Sulfide solid electrolyte and preparation method thereof, and all-solid-state lithium ion battery

Abstract

The application provides a sulfide solid electrolyte and a preparation method thereof, and a full-solid-state lithium ion battery. The preparation method replaces a traditional ball milling form, adopts a high-efficiency and large-batch high-speed stirring method to prepare a precursor, and is suitable for a wide range of sulfide material systems. The sulfide solid electrolyte material can retain the valence state of S to the greatest extent, avoids the change of the valence of S elements due to improper energy in the preparation by the ball milling method, reduces the generation of impurity phases after sintering, improves the crystallinity of the sulfide solid electrolyte, obtains a pure phase as much as possible, and further improves the ion conductivity and stability of the sulfide solid electrolyte at room temperature. Further, the first-cycle coulomb efficiency, cycle stability, cycle life and stable cycling capacity at high voltage of the full-solid-state lithium battery can be further improved. Meanwhile, the efficient preparation time and large-batch processing greatly reduce the time cost and improve the commercialization process of the sulfide solid electrolyte material.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion solid electrolyte battery technology, and particularly to a sulfide solid electrolyte and its preparation method, and an all-solid-state lithium-ion battery. Background Technology

[0002] Lithium-ion batteries are widely used in mobile phones, computers, automobiles, and energy storage due to their high energy density, long lifespan, and environmental friendliness. While traditional lithium-ion batteries have already revolutionized the energy industry, the increasing demand for energy storage places higher requirements on the safety, energy density, and lifespan of lithium-ion batteries. Therefore, all-solid-state batteries, which use solid-state electrolytes instead of flammable liquid electrolytes, are the ideal choice for the next generation of lithium-ion batteries. This is not only because solid-state electrolytes offer higher safety, but also because they can be matched with high-voltage cathode materials (such as Li(NiCoMn)O2) and high-capacity electrodes (such as lithium metal anodes) to achieve high-energy-density batteries.

[0003] Currently, there are many types of solid-state electrolytes. Among them, sulfide electrolytes have been extensively studied due to their conductivity and electrochemical stability comparable to traditional electrolytes. They represent the fastest-growing segment of commercially viable solid-state batteries and are considered a new breakthrough in the development of all-solid-state lithium-ion batteries. Electrolyte materials, as one of the core materials of lithium-ion batteries, significantly impact the electrochemical performance of the battery due to their conductivity and stability. Traditionally, sulfide materials are prepared by ball milling in a zirconium oxide jar. However, agglomeration during ball milling easily reduces milling efficiency. Therefore, how to efficiently prepare electrolyte materials with high ionic conductivity is a key process that needs to be solved in the commercialization of sulfide-based lithium-ion batteries. Simultaneously, reducing production costs is also a practical issue given the need for large-scale production.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a sulfide solid electrolyte and its preparation method, as well as an all-solid-state lithium-ion battery, in order to solve the problems of poor stability, low conductivity and high cost of preparation materials of existing sulfide electrolytes.

[0006] The technical solution of the present invention is as follows:

[0007] A sulfide solid electrolyte, wherein the sulfide solid electrolyte comprises Li 7-N PS 6-N X N Li 7-M- A PS 6-M-ACl A I M Li 7-A-V PS 6-A-V Cl A Br V Li 7-M-V PS 6-M-V Br V I M Li 7-N+B P 1-B Y B S 6-N X N Li 7-N P 1-C Z C S 6-N X N Li 7-A-V+B P 1-B Y B S 6-A-V Cl A Br V Li 7-M-A+B P 1-B Y B S 6-M-A Cl A I M Li 7-M-V+B P 1-B Y B S 6-M-V Br V I M Li 7-A-V P 1- C Y C S 6-A-V Cl A Br V Li 7-M-A P 1-C Y C S 6-M-A Cl A I M Li 7-M-V P 1-C Y C S 6-M-V Br V I M At least one of the following: X is selected from Cl, Br, I; Y is selected from Sn, Si, In, Ge, Pb; Z is selected from As, Sb; 0 < N ≤ 2, 0 < M ≤ 2, 0 < A ≤ 2, 0 < V ≤ 2; 0 ≤ B ≤ 1, 0 ≤ C ≤ 1.

