INORGANIC SULFIDE SOLID ELECTROLYTE HAVING HIGH AIR STABILITY, AND PREPARATION METHOD AND USE THEREOF

Abstract

An inorganic sulfide solid electrolyte having high air stability, and a preparation method and use thereof In the invention, some or all of P elements in a sulfide electrolyte are replaced with Sb elements, thereby providing an electrolyte having high air stability and ion mobility and applicable to an all-solid lithium secondary battery. The resulting inorganic sulfide electrolyte comprises the following materials: Li.sub.10M(P.sub.1-aSb.sub.a).sub.2S.sub.12, Li.sub.6(P.sub.1-aSb.sub.a)S.sub.5X and Li.sub.3(P.sub.1-aSb.sub.a)S.sub.4, where M is one or more of Ge, Si or Sn, X is one or more of F, Cl, Br or I, and 0.01≤a≤1.

Claims

1. An inorganic sulfide electrolyte material represented by the following formula (I),
Li.sub.10M(P.sub.1-aSb.sub.a).sub.2S.sub.12,   (I); wherein, M is one or more of Ge, Si and Sn, 0.01≤a≤1; preferably, 0.01≤a≤0.2.

2. The inorganic sulfide electrolyte material according to claim 1, wherein a is selected from 0.01, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.2, 0.3, 0.4 or 1; preferably, the inorganic sulfide electrolyte material represented by the formula (I) is Li.sub.10Ge(P.sub.0.99Sb.sub.0.01).sub.2S.sub.12, Li.sub.10Ge(P.sub.0.975Sb.sub.0.025).sub.2S.sub.12, Li.sub.10Ge(P.sub.0.925Sb.sub.0.075).sub.2S.sub.12, Li.sub.10Ge(P.sub.0.9Sb.sub.0.1).sub.2S.sub.12, Li.sub.10Ge(P.sub.0.875Sb.sub.0.125).sub.2S.sub.12, Li.sub.10Sn(P.sub.0.95Sb.sub.0.05).sub.2S.sub.12 or Li.sub.10Si(P.sub.0.95Sb.sub.0.05).sub.2S.sub.12.

3. An inorganic sulfide electrolyte material represented by the following formula (II),
Li.sub.6(P.sub.1-aSb.sub.a)S.sub.5X,   (II); wherein X is one or more of F, Cl, Br and I, 0.01≤a≤1; preferably, 0.025≤a≤0.2.

4. The inorganic sulfide electrolyte material according to claim 3, wherein a is selected from 0.025, 0.05, 0.075, 0.1, 0.15, 0.2, 0.5 or 1; preferably, the inorganic sulfide electrolyte material represented by the formula (II) is Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl or Li.sub.6(P.sub.0.95Sb.sub.0.05)S.sub.5Cl.

5. An inorganic sulfide electrolyte material represented by the following formula (III),
Li.sub.3(P.sub.1-aSb.sub.a)S.sub.4,   (III); wherein, 0.01≤a≤1; preferably, 0.05≤a≤0.3.

6. The inorganic sulfide electrolyte material according to claim 5, wherein a is selected from 0.05, 0.1, 0.2 or 0.3.

7. The inorganic sulfide electrolyte material according to claim 1, wherein the inorganic sulfide electrolyte material is a crystalline, amorphous or crystalline-amorphous composite type; and/or a working temperature of the sulfide solid electrolyte material is −100° C. to 300° C.

8. The preparation method of the inorganic sulfide electrolyte material according to claim 1, characterized by mixing the required raw materials according to the proportion, and grinding, and then performing heat treatment to obtain the sulfide electrolyte materials represented by the formula (I), formula (II), and formula (III), respectively.

9. The preparation method according to claim 8, wherein the time for the grinding is greater than 3 h; and/or the temperature for the heat treatment is greater than 300° C. and less than 600° C.

10. The preparation method according to claim 8, wherein the time for the grinding is greater than 3 h; and/or the temperature for the heat treatment is greater than 230° C. and less than 600° C.

11. A method for preparing an all-solid-state lithium secondary battery, wherein the method comprises using the sulfide solid electrolyte materials according to claim 1.

12. The inorganic sulfide electrolyte material according to claim 3, wherein the inorganic sulfide electrolyte material is a crystalline, amorphous or crystalline-amorphous composite type; and/or a working temperature of the sulfide solid electrolyte material is −100° C. to 300° C.

