A sulfide solid electrolyte membrane and a solid-state lithium ion battery

Abstract

The application relates to the field of lithium batteries, and discloses a sulfide solid electrolyte film and a solid lithium ion battery, the sulfide solid electrolyte film comprises a polymer film with a three-dimensional skeleton structure and a sulfide solid electrolyte material forming a continuous phase; the ion conductivity of the sulfide solid electrolyte film is > 10 ‑4 S / cm, and the thickness of the sulfide solid electrolyte film is <= 40 mu m; the sulfide forms a continuous phase in the polymer film by using a flexible polymer film as a skeleton support, the ion conductivity of the sulfide solid electrolyte film is ensured, and the thickness of the solid electrolyte film is greatly reduced.

Description

[0001] This application is application number 202110829108.1, filed on July 22, 2021, entitled "A divisional application of a sulfide solid electrolyte membrane and a solid lithium-ion battery". Technical Field

[0002] This invention relates to the field of lithium batteries, specifically to a sulfide solid electrolyte membrane and a solid lithium-ion battery. Background Technology

[0003] With the energy crisis and environmental protection requirements, new energy vehicles have received unprecedented attention. However, existing lithium-ion batteries, which use liquid electrolytes, do not yet fully meet safety requirements. In recent years, solid-state batteries using solid electrolytes have gained widespread attention due to their higher safety.

[0004] Existing solid-state electrolytes are mainly classified into three types: oxide solid-state electrolytes, sulfide solid-state electrolytes, and polymer solid-state electrolytes. Sulfide solid-state electrolytes are considered a material with broad industrial application prospects due to their high ionic conductivity. However, sulfide solid-state electrolyte membranes are difficult to form; the thickness of a pure sulfide solid-state electrolyte membrane is only about 0.5–1 mm. Excessive membrane thickness leads to excessively low volumetric energy density in the battery. Therefore, currently, sulfide solid-state electrolytes can only be used in laboratory-scale batteries, and their energy density is far lower than that of industrial liquid batteries.

[0005] In existing technologies, technicians have used methods such as pulsed laser deposition and vapor deposition to prepare corresponding solid electrolyte membranes, but these methods are costly and difficult to industrialize. Recent research results show that using sulfide solid electrolytes and polymer composites is an effective solution. Shuting Luo et al. prepared a solid electrolyte membrane with a thickness of 65 micrometers by compositing Li6PS5Cl and polyethylene oxide.

[0006] However, the aforementioned thickness still cannot fully meet the requirements for thinner and lighter solid-state lithium batteries. It is essential to find a thinner, higher-performance solid electrolyte membrane and apply it to lithium batteries. Summary of the Invention

[0007] In view of the above-mentioned problems in the prior art, the purpose of this invention is to provide a sulfide solid electrolyte membrane and a solid lithium-ion battery.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a sulfide solid electrolyte membrane, the sulfide solid electrolyte membrane comprising a polymer membrane having a three-dimensional framework structure and a sulfide solid electrolyte material forming a continuous phase; the ionic conductivity of the sulfide solid electrolyte membrane is >10. -4 S / cm, the thickness of the sulfide solid electrolyte membrane is ≤40μm.

[0010] In the method of this invention, the ionic conductivity of the sulfide solid electrolyte membrane can be, for example, 5 × 10⁻⁶. -4 S / cm, 5.5×10 -4 S / cm, 6×10 -4 S / cm or 10 -3 S / cm, etc.; the thickness of the sulfide solid electrolyte membrane can be, for example, 40μm, 35μm, 30μm or 25μm, etc.

[0011] This invention utilizes a flexible polymer membrane as a supporting framework, with sulfides forming a continuous phase within the polymer membrane. This ensures the ionic conductivity of the sulfide solid electrolyte membrane and significantly reduces its thickness.

[0012] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0013] Preferably, the polymer membrane is a PVDF membrane or a PVDF-based polymer membrane, wherein the molecular structure of the PVDF-based polymer membrane is P(VDF-B) or P(VDF-BA);

[0014] Wherein, B is selected from any one or a combination of at least two of trifluoroethylene (TrFE), hexafluoropropylene (HFP), or methyl methacrylate (MMA); A is selected from any one or a combination of at least two of chlorotrifluoroethylene (CTFE), 1,1-chlorofluoroethylene (CFE), or chlorodifluoroethylene (CDFE).

[0015] The mass fraction of VDF monomer-based structural units in the PVDF-based polymer film is a, where a ≥ 50%, for example, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.

[0016] The mass fraction of the structural unit based on monomer A in the PVDF-based polymer film is b, where b ≤ 20%, for example, 20%, 18%, 15%, 10%, 7%, 6%, 5%, 3%, or 1%.

[0017] In the above preferred technical solution, since the mass fraction of the VDF monomer-based structural units in the PVDF-based polymer film is greater than or equal to 50%, for the case where the molecular structure of the PVDF-based polymer film is P(VDF-B), the mass fraction of the B monomer-based structural units in the PVDF-based polymer film is less than or equal to 50%, for example, it can be 50%, 45%, 40%, 35%, 30%, 25%, or 20%; for the case where the molecular structure of the PVDF-based polymer film is P(VDF-BA), the sum of the mass fraction of the B monomer-based structural units and the mass fraction of the A monomer-based structural units in the PVDF-based polymer film is less than or equal to 50%, for example, it can be 50%, 45%, 40%, 35%, 30%, or 25%, etc., and c can be, for example, 0.5%, 1%, 3%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, or 35%, etc.

[0018] The polymer membrane of the present invention has good flexibility and can provide good skeletal support, which is beneficial to ensuring the continuity of the sulfide solid electrolyte membrane, so that the sulfide solid electrolyte membrane can obtain high ionic conductivity at a very thin thickness.

[0019] This invention utilizes electrospinning to prepare polymer membranes, forming a three-dimensional skeleton structure through fibers and making the mesh pores non-directional. This ensures good mechanical properties and facilitates the formation of a continuous phase of the sulfide solid electrolyte, thus better leveraging the advantage of improving the ionic conductivity of the sulfide solid electrolyte membrane.

