Solid-state electrolyte material, preparation method therefor, and use thereof

Abstract

The application discloses a kind of solid electrolyte material and its preparation method and application, solid electrolyte material can be used to make solid battery, including shell layer and the core wrapped in shell layer;The component of core is lithium ion conductor;Shell layer separates core with external air, and shell layer is sublimated / decomposed after heat treatment and removed from solid electrolyte material.The preparation method is to obtain solid electrolyte core, with shell layer component as raw material, form shell layer on the surface of solid electrolyte core by chemical vapor deposition method.The application uses "coating-thermal decomposition regeneration" dynamic control mechanism, completely solves the contradiction of solid electrolyte "storage needs protective layer, battery needs clean interface", so that the solid electrolyte material of the application has very high convenience and lower cost when producing, transporting, processing, and when used for preparing solid battery, can ensure that the electrochemical performance of battery is not affected.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery materials, and more particularly to a solid-state electrolyte material. Background Technology

[0002] As a core material for solid-state batteries, solid-state electrolytes are facing severe environmental tolerance challenges. High-performance oxide systems (such as LLZO and LLTO) and sulfide systems (such as LGPS) undergo catastrophic degradation upon contact with air. When exposed to environments containing trace amounts of moisture (RH > 30%), an insulating lithium carbonate layer forms on the surface of LLZO within 72 hours, causing a precipitous drop in ionic conductivity of over 90%. Equally critical is the hydrolysis problem of sulfide electrolytes—LGPS decomposes upon contact with water, producing highly toxic hydrogen sulfide gas, while simultaneously experiencing a conductivity decrease of over 60%. Behind these phenomena lies the inherent chemical instability of the materials: lithium ions in oxides readily react with carbon dioxide, while the PS bonds in sulfides break upon contact with water. Industry estimates suggest that material losses due to environmental sensitivity increase the mass production cost of solid-state batteries by 35%, becoming a primary obstacle to industrialization.

[0003] The environmental sensitivity of materials is tearing the entire industry chain apart. On the production side, the entire process from synthesis to battery assembly must rely on inert gas protection, which alone increases electrolyte costs by $8.7 per kilogram. Even more serious is the challenge of cross-border transportation: current methods require transporting electrolyte powder sealed in special containers under an argon atmosphere, increasing the cost of a single sea freight shipment by four times. On the manufacturing side, to avoid environmental degradation, electrode-electrolyte integration must be carried out in glove boxes with dew points below -60°C, causing production efficiency to plummet by 40%. Data shows that this ultra-low humidity environment makes the energy consumption of a single production line three times that of a traditional battery factory. Ultimately, on the battery performance side, environmental degradation triggers triple failure: the interfacial side reaction layer increases the ion migration barrier by 5, localized amorphization of the bulk phase leads to a decrease in bulk conductivity, and electrode contact degradation compresses cycle life to less than 100 cycles. Toyota's verification shows that LGPS electrolytes exposed to air for only 2 hours reduced the cycle life of assembled batteries to 30% of their original performance.

[0004] Current technological approaches to improving the surface stability of solid-state electrolyte materials face a dilemma: any attempt to enhance environmental stability comes at the cost of sacrificing interfacial dynamics. For example, Chinese patent application CN111082132A uses magnetron sputtering to form a physical barrier of lithium phosphate on the surface of a sulfide electrolyte; Chinese patent application CN119029285A forms a hydrophobic coating layer by reacting unsaturated carboxylic esters with the sulfide electrolyte; Chinese patent application CN119654730A generates an air-stable polymer coating layer on the surface of a sulfide electrolyte; and Chinese patent application CN110176628A coats an air-stable oxide coating layer onto the surface of the oxide solid electrolyte lithium lanthanum zirconium oxide (LLZO). While these methods of forming a physical protective layer on the electrolyte surface improve the air stability of the electrolyte material, the lithium-ion conductivity of the coating layer is much lower than that of the electrolyte itself, severely blocking lithium-ion transport, causing a surge in interfacial impedance, ultimately leading to a loss of full-cell energy density and accelerated battery performance degradation. Therefore, improving the air stability of the electrolyte without sacrificing electrolyte performance is crucial for promoting the commercial application of solid-state battery technology. Summary of the Invention

[0005] This invention provides a solid electrolyte material, its preparation method, and its application, in order to solve the technical problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0007] A solid electrolyte material includes a shell and a core encapsulated within the shell; the core is composed of lithium-ion conductors; the shell isolates the core from the outside air, and the shell sublimates / decomposes and is removed from the solid electrolyte material after heat treatment.

