Self-supporting ultra-thin solid electrolyte membrane, preparation method and all-solid-state battery

Abstract

The present invention discloses a self-supporting ultra-thin solid electrolyte membrane, a preparation method, and an all-solid-state battery. The membrane is composed of a solid electrolyte, a polymer, and a phosphate metal salt. The membrane is prepared by combining electrospinning, hot rolling, and other static pressing methods. The membrane contains a phosphate metal salt, which effectively improves the membrane's high-voltage and air-stability.

Description

Technical Field

[0001] The present invention relates to the field of solid-state batteries, and in particular to a self-supporting ultra-thin solid electrolyte membrane for all-solid-state batteries and a preparation method thereof. Background Art

[0002] In recent years, in order to improve safety, all-solid-state secondary batteries that use solid electrolytes instead of liquid electrolytes have attracted widespread attention.

[0003] Due to the non-flammability of solid electrolytes, lithium metal all-solid-state batteries based on sulfide solid electrolytes not only have high energy density but also high safety performance. However, in practical applications, excessively thick electrolyte membranes will greatly limit the battery energy density. Therefore, the preparation of a self-supporting ultra-thin solid electrolyte membrane is crucial.

[0004] There are various methods for preparing solid electrolyte membranes. Patent CN113363570A utilizes a direct mixing and compression molding of solid electrolyte powder and a fibrillating binder. Patent CN107968219A utilizes a mixture of a polymer, a solid electrolyte, and an organic solvent, followed by molding in a mold. However, due to the characteristics of the solid electrolyte particles and limitations of the preparation method, the electrolyte membrane produced by this method is relatively thick and difficult to maintain uniform thickness. Furthermore, the electrolyte membranes prepared by this method do not consider the stability of the polymer and electrolyte under high-pressure conditions. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a self-supporting ultra-thin solid electrolyte membrane for all-solid-state batteries and a preparation method thereof. The self-supporting ultra-thin electrolyte membrane is prepared by combining electrostatic spinning, hot rolling and other static pressing methods, and the electrolyte membrane contains phosphate metal salts, which can effectively improve the high-voltage stability and air stability of the electrolyte membrane.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A self-supporting ultra-thin solid electrolyte membrane is composed of a solid electrolyte, a polymer and a phosphate metal salt.

[0008] Preferably, the solid electrolyte is a sulfide solid electrolyte.

[0009] Preferably, the polymer is at least one of polyethylene oxide, polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, polyacrylic acid, carboxymethyl cellulose, polypropylene, polyethylene, polyimide, polyethylene terephthalate, polypropylene carbonate, polydimethylsiloxane, polyvinyl chloride, and nitrile rubber.

[0010] Preferably, the structural formula of the phosphate metal salt is:

[0011]

[0012] Among them, M + is a metal cation, and R is an alkyl group which is substituted or unsubstituted with a halogen atom and has more than 5 carbon atoms, or an unsaturated hydrocarbon group which is substituted or unsubstituted with a halogen atom and has more than 5 carbon atoms.

[0013] Preferably, the mass proportion of the solid electrolyte is 50% to 99.8%, the mass proportion of the polymer is 0.1% to 49.9%, and the mass proportion of the phosphate metal salt is 0.1% to 49.9%.

[0014] Preferably, the thickness of the electrolyte membrane is 3 μm to 100 μm.

[0015] A method for preparing a self-supporting ultrathin solid electrolyte membrane comprises the following steps:

[0016] S1, mixing a solid electrolyte, a polymer, a phosphate metal salt, and an organic solvent to obtain an electrolyte membrane precursor solution;

[0017] S2, preparing an electrolyte membrane from the electrolyte membrane precursor solution by electrospinning;

[0018] S3, densifying the prepared electrolyte membrane by hot rolling and cutting it into sheets;

[0019] S4. The hot rolled electrolyte membrane is subjected to isostatic pressing to obtain a self-supporting ultra-thin electrolyte membrane.

[0020] Preferably, the organic solvent is one or more of ethanol, isopropanol, n-butanol, toluene, chlorobenzene, ethyl acetate, butyl butyrate, n-heptane, petroleum ether, tetrahydrofuran, acetone, n-butyl ether, diethyl ether and cyclohexanone.

[0021] Preferably, the hot roller pressing heating temperature in step S3 is 50° C. to 200° C., and / or the isostatic pressure in step S4 is 50 MPa to 600 MPa.

