Preparation method and application of small-particle-size sulfide solid electrolyte

Abstract

This invention provides a method for preparing small-particle-size sulfide solid electrolytes and their applications. Under an inert atmosphere, a sulfide solid electrolyte precursor is mixed with a first solvent and reacted. The first solvent is selected from at least one of ethylenediamine, N,N-dimethylacetamide, and 1,2-ethylenedithiol. The mixture is then further mixed with a second solvent, and stirred to precipitate the sulfide solid electrolyte. The second solvent is selected from at least one of n-hexane, n-heptane, ethyl acetate, ethyl propionate, and N,N-dimethylacetamide. Solvent separation, drying, and heat treatment are then performed. This method synthesizes the sulfide solid electrolyte in the first solvent, which is then directly transferred to the second solvent, allowing the sulfide solid electrolyte to precipitate. Direct solvent separation eliminates the crystallization process, significantly reducing time and costs. The method is simple and efficient, resulting in high purity and high ionic conductivity. The resulting battery exhibits high discharge capacity, excellent cycle performance, rate capability, and limiting current density.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte technology, and particularly relates to a method for preparing small-particle-size sulfide solid electrolytes and their applications. Background Technology

[0002] The current development trend of lithium batteries is a shift from liquid to solid-state, combining high energy density and high safety. Among existing solid-state electrolyte materials, sulfide solid-state electrolytes have attracted widespread attention from the scientific and industrial communities due to their highest room-temperature ionic conductivity and their relatively soft texture, which allows for the reduction of electrolyte / electrode interface impedance through cold pressing.

[0003] In solid-state batteries, due to the rigid solid-solid contact between the electrolyte and the electrode inside the battery, the solid electrolyte cannot penetrate into the electrode like a liquid electrolyte, thus failing to construct an effective three-dimensional ion transport channel. Therefore, it is necessary to add some solid electrolyte particles inside the positive electrode to conduct lithium ions. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing small-particle-size sulfide solid electrolytes and their applications. This method is simple and easy to obtain small-particle-size sulfide solid electrolytes, and has high ionic conductivity.

[0005] This invention provides a method for preparing a small-particle-size sulfide solid electrolyte, comprising the following steps:

[0006] Under an inert atmosphere, the sulfide solid electrolyte precursor and the first solvent are mixed and reacted to obtain a sulfide solid electrolyte solution; the first solvent is selected from at least one of ethylenediamine, hydrazine, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol.

[0007] The sulfide solid electrolyte solution is mixed with the second solvent, and the mixture is stirred to precipitate the sulfide solid electrolyte, thereby obtaining a sulfide solid electrolyte suspension; the second solvent is selected from at least one of tetrahydrofuran, n-hexane, n-heptane, ethyl acetate, diethylene glycol dimethyl ether, ethyl propionate, acetone, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol.

[0008] The solvent in the sulfide solid electrolyte suspension was separated and dried to obtain an amorphous sulfide solid electrolyte.

[0009] The amorphous sulfide solid electrolyte was heat-treated to obtain a small-particle-size sulfide solid electrolyte.

[0010] Preferably, the volume ratio of the second solvent to the first solvent is greater than 1.

[0011] Preferably, the small-particle-size sulfide solid electrolyte is selected from Li3PS4; Li7PS6; Li 7-x PS 6-x Y x 0 < x ≤ 1, Y is selected from Cl - ,Br - I - Li7P3S 11 Li₂GeS₃; Li₂SiS₃; Li₂SnS₃; Li 10 GeP2S 12 and Li 10 SnP2S 12 One or more of them.

[0012] Preferably, the particle size D50 of the small-particle-size sulfide solid electrolyte is less than 1 μm.

[0013] Preferably, the sulfide solid electrolyte precursor is prepared by uniformly grinding the raw materials required for the target small-particle-size sulfide solid electrolyte;

[0014] The raw materials required for the target small-particle-size sulfide solid electrolyte include two or more of the following: Li, S8, Li2S, Li2Se, SiS2, P2S5, P2S3, LiCl, LiI, LiBr, GeS2, and SnS.

[0015] Preferably, the heat treatment temperature is 100–700°C, the heat treatment time is 1–24 h, and the heat treatment heating rate is 0.1–10°C / min.

[0016] Preferably, the reaction is carried out under stirring conditions; the stirring rate is 200-1500 rpm; the reaction temperature is 20-80°C; and the reaction time is 0.5-24 h.

[0017] This invention provides a solid electrolyte membrane, which is prepared from a small-particle-size sulfide solid electrolyte prepared by the preparation method described above.

[0018] This invention provides a solid-state battery, comprising a composite positive electrode and a negative electrode;

[0019] The composite cathode includes a small-particle-size sulfide solid electrolyte prepared by the preparation method described in the above technical solution.