[0008] The design concept of the above technical solution is that by coating the core with a protective layer to isolate the core from contact with air, the lithium-ion conductor (i.e., lithium-ion solid electrolyte) is prevented from deteriorating and its performance degraded. This allows the electrolyte material to maintain the structural stability of the core material even when exposed to air, improving the material's processability and significantly reducing the cost and difficulty of production, transportation, and assembly. At the same time, the protective layer can be removed through heat treatment steps in battery manufacturing (such as the solvent removal process after coating the positive and negative electrodes), restoring the lithium-ion conductivity of the electrolyte material. This avoids the protective layer affecting the performance of the electrolyte material and the final battery product. Through the reversible coating scheme, the solid electrolyte material of this invention can possess both ultra-high stability and lithium-ion conductivity.

[0009] As a further preferred embodiment of the above technical solution, after the solid electrolyte material is heat-treated at a temperature of 70°C or above, the residual amount of the shell layer is ≤2 at%, and after the solid electrolyte material is heat-treated at a temperature of 120°C or above, the residual amount of the shell layer is ≤0.05 at%.

[0010] As a further preferred embodiment of the above technical solution, the shell layer comprises elemental sulfur.

[0011] As a further preferred embodiment of the above technical solution, the thickness of the shell layer is 0.1 nm to 10000 nm, and more preferably 5 nm to 1000 nm. If the thickness is too thin, it cannot prevent moisture from eroding the core; if it is too thick, it will affect the subsequent removal and cause a waste of resources. Therefore, a suitable thickness range is required.

[0012] As a further preferred embodiment of the above technical solution, the lithium-ion conductor comprises garnet-type Li a La b Zr c O d and its derivatives, perovskite-type Li a La b Ti c O d and its derivatives, sulfide-germanium type Li a P b S c Cl d , and its derivatives, Li 10 GeP2S 12 and its derivatives and Li a Ni b Cl c O d At least one of the following: a, b, c, and d, where a, b, c, and d are stoichiometric coefficients that take different values ​​in different lithium-ion conductors. The aforementioned common lithium-ion conductors (i.e., lithium-ion solid electrolytes) are highly sensitive to air, and their performance deteriorates significantly upon contact with air, making them particularly suitable for the scheme of this invention.

[0013] As a further preferred embodiment of the above technical solution, the particle size of the lithium-ion conductor is 0.05~50μm, and more preferably 0.2~10μm. The particle size is mainly selected and adjusted according to the application scenario of the material.

[0014] Based on the same technical concept, the present invention also provides a method for preparing the solid electrolyte material described in the above technical solution, comprising the following operations: preparing a solid electrolyte core using the raw materials of the lithium-ion conductor, and forming a shell layer on the surface of the solid electrolyte core using the shell component as raw material by chemical vapor deposition, thereby obtaining the solid electrolyte material.

[0015] As a further preferred embodiment of the above technical solution, the raw materials for the lithium-ion conductor include a lithium source, and also at least one of a lanthanum source, zirconium source, titanium source, phosphorus source, sulfur source, chlorine source, and germanium source. The lithium-ion conductor is a traditional oxide or sulfide system lithium-ion solid electrolyte, which can be prepared using traditional methods such as solid-state sintering, melt-annealing, and solution methods.

[0016] As a further preferred embodiment of the above technical solution, the raw material for the chemical vapor deposition method is sulfur powder. During chemical vapor deposition, the sulfur powder is placed in the low-temperature zone of the chemical vapor deposition furnace, and the solid electrolyte core is placed in the high-temperature zone. Under vacuum conditions, nitrogen is used as the carrier gas to transport sulfur to the surface of the core precursor for deposition, forming a shell.

[0017] As a further preferred embodiment of the above technical solution, the temperature in the low-temperature zone is 115±1℃, and the temperature in the high-temperature zone is 130~150℃. The carrier gas flow rate is controlled at 20~1000mL / min. The vacuum degree during the deposition process is 10~50Pa.

[0018] Based on the same technical concept, the present invention also provides an application of the solid electrolyte material described in the above technical solution, which can be used to manufacture solid-state batteries.

