Air-stable sulfide solid-state electrolytes and methods of making the same

Abstract

This application belongs to the field of lithium-ion battery technology, and specifically discloses an air-stable solid electrolyte. The solid electrolyte includes a core and a hydrophobic layer coating the surface of the core. The core comprises sulfide particles, and the thickness of the hydrophobic layer is 5–30 nm. The solid electrolyte according to the embodiments of this application has a surface-coated hydrophobic layer with low surface activity, exhibiting strong air stability and enabling the fabrication of solid-state batteries with excellent battery performance.

Description

Technical Field

[0001] This application relates to the field of all-solid-state lithium-ion battery technology, specifically to an air-stabilized sulfide solid electrolyte and its preparation method. More specifically, it relates to a solid-state battery and an electronic device. Background Technology

[0002] With the wider application of lithium batteries in daily life and the widespread adoption of new energy vehicles, improving the safety and energy density of lithium batteries has become an urgent priority. Traditional organic electrolytes are flammable, explosive, and prone to leakage, posing significant safety hazards to lithium batteries. Replacing organic electrolytes with solid-state electrolytes holds the promise of fundamentally solving these battery safety risks. Among various solid-state electrolytes, sulfide electrolytes are considered the most promising solid-state electrolyte materials due to their excellent mechanical ductility and high ionic conductivity.

[0003] However, the biggest drawback of sulfide solid electrolytes is their poor air stability. They decompose with water to produce hydrogen sulfide gas, leading to material failure, or their ionic conductivity decreases due to environmental influences during long-term storage. Therefore, their preparation, use, and storage are greatly affected by environmental conditions, which limits their large-scale production and application, and has become a key technical challenge restricting the development of this field.

[0004] Therefore, there is an urgent need to develop air-stable sulfide solid electrolytes to improve the performance of solid-state batteries. Summary of the Invention

[0005] This application aims to at least partially address one of the technical problems existing in the prior art. To this end, this application provides a sulfide solid electrolyte.

[0006] The first aspect of this application discloses a solid-state electrolyte. According to an embodiment of this application, the solid-state electrolyte includes a core and a hydrophobic layer encapsulating the surface of the core. The core comprises sulfide particles, and the thickness of the hydrophobic layer is 5-30 nm. The solid-state electrolyte according to the embodiment of this application, with its surface encapsulated in a hydrophobic layer having low surface activity, exhibits strong air stability and can be used to fabricate solid-state batteries with excellent battery performance.

[0007] In some embodiments, the thickness of the hydrophobic layer is 8~20 nm.

[0008] In some embodiments, the hydrophobic layer comprises a long-chain hydrophobic polymer.

[0009] In some embodiments, the long-chain hydrophobic polymer is selected from at least one of polytrifluoropropylmethylsiloxane, polydimethylsiloxane, polyacrylic acid, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, methylcellulose, ethylcellulose, hydroxyethyl methacrylate, dodecyl methacrylate, fluoroalkyl acrylate, and silylalkyl methacrylate.

[0010] In some embodiments, the long-chain hydrophobic polymer includes at least one functional group selected from -F, -CF, -Si-O-Si-, -Si-C-, -CO-, -Si-O-, and -C-Si-O-.

[0011] In some embodiments, the long-chain hydrophobic polymer includes at least one functional group selected from -F, -CF, -Si-O-Si, and -C-Si-O-.

[0012] In some embodiments, the sulfide particles are selected from Li2SiS3, Li2SnS3, Li3PS4, and Li 5.5 PS 4.5 Cl 1.5 Li 5.5 PS 4.5 Cl 0.8 Br 0.7 Li7PS6, Li7P3S 11 Li6PS5Cl, Li6PS5Br, Li 10 GeP2S 12 and Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 At least one of them.

[0013] In some embodiments, the particle size distribution D of the sulfide particles 50 The range is from 0.2 μm to 30 μm.

[0014] In some embodiments, the ionic conductivity retention rate of the sulfide solid electrolyte is ≥90%.

[0015] In some embodiments, the ionic conductivity retention rate of the sulfide solid electrolyte is ≥95%.

[0016] The second aspect of this application discloses a method for preparing the solid electrolyte described in the first aspect of this application. According to an embodiment of this application, the method includes: mixing a solid electrolyte core material with a solid electrolyte hydrophobic layer material to obtain the solid electrolyte, wherein the solid electrolyte includes the core and a hydrophobic layer coating the surface of the core, the core comprising sulfide particles, and the thickness of the hydrophobic layer being 5-30 nm. The method according to the embodiment of this application can prepare a solid electrolyte with strong air stability. The method according to the embodiment of this application is applicable to sulfide solid electrolytes of various particle sizes and morphologies, and requires no expensive equipment or cumbersome processes, allowing for scalable mass production applications. Applying the prepared sulfide solid electrolyte to solid-state batteries can produce solid-state batteries with superior performance, meeting the requirements for high-energy-density all-solid-state batteries, and demonstrating good application prospects in all aspects.

[0017] In some embodiments, the solid electrolyte hydrophobic layer material comprises a long-chain hydrophobic polymer.