[0020] This invention provides a solid-state battery, comprising a positive electrode and a composite negative electrode;

[0021] The composite negative electrode includes a small-particle-size sulfide solid electrolyte prepared by the preparation method described in the above technical solution.

[0022] This invention provides a method for preparing a small-particle-size sulfide solid electrolyte, comprising the following steps: mixing a sulfide solid electrolyte precursor and a first solvent under an inert atmosphere and reacting to obtain a sulfide solid electrolyte solution; the first solvent is selected from at least one of ethylenediamine, hydrazine, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol; mixing the sulfide solid electrolyte solution with a second solvent and stirring to precipitate the sulfide solid electrolyte, obtaining a sulfide solid electrolyte suspension; the second solvent is selected from at least one of tetrahydrofuran, n-hexane, n-heptane, ethyl acetate, diethylene glycol dimethyl ether, ethyl propionate, acetone, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol; separating the solvent from the sulfide solid electrolyte suspension and drying to obtain an amorphous sulfide solid electrolyte; and heat-treating the amorphous sulfide solid electrolyte to obtain a small-particle-size sulfide solid electrolyte. This method involves synthesizing a sulfide solid electrolyte in a specific type of first solvent, followed by direct transfer to a specific type of second solvent. The small-particle-size sulfide solid electrolyte precipitates out, allowing for direct solvent separation without a crystallization process, significantly reducing time and costs. This method is simple and efficient. The sulfide solid electrolyte prepared by this method has high purity and high ionic conductivity. When used in the positive or negative electrode, the small-particle-size sulfide solid electrolyte enables the battery to exhibit high discharge capacity, excellent cycle performance, rate performance, and limiting current density. Attached Figure Description

[0023] Figure 1 The XRD pattern of the sulfide solid electrolyte prepared in Example 1 of this invention;

[0024] Figure 2 The XRD pattern of the sulfide solid electrolyte prepared in Example 2 of this invention;

[0025] Figure 3 The XRD pattern of the sulfide solid electrolyte prepared in Example 3 of this invention;

[0026] Figure 4 The XRD pattern of the sulfide solid electrolyte prepared in Example 4 of this invention;

[0027] Figure 5 The XRD pattern of the sulfide solid electrolyte prepared in Example 5 of this invention;

[0028] Figure 6 The XRD pattern of the sulfide solid electrolyte prepared in Example 6 of this invention;

[0029] Figure 7 This is a scanning electron microscope image of the sulfide solid electrolyte prepared in Example 4 of the present invention;

[0030] Figure 8The XRD pattern of the sulfide solid electrolyte prepared in comparison.

[0031] Figure 9 The image shows a scanning electron microscope (SEM) image of the sulfide solid electrolyte prepared in the comparative example. Detailed Implementation

[0032] This invention provides a method for preparing a small-particle-size sulfide solid electrolyte, comprising the following steps:

[0033] Under an inert atmosphere, the sulfide solid electrolyte precursor and the first solvent are mixed and reacted to obtain a sulfide solid electrolyte solution; the first solvent is selected from at least one of ethylenediamine, hydrazine, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol.

[0034] The sulfide solid electrolyte solution is mixed with the second solvent, and the mixture is stirred to precipitate the sulfide solid electrolyte, thereby obtaining a sulfide solid electrolyte suspension; the second solvent is selected from at least one of tetrahydrofuran, n-hexane, n-heptane, ethyl acetate, diethylene glycol dimethyl ether, ethyl propionate, acetone, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol.

[0035] The solvent in the sulfide solid electrolyte suspension was separated and dried to obtain an amorphous sulfide solid electrolyte.

[0036] The amorphous sulfide solid electrolyte was heat-treated to obtain a small-particle-size sulfide solid electrolyte.

[0037] The method provided by this invention synthesizes sulfide solid electrolytes in a first solvent of a specific type, and then directly transfers them to a second solvent of a specific type. The small-particle-size sulfide solid electrolytes can then precipitate out, and the solvent can be directly separated without a crystallization process, which greatly reduces time costs and is simple and efficient. The sulfide solid electrolytes prepared by this method have high purity and high ionic conductivity.

[0038] In this invention, a sulfide solid electrolyte precursor and a first solvent are mixed and reacted under an inert atmosphere to obtain a sulfide solid electrolyte solution; the first solvent is selected from at least one of ethylenediamine, hydrazine, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol.

[0039] The sulfide solid electrolyte precursor described in this invention is prepared by uniformly grinding the raw materials required for the target small-particle-size sulfide solid electrolyte.

[0040] The raw materials required for the target small-particle-size sulfide solid electrolyte include two or more of the following: Li, S8, Li2S, Li2Se, SiS2, P2S5, P2S3, LiCl, LiI, LiBr, GeS2, and SnS.

[0041] If the target small-particle-size sulfide solid electrolyte is Li6PS5Cl, the required raw materials can be Li2S, P2S5, LiCl and S8, or Li, S8, P2S5 and LiCl, or Li2S, P2S5 and LiCl; in a specific embodiment, the target small-particle-size sulfide solid electrolyte is Li6PS5Cl, and the required raw materials are Li2S, P2S5 and LiCl.

