Solid electrolyte, sandwich structure solid electrolyte membrane, preparation method and application

Abstract

The invention provides a solid electrolyte, a sandwich structure solid electrolyte membrane and a preparation method and application, and relates to the technical field of solid batteries, the solid electrolyte provided by the invention has the advantages that Li ions are partially replaced by M ions, and the radius of the M ions is larger than that of Li, so that higher degree of freedom is provided for residual Li, and coordination of alkali metal in a migration process is facilitated. Cl is replaced by cluster ions, and the cluster ions provide more degrees of freedom, so that coordination of alkali metal in a migration process is facilitated, and relatively high ionic conductivity is achieved. A double-doping strategy of M and A generates a synergistic effect, so that not only is the mobility of a cationic sublattice optimized, but also a conduction channel of an anionic skeleton is widened, and the ionic conductivity is improved by one order of magnitude compared with that of a traditional sulfide electrolyte. In addition, the solid electrolyte has good structural stability and excellent processability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state batteries, in particular to a solid-state electrolyte, a sandwich structure solid-state electrolyte film and a preparation method and application thereof. BACKGROUND

[0002] All-solid-state lithium batteries are considered an important development direction for the next generation of energy storage devices due to their high safety and high energy density. Sulfide solid electrolytes have become a research hotspot in the field of all-solid-state batteries due to their high ionic conductivity and good interface contact performance.

[0003] The particle size distribution of sulfide electrolytes has a significant impact on the ionic conductivity after film formation. Different particle sizes of electrolyte particles may lead to non-uniformity of ion transport paths after film formation, thereby affecting the overall performance of the battery. These problems not only limit the further development of the wet film formation process of sulfide electrolytes, but also have a negative impact on the energy density, cycle life and safety of all-solid-state batteries.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] One of the purposes of the present application is to provide a solid-state electrolyte and a sandwich structure solid-state electrolyte film with a particle size distribution to at least solve one of the technical problems existing in the prior art.

[0006] In order to achieve the above-mentioned purposes of the present application, the following technical solutions are adopted: The present application provides a solid-state electrolyte, which belongs to a cubic crystal system and has the following chemical formula: Li 5.5-x-y M x PS 4.5-y Cl 1.5+y-z A z ; wherein 0 M is a cation with a valence of +1, and the radius of M is greater than that of Li; A is a cluster ion, and the radius of A is greater than that of Cl.

[0007] Further, the M includes one or more of Na, K, Rb and Cs; Preferably, the A is selected from BF4, BH4, AlF4 or AlH4.

[0008] The application further provides a preparation method of the solid electrolyte, comprising the following steps: weighing Li2S, M2S, LiCl, LiA and P2S5 raw materials according to stoichiometric ratios of a general formula, mixing with grinding balls under protection of an inert atmosphere, and then ball milling to obtain a mixture, compacting and calcining the mixture under protection of the inert atmosphere, and then cooling to obtain the solid electrolyte.

[0009] Further, the rotation speed of the ball milling is 200-600 rpm, and the time is 4-20 h. Preferably, the zirconium oxide balls are used as the ball milling medium, and the mass ratio of the raw materials to the zirconium oxide balls is 1:10-40. Preferably, the calcining temperature is 300-700 ℃, and the time is 4-25 h. Preferably, the heating rate of the calcining is 4-10 ℃ / min.

[0010] The application further provides application of the solid electrolyte or the solid electrolyte prepared by the preparation method in preparation of a solid electrolyte film.

[0011] The application further provides a sandwich structure solid electrolyte film, comprising a core layer and interface layers arranged on both sides of the core layer; the particle size of the solid electrolyte in the core layer is larger than the particle size of the solid electrolyte in the interface layers. The solid electrolyte is the solid electrolyte or the solid electrolyte prepared by the preparation method.

[0012] Further, the particle size of the solid electrolyte in the core layer is 0.9-4 um, and the particle size of the solid electrolyte in the interface layers is 0.4-1.7 um. Preferably, the particle size ratio of the solid electrolyte in the core layer to the solid electrolyte in the interface layers is 0.414.

[0013] The application further provides a preparation method of the sandwich structure solid electrolyte film, comprising the following steps: 1) separately preparing powder of solid electrolyte with large particle size and small particle size; 2) mixing the powder of solid electrolyte with large particle size and small particle size with a binder respectively, and heating to a melting temperature of the binder to obtain a large particle size mixture and a small particle size mixture; 3) hot-pressing the large particle size mixture and the small particle size mixture in a mold respectively to obtain a large particle size film and a small particle size film; 4) laminating the large particle size film as a core layer and the small particle size film as an interface layer, and repeating hot-pressing to obtain the sandwich structure solid electrolyte film.

[0014] Further, the binder comprises polyamide or polyethylene. Preferably, the binder is added in an amount of 5% to 20% of the mass of the powder; Preferably, the temperature of the hot-pressing is 80 to 150 DEG C, and the pressure is 10 to 100 mega-pascal.

