Modified graphitized membrane material as well as preparation method and application thereof

Abstract

The invention relates to a modified graphitized membrane material as well as a preparation method and application thereof. The modified graphitized membrane material comprises a graphitized material, a modifier and a structure enhancer. When the modified graphitized membrane material is used as a current collector of a metal lithium composite electrode in a lithium battery, lithium atoms in metal lithium or lithium alloy foil compounded on the surface of the modified graphitized membrane material are diffused into the modified graphitized membrane material to form a lithium storage supplement layer. And at the later stage of battery reaction, when the active metal lithium almost disappears, the lithium storage supplementing layer starts to play a role, so that the cycle life of the battery is prolonged by more than 10%.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, and in particular to modified graphitized film materials for lithium secondary batteries. Background Technology

[0002] As society demands increasingly higher energy density from lithium-ion batteries, current research focuses on anode materials with higher specific capacity. Lithium metal, with its capacity of 3860 mAh / g and low potential of -3.04V, is considered the optimal anode material. Currently, lithium metal strips or lithium-copper composite strips are used as anode materials, with ternary cathode materials. However, after about 100 cycles, the capacity decays to below 80%, far from practical application. When lithium metal is used as an anode, capacity decays rapidly after about 100 cycles due to lithium pulverization and the formation of dead lithium, posing safety risks. Therefore, there is a ongoing search for materials that can assist in later cycles of lithium metal and extend the battery's cycle life in the later stages of lithium metal anode cycling. Summary of the Invention

[0003] To address the aforementioned problems, the inventors, through in-depth and meticulous research, discovered a modified graphitized film material that, when combined with metallic lithium, can form a lithium storage replenishment layer. This lithium storage replenishment layer can extend the battery's cycle life in the later stages of battery cycling.

[0004] Specifically, one aspect of the present invention relates to a modified graphitized film material comprising a graphitized material, a modifier, and a structural reinforcing agent, wherein the graphitized material comprises at least one of graphite, graphitized organic polymers, and graphene; the modifier comprises at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers; and the structural reinforcing agent comprises at least one of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, and polyacrylic acid.

[0005] According to some embodiments, the organic polymer includes polyimide or polyacrylonitrile.

[0006] According to some embodiments, the modified graphitized film is a film made of graphite or graphitized organic polymers, modifiers and structural reinforcing agents, or a film made of graphene, modifiers and structural reinforcing agents obtained by graphitization treatment.

[0007] According to some embodiments, in the modified graphitized film, the modifier accounts for 0.1%-10% by mass, and the structural reinforcing agent accounts for 0.1%-10% by mass. Preferably, the modifier accounts for 0.5%-5% by mass, and the structural reinforcing agent accounts for 0.5%-5% by mass.

[0008] According to some embodiments, the sheet resistance of the modified graphitized film is 0.1-100 mΩ / cm. 2 The membrane material thickness is 5-25μm, and the membrane density is 1.3-2.0g / cm³. 3 The tensile strength of the membrane material is 15-100MPa.

[0009] Another aspect of the present invention provides a method for preparing the above-mentioned modified graphitized film material, the method comprising the following steps:

[0010] A modified graphitized film is obtained by mixing graphite or graphitized organic polymer, a modifier, a structural reinforcing agent, and a small amount of solvent into a homogeneous material, followed by calendering. The modifier and structural reinforcing agent each account for 0.1%-10% by mass, and the solvent accounts for less than 3% by mass.

[0011] Alternatively, the graphene oxide slurry is mixed with a modifier and a structural reinforcing agent, with each modifier and structural reinforcing agent accounting for 0.1%-10% by mass. The slurry is then coated onto a release film and dried to obtain a graphene oxide film. After drying, the film is reduced to obtain a reduced graphene film, which is then subjected to a high-temperature graphitization treatment at 2300-3000℃ for 0.5-2 hours to obtain a modified graphitized film material.

[0012] According to some embodiments, the graphitized organic polymer is obtained by carbonizing an organic polymer selected from polyimide polymers or polyacrylonitrile polymers at 1200-1500°C for 1-2 hours, followed by graphitization at 2300-3000°C for 0.5-2 hours.

[0013] According to some embodiments, the graphite is acid-treated, washed with water until neutral, and then mixed with a modifier, a structural reinforcing agent, and a small amount of solvent.

[0014] According to some embodiments, the small amount of solvent includes at least one of N-methylpyrrolidone, n-hexane, and water.

