Oxygen element-doped sulfide electrolyte and preparation method therefor and use thereof

Abstract

An oxygen element-doped sulfide electrolyte and a preparation method therefor and a use thereof. The surface of the sulfide electrolyte contains a uniform oxide coating layer, and the interior of the sulfide electrolyte is doped with an oxygen element; the thickness of the oxide coating layer is 1-100 nm, and the oxygen element of the oxide-doped sulfide electrolyte is gradiently distributed. The structure can enhance the air stability of the sulfide electrolyte, and because of low doping amount of oxygen element, less ionic conductivity is lost. Meanwhile, the structure can ensure that the oxygen-coated shell is not easy to fall off, thereby further improving the air stability of the sulfide electrolyte.

Description

Oxygen-doped sulfide electrolyte, preparation method and application thereof Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an oxygen-doped sulfide electrolyte, a preparation method, and applications thereof. Background Art

[0002] In recent years, with the rapid popularization of electronic devices and electric vehicles, lithium-ion batteries, as a key power source, have seen rapid development in related industries. As the functions and performance of various devices improve, the market has placed higher demands on the high capacity, long cycle life, and safety of batteries. Currently, commercial lithium-ion batteries all use liquid electrolytes for the conduction of lithium ions between the positive and negative electrodes. However, the problems of flammability, puncture-induced short circuits and fires, and the large space occupied by liquid electrolytes in the battery still exist. Using inorganic solid electrolytes instead of liquid electrolytes can achieve higher battery energy density, simpler battery design, and higher safety. Therefore, the design and synthesis of solid electrolytes are very important for the future development of batteries.

[0003] Currently, inorganic solid electrolytes are primarily categorized into two technological approaches: oxide electrolytes and sulfide electrolytes. Sulfide electrolytes, with their ionic conductivity rivaling that of liquid electrolytes and their lower Young's modulus, are well-suited for use in all-solid-state batteries. However, sulfides' instability to air and moisture can lead to certain side reactions during the production process. The PS groups within the electrolyte react with moisture in the air to produce toxic H2S gas, resulting in a decrease in ionic conductivity. Oxygen doping can suppress side reactions and H2S gas production in sulfide electrolytes, and oxygen-doped sulfide electrolytes offer improved compatibility with commonly used oxide cathodes.

[0004] There are two methods for preparing oxygen-doped sulfide electrolytes:

[0005] 1) Internal doping of oxygen: Oxygen is uniformly distributed within the electrolyte particles, making the preparation process more complex. For example, when oxygen is provided by doping with raw materials containing oxygen (such as Li2O and P2O5), multiple ball milling cycles are required during the raw material mixing process. Agglomerated raw materials must also be manually broken up, which is time-consuming. Furthermore, significant material loss occurs due to material adhesion to the milling beads.

[0006] When the above method is used, when the oxygen doping level inside the sulfide electrolyte particles is too high, the migration performance of lithium ions will deteriorate and the ionic conductivity of the electrolyte will decrease. Moreover, through this doping method, it is impossible to achieve uniform oxygen doping under conditions where the oxygen ratio is very low, and it is especially difficult to achieve uniform dispersion of the material during sintering.

[0007] One approach involves adding Li2O2, LiNO3, or other substances as oxidants to the raw materials, followed by sintering to produce oxygen-doped sulfide electrolytes. While these methods improve the stability of the sulfide electrolytes, other electrolyte properties, including ionic conductivity, are significantly reduced, and the oxygen doping level cannot be controlled at the microscale.

[0008] Another method involves oxygen doping by introducing a certain amount of oxygen into the sintering atmosphere during the raw material sintering process. However, the resulting sulfide electrolytes from this method exhibit uneven oxygen distribution, leading to rapid particle deterioration and reduced conductivity, primarily in areas with low oxygen content. Furthermore, the amount of oxygen doping cannot be controlled, and high temperatures can easily lead to excessive oxidation of the electrolyte, significantly reducing ionic conductivity.

[0009] 2) Although the surface is coated with an oxygen-containing layer, which can reduce the proportion of oxygen doping, there is currently no mature preparation method, the coating efficiency is low, and it is difficult to control the thickness of the oxygen coating layer.

[0010] One method involves controlling the atmosphere within a ball mill by injecting a certain amount of oxygen and argon mixture into the mill to ball-mill the sulfide electrolyte, thereby obtaining an oxide-coated sulfide electrolyte. However, this method can cause the powder to become compacted and hardened during the ball milling process, failing to form fully oxide-coated particles. The air stability is also poor, and the different elemental ratios between the oxide shell and the particle interior create discontinuities in physical properties, making the shell easily detachable. Furthermore, ball milling can impose excessive mechanical stress on the electrolyte, disrupting the crystal structure and affecting ionic conductivity.

[0011] Another approach involves exposing sulfide electrolytes to humid air, causing the surface sulfide to react with water vapor and oxygen to form a surface oxide layer, resulting in an oxide-coated electrolyte. However, the oxide layer formed by this approach significantly affects the performance of the sulfide electrolyte, severely reducing ionic conductivity. Essentially, this involves hydrolysis and oxidation of the sulfide surface, which is equivalent to a slow failure process. The shell formation process, oxygen shell thickness, and oxygen doping level are all uncontrollable. Furthermore, the shell formation process produces gases such as H2S, which poses a health hazard to humans.

[0012] Therefore, there is an urgent need for more efficient and controllable methods to prepare oxygen-doped sulfide electrolytes.

[0013] Summary of the Invention

[0014] In response to the above technical problems, the present application provides an oxygen-doped sulfide electrolyte, a preparation method and its application. The oxygen-doped sulfide electrolyte is a sulfide electrolyte obtained by de-milling and separating from the milling medium. The obtained sulfide electrolyte has high ionic conductivity.