[0015] In addition, the application also provides a full solid-state battery, comprising the solid-state electrolyte, the solid-state electrolyte prepared by the preparation method, the sandwich structure solid-state electrolyte film or the sandwich structure solid-state electrolyte film prepared by the preparation method.

[0016] Compared with the prior art, the application has the following beneficial effects: The solid-state electrolyte provided by the application has the chemical formula Li 5.5-X M X PS 4.5 Cl 1.5-y A y The M ion partially replaces the Li ion, and because the M ion has a larger radius than Li, it provides higher freedom for the remaining Li, which helps the coordination of alkali metals during migration. The cluster ion replaces Cl, and because the cluster ion provides more freedom, it helps the coordination of alkali metals during migration, and has high ionic conductivity. The double-doping strategy of M and A produces a synergistic effect, which not only optimizes the mobility of the cation sublattice, but also widens the conduction channel of the anion skeleton, so that the ionic conductivity is improved by an order of magnitude compared with traditional sulfide electrolytes. In addition, the solid-state electrolyte also has good structural stability and excellent processing performance.

[0017] The sandwich structure solid-state electrolyte film provided by the application has a unique particle size gradient design, and the large particles construct the core layer, the small particles fill the gaps, and a dense interface layer is formed, which optimizes the denseness of the film layer, forms a continuous ion transmission channel, and effectively improves the conductivity of the solid-state electrolyte film to more than 2 ms / cm. DETAILED DESCRIPTION

[0018] Unless otherwise defined herein, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. Clear dictates that the meaning and scope of the terms should be clear; however, in the event of any potential ambiguities, the definitions provided herein prevail over any dictionary or extrinsic definition. In this application, unless indicated otherwise, the use of "or" means "and / or". In addition, the use of the term "comprising" and other forms is non-limiting.

[0019] Generally, the nomenclature used in connection with, and the techniques of, cell and tissue culture, molecular biology, immunology, microbiology, genetics and protein and nucleic acid chemistry and hybridization described herein are those well-known and commonly used in the art. The methods and techniques of the present application are generally performed according to conventional methods in the art, unless otherwise indicated, and such methods and techniques are explained fully in the literature in the field. Enzymatic reactions and purification techniques are performed according to manufacturer's specifications, as commonly accomplished in the art or as described herein. The nomenclature used in connection with, and the techniques of, analytical chemistry, synthetic organic chemistry, and medicinal and pharmaceutical chemistry described herein are those well-known and commonly used in the art.

[0020] The technical solutions of the present application will be described clearly and completely below in connection with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0021] According to one aspect of the present application, a solid-state electrolyte is provided, the solid-state electrolyte belongs to cubic system, and has the following chemical formula: Li 5.5-x-y M x PS 4.5-y Cl 1.5+y-z A z ; wherein, 0

[0022] M is a cation with a valence of +1, and the radius of M is greater than Li; A is a cluster ion, and the radius of A is greater than Cl.

[0023] Further, the M includes one or more of Na, K, Rb, Cs; Preferably, the A is selected from BF4, BH4, AlF4 or AlH4.

[0024] The present application provides a chemical formula of Li 5.5-x-y M x PS 4.5-y Cl 1.5+y-z A zThe solid electrolyte of the application is partially substituted by M ions instead of Li ions, and the M ions have a larger radius than Li ions, which provides more freedom for the remaining Li ions and helps the coordination of alkali metal ions during migration. The cluster ions are substituted for Cl ions, which provide more freedom and help the coordination of alkali metal ions during migration, and have a high ionic conductivity. The double-doping strategy of M and A produces a synergistic effect, which not only optimizes the mobility of the cation sublattice but also widens the conduction channel of the anion skeleton, so that the ionic conductivity is improved by an order of magnitude compared with traditional sulfide electrolytes. In addition, the solid electrolyte also has good structural stability and excellent processing performance.

[0025] In some preferred embodiments, the M includes one or more of Na, K, Rb, and Cs. The A is selected from BF4, BH4, AlF4, or AlH4.

[0026] When M is Na and A is BH4, Na partially substitutes for Li and BH4 partially substitutes for Cl. Since Na and BH4 are larger than the corresponding original Li and Cl, this co-doping method greatly improves the ionic conductivity. When the chemical formula of the sulfide solid electrolyte is Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 The ionic conductivity of the electrolyte at room temperature reaches 17.2 ms*cm -1 , which is an order of magnitude higher than that without the introduction of ions. Moreover, the sodium ion substitution in the present embodiment can change the crystal structure and stability of the material: Na2S is used to replace part of Li2S to form different solid solutions and improve the structural stability of the material. At the same time, the material after sodium ion substitution also exhibits high capacity and good cycle stability.

[0027] According to a second aspect of the application, the application further provides a preparation method of the above-mentioned solid electrolyte, which comprises: weighing Li2S, M2S, LiCl, LiA and P2S5 raw materials according to the stoichiometric ratio of the general formula, mixing with grinding balls under the protection of an inert atmosphere, and then ball milling to obtain a mixture, and then compacting, calcining and cooling the mixture under the protection of an inert atmosphere to obtain the solid electrolyte.

