Sulfide electrolyte and preparation method and application thereof

Abstract

The present invention provides a sulfide electrolyte and a preparation method and application thereof, and relates to the technical field of all-solid-state batteries, and the preparation method comprises the following steps: a phosphorus source, a sulfur source, a halogen source and a first additive are mixed to obtain a first mixture, the first additive comprises a phosphorus-sulfur compound, and the phosphorus-sulfur compound is less than the phosphorus source as a raw material, and is less than the phosphorus source as a raw material. The polymer has an irregular molecular structure; carrying out primary calcination on the first mixture to obtain a first calcined material; the first sintered material is mixed with a second additive to obtain a second mixture, and the second additive comprises a metal oxide; and carrying out secondary calcination on the second mixture to obtain the sulfide electrolyte. The method comprises the following steps: modifying LPSC particles by using a first additive (preferably phosphorus pentasulfide) to regulate and control electron cloud distribution in unit cells for the first time, modifying again by using a multi-metal element high-entropy process to regulate and control electron cloud distribution, and effectively improving the steady state of LPSC through two times of modification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of all-solid-state batteries, in particular to a sulfide electrolyte and a preparation method and application thereof. BACKGROUND

[0002] The sulfide solid electrolyte is a core factor for the industrial production of solid-state batteries, and its steady state, high ionic conductivity, processing technology and price are the difficulties to be solved. Among them, Li6PS5Cl (LPSC) is a representative sulfide electrolyte.

[0003] Currently, the academic community has conducted a large number of studies on the improvement of the stability of LPSC sulfide electrolytes. Common strategies include the introduction of halogen elements (such as F, Cl, Br, and I), the compounding of metal fluorides (such as MgF2 and CaF2), and the doping of some metal or non-metal elements (1. Lei Zhou, Xin Wei, Junxiang Zhang, Xuecui Mei, Cost-effective and high ionic conductivity sulfide solid electrolyte Li7.3P2.9S10.75X0.3 (X = F, Cl, Br, and I) for all-solid-state lithium batteries, ACS Appl. Energy Mater, 2024, 54, 356-362.). Although the side reactions are inhibited to some extent, the long cycle problem still cannot be met, and the reason lies in the fact that the steady state cannot reach the desired level. Liu et al. regulated the electronic distribution in the LPSC system by introducing Mg and F elements, prepared an oxidation-reduction-resistant electrolyte Li6PS5Cl-MgF2 (LPSC-MF), and verified the oxidation-reduction-resistant mechanism of the electrolyte through density functional theory calculations (2. Chong Liu, Butian Chen, Tianran Zhang, Electron redistribution enables redox-resistible Li6PS5Cl towards high-performance all-solid-state lithium batteries, Angew. Chem. Int. Ed. 2023, 62, 202302655.). Research has found that the introduction of Mg changes the distribution state of the electron cloud inside the LPSC unit cell, making it change from "concentrated distribution" to "uniform distribution", thereby inhibiting the side reaction with lithium metal. In addition, CN119965269A discloses a technical solution for regulating the arrangement of the electron cloud inside the LPSC unit cell by doping with Si elements, which improves the steady state of the material to some extent, but its ionic conductivity decreases significantly, limiting its application in high-performance solid-state batteries.

[0004] Therefore, existing technologies mainly involve the introduction of halogens such as F, Cl, Br, and I, as well as the introduction of Si or some metals, to regulate the electron cloud distribution inside the LPSC unit cell. However, this type of method still has significant drawbacks in practical applications: on the one hand, halogens such as F, Cl, Br, and I have stronger electronegativity than metals and do not significantly improve the steady state; on the other hand, the introduction of Si and single metals will selectively embed, making it difficult to achieve global optimization of the electron cloud distribution, thus limiting the improvement effect on the material's stability.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for preparing sulfide electrolytes, so as to at least solve one of the technical problems existing in the prior art.

[0007] The second objective of this invention is to provide a sulfide electrolyte.

[0008] The third objective of this invention is to provide an application of a sulfide electrolyte in the preparation of solid-state batteries.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing a sulfide electrolyte, comprising the following steps: (a) A phosphorus source, a sulfur source, a halogen source and a first additive are mixed to obtain a first mixture, wherein the first additive includes a phosphorus-sulfur compound, which has an irregular molecular structure compared to the phosphorus source used as a raw material; (b) The first mixture is calcined once to obtain a calcined material; (c) The first sintering material is mixed with the second additive to obtain a second mixture, wherein the second additive comprises a metal oxide; (d) The second mixture is calcined a second time to obtain the sulfide electrolyte.

