CN113451638A

CN113451638A - Sulfide solid electrolyte membrane and solid lithium ion battery

Info

Publication number: CN113451638A
Application number: CN202110829108.1A
Authority: CN
Inventors: 冯玉川; 刘思捷; 何泓材; 李峥
Original assignee: Qingtao Kunshan Energy Development Co ltd
Current assignee: Qingtao Kunshan Energy Development Co ltd
Priority date: 2021-07-22
Filing date: 2021-07-22
Publication date: 2021-09-28
Anticipated expiration: 2041-07-22
Also published as: CN113451638B; WO2023000604A1; CN114824449A

Abstract

The invention relates to the field of lithium batteries, and discloses a sulfide solid electrolyte membrane and a solid lithium ion battery, wherein 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; ion conductivity of the sulfide solid electrolyte membrane>10^‑4S/cm, wherein the thickness of the sulfide solid electrolyte membrane is less than or equal to 40 mu m; the flexible polymer membrane is used as a framework support function, and the sulfide forms a continuous phase in the polymer membrane, so that the ionic conductivity of the sulfide solid electrolyte membrane is ensured, and the thickness of the solid electrolyte membrane is greatly reduced.

Description

Sulfide solid electrolyte membrane and solid lithium ion battery

Technical Field

The invention relates to the field of lithium batteries, and relates to a sulfide solid electrolyte membrane and a solid lithium ion battery.

Background

With the requirements of energy crisis and environmental protection, new energy automobiles receive unprecedented attention, but the safety of the existing lithium ion batteries cannot completely meet the use requirements due to the adoption of liquid electrolytes. In recent years, solid-state batteries using a solid electrolyte have received much attention due to high safety.

The existing solid electrolytes are mainly divided into three types, namely oxide solid electrolytes, sulfide solid electrolytes and polymer solid electrolytes, and the sulfide solid electrolytes are considered to be materials with wide industrialization prospects due to high ionic conductivity. But the sulfide solid electrolyte membrane is difficult to form, the thickness of the pure sulfide solid electrolyte membrane is about 0.5-1 mm, and the volume energy density of the battery is too low due to the excessively large membrane thickness. Therefore, sulfide solid electrolytes are currently only available for laboratory-scale batteries, and the energy density is much lower than that of commercial liquid batteries.

In the prior art, technicians adopt methods such as pulse laser deposition, vapor deposition and the like to prepare corresponding solid electrolyte membranes, but the methods are high in cost and difficult to realize real industrialization. Recent research results show that the compounding of sulfide solid electrolyte and polymer is an effective solution, and Shuting Luo et al uses Li₆PS₅Cl and polyethylene oxide were compounded to produce a solid electrolyte membrane having a thickness of 65 μm.

However, the thickness still cannot completely satisfy the requirement of thinning the solid-state lithium battery, and it is necessary to find a thinner solid-state electrolyte membrane with better performance and apply the membrane to the lithium battery.

Disclosure of Invention

In view of the above problems in the prior art, an object of the present invention is to provide a sulfide solid electrolyte membrane and a solid lithium ion battery.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a sulfide solid state electrolyte membrane including a polymer film having a three-dimensional skeleton structure and a sulfide solid state electrolyte material forming a continuous phase; ion conductivity of the sulfide solid electrolyte membrane>10^-4S/cm, and the thickness of the sulfide solid electrolyte membrane is less than or equal to 40 mu m.

In the method of the present invention, the ionic conductivity of the sulfide solid electrolyte membrane may be, for example, 5X 10^-4S/cm、5.5×10^-4S/cm、6×10^-4S/cm or 10^-3S/cm and the like; the thickness of the sulfide solid electrolyte membrane may be, for example, 40 μm, 35 μm, 30 μm, 25 μm, or the like.

The invention uses the flexible polymer film as the skeleton supporting function, and the sulfide forms a continuous phase in the polymer film, thereby ensuring the ionic conductivity of the sulfide solid electrolyte film and greatly reducing the thickness of the solid electrolyte film.

The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.

Preferably, the polymer membrane is a PVDF membrane or a PVDF-based polymer membrane, and the molecular structure of the PVDF-based polymer membrane is P (VDF-B) or P (VDF-B-A);

wherein, B is selected from any one of Trifluoroethylene (TrFE), Hexafluoropropylene (HFP) or Methyl Methacrylate (MMA) or the combination of at least two of them; a is selected from any one of Chlorotrifluoroethylene (CTFE), 1-chlorofluoroethylene (1, 1-chlorotrifluoroethylene, CFE) or difluorochloroethylene (CDFE), or the combination of at least two of the materials;

the mass fraction of the VDF monomer-based structural units in the PVDF-based polymer membrane is a, a is more than or equal to 50 percent, such as 50 percent, 55 percent, 60 percent, 65 percent, 70 percent, 75 percent or 80 percent;

the PVDF-based polymer film has a mass fraction of structural units based on the A monomer of b.ltoreq.20%, for example, 20%, 18%, 15%, 10%, 7%, 6%, 5%, 3%, or 1%.

In the above preferred embodiment, since the mass fraction of the structural unit based on the VDF monomer in the PVDF-based polymer membrane is 50% or more, and the mass fraction of the structural unit based on the B monomer in the PVDF-based polymer membrane is 50% or less, for example, 45%, 40%, 35%, 30%, 25%, or 20% in the case where the molecular structure of the PVDF-based polymer membrane is P (VDF-B); in the case where the molecular structure of the PVDF-based polymer film is P (VDF-B-a), the sum of the mass fraction of the structural unit based on the B monomer and the mass fraction of the structural unit based on the a monomer in the PVDF-based polymer film is 50% or less, for example, 50%, 45%, 40%, 35%, 30%, or 25%, and the like, and c may be 0.5%, 1%, 3%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, or 35%, and the like, for example.

The polymer membrane has good flexibility, can provide good framework supporting effect, is favorable for ensuring the continuity of the sulfide solid electrolyte membrane, and enables the sulfide solid electrolyte membrane to obtain high ionic conductivity under the condition of very thin thickness.

According to the invention, the polymer membrane is prepared by using an electrostatic spinning method, a three-dimensional framework structure is formed by fibers, and the grid holes are free of directionality, so that on one hand, good mechanical properties are ensured, and on the other hand, the sulfide solid electrolyte is favorable for forming a continuous phase and the advantage of improving the ionic conductivity of the sulfide solid electrolyte membrane is better exerted.

