A graphene-based reference solid-state battery and a preparation method thereof

Abstract

The application belongs to the technical field of secondary batteries, and relates to a graphene-based reference solid-state battery and a preparation method thereof. The graphene-based reference solid-state battery comprises a positive electrode, a negative electrode and a solid-state electrolyte. The positive electrode, the negative electrode and the solid-state electrolyte film all contain multilayer graphene oxide film fragments. The interlayer spacing of the multilayer graphene oxide film is 4-20 angstroms. A small amount of liquid electrolyte is arranged between the solid-state electrolyte film and the positive electrode and the negative electrode. The graphene-based reference solid-state battery has an ion rapid transportation channel constructed by the multilayer graphene oxide in the positive electrode and the negative electrode and the solid-state electrolyte. The lithium ion diffusion and ion conductivity in the positive electrode and the negative electrode are significantly improved. The charge and discharge performance is improved. High energy density, long cycle life and high safety are achieved.

Description

Technical Field

[0001] This application relates to the field of secondary battery materials technology, and more specifically, to a graphene-based solid-state battery and its preparation method. Background Technology

[0002] Lithium-ion batteries are widely used in all aspects of modern life due to their advantages such as no memory effect, long cycle life, and environmental friendliness. With the continuous expansion of application scenarios (such as the low-altitude economy and drone industry) and the increasing demands on battery performance from different applications, developing batteries with high energy density, high rate capability, and high safety is currently a key focus of lithium battery technology development. Solid-state battery technology is an important development direction for achieving high energy density and high safety performance.

[0003] In existing battery technologies, various methods have been explored to improve battery performance. To increase energy density, optimizing electrode materials is commonly employed, such as using active materials with higher specific capacity or improving the microstructure of electrode materials to increase lithium-ion storage capacity. Enhancing battery safety often involves designing more stable electrolyte systems, using flame-retardant additives, or improving battery encapsulation structures. Additionally, existing technologies include locally adding graphene oxide to the positive electrode, negative electrode, or solid electrolyte membrane, attempting to improve local performance through the properties of graphene oxide.

[0004] However, existing solid-state battery technology still has significant drawbacks. Some solutions incorporating graphene oxide cannot construct a continuous and efficient ion transport network. Furthermore, current methods lack effective control over the interlayer spacing of graphene oxide, making it difficult to form ideal fast ion channels and effectively improve lithium-ion mobility. Due to the inherently slow lithium-ion migration rate in solid-state batteries, coupled with the aforementioned issues, the solid-solid interface impedance remains high. This directly leads to severe battery polarization, resulting in slower charge / discharge rates, reduced cycle life, and an inability to meet the growing demands for high energy density, high rate capability, and high safety in applications. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a graphene-based solid-state battery and its fabrication method. This graphene-based solid-state battery significantly improves lithium-ion diffusion and ionic conductivity in the positive and negative electrodes by constructing ion channels in the positive and negative electrodes and the solid electrolyte through multilayer graphene oxide films, thereby improving charge-discharge performance and achieving high energy density, long cycle life, and high safety.

[0006] The technical concept of this application is as follows: First, a multilayer graphene oxide film is efficiently prepared by coating. This multilayer graphene oxide film, combined with a small amount of liquid electrolyte, fills the gaps between the electrode active particles, creating a fast ion transport channel between the positive electrode, negative electrode, and solid electrolyte, forming a continuous ion transport network. The high orientation of graphene oxide significantly reduces the resistance to ion transport, thereby improving the lithium-ion diffusion kinetics of the positive and negative electrode materials and significantly enhancing the fast charge and discharge performance of the battery. Simultaneously, graphene oxide possesses excellent lithium-philic properties; its addition to the negative electrode can widen the lithium plating window and improve the charging window of the quasi-solid-state battery. Furthermore, the abundant oxygen-containing functional groups on the surface of graphene oxide can fix anions, promoting lithium salt dissociation and improving the ionic conductivity of the solid electrolyte. The functional groups in graphene oxide also further enhance the mechanical properties of the solid electrolyte through hydrogen bonding with the groups in the solid electrolyte.

