Solid electrolyte material, preparation method, electrolyte layer and lithium ion battery

Abstract

The invention relates to the technical field of solid electrolyte materials, in particular to a solid electrolyte material, a preparation method, an electrolyte layer and a lithium ion battery, the chemical general formula of the solid electrolyte material is LiaPSbClcBrdFe, 5.3 < = a < 6, 4.3 < = b < 5, 0.8 < = c < 1.7, 0 < = d < 0.9, and 0 < e < = 0.2; the solid electrolyte material is in the form of powder particles, the powder particle size D50 of the solid electrolyte material is less than or equal to 3 microns, and the particle size distribution Span value is less than or equal to 2; the F element is distributed on the surfaces of powder particles, and the distribution depth is less than or equal to 100nm. The F element is only distributed on the surface, and the distribution depth is less than or equal to 100nm, so that a stable protective layer structure can be constructed on the surface layer of the particle, the air stability and the chemical stability are optimized, meanwhile, side reaction with an electrode material is inhibited, the cycle life of a battery is prolonged, and the air stability of the material is fundamentally improved; the air stability, the solvent stability and the electrochemical cycle stability of the solid electrolyte are remarkably improved while the solid electrolyte material can keep high ionic conductivity and good mechanical performance, and popularization is facilitated.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte materials technology, specifically to a solid electrolyte material, a preparation method, an electrolyte layer, and a lithium-ion battery. Background Technology

[0002] Solid-state batteries are widely regarded as a crucial upgrade direction for future power batteries, and their performance and mass production capabilities directly influence the pace of their commercialization. Currently, the most researched and applied solid electrolytes are mainly classified into four categories: oxides, sulfides, halides, and polymers. Among them, sulfides have attracted much attention due to their high ionic conductivity and good interfacial contact performance, but their particle size has a significant impact on battery performance.

[0003] Sulfide solid electrolytes can still hydrolyze even under extremely low humidity conditions, releasing corrosive and harmful gases such as H2S, leading to structural collapse and performance degradation. When particle size is reduced to the micrometer and nanometer scale, their specific surface area increases dramatically, drastically increasing their sensitivity to moisture. This necessitates that material preparation, storage, transportation, and battery assembly be carried out in strictly humidity-controlled environments, significantly increasing industrialization costs. Furthermore, sulfide systems also suffer from a low electrochemical stability window and are prone to interfacial side reactions with electrodes, further hindering their widespread adoption in all-solid-state batteries.

[0004] Improving air stability and interfacial compatibility while maintaining advantages such as high ionic conductivity is a research direction for the sulfide all-solid-state battery industry. Summary of the Invention

[0005] (a) Purpose of the invention The purpose of this invention is to provide a solid electrolyte material, preparation method, electrolyte layer and lithium-ion battery that can improve air stability, solvent stability and cycle stability while maintaining high ionic conductivity and good mechanical strength.

[0006] (II) Technical Solution To address the above problems, the present invention provides a solid electrolyte material, comprising: the solid electrolyte material having the general chemical formula Li a PS b Cl c Br d F e Where 5.3≤a<6, 4.3≤b<5, 0.8≤c<1.7, 0≤d<0.9, 0<e≤0.2; the solid electrolyte material is in the form of powder particles, and the particle size D of the solid electrolyte material is... 50 ≤3 micrometers and particle size distribution Span value ≤2; F element is distributed on the surface of powder particles and the distribution depth is ≤100nm.

[0007] In another aspect of the invention, preferably, 5.3≤a≤5.6, 4.3≤b≤4.6, 1.3≤c<1.6, d=0, and 0.05≤e≤0.1.

[0008] In another aspect of the invention, preferably, 5.3≤a≤5.6, 4.3≤b≤4.6, 0.8≤c≤1, 0.6≤d≤0.85, and 0.05≤e≤0.1.

[0009] In another aspect of the present invention, preferably, the particle size D of the solid electrolyte material is... 50 ≤1 micrometer and particle size distribution Span value≤2, F element distribution depth on the surface of powder particles≤50nm.

[0010] In another aspect, preferably, a method for preparing a solid electrolyte material is provided, the method being applicable to the solid electrolyte material as described above, the method comprising the following steps: Step 100: Mix and grind the raw materials used to form the solid electrolyte material to obtain a mixture; Step 200: The mixture is subjected to solid-state sintering to obtain the first reactant; Step 300: Perform particle size treatment on the first reactant to obtain the second reactant; Step 400: Perform surface treatment on the second reactant to obtain the third reactant; Step 500: Anneal the third reactant to obtain a solid electrolyte material.

[0011] In another aspect of the present invention, preferably, the raw materials of the solid electrolyte material used in step 100 include: Li2S, P2S5 and LiCl or Li2S, P2S5, LiCl and LiBr.

[0012] In another aspect of the present invention, preferably, the solid-state sintering conditions in step 200 include: a temperature of 450°C to 600°C; a time of 6 hours to 15 hours; and a protective atmosphere including argon or nitrogen.