[0010] Furthermore, in step (a), the mass ratio of the phosphorus source, the sulfur source, and the halogen source is 1:3-7:1-3; Preferably, the amount of the first additive added is 5%-12% of the mass of the phosphorus source; Preferably, the phosphorus source comprises phosphorus pentasulfide; Preferably, the sulfur source includes one or more of lithium sulfide, nickel sulfide, manganese sulfide, and selenium sulfide; Preferably, the halogen source includes lithium chloride; Preferably, the first additive includes one or more of tetraphosphorus pentasulfide, tetraphosphorus trisulfide, and tetraphosphorus heptasulfide; Preferably, the mixing process in step (a) includes: mixing the phosphorus source, sulfur source, halogen source and first additive, and performing liquid-phase star ball milling; Preferably, the liquid phase comprises an organic liquid; Preferably, the organic liquid comprises one or more of isopropyl ether, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, propylene carbonate, dibutyl carbonate, dipropyl carbonate, butyl acetate, diphenyl carbonate, propyl propionate, ethyl propionate, isopropanol, ethyl acetate, and methylcyclotetrasiloxane.

[0011] Furthermore, in step (c), the mass ratio of the second additive to the sintered material is 1:5 to 1:15; Preferably, the second additive includes TiO2, ZnO, CoO, SnO2, CuO, V2O3, Al2O3, WO3, ZrO, NbO, Fe2O3, Cr2O3, CaO, MgO, SrO, BaO, and Cs. 11 One or more of O3, Rb2O, ScO, YO, Ta2O5, MoO2, MnO and Sb2O3; Preferably, the second additive includes TiO2, ZnO, CoO, SnO2, CuO, V2O3, Al2O3, WO3, ZrO, NbO, Fe2O3, Cr2O3, CaO, MgO, SrO, BaO, and Cs. 11 At least five of the following: O3, Rb2O, ScO, YO, Ta2O5, MoO2, MnO, and Sb2O3; Preferably, the molar ratio of each metal element in the second additive is 1; Preferably, the mixing process in step (c) includes: mixing the second additive and a calcined material, and then performing liquid-phase star ball milling; Preferably, the liquid phase comprises an organic liquid; Preferably, the organic liquid comprises one or more of isopropyl ether, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, propylene carbonate, dibutyl carbonate, dipropyl carbonate, butyl acetate, diphenyl carbonate, propyl propionate, ethyl propionate, isopropanol, ethyl acetate, and methylcyclotetrasiloxane.

[0012] Furthermore, the temperature of the first calcination is 400-500℃.

[0013] Furthermore, the temperature of the secondary calcination is 400-600℃.

[0014] Furthermore, after step (a) and before step (b), the process also includes: washing and filtration.

[0015] Preferably, after step (b) and before step (c), the process further includes: a grinding process; Preferably, the grinding process includes sequential liquid phase coarse grinding and liquid phase fine grinding; the liquid phase coarse grinding time is 1-2 h, and the median particle size of the sintered material after the liquid phase coarse grinding is 3.5-4.5 micrometers; the liquid phase fine grinding time is 2-3 h, and the median particle size of the sintered material after the liquid phase fine grinding is 1.5-2.5 micrometers.

[0016] Furthermore, after step (c) and before step (d), the process also includes: washing and filtration.

[0017] Furthermore, after the second calcination, a second-calcined material is obtained, which is then subjected to grinding. Preferably, the grinding process includes sequential liquid phase coarse grinding and liquid phase fine grinding; the liquid phase coarse grinding time is 1-2 h, and the median particle size of the sintered material after liquid phase coarse grinding is 3.5-4.5 micrometers; the liquid phase fine grinding time is 2-3 h, and the median particle size of the sintered material after liquid phase fine grinding is 1.5-2.5 micrometers.

[0018] Secondly, the present invention provides a sulfide electrolyte, which is prepared by the preparation method described above.

