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

Abstract

The invention provides a sulfide solid electrolyte, a preparation method thereof and an all-solid-state battery. The sulfide solid electrolyte provided by the invention comprises an inner core and a shell layer coating the surface of the inner core, the material of the inner core is argyrodite type electrolyte Li6PS5Cl, and the material of the shell layer is Li10SnP2S12. The sulfide solid electrolyte provided by the invention adopts argyrodite type electrolyte Li6PS5Cl as a core material and adopts Li10SnP2S12 as a shell material, so that the lithium ion conductivity is remarkably improved, and in a dew point environment of-10 DEG C, the H2S gas release amount is remarkably reduced, and the hydrolysis reaction starting time is remarkably delayed. Meanwhile, excellent cycling stability and interface stability are shown, and good performance can be kept even under the ultralow external pressure (0.5 MPa).

Description

TECHNICAL FIELD

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

[0002] With the increasing demand for high energy density and high safety batteries, full solid-state batteries as a technology that can replace traditional lithium-ion batteries have attracted widespread attention. Sulfide solid electrolytes are considered to be an ideal medium for lithium ion transmission in full solid-state batteries due to their high ionic conductivity and good mechanical flexibility. However, sulfides have poor stability in humid environments and are prone to react with moisture. According to the hard-soft acid-base theory, the P-S bond composed of hard acid P 5+ and soft base S 2- is easy to decompose to generate toxic H2S gas and cause a decrease in ionic conductivity. This limits the application of sulfide electrolytes in actual batteries.

[0003] In order to improve the air stability of sulfide electrolytes, researchers have tried various methods, including doping and coating. For example, doping: by doping, Sn 4+ , Se 4+ ions replace P 5+ ions in the lattice, which can improve the chemical stability of the electrolyte, but some Sn 4+ doping strategies, although they can improve stability, may result in low lithium ion conductivity at room temperature (about 0.01 mS / cm) in full solid-state batteries, limiting their practical application in full solid-state batteries; after Se 4+ doping, the amount of H2S gas released when the sulfide electrolyte is exposed to a humid environment is significantly reduced, and it has high ionic conductivity (5.4 mS / cm) and low activation energy (0.287 eV), but during the doping process, impurities are also likely to be formed, and the electrochemical window is poor, and at high current density, the growth of lithium dendrites can still penetrate the electrolyte, leading to short circuit of the battery. For example, coating: using NASICON-type oxide solid electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) to coat the sulfide electrolyte sheet, which improves the environmental stability of the sulfide electrolyte and the interface problem with the electrode while ensuring the conductivity, but there may be defects in mechanical strength and flexibility, and it has high interface impedance; using polymers (polytetrafluoroethylene, polyethylene oxide, polyethylene, etc.) to coat the sulfide composite solid-state electrolyte coated with sulfide, which effectively improves the lithium ion conductivity and cycle stability, but the thermal stability of the polymer is poor, and the coating layer will age or degrade during long-term use, leading to a decrease in its protective performance.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The main purpose of the present application is to provide a sulfide solid electrolyte, a preparation method thereof and a full solid-state battery, so as to solve the problem that the modification of sulfide electrolyte by ion doping or coating cannot simultaneously have excellent conductivity, mechanical ductility and air stability in the prior art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a sulfide solid electrolyte is provided, which comprises a core and a shell layer coated on the surface of the core, the material of the core is argyrodite-type electrolyte Li6PS5Cl, and the material of the shell layer is Li 10 SnP2S 12 .

[0007] Further, the Dv50 particle size of the sulfide solid electrolyte is 5-12 μm, and the average thickness of the shell layer is 0.5-2 μm.

[0008] In order to achieve the above-mentioned purpose, according to another aspect of the present application, a preparation method of a sulfide solid electrolyte is provided, which comprises: providing Li6PS5Cl, mixing Li6PS5Cl and SnS2 uniformly, and then sequentially performing heat treatment and solvent cleaning to obtain a sulfide solid electrolyte with core-shell structure; wherein the material of the core is argyrodite-type electrolyte Li6PS5Cl, and the material of the shell layer is Li 10 SnP2S 12 .