[0013] In another aspect of the present invention, preferably, the particle size treatment in step 300 includes ball milling, air jet milling, dry sand milling, or wet sand milling.

[0014] In another aspect of the present invention, preferably, the surface treatment in step 400 includes: loading the second reactant into a fluidized bed protected by a protective atmosphere, introducing dry HF gas in the powder fluidization state, controlling the temperature inside the fluidized bed to be between 20°C and 50°C, and the fluidization time to be between 1 min and 20 min, wherein the protective atmosphere includes an argon or nitrogen environment.

[0015] In another aspect of the present invention, preferably, the annealing treatment in step 500 includes: heating the third reactant in a protective atmosphere for 2 h to 10 h, wherein the heating temperature is 200 °C to 300 °C, and the protective atmosphere includes an argon or nitrogen environment.

[0016] In another aspect of the present invention, preferably, an electrolyte layer comprises a solid electrolyte material as described above or a solid electrolyte material prepared by the preparation method described above, wherein the electrolyte layer is formed by pressing the solid electrolyte material.

[0017] In another aspect of the present invention, preferably, a lithium-ion battery includes a positive electrode layer, a negative electrode layer, and an electrolyte layer between the positive and negative electrodes, wherein the electrolyte layer includes a solid electrolyte material as described above, a solid electrolyte material prepared by any of the preparation methods described above, or an electrolyte layer as described above.

[0018] (III) Beneficial Effects The above-described technical solution of the present invention has the following beneficial technical effects: The solid electrolyte material of this invention has F element distributed only on the surface of the solid electrolyte material powder particles with a distribution depth of ≤100nm. It can build a stable protective layer on the particle surface, optimize air stability and chemical stability, and suppress the occurrence of side reactions with electrode materials, extend battery cycle life, and achieve a fundamental improvement in the air stability of the material. This allows the solid electrolyte material to maintain high ionic conductivity and good mechanical properties while significantly improving the air stability, solvent stability and electrochemical cycle stability of the solid electrolyte, which is conducive to its widespread application. Attached Figure Description

[0019] Figure 1 This is the XRD pattern of the electrolyte in Example 1 of the present invention; Figure 2 This is the electrochemical impedance spectroscopy of the electrolyte in Example 1 of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0021] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Example A solid electrolyte material, comprising: the solid electrolyte material having the general chemical formula Li a PS b Cl c Br d F e Where 5.3≤a<6, 4.3≤b<5, 0.8≤c<1.7, 0≤d<0.9, 0<e≤0.2; the solid electrolyte material is in the form of powder particles, and the particle size D of the solid electrolyte material is... 50 The particle size distribution (D50) is ≤3 micrometers and the particle size distribution Span value is ≤2; the phosphorus (F) element is distributed on the surface of the powder particles with a distribution depth ≤100nm. The solid electrolyte in this embodiment is obtained by first controlling the particle size of a sulfide-type solid electrolyte and then uniformly fluorinating the surface at the nanoscale. The particle size (D50) is controlled to be 3 micrometers or less, and the particle size distribution Span value is not greater than 2, to ensure uniform dispersion and dense contact of the material in the electrode layer. Introducing F element into the powder surface forms a chemically stable F-rich surface protective layer, effectively inhibiting the contact between moisture in the air and the active components inside the sulfide, thereby improving the material's air stability, solvent stability, and cycle stability. The shallow distribution significantly improves interfacial stability without affecting the migration channels of the main lattice ions.

[0025] Furthermore, in this embodiment, 5.3≤a≤5.6, 4.3≤b≤4.6, 1.3≤c<1.6, d=0, and 0.05≤e≤0.1 are used to achieve a synergistic improvement in ionic conductivity and air stability, exhibiting high comprehensive electrochemical performance.

[0026] Furthermore, in this embodiment, where 5.3≤a≤5.6, 4.3≤b≤4.6, 0.8≤c≤1, 0.6≤d≤0.85, and 0.05≤e≤0.1, a synergistic improvement in ionic conductivity and air stability is achieved, exhibiting high comprehensive electrochemical performance.

[0027] Furthermore, in this embodiment, the particle size D of the solid electrolyte material is... 50 ≤1 micrometer and particle size distribution Span value≤2, F element distribution depth on the surface of powder particles≤50nm.

