A sulfide solid-state electrolyte and a preparation method and application thereof

Abstract

This invention relates to the field of battery technology, specifically to a sulfide solid electrolyte, its preparation method, and its applications; the chemical formula of the sulfide solid electrolyte is Li. 7‑x M x P 3‑y Q y S 11‑z O z Wherein, M is selected from at least one of Al, Ga, and In, and Q is selected from at least one of Si, Ge, Sn, Sb, Mo, Zn, Nb, Ta, and La, with 0.05 ≤ x ≤ 0.3 and 0.1 ≤ y ≤ 0.5; the room temperature ionic conductivity of the sulfide solid electrolyte is ≥ 6.8 × 10⁻⁶. ‑3 S cm ‑1 Furthermore, after exposure to an environment with a relative humidity of 5% for 30 minutes, the ionic conductivity retention rate is ≥79%. Compared with the prior art, this invention synergistically optimizes the lithium-ion migration channel through M and Q co-substitution and O / S co-doping, thereby improving the ionic conductivity and structural stability of the sulfide solid electrolyte.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a sulfide solid electrolyte, its preparation method, and its application. Background Technology

[0002] Sulfide solid electrolytes are characterized by their extremely high ionic conductivity (up to 10). -2 S·cm -1 With its high energy density (on a scale of several millimeters) and good machinability, it is considered a core material for next-generation high-energy-density all-solid-state batteries. Currently, mainstream sulfide electrolytes, such as Li... 10 GeP2S 12 Li6PS5X type, usually prepared by high-energy ball milling combined with heat treatment (solid phase method) or liquid phase method.

[0003] Solid-phase methods (mechanical ball milling) are simple, but they easily introduce impurities, resulting in poor batch-to-batch consistency. Furthermore, the synthesized electrolyte powder is sensitive to air and exhibits high interfacial resistance. Liquid-phase methods can achieve molecular-level homogeneous mixing and high product purity, but they typically use highly toxic and expensive organic solvents (such as acetonitrile and tetrahydrofuran), and subsequent solvent removal is difficult, often leaving residues that degrade performance. Due to the limitations of their inherent principles, these individual methods struggle to precisely and synergistically control various defects in the electrolyte material (such as vacancies, doping, and grain boundary structures) during synthesis. Summary of the Invention

[0004] In view of this, the present invention aims to at least partially solve one of the technical problems in the related art. To this end, the present invention provides a sulfide solid electrolyte, its preparation method, and its application. Through the substitution of M and Q elements and oxygen doping, a controllable composite defect structure is formed, synergistically optimizing the lithium-ion migration channel, thereby enabling the electrolyte to simultaneously possess high room-temperature ionic conductivity and good air stability.

[0005] To solve the above-mentioned technical problems, the present invention is implemented as follows: According to one aspect of the present invention, a sulfide solid electrolyte with the general chemical formula Li is provided. 7-x M x P 3-y Q y S 11-x O x Wherein, M is selected from at least one of Al, Ga and In, Q is selected from at least one of Si, Ge, Sn, Sb, Mo, Zn, Nb, Ta and La, 0.05≤x≤0.3, 0.1≤y≤0.5; The sulfide solid electrolyte has a room temperature ionic conductivity ≥ 6.8 × 10⁻⁶. -3 S cm -1Furthermore, after exposure to an environment with a relative humidity of 5% for 30 minutes, the ionic conductivity retention rate is ≥79%.

[0006] According to another aspect of the present invention, a method for preparing a sulfide solid electrolyte is provided, comprising the following steps: S1. Mix the lithium source, phosphorus source, M source, Q source and defect modifier to obtain a first mixture containing sulfur. S2. The first mixture obtained in S1 is mixed with an organic solvent and subjected to a first heat treatment reaction to obtain a second mixture; S3. The second mixture obtained in S2 is subjected to a second heat treatment to obtain a sulfide solid electrolyte.

[0007] In some embodiments, in step S1, the defect modifier comprises a eutectic mixture of Li2O and NH4Cl.

[0008] In some of these embodiments, the mixing is carried out under an inert atmosphere.

[0009] In some of these embodiments, the mixing process specifically involves ball milling.

[0010] In some embodiments, in step S1, the molar ratio of Li2O to NH4Cl is 1:1 to 2:1.

[0011] In some of these embodiments, in step S2, the organic solvent includes toluene and 1,2-dimethoxyethane.

[0012] In some of these embodiments, the mixing is specifically performed by ultrasonic dispersion.

[0013] In some of these embodiments, the temperature of the first heat treatment is 80°C to 120°C.

[0014] In some of these embodiments, the first heat treatment lasts for 6 to 12 hours.

[0015] In some embodiments, in step S2, the volume ratio of toluene to 1,2-dimethoxyethane is 3:1 to 1:1.