[0009] Further, the temperature of the heat treatment is 400-500℃, and the time of the heat treatment is 6-12h.

[0010] Further, the solvent cleaning comprises: soaking the heat treatment product in an organic solvent, solid-liquid separation and drying to obtain the sulfide solid electrolyte.

[0011] Further, the organic solvent is selected from at least one of anhydrous tetrahydrofuran, acetonitrile, acetone and anisole.

[0012] Further, the solid-liquid separation mode comprises at least one of filtration and centrifugation. Further, the drying is vacuum drying, the temperature of the vacuum drying is 60-150℃, and the time of the vacuum drying is 4-10h.

[0013] Further, the mass ratio of Li6PS5Cl to SnS2 is 100:(5-15), preferably 100:(8-12).

[0014] Further, the preparation method of Li6PS5Cl comprises: mixing Li2S, P2S5 and LiCl according to stoichiometric ratio, and then performing first sintering treatment to obtain Li6PS5Cl.

[0015] Further, the preparation method of SnS2 comprises: mixing SnCl2·2H2O and N2H4CS according to stoichiometric ratio, and then performing second sintering treatment to obtain SnS2.

[0016] Further, the temperature of the second sintering treatment is 250-350℃, and the time of the second sintering treatment is 1-4h.

[0017] According to the third aspect of the present application, a full solid-state battery is also provided, which comprises the sulfide solid electrolyte provided by the first aspect or obtained by the preparation method provided by the second aspect.

[0018] By applying the technical solution of the present application, the sulfide solid electrolyte provided by the present application adopts sulfosalt-type electrolyte Li6PS5Cl as the core material, adopts Li 10 SnP2S 12 As the shell material, not only the lithium ion conductivity is significantly improved, but also the H2S gas release amount is significantly reduced and the hydrolysis reaction starting time is significantly delayed in the dew point environment of-10℃. Meanwhile, the sulfide solid electrolyte provided by the present application also exhibits excellent cycle stability and interface stability, and can maintain good electrochemical performance even under ultra-low external pressure (0.5MPa). BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings accompanying the specification of the present application serve to provide further understanding of the present application, and the schematic embodiments of the present application and the description thereof serve to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0020] Figure 1 Scanning electron microscope (SEM) image of the solid sulfide electrolyte provided for Example 1;

[0021] Figure 2 Transmission electron microscope (TEM) image of the solid sulfide electrolyte provided for Example 1;

[0022] Figure 3 XRD spectrum of the product obtained in each step of Example 1;

[0023] Figure 4 Lithium ion conductivity test chart of the solid sulfide electrolyte provided for Example 1 and Comparative Examples 1-2 exposed for 0h, 3h and 6h respectively in the dew point environment of-40℃;

[0024] Figure 5The test chart of H2S generation amount of the solid-state sulfide electrolyte provided for the examples and comparative examples 1-2 exposed to different time in a closed environment with dew point of-10℃;

[0025] Figure 6 The test chart of discharge capacity of the solid-state sulfide electrolyte provided for the examples 1 and comparative example 1 after different cycles under 0.5 MPa ultra-low external pressure in the soft package full solid-state battery. DETAILED DESCRIPTION

[0026] It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict. The present application will be described in detail below with reference to the examples.

[0027] As analyzed in the background art of the present application, the sulfide electrolyte has poor stability in a humid environment, and the modification of the sulfide electrolyte by element doping, oxide or polymer coating cannot simultaneously have excellent electrical conductivity, mechanical ductility and air stability. In order to solve this problem, the present application provides a sulfide solid-state electrolyte and a preparation method thereof and a full solid-state battery.