[0028] The preparation method of the solid electrolyte of the application combines mechanical ball milling and high-temperature calcination, which is simple to operate and safe and efficient in the preparation process.

[0029] In some preferred embodiments, the rotation speed of the ball mill is 200-600 rpm, for example, but not limited to, 200 rpm, 300 rpm, 400 rpm, 500 rpm or 600 rpm; and the time is 4-20 h, for example, but not limited to, 4 h, 5 h, 8 h, 10 h, 12 h, 15 h, 18 h or 20 h.

[0030] In some preferred embodiments, the mass ratio of the raw material to the zirconium oxide ball is 1:10-40, for example, but not limited to, 1:10, 1:20, 1:30 or 1:40.

[0031] In some preferred embodiments, the calcination temperature is 300-700℃, for example, but not limited to, 300℃, 400℃, 500℃, 600℃ or 700℃, and the time is 4-25 h, for example, but not limited to, 4 h, 5 h, 8 h, 10 h, 12 h, 15 h, 20 h or 25 h. In the present application, the calcination can be performed by using a conventional muffle furnace sintering, and the muffle furnace is placed in an argon atmosphere.

[0032] In some preferred embodiments, the heating rate of the calcination is 4-10℃ / min, for example, but not limited to, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min. Slow heating can avoid thermal stress.

[0033] According to the second aspect of the present application, the present application also provides the use of the above-mentioned solid-state electrolyte or the solid-state electrolyte prepared by the above-mentioned preparation method in the preparation of a solid-state electrolyte film.

[0034] Based on the same inventive concept, the third aspect of the present application provides a sandwich structure solid-state electrolyte film, comprising a core layer and interface layers arranged on both sides of the core layer; the particle size of the solid-state electrolyte in the core layer is larger than the particle size of the solid-state electrolyte in the interface layers.

[0035] The sandwich structure solid-state electrolyte film provided by the present application realizes the synergistic optimization of mechanical strength, ionic conductivity, interface compatibility and safety by reasonably designing the material combination and layer sequence relationship of the intermediate dense layer and the two functional layers. Not only does it effectively solve the key technical problems of poor interface contact, lithium dendrite penetration and poor cycle stability of traditional solid-state electrolytes, but also has good processability and industrialization prospects. It is of great significance for the development of high-safety, long-life and high-energy-density all-solid-state batteries.

[0036] In some preferred embodiments, the particle size of the solid-state electrolyte in the core layer is 0.9-4 um, for example, but not limited to 0.9 um, 1 um, 2 um, 3 um or 4 um; the particle size of the solid-state electrolyte in the interface layer is 0.4-1.7 um, for example, but not limited to 0.4 um, 0.5 um, 0.8 um, 1 um, 1.2 um, 1.5 um or 1.7 um. The particle size ratio of the solid-state electrolyte in the core layer to the particle size of the solid-state electrolyte in the interface layer is 0.414. Under the above conditions, high ionic conductivity can be ensured while the positive and negative electrodes are well combined. It can be understood that the thickness of the core layer and the interface layer can be adjusted as needed without affecting the effect.

[0037] The fourth aspect of the present application provides a preparation method of the sandwich structure solid-state electrolyte film as described above, comprising the following steps: 1) separately preparing powder of solid-state electrolyte with large particle size and small particle size; 2) mixing the powder of solid-state electrolyte with large particle size and small particle size with a binder respectively and heating to the melting temperature of the binder to obtain a large particle size mixture and a small particle size mixture; 3) hot pressing the large particle size mixture and the small particle size mixture in a mold respectively to obtain a large particle size film and a small particle size film; 4) laminating the large particle size film as the core layer and the small particle size film as the interface layer and repeating hot pressing to obtain the sandwich structure solid-state electrolyte film.

[0038] The preparation method of the sandwich structure solid-state electrolyte film provided by the present application realizes the functional differentiation design of the core layer and the interface layer by separately selecting the powder of solid-state electrolyte with large particle size and small particle size, and combining the step-by-step mixing, melting and bonding and layering hot pressing process. This method does not require organic solvents, is green and environmentally friendly, has strong process controllability, and the obtained sandwich film has complete structure, firm interlayer bonding, excellent ion conduction performance, interface stability and mechanical safety, and is particularly suitable for large-scale manufacturing of high-energy density all-solid-state lithium batteries.

[0039] In some preferred embodiments, the binder comprises polyamide or polyethylene. The addition amount of the binder is 5%-20% of the mass of the powder, for example, but not limited to 5%, 10%, 15% or 20%.

[0040] In some preferred embodiments, the temperature of the hot pressing is 80-150℃, for example, but not limited to 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃, and the pressure is 10-100 MPa, for example, but not limited to 10 MPa, 20 MPa, 50 MPa, 80 MPa or 100 MPa.

