Sodium ion sulfide solid electrolyte and preparation method and application thereof

Abstract

The invention relates to a sodium ion sulfide solid electrolyte and a preparation method and application thereof, the stoichiometric formula of the sodium ion sulfide solid electrolyte is Na3-x-ySb1-xWxS4-yFy, 0 < x < = 0.05, and 0 < y < = 0.05. Compared with the prior art, the sodium ion sulfide solid electrolyte material prepared by co-doping the tungsten element and the fluorine element is relatively high in room-temperature ionic conductivity and relatively good in contact stability with a negative electrode interface in total battery application, the transmission performance of sodium ions in a battery is greatly improved, and the sodium ion sulfide solid electrolyte material has a great application prospect.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a sodium ion sulfide solid electrolyte and a preparation method and application thereof. Background Art

[0002] Sodium-ion batteries (SIBs) are considered a potential alternative to lithium-ion batteries due to their abundant resources and low cost, particularly in large-scale energy storage. However, the flammability, low thermal stability, and dendrite growth of traditional liquid electrolytes have limited their development. All-solid-state batteries, by replacing liquid electrolytes with solid-state electrolytes, could significantly improve safety, energy density, and cycle life.

[0003] However, the conventional sodium ion solid electrolyte Na3SbS4 in the prior art has a low ionic conductivity, usually around 10 -4 S / cm2 is on the order of magnitude, which is difficult to meet the needs of high-power batteries; and the air stability is poor, and it is easily hydrolyzed in humid air to produce H2S and NaOH, causing material decomposition; the interface compatibility is poor, and the interface impedance with the electrode material (Na metal negative electrode or high-voltage positive electrode) is large, which is prone to side reactions and forms an unstable solid electrolyte interface film. Summary of the Invention

[0004] The present invention aims to improve the low ionic conductivity, poor air stability, and high interfacial resistance with electrode materials of sodium-ion solid electrolytes, thereby providing a sodium-ion sulfide solid electrolyte and its preparation method and application. The present invention effectively solves the core problems of sodium-ion solid electrolytes, such as low ionic conductivity, poor air stability, and high interfacial resistance with electrode materials, through doping technology.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a sodium ion sulfide solid electrolyte, the stoichiometric formula of which is Na 3-x-y Sb 1-x W x S 4-y F y , where 0<x≤0.05, 0<y≤0.05.

[0007] Preferably, x is 0.05 and y is 0.01.

[0008] A second technical solution of the present invention is to provide a method for preparing the sodium ion sulfide solid electrolyte as described in one of the above technical solutions, comprising the following steps:

[0009] S1. Weigh Na2S, Sb2S3, S, WS2, and NaF raw materials according to the stoichiometric ratio, grind and mix the raw materials evenly to obtain powder;

[0010] S2. Pressing the powder obtained in step S1 into a sheet to obtain an electrolyte precursor sheet;

[0011] S3. The electrolyte precursor sheet obtained in step S2 is sealed in a quartz glass tube and sintered to obtain a sodium ion sulfide solid electrolyte.

[0012] In some specific embodiments, in step S1, the environment in which the raw materials are ground and mixed to obtain powder is an inert atmosphere.

[0013] More preferably, the inert atmosphere includes argon, nitrogen, etc.

[0014] In some specific embodiments, in step S1, after grinding and mixing the raw materials, ball milling is further performed. The ball-to-material ratio during ball milling is 20:1 to 30:1, and the particle size of the ball milling beads is 5 to 10 mm.

[0015] In some specific embodiments, the ball milling speed is 500-550 rpm, and the time is 15-20 h.

[0016] In some specific embodiments, in step S2, the pressing pressure is 130-200 MPa.

[0017] In some specific embodiments, in step S3, the electrolyte precursor sheet is sealed in a quartz glass tube and then vacuumed to create a vacuum environment in the quartz glass tube.

[0018] In some specific embodiments, in step S3, the sintering temperature is 420-450°C, the sintering time is 5-10 hours, and the heating rate is 1-2°C / min.

[0019] A third technical solution of the present invention is to provide a use of the sodium ion sulfide solid electrolyte as described in one of the above technical solutions in the preparation of a sodium ion battery.

[0020] A fourth technical solution of the present invention is to provide a sodium ion battery, comprising the sodium ion sulfide solid electrolyte, a positive electrode and a negative electrode as described in one of the above technical solutions.