[0007] The technical solution adopted in this application is as follows:

[0008] In a first aspect, this application provides a graphene-based solid-state battery, including a positive electrode, a negative electrode, and a solid electrolyte membrane; the positive electrode, the negative electrode, and the solid electrolyte membrane all contain multilayer graphene oxide film fragments, and a liquid electrolyte is present between the solid electrolyte membrane and the positive and negative electrode, wherein the liquid electrolyte accounts for 1%-5% of the total mass of the entire quasi-solid-state battery;

[0009] The multilayer graphene oxide film fragments are obtained by coating a suspension containing graphene oxide onto a polymer substrate film, drying and peeling to obtain a multilayer graphene oxide film, and then crushing the multilayer graphene oxide film; the interlayer spacing of the multilayer graphene oxide film is 4-20 angstroms.

[0010] Furthermore, in the aforementioned positive electrode sheet, the mass of the multilayer graphene oxide film fragments accounts for 0.1%-10% of the total mass of the positive electrode sheet; in the aforementioned negative electrode sheet, the mass of the multilayer graphene oxide film fragments accounts for 0.1%-10% of the total mass of the negative electrode sheet.

[0011] Furthermore, in the above-mentioned positive electrode sheet, the positive electrode active material includes one or more of lithium iron phosphate, ternary cathode and lithium cobalt oxide.

[0012] Furthermore, in the aforementioned negative electrode sheet, the negative electrode active material includes one or more of graphite, silicon carbon, and silicon oxide.

[0013] Furthermore, the mass percentage of multilayer graphene oxide film fragments in the above-mentioned solid electrolyte is 0.2%-5%; the solid electrolyte membrane is one of polyvinylidene fluoride membrane, polyepoxy vinyl membrane, polyacrylonitrile-based membrane, polyimide-based membrane, polyethylene-based membrane, polypropylene-based membrane or its derivatives or modifiers.

[0014] Secondly, this application provides a method for preparing the above-mentioned graphene-based solid-state battery, comprising:

[0015] A suspension containing graphene oxide is coated onto a polymer substrate, dried, and peeled to obtain a multilayer graphene oxide film with a thickness of 500 nm to 10 μm. The multilayer graphene oxide film is then broken into fragments with a particle size of 500 nm to 10 μm and dispersed in a solvent to obtain a graphene slurry with a solid content of 0.2 wt% to 5 wt%.

[0016] Positive electrode slurry, negative electrode slurry, and solid electrolyte slurry containing the graphene slurry were prepared respectively, and then coated to obtain positive electrode sheet, negative electrode sheet, and solid electrolyte membrane.

[0017] The above-mentioned positive electrode, solid electrolyte membrane, and negative electrode are stacked in sequence, sealed and dried, and then injected with 1%-5% liquid electrolyte.

[0018] Furthermore, the preparation method of the above-mentioned multilayer graphene oxide film includes:

[0019] The graphene oxide suspension and dispersant were mixed and stirred in a polar solvent, ultrasonically dispersed, coated on a polymer substrate film, and dried at 80-100℃ to obtain a multilayer graphene oxide film.

[0020] The solid content of graphene oxide in the graphene oxide suspension is 2wt%-5wt%, and the coating thickness is 100μm-500μm.

[0021] Furthermore, the preparation method of the above-mentioned positive electrode sheet includes:

[0022] The multilayer graphene oxide film fragments were dispersed in N-methylpyrrolidone to obtain graphene-NMP slurry;

[0023] A positive electrode slurry is obtained by mixing positive electrode active material, conductive agent, binder and graphene-NMP slurry. The positive electrode slurry is then uniformly coated on aluminum foil, and the positive electrode sheet is obtained after drying and cold pressing.

[0024] Furthermore, the preparation method of the above-mentioned negative electrode sheet includes:

[0025] The multilayer graphene oxide film was dispersed in water to obtain a graphene-water slurry;

[0026] A negative electrode slurry is obtained by mixing a negative electrode active material, a conductive agent, a dispersant, a binder and a graphene-water slurry. The negative electrode slurry is then uniformly coated on an aluminum foil, and the negative electrode sheet is obtained after drying and cold pressing.