[0041] In addition, the application further provides a solid-state battery comprising the solid-state electrolyte, the solid-state electrolyte prepared by the preparation method, the sandwich structure solid-state electrolyte film or the sandwich structure solid-state electrolyte film prepared by the preparation method.

[0042] The solid-state battery prepared by using the solid-state electrolyte material provided by the application can improve the electrical properties such as ion conductivity and charge-discharge cycle performance of the corresponding solid-state battery.

[0043] The application will be further described by examples. Unless otherwise specified, the materials in the examples are prepared according to the existing method or directly purchased from the market.

[0044] The example of the application provides a solid-state electrolyte, the chemical formula of which is Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0045] Specifically, the preparation method of the solid-state electrolyte comprises the following steps: S1, Li2S, Na2S, LiCl, LiBH4 and P2S5 are weighed according to the molar ratio of the chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank under an argon atmosphere; wherein the ball milling conditions are: zirconia balls are used as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, the ball-milled mixture is compacted in a square crucible under an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 500°C for 12 h under an argon atmosphere, and then cooled to obtain Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0046] S4, the cooled sample is ground by a planetary mill to obtain powders with D50=0.8 um and D50=1.93 um, respectively; S5, the two kinds of particle size powders are mixed with a polyamide binder (10%) respectively, mechanically mixed under a dry inert atmosphere, and then heated to the melting temperature of the binder (100°C); S6, the mixture is placed in a mold and hot-pressed at a temperature of 100°C and a pressure of 50 MPa; S7, the two kinds of different specification films after hot-pressing are stacked according to small-large-small, and the hot-pressing process is repeated to obtain a sandwich structure solid-state electrolyte film.

[0047] The embodiment of the application provides a solid-state electrolyte, which has a chemical formula of Li 5.2 Na 0.3 PS 4.5 Cl 1.2 (BH4) 0.3 .

[0048] Specifically, the preparation method of the solid-state electrolyte comprises the following steps: S1, Li2S, Na2S, LiCl, LiBH4 and P2S5 are weighed according to a molar ratio of a chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank under an argon atmosphere; wherein the ball milling conditions are as follows: zirconia balls are used as a ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:20, the rotation speed is 300 rpm during ball milling, and the ball milling time is 10 h; S3, the mixture after ball milling is compacted in a square crucible under an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 450 DEG C for 16 h under an argon atmosphere, and the Li 5.2 Na 0.3 PS 4.5 Cl 1.2 (BH4) 0.3 .

[0049] S4, the sample after cooling is ground by a planetary mill to obtain powders with D50=0.8 um and D50=1.93 um respectively; S5, two kinds of particle size powders are respectively mixed with a polyethylene binder (10%), and then mechanically mixed under a dry inert atmosphere, and then heated to a binder melting temperature (100 DEG C); S6, the mixture is placed in a mold and hot-pressed at a temperature of 100 DEG C and a pressure (50 MPa); S7, two kinds of different specification films after hot-pressing are stacked according to small-large-small, and the hot-pressing process is repeated to obtain a sandwich structure solid-state electrolyte film.

[0050] The embodiment of the application provides a solid-state electrolyte, which has a chemical formula of Li 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0051] Specifically, the preparation method of the solid-state electrolyte comprises the following steps: S1, Li2S, Na2S, LiCl, LiBH4 and P2S5 are weighed according to a molar ratio of a chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, ball milling the mixture in a ball milling tank under an argon atmosphere; wherein the ball milling conditions are: using zirconium oxide balls as the ball milling medium, the mass ratio of the mixture to the zirconium oxide balls is 1:25, the rotating speed during ball milling is 400 rpm, and the ball milling time is 8 h; S3, placing the ball-milled mixture in a square crucible under an argon atmosphere, compacting the mixture in the square crucible, and then placing the compacted crucible in a muffle furnace, sintering the mixture at 350°C under an argon atmosphere for 25 h, and obtaining Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0052] S4, grinding and crushing the cooled sample by a planetary mill to obtain powders with D50 = 1.7 um and D50 = 4.0 um, respectively; S5, mixing the powders with a polyamide binder (10%) respectively, mechanically mixing the mixture in a dry inert atmosphere, and then heating to the melting temperature of the binder (100°C); S6, placing the mixture in a mold, and hot-pressing the mixture at a temperature of 100°C and a pressure of 50 MPa; S7, stacking the two kinds of different specification films according to small-large-small, and repeating the hot-pressing process to obtain a sandwich structure solid-state electrolyte film.