[0015] The specific technical solutions of this application are as follows:

[0016] The present application provides an oxygen-doped sulfide electrolyte, wherein the surface of the sulfide electrolyte contains a uniform oxide coating layer, and the interior of the sulfide electrolyte is doped with oxygen;

[0017] The thickness of the oxide coating layer is 1-100 nm.

[0018] Preferably, for the above-mentioned sulfide electrolyte, the thickness of the oxide coating layer is 1-50 nm, preferably 5-15 nm.

[0019] Preferably, for any of the above-mentioned sulfide electrolytes, the total doping amount of oxygen element is 0.01-1%, preferably 0.05-0.25%.

[0020] The present application provides a method for batch preparation of oxygen-doped sulfide electrolytes, which comprises the following steps:

[0021] (1) mixing the raw materials uniformly and crushing them to obtain powder;

[0022] (2) finely grinding the powder to obtain finely ground powder;

[0023] (3) sintering the finely ground powder to obtain sulfide electrolyte powder;

[0024] (4) crushing the sulfide electrolyte powder to obtain crushed sulfide electrolyte powder;

[0025] (5) The crushed sulfide electrolyte powder is finely ground in a medium-free grinder using a mixed gas containing oxygen to obtain an oxide-coated sulfide electrolyte.

[0026] Preferably, in the above-mentioned method, the fine grinding in step (2) is to place the powder of step (1) into a medium-free grinder and grind the powder using a mixed gas containing oxygen to obtain finely ground powder.

[0027] Preferably, for any of the above methods, the medium-free pulverizer is a jet mill or a thin film rotary mixer.

[0028] Preferably, for any of the above methods, in step (2), the oxygen is 0.01-5%, preferably 0.01-1%, by volume percentage in the mixed gas;

[0029] And / or in step (5), the oxygen is 0.1-5%, preferably 0.1-0.5%, by volume percentage in the mixed gas.

[0030] Preferably, for any of the above methods, in step (2) and / or (5), the crushing pressure for fine grinding is 0.1-1.0 MPa, preferably 0.2-0.7 MPa, more preferably 0.2-0.4 MPa.

[0031] Preferably, for any of the above methods, a static electricity removal operation is performed in step (2) and / or in step (5), and preferably a static electricity removal operation is performed in both step (2) and step (5).

[0032] Preferably, in any of the above methods, the sulfide electrolyte is the sulfide electrolyte mentioned in any of the above methods.

[0033] The present application provides an all-solid-state battery, which comprises the sulfide electrolyte described in any one of the above items or the sulfide electrolyte prepared by the method described in any one of the above items.

[0034] Effects of the Invention

[0035] The sulfide electrolyte prepared by the method described in the present application has a gradient distribution of oxygen elements. This structure can improve the air stability of the sulfide electrolyte and requires a smaller amount of oxygen doping, resulting in less loss of ionic conductivity. At the same time, this structure can also ensure that the oxygen-coated shell is not easy to fall off, further improving the air stability of the sulfide electrolyte. In addition, the process method of the present application is simple and fast, and is convenient for batch synthesis.

[0036] This application uses medium-free grinding in a mixed gas containing oxygen to achieve surface coating of trace oxygen elements in the collision of particles in an oxygen atmosphere. Combined with static electricity removal, this method achieves more complete crushing and more uniform oxygen doping. This method controls the crushing pressure and oxygen concentration of the medium-free grinding to more accurately, more minutely, and more uniformly coat the raw material particles with oxygen elements. After sintering, it forms a sulfide electrolyte with a uniform internal doping of trace oxygen elements. This trace and uniform oxygen doping is difficult to achieve with other methods.

[0037] This method also allows for the coating of an oxygen-rich coating on the outer surface of internally oxygen-doped electrolyte particles, creating a structure with a low-concentration oxygen doping inside and an oxide coating on the outside. The overall low oxygen concentration in the sulfide electrolyte minimizes the impact of oxygen on the electrolyte's ionic conductivity while achieving good air stability. Furthermore, the oxygen content in the oxide coating and the particle interior exhibits a gradient oxygen concentration distribution, making it less likely to detach during sample preparation and reduce its air stability.

[0038] The method described in the present application achieves a pulverization process in which finer and lower-hardness sulfide electrolyte and its raw material powders are not agglomerated or adhered by performing static electricity removal operations on raw materials and equipment during the use of a media-free pulverizer, thereby achieving better particle pulverization effects and uniform and controllable particle size and oxygen shell thickness of the particles in a specified atmosphere.

[0039] Figures in the specification

[0040] FIG1 is an EDX schematic diagram of the oxygen-doped sulfide electrolyte prepared in Example 1.

[0041] FIG2 is an EDX schematic diagram of FIG1 magnified 24 times.

[0042] FIG3 is an EDX diagram of the oxygen-doped sulfide electrolyte prepared in Example 1 perpendicular to the direction of FIG1

[0043] FIG4 is an EDX schematic diagram of FIG2 magnified 24 times. DETAILED DESCRIPTION

[0044] The present application is described in detail below in conjunction with the described embodiments. Although specific embodiments of the present application are shown, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0045] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" are open-ended terms and should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present application, but the description is based on the general principles of the specification and is not intended to limit the scope of the present application. The scope of protection of this application shall be as defined by the attached claims.

[0046] The present application provides an oxygen-doped sulfide electrolyte, wherein the surface of the sulfide electrolyte contains a uniform oxide coating layer, and the interior of the sulfide electrolyte is doped with oxygen.

[0047] The oxygen-doped sulfide electrolyte refers to a sulfide electrolyte doped with oxygen. In the present application, the oxygen-doped sulfide electrolyte refers to a sulfide electrolyte having a uniform oxide coating layer on the surface and doped with oxygen inside the sulfide electrolyte.

[0048] A uniform oxide coating layer means that the oxygen element intensity is similar in all directions of the particle as measured by EDX oxygen element distribution testing, and the total intensity difference is within ±20%.

