Solid electrolyte membrane, preparation method therefor and use thereof

Abstract

Provided are a solid electrolyte membrane, a preparation method therefor and the use thereof, belonging to the technical field of solid-state batteries. In the solid electrolyte membrane, a sulfide solid electrolyte is coated with a coating layer containing an aprotic Lewis acid, so as to target and stabilize Lewis alkaline reaction sites in the sulfide solid electrolyte, thus greatly reducing the probability of the sulfide solid electrolyte reacting with moisture in the air. In addition, the initial ionic conductivity of the prepared solid electrolyte membrane and the rate of change in the ionic conductivity thereof under a specific condition are limited, so that a prepared secondary battery to which the product is applied has an ideal initial discharge capacity and good cycle stability.

Description

Solid electrolyte membrane and its preparation method and application Technical Field

[0001] The present application relates to the field of solid-state battery technology, and in particular to a solid-state electrolyte membrane and a preparation method and application thereof. Background Art

[0002] Among secondary batteries, all-solid-state batteries using solid electrolytes offer higher energy density and improved safety compared to lithium-ion batteries using liquid electrolytes. Among solid electrolytes, sulfide solid electrolytes are theoretically the most promising for industrial all-solid-state secondary batteries because their ionic conductivity at room temperature is close to that of liquid electrolytes. However, sulfide solid electrolytes are highly sensitive to air and moisture. When they react with moisture in the air, not only does their ionic conductivity decrease significantly, but they can also produce toxic hydrogen sulfide gas.

[0003] Summary of the Invention

[0004] The purpose of this application is to overcome the shortcomings of the existing technology and provide a solid electrolyte membrane, its preparation method, and its application. The solid electrolyte membrane of this application uses a coating layer containing an aprotic Lewis acid to coat a sulfide solid electrolyte, thereby targeting and stabilizing the Lewis basic reaction sites of the sulfide solid electrolyte, significantly reducing the probability of its reaction with moisture in the air. When the solid electrolyte membrane is applied to a secondary battery, the secondary battery has an ideal initial discharge capacity and good cycling stability.

[0005] In a first aspect of the present application, the present application provides a solid electrolyte membrane comprising a sulfide solid electrolyte and a coating layer provided on the surface of the sulfide solid electrolyte;

[0006] The coating layer comprises an aprotic Lewis acid;

[0007] The solid electrolyte membrane satisfies: A1-A2≤1 and A1≥1.5;

[0008] Wherein, A1 is the ionic conductivity of the solid electrolyte membrane at room temperature with a water content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm for 60 minutes, and the unit is mS / cm; A2 is the ionic conductivity of the solid electrolyte membrane in an air environment at 25°C and a relative humidity of 50% for 60 minutes, and the unit is mS / cm.

[0009] As an implementation scheme of the present application, the range of A1 is: 1.5mS / cm≤A1≤9mS / cm.

[0010] As an implementation scheme of the present application, the range of A2 is: 1mS / cm≤A2≤8.6mS / cm.

[0011] As an embodiment of the present application, the aprotic Lewis acid includes at least one of boron halide, aluminum halide, iron halide, copper halide, cobalt halide, zinc halide, titanium halide, zirconium halide, niobium halide, Al(CH3)3, p-benzoquinone, 1,4-naphthoquinone, 9,10-phenanthrenequinone, and 9,10-anthraquinone.

[0012] As an embodiment of the present application, the aprotic Lewis acid includes at least one of boron halide, aluminum halide, iron halide, copper halide, cobalt halide, zinc halide, titanium halide, zirconium halide, niobium halide, and Al(CH3)3.

[0013] As an embodiment of the present application, the mass content of the aprotic Lewis acid in the sulfide solid electrolyte is 1 to 4 wt%.

[0014] As an embodiment of the present application, the aprotic Lewis acid includes aluminum halide, and the mass content of the aluminum halide in the sulfide solid electrolyte is 1 to 3 wt%.

[0015] As an embodiment of the present application, the general formula of the sulfide solid electrolyte is Li x A y B z , wherein A includes one or two of Ge, Sn, and P, B includes one or two of S and Cl, 3≤x≤10, 1≤y≤3, 0≤z≤12.