[0008] A method for preparing a sulfide solid electrolyte, comprising the steps of:

[0009] The raw materials corresponding to the molecular formula of the sulfide solid electrolyte are mixed according to a predetermined stoichiometric ratio, and then subjected to high-speed stirring to obtain precursor powder.

[0010] The precursor powder is placed in an atmosphere furnace, and an inert gas is continuously introduced. The temperature is raised to 350-550℃ and reacted for 1-12 hours to obtain the sulfide solid electrolyte.

[0011] The method for preparing the sulfide solid electrolyte, wherein the sulfide solid electrolyte comprises Li 7- N PS 6-N X N Li 7-M-A PS 6-M-A Cl A I M Li 7-A-V PS 6-A-V Cl A Br V Li 7-M-V PS 6-M-V Br V I M Li 7-N+B P 1-B Y B S 6-N X N Li 7- N P 1-C Z C S 6-N X N Li 7-A-V+B P 1-B Y B S 6-A-V Cl A Br V Li 7-M-A+B P 1-B Y B S 6-M-A Cl A I M Li 7-M-V+B P 1-B Y B S 6-M-V Br V I M Li 7-A-V P 1-C Y C S 6-A-V Cl A Br V Li 7-M-A P 1-C Y C S 6-M-A ClA I M Li 7-M-V P 1-C Y C S 6-M-V Br V I M At least one of the following: X is selected from Cl, Br, I; Y is selected from Sn, Si, In, Ge, Pb; Z is selected from As, Sb; 0 < N ≤ 2, 0 < M ≤ 2, 0 < A ≤ 2, 0 < V ≤ 2; 0 ≤ B ≤ 1, 0 ≤ C ≤ 1.

[0012] The method for preparing the sulfide solid electrolyte, wherein the raw materials include one or more of LiCl, Li2S, P2S5, LiI, SnS2, LiBr, SiS2, In2S3, GeS2, PbS, As2S3 or Sb2S3.

[0013] The method for preparing the sulfide solid electrolyte, wherein the high-speed stirring speed is 20,000-40,000 rpm and the high-speed stirring time is 10-30 minutes.

[0014] In the method for preparing the sulfide solid electrolyte, the heating rate in the step of heating to 350-550℃ is 3℃ / min.

[0015] The method for preparing the sulfide solid electrolyte further includes, after the reaction is completed, the step of cooling to room temperature at a rate of 2°C / min.

[0016] The method for preparing the sulfide solid electrolyte, wherein the inert gas includes one or more of argon, helium, neon, or nitrogen.

[0017] An application of a sulfide solid electrolyte, wherein the sulfide solid electrolyte prepared by the method described above or any of the above methods is used to prepare an all-solid-state lithium-ion battery.

[0018] An all-solid-state lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is a sulfide solid electrolyte as described above or a sulfide solid electrolyte prepared by any of the above-described methods.

[0019] Beneficial Effects: This invention provides a sulfide solid electrolyte, its preparation method, and an all-solid-state lithium-ion battery. The sulfide solid electrolyte uses a high-efficiency, mass-producible high-speed stirring method to prepare the precursor, applicable to a wide range of sulfide material systems. Under this method, the sulfide solid electrolyte material retains the valence state of sulfur to the greatest extent, avoiding the valence change of sulfur caused by inappropriate energy during ball milling, thereby reducing the formation of impurity phases after sintering, improving the crystallinity of the sulfide solid electrolyte, obtaining the purest phase possible, and thus improving the ionic conductivity and stability of the sulfide solid electrolyte at room temperature, resulting in ultra-high ionic conductivity (>2×10⁻⁶). -4 (S / cm) and low electronic conductivity (<1×10) -8 S / cm can improve the first-cycle coulombic efficiency, cycle stability, cycle life, and ability to cycle stably at high voltage in all-solid-state lithium batteries. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the preparation of sulfide solid electrolyte materials according to an embodiment of the present invention;

[0021] Figure 2 Li prepared using high-speed stirring in this embodiment of the invention 5.4 PS 4.4 Cl 1.6 Microstructure diagram;

[0022] Figure 3 The XRD patterns of solid electrolytes prepared from samples A, I, and L in Examples 1-4 of this invention at different doping values ​​are shown.

