A solid-state lithium-sulfur battery with integrated positive electrode and electrolyte and its preparation method

Abstract

This invention discloses a solid-state lithium-sulfur battery with an integrated positive electrode and electrolyte, and its preparation method. A polymer containing strongly polar groups and an inorganic fluorinated lithium salt are dissolved in an organic solvent I, and then an inorganic solid-state electrolyte is added. After high-temperature and high-intensity stirring to obtain a homogeneous solution A, solution B is obtained. Lithium polysulfide is dissolved in a high-dielectric-constant solvent II and added to solution A. Solution B is cast onto a porous conductive substrate, and after static defoaming, high-temperature infiltration, and freeze-drying, an integrated positive electrode / electrolyte structure is obtained. The integrated positive electrode / electrolyte structure is paired with lithium metal to assemble the solid-state lithium-sulfur battery with an integrated positive electrode and electrolyte. The method of this invention is controllable, simple to operate, and easy to implement. The prepared integrated positive electrode / electrolyte structure has multiple advantages, including good interfacial compatibility, high sulfur loading, outstanding sulfur suppression ability, structural stability, and dual electro-ionic conductivity.

Description

Technical Field

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

[0002] The energy crisis and environmental problems caused by the consumption of fossil fuels are becoming increasingly serious, making the development of green, efficient, and stable energy storage devices a current research hotspot. Lithium-sulfur batteries have attracted much attention due to their advantages such as high theoretical energy density, wide availability of raw materials, and environmental friendliness. However, problems such as the flammability of organic electrolytes and dendrite formation in lithium metal anodes lead to poor battery safety and short cycle life. Using solid electrolytes can fundamentally eliminate these hidden dangers; however, the solid-solid interface between the electrolyte and the electrode has poor contact and high interfacial impedance. Moreover, traditional sulfur cathodes experience significant volume expansion during the lithiation reaction, which further impairs the stability of the cathode / electrolyte interface and affects ion transport and charge transfer processes.

[0003] Existing research typically involves pre-doping a portion of the solid electrolyte component into the cathode to construct a cathode structure with dual electron / ion conduction, thereby enhancing interfacial contact and improving interfacial compatibility. However, due to insufficient electrolyte doping and simple doping methods, the cathode and electrolyte are not fully integrated, resulting in limited improvement of the interface. Moreover, this method comes at the cost of reducing the content of the active material in the cathode, affecting the actual specific capacity of the electrode. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a solid-state lithium-sulfur battery with an integrated cathode and electrolyte and its preparation method, which addresses the shortcomings of the prior art and solves the technical problems of low ionic conductivity of solid electrolyte, low loading and low utilization of active material on sulfur cathode, and high interfacial impedance between solid electrolyte and sulfur cathode, thereby improving the electrochemical performance of lithium-sulfur battery.

[0005] The present invention adopts the following technical solution:

[0006] A method for preparing a solid-state lithium-sulfur battery with an integrated positive electrode and electrolyte includes the following steps:

[0007] S1. The polymer containing strong polar groups and the inorganic fluorinated lithium salt are dissolved in organic solvent I. After mixing evenly, the inorganic solid electrolyte is added. The inorganic solid electrolyte is dispersed evenly by high temperature and high intensity stirring to obtain solution A.

[0008] S2. Dissolve lithium polysulfide in a high dielectric constant organic solvent II under high temperature stirring to form a lithium polysulfide solution with a concentration of 0.8-4.0 mol / L. Add the lithium polysulfide solution to solution A to obtain solution B.

[0009] S3. Solution B is cast onto a porous conductive substrate, and after static defoaming, high-temperature infiltration, and freeze-drying, a positive electrode / electrolyte integrated structure with a thickness of 100-300 μm is obtained.

[0010] S4. Pair the integrated positive electrode / electrolyte structure with lithium metal to assemble a solid-state lithium-sulfur battery with an integrated positive electrode and electrolyte.