[0016] As an embodiment of the present application, the sulfide solid electrolyte includes Li 10 GeP2S 12 、Li7P3S 11 、Li6PS5Cl、Li 5.5 PS 4.5 Cl 1.5 、Li 10 SnP2S 12 , Li3PS4 or at least one of them.

[0017] In a second aspect of the present application, the present application provides a method for preparing the solid electrolyte membrane, comprising the following steps:

[0018] Dispersing and mixing aprotic Lewis acid, sulfide solid electrolyte and binder in a solvent to prepare slurry, coating and drying to obtain a solid electrolyte membrane; or

[0019] The proton type Lewis acid, sulfide solid electrolyte and binder are dispersed and mixed, and then rolled to obtain a solid electrolyte membrane.

[0020] In a third aspect of the present application, the present application provides a solid-state battery comprising the solid-state electrolyte membrane.

[0021] In a fourth aspect of the present application, the present application provides an electrical device, comprising the solid-state battery, wherein the solid-state battery serves as a power supply for the electrical device.

[0022] The present application provides a solid electrolyte membrane and its preparation method and application. The solid electrolyte membrane of the present application uses a non-proton Lewis acid as a coating layer to coat a sulfide solid electrolyte, thereby targeting and stabilizing the Lewis alkaline reaction sites of the sulfide solid electrolyte, greatly reducing the probability of its reaction with moisture in the air. At the same time, using a non-proton Lewis acid as a coating layer to coat the sulfide solid electrolyte can also make the conductivity of the solid electrolyte membrane and the rate of change of ionic conductivity under specific conditions within a suitable range, so that after the solid electrolyte membrane is applied to a secondary battery, the secondary battery has an ideal initial discharge capacity and good cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is an XRD diagram of the sulfide Li6PS5Cl and the prepared solid electrolyte membrane in Example 1 of the present application. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0026] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0027] In the present application, there is no particular restriction on the specific dispersion, stirring, and rolling treatment methods, and those skilled in the art can select appropriate specific dispersion, stirring, and rolling treatment methods according to actual needs; there is no particular restriction on the solvents and binders used in the preparation of solid electrolyte membranes, and those skilled in the art can select appropriate dispersion solvents and binders according to actual needs.

[0028] The reagents and instruments used in this application without manufacturer indication are all conventional products that can be purchased commercially.

[0029] The present application is further described below with specific examples:

[0030] The embodiment of the present application provides a solid electrolyte membrane, comprising a sulfide solid electrolyte and a coating layer provided on the surface of the sulfide solid electrolyte;

[0031] The coating layer comprises an aprotic Lewis acid;

[0032] The solid electrolyte satisfies: A1-A2≤1 and A1≥1.5;

[0033] Wherein, A1 is the ionic conductivity of the solid electrolyte membrane at room temperature with a water content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm for 60 minutes, and the unit is mS / cm; A2 is the ionic conductivity of the solid electrolyte membrane in an air environment at 25°C and a relative humidity of 50% for 60 minutes, and the unit is mS / cm.