As a preferable technical scheme of the sulfide solid electrolyte membrane, the polymer membrane is a PVDF-based polymer membrane, the molecular structure of the polymer membrane is P (VDF-B), B is trifluoroethylene, the mass fraction of a structural unit based on a trifluoroethylene monomer in the polymer membrane is c, and c is less than or equal to 50%. At this time, the molecular structure of the polymer membrane is also P (VDF-TrFE).

P (VDF-TrFE) vs Li compared to other PVDF-based polymers₆PS₅The sulfide solid electrolyte such as Cl has interaction force and bonding effect, so that a lithium conducting path is formed at the position where sulfide and polymer are combined, and the performance of the solid electrolyte membrane is improved.

In some embodiments, the maximum mesh pore size of the polymer membrane is 30 μm.

It should be noted that the "mesh aperture" described in the present invention refers to: equivalent diameter of the through-hole in the three-dimensional skeleton structure.

It will be understood by those skilled in the art that for a through hole formed by a plurality of holes communicating, the equivalent diameter refers to the diameter of the partial hole, for example for fig. 2(a), see the double-headed arrow mark.

Preferably, the polymer membrane has a mesh pore size D50 of 10 μm to 18 μm, such as 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, or 18 μm. More preferably, the polymer membrane has a mesh pore size D90 of 10 to 18 μm.

In the present invention, the mesh aperture D50 is A to B, meaning that 50% or more of the mesh apertures are in the range of A to B. The mesh aperture D90 is A-B, meaning that 90% or more of the mesh apertures are in the A-B range. Illustratively, the topographical map can be obtained by SEM, then the dimensions measured, and the results statistically obtained.

Preferably, the polymer film has a non-oriented network of pores.

Preferably, the polymer film is prepared by electrospinning.

Preferably, the sulfide solid state electrolyte material includes Li₂S-P₂S₅、Li₂S-P₂S₅-MS_x、Li_3.4Si_0.4P_0.6S₄、Li₁₀GeP₂S_11.7O_0.3、Li_9.6P₃S₁₂、Li₇P₃S₁₁、Li₉P₃S₉O₃、Li_10.35Si_1.35P_1.65S₁₂、Li_9.81Sn_0.81P_2.19S₁₂、Li₁₀(Si_0.5Ge_0.5)P₂S₁₂、Li(Ge_0.5Sn_0.5)P₂S₁₂、Li(Si_0.5Sn_0.5)PsS₁₂、Li₁₀GeP₂S₁₂(LGPS)、Li₆PS₅X、Li₇P₂S₈I、Li_10.35Ge_1.35P_1.65S₁₂、Li_3.25Ge_0.25P_0.75S₄、Li₁₀SnP₂S₁₂、Li₁₀SiP₂S₁₂Or Li_9.54Si_1.74P_1.44S_11.7C_l0.3Wherein M is selected from any one or the combination of at least two of Si, Ge or Sn, X is selected from any one or the combination of at least two of Cl, Br or I, and X is more than or equal to 0 and less than or equal to 2.

Preferably, the sulfide solid state electrolyte material is Li₆PS₅X, wherein X is Cl, Br or I.

Preferably, the sulfide solid state electrolyte material forms a continuous phase within the polymer film by being prepared as a solution and poured onto the polymer film.

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

Preferably, the particle size of the sulfide solid state electrolyte material is 50% to 70%, such as 50%, 55%, 60%, 65%, or 70%, etc., of the maximum mesh pore size of the polymer membrane.

Preferably, the sulfide solid electrolyte membrane contains a lithium salt therein.

Preferably, the lithium salt accounts for 0 to 30 mass percent of the polymer in the polymer film and is not contained in the polymer film, more preferably 5 to 20 mass percent, and particularly preferably 5 to 15 mass percent.

Illustratively, the present invention provides a method of producing the sulfide solid electrolyte membrane described above, including the steps of:

s1: preparing the polymer film;

s2: pouring a solution containing sulfide solid electrolyte particles onto the polymer film obtained in step S1;

s3: drying and hot-pressing to form a film to obtain the sulfide solid electrolyte film;

ion conductivity of the sulfide solid electrolyte membrane>10^-4S/cm, wherein the thickness of the sulfide solid electrolyte membrane is less than or equal to 40 mu m;

wherein, in the step S1, the maximum mesh pore size of the prepared polymer film is larger than the particle size of the sulfide solid electrolyte particles in the step S2.

Preferably, in the step S1, the polymer film is an internal three-dimensional interconnected structure.

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

Preferably, step S2 further includes a step of thickness control.

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

The type of the solid-state lithium ion battery is not particularly limited in the present invention, and may be, for example, a lithium sulfur battery, a lithium ion battery, a lithium-iron disulfide battery, or a lithium-titanium sulfide battery.

The negative electrode of the lithium-sulfur battery can be metallic lithium, and the positive active material adopted by the positive electrode of the lithium-sulfur battery can be a sulfur-carbon composite material, and the formula and the composition of the lithium-sulfur battery are not described again.

Illustratively, the present invention provides a method for preparing the sulfur-carbon composite material, comprising: mixing sulfur steam and a conductive additive, wherein the mass ratio of the sulfur steam to the conductive additive can be adjusted according to actual use requirements, and heating at the temperature of 145-160 ℃ after mixing the sulfur steam and the conductive additive to obtain the sulfur-carbon composite.

As an embodiment, the conductive additive used for preparing the sulfur-carbon composite material includes, but is not limited to, any one or a combination of at least two of carbon black materials such as acetylene black, supp, super s, 350G, carbon fiber (VGCF), Carbon Nanotubes (CNTs), or ketjen black.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention combines the polymer film with a three-dimensional skeleton structure and the sulfide solid electrolyte material of a continuous phase, and can obtain high ionic conductivity while reducing the thickness.

(2) The invention provides a preferable preparation method of the sulfide solid electrolyte membrane, which is characterized in that a copolymer is prepared into a polymer membrane through electrospinning, a three-dimensional framework is formed by a three-dimensional through hole structure in the polymer membrane, so that the whole supporting membrane becomes flexible, sulfide solid electrolyte particles can form a continuous phase in the network through methods such as pouring, hot pressing and the like, a three-dimensional seepage network is formed, and the sulfide solid electrolyte membrane with high ionic conductivity and thin thickness is prepared.

