Solid state electrolyte, sandwiched solid state electrolyte membrane, and methods of making and use

Abstract

The application provides a kind of solid electrolyte, sandwich structure solid electrolyte membrane and preparation method and application, it is related to solid battery technical field, the solid electrolyte provided by the present application, M ion partially replaces Li ion, because M ion radius is larger than Li, provide higher freedom for remaining Li, help the coordination of alkali metal in the migration process. By cluster ion substitution Cl, because cluster ion provides more freedom, helps the coordination of alkali metal in the migration process, has higher ionic conductivity. The synergistic effect of M and A double-doped strategy optimizes the mobility of cation sublattice, and widens the conduction channel of anion skeleton, so that the ionic conductivity is improved by an order of magnitude compared with traditional sulfide electrolyte. In addition, the solid electrolyte also has good structural stability and excellent processing performance.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a solid electrolyte, a sandwich-structured solid electrolyte membrane, its preparation method, and its application. Background Technology

[0002] All-solid-state lithium batteries are considered an important development direction for next-generation 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 interfacial contact performance.

[0003] The particle size distribution of sulfide electrolytes significantly affects the ionic conductivity after film formation. Electrolyte particles of different sizes may lead to inhomogeneities in ion transport paths after film formation, thus affecting the overall performance of the battery. These issues not only limit the further development of wet film formation technology for sulfide electrolytes but also negatively impact the energy density, cycle life, and safety of all-solid-state batteries.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] One of the objectives of this invention is to provide a solid electrolyte and a sandwich structure solid electrolyte membrane with particle size distribution, so as to at least solve one of the technical problems existing in the prior art.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: This invention provides a solid electrolyte, which 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.

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

[0008] The present invention also provides a method for preparing the above-mentioned solid electrolyte, comprising: weighing Li2S, M2S, LiCl, LiA and P2S5 raw materials according to the stoichiometric ratio of the general formula, mixing them with grinding balls under an inert atmosphere and then ball milling them to obtain a mixture, compacting the mixture under an inert atmosphere, calcining it and then cooling it to obtain the solid electrolyte.

[0009] Furthermore, the ball mill operates at a speed of 200-600 rpm for a time of 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.

[0010] The present invention also provides the application of the above-described solid electrolyte or the solid electrolyte prepared by the above-described preparation method in the preparation of solid electrolyte membranes.

[0011] The present invention also provides a sandwich structure solid electrolyte membrane, comprising a core layer and an interface layer disposed on both sides of the core layer; wherein 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 described above or a solid electrolyte prepared by the preparation method described above.

[0012] Furthermore, 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.

[0013] The present invention also provides a method for preparing the above-mentioned sandwich structure solid electrolyte membrane, comprising 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.

[0014] Furthermore, the adhesive comprises 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.

[0015] In addition, the present invention also provides an all-solid-state battery, including the solid electrolyte described above, the solid electrolyte prepared by the preparation method described above, the sandwich structure solid electrolyte membrane described above, or the sandwich structure solid electrolyte membrane prepared by the preparation method described above.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The chemical formula provided by this invention is Li 5.5-X M X PS 4.5 Cl 1.5-y A y In this solid-state electrolyte, M ions partially replace Li ions. Because M ions have a larger radius than Li, they provide greater degrees of freedom to the remaining Li, facilitating coordination of alkali metals during migration. Cl is replaced by cluster ions, which also provide more degrees of freedom, aiding in coordination of alkali metals during migration and resulting in higher ionic conductivity. The dual-doping strategy of M and A produces a synergistic effect, optimizing the mobility of the cation sublattice and broadening the conduction channels of the anion framework, thus increasing the ionic conductivity by an order of magnitude compared to traditional sulfide electrolytes. Furthermore, this also endows the solid-state electrolyte with good structural stability and excellent processing performance.

