Functional current collector for improving rate capability and preparation method thereof

Abstract

The invention discloses a functional current collector capable of improving rate capability and a preparation method thereof, and relates to the technical field of functional current collectors. Nano cellulose is modified, and the modified nano cellulose is added in the process of preparing the high-rate-performance functional current collector, so that the mechanical property of the high-rate-performance functional current collector is enhanced, and the electrical conductivity is improved; aluminum oxide, metal aluminum and aluminum oxide are sequentially deposited in cooperation with vacuum evaporation to serve as insulating materials, an electronic insulating barrier can be provided, short circuit is prevented, chemical stability is kept in the high-temperature and high-pressure environment, and the hardness and abrasion resistance of the film are enhanced; the surface of a high polymer material is generally non-polar and inert and has great difference with the chemical property of metal aluminum, and an aluminum oxide bottoming mode is used for performing interface optimization on a subsequent evaporation aluminum layer, so that the layering risk is reduced; the metal aluminum is an excellent conductor, the resistance of the current collector is remarkably reduced, the requirement of high-rate charging and discharging is met, the aluminum density is low, the weight of the battery can be reduced, and the energy density is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of functional current collectors, and in particular to a functional current collector with improved rate performance and a preparation method thereof. Background Art

[0002] A functional current collector is a composite material that combines traditional metal current collectors (such as copper foil and aluminum foil) with specialized features such as enhanced safety and conductivity. Existing current collectors typically utilize a sandwich structure consisting of a metal conductive layer, a polymer matrix, and a metal conductive layer. The polymer layer possesses insulating and flame-retardant properties. When a battery is punctured or impacted, the polymer matrix quickly melts, creating a "point break," blocking the current flow and preventing the spread of thermal runaway, thus avoiding the short-circuit issues often associated with traditional current collectors due to metal burrs. Furthermore, their weight is 50% to 80% lower than pure metal current collectors, and their thickness is 25% to 40% lower than comparable pure metal current collectors. This frees up more space within the battery for active materials. With this reduced weight and increased active material content, energy density increases by 5% to 10%.

[0003] Functional current collectors are usually composed of multiple layers of materials, and the interface contact between different layers may not be tight enough. During the charge and discharge process, especially at high rates, lithium ions are frequently inserted and removed, and the volume changes greatly. If the interface bonding is not strong, it may cause delamination or poor contact, increase the interface resistance, and thus affect the transmission efficiency of ions and electrons. At the same time, the middle polymer layer itself is not conductive and has poor thermal conductivity (PET film has a thermal conductivity coefficient of 0.15~0.24 W / m·K), which makes its high-rate charge and discharge performance far worse than that of traditional current collectors. Therefore, the present invention provides a method for preparing a functional current collector with improved rate performance to solve the above technical problems. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a functional current collector with improved rate performance, 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: A functional current collector with high rate performance comprises the following structures from bottom to top: a polymer layer, an aluminum oxide layer, and a metal aluminum layer.

[0006] Furthermore, the polymer layer is any one of PET (polyethylene terephthalate) and PP (polypropylene).

[0007] Furthermore, the polymer layer includes PET raw material and modified nanocellulose.

[0008] A method for preparing a functional current collector with improved rate performance comprises the following steps: S1: Take PET raw material, heat it to the melting stage, then add modified nanocellulose and stir to obtain a composite slurry; S2: injecting the composite slurry into a preset mold, shaping, cutting, thickness measuring, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; S3: vacuum evaporating the prefabricated functional current collector to deposit aluminum oxide to form an aluminum oxide layer, thereby obtaining an aluminum oxide functional current collector; S4: Vacuum-evaporating the aluminum oxide functional current collector to deposit metal aluminum to form a metal aluminum layer, thereby obtaining a functional current collector with high rate performance.

