Current collector base material with high-temperature-resistant shape memory function and preparation method thereof

Abstract

The invention discloses a current collector base material with a high-temperature-resistant shape memory function and a preparation method of the current collector base material, and relates to the technical field of battery materials. The method specifically comprises the following steps: S1, uniformly mixing a PET material, a high-temperature-resistant material, a shape memory polymer and a functional additive to obtain a raw material; s2, blending and processing the raw materials to form a melt; extruding to form a thin film; pulling and stretching, cooling and shaping, rolling, and controlling and adjusting quality; a base film is obtained; s3, carrying out antistatic treatment on the base film to obtain a current collector base material; compared with a conventional base membrane, the composite phase change material base membrane shows more excellent performance in the aspects of elastic modulus, extension strength and elongation through a unique strengthening mechanism, a good synergistic effect and a multi-phase structure, and the performance characteristics enable the composite phase change material base membrane to have more advantages in numerous application scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a current collector substrate with a high-temperature resistant shape memory function and a preparation method thereof. Background Art

[0002] In the prior art, composite aluminum current collectors typically consist of an aluminum layer and a polymer layer. However, the aluminum layer and the polymer layer have different expansion coefficients. During processes such as coating, the differential expansion between the two layers can cause overall deformation due to temperature changes, affecting the performance and service life of the material. During the evaporation coating process, the aluminum source (aluminum wire) is heated to a high temperature and evaporates, forming gaseous aluminum atoms. These gaseous aluminum atoms carry a large amount of heat as they deposit onto the surface of the polymer substrate to form the aluminum layer, and the PET layer absorbs the heat from the aluminum vapor. At the same time, to ensure the quality and uniformity of the coating, the entire coating system is usually maintained at a certain high temperature. The aluminum layer, as the part that directly receives heat, continuously absorbs this heat. As heat is absorbed, the thermal motion of atoms within the aluminum layer intensifies, the amplitude of the grain vibration between the aluminum atoms increases, and the spacing between atoms begins to increase. At the microscopic level, the atomic plane spacing in the aluminum crystal structure increases, and the unit cell size becomes larger. For example, the aluminum layer appears blocky when viewed under SEM. From a macroscopic perspective, the aluminum layer expands in both planar directions (such as length and width) and thickness. If the aluminum layer is uniformly deposited on a polymer substrate, its expansion in the planar direction will be constrained by the polymer layer (and existing first- and second-generation aluminum plating equipment cannot deposit completely uniformly on the substrate. Analysis of varying surface resistance indicates that the aluminum layer is not uniformly deposited, which is likely related to the arrangement of the evaporation source). Because aluminum has a greater thermal expansion coefficient than polymer materials, the aluminum layer tends to expand outward, generating thermal stress between the aluminum and polymer layers. When thermal stress exceeds a certain limit, it causes deformation of the composite aluminum current collector, such as bending and warping. Therefore, a new type of intelligent buffer material and corresponding composite structure are needed to overcome this technical challenge.

[0003] In summary, in order to solve the above problems, it is of great significance to provide a current collector substrate with high-temperature resistant shape memory function and a preparation method thereof. Summary of the Invention

[0004] The object of the present invention is to provide a current collector substrate with high-temperature resistant shape memory function and a preparation method thereof, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a current collector substrate with high-temperature resistant shape memory function comprises the following steps:

[0007] S1: Mix PET material, high-temperature resistant material, shape memory polymer, and functional additives evenly to obtain raw materials.

[0008] S2: Co-mix and process the raw materials to form a melt; extrude it to form a film; perform traction stretching, cooling and shaping, winding, quality control and adjustment; obtain a base film.

[0009] S3: Conduct antistatic treatment on the base film to obtain a current collector substrate.

[0010] More preferably, the raw materials include the following substances, by mass: 45 - 55 parts of PET material, 50 parts of high-temperature resistant material, 35 - 40 parts of shape memory polymer, and 2 - 2.2 parts of functional additive.

[0011] The high-temperature resistant material includes polyimide and polyphenylene sulfide with a mass ratio of 6:4 - 9.

[0012] More preferably, the functional additive includes one or more of antioxidant or heat stabilizer.