[0019] Thirdly, the present invention provides an application of the sulfide electrolyte described above in the preparation of solid-state batteries.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The method for preparing sulfide electrolytes provided by this invention introduces a phosphorus-sulfur compound with a more irregular molecular structure than the phosphorus source as a first additive. This compound is blended with the phosphorus source, sulfur source, and halogen source and then calcined once. During the first calcination process, this additive can induce local structural distortion in the early stage of crystal growth, forming amorphous regions or vacancy defects, effectively perturbing PS4. 3- The distribution of electron clouds around the functional groups transforms their concentrated arrangement into a dispersed one, thus initially reducing the interfacial reactivity of the material. Subsequently, by introducing a second additive containing metal oxides for secondary doping and secondary calcination, a uniform distribution of different metal elements in the crystal lattice is achieved under the high-entropy effect. The mutual restraint between multiple metals prevents the segregation of a single metal, further optimizing the uniformity of the electron cloud arrangement within the unit cell. This dual regulation mechanism significantly improves the chemical and electrochemical stability of the sulfide electrolyte without significantly sacrificing ionic conductivity, particularly effectively suppressing interfacial side reactions between it and the lithium metal anode, increasing the critical current density, and extending the cycle life of the all-solid-state battery. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 The electron cloud arrangement diagrams are shown before (left) and after (right) doping of Mg metal. Figure 2 This is a microscopic diagram illustrating the primary and secondary calcination mechanisms of the present invention; Figure 3 The XRD pattern is shown in Example 1. Figure 4 This is the XRD pattern of Example 9. Detailed Implementation

[0023] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The first aspect of this invention provides a method for preparing a sulfide electrolyte, comprising the following steps: (a) A phosphorus source, a sulfur source, a halogen source and a first additive are mixed to obtain a first mixture, wherein the first additive includes a phosphorus-sulfur compound, which has an irregular molecular structure compared to the phosphorus source used as a raw material; (b) The first mixture is calcined once to obtain a calcined material; (c) The first sintering material is mixed with the second additive to obtain a second mixture, wherein the second additive comprises a metal oxide; (d) The second mixture is calcined a second time to obtain the sulfide electrolyte.

[0026] This invention designs a method to achieve a "steady-state" distribution by adjusting the internal electron cloud arrangement of LPSC sulfide electrolytes, thereby effectively reducing side reactions at the lithium metal interface and laying the foundation for the industrial production of high-stability LPSC sulfide electrolytes. First, this invention modifies LPSC particles with a first additive (preferably tetraphosphorus pentasulfide) to regulate the internal electron cloud arrangement of the unit cell. Second, it further modifies the LPSC particles using a high-entropy process with multiple metal elements to regulate the electron cloud distribution again. These two modifications effectively improve the steady-state state of LPSC.

[0027] Specifically, such as Figures 1-2 As shown, the method for preparing sulfide electrolytes provided by this invention is a process for adjusting electron cloud arrangement to suppress lithium metal interface reactions. The process is characterized by a two-step method that significantly improves the steady state of LPSC while maintaining high ionic conductivity and suppressing interfacial side reactions between LPSC and lithium metal. Tetraphosphine trisulfide, tetraphosphine heptasulfide, or tetraphosphine pentasulfide replaces diphosphine pentasulfide, creating vacancies or holes and causing a rearrangement of the electron cloud. Then, high-entropy multi-element metals are used for secondary sintering or doping, causing metal M to replace PS4. 3- The phosphorus element in the group further causes electron cloud rearrangement in the LPSC unit cell structure. The two-step process can significantly improve the internal structure of the LPSC unit cell due to PS4. 3- The highly concentrated electron cloud of the functional groups is transformed into a diffuse or uniformly distributed electron cloud rearrangement, which greatly improves the steady state of LPSC and greatly suppresses the side reactions between LPSC and lithium metal.

[0028] To further explain, this invention, while ensuring a certain ionic conductivity, employs dual regulation of the electron cloud within the LPSC unit cell, thereby efficiently enhancing the steady-state of the LPSC sulfide electrolyte. This one-step regulation involves the introduction of tetraphosphorus pentasulfide to replace PS4. 3- The first step involves creating vacancies through group formation, followed by high-entropy regulation by multiple metal elements. This high-entropy characteristic creates a "restraint" between the various metal elements, thus avoiding metal segregation and resulting in a more uniform electron cloud distribution in the LPSC unit cell structure. This process maximizes the material's stability while maintaining a certain ionic conductivity, avoiding excessive side reactions with lithium metal.

[0029] In some preferred embodiments, in step (a), the mass ratio of the phosphorus source, the sulfur source and the halogen source is 1:3-7:1-3; Among them, "3-7" can be, for example, 3, 4, 5, 6, 7, etc.; "1-3" can be, for example, 1, 2, 3, etc.