(3) The PVDF-based polymer is preferably used as the main component of the polymer membrane, the PVDF-based polymer and the sulfide solid electrolyte have better matching performance, and the formed solid electrolyte membrane has high ionic conductivity and thinner thickness, and is beneficial to improving the performance of the battery.

(4) P (VDF-TrFE) vs. Li for other PVDF-based polymers₆PS₅The sulfide solid electrolyte such as Cl has interaction force and bonding effect, so that a lithium conducting path is formed at the position where sulfide and polymer are combined, and the performance of the solid electrolyte membrane is improved.

Drawings

FIG. 1 is a physical diagram of a sulfide solid electrolyte membrane produced in example 1;

FIG. 2(a) is an SEM image of a P (VDF-TrFE) electrospun membrane prepared in example 1;

FIG. 2(b) is an SEM image of a P (VDF-TrFE) electrospun membrane prepared in example 2;

FIG. 2(c) is an SEM image of a P (VDF-TrFE) electrospun membrane prepared in example 3;

FIG. 3(a) is an SEM image of a P (VDF-TrFE) electrospun membrane prepared in example 4;

FIG. 3(b) is an SEM image of a P (VDF-TrFE) electrospun membrane prepared in example 5;

fig. 4 is an SEM image of the solid electrolyte membrane prepared in example 1;

FIG. 5 is a graph of cycle performance for example 7 and comparative example 1, where Li₆PS₅Cl @ P (VDF-TrFe) corresponds to example 7, Li₆PS₅Cl corresponds to comparative example 1;

FIG. 6 shows Li in example 6₆PS₅Nuclear magnetic resonance spectrum comparison graph of Cl @ PVDF solid electrolyte membrane and PVDF membrane;

FIG. 7 shows Li in example 1₆PS₅Nuclear magnetic resonance spectrum comparison of Cl @ P (VDF-TrFE) solid electrolyte membrane and P (VDF-TrFE) membrane.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In a first aspect, the present embodiment provides a sulfide solid state electrolyte membrane that includes a polymer film having a three-dimensional skeleton structure and a sulfide solid state electrolyte material that forms a continuous phase; ion conductivity of the sulfide solid electrolyte membrane>10^-4S/cm, and the thickness of the sulfide solid electrolyte membrane is less than or equal to 40 mu m.

In the embodiment of the invention, the flexible polymer film is used as a skeleton supporting function, and the sulfide forms a continuous phase in the polymer film, so that the ionic conductivity of the sulfide solid electrolyte film is ensured, and the thickness of the solid electrolyte film is greatly reduced.

As an embodiment, the molecular structure of the polymer membrane is P (VDF-B), B is selected from any one or the combination of at least two of trifluoroethylene, hexafluoropropylene or methyl methacrylate, the mass fraction of the structural unit based on the VDF monomer in the polymer membrane is more than or equal to 50 percent, and the mass fraction of the structural unit based on the B monomer in the polymer membrane is less than or equal to 50 percent.

In one embodiment, the molecular structure of the polymer film is P (VDF-B-A), B is selected from any one or combination of at least two of trifluoroethylene, hexafluoropropylene or methyl methacrylate, A is selected from any one or combination of at least two of chlorotrifluoroethylene, 1-chlorofluoroethylene or difluorochloroethylene, the mass fraction of structural units based on VDF monomers in the polymer film is greater than or equal to 50%, the mass fraction of structural units based on A monomers in the polymer film is less than or equal to 20%, and the sum of the mass fraction of structural units based on A monomers in the polymer film and the mass fraction of structural units based on B monomers in the polymer film is less than or equal to 50%.

As an embodiment, the molecular structure of the polymer membrane is P (VDF-TrFE), and the mass fraction of the structural unit based on the TrFE monomer in the polymer membrane is less than or equal to 50%.

The ionic conductivity is mainly provided by a sulfide solid electrolyte of a continuous phase, so as an implementation mode, the embodiment of the invention has no special requirement on the molar ratio of each monomer in the polymer membrane preparation raw material.

In one embodiment, the polymer film P (VDF-TrFE) is prepared from 80% to 20% to 50% of VDF, for example 80% to 20%, 75% to 25%, 70% to 30%, 65% to 35%, 60% to 40%, 55% to 45%, 50% to 50%, etc., in terms of molar ratio.

As an embodiment, in the raw material for producing the polymer film P (VDF-TrFE), the molar ratio of VDF to TrFE is 70% to 30%.

As an embodiment, the present application does not specifically require the molecular weight of the polymer, as long as the polymer can normally form a film to form a three-dimensional skeleton.

As an embodiment, the polymer film is an internal three-dimensional interconnected structure.

In one embodiment, the polymer membrane has a maximum mesh pore size of 30 μm.

In one embodiment, the polymer membrane has a mesh opening size D50 of 10 to 18 μm, and more preferably a mesh opening size D90 of 10 to 18 μm.

In the embodiment of the invention, no special requirement is imposed on the preparation method of the polymer film, and only the polymer skeleton forming a three-dimensional network structure needs to be prepared, and the polymer skeleton needs to be capable of accommodating the 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 conducting path.

As an embodiment, the polymer film has a non-oriented network of pores.

As a particularly preferred embodiment, the polymer film is prepared by electrospinning.

The polymer membrane is prepared by using an electrostatic spinning method, a three-dimensional framework structure is formed by fibers, and the grid holes are free of directionality, so that on one hand, good mechanical properties are ensured, on the other hand, the sulfide solid electrolyte is favorable for forming a continuous phase, and the advantage of improving the ionic conductivity of the sulfide solid electrolyte membrane is better played.