[0013] More preferably, the functional additive includes antioxidant and heat stabilizer with a mass ratio of 2:1 - 1.2.

[0014] More preferably, the shape memory polymer includes styrene-butadiene copolymer shape memory polymer; the antioxidant includes antioxidant 1010; the heat stabilizer includes calcium stearate.

[0015] More preferably, in step S2, the specific process for preparing the base film is: add the raw materials into a twin-screw extruder, co-mix and process at 260 - 350°C with a screw rotation speed of 100 - 300 r / min to obtain a melt; preheat a flat die to 260 - 350°C; extrude the melt through the flat die with a die inlet pressure of 15 - 30 MPa, use a traction device to perform traction at a traction speed of 3 - 8 m / min, cool and form, wind with a winding tension of 105 - 155 N, conduct quality control and adjustment to obtain a base film.

[0016] More preferably, the thickness of the current collector substrate is 5 - 7 μm.

[0017] Among them, the temperature increase process of the twin-screw extruder needs to be carried out step by step to reduce local overheating of the temperature and cause the material to decompose, and setting within the temperature range of 260 - 350°C can make the three materials melt simultaneously, fully mix and shear in the barrel to form a uniform melt.

[0018] Among them, the mold used in the present invention is a flat-seam mold, which is suitable for preparing films with high requirements for flatness and thickness accuracy. After the twin-screw extruder completes the blending process to form a uniform melt, ensure that the temperature of the melt remains within an appropriate range when passing through the mold. For this composite material, since it contains PET, PI, PPS, shape memory polymer and additives, the mold temperature is preferably set between 260°C and 350°C. According to the flow characteristics of different materials and the requirements of film thickness, the temperature of different parts of the mold can be finely adjusted to ensure the fluidity and uniformity of the melt in the mold. Adjust the pressure of the connection part between the extruder and the mold, and the adjustment of the pressure can be achieved by adjusting parameters such as screw speed and back pressure. Appropriate pressure can ensure that the melt passes through the mold at a stable flow rate and pressure, preventing uneven film thickness or defects. For the film with a common composite current collector thickness of 5-7 μm in the present invention, preferably 6 μm, the pressure at the mold inlet can be controlled between 15-30 MPa.

[0019] Among them, after the melt is extruded from the mold to form a film, a traction device is used to traction the film. The traction speed will affect the thickness and properties of the film. Generally speaking, a higher traction speed will make the film thinner, and at the same time, to a certain extent, it can improve the orientation degree of the film, thereby improving the tensile strength and modulus of the film. The present invention adopts flat-seam extrusion, and the traction speed is set between 3-8 m / min, and it can also be adjusted according to the thickness of the film and the required properties. The film also needs to be cooled and shaped during the traction process to fix its shape and properties. The present invention uses air-cooling method: during air-cooling, an air ring is used to cool the film, so that the film can be quickly cooled to room temperature or slightly higher than room temperature, which can avoid the film from deforming or sticking at high temperature. For thinner films, the cooling speed of air-cooling is relatively slow, but it will not produce water marks, which is suitable for films with high requirements for surface quality. The film after cooling and shaping needs to be wound up, and the film is evenly wound around the reel. The winding tension should be controlled properly to avoid the film from deforming or wrinkling during the winding process. The present invention uses a tension controller to control the winding tension between 105-155 N according to the thickness, width and material properties of the film, which can ensure that the film will not be stretched and deformed due to excessive tension or slack due to too small tension during the winding process.

[0020] Among them, during the thin film production process of the present invention, an on-line thickness measuring instrument is also used to monitor the thickness of the thin film in real time. According to the measurement results, parameters such as the traction speed, screw rotation speed, and die gap are adjusted to ensure the uniformity of the thin film thickness. For example, if it is found that a certain area of the thin film is thicker, the traction speed can be appropriately increased or the screw rotation speed can be decreased to make the thin film in this area thinner; if the thin film is too thin, the traction speed can be decreased or the screw rotation speed can be appropriately increased to increase the extrusion amount of the melt, thereby adjusting the thin film thickness. After the production is completed, performance tests are carried out on the produced thin film, including tensile performance, thermal performance, shape memory performance, etc. According to the test results, the entire production process is optimized, such as adjusting parameters such as the material ratio, processing temperature, and traction speed to meet the performance requirements of the thin film. The last step of thin film preparation is surface treatment, that is, antistatic treatment, which can be achieved by coating an antistatic agent or adding an antistatic masterbatch during raw material preparation to make the thin film surface have antistatic properties. In actual operation, the above parameters of the present invention are continuously adjusted and optimized to obtain a thin film product with stable performance and qualified quality.