[0011] Specifically, in step S1, the mass ratio of the polymer containing strong polar groups to the inorganic fluorinated lithium salt is (4-1):1, and the solid-liquid ratio of the mixture of the polymer containing strong polar groups and the inorganic fluorinated lithium salt to the organic solvent I is (0.04-0.2):1 g / ml.

[0012] Furthermore, organic solvent I includes at least one of acetonitrile, tetrahydrofuran, dimethylformamide, anisole, chloroform, dichloroethane, benzene, toluene, xylene, ethylbenzene, styrene, cyclohexane, cyclohexanone, chlorobenzene, dichloromethane, methanol, ethanol, ethyl acetate, butyl acetate, acetone, and carbon disulfide.

[0013] Inorganic fluorinated lithium salts include at least one of LiTFSI, LiFSI, LiODFB, LiPF6, LiBF4, LiCF3SO3, LiAsF6, LiTf, LiOTf, LiBC2O4F2, LiN(FSO2)2, LiN(CF3SO2)2, LiF, LiFAP, LiFAB, and LiTFSM.

[0014] Specifically, in step S1, the mass ratio of the inorganic solid electrolyte to the polymer containing strong polar groups is (0.05~0.20):1.

[0015] Furthermore, inorganic solid electrolytes include sulfide solid electrolytes and oxide electrolytes. Sulfide solid electrolytes include at least one of Li2S-P2S5 glass and ceramic glass, thio-LiSiCON-like solid solution and anion-doped Li2S-P2S5; oxide solid electrolytes include at least one of perovskite type, NASICON type and garnet type.

[0016] Polymer materials containing strongly polar groups include at least one of polyethylene oxide, polyvinylidene fluoride, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, and polyvinylidene fluoride-hexafluoropropylene copolymer.

[0017] Specifically, in step S1, the stirring temperature after adding the inorganic solid electrolyte is 60-80℃, and the stirring intensity is 500-2000 rpm.

[0018] Specifically, in step S2, the chemical formula of lithium polysulfide is: Li₂S x4≤x≤8, the high-temperature stirring temperature is 40~80℃, and the high dielectric constant organic solvent II includes at least one of N,N-dimethylacetamide, N-methylacetamide, acetamide, N,N-dimethylformamide, N-methylformamide, formamide, caprolactam, dimethyl sulfoxide, malononitrile, and tetramethylurea.

[0019] Specifically, in step S3, the thickness of the porous conductive substrate is less than the total thickness of the integrated positive electrode / electrolyte structure, the polysulfides have a concentration gradient distribution in the integrated positive electrode / electrolyte structure, and the concentration of polysulfides near the negative electrode surface tends to be zero.

[0020] Specifically, in step S3, the porous conductive substrate includes at least one of carbon cloth, carbon paper, nickel foam, aluminum foam, carbon nanotube film, graphene foam, and graphene aerogel.

[0021] Another technical solution of the present invention is a solid-state lithium-sulfur battery with an integrated positive electrode and electrolyte.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] A method for preparing a solid-state lithium-sulfur battery with an integrated cathode and electrolyte involves mixing a solid composite electrolyte slurry with a high-concentration lithium polysulfide solution and casting it onto a porous conductive substrate. A freeze-drying process is then performed to form an integrated cathode / electrolyte structure, which is then directly assembled with lithium to form a solid-state lithium-sulfur battery. The concentration of the lithium polysulfide solution is 0.8–4.0 mol / L, and the thickness of the integrated cathode / electrolyte structure is 100–300 μm. This allows for the introduction of more sulfur species into the integrated structure, ensuring a high loading capacity of active material per unit area. This invention features a controllable process, simple operation, and ease of implementation. It cleverly integrates the cathode and electrolyte into a single unit, maximizing contact between the electrolyte components and the positive electrode active material. This optimizes ion transport channels, reduces interfacial charge transfer impedance, improves interfacial compatibility, and increases the utilization rate of the active material.