[0049] In the present application, the oxygen-doped sulfide electrolyte may have a crystal structure of a high- or intermediate-order crystal family (cubic, hexagonal, tetragonal, or trigonal system) or a glass-ceramic phase itself.

[0050] The thickness of the oxide coating layer is 1-100 nm. Preferably, the thickness of the oxide coating layer is 1-50 nm, and more preferably 5-15 nm.

[0051] For example, the thickness of the surface uniform oxide coating can be 1nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc.

[0052] In some embodiments, the total doping amount of oxygen is 0.01-1%, further preferably 0.05-0.25%. In this application, the total doping amount of oxygen refers to the ratio of the signal intensity of O to the sum of the signal intensities of all elements in the EDX test.

[0053] For example, the overall doping amount of oxygen element can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95%, 1%, etc.

[0054] In the present application, there is no limitation on the method for measuring the thickness of the oxide coating layer, and the thickness of the oxide coating layer can be tested using conventional methods in the art, such as XPS testing.

[0055] Specifically, the thickness of the oxide coating layer refers to: when the XPS test depth of the sample gradually deepens from 1 nm to X nm, and the peak area of ​​the 1s orbital of O measured by XPS at the X+1 nm position in the test results differs from the peak area of ​​the 1s orbital of O measured by XPS at the X nm position by less than 5%, then the thickness of the oxide coating layer is X nm.

[0056] The overall oxygen doping amount in the sulfide electrolyte refers to the ratio of the sum of the oxygen signal intensity to the sum of the signal intensities of all elements at all scanning points in the electrolyte through EDX mapping test, which is the overall oxygen doping amount, expressed in percentage.

[0057] The determination method is to use a combination of STEM and element EDX mapping to test the O element signal intensity and compare it with the intensity of all element signals at each position.

[0058] In some embodiments, the sulfide electrolyte has the general formula (Li A )(G B )(S C )(X D ), where 0≤A≤12, 0≤B≤5, 0≤C≤12, 0≤D≤2,

[0059] G is selected from one or more of P, Si, Ge and Sn;

[0060] S is selected from one or more of S, O, N, Se and Te;

[0061] Z is selected from one or more of Cl, Br, I and F.

[0062] In some embodiments, the surface of the sulfide electrolyte contains a uniform oxide coating layer, and the interior of the sulfide electrolyte is doped with oxygen elements;

[0063] The thickness of the oxide coating layer is 1-100 nm. In some embodiments, the thickness of the oxide coating layer is 1-50 nm, preferably 5-15 nm. In some embodiments, the overall oxygen doping amount is 0.01-1%, preferably 0.05-0.25%. The oxygen-doped sulfide electrolyte described herein can improve the stability of the sulfide electrolyte and have higher ionic conductivity due to oxygen doping.

[0064] The present application also provides a method for batch preparation of oxygen-doped sulfide electrolytes, comprising the following steps:

[0065] (1) mixing the raw materials uniformly and crushing them to obtain powder;

[0066] (2) finely grinding the powder to obtain finely ground powder;

[0067] (3) sintering the finely ground powder to obtain sulfide electrolyte powder;

[0068] (4) crushing the sulfide electrolyte powder to obtain crushed sulfide electrolyte powder;

[0069] (5) The crushed sulfide electrolyte powder is finely ground in a medium-free grinder using a mixed gas containing oxygen to obtain an oxide-coated sulfide electrolyte.

[0070] In this application, the raw materials for preparing sulfide electrolytes are not limited in any way, and they can be raw materials commonly used in the art. For example, Li2S, P2S5, LiX, MX (X = Cl, F, Br, I, OH, O, O2, N, etc.; M = Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, etc.) can be used to prepare sulfide electrolytes Li 7-a (M b P 1-b )SX a (0<a≤2, 0≤b≤1); Li2S, P2S5, GeS2, MS, LiX (X=Cl, F, Br, I, OH, O, O2, N; M=Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, etc.) can also be used to synthesize Li 10+c M 1+c P 2-c S 12 (-1≤c≤2); Li2S, P2S5, SiS2, MS, LiX (X=Cl, F, Br, I, OH, O, O2, N, etc.; M=Ge, Si, Ta, La, Zr, Te, Se, Sn, Sb, etc.) can also be used to synthesize Li 21-e Si3M d P 3-d S 23 X e (0≤d≤3, 0≤e≤3); X and M may be multiple, or M and X may not be included.

[0071] In the present application, there is no limitation on the equipment used for crushing, and the crushing can be carried out by conventional equipment in the field, for example, an electric grinder, a dispersion tank, a rotary mill, a stirrer, a mixer, etc., but no grinding media is used.

[0072] In some embodiments, fine grinding of the powder involves placing the powder in a medium-free pulverizer and finely grinding the powder using a mixed gas containing oxygen to obtain finely ground powder. In some embodiments, crushing the sulfide electrolyte powder involves placing the sulfide electrolyte powder in an electric grinder to crush the powder to obtain crushed sulfide electrolyte powder. In some embodiments, the medium-free pulverizer is a jet mill or a thin film rotary mixer, preferably a jet mill.

[0073] Jet milling utilizes high-speed airflow to grind the surface of a material. It utilizes the high-speed rotating flow field generated by the airflow to cause the material to continuously rotate, collide, and rub against each other, thereby achieving the desired grinding effect. Jet milling offers advantages such as high grinding efficiency, high grinding precision, and minimal material damage. It is widely used for fine and ultrafine grinding of powdered materials.

[0074] The thin film gyratory mixer utilizes the high-speed rotation of the container itself to generate a super strong centrifugal force, so that the material impacts the inner wall to complete the crushing, and the material adheres to the inner wall to form a state similar to a powder / liquid film during the mixing and crushing process. For example, the Japanese PRIMIX thin film high-speed mixer FILMIX model 56-L can be used.

