Glass-ceramic state sulfide solid electrolyte as well as preparation method and application thereof

Abstract

The invention discloses a glass-ceramic state sulfide solid electrolyte as well as a preparation method and application thereof. This application is in the field of solid state batteries. According to the invention, Ga, Ge, Si, N and Br elements are doped and modified on the sulfide solid electrolyte L7P3S11 (lithium phosphorus sulfide), so that the glass-ceramic state sulfide solid electrolyte with excellent wet stability is obtained, and the lithium metal symmetric battery is designed and assembled, so that the electrolyte has excellent electrochemical performance. The molecular formula of the sulfide solid electrolyte is Li < 7 + 4x > P < 3-3x > (GaGeSi) < x > S < 11-2x > (NBr) < x >, wherein x is greater than 0 and less than or equal to 0.1. The preparation method of the sulfide solid-state electrolyte is simple and effective, meanwhile, the sulfide solid-state electrolyte has relatively good cycling stability on metal lithium, and the practical application problem of the sulfide solid-state electrolyte serving as an all-solid-state lithium ion battery electrolyte is expected to be solved.

Description

Technical Field

[0001] This application relates to the field of sulfide solid-state batteries, and particularly to a glass-ceramic sulfide solid-state electrolyte, a preparation method thereof, and an application thereof. Background Art

[0002] Lithium-ion batteries are widely used in the fields of electric vehicles, portable electronic devices, large-scale energy storage, etc. due to their high energy density, high power density, and cost advantages. All-solid-state lithium-ion batteries use solid electrolytes to replace flammable liquid organic electrolytes, which not only improves the safety of the batteries but also reduces the use of non-active substances in the batteries. In addition, the introduction of solid electrolytes enables the application of metallic lithium anodes, thereby enabling all-solid-state lithium batteries to obtain higher energy densities. Therefore, all-solid-state batteries constructed by replacing liquid organic electrolytes with solid electrolytes are expected to replace traditional lithium-ion batteries and become the next-generation energy storage technology.

[0003] Generally speaking, the main physical and chemical property requirements for solid electrolytes of all-solid-state lithium-ion batteries mainly include: (1) high room-temperature ionic conductivity (>10 -3 S·cm -1 ); (2) wide electrochemical window (>5.0 V (vs Li / Li + )); (3) low electronic conductivity (<10 -8 S·cm -1 ); (4) good chemical stability to positive / negative electrode materials; (5) ion transference number of about 1; (6) sintering temperature matching between the electrolyte and the electrode active material; (7) low cost and low toxicity. Currently, existing solid electrolytes are mainly divided into three types: polymer solid electrolytes, oxide solid electrolytes, and sulfide solid electrolytes. Among them, sulfide solid electrolytes are considered to be a solid electrolyte material with the most promising industrialization prospects due to their high ionic conductivity and good processing performance.

[0004] In recent years, the research on sulfide solid electrolyte materials has been in full swing. Among them, two sulfide solid electrolyte materials, Li 10 GeP2S 12 (1.2×10 -2 S·cm -1 ) and Li7P3S 11 (1.7×10 -2 S·cm -1 ), with relatively high ionic conductivity have attracted wide attention from scholars. However, the raw materials for synthesizing Li 10 GeP2S 12 contain Ge elements with high cost, which hinders its large-scale application in solid-state batteries. In contrast, Li7P3S 11The raw materials have advantages such as relatively low prices and comparable conductivities, which contribute to its commercial application in the field of solid-state batteries. Despite the above advantages, Li7P3S 11 The practical application process of the electrolyte still faces many problems such as poor air / water stability, poor stability at the electrode interface, a large gap in conductivity compared with organic liquid electrolytes, and poor chemical / electrochemical stability. Therefore, it is urgent to find low-cost and better-performing sulfide solid electrolytes and apply them to all-solid-state lithium-ion batteries. Summary of the Invention

[0005] In view of the above problems existing in the existing preparation technologies, the purpose of this application is to propose an effective design of a glass-ceramic sulfide solid electrolyte with the chemical formula Li 7+4x P 3-3x (GaGeSi) x S 11-2x (NBr) x . The Li7P3S 11 (lithium phosphorus sulfide) sulfide solid electrolyte doped with Ga, Ge, Si, N, and Br elements in this application is assembled into an all-solid-state battery, thereby improving the air stability and stability towards metallic lithium of the electrolyte and promoting its commercial development.

