Modified lithium sulfide and sulfide solid electrolyte, preparation method thereof and battery

Abstract

The invention provides a modified lithium sulfide solid electrolyte, a sulfide solid electrolyte, a preparation method thereof and a battery, and relates to the technical field of solid electrolyte materials. The preparation method of the sulfide solid electrolyte is different from a traditional doping technology, the high-stability sulfide solid electrolyte is prepared mainly through modification of lithium sulfide, the comprehensive performance of the sulfide solid electrolyte is improved, the ionic conductivity and chemical stability of the sulfide solid electrolyte are improved, and the service life of the sulfide solid electrolyte is prolonged. And the mechanical strength and the crack resistance are also obviously enhanced. The preparation method disclosed by the invention is simple, does not need to be carried out at high temperature, and does not need to use expensive raw materials and complex processes, so that the production cost is reduced, the application range of the sulfide solid electrolyte is expanded, and large-scale production and application of the sulfide solid electrolyte are favorably realized.

Description

Technical Field

[0001] This application relates to the technical field of solid electrolyte materials, and particularly to a modified lithium sulfide, a sulfide solid electrolyte, a preparation method thereof, and a battery. Background Art

[0002] Sulfide solid electrolytes are considered important candidate materials for achieving high-energy-density all-solid-state lithium batteries due to their high ionic conductivity (~10 -3 S / cm), low interfacial resistance, and characteristics suitable for lithium metal battery applications. However, sulfide solid electrolytes also have a series of technical bottlenecks, such as strong air sensitivity, resulting in a relatively rapid decline in ionic conductivity, insufficient mechanical strength, and poor interfacial stability with electrodes, which severely restricts the feasibility of their practical applications. Summary of the Invention

[0003] The purpose of this application is to provide a modified lithium sulfide, a sulfide solid electrolyte, a preparation method thereof, and a battery, aiming to solve the problems of strong air sensitivity, relatively rapid decline in ionic conductivity, insufficient mechanical strength, and poor interfacial stability with electrodes of existing sulfide solid electrolytes.

[0004] To achieve the above purpose, this application provides a modified lithium sulfide, including: lithium sulfide and doping elements, and the doping elements include oxygen, antimony, and nitrogen;

[0005] Optionally, the molar ratio of oxygen to lithium sulfide is 0.05 - 0.15:1, the molar ratio of antimony to lithium sulfide is 0.05 - 0.15:1, and the molar ratio of nitrogen to lithium sulfide is 0.05 - 0.15:1.

[0006] This application also provides a preparation method of a sulfide solid electrolyte, including:

[0007] Mixing the above-mentioned modified lithium sulfide with phosphorus pentasulfide and lithium chloride for a first heat treatment to obtain a sulfide solid electrolyte.

[0008] In some embodiments, the molar ratio of the modified lithium sulfide, the phosphorus pentasulfide, and the lithium chloride is 5 - 3.8:1:2 - 3.2;

[0009] Optionally, the temperature of the first heat treatment is 400 - 600 °C, and the time is 4 - 12 h.

[0010] In some embodiments, the preparation method of the modified lithium sulfide includes: mixing lithium sulfide or a raw material of lithium sulfide with a dopant for a second heat treatment to obtain a modified lithium sulfide; the dopant includes an oxygen source, an antimony source, and a nitrogen source;

[0011] In some embodiments, the oxygen source is selected from oxygen-containing oxides such as Li2O or Sb2O3;

[0012] Optionally, the antimony source is selected from Sb2O3 or SbCl3;

[0013] Optionally, the nitrogen source is selected from NH3 or urea.

[0014] In some embodiments, the molar ratio of lithium sulfide to the doping element in the dopant is 1:0.15 - 0.45;

[0015] Optionally, the molar ratio of lithium sulfide to the oxygen element in the oxygen source is 1:0.05 - 0.15;

[0016] Optionally, the molar ratio of lithium sulfide to the antimony element in the antimony source is 1:0.05 - 0.15;

[0017] Optionally, the molar ratio of lithium sulfide to the nitrogen element in the nitrogen source is 1:0.05 - 0.15.

[0018] In some embodiments, the temperature of the second heat treatment is 700°C - 800°C, the time is 8 hours - 12 hours, and the pressure is 0.5 MPa - 1 MPa.

[0019] In some embodiments, the raw materials of lithium sulfide include: lithium sulfate and a carbon source;

[0020] Optionally, the molar ratio of lithium sulfate to the carbon source is 1:(1.2 - 1.5).

