A lithium-sulfur solid-state battery and a method of manufacturing the same

Abstract

The application discloses a lithium-sulfur solid-state battery and a preparation method thereof, and belongs to the technical field of lithium-sulfur batteries.The lithium-sulfur solid-state battery comprises a positive electrode current collector, a positive electrode layer of three-dimensional graphene and sulfur composite arranged on one side of the positive electrode current collector, a solid-state electrolyte layer arranged on the side of the positive electrode layer of three-dimensional graphene and sulfur composite away from the positive electrode current collector, a modification layer arranged on the side of the solid-state electrolyte layer away from the positive electrode layer of three-dimensional graphene and sulfur composite, and a lithium negative electrode layer arranged on the side of the modification layer away from the solid-state electrolyte layer.The positive electrode layer in the battery is prepared from a three-dimensional graphene-sulfur composite material, which can greatly reduce the loss of positive electrode active material, thereby relieving the interface side reaction between the positive electrode layer and the solid-state electrolyte, and significantly improving the overall operation stability of the battery.The battery disclosed by the application contains a modification layer on the negative electrode side, which can inhibit the germination and growth of lithium dendrites, and significantly improve the cycle stability and safety performance of the battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-sulfur battery technology, specifically relating to a lithium-sulfur solid-state battery and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles, large-scale energy storage power stations, and portable electronic devices, the market has placed higher demands on the energy density, safety, and cycle life of energy storage batteries. Traditional lithium-ion batteries are limited by the theoretical capacity bottleneck of embedded electrode materials, and their energy density is approaching its upper limit, making it difficult to meet the application needs of high-end energy storage scenarios. Lithium-sulfur batteries use elemental sulfur as the positive electrode active material, with a theoretical specific capacity as high as 1675 mAh / g and a theoretical energy density exceeding 2600 Wh / kg. Moreover, sulfur has advantages such as abundant reserves, low cost, and good environmental compatibility, making it a key research and development direction for the next generation of high-energy-density energy storage batteries.

[0003] Traditional lithium-sulfur batteries mostly use organic liquid electrolyte systems. While these systems achieve certain electrochemical performance, liquid electrolytes are inherently flammable, volatile, and prone to leakage. During charge and discharge, they are susceptible to problems such as thermal runaway, electrolyte decomposition, and polysulfide shuttle effects, posing serious safety hazards and significantly limiting the application of lithium-sulfur batteries in high-end applications. Solid-state lithium-sulfur batteries completely replace organic liquid electrolytes with solid electrolytes, fundamentally eliminating safety risks such as leakage, combustion, and explosion. Furthermore, they can be paired with lithium metal anodes to further improve energy density. The overall structural stability, thermal stability, and service life of the battery are significantly improved, making this a key technological path for the commercialization of lithium-sulfur batteries.

[0004] Despite the advantages of sulfide solid electrolytes, existing lithium-sulfur solid batteries still suffer from several technical defects in areas such as cathode materials and interface control, which lead to unsatisfactory electrochemical performance and poor cycle stability, severely restricting their large-scale application.

[0005] First, traditional cathodes directly use elemental sulfur as the active material, which has inherent drawbacks such as extremely poor conductivity and drastic volume expansion during charge and discharge. Elemental sulfur has extremely low room temperature electronic conductivity, resulting in low electron transport efficiency during charge and discharge, significantly reducing the utilization rate of the active material, causing severe battery polarization, and making it difficult to improve rate performance. At the same time, sulfur undergoes a volume change rate of nearly 80% during lithiation and delithiation cycles, which can easily cause the cathode structure to break down, the active material to fall off, and the conductive network to completely collapse, accelerating the rapid decline in battery capacity and shortening battery life.

[0006] Secondly, there are challenges related to high interfacial impedance and poor ion conduction between solid electrolytes and electrode materials. Solid electrolytes and positive and negative electrode materials suffer from lattice mismatch and loose interfacial contact, resulting in high interfacial impedance. This hinders efficient lithium-ion transport, leading to low overall battery ionic conductivity, sluggish charge-discharge kinetics, and significant fluctuations in electrochemical performance, making it impossible to achieve stable and continuous energy storage and release.

[0007] Finally, the poor compatibility between the electrode and electrolyte interface makes it difficult to suppress side reactions and lithium dendrite formation caused by polysulfides. On the one hand, the polysulfide intermediates generated during charging and discharging are highly chemically reactive and readily undergo irreversible chemical reactions with the solid electrolyte. This not only consumes the positive electrode active material and damages the electrolyte structure, but also exacerbates the deterioration of interfacial impedance and blocks lithium-ion transport channels. On the other hand, lithium metal anodes are prone to lithium dendrite formation during cycling, which can not only puncture the solid electrolyte and cause internal short circuits in the battery, but also damage the integrity of the anode interface. Summary of the Invention

[0008] To address the above problems, the purpose of this invention is to provide a lithium-sulfur solid-state battery and its preparation method.

[0009] This invention provides a lithium-sulfur solid-state battery, comprising the following components stacked sequentially: Positive current collector; A three-dimensional graphene-sulfur composite cathode layer is disposed on one side of the cathode current collector; A solid electrolyte layer is disposed on the side of the three-dimensional graphene and sulfur composite positive electrode layer away from the positive electrode current collector; A modification layer is disposed on the side of the solid electrolyte layer away from the positive electrode layer composed of three-dimensional graphene and sulfur; A lithium anode layer is disposed on the side of the modification layer away from the solid electrolyte layer; Wherein: the modification layer is a modification layer containing MOFs material.

[0010] Preferably, the thickness of the three-dimensional graphene-sulfur composite cathode layer is 50~250μm, and more preferably 100~200μm.

[0011] Preferably, the three-dimensional graphene is a petal-shaped porous graphene; the specific surface area of ​​the three-dimensional graphene is 100~5000 m². 2 / g, further preferably 100~2000m 2 / g.

[0012] Preferably, the three-dimensional graphene contains micropores and / or mesopores.

[0013] Preferably, the method for preparing the three-dimensional graphene-sulfur composite cathode layer includes the following steps: S1. Three-dimensional graphene and elemental sulfur are heated and stirred under vacuum conditions to obtain a three-dimensional graphene-sulfur composite material. Using either step S2-1 or S2-2, the three-dimensional graphene-sulfur composite material is prepared into a three-dimensional graphene-sulfur composite cathode layer: S2-1. Mix the three-dimensional graphene-sulfur composite material, binder, and conductive agent, add solvent, and prepare a slurry; coat the slurry onto the surface of the positive electrode current collector, and after drying, obtain the three-dimensional graphene-sulfur composite positive electrode layer. S2-2. After mixing the three-dimensional graphene-sulfur composite material, solid electrolyte, and conductive agent, a binder is added and mixed to obtain a mixture. The mixture is then hot-pressed or electrostatically sprayed onto the surface of the positive electrode current collector to obtain the three-dimensional graphene-sulfur composite positive electrode layer.