[0021] In some specific embodiments, the positive electrode is selected from any one of TiS2, FeS2, and Na2S, and the negative electrode is selected from any one of Na metal and Na-Sn alloy.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The sodium ion sulfide solid electrolyte material prepared by co-doping tungsten and fluorine elements in the present invention has high ionic conductivity. In full battery applications, it has good interface contact stability with the negative electrode, greatly improving the sodium ion transmission performance in the battery, and has great application prospects.

[0024] (2) By introducing high-valent cation W 6+ Replace part of Sb 5+ , so that the ionic conductivity from 10 -4 The order of magnitude is increased to 10 -3 Order of magnitude.

[0025] (3) F doping can effectively isolate water molecules and inhibit the hydrolysis reaction of Na3SbS4, thereby improving the stability of Na3SbS4 in air.

[0026] (4) In a full battery, F in the electrolyte - With Na in the negative electrode + It can form strong ionic bonds, stabilize the interface between the electrolyte and the electrode, and reduce interfacial side reactions and impedance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The electrochemical impedance spectroscopy diagrams of the 0.01F0.05W-NSS solid electrolyte of Example 1 at different temperatures are shown;

[0028] Figure 2 The electrochemical impedance spectroscopy diagrams of the 0.02F0.05W-NSS solid electrolyte of Example 2 at different temperatures are shown;

[0029] Figure 3 The electrochemical impedance spectroscopy diagrams of the 0.04F0.05W-NSS solid electrolyte of Example 4 at different temperatures are shown;

[0030] Figure 4 The electrochemical impedance spectroscopy diagrams of the 0.05F0.05W-NSS solid electrolyte of Example 5 at different temperatures are shown;

[0031] Figure 5 The electrochemical impedance spectroscopy diagrams of the NSS solid electrolyte of Comparative Example 1 at different temperatures are shown;

[0032] Figure 6 Comparison of ionic conductivity of solid electrolytes at different W and F doping concentrations;

[0033] Figure 7 1 is a graph showing the stability test results of the electrolytes of Example 1 and Comparative Example 1 in air;

[0034] Figure 81 is a battery capacity-voltage curve of a TiS2 / Na3SbS4 / Na battery made of the solid electrolyte NSS of Comparative Example 1;

[0035] Figure 9 TiS2 / Na2O3 prepared from the solid electrolyte 0.01F0.05W-NSS of Example 1 2.94 Sb 0.95 W 0.05 S 3.99 F 0.01 Battery capacity-voltage curve of / Na battery. DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0037] In the following examples and comparative examples, unless otherwise specified, raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0038] Example 1

[0039] This embodiment provides a Na 3-x-y Sb 1-x W x S 4-y F y A sodium ion sulfide solid electrolyte and a preparation method thereof, wherein x=0.05, y=0.01, denoted as 0.01F0.05W-NSS.

[0040] (1)Na 3-x-y Sb 1-x W x S 4-y F y Where x = 0.05 and y = 0.01, in a glove box filled with argon atmosphere, Na2S, Sb2S3, S, NaF, and WS2 raw materials were weighed according to the stoichiometric ratio and transferred to a mortar and ground manually to mix the raw materials evenly;

[0041] (2) Weigh 5 mm zirconia ball mill beads at a ball-to-material ratio of 20:1, and transfer the ground and mixed powder into a zirconia ball mill jar;

[0042] (3) The zirconia ball mill was taken out of the glove box and placed on a planetary ball mill. The ball mill was operated at 500 rpm for 20 hours to obtain the electrolyte precursor powder. The electrolyte powder was transferred from the ball mill to the glove box for scraping treatment every 10 hours.

[0043] (4) After the process (3) is completed, the material in the ball mill is taken out and placed into a circular tablet mold with a diameter of 20 mm, and pressed into a circular tablet at a pressure of 130 MPa;

[0044] (5) The electrolyte precursor sheet in (4) is placed in a quartz glass tube with a diameter of 14 mm, and the precursor is sealed in the quartz tube under vacuum using a vacuum tube sealing machine;

[0045] (6) The quartz glass tube of (5) was placed in a muffle furnace for sintering, and a heating program was set with a heating rate of 2°C / min. Four groups of controls were set and sintered at 420°C, 430°C, 440°C and 450°C for 5 hours respectively. After that, the tube was naturally cooled to room temperature to obtain a 0.01F0.05W-NSS solid electrolyte.