[0016] In some embodiments, step S3, before the second heat treatment, further includes: vacuum filtering the second mixture obtained in S2, vacuum drying the obtained precipitate at 120°C to 150°C for 8 to 12 hours to obtain powder, and then pressing the powder into sheet-like preforms.

[0017] In some embodiments, in step S3, the reaction atmosphere of the second heat treatment includes H2S.

[0018] In some of these embodiments, the temperature of the second heat treatment is 450°C to 550°C.

[0019] In some of these embodiments, the second heat treatment lasts for 2 to 5 hours.

[0020] In some of these embodiments, the heating rate of the second heat treatment is 2°C / min to 5°C / min.

[0021] In some embodiments, in step S3, the volume fraction of H2S in the reaction atmosphere is 1% to 5%.

[0022] According to another aspect of the present invention, a solid-state battery is provided, comprising a positive electrode, a negative electrode, and a solid electrolyte membrane; The solid electrolyte membrane includes the sulfide solid electrolyte described in the above technical solution or the sulfide solid electrolyte prepared by the preparation method described in the above technical solution.

[0023] This invention provides a sulfide solid electrolyte, its preparation method, and its application, with the following advantages: 1. This invention forms a wide and continuous lithium-ion migration channel by substituting lithium sites with element M, phosphorus sites with element Q, and sulfur sites with element O, effectively improving ionic conductivity and enhancing crystal structure stability, thus achieving a balance between high ionic conductivity and good air stability. Specifically, the introduced element M... 3+ Additional lithium vacancies are created, while appropriate amounts of O doping improve the material's thermodynamic stability and tolerance to humid air.

[0024] 2. This invention combines the high reactivity of mechanical ball milling with the high uniformity of components in liquid phase method, avoiding the disadvantages of a single method. The mechanical pretreatment reduces the liquid phase reaction temperature and time, while the liquid phase process improves the uniformity of the final product.

[0025] 3. This invention uses a low-toxicity, low-boiling-point, weakly polar solvent to replace highly toxic solvents such as acetonitrile, and the solvent is easily removed through vacuum drying. The controllable heat treatment process avoids high-temperature sulfur volatilization, resulting in good product consistency.

[0026] 4. This invention utilizes defect modifiers to achieve multiple precise controls on vacancies, doping, and micropores in sulfide solid electrolytes, which is difficult to achieve using traditional methods. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present application, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the description of this application, "same chemical composition" should be interpreted broadly, that is, the main components of the two have the same chemical composition, or the two have substantially the same chemical composition, but may have errors or impurities within the acceptable range that can be understood by those skilled in the art.

[0029] 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.

[0030] Unless otherwise stated, all technical 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. All patents and publications referenced in this application are incorporated herein by reference in their entirety. The terms "comprising" or "including" are open-ended expressions, meaning they include the contents specified in this application but do not exclude other contents.

[0031] Sulfide solid electrolytes are characterized by their extremely high ionic conductivity (up to 10). -2 S·cm -1 With its high energy density (on a scale of several millimeters) and good machinability, it is considered a core material for next-generation high-energy-density all-solid-state batteries. Currently, mainstream sulfide electrolytes, such as Li... 10 GeP2S 12 Li6PS5X type, usually prepared by high-energy ball milling combined with heat treatment (solid phase method) or liquid phase method.

[0032] Solid-phase methods (mechanical ball milling) are simple, but they easily introduce impurities, resulting in poor batch-to-batch consistency. Furthermore, the synthesized electrolyte powder is sensitive to air and exhibits high interfacial resistance. Liquid-phase methods can achieve molecular-level homogeneous mixing and high product purity, but they typically use highly toxic and expensive organic solvents (such as acetonitrile and tetrahydrofuran), and subsequent solvent removal is difficult, often leaving residues that degrade performance. Due to the limitations of their inherent principles, these individual methods struggle to precisely and synergistically control various defects in the electrolyte material (such as vacancies, doping, and grain boundary structures) during synthesis.

[0033] The existing sulfide electrolyte synthesis technology has the following drawbacks: (1) it is difficult to balance ionic conductivity, air stability and process environmental protection; (2) electrolyte defects (such as lithium vacancies and sulfur vacancies) are uncontrollable, affecting lithium ion migration; (3) the interfacial compatibility with electrode materials needs to be improved.

[0034] Based on this, the present invention adopts a mechanochemical-liquid phase synergistic synthesis method and introduces a grain boundary defect regulator to actively intervene in the formation process and defect evolution of the electrolyte crystal structure. In this way, while taking into account the controllability of the process, the ionic conductivity and air stability of the sulfide solid electrolyte are effectively optimized.