[0053] In an embodiment of the present application, a solid-state electrolyte is provided, which has a chemical formula of Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0054] Specifically, the preparation method of the solid-state electrolyte includes the following steps: S1, taking Li2S, Na2S, LiCl, LiBH4, and P2S5 according to the molar ratio of the chemical formula, and mixing them uniformly under an argon atmosphere to obtain a mixture; S2, ball milling the mixture in a ball milling tank under an argon atmosphere; wherein the ball milling conditions are: using zirconium oxide balls as the ball milling medium, the mass ratio of the mixture to the zirconium oxide balls is 1:32, the rotating speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, placing the ball-milled mixture in a square crucible under an argon atmosphere, compacting the mixture in the square crucible, and then placing the compacted crucible in a muffle furnace, sintering the mixture at 500°C under an argon atmosphere for 12 h, and obtaining Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0055] S4, grinding and crushing the cooled sample by a planetary mill to obtain powders with D50 = 0.4 um and D50 = 0.96 um, respectively; S5, mixing the two kinds of particle size powders with polyamide binder (14%) respectively, mechanically mixing under dry inert atmosphere, and then heating to the binder melting temperature (120℃); S6, placing the mixture in a mold, hot pressing at a temperature of 120℃ and a pressure of 30 MPa; S7, stacking the two kinds of different specification films after hot pressing according to small-large-small, repeating the hot pressing process to obtain a sandwich structure solid electrolyte film.

[0056] The solid electrolyte provided by the embodiment of the present application has a chemical formula of Li5K 0.5 PS 4.5 Cl1(BF4) 0.5 .

[0057] Specifically, the preparation method of the solid electrolyte includes the following steps: S1, taking Li2S, K2S, LiCl, LiBH4 and P2S5 according to the molar ratio of the chemical formula, and mixing uniformly under an argon atmosphere to obtain a mixture; S2, ball milling the mixture in a ball milling tank under an argon atmosphere; wherein the ball milling conditions are: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, placing the ball-milled mixture in a square crucible under an argon atmosphere, compacting, and then placing the compacted crucible into a muffle furnace, sintering at 500℃ under an argon atmosphere for 12 h, and cooling to obtain Li5K 0.5 PS 4.5 Cl1(BF4) 0.5 .

[0058] S4, grinding and crushing the cooled sample through a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5, mixing the two kinds of particle size powders with polyamide binder (10%) respectively, mechanically mixing under dry inert atmosphere, and then heating to the binder melting temperature (100℃); S6, placing the mixture in a mold, hot pressing at a temperature of 100℃ and a pressure of 80 MPa; S7, stacking the two kinds of different specification films after hot pressing according to small-large-small, repeating the hot pressing process to obtain a sandwich structure solid electrolyte film.

[0059] The solid electrolyte provided by the embodiment of the present application has a chemical formula of Li5Rb 0.5 PS 4.5 Cl1(AlF4) 0.5 .

[0060] Specifically, the preparation method of the solid-state electrolyte includes the following steps: S1, Li2S, Rb2S, LiCl, LiAlF4, and P2S5 are weighed according to the molar ratio of the chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank under an argon atmosphere; wherein the ball milling conditions are: zirconia balls are used as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, the ball-milled mixture is compacted in a square crucible under an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 500°C under an argon atmosphere for 12 h, and after cooling, Li5Rb 0.5 PS 4.5 Cl1(AlF4) 0.5 .

[0061] S4, the cooled sample is ground by a planetary mill to obtain powders with D50=0.8 um and D50=1.93 um, respectively; S5, the two kinds of particle size powders are mixed with a polyamide binder (16%) respectively, and are mechanically mixed under a dry inert atmosphere, and then are heated to the melting temperature of the binder (80°C); S6, the mixture is placed in a mold and hot-pressed at a temperature of 80°C and a pressure of 90 MPa; S7, the two kinds of different specification films after hot-pressing are stacked according to small-large-small, and the hot-pressing process is repeated to obtain a sandwich structure solid-state electrolyte film.

[0062] Embodiment 7 provides a solid-state electrolyte with a chemical formula of Li5Cs 0.5 PS 4.5 Cl1(AlH4) 0.5 .

[0063] Specifically, the preparation method of the solid-state electrolyte includes the following steps: S1, Li2S, Cs2S, LiCl, LiAlH4, and P2S5 are weighed according to the molar ratio of the chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank under an argon atmosphere; wherein the ball milling conditions are: zirconia balls are used as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, the ball-milled mixture is compacted in a square crucible under an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 500°C under an argon atmosphere for 12 h, and after cooling, Li5Cs 0.5 PS 4.5Cl1(AlH4) 0.5 .

[0064] S4, the cooled sample is ground by a planetary mill to obtain powders with D50=0.8um and D50=1.93um, respectively; S5, the two kinds of particle size powders are mixed with polyamide (polyethylene) binder (10%) respectively, mechanically mixed in a dry inert atmosphere, and then heated to the melting temperature of the binder (100℃); S6, the mixture is placed in a mold and hot pressed at a temperature of 100℃ and a pressure of 60 MPa; S7, the two kinds of different specification film pieces after hot pressing are stacked according to small-large-small, and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte film.

[0065] The solid electrolyte provided by the embodiment of the present application has a chemical formula of Li5Na 0.5 PS 4.5 Cl1(AlH4) 0.5 .

