WO2023000604A1

WO2023000604A1 - Sulfide solid electrolyte membrane and solid lithium ion battery

Info

Publication number: WO2023000604A1
Application number: PCT/CN2021/138978
Authority: WO
Inventors: 冯玉川; 刘思捷; 何泓材; 李峥
Original assignee: 清陶(昆山)能源发展股份有限公司
Priority date: 2021-07-22
Filing date: 2021-12-17
Publication date: 2023-01-26
Also published as: CN114824449A; CN113451638A; CN113451638B

Abstract

The present disclosure relates to the field of lithium batteries, and provides a sulfide solid electrolyte membrane and a solid lithium ion battery. The sulfide solid electrolyte membrane 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 greater than 10 −4S/cm, and the thickness of the sulfide solid electrolyte membrane is less than or equal to 40 μm. The flexible polymer membrane acts as a support frame, and a sulfide forms a continuous phase in the polymer membrane, thereby ensuring the ionic conductivity of the sulfide solid electrolyte membrane and significantly reducing the thickness of the solid electrolyte membrane.

Description

A kind of sulfide solid electrolyte membrane and solid lithium ion battery

technical field

The embodiments of the present application relate to the field of lithium batteries, such as a sulfide solid-state electrolyte membrane and a solid-state lithium-ion battery.

Background technique

With the energy crisis and the requirements of environmental protection, new energy vehicles have received unprecedented attention, but the existing lithium-ion batteries are not fully safe due to the use of liquid electrolytes. In recent years, solid-state batteries using solid-state electrolytes have attracted extensive attention due to their high safety.

Existing solid-state electrolytes are mainly divided into three types: oxide solid-state electrolytes, sulfide solid-state electrolytes and polymer solid-state electrolytes, and sulfide solid-state electrolytes are considered to be a kind with broad industrialization prospects because of their high ionic conductivity. Material. However, it is difficult to form the sulfide solid-state electrolyte membrane. The thickness of the pure sulfide solid-state electrolyte membrane is about 0.5-1 mm. Excessive film thickness leads to low volumetric energy density of the battery. Therefore, at present, sulfide solid-state electrolytes can only be used in laboratory-scale batteries, and the energy density is much lower than that of industrial liquid batteries.

In related technologies, technicians have used methods such as pulsed laser deposition and vapor deposition to prepare corresponding solid electrolyte membranes, but these methods are expensive and difficult to truly industrialize. Recent research results have shown that the use of sulfide solid electrolytes and polymer composites is an effective solution. Shuting Luo et al. prepared a solid electrolyte membrane with a thickness of 65 microns by combining Li ₆ PS ₅ Cl and polyethylene oxide.

However, the above thickness still cannot fully meet the requirements of thinner and lighter solid-state lithium batteries. It is necessary to find a thinner and better-performing solid-state electrolyte membrane and apply it to lithium batteries.

Contents of the invention

The following is an overview of the topics described in detail in this article. This summary is not intended to limit the scope of the claims.

The present application provides a sulfide solid electrolyte membrane and a solid lithium ion battery.

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

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

In this application, the flexible polymer membrane is used as a skeleton support, and the sulfide forms a continuous phase in the polymer membrane, which ensures the ion conductivity of the sulfide solid electrolyte membrane and greatly reduces the thickness of the solid electrolyte membrane.

The following are the preferred technical solutions of the present application, but not as limitations on the technical solutions provided by the present application. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present application can be better achieved and realized.

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

Wherein, B is selected from any one or a combination of at least two of trifluoroethylene (Trifluoroethylene, TrFE), hexafluoropropylene (hexafluoropropylene, HFP) or methyl methacrylate (MMA); A is selected from three Any one or a combination of at least two of chlorofluoroethylene (chlorotrifluoroethylene, CTFE), 1,1-chlorofluoroethylene (1,1-chlorofluoroethylene, CFE) or chlorodifluoroethylene (Chlorodifluoroethylene cdfe, CDFE);

The mass fraction of structural units based on VDF monomers in the PVDF-based polymer film is a, where a≥50%, such as 50%, 55%, 60%, 65%, 70%, 75% or 80%;

The mass fraction of structural units based on A monomer in the PVDF-based polymer film is b, b≤20%, such as 20%, 18%, 15%, 10%, 7%, 6%, 5%, 3% or 1% etc.

In the above-mentioned preferred technical scheme, since the mass fraction of structural units based on VDF monomer 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 PVDF-based polymerization The mass fraction of the structural unit based on the B monomer in the film is less than or equal to 50%, for example, it can be 50%, 45%, 40%, 35%, 30%, 25% or 20%; for the molecules of the PVDF-based polymer film In the case of a structure of 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 less than or equal to 50%, for example, it can be 50% , 45%, 40%, 35%, 30% or 25%, etc. c, for example, can be 0.5%, 1%, 3%, 5%, 8%, 10%, 15%, 20%, 25%, 30% or 35% etc.

The polymer membrane of the present application has good flexibility and can provide a good skeleton support effect, which is beneficial to ensure the continuity of the sulfide solid electrolyte membrane, so that the sulfide solid electrolyte membrane can obtain high ion conductivity at a very thin thickness .

This application uses the method of electrospinning to prepare polymer membranes, forming a three-dimensional skeleton structure through fibers, and making the mesh holes non-directional, which ensures good mechanical properties on the one hand, and facilitates the formation of a continuous phase of sulfide solid electrolytes on the other hand And better play the advantage of improving the ionic conductivity of the sulfide solid electrolyte membrane.

As a preferred technical scheme of the sulfide solid electrolyte membrane described in the present application, the polymer membrane is a PVDF-based polymer membrane, the molecular structure is P(VDF-B), and B is trifluoroethylene, and in the polymer membrane The mass fraction of the structural unit based on the trifluoroethylene monomer is c, and c≤50%. At this time, the molecular structure of the polymer film is also P(VDF-TrFE).