[0035] Specifically, the present invention adopts the following technical solution: According to one aspect of the present invention, a sulfide solid electrolyte with the general chemical formula Li is provided. 7-x M x P 3-y Q y S 11-x O x Wherein, M is selected from at least one of Al, Ga and In, Q is selected from at least one of Si, Ge, Sn, Sb, Mo, Zn, Nb, Ta and La, 0.05≤x≤0.3, 0.1≤y≤0.5; The sulfide solid electrolyte has a room temperature ionic conductivity ≥ 6.8 × 10⁻⁶. -3 S cm -1 Furthermore, after exposure to an environment with a relative humidity of 5% for 30 minutes, the ionic conductivity retention rate is ≥79%.

[0036] In a specific embodiment of the present invention, the chemical formula of the sulfide solid electrolyte is Li. 7-x M x P 3-y Q y S 11- z O z The sulfide solid electrolyte has a cubic lattice structure similar to Li6PS5Cl, but some S sites are replaced by O atoms, some P sites are replaced by Q elements, and some Li sites are occupied by M elements. Through this multi-site synergistic substitution, a controllable composite defect structure is formed, thereby synergistically optimizing the lithium ion migration channel.

[0037] In a specific embodiment of the present invention, M is selected from at least one of Al, Ga, and In. The introduction of the M element is mainly used to partially substitute lithium sites. Because Al... 3+ Ga 3+ In 3+ The ionic radius of Li +The differences exist, and the higher valence states mean that their substitution introduces additional lithium vacancies into the crystal. These vacancies act as carriers for lithium ion migration, which helps to improve ionic conductivity.

[0038] In a specific embodiment of the present invention, Q is selected from at least one of Si, Ge, Sn, Sb, Mo, Zn, Nb, Ta, and La. The introduction of the Q element is mainly used to partially substitute phosphorus sites.

[0039] In a specific embodiment of the present invention, 0.05≤x≤0.3, specifically can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, and any value between the two mentioned above.

[0040] In a specific embodiment of the present invention, 0.1≤y≤0.5, specifically 0.1, 0.2, 0.3, 0.4, 0.5, and any value between any two of the above.

[0041] In a specific embodiment of the present invention, the room temperature ionic conductivity of the sulfide solid electrolyte is ≥6.8×10⁻⁶. - 3 S cm -1 Furthermore, after exposure to an environment with a relative humidity of 5% for 30 minutes, the ionic conductivity retention rate is ≥79%. The high ionic conductivity is attributed to the wide and continuous lithium-ion migration channels constructed through M and Q co-substitution and process control. The high air stability is mainly attributed to the stabilization of the crystal surface by O doping, which reduces side reactions with moisture in the air, as well as the formation of a dense and chemically stable microstructure.

[0042] According to another aspect of the present invention, a method for preparing a sulfide solid electrolyte is provided, comprising the following steps: S1. Mix the lithium source, phosphorus source, M source, Q source and defect modifier to obtain a first mixture containing sulfur. S2. The first mixture obtained in S1 is mixed with an organic solvent and subjected to a first heat treatment reaction to obtain a second mixture; S3. The second mixture obtained in S2 is subjected to a second heat treatment to obtain a sulfide solid electrolyte.

[0043] A first mixture containing sulfur was obtained by mixing lithium source, phosphorus source, M source, Q source and defect modifier. Specifically, Li2O reacts with NH4Cl in situ to generate LiCl and volatile gases, with LiCl as the product component, while the introduction of Li2O lays the foundation for subsequent oxygen doping.

[0044] In a specific embodiment of the present invention, in step S1, the lithium source includes, but is not limited to, one or more of lithium sulfide (Li2S), lithium oxide (Li2O), lithium hydroxide (LiOH), lithium hydride (LiH), and their hydrates, preferably Li2S. Using Li2S as a lithium source can directly provide Li + and S 2- It is the most direct raw material.

[0045] In a specific embodiment of the present invention, in step S1, the phosphorus source includes, but is not limited to, phosphorus pentasulfide (P2S5), lithium phosphate (Li3PO4), or other thiolated or oxygenated compounds that can provide phosphorus during the synthesis process, preferably P2S5 and / or Li3PO4. P2S5 is one of the most commonly used phosphorus and sulfur sources for the synthesis of thiophosphates, while using Li3PO4 introduces phosphorus, lithium, and oxygen simultaneously.

[0046] In a specific embodiment of the present invention, in step S1, the M source includes, but is not limited to, sulfides, oxides, halides, or other compounds of Al, Ga, and In that can be converted into the target valence state and form during the synthesis process. Specifically, it can be Al2S3, Ga2S3, In2S3, Al2O3, Ga2O3, In2O3, AlCl3, GaCl3, InCl3, etc., with sulfides preferred to reduce the introduction of heteroanions.