13. The inorganic sulfide electrolyte material according to claim 5, wherein the inorganic sulfide electrolyte material is a crystalline, amorphous or crystalline-amorphous composite type; and/or

14. The preparation method of the inorganic sulfide electrolyte material according to claim 3, characterized by mixing the required raw materials according to the proportion, and grinding, and then performing heat treatment to obtain the sulfide electrolyte materials represented by the formula (I), formula (II), and formula (III), respectively.

15. The preparation method of the inorganic sulfide electrolyte material according to claim 5, characterized by mixing the required raw materials according to the proportion, and grinding, and then performing heat treatment to obtain the sulfide electrolyte materials represented by the formula (I), formula (II), and formula (III), respectively.

16. A method for preparing an all-solid-state lithium secondary battery, wherein the method comprises using the sulfide solid electrolyte materials according to claim 3.

17. A method for preparing an all-solid-state lithium secondary battery, wherein the method comprises using the sulfide solid electrolyte materials according to claim 5.

18. A method for preparing an all-solid-state lithium secondary battery, wherein the method comprises using the sulfide solid electrolyte materials prepared by the method according to claim 8.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is an x-ray diffraction pattern obtained when a=0.01 in Example 1;

[0030] FIG. 2 shows some x-ray diffraction patterns obtained from the system in Example 1;

[0031] FIG. 3 shows graphs of electrochemical impedance and ion conductivity at different temperatures obtained when a=0.01 in Example 1;

[0032] FIG. 4 is a graph showing the relationship between the ion conductivity and the value of “a” of the material obtained in Example 1;

[0033] FIG. 5 is an x-ray diffraction pattern obtained when a=0.025 in Example 2;

[0034] FIG. 6 shows some x-ray diffraction patterns obtained from the system in Example 2;

[0035] FIG. 7 shows graphs of electrochemical impedance and ion conductivity at different temperatures obtained when a=0.025 in Example 2;

[0036] FIG. 8 is a graph of the relationship between the ion conductivity and the value of “a” of the material obtained in Example 2;

[0037] FIG. 9 is an x-ray diffraction pattern obtained when a=0.05 in Example 3;

[0038] FIG. 10 shows graphs of electrochemical impedance and ion conductivity at different temperatures obtained when a=0.05 in Example 3;

[0039] FIG. 11 is an x-ray diffraction pattern obtained when a=0.05 in Example 4;

[0040] FIG. 12 shows graphs of electrochemical impedance and ion conductivity at different temperatures obtained when a=0.05 in Example 4;

[0041] FIG. 13 shows graphs of electrochemical impedance and ion conductivity at different temperatures obtained when a=0.1 in Example 5;

[0042] FIG. 14 shows comparison of XRD patterns of the Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl material before and after exposure to air in Application Example 1;

[0043] FIG. 15 shows comparison of XRD patterns of the Li.sub.6(P.sub.0.9Sb.sub.0.1)S.sub.5Cl material before and after exposure to air in Application Example 1;

[0044] FIG. 16 shows graphs concerning comparison of the electrochemical impedance spectroscopies and comparison of ion conductivities (obtained by calculation) of the Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl material before and after exposure to air in Application Example 1;

[0045] FIG. 17 shows graphs concerning comparison of the electrochemical impedance spectroscopies and comparison of the ion conductivities (obtained by calculation) of the Li.sub.6(P.sub.0.9Sb.sub.0.1)S.sub.5Cl material before and after exposure to air in Application Example 1;

[0046] FIG. 18 shows graphs of the ion conductivity varying with change in temperature and current-time relationship graphs at a constant external voltage of 0.3 V for the Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl and Li.sub.6(P.sub.0.9Sb.sub.0.1)S.sub.5Cl in Application Example 1;

[0047] FIG. 19 shows comparison of XRD patterns of the Li.sub.10Ge(P.sub.0.875Sb.sub.0.125).sub.2S.sub.12 material before and after exposure to air in Application Example 2;

[0048] FIG. 20 shows comparison graphs of ion conductivities of the solid electrolyte materials of Li.sub.10Ge(P.sub.0.75Sb.sub.0.025).sub.2S.sub.12, Li.sub.10Ge(P.sub.0.925Sb.sub.0.075).sub.2S.sub.12, Li.sub.1Ge(P.sub.0.9Sb.sub.0.1).sub.2S.sub.12 and Li.sub.10Ge(P.sub.0.875Sb.sub.0.125).sub.2S.sub.12 before and after exposure to air in Application Example 2.