[0021] This application also provides a sulfide solid electrolyte prepared by the above - mentioned preparation method of the sulfide solid electrolyte.

[0022] This application also provides a battery including the above - mentioned sulfide solid electrolyte.

[0023] Compared with the prior art, the beneficial effects of this application include:

[0024] The preparation method of the sulfide solid electrolyte provided by this application is different from traditional doping techniques. It mainly prepares a highly stable sulfide solid electrolyte through the modification of lithium sulfide, improving the comprehensive performance of the sulfide solid electrolyte. It not only improves its ionic conductivity and chemical stability, but also significantly enhances its mechanical strength and crack resistance. Doping nitrogen (N), oxygen (O), and antimony (Sb) into lithium sulfide (LiS) can effectively improve the stability and ionic conductivity of the sulfide solid electrolyte. Its core mechanisms include: 1. Regulating the crystal structure to improve the connectivity of lithium-ion migration channels; 2. Introducing point defects to increase the concentration of lithium vacancies and improve the lithium-ion mobility; 3. Optimizing the local electronic structure to reduce the migration barrier of lithium ions; 4. Enhancing the air stability of the material to improve its practicality. The preparation method of this application is simple, does not require high temperatures, nor expensive raw materials and complex processes. This not only reduces production costs, but also expands its application scope, facilitating the large-scale production and application of sulfide solid electrolytes.

[0025] The sulfide solid electrolyte provided by this application uses multiple dopants in a synergistic manner, significantly improving the air stability and interfacial properties of the material while maintaining high ionic conductivity; improving the crack resistance of the material through a heat treatment process, solving the problem of excessive brittleness in the prior art; and preparing a high-performance and stable sulfide solid electrolyte through a lithium sulfide modification method. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as limiting the scope of this application.

[0027] Figure 1 SEM image of the modified lithium sulfide for Example 1;

[0028] Figure 2 SEM image of the sulfide solid electrolyte for Example 1;

[0029] Figure 3 Ionic conductivity of the sulfide solid electrolyte for Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] As used herein, the terms:

[0031] "Prepared by..." is synonymous with "comprising". As used herein, the terms "comprising", "including", "having", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or apparatus comprising the listed elements need not be limited to those elements alone, but may include other elements not expressly listed or elements inherent to such composition, step, method, article or apparatus.

[0032] The conjunctive "consisting of" excludes any unrecited element, step or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause within the body of a claim rather than immediately following the subject, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0033] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this should be understood to specifically disclose all ranges formed by any combination of any upper range limit or preferred value with any lower range limit or preferred value, whether or not the ranges are separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0034] In these examples, unless otherwise specified, the parts and percentages are by mass.

[0035] "Part by mass" refers to the basic measurement unit representing the mass ratio relationship of multiple components. 1 part can represent any unit mass, such as 1 g or 2.689 g, etc. If we say that the mass part of component A is a parts and the mass part of component B is b parts, it means the mass ratio of component A to component B is a:b. Or, it means the mass of component A is aK and the mass of component B is bK (K is any number representing a multiple factor). It should not be misunderstood that, different from the number of mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0036] "And / or" is used to indicate that either or both of the stated circumstances may occur. For example, A and / or B includes (A and B) and (A or B).

[0037] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0038] The present application provides a modified lithium sulfide, comprising: lithium sulfide and doping elements, and the doping elements include oxygen, antimony, and nitrogen.

[0039] Due to the limitations of the crystal structure defects and ionic conductivity of pure lithium sulfide, it is difficult to directly meet the high-performance requirements of solid electrolytes. In the present application, oxygen, antimony, and nitrogen elements are co-doped in lithium sulfide, and the multiple dopants act synergistically to significantly improve the air stability and interfacial properties of the material while maintaining high ionic conductivity.

[0040] Optionally, the molar ratio of oxygen to lithium sulfide is 0.05 - 0.15:1, for example, it can be 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1 or any ratio between 0.05 - 0.15:1; the molar ratio of antimony to lithium sulfide is 0.05 - 0.15:1, for example, it can be 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1 or any ratio between 0.05 - 0.15:1; the molar ratio of nitrogen to lithium sulfide is 0.05 - 0.15:1, for example, it can be 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.11:1, 0.12:1, 0.13:1, 0.14:1, 0.15:1 or any ratio between 0.05 - 0.15:1.