[0023] Figure 4 The AC impedance spectra of the electrolytes prepared from samples A, I, and L in Examples 1-4 of this invention are assembled into symmetrical cells.

[0024] Figure 5 This is a graph showing the first charge-discharge curve of an all-solid-state lithium-ion battery assembled from electrolyte A in Example 1 of this invention at a 0.1C rate.

[0025] Figure 6 The first charge-discharge curve of the sample I electrolyte assembled into an all-solid-state lithium-ion battery in Example 3 of this invention at a rate of 0.1C is shown.

[0026] Figure 7 This is a charge-discharge curve of the sample L electrolyte assembled into an all-solid-state lithium-ion battery in Example 4 of the present invention at a 0.1C rate. Detailed Implementation

[0027] This invention provides a sulfide solid electrolyte and its preparation method, as well as an all-solid-state lithium-ion battery. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] This invention provides a sulfide solid electrolyte, wherein the sulfide solid electrolyte comprises Li 7-N PS 6- N X N Li 7-M-A PS 6-M-A Cl A I M Li 7-A-V PS 6-A-V Cl A Br V Li 7-M-V PS 6-M-V Br V I M Li 7-N+B P 1-B Y B S 6-N X N Li 7-N P 1- C Z C S 6-N X N Li 7-A-V+B P 1-B Y B S 6-A-V Cl A Br V Li 7-M-A+B P 1-B Y B S 6-M-A Cl A I M Li 7-M-V+B P 1-B Y B S 6-M-V Br V I M Li 7-A- V P 1-C Y C S 6-A-V Cl A Br V Li 7-M-A P 1-C Y C S 6-M-A Cl A IM 、 Li 7-M-V P 1-C Y C S 6-M-V Br V I M at least one of; wherein, X is selected from one of Cl, Br, and I, Y is selected from one of Sn, Si, In, Ge, and Pb, Z is selected from one of As and Sb; 0 < N ≤ 2, 0 < M ≤ 2, 0 < A ≤ 2, 0 < V ≤ 2; 0 ≤ B ≤ 1, 0 ≤ C ≤ 1.

[0029] The sulfide solid electrolyte provided by the embodiment of the present invention includes a thiogermanate structure Li 7-N PS 6-N X N and related P-site and S-site doping, but not limited thereto. In some embodiments, the sulfide solid electrolyte further includes halogen doping, such as Br or I; carbon group element doping, such as Sn, Si, Ge, or Pb, and doping of other elements, etc. The doping of the above elements in the embodiment of the present invention can be effectively doped into the thiogermanate structure, broaden the lattice spacing, increase the degree of anion mixing, broaden the lithium ion transport channels, and greatly improve the ionic conductivity.

[0030] In some embodiments, in the chemical formula Li 7-N PS 6-N Cl N , N is preferably 0.5 < N < 1.6; when N is in this range, the conductivity of the sulfide solid electrolyte material can reach the optimum. Specifically, N = 0.5, 0.75, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6. However, N is not limited to the above values, and other unlisted values within this range are equally applicable.

[0031] In some embodiments, in the chemical formula Li 7-N+B P 1-B Sn B S 6-N Cl N , B is preferably 0 < B < 0.5; N is preferably 0.5 < N < 1.6; in this range, the conductivity of the sulfide solid electrolyte material > 1×10 -4 S / cm. Specifically, B = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5; N = 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6. However, B and N are not limited to the above values, and other unlisted values within this range are equally applicable.

[0032] The embodiment of the present invention also provides a preparation method of a sulfide solid electrolyte, such as Figure 1As shown, the steps include:

[0033] S10. The raw materials corresponding to the molecular formula of the sulfide solid electrolyte are mixed according to a predetermined stoichiometric ratio, and then subjected to high-speed stirring to obtain precursor powder.

[0034] S20. The precursor powder is placed in an atmosphere furnace, and an inert gas is continuously introduced. The temperature is raised to 350-550℃ and reacted for 1-12 hours to obtain the sulfide solid electrolyte.