[0049] FIG. 21 is a graph showing the charging and discharging curve of an all-solid-state Li—LiCoO.sub.2 secondary battery using the solid solution phase type Li.sub.10Ge(P.sub.0.99Sb.sub.0.01).sub.2S.sub.12 solid electrolyte material obtained in Application Example 3.

SPECIFIC MODES FOR CARRYING OUT THE EMBODIMENTS

[0050] The following Examples are used to illustrate the present invention, but are not used to limit the scope of the present invention. If the specific technologies or conditions are not indicated in the Examples, the Examples shall be carried out according to those described in the literatures in the field, or according to the product specification. If the manufacturers for some reagents or instruments are not indicated, the reagents or instruments used are conventional products that can be purchased through regular channels.

EXAMPLE 1: PREPARATION OF THE SOLID ELECTROLYTE MATERIAL Li.SUB.10.Ge(P.SUB.1-a.Sb.SUB.a.).SUB.2.S.SUB.12 .(0.01≤a≤1)

[0051] 15 mmoles of Li.sub.2S (0.69 g), 3 mmoles of GeS.sub.2 (0.411 g), (3-3a) mmoles of P.sub.2S.sub.5, and 3a mmoles of Sb.sub.2S.sub.5 powder were ground and mixed in a mortar, wherein 0.01≤a≤1. For example, if a=0.01, the formulation of various raw material was as follows: Li.sub.2S.sub.0.69 g, GeS.sub.2 0.411 g, P.sub.2S.sub.5 0.66 g, and Sb.sub.2S.sub.5 0.012 g. If a=0.1, the formulation of various raw material was as follows: Li.sub.2S 0.69 g, GeS.sub.2 0.411 g, P.sub.2S.sub.5 0.599 g, and Sb.sub.2S.sub.5 0.121 g, and so on. After being ground and mixed, the mixture was put into a 50 ml zirconia ball mill tank for ball milling at a ball milling speed of 400 revolutions per minute for 12 h. After being ball milled, the samples were compressed into round tablets at 100 MPa using a powder tableting machine, and then sealed in a vacuum quartz tube for calcination. The calcination temperature was controlled by programmed temperature rise. The temperature was increased from room temperature to 550° C. in 4 h, maintained at 550° C. for 4 h, and then controlled to decrease to 50° C. in 4 h, to obtain Li.sub.10Ge(P.sub.1-aSb.sub.a).sub.2S.sub.12 solid electrolyte material (0.01≤a≤1).

[0052] FIG. 1 shows the X-ray diffraction patterns of the material when a=0.01 (i.e., the solid electrolyte material Li.sub.10Ge(P.sub.0.99Sb.sub.0.01).sub.2S.sub.12) and Li.sub.10GeP.sub.2S.sub.12 standard card (JPCDF: 04-020-5216). FIG. 2 shows the X-ray diffraction patterns for the system with different values of a, wherein a is 0.01, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.2, 0.3, 0.4 and 1 from top to bottom, respectively. FIG. 3 shows graphs of electrochemical impedance at different temperatures and curve of ion conductivity varying with temperature for the material when a=0.01 (i.e., the solid electrolyte material Li.sub.10Ge(P.sub.0.99Sb.sub.0.01).sub.2S.sub.12). It can be obtained from FIG. 3 that the ion conductivity of this material is 11.4 millisiemens per centimeter at 25° C., and the activation energy is 11.0 kJ per mole. FIG. 4 is a graph showing the relationship between the ion conductivity and the value of “a” of the solid solution phase sulfide electrolyte material obtained in this system. It is found from FIG. 4 that when the value of “a” is 0.075 (i.e., the solid electrolyte material Li.sub.10Ge(P.sub.0.925Sb.sub.0.075).sub.2S.sub.12), the material has the highest room-temperature ion conductivity of 17.5 millisiemens per centimeter, which is higher than the room-temperature ion conductivity (12 millisiemens per centimeter) of Li.sub.10GeP.sub.2S.sub.12 material reported in literatures.

