Lithium metal batteries, lithium metal anodes, wrinkled graphene / carbon nanofiber composite films and their preparation methods
By preparing wrinkled graphene/carbon nanofiber composite films through electrospinning and spraying, the dendrite and interface problems of lithium metal anodes were solved, and efficient lithium deposition and long lifespan performance of lithium metal batteries were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TSINGHUA SHENZHEN INTERNATIONAL GRADUATE SCHOOL
- Filing Date
- 2023-07-17
- Publication Date
- 2026-05-26
AI Technical Summary
Lithium metal anodes suffer from dendrite growth, unstable interfacial reactions, and infinite volume changes, resulting in low coulombic efficiency, short cycle life, and high safety risks.
Polyacrylonitrile nanofiber membranes were prepared by electrospinning, and graphene oxide layers were formed on their surfaces by electrostatic spraying. Subsequently, pre-oxidation and carbonization treatments were performed to form wrinkled graphene/carbon nanofiber composite membranes, which were used as negative electrode current collectors for lithium metal batteries.
It effectively suppresses lithium dendrite formation, improves electrochemical and safety performance, and enhances the coulombic efficiency and cycle life of lithium metal batteries.
Smart Images
Figure CN116936724B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of lithium metal batteries, and more particularly to a lithium metal battery, a lithium metal anode, a wrinkled graphene / carbon nanofiber composite film, and a method for preparing the same. Background Technology
[0002] Lithium metal possesses high theoretical specific capacity and low electrochemical potential, making it an ideal anode material. When matched with different types of cathodes, lithium metal batteries, such as lithium-sulfur batteries and lithium-oxygen batteries, can achieve high energy densities. However, lithium metal anodes often suffer from a series of problems, including dendrite growth, unstable interface reactions, and infinite volume changes, leading to low coulombic efficiency, short cycle life, and potentially serious safety issues. Therefore, solving the dendrite and interface problems of lithium metal anodes is crucial for developing next-generation high-energy-density battery systems. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this application aims to provide a wrinkled graphene / carbon nanofiber composite film and its preparation method to improve the dendrite and interface problems of lithium metal anodes.
[0004] In addition, this application also provides a lithium metal anode comprising the above-mentioned wrinkled graphene / carbon nanofiber composite film, and a lithium metal battery comprising the lithium metal anode.
[0005] To achieve the above objectives, this application provides a method for preparing a wrinkled graphene / carbon nanofiber composite membrane, wherein the wrinkled graphene / carbon nanofiber composite membrane is used as a negative electrode current collector, and the preparation method includes the following steps:
[0006] Polyacrylonitrile nanofiber membranes were prepared by electrospinning using a mixed solution of polyacrylonitrile and silica as the electrospinning solution.
[0007] A graphene oxide dispersion was sprayed onto the surface of the polyacrylonitrile nanofiber membrane by electrostatic spraying to obtain a graphene oxide / polyacrylonitrile composite membrane.
[0008] The graphene oxide / polyacrylonitrile composite film is pre-oxidized.
[0009] The pre-oxidized graphene oxide / polyacrylonitrile composite film is subjected to carbonization treatment to obtain the wrinkled graphene / carbon nanofiber composite film.
[0010] In some possible embodiments, the mass fraction of polyacrylonitrile in the mixed solution of polyacrylonitrile and silica is 5 wt.% to 30 wt.%, and the mass ratio of polyacrylonitrile to silica is (5:1) to (20:1).
[0011] In some possible embodiments, the weight-average molecular weight of the polyacrylonitrile is 100,000 to 200,000; and the average diameter of the silica is 50 nm to 500 nm.
[0012] The method for preparing the mixed solution of polyacrylonitrile and silica includes:
[0013] A certain mass fraction of polyacrylonitrile and silicon dioxide are placed in a dimethylformamide solution, heated to 50℃~80℃, and stirred for 1h-5h.
[0014] In some possible embodiments, the mass concentration of graphene oxide in the graphene oxide dispersion is 0.1 mg / mL to 3 mg / mL; the dispersant in the graphene oxide dispersion is at least one of water or ethanol.
[0015] In some possible implementations, the voltage used in the electrospinning method is 10kV to 30kV, the receiving distance is 5cm to 20cm, and the flow rate of the electrospinning solution is 0.5mL / h to 2mL / h.