[0047] In a specific embodiment of the present invention, in step S1, the Q source includes, but is not limited to, sulfides, oxides, halides or other corresponding compounds of Si, Ge, Sn, Sb, Mo, Zn, Nb, Ta, and La. Specifically, it can be SiS2, GeS2, SnO2, Sb2O3, MoO3, ZnO, NbCl5, Ta2O5, LaCl3, etc., with sulfides preferred to reduce the introduction of heteroanions.

[0048] In a specific embodiment of the present invention, in step S1, the defect modifier comprises a eutectic mixture of Li₂O and NH₄Cl. Li₂O and NH₄Cl not only provide O and Cl doping sources, but also react in situ during mixing to generate LiCl and release volatile gases such as NH₃, HCl, H₂O, and H₂S. LiCl can serve as part of the product or an intermediate, while the released gases, during their escape, construct a nanoscale porous network within the particles and at grain boundaries. These pores can act as "short-circuit channels" for lithium-ion transport, while effectively buffering volumetric strain during cycling. The present invention utilizes the aforementioned defect modifier to achieve multiple precise controls over vacancies, doping, and micropores in the electrolyte, which is difficult to achieve using traditional methods.

[0049] In a specific embodiment of the present invention, in step S1, the molar ratio of Li2O to NH4Cl is 1:1 to 2:1, specifically 1:1, 1.5:1, 2:1, or any value between the two mentioned above. The present invention selects the above molar ratio to ensure a smooth and controllable reaction, avoiding the instantaneous generation of large amounts of gas that could lead to material splashing or agglomeration.

[0050] In a specific embodiment of the present invention, in step S1, the mixing is carried out under an inert atmosphere to prevent air (especially oxygen and water vapor) from oxidizing or hydrolyzing the sensitive sulfide raw materials.

[0051] In a specific embodiment of the present invention, in step S1, the mixing operation is ball milling, specifically: ball milling at a speed of 400 rpm to 600 rpm for 2 to 6 hours in a high-energy planetary ball mill jar. Ball milling can provide strong shearing, impact, and compressive forces, effectively achieving the crushing, mixing, and mechanochemical activation of materials.

[0052] After obtaining a first mixture containing sulfur, the first mixture is mixed with an organic solvent and subjected to a first heat treatment reaction to obtain a second mixture. Specifically, this liquid-phase process promotes the dissolution-recrystallization of the first mixture, achieving atomic-level homogeneous mixing and initial crystallization, and O atoms are doped into sulfur sites through the residual portion of Li2O.

[0053] In a specific embodiment of the present invention, in step S2, the organic solvent includes toluene and 1,2-dimethoxyethane (DME). Toluene, as a weakly polar solvent, has low solubility for ionic inorganic compounds but exhibits good dispersibility and low toxicity. DME, on the other hand, has a certain degree of polarity, enabling it to better wet and disperse some polar components, and is miscible with toluene. The present invention uses a low-toxicity, low-boiling-point weakly polar solvent to replace highly toxic solvents such as acetonitrile. The combination of the two achieves a good dispersion effect on the first mixture under the premise of low toxicity, and is easily removed by vacuum drying.

[0054] In a specific embodiment of the present invention, in step S2, the volume ratio of toluene to 1,2-dimethoxyethane is 3:1 to 1:1, specifically 3:1, 2:1, 1:1, or any value between the two. When the proportion of toluene is higher, the overall polarity of the organic solvent system is lower, and the cost is also lower; when the proportion of DME increases, the polarity of the organic solvent system increases, and the dispersion and reaction promotion effect on polar components is more obvious.

[0055] In a specific embodiment of the present invention, the mixing operation in step S2 is ultrasonic dispersion, which can be: ultrasonic dispersion at room temperature for 30 min to 60 min to form a uniform suspension, thereby achieving atomic-level uniform mixing and creating conditions for subsequent first heat treatment reaction.

[0056] In a specific embodiment of the present invention, in step S2, the temperature of the first heat treatment is 80℃~120℃, specifically 80℃, 90℃, 100℃, 110℃, 120℃, and any value between any two of the above; the time of the first heat treatment is 6h~12h, specifically 6h, 7h, 8h, 9h, 10h, 11h, 12h, and any value between any two of the above. The present invention selects the above-mentioned first heat treatment parameters, which are sufficient to provide energy to promote the dissolution-recrystallization process between particles, while avoiding premature rapid crystallization that leads to uneven composition.

[0057] After obtaining the second mixture, the second mixture is subjected to a second heat treatment to obtain a sulfide solid electrolyte. Specifically, this stage completes the final crystallization under a mild reducing atmosphere.