[0018] In some embodiments, the mixing process includes: performing a first mixing process on the solid electrolyte hydrophobic layer material and a first solvent; performing a second mixing process on the first mixing product and a second solvent; and performing a third mixing process on the second mixing product and the solid electrolyte core material.

[0019] In some embodiments, the first solvent is selected from at least one of hexafluoroisopropanol, 1-bromopentane, polyethylene glycol dimethyl ether, and trifluoroacetic acid.

[0020] In some embodiments, the second solvent is selected from at least one of n-hexane, n-heptane, n-decane, n-butyl ether, anhydrous xylene, toluene, anisole, dibromomethane, and butyl butyrate.

[0021] In some embodiments, the first mixing treatment is carried out for 5 to 15 hours at a rotation speed of 500 to 700 r / min and a temperature of 40 to 80°C.

[0022] In some embodiments, the mass ratio of the solid electrolyte hydrophobic layer material to the first solvent is (0.1~3):(0.5~20).

[0023] In some embodiments, the second mixing treatment is carried out for 0.5 to 10 hours at a rotation speed of 300 to 1000 r / min and a temperature of 25 to 60°C.

[0024] In some embodiments, the mass ratio of the first mixed product to the second solvent is (0.5~3):(1~5).

[0025] In some embodiments, the third mixing treatment is carried out for 0.5 to 10 hours at a rotation speed of 300 to 500 r / min and a temperature of 25 to 60°C.

[0026] In some embodiments, the mass ratio of the solid electrolyte core material to the second mixed treatment product is (0.5~3):(1~10).

[0027] In some embodiments, the third mixing process is followed by drying the product of the third mixing process.

[0028] In some embodiments, the drying process is carried out at a temperature of 60~200°C and in an oven atmosphere of vacuum or inert gas for 2~20 hours.

[0029] The third aspect of this application proposes the application of the solid electrolyte described in the first aspect of this application or the solid electrolyte prepared by the method described in the second aspect of this application in all-solid-state lithium batteries.

[0030] A fourth aspect of this application discloses a solid-state battery. According to an embodiment of this application, the solid-state battery includes a positive electrode, a negative electrode, and a solid-state electrolyte as described in the first aspect of this application or prepared by the method described in the second aspect of this application.

[0031] A fifth aspect of this application discloses an electronic device. According to an embodiment of this application, the electronic device includes the solid-state battery described in the fourth aspect of this application.

[0032] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0033] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0034] Figure 1 The XRD diffraction pattern is shown for the sulfide solid electrolyte material obtained in Example 1 of this application.

[0035] Figure 2 This is a comparison chart showing the first charge-discharge specific capacity performance of all-solid-state lithium batteries assembled from sulfide solid electrolyte materials obtained in Example 1 and Comparative Example 1 of this application.

[0036] Figure 3 This is a comparison chart showing the rate performance of all-solid-state lithium batteries assembled from sulfide solid electrolyte materials obtained in Example 1 and Comparative Example 1 of this application.

[0037] Figure 4This is a comparison chart of the cycle performance of all-solid-state lithium batteries assembled from the sulfide solid electrolyte material obtained in Example 1 of this application. Detailed Implementation

[0038] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0039] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0040] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0041] In the description of this application, it should be understood that the terms "width", "thickness", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0042] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.

[0043] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0044] In the description of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0045] In the description of this application, "multiple" means two or more.

[0046] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0047] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0048] Existing technologies develop air-stable sulfide solid electrolytes using elemental doping. However, this method has limitations: the introduction of dopant elements reduces the ionic conductivity of the electrolyte material, and some dopants contain highly toxic elements (such as arsenic, as), which can affect the health of operators. Besides elemental doping, surface coating modification methods are also used. However, these methods involve complex processes requiring high-temperature sintering or atomic layer deposition (ALD), increasing energy consumption or requiring expensive equipment, which is not conducive to large-scale production applications.

[0049] Based on this, the first aspect of this application proposes a solid-state electrolyte. According to an embodiment of this application, the solid-state electrolyte includes a core and a hydrophobic layer encapsulating the surface of the core. The core comprises sulfide particles, and the thickness of the hydrophobic layer is 5-30 nm, for example, it can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, and 30 nm, or a range between these values ​​of 6-30 nm and 7-30 nm. The solid-state electrolyte according to the embodiment of this application, with its surface encapsulated in a hydrophobic layer having low surface activity, exhibits strong air stability and can be used to fabricate solid-state batteries with excellent battery performance. A moderate thickness of the hydrophobic layer is beneficial for the preparation of solid electrolytes. If the hydrophobic layer is too thick, it will result in low ionic conductivity. If the hydrophobic layer is too thin, it will result in uneven coating and will not be able to protect the solid electrolyte.

[0050] According to an embodiment of this application, the thickness of the hydrophobic layer is 8~20 nm.

[0051] According to embodiments of this application, the hydrophobic layer comprises a long-chain hydrophobic polymer.

[0052] According to embodiments of this application, the long-chain hydrophobic polymer is selected from at least one of polytrifluoropropylmethylsiloxane (PTFPMS), polydimethylsiloxane (PDMS), polyacrylic acid (PAA), 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES), methylcellulose, ethylcellulose, hydroxyethyl methacrylate, dodecyl methacrylate, fluoroalkyl acrylate, and silylalkyl methacrylate.