[0046] (7) The 0.01F0.05W-NSS solid electrolyte sintered in (6) was transferred to a glove box, and the crystals were ground using an agate mortar to obtain 0.01F0.05W-NSS solid electrolyte powder, which was placed in a sample bottle and stored in the glove box.

[0047] Example 2

[0048] This embodiment provides a Na 3-x-y Sb 1-x W x S 4-y F y A sodium ion sulfide solid electrolyte and a preparation method thereof, wherein x=0.05, y=0.02, denoted as 0.02F0.05W-NSS.

[0049] (1)Na 3-x-y Sb 1-x W x S 4-y F y Where x = 0.05 and y = 0.02, in a glove box filled with argon atmosphere, Na2S, Sb2S3, S, NaF, and WS2 raw materials were weighed according to the stoichiometric ratio and transferred to a mortar and ground manually to mix the raw materials evenly;

[0050] (2) Weigh a certain amount of 5mm zirconia ball milling beads at a ball-to-material ratio of 20:1, and transfer the ground and mixed powder into a zirconia ball mill;

[0051] (3) The zirconia ball mill was taken out of the glove box and placed on a planetary ball mill. The mill was operated at 510 rpm for 15 hours to obtain the electrolyte precursor powder. The electrolyte powder was transferred from the ball mill to the glove box for scraping every 10 hours.

[0052] (4) After the process (3) is completed, the material in the ball mill is taken out and placed into a circular tablet mold with a diameter of 20 mm, and pressed into a circular tablet at a pressure of 130 MPa;

[0053] (5) The electrolyte precursor sheet in (4) is placed in a quartz glass tube with a diameter of 14 mm, and the precursor is sealed in the quartz tube under vacuum using a vacuum tube sealing machine;

[0054] (6) The quartz glass tube of (5) was placed in a muffle furnace for sintering, and a heating program was set with a heating rate of 2°C / min. Three groups of controls were set up, and they were sintered at 420°C, 430°C, and 440°C for 5 hours, respectively, and then naturally cooled to room temperature to obtain 0.02F0.05W-NSS solid electrolyte;

[0055] (7) The 0.02F0.05W-NSS solid electrolyte sintered in (6) was transferred to a glove box, and the crystals were ground using an agate mortar to obtain 0.02F0.05W-NSS solid electrolyte powder, which was placed in a sample bottle and stored in the glove box.

[0056] Example 3

[0057] This embodiment provides a Na 3-x-y Sb 1-x W x S 4-y F y A sodium ion sulfide solid electrolyte and a preparation method thereof, wherein x=0.05, y=0.03, denoted as 0.03F0.05W-NSS.

[0058] (1)Na 3-x-y Sb 1-x W x S 4-y F y Where x = 0.05 and y = 0.03, in a glove box filled with argon atmosphere, Na2S, Sb2S3, S, NaF, and WS2 raw materials were weighed according to the stoichiometric ratio and transferred to a mortar and ground manually to mix the raw materials evenly;

[0059] (2) Weigh a certain amount of 5mm zirconia ball milling beads at a ball-to-material ratio of 20:1, and transfer the ground and mixed powder into a zirconia ball mill;

[0060] (3) The zirconia ball mill was taken out of the glove box and placed on a planetary ball mill. The ball mill was operated at 500 rpm for 20 hours to obtain the electrolyte precursor powder. The electrolyte powder was transferred from the ball mill to the glove box for scraping treatment every 10 hours.

[0061] (4) After the process (3) is completed, the material in the ball mill is taken out and placed into a circular tablet mold with a diameter of 20 mm, and pressed into a circular tablet at a pressure of 130 MPa;

[0062] (5) The electrolyte precursor sheet in (4) is placed in a quartz glass tube with a diameter of 14 mm, and the precursor is sealed in the quartz tube under vacuum using a vacuum tube sealing machine;

[0063] (6) The quartz glass tube of (5) was placed in a muffle furnace for sintering, and a heating program was set with a heating rate of 2°C / min. Three groups of controls were set up, and they were sintered at 420°C, 430°C, and 440°C for 5 hours, respectively. After that, they were naturally cooled to room temperature to obtain 0.03F0.05W-NSS solid electrolyte;

[0064] (7) The 0.03F0.05W-NSS solid electrolyte sintered in (6) was transferred to a glove box, and the crystals were ground using an agate mortar to obtain 0.03F0.05W-NSS solid electrolyte powder, which was placed in a sample bottle and stored in the glove box.

