Sulfide solid-state electrolyte, electrode, solid-state electrolyte membrane, battery, battery assembly, and electrical device

Abstract

A sulfide solid-state electrolyte, an electrode, a solid-state electrolyte membrane, a battery, a battery assembly, and an electrical device. The sulfide solid-state electrolyte contains a halogen. In the crystal structure of the sulfide solid-state electrolyte, the occupancy of the halogen at the 4d Wyckoff position is 0.68-0.85.

Description

A sulfide solid electrolyte, electrode, solid electrolyte membrane, battery, battery assembly, and electrical device.

[0001] This disclosure claims priority to Chinese Patent Application No. 202510500237.4, filed on April 18, 2025, entitled "A Sulfide Solid Electrolyte, Electrode, Solid Electrolyte Membrane, Battery, Battery Component, and Electrical Equipment", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of lithium-ion battery technology, and in particular to a sulfide solid electrolyte, electrode, solid electrolyte membrane, battery, battery assembly, and electrical device. Background Technology

[0003] Lithium-ion batteries, as a core component of modern energy storage technology, have demonstrated an irreplaceable role in various fields such as portable electronic devices, electric vehicles, and renewable energy storage systems. With the increasing global demand for clean energy and efficient energy storage solutions, improving the performance of lithium-ion batteries has become a key research direction, with safety and energy density being the two core indicators determining their application scope and technological feasibility. While traditional liquid electrolytes possess good ionic conductivity and mature processing technology, they also have several significant drawbacks that limit battery safety and cycle life. In contrast, solid-state electrolytes, due to their potential to improve safety and energy density, are considered key materials for next-generation high-safety and high-performance lithium-ion batteries.

[0004] Among the many types of solid electrolytes, sulfide-based materials are favored for their high room-temperature ionic conductivity (theoretically up to 10). -2 Li₆PS₅Cl has attracted much attention due to its high conductivity (on the order of S / cm) and energy density. However, despite showing some potential, the actual ionic conductivity of stoichiometric Li₆PS₅Cl remains low (<3 mS / cm), which limits its commercial application to some extent.

[0005] Therefore, there is an urgent need for a sulfide solid electrolyte with high ionic conductivity, which would help improve the electrochemical performance of the battery. Summary of the Invention

[0006] This disclosure provides a sulfide solid electrolyte with high ionic conductivity, which enables the battery to have high electrochemical performance such as high conductivity.

[0007] In addition, this disclosure also provides an electrode, a solid electrolyte membrane, a battery, a battery assembly, and an electrical device.

[0008] This disclosure provides a sulfide solid electrolyte containing halogen, wherein the halogen occupies 0.68 to 0.85% of the 4d Wyckoff site in the crystal structure of the sulfide solid electrolyte.

[0009] In some embodiments disclosed herein, the sulfide solid electrolyte comprises sulfide solid electrolyte particles, at least a portion of the sulfide solid electrolyte particles comprising a core region and a surface region present on at least a portion of the surface of the core region, the core region and the surface region each independently comprising a sulfide electrolyte, the surface region containing a Q element, the Q element comprising O and / or Se; in the crystal structure of the sulfide solid electrolyte material, a portion of the 4d Wyckoff sites are occupied by the Q element and the sulfur element.

[0010] This disclosure includes some embodiments in which the halogen includes elements Cl and X, wherein the element X includes at least one of F, Br, and I.

[0011] This disclosure includes some embodiments in which the core region contains the halogen;

[0012] And / or, the surface region contains the halogen.

[0013] In some embodiments disclosed herein, the content of the Q element in the surface region decreases along the direction from the surface region to the core region;

[0014] And / or, the mass content of the Q element in the surface region is 0.29% to 1.53%.

[0015] This disclosure includes some embodiments in which the surface region contains element D, and element D includes at least one element selected from As, Sb, Bi, Sn, and In.

[0016] In some embodiments disclosed herein, the mass content of the D element in the surface region decreases along the direction from the surface region to the core region.

[0017] In some embodiments disclosed herein, the mass content of sulfur in the core region is greater than the mass content of sulfur in the surface region.

[0018] In some embodiments disclosed herein, the sulfur element occupies a fraction of 0.1 to 0.5 at the 4a Wyckoff site in the crystal structure of the sulfide solid electrolyte.

[0019] In some embodiments disclosed herein, the sulfide solid electrolyte further contains an element M, which includes an element Li.

[0020] In some embodiments disclosed herein, the element M further includes a metallic element with an atomic radius greater than that of the element Li; preferably, the metallic element with an atomic radius greater than that of the element Li includes elements Na and / or K.

[0021] Preferably, the molar percentage (g) of Na in the M element is 0% < g ≤ 20%;

[0022] Preferably, the molar percentage h of element K in element M is 0% < h ≤ 10%.

[0023] In some embodiments disclosed herein, in the crystal structure of the sulfide solid electrolyte, the M element occupies 0.10 to 0.52% of the 24g Wyckoff site. Preferably, the sites of the 24g Wyckoff site not occupied by the M element are vacant.

[0024] In some embodiments disclosed herein, in the crystal structure of the sulfide solid electrolyte, the M element occupies 0.2 to 0.42% of the 48h Wyckoff site; preferably, the sites of the 48h Wyckoff site not occupied by the M element are vacant.

[0025] In some embodiments disclosed herein, the molar percentage of the Li element in the M element is 70% to 100%;

[0026] In some embodiments disclosed herein, the sulfide solid electrolyte includes sulfide solid electrolyte particles, at least a portion of the sulfide solid electrolyte particles including a core region and a surface region present on at least a portion of the surface of the core region, wherein the core region and the surface region each independently include a sulfide electrolyte.

[0027] The sulfide electrolyte in the core region includes M. 6-y PS 5-y Cl 1+y-a X a ;

[0028] The sulfide electrolyte in the surface region includes M. 6-y PS 5-y-z Cl 1+y-a Q z X a and / or M 6-y P 1-m D m S 5-y Cl 1+y-a X a ;

[0029] M elements include alkali metal elements and / or alkaline earth metal elements;

[0030] Element X includes at least one of F, Br, and I;

[0031] The D element includes at least one of the elements As, Sb, Bi, Sn, and In.

[0032] a≥0, m>0;

[0033] 0 < y < 5;

[0034] 5-yz>0;

[0035] 1+ya>0.

[0036] In some embodiments disclosed herein, 0 ≤ a ≤ 0.7;

[0037] And / or, 0.3≤y≤0.8;

[0038] And / or, 0.05≤z≤0.25;

[0039] And / or, 0.05≤m≤0.3.

[0040] In some embodiments disclosed herein, the surface region has a volume fraction of 5-30% in the sulfide solid electrolyte particles;

[0041] In some embodiments disclosed herein, the core region and the surface region have the same crystal form; preferably, the core region and the surface region comprise a silver sulfide electrolyte of the silicogermanium ore type.

[0042] This disclosure also provides an electrode comprising a sulfide solid electrolyte as described above.

[0043] This disclosure also provides a solid electrolyte membrane, comprising the sulfide solid electrolyte as described above.