[0019] As a further preferred embodiment of the above technical solution, the solid-state battery includes a positive electrode, a negative electrode, and an electrolyte sheet;

[0020] The method for preparing the positive electrode sheet is as follows: a positive electrode mixture is prepared by using the solid electrolyte material, positive active material, conductive agent and binder, and then it is compounded with aluminum foil. After heat treatment, excess solvent and shell structure coated on the solid electrolyte material are removed, and the positive electrode sheet is obtained by rolling and cutting.

[0021] The method for preparing the negative electrode sheet is as follows: a negative electrode mixture is prepared by using the solid electrolyte material, negative electrode active material, conductive agent and binder, and then combined with copper foil. After heat treatment, excess solvent and shell structure coated on the solid electrolyte material are removed, and the negative electrode sheet is obtained by rolling and cutting.

[0022] And / or the preparation method of the electrolyte sheet is as follows: an electrolyte mixture is prepared by using the solid electrolyte material and a binder, then coated on a base film, and after heat treatment, excess solvent and shell structure covering the solid electrolyte material are removed. After rolling, the base film is separated and cut to obtain the electrolyte sheet.

[0023] The present invention has the following beneficial effects:

[0024] This invention is the first to employ a dynamic control mechanism of "coating-thermal decomposition and regeneration," completely resolving the contradiction between the need for a protective layer in solid-state electrolytes (SSEs) and the requirement for a clean interface in batteries. A core-shell structure is formed through a simple process. Utilizing the sublimation / decomposition of the shell layer at low temperatures, a nanoscale protective layer is constructed on the electrolyte surface, achieving superior stability in air. Subsequently, precise thermal decomposition completely removes the coating layer, restoring the interfacial ionic conductivity. This reversible cycle fundamentally avoids the problems of increased interfacial impedance caused by permanent residues of traditional ALD coatings and the residual issues of liquid-phase sulfur coatings. This makes the solid-state electrolyte material of this invention highly convenient and cost-effective in production, transportation, and processing, while ensuring that the electrochemical performance of the battery remains unaffected when used in the fabrication of solid-state batteries. Attached Figure Description

[0025] Figure 1 The image shows a transmission electron microscope (TEM) image of the solid electrolyte material prepared in Example 1. Detailed Implementation

[0026] The present invention will be described in detail below with reference to the accompanying drawings and embodiments, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0027] Example 1:

[0028] The solid electrolyte material of this embodiment includes a shell and a core encapsulated within the shell; the core is composed of lithium-ion conductors Li. 6.28 Al 0.24 La3Zr2O 12 (D50 particle size is 10 μm); the shell is composed of elemental sulfur, with a thickness of approximately 50 nm, which isolates the core from the external air. A transmission electron microscope (TEM) image of the solid electrolyte material in this embodiment is shown below. Figure 1 As shown in the figure, a dense coating layer with a thickness of about 50 nm has been formed on the surface of the core.

[0029] The solid electrolyte material in this embodiment is prepared by the following method:

[0030] (1) Preparation of solid electrolyte core:

[0031] According to stoichiometry, Li 6.28 Al 0.24 La3Zr2O 12 Lithium carbonate, aluminum hydroxide, zirconium nitrate, and lanthanum oxide were weighed out (Li₂CO₃ was added in excess at 10 wt% for sublimation compensation, and La₂O₃ was pre-calcined to remove water). The raw materials were mixed by planetary ball milling (300 rpm, 12 h, anhydrous ethanol medium), dried, sieved, and then heat-treated at 900℃ for 12 h. The resulting electrolyte material was further refined and classified using a mechanical grinder to a D50 of 10 μm to obtain a solid electrolyte core.

[0032] (2) Coating process:

[0033] First, the solid electrolyte core was vacuum dried at 120°C for 2 hours, and then placed in the deposition zone of a CVD furnace (150°C). High-purity sulfur powder was placed in a quartz boat in the evaporation zone (115°C). Under nitrogen carrier gas (20 mL / min) and a low vacuum environment (10 Pa), sulfur vapor was directionally transported to the surface of the solid electrolyte core. The solid electrolyte core was deposited for 50 minutes through a melt-condensation mechanism to form a continuous sulfur-coated shell structure. After the deposition was completed, the solid electrolyte material of this embodiment was obtained by cooling in a nitrogen atmosphere.