[0065] Example 4

[0066] This embodiment provides a Na 3-x-y Sb 1-x W x S 4-y F y A sodium ion sulfide solid electrolyte and a preparation method thereof, wherein x=0.05, y=0.04, denoted as 0.04F0.05W-NSS.

[0067] (1)Na 3-x-y Sb 1-x W x S 4-y F y Where x = 0.05 and y = 0.04, in a glove box filled with argon atmosphere, Na2S, Sb2S3, S, WS2, and NaF raw materials were weighed according to the stoichiometric ratio and transferred to a mortar and ground manually to mix the raw materials evenly;

[0068] (2) Weigh a certain amount of 5mm zirconia ball milling beads at a ball-to-material ratio of 20:1, and transfer the ground and mixed powder into a zirconia ball mill;

[0069] (3) The zirconia ball mill was taken out of the glove box and placed on a planetary ball mill. The ball mill was operated at 500 rpm for 20 hours to obtain the electrolyte precursor powder. The electrolyte powder was transferred from the ball mill to the glove box for scraping treatment every 10 hours.

[0070] (4) After the process (3) is completed, the material in the ball mill is taken out and placed into a circular tablet mold with a diameter of 20 mm, and pressed into a circular tablet at a pressure of 130 MPa;

[0071] (5) The electrolyte precursor sheet in (4) is placed in a quartz glass tube with a diameter of 14 mm, and the precursor is sealed in the quartz tube under vacuum using a vacuum tube sealing machine;

[0072] (6) The quartz glass tube of (5) was placed in a muffle furnace for sintering, and a heating program was set with a heating rate of 2°C / min. Three groups of controls were set up, and they were sintered at 420°C, 430°C, and 440°C for 5 hours, respectively. After that, they were naturally cooled to room temperature to obtain 0.04F0.05W-NSS solid electrolyte;

[0073] (7) The 0.04F0.05W-NSS solid electrolyte sintered in (6) was transferred to a glove box, and the crystals were ground using an agate mortar to obtain 0.04F0.05W-NSS solid electrolyte powder, which was placed in a sample bottle and stored in the glove box.

[0074] Example 5

[0075] This embodiment provides a Na 3-x-y Sb 1-x W x S 4-y F y A sodium ion sulfide solid electrolyte and a preparation method thereof, wherein x=0.05, y=0.05, denoted as 0.05F0.05W-NSS.

[0076] (1)Na 3-x-y Sb 1-x W x S 4-y F y , x = 0.05 and y = 0.05. In a glove box filled with argon atmosphere, Na2S, Sb2S3, S, NaF, and WS2 raw materials were weighed according to the stoichiometric ratio and transferred to a mortar and ground manually to mix the raw materials evenly;

[0077] (2) Weigh a certain amount of 5mm zirconia ball milling beads at a ball-to-material ratio of 20:1, and transfer the ground and mixed powder into a zirconia ball mill;

[0078] (3) The zirconia ball mill was taken out of the glove box and placed on a planetary ball mill. The ball mill was operated at 500 rpm for 20 hours to obtain the electrolyte precursor powder. The electrolyte powder was transferred from the ball mill to the glove box for scraping treatment every 10 hours.

[0079] (4) After the process (3) is completed, the material in the ball mill is taken out and placed into a circular tablet mold with a diameter of 20 mm, and pressed into a circular tablet at a pressure of 130 MPa;

[0080] (5) The electrolyte precursor sheet in (4) is placed in a quartz glass tube with a diameter of 14 mm, and the precursor is sealed in the quartz tube under vacuum using a vacuum tube sealing machine;

[0081] (6) The quartz glass tube of (5) was placed in a muffle furnace for sintering, and a heating program was set with a heating rate of 2°C / min. Three groups of controls were set up, and they were sintered at 420°C, 430°C, and 44°C for 5 hours respectively. After that, they were naturally cooled to room temperature to obtain 0.05F0.05W-NSS solid electrolyte;

[0082] (7) The 0.05F0.05W-NSS solid electrolyte sintered in (6) was transferred to a glove box, and the crystals were ground using an agate mortar to obtain 0.05F0.05W-NSS solid electrolyte powder, which was placed in a sample bottle and stored in the glove box.