[0020] As a preferred embodiment of the sulfide solid electrolyte membrane of the present invention, the polymer membrane is a PVDF-based polymer membrane with a molecular structure of P(VDF-B), where B is trifluoroethylene, and the mass fraction of the structural units based on trifluoroethylene monomers in the polymer membrane is c, where c ≤ 50%. In this case, the molecular structure of the polymer membrane is also P(VDF-TrFE).

[0021] Compared to other types of PVDF-based polymers, P(VDF-TrFE) has interactions and bonds with sulfide solid electrolytes such as Li6PS5Cl. This allows lithium conduction pathways to be formed at the sites where sulfides and polymers are bonded, thus improving the performance of the solid electrolyte membrane.

[0022] In some embodiments, the maximum mesh pore size of the polymer film is 30 μm.

[0023] It should be noted that the "mesh aperture" mentioned in this invention refers to the equivalent diameter of the through hole in the three-dimensional skeleton structure.

[0024] Those skilled in the art should understand that for a through hole formed by multiple interconnected holes, the equivalent diameter refers to the diameter of a local hole. For example, for Figure 2(a), the equivalent diameter is indicated by the double-headed arrow.

[0025] Preferably, the pore size D50 of the polymer membrane is 10 μm to 18 μm, such as 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, or 18 μm. More preferably, the pore size D90 of the polymer membrane is 10 μm to 18 μm.

[0026] In this invention, a mesh aperture D50 of A to B means that more than 50% of the mesh apertures are within the range of A to B. A mesh aperture D90 of A to B means that more than 90% of the mesh apertures are within the range of A to B. For example, a topographic image can be obtained using SEM, then dimensions can be measured, and the results can be statistically analyzed.

[0027] Preferably, the mesh pores of the polymer film are non-directional.

[0028] Preferably, the polymer film is prepared by electrospinning.

[0029] Preferably, the sulfide solid electrolyte material includes Li2S-P2S5 and Li2S-P2S5-MS. x Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 Li 9.6 P3S 12 Li7P3S 11 Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li(Si) 0.5 Sn 0.5 PS 12 Li 10GeP2S 12 (LGPS), Li6PS5X, Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 Li 10 SiP2S 12 Or Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 Any one or at least two of the following, wherein M is selected from any one or at least two of Si, Ge or Sn, and X is selected from any one or at least two of Cl, Br or I, and 0≤x≤2.

[0030] Preferably, the sulfide solid electrolyte material is Li6PS5X, where X is Cl, Br, or I.

[0031] Preferably, the sulfide solid electrolyte material is formed into a continuous phase within the polymer membrane by preparing a solution and injecting it onto the polymer membrane.

[0032] Preferably, the particle size of the sulfide solid electrolyte material is smaller than the maximum mesh pore size of the polymer membrane.

[0033] Preferably, the particle size of the sulfide solid electrolyte material is 50% to 70% of the maximum mesh pore size of the polymer film, such as 50%, 55%, 60%, 65%, or 70%.

[0034] Preferably, the sulfide solid electrolyte membrane contains a lithium salt.

[0035] Preferably, the lithium salt accounts for 0%-30% of the polymer in the polymer film by mass and does not exceed 0%, more preferably 5%-20%, and particularly preferably 5%-15%.

[0036] By way of example, the present invention provides a method for preparing the above-mentioned sulfide solid electrolyte membrane, the method comprising the following steps:

[0037] S1: Prepare the polymer film;

[0038] S2: Inject the solution containing sulfide solid electrolyte particles onto the polymer membrane obtained in step S1;

[0039] S3: Dry and hot-press to form a film to obtain the sulfide solid electrolyte membrane;

[0040] The ionic conductivity of the sulfide solid electrolyte membrane is >10. -4 S / cm, the thickness of the sulfide solid electrolyte membrane is ≤40μm;

[0041] In step S1, the maximum pore size of the polymer film obtained is greater than the particle size of the sulfide solid electrolyte particles obtained in step S2.

[0042] Preferably, in step S1, the polymer film has an internal three-dimensional interconnected structure.

[0043] Preferably, in step S1, the polymer film is prepared by electrospinning.

[0044] Preferably, step S2 further includes a thickness control step.

[0045] In a second aspect, the present invention provides a solid-state lithium-ion battery, the solid-state lithium-ion battery comprising a positive electrode, a negative electrode and the sulfide solid electrolyte membrane described in the first aspect.

[0046] This invention does not specifically limit the type of solid-state lithium-ion battery, such as lithium-sulfur battery, lithium-ion battery, lithium-iron disulfide battery or lithium-titanium sulfide battery, etc.

[0047] The negative electrode in a lithium-sulfur battery can be metallic lithium, while the positive electrode active material can be a sulfur-carbon composite material. The formulation and composition of lithium-sulfur batteries will not be elaborated here.

[0048] For example, the present invention provides a method for preparing the above-mentioned sulfur-carbon composite material, comprising: mixing sulfur vapor with a conductive additive, wherein the mass ratio of sulfur vapor to conductive additive can be adjusted according to actual use needs; after mixing sulfur vapor with conductive additive, heating at 145-160°C to obtain sulfur-carbon composite.

[0049] As one implementation method, the conductive additives used in preparing sulfur-carbon composite materials include, but are not limited to, any one or a combination of at least two of carbon black materials such as acetylene black, SuperP, SuperS, 350G, carbon fiber (VGCF), carbon nanotubes (CNTs), or Ketjen black.

[0050] Compared with existing technologies, the present invention has the following beneficial effects:

[0051] (1) The present invention combines a polymer membrane with a three-dimensional skeleton structure and a sulfide solid electrolyte material with a continuous phase, which can achieve high ionic conductivity while reducing the thickness.

[0052] (2) The present invention provides a preferred preparation method for the sulfide solid electrolyte membrane, wherein the copolymer is prepared into a polymer membrane by electrospinning, and the three-dimensional through-pore structure in the polymer membrane forms a three-dimensional skeleton, making the entire support membrane flexible. Then, by methods such as infusion and hot pressing, the sulfide solid electrolyte particles can form a continuous phase in the network, forming a three-dimensional permeation network, and a sulfide solid electrolyte membrane with high ionic conductivity and thin thickness is prepared.

[0053] (3) In this invention, PVDF-based polymer is preferably used as the main component of the polymer membrane. PVDF-based polymer has good compatibility with sulfide solid electrolyte, and the solid electrolyte membrane formed has high ionic conductivity and a thin thickness, which helps to improve battery performance.