[0021] More preferably, during the antistatic treatment process, it specifically includes the following steps:

[0022] (1) Substrate film pretreatment: The substrate film is treated by vacuum plasma (power: 3 - 4 kW, substrate film winding treatment speed: 10 - 15 M / min) to obtain a pretreated substrate film;

[0023] (2) Coating antistatic agent: The antistatic agent is coated on the pretreated substrate film by a microgravure coating process (cell depth: 8 - 12 um, linear speed: 15 - 20 m / min), the wet film thickness is 5 ± 1 um (regulated by the solid content of the coating liquid of 35%), and gradient temperature zone drying is carried out immediately after coating (zone 1: 60 - 80 °C, zone 2: 100 - 120 °C, total duration: 30 - 90 s), and the dry film thickness is 1.75 ± 0.1 μm.

[0024] More preferably, the antistatic agent includes the following raw materials, calculated by 100 parts by mass: 15 - 20 parts of main agent, 0.5 - 3 parts of auxiliary agent, and the rest is solvent; the main agent includes a quaternary ammonium salt type cationic surfactant (molecular weight 2000) and a polyether type nonionic surfactant (HLB value 12) with a mass ratio of 3:1; the auxiliary agent includes a nano-scale metal oxide dispersion (average particle size 10 - 50 nm); the solvent includes a polar solvent and a non-polar solvent with a mass ratio of 1:4.

[0025] More preferably, the current collector substrate is used to prepare a composite current collector; the application of the preparation process of the composite current collector includes the following steps: activating the surface of the current collector substrate and winding evaporation coating to obtain a composite current collector.

[0026] More preferably, the preparation process of the composite current collector includes the following steps: activating the surface of the current collector substrate by plasma treatment, loading it on the unwinding roller, preheating the evaporation area under a vacuum degree <5×10-3Pa, heating up at 80% power, and after reaching the evaporation temperature, guiding the substrate through the evaporation area at a speed of 14-16m / min with a unwinding tension of 195-205N through the guiding roller. At the same time, feeding aluminum wire into the evaporation area at a wire feeding speed of 550-570mm / min, and using the winding roller to collect the composite aluminum current collector with the coating completed at a winding tension of 215-225N. After breaking the vacuum, the composite current collector is obtained.

[0027] Among them, the thickness of the prepared film is selected according to the specific battery application requirements. In the embodiment of the present invention, a 6μm film is preferably used; before aluminizing, the substrate needs to be surface-activated. By using the plasma treatment method, active groups are introduced on the substrate surface to increase its surface energy, providing a good interface for subsequent coating to improve its bonding force with the aluminum film. High-purity aluminum wire is selected as the evaporation source, and the purity is usually required to be above 99.9% to ensure that the aluminized film has good conductivity and other properties.

[0028] Among them, the winding system of the present invention mainly includes an unwinding roller, a winding roller and a guiding roller: the unwinding roller is loaded with the pretreated substrate, and the substrate is guided through the evaporation area at a certain speed through the guiding roller. The winding roller is used to collect the composite aluminum current collector with the coating completed. The present invention adjusts the spacing of the guiding roller and the tension control system according to the thickness and width of the substrate to ensure that the substrate remains flat and the tension is uniform during the winding process, preventing the substrate from wrinkling or loosening during operation. During the process of installing the evaporation source aluminum wire into the evaporation equipment of the present invention, it is necessary to ensure the alignment accuracy of the position of the evaporation source and the heating device so that aluminum atoms can be evenly deposited on the substrate.