[0034] When sulfide solid electrolytes are used to prepare solid electrolyte membranes, their production and application conditions are very harsh. The main reason is that sulfide solid electrolytes are very easy to react with moisture in the air, thereby reducing their ionic conductivity and even producing toxic hydrogen sulfide. In order to improve the air stability of sulfide solid electrolytes and reduce the probability of their reaction with water, they can be modified by adopting bulk doping or constructing an outer inert insulating coating layer. For products modified by bulk doping, when the amount of doping is too small, the air stability of the prepared sulfide solid electrolyte membrane is not significantly improved, and when the doping amount is too high, the crystal structure of the sulfide solid electrolyte will be destroyed, thereby reducing the ionic conductivity of the prepared sulfide solid electrolyte membrane. For products modified by constructing an outer inert insulating coating layer, although the coating layer reduces the probability of the sulfide solid electrolyte reacting with water, when the product is applied to a battery, it is easy to block the lithium ion transmission channel, thereby causing the electrochemical performance of the battery to decline. Therefore, the present application provides a solid electrolyte membrane and a solid-state battery including the solid electrolyte membrane, which can effectively improve the above problems. In the present application, a layer of non-proton Lewis acid is provided on the surface of the sulfide solid electrolyte, and the empty orbitals of the substance interact with the electrons of the alkaline sites of the sulfide solid electrolyte to avoid the site from reacting with water, thereby improving the air stability of the sulfide solid electrolyte. At the same time, the substance will also selectively combine with the alkaline sites, greatly reducing the impact on the initial ionic conductivity of the sulfide solid electrolyte. In this way, by controlling the initial ionic conductivity of the product and the rate of change of ionic conductivity under specific conditions in a suitable range, the solid electrolyte membrane can be made to have a high initial discharge specific capacity when applied to a secondary battery, and also a high cycle stability.

[0035] In some embodiments, the range of A1 is: 1.5 mS / cm≤A1≤9 mS / cm; the range of A2 is: 1 mS / cm≤A2≤8.6 mS / cm.

[0036] For example, the A1 is a range value of one or any two of 1.5 mS / cm, 1.6 mS / cm, 1.7 mS / cm, 1.8 mS / cm, 1.9 mS / cm, 2 mS / cm, 2.5 mS / cm, 3 mS / cm, 3.5 mS / cm, 4 mS / cm, 4.5 mS / cm, 5 mS / cm, 6 mS / cm, 7 mS / cm, 7.2 mS / cm, 7.4 mS / cm, 7.5 mS / cm, 7.7 mS / cm, 7.8 mS / cm, 7.9 mS / cm, 8 mS / cm, 8.1 mS / cm, 8.5 mS / cm, 8.6 mS / cm, 8.9 mS / cm, and 9 mS / cm. The A2 is a range value of one or any two of 1mS / cm, 1.2mS / cm, 1.4mS / cm, 1.5mS / cm, 1.8mS / cm, 2mS / cm, 2.5mS / cm, 3mS / cm, 3.5mS / cm, 4mS / cm, 4.5mS / cm, 5mS / cm, 6mS / cm, 6.5mS / cm, 6.9mS / cm, 7mS / cm, 7.1mS / cm, 7.2mS / cm, 7.4mS / cm, 7.7mS / cm, 7.8mS / cm, 8mS / cm, 8.2mS / cm, 8.5mS / cm, and 8.6mS / cm.

[0037] The ionic conductivity of the solid electrolyte membrane and its rate of change after exposure to a humid environment can demonstrate the product's lithium ion conductivity and air stability. These properties of the solid electrolyte membrane are related to its performance when used in a secondary battery. When A1 and A2 of the solid electrolyte membrane are within the above ranges, the secondary battery using the solid electrolyte membrane can achieve excellent ion transport during the charge and discharge process, thereby exhibiting a high discharge specific capacity, while also ensuring that the secondary battery achieves excellent cycle performance.

[0038] Specifically, the A1 test method is as follows: the solid electrolyte membrane is placed in an environment with a water content of less than 0.1ppm and an oxygen content of less than 0.1ppm for 60 minutes. The solid electrolyte membrane (the test sample is a disc with a diameter of 10μm) is then placed in a mold battery. Carbon-coated aluminum foil is then placed on both sides of the solid electrolyte membrane as blocking electrodes. After applying a pressure of 360MPa to the assembled mold battery, an electrochemical impedance spectroscopy (EIS) test is performed. Finally, the EIS spectrum is fitted to test the thickness of the solid electrolyte membrane and calculate the ionic conductivity of the solid electrolyte membrane.

[0039] The test method of A2 is: placing the solid electrolyte membrane in an air environment at 25° C. and 50% relative humidity for 60 minutes, and testing and calculating the ionic conductivity of the solid electrolyte membrane in the same manner as the above test A1.

