Functional current collector, preparation method thereof and battery using functional current collector

Abstract

The invention provides a functional current collector, a preparation method thereof and a battery using the functional current collector. The functional current collector comprises a carbon fiber skeleton and an aluminum nanofiber layer arranged on the surface of the carbon fiber skeleton, the carbon fiber skeleton has a porous structure, the porosity of the carbon fiber skeleton is 60-80%, and the pore diameter of the carbon fiber skeleton is 5-50 [mu] m. The functional current collector provided by the invention has excellent bending performance, can provide a buffer space for volume expansion of an electrode material, is wide in application range, can be adapted to a high-capacity electrode material, prolongs the cycle service life of a battery using the functional current collector, has good conductivity, and is suitable for popularization and application. And the charge-discharge efficiency and the rate capability of the battery using the material are improved.

Description

Technical Field

[0001] This invention relates to the field of current collector technology, specifically to a functional current collector, its preparation method, and a battery using the functional current collector. Background Technology

[0002] In lithium-ion batteries and next-generation high-energy-density energy storage devices, the current collector, as the core component that carries the active material and enables electron transport, directly affects the battery's cycle life, rate performance, and safety through its structural design and performance. With the widespread application of high-capacity electrode materials such as silicon-based and tin-based materials, the dramatic volume expansion (typically exceeding 300%) that occurs during charging and discharging places higher demands on the structural adaptability and interface stability of the current collector.

[0003] Currently, the widely used traditional pure aluminum foil current collectors are mainly produced by processing aluminum ingots into aluminum foil through rolling and other methods. The pure aluminum foil current collectors prepared by this process have a dense structure and a porosity close to zero. This makes it difficult to effectively buffer the volume changes of high-capacity electrode materials during the lithium insertion / deintercalation process. The active material is easily peeled off and the current collector structure is broken due to repeated stress accumulation, which in turn causes the battery capacity to decay rapidly and the cycle life to decrease.

[0004] To improve the buffering performance of current collectors, existing technologies attempt to develop porous aluminum current collectors and carbon-aluminum composite current collectors. Porous aluminum current collectors mainly construct porous structures in the aluminum matrix through corrosion or electrolysis. However, the porous structures formed by such methods often lead to a decrease in the continuity of the conductive network, resulting in a significant increase in the surface resistance of the current collector, affecting electron transport efficiency, and limiting the rate performance and power output of the battery. Carbon-aluminum composite current collectors are generally manufactured using powder metallurgy processes to combine carbon materials such as graphite with an aluminum matrix. For example, aluminum-based powder and graphite powder are ball-milled and mixed uniformly in a certain proportion, then filled into a vacuum hot-pressing sintering furnace mold cavity for multi-stage vacuum hot-pressing sintering, followed by hot extrusion and other processes. Although this type of carbon-aluminum composite current collector can combine the flexibility of carbon materials with the conductivity of metals, this method still has obvious shortcomings in practical applications: the carbon materials are poorly dispersed uniformly in the aluminum matrix, the interfacial bonding force is weak, and delamination is prone to occur during long-term cycling; at the same time, the process control is difficult, and it is often difficult to balance high porosity and structural density, resulting in insufficient mechanical strength of the material or discontinuous conductive pathways.

[0005] In summary, existing current collector technologies face the following common challenges in high-capacity battery systems: First, traditional metal foils and porous metal structures struggle to provide effective volume expansion buffer space while maintaining high conductivity; second, the interfacial bonding strength in carbon-aluminum composites is low, making them prone to interfacial failure under cyclic stress; and third, existing fabrication processes generally cannot achieve synergistic control over pore structure, conductive network, and interfacial properties. Therefore, developing a novel current collector that combines good flexibility, a continuous conductive path, and controllable porous buffering function is crucial for improving the performance and reliability of high-capacity batteries. Summary of the Invention

[0006] To address the problems of existing traditional pure aluminum foil current collectors being unable to adapt to the volume expansion of high-capacity electrode materials such as silicon / tin, leading to structural breakage, and the poor continuity of the conductive network and excessively high surface resistivity of porous aluminum current collectors, as well as the weak interfacial bonding of carbon-aluminum composite materials causing easy delamination during cycling, this invention provides a functional current collector, its preparation method, and a battery using the functional current collector.

[0007] According to a first aspect of the present invention, a functional current collector is provided, the functional current collector comprising a carbon fiber skeleton and an aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton; the carbon fiber skeleton has a porous structure, the porosity of the carbon fiber skeleton is 60-80%, and the pore size of the carbon fiber skeleton is 5-50 μm.

[0008] The functional current collector provided by this invention comprises a carbon fiber skeleton and an aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton. Firstly, the porous carbon fiber skeleton constructs a three-dimensional porous support structure, providing a stable basic support framework for the entire functional current collector. Its porosity is controlled between 60% and 80%, and its pore size is controlled between 5 and 50 μm, giving the functional current collector excellent bending performance and better flexibility. The larger porosity and moderate pore size can effectively buffer the volume expansion of high-capacity electrode materials (such as silicon or tin) during charging and discharging, reserving sufficient space for the volume change of the active material, thereby reducing the structural stress caused by volume change. This effectively solves the problem that traditional pure aluminum foil current collectors cannot adapt to the volume expansion of high-capacity electrode materials, leading to current collector structure breakage. This improves the compatibility of the functional current collector with high-capacity electrode materials and extends the cycle life of batteries using this functional current collector. Secondly, the porosity characteristics of the porous carbon fiber skeleton can provide approximately 80% of the volume expansion buffer space for high-capacity electrode materials, helping to improve the performance of the functional current collector when dealing with volume changes in high-capacity electrode materials and enhancing its practical application. Thirdly, the aluminum nanofibers in the aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton are continuously distributed and interwoven within the carbon fiber skeleton to form a continuous conductive network structure. This maintains a low sheet resistance of the functional current collector, greatly improving its conductivity. In actual operation, electrons can be efficiently transported in the conductive network formed by the aluminum nanofibers in the aluminum nanofiber layer, reducing the resistance to electron transport and thus improving the charge-discharge efficiency and rate performance of the battery. Fourthly, the porous structure and high porosity of the carbon fiber skeleton result in a high interfacial bonding force between it and the aluminum nanofiber layer, reducing the risk of delamination during cycling and extending the cycle life of the battery using this functional current collector. In summary, the functional current collector provided by this invention has excellent bending performance and can provide buffer space for the volume expansion of electrode materials. It has a wide range of applications, can be adapted to high-capacity electrode materials, extends the cycle life of batteries using it, and has good conductivity, improving the charge-discharge efficiency and rate performance of batteries using it.