[0058] In a specific embodiment of the present invention, step S3, prior to the second heat treatment, further includes: vacuum filtering the second mixture obtained in S2, vacuum drying the resulting precipitate at 120°C~150°C for 8h~12h to remove residual organic solvent, obtaining powder, and then pressing the powder into sheet-like preforms. Tableting is not a necessary step; the powder state can also undergo the second heat treatment, but tableting helps to obtain a denser and more uniform final sample. The shape of the sheet-like preforms is not limited to circular sheets; it can be square sheets or other shapes.

[0059] In a specific embodiment of the present invention, in step S3, the reaction atmosphere of the second heat treatment includes H2S. Specifically, the sheet-like preform is placed in a sealed quartz tube, and after evacuation, a mixture of H2S and Ar is introduced. The volume fraction of H2S in the reaction atmosphere is 1% to 5%, specifically 1%, 2%, 3%, 4%, 5%, or any value between these two. H2S is a reducing sulfur source atmosphere. The H2S atmosphere can effectively suppress the loss of sulfur at high temperatures, repair sulfur vacancies, and simultaneously promote the uniform substitution of M and Q elements and the stable doping of O atoms, forming the target crystal structure.

[0060] In a specific embodiment of the present invention, in step S3, the temperature of the second heat treatment is 450℃~550℃, specifically 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, and any value between the above two. If the temperature is too low, crystallization will be incomplete; if the temperature is too high, excessive sulfur volatilization or the formation of impurity phases may occur. The present invention selects the above-mentioned second heat treatment temperature, and the controllable heat treatment process avoids high-temperature sulfur volatilization, resulting in good product consistency.

[0061] In a specific embodiment of the present invention, in step S3, the second heat treatment time is 2h~5h, specifically 2h, 3h, 4h, 5h, and any value between the two mentioned above; the present invention selects the above heat treatment time to ensure sufficient crystal growth and element diffusion.

[0062] In a specific embodiment of the present invention, in step S3, the heating rate of the second heat treatment is 2℃ / min to 5℃ / min, specifically 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, and any value between the two mentioned above; the present invention selects the above heating rate, which is beneficial to the stable growth of crystals and avoids thermal stress or uneven composition caused by excessively rapid heating.

[0063] According to another aspect of the present invention, a solid-state battery is provided, comprising a positive electrode, a negative electrode, and a solid electrolyte membrane; The solid electrolyte membrane includes the sulfide solid electrolyte described in the above technical solution or the sulfide solid electrolyte prepared by the preparation method described in the above technical solution.

[0064] In a specific embodiment of the present invention, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector along its thickness direction; wherein, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector. The positive current collector may be aluminum foil.

[0065] In a specific embodiment of the present invention, the positive electrode active material layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder; wherein, the positive electrode active material includes, but is not limited to, one or more of lithium iron phosphate, lithium iron manganese oxide, and lithium manganese iron phosphate; the positive electrode conductive agent includes, but is not limited to, one or more of conductive carbon, conductive carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; the positive electrode binder includes, but is not limited to, one or more of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). The present invention does not impose any special restrictions on the source of the above-mentioned positive electrode active material, positive electrode binder, and positive electrode conductive agent; commercially available products well known to those skilled in the art can be used.

[0066] In a specific embodiment of the present invention, the positive electrode sheet can be prepared by the following method: First, the raw materials are mixed in a solvent in a certain proportion to form a slurry, and then the positive electrode slurry is coated onto a positive electrode current collector, and dried and rolled to obtain the positive electrode sheet. The solvent is preferably N-methylpyrrolidone (NMP).

[0067] In a specific embodiment of the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector; wherein, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector may be made of copper foil.

[0068] In a specific embodiment of the present invention, the negative electrode active material layer includes a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent; wherein, the negative electrode active material includes, but is not limited to, natural graphite, artificial graphite, hard carbon, soft carbon, mesophase carbon microspheres, silicon-carbon composite materials, and SiO2. x One or more of the following are acceptable: the negative electrode binder includes, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS); the negative electrode conductive agent includes, but is not limited to, one or more of the following: conductive carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. This invention does not impose any special restrictions on the source of the above-mentioned negative electrode active material, negative electrode binder, and negative electrode conductive agent; commercially available products well known to those skilled in the art can be used.

[0069] In a specific embodiment of the present invention, the negative electrode sheet can be prepared by the following method: First, the raw materials are mixed in a solvent in a certain proportion to form a slurry, and then the negative electrode slurry is coated onto a negative electrode current collector, and dried and rolled to obtain the negative electrode sheet. The solvent is preferably water.

[0070] In a specific embodiment of the present invention, a solid-state battery can be prepared by assembling a positive electrode, a solid electrolyte membrane, and a negative electrode into a button cell according to the conventional battery assembly sequence, and then encapsulating it to obtain a solid-state battery. The specific conditions and parameters for each step in the above preparation process can be achieved using techniques well-known to those skilled in the art for preparing solid-state batteries; the present invention does not impose any special limitations on these aspects.