[0034] Comparative Example 1:

[0035] The solid electrolyte material of this comparative example was prepared by the following method:

[0036] (1) Same as in Example 1:

[0037] According to stoichiometry, Li 6.28 Al 0.24 La3Zr2O 12 Lithium carbonate, aluminum hydroxide, zirconium nitrate, and lanthanum oxide were weighed out (Li₂CO₃ was added in excess at 10 wt% for sublimation compensation, and La₂O₃ was pre-calcined to remove water). The raw materials were mixed by planetary ball milling (300 rpm, 12 h, anhydrous ethanol medium), dried, sieved, and then heat-treated at 900℃ for 12 h. The resulting electrolyte material was further refined and classified using a mechanical grinder to a D50 of 10 μm to obtain a solid electrolyte core.

[0038] (2) The solid electrolyte core is ground together with ammonium dihydrogen phosphate and lithium carbonate for 1 hour and then heat-treated at 800°C for 2 hours to obtain a solid electrolyte material with a lithium phosphate coating on the surface.

[0039] Example 2:

[0040] The solid electrolyte material of this embodiment includes a shell and a core encapsulated within the shell; the core is composed of lithium-ion conductors Li. 0.33 La 0.56 TiO3 (D50 particle size is 100nm); the shell is composed of elemental sulfur and is about 5nm thick, which isolates the core from the outside air.

[0041] The solid electrolyte material in this embodiment is prepared by the following method:

[0042] (1) Preparation of solid electrolyte core:

[0043] According to stoichiometry, Li 0.33 La 0.56TiO3 was prepared by weighing lithium carbonate, titanium dioxide, and lanthanum oxide as raw materials (Li2CO3 was added in excess at 10 wt% for sublimation compensation, and La2O3 was pre-calcined to remove water). The raw materials were mixed by planetary ball milling (350 rpm, 12 h, anhydrous ethanol medium), dried, sieved, and then heat-treated at 900℃ for 12 h. Further, the mixture was refined to below 100 nm by sand milling in an isopropanol system, followed by spray drying. After depolymerization, the D50 was approximately 100 nm, yielding a solid electrolyte core.

[0044] (2) Coating process:

[0045] First, the solid electrolyte core was vacuum dried at 120°C for 2 hours, and then placed in the deposition zone of a CVD furnace (150°C). High-purity sulfur powder was placed in a quartz boat in the evaporation zone (115°C). Under nitrogen carrier gas (20 mL / min), sulfur vapor was directionally transported to the surface of the solid electrolyte core. Deposition was carried out for 5 minutes through a melt-condensation mechanism to form a continuous sulfur-coated shell structure. After deposition, the solid electrolyte material of this embodiment was obtained by cooling in a nitrogen atmosphere.

[0046] Example 3:

[0047] The solid electrolyte material of this embodiment includes a shell and a core encapsulated within the shell; the core is composed of lithium-ion conductors Li. 10 GeP2S 12 (D50 particle size is 2μm); the shell is composed of elemental sulfur and is about 60nm thick, which isolates the core from the outside air.

[0048] The solid electrolyte material in this embodiment is prepared by the following method:

[0049] (1) Preparation of solid electrolyte core:

[0050] In an argon glove box with a dew point < -60℃, high-purity raw materials were accurately weighed according to a stoichiometric ratio of Li₂S:GeS₂:P₂S₅ = 5:1:1, and added to a zirconia ball mill jar containing anhydrous toluene solvent (ball-to-material ratio 20:1). The mixture was ball-milled at 500 rpm for 20 h to obtain an amorphous precursor. After drying, it was pressed into tablets at 300 MPa and sealed under vacuum (10... -3 Li was crystallized in a quartz tube containing Pa at a temperature increased to 500℃ at a rate of 2℃ / min and held at that temperature for 10 hours. After furnace cooling, Li was obtained. 10 GeP2S 12 Bulk. Further crushing yielded Li with a D50 of approximately 2 micrometers. 10 GeP2S 12 Electrolyte materials are solid electrolyte cores.

[0051] (2) Coating process:

[0052] First, the solid electrolyte core was vacuum dried at 120°C for 2 hours, and then placed in the deposition zone of a CVD furnace (150°C). High-purity sulfur powder was placed in a quartz boat in the evaporation zone (115°C). Under nitrogen carrier gas (20 mL / min), sulfur vapor was directionally transported to the surface of the solid electrolyte core. The solid electrolyte core was deposited for 60 minutes through a melt-condensation mechanism to form a continuous sulfur-coated shell structure. After the deposition was completed, the solid electrolyte material of this embodiment was obtained by cooling in a nitrogen atmosphere.