[0041] The present application provides a method for preparing a sulfide solid electrolyte, comprising:

[0042] Mixing the above-mentioned modified lithium sulfide with phosphorus pentasulfide and lithium chloride and performing a first heat treatment to obtain a sulfide solid electrolyte.

[0043] The preparation method of the sulfide solid electrolyte provided by this application is different from traditional doping techniques. It mainly prepares a highly stable sulfide solid electrolyte through the modification of lithium sulfide, improving the comprehensive performance of the sulfide solid electrolyte. It not only improves its ionic conductivity and chemical stability but also significantly enhances its mechanical strength and crack resistance. Doping lithium sulfide (Li2S) with nitrogen (N), oxygen (O), and antimony (Sb) can effectively improve the stability and ionic conductivity of the sulfide solid electrolyte. Its core mechanisms include: 1. Regulating the crystal structure to improve the connectivity of lithium-ion migration channels; 2. Introducing point defects to increase the concentration of lithium vacancies and improve the lithium-ion mobility; 3. Optimizing the local electronic structure to reduce the migration barrier of lithium ions; 4. Enhancing the air stability of the material to improve its practicality. The preparation method of this application is simple, does not require high temperatures, nor expensive raw materials and complex processes. This not only reduces the production cost but also expands its application scope, facilitating the large-scale production and application of sulfide solid electrolytes.

[0044] In some embodiments, the molar ratio of the modified lithium sulfide, phosphorus pentasulfide, and lithium chloride is 5 - 3.8:1:2 - 3.2. For example, it can be 5:1:2, 4:1:2, 4:1:2.5, 4.5:1:2.8, 5:1:3.2, 4.8:1:3, or any ratio between 5 - 3.8:1:2 - 3.2.

[0045] In some embodiments, the temperature of the first heat treatment is 400 - 600 °C. For example, it can be 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, or any value between 400 - 600 °C, and the time is 4 - 12 h. For example, it can be 4 h, 6 h, 8 h, 10 h, 12 h, or any value between 4 - 12 h.

[0046] In some embodiments, the preparation method of the modified lithium sulfide includes: mixing lithium sulfide or the raw material of lithium sulfide with a dopant and performing a second heat treatment to obtain the modified lithium sulfide; the dopant includes an oxygen source, an antimony source, and a nitrogen source.

[0047] By introducing three doping elements, oxygen, antimony, and nitrogen, into lithium sulfide, the synergistic effect of multiple dopants is achieved. While maintaining high ionic conductivity, the air stability and interfacial properties of the material are significantly improved. Oxygen doping can provide more lithium-ion migration channels and improve ionic conductivity; antimony doping can inhibit the generation of defects in the crystal structure and improve material stability; nitrogen doping can improve the interfacial properties of the material by changing the local electron cloud density of the crystal.

[0048] In some embodiments, the oxygen source is selected from oxygen-containing oxides such as Li2O or Sb2O3.

[0049] In some embodiments, the antimony source is selected from Sb2O3 or SbCl3; when the oxygen source is Sb2O3, the oxygen source and the antimony source can be the same, both being Sb2O3.

[0050] In some embodiments, the nitrogen source is selected from NH3 or urea.

[0051] In some embodiments, the molar ratio of lithium sulfide to the doping element in the dopant is 1:0.15 - 0.45;

[0052] Optionally, the molar ratio of lithium sulfide to the oxygen element in the oxygen source is 1:0.05 - 0.15;

[0053] Optionally, the molar ratio of lithium sulfide to the antimony element in the antimony source is 1:0.05 - 0.15;

[0054] Optionally, the molar ratio of lithium sulfide to the nitrogen element in the nitrogen source is 1:0.05 - 0.15.

[0055] In some embodiments, the temperature of the second heat treatment is 700°C - 800°C, for example, it can be 700°C, 750°C, 800°C or any value between 700°C and 800°C, the time is 8 hours - 12 hours, for example, it can be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours or any value between 8 hours and 12 hours, and the pressure is 0.5 MPa - 1 MPa, for example, it can be 0.5 MPa, 0.7 MPa, 0.8 MPa, 1 MPa or any value between 0.5 MPa and 1 MPa.

[0056] In some embodiments, the raw materials of lithium sulfide include: lithium sulfate and a carbon source.

[0057] In some embodiments, the molar ratio of lithium sulfate to the carbon source is 1:(1.2 - 1.5), for example, it can be 1:1.2, 1:1.3, 1:1.4, 1:1.5 or any ratio between 1:(1.2 - 1.5).