[0075] In the present application, there is no limitation on the components other than oxygen in the mixed gas containing oxygen. For example, it can be dry argon, nitrogen, carbon dioxide, carbon monoxide, hydrogen, H2S gas, etc. or a mixed gas of several thereof.

[0076] In some embodiments, in step (2), the oxygen is present in an amount of 0.01-5%, preferably 0.01-1%, by volume percentage in the mixed gas; and / or

[0077] In step (5), the oxygen gas is present in an amount of 0.1-5% by volume in the mixed gas, preferably 0.1-0.5% by volume.

[0078] For example, in step (2), the oxygen gas may be present in an amount of 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, etc., in terms of volume percentage in the mixed gas;

[0079] In step (5), the oxygen can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, etc., calculated as a percentage by volume in the mixed gas.

[0080] In some embodiments, the particle size of the powder in step (1) and the sulfide electrolyte powder after crushing in step (4) are both 0.5-5 mm; and / or

[0081] The particle size of the powder after fine grinding in step (2) and the sulfide electrolyte powder after fine grinding in step (5) are both 0.1-40 μm.

[0082] For example, the particle size of the powder and the crushed sulfide electrolyte powder can be 0.5-5mm, 0.5-4.5mm, 0.5-4mm, 0.5-3.5mm, 0.5-3mm, 0.5-2.5mm, 0.5-2mm, 0.5-1.5mm, 0.5-1mm, 1-5mm, 1-4.5mm, 1-4mm, 1-3.5mm, 1-3mm, 1-2.5mm, 1-2mm, 1-1.5mm, 1.5-5mm, 1.5-4.5mm, 1.5-4mm, 1.5-3 .5mm, 1.5-3mm, 1.5-2.5mm, 1.5-2mm, 2-5mm, 2-4.5mm, 2-4mm, 2-3.5mm, 2-3mm, 2-2.5mm, 2.5-5mm, 2.5-4.5mm, 2.5-4m m, 2.5-3.5mm, 2.5-3mm, 3-5mm, 3-4.5mm, 3-4mm, 3-3.5mm, 3.5-5mm, 3.5-4.5mm, 3.5-4mm, 4-5mm, 4-4.5mm, 4.5-5mm, etc.;

[0083] The particle size of the finely ground powder and the finely ground sulfide electrolyte powder can be 0.1-40μm, 0.1-30μm, 0.1-20μm, 0.1-10μm, 0.1-5μm, 0.1-1μm, 0.1-0.5μm, 0.5-40μm, 0.5-30μm, 0.5-20μm, 0.5-10μm, 0.5-5μm, 0.5-1μm, 5-40μm, 5-30μm, 5-20μm, 5-10μm, 10-40μm, 10-30μm, 10-20μm, 20-40μm, 20-30μm, 30-40μm, etc.

[0084] In some embodiments, a static electricity removal operation is performed in step (2) and / or step (5), and preferably a static electricity removal operation is performed in both steps (2) and (5).

[0085] In the present application, there is no limitation on the method of removing static electricity, and conventional static electricity removal equipment can be used for removing static electricity.

[0086] The present application adopts a method of removing static electricity, which can make the collision of particles more complete, reduce agglomeration and adhesion to the wall, and make the product more uniform.

[0087] In some embodiments, in steps (2) and / or (5), the pulverization pressure for fine grinding is 0.1 to 1.0 MPa, preferably 0.2 to 0.7 MPa, and more preferably 0.2 to 0.4 MPa.

[0088] For example, the pulverization pressure for fine grinding can be 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, etc.

[0089] In this application, the feed pressure refers to the pressure of the equipment when the material enters the equipment in step (2) / or (5). This application does not impose any restrictions on the feed pressure, which only needs to be greater than the crushing pressure. For example, the feed pressure can be 0.4-0.5Mpa.

[0090] In some embodiments, the sulfide electrolyte is the sulfide electrolyte described above.

[0091] In some embodiments, the method comprises the following steps:

[0092] (1) mixing the raw materials uniformly and crushing them to obtain powder;

[0093] (2) finely grinding the powder to obtain finely ground powder;

[0094] (3) sintering the finely ground powder to obtain sulfide electrolyte powder;

[0095] (4) crushing the sulfide electrolyte powder to obtain crushed sulfide electrolyte powder;

[0096] (5) The crushed sulfide electrolyte powder is finely ground in a medium-free grinder using a mixed gas containing oxygen to obtain an oxide-coated sulfide electrolyte. In some embodiments, the fine grinding in step (2) is to place the powder of step (1) into a medium-free grinder and finely grind the powder using a mixed gas containing oxygen to obtain a finely ground powder. In some embodiments, the medium-free grinder is a jet mill or a thin film rotary mixer. In some embodiments, in step (2), the oxygen is 0.01-5%, preferably 0.01-1%, by volume percentage in the mixed gas; and / or in step (5), the oxygen is 0.1-5%, preferably 0.1-0.5%, by volume percentage in the mixed gas. In some embodiments, in steps (2) and / or (5), the crushing pressure for fine grinding is 0.1-1.0 MPa, preferably 0.2-0.7 MPa, and more preferably 0.2-0.4 MPa. In some embodiments, a static electricity removal operation is performed in step (2) and / or step (5), preferably a static electricity removal operation is performed in both step (2) and / or (5). In some embodiments, the sulfide electrolyte is the sulfide electrolyte described above.

[0097] The present application adopts the described method to prepare sulfide electrolyte. Since no grinding media is used in the preparation process, the crushing is caused by the mutual collision between particles. During the process, no excessive heat is generated to affect the properties of the crushed material. In addition, the media-free crusher has a particle screening effect. The output particle size can be adjusted according to the difference between the feed pressure and the crushing pressure. The particles that reach the fineness will leave the crushing chamber and sink into the collector. The particle size distribution is concentrated, and excellent particle morphology and particle size consistency can be achieved, ensuring product quality and controllability.

[0098] The sulfide electrolyte prepared by the method described in the present application has a gradient distribution structure of oxygen elements, which can improve the stability of the sulfide and reduce the loss of ionic conductivity.