[0027] Furthermore, the preparation method of the above-mentioned solid electrolyte membrane includes:

[0028] The multilayer graphene oxide film was dispersed in N,N-dimethylformamide to prepare graphene-DMF slurry;

[0029] The polymer electrolyte matrix is ​​added to the graphene-DMF slurry, stirred and mixed, and then a DMF solution containing lithium salt is added. After mixing evenly, a solid electrolyte slurry is obtained.

[0030] The solid electrolyte slurry is coated onto a polymer substrate membrane and then vacuum dried to obtain the solid electrolyte membrane.

[0031] In summary, this application has the following beneficial effects:

[0032] 1. This application provides a graphene-based solid-state battery in which multilayer graphene oxide film fragments are added to both the positive and negative electrodes and the solid electrolyte. Combined with a small amount of liquid electrolyte, this significantly improves the transport of lithium ions between the active particles of the electrodes. This multilayer graphene oxide film has a regular layered structure with an interlayer spacing of 4-20 angstroms. This interlayer spacing can construct fast ion channels and create continuous diffusion paths within the particles, allowing lithium ions to move rapidly within the channels, thereby improving lithium ion mobility and enhancing the battery's charge-discharge performance.

[0033] 2. This application provides a coating method for synthesizing multilayer graphene oxide films. The coating method significantly improves the preparation efficiency, and based on this graphene film, various graphene slurries can be flexibly prepared, allowing graphene to be applied in positive electrodes, negative electrodes, and electrolytes.

[0034] 3. The quasi-solid-state battery prepared in this application significantly reduces the liquid electrolyte content, improves safety, and at the same time uses multilayer graphene oxide to construct ion transport channels, so as to ensure the battery's fast charge-discharge performance and cycle performance even with a significant reduction in liquid electrolyte content. Attached Figure Description

[0035] Figure 1 This is a SEM image of the multilayer graphene oxide film provided in Example 1 of this application;

[0036] Figure 2 This is the XRD pattern of the multilayer graphene oxide film provided in Example 1 of this application without being immersed in electrolyte;

[0037] Figure 3This is the XRD pattern of the multilayer graphene oxide film provided in Example 1 of this application after immersion in the electrolyte for 45 min;

[0038] Figure 4 This is the XRD pattern of the multilayer graphene oxide film provided in Example 3 of this application after high-temperature heat treatment. Detailed Implementation

[0039] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Specific conditions not specified in the examples shall be carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0040] This embodiment provides a graphene-based solid-state battery, which includes a positive electrode, a negative electrode, a solid electrolyte membrane, and a small amount of liquid electrolyte; specifically:

[0041] 1. Positive electrode sheet

[0042] In the process of preparing the positive electrode sheet, the mass ratio of the positive electrode active material, conductive agent, binder and multilayer graphene oxide film fragments is 93:(1-5):(1-5):(0.1-10); preferably, the mass ratio is 93:(2-4):(2-4):(0.5-5); more preferably, the mass ratio is 93:3:3:1.

[0043] The positive electrode active material is one or more of lithium iron phosphate, ternary positive electrode and lithium cobalt oxide; the conductive agent is at least one of conductive carbon black (e.g., commercial Super P), carbon nanotubes and graphene; the binder is at least one of polyvinylidene fluoride (PVDF), polyethylene oxide (PEO), polyacrylonitrile (PAN) and lithium polyacrylate (LiPAA).

[0044] 2. Negative electrode plate

[0045] In the preparation of the negative electrode sheet, the mass ratio of the negative electrode active material, conductive agent, dispersant, binder and multilayer graphene oxide film fragments is 93:(0.5-1.5):(1-3):(1-4):(0.1-10); preferably, the mass ratio is 93:(0.8-1.2):(1.5-2.5):(1.5-3.5):(0.5-5); more preferably, the mass ratio is 93.6:1:2:2.4:1.

[0046] The negative electrode active material is one or more of artificial graphite, natural graphite, silicon-carbon, and silicon-oxygen. The conductive agent is at least one of conductive carbon black (e.g., commercially available Super P), graphene, carbon nanofibers, and silver nanowires; the dispersant is sodium carboxymethyl cellulose (CMC) or sodium dodecyl sulfate (SDS); and the binder is at least one of styrene-butadiene rubber (SBR), polyimide (PI), polydopamine (PDA), or sodium alginate.