EXAMPLE 2: PREPARATION OF THE SOLID ELECTROLYTE MATERIAL Li.SUB.6.(P.SUB.1-a.Sb.SUB.a.)S.SUB.5.Cl (0.01≤a≤1)

[0053] 20 mmoles of Li.sub.2S (0.92 g), 8 mmoles of LiCl (0.336 g), (4-4a) mmoles of P.sub.2S.sub.5 and 4a mmoles of Sb.sub.2S.sub.5 powder were ground and mixed in a mortar, wherein 0.01≤a≤1. For example, if a=0.025, the formulation of various raw material was as follows: Li.sub.2S 0.92 g, LiCl 0.336 g, P.sub.2S.sub.5 0.866 g, and Sb.sub.2S.sub.5 0.03 g. If a=0.1, the formulation of various raw material was as follows: Li.sub.2S 0.92 g, LiCl 0.336 g, P.sub.2S.sub.5 0.799 g, and Sb.sub.2S.sub.5 0.121 g, and so on. After being ground and mixed, the mixture was put into a 50 ml zirconia ball mill tank for ball milling at a ball milling speed of 400 revolutions per minute for 12 h. After being ball milled, the samples were compressed into round tablets at 100 MPa using a powder tableting machine, and then sealed in a vacuum quartz tube for calcination. The calcination temperature was controlled by programmed temperature rise. The temperature was increased from room temperature to 550° C. in 4 h, maintained at 550° C. for 5 h, and then decreased to 50° C. by natural cooling to obtain the solid electrolyte material Li.sub.6(P.sub.1-aSb.sub.a)S.sub.5Cl (0.01≤a≤1).

[0054] FIG. 5 shows the X-ray diffraction patterns of the material when a=0.025 (i.e., the solid electrolyte material Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl) and Li.sub.6PS.sub.5Cl standard card (JPCDF: 04-018-1429). FIG. 6 shows the X-ray diffraction patterns for the system with different values of “a”, wherein a is 0.025, 0.05, 0.075, 0.1, 0.15, 0.2, 0.5 and 1 from top to bottom, respectively. FIG. 7 shows graphs of electrochemical impedance at different temperatures and curve of ion conductivity varying with temperature for the material when a=0.025 (i.e., the solid electrolyte material Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl). It can be obtained from FIG. 7 that the ion conductivity of this material is 2.5 millisiemens per centimeter at 25° C., and the activation energy is 18.4 kJ per mole. FIG. 8 is a graph showing the relationship between the ion conductivity and the “a” value of the solid solution phase sulfide electrolyte material obtained in this system. It is found from FIG. 8 that when the value of a is 0.05 (i.e., the solid electrolyte material Li.sub.6(P.sub.0.95Sb.sub.0.05)S.sub.5Cl), the material has the highest room-temperature ion conductivity, i.e., 2.9 millisiemens per centimeter, which is higher than the room-temperature ion conductivity (1.3 millisiemens per cm) of the non-solid solution phase Li.sub.6PS.sub.5Cl material under the same conditions.

EXAMPLE 3: PREPARATION OF THE SOLID ELECTROLYTE MATERIAL Li.SUB.10.Sn(P.SUB.0.95S.Sb.SUB.0.05..SUB.2S.SUB.12

[0055] 15 mmoles of Li.sub.2S (0.69 g), 3 mmoles of SnS.sub.2 (0.549 g), 2.85 mmoles of P2S5 (0.633 g), and 0.15 mmoles of Sb.sub.2S.sub.5 powder (0.061 g) were ground and mixed in a mortar. After being ground and mixed, the mixture was put into a 50 ml zirconia ball mill tank for ball milling at a ball milling speed of 400 revolutions per minute for 12 h. After being ball milled, the samples were compressed into round tablets at 100 MPa using a powder tableting machine, and then sealed in a vacuum quartz tube for calcination. The calcination temperature was controlled by programmed temperature rise. The temperature was increased from room temperature to 550° C. in 4 h, maintained at 550° C. for 4 h, and then controlled to decrease to 50° C. in 4 h to obtain the solid electrolyte material Li.sub.10Sn(P.sub.0.95Sb.sub.0.05).sub.2S.sub.12.