[0099] The present application provides an all-solid-state battery, which comprises the sulfide electrolyte described above or the sulfide electrolyte prepared by the method described above.

[0100] This application provides general and / or specific descriptions of the materials and experimental methods used in the experiments. In the following examples, unless otherwise specified, % represents wt%, i.e., percentage by weight. All reagents or instruments used without manufacturer indication are commercially available conventional reagents.

[0101] 1. Testing Methods of This Application

[0102] 1) Electrolyte Product Testing Method: 120 mg of sulfide electrolyte was pressed into a pellet (370 MPa) using a mold. The sample was subjected to an electrochemical impedance spectroscopy (EIS) test at a frequency range of 1 Hz to 5 MHz using an electrochemical workstation. The ionic conductivity was calculated. After the sulfide electrolyte powder was exposed to air for 24 hours, the ionic conductivity of the electrolyte was measured again. This value was divided by the ionic conductivity before the exposure test to obtain the ionic conductivity retention of the sulfide electrolyte after the exposure test.

[0103] 2) Thickness of the oxide coating layer: Using XPS testing, gradually increase the XPS test depth of the sample from 1 nm to X nm. If the difference between the O1s peak area of ​​the XPS measured at the X+1 nm position and the O1s peak area of ​​the XPS measured at the X nm position in the test results is less than 5%, then the thickness of the oxide coating layer is X nm. For example, the method for determining the thickness of the oxide coating layer uses XPS testing to test at different depths on the sample surface. When the O1s peak shape does not change significantly after a certain depth, this thickness is the thickness of the oxide coating layer. The average of the three measured positions is the thickness of the oxygen-coated outer shell layer.

[0104] Specifically, the parameters of the XPS test method are as follows:

[0105] X-ray source: monochromated AlKα ray (1486.6eV)

[0106] Spectrum measurement: O1s

[0107] Sputtering conditions: C60+, 10.0kV

[0108] Sputtering rate: about 2nm / min.

[0109] (3 Overall oxygen doping in sulfide electrolytes: EDX mapping tests were performed using a transmission electron microscope. A straight line was drawn from the edge of the electrolyte particle image, passing through the center of the electrolyte particle image. A graph was plotted with the starting point of the straight line as the horizontal axis and the signal intensity as the vertical axis. The O element signal intensities at each point on the horizontal axis were summed to obtain the total O element signal intensities. The signal intensities of all elements at each point on the horizontal axis were summed to obtain the total signal intensities of all elements. The ratio of the combined O element signal intensity to the total signal element intensity was the overall oxygen doping ratio. A straight line perpendicular to the straight line and also passing through the center of the electrolyte particle image was drawn to obtain the total O element signal intensities on the straight line. The straight line was rotated 45° clockwise and counterclockwise from the center of the electrolyte particle image, respectively, to obtain two straight lines with an angle of 45° to the straight line. The total O element signal intensities on these two straight lines were then calculated. If the sum of the O element signal intensities on the four straight lines differed within ±20%, the oxygen coating was considered to be relatively uniform.

[0110] 2. Example

[0111] Example 1 Preparation of sulfide electrolyte

[0112] (1) Li2S, P2S2, and LiCl were put into an electric grinder at a molar ratio of 2.5:0.5:1.0 (total mass of 1 kg) and ground at a speed of 60 rpm for 20 min to obtain powder.

[0113] (2) The powder is put into the air flow mill with a feed pressure of 0.45 MPa, a crushing pressure of 0.40 MPa, and a crushing gas source of 99.9% by volume argon and 0.1% by volume oxygen. Fine grinding is performed to obtain finely ground powder. D 90 The particle size is about 2 to 4 μm, and static electricity removal is performed during the fine grinding process.

[0114] (3) The finely ground powder was sintered in a vacuum atmosphere at a heating rate of 10°C / min, a sintering temperature of 550°C, and a holding time of 2h, and then cooled at room temperature to obtain a sulfide electrolyte powder.

[0115] (4) The sulfide electrolyte powder is crushed again in an electric grinder to obtain crushed sulfide electrolyte powder, wherein the grinding speed is 60 rpm and the grinding time is 30 min.

[0116] (5) The finely ground sulfide electrolyte powder was put into the air flow mill again with a feed pressure of 0.45 MPa and a crushing pressure of 0.20 MPa. The crushing gas source was a mixed gas of 99.8% argon and 0.2% oxygen by volume. During the fine grinding process, static electricity was removed to obtain a sulfide electrolyte (Li6PS5Cl) doped with oxygen elements inside and with a uniform oxide coating layer on the surface. The sulfide electrolyte was measured using XPS, and the thickness of the oxide coating layer was found to be 10 nm. The sum of the signal intensities of all elements such as O and Li, P, S, Cl, and O in the sulfide electrolyte was tested using EDX. The signal intensity distribution diagram is shown in Figure 1, and the 24-fold magnified diagram is shown in Figure 2. By comparison, the overall oxygen doping amount of the sulfide electrolyte was found to be 0.15%.

[0117] Figure 1 shows that the EDX mapping signal intensity for all elements in Example 1 is significantly greater than that for O, with the signal gradually increasing from the edges to the center, indicating a spherical particle structure. By summing the total element signal intensity at all locations and the O signal intensity, and calculating the intensity ratio, we find that the proportion of O to the total element is 0.15%.

[0118] Figure 2 is an enlarged view of Figure 1. It can be seen that the O element intensity is high on both sides, and the O element intensity in the middle is low and average, indicating that a shell-core structure with an O shell has been formed; the O element signal intensity of the particles is symmetrical on the left and right, indicating that the particles are evenly coated with oxygen shells.