[0006] According to one aspect of this application, there is provided a glass-ceramic sulfide solid electrolyte with the chemical formula Li 7+4x P 3-3x (GaGeSi) x S 11-2x (NBr) x ;

[0007] wherein, x is greater than 0 and less than or equal to 0.1.

[0008] Optionally, the ionic conductivity of the glass-ceramic sulfide solid electrolyte at room temperature is 1 - 3 mS / cm.

[0009] Preferably, x is selected from at least one of 0.02, 0.04, 0.05, 0.06, 0.08, 0.1.

[0010] According to another aspect of this application, there is provided a preparation method for the above glass-ceramic sulfide solid electrolyte, and the preparation method includes:

[0011] Mixing raw materials containing SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N, and LiBr, ball milling, roasting, and sintering to obtain the glass-ceramic sulfide solid electrolyte.

[0012] Optionally, in the raw materials, the molar ratio of SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N, and LiBr is the molar ratio of each element in the above chemical formula.

[0013] Optionally, the rotation speed of the ball milling is 100 - 600 r / min;

[0014] Optionally, the rotation speed of the ball milling is 400 - 600 r / min;

[0015] Optionally, the rotation speed of the ball milling is any value among 400 r / min, 500 r / min, 600 r / min or the range value between any two of them.

[0016] The time of the ball milling is 45 - 1200 min;

[0017] Optionally, the time of the ball milling is 600 - 1200 min;

[0018] Optionally, the time of the ball milling is any value among 600 min, 700 min, 800 min, 900 min, 1000 min, 1100 min, 1200 min or the range value between any two of them.

[0019] Pre - milling is carried out before the ball milling;

[0020] The rotation speed of the pre - milling is 100 - 300 r / min;

[0021] Optionally, the rotation speed of the pre - milling is any value among 100 r / min, 200 r / min, 300 r / min or the range value between any two of them.

[0022] The time of the pre - milling is 30 - 60 min.

[0023] Optionally, the time of the pre - milling is any value among 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min or the range value between any two of them.

[0024] Optionally, the temperature of the roasting is 200 - 300;

[0025] Optionally, the temperature of the roasting is any value among 200, 250, 300 or the range value between any two of them.

[0026] The time of the roasting is 4 - 10 h;

[0027] Optionally, the time of the roasting is any value among 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h or the range value between any two of them.

[0028] Optionally, tabletting is carried out after roasting;

[0029] The pressure for tabletting is 10 - 15 MPa.

[0030] Optionally, the pressure for tabletting is any value among 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa or a range value between any two of them.

[0031] Optionally, the temperature for sintering is 200 - 300;

[0032] Optionally, the temperature for sintering is any value among 200, 250, 300 or a range value between any two of them.

[0033] The time for sintering is 4 - 10 h;

[0034] Optionally, the time for sintering is any value among 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h or a range value between any two of them.

[0035] Optionally, the heating rate for sintering is 5 - 10 / min;

[0036] Optionally, the heating rate for sintering is any value among 5 / min, 6 / min, 7 / min, 8 / min, 9 / min, 10 / min or a range value between any two of them.

[0037] The atmosphere for sintering is an inert gas atmosphere;

[0038] The inert gas atmosphere is selected from at least one of nitrogen, helium, and argon;

[0039] Optionally, it is ground into powder after sintering.

[0040] The ionic conductivity of the sulfide solid electrolyte at room temperature is 1 - 3 mS / cm, meeting the application requirements of all - solid - state lithium - ion batteries.

[0041] Specifically, it is prepared by the following steps.

[0042] Put SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N and LiBr with a molar ratio of 0.01 - 0.05:1.76 - 1.72:0.74 - 0.66:0.01 - 0.05:0.005 - 0.025:0.01 - 0.05:0.01 - 0.05 into a ball - milling jar, pre - mill for 0.5 - 1 h at 100 - 300 rpm, and then ball - mill for 10 - 20 h at 300 - 600 rpm to obtain an amorphous phase mixture of the sulfide solid electrolyte. Then, cold - press to obtain a green body, put it into a quartz tube, and heat it to 200 - 300 at room temperature for 4 - 10 h. After the temperature drops to room temperature, take out the sulfide solid electrolyte for later use.