[0040] In some embodiments, the aprotic Lewis acid includes at least one of boron halide, aluminum halide, iron halide, copper halide, cobalt halide, zinc halide, titanium halide, zirconium halide, niobium halide, Al(CH3)3, p-benzoquinone, 1,4-naphthoquinone, 9,10-phenanthrenequinone, and 9,10-anthraquinone.

[0041] When the coating layer of a sulfide solid electrolyte contains these substances, they can effectively stabilize the active sites in the sulfide solid electrolyte that react with water. Furthermore, due to the excellent stability of these substances, when the sulfide solid electrolyte membrane is applied to a secondary battery, these substances will not react with other components of the solid electrolyte or the electrode, thus not affecting the electrochemical performance of the secondary battery.

[0042] In some embodiments, the aprotic Lewis acid includes aluminum chloride. Aluminum chloride has moderate acidity, strong binding ability with basic sites in the sulfide solid electrolyte, and does not directly react chemically with the sulfide solid electrolyte.

[0043] In some embodiments, the mass content of the aprotic Lewis acid in the sulfide solid electrolyte is 1 to 4 wt %. For example, the mass content of the aprotic Lewis acid in the sulfide solid electrolyte can be in the range of one or any two of 1 wt %, 2 wt %, 2.5 wt %, 3 wt %, and 4 wt %.

[0044] When the mass content of the aprotic Lewis acid in the sulfide solid electrolyte is maintained within the above range, the solid electrolyte membrane can achieve a balance between maintaining optimal ionic conductivity and air stability.

[0045] In some embodiments, the general formula of the sulfide solid electrolyte is Li x A y B z , wherein A includes one or two of Ge, Sn, and P, B includes one or two of S and Cl, 3≤x≤10, 1≤y≤3, 0≤z≤12.

[0046] Furthermore, the sulfide solid electrolyte includes Li 10 GeP2S 12 、Li7P3S 11 、Li6PS5Cl、Li 5.5 PS 4.5 Cl 1.5 、Li10 SnP2S 12 , Li3PS4 or at least one of them.

[0047] The present application is further described below with specific examples:

[0048] In each embodiment and comparative example, the glove box environment refers to an environment with a temperature of 25° C., a water content of less than 0.1 ppm, and an oxygen content of less than 0.1 ppm.

[0049] Example 1

[0050] A solid electrolyte membrane, the preparation method of which comprises the following steps:

[0051] (1) In a glove box, 0.02 g of NBR was dissolved in 2 mL of anhydrous toluene, and then Li6PS5Cl and BBr3 were added in a mass ratio of 99:1, where the mass ratio of Li6PS5Cl to NBR was 98:2.

[0052] (2) The mixture obtained in step (1) was ball-milled into a slurry in a ball mill, and then coated on a nylon mesh substrate and vacuum-dried at 60° C. to obtain a solid electrolyte membrane.

[0053] The solid electrolyte membrane was cut into 10 mm diameter discs and allowed to stand for 60 minutes in the same glove box environment before testing its ionic conductivity (A1). The membrane was then transferred to an air environment at 25°C and 50% relative humidity for 60 minutes before being returned to the glove box. The ionic conductivity (A2) of the membrane was then tested using the same testing method as for A1.

[0054] The parameter conditions are shown in Table 1.

[0055] Example 2

[0056] A solid electrolyte membrane, the only difference from Example 1 is that the mass ratio of Li6PS5Cl and BBr3 is 98:2.

[0057] Example 3

[0058] A solid electrolyte membrane, the only difference from Example 1 is that the mass ratio of Li6PS5Cl and BBr3 is 97:3.

[0059] Example 4

[0060] A solid electrolyte membrane, the preparation method of which comprises the following steps:

[0061] (1) In a glove box, 0.02 g of NBR was dissolved in 2 mL of anhydrous toluene, and then Li6PS5Cl and ZnCl2 were added in a mass ratio of 99:1, where the mass ratio of Li6PS5Cl to NBR was 98:2.

[0062] (2) The mixture obtained in step (1) was ball-milled into a slurry in a ball mill, and then coated on a nylon mesh substrate and vacuum-dried at 60° C. to obtain a solid electrolyte membrane.