[0009] In the above technical solution, the modified nanocellulose has a high specific surface area and strength. Adding modified nanocellulose can enhance mechanical properties, improve electrical conductivity and conductivity; it helps to form a more stable bonding interface with the subsequently evaporated alumina layer; after adding the modified nanocellulose, stir evenly to avoid uneven performance caused by agglomeration; corona treatment is performed before vacuum evaporation, and the roughness and polarity of the PET film surface are increased by high-voltage discharge, which significantly improves the adhesion of the alumina layer during subsequent vacuum evaporation, eliminates surface stress and avoids the generation of surface microcracks, and improves the overall quality of the film; vacuum evaporates alumina, and alumina acts as a dense ceramic layer to isolate the PET matrix from moisture, oxygen and electrolyte corrosion, thereby extending the life of the current collector; alumina is an insulating material that can provide an electronic insulation barrier, prevent short circuits, and maintain chemical stability under high temperature and high pressure environments; adding alumina can Enhance the hardness and wear resistance of the film. The surface of polymer materials is usually non-polar and inert, and its chemical properties are very different from those of metallic aluminum. It is difficult for aluminum atoms to form a strong physical anchor with the polymer during direct vapor deposition. It is easy to cause delamination or peeling due to thermal stress and mechanical friction during long-term use. Aluminum oxide is used as a primer. Aluminum oxide serves as an intermediate layer. The hydroxyl groups (-OH) on its surface can form hydrogen bonds with the polar groups (-COOH) in the polymer material. The lattice constant of the aluminum oxide layer is similar to that of aluminum. The surface can intervene between the polymer material and metallic aluminum, and as a transition layer, it optimizes the wettability between the two, optimizes the interface for the subsequent vapor-deposited aluminum layer, and reduces the risk of delamination. Metallic aluminum is an excellent conductor, which significantly reduces the current collector resistance and meets the needs of high-rate charging and discharging. The low density of aluminum can reduce the weight of the battery and increase the energy density. Aluminum forms a passivation film in the electrolyte to further protect the current collector.

[0010] PET provides flexibility and matrix support, the alumina layer provides protection and insulation, and the aluminum layer realizes conductivity. The "flexible-protective-conductive" composite system balances mechanical strength, conductivity, corrosion resistance and lightweight performance to meet the application requirements of high-rate lithium-ion batteries or supercapacitors.

[0011] Furthermore, in step S1, the mass ratio of the modified nanocellulose to the PET raw material is (1~2):1.

[0012] Furthermore, in step S1, the process conditions of heating and stirring are: heating to 250-265° C. and stirring for 1-2 hours.

[0013] Furthermore, the shaping process includes the following steps: First, longitudinal stretching is performed, with the preheating roller temperature set at 60~80℃, the slow pulling roller temperature at 80~85℃, the fast pulling roller temperature at 25~30℃, the cooling roller temperature at 30~50℃, and the longitudinal stretch ratio set to 3~3.5 times. Then, transverse stretching is performed, with the preheating roller temperature set at 80~100℃, the slow pulling roller temperature at 100~105℃, the longitudinal stretch ratio set to 3~3.5 times, the heat setting temperature at 190~210℃, the time for 3~6s, and air cooling to 45~50℃ after setting.

[0014] Furthermore, in step S2, the length of the polymer layer after cutting is 2.5-3 m; the thickness of the polymer layer is 5-10 μm; The corona process parameters are: voltage 380~400V, power 2~10kW, and corona rate 4~60m / min.

[0015] Furthermore, the vacuum evaporation process includes the following steps: the film-unwinding end is at 120~130N, the winding end is at 100~110N, and the winding trolley enters the evaporation chamber and is vacuumed to (5.0~5.5)×10 -3 Pa, open the winding trolley at a speed of 280~300m / min, heat the evaporation boat to 1200~1400℃, feed the aluminum wire at a speed of 300~350mm / min, and set the vacuum degree to (5.0~5.5)×10 -2 Pa, 50~100sccm oxygen atmosphere, aluminum oxide was deposited, and after breaking the vacuum, the vacuum degree was (5.0~5.5)×10 -2 Pa, 100~200sccm argon atmosphere, deposit metallic aluminum.

[0016] Furthermore, the preparation process of the modified nanocellulose comprises the following steps: The nanocellulose is mixed with an ethanol solution, dispersed, a silane coupling agent is added, heated for reaction, and finally washed with an ethanol solution and dried to obtain modified nanocellulose.

[0017] In the above technical solution, the surface of nanocellulose is modified by benzene ring modification, and conjugated groups are introduced by reacting a silane coupling agent containing a conjugated structure with the cellulose hydroxyl group. The modified nanocellulose is then added during the melting stage of the base film. The nanocellulose penetrates the base film in the transverse (TD) direction and has good electrical and thermal conductivity.

[0018] Furthermore, the ethanol solution is a mixed solution of ethanol and water with a volume ratio of (18~19):1.

[0019] Furthermore, the mass ratio of nanocellulose, ethanol solution, and silane coupling agent is (1-5):(20-100):1.

[0020] Furthermore, the dispersion process conditions are: heating to 70-85°C, ultrasonic dispersion at a power of 100-150W for 30-60 minutes.