[0043] Press the above - mentioned amorphous mixture into tablets with a pressure of 10 MPa - 15 MPa and a tablet diameter of 10 cm - 13 cm. Then, under the protection of Ar gas, heat it to 200 - 300 at a heating rate of 5 - 10 / min, keep it warm for 6 - 12 hours, and cool it naturally to room temperature. Then, grind the sintered electrolyte into powder for later use.

[0044] Put the obtained glass - ceramic sulfide solid electrolyte into a solid - state battery mold, keep the interface in close contact under a pressure of 200 - 500 MPa, place the cut Li foil on both sides to assemble a lithium - metal symmetric battery, and finally test its electrochemical performance.

[0045] According to another aspect of the present application, a lithium - metal symmetric battery is provided. The lithium - metal symmetric battery uses the above - mentioned solid electrolyte or the solid electrolyte prepared by the above - mentioned preparation method.

[0046] According to the above - mentioned scheme, the glass - ceramic sulfide solid electrolyte is Li 7.08 P 2.94 (GaGeSi) 0.02 S 10.96 (NBr) 0.02 ,

[0047] Li 7.16 P 2.88 (GaGeSi) 0.04 S 10.92 (NBr) 0.04 ,Li 7.2 P 2.85 (GaGeSi) 0.05 S 10.9 (NBr) 0.05 ,Li 7.24 P 2.82 (GaGeSi) 0.06 S 10.88 (NBr) 0.06 ,

[0048] Li 7.32 P 2.76 (GaGeSi) 0.08 S 10.84 (NBr) 0.08 ,Li 7.4 P 2.7 (GaGeSi) 0.1 S 10.8 (NBr) 0.1 a mixture of one or more of the above, and the negative electrode uses a cut Li foil.

[0049] This application discloses a glass-ceramic sulfide solid electrolyte, its preparation method and application. This application belongs to the field of solid-state batteries. This application mainly modifies the sulfide solid electrolyte L7P3S 11 (lithium phosphorus sulfide) by doping with elements Ga, Ge, Si, N, and Br, and then obtains a glass-ceramic sulfide solid electrolyte with excellent wet stability. By designing and assembling a lithium metal symmetric battery, it shows that this electrolyte has excellent electrochemical performance. The molecular formula of the sulfide solid electrolyte is: Li 7+4x P 3-3x (GaGeSi) x S 11-2x (NBr) x , where x is greater than 0 and less than or equal to 0.1. The preparation method of this sulfide solid electrolyte is simple and effective, and at the same time has good cycle stability for metallic lithium, and is expected to solve the practical application problem of sulfide solid electrolyte as an electrolyte for all-solid-state lithium-ion batteries.

[0050] The beneficial effects of this application are:

[0051] (1) Li7P3S 11 has a conductivity close to that of liquid electrolytes, and the synthesis raw materials are relatively inexpensive compared to other sulfide electrolytes, and it is a solid electrolyte with good application prospects.

[0052] (2) LiBr and Li3N can form a protective layer during charge and discharge, effectively inhibiting the growth of lithium dendrites.

[0053] (3) Doping of Ga, Ge, and Si to replace the P site of the sulfide electrolyte Li7P3S 11 can significantly improve the air stability of the electrolyte and is expected to realize high-voltage all-solid-state lithium-ion batteries, further improving the energy density and cycle life of the battery. Description of the Drawings

[0054] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0055] Figure 1 This is a photo taken after the glass-ceramic sulfide solid electrolyte implemented in the present application was exposed to air for 5 h.

[0056] Figure 2 This is the X-ray diffraction pattern of the glass-ceramic sulfide solid electrolyte implemented in the present application.

[0057] Figure 3 This is for the constant current charge-discharge test curve of the lithium metal symmetric battery assembled using Li 7.2 P 2.85 (GaGeSi) 0.05 S 10.9 (NBr) 0.05 as the electrolyte.