[0053] According to embodiments of this application, the long-chain hydrophobic polymer includes, but is not limited to, at least one of the functional groups selected from -F, -CF, -Si-O-Si-, -Si-C-, -CO-, -Si-O-, and -C-Si-O-, and the long-chain polymer is obtained through a polycondensation reaction between polymers.

[0054] According to embodiments of this application, the long-chain hydrophobic polymer includes at least one functional group selected from -F, -CF, -Si-O-Si, and -C-Si-O-.

[0055] According to embodiments of this application, the sulfide particles are selected from Li2SiS3, Li2SnS3, Li3PS4, and Li 5.5 PS 4.5 Cl 1.5 Li 5.5 PS 4.5 Cl0.8 Br 0.7 Li7PS6, Li7P3S 11 Li6PS5Cl, Li6PS5Br, Li 10 GeP2S 12 and Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 At least one of them.

[0056] According to an embodiment of this application, the particle size distribution D of the sulfide particles is... 50 The value can be 0.2μm to 30μm, for example, it can be 0.2μm, 1μm, 3μm, 5μm, 7μm, 9μm, 11μm, 13μm, 15μm, 17μm, 19μm, 21μm, 23μm, 25μm, 27μm, 29μm, 30μm or a range between the two, such as 1μm to 30μm or 3μm to 30μm.

[0057] According to an embodiment of this application, the solid electrolyte has a dew point of -10°C and is left to stand for 24 hours.

[0058] According to an embodiment of this application, the ionic conductivity retention rate of the solid electrolyte is ≥90%. It should be explained that the solid electrolyte is exposed to a humid environment and left to stand for a period of time. The ionic conductivity before and after standing is measured. The ionic conductivity retention rate refers to the ionic conductivity after exposure divided by the ionic conductivity before exposure.

[0059] According to an embodiment of this application, the ionic conductivity retention rate of the solid electrolyte is ≥95%.

[0060] A second aspect of this application discloses a method for preparing the solid electrolyte described in the first aspect of this application. According to an embodiment of this application, the method includes: mixing a solid electrolyte core material with a solid electrolyte hydrophobic layer material to obtain the solid electrolyte, wherein the solid electrolyte includes the core and a hydrophobic layer coating the surface of the core, the core comprising sulfide particles, and the hydrophobic layer having a thickness of 5-30 nm. The method according to the embodiment of this application can prepare a solid electrolyte with strong air stability.

[0061] According to embodiments of this application, the solid electrolyte hydrophobic layer material comprises a long-chain hydrophobic polymer.

[0062] According to embodiments of this application, the long-chain hydrophobic polymer is selected from at least one of polytrifluoropropylmethylsiloxane (PTFPMS), polydimethylsiloxane (PDMS), polyacrylic acid (PAA), 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES), methylcellulose, ethylcellulose, hydroxyethyl methacrylate, dodecyl methacrylate, fluoroalkyl acrylate, and silylalkyl methacrylate.

[0063] According to an embodiment of this application, the mixing process includes: performing a first mixing process on the solid electrolyte hydrophobic layer material and a first solvent; performing a second mixing process on the first mixing product and a second solvent; and performing a third mixing process on the second mixing product and the solid electrolyte core material.

[0064] According to embodiments of this application, the first solvent is selected from at least one of hexafluoroisopropanol, 1-bromopentane, polyethylene glycol dimethyl ether, and trifluoroacetic acid.

[0065] According to embodiments of this application, the second solvent is selected from at least one of n-hexane, n-heptane, n-decane, n-butyl ether, anhydrous xylene, toluene, anisole, dibromomethane, and butyl butyrate.

[0066] According to an embodiment of this application, the first mixing process is carried out for 5 to 15 hours at a rotation speed of 500 to 700 r / min and a temperature of 40 to 80°C.

[0067] According to an embodiment of this application, the mass ratio of the solid electrolyte hydrophobic layer material to the first solvent is (0.1~3):(0.5~20).

[0068] According to an embodiment of this application, the second mixing process is carried out for 0.5 to 10 hours at a rotation speed of 300 to 1000 r / min and a temperature of 25 to 60°C.

[0069] According to an embodiment of this application, the mass ratio of the first mixed treatment product to the second solvent is (0.5~3):(1~5).

[0070] According to an embodiment of this application, the third mixing treatment is carried out for 0.5 to 10 hours at a rotation speed of 300 to 500 r / min and a temperature of 25 to 60°C.

[0071] According to an embodiment of this application, the mass ratio of the solid electrolyte core material to the second mixed treatment product is (0.5~3):(1~10).

[0072] According to an embodiment of this application, the mass ratio of the solid electrolyte core material to the second mixed treatment product is (0.8~2):(2~6).

[0073] According to an embodiment of this application, after the third mixing treatment, the product of the third mixing treatment is further subjected to a drying treatment.

[0074] According to an embodiment of this application, the drying process is carried out for 2 to 20 hours at a temperature of 60 to 200°C and in an oven atmosphere of vacuum or inert gas.