[0021] Furthermore, the silane coupling agent is 3-aminophenyltrimethoxysilane.

[0022] Furthermore, the process conditions of the heating reaction are: reaction at a temperature of 60-70° C. for 5-6 hours.

[0023] Furthermore, the drying process conditions are: drying at a temperature of 60-70° C. for 1-2 hours.

[0024] Furthermore, the diameter of nanocellulose is 2~100nm.

[0025] Furthermore, the PET raw material is compounded with modified nano-kaolin and modified carbon nanospheres to obtain a composite PET material.

[0026] Further, the composite PET material is prepared by the following steps: Step 1: Take nano-kaolin, wash it with deionized water at a temperature of 45-60°C for 10-20 minutes, and dry it at 100-105°C for 1-2 hours to obtain pretreated nano-kaolin; Step 2: Mix the pretreated nano-kaolin, aluminum titanate coupling agent and ethanol solution, grind and disperse them, heat to react, centrifuge and dry them, and crush them to obtain modified nano-kaolin.

[0027] Step 3: mixing the carbon nanospheres with the mixed acid, dispersing them, heating them for reaction, cooling them to room temperature, centrifuging and washing them, and vacuum drying them to obtain carboxylated carbon nanospheres; Step 4: adding dichloromethane, 4-benzylideneaminophenol and 4-dimethylaminopyridine to the carboxylated carbon nanospheres, heating for reaction, centrifuging, washing and drying to obtain modified carbon nanospheres; Step 5: Take the PET raw material, mix it with the modified carbon nanospheres, add the modified nano-kaolin, heat it to melt and blend it, extrude it, and pelletize it to obtain a PET composite material.

[0028] In the above technical solution, the aluminum titanate coupling agent acts as a bridge molecule, one end of which is combined with the hydroxyl group on the surface of nano-kaolin, and the other end interacts with the polymer chain of PET. By coupling the modified nano-kaolin, the agglomeration of nano-kaolin is reduced, the dispersion uniformity is improved, and the interfacial bonding force between the inorganic filler and the organic matrix is ​​significantly improved. The addition of modified nano-kaolin can improve the tensile strength, bending modulus and other mechanical properties of the PET matrix. At the same time, the lamellar structure of nano-kaolin forms a physical barrier in the PET matrix, delaying the diffusion of heat and oxygen into the interior of the material, inhibiting thermal decomposition reactions, and enhancing the thermal stability of the PET material. The addition of modified carbon nanospheres can promote the formation of more carbides in the PET material during combustion, and can catalyze dehydration and polymerization reactions on the surface of the PET material to form a dense carbon layer. This carbon layer has good heat insulation and oxygen isolation properties, which can prevent the further spread of flames and slow down the overflow of volatile products formed by polymer decomposition, thereby enhancing the flame retardancy of the material; the modified carbon nanospheres are compounded with modified nano-kaolin, and through the interaction of physical barrier and chemical carbonization, a synergistic flame retardant effect is produced, which significantly improves the thermal stability of PET composite materials.

[0029] Furthermore, the mixed acid is a mixture of concentrated sulfuric acid and nitric acid, and the volume ratio of concentrated sulfuric acid to nitric acid is 3:1.

[0030] Furthermore, the concentration of concentrated sulfuric acid is 80-90w%, and the concentration of nitric acid is 60-70w%.

[0031] Furthermore, the mass ratio of carbon nanospheres to mixed acid is (5~7):1.

[0032] Furthermore, in step 4, the mass ratio of carboxylated carbon nanospheres, dichloromethane, 4-benzylideneaminophenol, and 4-dimethylaminopyridine is (3-5): (50-100): 1:0.1.

[0033] Furthermore, the mass ratio of the pretreated nano-kaolin, aluminum titanate coupling agent, and ethanol solution is (5~10):(0.1~0.3):(8~20).

[0034] Furthermore, the grinding process conditions are as follows: grinding with a ball mill at a rotation speed of 300-450 rpm, grinding 3-6 times, and dispersing for 15-30 minutes each time; The process conditions of the heating reaction are: reaction at a temperature of 60-70°C for 1-3 hours; The centrifugal process conditions are: 2400-3000 rpm, centrifugation for 15-25 min; The drying process conditions are: drying at a temperature of 100-120°C for 2-3 hours; The process conditions for crushing are: crushing to 5~100nm.

[0035] Furthermore, the mass ratio of the modified carbon nanospheres, the PET raw material, and the modified nano-kaolin is (0.5~3):90:1.