[0017] The sandwich structure solid electrolyte membrane provided by this invention, through the ingenious construction of a unique particle size gradient design, uses large particles to form the core layer, small particles to fill the gaps and form a dense interface layer, optimizes the membrane density, forms a continuous ion transport channel, and effectively improves the conductivity of the solid electrolyte membrane to greater than 2 ms / cm. Detailed Implementation

[0018] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0019] Generally, the nomenclature and techniques used in cell and tissue culture, molecular biology, immunology, microbiology, genetics, and protein and nucleic acid chemistry and hybridization, together with those described herein, are those well-known and commonly used in the art. Unless otherwise stated, the methods and techniques of the present invention are generally carried out according to conventional methods well-known in the art and described in various general and more specific references, which are cited and discussed throughout this specification. Enzymatic reactions and purification techniques are carried out according to the manufacturer's instructions, as commonly practiced in the art, or as described herein. The nomenclature, laboratory procedures, and techniques used in analytical chemistry, synthetic organic chemistry, and medical and medicinal chemistry, together with those described herein, are those well-known and commonly used in the art.

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] According to one aspect of the present invention, a solid electrolyte is provided, the solid electrolyte being of the cubic crystal system and having 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.

[0022] 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.

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

[0024] The chemical formula provided by this invention is Li 5.5-x-y M x PS 4.5-y Cl 1.5+y-z A zIn this solid-state electrolyte, M ions partially replace Li ions. Because M ions have a larger radius than Li, they provide greater freedom to the remaining Li, facilitating coordination of alkali metals during migration. Cl is replaced by cluster ions, which also provide greater freedom, aiding in coordination of alkali metals during migration and resulting in higher ionic conductivity. The dual-doping strategy of M and A produces a synergistic effect, optimizing the mobility of the cation sublattice and broadening the conduction channels of the anion framework, thus increasing the ionic conductivity by an order of magnitude compared to traditional sulfide electrolytes. Furthermore, this also endows the solid-state electrolyte with good structural stability and excellent processing performance.

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

[0026] When M is Na and A is BH4, Na partially replaces Li and BH4 partially replaces Cl. Since both Na and BH4 are larger than their respective original Li and Cl values, this co-doping method greatly improves the ionic conductivity. Specifically, when the chemical formula of the sulfide solid electrolyte is Li5Na... 0.5 PS 4.5 Cl1(BH4) 0.5 The electrolyte exhibits an ionic conductivity of 17.2 mS / cm at room temperature. -1 The conductivity is an order of magnitude higher than that without sodium ions. Furthermore, the sodium ion substitution in this embodiment alters the crystal structure and stability of the material: replacing some Li₂S with Na₂S forms different solid solutions, improving the material's structural stability. Simultaneously, the sodium-substituted material also exhibits higher capacity and better cycling stability.

[0027] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-mentioned solid electrolyte, comprising: weighing Li2S, M2S, LiCl, LiA and P2S5 raw materials according to the stoichiometric ratio of the general formula, mixing them with grinding balls under an inert atmosphere and then ball milling them to obtain a mixture, compacting the mixture under an inert atmosphere, calcining it and then cooling it to obtain the solid electrolyte.

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

[0029] In some preferred embodiments, the rotational 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; the time is 4~20h, for example, but not limited to 4 h, 5h, 8 h, 10 h, 12 h, 15 h, 18 h or 20 h.

[0030] In some preferred embodiments, zirconia balls are used as the ball milling medium, and the mass ratio of raw material to zirconia balls is 1:10 to 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 4~25h, for example, but not limited to 4h, 5h, 8h, 10h, 12h, 15h, 20h or 25h. In this application, calcination can be carried out using a conventional muffle furnace sintering, with the muffle furnace placed in an argon atmosphere.

[0032] In some preferred embodiments, the calcination heating rate 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 avoids thermal stress.

[0033] According to a second aspect of the present invention, the present invention also provides the application of the above-described solid electrolyte or the solid electrolyte prepared by the above-described preparation method in the preparation of solid electrolyte membranes.

[0034] Based on the same inventive concept, a third aspect of the present invention provides a sandwich structure solid electrolyte membrane, including a core layer and an interface layer disposed on both sides of the core layer; wherein 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.

[0035] The sandwich-structured solid electrolyte membrane provided in this solution achieves synergistic optimization of mechanical strength, ionic conductivity, interfacial compatibility, and safety through a rational design of the material combination and layer sequence relationship between the middle dense layer and the functional layers on both sides. It not only effectively solves key technical problems of traditional solid electrolytes such as poor interfacial contact, lithium dendrite penetration, and poor cycle stability, but also possesses good processability and industrialization prospects, which 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 electrolyte in the core layer is 0.9~4 μm, for example, but not limited to 0.9 μm, 1 μm, 2 μm, 3 μm or 4 μm; the particle size of the solid electrolyte in the interface layer is 0.4~1.7 μm, for example, but not limited to 0.4 μm, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm or 1.7 μm. The diameter ratio of the solid electrolyte particle size in the core layer to that in the interface layer is 0.414. Under the above conditions, high ionic conductivity and good bonding with both positive and negative electrodes can be ensured. It is understood that the thickness of the core layer and the interface layer can be adjusted as needed without affecting their effectiveness.