[0075] According to an embodiment of this application, the drying process is carried out at a temperature of 100~150°C and in an oven atmosphere of vacuum or inert gas for 5~15 hours.

[0076] The third aspect of this application proposes the application of the solid electrolyte described in the first aspect of this application or the solid electrolyte prepared by the method described in the second aspect of this application in all-solid-state lithium batteries.

[0077] The fourth aspect of this application proposes a solid-state battery. According to an embodiment of this application, the solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte as described in the first aspect of this application or prepared by the method described in the second aspect of this application. According to the embodiments of this application, it should be explained that "solid-state battery" includes all-solid-state batteries and batteries containing a certain proportion of liquid electrolyte, such as semi-solid-state batteries and quasi-solid-state batteries. Specifically, all-solid-state batteries do not contain any liquid electrolyte; all electrolytes are solid. Such batteries generally have higher safety because solid electrolytes are non-flammable and can suppress the growth of lithium dendrites, thereby reducing the risk of short circuits. Furthermore, all-solid-state batteries generally have higher energy density because metallic lithium can be used as the negative electrode material, thus achieving higher energy density. All-solid-state batteries have long cycle life, a wide operating temperature range, and better mechanical strength and stability. Semi-solid-state batteries contain a small amount of liquid electrolyte, typically around 5-10% by mass. Semi-solid-state batteries maintain a certain high ion transport rate compared to liquid batteries while improving safety, representing a transitional technology between traditional liquid lithium batteries and all-solid-state batteries. Quasi-solid-state batteries refer to batteries with a liquid electrolyte percentage of less than 5% by mass. These batteries have a higher solid electrolyte content and less liquid electrolyte, resulting in better safety than semi-solid-state batteries, but still not as good as all-solid-state batteries. The solid-state battery according to the embodiments of this application improves battery performance.

[0078] A fifth aspect of this application discloses an electronic device. According to an embodiment of this application, the electronic device includes the solid-state battery described in the fourth aspect of this application.

[0079] Compared with the prior art, the advantages of this application are as follows:

[0080] First, the air-stable solid electrolyte material provided in this application has a hydrophobic layer that is tightly bonded to the solid electrolyte via in-situ polymerization, making the hydrophobic layer difficult to detach. This solid electrolyte not only has strong environmental adaptability but also high ionic conductivity; its coating method is applicable to solid electrolytes of various particle sizes and morphologies. Composite electrode sheets and ultrathin solid electrolyte films prepared using this solid electrolyte have excellent surface smoothness, and the assembled solid-state batteries also exhibit high discharge specific capacity, rate performance, and cycle stability.

[0081] Secondly, the method for preparing air-stable solid electrolyte materials provided in this application does not require expensive equipment, the steps are simple and easy to implement, and it can be scaled up for mass production applications. That is, by controlling the mass ratio of polymer, first solvent, second solvent and solid electrolyte, the drying temperature ratio and related parameters, a hydrophobic coating with controllable thickness can be obtained on the surface of solid electrolyte, thereby improving the environmental adaptability of solid electrolyte and having good prospects for practical industrial applications.

[0082] Finally, the preparation method provided in this application is suitable for small-particle-size solid electrolytes, and the obtained nanoscale air-stable solid electrolyte material is used to assemble an all-solid-state lithium battery. Due to the improved air stability of the small-particle-size solid electrolyte, the full battery has a high discharge specific capacity and rate performance.

[0083] This application can improve the shortcomings of existing solid electrolyte materials for all-solid-state lithium batteries, enhance air stability, and has a universal preparation method, enabling solid electrolytes to be better applied in all-solid-state lithium batteries. At the same time, it also has good prospects for industrial application.

[0084] The following will explain the solution of this application with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0085] Example 1

[0086] This embodiment provides a solid electrolyte and its preparation method, wherein the solid electrolyte contains sulfide particles Li 5.5 PS 4.5 Cl 1.5 , particle size distribution of sulfide particles D 50 The wavelength is 680 nm, and the ionic conductivity σ is 7.42 mS / cm. -1After standing at -10℃ dew point for 24 h, the ionic conductivity was retained at 95%, and the hydrophobic layer thickness was 10 nm. The specific preparation process includes the following steps:

[0087] The polymer is PTFPMS, the first solvent is 1-bromopentane, and the second solvent is n-heptane. First, PTFPMS and 1-bromopentane are mixed at a mass ratio of 1:5 at 600 r / min and 50°C for 10 h to obtain a first mixed product. Then, the first mixed product and the second solvent n-heptane are mixed at a mass ratio of 0.5:3 at 400 r / min and 40°C for 5 h to obtain a second mixed product. The second mixed product is then combined with the Li... 5.5 PS 4.5 Cl 1.5 The third mixing process was carried out at a mass ratio of 0.5:2 at a rotation speed of 400 r / min and a temperature of 40℃ for 2 h to obtain the third mixing product. The final third mixing product was then vacuum dried at 120℃ for 10 h to obtain the final air-stable solid electrolyte.