[0058] Figure 4 This is for the constant current charge-discharge test curve of the lithium metal symmetric battery assembled using Li 7.4 P 2.7 (GaGeSi) 0.1 S 10.8 (NBr) 0.1 as the electrolyte.

[0059] Figure 5 This is the electrochemical impedance spectroscopy diagram of the glass-ceramic sulfide solid electrolyte implemented in the present application. Detailed implementation manners

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. For those not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are followed. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0061] The features and performances of the present application will be further described in detail below in combination with the embodiments.

[0062] Example 1

[0063] SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N and LiBr with a molar ratio of 0.01:1.76:0.74:0.01:0.005:0.01:0.01 were placed in a ball milling jar and pre-milled at 250 rpm for 1 h and then ball milled at 600 rpm for 20 h to obtain an amorphous phase mixture of sulfide solid electrolyte. Cold pressing was carried out to obtain a green body, which was put into a quartz tube and heated to 250 at room temperature for 5 h. After the temperature dropped to room temperature, the sulfide solid electrolyte Li 7.08 P 2.94 (GaGeSi) 0.02 S 10.96 (NBr) 0.02 was obtained and labeled as LPS-0.02. The obtained electrolyte was poured into a solid-state battery mold and pressed into tablets at a pressure of 350 MPa. The measured X-ray diffraction pattern is shown in the appendix Figure 2 as shown. The obtained electrolyte was poured into a solid-state battery mold and pressed into tablets at a pressure of 500 MPa. The measured electrochemical impedance spectrum is shown in the appendix Figure 5 (a). The ionic conductivity of this electrolyte was calculated to be 2.93 mS·cm -1 .

[0064] Example 2

[0065] SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N and LiBr with a molar ratio of 0.02:1.75:0.72:0.02:0.01:0.02:0.02 were placed in a ball milling jar and pre-milled at 250 rpm for 1 h and then ball milled at 600 rpm for 20 h to obtain an amorphous phase mixture of sulfide solid electrolyte. Cold pressing was carried out to obtain a green body, which was put into a quartz tube and heated to 250 at room temperature for 5 h. After the temperature dropped to room temperature, the sulfide solid electrolyte Li 7.16 P 2.88 (GaGeSi) 0.04 S 10.92 (NBr) 0.04 was obtained and labeled as LPS-0.04. The obtained electrolyte was poured into a solid-state battery mold and pressed into tablets at a pressure of 350 MPa. The measured X-ray diffraction pattern is shown in the appendix Figure 2 as shown. The obtained electrolyte was poured into a solid-state battery mold and pressed into tablets at a pressure of 500 MPa. The measured electrochemical impedance spectrum is shown in the appendix Figure 5 (b). The ionic conductivity of this electrolyte was calculated to be 2.34 mS·cm -1 .

[0066] Example 3

[0067] SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N and LiBr with a molar ratio of 0.025:1.75:0.71:0.025:0.012:0.025:0.025 were placed in a ball milling jar and pre-milled at 250 rpm for 1 h and then ball milled at 600 rpm for 20 h to obtain an amorphous phase mixture of the sulfide solid electrolyte. Cold pressing was carried out to obtain a green body, which was put into a quartz tube and heated to 250 at room temperature for 5 h. After the temperature dropped to room temperature, the sulfide solid electrolyte Li 7.2 P 2.85 (GaGeSi) 0.05 S 10.9 (NBr) 0.05 was obtained and labeled as LPS-0.05. The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 350 MPa. The measured X-ray diffraction pattern is shown in the appendix Figure 2 as shown. The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 350 MPa. Cut Li foils were placed on both sides. The current density increment for each cycle was 0.05 mA·cm -2 , and a constant current charge-discharge test of the symmetric battery was carried out at 28. The test results are shown in Figure 3 as shown, and the critical current density of this electrolyte was obtained as 3.1 mA·cm -2 . The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 500 MPa. The measured electrochemical impedance spectrum is shown in the appendix Figure 5 (c) as shown, and the ionic conductivity of this electrolyte was calculated to be 1.76 mS·cm -1 .