[0028] In a first typical embodiment of the present application, a sulfide solid-state electrolyte is provided, which comprises a core and a shell layer coated on the surface of the core, the material of the core is a thioargyrite-type electrolyte Li6PS5Cl, and the material of the shell layer is Li 10 SnP2S 12 .

[0029] The sulfide solid-state electrolyte provided by the present application uses a thioargyrite-type electrolyte Li6PS5Cl as the core material, and uses Li 10 SnP2S 12 as the shell layer material, which not only significantly improves the lithium ion conductivity, but also significantly reduces the release amount of toxic gas H2S in a dew point environment of-10℃, and significantly delays the start time of hydrolysis reaction. At the same time, the sulfide solid-state electrolyte provided by the present application also exhibits excellent cycle stability and interface stability, and can maintain good electrochemical performance even under ultra-low external pressure (0.5 MPa).

[0030] In some embodiments of the present application, the Dv50 particle size of the sulfide solid-state electrolyte is 5-12 μm, and the average thickness of the shell layer is 0.5-2 μm, so that it is not only more beneficial to uniform dispersion in a full solid-state battery, but also has more excellent stability. Specifically, the Dv50 particle size of the sulfide solid-state electrolyte can be 5 μm, 6 μm, 7 μm, 8 μm, 8.5 μm, 10 μm, 11 μm, 12 μm, or a range value formed by any two of the above values; and the average thickness of the shell layer can be 0.5 μm, 0.8 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.8 μm, 2.0 μm, or a range value formed by any two of the above values.

[0031] In another typical embodiment of the present application, a preparation method of a sulfide solid-state electrolyte is provided, which comprises: providing a argyrodite-type electrolyte Li6PS5Cl, uniformly mixing the argyrodite-type electrolyte Li6PS5Cl and SnS2, and then sequentially performing heat treatment and solvent cleaning to obtain a sulfide solid-state electrolyte with a core-shell structure; wherein the material of the inner core is the argyrodite-type electrolyte Li6PS5Cl, and the material of the shell layer is Li 10 SnP2S 12 .

[0032] The preparation method of the sulfide solid-state electrolyte provided in the present application uniformly mixes the argyrodite-type electrolyte Li6PS5Cl and SnS2, and then performs heat treatment, so that Li6PS5Cl and SnS2 react, and then Li 10 SnP2S 12 is generated in situ on the outer surface of Li6PS5Cl. At the same time, LiCl is generated in the reaction process, and then LiCl is removed by subsequent solvent cleaning, so as to obtain a sulfide solid-state electrolyte with a core-shell structure. The preparation method of the sulfide solid-state electrolyte is simple in process, convenient in operation, easy to realize large-scale production, and further reduces the preparation cost.

[0033] In some embodiments of the present application, in order to further improve the in-situ generation efficiency of the shell layer Li 10 SnP2S 12 , the heat treatment temperature is preferably 400-500 ℃, and the heat treatment time is 6-12 h. Specifically, the heat treatment temperature can be 400 ℃, 420 ℃, 450 ℃, 480 ℃, 500 ℃, or a range value formed by any two of the above values; and the heat treatment time can be 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, or a range value formed by any two of the above values.

[0034] In some embodiments of the present application, the solvent cleaning comprises: soaking the heat-treated product in an organic solvent, solid-liquid separation and drying to obtain the sulfide solid electrolyte. By soaking the heat-treated product in an organic solvent, the LiCl generated during the heat treatment and remaining on the surface of the heat-treated product is dissolved by the organic solvent, and then removed by solid-liquid separation, and after drying, the sulfide solid electrolyte with a core-shell structure can be obtained.

[0035] In some embodiments of the present application, the above-mentioned organic solvent is not specifically limited, and any organic solvent capable of dissolving LiCl can be used, including but not limited to any one or a mixture of two or more of anhydrous tetrahydrofuran, acetonitrile, acetone, anisole.

[0036] In some embodiments of the present application, the solid-liquid separation method is not limited, including but not limited to any one or a combination of two or more of filtration, centrifugation, etc., and the filtration is, for example, suction filtration.