[0066] Specifically, the preparation method of the solid electrolyte includes the following steps: S1, Li2S, Na2S, LiCl, LiAlH4, and P2S5 are weighed according to the molar ratio of the chemical formula and mixed uniformly in an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank in an argon atmosphere; wherein the ball milling conditions are: zirconia balls are used as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10h; S3, the ball milled mixture is compacted in a square crucible in an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 500℃ for 12h in an argon atmosphere, and then cooled to obtain Li5Na 0.5 PS 4.5 Cl1(AlH4) 0.5 .

[0067] S4, the cooled sample is ground by a planetary mill to obtain powders with D50=0.8um and D50=1.93um, respectively; S5, the two kinds of particle size powders are mixed with polyamide (polyethylene) binder (10%) respectively, mechanically mixed in a dry inert atmosphere, and then heated to the melting temperature of the binder (100℃); S6, the mixture is placed in a mold and hot pressed at a temperature of 100℃ and a pressure of 50 MPa; S7, the two kinds of different specification film pieces after hot pressing are stacked according to small-large-small, and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte film.

[0068] The embodiment of the present application provides a solid-state electrolyte, which has a chemical formula of Li5Rb 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0069] Specifically, the preparation method of the solid-state electrolyte comprises the following steps: S1, Li2S, Rb2S, LiCl, LiBH4 and P2S5 are weighed according to the molar ratio of the chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank under an argon atmosphere; wherein the ball milling conditions are as follows: zirconia balls are used as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed is 300 rpm during ball milling, and the ball milling time is 10 h; S3, the mixture after ball milling is compacted in a square crucible under an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 500 DEG C for 12 h under an argon atmosphere, and the Li5Rb 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0070] S4, the cooled sample is ground by a planetary mill to obtain powders with D50=0.8 um and D50=1.93 um respectively; S5, the powders with two particle sizes are mixed with a polyamide binder (10%) respectively, and are mechanically mixed under a dry inert atmosphere, and then are heated to the melting temperature (100 DEG C) of the binder; S6, the mixture is placed in a mold and is hot-pressed at 100 DEG C and a pressure (50 MPa); S7, the two kinds of different specification films after hot-pressing are stacked according to small-large-small, and the hot-pressing process is repeated to obtain a sandwich structure solid-state electrolyte film.

[0071] The comparative example of the present application provides a solid-state electrolyte, which has a chemical formula of Li5Na 0.5 PS 4.5 Cl 1.5 .

[0072] Specifically, the preparation method of the solid-state electrolyte comprises the following steps: S1, Li2S, Na2S, LiCl and P2S5 are weighed according to the molar ratio of the chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, ball milling the mixture in a ball milling tank under an argon atmosphere; wherein the ball milling conditions are: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, placing the ball-milled mixture in a square crucible under an argon atmosphere, compacting the mixture in the square crucible, and then placing the compacted crucible in a muffle furnace, sintering the mixture at 500°C under an argon atmosphere for 12 h, and obtaining Li5Na 0.5 PS 4.5 Cl 1.5 .

[0073] S4, grinding and crushing the cooled sample by a planetary mill to obtain powders with D50 = 0.8 um and D50 = 1.93 um, respectively; S5, mixing the two kinds of powders with a polyamide binder (10%) respectively, mechanically mixing the mixture in a dry inert atmosphere, and then heating to the melting temperature of the binder (100°C); S6, placing the mixture in a mold, and hot-pressing the mixture at a temperature of 100°C and a pressure of 50 MPa; S7, stacking the two kinds of hot-pressed films according to the order of small-large-small, and repeating the hot-pressing process to obtain a sandwich-structured solid-state electrolyte film.

[0074] The comparative example 2 provides a solid-state electrolyte with a chemical formula of Li 5.5 PS 4.5 Cl1(BH4) 0.5 .

[0075] Specifically, the preparation method of the solid-state electrolyte includes the following steps: S1, taking Li2S, LiCl, LiBH4, and P2S5 according to the molar ratio of the chemical formula, and mixing the materials uniformly under an argon atmosphere to obtain a mixture; S2, ball milling the mixture in a ball milling tank under an argon atmosphere; wherein the ball milling conditions are: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, placing the ball-milled mixture in a square crucible under an argon atmosphere, compacting the mixture in the square crucible, and then placing the compacted crucible in a muffle furnace, sintering the mixture at 500°C under an argon atmosphere for 12 h, and obtaining Li 5.5 PS 4.5 Cl1(BH4) 0.5 .

[0076] S4, grinding and crushing the cooled sample by a planetary mill to obtain powders with D50 = 0.8 um and D50 = 1.93 um, respectively; S5, the two kinds of particle size powder are mixed with polyamide binder (10%) respectively, mechanically mixed under dry inert atmosphere, and then heated to the melting temperature of the binder (100°C); S6, the mixture is placed in a mold and hot-pressed at a temperature of 100°C and a pressure of 50 MPa; S7, the two different specification films after hot-pressing are stacked according to small-large-small, and the hot-pressing process is repeated to obtain a sandwich structure solid electrolyte film.