Since film formation by not easy pressing is a common problem of sulfide solid electrolytes, and thus, the kind of sulfide solid electrolyte is not particularly limited in the embodiments of the present invention, sulfide solid electrolytes known in the art can be used in the present invention, including but not limited to Li₂S-P₂S₅、Li₂S-P₂S₅-MS_x、Li_3.4Si_0.4P_0.6S₄、Li₁₀GeP₂S_11.7O_0.3、Li_9.6P₃S₁₂、Li₇P₃S₁₁、Li₉P₃S₉O₃、Li_10.35Si_1.35P_1.65S₁₂、Li_9.81Sn_0.81P_2.19S₁₂、Li₁₀(Si_0.5Ge_0.5)P₂S₁₂、Li(Ge_0.5Sn_0.5)P₂S₁₂、Li(Si_0.5Sn_0.5)PsS₁₂、Li₁₀GeP₂S₁₂、Li₆PS₅X、Li₇P₂S₈I、Li_10.35Ge_1.35P_1.65S₁₂、Li_3.25Ge_0.25P_0.75S₄、Li₁₀SnP₂S₁₂、Li₁₀SiP₂S₁₂Or Li_9.54Si_1.74P_1.44S_11.7C_l0.3Any one of orAt least two combinations, wherein M is selected from any one or at least two combinations of Si, Ge or Sn, X is selected from any one or at least two combinations of Cl, Br or I, and X is more than or equal to 0 and less than or equal to 2.

As a particularly preferred embodiment, the sulfide solid electrolyte is Li₆PS₅X, wherein X is Cl, Br, I.

As one embodiment, the sulfide solid state electrolyte material forms a continuous phase within the polymer film by being prepared as a solution and poured onto the polymer film.

As an embodiment, the particle size of the sulfide solid state electrolyte material is smaller than the maximum mesh pore size of the polymer membrane. Further preferably, the particle size of the sulfide solid electrolyte particles is 50% to 70%, most preferably 60%, of the maximum mesh pore size of the polymer membrane.

The mesh aperture with proper size is beneficial to the sulfide solid electrolyte particles to form a continuous phase in a mode of preparing a solution to perfuse the polymer membrane; if the mesh aperture is too small, the sulfide solid electrolyte cannot be completely poured into the polymer, which affects the ionic conductivity of the finally formed sulfide solid electrolyte membrane.

As one embodiment, the sulfide solid state electrolyte membrane includes a lithium salt effective to increase the ionic conductivity of the sulfide solid state electrolyte membrane.

In the embodiment of the present invention, the kind of the lithium salt is not particularly limited, and any known lithium salt can be used in the present invention without departing from the inventive concept of the present application. Known lithium salts include inorganic lithium salts including, but not limited to, lithium perchlorate (LiClO), organic lithium salts, or mixtures of inorganic and organic lithium salts₄) Lithium tetrafluoroborate (LiBF)₄) Lithium hexafluoroarsenate (LiAsF)₆) Or lithium hexafluorophosphate (LiPF)₆) Any one or a combination of at least two of; organic lithium salts include, but are not limited to, lithium bis (oxalato) borate (LiBOB), lithium difluoro (oxalato) borate (LIFOB), lithium bis (difluorosulfonimide) (LiFSI), lithium bis (trifluoromethylsulfonimide) (MSDS), lithium triflate (LiCF)₃SO₃) Or two (three)Lithium fluoromethylsulfonyl imide (LiN (CF)₃SO₂)₂) Any one or a combination of at least two of them.

Preferably, the mass ratio of the lithium salt to the polymer in the polymer film is 0% to 30% and does not contain 0%, more preferably 5% to 20%, and particularly preferably 5% to 15%.

The ionic conductivity of the finally prepared sulfide solid electrolyte membrane reaches 10^-4S/cm and a thickness of less than 40 mu m, and a relatively complete sulfide solid electrolyte membrane with high ionic conductivity and relatively thin thickness is prepared for the first time.

An embodiment of the present invention further provides a method for producing the above sulfide solid electrolyte membrane, including:

s1: preparing the polymer film;

s3: drying and hot-pressing to form a film to obtain a sulfide solid electrolyte film;

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

In one embodiment, in step S1, the molecular structure of the polymer film is P (VDF-B), 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 the VDF monomer in the polymer film is greater than or equal to 50%, and the mass fraction of the structural units based on the B monomer in the polymer film is less than or equal to 50%.

In one embodiment, in step S1, the molecular structure of the polymer film is P (VDF-B-a), B is selected from any one or a combination of at least two of trifluoroethylene, hexafluoropropylene, or methyl methacrylate, a is selected from any one or a combination of at least two of chlorotrifluoroethylene, 1-chlorofluoroethylene, or difluorochloroethylene, the mass fraction of structural units based on the VDF monomer in the polymer film is equal to or greater than 50%, the mass fraction of structural units based on the a monomer in the polymer film is equal to or less than 20%, and the sum of the mass fraction of structural units based on the a monomer in the polymer film and the mass fraction of structural units based on the B monomer in the polymer film is equal to or less than 50%.

In the embodiment of the present invention, there is no particular requirement on the molar ratio of each monomer in the raw materials for preparing the polymer film in step S1.

In one embodiment, in step S1, the molar ratio of VDF to TrFE (VDF to TrFE) in the raw material for preparing the polymer film P (VDF-TrFE) is 80% to 20% to 50%.

As an embodiment, in step S1, in the raw material for preparing the polymer film P (VDF-TrFE), the molar ratio of VDF to TrFE is 70% to 30%.

In one embodiment, in step S1, the polymer film is an internal three-dimensional interconnected structure.

In one embodiment, in step S1, the maximum mesh pore size of the polymer membrane is 30 μm.

In one embodiment, in step S1, the polymer film has a mesh pore size D50 of 10 μm to 18 μm, and more preferably, the polymer film has a mesh pore size D90 of 10 μm to 18 μm.

As one embodiment, in step S1, a polymer film is prepared by electrospinning.

In the embodiment of the present invention, the method for preparing the electrospun membrane is not particularly limited, and as an embodiment, the corresponding polymeric electrospun membrane can be prepared by dissolving the polymeric particles in a solvent to obtain a precursor solution of the polymer, and then electrospinning under the action of an electric field.

As a particularly preferred embodiment, the polymer in the precursor solution of the polymer is P (VDF-TrFE).

In the embodiment of the present invention, the solvent in the precursor solution of the polymer is not particularly limited as long as the polymer particles can be uniformly dissolved, and may be N, N-dimethylamide, acetone, ethanol, ethylene glycol monomethyl ether, or the like as an embodiment.