[0024] Furthermore, in order to ensure the structural stability of the integrated structure and to fully realize its intended function, this invention limits the mass ratio of polymer to lithium salt, the solid-liquid ratio of the polymer / lithium salt mixture to organic solvent I, and the mass ratio of inorganic solid electrolyte to polymer.

[0025] Furthermore, the selected organic solvent I readily dissolves polar polymer materials, while the inorganic solid electrolyte can be uniformly dispersed within it; in addition, these solvents have a certain degree of volatility, making them easy to dry and remove later; the selected inorganic fluorinated lithium salt has a low lattice energy, is easy to dissociate, and has good chemical stability; the fluorinated anions it provides can also participate in the formation of a passivation film on the lithium anode surface, further preventing the corrosion of lithium by a small amount of lithium polysulfides that may diffuse to the anode.

[0026] Furthermore, in order to ensure the structural stability of the integrated structure and to fully realize its intended function, this invention limits the mass ratio of inorganic solid electrolyte to polymer.

[0027] Furthermore, the selected inorganic solid electrolyte possesses high ionic conductivity, primarily used to improve the ionic conductivity of the integrated structure while simultaneously enhancing the mechanical strength of the polymer matrix. The chosen polymer, containing strongly polar groups, readily dissociates the lithium salt, facilitating lithium-ion conduction. Simultaneously, it exerts a strong chemical clamping effect on the active material, lithium polysulfides, preventing its extraction from the positive electrode and diffusion to the negative electrode to react with lithium, thus suppressing the shuttle effect. The selected lithium polysulfides are all long-chain polysulfides, readily soluble in most organic solvents. Using lithium polysulfides as the active material introduces an additional lithium source into the integrated structure, increasing lithium-ion concentration and improving ionic conductivity. Moreover, the conversion of lithium polysulfides to lithium sulfides does not involve the significant volume expansion seen in the conversion of sulfur to lithium sulfides, which is beneficial for electrode structural stability. Limiting the stirring temperature of the lithium polysulfide solution allows for more rapid and complete dissolution of lithium polysulfides in the organic solvent.

[0028] Furthermore, in order to ensure that the inorganic solid electrolyte is fully, uniformly, and stably dispersed, the high stirring temperature and high stirring intensity after the addition of the inorganic solid electrolyte are limited.

[0029] Furthermore, organic solvent II is selected because it is a high dielectric constant solvent, which has good solubility for lithium polysulfides and can be used to prepare high-concentration lithium polysulfide solutions. This is a key technology for improving the loading of active materials in the integrated structure.

[0030] Furthermore, limiting the thickness of the porous conductive substrate to less than the total thickness of the integrated structure is to prevent direct electrical contact between the positive and negative electrodes, which could lead to an internal short circuit. Polysulfides form a concentration gradient distribution in the integrated positive / electrolyte structure, with the concentration approaching zero near the surface of the negative electrode. This is to prevent polysulfides from directly contacting the lithium negative electrode and causing lithium corrosion.

[0031] Furthermore, the selected porous conductive substrate can serve as both an electronic conductor and a physical support, providing an electronic conduction path and supporting the stable molding of the integrated structure.

[0032] A solid-state lithium-sulfur battery with an integrated cathode and electrolyte structure is disclosed. The integrated cathode / electrolyte structure prepared by the method of this invention has multiple advantages, such as low interface impedance, high active material loading, outstanding ability to confine sulfur species, structural stability, and dual electrical / ionic conductivity. It is beneficial to improve the overall energy density, cycle stability and rate performance of solid-state lithium-sulfur batteries.