[0036] Furthermore, the aluminum titanate coupling agent is OL-AT1618.

[0037] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention improves the thermal and electrical conductivity of the base film by introducing modified nanocellulose into the original base film, thereby improving the high-rate charge and discharge performance of the functional current collector.

[0038] 2. The present invention introduces modified nanocellulose into the original base film. The hydroxyl content on the cellulose chain is as high as 30%, which is an active group. It can increase the chemical bond with alumina and improve the bonding strength of the coating.

[0039] 3. The present invention introduces modified nanocellulose into the original base film. The nanocellulose itself has a high tensile strength of 2-7.7GPa, which enhances the mechanical properties of the composite aluminum foil and makes it less likely to break during the winding process.

[0040] 4. The present invention improves the tensile strength, flexural modulus and impact toughness of the material by adding a small amount of modified nano-kaolin to the PET material, reduces the crystallization activation energy of PET, accelerates its crystallization process, reduces the cooling time during the shaping process, improves production efficiency, and improves the thermal stability of the material.

[0041] 5. The present invention improves the flame retardant effect of PET material by adding modified carbon nanosphere material and synergizing with modified nano kaolin. DETAILED DESCRIPTION

[0042] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0043] In the following specific embodiments, PET raw material, brand BS-W, average particle size 5mm; Nanocellulose, model PH-102; Alumina, crystalline α phase, average particle size 40nm; Carbon nanospheres, model 100T, average particle size 15nm; The aluminum titanate coupling agent is OL-AT1618; The ethanol solution is a mixed solution of ethanol and water with a volume ratio of 19:1; Example 1: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 250℃ and melt it, then add modified nanocellulose and stir it for 1 hour to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 1:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3 times, the heat setting temperature is 190°C, the time is 3s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, open the winding trolley, the speed is 280m / min, the evaporation boat temperature is heated to 1200℃, feed the aluminum wire, the wire feeding speed is 310mm / min, and the vacuum degree is 5.0×10 -2 Pa, 50 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 320mm / min. The vacuum degree is 5.0×10 -2 Pa, 100 sccm argon atmosphere, metal aluminum is deposited to form a metal aluminum layer to obtain a functional current collector with high rate performance.

[0044] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0045] Example 2: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 255℃, then add modified nanocellulose and stir for 1 hour to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 1.2:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 61°C, the slow pull roller temperature is 82°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 50°C, and the longitudinal stretch ratio is set to 3 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 85°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3 times, the heat setting temperature is 190°C, the time is 4s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280 m / min, the evaporation boat is heated to 1200 °C, and the aluminum wire is fed at a speed of 315 mm / min. The vacuum degree is 5.0 × 10 -2 Pa, 55 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 320mm / min. The vacuum degree is 5.0×10 -2 Pa, 110sccm argon atmosphere, metal aluminum was deposited to form a metal aluminum layer, and a functional current collector with high rate performance was obtained.

[0046] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0047] Example 3: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 256℃, then add modified nanocellulose and stir for 1.5 hours to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 1.4:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3 times, the heat setting temperature is 190°C, the time is 3s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 320mm / min. The vacuum degree is 5.0×10 -2 Pa, 60 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 325mm / min. The vacuum degree is 5.0×10 -2 Pa, 115sccm argon atmosphere, metal aluminum was deposited to form a metal aluminum layer, and a functional current collector with high rate performance was obtained.

[0048] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0049] Example 4: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 258℃, then add modified nanocellulose and stir for 1.5 hours to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 1.6:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3 times, the heat setting temperature is 200°C, the time is 5s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 325mm / min. The vacuum degree is 5.0×10 -2 Pa, 65 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, open the winding trolley, the speed is 280m / min, the evaporation boat temperature is heated to 1200℃, feed the aluminum wire, the wire feeding speed is 330mm / min, and the vacuum degree is 5.0×10 -2 Pa, 120sccm argon atmosphere, metal aluminum was deposited to form a metal aluminum layer, and a functional current collector with high rate performance was obtained.

[0050] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0051] Example 5: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 259℃, then add modified nanocellulose and stir for 2 hours to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 1.8:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3.5 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3.5 times, the heat setting temperature is 200°C, the time is 6s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 325mm / min. The vacuum degree is 5.0×10 -2 Pa, 55 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 335mm / min. The vacuum degree is 5.0×10 -2 Pa, 115sccm argon atmosphere, metal aluminum was deposited to form a metal aluminum layer, and a functional current collector with high rate performance was obtained.