[0044] This disclosure also provides a battery, including electrodes as described above and / or a solid electrolyte membrane as described above.

[0045] This disclosure also provides a battery assembly including one or more batteries as described above.

[0046] This disclosure also provides an electrical device, including the battery as described above, or including a battery assembly as described above.

[0047] The sulfide solid electrolyte provided in this disclosure exhibits high anionic disorder by controlling the occupancy fraction of halogens at the 4d Wyckoff sites in the crystal structure to be between 0.68 and 0.85. Therefore, the sulfide solid electrolyte provided in this disclosure also possesses high ionic conductivity, which is beneficial for improving the electrochemical performance of the battery. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0049] Figure 1 is a schematic diagram of the structure of a sulfide solid electrolyte provided in an embodiment of this disclosure.

[0050] The accompanying drawings have illustrated specific embodiments of this disclosure, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this disclosure to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this disclosure clearer, the technical solutions in the embodiments of this disclosure will be clearly and completely described below in conjunction with the embodiments of this disclosure. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0052] In the manufacturing process of lithium batteries, using solid-state electrolytes instead of liquid electrolytes has the potential to improve battery safety and energy density. Among the many solid-state electrolytes, sulfide solid-state electrolytes (such as Li6PS5Cl) are widely used due to their high ionic conductivity and energy density. However, sulfide solid-state electrolytes suffer from low conductivity and low stability. This chemical instability and the resulting environmental hazards not only increase manufacturing and processing costs but also pose potential risks to the safe use of batteries.

[0053] The inventors discovered that the root cause of this phenomenon lies in the low chemical bond energy of PS, which makes the sulfide structure more susceptible to oxidation or desulfurization reactions, leading to structural changes and a significant decrease in the surface stability and ionic conductivity of the sulfide solid electrolyte.

[0054] Therefore, this disclosure focuses on modifying the PS chemical bonds within the stable crystalline phase of sulfide solid electrolytes. During the modification process, the inventors attempted to dope the electrolyte with elements that enhance its antioxidant properties (such as oxygen). While oxygen doping improves the surface stability of the sulfide solid electrolyte due to the low bond energy of the PO bond, it also reduces its ionic conductivity, resulting in lower electrochemical performance such as conductivity. This makes it impossible to simultaneously meet the requirements of solid electrolytes for both surface stability and ionic conductivity.

[0055] Based on this, this disclosure provides a sulfide solid electrolyte containing halogens. In the crystal structure of the sulfide solid electrolyte, the halogen occupancy fraction at the 4d Wyckoff site is 0.68 to 0.85.

[0056] The sulfide solid electrolyte provided in this embodiment has the above-mentioned characteristics, and thus exhibits high stability and ionic conductivity, which is beneficial for improving the electrochemical performance of the battery.

[0057] In this disclosure, the occupancy fraction of a certain element at a certain Wyckoff site refers to the proportion of the number of sites occupied by the element at that Wyckoff site to the total number of sites at that Wyckoff site; for example, the occupancy fraction of halogens at 4d Wyckoff sites of 0.68 to 0.85 can be understood as the proportion of the number of sites occupied by halogens at 4d Wyckoff sites to the total number of sites at 4d Wyckoff sites.

[0058] The inventors analyzed that the sulfide solid electrolyte provided in this disclosure has a high ionic conductivity because: currently, in conventional sulfide solid electrolytes, halogens occupy 100% of the 4d Wyckoff sites, while in this disclosure, the halogen occupancy in the 4d Wyckoff sites is 0.68–0.85, indicating that some sites on the 4d Wyckoff sites are occupied by other elements. This suggests that halogens, sulfur, and other elements in the sulfide solid electrolyte exhibit a disordered distribution, providing more transport channels for active metal ions (such as lithium ions) in the sulfide solid electrolyte, thereby improving the ionic conductivity of the sulfide solid electrolyte. If the halogen occupancy in the 4d Wyckoff sites is less than 0.68, the crystal structure is unstable and prone to collapse during battery cycling, affecting the stability of the sulfide solid electrolyte. Therefore, in this embodiment of the present disclosure, the occupancy fraction of halogen elements in the 4d Wyckoff site is controlled to be 0.68 to 0.85, which can improve both the ionic conductivity and stability of the sulfide solid electrolyte, thereby improving the battery's safety and electrochemical performance such as conductivity.

[0059] In detail, the occupancy fraction of halogens at the 4d Wyckoff site can be tested using conventional testing methods in the art. For example, it can be tested by refined XRD on sulfide solid electrolytes, and the diffraction data can be obtained by fitting the Rietveld method with an error factor of less than 10%.

[0060] In some embodiments of this disclosure, the sulfide solid electrolyte includes sulfide solid electrolyte particles, at least a portion of which includes a core region and a surface region present on at least a portion of the surface of the core region. The core region and the surface region each independently include a sulfide electrolyte, and the surface region contains an element Q, which includes O and / or Se. As shown in FIG1, the sulfide solid electrolyte of an embodiment of this disclosure includes a core region (core area) and a surface region (gradient region) present on at least a portion of the surface of the core region.

[0061] When the sulfide solid electrolyte has the above-described composition, its surface stability and ionic conductivity can be further improved. Specifically, by using Q element (at least one of O and Se elements, which has a low reactivity with moisture in the air) to dope the surface region of the sulfide solid electrolyte, the sulfur content in the surface region is reduced, further mitigating the problem of decreased surface stability caused by the easy reaction of sulfur with moisture in the air. On the other hand, the bond energies formed between O and Se elements and P elements are stronger than the PS bond energies, thus further enhancing the surface stability of the sulfide solid electrolyte. Simultaneously, the gradient doping of Q element only in the surface region reduces the internal occupation of the sulfide solid electrolyte by Q element, further mitigating the problem of decreased ionic conductivity caused by Q element doping. Therefore, the sulfide solid electrolyte provided in this embodiment of the present disclosure achieves both high stability and high ionic conductivity.

[0062] The sulfide solid electrolyte particles provided in this embodiment are mainly spherical or near-spherical in shape, with the core region located inside the sulfide solid electrolyte particle and the surface region located outside the sulfide solid electrolyte particle.

[0063] In detail, the surface region can grow on part or all of the core region's surface. The core and surface regions of the aforementioned sulfide solid electrolyte are continuously distributed without stratification. Therefore, it is possible to establish complete and continuous ion transport channels within the sulfide solid electrolyte particles, further improving the solid-solid interface, reducing high interfacial impedance and interfacial side reactions, and thus contributing to higher ionic conductivity in the sulfide solid electrolyte.

[0064] In some embodiments, the sulfide solid electrolyte contains an element Q, which includes O and / or Se; in the crystal structure of the sulfide solid electrolyte material, some sites in the 4d Wyckoff sites are occupied by the element Q and sulfur. The anionic disorder in the sulfide solid electrolyte of this disclosure embodiment is further enhanced, which is beneficial for further improving the ionic conductivity of the sulfide solid electrolyte, and thus beneficial for improving the electrochemical performance of the battery, such as conductivity.