[0030] Preferably, the amount of the first additive added is 5%-12% of the mass of the phosphorus source, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, etc. Preferably, the phosphorus source comprises phosphorus pentasulfide; Preferably, the sulfur source includes one or more of lithium sulfide, nickel sulfide, manganese sulfide, and selenium sulfide; Preferably, the halogen source includes lithium chloride; Preferably, the first additive includes one or more of tetraphosphorus pentasulfide, tetraphosphorus trisulfide, and tetraphosphorus heptasulfide; In this invention, phosphorus pentasulfide has a highly symmetrical and regular cage-like structure. Phosphorus pentasulfide, phosphorus trisulfide, and phosphorus heptasulfide, due to their different numbers of sulfur atoms, have their symmetry disrupted, resulting in distorted or missing molecular configurations, exhibiting distorted or missing cage-like or chain-like structures, thus exhibiting "irregularity." They belong to phosphorus-sulfur compounds with irregular molecular structures. This irregular molecular structure has the ability to introduce distortions, vacancies, or local amorphous states into the crystal lattice, providing a structural basis for subsequent "electron cloud rearrangement."

[0031] Preferably, the mixing process in step (a) includes: mixing the phosphorus source, sulfur source, halogen source and first additive, and performing liquid-phase star ball milling; Preferably, the liquid phase comprises an organic liquid; Preferably, the organic liquid comprises one or more of isopropyl ether, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, propylene carbonate, dibutyl carbonate, dipropyl carbonate, butyl acetate, diphenyl carbonate, propyl propionate, ethyl propionate, isopropanol, ethyl acetate, and methylcyclotetrasiloxane.

[0032] In some preferred embodiments, in step (c), the mass ratio of the second additive to the sintered material is 1:5 to 1:15, for example, it can be 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, etc.; more preferably, it is 1:5 to 1:12.

[0033] Preferably, the second additive includes TiO2, ZnO, CoO, SnO2, CuO, V2O3, Al2O3, WO3, ZrO, NbO, Fe2O3, Cr2O3, CaO, MgO, SrO, BaO, and Cs. 11 One or more of O3, Rb2O, ScO, YO, Ta2O5, MoO2, MnO and Sb2O3; Preferably, the second additive includes TiO2, ZnO, CoO, SnO2, CuO, V2O3, Al2O3, WO3, ZrO, NbO, Fe2O3, Cr2O3, CaO, MgO, SrO, BaO, and Cs. 11 At least five of the following: O3, Rb2O, ScO, YO, Ta2O5, MoO2, MnO, and Sb2O3; Preferably, the molar ratio of each metal element in the second additive is 1; Preferably, the mixing process in step (c) includes: mixing the second additive and a calcined material, and then performing liquid-phase star ball milling; Preferably, the liquid phase comprises an organic liquid; Preferably, the organic liquid comprises one or more of isopropyl ether, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, propylene carbonate, dibutyl carbonate, dipropyl carbonate, butyl acetate, diphenyl carbonate, propyl propionate, ethyl propionate, isopropanol, ethyl acetate, and methylcyclotetrasiloxane.

[0034] In some preferred embodiments, the temperature of the first calcination is 400-500°C, for example, 400°C, 450°C, 500°C, etc.

[0035] In some preferred embodiments, the temperature of the secondary calcination is 400-600℃, for example, 400℃, 450℃, 500℃, 550℃, 600℃, etc.

[0036] In some preferred embodiments, after step (a) and before step (b), a washing and filtration process is further included.

[0037] Preferably, after step (b) and before step (c), the process further includes: a grinding process; Preferably, the grinding process includes sequential liquid phase coarse grinding and liquid phase fine grinding; the liquid phase coarse grinding time is 1-2 hours, for example, 1 hour, 1.5 hours, 2 hours, etc., and the median particle size of the sintered material after the liquid phase coarse grinding is 3.5-4.5 micrometers, preferably 4 micrometers; the liquid phase fine grinding time is 2-3 hours, for example, 2 hours, 2.5 hours, 3 hours, etc., and the median particle size of the sintered material after the liquid phase fine grinding is 1.5-2.5 micrometers, preferably 2 micrometers.

[0038] In some preferred embodiments, after step (c) and before step (d), a washing and filtration process is further included.

[0039] In some preferred embodiments, the second calcination is performed to obtain the second calcined material, which is then subjected to grinding. Preferably, the grinding process includes sequential liquid phase coarse grinding and liquid phase fine grinding; the liquid phase coarse grinding time is 1-2 hours, for example, 1 hour, 1.5 hours, 2 hours, etc., and the median particle size of the sintered material after liquid phase coarse grinding is 3.5-4.5 micrometers, preferably 4 micrometers; the liquid phase fine grinding time is 2-3 hours, for example, 2 hours, 2.5 hours, 3 hours, etc., and the median particle size of the sintered material after liquid phase fine grinding is 1.5-2.5 micrometers, preferably 2 micrometers.