[0088] Example 2

[0089] This embodiment provides a solid electrolyte and its preparation method, wherein the solid electrolyte contains sulfide particles Li 10 GeP2S 12 , particle size distribution of sulfide particles D 50 The wavelength is 620 nm, and the ionic conductivity σ is 6.86 mS / cm. -1 After standing at -10℃ dew point for 24 h, the ionic conductivity was retained at 92%, and the hydrophobic layer thickness was 15 nm. The specific preparation process includes the following steps:

[0090] The polymer is PDMS, the first solvent is polyethylene glycol dimethyl ether, and the second solvent is n-butyl ether. First, PDMS and polyethylene glycol dimethyl ether are mixed at a mass ratio of 1:8 at a rotation speed of 650 r / min and a temperature of 60°C for 12 hours to obtain a first mixed product. Then, the first mixed product and the second solvent n-butyl ether are mixed at a mass ratio of 1:5 at a rotation speed of 500 r / min and a temperature of 30°C for 8 hours to obtain a second mixed product. The second mixed product is then mixed with the Li... 10 GeP2S 12 The third mixing process was carried out at a mass ratio of 1:3, a rotation speed of 300 r / min, and a temperature of 45℃ for 5 h to obtain the third mixing product. The final third mixing product was then vacuum dried at 130℃ for 12 h to obtain the final air-stable solid electrolyte.

[0091] Example 3

[0092] This embodiment provides a solid electrolyte and its preparation method, wherein the solid electrolyte contains sulfide particles Li6PS5Cl, and the particle size distribution D of the sulfide particles is... 50 The nanometer diameter is 3 μm, and the ionic conductivity σ is 3.12 mS / cm. -1 After standing at -10℃ dew point for 24 h, the ionic conductivity was retained at 93%, and the hydrophobic layer thickness was 12 nm. The specific preparation process includes the following steps:

[0093] The polymer is PAA, the first solvent is hexafluoroisopropanol, and the second solvent is toluene. First, PAA and hexafluoroisopropanol are mixed at a mass ratio of 1:3 at 580 r / min and 55 °C for 15 h to obtain a first mixed product. Then, the first mixed product and toluene are mixed at a mass ratio of 1:4 at 500 r / min and 45 °C for 5 h to obtain a second mixed product. The second mixed product is then mixed with Li6PS5Cl at a mass ratio of 2:3 at 450 r / min and 30 °C for 4 h to obtain a third mixed product. Finally, the third mixed product is vacuum dried at 110 °C for 8 h to obtain the final air-stable solid electrolyte.

[0094] Example 4

[0095] This embodiment provides a solid electrolyte and its preparation method, wherein the solid electrolyte contains sulfide particles Li7P3S. 11 , particle size distribution of sulfide particles D 50 The diameter is 5 μm, and the ionic conductivity σ is 2.42 mS / cm. -1 After standing at -10℃ dew point for 24 h, the ionic conductivity was retained at 91%, and the hydrophobic layer thickness was 10 nm. The specific preparation process includes the following steps:

[0096] The polymer is PFDTES, the first solvent is hexafluoroisopropanol, and the second solvent is butyl butyrate. First, PFDTES and hexafluoroisopropanol are mixed at a mass ratio of 0.5:2 at 600 r / min and 50 °C for 13 h to obtain a first mixed product. Then, the first mixed product and the second solvent, butyl butyrate, are mixed at a mass ratio of 1:5 at 500 r / min and 40 °C for 8 h to obtain a second mixed product. The second mixed product is then mixed with the Li7P3S... 11The third mixing process was carried out at a mass ratio of 2:5, a rotation speed of 500 r / min, and a temperature of 55℃ for 6 h to obtain the third mixing product. The final third mixing product was then vacuum dried at 100 ℃ for 10 h to obtain the final air-stable solid electrolyte.

[0097] Example 5

[0098] This embodiment provides a solid electrolyte and its preparation method, wherein the solid electrolyte contains sulfide particles Li 5.5 PS 4.5 Cl 0.8 Br 0.7 , particle size distribution of sulfide particles D 50 The diameter is 2 μm, and the ionic conductivity σ is 8.42 mS / cm. -1 After standing at -10℃ dew point for 24 h, the ionic conductivity was retained at 94%, and the hydrophobic layer thickness was 8 nm. The specific preparation process includes the following steps:

[0099] The polymer is PTFPMS, the first solvent is hexafluoroisopropanol, and the second solvent is n-hexane. First, PTFPMS and hexafluoroisopropanol are mixed at a mass ratio of 1:3 at 700 r / min and 60°C for 10 h to obtain a first mixed product. Then, the first mixed product and the second solvent n-hexane are mixed at a mass ratio of 1:3 at 500 r / min and 40°C for 5 h to obtain a second mixed product. The second mixed product is then mixed with the Li... 5.5 PS 4.5 Cl 0.8 Br 0.7 The third mixing process was carried out at a mass ratio of 1:3, a rotation speed of 350 r / min, and a temperature of 50 °C for 3 h to obtain the third mixing product. The final third mixing product was then vacuum dried at 100 °C for 5 h to obtain the final air-stable solid electrolyte.

[0100] Example 6

[0101] The same method as in Example 1 was used for preparation, except that the polymer PTFPMS and the first solvent 1-bromopentane were mixed at a mass ratio of 3:0.5, and the other processes were the same as in Example 1.