Compared with other types of PVDF-based polymers, P(VDF-TrFE) has interaction and bonding with sulfide solid electrolytes such as Li ₆ PS ₅ Cl, which makes the position where the sulfide and polymer combine also form a conductive structure. Lithium pathways that enhance the performance of solid-state electrolyte membranes.

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

It should be noted that the "grid aperture" mentioned in this application refers to the equivalent diameter of the through holes in the three-dimensional skeleton structure.

Those skilled in the art should understand that for a through hole formed by connecting multiple holes, the equivalent diameter refers to the diameter of a local hole. For example, in FIG. 2A , the equivalent diameter is indicated by the double-headed arrow.

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

In the present application, the grid aperture D50 is A to B, which means that more than 50% of the grid apertures are within the range of A to B. The grid aperture D90 is A to B, which means that more than 90% of the grid apertures are in the range of A to B. Exemplarily, the topography can be obtained by SEM, then the dimensions can be measured, and the results can be obtained statistically.

Preferably, the mesh pores of the polymer film have no orientation.

Preferably, the polymer film is prepared by electrospinning.

Preferably, the sulfide solid electrolyte material includes Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -MS _x , Li _3.4 Si _0.4 P _0.6 S ₄ , Li ₁₀ GeP ₂ S _11.7 O _0.3 , Li _9.6 P ₃ S ₁₂ , Li ₇ P ₃ S ₁₁ , Li ₉ P ₃ S ₉ O ₃ , 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 )P ₂ S ₁₂ , Li(Ge _0.5 Sn _0.5 )P ₂ S ₁₂ , Li(Si _0.5 Sn _0.5 )PsS ₁₂ , Li ₁₀ GeP ₂ S ₁₂ (LGPS), Li ₆ PS ₅ X, Li ₇ P ₂ S ₈ I, Li _10.35 Ge _1.35 Any one or at least two of P _1.65 S ₁₂ , Li _3.25 Ge _0.25 P _0.75 S ₄ , Li ₁₀ SnP ₂ S ₁₂ , Li ₁₀ SiP ₂ S ₁₂ or Li _9.54 Si _1.74 P _1.44 S _11.7 C _l0.3 A combination, wherein M is selected from any one or a combination of at least two of Si, Ge or Sn, X is selected from any one or a combination of at least two of Cl, Br or I, and 0≤x≤2.

Preferably, the sulfide solid electrolyte material is Li ₆ PS ₅ X , wherein X is Cl, Br or I.

Preferably, the sulfide solid electrolyte material forms a continuous phase in the polymer membrane by making a solution and pouring it onto the polymer membrane.

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

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

Preferably, the sulfide solid electrolyte membrane contains lithium salt.

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

Exemplarily, the present application provides a method for preparing the above-mentioned sulfide solid electrolyte membrane, the method for preparing the sulfide solid electrolyte membrane includes the following steps:

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;

The ionic conductivity of the sulfide solid electrolyte membrane is >10 ^-4 S/cm, and the thickness of the sulfide solid electrolyte membrane is ≤40 μm;

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

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

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

Preferably, in step S2, a step of thickness control is also included.

In a second aspect, an embodiment of the present application provides a solid-state lithium-ion battery, which includes a positive electrode, a negative electrode, and the sulfide solid-state electrolyte membrane described in the first aspect.

The present application does not specifically limit the type of the solid-state lithium-ion battery, for example, it may be a lithium-sulfur battery, a lithium-ion battery, a lithium-iron disulfide battery or a lithium-titanium sulfide battery.

The negative electrode in the lithium-sulfur battery can be lithium metal, and the positive electrode active material used in the positive electrode in the lithium-sulfur battery can be a sulfur-carbon composite material. The formula and composition of the lithium-sulfur battery will not be repeated here.

Exemplarily, the present application provides a method for preparing the above-mentioned sulfur-carbon composite material, including: mixing sulfur vapor and conductive additives, wherein the mass ratio of sulfur vapor to conductive additives can be adjusted according to actual use needs, and the After sulfur vapor is mixed with conductive additives, it is heated at 145-160°C to obtain sulfur-carbon composites.

As an embodiment, the conductive additives used in the preparation of sulfur-carbon composite materials include but are not limited to any of carbon black materials such as acetylene black, SuperP, SuperS, 350G, carbon fiber (VGCF), carbon nanotubes (CNTs) or Ketjen Black. One or a combination of at least two.

Compared with the prior art, the embodiment of the present application has the following beneficial effects:

(1) In the embodiment of the present application, a polymer film with a three-dimensional skeleton structure is combined with a continuous phase sulfide solid electrolyte material, which can obtain high ion conductivity while reducing the thickness.

(2) The embodiment of the present application provides a preferred preparation method of the sulfide solid electrolyte membrane. The copolymer is prepared into a polymer film by electrospinning, and the three-dimensional through-hole structure in the polymer film forms a three-dimensional skeleton, so that the entire The support membrane becomes flexible, and then through perfusion, hot pressing and other methods, the sulfide solid electrolyte particles can form a continuous phase in the network, forming a three-dimensional percolation network, and a sulfide solid electrolyte membrane with high ion conductivity and thin thickness is prepared. .

(3) The embodiment of the present application preferably uses PVDF-based polymer as the main component of the polymer membrane. The PVDF-based polymer has a good match with the sulfide solid electrolyte, and the formed solid electrolyte membrane has high ion conductivity and relatively Thin thickness helps to improve battery performance.

