Lightweight 3D composite current collector and preparation method and application thereof

Abstract

The invention discloses a lightweight 3D composite current collector and a preparation method and application thereof, and belongs to the technical field of new energy batteries. The light-weight 3D composite current collector comprises a polyamide urea fiber silk screen, wherein a CuM nano-alloy layer is arranged on the surface of at least one side of the silk screen; copper reinforcing layers are arranged on the edges of the two sides in the width direction of the CuM nano-alloy layer in the extending direction of the silk screen; a carbon material conductive film layer is arranged on the surface of the CuM nano-alloy layer and on the inner side of the copper reinforcing layer, and the carbon material conductive film layer is made of a three-dimensional porous structure conductive carbon material; and the surface density of the lightweight 3D composite current collector is 20-40g / m < 2 >. The light-weight 3D composite current collector is low in surface density, can be directly used as a negative pole piece of a negative-electrode-free battery, and can be used for replacing a pure metal foil current collector to effectively reduce the weight of the battery, so that the energy density of the battery is improved.

Description

Technical Field

[0001] This invention relates to a lightweight 3D composite current collector, its preparation method and application, belonging to the field of new energy battery technology. Background Technology

[0002] Over the past decade, electrodeless alkali metal batteries have attracted widespread attention due to their high energy density, low cost, and ease of production. Current research focuses on improving the energy density of electrodeless batteries; however, a long-neglected issue is the weight of the copper current collector, which accounts for approximately 25% of the total mass of electrodeless lithium metal batteries without contributing any capacity. Therefore, replacing the heavy and electrochemically inactive copper foil with a lightweight alternative can significantly improve the energy density of electrodeless alkali metal batteries.

[0003] Sputtering an ultrathin copper layer onto a polymer substrate as a composite current collector can effectively reduce weight and thus improve the energy density of electrodeless batteries. However, existing composite current collectors suffer from poor interfacial stability, and the copper layer is prone to separation from the polymer substrate, which restricts the electrochemical performance and safety of electrodeless batteries. The core challenge lies in the fact that the interaction between the traditional polymer substrate and the copper layer is usually weak, resulting in a large sheet resistance and extremely poor structural stability of the composite current collector. This limits the reversibility and kinetics of the alkali metal deposition-stripping process, severely restricting the performance improvement and rapid iteration of electrodeless batteries.

[0004] Another fatal flaw of negative electrode-less batteries is that alkali metals themselves have the characteristic of "no host". During the charging and discharging process, alkali metals are deposited and peeled off on the surface of the negative electrode current collector, causing significant volume deformation of the negative electrode. At the same time, the uneven electric field distribution and large nucleation barrier promote the disordered distribution of alkali metal ions, thereby inducing dendrite growth and causing damage to the electrode structure. These factors will jointly lead to the degradation of battery cycle performance and safety hazards. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention proposes a lightweight 3D composite current collector, its preparation method, and its applications. This material has a low areal density and can be directly used as the negative electrode sheet in a negative electrodeless battery. Replacing pure metal foil current collectors with it can effectively reduce battery weight, thereby increasing battery energy density.

[0006] The first aspect of the present invention relates to a lightweight 3D composite current collector, comprising a polyamide-based urea fiber mesh, wherein the mesh is polymerized from a functional monomer containing an acylhydrazine group and an isocyanate crosslinking agent, wherein the fiber diameter in the mesh is 0.2 to 20 μm, the mesh porosity is 20% to 70%, and the mesh pore size is 20 to 50 μm;

[0007] A CuM nano-alloy layer is provided on at least one side surface of the wire mesh, wherein M is selected from at least one of Ag, In, Mg, Zn, Sn, Bi, and Au; the thickness of the CuM nano-alloy layer is 0.1–2 μm, and the Cu content is greater than 90 wt%.

[0008] Along the wire mesh extension direction, copper reinforcement layers are provided on both sides of the CuM nano-alloy layer width direction;

[0009] A carbon material conductive film layer is provided on the surface of the CuM nano-alloy layer and inside the copper reinforcement layer (the carbon material conductive film layer abuts against the inner surface of the copper reinforcement layer). The carbon material conductive film layer is composed of a three-dimensional porous conductive carbon material with an average pore size of 1-5 μm and a porosity greater than 90%.