[0102] Example 7

[0103] The same method as in Example 1 was used for preparation, except that the polymer PTFPMS and the first solvent 1-bromopentane were mixed at a mass ratio of 0.1:20, and the other processes were the same as in Example 1.

[0104] Example 8

[0105] The same method as in Example 1 was used for preparation, except that the polymer PTFPMS and the first solvent 1-bromopentane were mixed at a mass ratio of 4:0.5, and the other processes were the same as in Example 1.

[0106] Example 9

[0107] The same method as in Example 1 was used for preparation, except that the polymer PTFPMS and the first solvent 1-bromopentane were mixed at a mass ratio of 0.1:21, and the other processes were the same as in Example 1.

[0108] Example 10

[0109] The preparation was carried out using the same method as in Example 1, except that the solid electrolyte core material and the second mixed treatment product were mixed at a mass ratio of 0.5:10, and the other processes were the same as in Example 1.

[0110] Example 11

[0111] The preparation was carried out using the same method as in Example 1, except that the solid electrolyte core material and the second mixed treatment product were mixed at a mass ratio of 3:1, and the other processes were the same as in Example 1.

[0112] Example 12

[0113] The preparation was carried out using the same method as in Example 1, except that the solid electrolyte core material and the second mixed treatment product were mixed at a mass ratio of 0.4:10, while the other processes were the same as in Example 1.

[0114] Example 13

[0115] The preparation was carried out using the same method as in Example 1, except that the solid electrolyte core material and the second mixed treatment product were mixed at a mass ratio of 4:1, and the other processes were the same as in Example 1.

[0116] Example 14

[0117] The same method as in Example 1 was used for preparation, except that the drying temperature was 200°C, while the other processes were the same as in Example 1.

[0118] Example 15

[0119] The same method as in Example 1 was used for preparation, except that the drying temperature was 60°C, while the other processes were the same as in Example 1.

[0120] Example 16

[0121] The same method as in Example 1 was used for preparation, except that the drying temperature was 210°C, and the other processes were the same as in Example 1.

[0122] Example 17

[0123] The same method as in Example 1 was used for preparation, except that the drying temperature was 50°C, while the other processes were the same as in Example 1.

[0124] Example 18

[0125] The same method as in Example 1 was used for preparation, except that the polymer was polydimethylsiloxane, and the other processes were the same as in Example 1.

[0126] Example 19

[0127] The same method as in Example 1 was used for preparation, except that the polymer was polyvinyl alcohol, and the other processes were the same as in Example 1.

[0128] Example 20

[0129] The preparation was carried out using the same method as in Example 1, except that the first solvent was polyethylene glycol dimethyl ether, and the other processes were the same as in Example 1.

[0130] Example 21

[0131] The preparation was carried out using the same method as in Example 1, except that the first solvent was tetrahydrofuran, and the other processes were the same as in Example 1.

[0132] Example 22

[0133] The preparation was carried out using the same method as in Example 1, except that the second solvent was n-hexane, and the other processes were the same as in Example 1.

[0134] Example 23

[0135] The preparation was carried out using the same method as in Example 1, except that the second solvent was dichloromethane, and the other processes were the same as in Example 1.

[0136] Example 24

[0137] The same method as in Example 1 was used for preparation, except that the thickness of the hydrophobic layer was 5 nm, and the other processes were the same as in Example 1.

[0138] Example 25

[0139] The same method as in Example 1 was used for preparation, except that the thickness of the hydrophobic layer was 30 nm, and the other processes were the same as in Example 1.

[0140] Comparative Example 1

[0141] The experimental process of this comparative example is basically the same as that of Example 1. The same sulfide solid electrolyte material as in Example 1 is used. The difference is that the polymer PTFPMS and the first solvent 1-bromopentane are not added. The other processes are the same as in Example 1.

[0142] Comparative Example 2

[0143] The experimental process of this comparative example is basically the same as that of Example 1, except that the polymer PTFPMS is not added, while the other processes are the same as in Example 1.

[0144] Comparative Example 3

[0145] The experimental process of this comparative example is basically the same as that of Example 1, except that the thickness of the hydrophobic layer is 4 nm, and the other processes are the same as those in Example 1.

[0146] Comparative Example 4

[0147] The experimental process of this comparative example is basically the same as that of Example 1, except that the thickness of the hydrophobic layer is 31 nm, and the other processes are the same as those in Example 1.

[0148] Test case

[0149] XRD Experiment: First, the sulfide electrolyte powder was placed into a custom mold, then sealed with adhesive to prevent air contact. Finally, the prepared sample was placed in an XRD analyzer for testing. The XRD diffraction pattern of the sulfide solid electrolyte material obtained in Example 1 is shown below. Figure 1 As shown.

[0150] Ionic conductivity test: Weigh 150 mg of sulfide solid electrolyte material from Examples 1-25 and Comparative Examples 1-4, place it in a mold with an inner diameter of 10 mm, press it down with stainless steel current collectors from top to bottom, apply a pressure of 370 MPa for 5 min, and perform AC impedance test at 25°C using an electrochemical workstation. The amplitude of the AC current is 15 mV, and the frequency range is 0.01 Hz to 1 MHz.