[0053] Example 4:

[0054] The solid electrolyte material of this embodiment includes a shell and a core encapsulated within the shell; the core is composed of lithium-ion conductor Li6PS5Cl (D50 particle size of 200nm); the shell is composed of elemental sulfur and has a thickness of about 10nm, which isolates the core from the outside air.

[0055] The solid electrolyte material in this embodiment is prepared by the following method:

[0056] (1) Preparation of solid electrolyte core:

[0057] In an argon glove box with a dew point < -60℃, high-purity raw materials were accurately weighed according to the stoichiometric ratio of Li₂S:P₂S₅:LiCl = 3:1:0.5 (Li₂S and LiCl need to be dehydrated under vacuum at 120℃ for 12 hours). Acetonitrile solvent and zirconia grinding balls (ball-to-material ratio 30:1) were added, and the mixture was ball-milled at 400 rpm for 24 hours to form a uniform slurry. After vacuum drying at 80℃, the mixture was ground and sieved. The powder was then pressed into tablets and sealed under vacuum (10... -3 Crystallization was achieved by heating the material to 500℃ at 3℃ / min and holding it for 8 hours in a quartz tube. The material was then further refined by sand milling in anisole system until the D50 was below 200nm. After further centrifugation, drying, and dissociation, Li6PS5Cl electrolyte material with a D50 particle size of 200nm was obtained, which is the solid electrolyte core.

[0058] (2) Coating process:

[0059] First, the solid electrolyte core was vacuum dried at 120°C for 2 hours, and then placed in the deposition zone of a CVD furnace (150°C). High-purity sulfur powder was placed in a quartz boat in the evaporation zone (115°C). Under nitrogen carrier gas (20 mL / min), sulfur vapor was directionally transported to the surface of the solid electrolyte core. The solid electrolyte core was deposited for 10 minutes through a melt-condensation mechanism to form a continuous sulfur-coated shell structure. After the deposition was completed, the solid electrolyte material of this embodiment was obtained by cooling in a nitrogen atmosphere.

[0060] Example 5:

[0061] The solid electrolyte material of this embodiment includes a shell and a core encapsulated within the shell; the core is composed of lithium-ion conductor LiNbOCl4 (D50 particle size is 5μm); the shell is composed of elemental sulfur and has a thickness of about 30nm, which isolates the core from the outside air.

[0062] The solid electrolyte material in this embodiment is prepared by the following method:

[0063] (1) Preparation of solid electrolyte core:

[0064] In an argon glove box with a dew point < -60℃, raw materials were weighed according to a stoichiometric ratio of LiCl:NbOCl3 = 1:1 (NbOCl3 needs to be pre-calcined at 120℃ to remove impurities, and LiCl is vacuum dried at 150℃ for 24h). Anhydrous heptane solvent and zirconia grinding balls (ball-to-material ratio 20:1) were added, and the mixture was ball-milled at 350rpm for 15h to form a uniform precursor. After drying, the precursor was pressed into tablets and sealed under vacuum (10... -3 In a quartz tube, the temperature was increased to 150℃ at 3℃ / min and held for 12h to complete the solid-phase reaction. After cooling in the furnace, the material was further refined by dry ball milling to obtain LiNbOCl4 solid electrolyte material with a D50 of 5μm, which is the solid electrolyte core.

[0065] (2) Coating process:

[0066] First, the solid electrolyte core was vacuum dried at 120°C for 2 hours, and then placed in the deposition zone of a CVD furnace (150°C). High-purity sulfur powder was placed in a quartz boat in the evaporation zone (115°C). Under nitrogen carrier gas (20 mL / min), sulfur vapor was directionally transported to the surface of the solid electrolyte core. The solid electrolyte core was deposited for 30 minutes through a melt-condensation mechanism to form a continuous sulfur-coated shell structure. After the deposition was completed, the solid electrolyte material of this embodiment was obtained by cooling in a nitrogen atmosphere.