[0014] More preferably, in step S1, the mass ratio of three-dimensional graphene to elemental sulfur is 10:90~40:60, and more preferably 15:85~35:65.

[0015] More preferably, in step S1, the heating and stirring speed is 200~600 rpm, the heating and stirring temperature is 155~160℃, and the heating and stirring time is 2~24h.

[0016] More preferably, in step S2-1, the binder is selected from one or two of acrylonitrile copolymer LA133 and acrylonitrile copolymer LA132; the solvent is a mixed solvent composed of isopropanol and water in a volume ratio of 5:95 to 30:70; and the conductive agent is selected from one or more of Ketjen Black, carbon nanotubes, Super P, and graphene.

[0017] More preferably, in step S2-1, the mass ratio of the three-dimensional graphene-sulfur composite material, the conductive agent, and the binder is (70~85):(10~20):(5~10); and the solid content of the slurry is 15~35wt% when the solvent is added.

[0018] In a further preferred embodiment, in step S2-1, the drying temperature is 55~65℃ and the drying time is 12~24h.

[0019] More preferably, in step S2-2, the binder is polytetrafluoroethylene (PTFE); the conductive agent is selected from one or more of Ketjen Black, carbon nanotubes, Super P, and graphene; and the solid electrolyte is selected from Li6PS5Cl, Li6PS5Br, Li6PS5I, and Li 10 GeP2S 12 Li7P3S 11 75Li₂S·₂₅P₂S₅ and Li 10 SiP2S12 One of them.

[0020] More preferably, in step S2-2, the mass ratio of the three-dimensional graphene-sulfur composite material, solid electrolyte, conductive agent and binder is (40~70):(20~40):(1~20):(0.5~5), preferably (40~65):(25~40):(5~20):(0.5~2), and even more preferably 54:36:9:1.

[0021] Preferably, the solid electrolyte layer is a sulfide solid electrolyte layer, specifically selected from Li6PS5Cl, Li6PS5Br, Li6PS5I, and Li 10 GeP2S 12 Li7P3S 11 75Li₂S·₂₅P₂S₅ and Li 10 SiP2S 12 One of them.

[0022] Preferably, the lithium anode layer is selected from one or more of a metallic lithium anode layer, a lithium alloy anode layer, and a lithium-carbon composite anode layer; the thickness of the lithium alloy anode layer is 5~500μm; more preferably 50~500μm.

[0023] Preferably, the lithium anode layer is a lithium-carbon composite anode layer.

[0024] More preferably, the lithium alloy anode layer is selected from lithium and one or more of silicon, indium, silver, magnesium, aluminum, boron, tin, gallium, cobalt, gold, barium, bismuth, calcium, germanium, mercury, platinum, zinc, lead, antimony, cadmium, and cobalt.

[0025] Preferably, the thickness of the modified layer is 1~50μm, more preferably 1~30μm.

[0026] Preferably, the modified layer comprises the following raw materials in parts by mass: 1-20 parts of MOF material, 1-5 parts of lithium salt, 1-5 parts of binder, and 0.5-2 parts of additive.

[0027] More preferably, the MOFs material is selected from one or more of the ZIF series, IRMOF series, MIL series, NU series, UiO series, and PCN series, preferably the ZIF series; the ZIF series is selected from one or more of ZIF-7, ZIF-8, ZIF-63, ZIF-67, ZIF-71, and ZIF-90; the IRMOF series is selected from one or more of IRMOF-1, IRMOF-3, IRMOF-6, IRMOF-8, IRMOF-9, and IRMOF-10; and the MIL series is selected from MIL-53, MIL... -88, MIL-96, MIL-100, MIL-101, MIL-125; the NU sequence is selected from one or more of NU-100, NU-109, NU-110, NU-111, NU-125, NU-901; the UiO series is selected from one or more of UiO-67, UiO-68, UiO-76, UiO-77, UiO-84; the PCN series is selected from one or more of PCN-14, PCN-200, PCN-221, PCN-222, PCN-223, PCN-250.

[0028] More preferably, the lithium salt is selected from one or more of lithium fluoride, lithium nitride, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium perchlorate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium carbonate, lithium oxalate, lithium bicarbonate, lithium acetate, lithium halide, lithium sulfate, and lithium hydroxide.

[0029] More preferably, the adhesive is selected from one or more of polyvinyl alcohol, polyethylene oxide, polybutene-styrene, polystyrene-butadiene copolymer, polyvinylidene fluoride, polystyrene, polycarboxymethyl cellulose, polyurethane, methacrylate, epoxy resin and its derivatives, styrene-butadiene rubber, and sodium carboxymethyl cellulose.

[0030] More preferably, the additive is selected from one or more of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and hexadecyltrimethylammonium bromide.

[0031] Preferably, the method for preparing the modified layer includes the following steps: MOF materials, lithium salts, binders and additives are mixed and then a solvent is added to prepare a slurry. The slurry is coated onto the lithium anode layer and dried to obtain the modified layer.

[0032] More preferably, the solvent is selected from one or more of N-methylpyrrolidone, tetrahydrofuran, dimethyl ethyl ether, dichloromethane, ethylene carbonate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and ethylene glycol dimethyl ether; the mass ratio of MOFs material to solvent is (0.01~0.5):1, preferably (0.05~0.2):1.

[0033] More preferably, the drying temperature is 80~100℃ and the drying time is 8~12h.

[0034] Secondly, the present invention provides a method for preparing a solid-state lithium-sulfur battery, comprising the following steps: A three-dimensional graphene-sulfur composite positive electrode layer is prepared on the positive electrode current collector to obtain the positive electrode side component; a modification layer is prepared on the lithium negative electrode layer to obtain the negative electrode side component; the positive electrode side component, solid electrolyte, and negative electrode side component are assembled and packaged to obtain the solid lithium-sulfur battery.

[0035] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects: The solid-state lithium-sulfur battery designed in this invention has a positive electrode layer made of three-dimensional graphene-sulfur composite material. Three-dimensional graphene possesses a unique three-dimensional porous interconnected structure, which on the one hand provides ample loading space for sulfur active materials and forms a strong physical confinement effect on polysulfide intermediates generated during charging and discharging, reducing their migration and interfacial diffusion within the positive electrode, significantly reducing the loss of positive electrode active materials, thereby alleviating interfacial side reactions between the positive electrode layer and the solid electrolyte, and significantly improving the overall operational stability of the battery. On the other hand, three-dimensional graphene itself has excellent electronic conductivity and structural stability, which can effectively compensate for the defects of poor electronic insulation and hindered ion conduction of elemental sulfur, and synergistically construct an efficient electron / ion hybrid conduction network with the solid electrolyte, optimizing the electron and ion transport dynamics inside the electrode, and improving the utilization rate of active materials and the rate performance of the battery.