[0016] The voltage of the electrostatic spraying method is 10kV to 30kV, the receiving distance is 5cm to 20cm, and the flow rate of the graphene oxide dispersion is 1mL / h to 15mL / h.
[0017] In some possible embodiments, the pre-oxidation treatment step includes: heating the graphene oxide / polyacrylonitrile composite film in air to 200°C at a heating rate of 1°C / min to 5°C / min, and holding it at that temperature for 0.5 h; then heating it to 225°C at the same heating rate and holding it at that temperature for 0.5 h; and finally heating it to 250°C and holding it at that temperature for 1 h to 3 h.
[0018] In some possible implementations, the carbonization step includes:
[0019] The pre-oxidized graphene oxide / polyacrylonitrile composite film was heated to 600℃ to 1000℃ under an inert atmosphere at a heating rate of 1℃ / min to 10℃ / min, and held at that temperature for 1h to 5h.
[0020] This application also provides a wrinkled graphene / carbon nanofiber composite membrane prepared by the above preparation method.
[0021] This application also provides a lithium metal anode and a lithium metal battery comprising the above-mentioned wrinkled graphene / carbon nanofiber composite film.
[0022] This application prepares a polyacrylonitrile fiber membrane by electrospinning, forms a graphene oxide layer on the surface of the polyacrylonitrile nanofiber membrane by electrostatic spraying, and then obtains a wrinkled graphene / carbon nanofiber composite membrane with a self-supporting structure by pre-oxidation and carbonization treatment. When used as a negative electrode current collector, this composite membrane can effectively regulate lithium deposition, inhibit dendrite formation, and improve the electrochemical performance and safety performance of lithium metal negative electrodes. Attached Figure Description
[0023] Figure 1 This is a scanning electron microscope image of the carbon nanofiber membrane prepared in Comparative Example 1 of the present invention.
[0024] Figure 2 Figure a is a scanning electron microscope image of the wrinkled graphene / carbon nanofibers prepared in Example 1 of the present invention. Figure 2 Figure b is a scanning electron microscope image of the wrinkled graphene / carbon nanofibers prepared in Example 2 of the present invention. Figure 2 Figure c is a scanning electron microscope image of the wrinkled graphene / carbon nanofibers prepared in Example 3 of the present invention.
[0025] Figure 3 The batteries of Embodiment 1 and Comparative Example 1 of this invention are in a 1mAh cm⁻¹ range. -2 A comparison chart of the coulombic efficiencies of deep discharge.
[0026] Figure 4 Figure a shows the battery of Embodiment 1 of the present invention at 1 mA h cm. -2 Scanning electron microscope image of lithium deposition morphology after 50 cycles of deep discharge. Figure 4 Figure b shows the battery of Comparative Example 1 of the present invention at 1 mA h cm. -2 Scanning electron microscope image of lithium deposition morphology after 50 cycles of deep discharge. Detailed Implementation
[0027] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0028] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0029] One embodiment of this application provides a method for preparing a wrinkled graphene / carbon nanofiber composite membrane, wherein the wrinkled graphene / carbon nanofiber composite membrane is used as a negative electrode current collector, and the preparation method includes the following steps:
[0030] Polyacrylonitrile nanofiber membranes were prepared by electrospinning using a mixed solution of polyacrylonitrile and silica as the electrospinning solution.
[0031] A graphene oxide dispersion was electrostatically sprayed onto the surface of the polyacrylonitrile nanofiber membrane to prepare a graphene oxide / polyacrylonitrile composite membrane (GO / PAN).
[0032] The graphene oxide / polyacrylonitrile composite film is pre-oxidized.
[0033] The pre-oxidized graphene oxide / polyacrylonitrile composite film is subjected to carbonization treatment to obtain the wrinkled graphene / carbon nanofiber composite film.
[0034] This invention utilizes electrospinning to prepare polyacrylonitrile (PAN) nanofiber membranes with excellent flexibility by adding silica (SiO2) to the PAN membrane. Electrostatic spraying allows for the uniform deposition of graphene oxide (GO) on the PAN membrane surface, resulting in a flat and dense graphene oxide film. Subsequent oxidation and carbonization processes cause the planar graphene oxide film to wrinkle and form a dense reduced graphene oxide film due to the thermal shrinkage of the PAN nanofiber membrane, yielding a wrinkled graphene / carbon nanofiber composite membrane material. When used as a current collector in the negative electrode of a lithium metal battery, this wrinkled graphene membrane structure effectively regulates lithium deposition in the lithium metal negative electrode, partially releasing stress during the lithium deposition process, inhibiting lithium dendrite formation, and improving the electrochemical performance of the lithium metal battery. Furthermore, the carbon nanofiber structure beneath the wrinkles provides support, which is beneficial for lithium storage.