[0071] To further illustrate the present invention, the following embodiments are provided for detailed description. All raw materials used in the following embodiments of the present invention are commercially available.

[0072] Example 1 S1. In an argon glove box (O2≤0.1ppm, H2O≤0.1ppm), 1.47g Li2S, 3.222g P2S5, 0.236g Ga2S3, 0.137g GeS2, 0.06g Li2O and 0.107g NH4Cl were placed into a ball mill jar for the first ball milling. The ball milling medium was ZrO2, the ball-to-material ratio was 30:1, the rotation speed was 500rpm, and the ball milling was carried out for 4 hours to obtain the first mixture.

[0073] S2. Transfer the first mixture to a glove box, add 15 mL of a mixed organic solvent of toluene and 1,2-dimethoxyethane (volume ratio 2:1), and ultrasonically disperse for 45 min to form a uniform suspension. Transfer the suspension to a 50 mL polytetrafluoroethylene-lined reactor and heat-treat at 100 °C for 10 h to obtain the second mixture.

[0074] S3. The second mixture is vacuum filtered, and the resulting precipitate is vacuum dried at 140°C for 10 hours to obtain powder. The powder is then pressed into sheet-like preforms with a diameter of 10 mm and a thickness of about 1 mm.

[0075] S4. Place the sheet-like preform in a sealed quartz tube, evacuate, and then fill with Ar gas containing 3% H2S (pressure 0.05 MPa). Heat to 500℃ at a rate of 3℃ / min, hold for 3 hours, then program the temperature down to 200℃ (2℃ / min) and allow to cool naturally to room temperature to obtain the sulfide solid electrolyte, denoted as Li. 6.8 Ga 0.2 P 2.9 Ge 0.1 S 10.8 O 0.2 .

[0076] Example 2 S1. In an argon glove box (O2≤0.1ppm, H2O≤0.1ppm), 1.539g Li2S, 3.111g P2S5, 0.075g Al2S3, 0.274g GeS2, 0.03g Li2O and 0.053g NH4Cl were placed into a ball mill jar for the first ball milling. The ball milling medium was ZrO2, the ball-to-material ratio was 30:1, the rotation speed was 450rpm, and the ball milling was carried out for 5 hours to obtain the first mixture.

[0077] S2. Transfer the first mixture to a glove box, add 15 mL of a mixed organic solvent of toluene and 1,2-dimethoxyethane (volume ratio 3:1), and ultrasonically disperse for 60 min to form a uniform suspension. Transfer the suspension to a 50 mL polytetrafluoroethylene-lined reactor and heat-treat at 80 °C for 12 h to obtain the second mixture.

[0078] S3. The second mixture is vacuum filtered, and the resulting precipitate is vacuum dried at 120°C for 12 hours to obtain powder. The powder is then pressed into sheet-like preforms with a diameter of 10 mm and a thickness of about 1 mm.

[0079] S4. Place the sheet-like preform in a sealed quartz tube, evacuate, and then fill with Ar gas containing 1% H2S (pressure 0.05 MPa). Heat to 450℃ at a rate of 2℃ / min, hold for 5 hours, then program the temperature down to 200℃ at 2℃ / min, and allow to cool naturally to room temperature to obtain the sulfide solid electrolyte, denoted as Li. 6.9 Al 0.1 P 2.8 Ge 0.2 S 10.9 O 0.1 .

[0080] Example 3 S1. In an argon glove box (O2≤0.1ppm, H2O≤0.1ppm), 1.401g Li2S, 2.778g P2S5, 0.489g In2S3, 0.461g SiS2, 0.09g Li2O and 0.16g NH4Cl were placed into a ball mill jar for the first ball milling. The ball milling medium was ZrO2, the ball-to-material ratio was 30:1, the rotation speed was 600rpm, and the ball milling was carried out for 2 hours to obtain the first mixture.

[0081] S2. Transfer the first mixture to a glove box, add 15 mL of a mixed organic solvent of toluene and 1,2-dimethoxyethane (volume ratio 1:1), and ultrasonically disperse for 30 min to form a uniform suspension. Transfer the suspension to a 50 mL polytetrafluoroethylene-lined reactor and heat-treat at 120 °C for 6 h to obtain the second mixture.

[0082] S3. The second mixture is vacuum filtered, and the resulting precipitate is vacuum dried at 150°C for 8 hours to obtain powder. The powder is then pressed into sheet-like preforms with a diameter of 10 mm and a thickness of about 1 mm.