[0065] This disclosure does not impose any special limitations on the particle size and particle size distribution of sulfide solid electrolytes; they can be selected according to actual needs. For example, the particle size of sulfide solid electrolytes includes 0.3 to 15 μm.

[0066] It should be noted that the particle size here refers to the median particle size Dv50.

[0067] In some embodiments of this disclosure, element X includes at least one element selected from F, Br, and I. In the sulfide solid electrolyte of this disclosure, at least one element selected from F, Br, and I is used to replace Cl element in the core and surface regions for doping. This results in higher anionic disorder in the sulfide solid electrolyte and a better increase in lithium-ion vacancies, thus improving conductivity. The inventors explain that the introduction of element X further increases the randomness of anion positions. This local disorder can better weaken the rigidity of the crystal lattice, allowing lithium ions more space to migrate, thereby further improving the ionic conductivity of the sulfide solid electrolyte. Furthermore, the increased anionic disorder further lowers the energy barriers of static defects (such as vacancies and interstitials), making these defects easier to form and move, providing more detour paths for lithium ions to move, further reducing obstacles in the diffusion process, and thus further improving the overall ionic conductivity of the sulfide solid electrolyte.

[0068] In some embodiments, the core region contains halogen, which can further enhance the ionic conductivity of the sulfide solid electrolyte.

[0069] In some embodiments, the surface region contains halogens, which can further enhance the ionic conductivity of the sulfide solid electrolyte.

[0070] In some embodiments of this disclosure, the content of element Q in the surface region decreases from the surface region to the core region. That is, the volume percentage of element Q decreases from the surface of the surface region to the core region, which is beneficial for further improving the surface stability and ionic conductivity of the sulfide solid electrolyte.

[0071] In some embodiments, the mass content of Q element in the surface region is 0.29% to 1.53%, which further improves both the surface stability and ionic conductivity of the sulfide solid electrolyte.

[0072] In some embodiments, the surface region contains element D, which is selected from at least one element chosen from As, Sb, Bi, Sn, and In. These elements exhibit relatively weak oxidizing power and low electropositivity when forming cations, thus possessing low redox activity and reducing reactions with the electrode material. Therefore, by using the aforementioned elements to dope the surface region of the sulfide solid electrolyte in the embodiments of this disclosure, it is helpful to maintain the long-term stability of the sulfide solid electrolyte.

[0073] In some embodiments, the mass content of element D in the surface region decreases from the surface region to the core region. That is, the mass content of element D decreases from the surface of the surface region to the core region, which is beneficial to further improve the surface stability and ionic conductivity of the sulfide solid electrolyte.

[0074] In detail, in the sulfide solid electrolyte of this disclosure, the surface region may include both Q and D elements, or only one of Q and D elements. The mass content of Q and / or D elements decreases from the surface of the surface region towards the core region. Specifically, the solid electrolyte particles contain at least one of Q and D elements only in the surface region, while the core region does not contain the aforementioned elements. Furthermore, in the surface region, the content of the aforementioned elements is higher in a portion of the surface region near the surface, and the mass content of the aforementioned elements decreases from the surface towards the core region.

[0075] In some embodiments, the mass content of sulfur in the core region is greater than that in the surface region, which further improves the ionic conductivity of the sulfide solid electrolyte and is beneficial to better improve the electrochemical performance of the battery, such as conductivity.

[0076] In practice, the mass content of the above elements can be obtained by FIB slicing to obtain the cross section of the sulfide solid electrolyte, and then by EDS measurement to obtain the proportion of the mass content of all elements in the selected area (which can be any area selected from the surface of the surface area to the core area in the direction of the core area where the mass content of the above elements needs to be counted) from the core area to the selected area.

[0077] To further improve the stability of sulfide solid electrolytes, in some embodiments, the sulfur element occupies 0.1 to 0.5% of the 4aWyckoff site, with the remainder being Cl, X, and Q elements.

[0078] In some embodiments, the sulfide solid electrolyte further contains an element M, which includes alkali metals and / or alkaline earth metals. In one specific embodiment, the element M includes lithium (Li), meaning the active metal ion in the sulfide solid electrolyte can be Li ions. The solid electrolyte can conduct cations formed by the element M; for example, if M is Li, the solid electrolyte conducts lithium ions.

[0079] In the sulfide solid electrolyte of this disclosure, element M further includes alkali metal elements other than Li. In some embodiments, element M also includes metal elements with atomic radii larger than Li; preferably, the metal elements with atomic radii larger than Li include sodium and / or potassium. These metal elements with larger atomic radii can better induce lattice expansion, further reducing the migration resistance of ions in the lattice, thereby better expanding the migration channels for lithium ions or other charge carriers, and contributing to further improving the ionic conductivity of the sulfide solid electrolyte.

[0080] In some embodiments of this disclosure, when element M includes at least one of element Li, element Na, and element K, the embodiments of this disclosure further improve the conductivity of sulfide solid electrolyte particles by controlling the molar ratio of element Li, element Na, and element K in element M.

[0081] In one specific embodiment, the molar percentage g of Na in element M is 0% < g ≤ 20%. For example, the molar percentage of Na in element M is, for instance, a range of 0.01%, 5%, 10%, 15%, 20%, or any combination thereof.

[0082] In one specific implementation, the molar percentage h of element K in element M is 0% < h ≤ 10%. For example, the molar percentage h of element K in element M is, for example, a range of 0.01%, 5%, 10%, or any combination thereof.

[0083] Preferably, in some embodiments, the occupancy fraction of element M at the 24g Wyckoff site is 0.1 to 0.52; preferably, the sites at the 24g Wyckoff site not occupied by element M are vacant.

[0084] Preferably, in one specific embodiment, the occupancy fraction of element M at the 48h Wyckoff site is 0.2 to 0.42; preferably, the sites at the 48h Wyckoff site not occupied by element M are vacant.

[0085] In this embodiment, the M element is distributed in the lattice in the above-described occupation manner, which can provide more movable space and more flexible migration paths for lithium ions, which is beneficial to further reduce mutual obstruction between ions, thereby improving the ionic conductivity of the sulfide solid electrolyte.

[0086] Specifically, when M includes multiple elements, the occupancy fractions of element M at the 24g Wyckoff site (the sum of the occupancy fractions of each element at the 24g Wyckoff site) and the occupancy fractions of element M at the 48h Wyckoff site (the sum of the occupancy fractions of each element at the 48h Wyckoff site) can be tested using conventional methods in the art. For example, sulfide solid electrolytes can be tested using refined XRD, and the diffraction data can be obtained by fitting the Rietveld method with an error factor of less than 10%.

[0087] In some embodiments, the molar percentage of Li in element M is 70% to 100%. For example, the molar percentage of Li in element M is, for instance, a range of 70%, 80%, 90%, 100%, or any combination thereof. When the molar percentage of Li in element M is within the above range, the ionic conductivity of the sulfide solid electrolyte can be further improved.

[0088] In some embodiments of this disclosure, the sulfide solid electrolyte includes sulfide solid electrolyte particles, at least a portion of which includes a core region and a surface region present on at least a portion of the surface of the core region, wherein the core region and the surface region each independently include a sulfide electrolyte.