[0042] If the target small-particle-size sulfide solid electrolyte is Li3PS4, the required raw materials can be S8, Li2S and P2S5, or Li2S and P2S5; in a specific embodiment, the target small-particle-size sulfide solid electrolyte is Li3PS4, and the required raw materials are Li2S and P2S5.

[0043] If the target small-particle-size sulfide solid electrolyte is Li 5.5 PS 4.5 Cl 1.5 The required raw materials can be Li₂S, P₂S₅, LiCl, and S₈, or Li, S₈, P₂S₅, and LiCl, or Li₂S, P₂S₅, and LiCl. In a specific embodiment, the target small-particle-size sulfide solid electrolyte is Li. 5.5 PS 4.5 Cl 1.5 The required raw materials are Li2S, P2S5, and LiCl;

[0044] If the target small-particle-size sulfide solid electrolyte is Li7PS6, the required raw materials can be Li2S, P2S5, or Li, S8 and P2S5.

[0045] If the target small-particle-size sulfide solid electrolyte is Li2SiS3, then the required raw materials are Li2S, SiS2 and P2S5.

[0046] If the target small-particle-size sulfide solid electrolyte is Li 10 GeP2S 12 The required raw materials are Li2S, P2S5 and GeS2.

[0047] The reaction described in this invention is carried out under stirring conditions; the stirring rate is 200–1500 rpm; the reaction temperature is 20–80°C; and the reaction time is 0.5–24 h. In the first solvent, the components of the sulfide solid electrolyte precursor dissolve and undergo intermolecular collisions, thereby reacting to obtain a sulfide solid electrolyte solution.

[0048] This invention involves mixing the sulfide solid electrolyte solution with a second solvent under an inert atmosphere, stirring to precipitate the sulfide solid electrolyte, and obtaining a sulfide solid electrolyte suspension. The second solvent is selected from at least one of tetrahydrofuran, n-hexane, cyclohexane, n-heptane, ethyl acetate, diethylene glycol dimethyl ether, ethyl propionate, acetone, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethanedithiol. The stirring method can be magnetic stirring, mechanical stirring, or ultrasonic dispersion, but is not limited to these methods; any method sufficient to fully dissolve and react the sulfide solid electrolyte precursor is acceptable. In the aforementioned second solvents, the sulfide solid electrolyte is refined, and stirring for a period of time allows it to fully precipitate, resulting in the sulfide solid electrolyte suspension.

[0049] In this invention, the volume ratio of the second solvent to the first solvent is preferably greater than 1; more preferably, the volume ratio of the second solvent to the first solvent is 4 to 6:1; in a specific embodiment, the volume ratio of the second solvent to the first solvent is 5:1. In a specific embodiment, the first solvent is ethylenediamine and the second solvent is n-hexane; or the first solvent is a mixture of ethylenediamine and 1,2-ethylenedithiol in a volume ratio of 1:1 and the second solvent is n-hexane; or the first solvent is a mixture of ethylenediamine and 1,2-ethylenedithiol in a volume ratio of 1:1 and the second solvent is a mixture of n-hexane and ethyl acetate in a volume ratio of 1:1.

[0050] Preferably, this invention involves separating the solvent from the sulfide solid electrolyte suspension under an inert atmosphere and drying it to obtain an amorphous sulfide solid electrolyte. The solvent separation in this invention is performed by centrifugation, rotary evaporation, or high-temperature treatment; the first solvent, the second solvent, and the sulfide solid electrolyte are separated.

[0051] After separation, the present invention preferably dries the residual solvent on the sulfide solid electrolyte under an inert atmosphere; the drying method is vacuum drying or freeze drying. The equipment used for drying includes, but is not limited to, vacuum ovens, atmosphere furnaces, muffle furnaces, rotary evaporators, freeze desiccants, etc., as long as the solvent remaining on the sulfide solid electrolyte precursor can be removed.

[0052] After obtaining the amorphous sulfide solid electrolyte, this invention heat-treats the amorphous sulfide solid electrolyte to obtain a small-particle-size sulfide solid electrolyte. The small-particle-size sulfide solid electrolyte is a crystalline electrolyte. The small-particle-size sulfide solid electrolyte in this invention is selected from Li3PS4; Li7PS6; Li 7-x PS 6-x Y x 0 < x ≤ 1, Y is selected from Cl - ,Br - I - Li7P3S 11Li₂GeS₃; Li₂SiS₃; Li₂SnS₃; Li 10 GeP2S 12 and Li 10 SnP2S 12 One or more of the following. The Li 7-x PS 6- x Y x It can be Li6PS5Cl or Li 5.5 PS 4.5 Cl 1.5 In a specific embodiment, the small-particle-size sulfide solid electrolyte is Li6PS5Cl, Li3PS4, or Li 5.5 PS 4.5 Cl 1.5 .