[0010] The areal density of the lightweight 3D composite current collector is 20–40 g / m³. 2 .

[0011] The second aspect of this invention relates to a method for preparing a lightweight 3D composite current collector, comprising the following steps:

[0012] Step 1: Using functional monomers containing hydrazide groups and isocyanate crosslinking agents as raw materials, weave polyamide-based urea fiber mesh with a fiber diameter of 0.2–20 μm, a mesh porosity of 20%–70%, and a mesh pore size of 20–50 μm.

[0013] Step 2: Deposit Cu and metal M on at least one side of the screen to form a CuM nano-alloy layer; M is selected from at least one of Ag, In, Mg, Zn, Sn, Bi, and Au; the alloy layer thickness is 0.1–2 μm, and the Cu content is greater than 90 wt%.

[0014] Step 3: Along the wire mesh extension direction, copper is plated on both sides of the CuM nano-alloy layer width direction to form a copper reinforcement layer;

[0015] Step 4: Coat the surface of the CuM nano-alloy layer and the inside of the copper reinforcement layer with a three-dimensional porous conductive carbon material to form a carbon material conductive film with a pore size of 1-5 μm and a porosity greater than 90%. The thickness of the carbon material conductive film is greater than that of the copper reinforcement layer.

[0016] Step 5: Finally, calendering and slitting are performed to obtain a surface density of 20–40 g / m³. 2 Lightweight 3D composite current collector.

[0017] A third aspect of the present invention relates to the application of the above-mentioned lightweight 3D composite current collector in a battery.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] 1. Using polyamide-based urea fiber mesh as a substrate, the NH and C=O groups on it have a strong coordination effect with the nano-metal particles, thus forming a stable PASC-CuM mesh film, giving the composite current collector excellent interfacial stability; even after repeated bending, the surface CuM nano-alloy layer remains dense and uniform, and the resistance remains stable; the strong interfacial interaction between the substrate and the CuM nano-alloy layer enhances the interfacial stability, flexibility, and safety of the negative electrode-free battery; the material after depositing the CuM nano-alloy layer still has a mesh structure, which is conducive to the bonding of carbon material conductive film layer, making the overall structure more robust and greatly enhancing the mechanical strength, tensile strength, and conductivity of the current collector material;

[0020] 2. The CuM nano-alloy layer is set at the bottom of the carbon material conductive film layer. M, as a seed crystal, can provide activation sites for alkali metal deposition, ensuring that the metal element is preferentially deposited inside the carbon material conductive film layer. The carbon material conductive film layer has a three-dimensional porous structure with moderate pore size, high porosity, and large pore volume, which is conducive to the storage and transport of metal ions. It can effectively reduce the local current density, delay the appearance of metal dendrites, and the huge pore volume provides sufficient space for the storage of alkali metals, which can effectively avoid the volume expansion of the negative electrode during charging.

[0021] 3. The lightweight 3D composite current collector has a low surface density and can be directly used as the "negative electrode" of batteries without a negative electrode (without pre-placed negative electrode active material). Replacing pure metal foil current collectors with it can effectively reduce battery weight, thereby increasing battery energy density.

[0022] 4. Polyamide-based urea fiber meshes are constructed using functional monomers containing hydrazide groups and isocyanate crosslinking agents as the main raw materials. The strong coordination between the NH and C=O groups of these fibers and the nano-metal particles forms binding sites. Based on these binding sites, the CuM nano-alloy layer directly deposited on the mesh surface is ensured to have good bonding stability with the mesh. This method is simple, direct, time-saving, labor-saving, safe, and reliable, and is suitable for large-scale production. It overcomes the prejudice that setting a metal layer on an organic substrate requires pretreatment of the organic substrate to improve the bonding performance between the two. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the cross-sectional structure of the lightweight 3D composite current collector in an embodiment of the present invention;

[0024] Figure 2 Here is a SEM image of the PASC fiber mesh from Example 1;

[0025] Figure 3 Here is a SEM image of the PASC-CuIn mesh in Example 1;

[0026] Figure 4This is a comparison graph showing the resistance changes of PASC-CuIn mesh and commercially available pure Cu foil after the bending experiment in Example 1.