In general, the concentration of the precursor solution prepared at the time of electrospinning, the time and speed of electrospinning, and the like affect the thickness of the spun film. The embodiment of the invention has no special limitation on the technical parameters of electrospinning, as long as the corresponding spinning membrane is prepared.

In the embodiment of the present invention, the process parameters such as the electric field intensity are not particularly limited, but the electric field intensity should be larger than the critical electric field intensity of the electrospinning, and as an embodiment, the electric field intensity is 0.5kV/cm to 2kV/cm, preferably 1kV/cm to 1.6 kV/cm.

As an embodiment, a lithium salt is added during the preparation of the polymer film in step S1, and the lithium salt is mixed with the polymer in step S1 to prepare a precursor solution, and the polymer film is prepared using electrospinning.

The pre-mixing of the lithium salt and the polymer before film formation is beneficial to the uniformity degree of mixing of the lithium salt and the polymer and improves the interaction of the lithium salt and the polymer.

In the embodiment of the present invention, the kind of the lithium salt added to the precursor solution is not particularly limited, and any known lithium salt can be used in the present invention without departing from the inventive concept of the present application. Known lithium salts include inorganic lithium salts including, but not limited to, lithium perchlorate (LiClO), organic lithium salts, or mixtures of inorganic and organic lithium salts₄) Lithium tetrafluoroborate (LiBF)₄) Lithium hexafluoroarsenate (LiAsF)₆) Or lithium hexafluorophosphate (LiPF)₆) Any one or a combination of at least two of; organic lithium salts include, but are not limited to, lithium bis (oxalato) borate (LiBOB), lithium difluoro (oxalato) borate (LIFOB), lithium bis (difluorosulfonimide) (LiFSI), lithium bis (trifluoromethylsulfonimide) (MSDS), lithium triflate (LiCF)₃SO₃) Or lithium bis (trifluoromethylsulfonyl) imide (LiN (CF)₃SO₂)₂) Any one or a combination of at least two of them.

In one embodiment, the lithium salt in the precursor solution is 0% to 30% by mass of the polymer in the polymer film and is not 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%, and the like, more preferably 5% to 20%, and particularly preferably 5% to 15%.

In the electrospinning process, due to the existence of anions and cations carried by lithium salt, the electric field of a spinning machine can be influenced in the electrospinning forming process of the polymer film, and the grid hole orientation of the formed polymer film is too high. Therefore, the amount of the lithium salt used is favorably in a suitable range.

Orientation means that in a polymer film, polymer spinning is arranged in a fixed direction to form regular grid hole arrangement.

In one embodiment, in step S1, the polymer film has non-directional cell pores.

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

In the embodiment of the present invention, there is no particular limitation on the kind of the sulfide solid electrolyte particles in step S2, and any sulfide solid electrolyte known in the art can be used in the present invention, including but not limited to Li₂S-P₂S₅、Li₂S-P₂S₅-MS_x、Li_3.4Si_0.4P_0.6S₄、Li₁₀GeP₂S_11.7O_0.3、Li_9.6P₃S₁₂、Li₇P₃S₁₁、Li₉P₃S₉O₃、Li_10.35Si_1.35P_1.65S₁₂、Li_9.81Sn_0.81P_2.19S₁₂、Li₁₀(Si_0.5Ge_0.5)P₂S₁₂、Li(Ge_0.5Sn_0.5)P₂S₁₂、Li(Si_0.5Sn_0.5)PsS₁₂、Li₁₀GeP₂S₁₂、Li₆PS₅X、Li₇P₂S₈I、Li_10.35Ge_1.35P_1.65S₁₂、Li_3.25Ge_0.25P_0.75S₄、Li₁₀SnP₂S₁₂、Li₁₀SiP₂S₁₂Or Li_9.54Si_1.74P_1.44S_11.7C_l0.3Wherein M is selected from any one or the combination of at least two of Si, Ge or Sn, X is selected from any one or the combination of at least two of Cl, Br or I, and X is more than or equal to 0 and less than or equal to 2.

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

The dispersion method according to the embodiment of the present invention is not particularly limited, and a mechanical dispersion method such as mechanical stirring may be employed, and it is only necessary to form a homogeneous solution of sulfide electrolyte particles in a solvent.

As an embodiment, step S2 further includes a step of controlling the thickness.

The thickness control means that the thickness of the polymer film after impregnation of the sulfide solid electrolyte is controlled within a specific thickness range, for example, within 40 μm.

The method of controlling the thickness according to the embodiment of the present invention is not particularly limited, and as an embodiment, the doctor blade coating may be performed by using a doctor blade having a thickness adjusting knob.

In one embodiment, the drying step S3 is performed to remove excess solvent, and a drying method is known, for example, the electrolyte membrane poured is dried in a constant temperature dryer.

The temperature and time for drying are not particularly required in the embodiment of the present invention, and the drying may be performed, for example, at 100 to 150 ℃ for 1 to 10 hours.

In a second aspect, the present embodiment provides a solid-state lithium ion battery comprising a positive electrode, a negative electrode and the sulfide solid electrolyte membrane prepared in the above embodiments.

In an embodiment of the present invention, the negative electrode is formed of a lithium host material that can be used as a negative electrode terminal of a lithium ion battery. For example, the negative electrode may include a lithium host material capable of functioning as a negative electrode terminal for a battery. In various aspects, the anode may be defined by a plurality of anode active material particles, and such anode active material particles may be disposed in one or more layers so as to define a three-dimensional structure of the anode.

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

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

In one embodiment, the anode is a silicon-based anode active material comprising silicon, such as a silicon alloy and/or silicon oxide. In one embodiment, the silicon-based negative active material may also be mixed with graphite.

In one embodiment, the negative electrode may include a carbonaceous-based negative active material including any one of graphite, graphene, or Carbon Nanotubes (CNTs), or a combination of at least two thereof.

In one embodiment, the negative electrode includes one or more negative active materials that accept lithium, such as lithium titanium oxide (Li)₄Ti₅O₁₂) Transition metal (e.g., Sn), metal oxide (e.g., V)₂O₅) Tin oxide (SnO), titanium dioxide (TiO)₂) Titanium niobium oxide (Ti)_xNb_yO_zWhere 0. ltoreq. x.ltoreq.2, 0. ltoreq. y.ltoreq.24, 0. ltoreq. z.ltoreq.64), metal alloys (e.g. copper-tin alloys (Cu)₆Sn₅) Or a metal sulfide (e.g., iron sulfide (FeS)))Means one or a combination of at least two.

