High-magnification 3D composite current collector and energy storage equipment

Abstract

The utility model provides a high magnification type 3D composite current collector and energy storage equipment, which comprises an extension foil layer, a first porous foamed aluminum layer and a second porous foamed aluminum layer, the first porous foamed aluminum layer and the second porous foamed aluminum layer are sequentially arranged outwards from at least one side of the extension foil layer, and the porosity ratio N of the first porous foamed aluminum layer to the second porous foamed aluminum layer is less than 1. The high-magnification type 3D composite current collector provided by the utility model overcomes the limitations of the traditional foamed aluminum current collector in ductility, mechanical strength and coating process, and provides powerful material support for the progress of the battery technology while ensuring good toughness and improving the charge-discharge magnification of the battery.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, specifically relating to a high-rate 3D composite current collector and energy storage device. Background Technology

[0002] With the continuous development of modern technology, batteries, as an important energy storage device, are widely used in many fields such as electric vehicles and portable electronic devices. However, in traditional practices, copper foil, aluminum foil, or stainless steel are commonly used as current collectors. The low specific surface area of ​​these foils undoubtedly limits the loading of active materials on the electrodes and the charge-discharge performance of the battery. To improve the loading rate of active materials and optimize charge-discharge performance, the current common practice is to increase the coating thickness of the active materials. While this method can optimize the battery energy density to some extent, the thicker active material layer will significantly prolong the electron migration path, increase the internal resistance of the electrode, and increase the heat generation of the electrode. To solve these problems, aluminum foam has been introduced as a current collector. However, using aluminum foam as a current collector still has some problems. Although the large specific surface area of ​​aluminum foam can improve the loading of active materials to a certain extent while maintaining the coating thickness, conventional aluminum foam current collectors have extremely low tensile strength and cannot withstand the stretching caused by electrode compaction. During the compaction process, the aluminum foam inside the electrode often breaks, thereby increasing the safety risk of the battery. In addition, the increase in the loading of active materials will lead to an increase in current density, which in turn causes heat generation. Improving the tensile strength of aluminum foam, optimizing the current density of aluminum foam electrodes, and enhancing the rate performance of batteries using aluminum foam as current collectors have become major research focuses. Utility Model Content

[0003] To address the existing technical problems, this utility model proposes a high-rate 3D composite current collector, which solves the problems of poor tensile strength, low electrode compaction density, and uneven current distribution caused by the thickness of the electrode when using aluminum foam as a current collector. It obtains a high-rate 3D composite current collector with excellent rate performance, high pressure resistance and ductility, high loading of active material, and reasonable optimization of electrode current distribution.

[0004] This utility model provides a high-magnification 3D composite current collector, including an extended foil layer, a first porous aluminum foam layer and a second porous aluminum foam layer sequentially arranged from at least one side of the extended foil layer outwards, wherein the porosity ratio N of the first porous aluminum foam layer and the second porous aluminum foam layer is less than 1.

[0005] As a further option, the porosity ratio N between the first porous aluminum foam layer and the second porous aluminum foam layer is selected from 0.65 ≤ N < 1.

[0006] As a further option, the porosity of the first porous aluminum foam layer is selected from 60% to 97%.

[0007] As a further option, the porosity of the second porous aluminum foam layer is selected from 80% to 99%.

[0008] As a further option, the thickness of the extended foil layer is selected from 5-40 μm.

[0009] As some preferred embodiments, the thickness of the extended foil layer is selected from 10-30 μm.

[0010] As a further embodiment, the thickness ratio between the first porous aluminum foam layer and the second porous aluminum foam layer is selected from 0.05-5.

[0011] As some preferred embodiments, the thickness ratio between the first porous aluminum foam layer and the second porous aluminum foam layer is selected from 0.5-2.

[0012] As a further option, the thickness of the first porous aluminum foam layer is selected from 100-1000 μm.

[0013] As a further option, the thickness of the second porous aluminum foam layer is selected from 200-2000 μm.