[0077] The comparative example 3 provides a solid electrolyte with a chemical formula of Li 5.5 PS 4.5 Cl 1.5 .

[0078] Specifically, the preparation method of the solid electrolyte includes the following steps: S1, Li2S, LiCl, and P2S5 are weighed according to the molar ratio of the chemical formula and mixed uniformly under an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank under an argon atmosphere; wherein the ball milling conditions are: zirconia balls are used as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, the ball-milled mixture is placed in a square crucible and compacted under an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 500°C for 12 h under an argon atmosphere, and after cooling, Li 5.5 PS 4.5 Cl 1.5 .

[0079] S4, the cooled sample is ground and broken by a planetary mill to obtain powders with D50=0.8 um and D50=1.93 um, respectively; S5, the two kinds of particle size powder are mixed with polyamide (polyethylene) binder (10%) respectively, mechanically mixed under dry inert atmosphere, and then heated to the melting temperature of the binder (100°C); S6, the mixture is placed in a mold and hot-pressed at a temperature of 100°C and a pressure of 50 MPa; S7, the two different specification films after hot-pressing are stacked according to small-large-small, and the hot-pressing process is repeated to obtain a sandwich structure solid electrolyte film.

[0080] The comparative example 4 provides a solid electrolyte with a chemical formula of Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0081] Specifically, the preparation method of the solid-state electrolyte comprises the following steps: S1, Li2S, Na2S, LiCl, LiBH4, and P2S5 are weighed according to the molar ratio of the chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank under an argon atmosphere; wherein the ball milling conditions are: zirconia balls are used as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, the ball-milled mixture is compacted in a square crucible under an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 500 DEG C under an argon atmosphere for 12 h, and after cooling, Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0082] S4, the cooled sample is ground by a planetary mill to obtain powders with D50=0.3 um and D50=0.72 um, respectively; S5, the two kinds of particle size powders are mixed with polyamide (polyethylene) binder (10%) respectively, mechanically mixed under a dry inert atmosphere, and then heated to the melting temperature of the binder (100 DEG C); S6, the mixture is placed in a mold and hot-pressed at a temperature of 100 DEG C and a pressure of 50 MPa; S7, the two kinds of different specification films after hot pressing are stacked according to small-large-small, and the hot pressing process is repeated to obtain a sandwich structure solid-state electrolyte film.

[0083] The present application provides a solid-state electrolyte with a chemical formula of Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0084] Specifically, the preparation method of the sulfide solid-state electrolyte comprises the following steps: S1, Li2S, Na2S, LiCl, LiBH4, and P2S5 are weighed according to the molar ratio of the chemical formula and are uniformly mixed under an argon atmosphere to obtain a mixture; S2, the mixture is ball milled in a ball mill tank under an argon atmosphere; wherein the ball milling conditions are: zirconia balls are used as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the rotation speed during ball milling is 300 rpm, and the ball milling time is 10 h; S3, the ball-milled mixture is compacted in a square crucible under an argon atmosphere, and then the compacted crucible is placed in a muffle furnace and sintered at 500 DEG C under an argon atmosphere for 12 h, and after cooling, Li6 Li5Na 0.5 PS4.5 Cl1(BH4) 0.5 .

[0085] S4, grind the cooled sample through a planetary mill to obtain a powder with a D50 of 0.8 um; S5, mix the powder with a polyamide binder (10%), mechanically mix under a dry inert atmosphere, and then heat to the binder melting temperature (100°C); S6, place the mixture in a mold and hot-press at a temperature of 100°C and a pressure of 50 MPa; S7, stack the hot-pressed film according to three layers, and repeat the hot-pressing process to obtain a sandwich structure solid electrolyte film.

[0086] To verify the performance of the sandwich structure solid electrolyte film provided in the above examples and comparative examples, the following method is used: Post-burning ionic conductivity test method: Take a piece of the post-burning solid electrolyte provided in Examples 1-9 and Comparative Examples 1-5, gently grind it to a powder state in a mortar, weigh 0.11-0.14g of the powder, place it in a mold with a diameter of 10mm, area S=0.5*0.5*Π, pressure 10mpa, pressure for 10-15min, use Donghua electrochemical workstation to test impedance, get impedance data (R / Ω), then take out the piece, test thickness (H / cm), according to the formula ion conduct =H / S / R.

[0087] Film pressing ionic conductivity calculation method: Cut the sandwich structure solid electrolyte film provided in Examples 1-9 and Comparative Examples 1-5 into a 10mm diameter disc using a slicer, use Donghua electrochemical workstation to test impedance, test thickness (H / cm), according to the formula ion conduct =H / S / R.