[0119] The element intensity distribution diagrams on the straight line perpendicular to the direction of Figures 1 and 2 are shown in Figures 3 and 4. The enlarged diagram of Figure 3 magnified 24 times is shown in Figure 4. The difference in oxygen element intensity between Figures 1 and 3 is 5%, which is less than 20%, proving that the oxygen element shell coating of the particle is relatively uniform.

[0120] Example 2 Preparation of sulfide electrolyte

[0121] The difference between Example 2 and Example 1 is that in step (2), oxygen with a volume content of 0.30% and argon with a volume of 99.7% are introduced to obtain a sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured by the same method as in Example 1 is 10nm, and the overall oxygen doping amount is 0.22%. In step (2), the oxygen ratio is increased, and more oxygen elements are doped internally. The stability is slightly improved compared with Example 1, but the ionic conductivity is significantly reduced. Among them, stability refers to the comparison of the ionic conductivity after exposure to air for 24 hours with the ionic conductivity before the exposure test. The relationship between the ionic conductivity of the oxygen-doped sulfide electrolyte obtained after preparation and the ionic conductivity of the electrolyte not doped with oxygen is shown in Table 1.

[0122] Example 3 Preparation of sulfide electrolyte

[0123] Example 3 differs from Example 1 in that in step (2), 0.03% by volume of oxygen and 99.97% by volume of argon are introduced to obtain a sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as in Example 1 is 10 nm, and the overall oxygen doping level is 0.12%. In step (2), the oxygen content is reduced, the internal doping level is reduced, and the ionic conductivity is higher, but the stability is significantly reduced compared to Example 1.

[0124] Example 4 Preparation of sulfide electrolyte

[0125] Example 4 differs from Example 1 in that in step (5), 0.10% by volume of oxygen and 99.9% by volume of argon are introduced to obtain a sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as in Example 1 is 5 nm, and the overall oxygen doping level is 0.10%. In step (5), the oxygen content is reduced, the oxygen coating layer is thinner, and the ionic conductivity is higher, but the stability is significantly reduced compared to Example 1.

[0126] Example 5 Preparation of sulfide electrolyte

[0127] Example 5 differs from Example 1 in that in step (5), 0.30% by volume of oxygen and 99.7% by volume of argon are introduced to produce a sulfide electrolyte doped with oxygen and having an oxide coating on the surface. The thickness of the oxide coating, measured using the same method as in Example 1, was 15 nm, and the overall oxygen doping level was 0.21%. In step (5), the oxygen content is increased, the oxygen coating is thicker, and stability is slightly improved compared to Example 1, but ionic conductivity is significantly reduced.

[0128] Example 6 Preparation of sulfide electrolyte

[0129] The difference between Example 6 and Example 1 is that the crushing pressure in step (2) is 0.20 MPa. The resulting sulfide electrolyte (Li6PS5Cl) has an oxide coating thickness of 10 nm and an overall oxygen doping level of 0.11% as measured by the same method as in Example 1. The reduced crushing pressure in step (2) reduces the oxygen doping level, resulting in a thinner oxygen coating layer and higher ionic conductivity, but significantly lower stability than in Example 1.

[0130] Example 7 Preparation of sulfide electrolyte

[0131] Example 7 differs from Example 1 in that the crushing pressure in step (5) is 0.40 MPa. The resulting sulfide electrolyte (Li6PS5Cl) has an oxide coating thickness of 15 nm, measured using the same method as in Example 1, and an overall oxygen doping level of 0.20%. Increasing the crushing pressure in step (5) results in a thicker oxygen coating layer, resulting in a slight improvement in stability compared to Example 1, but a significant decrease in ionic conductivity.

[0132] Example 8 Preparation of sulfide electrolyte

[0133] Example 8 differs from Example 1 in that only the static electricity removal operation is performed in step (2) to obtain a sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as in Example 1 is 8 nm, and the overall oxygen doping level is 0.14%. The static electricity removal operation in step (5) is omitted, resulting in insufficient oxygen coating in step (5), a thinner coating layer, and a higher ionic conductivity, but significantly lower stability than in Example 1.

[0134] Example 9 Preparation of sulfide electrolyte

[0135] The difference between Example 9 and Example 1 is that only the static electricity removal operation is performed in step (5) to obtain a sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as Example 1 is 10 nm, and the oxygen doping level is 0.13%. The static electricity removal operation in step (2) is omitted, resulting in insufficient oxygen doping in step (2), a reduced oxygen doping level, and a higher ionic conductivity, but a significantly lower stability than that of Example 1.

[0136] Example 10 Preparation of sulfide electrolyte

[0137] The difference between Example 10 and Example 1 is that no static electricity removal operation is performed during the entire process. The sulfide electrolyte (Li6PS5Cl) is obtained. The thickness of the oxide coating layer measured using the same method as Example 1 is 8 nm, and the overall oxygen doping level is 0.09%. The static electricity removal operations in steps (2) and (5) are omitted, resulting in insufficient oxygen doping in step (2) and insufficient oxygen coating in step (5). The oxygen doping level is reduced, and the ionic conductivity is higher, but the stability is significantly lower than that of Example 1.

[0138] Example 11 Preparation of sulfide electrolyte

[0139] The difference between Example 11 and Example 1 is that different raw materials are used. Example 11 uses Li2S, P2S2 and GeS2 as raw materials with a molar ratio of 5:1:1 to prepare a sulfide electrolyte (Li 10 GeP2S 12 ), the thickness of the oxide coating layer measured using the same method as in Example 1 was 10 nm, and the overall oxygen doping level was 0.16%. Examples 11-14 synthesize different sulfide electrolytes using this patented method, maintaining high ionic conductivity while maintaining air stability comparable to that of Example 1, demonstrating that other sulfide electrolytes can also be synthesized using this method.

[0140] Example 12 Preparation of sulfide electrolyte

[0141] The difference between Example 12 and Example 1 is that different raw materials are used. Example 12 uses raw materials of Li2S, P2S2, LiCl and SiS2 with a molar ratio of 9.5:1.5:1:3 to prepare the sulfide electrolyte (Li 20 Si3P3S 23 Cl), the thickness of the oxide coating layer measured by the same method as in Example 1 is 10 nm, and the overall oxygen doping amount is 0.15%.