[0063] The solid electrolyte membrane was cut into 10 mm diameter discs and allowed to stand for 60 minutes in the same glove box environment before testing its ionic conductivity (A1). The membrane was then transferred to an air environment at 25°C and 50% relative humidity for 60 minutes before being returned to the glove box. The ionic conductivity (A2) of the membrane was then tested using the same testing method as for A1.

[0064] Example 5

[0065] A solid electrolyte membrane, the only difference from Example 4 is that the mass ratio of Li6PS5Cl and ZnCl2 is 98:2.

[0066] Example 6

[0067] A solid electrolyte membrane, the only difference from Example 4 is that the mass ratio of Li6PS5Cl and ZnCl2 is 97:3.

[0068] Example 7

[0069] A solid electrolyte membrane, the preparation method of which comprises the following steps:

[0070] (1) In a glove box environment, Li was added at a mass ratio of 99:1. 5.5 PS 4.5 Cl 1.5 Mixed with AlCl3;

[0071] (2) The mixture obtained in step (1) was transferred to a sealed ball mill in a glove box, and then ball milled at 500 r / min for 600 min to obtain a mixture;

[0072] (3) The mixture and polytetrafluoroethylene were mixed and ball-milled in a mass ratio of 99.5:0.5, and then the powder was roller-pressed to obtain a solid electrolyte membrane.

[0073] The solid electrolyte membrane was cut into 10 mm diameter discs and allowed to stand for 60 minutes in the same glove box environment before testing its ionic conductivity (A1). The membrane was then transferred to an air environment at 25°C and 50% relative humidity for 60 minutes before being returned to the glove box. The ionic conductivity (A2) of the membrane was then tested using the same testing method as for A1.

[0074] Example 8

[0075] A solid electrolyte membrane, the difference from Example 7 is that the Li 5.5 PS 4.5 Cl 1.5 The mass ratio of AlCl3 is 98:2.

[0076] Example 9

[0077] A solid electrolyte membrane, the difference from Example 7 is that the Li 5.5 PS 4.5 Cl 1.5 The mass ratio of AlCl3 is 97:3.

[0078] Example 10

[0079] A solid electrolyte membrane, the difference from Example 7 is that the Li 5.5 PS 4.5 Cl 1.5 The mass ratio of AlCl3 is 96:4.

[0080] Example 11

[0081] A solid electrolyte membrane, the preparation method of which comprises the following steps:

[0082] (1) In a glove box environment, Li was added at a mass ratio of 99:1. 10 GeP2S 12 Mixed with AlCl3;

[0083] (2) The mixture obtained in step (1) was transferred to a sealed ball mill in a glove box, and then ball milled at 500 r / min for 600 min to obtain a mixture;

[0084] (3) The mixture and polytetrafluoroethylene were mixed and ball-milled in a mass ratio of 99.5:0.5, and the obtained powder was roller-pressed to obtain a solid electrolyte membrane.

[0085] The solid electrolyte membrane was cut into 10 mm diameter discs and allowed to stand for 60 minutes in the same glove box environment before testing its ionic conductivity (A1). The membrane was then transferred to an air environment at 25°C and 50% relative humidity for 60 minutes before being returned to the glove box. The ionic conductivity (A2) of the membrane was then tested using the same testing method as for A1.

[0086] Example 12

[0087] A solid electrolyte membrane, the difference from Example 11 is that the Li 10 GeP2S 12 The mass ratio of AlCl3 is 98:2.

[0088] Example 13

[0089] A solid electrolyte membrane, the difference from Example 11 is that the Li 10 GeP2S 12 The mass ratio of AlCl3 is 97:3.

[0090] Example 14

[0091] A solid electrolyte membrane, the difference from Example 11 is that the Li 10 GeP2S 12 The mass ratio of AlCl3 is 96:4.

[0092] Example 15

[0093] A solid electrolyte membrane, the only difference from Example 1 is that the mass ratio of Li6PS5Cl and BBr3 is 99.5:0.5.