[0067] The solid electrolyte materials of each embodiment were tested, and the test methods and results are shown below:

[0068] I. Characterization of residual rate of coating layer after heat treatment:

[0069] The samples from Examples 1-5 were divided into three parts: one part was left untreated as a control sample; one part was heat-treated in a glove box at 70°C for 2 hours; and the other part was heat-treated in a glove box at 150°C for 2 hours. The elemental sulfur content of the three materials was tested using ICP (atomic absorption spectrometry). The residual sulfur content of the sample after heat treatment at different temperatures was calculated as: (Elemental sulfur content of the heat-treated sample / Elemental sulfur content of the control sample). The residual sulfur content test results are shown in Table 1.

[0070] The specific detection steps for ICP testing of elemental sulfur content are as follows:

[0071] (1) Sample pretreatment: For materials whose core does not contain sulfur (such as in Examples 1, 2 and 5), direct digestion is performed. For materials whose core contains sulfur (such as in Examples 3 and 4), the elemental sulfur in the material is first fully dissolved in toluene, then centrifuged. The dissolution-centrifugation operation is repeated until the precipitate does not contain elemental sulfur. All supernatant is collected for digestion.

[0072] (2) Sample digestion: High-temperature and high-pressure digestion is carried out in a high-pressure closed digestion vessel (such as a microwave digester) using a mixture of strong oxidizing acids (e.g., nitric acid-hydrochloric acid mixture) to convert elemental sulfur into sulfate.

[0073] (3) Sulfur content test: The digested sample is put into the ICP test equipment to test the content of sulfate ions, and the content of elemental sulfur is calculated.

[0074]

[0075] II. Battery performance characterization:

[0076] Batteries were fabricated using the solid electrolyte core and solid electrolyte material from each embodiment and comparative example as raw materials, and their performance was tested. The test methods are as follows:

[0077] 1. Place the solid electrolyte core and solid electrolyte material of Examples 1-5 and the solid electrolyte material of Comparative Example 1 under normal temperature and humidity (25°C, 33% relative humidity) for 2 hours.

[0078] 2. Battery manufacturing

[0079] 2.1 Semi-solid-state battery fabrication:

[0080] The solid electrolyte core and solid electrolyte material of Example 1 and Example 2, as well as the solid electrolyte material of Comparative Example 1, were respectively mixed with NCM622 positive electrode material, conductive agent (SP+CNTs), and binder (PVDF) in a ratio of 1:96:1.5:1.5 to prepare NMP slurry. The slurry was coated on an aluminum foil with a thickness of 16 micrometers, dried in a forced air at 150°C for 2 hours, and then rolled and cut to obtain positive electrode sheets.

[0081] A silicon-carbon anode (nano-silicon and graphite in a mass ratio of 1:9), PEG-400, CMC, PAA, and a conductive agent (Ketjen black: carbon nanotubes = 3:1) were dispersed at high speed (2000 rpm, 1 h) in a deionized aqueous solution at a ratio of 91.5:3:2:1.5:2 to form a premixed slurry. This slurry was coated onto copper foil, dried at 80°C for 1 h, then vacuum heat-treated at 200°C for 2 h, and further rolled and cut into suitable sizes to obtain the anode sheet.

[0082] The positive electrode sheet, a traditional PE separator, and the negative electrode sheet are assembled into a semi-solid-state soft-pack battery using a stacking machine, a packaging machine, and a liquid injection machine.

[0083] 2.2. Fabrication of all-solid-state batteries:

[0084] The solid electrolyte core and solid electrolyte material from Examples 3-5 were respectively combined with NCM622 positive electrode material, conductive agent (SP+CNTs), and binder (PTFE) in a ratio of 1:96:1.5:1.5 to prepare electrode sheets using a dry electrode process. The electrodes were then dried at 150°C for 2 hours, further rolled, and cut to obtain positive electrode sheets.

[0085] The solid electrolyte core and solid electrolyte material from Examples 3-5 were mixed with binder (PTFE) at a ratio of 97.5:1.5 using a dry process and then laminated with PET film. The mixture was further dried at 120°C for 2 hours, rolled, and cut to obtain electrolyte sheets.

[0086] The positive electrode, electrolyte, and lithium indium alloy negative electrode are sequentially loaded into a solid-state battery mold and then locked under a pressure of 200 MPa to obtain an all-solid-state battery.

[0087] 3. Battery evaluation:

[0088] The electrical performance of each battery was tested, including AC impedance, 0.2C discharge capacity, and 0.2C cycle testing. The test results are shown in Table 2.