[0022] An all-solid-state battery comprises a positive electrode and a negative electrode, with one or more layers of the above-mentioned self-supporting ultrathin solid electrolyte membrane arranged between the positive electrode and the negative electrode.

[0023] Compared with the prior art, the advantages of the self-supporting ultra-thin solid electrolyte membrane for all-solid-state batteries and the preparation method thereof of the present invention are:

[0024] (1) By compounding solid electrolyte, polymer and phosphate metal salt, and sequentially undergoing electrospinning, hot rolling and isostatic pressing, the self-supporting ultra-thin electrolyte membrane has the characteristics of thin thickness and good thickness uniformity, so that the all-solid-state battery with the self-supporting ultra-thin electrolyte membrane has a higher energy density.

[0025] (2) Phosphate metal salts are rich in oxygen-containing functional groups, which can effectively improve the air stability of the membrane when applied to solid electrolyte membranes, thereby improving the cycle performance of all-solid-state batteries.

[0026] (3) The alkyl group substituted or unsubstituted with halogen atoms having more than 5 carbon atoms, or the phosphate metal salt having an unsaturated hydrocarbon group substituted or unsubstituted with halogen atoms having more than 5 carbon atoms is in a solid state and can be combined with a polymer to inhibit the precipitation of the positive electrode material under high voltage, so that the all-solid-state battery with the self-supporting ultra-thin electrolyte membrane has the advantage of strong high-voltage stability.

[0027] (4) The preparation method of the self-supporting ultrathin solid electrolyte membrane provided by the present invention is simple, low-cost and easy to industrialize. DETAILED DESCRIPTION

[0028] The following examples further describe the present invention in detail.

[0029] Example

[0030] A self-supporting ultra-thin solid electrolyte membrane composed of a solid electrolyte, a polymer, and a phosphate metal salt. The solid electrolyte accounts for 50% to 99.8% by weight, the polymer accounts for 0.1% to 49.9% by weight, and the phosphate metal salt accounts for 0.1% to 49.9% by weight, with the sum of the three not exceeding 100%. The self-supporting ultra-thin solid electrolyte membrane has a thickness of 3μm to 100μm.

[0031] The solid electrolyte is a sulfide solid electrolyte, specifically including at least one of a binary sulfide solid electrolyte, an LGPS-type crystalline sulfide solid electrolyte, a Thio-LiSICON series, and an argyrodite-type crystalline sulfide solid electrolyte, wherein the binary sulfide solid electrolyte is mainly composed of Li2S-P2S5, specifically (100-a)Li2S·a P2S5, a=20-40; bLi2S·a P2S5·c LiBr·d LiI, b:a=3~4, (c+d) / (a+b+c+d)=5~50%.

[0032] The polymer is at least one of polyethylene oxide, polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, polyacrylic acid, carboxymethyl cellulose, polypropylene, polyethylene, polyimide, polyethylene terephthalate, polypropylene carbonate, polydimethylsiloxane, polyvinyl chloride, and nitrile rubber.

[0033] The structural formula of phosphate metal salt is:

[0034]

[0035] Among them, M + is a metal cation, preferably Li + , R is a halogen-substituted or unsubstituted alkyl group having more than 5 carbon atoms, or a halogen-substituted or unsubstituted unsaturated hydrocarbon group having more than 5 carbon atoms.

[0036] A method for preparing a self-supporting ultrathin solid electrolyte membrane comprises the following steps:

[0037] S1, mixing a solid electrolyte, a polymer, a phosphate metal salt, and an organic solvent to obtain an electrolyte membrane precursor solution;

[0038] S2, preparing an electrolyte membrane from the electrolyte membrane precursor solution by electrospinning;

[0039] S3, densifying the prepared electrolyte membrane by hot rolling and cutting it into sheets;

[0040] S4. The hot rolled electrolyte membrane is subjected to isostatic pressing to obtain a self-supporting ultra-thin electrolyte membrane.

[0041] The organic solvent is one or more of ethanol, isopropanol, n-butanol, toluene, chlorobenzene, ethyl acetate, butyl butyrate, n-heptane, petroleum ether, tetrahydrofuran, acetone, n-butyl ether, diethyl ether and cyclohexanone.

[0042] The heating temperature of the hot roller pressing in step S3 is 50° C. to 200° C., and the medium static pressure in step S4 is 50 MPa to 600 MPa.