[0047] 3. Solid electrolyte membrane

[0048] In the solid electrolyte membrane process, the mass ratio of polymer electrolyte matrix, lithium salt and multilayer graphene oxide film fragments is 83:(10-20):(0.5-5); preferably 83:(13-18):(1-3).

[0049] The polymer electrolyte matrix is ​​one of polyvinylidene fluoride (PVDF), polyethylene oxide (PEO), polyacrylonitrile (PAN), polyimide (PI), polyethylene (PE), and polypropylene (PP), or a derivative or modifier thereof; the lithium salt is at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalateborate)borate (LiBOB), lithium difluorooxalateborate (LiDFOB), lithium hexafluorophosphate, lithium perchlorate, or lithium borohydride.

[0050] 4. Liquid electrolyte, wherein the liquid electrolyte is a conventional commercial liquid electrolyte, which accounts for 1%-5% of the total mass of the quasi-solid-state battery, preferably 1.5%-4.5%, for example, it can be 2%, 3% or 4%.

[0051] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0052] Example of preparation of multilayer graphene oxide films

[0053] Preparation Example 1

[0054] This preparation example provides a multilayer graphene oxide film, the preparation method of which is as follows:

[0055] (1) Weigh 15g of graphene oxide and disperse it in water to obtain a graphene oxide dispersion.

[0056] (2) Add the graphene oxide dispersion and 15 mg of PVP to 100 ml of deionized water and stir for 4 h, then perform ultrasonic dispersion for 2 h, and after standing, obtain the coating slurry (the solid content of graphene oxide is 2.5 wt%).

[0057] (3) The coating slurry was coated onto the PET film using a coating machine. The coating thickness was 300 μm. Then, it was dried at 90 °C for 12 h to obtain a multilayer graphene oxide film.

[0058] Figure 1 The image shows a SEM image of the multilayer graphene oxide film. As can be seen from the image, its surface exhibits a regular multilayer structure with a thickness of 3 μm.

[0059] Figure 2 and Figure 3 Here is the XRD pattern of this multilayer graphene oxide film. Figure 2 The interlayer spacing of the multilayer graphene oxide film is 6.97 angstroms; after immersion in the electrolyte for 45 minutes, the interlayer spacing is 18.7 angstroms.

[0060] Preparation Example 2

[0061] The difference between this and Preparation Example 1 is that the coating thickness is 500 μm; the thickness of the resulting multilayer graphene oxide film is 5 μm; and the interlayer spacing is 7.05 angstroms.

[0062] Preparation Example 3

[0063] The difference between this and Preparation Example 1 is that the obtained multilayer graphene oxide film was subjected to high-temperature heat treatment at 1200℃ for 5 hours in an argon atmosphere; the thickness of the obtained multilayer graphene film was 6 μm; and the interlayer spacing was 3.34 angstroms.

[0064] Example

[0065] Example 1

[0066] This embodiment provides a graphene-based solid-state battery, the preparation method of which is as follows:

[0067] 1. Preparation of the positive electrode sheet:

[0068] The multilayer graphene oxide film provided in Preparation Example 1 was broken into fragments with a particle size of 3 μm and dispersed in N-methylpyrrolidone to obtain graphene-NMP slurry.

[0069] Lithium iron phosphate (LiFePO4) was used as the active material, Super P as the conductive agent, and PVDF as the binder. The mass ratio of the active material, Super P, PVDF, and multilayer graphene oxide film fragments was 93:3:3:1. The active material, Super P, a 5% solids content PVDF@NMP solution, and a 0.8% solids content graphene@NMP slurry were thoroughly mixed and stirred in the specified proportions to obtain the positive electrode slurry. Finally, the positive electrode slurry was uniformly coated onto aluminum foil, and after drying and cold pressing, the positive electrode sheet was obtained.

[0070] (2) Preparation of negative electrode sheet:

[0071] The multilayer graphene oxide film provided in Preparation Example 1 was broken into fragments with a particle size of 500 nm-5 μm and dispersed in water to obtain graphene-water slurry.