[0015] According to some embodiments, the release film is a polyethylene terephthalate / polypropylene / polyethylene plastic film with a surface (the bonding surface of the graphitized film material) treated with a silicone oil coating.

[0016] According to some implementation methods, the reducing agent used for reduction includes hydrazine hydrate or vitamin C.

[0017] Another aspect of the present invention provides the use of the above-described modified graphitized film material as a current collector for a lithium metal composite electrode in a lithium battery.

[0018] According to some embodiments, the lithium metal composite electrode includes: a modified graphitized film material as a current collector; an active material layer composited on at least one surface of the modified graphitized film material, the active material layer being a continuous or intermittently distributed lithium metal or lithium alloy foil; and a lithium storage replenishment layer formed by lithium atoms diffusing into the modified graphitized film material via hot-pressing composite.

[0019] According to some embodiments, the thickness of the lithium storage replenishment layer is 2-25 μm, preferably 3-20 μm, and more preferably 5-15 μm.

[0020] According to some embodiments, the thickness of the lithium metal or lithium alloy foil is 1-100 μm, preferably 1-20 μm; and the width is 50-1400 mm, preferably 200-700 mm.

[0021] According to some embodiments, the lithium alloy foil is a foil material formed by combining metallic lithium with any one or at least two elements selected from Ag, Au, Sn, Si, Zn, Al, Mg, In, Ga, B, Mn, Sb, Cr, C, V, Cu, Fe, or Ti.

[0022] According to some embodiments, both sides of the modified graphitized film are coated with an active material layer.

[0023] According to certain embodiments, the lithium metal composite electrode is prepared by the following method, which includes the following steps:

[0024] Step 1: Prepare the modified graphitized film material, and roll it up together with one side of the release film;

[0025] Step 2: Unwind the lithium metal / lithium alloy foil and the modified graphitized film. Then, perform low-pressure bonding of the modified graphitized film with the side of the lithium metal / lithium alloy foil facing the side of the film without the release film attached. The pressure is set to 1-2 MPa. Remove the release film to obtain a single-sided lithium composite negative electrode.

[0026] Step 3: Unwind another roll of lithium metal / lithium alloy foil, and pressure bond the side of the single-sided composite negative electrode without composite lithium to the unwound lithium metal / lithium alloy foil. The pressure is set to 3-5 MPa to obtain a preliminary double-sided lithium composite negative electrode.

[0027] Step 4: The preliminary double-sided lithium composite anode is rolled by hot rollers. The temperature of the hot rollers is 40-60℃ and the pressure is set to 1-2MPa to obtain the lithium composite anode.

[0028] According to some embodiments, the release film is a PET (polyethylene terephthalate) / PP (polypropylene) / PE (polyethylene) plastic film with a surface (the bonding surface of the graphitized film material) coated with silicone oil.

[0029] According to some embodiments, the lithium composite electrode is used directly as the negative electrode of a liquid or solid lithium battery.

[0030] According to certain implementation methods, the positive electrode of a lithium battery may use lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich manganese-based positive electrode material, lithium iron phosphate, lithium manganese iron phosphate, sulfur-carbon positive electrode, sulfurized polyacrylonitrile, or lithium cobalt oxide, etc.

[0031] According to some embodiments, the lithium battery is a liquid lithium-ion battery or a solid lithium-ion battery.

[0032] According to certain implementation methods, the electrolyte of a lithium battery can be a liquid electrolyte or a solid electrolyte; the liquid electrolyte can be an ester or an ether; the solid electrolyte can be an inorganic solid electrolyte, such as an oxide solid electrolyte, a halide solid electrolyte, or a sulfide solid electrolyte; the solid electrolyte can also be a polymer electrolyte (polyethylene oxide, polysiloxane, polyacrylonitrile, polyvinylidene fluoride, etc.) or an electrolyte that is a mixture of polymer electrolyte and inorganic solid electrolyte, such as a polyethylene oxide mixed with an oxide, halide, or sulfide electrolyte.

[0033] According to some implementation methods, the separator of the liquid battery is made of PP, PE or a three-layer composite separator of PP and PE, and the separator may be coated with ceramic, PVDF (polyvinylidene fluoride), boehmite or inorganic solid electrolyte powder.

[0034] According to certain implementation methods, batteries can be configured as square, pouch, or cylindrical batteries.