[0088] The results are shown in the following table: Sample Name Post-burn Ionic Conductivity (mS / cm) Press-film Ionic Conductivity (mS / cm) Example 1 18.1 2.41 Example 2 16.9 2.13 Example 3 18.2 2.87 Example 4 18.0 2.08 Example 5 17.9 2.37 Example 6 17.6 2.33 Example 7 17.5 2.34 Example 8 18.3 2.40 Example 9 19.2 2.51 Comparative Example 1 14.3 1.72 Comparative Example 2 14.1 1.71 Comparative Example 3 11.9 1.45 Comparative Example 4 18.1 1.03 Comparative Example 5 18.3 1.21 From the above experimental results, it can be seen that: Comparison of Examples 1-9 and Comparative Example 1: Without adding BH4, it is not possible to achieve the ionic conductivity that can be achieved by co-doping; The reason is that the doping of Na alone is not enough to contribute to the freedom of Li elements.

[0089] Comparison of Examples 1-9 and Comparative Example 2: Without adding Na, it is not possible to achieve the ionic conductivity that can be achieved by co-doping; The reason is that the doping of BH4 alone is not enough to contribute to the freedom of Li elements.

[0090] Example 1-9 and Comparative Example 3: Without doping of two elements, the ion conductivity further decreases, because there is no element with large ionic radius to provide more freedom for Li migration.

[0091] Example 1-9 and Comparative Example 4: Too small particles will cause a serious decrease in ion conductivity, because the increase of interfacial area between particles hinders ion conduction; Example 1-9 and Comparative Example 5: According to the three-layer small particle size film pressing, the ion conductivity of the electrolyte membrane is small, because too small particles increase the interfacial area between particles, thereby causing a decrease in ion conductivity.

[0092] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solid electrolyte, characterized in that, The solid electrolyte belongs to the cubic crystal system and has the following chemical formula: Li 5.5-x-y M x PS 4.5-y Cl 1.5+y-z A z ; Where 0 < x ≤ 0.5, 0 ≤ y < 0.5, and 0 < z ≤ 0.5 M is a cation with a valence state of +1, and the radius of M is greater than that of Li; A is a cluster ion, and the radius of A is greater than that of Cl.

2. The solid electrolyte according to claim 1, characterized in that, The M includes one or more of Na, K, Rb, and Cs; Preferably, A is selected from BF4, BH4, AlF4, or AlH4.

3. The method for preparing the solid electrolyte according to claim 1 or 2, characterized in that, include: Li₂S, M₂S, LiCl, LiA, and P₂S₅ raw materials were weighed according to the stoichiometric ratio of the general formula, mixed with grinding balls under an inert atmosphere, and then ball-milled to obtain a mixture. The mixture was then compacted, calcined, and cooled under an inert atmosphere to obtain the solid electrolyte.

4. The preparation method according to claim 3, characterized in that, The ball mill operates at a speed of 200-600 rpm for 4-20 hours. Preferably, zirconia balls are used as the ball milling medium, and the mass ratio of raw material to zirconia balls is 1:10~40; Preferably, the calcination temperature is 300~700℃ and the time is 4~25h; Preferably, the heating rate of the calcination is 4~10℃ / min.

5. The application of the solid electrolyte according to claim 1 or 2 or the solid electrolyte prepared by the preparation method according to claim 3 or 4 in the preparation of solid electrolyte membranes.

6. A sandwich-structured solid electrolyte membrane, characterized in that, It includes a core layer and interface layers disposed on both sides of the core layer; the particle size of the solid electrolyte in the core layer is larger than the particle size of the solid electrolyte in the interface layer. The solid electrolyte is the solid electrolyte as described in claim 1 or 2, or a solid electrolyte prepared by the preparation method described in claim 3 or 4.

7. The sandwich-structured solid electrolyte membrane according to claim 6, characterized in that, The particle size of the solid electrolyte in the core layer is 0.9~4 μm; the particle size of the solid electrolyte in the interface layer is 0.4~1.7 μm. Preferably, the particle size ratio of the solid electrolyte in the core layer to the solid electrolyte in the interface layer is 0.

414.

8. The method for preparing the sandwich structure solid electrolyte membrane according to claim 6 or 7, characterized in that, Includes the following steps: 1) Prepare solid electrolyte powders with large and small particle sizes respectively; 2) Mix the large-particle-size and small-particle-size powders separately with the binder and heat to the binder's melting temperature to obtain a large-particle-size mixture and a small-particle-size mixture; 3) The large-particle-size mixture and the small-particle-size mixture are placed in a mold and hot-pressed to obtain a large-particle-size membrane and a small-particle-size membrane; 4) Stack large-diameter membranes as the core layer and small-diameter membranes as the interface layer, and repeatedly hot-press to obtain the sandwich structure solid electrolyte membrane.

9. The preparation method according to claim 8, characterized in that, The adhesive includes polyamide or polyethylene; Preferably, the amount of binder added is 5% to 20% of the powder mass; Preferably, the hot pressing temperature is 80~150℃ and the pressure is 10~100 MPa.

10. An all-solid-state battery, characterized in that, Includes the solid electrolyte as described in claim 1 or 2, the solid electrolyte prepared by the preparation method described in claim 3 or 4, the sandwich structure solid electrolyte membrane as described in claim 6 or 7, or the sandwich structure solid electrolyte membrane prepared by the preparation method described in claim 8 or 9.