[0037] In some embodiments of the present application, the drying is vacuum drying, the temperature of the vacuum drying is 60-150℃, and the time of the vacuum drying is 4-10h. Specifically, the temperature of the vacuum drying can be 60℃, 90℃, 120℃, 150℃, or a range value formed by any two numerical values, and the time of the vacuum drying can be 4h, 6h, 8h, 10h, or a range value formed by any two numerical values.

[0038] In some embodiments of the present application, the mass ratio of Li6PS5Cl to SnS2 is 100:(5-15), so as to further improve the structural stability of the sulfide solid electrolyte, and especially when the mass ratio of Li6PS5Cl to SnS2 is 100:(8-12), it is more beneficial to improve the ionic conductivity, cycle stability and interface stability while improving the structural stability of the sulfide solid electrolyte. Specifically, the mass ratio of Li6PS5Cl to SnS2 can be 100:5, 100:8, 100:10, 100:12, 100:15, or a range value formed by any two numerical values.

[0039] In some embodiments of the present application, the preparation method of Li6PS5Cl comprises: uniformly mixing Li2S, P2S5 and LiCl according to the stoichiometric ratio, and then performing first sintering treatment to obtain Li6PS5Cl, so as to further improve the preparation efficiency of Li6PS5Cl.

[0040] In some embodiments, the first sintering treatment is performed at a temperature of 450-550℃ for 5-8h to further improve the processing efficiency of Li6PS5Cl. Specifically, the first sintering treatment can be performed at a temperature of 450℃, 480℃, 500℃, 520℃, 550℃ or any range between any two of the values; and / or the first sintering treatment can be performed for a time of 5h, 5.5h, 6h, 7h, 8h or any range between any two of the values.

[0041] In some embodiments, Li2S, P2S5 and LiCl are mixed in stoichiometric ratio to obtain a raw material mixture, and the raw material mixture is sintered by heating from room temperature to a first sintering treatment temperature. To further improve the uniformity of the core material Li6PS5Cl, the heating rate is preferably 2-5℃ / min. Specifically, the heating rate can be 2℃ / min, 2.5℃ / min, 3℃ / min, 4℃ / min, 5℃ / min or any range between any two of the values.

[0042] In some embodiments of the present application, Li6PS5Cl can also be obtained by commercial purchase.

[0043] In some embodiments of the present application, the method for preparing SnS2comprises mixing SnCl2·2H2O and N2H4CS in stoichiometric ratio and performing a second sintering treatment to obtain SnS2, to further improve the preparation efficiency of SnS2.

[0044] In some embodiments, the second sintering treatment is performed at a temperature of 250-350℃ for 1-4h to further improve the efficiency of the second sintering treatment. Specifically, the second sintering treatment can be performed at a temperature of 250℃, 280℃, 300℃, 320℃, 350℃ or any range between any two of the values; and / or the second sintering treatment can be performed for a time of 1h, 1.5h, 2h, 3h, 4h or any range between any two of the values.

[0045] In some embodiments of the present application, SnS2can also be obtained by commercial purchase.

[0046] In a third typical embodiment of the present application, a full solid-state battery is also provided, which comprises the sulfide solid-state electrolyte provided in the first typical embodiment or prepared according to the preparation method provided in the second typical embodiment.

[0047] The all-solid-state battery provided in the application uses a sulfide solid electrolyte with a core-shell structure as an electrolyte, which not only significantly improves the lithium ion conductivity, but also significantly reduces the gas release amount and significantly delays the start-up time of the hydrolysis reaction in a dew point environment of-10℃. At the same time, the all-solid-state battery provided in the application also exhibits excellent cycle stability and interface stability, and can maintain good performance even under ultra-low external pressure (0.5 MPa).

[0048] The beneficial effects of the application will be further illustrated below in combination with examples and comparative examples.