[0027] Figure 5 The image shows a surface SEM image of the lightweight 3D composite current collector in Example 1.

[0028] In the figure: 100, wire mesh; 200, CuM nano-alloy layer; 300, copper reinforcement layer; 400, carbon material conductive film layer. Detailed Implementation

[0029] The embodiments of the present invention will now be described in detail. Experimental methods not specifically described in the embodiments were performed according to conventional methods and conditions.

[0030] This invention relates to a method for preparing a lightweight 3D composite current collector, comprising the following steps:

[0031] Step 1: Using functional monomers containing hydrazide groups and isocyanate crosslinking agents as raw materials, polyamide-based urea fiber mesh is constructed to obtain mesh 100 with fiber diameter of 0.2-20 μm, porosity of 20%-70%, and pore size of 20-50 μm.

[0032] Step 2: Cu and metal M are deposited on at least one side of the screen to form a CuM nano-alloy layer 200, resulting in a PASC-CuM screen film; M is selected from at least one of Ag, In, Mg, Zn, Sn, Bi, and Au; the thickness of the CuM nano-alloy layer is 0.1–2 μm, and the Cu content is greater than 90 wt%.

[0033] Step 3: Along the wire mesh extension direction, copper is plated on both sides of the CuM nano-alloy layer width direction to form a copper reinforcement layer 300.

[0034] Step 4: Coat the surface of the CuM nano-alloy layer and the inner side of the copper reinforcement layer with a three-dimensional porous conductive carbon material to form a carbon material conductive film layer 400. The pore size of the carbon material conductive film layer is 1-5 μm, the porosity is greater than 90%, and the thickness of the carbon material conductive film layer is greater than that of the copper reinforcement layer.

[0035] Step 5, finally calendering and slitting to form as shown Figure 1 The lightweight 3D composite current collector shown has an areal density of 20–40 g / m³. 2 .

[0036] For some specific implementation schemes, the construction of polyamide-based urea fiber mesh in step one can be carried out by any one of the following methods: electrospinning, charge-induction spinning, melt spinning, wet spinning, dry spinning, and dry-wet spinning.

[0037] For some specific implementation schemes, the functional monomer containing the hydrazide group in step one is at least one of terephthalohydrazide, isophthalohydrazide, o-phthalohydrazide, trimesohydrazide, adipate dihydrazide, sebacic dihydrazide, and succinic dihydrazide; the isocyanate crosslinking agent is at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isoflurane diisocyanate, xylene diisocyanate, and diphenylmethane diisocyanate.

[0038] Preferably, the molar ratio of the hydrazide group in the functional monomer to the cyanate group in the crosslinking agent is 1:1.

[0039] For some specific implementation schemes, the fiber diameter of the wire mesh 100 can be 0.2μm, 0.5μm, 1μm, 5μm, 10μm, 15μm, 20μm, etc., the porosity of the wire mesh can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, etc., and the opening diameter of the wire mesh can be 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.

[0040] For some specific implementation schemes, the deposition in step two uses processes such as vapor deposition, sputtering, electroless plating, or electroplating.

[0041] For some specific implementation schemes, the thickness of the CuM nanoalloy layer can be 0.1μm, 0.5μm, 1μm, 1.5μm, 2μm, etc., and the Cu content can be 91wt%, 92wt%, 95wt%, 96wt%, 99wt%, etc.

[0042] In some specific implementation schemes, the copper reinforcement layer can be used as a battery current-conducting tab on the one hand, and as a "reinforcing rib" when the electrode sheet is coated at high speed on the other hand; its thickness is 1 to 3 μm, and its width (perpendicular to the material extension direction) is 6 to 12 mm. For example, the thickness can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, etc., and the width can be 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, etc.

[0043] For some specific implementation schemes, the thickness of the carbon material conductive film layer is 20 to 50 μm, for example, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0044] For some specific implementation schemes, the average pore size of the carbon material conductive film layer is 1 to 5 μm, and the porosity is greater than 90%; for example, the pore size can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc., and the porosity can be 91%, 92%, 95%, 97%, etc.