[0009] Preferably, the carbon fiber skeleton has a honeycomb structure.

[0010] The honeycomb-structured carbon fiber skeleton can also form a continuous conductive network structure. Its synergistic effect with the continuous conductive network structure formed by aluminum nanofibers in the aluminum nanofiber layer can further improve the conductivity of the functional current collector, thereby improving the charge and discharge efficiency and rate performance of the battery using this functional current collector.

[0011] Preferably, the cross-sectional diameter of the carbon fibers in the carbon fiber skeleton is 750~850 nm.

[0012] Controlling the cross-sectional diameter (i.e. width) of a single carbon fiber in the carbon fiber skeleton within the aforementioned range has two advantages: firstly, it helps maintain the three-dimensional porous structure of the carbon fiber skeleton and further enhances its mechanical support strength and structural stability; secondly, it allows the carbon fiber to maintain a certain degree of flexibility while providing a more uniform stress distribution for the functional current collector, thereby better adapting to the volume changes of the electrode material during cycling.

[0013] Preferably, the cross-sectional diameter of the aluminum nanofibers in the aluminum nanofiber layer is 50~200 nm.

[0014] Controlling the cross-sectional diameter (i.e. width) of individual aluminum nanofibers in the aluminum nanofiber layer within the aforementioned range is beneficial for forming a denser and more continuous conductive network on and inside the carbon fiber skeleton. Furthermore, the finer aluminum nanofibers can cover a larger area of ​​the carbon fiber surface, enhancing the contact points between fibers, thereby effectively improving electron transfer efficiency, reducing interfacial resistance, and further enhancing the overall conductivity of the functional current collector. This helps to improve the charge-discharge efficiency and rate performance of batteries using this functional current collector.

[0015] Preferably, the aluminum nanofiber layer contains aluminum whiskers with a length of 1~3 μm.

[0016] In addition to aluminum nanofibers, the aluminum nanofiber layer also contains aluminum whiskers. The presence of aluminum whiskers can enhance the mechanical interlocking effect between the carbon fibers in the carbon fiber skeleton and the aluminum nanofiber network in the aluminum nanofiber layer. This mechanical interlocking mechanism makes the bond between the carbon fiber skeleton and the aluminum nanofiber network stronger. During battery cycling, it can effectively resist interface separation caused by factors such as changes in electrode material volume and charging and discharging stress, thus ensuring the stability and durability of the functional current collector structure.

[0017] Preferably, the total volume of the aluminum nanofiber layer is V1, and the total volume of the functional current collector is V2. V1 and V2 satisfy 35%≤V1 / V2≤45%.

[0018] By controlling the volume fraction of the aluminum nanofiber network in the aluminum nanofiber layer within the total volume of the entire functional current collector (including the carbon fiber skeleton and the aluminum nanofibers in the aluminum nanofiber layer), i.e. the amount of aluminum nanofiber filling, within the aforementioned range, firstly, it can maintain the overall structural stability of the functional current collector and better balance its conductivity and mechanical strength; secondly, it helps the aluminum nanofibers form a more continuous and uniformly distributed three-dimensional conductive network on the carbon fiber skeleton, thereby significantly improving the electron transport efficiency in the current collector and effectively reducing the interfacial resistance; thirdly, the appropriate volume fraction of the aluminum nanofiber network in the aluminum nanofiber layer in the functional current collector can avoid affecting the inherent porous buffering characteristics of the carbon skeleton due to excessive aluminum nanofibers, ensuring that it can still effectively adapt to the volume changes of the electrode material. Therefore, by controlling the amount of aluminum nanofiber network filling in the entire functional current collector, the functional current collector can further enhance its conductivity and structural reliability while maintaining good structural flexibility and buffering capacity, thereby improving its overall cycle stability and rate performance in battery applications.

[0019] Preferably, the above-mentioned functional current collector further includes an electrolyte layer, which is disposed on the surface of the aluminum nanofiber layer. The electrolyte layer includes polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and the mass percentage of polyvinylidene fluoride-hexafluoropropylene in the electrolyte layer is 81-95%.

[0020] Further, by setting an electrolyte layer containing polyvinylidene fluoride-hexafluoropropylene on the surface of the aluminum nanofiber layer, the functional current collector can be given higher flexibility.

[0021] Preferably, the electrolyte layer further includes a lithium salt, wherein the lithium salt accounts for 5-19% of the mass of the electrolyte layer; the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), and lithium tetrafluoroborate (LiBF4).

[0022] By further introducing lithium salt into the electrolyte layer and controlling the mass ratio of lithium salt in the electrolyte layer within a certain range, the overall performance of the functional current collector can be improved. Specifically, the addition of lithium salt helps to provide sufficient migratable lithium ions in the electrolyte layer, thereby further improving the ionic conductivity of the functional current collector and promoting efficient ion transport during battery charging and discharging. Furthermore, the synergistic effect of PVDF-HFP and lithium salt optimizes the flexibility and electrochemical stability of the electrolyte layer, enabling the functional current collector to maintain good structural integration while possessing superior interfacial ion transport characteristics, thereby helping to improve the overall cycle stability and safety performance of the battery.