[0053] The heat treatment temperature described in this invention is 100–700°C, the heat treatment time is 1–24 h, and the heating rate is 0.1–10°C / min. In a specific embodiment, the heat treatment temperature is 300°C or 550°C; the heat treatment time is 5 h or 10 h; and the heating rate is 5°C / min.

[0054] The particle size D50 of the small-particle-size sulfide solid electrolyte prepared by this invention is less than 1 μm. In a specific embodiment, the particle size D50 of the small-particle-size sulfide solid electrolyte is 395–830 nm, and the D90 is 860–1460 nm.

[0055] The small-particle-size sulfide solid electrolyte Li6PS5Cl prepared by this invention has an ionic conductivity of 5.50–5.63 mS / cm or 4.49–4.57 mS / cm; the small-particle-size sulfide solid electrolyte Li6PS5Cl has an ionic conductivity of 5.50–5.63 mS / cm or 4.49–4.57 mS / cm. 5.5 PS 4.5 Cl 1.5 The ionic conductivity of the small-particle-size sulfide solid electrolyte Li3PS4 is 6.73–6.81 mS / cm; the ionic conductivity of the small-particle-size sulfide solid electrolyte Li3PS4 is 0.72–0.87 mS / cm.

[0056] The present invention also provides a solid electrolyte membrane, which is prepared by the preparation method described above using a small-particle-size sulfide solid electrolyte.

[0057] The electrolyte membrane described above has excellent flatness and density.

[0058] Experimental results show that solid electrolyte membranes prepared using small-particle-size sulfide solid electrolytes have lower porosity, which can also be observed by scanning electron microscopy. They have higher density than solid electrolyte membranes prepared using larger-particle-size electrolyte powders.

[0059] The solid electrolyte membrane further includes a binder and a solvent; the mass ratio of the small-particle-size sulfide solid electrolyte, binder and solvent is (1.9-2.0):(1.5-1.6):(0.75-0.85); in a specific embodiment, the binder is SEBS and the solvent is p-xylene; the mass ratio of the small-particle-size sulfide solid electrolyte, binder and solvent is 1.96:1.523:0.8.

[0060] The solid electrolyte membrane is preferably obtained by coating a slurry comprising a small-particle-size sulfide solid electrolyte onto a substrate; the solid content of the slurry is 45-50%; in a specific embodiment, the solid content is 46.7%. The substrate is PET.

[0061] This invention provides a battery comprising a composite positive electrode and a negative electrode;

[0062] The composite positive electrode and / or composite negative electrode include a small-particle-size sulfide solid electrolyte prepared by the preparation method described in the above technical solution.

[0063] By adding a portion of the above-mentioned small-particle-size sulfide solid electrolyte to the positive or negative electrode, with an addition amount of 10-20 wt%, the positive or negative electrode particles can be coated to achieve a better ion transport effect.

[0064] The slurry for preparing the composite positive electrode includes a positive electrode, a binder, a solvent, and a conductive agent. The positive electrode is NCM811, the binder is PIB, the solvent is p-xylene, and the conductive agent is Super C65. The solid content of the slurry is 65-75%, preferably 68-72%. In a specific embodiment, the proportion of each component in the composite positive electrode is NCM811:Li6PS5Cl:Super C65:PIB = 80:16.4:1.6:2.

[0065] The present invention preferably involves coating the above-mentioned slurry onto an aluminum foil substrate to obtain a composite positive electrode.

[0066] In a specific embodiment of the present invention, the battery includes a composite positive electrode, a lithium metal negative electrode, and the aforementioned electrolyte membrane.

[0067] This invention provides a solid-state battery, comprising a positive electrode and a composite negative electrode;

[0068] The composite negative electrode includes a small-particle-size sulfide solid electrolyte prepared by the preparation method described in the above technical solution.

[0069] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of a method for preparing a small-particle-size sulfide solid electrolyte and its application, should not be construed as limiting the scope of protection of the present invention.

[0070] Example 1

[0071] A method for preparing a sulfide solid electrolyte Li6PS5Cl includes the following steps:

[0072] S1. In a glove box filled with inert gas, weigh 0.383g Li2S, 0.37g P2S5 and 0.141g LiCl according to the preset molar ratio, transfer them to a degassing machine and grind them evenly to obtain Li6PS5Cl electrolyte precursor.

[0073] S2. In a glove box filled with inert gas, the Li6PS5Cl precursor was transferred to a container containing 10 mL of ethylenediamine and stirred at 55 °C for 24 h to obtain an ethylenediamine solution of Li6PS5Cl.

[0074] S3. In a glove box filled with inert gas, transfer the Li6PS5Cl solution to a container containing 50mL of n-hexane, and stir thoroughly to obtain a Li6PS5Cl suspension.