[0058] This application also provides a sulfide solid electrolyte prepared by the preparation method of the above sulfide solid electrolyte.

[0059] The sulfide solid electrolyte provided by this application uses multiple dopants in a synergistic manner, while maintaining high ionic conductivity, significantly improving the air stability and interfacial properties of the material; improving the crack resistance strength of the material through the heat treatment process, solving the problem of excessive brittleness in the prior art; through the lithium sulfide modification method, a high-performance and stable sulfide solid electrolyte is prepared.

[0060] This application also provides a battery including the above sulfide solid electrolyte.

[0061] The implementation scheme of the present application will be described in detail below in combination with specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments, the operations are carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not specified by the manufacturer can all be obtained as conventional products through commercial purchase.

[0062] SEM test equipment: Zeiss Gemini 500, with an acceleration voltage of 10 kV.

[0063] Example 1

[0064] Example 1 provides a sulfide solid electrolyte, and its preparation method includes the following steps:

[0065] Step 1: Mix 10.9 g of lithium sulfate (Li2SO4, purity ≥ 99.5%, manufacturer: Sigma-Aldrich) with 5.0 g of carbon source (acetylene black, purity ≥ 99%, manufacturer: Alfa Aesar). Subsequently, add 0.03 g of oxide (Li2O, purity ≥ 99%, manufacturer: Alfa Aesar) or 2.27 g of SbCl3 (purity ≥ 99.5%, manufacturer: Sigma-Aldrich) or nitrogen source urea (CO(NH2)2, purity ≥ 99%, manufacturer: Alfa Aesar) and mix them using a planetary ball mill (manufacturer: Fritsch Pulverisette 7). The ball-to-material ratio is 10:1, the rotation speed is 300 rpm, and the ball milling time is 1 hour to obtain a mixture.

[0066] Place the mixture in a high-temperature furnace (manufacturer: Carbolite Gero), under nitrogen protection (purity 99.999%), carry out a reduction reaction at 800 °C for 12 hours, and the reaction pressure is 1 MPa to obtain reaction-doped lithium sulfide and carbon. Then, it is purified by ethanol and dried to obtain pure doped product modified lithium sulfide, including Li2S-O, Li2S-Sb, and Li2S-N. Characterization by scanning electron microscope (SEM) (as Figure 1 shown) shows that the particles are uniform, the average particle size is 3 μm, and the shape is an irregular polyhedron.

[0067] Step 2: The molar ratio of 6.12 g (0.1 mol) of the product from Step 1, namely Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N (doped with 0.01 mol), 4.44 g (0.02 mol) of P2S5, and 1.7 g (0.04 mol) of LiCl is 5:1:2. After uniform mixing, an appropriate amount of ball-milling medium is added, and under the rotation speed of 450 rpm / min, effective ball-milling is carried out for 15 hours. Then, under the condition of 500 °C, heat preservation is carried out for 5 h to obtain the sulfide solid electrolyte of Example 1, including LPSCl-O, LPSCl-Sb, or LPSCl-N. The scanning electron microscope (SEM) pictures are as Figure 2 shown.

[0068] Example 2

[0069] Adopt the scheme of Example 1, and change 0.1 mol of Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N to 0.1 mol of Li2S-0.05O, Li2S-0.05Sb, and Li2S-0.05N (doped with 0.005 mol).

[0070] Example 3

[0071] Adopt the scheme of Example 1, and change 0.1 mol of Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N to 0.1 mol of Li2S-0.15O, Li2S-0.15Sb, and Li2S-0.15N (doped with 0.015 mol).

[0072] Example 4

[0073] Adopt the scheme of Example 1, and change the calcination temperature in Step 2 from 500 °C to 400 °C.

[0074] Example 5

[0075] Adopt the scheme of Example 1, and change the calcination temperature in Step 2 from 500 °C to 600 °C.

[0076] Experimental Example 6

[0077] Adopt the scheme of Example 1, and change 0.02 mol of P2S5 and 0.04 mol of LiCl to 0.025 mol of P2S5 and 0.075 mol of LiCl. The molar ratio of modified Li2S:P2S5:LiCl is 4:1:3.

[0078] Experimental Example 7

[0079] Adopt the solution of Example 1, and change 0.02 mol of P2S5 and 0.04 mol of LiCl to 0.026 mol of P2S5 and 0.083 mol of LiCl. The molar ratio of the modified Li2S:P2S5:LiCl is 3.8:1:3.2.