[0052] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0053] Example 6: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 260℃, then add modified nanocellulose and stir for 2 hours to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 2:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3.5 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3.5 times, the heat setting temperature is 200°C, the time is 6s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, open the winding trolley, the speed is 280m / min, the evaporation boat temperature is heated to 1200℃, feed the aluminum wire, the wire feeding speed is 340mm / min, and the vacuum degree is 5.0×10 -2 Pa, 70 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 345mm / min. The vacuum degree is 5.0×10 -2 Pa, 130sccm argon atmosphere, metal aluminum was deposited to form a metal aluminum layer, and a functional current collector with high rate performance was obtained.

[0054] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0055] Example 7: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 260℃, then add modified nanocellulose and stir for 2 hours to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 2:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3.5 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3.5 times, the heat setting temperature is 200°C, the time is 6s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, open the winding trolley at a speed of 280m / min, heat the evaporation boat to 1200℃, feed the aluminum wire at a speed of 350mm / min, and set the vacuum degree to 5.0×10 -2 Pa, 80 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, open the winding trolley, the speed is 280m / min, the evaporation boat temperature is heated to 1200℃, feed the aluminum wire, the wire feeding speed is 340mm / min, and the vacuum degree is 5.0×10 -2 Pa, 140sccm argon atmosphere, metal aluminum was deposited to form a metal aluminum layer, and a functional current collector with high rate performance was obtained.

[0056] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0057] The preparation of composite PET material includes the following steps: Step 1: Take nano-kaolin, wash it with deionized water at 45°C for 10 minutes, and dry it at 100°C for 1 hour to obtain pretreated nano-kaolin; Step 2: Mix the pretreated nano-kaolin, aluminum titanate coupling agent, and ethanol solution, grind and disperse, heat to react, centrifuge and dry, and crush to obtain modified nano-kaolin; the mass ratio of the pretreated nano-kaolin, aluminum titanate coupling agent, and ethanol solution is 5:0.1:20; the grinding process conditions are: grinding using a ball mill at a speed of 350 rpm, grinding 3 times, and each dispersion for 15 minutes; the heating reaction process conditions are: reacting at a temperature of 60°C for 1 hour; the centrifugal process conditions are: centrifuging at 2400 rpm for 15 minutes; the drying process conditions are: drying at a temperature of 100°C for 2 hours; and the crushing process conditions are: crushing to 5 nm; Step 3: mixing the carbon nanospheres with a mixed acid, dispersing the mixture, heating the mixture for reaction, cooling the mixture to room temperature, centrifuging and washing the mixture, and vacuum drying the mixture to obtain carboxylated carbon nanospheres; the mixed acid is a mixture of concentrated sulfuric acid and nitric acid, wherein the volume ratio of the concentrated sulfuric acid to the nitric acid is 3:1; and the mass ratio of the carbon nanospheres to the mixed acid is 5:1; Step 4: adding carboxylated carbon nanospheres to dichloromethane, adding 4-benzylideneaminophenol and 4-dimethylaminopyridine, heating for reaction, centrifuging, washing and drying to obtain modified carbon nanospheres; the mass ratio of carboxylated carbon nanospheres, dichloromethane, 4-benzylideneaminophenol and 4-dimethylaminopyridine is 3:50:1:0.1; Step 5: Take PET raw material, mix it with modified carbon nanospheres, add modified nano-kaolin, heat to melt blend, extrude and pelletize to obtain PET composite material; the mass ratio of modified carbon nanospheres, PET raw material and modified nano-kaolin is 0.5:90:1.

[0058] Comparative Example 1: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: PET raw material was dried at 60°C for 1 hour and heated to 270°C to melt to obtain slurry; S2: The slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3.5 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3.5 times, the heat setting temperature is 200°C, the time is 6s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 320mm / min. The vacuum degree is 5.0×10 -2 Pa, 90 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280 m / min, the evaporation boat is heated to 1200 °C, and the aluminum wire is fed at a speed of 322 mm / min. The vacuum degree is 5.0 × 10 -2 Pa, 150sccm argon atmosphere, metal aluminum was deposited to form a metal aluminum layer, and a functional current collector with high rate performance was obtained.