[0075] S4. In a glove box filled with inert gas, the above Li6PS5Cl suspension is centrifuged to separate the Li6PS5Cl electrolyte from ethylenediamine / n-hexane, and a solid Li6PS5Cl electrolyte containing a small amount of solvent is obtained.

[0076] S5. In a glove box filled with inert gas, the Li6PS5Cl obtained above is transferred to a vacuum drying oven to remove the residual solvent and obtain amorphous Li6PS5Cl electrolyte.

[0077] S6. In a glove box filled with inert gas, the amorphous Li6PS5Cl electrolyte powder obtained in the previous step was transferred to a muffle furnace for heat treatment. It was calcined at 550℃ for 10h with a heating rate of 5℃ / min. After that, the sample was ground and sieved to obtain a high-purity small-particle-size sulfide solid electrolyte.

[0078] Example 2

[0079] A method for preparing a sulfide solid electrolyte Li3PS4 includes the following steps:

[0080] S1. In a glove box filled with inert gas, weigh 0.23g Li2S and 0.37g P2S5 according to a preset molar ratio, transfer them to a degassing machine and grind them evenly to obtain Li3PS4 electrolyte precursor.

[0081] S2. In a glove box filled with inert gas, the Li3PS4 precursor was transferred to a container containing 10 mL of ethylenediamine and stirred at 55 °C for 24 h to obtain an ethylenediamine solution of Li3PS4.

[0082] S3. In a glove box filled with inert gas, transfer the Li3PS4 solution to a container containing 50mL of n-hexane, stir thoroughly, and obtain a Li3PS4 suspension.

[0083] S4. In a glove box filled with inert gas, the above Li3PS4 suspension is centrifuged to separate the Li3PS4 electrolyte from ethylenediamine / n-hexane, and a solid Li3PS4 electrolyte containing a small amount of solvent is obtained.

[0084] S5. In a glove box filled with inert gas, the Li3PS4 obtained above is transferred to a vacuum drying oven to remove the residual solvent and obtain amorphous Li3PS4 solid electrolyte.

[0085] S6. In a glove box filled with inert gas, the Li3PS4 electrolyte powder obtained in the previous step was transferred to a muffle furnace for heat treatment. It was calcined at 300℃ for 5 hours with a heating rate of 5℃ / min. After that, the sample was ground and sieved to obtain a high-purity small-particle-size sulfide solid electrolyte.

[0086] Example 3

[0087] A sulfide solid electrolyte Li 5.5 PS 4.5 Cl 1.5 The preparation method includes the following steps:

[0088] S1. In a glove box filled with inert gas, weigh 0.46g Li₂S, 0.56g P₂S₅, and 0.318g LiCl according to a preset molar ratio, transfer them to a degassing machine, and grind them evenly to obtain Li. 5.5 PS 4.5 Cl 1.5 Electrolyte precursors;

[0089] S2. In a glove box filled with inert gas, Li... 5.5 PS 4.5 Cl 1.5 The precursor was transferred to a container containing 10 mL of ethylenediamine and reacted at 55 °C for 24 h with stirring to obtain Li. 5.5 PS 4.5 Cl 1.5 ethylenediamine solution;

[0090] S3. In a glove box filled with inert gas, Li... 5.5 PS 4.5 Cl 1.5 The solution was transferred to a container containing 50 mL of n-hexane, and after thorough stirring, Li was obtained. 5.5 PS 4.5 Cl 1.5 Suspension;

[0091] S4. In a glove box filled with inert gas, the above-mentioned Li... 5.5 PS 4.5 Cl 1.5 The suspension was centrifuged to remove Li 5.5 PS 4.5 Cl 1.5 The electrolyte was separated from ethylenediamine / n-hexane to obtain Li containing a small amount of solvent. 5.5 PS 4.5 Cl 1.5 Solid electrolyte;

[0092] S5. In a glove box filled with inert gas, the Li obtained above is subjected to... 5.5 PS 4.5 Cl 1.5 The mixture was transferred to a vacuum drying oven to remove residual solvent, yielding amorphous Li. 5.5 PS 4.5 Cl 1.5 Electrolytes;

[0093] S6. In a glove box filled with inert gas, the Li obtained in the previous step is subjected to... 5.5 PS 4.5 Cl 1.5 The electrolyte powder was transferred to a muffle furnace for heat treatment, calcined at 550℃ for 10 hours with a heating rate of 5℃ / min. After that, the sample was ground and sieved to obtain a high-purity, small-particle-size sulfide solid electrolyte.

[0094] Example 4

[0095] A method for preparing a sulfide solid electrolyte Li6PS5Cl includes the following steps:

[0096] S1. In a glove box filled with inert gas, weigh 0.383g Li2S, 0.37g P2S5 and 0.141g LiCl according to the preset molar ratio, transfer them to a degassing machine and grind them evenly to obtain Li6PS5Cl electrolyte precursor.