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

As an embodiment, the anode active material may be doped with a conductive material such as: any one or a combination of at least two of carbon-based materials, powdered nickel, other metal particles, or conductive polymers. Alternatively, the carbon-based material may include, for example, at least one particle of carbon black, graphite, super p, acetylene black (e.g., KETCHENTM black or denka black), carbon fiber, carbon nanotubes, graphene, or the like. Alternatively, the conductive polymer may include at least one of polyaniline, polythiophene, polyacetylene, polypyrrole, poly (3, 4-ethylenedioxythiophene) polysulfonylstyrene, or the like.

As an embodiment, the anode active material may be doped with a binder such as: poly (tetrafluoroethylene) (PTFE), sodium carboxymethylcellulose (CMC), Styrene Butadiene Rubber (SBR), polyvinylidene fluoride (PVDF), Nitrile Butadiene Rubber (NBR), styrene ethylene butylene styrene copolymer (SEBS), styrene butadiene styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof.

As an embodiment, the negative electrode may include 50% to 97% of a negative active material, optionally 0% to 60% of a solid electrolyte, optionally 0% to 15% of a conductive material, and optionally 0% to 10% of a binder. It should be noted that "optional" means that the corresponding substance may or may not be included, and that the corresponding substance is not included when the content is 0%.

As an embodiment, the positive electrode comprises a positive electroactive material layer comprising a lithium-based positive electroactive material.

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

As an embodiment, the positive electrode electroactive material layer is formed of a plurality of positive electrode active particles including 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).

As an embodiment, the positive electrode electroactive material layer is one of a layered oxide cathode, a spinel cathode, an olivine-type cathode, or a polyanion cathode.

As an embodiment, a layered oxide cathode (e.g., a rock salt layered oxide cathode) comprises one or more lithium-based positive electroactive materials selected from the group consisting of: LiCoO₂(LCO)，LiNi_aMn_bCo_1-a-bO₂(wherein a is not less than 0 and not more than 1, and b is not less than 0 and not more than 1), LiNi_1-c-dCo_cAl_dO₂(where c is 0. ltoreq. c.ltoreq.1 and d is 0. ltoreq. d.ltoreq.1), LiNi_eMn_1-eO₂(wherein 0. ltoreq. e.ltoreq.1) or Li_1+fMO₂(wherein M is any one or a combination of at least two of Mn, Ni, Co or Al, and f is 0. ltoreq. f.ltoreq.1).

As an embodiment, the spinel cathode comprises one or more lithium-based positive electroactive materials selected from the group consisting of: LiMn₂O₄(LMO) and LiNi_0.5Mn_1.5O₄。

As an embodiment, the olivine-type cathode comprises one or more lithium-based positive electroactive materials LiMPO₄(wherein M is at least one of Fe, Ni, Co and Mn).

As an embodiment, the polyanionic cathode comprises one or more lithium-based positive electroactive materials: phosphates and/or silicates, phosphates such as LiV₂(PO₄)₃Silicates such as LiFeSiO₄。

As an embodiment, the positive electrode electroactive material layer further includes an electrolyte, such as a plurality of electrolyte particles.

As an embodiment, one or more lithium-based positive electroactive materials may optionally be coated and/or may be doped.

As aIn one embodiment, the compound is LiNbO₃And/or Al₂O₃One or more lithium-based positive electroactive materials are coated.

As an embodiment, the one or more lithium-based positive electroactive materials are doped by magnesium (Mg).

As an embodiment, one or more lithium-based positive electroactive materials may optionally be mixed with one or more conductive materials capable of providing an electron conduction path and/or at least one polymeric binder material that improves the structural integrity of the positive electrode.

As an embodiment, the positive electrode electroactive material layer may include 30% to 98% of one or more lithium-based positive electrode electroactive materials, 0% to 30% of a conductive material, and 0% to 20% of a binder, and in some embodiments, 1% to 20% of a binder.

As an embodiment, the lithium-based positive electroactive material may optionally be mixed with a binder as follows: polytetrafluoroethylene (PTFE), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), Nitrile Butadiene Rubber (NBR), styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, or lithium alginate, or a combination of at least two thereof.

As an embodiment, the lithium-based positive electrode electroactive material may optionally be mixed with a conductive material that may include any one or a combination of at least two of a carbon-based material, powdered nickel, other metal particles, or a conductive polymer. The carbon-based material may include, for example, any one or a combination of at least two of carbon black, graphite, acetylene black (e.g., KETCHENTM black or denk atm black), carbon fiber, carbon nanotubes, or graphene. The conductive polymer may include, for example, any one of polyaniline, polythiophene, polyacetylene, or polypyrrole, or a combination of at least two thereof.

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

Example 1

Mono, Li₆PS₅Preparation of Cl:

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

Li obtained by calcination₆PS₅The Cl powder was passed through a 400 mesh sieve to obtain electrolyte powder particles having a uniform particle size.

Preparation of P (VDF-TrFE) electrospun membrane

1.0g of P (VDF-TrFE) polymer particles was slowly dissolved in a mixed solvent of 3ml of Dimethylformamide (DMF) and 2ml of acetone to prepare raw materials of the P (VDF-TrFE) polymer particles, and VDF: TrFE (molar ratio) was 70%: 30%, to obtain a pure P (VDF-TrFE) precursor solution. Carrying out electrospinning on the P (VDF-TrFE) precursor solution under the conditions that the electric field strength is 1kV/cm and the flow rate is 1mL/h to prepare a P (VDF-TrFE) electrospinning membrane, wherein an SEM image of the membrane is shown in figure 2(a), and the mesh aperture D50 of the obtained P (VDF-TrFE) electrospinning membrane is 10-18 microns;

III, Li₆PS₅Preparation of Cl @ P (VDF-TrFE) sulfide solid electrolyte membrane

The Li obtained in the step one₆PS₅Cl particles were dissolved in toluene (99.9% purity) and mechanically stirred at 30 ℃ for 1h to obtain homogeneous Li₆PS₅And (4) Cl solution. Taking two sheets of P (VDF-TrFE) electrospinning films, and respectively adding Li₆PS₅Pouring Cl solution onto two sheets of P (VDF-TrFE) electrospun membranes, and controlling the thickness by using a scraper;

the impregnated sulfide solid electrolyte membrane was dried in a constant temperature drier at 120 ℃ for 2 hours to remove excess solvent, to obtain two sheets of composite solid electrolyte membranes. Then, the two sheets of the composite solid electrolyte were stacked and hot-pressed at 200 ℃ under 10MPa for 2 hours. All operations were performed in an argon atmosphere to obtain a sulfide solid electrolyte membrane.