[0056] FIG. 9 shows the X-ray diffraction pattern of the solid electrolyte material Li.sub.10Sn(P.sub.0.95Sb.sub.0.05).sub.2S.sub.12. FIG. 10 shows graphs of electrochemical impedance at different temperatures and curve of ion conductivity varying with temperature for this solid electrolyte material. It can be obtained from FIG. 10 that the ion conductivity of this material is 5.6 millisiemens per centimeter at 25° C., and the activation energy is 11.6 kJ per mole. It is found from FIG. 10 that the Li.sub.10Sn(P.sub.0.95Sb.sub.0.05).sub.2S.sub.12 solid electrolyte material has a relatively high room-temperature ion conductivity, which is closer to the room-temperature ion conductivity (6.3 millisiemens per centimeter) of the Li.sub.10SnP.sub.2S.sub.12 material reported in literatures.

EXAMPLE 4: PREPARATION OF THE SOLID ELECTROLYTE MATERIAL Li.SUB.10.Si(P.SUB.0.95.Sb.SUB.0.05.).SUB.2.S.SUB.12

[0057] 15 mmoles of Li.sub.2S (0.69 g), 3 mmoles of SiS.sub.2 (0.276 g), 2.85 mmoles of P.sub.2S.sub.5 (0.633 g), and 0.15 mmoles of Sb.sub.2S.sub.5 powder (0.061 g) were ground and mixed in a mortar. After being ground and mixed, the mixture was put into a 50 ml zirconia ball mill tank for ball milling at a ball milling speed of 400 revolutions per minute for 12 h. After being ball milled, the samples were compressed into round tablets at 100 MPa using a powder tableting machine, and then sealed in a vacuum quartz tube for calcination. The calcination temperature was controlled by programmed temperature rise. The temperature was increased from room temperature to 550° C. in 4 h, maintained at 550° C. for 4 h, and then controlled to decrease to 50° C. in 4 h to obtain the solid electrolyte material Li.sub.10Si(P.sub.0.95Sb.sub.0.05).sub.2S.sub.12.

[0058] FIG. 11 shows the X-ray diffraction pattern of the solid electrolyte material Li.sub.10Si(P.sub.0.95Sb.sub.0.05).sub.2S.sub.12. FIG. 12 shows graphs of electrochemical impedance at different temperatures and curve of ion conductivity varying with temperature for this solid electrolyte material. It can be obtained from FIG. 12 that the ion conductivity of this material is 2.5 millisiemens per centimeter at 25° C., and the activation energy is 11.6 kJ per mole. It is found from FIG. 12 that the Li.sub.10Si(P.sub.0.95Sb.sub.0.05).sub.2S.sub.12 solid electrolyte material has a relatively high room-temperature ion conductivity, which is higher than the room-temperature ion conductivity (2 millisiemens per centimeter) of the Li.sub.10SiP.sub.2S.sub.12 material reported in literatures.

EXAMPLE 5: PREPARATION OF THE SOLID ELECTROLYTE MATERIAL Li.SUB.3.(P.SUB.1-a.Sb.SUB.a.)S.SUB.4 .(0.01≤a≤1)

[0059] 9 mmoles of Li.sub.2S (0.414 g), (3-3a) mmoles of P.sub.2S.sub.5, and 3a mmoles of Sb.sub.2S.sub.5 powder were ground and mixed in a mortar, wherein 0.01≤a≤1. If a=0.05, the formulation of various raw material was as follows: Li.sub.2S 0.414 g, P.sub.2S.sub.5 0.633 g, and Sb.sub.2S.sub.5 0.061 g. If a=0.1, the formulation of various raw material was as follows: Li.sub.2S 0.414 g, P.sub.2S.sub.5 0.599 g, and Sb.sub.2S.sub.5 0.121 g, and so on. After being ground and mixed, the mixture was put into a 50 ml zirconia ball mill tank for ball milling at a ball milling speed of 400 revolutions per minute for 12 h. After being ball milled, the samples were compressed into round tablets at 100 MPa using a powder tableting machine, and then sealed in a vacuum quartz tube for calcination. The calcination temperature was controlled by programmed temperature rise. The temperature was increased from room temperature to 260° C. in 3 h, maintained at 260° C. for 4 h, and then controlled to decrease to 50° C. in 4 h to obtain the solid electrolyte material Li.sub.3(P.sub.1-aSb.sub.a)S.sub.4 (0.01≤a≤1).