[0054] (4) Compared with other PVDF-based polymers, P(VDF-TrFE) has interaction forces and bonding with sulfide solid electrolytes such as Li6PS5Cl, which makes the sites where sulfides and polymers are combined also form lithium conduction pathways, thus improving the performance of solid electrolyte membranes. Attached Figure Description

[0055] Figure 1 This is a photograph of the sulfide solid electrolyte membrane prepared in Example 1.

[0056] Figure 2(a) is a SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 1;

[0057] Figure 2(b) is a SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 2;

[0058] Figure 2(c) is a SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 3;

[0059] Figure 3(a) is a SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 4;

[0060] Figure 3(b) is a SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 5;

[0061] Figure 4 This is a SEM image of the solid electrolyte membrane prepared in Example 1;

[0062] Figure 5 The figures show the cycling performance of Example 7 and Comparative Example 1, where Li6PS5Cl@P(VDF-TrFe) corresponds to Example 7 and Li6PS5Cl corresponds to Comparative Example 1.

[0063] Figure 6This is a comparison of the nuclear magnetic resonance spectra of the Li6PS5Cl@PVDF solid electrolyte membrane and the PVDF membrane in Example 6;

[0064] Figure 7 The image shows a comparison of the nuclear magnetic resonance spectra of the Li6PS5Cl@P(VDF-TrFE) solid electrolyte membrane and the P(VDF-TrFE) membrane in Example 1. Detailed Implementation

[0065] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0066] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0067] In a first aspect, this embodiment provides a sulfide solid electrolyte membrane, which comprises a polymer membrane having a three-dimensional framework structure and a sulfide solid electrolyte material forming a continuous phase; the ionic conductivity of the sulfide solid electrolyte membrane is >10. -4 S / cm, the thickness of the sulfide solid electrolyte membrane is ≤40μm.

[0068] In this embodiment of the invention, a flexible polymer membrane is used as a framework support, and the sulfide forms a continuous phase in the polymer membrane, which ensures the ionic conductivity of the sulfide solid electrolyte membrane and greatly reduces the thickness of the solid electrolyte membrane.

[0069] In one embodiment, the polymer membrane has a molecular structure of P(VDF-B), where B is selected from any one or a combination of at least two of trifluoroethylene, hexafluoropropylene, or methyl methacrylate. The mass fraction of the structural units based on VDF monomers in the polymer membrane is ≥50%, and the mass fraction of the structural units based on B monomers in the polymer membrane is ≤50%.

[0070] In one embodiment, the molecular structure of the polymer membrane is P(VDF-BA), where B is selected from any one or a combination of at least two of trifluoroethylene, hexafluoropropylene, or methyl methacrylate, and A is selected from any one or a combination of at least two of trifluorochloroethylene, 1,1-chlorofluoroethylene, or difluorochloroethylene. The mass fraction of the VDF-based structural units in the polymer membrane is ≥50%, the mass fraction of the A-based structural units in the polymer membrane is ≤20%, and the sum of the mass fractions of the A-based structural units and the B-based structural units in the polymer membrane is ≤50%.

[0071] In one embodiment, the polymer membrane has a molecular structure of P(VDF-TrFE), and the mass fraction of the TrFE monomer-based structural units in the polymer membrane is ≤50%.

[0072] The ionic conductivity is mainly provided by the sulfide solid electrolyte in the continuous phase. Therefore, as an implementation method, the present invention does not have special requirements on the molar ratio of each monomer in the raw materials for polymer membrane preparation.

[0073] In one embodiment, the raw materials for preparing the polymer membrane P (VDF-TrFE) have a VDF:TrFE (molar ratio) of 80%:20% to 50%:50%, such as 80%:20%, 75%:25%, 70%:30%, 65%:35%, 60%:40%, 55%:45%, or 50%:50%, etc.

[0074] In one embodiment, the raw materials for preparing the polymer membrane P (VDF-TrFE) have a VDF:TrFE (molar ratio) of 70%:30%.

[0075] As one implementation method, this application does not have special requirements for the molecular weight of the polymer, as long as the polymer can form a film normally and form a three-dimensional skeleton.

[0076] In one embodiment, the polymer membrane has an internal three-dimensional interconnected structure.

[0077] In one embodiment, the maximum pore size of the polymer film is 30 μm.

[0078] In one embodiment, the pore size D50 of the polymer membrane is 10 μm to 18 μm, and more preferably the pore size D90 of the polymer membrane is 10 μm to 18 μm.

[0079] In this embodiment of the invention, there are no special requirements for the preparation method of the polymer film. It is only necessary to prepare a polymer skeleton that forms a three-dimensional network structure. The polymer skeleton needs to be able to accommodate sulfide solid electrolyte particles so that the sulfide solid electrolyte particles form a continuous phase in the three-dimensional network structure to provide a lithium conduction pathway.

[0080] In one embodiment, the mesh pores of the polymer film are non-directional.

[0081] In a particularly preferred embodiment, the polymer film is prepared by electrospinning.

[0082] Polymer membranes are prepared by electrospinning, forming a three-dimensional framework structure through fibers and making the mesh pores non-directional. This ensures good mechanical properties and facilitates the formation of a continuous phase of the sulfide solid electrolyte, thus better leveraging the advantage of improving the ionic conductivity of the sulfide solid electrolyte membrane.

[0083] Since the difficulty in pressing into a film is a common problem for sulfide solid electrolytes, the embodiments of the present invention do not particularly limit the type of sulfide solid electrolyte. All sulfide solid electrolytes known in the prior art can be used in the present invention, including but not limited to Li2S-P2S5 and Li2S-P2S5-MS. x Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 Li 9.6 P3S 12 Li7P3S 11 Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li(Si) 0.5 Sn 0.5 PS 12 Li 10 GeP2S 12 Li6PS5X, Li7P2S8I, Li 10.35 Ge 1.35P 1.65 S 12 Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 Li 10 SiP2S 12 Or Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 Any one or at least two of the following, wherein M is selected from any one or at least two of Si, Ge or Sn, and X is selected from any one or at least two of Cl, Br or I, and 0≤x≤2.

[0084] In a particularly preferred embodiment, the sulfide solid electrolyte is Li6PS5X, where X = Cl, Br, I.