[0068] Example 4

[0069] SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N and LiBr with a molar ratio of 0.03:1.74:0.70:0.03:0.015:0.03:0.03 were placed in a ball milling jar and pre-milled at 250 rpm for 1 h and then ball milled at 600 rpm for 20 h to obtain an amorphous phase mixture of the sulfide solid electrolyte. Cold pressing was carried out to obtain a green body, which was put into a quartz tube and heated to 250 at room temperature for 5 h. After the temperature dropped to room temperature, the sulfide solid electrolyte Li 7.24 P 2.82 (GaGeSi) 0.06 S 10.88 (NBr) 0.06 was obtained and labeled as LPS-0.06. The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 350 MPa. The measured X-ray diffraction pattern is shown in the appendix Figure 2 as shown. The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 500 MPa. The measured electrochemical impedance spectrum is shown in the appendixFigure 5 (As shown in (d), the ionic conductivity of this electrolyte was calculated to be 2.14 mS·cm -1 .

[0070] Example 5

[0071] SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N, and LiBr with a molar ratio of 0.04:1.73:0.68:0.04:0.02:0.04:0.04 were placed in a ball milling jar and pre-milled at 250 rpm for 1 h and then ball milled at 600 rpm for 20 h to obtain an amorphous phase mixture of the sulfide solid electrolyte. The obtained mixture was cold pressed to obtain a green body, which was placed in a quartz tube and heated to 250 °C at room temperature for 5 h. After the temperature was cooled to room temperature, the sulfide solid electrolyte Li 7.32 P 2.76 (GaGeSi) 0.08 S 10.84 (NBr) 0.08 was obtained and labeled as LPS-0.08. The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 350 MPa. The X-ray diffraction pattern measured is as shown in the appendix Figure 2 . The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 500 MPa. The electrochemical impedance spectrum measured is as shown in the appendix Figure 5 (e), and the ionic conductivity of this electrolyte was calculated to be 2.03 mS·cm -1 .

[0072] Example 6

[0073] SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N, and LiBr with a molar ratio of 0.05:1.72:0.66:0.05:0.025:0.05:0.05 were placed in a ball milling jar and pre-milled at 250 rpm for 1 h and then ball milled at 600 rpm for 20 h to obtain an amorphous phase mixture of the sulfide solid electrolyte. The obtained mixture was cold pressed to obtain a green body, which was placed in a quartz tube and heated to 250 °C at room temperature for 5 h. After the temperature was cooled to room temperature, the sulfide solid electrolyte Li 7.4 P 2.7 (GaGeSi) 0.1 S 10.8 (NBr) 0.1 was obtained and labeled as LPS-0.10. The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 350 MPa. The X-ray diffraction pattern measured is as shown in the appendix Figure 2 . The obtained electrolyte was poured into a solid-state battery mold and pressed into a tablet at a pressure of 350 MPa. Cut Li foils were placed on both sides. The current density increment for each cycle was 0.05 mA·cm -2, the symmetric battery constant current charge-discharge test was carried out at 28. The test results are as Figure 4 shown, and the critical current density of this electrolyte was obtained as 0.9 mA·cm -2 . The obtained electrolyte was poured into a solid-state battery mold and pressed into tablets under a pressure of 500 MPa. The measured electrochemical impedance spectrum is as attached Figure 5 (f) shown. The ionic conductivity of this electrolyte was calculated to be 1.49 mS·cm -1 .

[0074] Test Example 1

[0075] Photos of the glass-ceramic sulfide solid electrolytes of Examples 1, 2, 4, and 5 taken after being exposed to air for 5 h are as Figure 1 shown. It can be seen that this electrolyte has excellent wet stability.

[0076] The X-ray diffraction patterns of the glass-ceramic sulfide solid electrolytes of Examples 1 to 6 are as Figure 2 shown. It can be seen from the figure that elements Ga, Ge, Si, N, and Br can be well incorporated into the L7P3S 11 lattice. However, as x increases, the diffraction peak intensities corresponding to 27.8° and 29.4° gradually increase, indicating the precipitation of the Ga2S3 phase. It shows that only an appropriate doping amount can obtain a pure-phase Ga, Ge, Si, N, Br element-doped L7P3S 11 glass-ceramic sulfide solid electrolyte.