(4) Compared with other PVDF-based polymers, P(VDF-TrFE) has interaction and bonding with sulfide solid electrolytes such as Li ₆ PS ₅ Cl, which makes the binding position of sulfide and polymer also form The lithium-conducting pathway improves the performance of the solid electrolyte membrane.

Other aspects will be apparent to others upon reading and understanding the drawings and detailed description.

Description of drawings

The accompanying drawings are used to provide a further understanding of the technical solutions herein, and constitute a part of the description, and are used together with the embodiments of the application to explain the technical solutions herein, and do not constitute limitations to the technical solutions herein.

Fig. 1 is the physical picture of the sulfide solid electrolyte membrane prepared in embodiment 1;

Fig. 2A is the SEM figure of the P (VDF-TrFE) electrospun membrane prepared in embodiment 1;

Fig. 2B is the SEM figure of the P (VDF-TrFE) electrospun membrane prepared in embodiment 2;

Fig. 2 C is the SEM picture of the P (VDF-TrFE) electrospun membrane prepared in embodiment 3;

Fig. 3 A is the SEM picture of the P (VDF-TrFE) electrospun membrane prepared in embodiment 4;

Fig. 3 B is the SEM picture of the P (VDF-TrFE) electrospun membrane prepared in embodiment 5;

Fig. 4 is the SEM picture of the solid electrolyte membrane prepared in embodiment 1;

Figure 5 is a cycle performance diagram of Example 7 and Comparative Example 1, wherein Li ₆ PS ₅ Cl@P(VDF-TrFe) corresponds to Example 7, and Li ₆ PS ₅ Cl corresponds to Comparative Example 1;

Fig. 6 is a comparison diagram of NMR spectra of Li ₆ PS ₅ Cl@PVDF solid electrolyte membrane and PVDF membrane in Example 6;

Fig. 7 is a comparison chart of the nuclear magnetic resonance spectra of the Li ₆ PS ₅ Cl@P(VDF-TrFE) solid electrolyte membrane and the P(VDF-TrFE) membrane in Example 1.

detailed description

The technical solution of the present application will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

In order to make the purpose, technical solutions and advantages of the application clearer, the technical solutions in the embodiments of the application will be clearly and completely described below, and the described embodiments are only part of the embodiments of the application, not all embodiments . Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

In the first aspect, this embodiment provides a sulfide solid electrolyte membrane, the sulfide solid electrolyte membrane includes a polymer film having a three-dimensional skeleton structure and a sulfide solid electrolyte material forming a continuous phase; the sulfide solid electrolyte membrane The ionic conductivity is >10 ^-4 S/cm, and the thickness of the sulfide solid electrolyte membrane is ≤40 μm.

In the embodiment of the present application, the flexible polymer membrane is used as a skeleton 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.

As an embodiment, the molecular structure of the polymer film is P(VDF-B), and B is selected from any one or a combination of at least two of trifluoroethylene, hexafluoropropylene or methyl methacrylate, The mass fraction of structural units based on VDF monomer in the polymer film is ≥ 50%, and the mass fraction of structural units based on B monomer in the polymer film is ≤ 50%.

As an embodiment, the molecular structure of the polymer film is P(VDF-B-A), and 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, 1,1-chlorofluoroethylene or difluorochloroethylene, and the mass fraction of structural units based on VDF monomer in the polymer film is ≥50% , the mass fraction of structural units based on monomer A in the polymer film is ≤ 20%, the mass fraction of structural units based on monomer A in the polymer film is the same as the mass fraction of structural units based on monomer B in the polymer film The sum of the scores ≤ 50%.

As an embodiment, the molecular structure of the polymer film is P(VDF-TrFE), and the mass fraction of structural units based on TrFE monomers in the polymer film is ≤50%.

The ionic conductivity is mainly provided by the sulfide solid electrolyte in the continuous phase. Therefore, as an implementation mode, the examples of the present application have no special requirements on the molar ratio of each monomer in the raw materials for polymer membrane preparation.

As an embodiment, in the raw materials for the preparation of the polymer film P (VDF-TrFE), VDF:TrFE (molar ratio)=80%:20%～50%:50%, such as 80%:20%, 75%: 25%, 70%: 30%, 65%: 35%, 60%: 40%, 55%: 45% or 50%: 50%, etc.

As an embodiment, among the raw materials for the preparation of the polymer film P(VDF-TrFE), VDF:TrFE (molar ratio)=70%:30%.

As an embodiment, the present application has no special requirements on the molecular weight of the polymer, as long as the polymer can form a film normally and form a three-dimensional skeleton.

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

As an implementation manner, the maximum mesh pore size of the polymer membrane is 30 μm.

As an embodiment, the mesh pore size D50 of the polymer membrane is 10 μm to 18 μm, more preferably the mesh pore size D90 of the polymer membrane is 10 μm to 18 μm.

In the embodiment of the present application, there is no special requirement for the preparation method of the polymer film, only a polymer skeleton forming a three-dimensional network structure is required. The polymer skeleton needs to be able to accommodate sulfide solid electrolyte particles, so that the sulfide solid electrolyte particles A continuous phase is formed in the three-dimensional network structure to provide lithium-conducting pathways.

As an embodiment, the mesh pores of the polymer film have no orientation.

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

The polymer membrane is prepared by electrospinning, and the three-dimensional skeleton structure is formed through the fibers, and the mesh holes are not oriented. Make good use of the advantages of improving the ionic conductivity of the sulfide solid electrolyte membrane.