[0089] The core region's sulfide electrolyte includes M 6-y PS 5-y Cl 1+y-a X a ;

[0090] The sulfide electrolyte in the surface region includes M 6-y PS 5-y-z Cl 1+y-a Q z X a and / or M 6-y P 1-m D m S 5-y Cl 1+y-a X a ;

[0091] Among them, the M element includes alkali metal elements and / or alkaline earth metal elements;

[0092] Element X includes at least one of F, Br, and I;

[0093] The D element includes at least one of the elements As, Sb, Bi, Sn, and In.

[0094] a≥0, m>0;

[0095] 0 < y < 5; Z > 0;

[0096] 5-yz>0;

[0097] 1+ya>0.

[0098] In some embodiments, the sulfide electrolyte in the core region of the sulfide solid electrolyte includes M 6-y PS 5-y Cl 1+y-a X a ; The surface region includes M 6-y PS 5-y-z Cl 1+y-a Q z X a and M 6-y P 1-m D m S 5-y Cl 1+y-a X a At least one of the above-described structures. The sulfide solid electrolyte of the present disclosure has the above-described structural formula, and its surface stability and ionic conductivity can be further improved.

[0099] It should be clarified that the core region and the surface region have the same crystal structure. The surface region of the sulfide solid electrolyte may include Q and D elements, or may only include one of Q or D elements.

[0100] The chemical element composition of the core and surface regions of the aforementioned solid electrolyte particles can be tested using common methods, such as X-ray diffraction, transmission electron microscopy, and synchrotron radiation X-ray absorption fine structure analysis.

[0101] In some embodiments, 0 ≤ a ≤ 0.7, so that the X element has a more suitable doping ratio, thereby giving the sulfide solid electrolyte better ionic conductivity.

[0102] In one specific embodiment, when 0.3≤y≤0.7, the doping of Cl element further improves the ionic conductivity of the sulfide solid electrolyte.

[0103] In one specific embodiment, when D element is doped into a sulfide solid electrolyte at a doping ratio of 0.05≤m≤0.3, its ionic conductivity can be further improved.

[0104] To better balance the ionic conductivity and stability of the sulfide solid electrolyte, in some embodiments, the volume fraction of the surface region in the sulfide solid electrolyte particles is 5% to 30%, for example, the volume fraction of the surface region in the sulfide solid electrolyte is, for example, a range of 5%, 10%, 15%, 20%, 25%, 30%, or any combination thereof.

[0105] In practice, the volume percentage of the above elements can be obtained by FIB slicing to obtain the cross section of the sulfide solid electrolyte, and then by EDS measurement to obtain the volume occupied by the elements from the core region to the surface region in the selected area (which can be any region selected from the surface of the surface region to the core region in which the volume percentage of the above elements needs to be statistically calculated).

[0106] In some embodiments of this disclosure, the core region and the surface region have the same crystal form. When the core region and the surface region have the same crystal form, it is more conducive to forming a continuous and uniform ion transport path, further reducing the resistance encountered by active metal ions during transport within the sulfide solid electrolyte, thereby improving the ion conductivity of the conductive agent. Preferably, the core region and the surface region comprise an argyrogermanium sulfide electrolyte with a silver sulfide crystal form.

[0107] This disclosure also provides a method for preparing a sulfide solid electrolyte, which includes the following steps:

[0108] A halogen-containing solid electrolyte raw material was surface modified using a Q source to form a surface region, thereby obtaining a sulfide solid electrolyte including a core region and a surface region existing on at least part of the surface of the core region. The halogen occupancy fraction at the 4d Wyckoff site in the crystal structure of the sulfide solid electrolyte was 0.68–0.85.

[0109] This disclosure discloses an embodiment of a sulfide solid electrolyte that can be prepared using the aforementioned method. In this sulfide solid electrolyte, the core region and the surface region are continuously distributed, meaning the surface region grows within at least a portion of the surface of the core region. The content of element Q decreases from the surface of the surface region towards the core region, thus improving the surface stability of the sulfide solid electrolyte. In the crystal structure of the sulfide solid electrolyte prepared by this method, the halogen fraction at the 4d Wyckoff sites is 0.68–0.85, further enhancing the anionic disorder within the sulfide solid electrolyte. Therefore, the sulfide solid electrolyte prepared by the aforementioned method exhibits high ionic conductivity and surface stability, which is beneficial for improving the battery's safety performance and electrochemical performance such as conductivity.

[0110] In some embodiments, the Q source includes at least one of the O source and the Se source, which further improves the surface stability of the sulfide solid electrolyte.

[0111] In some embodiments, the method for preparing solid electrolyte raw materials includes: sintering raw materials including M source, S source, P source, Cl source and X source to obtain solid electrolyte raw materials.

[0112] In one specific embodiment, the sintering temperature is 300–500°C, and the processing time is 1–15 h. For example, the sintering temperature is, for example, a range of 300°C, 350°C, 400°C, 450°C, 500°C, or any combination thereof; the sintering time is, for example, a range of 1 h, 5 h, 10 h, 15 h, or any combination thereof. By further controlling the sintering temperature and time, this embodiment of the present disclosure enables better bonding between raw material particles, which is more conducive to the preparation of sulfide solid electrolytes with good ionic conductivity.

[0113] In detail, in order to obtain raw material particles including M source, S source, P source, Cl source and X source, in some embodiments, the raw materials including M source, S source, P source, Cl source and X source are subjected to ball milling and cold pressing in sequence to obtain raw material particles before sintering.

[0114] In the ball milling process described above, the purpose is twofold: firstly, to ensure uniform mixing of the raw materials, and secondly, to obtain raw material particles with a more uniform particle size. This disclosure does not impose any specific limitations on the particle size of the raw materials; the size can be selected according to actual conditions. For example, the D50 of the raw material particles can be 0.3–15 μm.

[0115] Furthermore, to obtain more uniformly mixed raw material particles, in some embodiments, the ball milling speed is 500–800 r / min, and the processing time is 10–15 h. For example, the ball milling speed is, for example, a range of 500 r / min, 600 r / min, 700 r / min, 800 r / min, or any combination thereof, and the ball milling time is, for example, a range of 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, or any combination thereof.

[0116] The aforementioned cold pressing process can be performed using conventional instruments, such as hydraulic presses or mechanical presses. This disclosure does not impose specific limitations on the processing time, temperature, or pressure of the cold pressing process, as long as the raw material particles are obtained. For example, the processing pressure of the cold pressing process is 200–300 MPa, and the temperature is 20–30°C.

[0117] In specific implementation, when the M element is the Li element, the M source can be a compound containing the Li element. For example, the raw materials including the M source, S source, P source, Cl source, and X source can be Li2S, P2S5, LiCl, and LiX (X = F, Br, or I).

[0118] When element M includes element Na, source M can be a compound containing element Na. For example, source M may include one or more of NaCl and Na2S.

[0119] When element M includes element K, the source of M can be a compound containing element K. For example, the source of M may include one or more of KCl and K2S.

[0120] In this embodiment of the disclosure, the process of surface modification of a halogen-containing solid electrolyte raw material using a Q source includes: calcining a mixed system comprising a Q source and a halogen-containing solid electrolyte raw material to achieve surface modification.

