SULFIDE SOLID ELECTROLYTE, AND PREPARATION METHOD AND USE THEREOF

Abstract

Provided are a sulfide solid electrolyte, and a preparation method and use thereof. The sulfide solid electrolyte has a chemical composition formula of Li.sub.6P.sub.1-a(M).sub.aS.sub.5X (where M is one or more selected from the group consisting of V, Nb, and Ta, and X is one or more selected from the group consisting of F, Cl, and Br). The preparation method includes: weighing raw materials of a Li source, a P source, an S source, an M source, and an X source, and mixing to be uniform to obtain a mixture, and subjecting the mixture to ball milling to obtain a precursor powder of the sulfide solid electrolyte; sieving the precursor powder to obtain a sieved powder, and then pressing the sieved powder into a solid sheet; and subjecting the solid sheet to vacuum high-temperature sintering to obtain the sulfide solid electrolyte.

Claims

1. A sulfide solid electrolyte, having a chemical composition formula of Li.sub.6P.sub.1-a(M).sub.aS.sub.5X, wherein M is one or more selected from the group consisting of V, Nb, and Ta, and X is one or more selected from the group consisting of F, Cl, and Br.

2. The sulfide solid electrolyte according to claim 1, wherein a is in a range of greater than 0 and less than 1.

3. The sulfide solid electrolyte according to claim 2, wherein the a is in a range of greater than 0 and less than or equal to 0.2.

4. A method for preparing the sulfide solid electrolyte according to claim 1, comprising the following steps: S1, weighing raw materials of a Li source, a P source, an S source, an M source, and an X source according to a stoichiometric ratio of the Li.sub.6P.sub.1-a(M).sub.aS.sub.5X, and then mixing to be uniform to obtain a mixture, and subjecting the mixture to ball milling to obtain a precursor powder of the sulfide solid electrolyte, a being in a range of greater than 0 and less than 1; S2, sieving the precursor powder to obtain a sieved powder, and then pressing the sieved powder into a solid sheet; and S3, subjecting the solid sheet to vacuum high-temperature sintering to obtain the sulfide solid electrolyte.

5. The method according to claim 4, wherein the raw materials in step S1 comprise the following components: the Li source, being one or more selected from the group consisting of LiH, Li.sub.2S.sub.2, and Li.sub.2S; the S source, being one or more selected from the group consisting of S, H.sub.2S, P.sub.2S.sub.5, P.sub.4S.sub.9, P.sub.4S.sub.3, Li.sub.2S.sub.2, and Li.sub.2S; the P source, being one or more selected from the group consisting of P, P.sub.2S.sub.5, P.sub.4S.sub.9, P.sub.4S.sub.3, P.sub.4S.sub.6, and P.sub.4S.sub.5; the X source, being one or more selected from the group consisting of LiCl, LiBr, LiI, LiF, VCl.sub.5, NbCl.sub.5, and TaCl.sub.5; and the M source, being one or more selected from the group consisting of VF.sub.5, NbCl.sub.5, and TaCl.sub.5.

6. The method according to claim 4, wherein the ball milling in step S1 is conducted at a speed of 380 rpm to 1,500 rpm for 7 h to 48 h.

7. The method according to claim 4, further comprising, in step S1, conducting manual grinding for 15 min to 30 min by using an agate mortar before the ball milling.

8. The method according to claim 4, wherein the ball milling in step S1 is conducted by using a planetary ball mill.

9. The method according to claim 4, wherein the sieving in step S2 is conducted by using a sieve of 300 mesh to 1,200 mesh.

10. The method according to claim 4, wherein the pressing in step S2 is conducted at a pressure of 300 MPa to 500 MPa.

11. The method according to claim 4, wherein the solid sheet in step S2 has a thickness of 200 m to 1,000 m.

12. The method according to claim 4, wherein the vacuum high-temperature sintering in step S3 is conducted at a temperature of 350 C. to 700 C. for 1 h to 8 h.

13. The method according to claim 4, wherein step S3 is performed by sealing the solid sheet in a vacuum quartz tube, then placing into a muffle furnace, and conducting high-temperature sintering to obtain the sulfide solid electrolyte.

14. The method according to claim 12, wherein the vacuum high-temperature sintering is conducted at a heating rate of 0.5 C./min to 5 C./min.