[0094] Example 16

[0095] A solid electrolyte membrane, the only difference from Example 1 is that the mass ratio of Li6PS5Cl and BBr3 is 96:4.

[0096] Example 17

[0097] A solid electrolyte membrane, the only difference from Example 4 is that the mass ratio of Li6PS5Cl and ZnCl2 is 99.5:0.5.

[0098] Example 18

[0099] A solid electrolyte membrane, the difference from Example 4 is only that the mass ratio of Li6PS5Cl and ZnCl2 is 96:4.

[0100] Example 19

[0101] A solid electrolyte membrane, the difference from Example 7 is that the Li 5.5 PS 4.5 Cl 1.5 The mass ratio of AlCl3 is 99.5:0.5.

[0102] Example 20

[0103] A solid electrolyte membrane, the difference from Example 11 is that the Li 10 GeP2S 12 The mass ratio of AlCl3 is 99.5:0.5.

[0104] Comparative Example 1

[0105] A solid electrolyte membrane, the preparation method of which comprises the following steps:

[0106] (1) In a glove box, 0.02 g of NBR was dissolved in 2 mL of anhydrous toluene, and then Li6PS5Cl was added. The mass ratio of Li6PS5Cl to NBR was 98:2.

[0107] (2) The mixture obtained in step (1) was ball-milled into a slurry in a ball mill, and then coated on a nylon mesh substrate and vacuum-dried at 60° C. to obtain a solid electrolyte membrane.

[0108] The solid electrolyte membrane was cut into 10 mm diameter discs and allowed to stand for 60 minutes in the same glove box environment. The ionic conductivity A1 of the solid electrolyte membrane was then measured. The solid electrolyte membrane was then transferred to an air environment at 25°C and 50% relative humidity for 60 minutes. The membrane was then returned to the glove box and tested for ionic conductivity A2 using the same test method as for ionic conductivity A1.

[0109] Comparative Example 2

[0110] A solid electrolyte membrane, the preparation method of which comprises the following steps:

[0111] In a glove box environment, Li 5.5 PS 4.5 Cl 1.5 The solid electrolyte and polytetrafluoroethylene were mixed and ball-milled in a mass ratio of 99.5:0.5, and the obtained powder was roller-pressed to obtain a solid electrolyte membrane.

[0112] The solid electrolyte membrane was cut into 10 mm diameter discs and allowed to stand for 60 minutes in the same glove box environment. The ionic conductivity A1 of the solid electrolyte membrane was then measured. The solid electrolyte membrane was then transferred to an air environment at 25°C and 50% relative humidity for 60 minutes. The membrane was then returned to the glove box and tested for ionic conductivity A2 using the same test method as for ionic conductivity A1.

[0113] Comparative Example 3

[0114] A solid electrolyte membrane, the preparation method of which comprises the following steps:

[0115] In a glove box environment, Li 10 GeP2S 12 The mixture was mixed with polytetrafluoroethylene in a mass ratio of 99.5:0.5 and ball-milled, and the obtained powder was roller-pressed to obtain a solid electrolyte membrane.

[0116] The solid electrolyte membrane was cut into 10 mm diameter discs and allowed to stand for 60 minutes in the same glove box environment. The ionic conductivity A1 of the solid electrolyte membrane was then measured. The solid electrolyte membrane was then transferred to an air environment at 25°C and 50% relative humidity for 60 minutes. The membrane was then returned to the glove box and tested for ionic conductivity A2 using the same test method as for ionic conductivity A1.

[0117] Comparative Example 4

[0118] A solid electrolyte membrane, the preparation method of which comprises the following steps:

[0119] (1) Li 5.5 PS 4.5 Cl 1.5 Place it in a sealed reaction vessel, then introduce dry compressed air with a carbon dioxide content of 0.04% and control the gas flow rate to 100 cm 3 / min, then maintain the temperature at 25°C for 3h to obtain a mixture;

[0120] (2) The mixture and polytetrafluoroethylene were mixed and ball-milled in a mass ratio of 99.5:0.5, and the obtained powder was roller-pressed to obtain a solid electrolyte membrane.