[0121] In some embodiments, this disclosure further facilitates the acquisition of sulfide solid electrolytes with higher ionic conductivity and surface stability by controlling the calcination temperature and time. Specifically, the calcination temperature is 200–400°C, and the processing time is 5–15 h. For example, the calcination temperature is, for example, a range of 200°C, 250°C, 300°C, 350°C, 400°C, or any combination thereof; the calcination time is, for example, a range of 5 h, 10 h, 15 h, or any combination thereof.

[0122] In detail, in the above preparation process, the embodiments of this disclosure first employ a sintering process to form a halogen-containing solid electrolyte raw material from raw material particles including M source (M source is an active ion source), S source, P source, Cl source, and X source. The halogen-containing solid electrolyte raw material is a spherical or near-spherical particle with a complete structure (i.e., integrally formed by sintering, with no internal interface). Next, based on the above-mentioned complete structure, the embodiments of this disclosure dope the Q source from the outer surface to the inner surface of the sulfide solid electrolyte precursor. The degree of contact between the Q source and the inner and outer surfaces of the sulfide solid electrolyte precursor differs. This results in a gradient distribution of the above elements in the portion near the outer surface of the solid electrolyte raw material, achieving surface modification of the halogen-containing solid electrolyte raw material by the Q source to obtain the sulfide solid electrolyte.

[0123] In some embodiments, the Q source is an oxygen-enriched gas (O2 / Ar mixture), and the oxygen content in the calcination process ranges from 5% to 20%. By using an oxygen-enriched gas (O2 / Ar mixture) as the Q source and further controlling the oxygen content in the calcination process to be 5% to 20%, this method is beneficial for obtaining a sulfide solid electrolyte with better surface stability. For example, the oxygen content in the calcination process may be, for instance, 5%, 10%, 15%, 20%, or any combination thereof.

[0124] When the Q source is Se, Li6PS5Cl powder and Se powder can be mixed under an inert atmosphere, ball-milled at 200-300℃ and 300-900 r / min for 1-3 hours, and then calcined at 100-250℃ for 12-24 hours to obtain Se-doped sulfide solid electrolyte.

[0125] In some embodiments, the mixed system further includes a D source containing D element, which includes at least one element selected from As, Sb, Bi, Sn, and In, thereby further improving the surface stability of the sulfide solid electrolyte.

[0126] Specifically, by mixing raw material particles including M source, S source, P source, Cl source, and X source and then subjecting them to sintering, a mixture containing M can be obtained. 6-y PS 5-y Cl 1+y-a X a The present disclosure does not impose any special limitations on the form and source of the raw material particles, including M source, S source, P source, Cl source, and X source; selection can be made according to the actual situation. It is understood that, in order to avoid the influence of air components on the synthesis of the sulfide solid electrolyte precursor, sintering treatment under a protective atmosphere, such as argon, is required.

[0127] The sulfide solid electrolyte precursor is calcined with a Q source and / or a D source to obtain the sulfide solid electrolyte. Specifically, the sulfide solid electrolyte precursor can be calcined with both the Q source and the D source, or it can be calcined with either the Q source or the D source.

[0128] After calcination, the sulfide solid electrolyte of this embodiment includes a core region and a surface region grown on at least a portion of the surface of the core region. The core region includes M. 6-y PS 5-y Cl 1+y-a X a The surface region includes M 6-y PS 5-y-z Cl 1+y-a Q z X a and M 6-yP 1-m D m S 5-y Cl 1+y-a X a At least one of them. Specifically, the surface region of the sulfide solid electrolyte, obtained by calcining the sulfide solid electrolyte precursor with a Q source, includes M... 6-y PS 5-y-z Cl 1+y-a Q z X a After calcining the sulfide solid electrolyte precursor with a D source, the surface region of the resulting sulfide solid electrolyte includes M. 6-y P 1-m D m S 5-y Cl 1+y-a X a .

[0129] In this embodiment of the disclosure, the occupancy fraction of each of the above elements at Wyckoff sites in the crystal can be controlled by the feeding ratio of M source, S source, P source, Cl source, X source, Q source and D source.

[0130] When element D includes element As, the source of D can be a compound that includes element As. For example, the source of D can include one or more of As2S3, As2S5, and As powder.

[0131] When element D includes element Sb, the source of D can be a compound that includes element Sb. For example, the source of D can include one or more of Sb2S3, SbCl3, and Sb powder.

[0132] When element D includes element Bi, the source of D can be a compound that includes element Bi. For example, the source of D can include one or more of Bi2S3, BiCl3, and Bi powder.

[0133] When element D includes element Sn, the source of D can be a compound that includes element Sn. For example, the source of D can include one or more of SnS, SnS2, SnCl2, and Sn powder.

[0134] When element D includes element In, the source of D can be a compound that includes element In. For example, the source of D can include one or more of In2S3, InCl3, and In powder.

[0135] In this embodiment, the sulfide solid electrolyte or the sulfide solid electrolyte prepared by the above-described method can be used alone as a solid electrolyte in a battery. Alternatively, other components such as polymers (ethylene oxide (PEO), polyvinylidene fluoride (PVDF), etc.) and metal oxides (Al2O3, SiO2, ZrO2, etc.) can be added to further improve the ionic conductivity, stability, and other properties of the sulfide solid electrolyte.

[0136] This disclosure also provides an electrode comprising the above-described sulfide solid electrolyte. The electrode and the sulfide solid electrolyte have corresponding advantages, which will not be elaborated here.

[0137] The electrode in this embodiment can be a positive or negative electrode. The electrode includes an electrode sheet, which includes an electrode current collector and an electrode active layer disposed on at least one side of the electrode current collector. The electrolytic active layer includes the aforementioned sulfide solid electrolyte.

[0138] This disclosure also provides a solid electrolyte membrane, including the above-mentioned sulfide solid electrolyte or the sulfide solid electrolyte prepared according to the above-mentioned method for preparing sulfide solid electrolyte. The solid electrolyte membrane has corresponding advantages over the sulfide solid electrolyte, which will not be elaborated here.

[0139] This disclosure also provides a battery including the electrodes described above and / or the solid electrolyte membrane described above. This battery has advantages corresponding to the sulfide solid electrolytes described above, which will not be elaborated upon here.

[0140] Specifically, the battery in this embodiment is a solid-state battery. The battery includes a positive electrode, a negative electrode, and a solid electrolyte membrane located between the positive and negative electrodes. The solid electrolyte membrane includes the aforementioned sulfide solid electrolyte. The sulfide solid electrolyte forms a physical barrier between the positive and negative electrodes of the solid-state battery and also acts as an ion conductor, allowing lithium ions to move smoothly between the two electrodes during charging and discharging.