[0049] Example 1

[0050] The present embodiment provides a sulfide electrolyte with a core-shell structure, which is prepared according to the following steps:

[0051] (1) The raw materials Li2S (99.98% purity), P2S5 (99% purity) and LiCl are mixed in a stoichiometric ratio, and a ball mill is used to mill at a speed of 500 rpm under the protection of inert gas (argon) for 15 h to obtain a raw material mixture; the raw material mixture is heated to 500℃ at a rate of 3℃ / min under a protective atmosphere (argon or nitrogen), and kept for 6 h to obtain a heat-treated material, which is ground and sieved through a 200 mesh sieve, and then dried at 125℃ for 4 h to obtain an inner core material Li6PS5Cl;

[0052] (2) SnCl2·2H2O (purity 98%) and N2H4CS (purity 99%) are mixed in a molar ratio of 1:3.5 and sintered at 300℃ for 2 hours under an argon atmosphere to obtain SnS2;

[0053] (3) SnS2 and Li6PS5Cl are uniformly mixed in a mass ratio of 10:100 and then annealed at 450℃ for 8 h to obtain a heat-treated product;

[0054] (4) The heat-treated product is soaked in anhydrous tetrahydrofuran (purity ≥99.99%) at room temperature for 6 h, and then filtered to remove LiCl, and then vacuum dried at 100℃ for 8 h to obtain a solid-state sulfide electrolyte with a core-shell structure.

[0055] Example 2

[0056] The difference between the present embodiment and Example 1 is that in step (3), the mass ratio of SnS2 to Li6PS5Cl is 8:100.

[0057] Example 3

[0058] The difference between the present embodiment and Example 1 is that in step (3), the mass ratio of SnS2 to Li6PS5Cl is 12:100.

[0059] Example 4

[0060] The difference between this example and Example 1 is that in step (3), the mass ratio of SnS2 and Li6PS5Cl is 5:100.

[0061] Example 5

[0062] The difference between this example and Example 1 is that in step (3), the mass ratio of SnS2 and Li6PS5Cl is 15:100.

[0063] Example 6

[0064] The difference between this example and Example 1 is that in step (3), the mass ratio of SnS2 and Li6PS5Cl is 3:100.

[0065] Example 7

[0066] The difference between this example and Example 1 is that in step (3), the mass ratio of SnS2 and Li6PS5Cl is 20:100.

[0067] Example 8

[0068] The difference between this example and Example 1 is that in step (3), the temperature of heat treatment is 400℃, and the time of heat treatment is 12h.

[0069] Example 9

[0070] The difference between this example and Example 1 is that in step (3), the temperature of heat treatment is 500℃, and the time of heat treatment is 6h.

[0071] Example 10

[0072] The difference between this example and Example 1 is that in step (3), the temperature of heat treatment is 300℃, and the time of heat treatment is 15h.

[0073] Example 11

[0074] The difference between this example and Example 1 is that in step (3), the temperature of heat treatment is 600℃, and the time of heat treatment is 6h.

[0075] Comparative Example 1

[0076] This comparative example provides a solid-state sulfide electrolyte Li6PS5Cl, which is the core material Li6PS5Cl prepared in step (1) in Example 1.

[0077] Comparative Example 2

[0078] The comparative example 1 provides a solid-state sulfide electrolyte Li 10 SnP2S 12 which is prepared according to the following steps:

[0079] (1) SnCl2·2H2O (purity 98%) and N2H4CS (purity 99%) are mixed according to a molar ratio of 1:3.5, sintered at 300°C for 2 hours under an argon atmosphere, to obtain SnS2;

[0080] (2) Li2S (purity 99.98%), P2P5 (99% purity) and SnS2 are mixed according to a stoichiometric ratio, ball-milled at a speed of 500 rpm for 20 hours at room temperature to obtain a ball-milled mixed powder, and the ball-milled mixed powder is sintered at 600°C for 8 hours under an argon atmosphere to obtain Li 10 SnP2S 12 .