[0023] According to a second aspect of the present invention, a method for preparing a functional current collector is provided, comprising the following steps: S1. A precursor solution is deposited onto a receiving device by electrospinning to form a fiber membrane, wherein the precursor solution includes a precursor, which includes at least one of polyacrylonitrile (PAN), polyimide, polyvinyl alcohol, and pitch. S2. Carbonize the fiber membrane to form a carbon fiber skeleton with a porous structure, wherein the porosity of the carbon fiber skeleton is 60-80% and the pore size of the carbon fiber skeleton is 5-50 μm. S3. The carbon fiber skeleton is added to an electrolyte containing aluminum ions, and the aluminum ions are reduced to aluminum metal atoms by electrodeposition and deposited on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer, thus obtaining a functional current collector.

[0024] In the preparation method of the functional current collector provided in this scheme, the precursor solution containing the above-mentioned materials is first stably formed into a jet under the action of an electric field through electrospinning technology, so that the precursor material in the precursor solution is deposited on the receiving device to obtain a fiber membrane. Then, the cellulose membrane is subjected to carbonization treatment. During the carbonization treatment, the non-carbon elements in the fiber membrane are gradually removed to form a carbon fiber skeleton with a porous structure, a porosity of 60-80%, and a pore size of 5-50 μm. The carbon fiber skeleton has excellent bending performance and high conductivity. The large porosity and moderate pore size can effectively buffer the volume expansion of high-capacity electrode materials (such as silicon or tin) during charging and discharging, leaving sufficient space for the volume change of active material, thereby reducing the structural stress caused by volume change. This effectively solves the problem that traditional pure aluminum foil current collectors cannot adapt to the volume expansion of high-capacity electrode materials, which leads to the breakage of the current collector structure. It improves the compatibility of functional current collectors with high-capacity electrode materials and extends the cycle life of batteries using this functional current collector. Then, the electrolyte is deposited using electrodeposition technology. Aluminum ions in the carbon fiber skeleton are reduced to aluminum metal atoms and deposited on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer. During the forming process, the aluminum nanofibers formed by the reduction of aluminum ions are continuously distributed and interwoven inside the carbon fiber skeleton to form a continuous conductive network structure. This allows the functional current collector to maintain a low sheet resistance, which greatly improves the conductivity of the functional current collector and the charge / discharge efficiency and rate performance of the battery using this functional current collector. Furthermore, the high interfacial bonding between the carbon fiber skeleton and the aluminum nanofiber layer in the functional current collector prepared by the above method can reduce the risk of delamination during cycling.

[0025] Preferably, S2 includes the following operations: pre-oxidizing the fiber membrane at 250~300℃, and carbonizing the pre-oxidized fiber membrane at 800~1200℃ to obtain a carbon fiber skeleton; during the pre-oxidation process, the heating rate is controlled at 1~5℃ / min; during the carbonization process, the heating rate is controlled at 5~10℃ / min.

[0026] Preferably, the pre-oxidation treatment is carried out in an air atmosphere, and the carbonization treatment is carried out in an argon atmosphere.

[0027] Preferably, the pre-oxidation treatment time is 1 to 3 hours, and the carbonization treatment time is 2 to 4 hours.

[0028] In the preparation of the carbon fiber skeleton, the fiber membrane is first placed in an air atmosphere and heated to 250-300℃ at a rate of 1-5℃ / min and held for 1-3 hours. During this process, the fibers in the fiber membrane undergo a pre-oxidation reaction, and their molecular structure gradually transforms into a ladder structure, which improves the thermal stability of the fibers and lays the foundation for the subsequent carbonization process. Then, the pre-oxidized fiber membrane is placed in an argon atmosphere and heated to 800-1200℃ at a rate of 5-10℃ / min and held for 2-4 hours. Under the protection of high temperature and inert gas, the non-carbon elements in the fibers are gradually removed, forming a carbon fiber skeleton with a porous structure and high conductivity. The carbon fiber skeleton exhibits a pre-set honeycomb structure with a porosity of 60-80%. Therefore, by controlling the temperature and heating rate within the above-mentioned range during the pre-oxidation and carbonization treatment of the fiber membrane, a carbon fiber skeleton with a porous honeycomb structure, high thermal stability, and high conductivity can be prepared. This improves the flexibility, bending resistance, and buffering effect of the functional current collector containing the carbon fiber skeleton on the volume expansion of high-capacity electrode materials during charging and discharging. At the same time, it endows the functional current collector with high conductivity and improves the charge and discharge efficiency and rate performance of the battery using the functional current collector.

[0029] Preferably, in S1, the precursor solution further includes nano-carbon materials, the mass fraction of which is 0.1-1%, and the nano-carbon materials include at least one of carbon nanotubes, graphene nanoribbons, carbon nanofibers, and graphene.

[0030] By adding 0.1–1 wt% of nano-carbon material to the precursor solution, the conductivity of the subsequently prepared fiber membrane can be further enhanced, while the mechanical properties of the fiber membrane can be improved.

[0031] Preferably, in S1, the conditions for electrospinning are as follows: voltage 16~20 kV, ambient humidity 25~35%, and receiving distance 13~17 cm.

[0032] In the process of preparing fiber membranes using electrospinning, the voltage is controlled between 16 and 20 kV. This voltage intensity allows the precursor solution to stably form a jet under the action of the electric field. The ambient humidity is controlled between 25 and 35%. Suitable humidity conditions help maintain the stability of the jet and avoid abnormal fiber morphology due to excessively high or low humidity. The receiving distance is controlled between 13 and 17 cm. At this distance, the jet has sufficient time for solvent evaporation and fiber solidification, while ensuring that the fibers can be uniformly deposited on the receiving device. Therefore, by controlling the voltage, ambient humidity, and receiving distance during the electrospinning process within the aforementioned ranges, fiber membranes with a cross-sectional diameter (i.e., width) of approximately 800 nm per fiber can be obtained. Fibers of this size effectively maintain the structural integrity and mechanical stability of the carbon fiber skeleton during subsequent carbonization, resulting in a three-dimensional porous structure with suitable porosity and pore size distribution. Furthermore, this uniform fiber diameter helps maintain the uniformity of the pore structure during carbonization, thereby enhancing the adaptability of the prepared carbon fiber skeleton to volume changes in high-capacity electrode materials and improving its buffering effect and structural reliability. On this basis, the uniform diameter of the carbon fiber skeleton also provides a good carrier for the subsequent electrodeposition of aluminum nanofiber layers. The consistency of fiber size and surface regularity facilitate the uniform growth of aluminum nanofibers on and inside the skeleton, forming a continuous and dense conductive network, thus significantly improving the electron transport efficiency of the functional current collector and reducing interfacial resistance. In summary, by rationally controlling the electrospinning conditions, the diameter of a single fiber can be controlled during the fiber membrane preparation stage. This allows for the gradual optimization of the porous structure of the carbon fiber skeleton and the conductivity of the aluminum nanofiber layer, ultimately enabling the functional current collector to exhibit comprehensive advantages in terms of mechanical adaptability and electrochemical performance.