[0035] The preparation of the sulfide solid electrolyte described in this invention differs from traditional ball milling. It employs high-efficiency, high-speed stirring for tens of minutes or even just a few minutes to obtain a uniform precursor. This precursor is then sintered in a single, large-scale process to obtain the sulfide solid electrolyte, which exhibits extremely high room-temperature ionic conductivity and high stability. Furthermore, the microstructure of the sulfide solid electrolyte samples prepared in this embodiment is essentially consistent with that of powders prepared by traditional ball milling, and the sintered particles are large and exhibit good crystallinity.

[0036] In some embodiments, the high-speed stirring treatment operates at a rotation speed of 20,000-40,000 rpm for 10-30 minutes. At this high-speed stirring speed and time, the raw materials can be thoroughly ground to obtain powder with uniform particle size. Insufficient treatment time leads to uneven mixing, inconsistent powder particle size, and large particle size differences, making it easy for raw material residues to remain after sintering. This results in unstable performance and low ionic conductivity of the obtained sulfide solid electrolyte material. Conversely, excessive treatment time can damage the initial sulfide solid electrolyte material, increasing the proportion of impurities after sintering and also reducing ionic conductivity. Specifically, the high-speed stirring treatment can be performed at a rotation speed of 40,000 rpm for 10 minutes or at a rotation speed of 30,000 rpm for 20 minutes. The required treatment time varies depending on the material system and can be adjusted according to the type of precursor.

[0037] In some implementations, due to the need to take heat dissipation into account, the high-speed stirring process can be paused for 1 minute every 5 minutes, and this cycle can be repeated.

[0038] In some embodiments, the high-speed stirring employs a rotating blade, which is a three-layered, double-headed blade slightly smaller than the inner diameter of the cavity.

[0039] In some embodiments, the particle size distribution D50 of the sulfide solid electrolyte precursor is 90 μm. Specifically, the speed and time of the high-speed stirring process can be appropriately adjusted according to different precursors and particle sizes.

[0040] The preparation method of this invention replaces the traditional high-energy ball milling method by using a high-speed stirring technique with a rotating blade to prepare the sulfide solid electrolyte precursor. This reduces the time required for ball milling from several hours to over ten hours to less than half an hour, and allows for the preparation of kilogram-scale precursors in a single operation, greatly improving preparation efficiency. Specifically, compared to traditional ball milling, this invention uses high-speed stirring to rapidly form the initial sulfide solid electrolyte precursor powder without further damaging the powder. Furthermore, for doped elements, this method allows the dopant elements to enter the crystal lattice to the maximum extent, reducing the formation of impurity phases. Simultaneously, this preparation method produces a uniform amorphous material with high ionic conductivity (>3×10⁻⁶). -4 (S / cm) and low electronic conductivity (<1×10) -8 Its ultra-high ionic conductivity (S / cm) and electrolyte stability can reduce the occurrence of side reactions and improve the first-cycle coulombic efficiency, cycle stability and cycle life of all-solid-state lithium batteries.

[0041] In some embodiments, the raw materials include one or more of LiCl, Li₂S, P₂S₅, LiI, SnS₂, LiBr, SiS₂, In₂S₃, GeS₂, PbS, As₂S₃, or Sb₂S₃. The appropriate raw materials can be selected depending on the specific sulfide solid electrolyte. For example, to prepare LPSC electrolyte, LiCl, Li₂S, and P₂S₅ can be selected; to prepare LPSCI electrolyte, LiCl, Li₂S, LiI, and P₂S₅ can be selected; to prepare LPSnSCI electrolyte, LiCl, Li₂S, LiI, SnS₂, and P₂S₅ can be selected, etc., as needed. It should also be noted that this invention does not have special requirements regarding the source of the raw materials used; commercially available materials are sufficient.

[0042] In some specific embodiments, the preparation of sulfide solid electrolyte LPSC includes the following steps:

[0043] S100. LiCl, P2S5 and Li2S are weighed according to different chemical formulas in stoichiometric ratios, mixed and subjected to high-speed stirring to obtain a mixed powder.