[0033] In summary, the method of this invention is controllable, easy to operate, and readily achievable. It cleverly integrates the high-sulfur-loaded cathode and the composite electrolyte into one, effectively solving various problems existing in traditional solid-state lithium-sulfur batteries, such as the low ionic conductivity of the solid electrolyte, the low loading and utilization rate of active materials on the sulfur cathode, and the high interfacial impedance between the solid electrolyte and the sulfur cathode, thereby improving the overall electrochemical and safety performance of solid-state lithium-sulfur batteries.

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0035] Figure 1 The cycling performance diagram is shown for the integrated solid-state lithium-sulfur battery prepared in Example 1.

[0036] Figure 2 Voltage-capacity diagram of the integrated solid-state lithium-sulfur battery prepared in Example 1;

[0037] Figure 3 The cycling performance of a conventional solid-state lithium-sulfur battery prepared for Comparative Example 1 is shown in the figure. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0040] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0041] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0042] Unless otherwise specified, the components or preferred components involved in this invention can be combined with each other to form new technical solutions.

[0043] In this invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been listed in this document, and "6~22" is simply an abbreviation of these numerical combinations.

[0044] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0045] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0046] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0047] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0048] This invention discloses a method for preparing a solid-state lithium-sulfur battery with an integrated positive electrode and electrolyte, comprising the following steps:

[0049] S1. Dissolve the polymer containing strong polar groups and the inorganic fluorinated lithium salt in organic solvent I, mix them evenly, add the inorganic solid electrolyte, and disperse them evenly under high temperature (60-80℃) and high stirring intensity (500-2000rpm) to obtain solution A;

[0050] The mass ratio of polymer to inorganic fluorinated lithium salt is (4-1):1, the solid-liquid ratio of polymer / lithium salt mixture to organic solvent I is (0.04-0.2):1 g / ml, and the mass ratio of inorganic solid electrolyte to polymer is (0.05-0.20):1.

[0051] Polymer materials containing strongly polar groups include at least one of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), polyvinyl acetate (PVA), and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP).

[0052] Inorganic fluorinated lithium salts include at least one of LiTFSI, LiFSI, LiODFB, LiPF6, LiBF4, LiCF3SO3, LiAsF6, LiTf, LiOTf, LiBC2O4F2, LiN(FSO2)2, LiN(CF3SO2)2, LiF, LiFAP, LiFAB, and LiTFSM. The selected inorganic fluorinated lithium salts have low lattice energy, are easy to dissociate, and have good chemical stability. The fluorinated anions they provide can also participate in the formation of a passivation film on the lithium anode surface, further preventing the corrosion of lithium by a small amount of lithium polysulfides that may diffuse to the anode.

[0053] Organic solvent I includes at least one of acetonitrile, tetrahydrofuran, dimethylformamide, anisole, chloroform, dichloroethane, benzene, toluene, xylene, ethylbenzene, styrene, cyclohexane, cyclohexanone, chlorobenzene, dichloromethane, methanol, ethanol, ethyl acetate, butyl acetate, acetone, and carbon disulfide.

[0054] Inorganic solid electrolytes include sulfide solid electrolytes and oxide electrolytes. Sulfide solid electrolytes include at least one of Li2S-P2S5 glass and ceramic glass, thio-LiSiCON-like solid solutions and anion-doped Li2S-P2S5. Oxide solid electrolytes include at least one of perovskite type, NASICON type and garnet type.

[0055] S2. Dissolve lithium polysulfide in a high dielectric constant organic solvent II under high temperature stirring to form a lithium polysulfide solution with a concentration of 0.8-4.0 mol / L. Add the solution to solution A to obtain solution B.

[0056] The chemical formula of lithium polysulfide is: Li₂S x , 4≤x≤8, including at least one of Li2S4, Li2S5, Li2S6, Li2S7 and Li2S8.

[0057] The concentration of the lithium polysulfide solution is 0.8–4.0 mol / L, and the stirring temperature of the lithium polysulfide solution is 40–80℃ to accelerate the complete dissolution of lithium polysulfides.