[0033] Preferably, in S1, the receiving device is a drum receiver or a flat receiver.

[0034] Preferably, in S1, the mass fraction of the precursor in the precursor solution is 10-15%.

[0035] By controlling the mass fraction of the precursor in the precursor solution within the above-mentioned range, the viscosity of the precursor solution can be kept at a suitable level, which is beneficial to improving the efficiency of subsequent electrospinning and thus obtaining fiber membranes with better performance.

[0036] Preferably, in S1, the precursor solution further includes the solvent N,N-dimethylformamide (DMF) and carbon nanotubes.

[0037] Preferably, in S3, the electrolyte containing aluminum ions includes an ionic liquid, which is prepared by AlCl3 and imidazolium chloride in a molar ratio of (1.1~1.5):1, and the imidazolium chloride includes at least one of 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) and 1-butyl-3-methylimidazolium chloride ([BMIm]Cl).

[0038] In the process of depositing aluminum nanofiber layers on the surface of carbon fiber skeleton using electrodeposition technology, an ionic liquid was prepared by mixing AlCl3 and imidazolium chloride salt in a specific molar ratio as an electrolyte. This electrolyte can provide a stable source of aluminum ions and has good ionic conductivity, which is beneficial to the electrodeposition process.

[0039] Preferably, in S3, the electrodeposition conditions are as follows: temperature 75~85℃, current density 3~7 mA / cm². 2 The deposition time is 25-35 minutes.

[0040] During the deposition of aluminum nanofiber layers on the surface of a carbon fiber skeleton using an electrodeposition process, the current density was controlled at 3–7 mA / cm². 2 The current density is such that it ensures a sufficient deposition rate of aluminum ions on the carbon fiber skeleton surface without causing uneven deposition due to excessive current. The deposition time is controlled between 25 and 35 minutes. Within this time, aluminum ions can be fully deposited and grown into an aluminum nanofiber network in the internal pores and surface of the carbon fiber skeleton. The aluminum nanofibers can deposit and grow from the surface of the carbon fiber skeleton deep inside, with an effective filling depth (i.e., the extension depth of the aluminum nanofibers in the pores of the carbon fiber skeleton) reaching 150 μm. This allows for the full filling of the pores of the carbon fiber skeleton with aluminum nanofibers, forming a uniform conductive network and further improving the conductivity of the functional current collector. The temperature is controlled between 75 and 85℃. A suitable temperature helps to improve the activity and diffusion rate of ions, promoting the smooth progress of the electrodeposition reaction. In summary, by rationally controlling the electrodeposition conditions, aluminum ions can be uniformly deposited on the surface and internal voids of the carbon fiber skeleton and grow into an aluminum nanofiber network, improving the conductivity of the functional current collector. Furthermore, during the aluminum ion deposition process, aluminum whiskers with a length of 1–3 μm grow in situ on the surface of the carbon fibers in the carbon fiber skeleton. These aluminum whiskers enhance the mechanical interlocking effect between the carbon fibers in the carbon fiber skeleton and the aluminum nanofiber network in the aluminum nanofiber layer. This mechanical interlocking mechanism makes the bond between the carbon fiber skeleton and the aluminum nanofiber network stronger, effectively resisting interface separation caused by factors such as electrode material volume changes and charge / discharge stress during battery cycling, thus ensuring the stability and durability of the functional current collector structure.

[0041] In addition, the electrodeposition process uses a temperature range of 75~85℃, which is a low-temperature process. This allows it to be compatible with flexible substrates, making it possible to prepare flexible functional current collectors and broadening the application fields of current collectors, such as in flexible electronic devices.

[0042] Preferably, in step S3, after adding the carbon fiber skeleton to the electrolyte containing aluminum ions, reducing the aluminum ions to aluminum metal atoms by electrodeposition and depositing them on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer, the step further includes coating the surface of the aluminum nanofiber layer with a polyvinylidene fluoride-hexafluoropropylene solution to form an electrolyte layer.

[0043] After depositing an aluminum nanofiber layer on the surface of a carbon fiber skeleton, a polyvinylidene fluoride-hexafluoropropylene solution is further coated on the surface of the aluminum nanofiber layer to form an electrolyte layer, which can improve the flexibility of the functional current collector.

[0044] Preferably, the mass percentage of polyvinylidene fluoride-hexafluoropropylene in the polyvinylidene fluoride-hexafluoropropylene solution is 65-85%.

[0045] Preferably, the polyvinylidene fluoride-hexafluoropropylene solution further includes lithium salt, wherein the mass percentage of lithium salt in the polyvinylidene fluoride-hexafluoropropylene solution is 5-15%, and the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), and lithium tetrafluoroborate (LiBF4).

[0046] Preferably, the polyvinylidene fluoride-hexafluoropropylene solution further includes an organic solvent, wherein the mass percentage of the organic solvent in the polyvinylidene fluoride-hexafluoropropylene solution is 10-20%, and the organic solvent includes at least one of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC).

[0047] According to a third aspect of the present invention, a battery is provided, the battery comprising the above-described functional current collector or a functional current collector prepared by the above-described method for preparing the functional current collector.