[0035] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0036] 1. The modified graphitized film material of the present invention comprises graphitized materials, modifiers, and structural reinforcing agents. The modifiers (single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers) possess lithium conductivity. After modification with the modifiers, lithium atoms can more easily insert into the interlayer gaps of graphite or the gaps between graphene layers, thereby facilitating the formation of a lithium storage replenishment layer. Furthermore, the modifiers and structural reinforcing agents (polytetrafluoroethylene, polyvinylidene fluoride, etc.) can make the mixed material easier to form a film and improve the mechanical strength of the film material, facilitating large-scale production in rolls.

[0037] 2. The lithium storage replenishment layer formed between the lithium metal / lithium alloy and the modified graphitized film plays a role in the later stages of battery cycling in cells with lithium metal / lithium alloy as the negative electrode active material, improving the cycle performance of the cell and increasing the cycle life by more than 10%.

[0038] 3. Graphitized film materials are lightweight and have high tensile strength, and can be used in large quantities in rolls to prepare lithium composite anodes, meeting the demand for high specific energy and lightweight anodes. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the lithium recombination reaction mechanism at the negative electrode during battery cycling.

[0040] 1-Lithium metal foil / lithium alloy foil, 1'-Powdered lithium in the later stage of the reaction (with low activity in the reaction), 2-Lithium storage replenishment layer, 3-Modified graphitized film material

[0041] Figure 2 Cyclic test curves of lithium-ion batteries using lithium composite negative electrodes from Comparative Examples 1, 2, 3, 1, 2, 3, and 4 are shown.

[0042] Figure 3 Time-voltage data graph for assembling coin cells with lithium storage supplementary layer material;

[0043] Figure 4 Time-voltage data graph for assembling coin cells without lithium storage supplemental layer material. Detailed Implementation

[0044] To facilitate understanding of this application, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of this application.

[0045] Example 1

[0046] Preparation of modified graphitized film materials:

[0047] Flake graphite powder was oxidized with concentrated sulfuric acid, the product was washed with water until neutral, and dried at low temperature to obtain product A. Product A, single-walled carbon nanotubes, and polyvinylidene fluoride resin were mixed at a mass ratio of 97.5:

[0048] Mix in a 1.5:1 ratio, add trace amounts of 1-methyl-2-pyrrolidone solvent, knead until uniform, and use a roller press with a pressure set to 3 MPa to prepare a graphitized film with a thickness of 20 μm. One side is bonded to a release film and rolled up together. The tensile strength of the film is 16.5 MPa.

[0049] Preparation of lithium composite anode:

[0050] The active material is a 20μm thick lithium foil in roll. A roll of lithium foil and the 20μm thick graphitized film prepared above are unwound and rolled together. Using a roller press, the pressure is set to 2MPa to obtain a preliminary single-sided lithium composite anode.

[0051] Another 20μm thick lithium foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0052] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 2 MPa, a temperature of 50°C, and a rolling speed of 30 m / min to obtain lithium composite anode 1 (with a lithium storage replenishment layer thickness of 5 μm) for use in batteries.

[0053] Example 2

[0054] Preparation of modified graphitized film materials:

[0055] First, a polyimide polymer was synthesized. The polyimide was then carbonized at 1300℃ for 1 hour, followed by graphitization at 2600℃ for 1 hour to obtain the graphitized product (B). Product B, multi-walled carbon nanotubes, and polytetrafluoroethylene (powder, particle size less than 12μm, Aladdin) were mixed in a mass ratio of 97.5:1:1.5. A trace amount of 1-methyl-2-pyrrolidone was added and mixed evenly. A 17μm thick film was prepared using a roller press with a pressure of 5MPa. The film was then rolled up together with a PET plastic film coated with a thin layer of silicone oil to obtain a rolled graphitized film with a tensile strength of 20.1MPa.

[0056] Preparation of lithium composite anode:

[0057] The active material is a 20μm thick lithium foil in roll. A roll of lithium foil and a 17μm thick graphitized film prepared above are unwound and rolled together. Using a roller press with a pressure of 1MPa, a preliminary single-sided lithium composite anode is obtained.

[0058] Another 20μm thick lithium foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0059] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 1 MPa, a temperature of 50°C, and a rolling speed of 30 m / min to obtain lithium composite anode 2 (with a lithium storage supplement layer thickness of 10 μm) for use in batteries.

[0060] Example 3

[0061] The graphitized film material modified in Example 3 is the same as that in Example 2.