[0141] Generally, the aforementioned solid-state battery includes a solid electrolyte, a cell, and a casing for encapsulating the cell. The solid electrolyte is located between the positive and negative electrodes of the solid-state battery and is assembled within the cell inside the casing. The cell includes electrode plates (including positive and negative electrode plates). The cell can be a stacked cell, meaning it is composed of alternating layers of positive electrode plates, a separator, and a negative electrode plate; or it can be a wound cell, meaning it is composed of stacked positive electrode plates, a separator, and a negative electrode plate, which are then wound together. In specific implementations, a stacked cell can be formed by alternating layers of positive electrode plates, a separator, and a negative electrode plate, and then the cell can be encapsulated using an aluminum-plastic film.

[0142] In this embodiment of the disclosure, the battery cell can be packaged using conventional housing materials in the art, such as flexible packaging materials like aluminum-plastic film, but is not limited thereto.

[0143] The embodiments disclosed herein can assemble components such as positive electrode, separator and negative electrode into a battery using conventional methods in the art. For example, positive electrode, solid electrolyte and negative electrode can be stacked alternately to obtain a stacked cell (or wound into a wound cell); then the cell is placed in a casing (outer packaging) to obtain a battery.

[0144] In this embodiment of the present disclosure, the positive electrode sheet includes a positive current collector and a positive active material layer. Specifically, the positive active layer can be provided on one side surface of the positive current collector in the thickness direction, or the positive active layer can be provided on both sides of the positive current collector in the thickness direction.

[0145] The positive electrode active material layer may include positive electrode active material, conductive agent and binder. In the positive electrode coating, the mass percentage of positive electrode active material may be 70% to 99%, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99% or any combination thereof. The mass fraction of binder may be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15% or any combination thereof.

[0146] The binder for the positive electrode active material layer can be the binder material provided in this disclosure alone, or it can be a composite of one or more of the following: polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, etc., used as the binder for the positive electrode active material layer.

[0147] In some embodiments, the positive electrode active material may include LiCoO2, LiNiO2, or LiCo. x Ni 1-x O2 (0≤x≤1), LiCo x Ni 1-x-y Al y O2(0≤x≤1,0≤y≤1), LiMn2O4, LiFe x Mn y M z O4 (M is one or more of Al, Mg, Ga, Cr, Co, Ni, Cu, Zn or Mo, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1), Li 1+x L 1－y－zM y N z O2 (L, M, N are one or more of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1), LiFePO4, Li3V2(PO4)3, Li3V3(PO4)3, LiVPO4F, Li2CuO2, Li5FeO4, and metal sulfides and oxides (such as TiS2, V2S3, FeS, FeS2, LiMS) x (M is at least one of the transition metal elements such as Ti, Fe, Ni, Cu, Mo, etc., 1≤x≤2.5), TiO2, Cr3O8, V2O5, MnO2, etc.

[0148] The embodiments disclosed herein may employ conventional positive current collectors in the art, for example, positive current collectors may include aluminum foil.

[0149] In this embodiment, the positive electrode sheet can be prepared by conventional methods in the art, such as by coating. Specifically, the positive electrode active material, conductive agent, binder, and other components used to form the positive electrode active layer can be dispersed in a solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry. This slurry is then coated onto the surface of the positive electrode current collector, and after drying, rolling, and other processes, the positive electrode sheet is obtained. The coating, drying, and rolling processes involved are conventional operations for preparing positive electrode sheets using the coating method, and are not particularly limited thereto.

[0150] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer can be provided on one side surface of the negative electrode current collector in the thickness direction, or negative electrode active material layers can be provided on both opposite sides surface of the negative electrode current collector in the thickness direction.

[0151] In the embodiments of this disclosure, the binder in the negative electrode active material layer can be either the binder material provided in this disclosure alone, or it can be used in combination with any binder suitable for negative electrodes known in the art. For example, at least one of the following can be used together with the binder material provided in this disclosure in the preparation of the negative electrode active material layer: polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), tetrafluoroethylene and its copolymers, polyvinylidene fluoride and its copolymers, polyolefins and their copolymers (e.g., polyethylene-polyethylene glycol block copolymers), polyethers and their copolymers (e.g., polyethylene oxide), polyphenylene ethers and their copolymers, polysiloxanes and their copolymers (e.g., polydimethylsiloxane, poly(dimethylsiloxane-co-alkylmethylsiloxane)), polyesters and their copolymers (e.g., polyethylene ester, polyvinyl acetate, polyacrylate, etc.), carboxymethyl cellulose, styrene-butadiene latex, nitrile rubber, and polyacrylic acid (PAA).

[0152] Specifically, polyolefins include one or more of polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / vinylidene fluoride copolymer, and propylene / vinylidene fluoride copolymer; polytetrafluoroethylene and its copolymers may be at least one of tetrafluoroethylene / ethylene copolymer, tetrafluoroethylene / propylene copolymer, tetrafluoroethylene / vinylidene fluoride copolymer, tetrafluoroethylene / ether copolymer, tetrafluoroethylene / branched polyether copolymer, tetrafluoroethylene / vinyl ether copolymer, tetrafluoroethylene / branched polyether / vinyl ether copolymer, and tetrafluoroethylene / siloxane copolymer.

[0153] In addition, the negative electrode active material layer also includes a negative electrode active material. Specifically, the negative electrode active material may include graphite, and the conductive agent may include one or more of conductive carbon black, carbon nanotubes (CNT), acetylene black, graphene, Ketjen black, and carbon fiber.

[0154] This disclosure also provides a battery assembly including one or more of the above-described batteries. This battery assembly has advantages corresponding to the above-described sulfide solid electrolyte, which will not be described in detail here.

[0155] Generally, a battery assembly includes multiple batteries as individual cells, connected to form the battery assembly. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a hybrid connection including these methods, without particular limitation. This disclosure also provides a battery assembly including one or two batteries from any of the above embodiments. The battery assembly can be a battery pack or a battery module, etc.

[0156] This disclosure also provides an electrical device including the aforementioned battery or battery assembly. This electrical device has advantages over the aforementioned sulfide solid electrolyte, which will not be elaborated further.

[0157] The electrical equipment provided in this disclosure can be conventional electrical equipment in the field, such as power equipment (e.g., two-wheeled, three-wheeled or four-wheeled electric vehicles), electrical equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without any particular limitation.

[0158] The technical solutions of this disclosure are further described below with reference to specific embodiments.

[0159] Example 1

[0160] The sulfide solid electrolyte of this embodiment is prepared through the following steps:

[0161] 1) The raw materials Li2S, P2S5, LiCl and LiBr are mixed in a certain molar ratio and placed in a ball mill. The mixture is then ball-milled at a speed of 500 r / min for 15 h to obtain a mixture. The mixture is then cold-pressed into particles and sintered at 400℃ in a protective atmosphere for 5 h to obtain a sulfide solid electrolyte precursor.

[0162] 2) Sulfide solid electrolyte was obtained by calcination at 250°C for 7 hours under an oxygen / argon mixed atmosphere with an oxygen partial pressure of 10%.