[0036] This invention adds a modification layer containing MOFs material to the negative electrode side of the battery. This modification layer can act as a physical barrier layer, isolating direct contact between lithium metal / lithium metal alloy and solid electrolyte, and further blocking the diffusion and migration of polysulfides along the interface path to the negative electrode side. At the same time, the modification layer can effectively regulate the deposition and deintercalation behavior of lithium ions, suppressing the initiation and growth of lithium dendrites from the source, and significantly improving the cycle stability and safety performance of the battery. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the lithium-sulfur solid-state battery in this invention.

[0038] Figure 2This is a SEM image of the three-dimensional graphene used in the embodiments of the present invention.

[0039] Figure 3 This is a SEM image of the cross-section of the lithium-sulfur solid-state battery prepared in Example 1. Detailed Implementation

[0040] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0041] As mentioned above, the present invention provides a lithium-sulfur solid-state battery, comprising the following components stacked sequentially: Positive current collector; A three-dimensional graphene-sulfur composite cathode layer is disposed on one side of the cathode current collector; A solid electrolyte layer is disposed on the side of the three-dimensional graphene and sulfur composite positive electrode layer away from the positive electrode current collector; A modification layer is disposed on the side of the solid electrolyte layer away from the positive electrode layer composed of three-dimensional graphene and sulfur; A lithium anode layer is disposed on the side of the modification layer away from the solid electrolyte layer; Wherein: the modification layer is a modification layer containing MOFs material.

[0042] The solid-state lithium-sulfur battery designed in this invention uses a three-dimensional graphene-sulfur composite material as the core positive electrode active material. Three-dimensional graphene possesses a unique petal-like porous structure, which not only provides ample storage space for sulfur active materials, but its internal micropores also utilize steric hindrance to confine the sulfur active materials into a nanoscale dispersed state, even inducing the formation of short-chain sulfur, thus creating a strong physical confinement for polysulfide intermediates generated during charging and discharging. This effectively blocks direct contact between polysulfides and the solid electrolyte, significantly reducing interfacial side reactions and minimizing the loss of positive electrode active materials. The pores of three-dimensional graphene can also serve as nanoreactors, providing a site for sulfur redox reactions and shortening the ion / electron transport path, effectively solving the problems of rapid capacity decay and volume expansion in traditional lithium-sulfur batteries. Furthermore, three-dimensional graphene itself possesses excellent electronic conductivity and structural stability, effectively compensating for the poor electronic insulation and impaired ion conduction of elemental sulfur. It also synergistically constructs a highly efficient electron / ion hybrid conduction network with the solid electrolyte, optimizing the electron and ion transport kinetics within the electrode and improving the utilization rate of active materials and battery rate performance.

[0043] For the negative electrode system, this invention adds a modification layer to the surface of the lithium negative electrode layer, which is made of MOF (Metal-Organic Focal Elements) material. MOF materials possess abundant porous structures and excellent ion transport performance, which can shorten the transport path of lithium ions through the artificial SEI (Sediment-Insulated Electrode), promoting rapid and uniform lithium ion conduction. Furthermore, MOF materials have a certain degree of rigidity and extremely high mechanical strength, which, as a modification layer, can construct a robust mechanical barrier, fundamentally inhibiting lithium dendrite initiation and longitudinal growth, and eliminating the risk of internal short circuits caused by dendrites piercing the electrolyte. In addition, this modification layer can effectively isolate the lithium negative electrode layer from direct contact with the solid electrolyte, further blocking the diffusion and migration of polysulfides along the interface path to the negative electrode side, comprehensively enhancing the stability of the negative electrode interface, significantly improving battery cycle life and safety performance, and significantly alleviating the industry pain points of traditional liquid electrolyte batteries such as easy fire and thermal runaway.

[0044] This invention's solid-state lithium-sulfur battery uses a solid electrolyte, completely eliminating the need for traditional flammable and volatile organic liquid electrolytes. This eliminates the risks of leakage and spontaneous combustion at the source, further strengthening the battery's safety. Leveraging the synergistic effect of the aforementioned material selection and structural design, this solid-state lithium-sulfur battery combines high energy density and long cycle life, fully meeting the high-performance requirements of future high-end energy storage scenarios. Its overall structural design is simple and rational, the manufacturing process is highly controllable and easy to mass-produce, possessing excellent prospects for industrial application and market promotion value.

[0045] In some embodiments, the thickness of the three-dimensional graphene-sulfur composite cathode layer is 50~250μm, including but not limited to: 50μm, 100μm, 150μm, 200μm, 250μm, etc., preferably 100~200μm.

[0046] In some embodiments, the three-dimensional graphene is petal-shaped porous graphene; the specific surface area of ​​the three-dimensional graphene is 100~5000 m². 2 / g; including but not limited to: 100m 2 / g、500m 2 / g, 1000m 2 / g, 1500m 2 / g、2000m 2 / g、2500m 2 / g、3000m 2 / g、3500m 2 / g、4000m 2 / g、4500m 2 / g、5000m 2 / g, etc., preferably 100~2000m 2 / g.

[0047] In some embodiments, three-dimensional graphene contains micropores and / or mesopores. In some embodiments, the method for preparing the three-dimensional graphene-sulfur composite cathode layer includes the following steps: S1. Three-dimensional graphene and elemental sulfur are heated and stirred under vacuum conditions to obtain a three-dimensional graphene-sulfur composite material. Using either step S2-1 or S2-2, the three-dimensional graphene-sulfur composite material is prepared into a three-dimensional graphene-sulfur composite cathode layer: S2-1. Mix the three-dimensional graphene-sulfur composite material, binder, and conductive agent, add solvent, and prepare a slurry; coat the slurry onto the surface of the positive electrode current collector, and after drying, obtain the three-dimensional graphene-sulfur composite positive electrode layer. S2-2. After mixing the three-dimensional graphene-sulfur composite material, solid electrolyte, and conductive agent, a binder is added and mixed to obtain a mixture. The mixture is then hot-pressed or electrostatically sprayed onto the surface of the positive electrode current collector to obtain the three-dimensional graphene-sulfur composite positive electrode layer.

[0048] In some embodiments, in step S1, the mass ratio of three-dimensional graphene to sulfur is 10:90 to 40:60, including but not limited to: 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, etc., preferably 15:85 to 35:65.

[0049] In some embodiments, in step S1, the heating and stirring speed is 200~600 rpm, including but not limited to: 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, etc.; the heating and stirring temperature is 155~160℃, including but not limited to: 155℃, 156℃, 157℃, 158℃, 159℃, 160℃, etc.; the heating and stirring time is 2~24h, including but not limited to: 2h, 5h, 8h, 10h, 12h, 15h, 18h, 20h, 22h, 24h, etc.