[0028] The size of sulfide solid electrolyte particles plays a crucial role in the overall performance of all-solid-state batteries, involving multiple dimensions such as ion transport, electrolyte layer structural integrity, and interface matching with the electrodes. Firstly, from an ion conduction perspective, while smaller particle size facilitates a tighter contact interface with the electrodes, it also increases the number of interfaces, amplifying the accumulated interfacial impedance and reducing overall ion conduction efficiency. Therefore, excessively small particle size may actually decrease macroscopic conductivity. Secondly, the electrolyte layer in the battery serves a dual function as an ion channel and physical barrier; it must be dense enough to block lithium dendrite penetration while remaining as thin as possible to increase energy density. Small-particle solid electrolytes have a larger specific surface area and higher surface energy, making it easier to rearrange and fill pores during compaction, thus constructing an electrolyte layer with fewer defects and higher density, contributing to improved safety and reduced thickness. Furthermore, in the cathode composite structure, the electrolyte needs to be deeply coupled with the cathode active particles. If the solid electrolyte particles are too large, it is not only difficult to uniformly fill the interparticle gaps but also increases the volume fraction of the electrolyte in the cathode, sacrificing the proportion of active material usable for energy storage reactions. Ideally, the electrolyte particle size should be similar to that of the cathode material to achieve efficient ion transport and ensure high energy density. Therefore, particle size design is not a single objective, but a balance of various performance requirements. This embodiment employs a differentiated particle size optimization strategy: the solid electrolyte used in the cathode composite layer has a particle size D50 controlled at 1 micrometer or less, and a particle size distribution Span ≤ 2, which is optimally matched with 3 to 5 micrometer-sized cathode particles, improving interfacial contact quality. The material used in the electrolyte separator layer has a particle size D50 controlled within 3 micrometers, and a Span ≤ 2, which maintains excellent compactness and high ionic conductivity while helping to reduce the electrolyte layer thickness as much as possible. By controlling the particle size distribution, the synergistic optimization of ion conduction, mechanical compactness, and interfacial contact is achieved, enabling the solid electrolyte of this embodiment to achieve performance balance and maximize overall efficiency in actual battery structures.

[0029] Poor air stability is another significant drawback restricting the industrial application of sulfide solid electrolytes based on argillium sulfide. The smaller the particle size and the larger the specific surface area, the more pronounced the air stability problem becomes. Replacing some of the original halogens in argillium sulfide electrolytes with sulfur (F) can effectively improve the air stability of the electrolyte. The introduction of F enhances the lattice energy, making the crystal structure more compact and suppressing irreversible phase transitions caused by H₂O or O₂ penetration. Furthermore, the high electronegativity of F attracts electrons, reducing the electron density of sulfur and decreasing the amount of sulfur. 2- To S 0The tendency of fluorine doping makes it more difficult to oxidize. Meanwhile, during the first charge-discharge cycle, the fluorine-doped electrolyte forms a LiF-containing interface layer at the interface with the positive and negative electrodes. This interface layer effectively prevents the continuous occurrence of interfacial side reactions during repeated charge-discharge cycles and also resists the growth of lithium dendrites, thus improving cycle stability. Therefore, fluorine doping can improve both the air stability and cycle stability of sulfide electrolytes.

[0030] Existing fluoride doping techniques primarily involve adding fluoride components during synthesis. The resulting electrolyte product exhibits a near-uniform distribution of fluoride (F) on the surface and within the electrolyte particles, thus falling under the category of bulk doping. Under these conditions, maintaining high ionic conductivity requires a very limited amount of F doping, resulting in a relatively limited improvement in the material's air stability, failing to fundamentally address the air stability problem of sulfide electrolytes. Increasing the F doping amount can better improve air stability, but it significantly reduces the electrolyte's ionic conductivity. Therefore, this approach cannot effectively improve the material's air stability while maintaining high ionic conductivity.

[0031] In this embodiment, the F element in the solid electrolyte material is only distributed on the surface of the solid electrolyte material powder particles and the distribution depth is ≤100nm. This is a surface doping technology. After the sulfide solid electrolyte is processed to a suitable particle size, it can fundamentally improve the air stability of the material while maintaining high ionic conductivity and good mechanical strength. At the same time, it can effectively improve its electrochemical cycle stability, thereby significantly improving its overall performance and facilitating its promotion.

[0032] This embodiment also provides a method for preparing a solid electrolyte material, characterized in that the preparation method is applicable to the solid electrolyte material described above, and the preparation method includes the following steps: Step 100: The raw materials used to form the solid electrolyte material are mixed and ground to obtain a mixture. The materials can be taken according to a preset molar ratio of chemical components. Further, in this embodiment, the raw materials used for the solid electrolyte material include: Li₂S, P₂S₅, and LiCl, or Li₂S, P₂S₅, LiCl, and LiBr. The purpose of mixing and grinding is to achieve uniform mixing at the microscale, which is beneficial for achieving high-quality solid-state sintering subsequently.

[0033] Step 200: The mixture is subjected to solid-state sintering to obtain the first reactant. Further, in this embodiment, the solid-state sintering conditions include: a temperature of 450℃~600℃; a time of 6h~15h; and a protective atmosphere including argon or nitrogen. The purpose of solid-state sintering is to drive a controllable chemical reaction between different raw materials under solid-state conditions, thereby synthesizing a solid electrolyte material with a predetermined chemical formula.