[0060] FIG. 13 shows graphs of electrochemical impedance at different temperatures and curve of ion conductivity varying with temperature for the material when a=0.1 (i.e., the solid electrolyte material Li.sub.3(P.sub.0.9Sb.sub.0.1)S.sub.4). It can be obtained from FIG. 13 that the ion conductivity of this material is 0.06 millisiemens per centimeter at 25° C., and the activation energy is 16.0 kJ per mole.

APPLICATION EXAMPLE 1: AIR STABILITY TEST AND APPLICATION OF THE Li.SUB.6.(P.SUB.1-a.Sb.SUB.a.)S.SUB.5.Cl SOLID ELECTROLYTE MATERIAL

[0061] The Li.sub.6(P.sub.1-aSb.sub.a)S.sub.5Cl solid electrolyte material obtained in Example 2 was used for dry air stability test (a=0.025, 0.1). In a glove box, the solid electrolyte materials Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl and Li.sub.6(P0.9Sb.sub.0.1)S.sub.5Cl (100 mg for each) obtained in Example 2 were taken, and put into a 1 ml open glass bottle, respectively, then the glass bottles were placed in a reaction box which was ventilated with a flow of dry air, and allowed to stand at room temperature for 24 h under a dry air flow of 100 ml per minute. Afterwards, the samples were taken out for XRD, ion conductivity and electroconductivity tests.

[0062] FIG. 14 shows comparison of XRD patterns of the material Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl before and after exposure to air. FIG. 15 shows comparison of XRD patterns of the material Li.sub.6(P.sub.0.9Sb.sub.0.1)S.sub.5Cl before and after exposure to air. FIG. 16 shows graphs concerning comparison of the electrochemical impedance spectroscopies and comparison of the ion conductivities (obtained by calculation) of the material Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl before and after exposure to air. FIG. 17 shows graphs concerning comparison of the electrochemical impedance spectroscopies and the comparison of ion conductivities (obtained by calculation) of the material Li.sub.6(P.sub.0.9Sb.sub.0.1)S.sub.5Cl material before and after exposure to air. FIG. 18 shows graphs of the ion conductivity varying with temperature change and current-time relationship graphs at a constant external voltage of 0.3 V of these two materials. It can be found from the above Figures that after exposure to air, the XRD of the material Li.sub.6(P.sub.0.975Sb.sub.0.025)S.sub.5Cl does not change much, but the ion conductivity decreases greatly. After 24 hours of action of air atmosphere, the ion conductivity of the material decreases from 2.5×10.sup.−3 Scm.sup.−1 to 1.0×10.sup.−5 Scm.sup.−1. After the action of air atmosphere, the ion conductivity of the material is only 0.004 times that before the action of air. As the Sb content in the solid solution phase structure increases to 10% (a=0.1), the air stability of the obtained solid electrolyte material Li.sub.6(P.sub.0.9Sb.sub.0.1)S.sub.5Cl becomes higher. Similarly, after 24 hours of action of air atmosphere, the XRD pattern of the material does not change much, and the ion conductivity decreases from 1.9×10.sup.−3 Scm.sup.−1 to 2.3×10.sup.−4 Scm.sup.−1. After the action of air atmosphere, the ion conductivity of the material is 0.12 times that before the action of air. In addition, the electroconductivities of the above two materials do not change much.

APPLICATION EXAMPLE 2: AIR STABILITY TEST AND APPLICATION OF THE SOLID ELECTROLYTE MATERIAL Li.SUB.10.Ge(P.SUB.1-a.Sb.SUB.a.).SUB.2.S.SUB.12

[0063] The Li.sub.10Ge(P.sub.1-aSb.sub.a).sub.2S.sub.12 solid electrolyte material obtained in Example 1 was used for dry air stability test (a=0.025, 0.075, 0.1, 0.125). In a glove box, the solid electrolyte materials Li.sub.10Ge(P.sub.0.975Sb.sub.0.025).sub.2S.sub.12, Li.sub.10Ge(P.sub.0.925 Sb.sub.0.075).sub.2S.sub.12, Li.sub.10Ge(P.sub.0.9Sb.sub.0.1).sub.2S.sub.12 and Li.sub.10Ge(P.sub.0.875Sb.sub.0.125).sub.2S.sub.12 (200 mg each) obtained in Example 1 were taken, and put into a 1 ml open glass bottle, respectively, then the glass bottles were placed in a reaction box which was ventilated with a flow of dry air, and allowed to stand at room temperature for 24 h under a dry air flow of 100 ml per minute. Afterwards, the samples were taken out for XRD, ion conductivity and electroconductivity tests. FIG. 19 shows comparison of XRD patterns of the material Li.sub.10Ge(P.sub.0.875Sb.sub.0.125).sub.2S.sub.12 before and after exposure to air. FIG. 20 shows comparison graphs of ion conductivity change of these four materials before and after exposure to air. It can be found from the above Figures that after exposure to air for 24 h, the XRD of the material Li.sub.10Ge(P.sub.0.875Sb.sub.0.125).sub.2S.sub.12 does not change much. Similarly, the ion conductivities of the obtained four materials do not change much before and after exposure to air. After 24 hours of exposure to air, the ion conductivities of the above four materials can still reach 10 mScm.sup.−2 or more. It shows that the material has good air stability and can be used directly in a dry air atmosphere, with great application value.