[0035] This preparation method is simple, highly operable, and low-cost. However, using conventional impregnation methods, where polyacrylonitrile (PA) films are immersed in graphene oxide dispersions, it's difficult for graphene oxide to spread uniformly and densely on the PA film surface. The distribution of the graphene oxide film on the PA film cannot be controlled, resulting in an uncontrollable structure. Furthermore, the impregnation process loosens the PA film structure, leading to an uncontrollable structure of the wrinkled graphene film after heat treatment. When used as a negative electrode current collector, lithium tends to deposit at the cross-linked nodes of carbon nanofibers. With increasing cycle count, a large number of lithium agglomerates form, further causing structural collapse and irreversible damage, resulting in poor cycle performance. Simultaneously using electrospun PA and electrostatically sprayed graphene oxide results in individual wrinkled agglomerates of graphene oxide particles, preventing proper film formation and failing to obtain a wrinkled reduced graphene oxide film. This also fails to effectively improve the lithium deposition and dendrite formation problems in lithium metal negative electrodes.
[0036] In some embodiments, the mass fraction of polyacrylonitrile in the mixed solution of polyacrylonitrile and silica is 5 wt.% to 30 wt.%, and the mass ratio of polyacrylonitrile to silica is (5:1) to (20:1).
[0037] In some embodiments, the weight-average molecular weight of the polyacrylonitrile is 100,000 to 200,000; and the average diameter of the silica is 50 nm to 500 nm.
[0038] The method for preparing the mixed solution of polyacrylonitrile and silica includes:
[0039] A certain mass fraction of polyacrylonitrile and silicon dioxide are placed in a dimethylformamide solution, heated to 50℃~80℃, and stirred for 1h-5h.
[0040] In some embodiments, the concentration of the graphene oxide dispersion is 0.1 mg / mL to 3 mg / mL.
[0041] The preparation method of the graphene oxide dispersion includes the following steps:
[0042] A certain amount of graphene oxide was dispersed in a mixed solvent of deionized water and anhydrous ethanol, stirred for 0.5 h to 1 h, and ultrasonically dispersed for 0.5 h to 2 h. The volume ratio of deionized water to anhydrous ethanol was (1:1) to (1:100).
[0043] In some embodiments, the voltage used in the electrospinning method is 10kV to 30kV, the receiving distance is 5cm to 20cm, and the flow rate of the electrospinning solution is 0.5mL / h to 2mL / h. The voltage used in the electrostatic spraying method is 10kV to 30kV, the receiving distance is 5cm to 20cm, and the flow rate of the graphene oxide dispersion is 1mL / h to 15mL / h.
[0044] In some embodiments, the pre-oxidation treatment step includes: heating the graphene oxide / polyacrylonitrile composite film in air to 200°C at a heating rate of 1°C / min to 5°C / min, and holding it at that temperature for 0.5 h; then heating it to 225°C at the same heating rate and holding it at that temperature for 0.5 h; and finally heating it to 250°C and holding it at that temperature for 1 h to 3 h.
[0045] By performing a pre-oxidation treatment, the linear PAN molecules undergo cyclization and dehydrogenation, transforming into a heat-resistant trapezoidal structure, thus maintaining the fiber's morphology and preventing combustion or melting during carbonization. This application employs a gradient-temperature pre-oxidation method. If the pre-oxidation starting temperature is too low (below 200℃), structural transformation cannot be achieved, and time and energy costs will increase. If the starting temperature is too high, the PAN fibers are prone to rapid exothermic reaction and melting. If the pre-oxidation process terminates at a temperature too high (above 250℃), over-oxidation will occur, while a termination temperature that is too low will lead to insufficient pre-oxidation. Generally, a reasonable pre-oxidation temperature range is 180℃-300℃. Furthermore, if the residence time is too short, the fiber structure after oxidation will be poor, making carbonization impossible. As the residence time increases, the fiber shrinkage rate also increases, and the fiber density and oxygen content increase, while the microcrystalline orientation decreases.