[0034] Step 300: Perform particle size treatment on the first reactant to obtain the second reactant. The purpose of particle size treatment is to ensure that the particle size meets the material requirements.

[0035] Step 400: Perform surface treatment on the second reactant to obtain the third reactant; In this embodiment, the surface treatment includes: loading the second reactant into a fluidized bed protected by a protective atmosphere, introducing dry HF gas in the powder fluidization state, controlling the temperature inside the fluidized bed to be between 20°C and 50°C, and the fluidization time to be between 1 min and 20 min, wherein the protective atmosphere includes an argon or nitrogen environment.

[0036] Step 500: Anneal the third reactant to obtain a solid electrolyte material. In this embodiment, the annealing process includes heating the third reactant in a protective atmosphere for 2 to 10 hours, wherein the heating temperature is 200°C to 300°C, and the protective atmosphere includes an argon or nitrogen environment.

[0037] This embodiment utilizes a fluidized bed apparatus to first place the sulfide electrolyte in a powder fluidized state under inert gas protection, followed by the introduction of dry HF gas for low-temperature fluorination. The core function of the powder fluidized bed is to use airflow to suspend solid particles and present them in a fluid-like state, thereby greatly enhancing the contact and reaction between the gas and solid phases. This allows the fluorination reaction on the surface of the sulfide electrolyte to occur uniformly and rapidly at low temperatures. This significantly reduces the fluorination temperature and makes it easy to control the fluorinated layer thickness by adjusting fluorination time and temperature, achieving uniform fluorination at the nanoscale. Based on this method, controllable fluorination of the sulfide electrolyte surface is achieved, enabling the solid electrolyte material to maintain high ionic conductivity and good mechanical strength while fundamentally improving its air stability and effectively enhancing its electrochemical cycling stability. This solution addresses the problem of powders struggling to react uniformly with gases in a static state. It avoids the issue of small-particle-size sulfide electrolytes agglomerating due to increased surface energy, making the gas-solid reaction difficult to occur uniformly on individual particle surfaces. This results in severely uneven fluorinated layer thickness, with some particles lacking a fluorinated layer altogether. It also avoids the need for fluorination reactions that require high temperatures (>300℃) to be effective, where the degree of fluorination is difficult to control and can easily lead to a significant decrease in electrolyte ionic conductivity due to over-fluorination. Furthermore, for small-particle-size sulfide electrolytes, high-temperature post-treatment can easily cause secondary particle growth, and particle size is crucial for the application of sulfide electrolytes.

[0038] For the reasons mentioned above, this embodiment incorporates a low-temperature fluorination process using a fluidized bed. The fluidized bed first places the small-particle-size sulfide electrolyte in a fluid-like state of particle suspension, greatly enhancing the contact and reaction between HF gas and the electrolyte solid. At low temperatures, a nanoscale fluorinated layer is first formed on the surface of the sulfide electrolyte. The thickness of the fluorinated layer is pre-controlled by adjusting the low temperature and processing time. Then, the surface-controlled fluorinated sulfide electrolyte undergoes annealing (temperature not exceeding 300℃) to further stabilize the fluorinated layer structure on the electrolyte surface. At this annealing temperature, the ionic conductivity and other properties of the sulfide electrolyte are significantly improved, while the particle size remains unchanged.

[0039] This embodiment also provides an electrolyte layer, including the solid electrolyte material as described above or the solid electrolyte material prepared by the preparation method described above, wherein the electrolyte layer is formed by pressing the solid electrolyte material.

[0040] This embodiment also provides a lithium-ion battery, including a positive electrode layer, a negative electrode layer and an electrolyte layer between the positive and negative electrodes. The electrolyte layer includes a solid electrolyte material as described above, a solid electrolyte material prepared by any of the preparation methods described above, or an electrolyte layer as described above.

[0041] The following will further illustrate the implementation of the powder material and its preparation method with reference to specific embodiments of the present invention. Unless otherwise specified, the raw materials used in each embodiment are commercially available products, and the process conditions are conventional operating conditions unless otherwise specified.

[0042] Example 1 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 ClBr 0.65 F 0.05 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -70°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, LiCl, and LiBr were weighed in a molar ratio of 1.8:0.5:1.0:0.7. The weighed raw materials were ground into powder and then mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 450°C for 8 hours, followed by natural cooling to obtain the first reactant. The first reactant was first particle-sized using an air jet mill, and then further particle-sized using a ball mill to obtain the second reactant. The second reactant was then loaded into an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 20°C for 5 minutes to obtain the third reactant. The third reactant was then loaded into an argon-protected reactor vessel and heated at 200°C for 3 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 35 nm deep on the surface of the powder particles. Figure 1 This is the XRD pattern of the electrolyte in Example 1 provided by the present invention. Figure 2 This is the electrochemical impedance spectroscopy of the electrolyte in Example 1 provided by the present invention.