15. The method according to claim 4, further comprising, in step S3, cooling to room temperature at a rate of 0.5 C./min to 5 C./min after the vacuum high-temperature sintering is completed.

16. The method according to claim 4, wherein the weighing, the mixing to be uniform, the ball milling, the sieving, the pressing, and the vacuum high-temperature sintering in steps S1 to S3 each are conducted under the protection of an inert atmosphere.

17. (canceled)

18. A solid-state battery, comprising a cathode part, an anode part, and an electrolyte part; wherein at least one of the cathode part, the anode part, and the electrolyte part comprises the sulfide solid electrolyte according to claim 1.

19. The solid-state battery according to claim 18, wherein a weight of the sulfide solid electrolyte in the cathode part accounts for 0 wt % to 40 wt % of a total weight of the cathode part.

20. The solid-state battery according to claim 18, wherein a cathode active material in the cathode part is one or a mixture of two or more selected from the group consisting of LiCoO.sub.2, LiFePO.sub.4, LiNi.sub.xCo.sub.yMn.sub.1-x-yO.sub.2, LiNi.sub.xCo.sub.yAl.sub.1-x-yO.sub.2, LiNi.sub.0.5Mn.sub.1.5O.sub.4, and LiFe.sub.xMn.sub.1-xPO.sub.4.

21. The solid-state battery according to claim 18, wherein the anode part is constructed by mixing an anode active material and a sulfide solid electrolyte, and the anode active material is a lithium alloy anode material, and the sulfide solid electrolyte has a chemical composition formula of Li.sub.6P.sub.1-a(M).sub.aS.sub.5X, M being one or more selected from the group consisting of V, Nb, and Ta, and X being one or more selected from the group consisting of F, Cl, and Br.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 shows cycle efficiency of solid electrolytes prepared in Example 1, Example 2, and Comparative Example 1.

[0039] FIG. 2 shows impedance of solid electrolytes prepared in Example 1 and Comparative Example 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The present disclosure will be described in detail below in conjunction with the drawings and examples. The following examples are implemented on the premise of the technical solution of the present disclosure, and provide detailed implementation modes and specific operating processes, which will help those skilled in the art to further understand the present disclosure. It should be pointed out that the scope of the present disclosure is not limited to the following examples. Those modifications and improvements made based on the concept of the present disclosure shall all belong to the scope of the present disclosure.

EXAMPLE 1

[0041] This example provided a Li.sub.6P.sub.0.8V.sub.0.2S.sub.5F solid electrolyte, which was prepared as follows:

[0042] The reagents Li.sub.2S, P.sub.2S.sub.5, and VF.sub.5 were weighed at a stoichiometric ratio of Li.sub.2S:P.sub.2S.sub.5:VF.sub.5=3:0.4:0.2, then mixed and manually ground for 15 min to obtain a mixture. The mixture was put into a zirconia ball mill jar, and zirconia balls were added thereto at a mass ratio of 1:50. After that, the mixture was subjected to ball milling at a speed of 550 rpm for 17 h; a resulting milled sample attached to the wall of the zirconia ball mill jar was scraped off, then ground manually with a mortar for 15 min, and then sieved through a 400-mesh sieve to obtain a uniformly mixed precursor. The precursor was pressed into a solid sheet (with a diameter of 12 mm) at 350 MPa. The solid sheet was packed into a quartz tube and sealed. The solid sheet was heated to a temperature of 550 C. at a heating rate of 0.5 C./min and held at the temperature for 7 h, and then cooled to obtain the Li.sub.6P.sub.0.8V.sub.0.2S.sub.5F solid electrolyte powder. It can be found from an X-ray diffraction (XRD) that the solid electrolyte powder prepared by this method is in an argyrodite-type cubic phase with desirable crystal form and high purity. The solid electrolyte powder was pressed at a pressure of 580 MPa for 3 min to obtain a solid electrolyte sheet. All the aforementioned preparation processes were conducted under the protection of an argon atmosphere.

[0043] The solid electrolyte sheet has a lithium conductivity of 510.sup.3 S/cm at room temperature. (The alternating-current (AC) impedance of the sulfide electrolyte was determined by using a multi-channel electrochemical workstation at a temperature of 298 K to 375 K and a frequency of 1 MHz to 10 Hz). The cycle efficiency is shown in FIG. 1. As shown in FIG. 1, the full cell has an excellent stability during 50 cycles. The impedance is shown in FIG. 2. As shown in FIG. 2, the solid electrolyte sheet prepared in Example 1 has a high ionic conductivity.