[0062] The 20μm thick lithium foil in Example 2 was replaced with a 20μm thick lithium-magnesium alloy foil (magnesium content of 5%). A roll of lithium-magnesium alloy foil and the 17μm thick graphitized film prepared above were unwound and rolled up. Using a roller press with the pressure set to 2MPa, a preliminary single-sided lithium composite anode was obtained.

[0063] Another 20μm thick lithium-magnesium alloy foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0064] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 1 MPa, a temperature of 45°C, and a rolling speed of 30 m / min to obtain lithium composite anode 3 (with a lithium storage supplement layer thickness of 10 μm) for use in batteries.

[0065] Example 4

[0066] Preparation of modified graphitized film: A 5% solid content graphene oxide oily slurry was used, followed by a 0.4% solid content single-walled carbon nanotube slurry, and finally a 0.5% polyvinylidene fluoride slurry. The three were mixed thoroughly, with a graphene:single-walled carbon nanotube:polyvinylidene fluoride mass ratio of 98:1:1. The new slurry was applied to a PET plastic film coated with a thin silicone oil layer using a 250μm doctor blade, and then dried at 45 degrees Celsius for 10 hours to form a pre-dried graphene oxide film. The graphene oxide film was then transferred from the PET film... The ET plastic film is peeled off to obtain a self-supporting graphene oxide film. The graphene oxide film is then placed in a vitamin C solution (0.5 mol / L) for reduction at 80℃ for 24 hours to obtain a reduced graphene film. The reduced graphene film is further compacted under the protection of upper and lower film materials to obtain a shaped graphene film. The rolled graphene film is then subjected to a high-temperature treatment at 2500℃ for 30 minutes to obtain a graphitized film with a thickness of 12 μm and a tensile strength of 23.5 MPa.

[0067] Preparation of lithium composite anode:

[0068] The active material is a 20μm thick lithium foil in roll. A roll of lithium foil and a 12μm thick graphitized film prepared above are unwound and rolled together. Using a roller press, the pressure is set to 1.5MPa to obtain a preliminary single-sided lithium composite anode.

[0069] Another 20μm thick lithium foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0070] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 1 MPa, a temperature of 45°C, and a rolling speed of 40 m / min to obtain lithium composite anode 4 (with a lithium storage replenishment layer thickness of 7.5 μm) for use in batteries.

[0071] Comparative Example 1

[0072] The active material is a 20μm thick lithium foil in rolls. Two rolls of lithium foil and a 6μm thick copper foil are unwound and rolled up. The pressure is set to 3MPa using a roller press to obtain the lithium composite negative electrode 5.

[0073] Comparative Example 2

[0074] Preparation of ungraphitized membrane material: First, a polyimide polymer was synthesized, and the polyimide was carbonized at 1300℃ for 1 hour to obtain an ungraphitized product (B). Product B, multi-walled carbon nanotubes, and polytetrafluoroethylene (powder, particle size less than 12μm, Aladdin) were mixed in a mass ratio of 97.5:1:1.5. A trace amount of 1-methyl-2-pyrrolidone was added and mixed evenly. A membrane material with a thickness of 17μm was prepared by using a roller press with a pressure of 5MPa. The membrane material was then rolled up together with a PET plastic film with a thin silicone oil coating to obtain a rolled membrane material. The tensile strength of the membrane material was 18.6MPa.

[0075] The active material is a 20µm thick lithium foil in roll. A roll of lithium foil and a 17µm thick ungraphitized film prepared above are unwound and rolled together. Using a roller press, the pressure is set to 1.5MPa to obtain a preliminary single-sided lithium composite anode.

[0076] Another 20μm thick lithium foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0077] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 1 MPa, a temperature of 50°C, and a rolling speed of 30 m / min to obtain the lithium composite anode 6 to be used in the battery.

[0078] Comparative Example 3

[0079] Preparation of graphitized membrane: First, a polyimide polymer is synthesized. The polyimide is then carbonized at 1300℃ for 1 hour, followed by graphitization at 2600℃ for 1 hour to obtain the graphitized product (B). Product B and polytetrafluoroethylene (powder, particle size less than 12μm, Aladdin) are mixed at a mass ratio of 98.5:1.5. A trace amount of 1-methyl-2-pyrrolidone is added and mixed evenly. A membrane with a thickness of 17μm and a tensile strength of 17.8MPa is prepared by using a roller press with a pressure of 5MPa.