[0083] Comparative Example 1

[0084] This comparative example provides a Na3SbS4 solid electrolyte (referred to as NSS solid electrolyte) and a preparation method thereof, comprising the following steps:

[0085] (1) In a glove box filled with argon atmosphere, Na2S, Sb2S3, and S raw materials were weighed according to the stoichiometric ratio and transferred to a mortar and ground manually to mix the raw materials uniformly;

[0086] (2) Weigh a certain amount of 5mm zirconia ball milling beads at a ball-to-material ratio of 20:1, and transfer the ground and mixed powder into a zirconia ball mill;

[0087] (3) The zirconia ball mill was taken out of the glove box and placed on a planetary ball mill. The ball mill was operated at 500 rpm for 20 hours to obtain the electrolyte precursor powder. The electrolyte powder was transferred from the ball mill to the glove box for scraping treatment every 10 hours.

[0088] (4) After the process (3) is completed, the material in the ball mill is taken out and placed into a circular tablet mold with a diameter of 20 mm, and pressed into a circular tablet at a pressure of 130 MPa;

[0089] (5) The electrolyte precursor sheet in (4) is placed in a quartz glass tube with a diameter of 14 mm, and the precursor is sealed in the quartz tube under vacuum using a vacuum tube sealing machine;

[0090] (6) The quartz glass tube of (5) was placed in a muffle furnace for sintering, and a heating program was set with a heating rate of 2°C / min. The tube was sintered at 430°C for 5 hours, and then naturally cooled to room temperature to obtain an NSS solid electrolyte.

[0091] (7) The NSS solid electrolyte sintered in (6) was transferred to a glove box, and the crystals were ground using an agate mortar to obtain NSS solid electrolyte powder, which was then placed in a sample bottle and stored in the glove box.

[0092] Test Example 1: Ionic Conductivity

[0093] 100 mg of the solid electrolyte powder obtained in each embodiment and comparative example was weighed and placed in a tableting mold with a diameter of 10 mm. The solid electrolyte powder was tableted at a pressure of 360 MPa, and the stainless steel at both ends of the mold was used as the blocking electrode of the electrolyte sheet. The EIS of the electrolyte sample was analyzed using an EClab electrochemical workstation, and the frequency scan range was set between 7 MHz and 1 Hz. The ionic conductivity was calculated according to the formula σ = L / (R * S), where σ represents the ionic conductivity of the solid electrolyte, L represents the thickness of the electrolyte sheet, S represents the area of ​​the electrolyte sheet, and R is the resistance value obtained by the AC impedance test.

[0094] like Figure 1 The following are electrochemical impedance spectroscopy (EIS) diagrams of the 0.01F0.05W-NSS solid electrolyte prepared in Example 1 at different temperatures, from which the ionic conductivity at different sintering temperatures can be calculated. When the sintering temperature is 420°C, the ionic conductivity is 9.13mS / cm; when the sintering temperature is 430°C, the ionic conductivity is 11mS / cm; when the sintering temperature is 440°C, the ionic conductivity is 4.7mS / cm; when the sintering temperature is 450°C, the ionic conductivity is 7.4mS / cm. In the subsequent assembly of all-solid-state sodium ion batteries, the electrolyte material with the best ionic conductivity at room temperature is selected for testing.

[0095] like Figure 2 The following are EIS graphs of the 0.02F0.05W-NSS solid electrolyte prepared in Example 2 at different temperatures, from which the ionic conductivity at different sintering temperatures can be calculated. When the sintering temperature is 420°C, the ionic conductivity is 3.06mS / cm; when the sintering temperature is 430°C, the ionic conductivity is 4.3mS / cm; and when the sintering temperature is 440°C, the ionic conductivity is 4.7mS / cm.

[0096] like Figure 3Figure 2 shows the EIS graphs of the 0.04F0.05W-NSS solid electrolyte prepared in Example 4 at different temperatures. From this, the ionic conductivity at different sintering temperatures can be calculated. When the sintering temperature is 420°C, the ionic conductivity is 2.83 mS / cm; when the sintering temperature is 430°C, the ionic conductivity is 3.4 mS / cm; and when the sintering temperature is 440°C, the ionic conductivity is 4.18 mS / cm.

[0097] like Figure 4 The following are EIS plots of the 0.05F0.05W-NSS solid electrolyte prepared in Example 5 at different temperatures. From these, the ionic conductivity at different sintering temperatures can be calculated. At 420°C, the ionic conductivity is 3.6 mS / cm; at 430°C, the ionic conductivity is 1.82 mS / cm; and at 440°C, the ionic conductivity is 4.19 mS / cm.

[0098] like Figure 5 , which is the electrochemical impedance spectroscopy diagram of the solid electrolyte NSS prepared in Comparative Example 1, and the calculated ionic conductivity of the NSS at a sintering temperature of 430° C. is 0.9 mS / cm.

