants, not only ensures excellent heat-sealing performance but also improves compatibility with battery electrodes. This simplifies the encapsulation process, improves encapsulation quality, and reduces production costs, providing a solid technical guarantee for the large-scale industrial production and commercial promotion of new energy vehicle batteries.

[0083] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A battery aluminum-plastic film composite material for use in new energy vehicles, characterized in that, From the outside in, it consists of an outer protective layer, a middle barrier layer, and an inner heat-sealing layer, wherein: The outer protective layer is an aluminum alloy sheet containing aluminum, magnesium, zinc and trace rare earth elements. The content of rare earth elements accounts for 0.1%-1% of the total weight of the alloy. The thickness of the outer protective layer is 20-50μm, and its Vickers hardness reaches 80-120HV. The intermediate barrier layer is a multi-layer composite structure formed by alternating layers of PVA film and metal foil. The cross-linking degree of the PVA film is 30%-60%, and the metal foil is aluminum foil with a purity of not less than 99.5%. The total thickness of the intermediate barrier layer is 10-30 μm; the thickness of each PVA film layer is 2-6 μm, and the thickness of each metal foil layer is 4-8 μm. The inner heat-sealing layer is a thermoplastic elastomer material incorporating nano-silica particles. The mass of the nano-silica particles accounts for 2%-8% of the total mass of the thermoplastic elastomer material. The thickness of the inner heat-sealing layer is 10-20μm, its heat-sealing initiation temperature is 120-150℃, and its heat-sealing strength is 30-50N / 15mm. The thermoplastic elastomer material used in the inner heat-sealing layer is selected from one or more of styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, and their modified derivatives.

2. The aluminum-plastic film composite material for batteries used in new energy vehicles according to claim 1, characterized in that: The alloy composition of the outer protective layer, by weight percentage, is 2%-6% magnesium and 1%-3% zinc.

3. The aluminum-plastic film composite material for batteries used in new energy vehicles according to claim 1, characterized in that: The surface of the aluminum alloy sheet of the outer protective layer is subjected to micro-arc oxidation treatment to form a ceramic film layer with a thickness of 1-3μm.

4. The aluminum-plastic film composite material for batteries used in new energy vehicles according to claim 1, characterized in that: The PVA film of the intermediate barrier layer contains 0.5%-2% nano-montmorillonite by mass during the preparation process.

5. The aluminum-plastic film composite material for batteries used in new energy vehicles according to claim 1, characterized in that: During the processing and molding of the thermoplastic elastomer material of the inner heat-sealing layer, an antioxidant with a mass fraction of 0.1%-0.5% is added. The antioxidant is selected from one or more of hindered phenolic antioxidants and phosphite antioxidants.

6. A method for preparing the battery aluminum-plastic film composite material as described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1, Preparation of the outer protective layer: The raw materials are accurately weighed according to the predetermined alloy composition ratio, and then melted in a vacuum melting furnace with a vacuum degree of not less than 1×10⁻³Pa at a temperature of 700-800℃ for a refining time of not less than 30 minutes. The cast thin plate billet is rolled in multiple passes, with the single pass reduction rate controlled at 10%-20%, and finally annealed at 300-400℃ for 1-2 hours. Step S2, Preparation of the intermediate barrier layer: PVA powder is dissolved in a mixed solvent of deionized water and anhydrous ethanol in a volume ratio of 3-4:1 to prepare a 10%-20% concentration solution. Glutaraldehyde crosslinking agent is added and the mixture is reacted at 50-70℃ for 2-4 hours. Aluminum ingots are rolled at room temperature using a multi-roll cold rolling mill at a rolling speed of 10-20 m / min to the required thickness. Then, PVA film and metal foil are laminated by vacuum hot pressing at a temperature of 150-200℃, a pressure of 5-10 MPa, and a time of 10-20 seconds. Step S3, Inner heat-sealing layer preparation: The thermoplastic elastomer raw material and nano silica particles are mixed in a high-speed mixer at 800-1200 rpm for 30-60 minutes until uniformly dispersed. The mixture is then melt-blended and extruded into granules at 160-180℃ using a twin-screw extruder at a screw speed of 200-300 rpm. The obtained masterbatch is used to form an inner heat-sealing film at 140-160℃ and a blow-up ratio of 2-3 through a blow molding process. Step S4, Composite Molding: A dry lamination process is used to bond the outer protective layer, the middle barrier layer, and the inner heat-sealing layer together under conditions of adhesive application rate of 2-4 g / m², lamination pressure of 0.2-0.4 MPa, and temperature of 50-70℃.

7. The method according to claim 6, wherein the outer protective layer is subjected to an emulsion lubrication and cooling process during rolling, with an emulsion flow rate of 5-10 L / min and an emulsion temperature controlled at 20-30℃.

8. According to the method of claim 6, the composite aluminum-plastic film composite material of the battery after composite molding needs to be subjected to electron beam irradiation treatment, and the irradiation dose is 10-30kGy.