[0083] S4. Place the sheet-like preform in a sealed quartz tube, evacuate, and then fill with Ar gas containing 5% H2S (pressure 0.05 MPa). Heat to 550℃ at a rate of 5℃ / min, hold for 2 hours, then program the temperature down to 200℃ (2℃ / min) and allow to cool naturally to room temperature to obtain the sulfide solid electrolyte, denoted as Li. 6.7 In 0.3 P 2.5 Si 0.5 S 10.7 O 0.3 .

[0084] Comparative Example 1 S1. In an argon glove box (O2≤0.1ppm, H2O≤0.1ppm), 1.47g Li2S, 3.222g P2S5, 0.236g Ga2S3, 0.137g GeS2, 0.03g Li2O and 0.085g LiCl were placed into a ball mill jar for the first ball milling. The ball milling medium was ZrO2, the ball-to-material ratio was 30:1, the rotation speed was 500rpm, and the ball milling was carried out for 12h to obtain powder.

[0085] S2. Place the powder in a sealed quartz tube, evacuate it, and then fill it with Ar gas containing 3% H2S (pressure 0.05MPa). Heat the powder to 500℃ at a heating rate of 3℃ / min, hold it at that temperature for 5h, and then cool it down to 200℃ at a programmed temperature (2℃ / min) and then let it cool naturally to room temperature to obtain sulfide solid electrolyte powder.

[0086] Comparative Example 2 S1. In an argon glove box (O2≤0.1ppm, H2O≤0.1ppm), 1.47g Li2S, 3.222g P2S5, 0.236g Ga2S3, and 0.137g GeS2 were dissolved in 20mL acetonitrile. After stirring for 24h, the solution was transferred to a 50mL polytetrafluoroethylene-lined reactor and dried under vacuum at 60℃ for 10h to allow the solvent to fully evaporate, resulting in a powder.

[0087] S2. Place the powder in a sealed quartz tube, evacuate it, and then fill it with Ar gas containing 3% H2S (pressure 0.05MPa). Heat the powder to 500℃ at a heating rate of 3℃ / min, hold it at that temperature for 5h, and then cool it down to 200℃ at a programmed cooling rate of 2℃ / min before allowing it to cool naturally to room temperature to obtain sulfide solid electrolyte powder.

[0088] Comparative Example 3 S1. In an argon glove box (O2≤0.1ppm, H2O≤0.1ppm), 1.562g Li2S, 3.222g P2S5, 0.236g Ga2S3, and 0.137g GeS2 were placed into a ball mill jar for the first ball milling. The ball milling medium was ZrO2, the ball-to-material ratio was 30:1, the rotation speed was 500 rpm, and the ball milling was carried out for 4 hours to obtain the first mixture.

[0089] S2. Transfer the first mixture to a glove box, add 15 mL of a mixed organic solvent of toluene and 1,2-dimethoxyethane (volume ratio 2:1), and ultrasonically disperse for 45 min to form a uniform suspension. Transfer the suspension to a 50 mL polytetrafluoroethylene-lined reactor and heat-treat at 100 °C for 10 h to obtain the second mixture.

[0090] S3. The second mixture is vacuum filtered, and the resulting precipitate is vacuum dried at 140°C for 10 hours to obtain powder. The powder is then pressed into sheet-like preforms with a diameter of 10 mm and a thickness of about 1 mm.

[0091] S4. Place the sheet-like preform in a sealed quartz tube, evacuate the tube, and then fill it with Ar gas containing 3% H2S (pressure 0.05MPa). Heat the tube to 500℃ at a heating rate of 3℃ / min, hold for 3 hours, then cool it down to 200℃ at a programmed rate of 2℃ / min, and then allow it to cool naturally to room temperature to obtain the sulfide solid electrolyte.

[0092] Comparative Example 4 S1. In an argon glove box (O2≤0.1ppm, H2O≤0.1ppm), 1.539g Li2S, 3.334g P2S5, 0.118g Ga2S3, 0.03g Li2O and 0.053g NH4Cl were placed into a ball mill jar for the first ball milling. The ball milling medium was ZrO2, the ball-to-material ratio was 30:1, the rotation speed was 500rpm, and the ball milling was carried out for 4 hours to obtain the first mixture.

[0093] S2. Transfer the first mixture to a glove box, add 15 mL of a mixed organic solvent of toluene and 1,2-dimethoxyethane (volume ratio 2:1), and ultrasonically disperse for 45 min to form a uniform suspension. Transfer the suspension to a 50 mL polytetrafluoroethylene-lined reactor and heat-treat at 100 °C for 10 h to obtain the second mixture.

[0094] S3. The second mixture is vacuum filtered, and the resulting precipitate is vacuum dried at 140°C for 10 hours to obtain powder. The powder is then pressed into sheet-like preforms with a diameter of 10 mm and a thickness of about 1 mm.