[0151] Humid air stability test of solid electrolyte materials: The sulfide solid electrolytes from Examples 1-25 and Comparative Examples 1-4 were subjected to humid air stability tests. In a glove box, 300 mg of the solid electrolyte material was weighed and placed into a 5 mL open glass bottle. The bottle was then placed in a reaction chamber with a specific humidity airflow and allowed to stand at room temperature. The relative humidity of the humid air was 10% (approximately equal to the dew point of -10°C), and the air flow rate was 100 mL / min. Samples were taken after 24 hours for ion conductance testing.

[0152] Assembly of the solid-state lithium battery: The solid-state lithium battery consists of a high-nickel positive electrode material, a lithium-indium alloy negative electrode, and a sulfide solid electrolyte material prepared in Examples 1-25 or Comparative Examples 1-4. The specific assembly process is as follows: First, 100 mg of sulfide solid electrolyte is placed into a Φ10 mm mold and pressed into an intermediate layer under a pressure of 200 MPa; then, 10 mg of composite positive electrode material (composed of 7 mg of high-nickel positive electrode material and 3 mg of sulfide solid electrolyte) is added to one end of the intermediate layer and pressed into shape under a pressure of 200 MPa; finally, a certain amount of lithium-indium alloy negative electrode is added to the other end of the intermediate layer and assembled into an all-solid-state lithium battery under a pressure of 240 MPa.

[0153] Solid-state lithium battery testing: Test temperature 25℃, voltage range 2.6~4.4V vs. Li + / Li. The full cell at 0.1C (1C = 200 mA g). -1 The first-cycle charge-discharge capacity and coulombic efficiency were tested at a current density of 0.2C, 0.5C, 0.8C, 1C, 2C, and 3C; rate performance was tested at different current densities of 0.2C, 0.5C, 0.8C, 1C, 2C, and 3C; long-cycle performance was tested at a current density of 1C, and the number of cycles in which the capacity retention rate decayed to 80% was recorded. The comparison of the first-cycle charge-discharge specific capacity performance of the all-solid-state lithium battery assembled with the sulfide solid electrolyte material obtained in Example 1 and Comparative Example 1 is shown in the figure below. Figure 2 As shown in the figure, the rate performance comparison of all-solid-state lithium batteries assembled with sulfide solid electrolyte materials obtained in Example 1 and Comparative Example 1 is as follows. Figure 3 As shown in the figure, the cycle performance comparison of the all-solid-state lithium battery assembled with the sulfide solid electrolyte material obtained in Example 1 is as follows. Figure 4 As shown.

[0154] Table 1: Properties of sulfide solid electrolyte materials in Examples 1-25 and Comparative Examples 1-4

[0155]

[0156]

[0157] Table 2: Performance data of all-solid-state lithium batteries in Examples 1-25 and Comparative Examples 1-4

[0158]

[0159]

[0160] Analysis of the data in Tables 1 and 2 shows that the air-stabilized sulfide solid electrolyte material of this application exhibits high ionic conductivity and humid air stability. The preparation method is universally applicable. All-solid-state lithium batteries composed using this air-stabilized sulfide solid electrolyte material demonstrate excellent discharge specific capacity, high rate performance, and stable long-cycle performance. This is attributed to the presence of a hydrophobic layer with low surface activity coated on the surface of the sulfide electrolyte. This hydrophobic layer, after in-situ polymerization, is tightly bound to the sulfide solid electrolyte via bonding, thus providing hydrophobic properties.

[0161] Comparing Example 1 with Comparative Examples 1 and 2, it was found that the interface treatment significantly improved the humid air stability of the sulfide solid electrolyte, and the overall performance of the all-solid-state lithium battery was also significantly improved. This fully demonstrates that improving environmental adaptability is crucial to the overall performance of the all-solid-state battery.

[0162] Compared with Examples 1, 24, and 25 and Comparative Examples 3 and 4, it can be seen that the ionic conductivity retention rate of the solid electrolyte prepared with a hydrophobic layer of 5nm~30nm is improved, and the number of cycles in which the (1C) capacity retention rate of the prepared solid battery decays to 80% is increased.

[0163] Compared with Examples 1, 2, 3, 4 and 5, it can be seen that the surface coating materials of the sulfide solid electrolyte are different, but the process parameters of the preparation process are different. The material properties of the obtained sulfide solid electrolyte and the electrochemical performance of the assembled all-solid-state lithium battery are also slightly different. This shows that while obtaining an air-stable sulfide electrolyte, the performance of the all-solid-state lithium battery can be optimized by adjusting the preparation parameters and changing the surface coating material of the sulfide solid electrolyte.

[0164] Compared with Examples 1, 6, 7 and 8, 9, the solid electrolyte prepared with a polymer to 1-bromopentane mass ratio in the range of (0.1~3):(0.5~20) has improved ionic conductivity retention and the number of cycles required for the (1C) capacity retention of the prepared solid battery to decay to 80% is increased.