The thickness of the finally obtained sulfide solid electrolyte membrane is 37 mu m, and the ionic conductivity is 1.2mS cm^-1。

FIG. 1 is a schematic view of a sulfide solid electrolyte membrane produced in example 1.

Fig. 2(a) is an SEM image of the P (VDF-TrFE) electrospun membrane prepared in example 1.

Fig. 4 is an SEM image of the solid electrolyte membrane prepared in example 1.

FIG. 7 shows Li in example 1₆PS₅Cl @ P (VDF-TrFE) solid electrolyte membrane NMR spectrum.

Example 2

In this example, compared to the preparation method of example 1, the mass of the P (VDF-TrFE) polymer particles in the preparation step of the P (VDF-TrFE) electrospun membrane was 0.6g, fig. 2(b) is an SEM image of the prepared P (VDF-TrFE) electrospun membrane, and the mesh pore size D50 of the obtained P (VDF-TrFE) electrospun membrane was 1 μm to 5 μm, which is otherwise the same as example 1.

The thickness of the finally obtained sulfide solid electrolyte membrane was 37 μm, and the ionic conductivity was 1.01X 10^-4S/cm。

Example 3

In this example, compared to the preparation method of example 1, the mass of the P (VDF-TrFE) polymer particles in the preparation step of the P (VDF-TrFE) electrospun membrane was 0.8g, fig. 2(c) is an SEM image of the prepared P (VDF-TrFE) electrospun membrane, and the mesh pore size D50 of the obtained P (VDF-TrFE) electrospun membrane was 5 μm to 10 μm, which is otherwise the same as example 1.

The thickness of the finally obtained sulfide solid electrolyte membrane was 37 μm, and the ionic conductivity was 5.3X 10^-4S/cm。

Example 4

In this example, in comparison with the preparation method of example 1, 0.6g of P (VDF-TrFE) polymer particles and 0.3g of lithium bis (fluorosulfonyl) imide salt (LiFSI) were slowly dissolved in a mixed solvent of 3ml of Dimethylformamide (DMF) and 2ml of acetone in the preparation step of P (VDF-TrFE) electrospun membrane, and the other was the same as example 1.

Fig. 3(a) is an SEM image of the P (VDF-TrFE) electrospun membrane prepared in example 4.

The finally obtained P (VDF-TrFE) electrospun membrane has certain directionality, and the oriented electrospun membrane is difficult to pour.

Example 5

In this example, in comparison with the preparation method of example 1, 1.0g of P (VDF-TrFE) polymer particles and 0.3g of lithium bis (fluorosulfonyl) imide salt (LiFSI) were slowly dissolved in a mixed solvent of 3ml of Dimethylformamide (DMF) and 2ml of acetone in the preparation step of P (VDF-TrFE) electrospun membrane, and the other was the same as example 1.

Fig. 3(b) is an SEM image of the P (VDF-TrFE) electrospun membrane prepared in example 5.

The finally obtained P (VDF-TrFE) electrospun membrane has improved directionality, namely, the directionality is weakened, and the perfusion difficulty is reduced.

Example 6

The PVDF membrane was prepared using the same electrospinning process as in example 1, and the rest was the same as in example 1.

Li finally obtained₆PS₅The Cl @ PVDF solid electrolyte membrane had a thickness of 37 μm and an ionic conductivity of 5X 10^-4S/cm。

example 7

This embodiment provides an S @ C | Li₆PS₅The preparation method of the Cl @ P (VDF-TrFE) | | Li-In battery comprises the following steps:

dissolving the multi-wall carbon nano tube in a sodium dodecyl benzene sulfonate solution with the mass fraction of 1%, and dissolving sulfur in tetrahydrofuran to form a protective solution. The protective solution was added to the multi-walled carbon nanotube solution and stirred vigorously. The suspension was separated and washed several times with distilled water to remove sodium dodecylbenzenesulfonate. And drying the obtained sulfur-carbon nanotube composite to obtain S @ C composite particles, wherein the mass ratio of the nano sulfur to the multi-wall carbon nanotubes is 6: 4.

The synthesized S @ C composite particles and Li₆PS₅The Cl was stirred in a ball mill at a stirring speed of 300rpm for 1h at a mass ratio of 4:6, and the resulting product was prepared to form a positive electrode.

The positive electrode and the Li-In negative electrode were used, and Li prepared In example 1 was used₆PS₅The Cl @ P (VDF-TrFE) sulfide solid electrolyte membrane stack forms an all solid-state lithium ion battery.

Example 8

This example provides a Li₆PS₅Cl@C||Li₆PS₅The preparation method of the Cl @ P (VDF-TrFE) | | Li-In battery comprises the following steps:

mixing Li₆PS₅The Cl and the multi-walled carbon nanotubes are mixed in a mass ratio of 7:3 and ball milled in a ball mill at a speed of 100rpm for one hour, and the obtained product is prepared to form the positive electrode.

After 180 cycles of the cell, no significant attenuation was seen.

Example 9

This embodiment provides an NCM @ LNO | | | Li₆PS₅The preparation method of the Cl @ P (VDF-TrFE) | | Li-In battery comprises the following steps:

commercial NCM811 pellets were heated at 90 ℃ for twelve hours before use, and LiOC was added₂H₅And Nb (OC)₂H5)₅After dissolving in absolute ethanol, NCM811 was added to the above solution and stirred for 3 hours. And drying the slurry at 150 ℃ for 12h, and heating the slurry at 400 ℃ for 1h in an oxygen atmosphere to form LNO coated NCM particles, and preparing the obtained product to form the anode.

After 1000 cycles of the cell, no significant attenuation was seen.