[0029] Among them, during the process of winding evaporation coating of the present invention, it is necessary to perform a pre-vacuum treatment in advance. A high-vacuum environment helps to reduce the contamination of the aluminum film by impurity gases, ensure that aluminum atoms are not disturbed during flight, and improve the coating quality. The evaporation system needs to be preheated and slowly heated to avoid material splashing and evaporation source damage caused by sudden temperature rise. Adjust the heating power according to the power of the equipment and the amount of the evaporation source. The present invention preferably has a heating power of 80%. When the evaporation source reaches the evaporation temperature, start the winding system to make the substrate pass through the evaporation area at a certain linear speed. At the same time, the aluminum source starts to evaporate, and aluminum atoms will fly towards the surface of the substrate in a straight line trajectory and deposit on the substrate to form an aluminum film. By controlling the winding speed and evaporation rate, the thickness of the aluminum film can be adjusted. The preferred process of the present invention is: when the winding tension is controlled at 215-225 N, the unwinding tension is controlled at 195-205 N, the winding speed is 14-16 m / min, and the wire feeding speed is 550-570 mm / min, by adjusting the evaporation power, control the deposition rate of the aluminum film to make the final thickness of the aluminum film reach 950-1050 nm.

[0030] Compared with the prior art, the beneficial effects of the present application are as follows:

[0031] (1) The present invention forms a high-temperature resistant composite deformation memory material by introducing a high-temperature resistant polymer material, a shape memory polymer material, and additives into a PET polymer layer material, and obtains a current collector substrate with a high-temperature resistant shape memory function through a specific process and aluminizing. When the coating temperature rises, this material can adaptively adjust its own shape and mechanical properties according to the difference in the expansion coefficients of the aluminum layer and the polymer layer: when the aluminum layer expands, the buffer material can absorb part of the expansion stress of the aluminum layer, and at the same time, through its own elastic deformation, make up for the insufficient expansion of the polymer layer, thereby effectively reducing the overall deformation caused by the expansion difference between the two.

[0032] (2) The present invention uses the compounding of polyimide and polyphenylene sulfide as the high-temperature resistant polymer material, which can improve the high-temperature resistance and processing performance of the composite material; by adding styrene-butadiene copolymer as the shape memory polymer, at high temperature, the soft segment (butadiene part) of the styrene-butadiene copolymer can deform, while the hard segment (styrene part) plays a role in fixing the shape, thereby endowing the material with a shape memory effect; by adding an antioxidant, effectively inhibiting the oxidation reaction of the material at high temperature and extending the service life of the material; by adding a heat stabilizer, further improving the stability of the material. Detailed implementation mode

[0033] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0034] It should be noted that there are no special restrictions on the purchasing manufacturers of all raw materials involved in the present invention. Exemplarily, they include: PET material with a particle diameter of 2 - 4 mm; polyimide with a particle diameter of 2 - 4 mm; polyphenylene sulfide with a particle diameter of 2 - 4 mm; styrene-butadiene copolymer with a molecular weight of 250,000 - 350,000 g / mol; the CAS number of antioxidant 1010: 6683-19-8; the CAS number of calcium stearate: 1592-23-0.

[0035] Among them, in the following examples, "parts" are parts by mass. All raw materials mentioned above and used below but not mentioned are commercially available; the thickness of the prepared current collector substrate is 6 μm.

[0036] Example 1: Preparation of the current collector substrate:

[0037] S1: Mix 50 parts of PET material, 50 parts of high-temperature resistant materials (polyimide and polyphenylene sulfide with a mass ratio of 6:4), 40 parts of shape memory polymer (styrene-butadiene copolymer), and 2.1 parts of functional additives (1.4 parts of antioxidant 1010, 0.6 parts of calcium stearate) evenly to obtain the raw materials.

[0038] S2: Add the raw materials into a twin-screw extruder and conduct co-blending processing at 300 °C with a screw speed of 150 r / min to obtain a melt; preheat the flat die to 300 °C; extrude the melt through the flat die with a die inlet pressure of 23 MPa, use a traction device to perform traction at a traction speed of 5 m / min, cool and form, and wind up with a winding tension of 130 N, and conduct quality control and adjustment to obtain the base film.

[0039] S3: Conduct antistatic treatment on the base film to obtain the current collector substrate.