[0058] The high dielectric constant organic solvent II includes at least one of N,N-dimethylacetamide, N-methylacetamide, acetamide, N,N-dimethylformamide, N-methylformamide, formamide, caprolactam, dimethyl sulfoxide, malononitrile, and tetramethylurea. All organic solvents II are high dielectric constant solvents and have good solubility for lithium polysulfides, enabling the preparation of high-concentration lithium polysulfide solutions. This is a key technology for improving the loading of active materials in integrated structures.

[0059] S3. Solution B is cast onto a porous conductive substrate, and after standing to remove bubbles (6-24h), high-temperature infiltration (40-80℃), and freeze-drying (12-48h), a positive electrode / electrolyte integrated structure with a thickness of 100-300μm is obtained.

[0060] The thickness of the porous conductive substrate is less than the total thickness of the integrated positive electrode / electrolyte structure. Polysulfides have a concentration gradient distribution in the integrated positive electrode / electrolyte structure, and the concentration of polysulfides near the negative electrode surface tends to be zero.

[0061] The porous conductive substrate includes at least one of carbon cloth, carbon paper, nickel foam, aluminum foam, carbon nanotube film, graphene foam, and graphene aerogel.

[0062] S4. The integrated positive electrode / electrolyte structure is directly paired with lithium metal to assemble a solid-state lithium-sulfur battery.

[0063] The solid-state lithium-sulfur battery with integrated cathode electrolyte prepared by the method of this invention has multiple advantages such as low interface impedance, high active material loading, outstanding ability to confine sulfur species, stable structure, and dual conduction of electricity and ions. The initial specific capacity reaches 896.2-1188.4 mAh / g, the specific capacity after cycling reaches 391.4-507.7 mAh / g, and the average coulombic efficiency reaches 99.21%-99.58%.

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0065] Example 1

[0066] A method for preparing an integrated cathode / electrolyte solid-state lithium-sulfur battery includes the following steps:

[0067] S1. Dissolve PEO and LiTFSI in acetonitrile at a mass ratio of 2.5:1 (solid-liquid ratio 0.04 g / ml), then add 10 wt% (compared to PEO) of LLZTO, and stir evenly at 60℃ and 2000 rpm to obtain solution A.

[0068] S2. Elemental sulfur and lithium sulfide are mixed at a molar ratio of 7:1 and reacted and dissolved completely in N,N-dimethylacetamide at 45°C to obtain a 1.2M Li₂S₈ solution. This solution is then added to solution A to obtain solution B.

[0069] S3. Solution B is poured onto conductive carbon cloth, and after standing to remove bubbles, high-temperature infiltration, and freeze-drying, a positive electrode / electrolyte integrated structure with a thickness of 200μm is obtained.

[0070] S4. The integrated structure and lithium sheet are stacked in a vacuum glove box and sealed in a battery case to obtain a solid lithium-sulfur battery.

[0071] Example 2

[0072] The mass ratio of PVDF to LiFSI was 3:1, organic solvent I was tetrahydrofuran, the solid-liquid ratio was 0.1 g / ml, the amount of LATP added was 5 wt%, elemental sulfur and lithium sulfide were in a molar ratio of 5:1, organic solvent II was dimethyl sulfoxide, the concentration of Li₂S₆ solution was 1.8 M, the conductive substrate was graphene foam, and the thickness of the monolithic structure was 250 μm. The remaining process steps and conditions were the same as in Example 1.

[0073] Example 3

[0074] The mass ratio of PEO to LiTFSI was 4:1, the solid-liquid ratio of the PEO / LiTFSI mixture to acetonitrile was 0.2:1, the amount of LLZTO added was 20% (compared to PEO), the stirring temperature of solution A was 70℃, the stirring speed was 1500 rpm, the concentration of Li2S8 solution was 0.8 mol / L, the stirring temperature was 40℃, and the thickness of the monolithic structure was 100 μm. The remaining process steps and conditions were the same as in Example 1.