[0050] In some embodiments, in step S2-1, the binder is selected from one or two of acrylonitrile copolymer LA133 and acrylonitrile copolymer LA132; the solvent is a mixed solvent composed of isopropanol and water in a volume ratio of (5~30):(70~95); and the conductive agent is selected from one or more of Ketjen Black, carbon nanotubes, Super P, and graphene.

[0051] In some embodiments, in step S2-1, the mass ratio of the three-dimensional graphene-sulfur composite material, the conductive agent, and the binder is (70~85):(10~20):(5~10), including but not limited to: 70:20:10, 75:15:10, 75:20:5, 80:10:10, 80:15:5, 85:10:5, etc.; the solid content of the slurry to which the solvent is added is 15~35wt%, including but not limited to: 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, etc.

[0052] In some embodiments, in step S2-1, the drying temperature is 55~65℃, including but not limited to: 55℃, 58℃, 60℃, 62℃, 65℃, etc.; the drying time is 12~24h, including but not limited to: 12h, 15h, 18h, 20h, 24h, etc.

[0053] In some embodiments, in step S2-2, the binder is PTFE, the conductive agent is selected from one or more of Ketjen Black, carbon nanotubes, Super P, and graphene; the solid electrolyte is selected from Li6PS5Cl, Li6PS5Br, Li6PS5I, and Li 10 GeP2S 12 Li7P3S 11 75Li₂S·₂₅P₂S₅ and Li 10 SiP2S 12 One of them.

[0054] In some embodiments, in step S2-2, the mass ratio of the three-dimensional graphene-sulfur composite material, solid electrolyte, conductive agent, and binder is (40~70):(20~40):(1~20):(0.5~5), including but not limited to: 40:40:15:5, 50:25:20:5, 54:36:9:1, 60:20:19.5:0.5, 70:20:5:5, 60:15:20:5, 60:36:1:3, etc., preferably (40~65):(25~40):(5~20):(0.5~2); more preferably 54:36:9:1.

[0055] In some embodiments, the solid electrolyte layer is a sulfide solid electrolyte layer, specifically selected from Li6PS5Cl, Li6PS5Br, Li6PS5I, and Li 10 GeP2S 12 Li7P3S 11 75Li₂S·₂₅P₂S₅, Li 10 SiP2S 12 One of them.

[0056] In this invention, the solid electrolyte layer is a sulfide solid electrolyte layer, which can improve the chemical compatibility between the positive electrode layer and the solid electrolyte layer and reduce the interfacial impedance between the positive electrode layer and the solid electrolyte layer.

[0057] In some embodiments, the lithium anode layer is selected from one or more of a metallic lithium anode layer, a lithium alloy anode layer, and a lithium-carbon composite anode layer; the thickness of the lithium alloy anode layer is 5~500μm, including but not limited to: 5μm, 50μm, 100μm, 200μm, 300μm, 400μm, 500μm, etc.; more preferably 100~500μm.

[0058] In some embodiments, the lithium anode layer is a lithium-carbon composite anode layer.

[0059] The lithium-carbon composite anode layer contains a porous carbonaceous framework, which not only provides space for the deposition of metallic lithium, but also suppresses volume changes during the cycling process of metallic lithium, thereby improving the cycling efficiency and safety of the lithium anode, and enhancing energy density and cycle life.

[0060] In some embodiments, the lithium alloy anode layer is selected from lithium and one or more of silicon, indium, silver, magnesium, aluminum, boron, tin, gallium, cobalt, gold, barium, bismuth, calcium, germanium, mercury, platinum, zinc, lead, antimony, cadmium, and cobalt.

[0061] In some embodiments, the thickness of the modification layer is 1~50μm, including but not limited to: 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, etc.

[0062] In some embodiments, the raw materials for the modifying layer, by weight percentage, include: MOF materials are 1 to 20 parts, including but not limited to: 1 part, 2 parts, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, etc.; Lithium salt 1 to 5 parts, including but not limited to: 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc.; 1 to 5 parts of adhesive, including but not limited to: 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc.; Additives are used in amounts of 0.5 to 2 parts, including but not limited to: 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, etc.

[0063] In some embodiments, the MOFs material is selected from one or more of the ZIF series, IRMOF series, MIL series, NU series, UiO series, and PCN series, preferably the ZIF series; the ZIF series is selected from one or more of ZIF-7, ZIF-8, ZIF-63, ZIF-67, ZIF-71, and ZIF-90; the IRMOF series is selected from one or more of IRMOF-1, IRMOF-3, IRMOF-6, IRMOF-8, IRMOF-9, and IRMOF-10; the MIL series is selected from MIL-53, MIL... -88, MIL-96, MIL-100, MIL-101, MIL-125; the NU sequence is selected from one or more of NU-100, NU-109, NU-110, NU-111, NU-125, NU-901; the UiO series is selected from one or more of UiO-67, UiO-68, UiO-76, UiO-77, UiO-84; the PCN series is selected from one or more of PCN-14, PCN-200, PCN-221, PCN-222, PCN-223, PCN-250.

[0064] In some embodiments, the lithium salt is selected from one or more of lithium fluoride, lithium nitride, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium perchlorate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium carbonate, lithium oxalate, lithium bicarbonate, lithium acetate, lithium halide, lithium sulfate, and lithium hydroxide.

[0065] In some embodiments, the adhesive is selected from one or more of polyvinyl alcohol, polyethylene oxide, polybutene-styrene, polystyrene-butadiene copolymer, polyvinylidene fluoride, polystyrene, polycarboxymethyl cellulose, polyurethane, methacrylate, epoxy resin and its derivatives, styrene-butadiene rubber, and sodium carboxymethyl cellulose.

[0066] In some embodiments, the additive is selected from one or more of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and hexadecyltrimethylammonium bromide.

[0067] In some embodiments, the thickness of the modification layer is 1~50μm, including but not limited to: 1μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, etc., preferably 5~40μm.

[0068] In some embodiments, the method for preparing the modified layer includes the following steps: MOF materials, lithium salts, binders and additives are mixed and then a solvent is added to prepare a slurry. The slurry is coated onto the lithium anode layer and dried to obtain the modified layer.

[0069] In some embodiments, the solvent is selected from one or more of N-methylpyrrolidone, tetrahydrofuran, dimethyl ethyl ether, dichloromethane, ethylene carbonate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and ethylene glycol dimethyl ether. The mass ratio of MOFs to solvent is (0.01~0.5):1, including but not limited to: 0.01:1, 0.05:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, etc., preferably (0.05~0.2):1.