[0043] Example 1

[0044] LGPS, polyethylene oxide, and phosphate metal salt were weighed in a mass ratio of 50:49.9:0.1, totaling 10g. 50mL of toluene solvent was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot roller milled at 80°C to a thickness of 5μm and then isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery. The voltage ranges were 3.0V~4.45V and 3.0V~4.25V, respectively. The structural formula of the phosphate metal salt in this embodiment is shown below (I), where M=Li.

[0045]

[0046] Example 2

[0047] The difference from Example 1 is that the film is hot-rolled at 50° C. to a thickness of 3 μm and then is isostatically pressed at 300 MPa to form a self-supporting ultrathin solid electrolyte membrane.

[0048] Comparative Example 1

[0049] LGPS and polyethylene oxide (PEO) were weighed in a 50:50 mass ratio, totaling 10g. 50mL of toluene was added to completely dissolve the two materials. The resulting membrane was formed by electrospinning, then hot-rolled at 80°C to a thickness of 5μm and isostatically pressed at 300MPa to form a solid electrolyte membrane. This solid electrolyte membrane served as the battery's interlayer, along with graphite as the negative electrode and lithium cobalt oxide as the positive electrode, to form an all-solid-state battery. The voltage ranges were 3.0V to 4.45V and 3.0V to 4.25V, respectively.

[0050] Example 3

[0051] Li6PS5Cl, polyethylene oxide, and phosphate metal salt were weighed in a mass ratio of 50:49.9:0.1, totaling 10g. 50mL of toluene solvent was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot roller milled at 80°C to a thickness of 5μm and then isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery. The voltage ranges were 3.0V~4.45V and 3.0V~4.25V, respectively. The structural formula of the phosphate metal salt in this embodiment is shown in (I), where M=Li.

[0052] Comparative Example 2

[0053] Li6PS5Cl and polyethylene oxide were weighed in a mass ratio of 50.1:49.9, totaling 10g. 50mL of toluene was added to completely dissolve the two materials. The resulting membrane was formed by electrospinning, then hot-rolled at 80°C to a thickness of 5μm and isostatically pressed at 300MPa to form a solid electrolyte membrane. This solid electrolyte membrane served as the battery's intermediate layer, along with graphite as the negative electrode and lithium cobalt oxide as the positive electrode, to form an all-solid-state battery. The voltage ranges were 3.0V to 4.45V and 3.0V to 4.25V, respectively.

[0054] Example 4

[0055] Li6PS5Cl, nitrile rubber, and phosphate metal salt were weighed in a mass ratio of 50:49.9:0.1, totaling 10g. 50mL of toluene solvent was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot-rolled at 80°C to a thickness of 5μm and then isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with a voltage of 3.0V to 4.45V. The structural formula of the phosphate metal salt in this embodiment is shown in (I), where M = Li.

[0056] Example 5

[0057] Li6PS5Cl, nitrile rubber, and phosphate metal salt were weighed in a mass ratio of 50:49.9:0.1, totaling 10g. 50mL of toluene solvent was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot-rolled at 80°C to a thickness of 5μm and then isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with a voltage of 3.0V to 4.45V. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M = Li.

[0058]

[0059] Example 6

[0060] Li6PS5Cl, nitrile rubber, and phosphate metal salt were weighed in a mass ratio of 99.8:0.1:0.1, totaling 10g. 50mL of toluene solvent was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot roller milled at 80°C to a thickness of 5μm and then isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery. The voltage ranges were 3.0V~4.45V and 3.0V~4.25V, respectively. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M=Li.

[0061] Comparative Example 3

[0062] Li6PS5Cl and nitrile rubber were weighed in a mass ratio of 99.8:0.2, totaling 10g. 50mL of toluene was added to completely dissolve the two materials. The resulting membrane was formed by electrospinning, then hot-rolled at 80°C to a thickness of 5μm and isostatically pressed at 300MPa to form a solid electrolyte membrane. This solid electrolyte served as the battery's interlayer, along with graphite as the negative electrode and lithium cobalt oxide as the positive electrode, to form an all-solid-state battery. The voltage ranges were 3.0V to 4.45V and 3.0V to 4.25V, respectively.

[0063] Example 7

[0064] Li6PS5Cl, nitrile rubber, and phosphate metal salt were weighed in a mass ratio of 50:0.1:49.9, totaling 10g. 50mL of toluene solvent was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot roller milled at 80°C to a thickness of 5μm and then isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with a voltage of 3.0V to 4.45V. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M = Li.