[0040] In a preferred embodiment of the present invention, the method for preparing the sulfide electrolyte includes the following steps: Step 1: The phosphorus source, sulfur source, halogen source and the first additive are subjected to liquid phase star ball milling, wherein the mass ratio of the phosphorus source, sulfur source and halogen source is 1:3-7:1-3, and the amount of the first additive added is 5%-12% of the mass of the phosphorus source. The first additive includes one or more of tetraphosphorus pentasulfide, tetraphosphorus trisulfide and tetraphosphorus heptasulfide.

[0041] Step 2: Wash and filter the sample after the treatment in Step 1.

[0042] Step 3: Calcine the sample treated in Step 2 under N2, with the calcination temperature set between 400-500℃.

[0043] Step 4: Perform liquid phase coarse grinding on the sample processed in step 3. Set the grinding time to 1-2 hours and stop when D50 reaches 4 micrometers.

[0044] Step 5: Perform liquid phase fine grinding on the sample processed in step 4, and set the grinding time to 2-3 hours until the D50 reaches 2 micrometers.

[0045] Step 6: The sample treated in Step 5 is subjected to liquid-phase star ball milling with the second additive. The mass ratio of the second additive to the first feedstock is 1:5-1:15. The second additive includes TiO2, ZnO, CoO, SnO2, CuO, V2O3, Al2O3, WO3, ZrO, NbO, Fe2O3, Cr2O3, CaO, MgO, SrO, BaO, and Cs. 11 One or more of O3, Rb2O, ScO, YO, Ta2O5, MoO2, MnO and Sb2O3, wherein the molar ratio of each metal element is 1.

[0046] Step 7: Repeat step 2.

[0047] Step 8: Calcine the sample treated in Step 7 under N2, with the calcination temperature set to 400-600℃.

[0048] Step 9: Repeat step 4.

[0049] Step 10: Repeat step 5 and dry the product to obtain the high-entropy calcined product.

[0050] A second aspect of the present invention provides a sulfide electrolyte, which is prepared by the above-described preparation method.

[0051] In this invention, the distribution of LPSC sulfide solid electrolyte in a solid-state battery involves three locations: its composite with the positive electrode, its composite with the negative electrode, and the electrolyte layer. Each location is associated with side reactions; therefore, a stable LPSC with high ionic conductivity is crucial for the industrial production of solid-state batteries. Currently, solid-state batteries are still effectively evaluated using mold batteries, and the negative electrode material is mostly Li metal or lithium-indium alloy. This invention uses a two-step process to regulate the electron cloud distribution within the LPSC cell, transforming the relatively "concentrated" "active" state of the LPSC electron cloud distribution into a uniformly distributed stable state, thereby suppressing the reaction between LPSC and lithium metal. The first step preferably uses tetraphosphorus pentasulfide to replace or partially replace diphosphorus pentasulfide, forming a localized amorphous state within the crystal lattice and reducing PS4. 3- The degree of concentration of the electron cloud of the group. The second step is to use multi-metal elements to achieve high entropy, utilizing the mutual attraction between different metals to prevent segregation and achieve uniform replacement of PS4. 3- The phosphorus element in the group effectively regulates the distribution of the electron cloud within the LPSC unit cell. This two-step process effectively suppresses side reactions between LPSC and lithium metal while ensuring high ionic conductivity, thereby guaranteeing long cycle life and reducing processing difficulty.

[0052] A third aspect of the present invention provides the application of a sulfide electrolyte in the preparation of a solid-state battery.

[0053] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0054] Example 1 This embodiment provides a sulfide electrolyte, the preparation process of which is as follows: Step 1: Phosphorus pentasulfide, lithium sulfide, lithium chloride and additive (phosphorus pentasulfide) are subjected to liquid-phase star ball milling, wherein the mass ratio of phosphorus pentasulfide, lithium sulfide and lithium chloride is 1:5:2, the amount of phosphorus pentasulfide added is 5% of the mass of phosphorus pentasulfide, and the liquid phase is tetrahydrofuran.

[0055] Step 2: Wash and filter the sample after the treatment in Step 1.

[0056] Step 3: Calcine the sample treated in Step 2 under N2 at a temperature of 400℃.

[0057] Step 4: Perform liquid phase coarse grinding on the sample processed in step 3. Set the grinding time to 1-2 hours and stop when D50 reaches 4 micrometers.

[0058] Step 5: Perform liquid phase fine grinding on the sample processed in step 4, and set the grinding time to 2-3 hours until the D50 reaches 2 micrometers.