[0081] Comparative example 3

[0082] The comparative example 1 provides a solid-state sulfide electrolyte which is prepared according to the following steps:

[0083] (1) The core material Li6PS5Cl (its preparation method is the same as that of example 1) is provided, and the core material Li6PS5Cl is uniformly mixed with SeS2 according to a mass ratio of 100:10, and annealed at 450°C for 8 hours to obtain a heat-treated product;

[0084] (2) The heat-treated product is soaked in anhydrous tetrahydrofuran at room temperature for 6 hours, filtered to remove LiCl, and then vacuum dried at 100°C for 8 hours to obtain a solid-state sulfide electrolyte with a core-shell structure.

[0085] Comparative example 4

[0086] The comparative example 1 provides a solid-state sulfide electrolyte which is prepared according to the following steps:

[0087] (1) The core material Li6PS5Cl (its preparation method is the same as that of example 1) is provided, and the core material Li6PS5Cl is uniformly mixed with GeS2 according to a mass ratio of 100:10, and annealed at 450°C for 8 hours to obtain a heat-treated product;

[0088] (2) The heat-treated product is soaked in anhydrous tetrahydrofuran at room temperature for 6 hours, filtered to remove LiCl, and then vacuum dried at 100°C for 8 hours to obtain a solid-state sulfide electrolyte with a core-shell structure.

[0089] Comparative example 5

[0090] The difference between the comparative example 1 and example 1 is that step (4) is not performed, and the heat-treated product is directly used as a sulfide solid-state electrolyte.

[0091] Experimental Example 1

[0092] The particle size and shell thickness of the solid sulfide electrolytes provided in the examples and comparative examples were measured, and the results are shown in Table 1 below.

[0093] Among them, (1) the test method for the particle size of solid sulfide electrolyte Dv50 is as follows: wet particle size test of electrolyte sample is carried out in accordance with the standard GB / T 19077-2016 "Particle Size Analysis by Laser Diffraction". Note that the weighing of sample, dispersion of organic solvent and test process must be carried out in a dry room environment with dew point ≤ -40℃;

[0094] (2) The test method for the average thickness of the solid sulfide electrolyte shell is as follows: Refer to standards GB / T 45114-2024 "Nanotechnology - Transmission Electron Microscopy for Measurement of Nanoparticle Size and Shape Distribution" and GB / T 18907-2013 "Microbeam Analysis - Selected Area Electron Diffraction Analysis Method for Transmission Electron Microscopy" to test the thickness of the solid sulfide electrolyte shell. It is important to use a vacuum transfer box or sample introduction device to ensure that the sample does not come into contact with air during transport and testing.

[0095] Table 1

[0096]

[0097] Note: Since the coating layer in Comparative Example 5 contains LiCl, the thickness was not measured.

[0098] Figure 1 Scanning electron microscope (SEM) image of the solid sulfide electrolyte provided in Example 1; Figure 2 Transmission electron microscopy (TEM) image of the solid sulfide electrolyte provided in Example 1; from Figure 1 and Figure 2 It can be seen that the solid sulfide electrolyte provided in Example 1 has a distinct core-shell structure.

[0099] Figure 3 The XRD patterns of the products obtained in each step of Example 1 are shown below. "LPSC" refers to the core material Li6PS5Cl obtained in step (1); "LPSC@LPSC before cleaning" refers to the heat-treated product obtained in step (3); and "LPSC@LPSC after cleaning" refers to the XRD pattern with a core-shell structure obtained in step (4). Figure 3 It can be seen that the XRD patterns of both "LPSC@LPSC before cleaning" and "LPSC@LPSC after cleaning" correspond well with the LPSC base sample. However, there is a LiCl impurity phase in "LPSC@LPSC before cleaning", which is removed after solvent cleaning.

[0100] Test Example 2

[0101] The solid-state sulfide electrolytes provided by the examples and comparative examples were subjected to lithium ion conductivity, air stability and electrochemical tests, respectively, and the results are shown in Table 2 below.