[0046] In some embodiments, the carbonization step includes:
[0047] The pre-oxidized graphene oxide / polyacrylonitrile composite film was heated to 600℃~1000℃ at a heating rate of 1℃ / min~10℃ / min under an inert atmosphere and held at that temperature for 1h~5h. The inert atmosphere was nitrogen, argon, or an argon / hydrogen (Ar / H2) mixture.
[0048] Graphene oxide (GO) is transformed into reduced graphene oxide (rGO) through carbonization, which improves its conductivity. Polyacrylonitrile (PAN) can be processed to obtain carbon nanofibers (CNF) with high crystal orientation, good electrical and thermal conductivity. Furthermore, due to the differences in the degree of thermal shrinkage of different carbon materials, a wrinkled morphology can be obtained after carbonization.
[0049] An embodiment of this application also provides a wrinkled graphene / carbon nanofiber composite membrane prepared by the above-described preparation method.
[0050] An embodiment of this application also provides a lithium metal anode, including the wrinkled graphene / carbon nanofiber composite film used as an anode current collector.
[0051] This application also provides a lithium metal battery, including the lithium metal negative electrode. The lithium metal battery may be a lithium-sulfur battery, a lithium-oxygen battery, etc.
[0052] The technical solutions in this application will be explained below with reference to specific embodiments and comparative examples. Those skilled in the art will understand that the following examples are for illustrative purposes only and should not be construed as limiting the invention. The main raw materials and equipment used in the specific embodiments and comparative examples are all conventional commercially available products or open-source materials.
[0053] Example 1
[0054] This embodiment provides a method for preparing a wrinkled graphene / carbon nanofiber composite membrane, including the following steps:
[0055] (1) Preparation of electrospinning solution
[0056] In this embodiment, powdered polyacrylonitrile (PAN, purchased from Sigma-Aldrich Chemical Company) with a weight average molecular weight of 150,000 g / mol and silica (SiO2) particles with an average diameter of 200 nm were used, with a mass ratio of PAN to SiO2 of 10:1.
[0057] First, weigh out a certain amount of PAN and SiO2, add them to a certain amount of dimethylformamide (DMF) solution, and then stir at 70℃ for 3 hours to completely dissolve the PAN and uniformly disperse the SiO2 nanoparticles, thus obtaining a dimethylformamide solution of polyacrylonitrile and silica with a mass fraction of 10 wt.% (denoted as PAN@SiO2 / DMF solution).
[0058] (2) Preparation of electrostatic spraying solution
[0059] A single-layer graphene oxide aqueous dispersion with a concentration of 10 mg / g (purchased from Hangzhou Gaoxi Technology Co., Ltd.) was used, and its concentration was diluted to 0.5 mg / mL with deionized water and anhydrous ethanol at a volume ratio of 1:3. The mixture was then stirred for 0.5 h and ultrasonically dispersed for 1 h to obtain the graphene oxide dispersion.
[0060] (3) Electrospinning
[0061] Take an appropriate amount of the PAN@SiO2 / DMF solution prepared in step (1) and place it in a syringe. Set the distance from the syringe nozzle to the receiver (spinning stroke / receiving distance) to 12cm, adjust the voltage to 25kV, and set the syringe advance speed (spinning speed / flow rate of the electrospinning solution) to 1mL / h. After electrospinning for 3h, a polyacrylonitrile nanofiber membrane is obtained.
[0062] (4) Electrostatic spraying
[0063] Take the graphene oxide dispersion prepared in step (2) and place it in a syringe. Set the same receiving distance and voltage as in step (3). Set the flow rate of the graphene oxide dispersion to 10 mL / h. Spray the graphene oxide dispersion onto the polyacrylonitrile nanofiber membrane. After the solvent evaporates, obtain the graphene oxide / polyacrylonitrile nanofiber (GO / PAN) composite membrane material. The duration of this spraying step is 3 hours.
[0064] (5) Pre-oxidation treatment
[0065] The GO / PAN composite film material obtained in step (4) was heated from room temperature to 200°C in air at a heating rate of 5°C / min, held at that temperature for 0.5h, then heated to 225°C at the same heating rate, held at that temperature for 0.5h, and finally heated to 250°C, held at that temperature for 1h, and then removed after cooling in the furnace.