[0044] S200. The mixed powder is placed in an atmosphere furnace, and an inert gas is continuously introduced. The temperature is raised to 300-550℃ and reacted for 1-10 hours. After being cooled to room temperature, it is crushed and collected to obtain sulfide solid electrolyte LPSC.

[0045] Specifically, the high-speed stirring speed is 20,000-40,000 rpm, and the high-speed stirring time is 10-30 minutes.

[0046] In some embodiments, the heating rate in the step of heating to 350-550°C is 3°C / min.

[0047] In some embodiments, after heating to 300-550°C and reacting for 1-10 hours, the process further includes cooling to room temperature at a rate of 2°C / min.

[0048] In some embodiments, the inert gas includes one or more of argon, helium, neon, or nitrogen.

[0049] In some embodiments, in step S20, the container for the high-temperature sintering reaction is made of alumina, a quartz crucible, or a titanium can.

[0050] The method for preparing sulfide solid electrolytes provided in this invention replaces the traditional ball milling method. It employs a high-efficiency, high-speed stirring method to prepare precursor powder. The obtained sulfide is placed in a large container in an atmosphere furnace, where an inert gas is continuously introduced, and the temperature is raised to 350-550℃ for 1-10 hours. Finally, the obtained sulfide solid electrolyte is collected by crushing. This method is applicable to a wide range of sulfide material systems. The sulfide solid electrolyte material prepared using this method retains the valence state of sulfur to the greatest extent possible, avoiding the valence change of sulfur caused by inappropriate energy in ball milling. This reduces the formation of impurity phases after sintering, improves the crystallinity of the sulfide solid electrolyte, and yields a purer phase, thereby improving the ionic conductivity and stability of the sulfide solid electrolyte at room temperature. Meanwhile, this method is simple and easy to operate, and is suitable for large-scale production. The initial sulfide solid electrolyte powder can be obtained within half an hour by mixing and stirring at high speed. Subsequently, a large-capacity alumina crucible is used to heat the powder under an inert gas to obtain kilogram-level sulfide solid electrolyte. The electrolyte has good stability and high conductivity, which greatly reduces the time cost of material preparation and improves the commercialization process.

[0051] This invention also provides an application of a sulfide solid electrolyte, wherein the sulfide solid electrolyte prepared by the method described above or any of the above methods is used to prepare an all-solid-state lithium-ion battery.

[0052] This invention also provides an all-solid-state lithium-ion battery, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is a sulfide solid electrolyte as described above or a sulfide solid electrolyte prepared by any of the above-described methods.

[0053] The following specific embodiments further illustrate the present invention, including a sulfide solid electrolyte, its preparation method, and an all-solid-state lithium-ion battery:

[0054] Example 1 Synthesis of LPSC

[0055] Weigh out the following items from inside the glove box:

[0056] Sample A: 21.4g Li₂S, 20.7g P₂S₅, 7.9g LiCl (Li₆PS₅Cl)

[0057] Sample B: 20.57g Li₂S, 20.73g P₂S₅, 8.69g LiCl (Li 5.9 PS 4.9 Cl 1.1 )

[0058] Sample C: 19.74g Li₂S, 20.75g P₂S₅, 9.5g LiCl (Li 5.8 PS 4.8 Cl 1.2 )

[0059] Pour the raw materials in the above proportions into the grinding machine chamber and mix them at high speed for 15 minutes. Since heat dissipation needs to be considered, a 1-minute break can be taken every 5 minutes. This will produce the precursor.

[0060] The precursor was placed in an alumina crucible and sintered at 560℃ under an argon atmosphere for 8 hours. The heating rate was 3℃ / min, and the cooling rate was 2℃ / min. After sintering, the sample was collected and thoroughly ground in a glove box. It was then sieved using a 30-micron sieve to obtain the LPSC sample with the corresponding molecular formula.