[0037] A fourth aspect of the present invention provides a method for preparing the above-described sandwich structure solid electrolyte membrane, comprising 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.

[0038] The method for preparing a sandwich-structured solid electrolyte membrane provided by this invention achieves functional differentiation between the core layer and the interface layer by selecting solid electrolyte powders with large and small particle sizes respectively, and combining stepwise mixing, melt bonding, and layered hot pressing processes. This method requires no organic solvents, is environmentally friendly, and offers strong process controllability. The resulting sandwich membrane has a complete structure, strong interlayer bonding, and excellent ion conductivity, interfacial stability, and mechanical safety, making it particularly suitable for the large-scale manufacturing of high-energy-density all-solid-state lithium batteries.

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

[0040] In some preferred embodiments, the hot pressing temperature is 80~150°C, for example, but not limited to 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, 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 present invention also provides an all-solid-state battery, including the solid electrolyte described above, the solid electrolyte prepared by the preparation method described above, the sandwich structure solid electrolyte membrane described above, or the sandwich structure solid electrolyte membrane prepared by the preparation method described above.

[0042] Using the solid electrolyte material provided by this invention to prepare all-solid-state batteries can improve the electrical properties of the corresponding all-solid-state batteries, such as ionic conductivity and charge-discharge cycle performance.

[0043] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0044] Example 1 This application provides a solid electrolyte with the chemical formula Li5Na. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0045] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Na2S, LiCl, LiBH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5Na was obtained. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0046] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0047] Example 2 This application provides a solid electrolyte with the chemical formula Li 5.2 Na 0.3 PS 4.5 Cl 1.2 (BH4) 0.3 .

[0048] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Na2S, LiCl, LiBH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:20, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 450°C for 16 hours under an argon atmosphere. After cooling, Li was obtained. 5.2 Na 0.3 PS 4.5 Cl 1.2 (BH4) 0.3 .

[0049] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyethylene binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0050] Example 3 This application provides a solid electrolyte with the chemical formula Li5Na. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0051] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Na2S, LiCl, LiBH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball mill jar 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 1:25, the ball milling speed is 400 rpm, and the ball milling time is 8 hours. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 350°C for 25 hours under an argon atmosphere. After cooling, Li5Na was obtained. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0052] S4. The cooled sample is ground and crushed by a planetary mill to obtain powders with D50=1.7um and D50=4.0um respectively; S5. Mix the two particle size powders separately with polyamide binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0053] Example 4 This application provides a solid electrolyte with the chemical formula Li5Na. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0054] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Na2S, LiCl, LiBH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5Na was obtained. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0055] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.4um and D50=0.96um respectively; S5. Mix the two particle size powders separately with polyamide binder (14%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (120℃). S6. Place the mixture in a mold and hot-press it at 120°C with a pressure (30 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0056] Example 5 This application provides a solid electrolyte with the chemical formula Li5K. 0.5 PS 4.5 Cl1(BF4) 0.5 .

[0057] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, K2S, LiCl, LiBH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed 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. The compacted crucible is then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5K is obtained. 0.5 PS 4.5 Cl1(BF4) 0.5 .

[0058] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot-press it at 100°C with pressure (80 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0059] Example 6 This application provides a solid electrolyte with the chemical formula Li5Rb 0.5 PS 4.5 Cl1(AlF4) 0.5 .

[0060] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Rb2S, LiCl, LiAlF4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5Rb was obtained. 0.5 PS 4.5 Cl1(AlF4) 0.5 .

[0061] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide binder (16%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (80℃). S6. Place the mixture in a mold and hot-press it at 80°C with a pressure (90 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0062] Example 7 This application provides a solid electrolyte with the chemical formula Li5Cs. 0.5 PS 4.5 Cl1(AlH4) 0.5 .