[0095] S4. Place the sheet-like preform in a sealed quartz tube, evacuate, and then fill with Ar gas containing 3% H2S (pressure 0.05 MPa). Heat to 500℃ at a rate of 3℃ / min, hold for 3 hours, then program the temperature down to 200℃ (2℃ / min) and allow to cool naturally to room temperature to obtain the sulfide solid electrolyte, denoted as Li. 6.9 Ga 0.1 P3S 10.9 O 0.1 .

[0096] Performance testing: The sulfide solid electrolyte powders obtained in Comparative Examples 1-2 were pressed into discs with a thickness of about 1 mm. Gold electrodes were sputtered on both sides of the sulfide solid electrolytes obtained in Examples 1-9 and Comparative Examples 1-4. The room temperature ionic conductivity was measured by electrochemical impedance spectroscopy. The sulfide solid electrolytes were exposed in a dry room with a humidity of 5%, and samples were taken at regular intervals to test their ionic conductivity retention rate, thus obtaining their air stability.

[0097] The test results are shown in Table 1 below.

[0098] Table 1 Performance Test Results As shown in Table 1, the mechanochemical-liquid phase synergistic synthesis method of the present invention (Examples 1-6) has significant advantages over the traditional single solid phase (Comparative Example 1) and single liquid phase (Comparative Example 2), with a substantial improvement in both ionic conductivity and air stability. Examples 1 and 3 demonstrate that the introduction of the defect modifier (Li₂O / NH₄Cl) is key to achieving high air stability; its provided O doping and in-situ generated micropores synergistically optimize electrolyte performance. Examples 1-3 and 4 show that M / Q co-substitution (Examples 1-3) has a synergistic enhancement effect compared to single doping (Comparative Example 4), simultaneously optimizing lithium-ion migration channels and structural stability.

[0099] In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment 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, 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, without contradiction. Additionally, it should be noted that in this specification, 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 indicated technical features.

[0100] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sulfide solid-state electrolyte, characterized by, Li 7-x M x P 3-y Q y S 11-x O x wherein M is selected from at least one of Al, Ga and In, Q is selected from at least one of Si, Ge, Sn, Sb, Mo, Zn, Nb, Ta and La, 0.05≤x≤0.3, 0.1≤y≤0.5; The room temperature ionic conductivity of the sulfide solid electrolyte is ≥ 6.8 x 10 -3 S cm -1 , and the ion conductivity retention rate is ≥ 79% after exposure in an environment with a relative humidity of 5% for 30 min.

2. A method of producing the sulfide solid electrolyte according to claim 1, characterized by, Includes the following steps: S1. Mix the lithium source, phosphorus source, M source, Q source and defect modifier to obtain a first mixture containing sulfur. S2. The first mixture obtained in S1 is mixed with an organic solvent and subjected to a first heat treatment reaction to obtain a second mixture; S3. The second mixture obtained in S2 is subjected to a second heat treatment to obtain a sulfide solid electrolyte.

3. The method of claim 2, wherein, In step S1, the defect control agent includes a eutectic mixture of Li2O and NH4Cl; And / or, the mixing is carried out under an inert atmosphere; And / or, the specific operation of the mixing is ball milling.

4. The production method according to claim 3, characterized by, In step S1, the molar ratio of Li2O to NH4Cl is 1:1 to 2:

1.

5. The preparation method according to claim 2, characterized in that, In step S2, the organic solvents include toluene and 1,2-dimethoxyethane; And / or, the specific operation of the mixing is ultrasonic dispersion; And / or, the temperature of the first heat treatment is 80℃~120℃; And / or, the duration of the first heat treatment is 6h to 12h.

6. The preparation method according to claim 5, characterized in that, In step S2, the volume ratio of toluene to 1,2-dimethoxyethane is 3:1 to 1:

1.

7. The preparation method according to claim 2, characterized in that, In step S3, before the second heat treatment, the process further includes: vacuum filtering the second mixture obtained in S2, vacuum drying the obtained precipitate at 120℃~150℃ for 8h~12h to obtain powder, and then pressing the powder into sheet-like preforms.

8. The preparation method according to claim 2, characterized in that, In step S3, the reaction atmosphere of the second heat treatment includes H2S; And / or, the temperature of the second heat treatment is 450℃~550℃; And / or, the duration of the second heat treatment is 2h to 5h; And / or, the heating rate of the second heat treatment is 2℃ / min to 5℃ / min.

9. The production method according to claim 8, characterized by, In step S3, the volume fraction of H2S in the reaction atmosphere is 1% to 5%.

10. A solid-state battery, characterized by, Including positive electrode, negative electrode, and solid electrolyte membrane; The solid electrolyte membrane includes the sulfide solid electrolyte of claim 1 or the sulfide solid electrolyte prepared by the preparation method of any one of claims 2 to 9.

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