[0040] Example 2: Preparation of the current collector substrate:

[0041] S1: Mix 50 parts of PET material, 50 parts of high-temperature resistant materials (polyimide and polyphenylene sulfide with a mass ratio of 6:9), 40 parts of shape memory polymer (styrene-butadiene copolymer), and 2.1 parts of functional additives (1.4 parts of antioxidant 1010, 0.6 parts of calcium stearate) evenly to obtain the raw materials.

[0042] S2: Add the raw materials into a twin-screw extruder and conduct co-blending processing at 300 °C with a screw speed of 150 r / min to obtain a melt; preheat the flat die to 300 °C; extrude the melt through the flat die with a die inlet pressure of 23 MPa, use a traction device to perform traction at a traction speed of 5 m / min, cool and form, and wind up with a winding tension of 130 N, and conduct quality control and adjustment to obtain the base film.

[0043] S3: Perform antistatic treatment on the base film to obtain the current collector substrate.

[0044] Example 3: Preparation of the current collector substrate:

[0045] S1: Mix 50 parts of PET material, 50 parts of high-temperature resistant material (polyimide and polyphenylene sulfide with a mass ratio of 6:4), 35 parts of shape memory polymer (styrene-butadiene copolymer), and 2.1 parts of functional additives (1.4 parts of antioxidant 1010, 0.6 parts of calcium stearate) evenly to obtain the raw material;

[0046] S2: Add the raw material into a twin-screw extruder and perform co-blending processing at 300 °C with a screw rotation speed of 150 r / min to obtain the melt; preheat the flat die to 300 °C; extrude the melt through the flat die at a die inlet pressure of 23 MPa, use the traction device to perform traction at a traction speed of 5 m / min, cool and form, and perform winding at a winding tension of 130 N, and conduct quality control and adjustment to obtain the base film;

[0047] S3: Perform antistatic treatment on the base film to obtain the current collector substrate.

[0048] Example 4: Preparation of the current collector substrate:

[0049] S1: Mix 50 parts of PET material, 50 parts of high-temperature resistant material (polyimide and polyphenylene sulfide with a mass ratio of 6:9), 35 parts of shape memory polymer (styrene-butadiene copolymer), and 2.1 parts of functional additives (1.4 parts of antioxidant 1010, 0.6 parts of calcium stearate) evenly to obtain the raw material;

[0050] S2: Add the raw material into a twin-screw extruder and perform co-blending processing at 300 °C with a screw rotation speed of 150 r / min to obtain the melt; preheat the flat die to 300 °C; extrude the melt through the flat die at a die inlet pressure of 23 MPa, use the traction device to perform traction at a traction speed of 5 m / min, cool and form, and perform winding at a winding tension of 130 N, and conduct quality control and adjustment to obtain the base film;

[0051] S3: Perform antistatic treatment on the base film to obtain the current collector substrate.

[0052] Comparative Example 1: Based on Example 1, change the type of high-temperature resistant material, and the specific steps are as follows

[0053] S1: Mix 50 parts of PET material, 50 parts of high-temperature resistant material (polycarbonate and polyphenylene sulfide with a mass ratio of 6:4), 40 parts of shape memory polymer (styrene-butadiene copolymer), and 2.1 parts of functional additives (1.4 parts of antioxidant 1010, 0.6 parts of calcium stearate), and mix evenly to obtain the raw material;

[0054] S2: Add the raw materials into a twin-screw extruder, and conduct blending processing at 300 °C with a screw rotation speed of 150 r / min to obtain a melt; preheat a flat die to 300 °C; extrude the melt through the flat die with an inlet pressure of 23 MPa for the die, use a traction device to conduct traction at a traction speed of 5 m / min, cool and form, and conduct winding with a winding tension of 130 N, conduct quality control and adjustment to obtain a base film;

[0055] S3: Conduct antistatic treatment on the base film to obtain a current collector substrate.

[0056] Comparative Example 2: Based on Example 1, change the type of shape memory polymer, specifically as follows:

[0057] S1: 50 parts of PET material, 50 parts of high-temperature resistant materials (polyimide and polyphenylene sulfide with a mass ratio of 6:4), 40 parts of ordinary polystyrene, 2.1 parts of functional additives (1.4 parts of antioxidant 1010, 0.6 parts of calcium stearate), mix evenly to obtain raw materials;

[0058] S2: Add the raw materials into a twin-screw extruder, and conduct blending processing at 300 °C with a screw rotation speed of 150 r / min to obtain a melt; preheat a flat die to 300 °C; extrude the melt through the flat die with an inlet pressure of 23 MPa for the die, use a traction device to conduct traction at a traction speed of 5 m / min, cool and form, and conduct winding with a winding tension of 130 N, conduct quality control and adjustment to obtain a base film;

[0059] S3: Conduct antistatic treatment on the base film to obtain a current collector substrate.