[0014] As a further embodiment, the first porous aluminum foam layer and the second porous aluminum foam layer are constructed from cross-linked aluminum fibers, and a conductive carbon layer is provided from the aluminum fibers outward.

[0015] As a further option, the radius of the aluminum fiber is selected from 0.5-150μm.

[0016] As some preferred options, the radius of the aluminum fiber is selected from 20-100 μm.

[0017] As a further option, the thickness of the conductive carbon layer is selected from 0.3 nm to 3 μm.

[0018] As some preferred embodiments, the thickness of the conductive carbon layer is selected from any one of 5nm to 2.5μm, 20nm to 2μm, and 50nm to 1.5μm.

[0019] As some preferred embodiments, the thickness of the conductive carbon layer is selected from 100 nm to 1 μm.

[0020] As a further option, the material of the extended foil layer is not limited in principle, and can be selected from any one of aluminum, copper, stainless steel, and nickel.

[0021] As a further option, the conductive carbon layer material is not limited in principle, and can be selected from any one of graphite, graphene, and conductive carbon black.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] This solution innovatively places the first and second porous aluminum foam layers on the outer layer of the extended foil layer, effectively solving the problems of poor toughness and low electrode compaction density inherent in aluminum foam as a current collector. This structural design not only improves the toughness and pressure resistance of the current collector but also facilitates and speeds up the coating process by blocking the through-pore structure of the aluminum foam, significantly improving coating efficiency. Furthermore, by cleverly designing two porous aluminum foam layers with different porosities, this solution optimizes the electrode current density distribution, reduces electrode resistance, and alleviates heat generation during battery charging and discharging, thus achieving a high-rate 3D composite current collector. In summary, this solution provides a highly efficient solution that combines high toughness and low electrode contact resistance while overcoming the defects of traditional aluminum foam coating. Attached Figure Description

[0024] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0025] Figure 1 This is a schematic diagram of a high-ratio 3D composite current collector structure;

[0026] Figure 2 This is a cross-sectional view of the aluminum fiber.

[0027] Among them, 1-extended foil layer; 2-first porous aluminum foam layer; 3-second porous aluminum foam layer; 4-aluminum fiber; 5-conductive carbon layer. Detailed Implementation

[0028] For ease of understanding, the present invention will be described more comprehensively below, and embodiments of the present invention will be given, but this does not limit the scope of the present invention.

[0029] like Figure 1 As shown, this utility model provides a high-magnification 3D composite current collector, including an extended foil layer 1, a first porous aluminum foam layer 2 and a second porous aluminum foam layer 3 sequentially arranged from at least one side of the extended foil layer 1 outwards, and the porosity ratio N of the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 is less than 1.

[0030] In this solution, to address the issues of poor toughness, low electrode compaction density, and difficulty in coating due to the through-hole structure of aluminum foam as a current collector, the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 are placed on the outer layer of the extended foil layer 1. On one hand, the extended foil layer 1 can bear and disperse the pressure during compaction, preventing the breakage of the aluminum foam inside the outer first porous aluminum foam layer 2 and the second porous aluminum foam layer 3, thereby improving the toughness and pressure-bearing capacity of the high-ratio 3D composite current collector. On the other hand, the extended foil layer 1, located inside the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3, can also block the through-hole structure of the aluminum foam, preventing leakage of the coating slurry, making the coating process of the high-ratio 3D composite current collector convenient and quick, thus solving the defects of aluminum foam as a current collector and effectively improving coating efficiency. Furthermore, in this solution, from at least one side of the extended foil layer 1... A first porous aluminum foam layer 2 and a second porous aluminum foam layer 3 are sequentially arranged on the outside, and the porosity ratio between the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 is less than 1. By setting two porous aluminum foam layers with different porosities and ensuring that the porosity of the first porous aluminum foam layer 2 is less than that of the second porous aluminum foam layer 3, the extended foil layer 1 as the inner layer and the first porous aluminum foam layer 2 have stronger current carrying capacity during battery use, thereby effectively improving the rate performance of the battery when preparing high-rate 3D composite current collectors and alleviating the heat generation phenomenon during use. With the joint cooperation of the extended foil layer 1, the first porous aluminum foam layer 2, and the second porous aluminum foam layer 3, this utility model obtains a high-rate 3D composite current collector with high toughness and high rate, while effectively overcoming the problems of slurry leakage and heat generation when using traditional aluminum foam coating slurry.