[0065] Example 8

[0066] Li6PS5Cl, nitrile rubber, and phosphate metal salt were weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of tetrahydrofuran solvent was added to completely dissolve the three materials. The membrane was formed by electrospinning, then hot-rolled at 80°C to a thickness of 5μm and then isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery interlayer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with voltage ranges of 3.0V to 4.45V and 3.0V to 4.25V, respectively. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M = Li.

[0067] Comparative Example 4

[0068] Li6PS5Cl and nitrile rubber were weighed in a mass ratio of 95:5, totaling 10g. 50mL of tetrahydrofuran (THF) was added to completely dissolve the two materials. The resulting membrane was formed by electrospinning, then hot-rolled at 80°C to a thickness of 5μm and isostatically pressed at 300MPa to form a solid electrolyte membrane. This solid electrolyte membrane served as the battery's interlayer, along with graphite as the negative electrode and lithium cobalt oxide as the positive electrode, to form an all-solid-state battery. The voltage ranges were 3.0V to 4.45V and 3.0V to 4.25V, respectively.

[0069] Example 9

[0070] Li6PS5Cl, nitrile rubber, and phosphate metal salt were weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot-rolled at 80°C to a thickness of 5μm and then isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with a voltage of 3.0V to 4.45V. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M = Li.

[0071] Example 10

[0072] Li 5.4 PS 4.4 Cl 1.6, polyimide, and phosphate metal salt are weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of solvent (n-heptane + n-butyl ether) is added to completely dissolve the three materials. The membrane is formed by electrospinning, and then hot roller milled at 80°C to a thickness of 5μm and isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane is used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with voltage ranges of 3.0V~4.45V and 3.0V~4.25V, respectively. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M=Li.

[0073] Comparative Example 5

[0074] Li 5.4 PS 4.4 Cl 1.6 10g of polyimide and polyimide were weighed in a 95:5 mass ratio. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the three materials. The membrane was then formed by electrospinning. This membrane was then hot-rolled at 80°C to a thickness of 5μm and isostatically pressed at 300MPa to form a solid electrolyte membrane. This solid electrolyte served as the battery's interlayer, along with graphite as the negative electrode and lithium cobalt oxide as the positive electrode, to form an all-solid-state battery. The voltage ranges were 3.0V to 4.45V and 3.0V to 4.25V, respectively.

[0075] Example 11

[0076] Li6PS5Cl, nitrile rubber, and phosphate metal salt were weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot-rolled at 200°C to a thickness of 100μm and isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with a voltage of 3.0V to 4.45V. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M = Li.

[0077] Example 12

[0078] Li6PS5Cl, nitrile rubber, and phosphate metal salt were weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot-rolled at 200°C to a thickness of 100μm and isostatically pressed at 300MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with a voltage of 3.0V to 4.45V. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M = Li.

[0079] Example 13

[0080] Li7P3S 11 , nitrile rubber, and phosphate metal salts were weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot roller-milled at 150°C to a thickness of 15μm and then isostatically pressed at 50MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery. The voltage ranges were 3.0V~4.45V and 3.0V~4.25V, respectively. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M=Li.

[0081] Comparative Example 6

[0082] Li7P3S 11 10g of nitrile rubber and butadiene-acrylonitrile rubber were weighed in a mass ratio of 95:5. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the two materials. The membrane was formed by electrospinning, then hot-rolled at 150°C to a thickness of 15μm and isostatically pressed at 50MPa to form a solid electrolyte membrane. This solid electrolyte membrane was used as the battery interlayer, with graphite as the negative electrode and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery. The voltage ranges were 3.0V to 4.45V and 3.0V to 4.25V, respectively.

[0083] Example 14

[0084] Li7P3S 11, nitrile rubber, and phosphate metal salts were weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot-rolled at 150°C to a thickness of 15μm and then isostatically pressed at 600MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with a voltage of 3.0V to 4.45V. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M=Li.

[0085] Example 15

[0086] Li7P3S 11 , nitrile rubber, and phosphate metal salts were weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot-rolled at 150°C to a thickness of 15μm and then isostatically pressed at 600MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery with a voltage of 3.0V to 4.45V. The structural formula of the phosphate metal salt in this embodiment is shown in (II), where M=Li.