Example 10

With Li₂S is a positive electrode active material, and the rest is the same as example 7.

After 500 cycles of the cell, no significant decay was seen.

Example 11

By FeS₂The procedure of example 7 was repeated except that the positive electrode active material was used.

After 500 cycles of the cell, no significant decay was seen.

Comparative example 1

Compared with example 7, the difference is that the P (VDF-TrFE) sulfide solid electrolyte membrane is replaced with pure Li₆PS₅A Cl sulfide solid electrolyte membrane.

It is shown by combining FIG. 2(a) to FIG. 2(c) and examples 1 to 3 that the thickness of the sulfide solid electrolyte membrane obtained by impregnating the P (VDF-TrFE) polymer membrane with the sulfide solid electrolyte particles can be 40 μm or less. However, when the mesh pore size of the polymer membrane is too small, the pore size is limited by the particle size of the sulfide solid electrolyte particles, so that the perfusion effect is not ideal, and the larger sulfide particles are difficult to completely fill into the spinning mesh, so that the ion conductivity of the sulfide solid electrolyte membrane prepared in the embodiment 2-3 is low, and when the mesh pore size of the polymer membrane reaches more than 10 μm, the ion conductivity is obviously improved.

With reference to fig. 3(a) and 3(b), after the lithium salt is added, the charge of anions and cations carried by the lithium salt can affect the electric field of the spinning machine during electrospinning, so that the grids of the polymer electrospun membrane form directional arrangement; when the lithium salt concentration is reduced, the lattice orientation of the polymer electrospun membrane is reduced.

With reference to fig. 1 and 4, the thickness of the sulfide solid electrolyte membrane prepared in example 1 reaches 37 μm, the surface of the sulfide solid electrolyte membrane is uniformly distributed, the particles are uniformly poured into the polymer membrane, and the polymer membrane is completely covered by the particles.

FIG. 6 shows Li in example 6₆PS₅FIG. 7 is a graph showing the comparison of nuclear magnetic resonance spectra of a Cl @ PVDF solid electrolyte membrane and a PVDF membrane, and Li of example 1₆PS₅Comparing the nuclear magnetic resonance spectrum of the Cl @ P (VDF-TrFE) solid electrolyte membrane with that of the P (VDF-TrFE) membrane, and comparing the FIG. 6 with the FIG. 7, it can be seen that the nuclear magnetic resonance spectrum of the solid electrolyte membrane formed by pure PVDF and sulfide solid electrolyte is the same as that of pure PVDF, which proves that there is no interaction between pure PVDF and sulfide solid electrolyte; whereas the solid electrolyte membrane formed of P (VDF-TrFE) and the sulfide solid electrolyte has a different peak shape than pure P (VDF-TrFE), and thus it can be seen that the sulfide solid electrolyte membrane has a strong interaction with P (VDF-TrFE) rather than a pure physical mixture.

FIG. 5 is a graph of cycle performance for example 7 and comparative example 1, where Li₆PS₅Cl @ P (VDF-TrFe) corresponds to example 7, Li₆PS₅Cl corresponds to comparative example 1, and as can be seen from FIG. 5 and examples 7 and comparative example 1, pure Li is used₆PS₅The cell capacity of Cl sulfide solid electrolyte membranes declines faster because too thick a sulfide solid electrolyte membrane prolongs the ion conduction path, making the interface problem of the cell worse during charging and discharging.

As can be seen from examples 7 to 11, the sulfide solid electrolyte membrane according to the present application has good performance in various batteries, and has an advantage of wide application.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. A sulfide solid state electrolyte membrane, characterized by comprising a polymer film having a three-dimensional skeleton structure and a sulfide solid state electrolyte material forming a continuous phase; ion conductivity of the sulfide solid electrolyte membrane>10^-4S/cm, wherein the thickness of the sulfide solid electrolyte membrane is less than or equal to 40 mu m;

the polymer film is a PVDF-based polymer film, the molecular structure of the polymer film is P (VDF-B), B is trifluoroethylene, the mass fraction of a structural unit based on a trifluoroethylene monomer in the polymer film is c, and c is less than or equal to 50%;

the polymer film is prepared through electrospinning, and the grid holes of the polymer film are not directional.

2. The sulfide solid electrolyte membrane according to claim 1, wherein the polymer membrane has a mesh pore size D50 of 10 μm to 18 μm.

3. The sulfide solid state electrolyte membrane according to claim 1, wherein the sulfide solid state electrolyte material includes Li₂S-P₂S₅、Li₂S-P₂S₅-MS_x、Li_3.4Si_0.4P_0.6S₄、Li₁₀GeP₂S_11.7O_0.3、Li_9.6P₃S₁₂、Li₇P₃S₁₁、Li₉P₃S₉O₃、Li_10.35Si_1.35P_1.65S₁₂、Li_9.81Sn_0.81P_2.19S₁₂、Li₁₀(Si_0.5Ge_0.5)P₂S₁₂、Li(Ge_0.5Sn_0.5)P₂S₁₂、Li(Si_0.5Sn_0.5)PsS₁₂、Li₁₀GeP₂S₁₂、Li₆PS₅X、Li₇P₂S₈I、Li_10.35Ge_1.35P_1.65S₁₂、Li_3.25Ge_0.25P_0.75S₄、Li₁₀SnP₂S₁₂、Li₁₀SiP₂S₁₂Or Li_9.54Si_1.74P_1.44S_11.7Cl_0.3Wherein M is selected from any one or the combination of at least two of Si, Ge or Sn, X is selected from any one or the combination of at least two of Cl, Br or I, and X is more than or equal to 0 and less than or equal to 2.

4. The sulfide solid state electrolyte membrane according to claim 3, wherein the sulfide solid state electrolyte material is Li₆PS₅X, wherein X is Cl, Br or I.

5. The sulfide solid electrolyte membrane according to claim 3, wherein the sulfide solid electrolyte material forms a continuous phase within the polymer membrane by being prepared as a solution and poured onto the polymer membrane.

6. The sulfide solid electrolyte membrane according to claim 3, wherein the particle size of the sulfide solid electrolyte material is 50% to 70% of the maximum mesh pore size of the polymer membrane.

7. A solid state lithium ion battery comprising a cathode, an anode, and the sulfide solid state electrolyte membrane of any one of claims 1-6.