[0031] As some preferred examples, the porosity ratio N between the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 is selected from 0.65 ≤ N < 1. In high-ratio 3D composite current collectors, a porosity ratio N less than 1 helps to improve the current carrying capacity of the first porous aluminum foam layer 2. Furthermore, by controlling the porosity ratio N ≥ 0.65, it helps to optimize the pore structure of the first porous aluminum foam layer 2 and further improve the toughness of the high-ratio 3D composite current collector.

[0032] As an example of some optional parameters, the porosity of the first porous aluminum foam layer 2 is selected from 60% to 97%.

[0033] As an example of some optional parameters, the porosity of the second porous aluminum foam layer 3 is selected from 80% to 99%.

[0034] like Figure 1 , 2As shown, the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 are constructed from cross-linked aluminum fibers 4, and a conductive carbon layer 5 is provided outward from the aluminum fibers 4. To further improve the electrochemical capability of the high-rate 3D composite current collector and optimize the battery rate performance, the conductive carbon layer 5 disposed on the surface of the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 helps to reduce the contact resistance between the active material and the aluminum fibers 4, thereby reducing the internal resistance of the electrode.

[0035] As an example of some optional parameters, the thickness of the extended foil layer 1 is selected from 5-40 μm, which helps to fully enhance the pressure resistance of the high-ratio 3D composite current collector.

[0036] As a preferred example of some optional parameters, the thickness of the extended foil layer 1 is selected from 10-30 μm. The extended foil layer 1 selected from 10-30 μm helps to further optimize and improve the pressure bearing capacity of the high-ratio 3D composite current collector.

[0037] The thickness ratio between the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 is selected from 0.05-5. When the thickness ratio between the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 is selected from 0.05-5, it helps to optimize the electron conduction path and reduce electrode heating.

[0038] As a preferred example of some optional parameters, the thickness ratio between the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 is selected from 0.5-2. Selecting a thickness ratio of 0.5-2 for the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 helps to further optimize the electron conduction path, while improving the pressure resistance of the high-ratio 3D composite current collector.

[0039] As an example of some optional parameters, the thickness of the first porous aluminum foam layer 2 is selected from 100-1000 μm.

[0040] As an example of some optional parameters, the thickness of the second porous aluminum foam layer 3 is selected from 200-2000 μm.

[0041] As an example of some optional parameters, the radius of the aluminum fiber 4 is selected from 0.5-150 μm.

[0042] As a preferred example of some optional parameters, the radius of the aluminum fiber 4 is selected from 20-100 μm. Selecting an aluminum fiber 4 radius of 20-100 μm helps to optimize the conductivity of the high-ratio 3D composite current collector, reduce heat generation, and improve the pressure resistance of the high-ratio 3D composite current collector.

[0043] As an example of some optional parameters, the thickness of the conductive carbon layer 5 is selected from 0.3 nm to 3 μm.

[0044] As a preferred example of some optional parameters, the thickness of the conductive carbon layer 5 is selected from any one of 5nm to 2.5μm, 20nm to 2μm, and 50nm to 1.5μm.

[0045] As a preferred example of some optional parameters, the thickness of the conductive carbon layer 5 is selected from 100 nm to 1 μm, for example, it can be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1 μm. By controlling the thickness of the conductive carbon layer 5 to be selected from 100 nm to 1 μm, it is helpful to further reduce the internal resistance of the high-rate 3D composite current collector.

[0046] As an example of some optional parameters, the material of the extended foil layer 1 is not limited in principle, and can be selected from any one of aluminum, copper, stainless steel, and nickel.