[0121] The solid electrolyte membrane was cut into 10 mm diameter discs and allowed to stand for 60 minutes in the same glove box environment. The ionic conductivity A1 of the solid electrolyte membrane was then measured. The solid electrolyte membrane was then transferred to an air environment at 25°C and 50% relative humidity for 60 minutes. The membrane was then returned to the glove box and tested for ionic conductivity A2 using the same test method as for ionic conductivity A1.

[0122] The solid electrolyte membranes in the examples and comparative examples were used to prepare all-solid-state secondary batteries, wherein the positive electrode was prepared by using commercially available LiNi 0.8 Co 0.1 Mn 0.1 O2, Li6PS5Cl, vapor-phase carbon fiber, and polytetrafluoroethylene were ball-milled in a mass ratio of 70:28:8:1:0.2 and rolled to prepare the powder. Subsequently, the positive electrode sheet, solid electrolyte membrane, commercially available indium sheet, and commercially available lithium sheet were assembled in the order of assembly and pressed at a pressure of 50 MPa to obtain an all-solid-state secondary battery. The solid electrolyte membrane in each of the examples and comparative examples was allowed to stand for 60 minutes at 25°C with a water content of less than 0.1ppm and an oxygen content of less than 0.1ppm. The prepared all-solid-state secondary battery was designated S1. The solid electrolyte membrane in each of the examples and comparative examples was allowed to stand for 60 minutes in an air environment at 25°C and a relative humidity of 50%. The prepared all-solid-state secondary battery was designated S2. Both groups of batteries were subjected to constant current charge and discharge tests at 1.9-3.7V and 0.1C (1C = 200mA / g). The initial discharge specific capacity and the capacity retention rate after 100 cycles were calculated. The results are shown in Table 2.

[0123] Table 1 Parameter conditions of Examples 1-20 and Comparative Examples 1-4 and test results of A1 and A2

[0124] Table 2 Electrochemical test results of all-solid-state secondary batteries prepared using solid electrolyte membranes in Examples 1-20 and Comparative Examples 1-4

[0125] It can be clearly seen from the table that the solid electrolyte membranes prepared in each embodiment have ideal air stability and ionic conductivity, so that when the product is used in an all-solid-state secondary battery, rapid transmission of lithium ions can be achieved. At a rate of 0.1C, the first discharge specific capacity of the prepared all-solid-state secondary battery can reach more than 175mAh / g, and after 100 cycles, its capacity retention rate can still reach more than 85%. The solid electrolyte membrane prepared in Example 1 and the unmodified sulfide Li6PS5Cl electrolyte membrane were respectively subjected to XRD detection, and the control results are shown in Figure 1. It can be seen that the non-proton Lewis acid is not doped into the interior of the sulfide lattice, but is only coated on the surface of the sulfide. Moreover, even after standing in a humid environment, compared with comparative examples 1 to 3 for blank control, the solid electrolyte membrane prepared in each embodiment can still reach an initial discharge capacity of more than 175 mAh / g when used, and the capacity difference before standing is no more than 10 mAh / g, and the capacity retention rate can be maintained at more than 75%, indicating that the product is less restricted by the production environment and can be effectively used in the integrated production of all-solid-state secondary batteries. According to each embodiment, it can also be seen that with the coating of the aprotic Lewis acid, the ionic conductivity of the prepared solid electrolyte membrane decreases to a certain extent compared to the control sulfide solid electrolyte membrane without the introduction of the aprotic Lewis acid, and increases with the increase of the coating amount. However, the change in the ionic conductivity of the sulfide solid electrolyte membrane before and after coating is less than 1 mS / cm. When the product is used, the initial discharge capacity and cycle stability of the secondary battery are better, indicating that the aprotic Lewis acid coating layer can improve the air stability of the sulfide solid electrolyte and maintain the high ionic conductivity of the sulfide solid electrolyte itself. In contrast, the non-proton Lewis acid used in the products of Example 15, Example 17, Example 19 and Example 20 cannot completely inhibit the reactivity of the alkaline sites of the sulfide. When exposed to a hot and humid environment and applied to an all-solid-state battery, not only does its first discharge specific capacity decrease to a certain extent, but the capacity retention rate also decreases to a certain extent. For the products of Example 16 and Example 18, due to the large amount of coating of the non-proton Lewis acid, when it is applied to an all-solid-state secondary battery, the first discharge specific capacity of the secondary battery decreases. Comparative Example 4 is a modified product in which carbonate is used to coat the sulfide. It can be seen that compared with the blank control group, the air stability of the product is improved to a certain extent, but the degree of improvement is very limited. After the product is subjected to hot and humid conditions and then applied to an all-solid-state secondary battery, the first discharge specific capacity shown by the all-solid-state battery is low, and the capacity retention rate after 100 cycles is not as good as that of the products of each embodiment.