Since it is not easy to press into a film, it is a common problem of sulfide solid-state electrolytes. Therefore, the embodiment of the present application does not specifically limit the type of sulfide solid-state electrolytes. All sulfide solid-state electrolytes known in the related art can be used in this application. Including but not limited to Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -MS _x , Li _3.4 Si _0.4 P _0.6 S ₄ , Li ₁₀ GeP ₂ S _11.7 O _0.3 , Li _9.6 P ₃ S ₁₂ , Li ₇ P ₃ S ₁₁ , Li ₉ P ₃ S ₉ O ₃ , 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 )P ₂ S ₁₂ , Li(Ge _0.5 Sn _0.5 ) P ₂ S ₁₂ , Li(Si _0.5 Sn _0.5 )PsS ₁₂ , Li ₁₀ GeP ₂ S ₁₂ , Li ₆ PS ₅ X, Li ₇ P ₂ S ₈ I, Li _10.35 Ge _1.35 P _1.65 S ₁₂ , Li _3.25 Ge _0.25 P Any one or a combination of at least two of _0.75 S ₄ , Li ₁₀ SnP ₂ S ₁₂ , Li ₁₀ SiP ₂ S ₁₂ or Li _9.54 Si _1.74 P _1.44 S _11.7 C _10.3 , wherein M is selected from Si, Ge Or any one or a combination of at least two of Sn, X is selected from any one or a combination of at least two of Cl, Br or I, 0≤x≤2.

As a particularly preferred embodiment, the sulfide solid electrolyte is Li ₆ PS ₅ X , where X=Cl, Br, I.

As an embodiment, the sulfide solid electrolyte material forms a continuous phase in the polymer membrane by making a solution and pouring it onto the polymer membrane.

As an embodiment, the particle size of the sulfide solid 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% of the maximum mesh pore size of the polymer membrane, most preferably 60%.

The mesh pore size of an appropriate size is conducive to the formation of a continuous phase by the sulfide solid electrolyte particles being made into a solution to perfuse the polymer membrane; if the mesh pore size is too small, the sulfide solid electrolyte cannot be completely poured into the polymer, which affects the final phase. Ionic conductivity of shaped sulfide solid electrolyte membranes.

As an embodiment, the sulfide solid electrolyte membrane includes a lithium salt, which can effectively improve the ion conductivity of the sulfide solid electrolyte membrane.

In the embodiment of the present application, there is no particular limitation on the type of lithium salt, and any known lithium salt can be used in the present application without departing from the concept of the present application. Known lithium salts include inorganic lithium salts, organic lithium salts or mixtures of inorganic lithium salts and organic lithium salts, inorganic lithium salts include but not limited to lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), hexa Any one or a combination of at least two of lithium fluoroarsenate (LiAsF ₆ ) or lithium hexafluorophosphate (LiPF ₆ ); organic lithium salts include but are not limited to lithium bisoxalate borate (LiBOB), lithium difluorooxalate borate (LIFOB), Lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethylsulfonyl imide (MSDS), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) or bis(trifluoromethylsulfonyl)imide Any one or a combination of at least two of lithium (LiN(CF ₃ SO ₂ ) ₂ ).

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

The sulfide solid electrolyte membrane finally prepared according to the embodiment of the present application has an ionic conductivity of 10 ^-4 S/cm and a thickness of less than 40 μm. For the first time, a relatively complete sulfide solid electrolyte membrane with high ionic conductivity and thin thickness has been produced.

The embodiment of the present application further provides a method for preparing the above-mentioned 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;

As an embodiment, in step S1, the polymer film is a PVDF film.

As an embodiment, in step S1, the molecular structure of the polymer film is P(VDF-B), and B is selected from any one or at least two of trifluoroethylene, hexafluoropropylene or methyl methacrylate. A combination of species, the mass fraction of the structural unit based on the VDF monomer in the polymer film is ≥ 50%, and the mass fraction of the structural unit based on the B monomer in the polymer film is ≤ 50%.

As an embodiment, in step S1, the molecular structure of the polymer film is P(VDF-B-A), and B is selected from any one or at least two of trifluoroethylene, hexafluoropropylene or methyl methacrylate. Combination, A is selected from any one or a combination of at least two of chlorotrifluoroethylene, 1,1-chlorofluoroethylene or difluorochloroethylene, and the mass fraction of structural units based on VDF monomer in the polymer film is ≥ 50%, the mass fraction of structural units based on monomer A in the polymer film is ≤ 20%, the mass fraction of structural units based on monomer A in the polymer film is the same as the structural unit based on monomer B in the polymer film The sum of the mass fractions is ≤50%.

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

As an embodiment, in step S1, among the raw materials for the preparation of the polymer film P(VDF-TrFE), VDF:TrFE (molar ratio)=80%:20%˜50%:50%.

As an embodiment, in step S1, among the raw materials for the preparation of the polymer film P(VDF-TrFE), VDF:TrFE (molar ratio)=70%:30%.

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

As an implementation manner, in step S1, the maximum mesh pore size of the polymer membrane is 30 μm.

As an embodiment, in step S1, the mesh pore diameter D50 of the polymer membrane is 10 μm˜18 μm, more preferably the mesh pore diameter D90 of the polymer membrane is 10 μm˜18 μm.

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

In the embodiment of the present application, the preparation method of electrospinning is not particularly limited. As an embodiment, polymer particles can be dissolved in a solvent to obtain a polymer precursor solution, and then electrospinning is performed under the action of an electric field. filaments to prepare corresponding polymer electrospun membranes.

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

In the embodiment of the present application, the solvent in the polymer precursor solution is not particularly limited, as long as the polymer particles can be uniformly dissolved. As an embodiment, it can be N,N-dimethylamide, acetone, Ethanol or, ethylene glycol monomethyl ether, etc.

Generally speaking, the concentration of the precursor solution prepared during electrospinning, the time and speed of electrospinning will affect the thickness of the spinning membrane. The embodiment of the present application has no special limitation on the process parameters of the electrospinning, as long as the corresponding spinning membrane is prepared.