[0072] Graphite is used as the active material, Super P as the conductive agent, CMC as the dispersant, and SBR as the binder. The mass ratio of the active material, Super P, CMC, SBR, and multilayer graphene oxide film fragments is 93.6:1:2:2.4:1. The active material, Super P, CMC, a 45% solids content SBR solution, and a 1% solids content graphene@water slurry are thoroughly mixed in the specified proportions to obtain the negative electrode slurry. Finally, the mixture is uniformly coated onto copper foil, and after drying and cold pressing, the negative electrode sheet is obtained.

[0073] (3) Preparation of solid electrolyte membranes:

[0074] The multilayer graphene oxide film provided in Preparation Example 1 was broken into fragments with a particle size of 500 nm-5 μm and dispersed in N,N-dimethylformamide to obtain graphene-DMF slurry.

[0075] PEO was used as the polymer electrolyte matrix, and LiTFSI was used as the lithium salt. The mass ratio of PEO, LiTFSI, and multilayer graphene oxide film fragments was 83:15:2. First, PEO was added to a 0.4% solid content graphene-DMF slurry and stirred for 3 hours to obtain solution A. Then, LiTFSI was dispersed in DMF and mixed and sonicated for 2 hours to obtain solution B. After mixing and stirring solutions A and B for 2 hours, the mixture was poured onto a polytetrafluoroethylene membrane and vacuum dried to obtain a solid electrolyte membrane.

[0076] (4) Battery fabrication:

[0077] The positive electrode, solid electrolyte membrane, and negative electrode are stacked sequentially, with the solid electrolyte membrane positioned between the positive and negative electrodes to act as a separator. Then, an aluminum-plastic film is wrapped around the film, and the mixture is dried in a vacuum oven at 120°C. After injecting 5 wt% liquid electrolyte (1 M LiPF6 in DMC:EC:EMC = 1:1:1 Vol%), the mixture is sealed and formed to produce a soft-pack quasi-solid-state battery.

[0078] Example 2

[0079] The difference between this example and Example 1 is that the content of multilayer graphene oxide in the positive electrode, negative electrode, and solid electrolyte membrane is reduced to 0.3 wt%. Specifically:

[0080] In the positive electrode, the mass ratio of positive electrode active material, Super P, PVDF, and multilayer graphene oxide film fragments is 93.7:3:3:0.3;

[0081] In the negative electrode: the mass ratio of negative electrode active material, Super P, CMC, SBR, and multilayer graphene oxide film fragments is 94.3:1:2:2.4:0.3;

[0082] The mass ratio of solid electrolyte membrane fragments (PEO, LiTFSI, and multilayer graphene oxide film fragments) is 84.5:15.2:0.3.

[0083] Example 3:

[0084] The difference between this and Example 1 is that the positive electrode active material lithium iron phosphate is replaced with an equal amount of NCM811.

[0085] Example 4:

[0086] The difference between this and Example 1 is that the graphite anode active material is replaced with an equal amount of graphite + 10% silicon-carbon mixed anode.

[0087] Example 5:

[0088] The difference between this example and Example 1 is that the polymer electrolyte matrix PEO is replaced with an equal amount of PVDF.

[0089] Example 6

[0090] The difference between this and Example 1 is that the amount of liquid electrolyte injected during battery fabrication is 2 wt%.

[0091] Example 7

[0092] The difference between this example and Example 1 is that the positive electrode, negative electrode, and solid electrolyte membrane are prepared using an equal amount of multilayer graphene oxide film provided in Example 2.

[0093] Example 8

[0094] The difference between this and Example 1 is that the multilayer graphene oxide film used in the preparation of the positive electrode, negative electrode, and solid electrolyte membrane has a particle size of 8 μm.

[0095] Comparative Example 1

[0096] The difference between this comparative example and Example 1 is that: multilayer graphene oxide film fragments (provided in Preparation Example 1) are added only during the preparation of the solid electrolyte membrane, and are not added during the preparation of the positive and negative electrodes. Specifically:

[0097] In the positive electrode: the mass ratio of positive electrode active material, Super P, and PVDF is 94:3:3;

[0098] In the negative electrode: the mass ratio of negative electrode active material, Super P, CMC, and SBR is 94.6:1:2:2.4;

[0099] Solid electrolyte membrane: The mass ratio of PEO, LiTFSI, and multilayer graphene oxide film fragments is 83:15:2.