Claims

1. A solid electrolyte membrane, comprising a sulfide solid electrolyte and a coating layer arranged on the surface of the sulfide solid electrolyte; The coating layer comprises a non-protonic Lewis acid; The solid electrolyte membrane satisfies: A1-A2≤1 and A1≥1.5; Wherein A1 is the ionic conductivity of the solid electrolyte membrane in an environment of 25°C, water content <0.1ppm, and oxygen content <0.1ppm for 60 minutes, and the unit is mS / cm; A2 is the ionic conductivity of the solid electrolyte membrane in an air environment of 25°C and 50% relative humidity for 60 minutes, and the unit is mS / cm.

2. The solid electrolyte membrane according to claim 1, wherein: The non-protonic Lewis acid includes at least one of boron halide, aluminum halide, iron halide, copper halide, cobalt halide, zinc halide, titanium halide, zirconium halide, niobium halide, Al(CH3)3, p-benzoquinone, 1,4-naphthoquinone, 9,10-phenanthrenequinone, and 9,10-anthraquinone.

3. The solid electrolyte membrane according to claim 2, wherein: The non-protonic Lewis acid includes at least one of boron halide, aluminum halide, iron halide, copper halide, cobalt halide, zinc halide, titanium halide, zirconium halide, niobium halide, and Al(CH3)3.

4. The solid electrolyte membrane according to claim 1, wherein: The mass content of the non-proton Lewis acid in the sulfide solid electrolyte is 1-4 wt%.

5. The solid electrolyte membrane according to claim 4, wherein: The non-proton Lewis acid comprises aluminum halide, and the mass content of the aluminum halide in the sulfide solid electrolyte is 1 to 3 wt%.

6. The solid electrolyte membrane according to claim 1, wherein: The general formula of the sulfide solid electrolyte is Li x A y B z , wherein A includes one or two of Ge, Sn, and P, B includes one or two of S and Cl, 3≤x≤10, 1≤y≤3, 0≤z≤12.

7. The solid electrolyte membrane according to claim 1, wherein: The sulfide solid electrolyte includes Li 10 GeP2S 12 、Li7P3S 11 、Li6PS5Cl、Li 5.5 PS 4.5 Cl 1.5 , Li 10 SnP2S 12 , Li3PS4 or at least one of the following.

8. The solid electrolyte membrane according to claim 1, wherein: The range of A1 is: 1.5mS / cm≤A1≤9mS / cm.

9. The solid electrolyte membrane according to claim 1, wherein: The range of A2 is: 1mS / cm≤ A2≤8.6mS / cm.

10. The method for preparing a solid electrolyte membrane according to any one of claims 1 to 9, comprising the following steps: The non-proton Lewis acid, sulfide solid electrolyte and binder are dispersed and mixed in a solvent to prepare slurry, coated and dried to obtain a solid electrolyte membrane.

11. The method for preparing a solid electrolyte membrane according to any one of claims 1 to 9, comprising the following steps: The non-proton Lewis acid, sulfide solid electrolyte and binder are dispersed and mixed, and then rolled to obtain a solid electrolyte membrane.

12. A solid-state battery comprising the solid electrolyte membrane according to any one of claims 1 to 9.

13. An electrical device, comprising the solid-state battery according to claim 12, wherein the solid-state battery serves as a power supply for the electrical device.

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