[0048] Applying the functional current collector provided by this invention to batteries can extend the cycle life of batteries and improve the charge and discharge efficiency and rate performance of batteries. Detailed Implementation

[0049] The technical features of the technical solution provided by the present invention will be further clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] In the following examples and comparative examples, the porosity of the carbon fiber skeleton can be measured using mercury intrusion porosimetry, a method that can accurately determine the pore volume and total porosity of porous materials within different pore size ranges. The pore size and distribution of the carbon fiber skeleton can be obtained by capturing cross-sectional images using a scanning electron microscope (SEM) and then performing statistical measurements using image analysis software (such as ImageJ). The volume fraction of the aluminum nanofiber layer in the functional current collector is determined by accurately measuring the mass difference of the carbon fiber skeleton before and after electrodeposition to obtain the aluminum deposition mass, combined with the aluminum density (2.70 g / cm³). 3 The volume of the aluminum phase is calculated and then divided by the total volume of the functional current collector (calculated based on its geometry). This volume fraction can be corroborated by the analysis of elemental distribution using scanning electron microscopy (SEM) and the accompanying energy-dispersive X-ray spectroscopy (EDS).

[0051] Example 1 A functional current collector includes a carbon fiber skeleton and an aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton; the carbon fiber skeleton has a porous honeycomb structure with a porosity of 75% and a pore size of 20 μm; the aluminum nanofiber layer accounts for 40 vol% of the volume of the functional current collector. The functional current collector provided in this embodiment is prepared through the following steps: S1. A precursor solution with a mass fraction of 12% PAN was prepared by dissolving polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF). The precursor solution was then deposited onto a receiving device by electrospinning deposition under the action of an electric field to obtain a fiber membrane with a cross-sectional diameter of 800 nm. During the electrospinning process, the voltage was 18 kV, the ambient humidity was 30%, and the receiving distance was 15 cm. S2. The fiber membrane is placed in an air atmosphere and heated to 280°C at a rate of 1°C / min and held for 2 hours to perform pre-oxidation treatment on the fiber membrane. Then, the pre-oxidized fiber membrane is placed in an argon atmosphere and heated to 1000°C at a rate of 8°C / min and held for 3 hours to perform carbonization treatment on the fiber membrane to obtain a carbon fiber skeleton. S3. An ionic liquid was prepared by mixing AlCl3 and [EMIm]Cl at a molar ratio of 1.3:1 as an electrolyte. A carbon fiber skeleton was added to the electrolyte, and aluminum ions were reduced to aluminum metal atoms using an electrodeposition process, which were then deposited on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer, thus obtaining a functional current collector. During the electrodeposition process, the current density was 5 mA / cm². 2 The temperature was 80℃ and the deposition time was 30 min.

[0052] Example 2 A functional current collector includes a carbon fiber skeleton and an aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton; the carbon fiber skeleton has a porous honeycomb structure with a porosity of 60% and a pore size of 5 μm; the aluminum nanofiber layer accounts for 35 vol% of the volume of the functional current collector. The functional current collector provided in this embodiment is prepared through the following steps: S1. A precursor solution with a mass fraction of 12% PAN was prepared by dissolving polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF). The precursor solution was then deposited onto a receiving device by electrospinning deposition under the action of an electric field to obtain a fiber membrane with a cross-sectional diameter of 750 nm. During the electrospinning process, the voltage was 16 kV, the ambient humidity was 25%, and the receiving distance was 13 cm. S2. The fiber membrane is placed in an air atmosphere and heated to 250°C at a rate of 2°C / min and held for 3 hours to pre-oxidize the fiber membrane. Then, the pre-oxidized fiber membrane is placed in an argon atmosphere and heated to 800°C at a rate of 5°C / min and held for 4 hours to carbonize the fiber membrane to obtain a carbon fiber skeleton. S3. An ionic liquid was prepared by mixing AlCl3 and [EMIm]Cl at a molar ratio of 1.1:1 as the electrolyte. A carbon fiber skeleton was added to the electrolyte, and aluminum ions were reduced to aluminum metal atoms and deposited on the surface of the carbon fiber skeleton using an electrodeposition process to form an aluminum nanofiber layer, thus obtaining a functional current collector. During the electrodeposition process, the current density was 3 mA / cm². 2 The temperature was 75℃ and the deposition time was 35 min.

[0053] Example 3 A functional current collector includes a carbon fiber skeleton and an aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton; the carbon fiber skeleton has a porous honeycomb structure with a porosity of 80% and a pore size of 50 μm; the aluminum nanofiber layer accounts for 45 vol% of the volume of the functional current collector. The functional current collector provided in this embodiment is prepared through the following steps: S1. A precursor solution with a mass fraction of 12% PAN was prepared by dissolving polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF). The precursor solution was then deposited onto a receiving device by electrospinning deposition under the action of an electric field to obtain a fiber membrane with a cross-sectional diameter of 850 nm. During the electrospinning process, the voltage was 20 kV, the ambient humidity was 35%, and the receiving distance was 17 cm. S2. The fiber membrane is placed in an air atmosphere and heated to 300°C at a rate of 5°C / min and held for 1 hour to pre-oxidize the fiber membrane. Then, the pre-oxidized fiber membrane is placed in an argon atmosphere and heated to 1200°C at a rate of 10°C / min and held for 2 hours to carbonize the fiber membrane to obtain a carbon fiber skeleton. S3. An ionic liquid was prepared by mixing AlCl3 and [EMIm]Cl at a molar ratio of 1.5:1 as an electrolyte. A carbon fiber skeleton was added to the electrolyte, and aluminum ions were reduced to aluminum metal atoms using an electrodeposition process, which were then deposited on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer, thus obtaining a functional current collector. During the electrodeposition process, the current density was 7 mA / cm². 2 The temperature was 85℃ and the deposition time was 25 min.