[0059] Step 6: The sample after step 5 (i.e., the sintered material after step 5) and the additives are subjected to liquid-phase star ball milling. The additives include TiO2, ZnO, CoO, SnO2 and CuO. The total mass of the additives and the mass ratio of the sintered material is 1:5, and the molar ratio of each metal element is 1:1:1:1:1.

[0060] Step 7: Repeat step 2.

[0061] Step 8: Calcine the sample treated in Step 7 under N2 at a temperature of 400℃.

[0062] Step 9: Repeat step 4.

[0063] Step 10: Repeat step 5 and dry the product to obtain the high-entropy calcined product.

[0064] Example 2 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 1 in that: In step 1, the amount of tetraphosphine pentasulfide added is 7% of the mass of diphosphine pentasulfide; In step 3, the calcination temperature is set to 450℃; In step 6, the additives include V2O3, Al2O3, WO3, ZrO and NbO, and the total mass of the additives is in the mass ratio of one batch of sintered material to 1:8. In step 8, the calcination temperature is set to 450℃.

[0065] Example 3 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 1 in that: In step 1, the amount of tetraphosphine pentasulfide added is 9% of the mass of diphosphine pentasulfide; In step 3, the calcination temperature is set to 500℃; In step 6, the additives include Fe2O3, Cr2O3, CaO, MgO, and SrO, and the total mass of the additives is in the mass ratio of one batch of sintered material to 1:10. In step 8, the calcination temperature is set to 500℃.

[0066] Example 4 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 1 in that: In step 1, the amount of tetraphosphine pentasulfide added is 10% of the mass of diphosphine pentasulfide; In step 3, the calcination temperature is set to 450℃; In step 6, the additives include BaO and Cs. 11 The total mass of additives, including O3, Rb2O, ScO, and YO, is in a mass ratio of 1:12 to that of the first batch of sintered material. In step 8, the calcination temperature is set to 550℃.

[0067] Example 5 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 1 in that: In step 1, the amount of tetraphosphine pentasulfide added is 12% of the mass of diphosphine pentasulfide; In step 3, the calcination temperature is set to 500℃; In step 6, the additives include TiO2, ZnO, Cr2O3, MoO2, MnO and Sb2O3, with a molar ratio of 1:1:1:1:1:1:1 for each metal element; the total mass of the additives is in a mass ratio of 1:8 to that of the sintering material. In step 8, the calcination temperature is set to 550℃.

[0068] Example 6 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 1 in that: In step 3, the calcination temperature is set to 460℃; In step 6, the additives include SnO2, V2O3, Al2O3, CaO, MgO, ScO and Ta2O5, with a molar ratio of 1:1:1:1:1:1:1:1 for each metal element; the total mass of the additives is in a mass ratio of 1:6 to that of the sintering material. In step 8, the calcination temperature is set to 560℃.

[0069] Example 7 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 1 in that: In step 1, the amount of tetraphosphine pentasulfide added is 8% of the mass of diphosphine pentasulfide; In step 6, the total mass of the additives is in the mass ratio of one batch of raw material to 1:7. In step 8, the calcination temperature is set to 430℃.

[0070] Example 8 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 2 in that: In step 6, the additives include V2O3, Al2O3, ZnO, Cr2O3, and YO.

[0071] Example 9 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 3 in that: In step 6, the additives include Fe2O3, Cr2O3, CaO, MgO, SrO, ZrO and NbO, with a molar ratio of 1:1:1:1:1:1:1:1 for each metal element.

[0072] Example 10 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 6 in that: In step 6, the additives include SnO2, V2O3, Al2O3, CaO, MgO, ScO, ZrO, Ta2O5, YO and MoO2, with a molar ratio of 1:1:1:1:1:1:1:1:1:1:1.

[0073] Example 11 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 10 in that: In step 1, the mass ratio of phosphorus pentasulfide, lithium sulfide, and lithium chloride is 1:7:3; the amount of tetraphosphorus pentasulfide added is 4% of the mass of phosphorus pentasulfide. In step 6, the total mass of the additives is in a mass ratio of 1:4 to that of the raw material.

[0074] Example 12 This embodiment provides a sulfide electrolyte, the preparation process of which differs from that of Example 10 in that: In step 1, the mass ratio of phosphorus pentasulfide, lithium sulfide, and lithium chloride is 1:3:1; the amount of tetraphosphine pentasulfide added is 13% of the mass of phosphorus pentasulfide. In step 6, the total mass of the additives is in a mass ratio of 1:15 to that of the raw material.

[0075] Comparative Example 1 This comparative example provides a sulfide electrolyte, the preparation process of which differs from that of Example 1 in that: Only steps 1-5 are performed; subsequent secondary additive treatment and secondary calcination are not carried out.