[0097] S2. In a glove box filled with inert gas, the Li6PS5Cl precursor was transferred to a container containing 10 mL of a mixed solvent of ethylenediamine / 1,2-ethylenedithiol (volume ratio 1:1). The mixture was stirred at 55 °C for 24 h to obtain an ethylenediamine / 1,2-ethylenedithiol solution of Li6PS5Cl.

[0098] S3. In a glove box filled with inert gas, transfer the Li6PS5Cl solution to a container containing 50mL of n-hexane, and stir thoroughly to obtain a Li6PS5Cl suspension.

[0099] S4. In a glove box filled with inert gas, the above Li6PS5Cl suspension is centrifuged to separate the Li6PS5Cl electrolyte from ethylenediamine / 1,2-ethylenedithiol / n-hexane, and a solid Li6PS5Cl electrolyte containing a small amount of solvent is obtained.

[0100] S5. In a glove box filled with inert gas, the Li6PS5Cl obtained above is transferred to a vacuum drying oven to remove the residual solvent and obtain amorphous Li6PS5Cl electrolyte.

[0101] S6. In a glove box filled with inert gas, the Li6PS5Cl electrolyte powder obtained in the previous step was transferred to a muffle furnace for heat treatment. It was calcined at 550℃ for 10h with a heating rate of 5℃ / min. After that, the sample was ground and sieved to obtain a high-purity small-particle-size sulfide solid electrolyte.

[0102] Example 5

[0103] A method for preparing a sulfide solid electrolyte Li6PS5Cl includes the following steps:

[0104] S1. In a glove box filled with inert gas, weigh 0.383g Li2S, 0.37g P2S5 and 0.141g LiCl according to the preset molar ratio, transfer them to a degassing machine and grind them evenly to obtain Li6PS5Cl electrolyte precursor.

[0105] S2. In a glove box filled with inert gas, the Li6PS5Cl precursor was transferred to a container containing 10 mL of 1,2-ethylenedithiol and stirred at 55 °C for 24 h to obtain a 1,2-ethylenedithiol solution of Li6PS5Cl.

[0106] S3. In a glove box filled with inert gas, transfer the Li6PS5Cl solution to a container containing 50mL of ethyl acetate, stir thoroughly, and obtain a Li6PS5Cl suspension.

[0107] S4. In a glove box filled with inert gas, the above Li6PS5Cl suspension is centrifuged to separate the Li6PS5Cl electrolyte from 1,2-ethanedithiol / ethyl acetate, and a Li6PS5Cl solid electrolyte containing a small amount of solvent is obtained.

[0108] S5. In a glove box filled with inert gas, the Li6PS5Cl obtained above is transferred to a vacuum drying oven to remove the residual solvent and obtain amorphous Li6PS5Cl electrolyte.

[0109] S6. In a glove box filled with inert gas, the Li6PS5Cl electrolyte powder obtained in the previous step was transferred to a muffle furnace for heat treatment. It was calcined at 550℃ for 10h with a heating rate of 5℃ / min. After that, the sample was ground and sieved to obtain a high-purity small-particle-size sulfide solid electrolyte.

[0110] Example 6

[0111] A method for preparing a sulfide solid electrolyte Li6PS5Cl includes the following steps:

[0112] S1. In a glove box filled with inert gas, weigh 0.383g Li2S, 0.37g P2S5 and 0.141g LiCl according to the preset molar ratio, transfer them to a degassing machine and grind them evenly to obtain Li6PS5Cl electrolyte precursor.

[0113] S2. In a glove box filled with inert gas, the Li6PS5Cl precursor was transferred to a container containing 10 mL of a mixed solvent of ethylenediamine / 1,2-ethylenedithiol (volume ratio 1:1). The mixture was stirred at 55 °C for 24 h to obtain an ethylenediamine / 1,2-ethylenedithiol solution of Li6PS5Cl.

[0114] S3. In a glove box filled with inert gas, transfer the Li6PS5Cl solution to a container containing 50 mL of n-hexane / ethyl acetate mixed solvent (volume ratio 1:1), and stir thoroughly to obtain a Li6PS5Cl suspension.

[0115] S4. In a glove box filled with inert gas, the above Li6PS5Cl suspension is centrifuged to separate the Li6PS5Cl electrolyte from ethylenediamine / 1,2-ethylenedithiol / n-hexane / ethyl acetate, and a solid Li6PS5Cl electrolyte containing a small amount of solvent is obtained.

[0116] S5. In a glove box filled with inert gas, the Li6PS5Cl obtained above is transferred to a vacuum drying oven to remove the residual solvent and obtain amorphous Li6PS5Cl electrolyte.

[0117] S6. In a glove box filled with inert gas, the Li6PS5Cl electrolyte powder obtained in the previous step was transferred to a muffle furnace for heat treatment. It was calcined at 550℃ for 10h with a heating rate of 5℃ / min. After that, the sample was ground and sieved to obtain a high-purity small-particle-size sulfide solid electrolyte.