[0085] In one embodiment, the sulfide solid electrolyte material is formed into a continuous phase within the polymer membrane by preparing a solution and injecting it onto the polymer membrane.

[0086] In one embodiment, the particle size of the sulfide solid electrolyte material is smaller than the maximum pore size of the polymer membrane. More preferably, the particle size of the sulfide solid electrolyte particles is 50% to 70% of the maximum pore size of the polymer membrane, and most preferably 60%.

[0087] A suitable mesh size is beneficial for sulfide solid electrolyte particles to form a continuous phase by being infused into a polymer membrane as a solution; if the mesh size is too small, the sulfide solid electrolyte cannot be completely infused into the polymer, affecting the ionic conductivity of the final sulfide solid electrolyte membrane.

[0088] In one embodiment, the sulfide solid electrolyte membrane includes a lithium salt, which can effectively improve the ionic conductivity of the sulfide solid electrolyte membrane.

[0089] In this invention, the type of lithium salt is not particularly limited. Any known lithium salt can be used in this invention without departing from the inventive concept of this application. Known lithium salts include inorganic lithium salts, organic lithium salts, or mixtures of inorganic and organic lithium salts. Inorganic lithium salts include, but are not limited to, any one or at least two combinations of lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), or lithium hexafluorophosphate (LiPF6). Organic lithium salts include, but are not limited to, any one or at least two combinations of lithium bis(trifluoromethanesulfonyl)imide (LiBOB), lithium difluorooxalate borate (LIFOB), lithium bis(difluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (MSDS), lithium trifluoromethanesulfonate (LiCF3SO3), or lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2).

[0090] Preferably, the mass ratio of the lithium salt to the polymer in the polymer film is 0%-30% and contains no 0%, more preferably 5%-20%, and particularly preferably 5%-15%.

[0091] The sulfide solid electrolyte membrane finally prepared according to the embodiments of the present invention has an ionic conductivity of 10. -4 For the first time, a relatively complete sulfide solid electrolyte membrane with high ionic conductivity and thin thickness was successfully prepared with a strength of S / cm and a thickness of less than 40 μm.

[0092] The present invention further provides a method for preparing the above-mentioned sulfide solid electrolyte membrane, comprising:

[0093] S1: Prepare the polymer film;

[0094] S2: Inject the solution containing sulfide solid electrolyte particles onto the polymer membrane obtained in step S1;

[0095] S3: Dry and hot-press to form a film to obtain a sulfide solid electrolyte membrane;

[0096] The ionic conductivity of the sulfide solid electrolyte membrane is >10. -4 S / cm, the thickness of the sulfide solid electrolyte membrane is ≤40μm;

[0097] In step S1, the maximum pore size of the polymer film obtained is greater than the particle size of the sulfide solid electrolyte particles obtained in step S2.

[0098] In one embodiment, in step S1, the polymer film is a PVDF film.

[0099] In one embodiment, in step S1, the molecular structure of the polymer membrane is P(VDF-B), where B is selected from any one or a combination of at least two of trifluoroethylene, hexafluoropropylene, or methyl methacrylate. The mass fraction of the structural units based on VDF monomers in the polymer membrane is ≥50%, and the mass fraction of the structural units based on B monomers in the polymer membrane is ≤50%.

[0100] In one embodiment, in step S1, the molecular structure of the polymer membrane is P(VDF-BA), where B is selected from any one or a combination of at least two of trifluoroethylene, hexafluoropropylene, or methyl methacrylate, and A is selected from any one or a combination of at least two of trifluorochloroethylene, 1,1-chlorofluoroethylene, or difluorochloroethylene. The mass fraction of the structural units based on VDF monomers in the polymer membrane is ≥50%, the mass fraction of the structural units based on A monomers in the polymer membrane is ≤20%, and the sum of the mass fractions of the structural units based on A monomers and the mass fractions of the structural units based on B monomers in the polymer membrane is ≤50%.

[0101] In this embodiment of the invention, there are no special requirements for the molar ratio of each monomer in the raw materials for preparing the polymer film in step S1.

[0102] In one embodiment, in step S1, the raw materials for preparing the polymer film P (VDF-TrFE) have a VDF:TrFE (molar ratio) of 80%:20% to 50%:50%.

[0103] In one embodiment, in step S1, the raw materials for preparing the polymer film P (VDF-TrFE) have a VDF:TrFE (molar ratio) of 70%:30%.

[0104] In one embodiment, in step S1, the polymer membrane has an internal three-dimensional interconnected structure.

[0105] In one embodiment, in step S1, the maximum pore size of the polymer film is 30 μm.

[0106] In one embodiment, in step S1, the mesh pore size D50 of the polymer membrane is 10 μm to 18 μm, and more preferably the mesh pore size D90 of the polymer membrane is 10 μm to 18 μm.

[0107] In one embodiment, in step S1, a polymer film is prepared by electrospinning.

[0108] In this embodiment of the invention, there is no particular limitation on the preparation method of electrospinning. As one embodiment, polymer precursor solutions can be obtained by dissolving polymer particles in a solvent and then electrospinning them under an electric field to prepare the corresponding polymer electrospinned membrane.

[0109] In a particularly preferred embodiment, the polymer in the polymer precursor solution is P(VDF-TrFE).

[0110] In this embodiment of the invention, the solvent in the polymer precursor solution is not particularly limited, as long as it allows the polymer particles to dissolve uniformly. As one embodiment, it can be N,N-dimethylamide, acetone, ethanol, or ethylene glycol monomethyl ether, etc.

[0111] Generally, the concentration of the precursor solution, the electrospinning time, and the speed affect the thickness of the spun film. This invention does not impose specific limitations on the electrospinning process parameters, as long as the desired spun film is obtained.

[0112] In this embodiment of the invention, there are no particular limitations on process parameters such as electric field strength, but the electric field strength should be greater than the critical electric field strength for electrospinning. As one embodiment, the electric field strength is 0.5kV / cm to 2kV / cm, preferably 1kV / cm to 1.6kV / cm.

[0113] In one embodiment, lithium salt is added during the preparation of the polymer membrane in step S1. The lithium salt is mixed with the polymer in step S1 to prepare a precursor solution, and the polymer membrane is prepared by electrospinning.