[0045] Example 1

[0046] The process for preparing the lightweight 3D composite current collector in this embodiment is as follows.

[0047] Weaving polyamide urea (PASC) fiber webs

[0048] S11, add hexamethylene diisocyanate and polyethylene glycol (PPG-1000) in a molar ratio of 2:1 to DMF with an equal mass of the two, and stir at 80°C for 8 hours to form hexamethylene diisocyanate-polyethylene glycol prepolymer A;

[0049] In step S12, isophthalohydrazide, hexamethylene diisocyanate trimer, and DMF in a molar ratio of 1.25:0.17 are added to prepolymer A, and the mixture is stirred at 80°C for 1 hour to obtain a spinning precursor solution. The amount of DMF in step S12 is four times that in step S11. The molar ratio of hydrazide groups in the functional monomer to cyanate groups in the crosslinking agent is 1:1.

[0050] S13, the spinning voltage of the spinning precursor solution was set to 25kV, and electrospinning was performed using a stainless steel needle. The fibers were collected on a grounded aluminum foil (receiving distance of 10cm), then rolled, peeled, and wound to obtain a PASC fiber web with a thickness of 6μm and a porosity of 50%. Its scanning electron microscope image is shown below. Figure 2 As shown.

[0051] CuM alloy deposited on wire mesh surface

[0052] The PASC fiber mesh obtained in step S13 was mounted into a magnetron sputtering apparatus, and a CuIn alloy target was inserted. Using argon as the working atmosphere, CuIn alloy layers were sputtered onto the upper and lower surfaces of the PASC fiber mesh using radio frequency magnetron sputtering mode. The thickness of the CuIn alloy layer on one side was 200 nm. After sputtering, the obtained material was vacuum annealed at 350°C for 2 minutes to obtain the PASC-CuIn mesh film. Its scanning electron microscope image is shown below. Figure 3 As shown;

[0053] Compare Figure 2 and Figure 3 It can be observed that the surface of the PASC fiber mesh still exhibits a mesh structure after sputtering CuM alloy, and the surface is dense. This is related to the strong coordination between the NH and C=O groups on the polyamide urea material and CuM; for example Figure 3 As shown, in terms of material properties, the PASC-CuIn mesh maintains stable resistance even after repeated bending, demonstrating a significant advantage over pure copper foil. Furthermore, the copper reinforcement layer and carbon conductive film layer added on this basis exhibit excellent bonding performance, resulting in a negative electrode composite current collector with good mechanical strength, tensile strength, and conductivity.

[0054] Install copper reinforcement layer

[0055] The brush plating voltage was set to 12V, the temperature to 30℃, and the relative speed of the PASC-CuIn mesh to the brush to 1.5m / min. High-speed brush plating was performed on both sides of the CuM nano-alloy layer in the width direction using a high-speed copper plating solution (copper sulfate 45g / L, sulfuric acid 200g / L, sodium chloride 0.3g / L, potassium hydroxide 25g / L, glycerol 7.5g / L, solvent: deionized water) to form a copper reinforcement layer with a thickness of 2μm and a width of 6mm. After that, it was cleaned and dried.

[0056] Set a conductive film layer of carbon material

[0057] 10 kg of carbon nanofibers (Suzhou First Element Nanotechnology Co., Ltd., CNTp, diameter 50-200 nm, aspect ratio 50-400) were added to 90 kg of 50% alcohol solution. After ultrasonic treatment, 7 kg of 10% polyvinyl alcohol solution and 3 kg of 10% sodium carboxymethyl cellulose solution were added to the mixture. The mixture was stirred continuously at 200 rpm for 30 min to ensure thorough mixing and obtain carbon nanofiber dispersion. The dispersion was coated on both sides of a reinforced PASC-CuIn mesh and freeze-dried to form a conductive carbon material film layer.