[0061] Example 2 Synthesis of LPSC

[0062] Weigh out the following items from inside the glove box:

[0063] Sample D: 18.9g Li₂S, 20.78g P₂S₅, 10.30g LiCl (Li 5.7 PS 4.7 Cl 1.3 )

[0064] Sample E: 18.07g Li₂S, 20.81g P₂S₅, 11.11g LiCl (Li 5.6 PS 4.6 Cl 1.4 )

[0065] Sample F: 17.23g Li₂S, 20.84g P₂S₅, 11.9g LiCl (Li 5.5 PS 4.5 Cl 1.5 )

[0066] Sample G: 16.39g Li₂S, 20.87g P₂S₅, 12.73g LiCl (Li 5.4 PS 4.4 Cl 1.6 )

[0067] Pour the raw materials in the above proportions into the grinding machine chamber and mix them at high speed for 10 minutes. Since heat dissipation needs to be considered, a 1-minute break can be made every 5 minutes. This will produce the precursor.

[0068] The precursor was placed in an alumina crucible and sintered at 520℃ under an argon atmosphere for 8 hours. The heating rate was 3℃ / min, and the cooling rate was 2℃ / min. After sintering, the sample was collected and thoroughly ground in a glove box. It was then sieved using a 30-micron sieve to obtain the LPSC sample with the corresponding molecular formula.

[0069] Example 3 Synthesis of LPSCI

[0070] Weigh out the following items from inside the glove box:

[0071] Sample H: 21.04g Li₂S, 20.35g P₂S₅, 7.37g LiCl, 1.23g LiI (Li₆PS₅Cl) 0.95 I 0.05 )

[0072] Sample I: 21.69g Li₂S, 20.02g P₂S₅, 6.87g LiCl, 2.41g LiI (Li₆PS₅Cl) 0.9 I 0.1 )

[0073] Sample J: 20.03g Li₂S, 19.38g P₂S₅, 5.91g LiCl, 4.66g LiI (Li₆PS₅Cl) 0.8 I 0.2 )

[0074] Pour the raw materials in the above proportions into the grinding mill chamber and mix them at high speed for 18 minutes. Since heat dissipation needs to be considered, a 1-minute break can be taken every 5 minutes. This will produce the precursor.

[0075] The precursor was placed in an alumina crucible and sintered at 550℃ under an argon atmosphere for 12 hours. The heating rate was 3℃ / min, and the cooling rate was 2℃ / min. After sintering, the sample was collected and thoroughly ground in a glove box. It was then sieved using a 30-micron sieve to obtain the LPSC sample with the corresponding molecular formula.

[0076] Example 4 LPSnSCI

[0077] Sample K: 20.55g Li₂S, 18.7g P₂S₅, 6.75g LiCl, 2.37g LiI, 1.62g SnS₂(Li 6.05 Sn 0.05 P 0.95 S5Cl 0.9 I 0.1 )

[0078] Sample L: 20.41g Li₂S, 17.42g P₂S₅, 6.64g LiCl, 2.33g LiI, 3.18g SnS₂(Li 6.1 Sn 0.1 P 0.9 S5Cl 0.9 I 0.1 )

[0079] Sample M: ​​20.14g Li₂S, 14.99g P₂S₅, 6.43g LiCl, 2.25g LiI, 6.16g SnS₂(Li 6.2 Sn 0.2 P 0.8 S5Cl 0.9 I 0.1 )

[0080] Pour the raw materials in the above proportions into the grinding machine chamber and mix them at high speed for 20 minutes. Since heat dissipation needs to be considered, a 1-minute break can be taken every 5 minutes. This will produce the precursor.

[0081] The precursor was placed in an alumina crucible and sintered at 500℃ under an argon atmosphere for 12 hours. The heating rate was 3℃ / min, and the cooling rate was 2℃ / min. After sintering, the sample was collected and thoroughly ground in a glove box. It was then sieved using a 30-micron sieve to obtain the LPSC sample with the corresponding molecular formula.

[0082] Test Example 1

[0083] The sample G(Li) obtained in Example 2 above 5.4 PS 4.4 Cl 1.6 ) to observe, its microstructure is as follows Figure 2 As shown in the figure, the microstructure of the sample prepared in this embodiment is basically the same as that of the powder prepared by traditional ball milling, and the sintered particles are large and have good crystallinity.

[0084] X-ray diffraction was performed on the sulfide solid electrolyte samples A, I, and L prepared in Examples 1-4 above, with diffraction angles ranging from 20° to 70°. The XRD results are as follows: Figure 3 As shown in the figure, the XRD pattern in the example exhibits a very pure silver-germanium sulfide structure, with high main peak intensity and few impurity peaks.