[0080] Comparative Example 1

[0081] Adopt the solution of Example 1, and change 0.1 mol of Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N to 0.1 mol of Li2S-0.1O, that is, the modified lithium sulfide is only doped with oxygen element.

[0082] Comparative Example 2

[0083] Adopt the solution of Example 1, and change 0.1 mol of Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N to 0.1 mol of Li2S-0.1Sb, that is, the modified lithium sulfide is only doped with Sb element.

[0084] Comparative Example 3

[0085] Adopt the solution of Example 1, and change 0.1 mol of Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N to 0.1 mol of Li2S-0.1N, that is, the modified lithium sulfide is only doped with N element.

[0086] Comparative Example 4

[0087] Adopt the solution of Example 1, and change 0.1 mol of Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N to 0.1 mol of Li2S-0.1O and Li2S-0.1Sb, that is, the modified lithium sulfide is only doped with O element and Sb element.

[0088] Comparative Example 5

[0089] Adopt the solution of Example 1, and change 0.1 mol of Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N to 0.1 mol of Li2S-0.1O and Li2S-0.1N, that is, the modified lithium sulfide is only doped with O element and N element.

[0090] Comparative Example 6

[0091] Adopt the solution of Example 1, and change 0.1 mol of Li2S-0.1O, Li2S-0.1Sb, and Li2S-0.1N to 0.1 mol of Li2S-0.1N and Li2S-0.1Sb, that is, the modified lithium sulfide is only doped with Sb element and N element.

[0092] Comparative Example 7

[0093] Adopt the solution of Example 1, and change 0.02 mol of P2S5 and 0.04 mol of LiCl to 0.019 mol of P2S5 and 0.034 mol of LiCl. The modified molar ratio of Li2S:P2S5:LiCl is 5.2:1:1.8.

[0094] Comparative Example 8

[0095] Adopt the solution of Example 1, and change 0.02 mol of P2S5 and 0.04 mol of LiCl to 0.028 mol of P2S5 and 0.095 mol of LiCl. The modified molar ratio of Li2S:P2S5:LiCl is 3.6:1:3.4.

[0096] Comparative Example 9

[0097] Comparative Example 9 provides a sulfide solid electrolyte, and its preparation method includes the following steps:

[0098] Mix 0.1 mol of Li2S, 0.01 mol of Li2O, 0.01 mol of SbCl3, 0.005 mol of Co(NH2)2, 0.02 mol of P2S5 and 0.04 mol of LiCl uniformly, add an appropriate amount of ball-milling medium, and ball-mill effectively at a rotation speed of 450 rpm / min for 15 hours, and then keep the temperature at 500 °C for 5 h to obtain the doped O, Sb, N sulfide solid electrolyte of Comparative Example 9.

[0099] The preparation parameter data of the sulfide solid electrolytes of each example and comparative example are shown in Table 1.

[0100] Table 1 Parameter data of the sulfide solid electrolytes of each example and comparative example

[0101]

[0102]

[0103] The sulfide solid electrolytes obtained in each example and comparative example are respectively subjected to ion conductivity tests. The test results of Example 1 are as Figure 3 shown, and the test results of each example and comparative example are shown in Table 2. The ion conductivity test method is as follows:

[0104] 1. Sample preparation

[0105] (1) Powder sample treatment: Use a mold (Zhongke Wanyuan, model: JYGS1-10, inner diameter 10 mm), press at 300-500 MPa for 1 minute to obtain a self-supporting sheet and form a tight disc.

[0106] (2) Electrode Preparation: Coat gold (Au), platinum (Pt), carbon (C), or stainless steel (SS) on both sides of the sample as electrodes to ensure good electrical contact.

[0107] 2. AC Impedance Spectroscopy (EIS) Test

[0108] (1) Test Equipment: Use an impedance analyzer (such as BioLogic, Solartron, etc.). Connect the fixture (such as two-electrode or three-electrode configuration) to ensure good contact between the sample and the equipment. Perform sealing treatment (such as glove box operation or encapsulating the sample) to avoid the reaction of sulfides with moisture in the air.

[0109] (2) Test Parameters: Frequency Range: 1 MHz - 0.01 Hz or 10 MHz - 0.01 Hz (the specific range is adjusted according to the sample situation). AC Amplitude: 10 mV or 50 mV (usually choose a small amplitude that does not affect ion migration). Test Temperature: Room temperature (25 °C).