APPLICATION EXAMPLE 3: APPLICATION OF THE ELECTROLYTE MATERIAL Li.SUB.10.Ge(P.SUB.0.99.Sb.SUB.0.01.).SUB.2.S.SUB.12 .IN AN ALL-SOLID-STATE Li—LiCoO.SUB.2 .SECONDARY BATTERY

[0064] The Li.sub.10Ge(P.sub.0.99Sb.sub.0.01).sub.2S.sub.12 electrolyte material obtained in Example 1 was used in an all-solid-state Li—LiCoO.sub.2 secondary battery. The LiCoO.sub.2 positive electrode material used was first coated with LiNbO.sub.2 on the surface through atomic layer deposition (ALD), and the coating layer was about 10 nm. After the completion of coating, the LiCoO.sub.2 positive electrode material, the electrolyte material Li.sub.10Ge(P.sub.0.99Sb.sub.0.01).sub.2S.sub.12 and acetylene carbon were mixed at a ratio of 60:30:10 (mass ratio) in a glove box. Specifically, the mixing process refers to grinding with a mortar for 20 min. The ground material was used as a positive electrode powder. A thin metal indium sheet was used as the negative electrode, and the electrolyte material Li.sub.10Ge(P.sub.0.99Sb.sub.0.01).sub.2S.sub.12 obtained in Example 1 was also used as the electrolyte. 100 mg of the electrolyte material Li.sub.10Ge(P.sub.0.99Sb.sub.0.01).sub.2S.sub.12 was taken and put into a liner for a mold battery with a cross-sectional area of 0.785 cm.sup.2, and pressed under a pressure of 200 MPa to obtain an electrolyte layer. Subsequently, 10 mg of the positive electrode powder was added to one side of the electrolyte layer, and after spreading evenly, pressing was performed under a pressure of 350 MPa for the second time to laminate the positive electrode layer and the electrolyte layer together. Then an indium sheet as a negative electrode layer was placed on the other side of the electrolyte layer. After the whole process was completed, the liner was put into the mold battery, and sealed by pressing and tightening screws, so as to obtain an all-solid-state Li—LiCoO.sub.2 secondary battery after sealing. A charging-discharging test was performed on the battery with a current density of 32 mA, and a cut-off voltage of 2.0 to 3.6 V. FIG. 21 shows the charging-discharging curves of the first two cycles of the battery. It can be found in FIG. 21 that the reversibility of the charging and discharging process of the battery is good, and the battery capacity remains 0.8 mAh or more. When the capacity of first cycle is 0.870 mAh, the specific capacity is 145.0 mAh per gram calculated on the basis of the mass of lithium cobalt oxide (6 mg). When the discharge capacity of the first cycle is 0.707 mAh, the specific capacity is 117.8 mAh per gram calculated on the basis of the mass of lithium cobalt oxide (6 mg). The charge specific capacity and discharge specific capacity of the second cycle are 121.1 mAh per gram and 116.2 mAh per gram, respectively. The reversibility of the battery cycle is good.

[0065] The above experimental results show that the inorganic sulfide electrolyte material provided in the present invention has good air stability, simple preparation method, low production cost, good air stability, and high lithium ion conductivity, and is expected to solve the actual application problem of the inorganic sulfide electrolyte as the electrolyte of a high-performance all-solid-state lithium secondary battery.

[0066] Although the general description and specific embodiments have been used to describe the present invention in detail above, some modifications or improvements can be made on the basis of the present invention, which is obvious to a person skilled in the art. Therefore, all these modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.