In the embodiment of the present application, there are no special restrictions on the process parameters such as electric field strength, but the electric field strength should be greater than the critical electric field strength of electrospinning. As an embodiment, the electric field strength is 0.5kV/cm-2kV/cm, preferably 1kV /cm～1.6kV/cm.

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

The premixing of lithium salt and polymer before film formation is beneficial to the uniformity of mixing and improving the interaction between the two.

In the embodiment of the present application, the type of lithium salt added to the precursor solution is not particularly limited, and any known lithium salt can be used in the present application without departing from the concept of the application. Known lithium salts include inorganic lithium salts, organic lithium salts or mixtures of inorganic lithium salts and organic lithium salts, inorganic lithium salts include but not limited to lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), hexa Any one or a combination of at least two of lithium fluoroarsenate (LiAsF ₆ ) or lithium hexafluorophosphate (LiPF ₆ ); organic lithium salts include but are not limited to lithium bisoxalate borate (LiBOB), lithium difluorooxalate borate (LIFOB), Lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethylsulfonyl imide (MSDS), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) or bis(trifluoromethylsulfonyl)imide Any one or a combination of at least two of lithium (LiN(CF ₃ SO ₂ ) ₂ ).

As an embodiment, the lithium salt in the precursor solution accounts for 0%-30% by mass of the polymer in the polymer film and does not contain 0%, such as 0.5%, 1%, 2%, 2.5% , 3%, 4%, 5%, 5.5%, 6%, 8%, 9%, 10%, 12%, 15%, 17%, 20%, 22%, 25%, 27% or 30%, etc., More preferably, it is 5%-20%, Especially preferably, it is 5%-15%.

During the electrospinning process, due to the presence of anions and cations of the lithium salt, the electric field of the spinning machine will be affected during the electrospinning process of the polymer film, and the mesh holes in the formed polymer film Orientation is too high. Therefore, it is advantageous that the amount of the lithium salt used is within an appropriate range.

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

As an embodiment, in step S1, the mesh pores of the polymer film have no orientation.

As 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, most preferably 60%.

In the embodiment of the present application, there is no particular limitation on the type of sulfide solid electrolyte particles in step S2. All sulfide solid electrolytes known in the related art can be used in this application, including but not limited to Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -MS _x , Li _3.4 Si _0.4 P _0.6 S ₄ , Li ₁₀ GeP ₂ S _11.7 O _0.3 , Li _9.6 P ₃ S ₁₂ , Li ₇ P ₃ S ₁₁ , Li ₉ P ₃ S ₉ O ₃ , 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 )P ₂ S ₁₂ , Li(Ge _0.5 Sn _0.5 )P ₂ S ₁₂ , Li(Si _0.5 Sn _0.5 )PsS ₁₂ , Li ₁₀ GeP ₂ S ₁₂ , Li ₆ PS ₅ X, Li ₇ P ₂ S ₈ I, Li _10.35 Ge _1.35 P _1.65 S ₁₂ , Li _3.25 Ge _0.25 P _0.75 S ₄ , Li ₁₀ SnP ₂ S ₁₂ , Any one or a combination of at least two of Li ₁₀ SiP ₂ S ₁₂ or Li _9.54 Si _1.74 P _1.44 S _11.7 C _10.3 , wherein M is selected from any one or at least two of Si, Ge or Sn X is selected from any one or a combination of at least two of Cl, Br or I, 0≤x≤2.

As an embodiment, in step S2, it also includes putting the sulfide solid electrolyte particles into the solvent and dispersing to form a homogeneous solution. Solvents capable of uniformly dispersing sulfide solid electrolyte particles are known, including but not limited to benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, cyclohexanone, chlorobenzene, dichlorobenzene, Any one or a combination of at least two of methanol, ethanol, isopropanol or ether.

In the embodiment of the present application, there is no particular limitation on the dispersion method, and a mechanical dispersion method, such as mechanical stirring, can be used, as long as the sulfide electrolyte particles are formed into a homogeneous solution in a solvent.

As an implementation manner, in step S2, a step of thickness control is also included.

The thickness control refers to controlling the thickness of the polymer film perfused with the sulfide solid electrolyte within a specific thickness range, for example, within 40 μm.

The method of thickness control in the embodiment of the present application is not particularly limited. As an embodiment, scraping can be performed by using a scraper with a thickness adjustment knob.

As an implementation, in step S3, the purpose of drying is to remove excess solvent, and the drying method is known, for example, the electrolyte membrane obtained by perfusion is dried in a constant temperature dryer.

The embodiments of the present application have no special requirements on the drying temperature and drying time, for example, drying may be performed at 100° C. to 150° C. for 1 h to 10 h.

In a second aspect, this embodiment provides a solid-state lithium-ion battery, which includes a positive electrode, a negative electrode, and the sulfide solid-state electrolyte membrane prepared in the above-mentioned embodiment.

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

In one embodiment, the negative electrode can also include an electrolyte material, the type of electrolyte material is known in the art, and can be any one of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte or a polymer solid electrolyte. one or a combination of at least two.

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

In one embodiment, the negative electrode includes one or more negative electrode active materials that accept lithium, such as lithium titanium oxide (Li ₄ Ti ₅ O ₁₂ ), transition metals (such as Sn), metal oxides (such as V ₂ O ₅ ), tin oxide (SnO), titanium dioxide (TiO ₂ ), titanium niobium oxide (Ti _x Nb _y O _z , where 0≤x≤2, 0≤y≤24, 0≤z≤64), metal alloy ( For example, any one or a combination of at least two of copper-tin alloys (Cu ₆ Sn ₅ )) or metal sulfides (such as iron sulfide (FeS)).