[0066] (6) Carbonization treatment
[0067] The composite membrane material obtained after pre-oxidation treatment in step (5) is carbonized in a tube furnace. Under an argon atmosphere, the temperature is gradually increased from room temperature to 600℃ at a heating rate of 5℃ / min, held at the temperature for 2 hours, and then cooled to room temperature to obtain a wrinkled graphene / carbon nanofiber (rGO / CNF) composite membrane.
[0068] Example 2
[0069] The difference between this embodiment and Embodiment 1 is that the carbonization temperature in step (6) is 800°C. The other steps are the same as in Embodiment 1 and will not be repeated here.
[0070] Example 3
[0071] The difference between this embodiment and Embodiment 1 is that the carbonization temperature in step (6) is 1000℃. The other steps are the same as in Embodiment 1 and will not be repeated here.
[0072] Comparative Example 1
[0073] (1) Prepare the electrospinning solution. This step is the same as step (1) in Example 1.
[0074] (2) Electrospinning. This step is the same as step (3) in Example 1.
[0075] (3) Pre-oxidation treatment. The polyacrylonitrile nanofiber membrane obtained in step (2) is oxidized in air. First, the temperature is increased from room temperature to 200℃ at a heating rate of 5℃ / min and held for 0.5h. Then, the temperature is increased to 225℃ at the same heating rate and held for 0.5h. Finally, the temperature is increased to 250℃ and held for 1h. After cooling in the furnace, the membrane is removed.
[0076] (4) Carbonization treatment. The PAN membrane material obtained after the pre-oxidation treatment in step (3) is carbonized in a tube furnace. Under an argon atmosphere, the temperature is gradually increased from room temperature to 600℃ at a heating rate of 5℃ / min, held at the temperature for 2 hours, and then cooled to room temperature to obtain carbon nanofiber (CNF) membrane material.
[0077] Compared with Example 1, Comparative Example 1 only prepared carbon nanofiber membranes without wrinkled graphene layers.
[0078] Figure 1 Here is a scanning electron microscope image of the pure CNF film material prepared in Comparative Example 1, as shown. Figure 1 As shown, the CNF film material is made of disordered carbon nanofibers with a diameter of about 100 nm. The protruding structure on the carbon nanofibers is caused by SiO2 particles embedded in them.
[0079] The wrinkled rGO / CNF composite films prepared in Examples 1-3 were tested by scanning electron microscopy (SEM), and the test results are as follows: Figure 2 Figure a Figure 2 The b-image and Figure 2 As shown in Figure c, it can be seen that one side of the carbonized rGO / CNF composite film exhibits obvious wrinkles, and the degree of wrinkling increases with the increase of carbonization temperature.
[0080] The wrinkled rGO / CNF composite membrane obtained in Example 1 and the carbon nanofiber membrane in Comparative Example 1 were used as negative electrode current collectors and assembled into a coin cell for electrochemical performance testing. The specific method is as follows: A negative electrode shell, spring sheet, gasket, lithium sheet, 50 μL electrolyte, separator, and positive electrode shell were provided. The prepared wrinkled rGO / CNF composite membrane and carbon nanofiber membrane were respectively punched into electrode sheets with a diameter of 12 mm. A lithium metal sheet was used as the counter electrode, and a polypropylene microporous membrane (Celgard 2400) was used as the separator. The electrolyte was 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) solvents in a volume ratio of 1:1, and 1% LiNO3. A 2032 type coin cell was assembled in a glove box filled with high-purity argon. The coulombic efficiency of the above half cell was tested at room temperature using the Land battery testing system. First, 1 mA cm⁻¹ was used as the starting point. -2 The charging current is used for charging, and the lithium intercalation capacity is fixed at 1mAh / cm³.-2 Subsequently, during the discharge process, lithium was delithiated to 0.5V at the same current density.
[0081] See Figure 3 The lithium anode obtained according to the above steps in Example 1 exhibited better cycle stability in the coulombic efficiency test, maintaining a coulombic efficiency of over 98% after 200 cycles. In contrast, the 2032 coin cell prepared in Comparative Example 1 showed better cycle stability in a 1mAh cm⁻¹ mAh solution. -2 After 80 deep discharge cycles at a current density, the coulombic efficiency drops below 90%, and the coulombic efficiency fluctuates significantly during the cycle.