[0114] Premixing lithium salt and polymer before film formation improves the uniformity of their mixing and enhances their interaction.

[0115] In this invention, there is no particular limitation on the type of lithium salt added to the precursor solution. Any known lithium salt can be used in this invention without departing from the inventive concept of this application. Known lithium salts include inorganic lithium salts, organic lithium salts, or mixtures of inorganic and organic lithium salts. Inorganic lithium salts include, but are not limited to, any one or at least a combination of two of lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), or lithium hexafluorophosphate (LiPF6). Organic lithium salts include, but are not limited to, any one or at least a combination of two of lithium bis(trifluoromethylsulfonyl)imide (LiBOB), lithium difluorooxalate borate (LIFOB), lithium bis(difluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethylsulfonyl)imide (MSDS), lithium trifluoromethanesulfonate (LiCF3SO3), or lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2).

[0116] In one embodiment, the lithium salt in the precursor solution accounts for 0%-30% of the polymer in the polymer film by mass and does not exceed 0%, for example, 0.5%, 1%, 2%, 2.5%, 3%, 4%, 5%, 5.5%, 6%, 8%, 9%, 10%, 12%, 15%, 17%, 20%, 22%, 25%, 27% or 30%, more preferably 5% to 20%, and particularly preferably 5% to 15%.

[0117] During the electrospinning process, the presence of cations and anions in lithium salts affects the electric field of the spinning machine during polymer film formation, resulting in excessively high orientation of the mesh pores in the formed polymer film. Therefore, using an appropriate amount of lithium salt is beneficial.

[0118] Orientation refers to the fact that in polymer films, polymer fibers are arranged in a fixed direction to form a regular grid pattern.

[0119] In one embodiment, in step S1, the mesh pores of the polymer film are non-directional.

[0120] In a preferred embodiment, the particle size of the sulfide solid electrolyte particles is 50% to 70% of the maximum pore size of the polymer membrane, and most preferably 60%.

[0121] In this embodiment of the invention, there is no particular limitation on the type of sulfide solid electrolyte particles in step S2. All known sulfide solid electrolytes in the prior art can be used in this invention, including but not limited to Li2S-P2S5 and Li2S-P2S5-MS. x Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 Li 9.6 P3S 12 Li7P3S 11 Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li(Si)0.5 Sn 0.5 PS 12 Li 10 GeP2S 12 Li6PS5X, Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 Li 10 SiP2S 12 Or Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 Any one or at least two of the following, wherein M is selected from any one or at least two of Si, Ge or Sn, and X is selected from any one or at least two of Cl, Br or I, and 0≤x≤2.

[0122] In one embodiment, step S2 further includes adding the sulfide solid electrolyte particles to a solvent and dispersing them to form a homogeneous solution. Solvents capable of uniformly dispersing the sulfide solid electrolyte particles are known, including but not limited to any one or a combination of at least two of benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, cyclohexanone, chlorobenzene, dichlorobenzene, methanol, ethanol, isopropanol, or diethyl ether.

[0123] The embodiments of the present invention do not have any particular limitation on the dispersion method. Mechanical dispersion methods, such as mechanical stirring, can be used. It is sufficient to form a homogeneous solution of sulfide electrolyte particles in a solvent.

[0124] In one implementation, step S2 also includes a thickness control step.

[0125] The thickness control refers to controlling the thickness of the polymer film after infusion with sulfide solid electrolyte within a specific thickness range, such as within 40 μm.

[0126] The embodiments of the present invention do not particularly limit the method of thickness control. As one embodiment, the coating can be performed by using a scraper with a thickness adjustment knob.

[0127] In one implementation, the purpose of drying in step S3 is to remove excess solvent. The drying method is known, for example, drying the electrolyte membrane obtained by filling in a constant temperature dryer.

[0128] The embodiments of the present invention do not have special requirements for the drying temperature and drying time. For example, drying can be carried out at 100℃~150℃ for 1h~10h.

[0129] Secondly, this embodiment provides a solid-state lithium-ion battery, which includes a positive electrode, a negative electrode, and a sulfide solid electrolyte membrane prepared in the above embodiments.

[0130] In embodiments of the present invention, the negative electrode is formed of a lithium host material capable of being used as a negative terminal of a lithium-ion battery. For example, the negative electrode may comprise a lithium host material capable of being used as a negative terminal of a battery. In various aspects, the negative electrode may be defined by a variety of negative electrode active material particles, such negative electrode active material particles may be disposed in one or more layers to define the three-dimensional structure of the negative electrode.

[0131] In one embodiment, the negative electrode may further include an electrolyte material, the type of which is known in the art and may be any one or a combination of at least two of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes or polymer solid electrolytes.

[0132] In one embodiment, the negative electrode may include a lithium-based negative electrode active material, comprising, for example, lithium metal and / or lithium alloys.

[0133] In one embodiment, the negative electrode is a silicon-based negative electrode active material comprising silicon, such as silicon alloys and / or silicon oxide. In another embodiment, the silicon-based negative electrode active material may also be mixed with graphite.

[0134] In one embodiment, the negative electrode may include a carbon-based negative electrode active material comprising any one or a combination of at least two of graphite, graphene, or carbon nanotubes (CNTs).

[0135] In one embodiment, the negative electrode includes one or more negative electrode active materials that accept lithium, such as lithium titanium oxide (Li4Ti5O). 12 Transition metals (e.g., Sn), metal oxides (e.g., V₂O₅), tin oxide (SnO), titanium dioxide (TiO₂), and titanium niobium oxide (TiO₂) x Nb y O z , where 0≤x≤2, 0≤y≤24, 0≤z≤64, metal alloys (e.g., copper-tin alloy (Cu6Sn5)) or metal sulfides (e.g., iron sulfide (FeS)) are any one or a combination of at least two of them.

[0136] In one embodiment, the negative electrode active material in the negative electrode may be doped with one or more conductive materials that provide an electron conduction path and / or at least one polymer binder material that improves the structural integrity of the negative electrode.

[0137] In one embodiment, the negative electrode active material may be doped with any one or a combination of at least two of the following conductive materials: carbon-based materials, powdered nickel, other metal particles, or conductive polymers. Optionally, the carbon-based material may include at least one particle selected from, for example, carbon black, graphite, SuperP, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers, carbon nanotubes, or graphene. Optionally, the conductive polymer may include at least one selected from, such as, polyaniline, polythiophene, polyacetylene, polypyrrole, or poly(3,4-ethylenedioxythiophene)polysulfonated styrene.