[0054] Example 4 This embodiment provides a functional current collector. Compared with embodiment 1, the difference in composition is: (1) In the electrospinning process of the preparation step S1 of the functional current collector, the voltage is 15 kV, the ambient humidity is 40%, and the receiving distance is 11 cm; (2) The porosity of the carbon fiber skeleton obtained in the preparation step S2 of the functional current collector is 65%, and the pore size of the carbon fiber skeleton is 15 μm.

[0055] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0056] Example 5 This embodiment provides a functional current collector. Compared with embodiment 1, the difference in composition is: (1) In the electrospinning process of the preparation step S1 of the functional current collector, the voltage is 22 kV, the ambient humidity is 20%, and the receiving distance is 19 cm; (2) The porosity of the carbon fiber skeleton obtained in the preparation step S2 of the functional current collector is 70%, and the pore size of the carbon fiber skeleton is 25 μm.

[0057] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0058] Example 6 This embodiment provides a functional current collector. Compared with embodiment 1, the difference in composition is: (1) In the preparation step S2 of the functional current collector, the heating rate in the pre-oxidation process is 0.5℃ / min, and the heating rate in the carbonization process is 12℃ / min; (2) The porosity of the carbon fiber skeleton obtained in the preparation step S2 of the functional current collector is 68%, and the pore size of the carbon fiber skeleton is 18 μm.

[0059] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0060] Example 7 This embodiment provides a functional current collector. Compared with embodiment 1, the difference in composition is: (1) In the preparation step S2 of the functional current collector, the heating rate in the pre-oxidation process is 5.5℃ / min, and the heating rate in the carbonization process is 4℃ / min; (2) The porosity of the carbon fiber skeleton obtained in the preparation step S2 of the functional current collector is 68%, and the pore size of the carbon fiber skeleton is 22 μm.

[0061] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0062] Example 8 This embodiment provides a functional current collector. Compared with embodiment 1, the difference in composition is: (1) In the preparation step S2 of the functional current collector, the temperature of the pre-oxidation treatment is 230°C and the temperature of the carbonization treatment is 1250°C; (2) The porosity of the carbon fiber skeleton obtained in the preparation step S2 of the functional current collector is 72% and the pore size of the carbon fiber skeleton is 22 μm.

[0063] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0064] Example 9 This embodiment provides a functional current collector. Compared with embodiment 1, the difference in composition is: in the preparation step S2 of the functional current collector, the temperature of the pre-oxidation treatment is 320°C and the temperature of the carbonization treatment is 750°C; (2) the porosity of the carbon fiber skeleton obtained in the preparation step S2 of the functional current collector is 73% and the pore size of the carbon fiber skeleton is 19 μm.

[0065] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0066] Example 10 This embodiment provides a functional current collector. Compared with Embodiment 1, the difference in composition is: (1) In the electrodeposition process of step S3 of the preparation step of the functional current collector, the temperature is 70°C and the current density is 2 mA / cm. 2 The deposition time is 40 min; (2) The volume ratio of the aluminum nanofiber layer in the functional current collector prepared by step S3 is 30 vol.

[0067] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0068] Example 11 This embodiment provides a functional current collector. Compared with Embodiment 1, the difference in composition is: (1) In the electrodeposition process of step S3 of the preparation step of the functional current collector, the temperature is 87°C and the current density is 8 mA / cm. 2 The deposition time is 20 min; (2) The volume ratio of the aluminum nanofiber layer in the functional current collector prepared by step S3 is 50 vol.

[0069] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0070] Example 12 This embodiment provides a functional current collector. Compared with embodiment 1, the difference in composition is: (1) The functional current collector also includes an electrolyte layer, which is disposed on the surface of the aluminum nanofiber layer. The electrolyte layer includes polyvinylidene fluoride-hexafluoropropylene; (2) In the preparation step S2 of the functional current collector, the carbonization temperature is 800°C; (3) In the preparation step S3 of the functional current collector, after aluminum ions are reduced to aluminum metal atoms by electrodeposition and deposited on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer, the embodiment further includes spin-coating a PVDF-HFP solution prepared by polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and the organic solvent diethyl carbonate (DEC) onto the surface of the aluminum nanofiber layer, and then drying it to form an electrolyte layer with a thickness of 1 μm.

[0071] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0072] Example 13 This embodiment provides a functional current collector. Compared with Embodiment 12, the difference in composition is as follows: (1) The PVDF-HFP solution spin-coated on the surface of the aluminum nanofiber layer also includes a lithium salt; (2) The obtained functional current collector also includes an electrolyte layer, which is disposed on the surface of the aluminum nanofiber layer. The electrolyte layer includes polyvinylidene fluoride-hexafluoropropylene and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), wherein the mass percentage of polyvinylidene fluoride-hexafluoropropylene in the electrolyte layer is 90%, and the mass percentage of lithium salt in the electrolyte layer is 10%; (3) In step S3 of the preparation of the functional current collector, after aluminum ions are reduced to aluminum metal atoms by electrodeposition and deposited on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer, the embodiment further includes spin-coating a PVDF-HFP solution prepared by polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and diethyl carbonate (DEC) on the surface of the aluminum nanofiber layer, and then drying it to form an electrolyte layer with a thickness of 1 μm.

[0073] Apart from the differences mentioned above, the materials, formulation ratios, and preparation operations used in this embodiment are strictly consistent with those in Example 1.

[0074] Comparative Example 1: Traditional pure aluminum foil current collector A functional current collector, which is a pure aluminum foil current collector, is used as the functional current collector in this comparative example, which is made by rolling aluminum ingots into aluminum foil.

[0075] Comparative Example 2: Porous Aluminum Current Collector A functional current collector is prepared by means of the following steps: etching an aluminum foil by anodizing to form a porous structure with a porosity of about 60% and an average pore size of about 10 μm, as the functional current collector provided in this comparative example.

[0076] Comparative Example 3: Carbon-aluminum composite current collector A functional current collector is prepared by the following steps: aluminum powder and graphite powder are ball-milled and mixed at a mass ratio of 9:1, and then hot-pressed and sintered under argon protection at a temperature of 600℃ and a pressure of 30 MPa for 2 hours to obtain a carbon-aluminum composite current collector, which is used as the functional current collector provided in this comparative example.