[0142] Example 13 Preparation of sulfide electrolyte

[0143] The difference between Example 13 and Example 1 is that different raw materials are used. Example 13 uses Li2S and P2S2 as raw materials with a molar ratio of 1.5:0.5 to prepare a sulfide electrolyte (Li3PS4). The thickness of the oxide coating layer measured by the same method as Example 1 is 10 nm, and the overall oxygen doping amount is 0.14%.

[0144] Example 14 Preparation of sulfide electrolyte

[0145] The difference between Example 14 and Example 1 is that different raw materials are used. Example 14 uses Li2S and P2S2 as raw materials with a molar ratio of 3.5:1.5 to prepare the sulfide electrolyte (Li7P3S 11 ), the thickness of the oxide coating layer measured by the same method as in Example 1 is 10 nm, and the overall oxygen doping amount is 0.14%.

[0146] Comparative Example 1 Preparation of sulfide electrolyte

[0147] Comparative Example 1 is compared with Example 1. The difference is that step (2) uses ball milling to obtain a sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as Example 1 is 10 nm, and the overall oxygen doping level is 0.28%. The use of ball milling in step (2) compacts the material, which can easily lead to excessive and uneven oxygen doping. This lowers the conductivity, and degradation tends to begin in areas with less oxygen, resulting in poor stability.

[0148] Comparative Example 2 Preparation of sulfide electrolyte

[0149] Comparative Example 2 is compared with Example 1. The difference between them is that in step (5), ball milling is used to obtain the sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as in Example 1 is 20 nm, and the overall oxygen doping level is 0.22%. The use of ball milling in step (5) compacts the material, easily resulting in excessive oxygen coating. Furthermore, the integrity and uniformity of the coating layer cannot be guaranteed. Furthermore, the conductivity is low, degradation is easily initiated in areas with low oxygen content, and stability is also poor.

[0150] Comparative Example 3 Preparation of sulfide electrolyte

[0151] Comparative Example 3 is compared with Example 1. The difference is that in step (2), only argon gas is introduced instead of oxygen to obtain the sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as Example 1 is 10 nm, and the overall oxygen doping level is 0.06%. Oxygen doping is not performed in step (2), and the internal oxygen content is absent. Although the ionic conductivity is higher, the stability is significantly lower than that of Example 1.

[0152] Comparative Example 4 Preparation of sulfide electrolyte

[0153] Comparative Example 4 differs from Example 1 in that oxygen is not introduced in step (5) to obtain the sulfide electrolyte (Li6PS5Cl), which does not contain an oxide coating layer, and the overall oxygen doping level is 0.05%. Oxygen coating is not performed in step (5), and no oxide coating layer is present. Although the ionic conductivity is higher, the stability is significantly lower than that of Example 1.

[0154] Comparative Example 5 Preparation of sulfide electrolyte

[0155] The difference between Comparative Example 5 and Example 1 is that oxygen is not introduced in steps (2) and (5), and step (3) is modified as follows: the finely ground powder is sintered in a mixed gas of 0.1% oxygen and 99.9% argon, with a heating rate of 10°C / min, a sintering temperature of 550°C, a holding time of 2h, and cooling at room temperature to obtain a sulfide electrolyte powder. The obtained sulfide electrolyte (Li6PS5Cl) does not contain an oxide coating layer, and the overall oxygen doping amount is 2.21%. Using this method for oxygen doping, the results show that it is easy to overdope oxygen at high temperatures and the doping amount is difficult to control. Excessive oxygen doping makes its air stability relatively good, but the ionic conductivity is significantly reduced compared with Example 1, making it difficult to use as a qualified electrolyte.

[0156] Comparative Example 6 Preparation of sulfide electrolyte

[0157] Comparative Example 6 is compared with Example 1. The difference is that in step (2), 5.0% by volume of oxygen and 95.0% by volume of argon are introduced to obtain a sulfide electrolyte (Li6PS5Cl). No oxide coating layer is measured using the same method as in Example 1, and the overall oxygen doping level is 1.85%. The introduction of excessive oxygen in step (2) results in an excessively high oxygen doping level. Although the air stability is relatively good, the ionic conductivity is significantly lower than that of Example 1, making it difficult to use as a qualified electrolyte.

[0158] Comparative Example 7 Preparation of sulfide electrolyte

[0159] Comparative Example 7 is compared with Example 1. The difference is that in step (5), 5.0% by volume of oxygen and 95.0% by volume of argon are introduced to obtain a sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as Example 1 is 40 nm, and the overall oxygen doping level is 1.61%. The introduction of excessive oxygen in step (5) results in an excessively high oxygen doping level. Although the air stability is relatively good, the ionic conductivity is significantly lower than that of Example 1, making it difficult to use as a qualified electrolyte.

[0160] Comparative Example 8 Preparation of sulfide electrolyte

[0161] Comparative Example 8 is compared with Example 1, except that step (5) is changed to: the electrolyte is placed in moist air at a humidity of 20% for 1 hour to obtain a sulfide electrolyte (Li6PS5Cl). The thickness of the oxide coating layer measured using the same method as Example 1 is 110 nm, and the overall oxygen doping amount is 5.98%. Using this method for oxygen doping, the presence of moisture accelerates the oxidative decomposition of the electrolyte, causing the coating layer to form faster and thicker, which is difficult to control. Furthermore, hydrogen sulfide gas is generated, resulting in a coating layer composition that differs from that of the coating layer in the example. The coating layer has poor air stability and a significantly lower ionic conductivity than that of Example 1, making it completely unusable as a qualified electrolyte.