[0085] Test Example 2

[0086] The electrochemical performance of the sulfide solid electrolytes prepared in Examples 1-4 above was tested:

[0087] Ionic conductivity testing: This was obtained using an electrochemical workstation with AC impedance spectroscopy (EIS) ranging from 10 to 1,000,000 Hz at 25°C. 0.3 g of solid electrolyte powder was poured into a 10 mm diameter sleeve and compressed using a tablet press at 200 MPa for 1 minute. The thickness of the solid electrolyte disc was measured using a micrometer. A carbon-coated copper foil was placed at each end of the solid electrolyte disc (carbon end facing the solid electrolyte), forming a blocked cell of carbon-coated aluminum foil / electrolyte disc / carbon-coated aluminum foil. This cell was placed in a conductivity testing kit, pressurized to 200 MPa, and connected to the electrochemical workstation for EIS testing (range 10–1,000,000 Hz). A DC voltage of 200 mV was applied at 25°C. The results are as follows: Figure 4 As shown in the figure, at room temperature, the impedances of samples A, I, and L are 53.2Ω, 28.9Ω, and 43.0Ω, respectively, with corresponding conductivityes of 3.8ms / cm, 4.1ms / cm, and 5.2ms / cm.

[0088] Test Example 3

[0089] The sulfide solid electrolyte Li6PS5Cl (sample A) provided in Example 1 and the sulfide solid electrolyte Li6PS5Cl provided in Example 3 were compared. 0.9 I 0.1 (Sample I), the sulfide solid electrolyte Li provided in Example 4 6.1 Sn 0.1 P 0.9 S5Cl 0.9 I 0.1 (Sample L) The first-cycle coulombic efficiency and discharge capacity were tested using a Newwell tester, including the following specific steps:

[0090] 1) Take a certain amount of the above electrolyte material and compress it into tablets under a pressure of 40 MPa to obtain LPSC solid electrolyte tablets;

[0091] 2) On one side of the solid electrolyte sheet prepared in step 1), a certain mass of ternary cathode material and sulfide solid electrolyte are added to form a cathode material; on the other side of the solid electrolyte, a mixture of graphite and sulfide solid electrolyte is added to form a negative electrode material; and the solid electrolyte sheet is pressed at 300 MPa to obtain an all-solid-state lithium-ion battery.

[0092] 3) Perform 0.1C charge and discharge cycles on the all-solid-state lithium battery obtained in step 2), with a voltage range of 3-4.2V vs. Li / Li. + .

[0093] The first-cycle coulombic efficiency of the all-solid-state battery assembled with samples A, I, and L is as follows: Figures 5-7 As shown in the figure, the battery composed of the sulfide solid electrolyte material prepared in the embodiment of the present invention has a first-cycle coulombic efficiency of over 82%, indicating that the high conductivity and stability of the electrolyte prepared in this way will significantly improve the reversible capacity during charge and discharge. At the same time, the battery composed of the sulfide electrolyte material prepared in the embodiment of the present invention has an even higher charge and discharge capacity, even reaching 175 mAh / g.

[0094] In summary, this invention provides a sulfide solid electrolyte, its preparation method, and an all-solid-state lithium-ion battery. The preparation method replaces the traditional ball milling method, employing a high-efficiency and large-scale high-speed stirring process to prepare the precursor. The obtained sulfide is placed in a large container in an atmosphere furnace, continuously purged with inert gas, and heated to 350-550℃ for 1-10 hours. Finally, the obtained sulfide solid electrolyte is collected by crushing. This method is applicable to a wide range of sulfide material systems. The sulfide solid electrolyte material prepared using this method retains the valence state of sulfur to the greatest extent, avoiding the valence change of sulfur caused by inappropriate energy in ball milling, thereby reducing the formation of impurity phases after sintering, improving the crystallinity of the sulfide solid electrolyte, obtaining a purer phase, and thus improving the ionic conductivity and stability of the sulfide solid electrolyte at room temperature. This invention obtains a uniform sulfide solid electrolyte precursor through high-speed stirring, and the resulting sulfide solid electrolyte exhibits extremely high ionic conductivity (>2×10⁻⁶). -4 (S / cm) and low electronic conductivity (<1×10) -8 S / cm), for example, the solid electrolyte material Li described in this invention. 5.4 PS 4.4 Cl 1.6 At 25°C, the ionic conductivity is greater than 1×10⁻⁶. -2 The ionic conductivity of Li6PS5Cl is greater than 4 × 10⁻⁶ S / cm. -3The S / cm ratio can improve the first-cycle coulombic efficiency, cycle stability, cycle life, and stable cycling capability under high voltage in all-solid-state lithium batteries. Furthermore, this preparation method allows for the formation of a complete precursor from sulfides in just half an hour, enabling the simultaneous preparation of hundreds or even thousands of grams of precursors. This high efficiency in preparation time and large-scale processing significantly reduces time costs, thereby accelerating the commercialization of sulfide solid electrolyte materials.