[0076] Comparative Example 2 This comparative example provides a sulfide electrolyte, the preparation method of which is as follows: Phosphorus pentasulfide, lithium sulfide and lithium chloride are mixed in a mortar in a molar ratio of 1:5:2, then calcined in a nitrogen atmosphere furnace at 350-500℃, and then crushed to obtain a D50 of 1 micrometer.

[0077] Test case Test samples: The sulfide electrolytes prepared in Examples 1-12 and Comparative Examples 1-2 were used as samples for testing.

[0078] Test method: (1) Characterization of ionic conductivity: 0.2 g of pulverized material was placed in a battery mold for cold pressing, with the pressure maintained at 350 MPa during the cold pressing process. The ionic conductivity of the solid electrolyte was evaluated by testing the electrochemical impedance spectroscopy of the ion-blocking battery (stainless steel sheet / electrolyte sheet / stainless steel sheet). The formula for calculating ionic conductivity is as follows: Where σ represents the ionic conductivity of the sample, L is the thickness of the electrolyte sheet, S is the surface area of ​​the electrolyte sheet, and R is the resistance of the electrolyte sheet.

[0079] (2) Critical current density test of lithium metal symmetric battery (CCD): 120 mg of electrolyte was pressed at 400 MPa for 3 min. A 50 μm lithium foil with a diameter of 10 mm was used as an electron blocking electrode to assemble a stainless steel symmetric mold battery at 50 MPa intracavity pressure. The current density was 0.05 mA / cm². 2 The initial current density is 0.05 mA / cm². 2 The critical current density test was conducted on the current density increase.

[0080] The test results are shown in Table 1.

[0081] Table 1. Ionic conductivity, lithium-symmetric CCD and D50 of the Examples and Comparative Examples

[0082] As can be seen from the data in Table 1, based on the test data in Table 1, in terms of the critical current density (CCD) of lithium symmetric batteries, the sulfide electrolyte prepared in the embodiments of the present invention exhibits significantly better electrochemical stability and LPSC and the ability to suppress the side reactive electrode of lithium metal than the comparative example.

[0083] As can be seen from the above examples and comparative examples, different types, contents, and processes of additives all have different effects on ionic conductivity and critical current density. Examples 1 and 1 show that the introduction of the di-sintered coating layer has a significant gain effect on increasing the critical current and a significant protective effect against lithium metal reactions. Examples 1-4 use 5 different metal elements, while Examples 5 and 6 use 6 and 7 different metal elements respectively, Example 9 uses 7 elements, and Example 10 uses 10 elements. Overall, more metal elements tend to result in a higher critical current density. This is due to the balance between the metals under high entropy conditions, preventing significant segregation and further regulating the balance of electron cloud arrangement within the LPSC cell, thus suppressing lithium metal interface reactions. Examples 9 and 3 show that Example 9 adds two metal elements, ZrO and NbO, increasing its CCD value from 1.25 to 1.31 mA / cm². 2 As can be seen from Examples 6 and 10, Example 10 added four metallic elements: ZrO, Ta₂O₅, YO, and MoO₂, and its CCD value increased from 1.34 to 1.59 mA / cm². 2 As demonstrated in Examples 8 and 2, replacing three metal elements increased the CCD value from 0.70 to 0.76 mA / cm². 2 The above process comparison shows that the introduction of tetraphosphorus pentasulfide and the doping of different metal elements can effectively increase the CCD value and suppress lithium metal side reactions.

[0084] In addition, from Figure 3 The image shown is the XRD pattern of Example 1. Figure 4 The XRD pattern of Example 9 shows that all samples exhibit typical LPSC diffraction peaks, indicating that the preparation method of this invention can effectively form the target crystalline phase while maintaining the integrity of the main structure. No obvious impurity peaks were observed in the spectrum, suggesting that the first additive (e.g., tetraphosphorus pentasulfide) and the second additive (polymetallic oxide) did not introduce observable foreign phases after two calcinations. This indicates that the metal elements may enter the crystal lattice in the form of doping or solid solution, or be uniformly distributed at the grain boundaries in an extremely fine / amorphous state, thereby achieving the control of electron cloud distribution without disrupting the long-range ordered structure.

[0085] It is evident that the two-step electron cloud distribution regulation strategy of this invention can suppress lithium metal interface side reactions and improve electrolyte stability. Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of this invention and not intended to limit it. Although the invention 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; and these 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 invention.