[0070] In some embodiments, the drying temperature is 80~100℃, including but not limited to: 80℃, 85℃, 90℃, 95℃, 100℃, etc.; the drying time is 8~12h, including but not limited to: 8h, 9h, 10h, 11h, 12h, etc.

[0071] Secondly, the present invention provides a method for preparing a solid-state lithium-sulfur battery, comprising the following steps: A three-dimensional graphene-sulfur composite positive electrode layer is prepared on the positive electrode current collector to obtain the positive electrode side component; a modification layer is prepared on the lithium negative electrode layer to obtain the negative electrode side component; the positive electrode side component, solid electrolyte, and negative electrode side component are assembled and packaged to obtain the solid lithium-sulfur battery.

[0072] A schematic diagram of the solid-state lithium-sulfur battery in this invention is shown below. Figure 1 As shown, the cathode includes a positive current collector; a three-dimensional graphene-sulfur composite positive electrode layer disposed on one side of the positive current collector; a solid electrolyte layer disposed on the side of the three-dimensional graphene-sulfur composite positive electrode layer away from the positive current collector; a modification layer disposed on the side of the solid electrolyte layer away from the three-dimensional graphene-sulfur composite positive electrode layer; and a lithium negative electrode layer disposed on the side of the modification layer away from the solid electrolyte layer. Specific preparation methods can be found in the embodiments.

[0073] Example 1 In this embodiment, the mass ratio of three-dimensional graphene to elemental sulfur in the composite cathode layer is 20:80; the three-dimensional graphene is a porous graphene with a three-dimensional petal-like structure, as visible under SEM. Figure 2 It can be seen that it has a three-dimensional petal shape; according to tests, three-dimensional graphene contains both micropores and mesopores, with micropore diameters of approximately 0.5~1.5 nm and mesopore diameters of approximately 2~10 nm, and a specific surface area of ​​approximately 1000 m². 2 / g; the MOF material is ZIF-8 material with a D50 of 200nm and a pore size of 0.4Å; the solid electrolyte is Li6PS5Cl sulfide solid electrolyte; the lithium anode layer is a lithium-carbon composite anode layer.

[0074] The solid-state lithium-sulfur battery is prepared using the following method in this embodiment: S1. Three-dimensional graphene (3DG) and elemental sulfur are added to a reaction vessel and heated and stirred under vacuum conditions. During the heating process, the scraper speed is 50 rpm and the stirring speed is 300 rpm. When the temperature reaches 155℃, the scraper speed is adjusted to 100 rpm and the stirring speed is adjusted to 500 rpm. The mixture is stirred and stirred for 12 hours under these conditions. After stirring and mixing, elemental sulfur is uniformly adsorbed in 3DG to obtain a 3DG / S composite material.

[0075] S2, 3DG / S composite material, Ketjen Black, and LA133 were mixed in a mass ratio of 80:10:10. A mixed solvent consisting of isopropanol and water (volume ratio of isopropanol to water of 15:85) was added until the solid content of the solution was 25wt%. The mixture was stirred until homogeneous to obtain a slurry. The slurry was coated onto the surface of the positive electrode current collector and dried at 60℃ for 18h to obtain the positive electrode module. The thickness of the three-dimensional graphene-sulfur composite positive electrode layer in the positive electrode module was approximately 150μm.

[0076] S3. ZIF-8 material, LiTFSI, SBR, sodium dodecylbenzenesulfonate and DME are mixed uniformly in a mass ratio of 10:3:1:1:85 to obtain a mixed slurry. The mixed slurry is sprayed onto a lithium-carbon composite anode layer (the thickness of the lithium-carbon composite anode layer is 50μm) and baked at 80℃ for 10h to obtain an anode component. The thickness of the modification layer on the anode component is 10μm.

[0077] S4. Arrange the positive electrode assembly, Li6PS5Cl sulfide solid electrolyte, and negative electrode assembly according to... Figure 1 The structure is assembled and then packaged to obtain a solid-state lithium-sulfur battery.

[0078] The SEM image of the cross-section of the solid-state lithium-sulfur battery prepared in this embodiment is shown below. Figure 2 As shown, the current collector layer, the three-dimensional graphene and sulfur composite positive electrode layer, the sulfide solid electrolyte layer, the modification layer, and the lithium-carbon composite negative electrode layer are tightly bonded together.

[0079] Comparative Example 1 The lithium-sulfur battery in this comparative example has the following structure: a positive electrode current collector; a sulfur positive electrode layer disposed on one side of the positive electrode current collector; a solid electrolyte layer disposed on the side of the sulfur positive electrode layer away from the positive electrode current collector; and a lithium negative electrode layer disposed on the side of the solid electrolyte layer away from the sulfur positive electrode layer. The specific preparation method is as follows: S1. Mix elemental sulfur, Ketjen black, and LA133 in a mass ratio of 80:10:10, then add a mixed solvent of isopropanol and water (volume ratio of isopropanol and water is 15:85) until the solid content of the solution is 25wt%. Stir until the mixture is homogeneous to obtain a slurry. Coat the slurry onto the surface of the positive electrode current collector and dry it at 60℃ for 18h to obtain a positive electrode module. The thickness of the sulfur positive electrode layer in the positive electrode module is 150μm.

[0080] S2. Assemble the positive electrode component, Li6PS5Cl sulfide solid electrolyte and lithium-carbon composite negative electrode layer (the thickness of the lithium-carbon composite negative electrode layer is 50μm), and then encapsulate them to obtain a solid lithium-sulfur battery.

[0081] Comparative Example 2 The preparation method is basically the same as in Example 1, except that no modification layer is provided. The specific preparation method is as follows: S1, same as step S1 in Example 1.

[0082] S2, same as step S2 in Example 1.

[0083] S3. Assemble the positive electrode component, Li6PS5Cl sulfide solid electrolyte and lithium-carbon composite negative electrode layer (the thickness of the lithium-carbon composite negative electrode layer is 50μm), and then encapsulate them to obtain a solid lithium-sulfur battery.

[0084] Comparative Example 3 The process is essentially the same as in Example 1, except that the three-dimensional graphene and sulfur composite cathode layer is replaced with a sulfur cathode layer. The specific preparation method is as follows: S1. Mix elemental sulfur, Ketjen black, and LA133 in a mass ratio of 80:10:10, then add a mixed solvent of isopropanol and water (volume ratio of isopropanol and water is 15:85) until the solid content of the solution is 25wt%. Stir until the mixture is homogeneous to obtain a slurry. Coat the slurry onto the surface of the positive electrode current collector and dry it at 60℃ for 18h to obtain a positive electrode module. The thickness of the sulfur positive electrode layer in the positive electrode module is 150μm.

[0085] S2, the same as step S3 in Example 1.