[0100] Comparative Example 2

[0101] The difference between this comparative example and Example 1 is that no multilayer graphene oxide film fragments are added during the preparation of the positive electrode, negative electrode, and solid electrolyte membrane. Specifically:

[0102] In the positive electrode: the mass ratio of positive electrode active material, Super P, and PVDF is 94:3:3;

[0103] In the negative electrode: the mass ratio of negative electrode active material, Super P, CMC, and SBR is 94.6:1:2:2.4;

[0104] Solid electrolyte membrane: PEO and LiTFSI in a mass ratio of 85:15.

[0105] Comparative Example 3

[0106] The difference between this comparative example and Example 1 is that the multilayer graphene film added during the preparation of the positive electrode, negative electrode and solid electrolyte membrane was provided by Preparation Example 3.

[0107] Comparative Example 4

[0108] The difference between this comparative example and Example 1 is that the particle size of the multilayer graphene oxide film fragments added during the preparation of the positive electrode, negative electrode and solid electrolyte membrane is 350 nm.

[0109] Comparative Example 5

[0110] The difference between this comparative example and Example 1 is that the particle size of the multilayer graphene oxide film fragments added during the preparation of the positive electrode, negative electrode and solid electrolyte membrane is 15 μm.

[0111] Comparative Example 6

[0112] The difference between this comparative example and Example 1 is that an equal amount of commercially available ordinary graphene oxide was added during the preparation of the positive electrode, negative electrode, and solid electrolyte membrane.

[0113] Comparative Example 7

[0114] The difference between this comparative example and Example 1 is that no liquid electrolyte is added during battery preparation; that is, the amount of liquid electrolyte is 0 wt%.

[0115] The electrochemical performance of the quasi-solid-state batteries provided in the above embodiments and comparative examples was tested according to GB / T31486—2024, GB / T31484—2015 and GB 38031—2020. The results are shown in Table 1.

[0116] Table 1.

[0117]

[0118]

[0119] As can be seen from Table 1:

[0120] The quasi-solid-state batteries provided in Examples 1-8 of this application all exhibit excellent charge and discharge performance, achieving high energy density, long cycle life, and high safety.

[0121] As can be seen from the performance comparison of the quasi-solid-state batteries in Comparative Examples 1 and 2 with those in Example 1, the quasi-solid-state batteries have poor long cycle life. The capacity retention rate after 1000 cycles at 1C and the capacity retention rates at 2C and 4C are much lower than those of this application. Although commercially available graphene oxide was used in Comparative Example 6, it was still difficult to achieve the electrochemical performance of this application. This is mainly because the untreated graphene oxide has an irregular sheet structure and small interlayer spacing, making it difficult to construct stable fast ion transport channels.

[0122] As can be seen from Examples 1 and 7 and Comparative Examples 3-5, the interlayer spacing of the multilayer graphene oxide film and the particle size of the film fragments have a significant impact on the performance of solid-state batteries. This is because: if the interlayer spacing is too small, a fast ion transport channel cannot be formed, thus failing to improve ionic conductivity; if the interlayer spacing is too large, lithium ions in the channel will form a disordered distribution, leading to a decrease in ionic conductivity; if the fragment particle size is too small, a continuous pathway cannot be formed between the active material particles; if the fragment particle size is too large, the graphene sheet will completely encapsulate the active material particles, affecting the contact between the active particles and reducing capacity.

[0123] As can be seen from Examples 1 and 6 and Comparative Example 7, injecting a small amount of liquid electrolyte during the fabrication of quasi-solid-state batteries helps improve their charge-discharge performance. This is mainly because a small amount of liquid electrolyte can fill the gaps between the electrode active particles, forming a continuous ion transport network together with the multilayer graphene oxide film to construct fast ion transport channels.

[0124] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A graphene-based solid-state battery, characterized in that, It includes positive electrode plates, negative electrode plates, and solid electrolyte membranes; The positive electrode, negative electrode, and solid electrolyte membrane all contain multilayer graphene oxide film fragments, and a liquid electrolyte is present between the solid electrolyte membrane and the positive and negative electrode, wherein the liquid electrolyte constitutes 1%-5% of the total mass of the quasi-solid-state battery. The multilayer graphene oxide film fragments are obtained by coating a suspension containing graphene oxide onto a polymer substrate film, drying and peeling to obtain a multilayer graphene oxide film, and then crushing the multilayer graphene oxide film; the interlayer spacing of the multilayer graphene oxide film is 4-20 angstroms.