[0060] Performance test: Use a universal material testing machine to test the current collector substrates prepared in each example and comparative example and the conventionally used PET film (conventional base film), and the experimental data are shown in Table 1.

[0061] Table 1

[0062]

[0063]

[0064] Conclusion: It can be seen from Table 1 that: (1) The elastic modulus of Examples 1 to 4 in the MD direction and TD direction are all higher than that of the conventional base film. The reason is that the composite phase change material introduces a new strengthening mechanism: the phase change material and the base film form a tight chemical bond or strong interaction, which limits the relative movement of the molecular chains; when subjected to external force, the molecular chains are more difficult to displace, and the material's ability to resist elastic deformation is enhanced, thereby increasing the elastic modulus; this strengthening effect is similar to adding more solid supporting components to the building structure, making the overall structure more difficult to deform; in terms of microstructure, the composite process may make the base film microstructure more dense; the addition of phase change material fills the gaps or defects that may have existed in the base film, making the internal structure of the material more uniform and dense. This densified structure increases the rigidity of the material, thereby increasing the elastic modulus.

[0065] Therefore, due to the new strengthening mechanism and densification of the microstructure, the composite phase change material base film (Example) has a higher elastic modulus in the MD and TD directions than conventional base films. This indicates that the composite phase change material base film can better resist external forces and maintain its shape stability during the elastic deformation stage.

[0066] (2) The extension strength of Examples 1 to 4 in the MD and TD directions is higher than that of the conventional base film. The reason is that there is a synergistic effect between the composite phase change material and the base film. The phase change material not only has a certain strength itself, but also can effectively transfer stress when subjected to force after being combined with the base film, making the stress distribution of the entire material system more uniform during the stretching process; the good interface bonding between the composite phase change material and the base film prevents the generation and expansion of cracks; when the material is subjected to tensile force, the interface can effectively transfer the load, avoiding stress concentration in local areas and causing premature fracture of the material, thereby improving the extension strength.

[0067] Therefore, due to the synergistic reinforcement effect and good interface bonding, the composite phase change material base film (embodiment) has higher tensile strength in both the MD and TD directions than conventional base films. This means that the composite phase change material base film is less likely to break when subjected to large tensile loads, and has better structural stability and load-bearing capacity.

[0068] (3) The elongation rates of Examples 1 to 4 in the MD direction and TD direction are higher than those of the conventional base film. The reason is the improvement of material toughness: Although the elastic modulus of the examples is relatively high, the composite phase change material may endow the base film with a certain degree of toughness. This toughness enables the material to absorb energy through the slip and rearrangement of molecular chains during the stretching process, so as to withstand greater deformation without fracture and exhibit a higher elongation rate; The adaptability of the multiphase structure: The multiphase structure of the composite phase change material base film has better adaptability. During the stretching process, different phases can coordinate and deform with each other, avoiding the sudden failure that may occur in single-phase materials. For example, when stressed, the phase change material phase and the base film phase can adjust their shapes together through interfacial interactions, enabling the overall material to withstand a greater degree of stretching.

[0069] Therefore, due to the improvement of material toughness and the good adaptability of the multiphase structure, the elongation rate of the composite phase change material base film (Examples) in the MD and TD directions is higher than that of the conventional base film. This shows that in practical applications, the composite phase change material base film can not only withstand a large tensile force, but also maintain the integrity of the material within a large deformation range, having better plasticity and application potential.