[0047] As an example of some optional parameters, the material of the conductive carbon layer 5 is not limited in principle, and can be selected from any one of graphite, graphene, and conductive carbon black.

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application and do not represent all possible embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0049] The chemical raw materials used in the following examples and comparative examples are all prior art and were obtained commercially. The experimental apparatus and testing equipment used in the following examples and comparative examples are all conventional equipment in the art, and there are no special requirements or limitations.

[0050] Example 1

[0051] S1: A 15μm thick aluminum foil, a 300μm thick polyurethane with a porosity of 94%, and a 300μm thick polyurethane with a porosity of 97% are assembled from the aluminum foil in the order of 94% and 97% polyurethane to form the first precursor of a high-ratio 3D composite current collector. The high-ratio 3D composite current collector precursor is placed in an electrolytic cell containing aluminum molten salt at a temperature of 100℃ and deposited at a voltage of 2.5V for 5 minutes. After being removed, the temperature is reduced to 25℃ by purging with nitrogen and the surface molten salt is washed off with deionized water to obtain the second precursor of the high-ratio 3D composite current collector.

[0052] S2: The first precursor of the high-ratio 3D composite current collector was treated at 400°C for 1 hour in an oxygen-containing gas of 2% oxygen and 98% nitrogen. Then, it was purged with argon for 10 minutes. After purging, the temperature was raised to 500°C for 3 hours under 65 Pa pressure to obtain the third precursor of the high-ratio 3D composite current collector.

[0053] S3: The third precursor of the high-ratio 3D composite current collector is placed into the vapor deposition system, and argon gas carrying aluminum vapor at 700°C is introduced into the low-temperature deposition zone (200°C) for 1.5 hours to obtain the fourth precursor of the high-ratio 3D composite current collector.

[0054] S4: The fourth precursor of the high-rate 3D composite current collector is fixed on the anode of the magnetron sputtering equipment. Graphite is used as the carbon source magnetron sputtering target, which is fixed on the cathode of the magnetron sputtering equipment. The magnetron sputtering equipment is turned on at a pressure of 6 Pa, and the target surface power is 15 W / cm². 2 After reacting for 6.5 hours, a high-rate 3D composite current collector with aluminum fiber 4 having a radius of 35 μm and conductive carbon layer 5 having a thickness of 1 μm was obtained.

[0055] A coating slurry was prepared using lithium iron phosphate as the active material, NMP as the solvent, conductive carbon black and carbon nanotubes as conductive agents, and PVDF as a binder. The coating slurry was then coated onto a high-ratio 3D composite current collector using a doctor blade to obtain an electrode sheet.

[0056] Example 2

[0057] The synthesis and preparation methods are the same as in Example 1, except that from both sides of the aluminum foil outwards, the polyurethane has a porosity of 60% and a porosity of 97% in sequence.

[0058] Example 3

[0059] The synthesis and preparation methods are the same as in Example 1, except that no conductive carbon layer is deposited.

[0060] Example 4

[0061] The synthesis and preparation methods are the same as in Example 1, except that from both sides of the aluminum foil outwards, there are polyurethanes with a porosity of 94% and polyurethanes with a porosity of 97%, wherein the thickness of the polyurethane with a porosity of 94% is selected from 900 μm, and the thickness of the polyurethane with a porosity of 97% is selected from 300 μm.

[0062] Example 5

[0063] The synthesis and preparation methods are the same as in Example 1, except that the aluminum foil thickness is selected from 9 μm.

[0064] Example 6

[0065] The synthesis and preparation methods are the same as in Example 1, except that the deposition time in S4 is 20 h and the thickness of the conductive carbon layer 5 is 3 μm.

[0066] Comparative Example 1

[0067] Aluminum foil is used as the current collector.

[0068] Comparative Example 2

[0069] The preparation method and steps are the same as in Example 1, except that the aluminum foil as the extended foil layer 1 is not provided.