2. The graphene-based solid-state battery according to claim 1, characterized in that, In the positive electrode sheet, the mass of the multilayer graphene oxide film fragments accounts for 0.1%-10% of the total mass of the positive electrode sheet; in the negative electrode sheet, the mass of the multilayer graphene oxide film fragments accounts for 0.1%-10% of the total mass of the negative electrode sheet.

3. The graphene-based solid-state battery according to claim 2, characterized in that, The positive electrode sheet contains one or more of lithium iron phosphate, ternary cathode, and lithium cobalt oxide.

4. The graphene-based solid-state battery according to claim 2, characterized in that, In the negative electrode sheet, the negative electrode active material includes one or more of graphite, silicon carbon, and silicon oxide.

5. The graphene-based solid-state battery according to claim 1, characterized in that, The mass percentage of multilayer graphene oxide film fragments in the solid electrolyte is 0.2%-5%; the solid electrolyte membrane is one of polyvinylidene fluoride membrane, polyepoxy vinyl membrane, polyacrylonitrile-based membrane, polyimide-based membrane, polyethylene-based membrane, polypropylene-based membrane or its derivatives or modifiers.

6. A method for preparing a graphene-based solid-state battery according to any one of claims 1-5, characterized in that, It includes: A suspension containing graphene oxide is coated onto a polymer substrate, dried, and peeled to obtain a multilayer graphene oxide film with a thickness of 500 nm to 10 μm. The multilayer graphene oxide film is then broken into fragments with a particle size of 500 nm to 10 μm and dispersed in a solvent to obtain a graphene slurry with a solid content of 0.2 wt% to 5 wt%. Positive electrode slurry, negative electrode slurry, and solid electrolyte slurry containing the graphene slurry were prepared respectively, and then coated to obtain positive electrode sheet, negative electrode sheet, and solid electrolyte membrane. The above-mentioned positive electrode, solid electrolyte membrane, and negative electrode are stacked in sequence, sealed and dried, and then injected with 1%-5% liquid electrolyte.

7. The method for preparing a graphene-based solid-state battery according to claim 6, characterized in that, The method for preparing the multilayer graphene oxide film includes: The graphene oxide suspension and dispersant were mixed and stirred in a polar solvent, ultrasonically dispersed, coated on a polymer substrate film, and dried at 80-100℃ to obtain a multilayer graphene oxide film. The graphene oxide suspension contains 2wt%-5wt% solids of graphene oxide, and the coating thickness is 100μm-500μm.

8. The method for preparing a graphene-based solid-state battery according to claim 6, characterized in that, The method for preparing the positive electrode sheet includes: The multilayer graphene oxide film fragments were dispersed in N-methylpyrrolidone to obtain graphene-NMP slurry; A positive electrode slurry is obtained by mixing positive electrode active material, conductive agent, binder and graphene-NMP slurry. The positive electrode slurry is then uniformly coated on aluminum foil, and the positive electrode sheet is obtained after drying and cold pressing.

9. The method for preparing a graphene-based solid-state battery according to claim 6, characterized in that, The method for preparing the negative electrode sheet includes: The multilayer graphene oxide film was dispersed in water to obtain a graphene-water slurry; A negative electrode slurry is obtained by mixing a negative electrode active material, a conductive agent, a dispersant, a binder and a graphene-water slurry. The negative electrode slurry is then uniformly coated on an aluminum foil, and the negative electrode sheet is obtained after drying and cold pressing.

10. The method for preparing a graphene-based solid-state battery according to claim 6, characterized in that, The method for preparing the solid electrolyte membrane includes: The multilayer graphene oxide film was dispersed in N,N-dimethylformamide to prepare graphene-DMF slurry; The polymer electrolyte matrix is ​​added to the graphene-DMF slurry, stirred and mixed, and then a DMF solution containing lithium salt is added. After mixing evenly, a solid electrolyte slurry is obtained. The solid electrolyte slurry is coated onto a polymer substrate membrane and then vacuum dried to obtain the solid electrolyte membrane.

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