In one embodiment, the negative active material in the negative electrode can be doped with one or more conductive materials that provide electron conduction paths and/or at least one polymeric binder material that improves the structural integrity of the negative electrode.

As an embodiment, the negative electrode active material can be doped with conductive materials such as: any one or a combination of at least two of carbon-based materials, powdered nickel, other metal particles or conductive polymers. Optionally, the carbon-based material may include, for example, at least one particle of carbon black, graphite, superP, acetylene black (such as KETCHENTM black or DENKATM black), carbon fiber, carbon nanotube, or graphene. Optionally, the conductive polymer may include at least one of polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene) polysulfonylstyrene, and the like.

As an embodiment, the negative active material can be doped with binders such as: poly(tetrafluoroethylene) (PTFE), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene Vinyl fluoride (PVDF), nitrile 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 negative electrode active materials, optional 0% to 60% of solid electrolytes, optional 0% to 15% of conductive materials, and optional 0% to 10% binder. It should be noted that "optional" means that the corresponding substance may or may not be included, and when the content is 0%, it means that the corresponding substance is not included.

As an embodiment, the positive electrode includes a positive electrode electroactive material layer, and the positive electrode electroactive material layer includes a lithium-based positive electrode electroactive material.

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

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

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

As an embodiment, the layered oxide cathode (eg, rock salt layered oxide cathode) comprises one or more lithium-based positive electrode electroactive materials selected from the group consisting of: LiCoO ₂ (LCO), LiNi _a Mn _b Co _{1 -ab} O ₂ (where 0≤a≤1, 0≤b≤1), LiNi _1-cd Co _c Al _d O ₂ (where 0≤c≤1 and 0≤d≤1), LiNi _e Mn _1-e Any one of O ₂ (where 0≤e≤1) or Li _1+f MO ₂ (where M is any one or a combination of at least two of Mn, Ni, Co or Al, 0≤f≤1) one or a combination of at least two.

As an embodiment, the spinel cathode comprises one or more lithium-based positive electrode electroactive materials selected from LiMn ₂ O ₄ (LMO) and LiNi _0.5 Mn _1.5 O ₄ .

As an embodiment, the olivine-type cathode comprises one or more lithium-based positive electrode electroactive materials LiMPO ₄ (where M is at least one of Fe, Ni, Co, and Mn).

As an embodiment, the polyanionic cathode comprises one or more lithium-based positive electrode electroactive materials: phosphates and/or silicates, phosphates such as _LiV2 ( _PO4 ) ₃ , silicates such as _LiFeSiO4 .

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

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

As an embodiment, one or more lithium-based cathode electroactive materials are coated by LiNbO ₃ and/or Al ₂ O ₃ .

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

As an embodiment, one or more lithium-based positive electrode electroactive materials can optionally be mixed with one or more conductive materials that provide electron conduction paths and/or at least one polymeric material that improves the structural integrity of the positive electrode. adhesive material.

As an embodiment, the positive electrode electroactive material layer may comprise 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 , in some embodiments, comprising 1% to 20% of binder.

As an embodiment, the lithium-based positive electrode electroactive material can optionally be mixed with the following binders: polytetrafluoroethylene (PTFE), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile 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 any one or a combination of at least two.

As an embodiment, the lithium-based positive electrode electroactive material can optionally be mixed with a conductive material that can include any one of carbon-based materials, powdered nickel, other metal particles, or conductive polymers or at least A combination of the two. The carbon-based material may include, for example, any one or a combination of at least two of carbon black, graphite, acetylene black (such as KETCHENTM black or DENKATM black), carbon fibers, carbon nanotubes, or graphene. The conductive polymer may include, for example, any one or a combination of at least two of polyaniline, polythiophene, polyacetylene or polypyrrole.

The positive current collector facilitates the flow of electrons between the positive electrode and the external circuit. The positive current collector may comprise metal such as metal foil, metal grid or metal mesh. For example, the positive electrode 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

1. Preparation of Li ₆ PS ₅ Cl:

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

The calcined Li ₆ PS ₅ Cl powder was passed through a 400-mesh sieve to obtain electrolyte powder particles with uniform particle size.

2. Preparation of P(VDF-TrFE) electrospun membrane

1.0gP (VDF-TrFE) polymer particle is slowly dissolved in the mixed solvent by 3ml dimethylformamide (DMF) and 2ml acetone, in the preparation raw material of P (VDF-TrFE) polymer particle, VDF:TrFE ( Molar ratio)=70%:30%, to obtain pure P(VDF-TrFE) precursor solution. The P(VDF-TrFE) precursor solution was electrospun under the conditions of an electric field strength of 1kV/cm and a flow rate of 1mL/h to prepare a P(VDF-TrFE) electrospun membrane. The SEM image is shown in Figure 2A. The mesh pore size D50 of P(VDF-TrFE) electrospun membrane is 10μm～18μm;

3. Preparation of Li ₆ PS ₅ Cl@P(VDF-TrFE) sulfide solid electrolyte membrane

The Li ₆ PS ₅ Cl particles obtained in Step 1 were dissolved in toluene (purity 99.9%), and mechanically stirred at 30° C. for 1 h to obtain a homogeneous Li ₆ PS ₅ Cl solution. Take two pieces of P(VDF-TrFE) electrospinning membranes, respectively pour Li ₆ PS ₅ Cl solution onto the two pieces of P(VDF-TrFE) electrospinning membranes, and control the thickness with a spatula;

The sulfide solid electrolyte membrane obtained by perfusion was dried in a constant temperature dryer at 120°C for 2 hours to remove excess solvent, and two composite solid electrolyte membranes were obtained. Then, the two composite solid electrolytes were stacked and hot-pressed at 200 °C and 10 MPa for 2 h. All operations are carried out in an argon atmosphere to obtain a sulfide solid electrolyte membrane.