[0162] Experimental Example: Determination of ionic conductivity and calculation of ionic conductivity retention

[0163] The ionic conductivity of the sulfide electrolytes obtained in the Examples and Comparative Examples was measured as follows: 2 g of the sulfide electrolyte was weighed and evenly spread on a glass Petri dish within a glove box. The Petri dish was then placed in a reaction chamber with a flow of air at a specified humidity (10% relative humidity) and a flow rate of 200 ml / min. The sample was then allowed to stand for 24 hours at room temperature. After standing, the sample was collected and its ionic conductivity was measured. The sample was then exposed to air for 24 hours, and its ionic conductivity was then measured.

[0164] Calculate the retention rate of ionic conductivity using the following formula:

[0165] Ionic conductivity retention rate = ionic conductivity after exposure to air / ionic conductivity in the reaction box, wherein the ionic conductivity is measured as follows:

[0166] The electrolyte powder was filled into a cylindrical sleeve mold with a diameter of 1 mm and compacted under a pressure of 6 MPa. An electrochemical workstation was used to perform EIS testing on the electrolyte sheet in the mold. A vernier caliper was used to measure the sample thickness, and the ionic conductivity of the electrolyte was calculated.

[0167] The results are shown in Table 1.

[0168] Table 1 Ionic conductivity retention rate

[0169] The electrolyte ionic conductivity relationship refers to the ratio of the ionic conductivity of the prepared oxygen-doped sulfide electrolyte to the ionic conductivity of the electrolyte not doped with oxygen, that is:

[0170] A: ratio ≥98%;

[0171] B: 98%> ratio ≥ 95%;

[0172] C: 95%> ratio ≥ 90%;

[0173] D: 90%> ratio ≥ 10%;

[0174] E: ratio <10%.

[0175] It can be seen from Examples 1-10 that by regulating the proportion of oxygen in the mixed gas in step (2) and / or step (5), selectively adding a static removal step and regulating the crushing pressure in step (2) and / or step (5), the oxygen doping and coating of the electrolyte can be optimized, thereby affecting the conductivity and the conductivity retention rate. In addition, the preferred proportion of oxygen in the mixed gas can further optimize the stability of the electrolyte.

[0176] As can be seen from Example 1 and Comparative Examples 1-2 in the above table, the ball milling method cannot achieve uniform and effective internal doping of oxygen, nor can it control the doping of relatively small amounts of oxygen to minimize the impact on conductivity. It is even more difficult to uniformly coat the surface of the particles with oxygen to form a complete protection. Therefore, the air stability of the sulfide electrolyte prepared by the ball milling method is also poor.

[0177] It can be seen from Example 1 and Comparative Examples 3-4 that only internal doping with oxygen elements or only covering with oxygen shells will significantly reduce the air stability of the electrolyte.

[0178] In addition, the reason why some comparative examples in Table 1 have high ionic conductivity is that the electrolytes of the comparative examples did not prepare the electrolytes of the structure of the present application, that is, some steps did not dope oxygen elements, resulting in high conductivity, but also more serious degradation after exposure to air.

[0179] While ensuring the conductivity retention of the electrolyte, Examples 1-14 also ensure a high ionic conductivity of the electrolyte, solving the problem of being unable to achieve both air stability and ionic conductivity in general oxygen doping or oxygen coating methods.

[0180] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application in any other manner. Any person skilled in the art may utilize the above disclosed technical content to modify or modify the present application into equivalent embodiments with equivalent variations. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present application and are based on the technical essence of the present application shall still fall within the scope of protection of the present application.

Claims

1. An oxygen-doped sulfide electrolyte, wherein the surface of the sulfide electrolyte contains a uniform oxide coating layer, and the interior of the sulfide electrolyte is doped with oxygen; The thickness of the oxide coating layer is 1-100 nm.

2. The sulfide electrolyte according to claim 1, wherein The thickness of the oxide coating layer is 1-50 nm, preferably 5-15 nm.

3. The sulfide electrolyte according to any one of claims 1 to 2, wherein The total doping amount of oxygen element is 0.01-1%, preferably 0.05-0.25%.

4. A method for batch preparation of oxygen-doped sulfide electrolytes, comprising the following steps: (1) mixing the raw materials uniformly and crushing them to obtain powder; (2) finely grinding the powder to obtain finely ground powder; (3) sintering the finely ground powder to obtain sulfide electrolyte powder; (4) crushing the sulfide electrolyte powder to obtain crushed sulfide electrolyte powder; (5) The crushed sulfide electrolyte powder is finely ground in a medium-free pulverizer using a mixed gas containing oxygen to obtain an oxide-coated sulfide electrolyte.

5. The method according to claim 4, wherein: The fine grinding in step (2) is to place the powder of step (1) into a medium-free pulverizer and grind the powder using a mixed gas containing oxygen to obtain a finely ground powder.

6. The method according to any one of claims 4 to 5, wherein: The medium-free pulverizer is a jet mill or a thin film rotary mixer.

7. The method according to any one of claims 4 to 6, wherein: In step (2), the oxygen is 0.01-5%, preferably 0.01-1%, by volume percentage in the mixed gas; And / or in step (5), the oxygen is 0.1-5%, preferably 0.1-0.5%, by volume percentage in the mixed gas.

8. The method according to any one of claims 4 to 7, wherein: In step (2) and / or (5), the pulverizing pressure for fine grinding is 0.1-1.0 MPa, preferably 0.2-0.7 MPa, and more preferably 0.2-0.4 MPa.

9. The method according to any one of claims 4 to 8, wherein: The static electricity removal operation is performed in step (2) and / or in step (5), and preferably the static electricity removal operation is performed in both step (2) and step (5).

10. The method according to any one of claims 4 to 9, wherein: The sulfide electrolyte is the sulfide electrolyte according to any one of claims 1 to 3.

11. An all-solid-state battery, comprising the sulfide electrolyte according to any one of claims 1 to 3 or the sulfide electrolyte prepared by the method according to any one of claims 4 to 10.

Images