[0138] In one implementation, the negative electrode active material may be doped with binders such as: poly(tetrafluoroethylene) (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof.

[0139] In one embodiment, the negative electrode may include 50% to 97% negative electrode active material, optionally 0% to 60% solid electrolyte, optionally 0% to 15% conductive material, and optionally 0% to 10% binder. It should be noted that "optional" means that the corresponding substance may or may not be included; when the content is 0%, it means that the corresponding substance is not included.

[0140] In one embodiment, the positive electrode includes a positive electrode electroactive material layer, the positive electrode electroactive material layer including a lithium-based positive electrode electroactive material.

[0141] The positive electrode electroactive material layer has a thickness of 1μm to 1000μm.

[0142] In one embodiment, the positive electrode active material layer is formed of a plurality of positive electrode active particles containing one or more transition metal cations, such as any one or a combination of at least two of manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe) or vanadium (V).

[0143] In one implementation, the positive electrode active material layer is one of a layered oxide cathode, a spinel cathode, an olivine cathode, or a polyanion cathode.

[0144] In one implementation, the layered oxide cathode (e.g., a rock salt layered oxide cathode) comprises one or more lithium-based positive electrode active materials selected from: LiCoO2 (LCO), LiNia Mn b Co 1-a-b O2 (where 0≤a≤1, 0≤b≤1), LiNi 1-c-d Co c Al d O2 (where 0≤c≤1 and 0≤d≤1), LiNi e Mn 1-e O2 (where 0 ≤ e ≤ 1) or Li 1+f MO2 (where M is any one or at least two of Mn, Ni, Co or Al, and 0≤f≤1) is any one or at least two of the following:

[0145] In one embodiment, the spinel cathode comprises one or more lithium-based positive electrode active materials selected from LiMn2O4 (LMO) and LiNi. 0.5 Mn 1.5 O4.

[0146] In one embodiment, the olivine-type cathode comprises one or more lithium-based positive electrode electroactive materials, LiMPO4 (where M is at least one of Fe, Ni, Co, and Mn).

[0147] In one embodiment, the polyanionic cathode comprises one or more lithium-based positive electrode active materials: phosphates and / or silicates, such as LiV2(PO4)3 for phosphates and LiFeSiO4 for silicates.

[0148] In one embodiment, the positive electrode electroactive material layer further includes an electrolyte, such as a plurality of electrolyte particles.

[0149] In one implementation, one or more lithium-based positive electrode active materials may optionally be coated and / or doped.

[0150] In one implementation, one or more lithium-based positive electrode electroactive materials are coated with LiNbO3 and / or Al2O3.

[0151] In one implementation, one or more lithium-based positive electrode active materials are doped with magnesium (Mg).

[0152] In one implementation, one or more lithium-based positive electrode electroactive materials may optionally be mixed with one or more conductive materials that can provide an electronic conduction path and / or at least one polymer binder material that improves the structural integrity of the positive electrode.

[0153] In one embodiment, the positive electrode active material layer may contain 30% to 98% of one or more lithium-based positive electrode active materials, 0% to 30% of conductive materials, and 0% to 20% of binder. In some embodiments, it may contain 1% to 20% binder.

[0154] As one implementation, the lithium-based positive electrode active material may optionally be mixed with any one or a combination of at least two of the following binders: polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, or lithium alginate.

[0155] In one embodiment, the lithium-based positive electrode active material may optionally be mixed with a conductive material, which may include any one or a combination of at least two of carbon-based materials, powdered nickel, other metal particles, or conductive polymers. Carbon-based materials may include, for example, any one or a combination of at least two of carbon black, graphite, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers, carbon nanotubes, or graphene. Conductive polymers may include, for example, any one or a combination of at least two of polyaniline, polythiophene, polyacetylene, or polypyrrole.

[0156] A positive current collector facilitates the flow of electrons between the positive electrode and an external circuit. The positive current collector may comprise a metal, such as a metal foil, metal grid, or metal mesh. For example, the positive current collector may be formed from any one or at least two of aluminum, stainless steel, nickel, or any other suitable conductive material known to those skilled in the art.

[0157] Example 1

[0158] I. Preparation of Li6PS5Cl:

[0159] Li₂S (99.9% purity), P₂S₅ (99% purity), and LiCl (99.9% purity) powders were weighed at a mass ratio of 5:1:2 and mixed in a planetary ball mill at a mixing speed of 100 rpm for 1 h. Subsequently, the mixture was calcined in a crucible at 400 °C for 10 h and then slowly cooled to room temperature.

[0160] The Li6PS5Cl powder obtained by calcination was passed through a 400-mesh sieve to obtain electrolyte powder particles with uniform particle size.

[0161] II. Preparation of P(VDF-TrFE) electrospun film

[0162] 1.0 g of P(VDF-TrFE) polymer particles were slowly dissolved in a mixed solvent of 3 ml dimethylformamide (DMF) and 2 ml acetone. The molar ratio of VDF to TrFE in the raw materials for preparing the P(VDF-TrFE) polymer particles was 70% to 30% to obtain a pure P(VDF-TrFE) precursor solution. The P(VDF-TrFE) precursor solution was electrospun under an electric field strength of 1 kV / cm and a flow rate of 1 mL / h to prepare a P(VDF-TrFE) electrospun membrane. The SEM image of the membrane is shown in Figure 2(a). The mesh pore size D50 of the obtained P(VDF-TrFE) electrospun membrane was 10 μm to 18 μm.

[0163] III. Preparation of Li6PS5Cl@P(VDF-TrFE) sulfide solid electrolyte membrane

[0164] The Li6PS5Cl particles obtained in step one were dissolved in toluene (99.9% purity) and mechanically stirred at 30°C for 1 hour to obtain a homogeneous Li6PS5Cl solution. Two P(VDF-TrFE) electrospun membranes were taken, and the Li6PS5Cl solution was poured onto the two P(VDF-TrFE) electrospun membranes respectively, with the thickness controlled by a doctor blade.