EXAMPLE 2

[0044] This example provided a Li.sub.6P.sub.0.8Ta.sub.0.2S.sub.5F solid electrolyte, which was prepared as follows:

[0045] The reagents Li.sub.2S, P.sub.2S.sub.5, and TaF.sub.5 were weighed at a stoichiometric ratio of Li.sub.2S:P.sub.2S.sub.5:VF.sub.5=3:0.4:0.2, then mixed and manually ground for 15 min to obtain a mixture. The mixture was put into a zirconia ball mill jar, and zirconia balls were added thereto at a mass ratio of 1:50. After that, the mixture was subjected to ball milling at a speed of 550 rpm for 17 h; a resulting milled sample attached to the wall of the zirconia ball mill jar was scraped off, then ground manually with a mortar for 15 min, and then sieved through a 400-mesh sieve to obtain a uniformly mixed precursor. The precursor was pressed into a solid sheet (with a diameter of 12 mm) at 350 MPa. The solid sheet was packed into a quartz tube and sealed. The solid sheet was heated to a temperature of 550 C. at a heating rate of 0.5 C./min and held at the temperature for 7 h, and then cooled to obtain the Li.sub.6P.sub.0.8Ta.sub.0.2S.sub.5F solid electrolyte powder. It can be found from an X-ray diffraction (XRD) that the solid electrolyte powder prepared by this method is in an argyrodite-type cubic phase with desirable crystal form and high purity. The solid electrolyte powder was pressed at a pressure of 580 MPa for 3 min to obtain a solid electrolyte sheet. All the aforementioned preparation processes were completed under the protection of an argon atmosphere. The solid electrolyte sheet has a lithium conductivity of 5.310.sup.3 S/cm at room temperature. (The AC impedance of the sulfide electrolyte was determined by using a multi-channel electrochemical workstation at a temperature of 298 K to 375 K and a frequency of 1 MHz to 10 Hz).

COMPARATIVE EXAMPLE 1

[0046] This example provided a Li.sub.6PS.sub.5F solid electrolyte, which was prepared as follows:

[0047] The reagents Li.sub.2S, P.sub.2S.sub.5, and LiF were weighted at a required stoichiometric ratio then mixed and manually ground for 15 min to obtain a mixture. The mixture was put into a zirconia ball mill jar, and zirconia balls were added thereto at a mass ratio of 1:50. After that, the mixture was subjected to ball milling at a speed of 550 rpm for 17 h; a resulting milled sample attached to the wall of the zirconia ball mill jar was scraped off, then ground manually with a mortar for 15 min, and then sieved through a 400-mesh sieve to obtain a uniformly mixed precursor. The precursor was pressed into a solid sheet (with a diameter of 12 mm) at 350 MPa. The solid sheet was packed into a quartz tube and sealed. The solid sheet was heated to a temperature of 550 C. at a heating rate of 0.5 C./min and held at the temperature for 7 h, and then cooled to obtain the Li.sub.6PS.sub.5F solid electrolyte powder. The solid electrolyte powder was pressed at a pressure of 580 MPa for 3 min to obtain a solid electrolyte sheet. All the aforementioned preparation processes were completed under the protection of an argon atmosphere. The solid electrolyte sheet in Comparative Example 1 has a lithium conductivity of 1.510.sup.3 S/cm at room temperature.

COMPARATIVE EXAMPLE 2

[0048] A Li.sub.6P.sub.0.8Sb.sub.0.2S.sub.5F sulfide solid electrolyte was provided, and the method for preparing the same was conducted similar to Example 1, except that in Comparative Example 2, the raw materials were Li.sub.2S:P.sub.2S.sub.5:SbF.sub.5=3:0.4:0.2.

[0049] The solid electrolyte sheet in Comparative Example 2 has a lithium conductivity of 1.110.sup.3 S/cm at room temperature.

[0050] The specific embodiments of the present disclosure are described above. It should be understood that the present disclosure is not limited to the above specific embodiments, and a person skilled in the art could make various variations or modifications within the scope of the claims without affecting the essence of the present disclosure.