[0077] Comparative Example 4 A functional current collector includes a carbon fiber skeleton and an aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton; the carbon fiber skeleton has a porous honeycomb structure with a porosity of 50% and a pore size of 30 μm; the aluminum nanofiber layer accounts for 40 vol% of the volume of the functional current collector. The functional current collector provided in this embodiment is prepared through the following steps: S1. A precursor solution with a mass fraction of 12% PAN was prepared by dissolving polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF). The precursor solution was then deposited onto a receiving device by electrospinning deposition under the action of an electric field to obtain a fiber membrane with a cross-sectional diameter of 600 nm. During the electrospinning process, the voltage was 14 kV, the ambient humidity was 40%, and the receiving distance was 11 cm. S2. The fiber membrane is placed in an air atmosphere and heated to 200°C at a rate of 0.5°C / min and held for 4 hours to pre-oxidize the fiber membrane. Then, the pre-oxidized fiber membrane is placed in an argon atmosphere and heated to 600°C at a rate of 15°C / min and held for 5 hours to carbonize the fiber membrane to obtain a carbon fiber skeleton. S3. An ionic liquid was prepared by mixing AlCl3 and [EMIm]Cl at a molar ratio of 1.3:1 as an electrolyte. A carbon fiber skeleton was added to the electrolyte, and aluminum ions were reduced to aluminum metal atoms and deposited on the surface of the carbon fiber skeleton using an electrodeposition process to form an aluminum nanofiber layer, thus obtaining a functional current collector. During the electrodeposition process, the current density was 1 mA / cm². 2 The temperature was 70℃ and the deposition time was 50 min.

[0078] Comparative Example 5 A functional current collector includes a carbon fiber skeleton and an aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton; the carbon fiber skeleton has a porous honeycomb structure with a porosity of 85% and a pore size of 60 μm; the aluminum nanofiber layer accounts for 55% of the volume of the functional current collector. The functional current collector provided in this embodiment is prepared through the following steps: S1. A precursor solution with a mass fraction of 12% PAN was prepared by dissolving polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF). The precursor solution was then deposited onto a receiving device by electrospinning deposition under the action of an electric field to obtain a fiber membrane with a cross-sectional diameter of 1000 nm. During the electrospinning process, the voltage was 24 kV, the ambient humidity was 15%, and the receiving distance was 20 cm. S2. The fiber membrane is placed in an air atmosphere and heated to 350°C at a rate of 6°C / min and held for 0.5 hours to pre-oxidize the fiber membrane. Then, the pre-oxidized fiber membrane is placed in an argon atmosphere and heated to 1400°C at a rate of 2°C / min and held for 1 hour to carbonize the fiber membrane to obtain a carbon fiber skeleton. S3. An ionic liquid was prepared by mixing AlCl3 and [EMIm]Cl at a molar ratio of 1.1:1 as the electrolyte. A carbon fiber skeleton was added to the electrolyte, and aluminum ions were reduced to aluminum metal atoms and deposited on the surface of the carbon fiber skeleton using an electrodeposition process to form an aluminum nanofiber layer, thus obtaining a functional current collector. During the electrodeposition process, the current density was 10 mA / cm². 2 The temperature was 90℃ and the deposition time was 15 min.

[0079] Test case 1. Participants This test example uses the functional current collectors prepared in Examples 1-13 and Comparative Examples 1-5 as test objects to conduct relevant performance tests.

[0080] 2. Test Content (1) Surface density The surface density of a functional current collector is determined by measuring the mass of the functional current collector per unit area using a precision balance (accuracy 0.01 mg).

[0081] (2) Porosity The porosity of the functional current collector was measured using a mercury porosimeter (AutoPore V 9620).

[0082] (3) Surface resistance The surface resistance of the functional current collector was measured using a four-probe resistance meter (RTS-9).

[0083] (4) Cycle life of silicon anode A silicon anode was prepared by using silicon as the negative electrode active material to prepare a negative electrode slurry and coating it on the two surfaces of a functional current collector. The silicon anode was then assembled with a conventional positive electrode, separator, and electrolyte into a coin cell. The cell was charged and discharged at a rate of 0.5 C, and the cycle life of the silicon anode was characterized by the number of cycles when the capacity retention rate dropped to 80%.

[0084] (5) Limiting bending radius The prepared functional current collector samples were wound around cylinders of different diameters, and it was observed whether cracks or fractures appeared. The minimum bending radius without damage was taken as the ultimate bending radius, which was used to characterize the flexibility or bending resistance of the functional current collector. The smaller the ultimate bending radius, the better the flexibility or bending resistance of the functional current collector; conversely, the larger the ultimate bending radius, the worse the flexibility or bending resistance of the functional current collector.

[0085] 3. Experimental Results Table 1. Performance test results of functional current collectors and batteries using them.

[0086] The performance test results of the functional current collectors provided in Examples 1-13 and Comparative Example 1 and the batteries using them are shown in Table 1.

[0087] As shown in Table 1: Compared to Comparative Examples 1-5, the functional current collectors provided in Examples 1-13 exhibit lower areal density, superior pore structure, lower sheet resistance, longer cycle life, and smaller ultimate bending radius, indicating superior overall performance. They are better able to adapt to the volume expansion of high-capacity electrode materials, improving the cycle stability and rate performance of the battery. This demonstrates that the functional current collectors provided in this application exhibit excellent performance in terms of areal density, porosity, sheet resistance, silicon anode cycle life, and ultimate bending radius.

[0088] By comparing the data from Examples 1, 4, and 5, it can be seen that the voltage, ambient humidity, and receiving distance used in the electrospinning process of the fiber membrane all affect the areal density, porosity, sheet resistance, silicon anode cycle life, and ultimate bending radius of the final functional current collector.