[0165] The sulfide solid electrolyte membrane obtained by infusion was dried at 120°C for 2 hours in a constant-temperature desiccator to remove excess solvent, yielding two composite solid electrolyte membranes. These two composite solid electrolyte membranes were then stacked and hot-pressed at 200°C and 10 MPa for 2 hours. All operations were performed under an argon atmosphere to obtain the sulfide solid electrolyte membrane.

[0166] The final sulfide solid electrolyte membrane had a thickness of 37 μm and an ionic conductivity of 1.2 mS / cm. -1 .

[0167] Figure 1 This is a photograph of the sulfide solid electrolyte membrane prepared in Example 1.

[0168] Figure 2(a) is a SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 1.

[0169] Figure 4 This is a SEM image of the solid electrolyte membrane prepared in Example 1.

[0170] Figure 7 The image shows the nuclear magnetic resonance spectrum of the Li6PS5Cl@P(VDF-TrFE) solid electrolyte membrane from Example 1.

[0171] Example 2

[0172] Compared with the preparation method of Example 1, in the preparation steps of P(VDF-TrFE) electrospun membrane, the mass of P(VDF-TrFE) polymer particles is 0.6g. Figure 2(b) is a SEM image of the prepared P(VDF-TrFE) electrospun membrane. The mesh pore size D50 of the obtained P(VDF-TrFE) electrospun membrane is 1μm to 5μm. Other steps are the same as in Example 1.

[0173] The final sulfide solid electrolyte membrane had a thickness of 37 μm and an ionic conductivity of 1.01 × 10⁻⁶. -4 S / cm.

[0174] Example 3

[0175] Compared with the preparation method of Example 1, in the preparation steps of P(VDF-TrFE) electrospun membrane, the mass of P(VDF-TrFE) polymer particles is 0.8g. Figure 2(c) is a SEM image of the prepared P(VDF-TrFE) electrospun membrane. The mesh pore size D50 of the obtained P(VDF-TrFE) electrospun membrane is 5μm to 10μm. Other steps are the same as in Example 1.

[0176] The final sulfide solid electrolyte membrane had a thickness of 37 μm and an ionic conductivity of 5.3 × 10⁻⁶. -4 S / cm.

[0177] Example 4

[0178] Compared with the preparation method of Example 1, in the preparation step of P(VDF-TrFE) electrospun membrane, 0.6g of P(VDF-TrFE) polymer particles and 0.3g of lithium bis(fluorosulfonyl)imide (LiFSI) are slowly dissolved in a mixed solvent of 3ml dimethylformamide (DMF) and 2ml acetone. The rest is the same as in Example 1.

[0179] Figure 3(a) is a SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 4.

[0180] The resulting P(VDF-TrFE) electrospun membrane has a certain degree of orientation, and it is difficult to inject the oriented electrospun membrane.

[0181] Example 5

[0182] Compared with the preparation method of Example 1, in the preparation step of P(VDF-TrFE) electrospun membrane, 1.0g of P(VDF-TrFE) polymer particles and 0.3g of lithium bis(fluorosulfonyl)imide (LiFSI) are slowly dissolved in a mixed solvent of 3ml dimethylformamide (DMF) and 2ml acetone, and the rest is the same as in Example 1.

[0183] Figure 3(b) is a SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 5.

[0184] The resulting P(VDF-TrFE) electrospun membrane exhibits improved orientation, meaning its orientation is weakened, thus reducing the difficulty of instillation.

[0185] Example 6

[0186] PVDF membranes were prepared using the same electrospinning process as in Example 1, and all other aspects were the same as in Example 1.

[0187] The final Li6PS5Cl@PVDF solid electrolyte membrane has a thickness of 37 μm and an ionic conductivity of 5 × 10⁻⁶. -4 S / cm.

[0188] Figure 6 This is a comparison of the nuclear magnetic resonance spectra of the Li6PS5Cl@PVDF solid electrolyte membrane and the PVDF membrane in Example 6;

[0189] Example 7

[0190] This embodiment provides a method for preparing an S@C||Li6PS5Cl@P(VDF-TrFE)||Li-In battery, including the following steps:

[0191] Multi-walled carbon nanotubes were dissolved in a 1% (w / w) sodium dodecylbenzenesulfonate solution, and sulfur was dissolved in tetrahydrofuran to form a protective solution. The protective solution was added to the multi-walled carbon nanotube solution, and the mixture was vigorously stirred. The suspension was separated and washed several times with distilled water to remove the sodium dodecylbenzenesulfonate. The resulting sulfur-carbon nanotube composite was dried to obtain S@C composite particles, wherein the mass ratio of nano-sulfur to multi-walled carbon nanotubes was 6:4.

[0192] The synthesized S@C composite particles were mixed with Li6PS5Cl at a mass ratio of 4:6 in a ball mill and stirred at a stirring speed of 300 rpm for 1 h. The resulting product was used to prepare a positive electrode.

[0193] The above-mentioned positive electrode, together with the Li-In negative electrode and the Li6PS5Cl@P(VDF-TrFE) sulfide solid electrolyte membrane prepared in Example 1, are stacked to form an all-solid-state lithium-ion battery.

[0194] Example 8

[0195] This embodiment provides a method for preparing a Li6PS5Cl@C||Li6PS5Cl@P(VDF-TrFE)||Li-In battery, including the following steps:

[0196] Li6PS5Cl and multi-walled carbon nanotubes were mixed in a mass ratio of 7:3 and ball-milled at 100 rpm for one hour to obtain the product for preparing a positive electrode.

[0197] The above-mentioned positive electrode, together with the Li-In negative electrode and the Li6PS5Cl@P(VDF-TrFE) sulfide solid electrolyte membrane prepared in Example 1, are stacked to form an all-solid-state lithium-ion battery.

[0198] No significant degradation was observed in the battery after 180 cycles.

[0199] Example 9

[0200] This embodiment provides a method for preparing an NCM@LNO||Li6PS5Cl@P(VDF-TrFE)||Li-In battery, including the following steps:

[0201] Commercially available NCM811 particles were heated at 90°C for 12 hours before use. LiOC2H5 and Nb(OC2H5)5 were dissolved in anhydrous ethanol, and then NCM811 was added to the solution and stirred for 3 hours. The slurry was dried at 150°C for 12 hours and then heated at 400°C for 1 hour in an oxygen atmosphere to form LNO-coated NCM particles. The resulting product was used to prepare a positive electrode.