Claims

1. A method for producing a sulfide electrolyte, characterized by, The method comprises the following steps: (a) mixing a phosphorus source, a sulfur source, a halogen source and a first additive to obtain a first mixture, wherein the first additive comprises a phosphorus-sulfur compound, and the phosphorus-sulfur compound has an irregular molecular structure compared with the phosphorus source as a raw material; (b) performing primary calcination on the first mixture to obtain a primary calcined material; (c) mixing the primary calcined material and a second additive to obtain a second mixture, wherein the second additive comprises a metal oxide; (d) performing secondary calcination on the second mixture to obtain the sulfide electrolyte.

2. The production method according to claim 1, characterized by, In step (a), the mass ratio of the phosphorus source, the sulfur source and the halogen source is 1:3-7:1-3; Preferably, the first additive is added in an amount of 5%-12% of the mass of the phosphorus source; Preferably, the phosphorus source comprises diphosphorus pentasulfide; Preferably, the sulfur source comprises one or more of lithium sulfide, nickel sulfide, manganese sulfide and selenium sulfide; Preferably, the halogen source comprises lithium chloride; Preferably, the first additive comprises one or more of tetraphosphorus tetrasulfide, tetraphosphorus trisulfide and tetraphosphorus heptasulfide; Preferably, the mixing process in step (a) comprises mixing the phosphorus source, the sulfur source, the halogen source and the first additive to perform liquid-phase star ball milling; Preferably, the liquid phase comprises an organic liquid; Preferably, the organic liquid comprises one or more of isopropyl ether, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, propylene carbonate, dibutyl carbonate, dipropyl carbonate, butyl acetate, diphenyl carbonate, propyl propionate, ethyl propionate, isopropyl alcohol, ethyl acetate and methylcyclosiloxane.

3. The preparation method according to claim 1, characterized in that, In step (c), the mass ratio of the second additive to the primary calcined material is 1:5-1:15; Preferably, the second additive comprises one or more of TiO2, ZnO, CoO, SnO2, CuO, V2O3, AI2O3, WO3, ZrO, NbO, Fe2O3, Cr2O3, CaO, MgO, SrO, BaO, Cs 11 O3, Rb2O, ScO, YO, Ta2O5, M0O2, MnO, and Sb2O3. Preferably, the second additive comprises at least five of Ti02, ZnO, CoO, Sn02, CuO, V203, AI203, W03, ZrO, NbO, Fe203, Cr203, CaO, MgO, SrO, BaO, Cs 11 O3, Rb20, ScO, YO, Ta205, M0O2, MnO, and Sb203; Preferably, the molar ratio of each metal element in the second additive is 1; Preferably, the mixing process in step (c) comprises mixing the second additive and the primary calcined material to perform liquid-phase star ball milling; Preferably, the liquid phase comprises an organic liquid; Preferably, the organic liquid comprises one or more of isopropyl ether, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, propylene carbonate, dibutyl carbonate, dipropyl carbonate, butyl acetate, diphenyl carbonate, propyl propionate, ethyl propionate, isopropyl alcohol, ethyl acetate and methylcyclosiloxane.

4. The method of claim 1, wherein, The temperature of the primary calcination is 400-500℃.

5. The preparation method according to claim 1, characterized in that, The temperature of the secondary calcination is 400-600℃.

6. The method of claim 1, wherein, After step (a) and before step (b), the method further comprises a washing and filtering process; Preferably, after step (b) and before step (c), the method further comprises a grinding process; Preferably, the grinding process comprises sequentially performing liquid-phase coarse grinding and liquid-phase fine grinding; the liquid-phase coarse grinding is performed for 1-2 h, and the primary calcined material after the liquid-phase coarse grinding has a median particle size of 3.5-4.5 microns; the liquid-phase fine grinding is performed for 2-3 h, and the primary calcined material after the liquid-phase fine grinding has a median particle size of 1.5-2.5 microns.

7. The preparation method according to claim 1, characterized in that, After step (c) and before step (d), the method further comprises a washing and filtering process.

8. The method of claim 1, wherein, After the secondary calcination, a secondary calcined material is obtained, and then a grinding process is performed; Preferably, the grinding process comprises liquid-phase coarse grinding and liquid-phase fine grinding performed in sequence; the liquid-phase coarse grinding is performed for 1-2 h, and the median particle size of the secondly burned material after the liquid-phase coarse grinding is 3.5-4.5 microns; the liquid-phase fine grinding is performed for 2-3 h, and the median particle size of the secondly burned material after the liquid-phase fine grinding is 1.5-2.5 microns.

9. A sulfide electrolyte, characterized by Prepared by the preparation method according to any one of claims 1-8.

10. Use of the sulfide electrolyte according to claim 9 for the production of a solid-state battery.

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