[0077] In Example 3, Li 7.2 P 2.85 (GaGeSi) 0.05 S 10.9 (NBr) 0.05 was used as the electrolyte to assemble the constant current charge-discharge test curve of the lithium metal symmetric battery as Figure 3 shown. Li 7.2 P 2.85 (GaGeSi) 0.05 S 10.9 (NBr) 0.05 The electrolyte was pressed into tablets in a battery mold, and cut Li foils were placed on both sides. The Li / / Li symmetric battery constant current charge-discharge test was carried out at 28 °C, and the current density increment for each cycle was 0.05 mA·cm -2 , and the critical current density of this electrolyte was obtained as 3.1 mA·cm -2 .

[0078] In Example 6, Li 7.4 P 2.7 (GaGeSi) 0.1 S 10.8 (NBr)0.1 The galvanostatic charge-discharge test curves of the lithium metal symmetric battery assembled with the electrolyte are as Figure 4 shown. Press the Li 7.4 P 2.7 (GaGeSi) 0.1 S 10.8 (NBr) 0.1 electrolyte into tablets in the battery mold, place the cut Li foils on both sides, and conduct the galvanostatic charge-discharge test of the Li / / Li symmetric battery at 28 °C. The current density increment for each cycle is 0.05 mA·cm -2 , and the critical current density of this electrolyte is obtained as 0.9 mA·cm -2 .

[0079] The electrochemical impedance spectra of the glass-ceramic sulfide solid electrolytes of Examples 1 to 6 are as Figure 5 shown. It can be seen from the figure that as the doping amounts of Ga, Ge, Si, N, and Br elements increase, the impedance of this sulfide solid electrolyte shows a regular change of increase-decrease-increase, that is, only an appropriate doping amount can obtain a sulfide solid electrolyte with high ionic conductivity. The result is consistent with the result of the X-ray diffraction pattern, further indicating that only an appropriate doping amount can obtain a pure-phase Ga, Ge, Si, N, Br element-doped L7P3S 11 glass-ceramic sulfide solid electrolyte.

[0080] As described above, only several embodiments of the present application are provided, and no any form of limitation is imposed on the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are all equivalent to equivalent embodiments and all fall within the scope of the technical solution.

Claims

1. A glass-ceramic sulfide solid electrolyte, characterized in that, The chemical formula of the glass-ceramic sulfide solid electrolyte is Li 7+4x P 3-3x (GaGeSi) x S 11-2x (NBr) x ; Among them, x is greater than 0 and less than or equal to 0.

1.

2. The glass-ceramic sulfide solid electrolyte according to claim 1, characterized in that, The ionic conductivity of the glass-ceramic sulfide solid electrolyte at room temperature is 1-3 mS / cm; Preferably, x is selected from at least one of 0.02, 0.04, 0.05, 0.06, 0.08, 0.

1.

3. A method for preparing the glass-ceramic sulfide solid electrolyte according to claim 1 or 2, characterized in that, The preparation method includes: Mixing raw materials containing SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N and LiBr, ball milling, roasting, and sintering to obtain the glass-ceramic sulfide solid electrolyte.

4. The preparation method according to claim 3, characterized in that, In the raw materials, the molar ratio of SiS2, Li2S, P2S5, GeS2, Ga2S3, Li3N and LiBr is the molar ratio of each element in the chemical formula described in claim 1.

5. The preparation method according to claim 3, characterized in that, The rotation speed of the ball milling is 100-600 r / min; The time of the ball milling is 45-1200 min.

6. The preparation method according to claim 3, characterized in that, The temperature of the roasting is 200-300; The time of the roasting is 4-10 h.

7. The preparation method according to claim 3, characterized in that, The temperature of the sintering is 200-300; The time of the sintering is 4-10 h.

8. The preparation method according to claim 3, characterized in that, The heating rate of the sintering is 5-10 / min.

9. The preparation method according to claim 3, characterized in that, The atmosphere of the sintering is an inert gas atmosphere; The inert gas atmosphere is selected from at least one of nitrogen, helium, and argon.

10. A lithium metal symmetric battery, characterized in that, The metal lithium symmetric battery uses the glass-ceramic sulfide solid electrolyte described in claim 1 or 2 or the glass-ceramic sulfide solid electrolyte prepared by the preparation method described in any one of claims 3-9.

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