[0075] Example 4

[0076] The mass ratio of PVDF to LiFSI was 1:1, the solid-liquid ratio of the PVDF / LiFSI mixture to tetrahydrofuran was 0.04:1, the amount of LATP added was 5% (compared to PVDF), the stirring temperature of solution A was 80℃, and the stirring speed was 500 rpm; the concentration of Li2S8 solution was 4 mol / L, and the stirring temperature was 80℃; the thickness of the monolithic structure was 300 μm. The remaining process steps and conditions were the same as in Example 2.

[0077] Comparative Example 1

[0078] Elemental sulfur and mesoporous carbon were thoroughly ground and mixed, and then sintered at high temperature to obtain a sulfur-carbon composite material (sulfur content ~70%). The sulfur-carbon composite material, SP, and PVDF were mixed evenly in NMP at a mass ratio of 8:1:1 and coated onto the surface of aluminum foil to obtain a conventional sulfur cathode.

[0079] PEO, LiTFSI, and LLZTO are thoroughly stirred in acetonitrile until homogeneous, poured into a polytetrafluoroethylene mold, and dried to obtain a traditional solid electrolyte.

[0080] The sulfur cathode, solid electrolyte, and lithium sheet are stacked sequentially in a vacuum glove box and sealed in a battery case to obtain a solid lithium-sulfur battery.

[0081] Table 1 Test results of the examples and comparative examples

[0082] Initial specific capacity mAh / g Specific capacity after cycling (mAh / g) Average Coulomb efficiency % Example 1 1188.4 507.7 99.58 Example 2 896.2 391.4 99.21 Comparative Example 1 523.9 5.9 95.42

[0083] The lithium-sulfur batteries obtained above were subjected to constant current charge-discharge tests at a rate of 0.1C, a voltage window of 1.7–2.8V, and 100 cycles. The results are summarized in Table 1. Figure 1 , Figure 2 and Figure 3 .

[0084] As can be seen, compared with solid-state lithium-sulfur batteries made using traditional methods, the integrated cathode / electrolyte solid-state lithium-sulfur battery made using the method of this invention has significant advantages in both reversible capacity and cycle stability, and exhibits excellent overall battery performance.

[0085] In summary, this invention provides a solid-state lithium-sulfur battery with an integrated cathode and electrolyte and its preparation method. The prepared integrated cathode / electrolyte structure has multiple advantages, including good interfacial compatibility, high sulfur loading, outstanding sulfur suppression capability, structural stability, and dual electro-ionic conductivity. It can effectively solve various problems existing in traditional solid-state lithium-sulfur batteries, such as the low ionic conductivity of the solid electrolyte, the low loading and utilization rate of active materials on the sulfur cathode, and the high interfacial impedance between the solid electrolyte and the sulfur cathode. This improves the overall energy density, cycle stability, and rate performance of the solid-state lithium-sulfur battery, while ensuring good battery safety performance.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a positive electrolyte-integrated solid-state lithium-sulfur battery, characterized by, The method comprises the following steps: S1, dissolving the polymer containing strong polar groups and the inorganic fluorine-containing lithium salt in the organic solvent I, adding the inorganic solid electrolyte after mixing uniformly, uniformly dispersing the inorganic solid electrolyte through high-temperature and high-intensity stirring, and obtaining solution A; S2, dissolving lithium polysulfide in a high-dielectric-constant organic solvent II at high temperature and stirring to form a lithium polysulfide solution with a concentration of 0.8-4.0 mol / L, adding the lithium polysulfide solution into solution A to obtain solution B; S3, pouring solution B on a porous conductive substrate, removing bubbles through standing, high-temperature infiltration, and freeze-drying to obtain a positive electrode / electrolyte integrated structure with a thickness of 100-300 μm, the thickness of the porous conductive substrate being less than the total thickness of the positive electrode / electrolyte integrated structure, the polysulfide having a concentration gradient distribution in the positive electrode / electrolyte integrated structure, and the concentration of the polysulfide near the surface of the negative electrode tending to zero; S4, directly pairing the positive electrode / electrolyte integrated structure with lithium metal to assemble a positive electrode / electrolyte integrated solid-state lithium-sulfur battery.