[0086] S3, the same as step S4 in Example 1.

[0087] Example 2 In this embodiment, the mass ratio of three-dimensional graphene to sulfur in the positive electrode layer composed of three-dimensional graphene (the same three-dimensional graphene as in Example 1) is 15:85; the solid electrolyte is Li. 10 GeP2S 12The electrolyte is a sulfide solid electrolyte; the MOF material is MIL-53 with a D50 of 500 nm and a pore size of 1 Å; the lithium anode layer is a lithium-silicon alloy anode layer; the specific preparation method is as follows: S1. Three-dimensional graphene (3DG) and elemental sulfur are added to a reaction vessel and heated and stirred under vacuum conditions. During the heating process, the scraper speed is 50 rpm and the stirring speed is 200 rpm. When the temperature reaches 158℃, the scraper speed is adjusted to 100 rpm and the stirring speed is adjusted to 200 rpm. The mixture is stirred and stirred for 6 hours under these conditions. After stirring and mixing, elemental sulfur is uniformly adsorbed in 3DG to obtain a 3DG / S composite material.

[0088] S2. Mix 3DG / S composite material, Super P, and LA133 in a mass ratio of 70:20:10, then add a mixed solvent of isopropanol and water (volume ratio of isopropanol and water is 30:70) until the solid content of the solution is 35wt%. Stir until the mixture is uniform to obtain a slurry. Coat the slurry onto the surface of the positive electrode current collector and dry it at 55℃ for 24h to obtain the positive electrode component. The thickness of the three-dimensional graphene and sulfur composite positive electrode layer in the positive electrode component is 100μm.

[0089] S3. MOFs material, LiPF6, PVDF, polyvinylpyrrolidone and dimethyl ethyl ether are mixed uniformly in a mass ratio of 5:5:1:2:70 to obtain a mixed slurry. The mixed slurry is sprayed onto a lithium silicon alloy anode layer (the thickness of the lithium silicon alloy anode layer is 100 μm) and baked at 80℃ for 10 h to obtain an anode component. The thickness of the modification layer on the anode component is 40 μm.

[0090] S4, positive electrode component, Li 10 GeP2S 12 Sulfide solid electrolyte and negative electrode assembly according to Figure 1 The structure is assembled and then packaged to obtain a solid-state lithium-sulfur battery.

[0091] Example 3 In this embodiment, the mass ratio of three-dimensional graphene to sulfur in the positive electrode layer composed of three-dimensional graphene (the same three-dimensional graphene as in Example 1) is 32:68; the solid electrolyte is Li7P3S. 11 A sulfide solid electrolyte; the MOF material is Uio-67 with a D50 of 600 nm and a pore size of 2 Å; the lithium anode layer is a lithium metal anode layer; the specific preparation method is as follows: S1. Three-dimensional petal-shaped porous graphene (3DG) and elemental sulfur are added to a reaction vessel and heated and stirred under vacuum conditions. During the heating process, the scraper speed is 50 rpm and the stirring speed is 300 rpm. When the temperature reaches 160℃, the scraper speed is adjusted to 100 rpm and the stirring speed is adjusted to 600 rpm. The mixture is stirred and stirred for 3 hours under these conditions. After stirring and mixing, elemental sulfur is uniformly adsorbed in 3DG to obtain a 3DG / S composite material.

[0092] S2. Mix 3DG / S composite material, carbon nanotubes, and LA132 at a mass ratio of 85:10:5, then add a mixed solvent of isopropanol and water (volume ratio of isopropanol and water is 5:95) until the solid content of the solution is 15wt%. Stir until the mixture is homogeneous to obtain a slurry. Coat the slurry onto the surface of the positive electrode current collector and dry it at 65℃ for 12h to obtain the positive electrode component. The thickness of the three-dimensional graphene and sulfur composite positive electrode layer in the positive electrode component is 200μm.

[0093] S3. MOFs material, LiTFSI, PEO, sodium dodecyl sulfate and NMP are mixed uniformly in a mass ratio of 20:1:5:0.5:100 to obtain a mixed slurry. The mixed slurry is sprayed onto the lithium metal anode layer (the thickness of the lithium metal anode layer is 500μm) and baked at 80℃ for 10h to obtain the anode component. The thickness of the modification layer on the anode component is 5μm.

[0094] S4, The positive electrode component, Li7P3S 11 Sulfide solid electrolyte and negative electrode assembly according to Figure 1 The structure is assembled and then packaged to obtain a solid-state lithium-sulfur battery.

[0095] Example 4 In this embodiment, the mass ratio of three-dimensional graphene (the same as in Example 1) to elemental sulfur in the positive electrode layer is 20:80; the MOF material is ZIF-8 material with a D50 of 200 nm and a pore size of 0.4 Å; the solid electrolyte is Li6PS5Cl sulfide solid electrolyte; and the lithium negative electrode layer is a lithium-carbon composite negative electrode layer.

[0096] The solid-state lithium-sulfur battery is prepared using the following method in this embodiment: S1. Three-dimensional graphene (3DG) and elemental sulfur are added to a reaction vessel and heated and stirred under vacuum conditions. During the heating process, the scraper speed is 50 rpm and the stirring speed is 300 rpm. When the temperature reaches 160℃, the scraper speed is adjusted to 100 rpm and the stirring speed is adjusted to 500 rpm. The mixture is stirred and stirred for 12 hours under these conditions. After stirring and mixing, elemental sulfur is uniformly adsorbed in 3DG to obtain a 3DG / S composite material.

[0097] S2. Mix 3DG / S composite material, Li6PS5Cl, and Ketjen black in a mass ratio of 54:36:9, then add PTFE (the mass ratio of 3DG / S composite material to PTFE is 54:1) and mix well to obtain a mixture. Hot-press the mixture onto the positive electrode current collector to obtain a positive electrode assembly. The thickness of the three-dimensional graphene and sulfur composite positive electrode layer in the positive electrode assembly is about 150 μm.

[0098] S3. ZIF-8 material, LiTFSI, SBR, sodium dodecylbenzenesulfonate and DME are mixed uniformly in a mass ratio of 10:3:1:1:85 to obtain a mixed slurry. The mixed slurry is sprayed onto a lithium-carbon composite anode layer (the thickness of the lithium-carbon composite anode layer is 50μm) and baked at 80℃ for 10h to obtain an anode component. The thickness of the modification layer on the anode component is 10μm.

[0099] S4. Arrange the positive electrode assembly, Li6PS5Cl sulfide solid electrolyte, and negative electrode assembly according to... Figure 1 The structure is assembled and then packaged to obtain a solid-state lithium-sulfur battery.