[0102] Among them, (1) the test method of ionic conductivity is: 0.2 g of the solid-state sulfide electrolyte provided by the examples and comparative examples is weighed at 25°C and -40°C dew point environment, respectively, and is pressed into a tablet in a mold to form a round tablet with a diameter of 10 mm, then the sample is exposed for 0 h, 3 h and 6 h, respectively, and electrochemical impedance (EIS) test is carried out, and the bulk impedance and grain boundary impedance are obtained after data fitting, and the ionic conductivity is calculated according to the following formula (1):

[0103] …………………………………………(1)

[0104] In the formula:

[0105] σ —— ionic conductivity, unit: siemens per centimeter (S / cm);

[0106] L —— sample thickness, unit: centimeter (cm);

[0107] π —— 3.14;

[0108] D —— sample bottom diameter, unit: centimeter (cm);

[0109] R1 —— fitted sample bulk impedance, unit: ohm (Ω);

[0110] R2 —— fitted sample grain boundary impedance, unit: ohm (Ω).

[0111] (2) The test method of air stability is: 2 g of the solid-state sulfide electrolyte provided by the examples and comparative examples is weighed respectively, and is laid and exposed in a closed environment with a dew point of -10°C, and the gas release amount (80 min) and the start time of hydrogen sulfide gas release are measured by a handheld H2S gas detector.

[0112] (3) The test method of electrochemical performance is: NCM811 is used as the positive electrode, graphite is used as the negative electrode, and the solid-state sulfide electrolyte provided by the examples and comparative examples is used as the solid-state electrolyte, respectively, to assemble 2 2 (cm) soft package full solid-state battery, and the battery capacity of the soft package full solid-state battery is tested. Then the soft package full solid-state battery is tested under 0.5 MPa ultra-low external pressure, and the battery capacity after 30 cycles is tested, and the capacity retention rate is calculated.

[0113] Table 2

[0114]

[0115] Figure 4 The lithium-ion conductivity test graphs for the solid sulfide electrolytes provided in Example 1 and Comparative Examples 1-2 after exposure at a dew point of -40°C for 0 h, 3 h, and 6 h, respectively; where "LPSC" refers to the core material Li6PS5Cl provided in Comparative Example 1; and "LSPS" refers to the shell material Li provided in Comparative Example 2. 10 SnP2S12; "LSPS@LPSC" refers to the core-shell structured solid sulfide electrolyte provided in Example 1. From Figure 4 It can be seen that after 0h exposure, the lithium-ion conductivity of LSPS is 6.08 mS / cm, and the ionic conductivity of the LSPS@LPSC core-shell electrolyte is 4.53 mS / cm, both higher than that of LPSC (3.86 mS / cm). After 3h and 6h exposure, the ionic conductivity of LPSC drops sharply by more than two orders of magnitude, while the ionic conductivity of LSPS and LSPS@LPSC decreases steadily with a lower magnitude. After 6h exposure, the ionic conductivity of LSPS@LPSC is approximately 100 times that of LPSC.

[0116] Figure 5 The graph shows the H2S generation of the solid sulfide electrolytes provided in Example 1 and Comparative Examples 1-2 after exposure to a closed environment at a dew point of -10°C for different times; where "LPSC" refers to the core material Li6PS5Cl provided in Comparative Example 1; and "LSPS" refers to the shell material Li provided in Comparative Example 2. 10 SnP2S 12 "LSPS@LPSC" refers to the solid sulfide electrolyte with a core-shell structure provided in Example 1. From Figure 5 It can be seen that after 80 minutes of exposure, the hydrogen sulfide gas produced by LSPS@LPSC was 6 ppm, which is much lower than the 45 ppm produced by LPSC. Moreover, compared with LPSC, the hydrogen sulfide gas release start time of LSPS@LPSC was delayed by 10 minutes.