[0070] Comparative Example 3

[0071] The preparation method and steps are the same as in Example 1, except that when assembling the first precursor of the high-ratio 3D composite current collector, a polyurethane with a porosity of 97% is not assembled.

[0072] Comparative Example 4

[0073] The preparation method and steps are the same as in Example 1, except that when assembling the first precursor of the high-ratio 3D composite current collector, the first precursor of the high-ratio 3D composite current collector is assembled from polyurethane with a porosity of 97% and polyurethane with a porosity of 80% in sequence from both sides of the aluminum foil.

[0074] The specific conditions for Examples 1-6 and Comparative Examples 1-4 are shown in Table 1.

[0075] Test methods

[0076] Tensile test: The sample width is 15mm and the length is 150mm. The tensile test is performed using a tensile testing machine at a speed of 50mm / min.

[0077] High-rate 3D composite current collector resistivity testing:

[0078] Take a sample area of ​​10cm² 2 A circular disc was subjected to a pressure of 5 MPa at both ends to test the resistivity of the current collector.

[0079] Electrode resistivity test:

[0080] Take a sample area of ​​10cm² 2 A circular electrode was subjected to a pressure of 5 MPa at both ends to test its resistivity.

[0081] Rate testing: The negative electrode uses graphite as the active material, deionized water as the solvent, conductive carbon black and carbon nanotubes as conductive agents, and CMC and SBR as binders to prepare a coating slurry. The coating slurry is then coated onto a thin copper current collector using a doctor blade to obtain an electrode sheet. The areal density of the electrode sheet is matched with that of the example positive electrode.

[0082] The separator uses a conventional PE membrane, and the electrolyte uses a conventional lithium hexafluorophosphate electrolyte. The battery is assembled and its rate performance is tested (25℃, 1C CC 5C DC).

[0083] The test results of Examples 1-6 and Comparative Examples 1-4 are shown in Table 2.

[0084] Table 1

[0085]

[0086]

[0087] Table 2

[0088] As can be observed from Examples 1-6 and Comparative Examples 1-4, Examples 1-6 exhibit more uniform overall performance than Comparative Examples 1-4. This demonstrates that the high-rate 3D composite current collector proposed in this invention effectively solves the problems of high electrode internal resistance, low active material loading, and poor rate performance when using traditional aluminum foil as a current collector. Furthermore, it addresses the issues of low tensile strength and uneven current distribution when using traditional aluminum foam as a current collector. The carbon-coated aluminum foam layer further reduces the contact resistance between the active material and the aluminum foam current collector, improving the battery rate performance. Thus, a high-rate 3D composite current collector with high toughness, low resistance, and ease of slurry coating is obtained.

[0089] As can be observed from Example 1 and Comparative Example 1, Comparative Example 1, which uses aluminum foil as the current collector, has a resistivity that is much higher than that of Example 1 and an active material load that is much lower than that of Example 1. This indicates that when the high-rate 3D composite current collector proposed in this scheme is used as the current collector, it can effectively improve the active material load and reduce the resistance, thereby optimizing the electrochemical performance of the battery.

[0090] As can be observed from Examples 1 and Comparative Examples 2-3, the overall performance of Comparative Example 2, which lacks aluminum foil as the extended foil layer 1, and Comparative Example 3, which lacks the second porous aluminum foam layer 3, is far inferior to that of Example 1. The tensile strength of Comparative Example 2 is much lower than that of Example 1, and the active material loading of Comparative Example 3 is weaker than that of Example 1. This indicates that in the high-ratio 3D composite current collector, the extended foil layer 1 and the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3, which are sequentially arranged from at least one side of the extended foil layer 1 outward, are both indispensable.

[0091] In Examples 1 and Comparative Example 4, it can be observed that ensuring the porosity ratio N between the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 is less than 1 is also crucial. When the porosity ratio N between the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 in Comparative Example 4 is greater than 1, it is difficult to fully utilize the synergistic effect between different porosities to improve the battery rate performance. Therefore, Comparative Example 4 exhibits a rate performance far lower than that of Example 1.