The finally obtained sulfide solid electrolyte membrane had a thickness of 37 μm and an ion conductivity of 1.2 mS cm ⁻¹ .

FIG. 1 is a physical diagram of the sulfide solid electrolyte membrane prepared in Example 1.

FIG. 2A is an SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 1. FIG.

FIG. 4 is an SEM image of the solid electrolyte membrane prepared in Example 1.

FIG. 7 is the NMR spectrum of the Li ₆ PS ₅ Cl@P(VDF-TrFE) solid electrolyte membrane in Example 1.

Example 2

Compared with the preparation method of Example 1 in this example, in the preparation steps of P(VDF-TrFE) electrospun membrane, the quality of P(VDF-TrFE) polymer particles is 0.6g, and Fig. 2B is the prepared P( VDF-TrFE) electrospun membrane SEM figure, the grid aperture D50 of the obtained P (VDF-TrFE) electrospun membrane is 1 μm～5 μm, other is the same as embodiment 1.

The finally obtained sulfide solid electrolyte membrane had a thickness of 37 μm and an ion conductivity of 1.01×10 ⁻⁴ S/cm.

Example 3

Compared with the preparation method of Example 1 in this example, in the preparation steps of P(VDF-TrFE) electrospun membrane, the quality of P(VDF-TrFE) polymer particles is 0.8g, and Fig. 2C shows the prepared P( VDF-TrFE) SEM image of the electrospun membrane, the grid aperture D50 of the obtained P (VDF-TrFE) electrospun membrane is 5 μm～10 μm, and the others are the same as in Example 1.

The finally obtained sulfide solid electrolyte membrane had a thickness of 37 μm and an ion conductivity of 5.3×10 ⁻⁴ S/cm.

Example 4

Compared with the preparation method of Example 1 in this example, in the preparation step of P(VDF-TrFE) electrospun membrane, 0.6g of P(VDF-TrFE) polymer particles and 0.3g of bisfluorosulfonimide lithium salt (LiFSI) was slowly dissolved in a mixed solvent of 3ml dimethylformamide (DMF) and 2ml acetone, and the others were the same as in Example 1.

FIG. 3A is an SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 4. FIG.

The finally obtained P(VDF-TrFE) electrospun membrane has a certain orientation, and the perfusion of the oriented electrospun membrane is difficult.

Example 5

Compared with the preparation method of Example 1 in this example, in the preparation step of P(VDF-TrFE) electrospun membrane, 1.0g of P(VDF-TrFE) polymer particles and 0.3g of bisfluorosulfonimide lithium salt (LiFSI) was slowly dissolved in a mixed solvent of 3ml dimethylformamide (DMF) and 2ml acetone, and the others were the same as in Example 1.

FIG. 3B is an SEM image of the P(VDF-TrFE) electrospun membrane prepared in Example 5. FIG.

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

Example 6

The same electrospinning process as in Example 1 was used to prepare a PVDF membrane, and the others were the same as in Example 1.

The finally obtained Li ₆ PS ₅ Cl@PVDF solid electrolyte membrane has a thickness of 37 μm and an ion conductivity of 5×10 ^-4 S/cm.

Example 7

This embodiment provides a method for preparing a S@C||Li ₆ PS ₅ Cl@P(VDF-TrFE)||Li-In battery, including the following steps:

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

The synthesized S@C composite particles and Li ₆ PS ₅ Cl were stirred in a ball mill at a stirring speed of 300 rpm for 1 h at a mass ratio of 4:6, and the obtained product was prepared to form a positive electrode.

The above-mentioned positive electrode, Li-In negative electrode, and the Li ₆ PS ₅ Cl@P(VDF-TrFE) sulfide solid-state electrolyte membrane prepared in Example 1 were laminated to form an all-solid-state lithium-ion battery.

Example 8

This embodiment provides a Li ₆ PS ₅ Cl@C||Li ₆ PS ₅ Cl@P(VDF-TrFE)||Li-In battery preparation method, including the following steps:

Li ₆ PS ₅ Cl and multi-walled carbon nanotubes were mixed at a mass ratio of 7:3 and ball milled in a ball mill at a speed of 100 rpm for one hour, and the obtained product was prepared to form a positive electrode.

After 180 cycles of the battery, there is no obvious attenuation.

Example 9

This embodiment provides a method for preparing an NCM@LNO||Li ₆ PS ₅ Cl@P(VDF-TrFE)||Li-In battery, including the following steps:

Commercial NCM811 particles were heated at 90°C for twelve hours before use, LiOC ₂ H ₅ and Nb(OC ₂ H5) ₅ were dissolved in absolute ethanol, then NCM811 was added to the above solution and stirred for 3 h. The slurry was dried at 150 °C for 12 h, and heated at 400 °C for 1 h in an oxygen atmosphere to form LNO-coated NCM particles, and the obtained product was prepared to form a positive electrode.

After 1000 cycles, the battery has no obvious attenuation.

Example 10

Li ₂ S was used as the positive electrode active material, and the others were the same as in Example 7.

After 500 cycles of the battery cycle, there is no obvious attenuation.

Example 11

Adopt FeS ₂ as positive electrode active material, others are identical with embodiment 7.

After 500 cycles of the battery cycle, there is no obvious attenuation.

Comparative example 1

Compared with Example 7, the difference is that the P(VDF-TrFE) sulfide solid electrolyte membrane is replaced by a pure Li ₆ PS ₅ Cl sulfide solid electrolyte membrane.