[0163] The composition of the core region, the composition of the surface region, the fraction of element M at the 24g Wyckoff site (abbreviated as M 24g in the table), the fraction of element M at the 48h Wyckoff site (abbreviated as M 48h in the table), the fraction of elements Cl and X at the 4d Wyckoff site (abbreviated as Cl+X 4d in the table), and the fraction of element S at the 4a Wyckoff site (abbreviated as S 4a in the table) of the sulfide solid electrolyte in this embodiment are shown in Table 1; the volume fraction of the surface region in the sulfide solid electrolyte, the thickness ratio of the surface region to the core region, the molar percentage of element Li in element M, the molar percentage of element Na in element M, and the molar percentage of element K in element M are shown in Table 2.

[0164] Examples 2-3 are basically the same as Example 1, except that the molar ratio of raw materials Li2S, P2S5, LiCl and LiBr added in step 1) of Examples 2-3 is different.

[0165] Example 4

[0166] This embodiment is basically the same as Embodiment 1, except that LiBr is not added in step 1) of this embodiment.

[0167] Example 5

[0168] This embodiment is basically the same as embodiment 1, except that the molar ratio of raw materials Li2S, P2S5, LiCl and LiBr added in step 1) of this embodiment is different.

[0169] Example 6

[0170] This embodiment is basically the same as embodiment 4, except that the molar ratio of raw materials Li2S, P2S5 and LiCl added in step 1) is different; step 2) is to calcine at 200°C for 8 hours under an oxygen atmosphere with an oxygen partial pressure of 5% to obtain sulfide solid electrolyte.

[0171] Example 7

[0172] This embodiment is basically the same as embodiment 4, except that the molar ratio of raw materials Li2S, P2S5 and LiCl added in step 1) is different; step 2) is to calcine at 200°C for 8 hours under an oxygen atmosphere with an oxygen partial pressure of 12% to obtain a sulfide solid electrolyte.

[0173] Example 8

[0174] This embodiment is basically the same as embodiment 4, except that the molar ratio of raw materials Li2S, P2S5 and LiCl added in step 1) is different; step 2) is to calcine at 200°C for 9 hours under an oxygen atmosphere with an oxygen partial pressure of 15% to obtain a sulfide solid electrolyte.

[0175] Example 9

[0176] This embodiment is basically the same as embodiment 1, except that the raw materials added in step 1) of this embodiment are Li2S, P2S5, LiCl, and LiI, and the molar ratio of Li2S, P2S5, LiCl, and LiI is different from that in the embodiment.

[0177] Example 10

[0178] This embodiment is basically the same as embodiment 4, except that step 2) in this embodiment is to calcine at 300°C for 15 hours under an oxygen atmosphere with an oxygen partial pressure of 12% to obtain a sulfide solid electrolyte.

[0179] Example 11

[0180] This embodiment is basically the same as embodiment 1, except that the raw materials added in step 1) of this embodiment are Li2S, P2S5, LiCl and NaCl.

[0181] Example 12

[0182] This embodiment is basically the same as embodiment 1, except that the raw materials added in step 1) of this embodiment are Li2S, P2S5, LiCl, NaCl and KCl.

[0183] Example 13

[0184] This embodiment is basically the same as embodiment 1, except that the raw materials added in step 1) of this embodiment are Li2S, P2S5 and LiCl; step 2) is to mix Se powder and precursor in Ar in proportion, ball mill at 180°C for 3 hours at 500 r / min, take it out and calcine at 150°C for 12 hours to obtain sulfide solid electrolyte.

[0185] Example 14

[0186] This embodiment is basically the same as embodiment 1, except that the raw materials added in step 1) of this embodiment are Li2S, P2S5, LiCl, etc.; in step 2), In powder and precursor are mixed in Ar in proportion, ball milled at 180°C for 3 hours at 400r / min, and then taken out and calcined at 150°C for 12 hours to obtain sulfide solid electrolyte.

[0187] Comparative Example 1

[0188] The preparation process of this comparative example is as follows: Li2S, P2S5, LiCl and LiBr raw materials are mixed and placed in a ball mill. The mixture is ball milled at a speed of 800 r / min for 15 h to obtain a mixture. The mixture is then cold-pressed into particles and annealed at 500℃ in a protective atmosphere for 5 h to obtain a sulfide solid electrolyte.

[0189] Comparative Example 2

[0190] The preparation process of this comparative example is as follows: Li2S, P2S5, LiCl and LiO raw materials are mixed and placed in a ball mill. The mixture is ball milled at a speed of 600 r / min for 15 h to obtain a mixture. The mixture is then cold-pressed into particles and annealed at 3500℃ in a protective atmosphere for 6 h to obtain a sulfide solid electrolyte.

[0191] Comparative Example 3

[0192] The preparation process of this comparative example is as follows: Li₂S, P₂S₅, and LiCl raw materials were mixed and placed in a ball mill. The mixture was then ball-milled at 800 r / min for 15 h to obtain a final mixture. Li₂S was then added... 5.5 PS 4.4 O 0.1 Cl 1.5 The mixture was then ball-milled at 600 r / min for 5 hours, and then cold-pressed into granules. The granules were then annealed at 500°C in a protective atmosphere for 6 hours to obtain a sulfide solid electrolyte.

[0193] Comparative Example 4

[0194] This embodiment is basically the same as embodiment 4, except that the molar ratio of Li2S, P2S5 and LiCl added in step 1) of this comparative example is different; step 2) is to calcine at 200°C for 10h under an oxygen atmosphere with an oxygen partial pressure of 20% to obtain a sulfide solid electrolyte.

[0195] Comparative Example 5

[0196] This comparative example is basically the same as Example 4, except that the molar ratio of the raw materials Li2S, P2S5, and LiCl added in this comparative example is different from that in Example 4.

[0197] Comparative Example 6

[0198] This comparative example is basically the same as Example 4, except that the molar ratio of raw materials Li2S, P2S5, and LiCl added in step 1) of this comparative example is different from that in Example 4.

[0199] Test case

[0200] Test methods for the core region components, surface region components, and the mass percentages of Li, Na, and K in the M element: Cross-sections of the solid electrolytes in the examples and comparative examples were obtained using a Zeiss Crossbeam 550 dual-beam scanning electron microscope via focused ion beam (FIB) sectioning. The mass content of each element from the center to the surface of the cross-section was measured by EDS, and the volume fraction of the surface region in the solid electrolyte was calculated. The test results are shown in Table 1 (mass percentages of Li in the M element, Li in the M element, Na in the M element, and K in the M element).

[0201] The method for determining the occupancy fraction of Wyckoff sites in the core and surface regions was to first test the sulfide solid electrolyte using refined XRD. The refined XRD characterization method was as follows: the solid electrolytes in the examples and comparative examples were scanned using Cu target Kα1 rays with a scanning range of 10-90°. The refined diffraction data were obtained by fitting using the Rietveld method, and the error factor of the fitting results was less than 10%. The test results are shown in Table 1.

[0202] Volume fraction test of the surface region in the solid electrolyte: Cross-sections of the solid electrolytes in the examples and comparative examples were obtained using a Zeiss Crossbeam 550 dual-beam scanning electron microscope via focused ion beam (FIB) sectioning. EDS measurements were used to determine the distribution of elements from the center to the surface of the cross-section, thus obtaining the volume occupied by the region containing element Q in the solid electrolyte (i.e., the volume fraction of the surface region in the solid electrolyte). Similarly, the thickness ratio of the surface region to the core region could be measured using the same method. The test results are shown in Table 2 (volume fraction of the surface region in the solid electrolyte).