[0058] The scanning electron microscope image of the conductive film layer of the carbon material is shown below. Figure 5 As shown, the average pore size is 1–5 μm, the porosity is 91%, and the pore volume is large (1.88 cm³). 3 The above characteristics are beneficial for the storage and transport of metal ions, can effectively reduce local current density, delay the appearance of metal dendrites, and the huge pore volume can provide sufficient space for the storage of alkali metals, effectively avoiding the volume expansion of the negative electrode during charging.

[0059] Finally, after calendering and slitting, a total thickness of 66.4 μm and an areal density of 28.72 g / m³ were obtained. 2 The 3D composite current collector can be directly used as the "negative electrode" of a negative electrodeless battery.

[0060] Example 2

[0061] The difference from Example 1 is that:

[0062] Before preparing prepolymer A, adipic acid dihydrazide, dicyclohexylmethane diisocyanate, and trihexamethylene diisocyanate in a molar ratio of 90.9:89.4:1 were directly added to 2.5 times the mass of DMF, and the mixture was stirred thoroughly to prepare a spinning precursor solution.

[0063] The prepared composite current collector has a total thickness of 66.2 μm and a material surface density of 28.57 g / m³. 2 .

[0064] Example 3

[0065] The difference from Example 2 is that:

[0066] The molar ratio of adipate dihydrazide, dicyclohexylmethane diisocyanate, and trihexamethylene diisocyanate in the spinning precursor solution was 88.625:87.125:1.

[0067] The prepared composite current collector has a total thickness of 66 μm and a material surface density of 28.52 g / m³. 2 .

[0068] Comparative Example 1

[0069] Commercially available copper foil was used as the negative electrode current collector. The copper foil thickness was 10 μm, and the material surface density was 89.6 g / m³. 2 .

[0070] Electrochemical performance tests were conducted on the samples described in the above embodiments and comparative examples. The batteries were assembled using a self-made lithium iron phosphate positive electrode, a 1 mol / L LiPF6 electrolyte (the solvent was a 1:1 volume ratio EC / DMC mixed solvent), and a Celgard 2325 separator, with the positive electrode / separator / negative electrode composite current collector arranged in the following manner. The test results are shown in Table 1.

[0071] The process of making the positive electrode sheet is as follows: Lithium iron phosphate (LFP), lithium supplementer Li2S, binder PVDF, conductive additive SP, and conductive additive CNTp (Suzhou First Element Nanotechnology Co., Ltd.) were dispersed in N-methylpyrrolidone (NMP) at a weight ratio of 95:0.5:2.2:1.8:1.5 and stirred to form a uniform slurry. This positive electrode slurry was then coated onto carbon-coated aluminum foil as a current collector substrate, vacuum dried at 80°C for 12 hours, and then calendered and slit to obtain the LFP positive electrode sheet. The single-sided mass loading of the LFP was approximately 29.4 mg / cm³. 2 Equivalent to 5mAh / cm 2 .

[0072] Table 1 Group Energy density, Wh / kg 1C / 200-cycle capacity retention First charge negative electrode volume expansion rate Example 1 323.8 88.5% 0 Example 2 328.4 86.7% 0 Example 3 330.2 89.2% 0 Comparative Example 1 292.9 76 cycles of short circuit 400.5%

[0073] The negative electrode volume expansion rate is calculated as (v-v0) / v*100%, where v is the negative electrode volume when fully charged and v0 is the original negative electrode volume.

[0074] As can be seen from Table 1:

[0075] 1. In the implementation of this invention, whether or not a prepolymer needs to be synthesized does not affect the preparation of PASC fiber mesh, nor will it have an adverse effect on the performance of the battery;

[0076] 2. Batteries made using commercially available copper foil as the negative electrode experienced short circuits after only 76 cycles, and disassembly revealed that the separator was punctured. In contrast, the negative electrode-free batteries made by using the composite current collector prepared by the method of this invention as the "negative electrode" have energy densities that are much higher than those of the batteries made in the comparative example. The capacity retention rate after 200 cycles at 1C / 1C is above 85%, and the battery charge-discharge performance and safety performance are better.

[0077] 3. The volume expansion rate of the negative electrode in the comparative example reached an astonishing 400%, while the battery prepared by the present invention showed no volume expansion before and after the first charge. This indicates that the negative electrode current collector prepared by the present invention can better accommodate alkali metals, thereby ensuring that the battery has excellent electrical performance.