[0089]

[0090] [Note] Because the solid electrolyte core material in Example 1 is highly alkaline, it caused gelation of the slurry during the preparation of the positive electrode slurry, making it impossible to prepare the positive electrode sheet normally.

[0091] It can be seen that, after being placed at room temperature and humidity, the solid electrolyte materials of the various embodiments of the present invention significantly improve the battery capacity and cycle performance compared to the uncoated solid electrolyte core, demonstrating the air stability of the solid electrolyte materials of the various embodiments of the present invention. At the same time, compared to Comparative Example 1 with a lithium phosphate protective layer, the present application has less impact on the battery internal resistance, capacity and cycle performance, and combines stability and electrochemical performance.

[0092] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and modifications obtained without departing from the inventive concept should also be considered within the scope of protection of the present invention.

[0093] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An application of a solid electrolyte material, characterized in that, The solid electrolyte material includes a shell and a core encapsulated within the shell; the core is composed of lithium-ion conductors; the shell isolates the core from the external air, and the shell sublimates / decomposes and is removed from the solid electrolyte material after heat treatment; after heat treatment at 70°C or above, the residual amount of the shell is ≤2 at%; after heat treatment at 120°C or above, the residual amount of the shell is ≤0.05 at% The solid electrolyte material is used to manufacture a solid-state battery; the solid-state battery includes a positive electrode, a negative electrode, and an electrolyte sheet. The method for preparing the positive electrode sheet is as follows: a positive electrode mixture is prepared by using the solid electrolyte material, positive active material, conductive agent and binder, and then it is compounded with aluminum foil. After heat treatment, excess solvent and shell structure coated on the solid electrolyte material are removed, and the positive electrode sheet is obtained by rolling and cutting. The method for preparing the negative electrode sheet is as follows: a negative electrode mixture is prepared by using the solid electrolyte material, negative electrode active material, conductive agent and binder, and then combined with copper foil. After heat treatment, excess solvent and shell structure coated on the solid electrolyte material are removed, and the negative electrode sheet is obtained by rolling and cutting. And / or the preparation method of the electrolyte sheet is as follows: an electrolyte mixture is prepared by using the solid electrolyte material and a binder, then coated on a base film, and after heat treatment, excess solvent and shell structure covering the solid electrolyte material are removed. After rolling, the base film is separated and cut to obtain the electrolyte sheet.

2. The application of the solid electrolyte material according to claim 1, characterized in that, The shell is composed of elemental sulfur.

3. The application of the solid electrolyte material according to claim 1, characterized in that, The thickness of the shell is 0.1 nm to 10000 nm.

4. The application of the solid electrolyte material according to any one of claims 1-3, characterized in that, The lithium-ion conductor includes garnet-type Li a La b Zr c O d and its derivatives, perovskite-type Li a La b Ti c O d and its derivatives, sulfide-germanium type Li a P b S c Cl d and its derivatives, Li 10 GeP2S 12 and its derivatives and Li a Ni b Cl c O d At least one of the following and its derivatives, wherein a, b, c, and d are stoichiometric coefficients.

5. The application of the solid electrolyte material according to claim 4, characterized in that, The particle size of the lithium-ion conductor is 0.05~50μm.

6. The application of the solid electrolyte material according to any one of claims 1-3, characterized in that, The preparation method of the solid electrolyte includes the following operations: using the raw materials of the lithium-ion conductor to prepare a solid electrolyte core, using the shell component as raw material, forming a shell on the surface of the solid electrolyte core by chemical vapor deposition, thereby obtaining the solid electrolyte material.

7. The application of the solid electrolyte material according to claim 6, characterized in that, The raw materials for the lithium-ion conductor include a lithium source, and also include at least one of a lanthanum source, a zirconium source, a titanium source, a phosphorus source, a sulfur source, a chlorine source, and a germanium source.

8. The application of the solid electrolyte material according to claim 6, characterized in that, The raw material for the chemical vapor deposition method is sulfur powder. During chemical vapor deposition, the sulfur powder is placed in the low-temperature zone of the chemical vapor deposition furnace, and the solid electrolyte core is placed in the high-temperature zone. Under vacuum conditions, nitrogen is used as a carrier gas to transport sulfur to the surface of the core precursor for deposition, forming a shell.

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