[0092] As can be observed from Examples 1-2, Example 2 exhibits higher tensile strength and rate performance than Example 1. This may be because the porosity ratio of 0.65≤N<1 helps to further reduce electrode resistance and improve the toughness of high-rate 3D composite current collectors.

[0093] As can be observed in Examples 1 and 3, the setting of conductive carbon layer 5 can effectively optimize the internal resistance of high-rate 3D composite current collector, thereby optimizing the electrode resistivity. As can be observed in Examples 1 and 6, when the thickness of conductive carbon layer 5 is selected from 100nm to 1μm, it can further optimize the internal resistance of high-rate 3D composite current collector.

[0094] Examples 1 and 4 demonstrate the effect of the thickness ratio of the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 on its performance. Table 2 shows that Example 1 exhibits a higher active material loading than Example 4, indicating that a thickness ratio of 0.5-2 between the first porous aluminum foam layer 2 and the second porous aluminum foam layer 3 helps optimize the electron conduction path of the high-ratio 3D composite current collector and improves the active material loading of the high-ratio 3D composite current collector. The thickness of the extended foil layer 1 is also a factor affecting tensile strength. Examples 1 and 5 show that Example 1 exhibits a higher tensile strength than Example 5; therefore, the thickness of the extended foil layer 1 is preferably 10-30 μm.

[0095] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention. Furthermore, without contradiction, those skilled in the art can combine and integrate different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A high-magnification 3D composite current collector, characterized in that, It includes an extended foil layer (1), a first porous aluminum foam layer (2) and a second porous aluminum foam layer (3) sequentially arranged from at least one side of the extended foil layer (1), wherein the ratio of the porosity of the first porous aluminum foam layer (2) and the second porous aluminum foam layer (3) is N < 1.

2. The high-magnification 3D composite current collector according to claim 1, characterized in that, The porosity ratio N between the first porous aluminum foam layer (2) and the second porous aluminum foam layer (3) is selected from 0.65≤N<1.

3. The high-magnification 3D composite current collector according to claim 1, characterized in that, The porosity of the first porous aluminum foam layer (2) is selected from 60% to 97%; The porosity of the second porous aluminum foam layer (3) is selected from 80% to 99%.

4. The high-magnification 3D composite current collector according to claim 1, characterized in that, The thickness of the extended foil layer (1) is selected from 5-40 μm; The thickness ratio between the first porous aluminum foam layer (2) and the second porous aluminum foam layer (3) is selected from 0.05-5.

5. The high-magnification 3D composite current collector according to claim 1, characterized in that, The thickness of the extended foil layer (1) is selected from 10-30 μm; The thickness ratio between the first porous aluminum foam layer (2) and the second porous aluminum foam layer (3) is selected from 0.5-2.

6. The high-magnification 3D composite current collector according to claim 1, characterized in that, The thickness of the first porous aluminum foam layer (2) is selected from 100-1000 μm; As a further option, the thickness of the second porous aluminum foam layer (3) is selected from 200-2000 μm.

7. The high-magnification 3D composite current collector according to claim 1, characterized in that, The first porous aluminum foam layer (2) and the second porous aluminum foam layer (3) are constructed from cross-linked aluminum fibers (4), and a conductive carbon layer (5) is provided outward from the aluminum fibers (4); The radius of the aluminum fiber (4) is selected from 0.5-150 μm; The thickness of the conductive carbon layer (5) is selected from 0.3 nm to 3 μm.

8. The high-magnification 3D composite current collector according to claim 7, characterized in that, The radius of the aluminum fiber (4) is selected from 20-100 μm.

9. The high-magnification 3D composite current collector according to claim 7, characterized in that, The thickness of the conductive carbon layer (5) is selected from any one of 5nm to 2.5μm, 20nm to 2μm, 50nm to 1.5μm, and 100nm to 1μm.

10. An energy storage device, characterized in that, Includes the high-magnification 3D composite current collector as described in any one of claims 1-9.

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