[0118] Table 1 shows the particle size test results of the sulfide solid electrolytes prepared in Examples 1 to 6 and the comparative examples of the present invention.

[0119] Table 2 shows the ionic conductivity data of the sulfide solid electrolytes prepared in Examples 1-6 and the comparative examples.

[0120] Table 1

[0121]

[0122] Table 2

[0123]

[0124] Example 7

[0125] The Li6PS5Cl electrolyte powder prepared in Example 1 was sieved through a 500-mesh sieve, and then a slurry for preparing a solid electrolyte membrane was prepared. SEBS was used as the binder, p-xylene as the solvent, and the slurry solid content was 46.7%. The specific experimental steps are as follows:

[0126] The required masses of electrolyte powder, solvent, and binder solution were calculated based on the determined mass ratio and solid content of the components. Then, 1.96 g of electrolyte powder, 1.523 g of p-xylene, and 0.8 g of SEBS solution were weighed and transferred to a 30 mL flat mixing container. The container was tightened and sealed with a sealing film, then placed in a degassing machine for degassing. After stirring, the mixture was poured onto a PET substrate and coated using an automatic coating machine to a thickness of 300 μm. After drying and cold pressing, the resulting sulfide solid electrolyte membrane was obtained for battery assembly. The same steps were applied to the sulfide solid electrolyte powders prepared in Examples 2-6 and the comparative example, as well as the purchased large-particle-size sulfide solid electrolyte powder (competitor 1, particle size D50 < 5 μm, conductivity 2.34 mS / cm), to obtain sulfide solid electrolyte membranes.

[0127] Table 3 shows the porosity data of the sulfide solid electrolyte membrane prepared in Example 7:

[0128] Table 3

[0129]

[0130]

[0131] Example 8

[0132] The Li6PS5Cl electrolyte powder prepared in Example 1 was sieved through a 500-mesh sieve, and then a composite cathode was prepared. The cathode used was NCM811, the binder was PIB, the solvent was p-xylene, the conductive carbon was Super C65, and the slurry solid content was 70%. The proportions of each component in the composite cathode were NCM811:Li6PS5Cl:Super C65:PIB = 80:16.4:1.6:2. The specific experimental steps are as follows:

[0133] Based on the determined mass ratio and solid content of the components, the required masses of positive electrode, electrolyte powder, solvent, and binder solution were calculated. Then, 2.508g of NCM811, 0.514g of electrolyte powder, 0.05g of Super C65, 0.8g of PIB binder solution, and 0.635g of p-xylene were weighed and transferred to a 30mL flat mixing container. The container was tightened and sealed with a sealing film, and then placed in a degassing machine for degassing. After stirring, the mixture was poured onto an aluminum foil substrate and coated using an automatic coating machine. It was then dried and cold-pressed to obtain the composite positive electrode sheet required for battery assembly. Simultaneously, the above operations were repeated using the sulfide solid electrolyte powder obtained in Examples 2-4 and purchased large-particle-size sulfide solid electrolyte powder to prepare the corresponding composite positive electrode.

[0134] Example 9

[0135] Using lithium metal as the negative electrode, the solid electrolyte membrane prepared in Example 7 and the composite positive electrode sheet prepared in Example 8 (including Examples 1-4 of the present invention and Competitor 1) were cut into appropriate sizes respectively. Then, the lithium metal negative electrode, electrolyte membrane and composite positive electrode were assembled into a battery in the mold battery in the order of lithium metal negative electrode, electrolyte membrane and composite positive electrode. During the test, it needs to be placed in a 55°C oven and a certain pressure is applied to the battery to make it tightly bonded. Then, a charge and discharge test is performed on it with a rate of 0.1C.

[0136] Table 4 shows the first discharge and cycle data of the assembled battery in Example 9:

[0137] Table 4

[0138]

[0139]

[0140] Comparative Example

[0141] A method for preparing a sulfide solid electrolyte Li6PS5Cl includes the following steps:

[0142] S1. In a glove box filled with inert gas, weigh 0.383g Li2S, 0.37g P2S5 and 0.141g LiCl according to the preset molar ratio, transfer them to a degassing machine and grind them evenly to obtain Li6PS5Cl electrolyte precursor.

[0143] S2. In a glove box filled with inert gas, the Li6PS5Cl precursor was transferred to a container containing 10 mL of anhydrous ethanol and stirred at 55 °C for 24 h to obtain an ethanol solution of Li6PS5Cl.

[0144] S3. In a glove box filled with inert gas, transfer the Li6PS5Cl solution to a container containing 50mL of anisole, stir thoroughly, and obtain a Li6PS5Cl suspension.

[0145] S4. In a glove box filled with inert gas, the above Li6PS5Cl suspension is centrifuged to separate the Li6PS5Cl electrolyte from ethanol / anisole, and a Li6PS5Cl solid electrolyte containing a small amount of solvent is obtained.