[0059] Comparative Example 2: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 260℃, then add modified nanocellulose and stir for 2 hours to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 1.8:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3.5 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3.5 times, the heat setting temperature is 200°C, the time is 6s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280 m / min, the evaporation boat is heated to 1200 °C, and the aluminum wire is fed at a speed of 322 mm / min. The vacuum degree is 5.0 × 10 -2 Pa, 95 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280 m / min, the evaporation boat is heated to 1200 °C, and the aluminum wire is fed at a speed of 332 mm / min. The vacuum degree is 5.0 × 10 -2 Pa, 155sccm argon atmosphere, metal aluminum was deposited to form a metal aluminum layer to obtain a functional current collector with high rate performance.

[0060] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0061] The preparation of composite PET material includes the following steps: Step 1: Take nano-kaolin, wash it with deionized water at 45°C for 10 minutes, and dry it at 100°C for 1 hour to obtain pretreated nano-kaolin; Step 2: Mix the pretreated nano-kaolin, aluminum titanate coupling agent, and ethanol solution, grind and disperse, heat to react, centrifuge and dry, and crush to obtain modified nano-kaolin; the mass ratio of the pretreated nano-kaolin, aluminum titanate coupling agent, and ethanol solution is 5:0.1:20; the grinding process conditions are: grinding using a ball mill at a speed of 350 rpm, grinding 3 times, and each dispersion for 15 minutes; the heating reaction process conditions are: reacting at a temperature of 60°C for 1 hour; the centrifugal process conditions are: centrifuging at 2400 rpm for 15 minutes; the drying process conditions are: drying at a temperature of 100°C for 2 hours; and the crushing process conditions are: crushing to 5 nm; Step 3: Take PET raw material, add modified nano-kaolin, heat until melt blending, extrude, and pelletize to obtain a PET composite material; the mass ratio of PET raw material to modified nano-kaolin is 90:1.

[0062] Comparative Example 3: A method for preparing a functional current collector with improved rate performance, comprising the following steps: S1: Take PET raw material, heat it to 260℃, then add modified nanocellulose and stir for 2 hours to obtain a composite slurry; the mass ratio of modified nanocellulose to PET raw material is 1.8:1; S2: The composite slurry is injected into a preset mold, and first longitudinal stretching is performed, the longitudinal stretching preheating roller temperature is set to 60°C, the slow pull roller temperature is 80°C, the fast pull roller temperature is 30°C, the cooling roller temperature is 30°C, and the longitudinal stretch ratio is set to 3.5 times, and then transverse stretching is performed, the transverse stretching preheating roller temperature is set to 80°C, the slow pull roller temperature is 100°C, the longitudinal stretch ratio is set to 3.5 times, the heat setting temperature is 200°C, the time is 6s, and after setting, it is air-cooled to 50°C, slitting, thickness measurement, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; the total thickness of the base film is 6μm, and the slitting process parameters are: length 2.5m; thickness measurement is 6μm; corona treatment process parameters are: voltage 380V, power 2kW, corona rate 4m / min; S3: The prefabricated functional current collector is vacuum-deposited. The film-releasing end is at 120N, and the winding end is at 100N. The winding trolley enters the evaporation chamber and is vacuumed to 5.0×10 -3 Pa, the winding trolley is turned on at a speed of 280 m / min, the evaporation boat is heated to 1200 °C, and the aluminum wire is fed at a speed of 331 mm / min. The vacuum degree is 5.0 × 10 -2 Pa, 100 sccm oxygen atmosphere, depositing aluminum oxide to form an aluminum oxide layer to obtain an aluminum oxide functional current collector; S4: Vacuum evaporation of the aluminum oxide functional current collector was performed, with the film-unwinding end at 120N and the winding end at 110N. The winding trolley entered the evaporation chamber and vacuumed to 5.0×10 -3Pa, the winding trolley is turned on at a speed of 280m / min, the evaporation boat is heated to 1200℃, and the aluminum wire is fed at a speed of 338mm / min. The vacuum degree is 5.0×10 -2 Pa, 200sccm argon atmosphere, metal aluminum is deposited to form a metal aluminum layer to obtain a functional current collector with high rate performance.

[0063] The preparation process of modified nanocellulose includes the following steps: Nanocellulose was mixed with an ethanol solution, heated to 70°C, and ultrasonically dispersed at a power of 100 W for 30 minutes. 3-Aminophenyltrimethoxysilane was added and reacted at a temperature of 60°C for 6 hours. Finally, the mixture was washed with an ethanol solution and dried at 60°C for 1 hour to obtain modified nanocellulose. The mass ratio of nanocellulose, ethanol solution, and silane coupling agent was 5:94:1.