[0043] Example 2 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 ClBr 0.6 F 0.1 The preparation method is as follows: The second reactant was prepared using the same process as in Example 1. The second reactant was then placed in an argon-protected fluidized bed (argon purity greater than 99.999%). After the powder entered the fluidized state, dry HF gas was introduced at 40°C for 10 minutes to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 250°C for 5 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 62 nm deep on the surface of the powder particles.

[0044] Example 3 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 ClBr 0.5 F 0.2 The preparation method is as follows: The second reactant was prepared using the same process as in Example 1. The second reactant was then placed in an argon-protected fluidized bed (argon purity greater than 99.999%). After the powder entered the fluidized state, dry HF gas was introduced at 50°C for 20 minutes to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 280°C for 10 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 82 nm deep on the surface of the powder particles.

[0045] Example 4 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 Cl 0.85 Br 0.84 F 0.01 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, LiCl, and LiBr were weighed in a molar ratio of 1.8:0.5:0.85:0.85. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 480°C for 6 hours, followed by natural cooling to obtain the first reactant. The first reactant was subjected to particle size reduction using an air jet mill, followed by a second particle size reduction using a wet sand mill to obtain the second reactant. The second reactant was then loaded into an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 20°C for 1 minute to obtain the third reactant. The third reactant was then loaded into an argon-protected reactor vessel and heated at 200°C for 2 hours to obtain the solid electrolyte. The F element is distributed in a region at a depth of about 17 nm on the surface of the powder particles.

[0046] Example 5 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.4 PS 4.4 Cl 0.8 Br 0.75 F 0.05 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, LiCl, and LiBr were weighed in a molar ratio of 1.9:0.5:0.8:0.8. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 470°C for 12 hours, followed by natural cooling to obtain the first reactant. The first reactant was then subjected to particle size reduction using a dry sand mill to obtain the second reactant. The second reactant was then placed in an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 20°C for 5 minutes to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 200°C for 3 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 47 nm deep on the surface of the powder particles.

[0047] Example 6 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 ClBr 0.65 F 0.05 The preparation method is as follows: The first reactant was prepared using the same process as in Example 1; the first reactant was subjected to particle size reduction using an air jet mill to obtain the second reactant; the second reactant was loaded into an argon-protected fluidized bed with argon purity greater than 99.999%, and after the powder entered the fluidized state, dry HF gas was introduced at a processing temperature of 20°C for 5 minutes to obtain the third reactant; the third reactant was loaded into an argon-protected reactor vessel and heated at 200°C for 3 hours to obtain the solid electrolyte. The fluorine element is distributed in a region approximately 53 nm deep on the surface of the powder particles.

[0048] Example 7 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.4 PS 4.4 ClBr 0.5 F 0.1 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, LiCl, and LiBr were weighed in a molar ratio of 1.9:0.5:1.0:0.6. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 490°C for 10 hours, followed by natural cooling to obtain the first reactant. The first reactant was then subjected to particle size reduction using an air jet mill to obtain the second reactant. The second reactant was then placed in an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 30°C for 10 minutes to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 200°C for 5 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 67 nm deep on the surface of the powder particles.

[0049] Example 8 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.4 PS 4.4 Cl 1.5 Br 0.05 F 0.05 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, LiCl, and LiBr were weighed in a molar ratio of 1.9:0.5:0.9:0.7. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 520°C for 10 hours, followed by natural cooling to obtain the first reactant. The first reactant was subjected to particle size reduction using an air jet mill, followed by a secondary particle size reduction using a ball mill to obtain the second reactant. The second reactant was then loaded into an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 30°C for 5 minutes to obtain the third reactant. The third reactant was then loaded into an argon-protected reactor vessel and heated at 250°C for 3 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 37 nm deep on the surface of the powder particles.

[0050] Example 9 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.7 PS 4.7 ClBr 0.25 F 0.05 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, LiCl, and LiBr were weighed in a molar ratio of 2.2:0.5:1:0.3. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 480°C for 8 hours, followed by natural cooling to obtain the first reactant. The first reactant was subjected to particle size reduction using an air jet mill, followed by a secondary particle size reduction using a ball mill to obtain the second reactant. The second reactant was then loaded into an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 40°C for 5 minutes to obtain the third reactant. The third reactant was then loaded into an argon-protected reactor vessel and heated at 250°C for 3 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 23 nm deep on the surface of the powder particles.

[0051] Example 10 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 Cl 1.69 F 0.01 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, and LiCl were weighed in a molar ratio of 1.8:0.5:1.7. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 500°C for 8 hours, followed by natural cooling to obtain the first reactant. The first reactant was subjected to particle size reduction using an air jet mill to obtain the second reactant. The second reactant was then placed in an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 50°C for 1 minute to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 200°C for 2 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 21 nm deep on the surface of the powder particles.