[0087] Example 16

[0088] Li7P3S 11 , nitrile rubber, and phosphate metal salts were weighed in a mass ratio of 95:4:1, totaling 10g. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the three materials. The membrane was formed by electrospinning, and then hot roller-milled at 150°C to a thickness of 15μm and isostatically pressed at 600MPa to form a self-supporting ultra-thin solid electrolyte membrane. The self-supporting ultra-thin solid electrolyte membrane was used as the battery intermediate layer, graphite as the negative electrode, and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery. The voltage ranges were 3.0V~4.45V and 3.0V~4.25V, respectively. The structural formula of the phosphate metal salt in this embodiment is shown in (III), where M=Li.

[0089]

[0090] Comparative Example 7

[0091] Li7P3S 1110g of nitrile rubber and butadiene-acrylonitrile rubber were weighed in a mass ratio of 95:5. 50mL of solvent (n-heptane + n-butyl ether) was added to completely dissolve the two materials. The membrane was formed by electrospinning, then hot-rolled at 150°C to a thickness of 15μm and isostatically pressed at 600MPa to form a solid electrolyte membrane. This solid electrolyte was used as the battery interlayer, with graphite as the negative electrode and lithium cobalt oxide as the positive electrode to assemble an all-solid-state battery. The voltage ranges were 3.0V to 4.45V and 3.0V to 4.25V, respectively.

[0092] All-solid-state batteries were prepared using the methods of Examples 1-16 and Comparative Examples 1-7, and charge and discharge cycle tests were performed. Each group included three parallel samples, and each set of test data used the average value of the three parallel samples. The specific data are shown in the following table.

[0093]

[0094]

[0095] Although the preferred embodiments of the present invention have been described in detail above, it should be clearly understood that various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A self-supporting solid electrolyte membrane, characterized in that: It is composed of a sulfide solid electrolyte, a polymer and a phosphate metal salt. The phosphate metal salt has the structural formula: Among them, M + For Li + ; R is a halogen-substituted or unsubstituted alkyl group having more than 5 C atoms, or a halogen-substituted or unsubstituted unsaturated hydrocarbon group having more than 5 C atoms; The mass proportion of the sulfide solid electrolyte is 50% to 99.8%, the mass proportion of the polymer is 0.1% to 49.9%, and the mass proportion of the phosphate metal salt is 0.1% to 49.9%; The thickness of the electrolyte membrane is 3 μm to 100 μm; The method for preparing the self-supporting solid electrolyte membrane comprises the following steps: S1, mixing a solid electrolyte, a polymer, a phosphate metal salt, and an organic solvent to obtain an electrolyte membrane precursor solution; S2. preparing an electrolyte membrane from the electrolyte membrane precursor solution by electrospinning; S3, densifying the prepared electrolyte membrane by hot rolling and cutting it into sheets; S4. Performing isostatic pressing on the hot rolled electrolyte membrane to obtain a self-supporting electrolyte membrane.

2. The self-supporting solid electrolyte membrane according to claim 1, wherein: The polymer is at least one of polyethylene oxide, polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, polyacrylic acid, carboxymethyl cellulose, polypropylene, polyethylene, polyimide, polyethylene terephthalate, polypropylene carbonate, polydimethylsiloxane, polyvinyl chloride, and nitrile rubber.

3. A method for preparing a self-supporting solid electrolyte membrane according to claim 1, characterized in that: The following steps are involved: S1, mixing a solid electrolyte, a polymer, a phosphate metal salt, and an organic solvent to obtain an electrolyte membrane precursor solution; S2. preparing an electrolyte membrane from the electrolyte membrane precursor solution by electrospinning; S3, densifying the prepared electrolyte membrane by hot rolling and cutting it into sheets; S4. Performing isostatic pressing on the hot rolled electrolyte membrane to obtain a self-supporting electrolyte membrane.

4. The method for preparing a self-supporting solid electrolyte membrane according to claim 3, wherein: The organic solvent is one or more of ethanol, isopropanol, n-butanol, toluene, chlorobenzene, ethyl acetate, butyl butyrate, n-heptane, petroleum ether, tetrahydrofuran, acetone, n-butyl ether, diethyl ether and cyclohexanone.

5. The method for preparing a self-supporting solid electrolyte membrane according to claim 3, wherein: The hot roller pressing heating temperature in step S3 is 50° C. to 200° C., and / or the isostatic pressure in step S4 is 50 MPa to 600 MPa.

6. An all-solid-state battery, characterized in that: The self-supporting solid electrolyte membrane comprises a positive electrode and a negative electrode, wherein one or more layers of the self-supporting solid electrolyte membrane according to any one of claims 1 to 2 are arranged between the positive electrode and the negative electrode.

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