[0064] The preparation of composite PET material includes the following steps: Step 1: mixing carbon nanospheres with mixed acid, dispersing, heating for reaction, cooling to room temperature, centrifuging for washing, and vacuum drying to obtain carboxylated carbon nanospheres; the mixed acid is a mixture of concentrated sulfuric acid and nitric acid, the volume ratio of concentrated sulfuric acid to nitric acid is 3:1; the mass ratio of carbon nanospheres to mixed acid is 5:1; Step 2: adding carboxylated carbon nanospheres to dichloromethane, adding 4-benzylideneaminophenol and 4-dimethylaminopyridine, heating for reaction, centrifuging, washing and drying to obtain modified carbon nanospheres; the mass ratio of carboxylated carbon nanospheres, dichloromethane, 4-benzylideneaminophenol and 4-dimethylaminopyridine is 3:60:1:0.1; Step 3: Take the PET raw material, mix it with the modified carbon nanospheres, heat it to melt and blend it, extrude it, and cut it into pellets to obtain a PET composite material; the mass ratio of the modified carbon nanospheres to the PET raw material is 0.5:90.

[0065] The functional current collectors obtained in Examples 1-7 and Comparative Examples 1-3 were used to prepare samples, and their performance was tested and the test results were recorded.

[0066] Tensile strength and elongation: The room temperature tensile strength and elongation at break of the composite aluminum foil are measured using an electronic universal material testing machine. The test conditions are: gauge length 10 mm, tensile speed 100 mm / min, width 15 mm. Other requirements are determined in accordance with the method specified in GB / T1040.3-2006.

[0067] Conductivity test: Use the Probe Technology RTS-7 four-probe tester to cut the sample into 10×10cm size and place it under the probe. Each sample is tested three times and the average value is taken. According to the formula, resistivity ρ=V / I×2πS, conductivity σ=1 / ρ.

[0068] Thermal conductivity test: Based on ASTM E1461 and ISO 22007-4 as reference standards, the base film is placed on the test bench using the laser flash method. The front surface of the sample is irradiated with a laser pulse, and the temperature rise curve of the back surface is measured with an infrared detector. The thermal conductivity k=α·ρ·c is calculated based on the specific heat capacity and density, where α is the thermal diffusivity.

[0069] Performance comparison table

[0070] According to the data in the above table, we can clearly draw the following conclusions: The functional current collectors with high rate performance obtained in Examples 1-7 were compared with the functional current collectors obtained in Comparative Examples 1-2. The test results show that: By introducing conjugated modified nanocellulose into the original PET base film, its high tensile strength improves the tensile strength of the high-rate functional current collector. However, due to its inherently low elongation (2-10%), the overall elongation of the functional current collector decreases. As the addition amount increases, although the tensile strength is significantly improved, the low elongation affects its use in the battery terminal. Therefore, compared with Examples 1-7, Example 2 still maintains excellent tensile strength and conductivity while meeting the MD (>20%) and TD (>10%) elongation requirements. The introduction of conjugated groups enhances the electron transfer effect and increases the conductivity. At the same time, the nanocellulose increases the thermal conductivity of the base film, greatly improving the high-rate performance of the functional current collector.

[0071] Compared with Examples 1-7, the functional current collector obtained in Comparative Example 1 does not add modified nanocellulose, and has lower tensile strength, higher elongation, low electrical conductivity, and low thermal conductivity. It can be seen that the functional current collector prepared without adding modified nanocellulose has low tensile strength, is prone to large plastic deformation under stress, has poor electrical conductivity, poor thermal conductivity, and poor stability, and cannot meet the requirements of high-rate performance.

[0072] Compared with Example 7, the functional current collector obtained in Comparative Example 2 does not contain modified nano-kaolin, and has lower tensile strength, higher elongation, lower electrical conductivity, and lower thermal conductivity. It can be seen that the addition of modified nano-kaolin is beneficial to enhancing mechanical properties and improving thermal stability, improving the barrier properties of the functional current collector, and reducing the contact resistance of the functional current collector interface, thereby improving the charge and discharge rate and power density.

[0073] Compared with Example 7, the functional current collector obtained in Comparative Example 3 does not add modified carbon nanospheres, and has lower tensile strength, higher elongation, lower electrical conductivity, and lower thermal conductivity. It can be seen that the addition of modified carbon nanospheres reduces the contact resistance of the functional current collector interface, thereby improving the charge and discharge rate and power density.