[0146] S5. In a glove box filled with inert gas, the Li6PS5Cl obtained above is transferred to a vacuum drying oven to remove the residual solvent and obtain amorphous Li6PS5Cl electrolyte.

[0147] S6. In a glove box filled with inert gas, the Li6PS5Cl electrolyte powder obtained in the previous step was transferred to a muffle furnace for heat treatment. It was calcined at 550℃ for 10h with a heating rate of 5℃ / min. After that, the sample was ground and sieved to obtain a sulfide solid electrolyte.

[0148] In a glove box filled with inert gas, the Li6PS5Cl electrolyte powder obtained in the previous step was transferred to a muffle furnace for heat treatment, calcined at 550℃ for 10 h at a heating rate of 5℃ / min. Afterwards, the sample was ground and sieved to obtain the sulfide solid electrolyte. The XRD pattern of the prepared sulfide solid electrolyte is shown below. Figure 7 As shown, in addition to the diffraction peaks attributed to Li6PS5Cl, there are also obvious diffraction peaks for Li3PO4, Li2S, and LiCl, indicating that the hydroxyl groups in ethanol react with the PS4 in the sulfide solid electrolyte. 3- Group reactions lead to a decrease in the purity of sulfide solid electrolytes.

[0149] As can be seen from the above embodiments, the present invention provides a method for preparing a small-particle-size sulfide solid electrolyte, comprising the following steps: mixing a sulfide solid electrolyte precursor and a first solvent under an inert atmosphere and reacting to obtain a sulfide solid electrolyte solution; the first solvent is selected from at least one of ethylenediamine, hydrazine, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol; mixing the sulfide solid electrolyte solution with a second solvent and stirring to precipitate the sulfide solid electrolyte to obtain a sulfide solid electrolyte suspension; the second solvent is selected from at least one of tetrahydrofuran, n-hexane, cyclohexane, n-heptane, ethyl acetate, diethylene glycol dimethyl ether, ethyl propionate, acetone, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,2-ethylenedithiol; separating the solvent from the sulfide solid electrolyte suspension and drying to obtain an amorphous sulfide solid electrolyte; and heat-treating the amorphous sulfide solid electrolyte to obtain a small-particle-size sulfide solid electrolyte. This method involves synthesizing a sulfide solid electrolyte in a specific type of first solvent, followed by direct transfer to a specific type of second solvent. The small-particle-size sulfide solid electrolyte precipitates out, allowing for direct solvent separation without a crystallization process, significantly reducing time and costs. This method is simple and efficient. The sulfide solid electrolyte prepared by this method has high purity and high ionic conductivity. When used in the positive or negative electrode, the small-particle-size sulfide solid electrolyte enables the battery to exhibit high discharge capacity, excellent cycle performance, rate performance, and limiting current density.

[0150] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a small-particle-size sulfide solid electrolyte, comprising the following steps: Under an inert atmosphere, the sulfide solid electrolyte precursor and the first solvent are mixed and reacted to obtain a sulfide solid electrolyte solution; the first solvent is selected from at least one of ethylenediamine and 1,2-ethylenedithiol. The sulfide solid electrolyte solution is mixed with the second solvent, and the mixture is stirred to precipitate the sulfide solid electrolyte, resulting in a sulfide solid electrolyte suspension; the second solvent is selected from at least one of n-hexane and ethyl acetate. The solvent in the sulfide solid electrolyte suspension was separated and dried to obtain an amorphous sulfide solid electrolyte. The amorphous sulfide solid electrolyte was heat-treated to obtain a small-particle-size sulfide solid electrolyte. The sulfide solid electrolyte precursor is prepared by uniformly grinding the raw materials required for the target small-particle-size sulfide solid electrolyte; the raw materials required for the target small-particle-size sulfide solid electrolyte include two or more of Li, S8, Li2S, Li2Se, SiS2, P2S5, P2S3, LiCl, LiI, LiBr, GeS2, and SnS. The particle size D50 of the small-particle-size sulfide solid electrolyte is less than 1 μm.

2. The preparation method according to claim 1, characterized in that, The small-particle-size sulfide solid electrolyte is selected from Li3PS4; Li 7-x PS 6-x Y x 0 < x ≤ 1, Y is selected from Cl - ,Br - I - Li7P3S 11 Li7PS6; Li2GeS3; Li2SiS3; Li2SnS3; Li 10 GeP2S 12 and Li 10 SnP2S 12 One or more of them.

3. The preparation method according to claim 1, characterized in that, The heat treatment temperature is 100~700℃, the heat treatment time is 1~24 h, and the heat treatment heating rate is 0.1~10℃ / min.

4. The preparation method according to claim 1, characterized in that, The reaction is carried out under stirring conditions; the stirring rate is 200~1500 rpm; the reaction temperature is 20~80℃; and the reaction time is 0.5~24 h.

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