[0100] Example 5 In this embodiment, the mass ratio of three-dimensional graphene to sulfur in the positive electrode layer composed of three-dimensional graphene (the same three-dimensional graphene as in Example 1) is 15:85; the solid electrolyte is Li. 10 GeP2S 12 The electrolyte is a sulfide solid electrolyte; the MOF material is MIL-53 with a D50 of 500 nm and a pore size of 1 Å; the lithium anode layer is a lithium-silicon alloy anode layer; the specific preparation method is as follows: S1. Three-dimensional graphene (3DG) and elemental sulfur are added to a reaction vessel and heated and stirred under vacuum conditions. During the heating process, the scraper speed is 50 rpm and the stirring speed is 200 rpm. When the temperature reaches 155℃, the scraper speed is adjusted to 100 rpm and the stirring speed is adjusted to 200 rpm. The mixture is stirred and stirred for 6 hours under these conditions. After stirring and mixing, elemental sulfur is uniformly adsorbed in 3DG to obtain a 3DG / S composite material.

[0101] S2, 3DG / S composite material, Li 10 GeP2S 12 Super P is mixed at a mass ratio of 40:40:18, and then PTFE (the mass ratio of 3DG / S composite material to PTFE is 40:2) is added and mixed to obtain a mixture. The mixture is then hot-pressed onto the positive electrode current collector to obtain a positive electrode assembly. The thickness of the three-dimensional graphene and sulfur composite positive electrode layer in the positive electrode assembly is about 100μm.

[0102] S3. MOFs material, LiPF6, PVDF, polyvinylpyrrolidone and dimethyl ethyl ether are mixed uniformly in a mass ratio of 5:5:1:2:70 to obtain a mixed slurry. The mixed slurry is sprayed onto a lithium silicon alloy anode layer (the thickness of the lithium silicon alloy anode layer is 100 μm) and baked at 80℃ for 10 h to obtain an anode component. The thickness of the modification layer on the anode component is 40 μm.

[0103] S4, positive electrode component, Li 10 GeP2S 12 Sulfide solid electrolyte and negative electrode assembly according to Figure 1 The structure is assembled and then packaged to obtain a solid-state lithium-sulfur battery.

[0104] Example 6 In this embodiment, the mass ratio of three-dimensional graphene to sulfur in the positive electrode layer composed of three-dimensional graphene (the same three-dimensional graphene as in Example 1) is 32:68; the solid electrolyte is Li7P3S. 11 A sulfide solid electrolyte; the MOF material is Uio-67 with a D50 of 600 nm and a pore size of 2 Å; the lithium anode layer is a lithium metal anode layer; the specific preparation method is as follows: S1. Three-dimensional petal-shaped porous graphene (3DG) and elemental sulfur are added to a reaction vessel and heated and stirred under vacuum conditions. During the heating process, the scraper speed is 50 rpm and the stirring speed is 300 rpm. When the temperature reaches 160℃, the scraper speed is adjusted to 100 rpm and the stirring speed is adjusted to 600 rpm. The mixture is stirred and stirred for 3 hours under these conditions. After stirring and mixing, elemental sulfur is uniformly adsorbed in 3DG to obtain a 3DG / S composite material.

[0105] S2, 3DG / S composite material, Li7P3S 11 Carbon nanotubes are mixed at a mass ratio of 65:25:9.5, and then PTFE (the mass ratio of 3DG / S composite material to PTFE is 65:0.5) is added and mixed to obtain a mixture. The mixture is electrostatically sprayed onto the positive electrode current collector to obtain a positive electrode component. The thickness of the three-dimensional graphene and sulfur composite positive electrode layer in the positive electrode component is about 200 μm.

[0106] S3. MOFs material, LiTFSI, PEO, sodium dodecyl sulfate and NMP are mixed uniformly in a mass ratio of 20:1:5:0.5:100 to obtain a mixed slurry. The mixed slurry is sprayed onto the lithium metal anode layer (the thickness of the lithium metal anode layer is 500μm) and baked at 80℃ for 10h to obtain the anode component. The thickness of the modification layer on the anode component is 5μm.

[0107] S4, The positive electrode component, Li7P3S 11 Sulfide solid electrolyte and negative electrode assembly according to Figure 1 The structure is assembled and then packaged to obtain a solid-state lithium-sulfur battery.

[0108] The solid lithium-sulfur batteries from Examples 1-6 and Comparative Examples 1-3 were left to stand for 12 hours before performance testing was conducted. The specific test conditions are as follows.

[0109] AC impedance test: Connect the solid-state battery to the electrochemical workstation and set the test frequency range to 10. 6 ~10 -2 The impedance test was conducted at room temperature with an AC disturbance voltage of 5~10 mV and a frequency of Hz. After the test, the interface resistance of the artificial SEI layer can be calculated by fitting the semicircle of the high-frequency region in the Nyquist plot. The test results are shown in Table 1.

[0110] Loop testing: At 25℃, constant current charging and discharging were used, with a charging and discharging voltage range of 1.7-2.6V and a charging and discharging rate of 0.2C. The initial capacity of the battery was recorded as C0. One full charge and discharge cycle was recorded as one cycle. The charging and discharging were performed according to the above method, and the battery capacity was tested after each cycle until the battery capacity reached 80% of C0 or the battery experienced a short circuit. The number of cycles at this point was recorded, and the first efficiency was calculated. The test results are shown in Table 1.

[0111] Table 1 As can be seen from the data in Table 1, in Comparative Example 1, there was no three-dimensional graphene in the positive electrode layer and no modification layer was set on the negative electrode side. The resulting solid-state lithium-sulfur battery had poor initial efficiency and cycle performance, and high AC impedance. In Comparative Example 2, compared to Comparative Example 1, a modification layer was set on the negative electrode side. The resulting solid-state lithium-sulfur battery showed some improvement in initial efficiency and cycle performance, and a slight decrease in impedance, but the overall performance was still poor. In Comparative Example 3, compared to Comparative Example 1, three-dimensional graphene was introduced into the positive electrode layer. The resulting solid-state lithium-sulfur battery showed some improvement in initial efficiency and cycle performance, and a slight decrease in impedance, but the overall performance was still poor. In Example 1, three-dimensional graphene was introduced into the electrode layer and a modification layer was set on the negative electrode side. The resulting solid-state lithium-sulfur battery showed a significant improvement in initial efficiency and cycle performance compared to Comparative Examples 1-3, and lower impedance, resulting in superior overall battery performance. In Examples 2-3, adjusting the process parameters of the solid-state lithium-sulfur battery caused some fluctuation in battery performance, but the overall performance was still superior. In Examples 4-6, the cathode components were prepared by dry method. The first efficiency and cycle performance of the corresponding assembled batteries may fluctuate slightly, but the overall performance is better.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lithium-sulfur solid-state battery, characterized in that, Including those set up in a stacked manner: Positive current collector; A three-dimensional graphene-sulfur composite cathode layer is disposed on one side of the cathode current collector; A solid electrolyte layer is disposed on the side of the three-dimensional graphene and sulfur composite positive electrode layer away from the positive electrode current collector; A modification layer is disposed on the side of the solid electrolyte layer away from the positive electrode layer composed of three-dimensional graphene and sulfur; A lithium anode layer is disposed on the side of the modification layer away from the solid electrolyte layer; Wherein: the modification layer is a modification layer containing MOFs material.