[0063] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Cs2S, LiCl, LiAlH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5Cs was obtained. 0.5 PS 4.5Cl1(AlH4) 0.5 .

[0064] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide (polyethylene) binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot-press it at 100°C with a pressure (60 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0065] Example 8 This application provides a solid electrolyte with the chemical formula Li5Na. 0.5 PS 4.5 Cl1(AlH4) 0.5 .

[0066] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Na2S, LiCl, LiAlH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5Na was obtained. 0.5 PS 4.5 Cl1(AlH4) 0.5 .

[0067] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide (polyethylene) binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0068] Example 9 This application provides a solid electrolyte with the chemical formula Li5Rb 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0069] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Rb2S, LiCl, LiBH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5Rb was obtained. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0070] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0071] Comparative Example 1 This application provides a solid electrolyte with the chemical formula Li5Na. 0.5 PS 4.5 Cl 1.5 .

[0072] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Na2S, LiCl, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5Na was obtained. 0.5 PS 4.5 Cl 1.5 .

[0073] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0074] Comparative Example 2 This application provides a solid electrolyte with the chemical formula Li. 5.5 PS 4.5 Cl1(BH4) 0.5 .

[0075] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, LiCl, LiBH4 and P2S5 according to the chemical formula molar ratio, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed 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. The compacted crucible is then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li is obtained. 5.5 PS 4.5 Cl1(BH4) 0.5 .

[0076] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0077] Comparative Example 3 This application provides a solid electrolyte with the chemical formula Li. 5.5 PS 4.5 Cl 1.5 .

[0078] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, LiCl, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed 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. The compacted crucible is then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li is obtained. 5.5 PS 4.5 Cl 1.5 .

[0079] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.8um and D50=1.93um respectively; S5. Mix the two particle size powders separately with polyamide (polyethylene) binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0080] Comparative Example 4 This application provides a solid electrolyte with the chemical formula Li5Na. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0081] Specifically, the preparation method of the above-mentioned solid electrolyte includes the following steps: S1. Weigh Li2S, Na2S, LiCl, LiBH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li5Na was obtained. 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0082] S4. The cooled sample was ground and crushed by a planetary mill to obtain powders with D50=0.3um and D50=0.72um respectively; S5. Mix the two particle size powders separately with polyamide (polyethylene) binder (10%), mechanically mix them under a dry inert atmosphere, and then heat them to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, two different sizes of membranes are stacked in a small-large-small pattern and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0083] Comparative Example 5 This application provides a solid electrolyte with the chemical formula Li5Na 0.5 PS 4.5 Cl1(BH4) 0.5 .

[0084] Specifically, the preparation method of the above-mentioned sulfide solid electrolyte includes the following steps: S1. Weigh Li2S, Na2S, LiCl, LiBH4, and P2S5 according to their chemical formula molar ratios, and mix them evenly under an argon atmosphere to obtain a mixture. S2. The mixture is ball-milled in a ball milling jar under an argon atmosphere. The ball milling conditions are as follows: using zirconia balls as the ball milling medium, the mass ratio of the mixture to the zirconia balls is 1:32, the ball milling speed is 300 rpm, and the ball milling time is 10 h. S3. The ball-milled mixture was compacted in a square crucible under an argon atmosphere. The compacted crucible was then placed in a muffle furnace and sintered at 500°C for 12 hours under an argon atmosphere. After cooling, Li6Li5Na was obtained. 0.5 PS4.5 Cl1(BH4) 0.5 .

[0085] S4. The cooled sample is ground and crushed by a planetary mill to obtain powder with D50=0.8um; S5. Mix the powder with polyamide binder (10%), mechanically mix under a dry inert atmosphere, and then heat to the binder melting temperature (100℃). S6. Place the mixture in a mold and hot press it at 100°C with a pressure (50 MPa). S7. After hot pressing, the membrane is stacked in three layers and the hot pressing process is repeated to obtain a sandwich structure solid electrolyte membrane.