[0052] Example 11 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 Cl 1.6 F 0.1 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, and LiCl were weighed in a molar ratio of 1.8:0.5:1.7. The weighed raw materials were ground into powder and then mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 500°C for 8 hours, followed by natural cooling to obtain the first reactant. The first reactant was first subjected to particle size reduction using an air jet mill, and then to particle size reduction using a sand mill. The second reactant was loaded into an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 50°C for 10 minutes to obtain the third reactant. The third reactant was then loaded into an argon-protected reactor vessel and heated at 200°C for 8 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 63 nm deep on the surface of the powder particles.

[0053] Example 12 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 Cl 1.5 F 0.2 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, and LiCl were weighed in a molar ratio of 1.8:0.5:1.7. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 500°C for 8 hours, followed by natural cooling to obtain the first reactant. The first reactant was subjected to particle size reduction using an air jet mill to obtain the second reactant. The second reactant was then placed in an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 50°C for 20 minutes to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 300°C for 10 hours to obtain the solid electrolyte. The fluorine element was distributed in a region approximately 91 nm deep on the surface of the powder particles.

[0054] Example 13 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.4 PS 4.4 Cl 1.5 F 0.1 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, and LiCl were weighed in a molar ratio of 1.9:0.5:1.6. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 550°C for 10 hours, followed by natural cooling to obtain the first reactant. The first reactant was then subjected to particle size reduction using an air jet mill to obtain the second reactant. The second reactant was then placed in an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 50°C for 10 minutes to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 300°C for 5 hours to obtain the solid electrolyte. The F element was distributed in a region approximately 59 nm deep on the surface of the powder particles.

[0055] Example 14 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.6 PS 4.6 Cl 1.35 F 0.05 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, and LiCl were weighed in a molar ratio of 2.1:0.5:1.4. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 560°C for 12 hours, followed by natural cooling to obtain the first reactant. The first reactant was subjected to particle size reduction using an air jet mill to obtain the second reactant. The second reactant was then placed in an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 50°C for 5 minutes to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 250°C for 5 hours to obtain the solid electrolyte. The F element was distributed in a region approximately 57 nm deep on the surface of the powder particles.

[0056] Example 15 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.99 PS 4.99 Cl1F 0.01 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, and LiCl were weighed in a molar ratio of 2.5:0.5:1. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 600°C for 15 hours, followed by natural cooling to obtain the first reactant. The first reactant was subjected to particle size reduction using an air jet mill to obtain the second reactant. The second reactant was then placed in an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 50°C for 1 minute to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 250°C for 10 hours to obtain the solid electrolyte. The F element was distributed in a region approximately 19 nm deep on the surface of the powder particles.

[0057] Example 16 This embodiment provides a surface-fluorinated sulfide electrolyte material with the chemical formula Li. 5.65 PS 4.65 Cl 1.3 F 0.05 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, and LiCl were weighed in a molar ratio of 2.15:0.5:1.35. The weighed raw materials were ground into powder and mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at 560°C for 12 hours, followed by natural cooling to obtain the first reactant. The first reactant was then subjected to particle size reduction using an air jet mill to obtain the second reactant. The second reactant was then placed in an argon-protected fluidized bed with argon purity greater than 99.999%. After the powder entered the fluidized state, dry HF gas was introduced at 50°C for 4 minutes to obtain the third reactant. The third reactant was then placed in an argon-protected reactor vessel and heated at 250°C for 10 hours to obtain the solid electrolyte. The F element was distributed in a region approximately 43 nm deep on the surface of the powder particles.

[0058] Comparative Example 1 This comparative example provides a sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 Cl1Br 0.7 The preparation method is as follows: Under a dry, high-purity argon atmosphere with a dew point of -75°C and a purity greater than or equal to 99.999%, Li₂S, P₂S₅, LiCl, and LiBr were weighed in a molar ratio of 1.8:0.5:1:0.7. The weighed raw materials were ground into powder and then mixed to obtain a mixture. The mixture was then subjected to solid-state sintering at a temperature of 470°C for 15 hours. After natural cooling, the first reactant was obtained. After natural cooling, the particle size of the first reactant was adjusted using an air jet mill to obtain the sulfide solid electrolyte.

[0059] Comparative Example 2 This comparative example provides a sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 ClBr 0.7 The preparation method is as follows: The treatment method is exactly the same as that of Comparative Example 1, except that after the particle size is treated by air jet mill, a secondary particle size treatment is performed by ball mill.

[0060] Comparative Example 3 This comparative example provides a bulk-doped sulfide electrolyte material with the chemical formula Li. 5.3 PS 4.3 ClBr 0.65 F 0.05 The preparation method is as follows: Under a dry, high-purity argon atmosphere, Li₂S, P₂S₅, LiCl, LiBr, and LiF were weighed in a molar ratio of 1.8:0.5:1:0.65:0.05. The weighed raw materials were ground into powder, mixed, and sintered at a temperature of 480°C for 15 hours. After natural cooling, the particle size was adjusted using an air jet mill to obtain the sulfide solid electrolyte, wherein the F element is distributed in bulk in the powder particles.