[0165] Compared with Examples 1, 10, 11 and 12, 13, the solid electrolyte prepared with a mass ratio of solid electrolyte core material to second mixed treatment product in the range of (0.5~3):(1~10) has improved ionic conductivity retention rate and increased number of cycles for the prepared solid battery to achieve (1C) capacity retention rate decay to 80%.

[0166] Compared with Examples 1, 14, 15 and 16, 17, the ionic conductivity retention rate of the solid electrolyte prepared in the drying temperature range of 60~200℃ is improved, and the number of cycles in which the (1C) capacity retention rate of the prepared solid battery decays to 80% is increased.

[0167] Compared with Examples 1, 18 and 19, the solid electrolyte prepared with polytrifluoropropylmethylsiloxane and polydimethylsiloxane as polymers has a higher ionic conductivity retention rate than that prepared with polyvinyl alcohol, and the number of cycles required for the (1C) capacity retention rate of the prepared solid battery to decay to 80% is increased.

[0168] Compared with Examples 1, 20 and 21, the solid electrolyte prepared with polyethylene glycol dimethyl ether and 1-bromopentane as the first solvent has a higher ionic conductivity retention rate than that prepared with tetrahydrofuran, and the solid battery prepared with these solvents has a higher number of cycles to achieve an 80% capacity retention rate at (1C).

[0169] Compared with Examples 1, 22 and 23, the solid electrolyte prepared with n-hexane and n-heptane as the second solvent has a higher ionic conductivity retention rate than that prepared with dichloromethane, and the solid battery prepared with n-hexane has a higher number of cycles to achieve an 80% capacity retention rate at (1C).

[0170] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0171] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for preparing a solid electrolyte, characterized in that, include: A solid electrolyte core material and a solid electrolyte hydrophobic layer material are mixed to obtain the solid electrolyte, which includes the core and a hydrophobic layer coating the surface of the core. The core comprises sulfide particles, and the hydrophobic layer has a thickness of 5-30 nm. The solid electrolyte hydrophobic layer material comprises a long-chain hydrophobic polymer selected from at least one of polyacrylic acid, methylcellulose, ethylcellulose, hydroxyethyl methacrylate, dodecyl methacrylate, and fluorinated alkyl acrylates. The mixing process includes: The solid electrolyte hydrophobic layer material is mixed with a first solvent in a first mixing process. The first mixture product is then subjected to a second mixture treatment with a second solvent. The second mixing product is then mixed with the solid electrolyte core material in a third mixing process. The first solvent is selected from at least one of hexafluoroisopropanol, 1-bromopentane, polyethylene glycol dimethyl ether, and trifluoroacetic acid; The second solvent is selected from at least one of n-hexane, n-heptane, n-decane, n-butyl ether, anhydrous xylene, toluene, anisole, dibromomethane, and butyl butyrate. in, The mass ratio of the solid electrolyte hydrophobic layer material to the first solvent is (0.1~3):(0.5~20). The mass ratio of the solid electrolyte core material to the second mixed treatment product is (0.5~3):(1~10). Following the third mixing process, the product of the third mixing process is further subjected to a drying process at a temperature of 60~200℃.

2. The method according to claim 1, characterized in that, The thickness of the hydrophobic layer is 8~20 nm.

3. The method according to claim 1, characterized in that, The long-chain hydrophobic polymer includes at least one functional group selected from -F, -CF, -Si-O-Si-, -Si-C-, -CO-, -Si-O-, and -C-Si-O-.

4. The method according to claim 1, characterized in that, The long-chain hydrophobic polymer includes at least one of the functional groups selected from -F, -CF, -Si-O-Si, and -C-Si-O-.

5. The method according to claim 1, characterized in that, The sulfide particles are selected from Li2SiS3, Li2SnS3, Li3PS4, and Li 5.5 PS 4.5 Cl 1.5 Li 5.5 PS 4.5 Cl 0.8 Br 0.7 Li7PS6, Li7P3S 11 Li6PS5Cl, Li6PS5Br, Li 10 GeP2S 12 and Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 At least one of them.

6. The method according to claim 1, characterized in that, The particle size distribution D of the sulfide particles 50 The range is 0.2 μm to 30 μm.

7. The method according to claim 1, characterized in that, The first mixing treatment was carried out for 5 to 15 hours at a rotation speed of 500 to 700 r / min and a temperature of 40 to 80℃. And / or, the second mixing treatment is carried out for 0.5 to 10 hours at a rotation speed of 300 to 1000 r / min and a temperature of 25 to 60°C; And / or, the mass ratio of the first mixed product to the second solvent is (0.5~3):(1~5); And / or, the third mixing treatment is carried out for 0.5 to 10 hours at a rotation speed of 300 to 500 r / min and a temperature of 25 to 60°C; And / or, the drying process is carried out in an oven under vacuum or inert gas conditions for 2 to 20 hours.

8. The application of the solid electrolyte prepared by the method according to any one of claims 1 to 7 in all-solid-state lithium batteries.

9. A solid-state battery, characterized in that, include: Positive electrode, negative electrode, and solid electrolyte prepared by the method according to any one of claims 1 to 7.

10. An electronic device, characterized in that, include: The solid-state battery according to claim 9.

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