Combining Figures 2A-2C and Examples 1-3 show that the thickness of the sulfide solid electrolyte membrane obtained by perfusing the P(VDF-TrFE) polymer membrane with sulfide solid electrolyte particles can reach below 40 μm. However, when the mesh pore size of the polymer membrane is too small, it is limited by the particle size of the sulfide solid electrolyte particles, which makes the infusion effect unsatisfactory, and it is difficult for larger sulfide particles to be completely poured into the spinning net, which makes the implementation The ionic conductivity of the sulfide solid electrolyte membrane prepared in Example 2-3 is low, and the ionic conductivity is significantly improved when the mesh pore size of the polymer membrane reaches 10 μm or more.

Combining Figure 3A and Figure 3B, after adding lithium salt, the anion and cation charges carried by the lithium salt itself will affect the electric field of the spinning machine during electrospinning, so that the grid of the polymer electrospinning membrane forms a directional arrangement; when The grid orientation of the polymer electrospun membrane weakened after decreasing the lithium salt concentration.

Combining Figure 1 and Figure 4, the thickness of the sulfide solid electrolyte membrane prepared in Example 1 reaches 37 μm, and the surface of the sulfide solid electrolyte membrane is evenly distributed, and the particles are evenly poured into the polymer membrane, and the particles cover the polymer membrane. whole.

Figure 6 is a comparison of the NMR spectra of the Li ₆ PS ₅ Cl@PVDF solid electrolyte membrane and the PVDF membrane in Example 6, and Figure 7 is the Li ₆ PS ₅ Cl@P(VDF-TrFE) solid electrolyte membrane and the PVDF membrane in Example 1 The NMR spectrum comparison chart of P(VDF-TrFE) membrane, comparing Figure 6 and Figure 7, it can be seen that the solid electrolyte membrane formed by pure PVDF and sulfide solid electrolyte is the same as the NMR spectrum of pure PVDF, which proves that pure PVDF and There is no interaction between the sulfide solid electrolytes; and the solid electrolyte membrane formed by P(VDF-TrFE) and sulfide solid electrolytes has a different peak shape than pure P(VDF-TrFE), which shows that the sulfide solid state The electrolyte membrane has a strong interaction with P(VDF-TrFE), not purely physical mixing.

Figure 5 is a cycle performance diagram of Example 7 and Comparative Example 1, wherein Li ₆ PS ₅ Cl@P(VDF-TrFe) corresponds to Example 7, Li ₆ PS ₅ Cl corresponds to Comparative Example 1, from Figure 5 and Example 7 Compared with Comparative Example 1, it can be seen that the capacity of the battery using the pure Li ₆ PS ₅ Cl sulfide solid electrolyte membrane declines faster, which is due to the fact that the too thick sulfide solid electrolyte membrane prolongs the ion conduction path, making the interface problem of the battery in the It's even worse during charging and discharging.

It can be seen from Examples 7-11 that the sulfide solid electrolyte membrane involved in this application has good performance in various batteries and has the advantage of being widely used.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present application, and the purpose is to enable those familiar with this technology to understand the content of the present application and implement it accordingly, and not to limit the protection scope of the present application. All equivalent changes or modifications made according to the spirit of the present application shall fall within the protection scope of the present application.

The applicant declares that the present application illustrates the detailed method of the present application through the above-mentioned examples, but the present application is not limited to the above-mentioned detailed method, that is, it does not mean that the application must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement to the present application, the equivalent replacement of each raw material of the product of the present application, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present application.

Claims

A sulfide solid-state electrolyte membrane, wherein the sulfide solid-state electrolyte membrane comprises a polymer membrane having a three-dimensional skeleton structure and a sulfide solid-state electrolyte material forming a continuous phase; the ionic conductivity of the sulfide solid-state electrolyte membrane is >10 -4 S/cm, the thickness of the sulfide solid electrolyte membrane is ≤40 μm;

The polymer film is a PVDF-based polymer film, the molecular structure is P (VDF-B), B is trifluoroethylene, and the mass fraction of structural units based on trifluoroethylene monomers in the polymer film is c, c ≤50%;

The polymer film is prepared by electrospinning, and the mesh holes of the polymer film have no orientation.
The sulfide solid electrolyte membrane according to claim 1, wherein the mesh pore diameter D50 of the polymer membrane is 10 μm˜18 μm.
The sulfide solid electrolyte membrane according to claim 1, wherein the sulfide solid electrolyte material comprises Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -MS x , Li 3.4 Si 0.4 P 0.6 S 4 , Li 10 GeP 2 S 11.7 O 0.3 , Li 9.6 P 3 S 12 , Li 7 P 3 S 11 , Li 9 P 3 S 9 O 3 , 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 )P 2 S 12 , Li(Ge 0.5 Sn 0.5 )P 2 S 12 , Li(Si 0.5 Sn 0.5 )PsS 12 , Li 10 GeP 2 S 12 , Li 6 PS 5 X, Li 7 P Any of 2 S 8 I, Li 10.35 Ge 1.35 P 1.65 S 12 , Li 3.25 Ge 0.25 P 0.75 S 4 , Li 10 SnP 2 S 12 , Li 10 SiP 2 S 12 or Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 One or a combination of at least two, wherein M is selected from any one of Si, Ge or Sn or a combination of at least two, and X is selected from any one of Cl, Br or I or a combination of at least two , 0≤x≤2.
The sulfide solid electrolyte membrane according to claim 3, wherein the sulfide solid electrolyte material is Li 6 PS 5 X, wherein X is Cl, Br or I.
The sulfide solid electrolyte membrane according to claim 3, wherein the sulfide solid electrolyte material forms a continuous phase in the polymer membrane by making a solution and pouring it onto the polymer membrane.
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.
A solid-state lithium-ion battery, comprising a positive electrode, a negative electrode and the sulfide solid-state electrolyte membrane according to any one of claims 1-6.