[0061] Performance testing: ① Ionic conductivity test: Under an argon atmosphere, weigh 150 mg of electrolyte powder prepared in the examples and comparative examples, place it in an insulating test mold sleeve, apply a pressing pressure of 300 MPa, and record the thickness of the electrolyte sheet after pressing as L (in cm) and the cross-sectional area of ​​the electrolyte sheet as S (in cm²). 2Subsequently, an AC impedance test was performed using a test mold. The obtained impedance value was recorded as R, in Ω. The ionic conductivity of the electrolyte material was calculated using the formula σ = L / (R·S), in S / cm. Assembly and testing were conducted under an inert atmosphere, and the test was performed at room temperature (25℃). ② Ion conductivity retention test: After the ionic conductivity test shown in ①, the room temperature ionic conductivity of the sample was recorded as σ0. A 500mg sample was placed in a -45℃ dew point environment for 24 hours, and the room temperature ionic conductivity after this period was measured using the same method as in ①, and recorded as σ0. t , with σ t / σ0×100% is denoted as the retention rate of ionic conductivity.

[0062] Table 1. Particle size and ionic conductivity test results of Examples 1-15 and Comparative Examples 1-3 In Examples 1-15, under the same particle size conditions, as the amount of F element doping on the surface of the electrolyte powder particles increased, the ionic conductivity gradually decreased to a certain extent, but the ionic conductivity retention rate increased significantly. Comparing Example 6 (with the same Li content and particle size of approximately 3 μm) with Comparative Example 1, the ionic conductivity of the electrolyte material after surface F doping decreased from 7.41 mS / cm to 6.97 mS / cm, but the ionic conductivity retention rate increased from 53.2% to 91.7%, showing a significant improvement. This indicates that the present invention can significantly improve the air stability of the material while maintaining the high ionic conductivity characteristics of the electrolyte. Similarly, for Example 8 and Comparative Example 2 (with the same Li content and particle size of less than 1 μm), the effect of surface F doping on improving the air stability of the material can also be observed.

[0063] Furthermore, comparing Example 6 with Comparative Example 3, which has the same Li content, elemental doping amount, and particle size, it can be found that both surface and bulk doping methods involved in Example 6 and Comparative Example 3 can improve the ionic conductivity retention rate of the material. However, the 91.7% ionic conductivity retention rate achieved by the surface-doped Example 6 is significantly better than the 75.4% ionic conductivity retention rate achieved by the bulk-doped Comparative Example 3. Moreover, the ionic conductivity of Example 6 is significantly better than that of Comparative Example 3, indicating that the surface nanoscale uniform doping achieved by the present invention can maintain the high ionic conductivity characteristics of the electrolyte material while improving the air stability of the material.

[0064] ② Solid-state battery cycle performance test: Under an argon atmosphere, the solid electrolyte, NCM811 cathode, and conductive carbon black prepared in the examples and comparative examples were weighed in a ratio of 20:75:5 and uniformly mixed to prepare a composite cathode material. 70 mg of solid electrolyte was added to an insulating test sleeve with a diameter of 10 mm, and a pressure of 300 MPa was applied and held for 120 seconds to form the solid electrolyte layer. 20 mg of the resulting composite cathode material was poured into one side of the pre-pressed electrolyte layer, and a pressure of 360 MPa was applied and held for 120 seconds to form the composite cathode material. A lithium-indium alloy sheet was then inserted into the other side of the electrolyte layer, and a pressure of 80 MPa was applied to form the composite cathode material. A positive electrode composite layer, a solid electrolyte layer, a lithium indium alloy sheet, and stainless steel current collectors on both sides constitute an all-solid-state battery for testing (Note that if the D50 of the example is 1~3μm, it is used for the electrolyte layer, and the corresponding electrode layer uses an electrolyte with the same chemical formula but D50 < 1μm; if the D50 of the example is < 1μm, it is used for the electrode layer, and the electrolyte layer uses an electrolyte with the same chemical formula but D50 = 1~3μm).

[0065] The assembled all-solid-state battery pack was placed in a 25°C constant temperature chamber for cycle performance testing. The test conditions included initial charge-discharge performance and cycle charge-discharge performance testing of the solid-state battery at a current density of 0.1C. The voltage range during the test was set to 2.7-4.3V (Li+ / Li).

[0066] Table 2 shows the battery test results for Examples 1-15 and Comparative Examples 1-2. Table 2 Battery test results of Examples 1-15 and Comparative Examples 1-3 As shown in Table 2, the all-solid-state batteries prepared using surface F-doped electrolytes in Examples 1-15 achieved a capacity retention of over 93% after 200 cycles of discharge, significantly better than Comparative Examples 1-3. This indicates that the present invention can effectively improve the electrochemical cycling stability of the electrolyte.