[0070] (4) In Comparative Example 1, when the type of high-temperature resistant material was changed, the high-temperature resistance was insufficient. The glass transition temperature of PC (147 °C) was significantly lower than that of polyimide (PI, Tg > 300 °C), and melt thermal degradation occurred at a processing temperature of 300 °C, with coking spots appearing on the surface of the base film. Moreover, the compatibility between PC and polyphenylene sulfide (PPS) was poor, resulting in a decrease in mechanical strength: phase separation occurred after blending, and the tensile strength of the base film decreased; In Comparative Example 2, when the type of shape memory polymer was changed, due to the loss of shape memory function, PS is an amorphous rigid plastic and lacks the soft segment reversible phase of SBS, so it cannot achieve temperature-responsive deformation and recovery. The shape fixation rate (<10%) is much lower than that of the examples (>85%), and the compatibility between PS and the PET high-temperature resistant material is poor, increasing the brittleness of the base film and greatly decreasing the elongation at break.

[0071] In summary, compared with the conventional base film, the composite phase change material base film of the present invention exhibits more excellent properties in terms of elastic modulus, elongation strength, and elongation rate through unique strengthening mechanisms, good synergistic effects, and the advantages of a multiphase structure. These performance characteristics give it greater advantages in many application scenarios.

[0072] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a current collector substrate with high-temperature resistant shape memory function, characterized in that It includes the following steps: S1: Mix PET material, high-temperature resistant material, shape memory polymer, and functional additive evenly to obtain raw materials; S2: Co-mix and process the raw materials to form a melt; extrude it to form a film; conduct traction stretching, cooling and shaping, winding, quality control and adjustment; obtain a base film; S3: Conduct antistatic treatment on the base film to obtain a current collector substrate.

2. The preparation method of a current collector substrate with high-temperature resistant shape memory function according to claim 1, characterized in that: The raw materials include the following substances, by mass: 45-55 parts of PET material, 50 parts of high-temperature resistant material, 35-40 parts of shape memory polymer, 2-2.2 parts of functional additive.

3. The preparation method of a current collector substrate with high-temperature resistant shape memory function according to claim 1, characterized in that: The high-temperature resistant material includes polyimide and polyphenylene sulfide with a mass ratio of 6:4-9.

4. The preparation method of a current collector substrate with high-temperature resistant shape memory function according to claim 1, characterized in that: The functional additive includes one or more of antioxidant or heat stabilizer; the shape memory polymer includes styrene-butadiene copolymer.

5. The preparation method of a current collector substrate with high-temperature resistant shape memory function according to claim 4, characterized in that: The antioxidant includes antioxidant 1010; the heat stabilizer includes calcium stearate.

6. The preparation method of a current collector substrate with high-temperature resistant shape memory function according to claim 1, characterized in that: In step S2, the specific process for preparing the base film is: Add the raw materials into a twin-screw extruder, co-mix and process at 260-350°C with a screw rotation speed of 100-300 r / min to obtain a melt; preheat a flat die to 260-350°C; extrude the melt through the flat die with a die inlet pressure of 15-30 MPa, use a traction device to conduct traction at a traction speed of 3-8 m / min, cool and form, wind with a winding tension of 105-155 N, conduct quality control and adjustment to obtain a base film.

7. The preparation method of a current collector substrate with high temperature resistant shape memory function according to claim 1, characterized in that: The thickness of the current collector substrate is 5-7 μm.

8. A current collector substrate prepared by the preparation method of a current collector substrate with high-temperature resistant shape memory function according to any one of claims 1-7.

9. The current collector substrate with high-temperature resistant shape memory function according to claim 8, characterized in that: The current collector substrate is used to prepare a composite current collector; the preparation process of the composite current collector includes the following steps: Activate the surface of the current collector substrate and wind and evaporate to deposit a film to obtain a composite current collector.

10. The current collector substrate with high-temperature resistant shape memory function according to claim 9, characterized in that: The preparation process of the composite current collector includes the following steps: Activate the surface of the current collector substrate by plasma treatment, load it on an unwinding roller, preheat the evaporation area under a vacuum degree <5×10-3 Pa, heat up at 80% power, after reaching the evaporation temperature, guide the substrate through the evaporation area at a speed of 14-16 m / min with an unwinding tension of 195-205 N through a guide roller, at the same time, feed aluminum wire into the evaporation area at a wire feeding speed of 550-570 mm / min, and use a winding roller to collect the composite aluminum current collector with a winding tension of 215-225 N after the film deposition is completed, and obtain a composite current collector after breaking the vacuum.

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