[0078] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A lightweight 3D composite current collector, characterized in that, Including polyamide-based urea fiber mesh; The mesh is polymerized from functional monomers containing hydrazide groups and isocyanate crosslinking agents. The fiber diameter in the mesh is 0.2-20 μm, the mesh porosity is 20%-70%, and the mesh pore size is 20-50 μm. A CuM nano-alloy layer is provided on at least one side surface of the wire mesh, wherein M is selected from at least one of Ag, In, Mg, Zn, Sn, Bi, and Au; the thickness of the CuM nano-alloy layer is 0.1–2 μm, and the Cu content is greater than 90 wt%. Along the wire mesh extension direction, copper reinforcement layers are provided on both sides of the CuM nano-alloy layer width direction; A carbon material conductive film layer is provided on the surface of the CuM nano-alloy layer and inside the copper reinforcement layer. The carbon material conductive film layer is composed of a three-dimensional porous conductive carbon material with an average pore size of 1-5 μm and a porosity of more than 90%. The areal density of the lightweight 3D composite current collector is 20–40 g / m³. 2 .

2. The lightweight 3D composite current collector according to claim 1, characterized in that, The copper reinforcement layer has a thickness of 1–3 μm and a width of 6–12 mm.

3. The lightweight 3D composite current collector according to claim 1, characterized in that, The carbon material conductive film layer is made of at least one of carbon nanofibers, carbon nanotubes, graphene, and porous carbon.

4. A method for preparing a lightweight 3D composite current collector, characterized in that, Includes the following steps: Step 1: Using functional monomers containing hydrazide groups and isocyanate crosslinking agents as raw materials, weave polyamide-based urea fiber mesh with a fiber diameter of 0.2–20 μm, a mesh porosity of 20%–70%, and a mesh pore size of 20–50 μm. Step 2: Deposit Cu and metal M on at least one side of the screen to form a CuM nano-alloy layer; M is selected from at least one of Ag, In, Mg, Zn, Sn, Bi, and Au; the alloy layer thickness is 0.1–2 μm, and the Cu content is greater than 90 wt%. Step 3: Along the wire mesh extension direction, copper is plated on both sides of the CuM nano-alloy layer width direction to form a copper reinforcement layer; Step 4: Coat the surface of the CuM nano-alloy layer and the inside of the copper reinforcement layer with a three-dimensional porous conductive carbon material to form a carbon material conductive film with a pore size of 1-5 μm and a porosity greater than 90%. The thickness of the carbon material conductive film is greater than that of the copper reinforcement layer. Step 5: Finally, calendering and slitting are performed to obtain a surface density of 20–40 g / m³. 2 Lightweight 3D composite current collector.

5. The preparation method according to claim 4, characterized in that, In step one, the polyamide-based urea fiber web is constructed using any one of the following methods: electrospinning, charge-induction spinning, melt spinning, wet spinning, dry spinning, or dry-wet spinning.

6. The preparation method according to claim 4, characterized in that, The functional monomer containing the hydrazide group mentioned in step one is at least one of terephthalohydrazide, isophthalohydrazide, o-phthalohydrazide, trimesohydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, and succinic acid dihydrazide; the isocyanate crosslinking agent is at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isoflurone diisocyanate, xylene diisocyanate, and diphenylmethane diisocyanate. Preferably, the molar ratio of the hydrazide group in the functional monomer to the cyanate group in the crosslinking agent is 1:

1.

7. The preparation method according to claim 4, characterized in that, In step two, the deposition process employs vapor deposition, sputtering, electroless plating, or electroplating.

8. The preparation method according to claim 4, characterized in that, The copper reinforcement layer has a thickness of 1–3 μm and a width of 6–12 mm.

9. The preparation method according to claim 4, characterized in that, The thickness of the carbon material conductive film is 20-50 μm, the average pore size of the carbon material conductive film is 1-5 μm, and the porosity is greater than 90%.

10. The application of the lightweight 3D composite current collector according to any one of claims 1 to 9 in a battery.

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