[0067] ③ Solvent stability test: The electrolyte / xylene mass ratio was mixed at 1:3, and after soaking for two hours, the xylene solution in the electrolyte was dried under a 99.999% pure argon atmosphere at 120℃ for 1 hour. The ionic conductivity of the electrolyte before and after solvent soaking was tested according to the method shown in ① Ionic conductivity test, and denoted as σ. 0、 σ t , with σ t / σ0×100% is used as an indicator of solvent stability.

[0068] Table 3 Solvent stability of Examples 1-15 and Comparative Examples 1-3 According to Table 3, under the same particle size conditions, surface fluorination can improve the solvent stability of sulfide electrolytes during battery fabrication. For example, in Example 6, Comparative Example 1, and Comparative Example 3, which have the same particle size and Li content, the introduction of F element significantly improved the solvent stability from 73%, with surface fluorination (97%) showing a better improvement effect than bulk fluorine doping (80%).

[0069] In summary, the sulfide solid electrolyte obtained by this invention retains the original excellent properties such as high ionic conductivity and good mechanical strength, while effectively improving the electrolyte's air stability and electrochemical cycle stability, significantly enhancing its comprehensive performance and practical value.

[0070] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

[0071] The present invention has been described above with reference to embodiments thereof. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

[0072] Although embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and modifications can be made to the embodiments of the present invention without departing from the spirit and scope of the invention.

[0073] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A solid electrolyte material, characterized in that, include: The chemical formula of the solid electrolyte material is Li. a PS b Cl c Br d F e Where 5.3≤a<6, 4.3≤b<5, 0.8≤c<1.7, 0≤d<0.9, 0<e≤0.2; the solid electrolyte material is in the form of powder particles, and the particle size D of the solid electrolyte material is... 50 ≤3 micrometers and particle size distribution Span value ≤2; F element is distributed on the surface of powder particles and the distribution depth is ≤100nm.

2. The solid electrolyte material according to claim 1, characterized in that: in, 5.3≤a≤5.6, 4.3≤b≤4.6, 1.3≤c<1.6, d=0, 0.05≤e≤0.

1.

3. The solid electrolyte material according to claim 1, characterized in that: in, 5.3≤a≤5.6, 4.3≤b≤4.6, 0.8≤c≤1, 0.6≤d≤0.85, 0.05≤e≤0.

1.

4. The solid electrolyte material according to claim 1, characterized in that: The solid electrolyte material has a powder particle size D 50 ≤1 micrometer and particle size distribution Span value≤2, F element distribution depth on the surface of powder particles≤50nm.

5. A method for preparing a solid electrolyte material, characterized in that, The preparation method is applicable to the solid electrolyte material as described in any one of claims 1 to 4, and the preparation method includes the following steps: Step 100: Mix and grind the raw materials used to form the solid electrolyte material to obtain a mixture; Step 200: The mixture is subjected to solid-state sintering to obtain the first reactant; Step 300: Perform particle size treatment on the first reactant to obtain the second reactant; Step 400: Perform surface treatment on the second reactant to obtain the third reactant; Step 500: Anneal the third reactant to obtain a solid electrolyte material.

6. The preparation method according to claim 5, characterized in that, The raw materials for the solid electrolyte material used in step 100 include: Li2S, P2S5 and LiCl or Li2S, P2S5, LiCl and LiBr.

7. The preparation method according to claim 5, characterized in that, The solid-state sintering conditions in step 200 include: a temperature of 450℃ to 600℃; a time of 6h to 15h; and a protective atmosphere including argon or nitrogen.

8. The preparation method according to claim 5, characterized in that, The particle size treatment in step 300 includes ball milling, air jet milling, dry sand milling, or wet sand milling.

9. The preparation method according to claim 5, characterized in that, The surface treatment in step 400 includes: loading the second reactant into a fluidized bed under a protective atmosphere, introducing dry HF gas in the powder fluidization state, controlling the temperature inside the fluidized bed to be between 20°C and 50°C, and the fluidization time to be between 1 min and 20 min. The protective atmosphere includes an argon or nitrogen environment.

10. The preparation method according to claim 5, characterized in that, The annealing process in step 500 includes heating the third reactant in a protective atmosphere for 2 to 10 hours, wherein the heating temperature is 200°C to 300°C, and the protective atmosphere includes an argon or nitrogen environment.

11. An electrolyte layer, characterized in that, The electrolyte layer is formed by pressing a solid electrolyte material as described in any one of claims 1 to 4 or a solid electrolyte material prepared by the preparation method described in any one of claims 5 to 10.

12. A lithium-ion battery, characterized in that, The lithium-ion battery includes a positive electrode layer, a negative electrode layer, and an electrolyte layer between the positive and negative electrodes. The electrolyte layer includes a solid electrolyte material as described in any one of claims 1 to 4, a solid electrolyte material prepared by the preparation method described in any one of claims 5 to 10, or an electrolyte layer as described in claim 11.

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