[0089] By comparing the data from Examples 1, 6, 7, 8, and 9, it can be seen that during the preparation of the functional current collector, the heating rate and temperature during the fiber membrane pre-oxidation and carbonization processes all affect the sheet resistance, silicon anode cycle life, and ultimate bending radius of the final functional current collector. In the preparation of the carbon fiber skeleton, the fiber membrane is first placed in an air atmosphere and heated to 250-300°C at a rate of 1-5°C / min and held for 1-3 hours. Then, the pre-oxidized fiber membrane is placed in an argon atmosphere and heated to 800-1200°C at a rate of 5-10°C / min and held for 2-4 hours. This can reduce the sheet resistance of the final functional current collector and improve its flexibility and bending resistance.

[0090] Comparison of data from Examples 1, 10, and 11 shows that during the deposition of aluminum nanofiber layers on the surface of a carbon fiber skeleton using electrodeposition, controlling the temperature between 75 and 85°C and the current density between 3 and 7 mA / cm² is effective. 2 By controlling the deposition time between 25 and 35 minutes, the resulting functional current collector can possess good flexibility and bend resistance while maintaining a low surface resistivity.

[0091] Compared to Example 1, the functional current collectors provided in Examples 12-13 also include an electrolyte layer disposed on the surface of the aluminum nanofiber layer. Test results show that the flexibility and bending resistance of the functional current collectors in Examples 12-13 are better than those in Example 1.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention, but such modifications or substitutions are all within the scope of protection of the present invention.

Claims

1. A functional current collector, characterized in that: The functional current collector includes a carbon fiber skeleton and an aluminum nanofiber layer disposed on the surface of the carbon fiber skeleton. The carbon fiber skeleton has a porous structure with a porosity of 60-80% and a pore size of 5-50 μm.

2. The functional current collector as described in claim 1, characterized in that: The carbon fiber skeleton has a honeycomb structure.

3. The functional current collector as described in claim 1, characterized in that: The carbon fiber in the carbon fiber skeleton has a cross-sectional diameter of 750~850 nm, and / or the aluminum nanofiber in the aluminum nanofiber layer has a cross-sectional diameter of 50~200 nm.

4. The functional current collector as described in claim 1, characterized in that: The aluminum nanofiber layer contains aluminum whiskers, the length of which is 1~3 μm.

5. The functional current collector as described in claim 1, characterized in that: Let V1 be the total volume of the aluminum nanofiber layer and V2 be the total volume of the functional current collector. V1 and V2 satisfy the condition that 35% ≤ V1 / V2 ≤ 45%.

6. The functional current collector as described in claim 1, characterized in that: The functional current collector also includes an electrolyte layer, which is disposed on the surface of the aluminum nanofiber layer. The electrolyte layer includes polyvinylidene fluoride-hexafluoropropylene, and the mass percentage of polyvinylidene fluoride-hexafluoropropylene in the electrolyte layer is 81-95%.

7. The functional current collector as described in claim 6, characterized in that: The electrolyte layer also includes a lithium salt, wherein the lithium salt accounts for 5-19% of the mass of the electrolyte layer; The lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium tetrafluoroborate.

8. A method for preparing a functional current collector, characterized in that, Includes the following steps: S1. A precursor solution is deposited onto a receiving device by electrospinning to form a fiber membrane, wherein the precursor solution comprises a precursor, the precursor comprising at least one of polyacrylonitrile, polyimide, polyvinyl alcohol, and pitch. S2. The fiber membrane is subjected to carbonization treatment to form a carbon fiber skeleton with a porous structure, wherein the porosity of the carbon fiber skeleton is 60-80% and the pore size of the carbon fiber skeleton is 5-50 μm; S3. The carbon fiber skeleton is added to an electrolyte containing aluminum ions, and the aluminum ions are reduced to aluminum metal atoms by electrodeposition and deposited on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer, thereby obtaining the functional current collector.

9. The method for preparing the functional current collector as described in claim 8, characterized in that, S2 includes the following operations: pre-oxidizing the fiber membrane at 250~300°C, and carbonizing the pre-oxidized fiber membrane at 800~1200°C to obtain the carbon fiber skeleton. During the pre-oxidation process, the heating rate is controlled to be 1~5℃ / min; During the carbonization process, the heating rate is controlled to be 5~10℃ / min.

10. The method for preparing the functional current collector as described in claim 8, characterized in that: In step S1, the precursor solution further includes nano-carbon materials, the mass fraction of which is 0.1-1%, and the nano-carbon materials include at least one of carbon nanotubes, graphene nanoribbons, carbon nanofibers, and graphene.

11. The method for preparing the functional current collector as described in claim 8, characterized in that, In S1, the conditions for electrospinning are as follows: voltage 16~20 kV, ambient humidity 25~35%, and receiving distance 13~17 cm.

12. The method for preparing the functional current collector as described in claim 8, characterized in that: In S3, the electrolyte containing aluminum ions includes an ionic liquid, which is prepared by AlCl3 and imidazolium chloride in a molar ratio of (1.1~1.5):1, wherein the imidazolium chloride includes at least one of 1-ethyl-3-methylimidazolium chloride and 1-butyl-3-methylimidazolium chloride.

13. The method for preparing the functional current collector as described in claim 8, characterized in that: In step S3, the electrodeposition conditions are as follows: temperature 75~85℃, current density 3~7 mA / cm². 2 The deposition time is 25-35 minutes.

14. The method for preparing the functional current collector as described in claim 8, characterized in that: In step S3, after adding the carbon fiber skeleton to an electrolyte containing aluminum ions, reducing the aluminum ions to aluminum metal atoms by electrodeposition and depositing them on the surface of the carbon fiber skeleton to form an aluminum nanofiber layer, the step further includes coating the surface of the aluminum nanofiber layer with a polyvinylidene fluoride-hexafluoropropylene solution to form an electrolyte layer.

15. A battery, characterized in that: The battery includes the functional current collector as described in any one of claims 1 to 7 or the functional current collector prepared by the preparation method of the functional current collector as described in any one of claims 8 to 14.

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