[0202] The above-mentioned positive electrode, together with the Li-In negative electrode and the Li6PS5Cl@P(VDF-TrFE) sulfide solid electrolyte membrane prepared in Example 1, are stacked to form an all-solid-state lithium-ion battery.

[0203] No significant degradation was observed in the battery after 1000 cycles.

[0204] Example 10

[0205] Li2S was used as the positive electrode active material, and everything else was the same as in Example 7.

[0206] No significant battery degradation was observed after 500 battery cycles.

[0207] Example 11

[0208] FeS2 was used as the positive electrode active material, and everything else was the same as in Example 7.

[0209] No significant battery degradation was observed after 500 battery cycles.

[0210] Comparative Example 1

[0211] Compared with Example 7, the difference is that the P(VDF-TrFE) sulfide solid electrolyte membrane is replaced with a pure Li6PS5Cl sulfide solid electrolyte membrane.

[0212] Combination Figures 2(a)-2(c) Examples 1-3 show that the thickness of sulfide solid electrolyte membranes obtained by infusing sulfide solid electrolyte particles onto P(VDF-TrFE) polymer membranes can all reach below 40 μm. However, when the mesh pore size of the polymer membrane is too small, the infusion effect is not ideal due to the particle size of the sulfide solid electrolyte particles themselves. Larger sulfide particles are difficult to completely infuse into the spinning web, resulting in lower ionic conductivity of the sulfide solid electrolyte membranes prepared in Examples 2-3. When the mesh pore size of the polymer membrane reaches 10 μm or more, the ionic conductivity is significantly improved.

[0213] Combining Figures 3(a) and 3(b), after adding lithium salt, the anionic and cation charges carried by the lithium salt itself will affect the electric field of the spinning machine during electrospinning, thereby causing the polymer electrospun membrane to form an oriented grid; when the lithium salt concentration is reduced, the grid orientation of the polymer electrospun membrane weakens.

[0214] Combination Figure 1 and Figure 4 The sulfide solid electrolyte membrane prepared in Example 1 has a thickness of 37 μm, and the surface of the sulfide solid electrolyte membrane is uniformly distributed. The particles are uniformly injected into the polymer membrane, and the particles completely cover the polymer membrane.

[0215] Figure 6 This is a comparison of the nuclear magnetic resonance spectra of the Li6PS5Cl@PVDF solid electrolyte membrane and the PVDF membrane in Example 6. Figure 7 This is a comparison of the nuclear magnetic resonance spectra of the Li6PS5Cl@P(VDF-TrFE) solid electrolyte membrane and the P(VDF-TrFE) membrane in Example 1. Figure 6 and Figure 7 It can be seen that the solid electrolyte membrane formed by pure PVDF and sulfide solid electrolyte has the same NMR spectrum as pure PVDF, proving that there is no interaction between pure PVDF and sulfide solid electrolyte; while the solid electrolyte membrane formed by P(VDF-TrFE) and sulfide solid electrolyte has a different peak shape than pure P(VDF-TrFE), which shows that the sulfide solid electrolyte membrane has a strong interaction with P(VDF-TrFE) and is not a simple physical mixture.

[0216] Figure 5 The figures show the cycling performance of Example 7 and Comparative Example 1, where Li6PS5Cl@P(VDF-TrFe) corresponds to Example 7 and Li6PS5Cl corresponds to Comparative Example 1. Figure 5As can be seen from Example 7 and Comparative Example 1, the battery capacity decays faster when using a pure Li6PS5Cl sulfide solid electrolyte membrane. This is because the excessively thick sulfide solid electrolyte membrane prolongs the ion conduction path, making the battery interface problems worse during charging and discharging.

[0217] As can be seen from Examples 7-11, the sulfide solid electrolyte membrane involved in this application has good performance in a variety of batteries and has the advantage of wide application.

[0218] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0219] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A sulfide solid electrolyte membrane, characterized in that, The sulfide solid electrolyte membrane comprises a polymer membrane with a three-dimensional framework structure and a sulfide solid electrolyte material forming a continuous phase; the ionic conductivity of the sulfide solid electrolyte membrane is >10. -4 S / cm, the thickness of the sulfide solid electrolyte membrane is ≤40μm; The polymer membrane is a PVDF-based polymer membrane with a molecular structure of P(VDF-B), where B is trifluoroethylene. The mass fraction of the structural units based on trifluoroethylene monomers in the polymer membrane is c, where c ≤ 50%. The polymer film is prepared by electrospinning, and the mesh pores of the polymer film are non-directional. The pore size D50 of the polymer film is 10μm~18μm; The sulfide solid electrolyte membrane includes a lithium salt, and the mass ratio of the lithium salt to the polymer in the polymer membrane is 5%-15%. The sulfide solid electrolyte membrane is prepared by the following method, which includes the following steps: S1: A precursor solution is prepared by mixing lithium salt with polymer, and a polymer film is prepared by electrospinning. S2: Inject the solution containing sulfide solid electrolyte particles onto the polymer membrane obtained in step S1; S3: Dry and hot-press to form a film to obtain a sulfide solid electrolyte membrane.

2. The sulfide solid electrolyte membrane as described in claim 1, characterized in that, The sulfide solid electrolyte material includes Li2S-P2S5 and Li2S-P2S5-MS. x Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 Li 9.6 P3S 12 Li7P3S 11 Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li(Si) 0.5 Sn 0.5 PS 12 Li 10 GeP2S 12 Li6PS5X, Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 Li 10 SiP2S 12 Or Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Any one or at least two of the following, wherein M is selected from any one or at least two of Si, Ge or Sn, and X is selected from any one or at least two of Cl, Br or I, and 0 ≤ x ≤ 2.

3. The sulfide solid electrolyte membrane as described in claim 2, characterized in that, The sulfide solid electrolyte material is Li6PS5X, where X is Cl, Br, or I.

4. The sulfide solid electrolyte membrane as described in claim 2, characterized in that, The particle size of the sulfide solid electrolyte material is 50% to 70% of the maximum mesh pore size of the polymer film.

5. A solid-state lithium-ion battery, the solid-state lithium-ion battery comprising a positive electrode, a negative electrode and a sulfide solid electrolyte membrane according to any one of claims 1-4.

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