[0074] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing a functional current collector with improved rate performance, characterized in that: The following steps are involved: S1: Take PET raw material, heat it to the melting stage, then add modified nanocellulose and stir to obtain a composite slurry; S2: injecting the composite slurry into a preset mold, shaping, cutting, thickness measuring, corona treatment, forming a polymer layer, and obtaining a prefabricated functional current collector; S3: vacuum evaporating the prefabricated functional current collector to deposit aluminum oxide to form an aluminum oxide layer, thereby obtaining an aluminum oxide functional current collector; S4: Vacuum-evaporating the aluminum oxide functional current collector to deposit metal aluminum to form a metal aluminum layer, thereby obtaining a functional current collector with high rate performance.

2. The method for preparing a functional current collector with improved rate performance according to claim 1, wherein: The preparation process of modified nanocellulose comprises the following steps: The nanocellulose is mixed with an ethanol solution, dispersed, a silane coupling agent is added, heated for reaction, and finally washed with an ethanol solution and vacuum dried to obtain modified nanocellulose.

3. The method for preparing a functional current collector with improved rate performance according to claim 1, wherein: In step S2, the shaping process includes the following steps: First, longitudinal stretching is performed, with the preheating roller temperature set at 60~80℃, the slow pull roller temperature at 80~85℃, the fast pull roller temperature at 25~30℃, the cooling roller temperature at 30~50℃, and the longitudinal stretch ratio set to 3~3.5 times. Then, transverse stretching is performed, with the preheating roller temperature set at 80~100℃, the slow pull roller temperature at 100~105℃, the longitudinal stretch ratio set to 3~3.5 times, the heat setting temperature at 190~210℃, the time for 3~6s, and air cooling to 45~50℃ after setting.

4. The method for preparing a functional current collector with improved rate performance according to claim 1, wherein: In step S3, the vacuum evaporation process includes the following steps: The film unwinding end is at 120~130N, the winding end is at 100~110N, and the winding trolley enters the evaporation chamber and vacuum is drawn to (5.0~5.5)×10 -3 Pa, open the winding trolley at a speed of 280~300m / min, heat the evaporation boat to 1200~1400℃, feed the aluminum wire at a speed of 300~350mm / min, and set the vacuum degree to (5.0~5.5)×10 -2 Pa, 50~100sccm oxygen atmosphere, aluminum oxide was deposited, and after breaking the vacuum, the vacuum degree was (5.0~5.5)×10 -2 Pa, 100~200sccm argon atmosphere, deposit metallic aluminum.

5. The method for preparing a functional current collector with improved rate performance according to claim 2, wherein: The mass ratio of nanocellulose, ethanol solution and silane coupling agent is (1~5):(20~100):

1.

6. The method for preparing a functional current collector with improved rate performance according to claim 2, wherein: The silane coupling agent is 3-aminophenyltrimethoxysilane.

7. The method for preparing a functional current collector with improved rate performance according to claim 1, wherein: PET raw material is composite PET material, which is made by the following process: Step 1: Take nano-kaolin, wash it with deionized water at a temperature of 45-60°C for 10-20 minutes, and dry it at 100-105°C for 1-2 hours to obtain pretreated nano-kaolin; Step 2: mixing the pretreated nano-kaolin, aluminum titanate coupling agent, and ethanol solution, grinding and dispersing them, heating for reaction, centrifugation drying, and crushing to obtain modified nano-kaolin; Step 3: mixing the carbon nanospheres with the mixed acid, dispersing them, heating them for reaction, cooling them to room temperature, centrifuging and washing them, and vacuum drying them to obtain carboxylated carbon nanospheres; Step 4: adding dichloromethane, 4-benzylideneaminophenol and 4-dimethylaminopyridine to the carboxylated carbon nanospheres, heating for reaction, centrifuging, washing and drying to obtain modified carbon nanospheres; Step 5: Take the PET raw material, mix it with the modified carbon nanospheres, add the modified nano-kaolin, heat it to melt and blend it, extrude it, and pelletize it to obtain a PET composite material.

8. The method for preparing a functional current collector with improved rate performance according to claim 7, wherein: In step 2, the mass ratio of pretreated nano-kaolin, aluminum titanate coupling agent, and ethanol solution is (5-10): (0.1-0.3): (8-20).

9. The method for preparing a functional current collector with improved rate performance according to claim 7, wherein: In step 4, the mass ratio of carboxylated carbon nanospheres, dichloromethane, 4-benzylideneaminophenol, and 4-dimethylaminopyridine is (3-5): (50-100): 1:0.

1.

10. A functional current collector for improving rate performance, characterized by: Prepared according to the preparation method according to any one of claims 1 to 9.

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