2. The lithium-sulfur solid-state battery according to claim 1, characterized in that, The thickness of the three-dimensional graphene-sulfur composite cathode layer is 50~250μm; And / or: Three-dimensional graphene is petal-shaped porous graphene; And / or: The specific surface area of ​​three-dimensional graphene is 100~5000 m² 2 / g; And / or: Three-dimensional graphene contains micropores and / or mesopores.

3. The lithium-sulfur solid-state battery according to claim 1 or 2, characterized in that, The method for preparing the three-dimensional graphene-sulfur composite cathode layer includes the following steps: S1. Three-dimensional graphene and elemental sulfur are heated and stirred under vacuum conditions to obtain a three-dimensional graphene-sulfur composite material. Using either step S2-1 or S2-2, the three-dimensional graphene-sulfur composite material is prepared into a three-dimensional graphene-sulfur composite cathode layer: S2-1. Mix the three-dimensional graphene-sulfur composite material, binder, and conductive agent, add solvent, and prepare a slurry; coat the slurry onto the surface of the positive electrode current collector, and after drying, obtain the three-dimensional graphene-sulfur composite positive electrode layer. S2-2. After mixing the three-dimensional graphene-sulfur composite material, solid electrolyte, and conductive agent, a binder is added and mixed to obtain a mixture. The mixture is then hot-pressed or electrostatically sprayed onto the surface of the positive electrode current collector to obtain the three-dimensional graphene-sulfur composite positive electrode layer.

4. The lithium-sulfur solid-state battery according to claim 3, characterized in that, In step S1, The mass ratio of three-dimensional graphene to elemental sulfur is 10:90 to 40:

60. And / or: The heating and stirring speed is 200~600 rpm, the heating and stirring temperature is 155~160℃, and the heating and stirring time is 2~24h.

5. The lithium-sulfur solid-state battery according to claim 3, characterized in that, In step S2-1, the binder is selected from one or both of acrylonitrile copolymer LA133 and acrylonitrile copolymer LA132; the solvent is a mixed solvent composed of isopropanol and water in a volume ratio of (5~30):(70~95); the conductive agent is selected from one or more of Ketjen Black, carbon nanotubes, Super P, and graphene; the mass ratio of the three-dimensional graphene-sulfur composite material, the conductive agent, and the binder is (70~85):(10~20):(5~10); the solid content of the slurry is 15~35 wt% when the solvent is added. And / or: In step S2-2, the binder is polytetrafluoroethylene, and the conductive agent is selected from one or more of Ketjen Black, carbon nanotubes, Super P, and graphene; the solid electrolyte is selected from Li6PS5Cl, Li6PS5Br, Li6PS5I, and Li 10 GeP2S 12 Li7P3S 11 75Li₂S·₂₅P₂S₅ and Li 10 SiP2S 12 One of them; the mass ratio of the three-dimensional graphene-sulfur composite material, solid electrolyte, conductive agent and binder is (40~70):(20~40):(1~20):(0.5~5).

6. The lithium-sulfur solid-state battery according to claim 3, characterized in that, The solid electrolyte layer is a sulfide solid electrolyte layer, specifically selected from Li6PS5Cl, Li6PS5Br, Li6PS5I, and Li 10 GeP2S 12 Li7P3S 11 75Li₂S·₂₅P₂S₅ and Li 10 SiP2S 12 One of them; And / or: The lithium anode layer is selected from one or more of metallic lithium anode layer, lithium alloy anode layer and lithium-carbon composite anode layer; the thickness of the lithium alloy anode layer is 5~500μm. And / or: The thickness of the modified layer is 1~50μm.

7. The lithium-sulfur solid-state battery according to claim 1 or 6, characterized in that, The modified layer comprises the following raw materials in the following mass ratios: 1-20 parts MOFs material, 1-5 parts lithium salt, 1-5 parts binder, and 0.5-2 parts additives.

8. The lithium-sulfur solid-state battery according to claim 6, characterized in that, The MOFs material is selected from one or more of the ZIF series, IRMOF series, MIL series, NU series, UiO series, and PCN series; the ZIF series is selected from one or more of ZIF-7, ZIF-8, ZIF-63, ZIF-67, ZIF-71, and ZIF-90; the IRMOF series is selected from one or more of IRMOF-1, IRMOF-3, IRMOF-6, IRMOF-8, IRMOF-9, and IRMOF-10; the MIL series is selected from MIL-53, MIL-88, and MIL- 96, at least one of MIL-100, MIL-101, and MIL-125; the NU series is selected from one or more of NU-100, NU-109, NU-110, NU-111, NU-125, and NU-901; the UiO series is selected from one or more of UiO-67, UiO-68, UiO-76, UiO-77, and UiO-84; the PCN series is selected from one or more of PCN-14, PCN-200, PCN-221, PCN-222, PCN-223, and PCN-250; And / or: The lithium salt is selected from one or more of lithium fluoride, lithium nitride, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium perchlorate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium carbonate, lithium oxalate, lithium bicarbonate, lithium acetate, lithium halide, lithium sulfate, and lithium hydroxide. And / or: The adhesive is selected from one or more of the following: polyvinyl alcohol, polyethylene oxide, polybutene-styrene, polystyrene-butadiene copolymer, polyvinylidene fluoride, polystyrene, polycarboxymethyl cellulose, polyurethane, methacrylate, epoxy resin and its derivatives, styrene-butadiene rubber, and sodium carboxymethyl cellulose; And / or: More preferably, the additive is selected from one or more of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and hexadecyltrimethylammonium bromide.

9. The lithium-sulfur solid-state battery according to claim 6, characterized in that, The method for preparing the modified layer includes the following steps: MOF materials, lithium salts, binders and additives are mixed and then a solvent is added to prepare a slurry. The slurry is coated onto the lithium anode layer and dried to obtain the modified layer.

10. The method for preparing a lithium-sulfur solid-state battery according to any one of claims 1 to 9, characterized in that, Includes the following steps: A three-dimensional graphene-sulfur composite positive electrode layer is prepared on the positive electrode current collector to obtain the positive electrode side component; a modification layer is prepared on the lithium negative electrode layer to obtain the negative electrode side component; the positive electrode side component, solid electrolyte, and negative electrode side component are assembled and packaged to obtain the solid lithium-sulfur battery.

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