[0203] The conductivity of the solid electrolytes obtained in the examples and comparative examples was tested using the following method: 50 mg of solid electrolyte powder was weighed and placed in an insulating sleeve with an inner diameter of 10 mm. It was then pressurized at 400 MPa and subjected to AC impedance spectroscopy to measure the impedance value of the electrolyte material. The thickness and area of ​​the pressurized sheet electrolyte material were then measured. Based on the impedance value, thickness, and area, the ionic conductivity of the solid electrolyte was calculated using the formula σ = d / (R × S), where σ is the ionic conductivity (S / cm), d is the thickness (cm), R is the impedance value (Ω), and S is the area (cm²). 2 The test results are shown in Table 3 (conductivity).

[0204] The air stability test method is as follows: Weigh 50 mg of solid electrolyte powder and place it in an insulating sleeve with an inner diameter of 10 mm. Pressurize it at 400 MPa and place it in a humid, sealed container with an H2S gas sensor for 30 minutes. Calculate the amount of H2S gas produced by the sample based on the H2S concentration measured by the H2S gas sensor. The temperature during the measurement was 30℃ and the relative humidity was 20%. The test results are shown in Table 3 (H2S production).

[0205] Table 1

[0206] Table 2

[0207] Table 3

[0208] As shown in the table, compared to the comparative example, the embodiments of this disclosure achieve both high stability and ionic conductivity of the sulfide solid electrolyte by controlling the occupancy fraction of halogens at the 4d Wyckoff sites in the crystal structure of the sulfide solid electrolyte to be 0.68–0.85. Compared to Example 10, other embodiments of this disclosure further improve the stability and ionic conductivity of the sulfide solid electrolyte by further controlling the volume fraction of the surface region in the solid electrolyte to be 5–30%.

[0209] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit them. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this disclosure.

Claims

A sulfide solid-state electrolyte characterized by The sulfide solid electrolyte contains halogens, and in the crystal structure of the sulfide solid electrolyte, the halogen occupies 0.68 to 0.85% of the 4d Wyckoff site. The sulfide solid-state electrolyte according to claim 1, characterized in that, The sulfide solid electrolyte comprises sulfide solid electrolyte particles, at least a portion of which includes a core region and a surface region present on at least a portion of the surface of the core region. The core region and the surface region each independently comprise a sulfide electrolyte, and the surface region contains an element Q, which includes O and / or Se. The sulfide solid electrolyte according to claim 1 or 2, characterized in that, The sulfide solid electrolyte contains the element Q, which includes O and / or Se; in the crystal structure of the sulfide solid electrolyte material, some sites in the 4d Wyckoff sites are occupied by the element Q and the element sulfur. The sulfide solid-state electrolyte according to any one of claims 1 to 3, characterized in that, The halogen includes elements Cl and X, wherein element X includes at least one of F, Br, and I. The sulfide solid electrolyte according to claim 2 is characterized in that, The core region contains the halogen; And / or, the surface region contains the halogen. The sulfide solid electrolyte according to claim 2 or 5, characterized in that, The mass content of the Q element in the surface region decreases along the direction from the surface region to the core region; And / or, the mass content of the Q element in the surface region is 0.29% to 1.53%. The sulfide solid electrolyte according to any one of claims 2, 5, 6, characterized in that, The surface region contains element D, which includes at least one of As, Sb, Bi, Sn, and In. The sulfide solid electrolyte according to claim 7 is characterized in that, The mass content of the D element in the surface region decreases along the direction from the surface region to the core region. The sulfide solid electrolyte according to any one of claims 2, 5 to 8, characterized in that, The mass content of sulfur in the core area is greater than that in the surface area. The sulfide solid-state electrolyte according to any one of claims 1 to 9, characterized in that, In the crystal structure of the sulfide solid electrolyte, the sulfur element occupies 0.1 to 0.5% of the 4a Wyckoff site. The sulfide solid-state electrolyte according to any one of claims 1 to 10, characterized in that, The sulfide solid electrolyte also contains element M, which includes element Li. The sulfide solid-state electrolyte according to claim 11, characterized in that, The M element also includes a metal element with an atomic radius greater than that of the Li element; preferably, the metal element with an atomic radius greater than that of the Li element includes the Na element and / or the K element; Preferably, the molar percentage (g) of Na in the M element is 0% < g ≤ 20%; Preferably, the molar percentage h of element K in element M is 0% < h ≤ 10%. The sulfide solid electrolyte according to claim 11 or 12, characterized in that, In the crystal structure of the sulfide solid electrolyte, the M element occupies 0.10 to 0.52% of the 24g Wyckoff site; preferably, the sites of the 24g Wyckoff site not occupied by the M element are vacant. The sulfide solid electrolyte according to claim 11 or 12, characterized in that, In the crystal structure of the sulfide solid electrolyte, the M element occupies 0.2 to 0.42% of the 48h Wyckoff site; preferably, the sites of the 48h Wyckoff site not occupied by the M element are vacant. The sulfide solid-state electrolyte according to any one of claims 11 to 14, characterized in that, The molar percentage of Li in the M element is 70% to 100%. The sulfide solid-state electrolyte according to claim 1, characterized in that, The sulfide solid electrolyte includes sulfide solid electrolyte particles, at least a portion of the sulfide solid electrolyte particles including a core region and a surface region present on at least a portion of the surface of the core region, the core region and the surface region each independently including sulfide electrolyte; The sulfide electrolyte of the core region comprises M 6-y PS 5-y Cl 1+y-a X a ; The sulfide electrolyte of the table layer region comprises M 6-y PS 5-y-z Cl 1+y-a Q z X a and / or M 6-y P 1-m D m S 5-y Cl 1+y-a X a ; M elements include alkali metal elements and / or alkaline earth metal elements; Element X includes at least one of F, Br, and I; The D element includes at least one of the elements As, Sb, Bi, Sn, and In. a≥0, m>0; 0＜y＜5； Z＞0； 5-yz>0; 1+ya>0. The sulfide solid electrolyte according to claim 16 is characterized in that, 0≤a≤0.7； And / or, 0.3≤y≤0.7; And / or, 0.05≤z≤0.25; And / or, 0.05≤m≤0.

3. The sulfide solid-state electrolyte according to claim 2, characterized in that, The surface region has a volume fraction of 5-30% in the sulfide solid electrolyte particles. The sulfide solid-state electrolyte according to claim 2, characterized in that, The core region and the surface region have the same crystal form; preferably, the core region and the surface region comprise silver sulfide electrolytes of the argyrophthalite type. An electrode characterized by Includes the sulfide solid electrolyte according to any one of claims 1-19. A solid-state electrolyte membrane characterized by Includes the sulfide solid electrolyte according to any one of claims 1-19. A battery characterized by Includes the electrode of claim 20 and / or the solid electrolyte membrane of claim 21. A battery assembly comprising one or more batteries as described in claim 22. An electric device characterized by comprising: It includes the battery of claim 22, or the battery assembly of claim 23.

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