[0095] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A sulfide solid electrolyte, characterized in that, The sulfide solid electrolyte includes Li6PS5Cl and Li6PS5Cl. 0.9 I 0.1 Or Li 6.1 Sn 0.1 P 0.9 S5Cl 0.9 I 0.1 ; The sulfide solid electrolyte has a room temperature ionic conductivity greater than or equal to 3.8 × 10⁻⁶. -3 S / cm, and electronic conductivity less than 1×10 -8 S / cm; The preparation method of the sulfide solid electrolyte includes the following steps: The raw materials corresponding to the molecular formula of the sulfide solid electrolyte are mixed according to a predetermined stoichiometric ratio, and then subjected to high-speed stirring to obtain precursor powder. The precursor powder was placed in an atmosphere furnace, and an inert gas was continuously introduced. The temperature was raised to 350-550℃ and reacted for 1-12 hours to obtain the sulfide solid electrolyte. The high-speed stirring process is carried out at a speed of 20,000-40,000 rpm for 10-30 minutes; the high-speed stirring process is intermittent, with a 1-minute pause after every 5 minutes of stirring. In the step of heating to 350-550℃, the heating rate is 3℃ / min.

2. A method for preparing a sulfide solid electrolyte, characterized in that, Including the following steps: The raw materials corresponding to the molecular formula of the sulfide solid electrolyte are mixed according to a predetermined stoichiometric ratio, and then subjected to high-speed stirring to obtain precursor powder. The precursor powder was placed in an atmosphere furnace, and an inert gas was continuously introduced. The temperature was raised to 350-550℃ and reacted for 1-12 hours to obtain the sulfide solid electrolyte. The high-speed stirring process is carried out at a speed of 20,000-40,000 rpm for 10-30 minutes; the high-speed stirring process is intermittent, with a 1-minute pause after every 5 minutes of stirring. In the step of heating to 350-550℃, the heating rate is 3℃ / min.

3. The method for preparing the sulfide solid electrolyte according to claim 2, characterized in that, The sulfide solid electrolyte includes Li6PS5Cl and Li6PS5Cl. 0.9 I 0.1 Or Li 6.1 Sn 0.1 P 0.9 S5Cl 0.9 I 0.1 .

4. The method for preparing the sulfide solid electrolyte according to claim 3, characterized in that, The raw materials include one or more of LiCl, Li2S, P2S5, LiI, and SnS2.

5. The method for preparing the sulfide solid electrolyte according to claim 2, characterized in that, After the reaction is complete, the process also includes the step of cooling to room temperature at a rate of 2°C / min.

6. The method for preparing the sulfide solid electrolyte according to claim 2, characterized in that, The inert gas includes one or more of argon, helium, neon, or nitrogen.

7. An application of a sulfide solid electrolyte, characterized in that, The sulfide solid electrolyte prepared by the method described in claim 1 or any of the methods described in claims 2-6 is used to prepare an all-solid-state lithium-ion battery.

8. An all-solid-state lithium-ion battery, comprising a positive electrode, a negative electrode, and an electrolyte, characterized in that, The electrolyte is the sulfide solid electrolyte of claim 1 or the sulfide solid electrolyte prepared by the preparation method of any one of claims 2-6.

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