2. The method for preparing a solid-state lithium-sulfur battery with integrated positive electrode and electrolyte according to claim 1, characterized in that, In step S1, the mass ratio of the polymer containing strong polar groups to the inorganic fluorine-containing lithium salt is (4-1):1, and the solid-liquid ratio of the mixture of the polymer containing strong polar groups and the inorganic fluorine-containing lithium salt to the organic solvent I is (0.04-0.2):1 g / ml.

3. The method of claim 2, wherein the method further comprises the step of: The organic solvent I includes at least one of acetonitrile, tetrahydrofuran, dimethylformamide, anisole, chloroform, dichloroethane, benzene, toluene, xylene, ethylbenzene, styrene, cyclohexane, cyclohexanone, chlorobenzene, dichloromethane, methanol, ethanol, ethyl acetate, butyl acetate, acetone, carbon disulfide; ​ The inorganic fluorine-containing lithium salt includes at least one of LiTFSI, LiFSI, LiODFB, LiPF6, LiBF4, LiCF3SO3, LiAsF6, LiTf, LiOTf, LiBC2O4F2, LiN(FSO2)2, LiN(CF3SO2)2, LiF, LiFAP, LiFAB, and LiTFSM.

4. The method for preparing a solid-state lithium-sulfur battery with integrated positive electrode and electrolyte according to claim 1, characterized in that, In step S1, the mass ratio of the inorganic solid electrolyte to the polymer containing strong polar groups is (0.05-0.20):

1.

5. The method of claim 4, wherein the method further comprises the step of: 5.

1. coating the cathode electrolyte with a protective layer of a lithium- ion-conducting material. The inorganic solid electrolyte includes a sulfide solid electrolyte and an oxide electrolyte, the sulfide solid electrolyte including at least one of Li2S-P2S5 glass and ceramic glass, thio-LiSiCON solid solution, and anion-doped Li2S-P2S5; and the oxide solid electrolyte including at least one of perovskite type, NASICON type, and garnet type. The polymer material containing strong polar groups includes at least one of polyethylene oxide, polyvinylidene fluoride, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, and polyvinylidene fluoride-hexafluoropropylene copolymer.

6. The method of claim 1, wherein the method is performed in a glove box under an inert atmosphere. In step S1, the stirring temperature after adding the inorganic solid electrolyte is 60-80°C, and the stirring intensity is 500-2000 rpm.

7. The method for preparing a solid-state lithium-sulfur battery with integrated positive electrode and electrolyte according to claim 1, characterized in that, In step S2, the chemical formula of lithium polysulfide is: Li2S x , 4≤x≤8, the temperature of high-temperature stirring is 40-80℃, and the high-dielectric-constant organic solvent II includes at least one of N,N-dimethylacetamide, N-methylacetamide, acetamide, N,N-dimethylformamide, N-methylformamide, formamide, caprolactam, dimethyl sulfoxide, malononitrile, and tetramethyl urea.

8. The method for preparing a solid-state lithium-sulfur battery with integrated positive electrode and electrolyte according to claim 1, characterized in that, In step S3, the porous conductive substrate includes at least one of carbon cloth, carbon paper, foamed nickel, foamed aluminum, carbon nanotube-based film, graphene foam, and graphene aerogel.

9. A positive electrolyte-integrated solid-state lithium-sulfur battery, characterized by The positive electrolyte integrated solid-state lithium-sulfur battery is prepared according to the preparation method of the positive electrolyte integrated solid-state lithium-sulfur battery according to any one of claims 1 to 8.

Images