[0086] To verify the performance of the sandwich-structured solid electrolyte membranes provided in the above embodiments and comparative examples, the following method was used in the experimental example: Post-burning conductivity test method: Take a piece of the solid electrolyte calcined material provided in Examples 1-9 and Comparative Examples 1-5, place it in a mortar, and gently grind it into powder. Weigh 0.11-0.14g of the powder and place it in a mold with a diameter of 10mm and an area of ​​S=0.5*0.5*Π. The pressure is 10mpa, and the pressure is maintained for 10-15min. The impedance is tested using a Donghua electrochemical workstation. After obtaining the impedance data (R / Ω), the sheet is taken out and the thickness (H / cm) is tested. The ionic conductance is calculated according to the formula: ionic conductance = H / S / R.

[0087] Method for calculating the ionic conductivity of press-film membranes: The sandwich structure solid electrolyte membranes provided in Examples 1-9 and Comparative Examples 1-5 were cut into 10mm diameter discs using a slicer. The impedance and thickness (H / cm) were tested using a Donghua electrochemical workstation. The ion conductance was calculated according to the formula: ion conductance = H / S / R.

[0088] The results are shown in the table below: 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 The above experimental results show that: Comparison of Examples 1-9 and Comparative Example 1: The ionic conductivity achievable through co-doping cannot be reached without the addition of BH4. The reason is that doping with Na alone does not contribute enough to the degree of freedom of Li.

[0089] Comparison of Examples 1-9 and Comparative Example 2: The ionic conductivity achievable through co-doping cannot be reached without the addition of Na. The reason is that BH4 doping alone does not contribute enough to the degree of freedom of Li.

[0090] Comparison of Examples 1-9 and Comparative Example 3: When neither element is doped, the ionic conductance decreases further because there are no elements with large ionic radii to provide more degrees of freedom for Li migration.

[0091] Comparison of Examples 1-9 and Comparative Example 4: Particles that are too small will cause a significant decrease in ionic conductivity because the increased interparticle interfaces hinder ion conduction. Comparison of Examples 1-9 and Comparative Example 5: The use of three-layer small-particle-size membranes results in low ionic conductivity of the electrolyte membrane. This is because the excessively small particles increase the contact area between particles, which in turn leads to a decrease in ionic conductivity.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solid electrolyte, characterized in that, The solid electrolyte belongs to the cubic crystal system and has the following chemical formula: Li 5.5-x M x PS 4.5 Cl 1.5-z A z ; Where 0 < x ≤ 0.5, 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. M includes one or more of Na, K, Rb, and Cs. The A is selected from BF4, AlF4, or AlH4.

2. The method for preparing the solid electrolyte according to claim 1, 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.

3. The preparation method according to claim 2, characterized in that, The ball mill operates at a speed of 200-600 rpm for 4-20 hours.

4. The preparation method according to claim 2, characterized in that, Zirconia balls were used as the milling medium, and the mass ratio of raw material to zirconia balls was 1:10~40.

5. The preparation method according to claim 2, characterized in that, The calcination temperature is 300~700℃, and the time is 4~25h.

6. The preparation method according to claim 2, characterized in that, The heating rate for calcination is 4~10℃ / min.

7. The application of the solid electrolyte of claim 1 or the solid electrolyte prepared by any one of claims 2 to 6 in the preparation of solid electrolyte membranes.

8. 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 of claim 1 or a solid electrolyte prepared by any one of the preparation methods of claims 2 to 6.

9. The sandwich-structured solid electrolyte membrane according to claim 8, characterized in that, The particle size of the solid electrolyte in the core layer is 0.9~4μm; the particle size of the solid electrolyte in the interface layer is 0.4~1.7μm.

10. The sandwich-structured solid electrolyte membrane according to claim 8, characterized in that, The particle size ratio of the solid electrolyte in the core layer to the solid electrolyte in the interface layer is 0.

414.

11. The method for preparing the sandwich structure solid electrolyte membrane according to any one of claims 8-10, 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.

12. The preparation method according to claim 11, characterized in that, The adhesive includes polyamide or polyethylene.

13. The preparation method according to claim 12, characterized in that, The amount of binder added is 5% to 20% of the powder mass.

14. The preparation method according to claim 12, characterized in that, The hot pressing temperature is 80~150℃ and the pressure is 10~100 MPa.

15. An all-solid-state battery, characterized in that, Includes the solid electrolyte as described in claim 1, the solid electrolyte prepared by the preparation method described in any one of claims 2 to 6, the sandwich structure solid electrolyte membrane as described in any one of claims 8 to 10, or the sandwich structure solid electrolyte membrane prepared by the preparation method described in any one of claims 11 to 14.