[0080] The active material is a 20µm thick lithium foil in roll. A roll of lithium foil and a 17µm thick film prepared above are unwound and rolled up. Using a roller press, the pressure is set to 1MPa to obtain a preliminary single-sided lithium composite anode.

[0081] Another 20μm thick lithium foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0082] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 1 MPa, a temperature of 50°C, and a rolling speed of 30 m / min to obtain lithium composite anode 7 (with a lithium storage replenishment layer thickness of 1.5 μm) for use in batteries.

[0083] The lithium composite anode 1 of Example 1, the lithium composite anode 2 of Example 2, the lithium composite anode 3 of Example 3, the lithium composite anode 4 of Example 4, the lithium composite anode 5 of Comparative Example 1, the lithium composite anode 6 of Comparative Example 2, and the lithium composite anode 7 of Comparative Example 3 were used as anodes. The cathode was a lithium nickel cobalt manganese oxide cathode (cathode areal density of 38.5 mg / cm³). 2 The separator is a single-sided ceramic PE membrane with a thickness of 14μm. A soft-pack battery is assembled using a liquid ether electrolyte. The charge / discharge rate is 0.2C, and the test voltage range is 2.7-4.35V. The electrochemical performance of the seven groups is as follows: Figure 1 As shown.

[0084] Through electrochemical cycle diagram ( Figure 2 As can be seen, the lithium composite anodes 1, 2, 3, and 4 of Examples 1, 2, 3, and 4 exhibit better cycle performance than the lithium composite anodes 5, 6, and 7 of Comparative Examples 1, 2, and 3. The lithium composite anodes of Examples 1, 2, 3, and 4 show rapid capacity decay after 100 to 150 cycles, at which point the lithium storage replenishment layer begins to function. Battery capacity increases after 150 to 200 cycles, extending the cycle life of the four cells in these examples by more than 50 cycles. In contrast, lithium composite product 5 in Comparative Example 1 lacks a lithium storage layer due to its copper layer; lithium composite product 6 in Comparative Example 2 lacks a lithium storage layer due to its non-graphitized film material, resulting in a linear capacity decay after approximately 150 cycles; and in Comparative Example 3, the lithium storage replenishment layer is too thin (1.5 μm thick), failing to replenish battery capacity in the later stages of cycling, leading to rapid capacity decay after 140 cycles.

[0085] A comparison of the data from Examples 2 and 3 shows that the active material of the lithium composite anode 3 in Example 3 is lithium-magnesium alloy foil. Due to the presence of magnesium, it is beneficial to the uniform deposition of metallic lithium, resulting in slightly better electrochemical performance.

[0086] Test method for lithium replenishment layer thickness: When the cell has cycled 140 times, disassemble the discharged cell in an argon glove box, remove the negative electrode, peel off the powdery lithium and dead lithium on the surface of the negative electrode, rinse the electrode surface with electrolyte, leaving only the graphitized film and lithium replenishment layer, and assemble it into a disc with an inner diameter of 14mm. With the side of the lithium replenishment layer facing the separator, use the metallic lithium disc as the counter electrode, inject electrolyte, assemble into a button cell, and test. The test procedure is as follows:

[0087] 1. Let it sit for 12 hours

[0088] 2. Constant current charging current 3.08mA, voltage 2V

[0089] 3. End

[0090] The cells in Examples 1, 2, 3, 4, Comparative Example 2, and Comparative Example 3 were all tested according to the above-described test method for lithium storage replenishment layers. The charging data for Examples 1, 2, 3, 4, and Comparative Example 3 are shown below. Figure 3 After being left to stand for 12 hours, the battery was charged at a constant current of 3.08 mA, and the battery voltage increased from 0.008V to 2V. All the lithium in the lithium storage replenishment layer was transferred to the negative electrode. The capacity of the lithium storage replenishment layer in the corresponding embodiment is shown in Table 1 below. The charging data for Comparative Example 2 is shown below. Figure 4 In Comparative Example 2, since there was no lithium storage replenishment layer, after 12 hours of rest, the battery voltage remained at around 1.56V. When charged with a constant current of 3.08mA, the battery voltage suddenly changed from 1.56V to nearly 4V, and the released capacity was 0. This indicates that the membrane material in Comparative Example 2 was not graphitized and no lithium storage replenishment layer was formed.