[0117] Figure 6 The graph shows the discharge capacity test results of the pouch-type all-solid-state batteries prepared using the solid sulfide electrolytes provided in Example 1 and Comparative Example 1, after different number of cycles under an ultra-low external pressure of 0.5 MPa; where "LPSC" refers to the core material Li6PS5Cl provided in Comparative Example 1; and "LSPS@LPSC" refers to the solid sulfide electrolyte with a core-shell structure provided in Example 1. Figure 6 It can be seen that under an ultra-low external pressure of 0.5 MPa, the battery capacity retention rate of LSPS@LPSC reaches 95.3%, which is significantly better than that of LPSC (85.2%).

[0118] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects:

[0119] The sulfide solid electrolyte provided by the present application adopts sulfide solid electrolyte Li6PS5Cl as the core material, adopts Li 10 SnP2S 12 As a shell material, not only does it significantly improve the lithium ion conductivity, but also significantly reduces the H2S gas release amount in a dew point environment of-10℃, and significantly delays the start-up time of the hydrolysis reaction. At the same time, the sulfide solid electrolyte provided by the present application also exhibits excellent cycle stability and interface stability, and can maintain good electrochemical performance even under ultra-low external pressure (0.5 MPa).

[0120] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A sulfide solid-state electrolyte, characterized by, The sulfide solid electrolyte comprises an inner core and a shell layer coated on the surface of the inner core, the material of the inner core is argyrodite electrolyte Li6PS5Cl, and the material of the shell layer is Li 10 SnP2S 12 .

2. The sulfide solid-state electrolyte according to claim 1, characterized by, The Dv50 particle size of the sulfide solid electrolyte is 5-12 μm, and the average thickness of the shell layer is 0.5-2 μm.

3. A method for producing a sulfide solid-state electrolyte, characterized by, The preparation method comprises the following steps: providing Li6PS5Cl, mixing Li6PS5Cl and SnS2 uniformly, and then sequentially performing heat treatment and solvent cleaning to obtain the sulfide solid electrolyte with a core-shell structure; wherein the material of the inner core is the argyrodite electrolyte Li6PS5Cl, and the material of the shell layer is Li 10 SnP2S 12 .

4. The production method according to claim 3, characterized by, The temperature of the heat treatment is 400-500℃, and the time of the heat treatment is 6-12 h.

5. The preparation method according to claim 3, characterized in that, The solvent cleaning comprises: soaking the heat treatment product in an organic solvent, solid-liquid separation and drying to obtain the sulfide solid electrolyte.

6. The production method according to claim 5, wherein The organic solvent is selected from at least one of anhydrous tetrahydrofuran, acetonitrile, acetone, anisole; And / or, the solid-liquid separation method comprises at least one of filtration and centrifugation; And / or, the drying is vacuum drying, the temperature of the vacuum drying is 60-150℃, and the time of the vacuum drying is 4-10 h.

7. The preparation method according to claim 3, characterized in that, The mass ratio of Li6PS5Cl to SnS2 is 100:(5-15), preferably 100:(8-12).

8. The production method according to any one of claims 3 to 7, characterized by, The preparation method of Li6PS5Cl comprises: uniformly mixing Li2S, P2S5 and LiCl according to the stoichiometric ratio, and then performing first sintering treatment to obtain Li6PS5Cl. Preferably, the temperature of the first sintering treatment is 450-550℃, and the time of the first sintering treatment is 5-8 h.

9. The production method according to any one of claims 3 to 7, characterized by, The preparation method of SnS2 comprises: mixing SnCl2·2H2O and N2H4CS according to the stoichiometric ratio, and then performing second sintering treatment to obtain SnS2. Preferably, the temperature of the second sintering treatment is 250-350℃, and the time of the second sintering treatment is 1-4 h.

10. An all-solid battery, characterized by, The all-solid-state battery comprises the sulfide solid electrolyte of claim 1 or 2 or the sulfide solid electrolyte obtained by the preparation method according to any one of claims 3-9.

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