[0110] Table 2 Electrochemical Performance Results of the Batteries in Each Example and Comparative Example

[0111]

[0112]

[0113] As can be seen from Table 2, the ion conductivity retention rate of the sulfide solid electrolyte of the proposed solution in this application is higher than that of the sulfide solid electrolyte in the comparative example, indicating that the sulfide solid electrolyte of the proposed solution in this application has good air stability and a slower decline in ion conductivity. This is because oxygen and nitrogen doping from lithium sulfide raw materials can form stable Li-O and P-N covalent bonds, reducing sensitivity to water and oxygen; Sb doping can enhance lattice distortion and the structural rigidity of the material, improve interface stability, enhance the anti-decomposition ability of the material, and inhibit the generation of by-products such as HS and LiOH. Compared with the doping methods of sulfide solid electrolytes in the prior art, the doping elements of the doping method of the sulfide solid electrolyte in this application are more uniform, which can reduce the problem of uneven local concentration of the material; the doping method of the sulfide solid electrolyte in this application can form a stable lattice, inhibit the generation of impurity phases; and can also reduce stress concentration and enhance mechanical stability.

[0114] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application.

[0115] In addition, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments rather than other features, the combination of features of different embodiments is meant to be within the scope of this application and forms different embodiments. For example, in the claims above, any one of the claimed embodiments can be used in any combination. The information disclosed in this background section is only for enhancing the understanding of the overall background of this application and should not be regarded as an admission or any form of implication that this information constitutes prior art already known to those skilled in the art.

Claims

1. A modified lithium sulfide, characterized in that: include: Lithium sulfide and doping elements, wherein the doping elements include oxygen, antimony and nitrogen; Optionally, the molar ratio of the oxygen to the lithium sulfide is 0.05-0.15:1, the molar ratio of the antimony to the lithium sulfide is 0.05-0.15:1, and the molar ratio of the nitrogen to the lithium sulfide is 0.05-0.15:

1.

2. A method for preparing a sulfide solid electrolyte, characterized in that: include: The modified lithium sulfide according to claim 1 is mixed with phosphorus pentasulfide and lithium chloride and subjected to a first heat treatment to obtain a sulfide solid electrolyte.

3. The method for preparing a sulfide solid electrolyte according to claim 2, characterized in that: The molar ratio of the modified lithium sulfide, the phosphorus pentasulfide and the lithium chloride is 5-3.8:1:2-3.2; Optionally, the temperature of the first heat treatment is 400-600° C., and the time is 4-12 hours.

4. The method for preparing a sulfide solid electrolyte according to claim 2, characterized in that: The preparation method of the modified lithium sulfide comprises: mixing lithium sulfide or raw materials of lithium sulfide with a dopant and performing a second heat treatment to obtain the modified lithium sulfide; the dopant comprises an oxygen source, an antimony source and a nitrogen source.

5. The method for preparing a sulfide solid electrolyte according to claim 4, characterized in that: The oxygen source is selected from Li2O or Sb2O3 oxygen-containing oxides; Optionally, the antimony source is selected from Sb2O3 or SbCl3; Optionally, the nitrogen source is selected from NH3 or urea.

6. The method for preparing a sulfide solid electrolyte according to claim 4, characterized in that: The molar ratio of the lithium sulfide to the doping element in the dopant is 1:0.15-0.45; Optionally, the molar ratio of the lithium sulfide to the oxygen element in the oxygen source is 1:0.05-0.15; Optionally, the molar ratio of the lithium sulfide to the antimony element in the antimony source is 1:0.05-0.15; Optionally, the molar ratio of the lithium sulfide to the nitrogen element in the nitrogen source is 1:0.05-0.

15.

7. The method for preparing a sulfide solid electrolyte according to claim 4, characterized in that: The temperature of the second heat treatment is 700° C.-800° C., the time is 8 hours-12 hours, and the pressure is 0.5 MPa-1 MPa.

8. The method for preparing a sulfide solid electrolyte according to claim 4, characterized in that: The raw materials of the lithium sulfide include: lithium sulfate and a carbon source; Optionally, the molar ratio of the lithium sulfate to the carbon source is 1:(1.2-1.5).

9. A sulfide solid electrolyte, characterized in that: The sulfide solid electrolyte is prepared by the preparation method of any one of claims 2 to 8.

10. A battery, characterized in that: Comprising the sulfide solid electrolyte as claimed in claim 9.

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