[0091] In Comparative Example 3, because there are no transport channels for carbon nanotubes or carbon fibers, metallic lithium cannot easily enter the interlayer of graphitization, so the thickness of the lithium storage supplement layer is only 1.5 μm, which is relatively thin.

[0092] Note: The capacity of the lithium storage replenishment layer = 3.08mA (set current) × Figure 3 / Figure 4 The horizontal axis represents time, thus yielding the capacity of the lithium storage replenishment layer in Table 1.

[0093] The area of ​​the electrode is 1.54 cm². 2 Thus, the areal capacity of Example 1 / Example 2 / Example 3 / Example 4 / Comparative Example 2 / Comparative Example 3 can be calculated, and the approximate thickness of the lithium storage replenishment layer can be deduced.

[0094] Table 1. Charging capacity of the assembled coin cell lithium storage supplementary layer during testing

[0095]

[0096] The applicant declares that this application illustrates its detailed structural features through the above embodiments, but this application is not limited to the above detailed structural features, that is, it does not mean that this application must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent substitutions of the components selected in this application, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this application.

Claims

1. A modified graphitized film material, characterized in that, The modified graphitized film material comprises graphitizing materials, modifiers, and structural reinforcing agents. The graphitized material includes at least one of graphite, graphitized organic polymers, and graphene. The modifier includes at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers. The structural reinforcing agent includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, and polyacrylic acid.

2. The modified graphitized film material according to claim 1, characterized in that, The organic polymer includes polyimide or polyacrylonitrile.

3. The modified graphitized film material according to claim 1, characterized in that, The modified graphitized membrane material is a membrane material made of graphite or graphitized organic polymers, modifiers and structural reinforcing agents, or a membrane material made of graphene, modifiers and structural reinforcing agents obtained by graphitization treatment.

4. The modified graphitized film material according to claim 1, characterized in that, In the modified graphitized film, the modifier accounts for 0.1%-10% by mass, and the structural reinforcing agent accounts for 0.1%-10% by mass.

5. The modified graphitized film material according to claim 1, characterized in that, The sheet resistance of the modified graphitized film is 0.1-100 mΩ / cm. 2 The membrane material thickness is 5-25μm, and the membrane density is 1.3-2.0g / cm³. 3 The tensile strength of the membrane material is 15-100MPa.

6. A method for preparing a modified graphitized film material according to any one of claims 1 to 5, characterized in that, The method includes: A modified graphitized film is obtained by mixing graphite or graphitized organic polymer, a modifier, a structural reinforcing agent, and a small amount of solvent into a homogeneous material, followed by calendering. The modifier and structural reinforcing agent each account for 0.1%-10% by mass, and the solvent accounts for less than 3% by mass. Alternatively, the graphene oxide slurry is mixed with a modifier and a structural reinforcing agent, with each modifier and structural reinforcing agent accounting for 0.1%-10% by mass. The slurry is then coated onto a release film and dried to obtain a graphene oxide film. After drying, the film is reduced to obtain a reduced graphene film, which is then subjected to a high-temperature graphitization treatment at 2300-3000℃ for 0.5-2 hours to obtain a modified graphitized film material.

7. The method according to claim 6, characterized in that, The graphitized organic polymer is obtained by carbonizing an organic polymer selected from polyimide polymers or polyacrylonitrile polymers at 1200-1500°C for 1-2 hours, followed by graphitization at 2300-3000°C for 0.5-2 hours. and / or The graphite is acid-treated, washed with water until neutral, and then mixed with a modifier, a structural reinforcing agent, and a small amount of solvent. and / or The solvent includes at least one of N-methylpyrrolidone, n-hexane, and water.

8. The method according to claim 6, characterized in that, The release film is a polyethylene terephthalate, polypropylene, or polyethylene plastic film with a surface (the bonding surface of the graphitized film material) treated with a silicone oil coating. and / or The reducing agent used in the reduction includes hydrazine hydrate or vitamin C.

9. The use of the modified graphitized film material according to any one of claims 1 to 5, characterized in that, The modified graphitized film is used as a current collector for the lithium metal composite electrode in a lithium battery.

10. The use according to claim 9, characterized in that, The lithium metal composite electrode comprises: Modified graphitized film material as a current collector; An active material layer composited on at least one surface of the modified graphitized film, wherein the active material layer is a continuous or intermittently distributed lithium metal or lithium alloy foil; and Lithium atoms diffuse into the modified graphitized film material to form a lithium storage replenishment layer through hot-pressing composite.

Images