[0082] See Figure 4 Figure b shows that in Comparative Example 1, the carbon nanofiber membrane without a graphene layer exhibited a large amount of lithium agglomerates after 50 cycles, and its structure was somewhat damaged. However... Figure 4 In Figure a, the wrinkled graphene layer of Example 1 can achieve dense and smooth lithium deposition after 50 cycles, and there is almost no dead lithium residue on the electrode surface, indicating that the wrinkled graphene layer can effectively suppress the formation of lithium dendrites and achieve excellent electrochemical performance.
[0083] Furthermore, electrochemical tests were performed on the wrinkled rGO / CNF composite membrane materials prepared in Examples 1-3 and Comparative Example 1, respectively. The specific test methods were the same as in Example 1, and the test results are shown in Table 1.
[0084] Table 1. Electrochemical test results of Examples 1-3 and Comparative Example 1 of the present invention.
[0085]
[0086] As shown in Table 1, compared to Comparative Example 1, the battery using the modified wrinkled material as the negative electrode current collector exhibits higher and more stable coulombic efficiency and longer cycle life. Therefore, designing rGO / CNF materials with wrinkled morphology can effectively suppress the formation and growth of negative electrode dendrites, thereby achieving better electrochemical performance.
[0087] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention should not depart from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a wrinkled graphene / carbon nanofiber composite membrane, characterized in that, The wrinkled graphene / carbon nanofiber composite film is used as a negative electrode current collector, and the preparation method includes the following steps: Polyacrylonitrile nanofiber membranes were prepared by electrospinning using a mixed solution of polyacrylonitrile and silica as the electrospinning solution. A graphene oxide dispersion was sprayed onto the surface of the polyacrylonitrile nanofiber membrane by electrostatic spraying to obtain a graphene oxide / polyacrylonitrile composite membrane. The graphene oxide / polyacrylonitrile composite film is pre-oxidized. The pre-oxidized graphene oxide / polyacrylonitrile composite film is subjected to carbonization treatment to obtain the wrinkled graphene / carbon nanofiber composite film.
2. The preparation method according to claim 1, characterized in that, The mass fraction of polyacrylonitrile in the mixed solution of polyacrylonitrile and silica is 5 wt.% to 30 wt.%, and the mass ratio of polyacrylonitrile to silica is (5:1) to (20:1).
3. The preparation method according to claim 2, characterized in that, The polyacrylonitrile has a weight-average molecular weight of 100,000 to 200,000; the silica has an average diameter of 50 nm to 500 nm. The method for preparing the mixed solution of polyacrylonitrile and silica includes: A certain mass fraction of polyacrylonitrile and silicon dioxide are placed in a dimethylformamide solution, heated to 50℃~80℃, and stirred for 1h-5h.
4. The preparation method according to claim 1, characterized in that, The graphene oxide dispersion has a mass concentration of 0.1 mg / mL to 3 mg / mL; the dispersant in the graphene oxide dispersion is at least one of water or ethanol.
5. The preparation method according to claim 1, characterized in that, The electrospinning method uses a voltage of 10kV to 30kV, a receiving distance of 5cm to 20cm, and a flow rate of 0.5mL / h to 2mL / h. The voltage of the electrostatic spraying method is 10kV to 30kV, the receiving distance is 5cm to 20cm, and the flow rate of the graphene oxide dispersion is 1mL / h to 15mL / h.
6. The preparation method according to claim 1, characterized in that, The pre-oxidation treatment step includes: heating the graphene oxide / polyacrylonitrile composite film in air to 200°C at a heating rate of 1°C / min to 5°C / min, and holding it at that temperature for 0.5 h; then heating it to 225°C at the same heating rate and holding it at that temperature for 0.5 h; and finally heating it to 250°C and holding it at that temperature for 1 h to 3 h.
7. The preparation method according to claim 1, characterized in that, The carbonization process includes: The pre-oxidized graphene oxide / polyacrylonitrile composite film was heated to 600℃ to 1000℃ under an inert atmosphere at a heating rate of 1℃ / min to 10℃ / min, and held at that temperature for 1h to 5h.
8. A wrinkled graphene / carbon nanofiber composite membrane, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.
9. A lithium metal anode, characterized in that, Including the wrinkled graphene / carbon nanofiber composite membrane as described in claim 8.
10. A lithium metal battery, characterized in that, Including the lithium metal anode as described in claim 9.