[0099] like Figure 6 As shown in the figure, it is a comparison chart of the optimal ionic conductivity under different W and F element doping concentrations. It can be concluded that the room temperature ionic conductivity of 0.01F0.05W-NSS obtained after annealing at 430°C is the highest. Subsequently, it is used as the electrolyte material for full battery testing to compare the full battery effect with Comparative Example 1.

[0100] Test Example 2: Stability test in air

[0101] The electrolyte powders prepared in Example 1 and Comparative Example 1 were exposed to air for 15 minutes, and then the tablets were placed back into the test mold for EIS testing using the same method as in Test Example 1. The ionic conductivity was calculated and compared before and after exposure to air. Figure 7 As shown, the ion conductivity decrease rate of Comparative Example 1 is about 50%, while the ion conductivity decrease rate of Example 1 is 8%, which is significantly lower than that of Comparative Example 1. It can be seen that the air stability of Example 1 is significantly better than that of Comparative Example 1.

[0102] Test Example 3-All-solid-state battery electrochemical performance test

[0103] To further test the application of electrolytes in all-solid-state batteries, the solid electrolyte NSS of Comparative Example 1 and the solid electrolyte 0.01F0.05W-NSS of Example 1 were used to assemble all-solid-state batteries TiS2 / Na3SbS4 / Na and TiS2 / Na 2.94 Sb0.95 W 0.05 S 3.99 F 0.01 / Na full battery, with TiS2 as the positive electrode and Na as the negative electrode. Because the positive electrode is TiS2, which is a sulfide positive electrode material, discharge is performed first during full battery testing to ensure that the sodium ions in the negative electrode are transferred to the positive electrode side.

[0104] like Figure 8 As shown, it is the battery capacity-voltage curve of TiS2 / Na3SbS4 / Na battery; Figure 9 As shown, it is TiS2 / Na 2.94 Sb 0.95 W 0.05 S 3.99 F 0.01 The battery capacity-voltage curve of the TiS2 / Na3SbS4 / Na battery shows that the first discharge capacity is lower (148mAh / g), while the TiS2 / Na 2.94 Sb 0.95 W 0.05 S 3.99 F 0.01 / Na has a high first discharge specific capacity (172mAh / g), so for Na3SbS4, the solid electrolyte Na 2.94 Sb 0.95 W 0.05 S 3.99 F 0.01 The interface contact with the metal Na negative electrode is more stable.

[0105] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A sodium ion sulfide solid electrolyte, characterized in that Its stoichiometric formula is Na 3-x-y Sb 1-x W x S 4-y F y , where 0<x≤0.05, 0<y≤0.

05.

2. A method for preparing the sodium ion sulfide solid electrolyte according to claim 1, characterized in that: The steps include: S1. Weigh Na2S, Sb2S3, S, WS2, and NaF raw materials according to the stoichiometric ratio, grind and mix the raw materials evenly to obtain powder; S2. Pressing the powder obtained in step S1 into a sheet to obtain an electrolyte precursor sheet; S3. The electrolyte precursor sheet obtained in step S2 is sealed in a quartz glass tube and sintered to obtain a sodium ion sulfide solid electrolyte.

3. The preparation method according to claim 2, characterized in that In step S1, the raw materials are ground and mixed to obtain powder in an inert atmosphere.

4. The preparation method according to claim 2, characterized in that In step S1, after grinding and mixing the raw materials, ball milling is performed. The ball-to-material ratio during ball milling is 20:1 to 30:1, the particle size of the ball milling beads is 5 to 10 mm, the ball milling speed is 500 to 550 rpm, and the time is 15 to 20 hours.

5. The preparation method according to claim 2, characterized in that In step S2, the pressing pressure is 130-200 MPa.

6. The preparation method according to claim 2, characterized in that In step S3 , the electrolyte precursor sheet is sealed in a quartz glass tube and then vacuumed to create a vacuum environment in the quartz glass tube.

7. The preparation method according to claim 2, characterized in that In step S3, the sintering temperature is 420-450° C., the sintering time is 5-10 hours, and the heating rate is 1-2° C. / min.

8. Use of the sodium ion sulfide solid electrolyte according to claim 1 in preparing a sodium ion battery.

9. A sodium ion battery, characterized in that: It comprises the sodium ion sulfide solid electrolyte, a positive electrode and a negative electrode as described in one of the above technical solutions.

10. The sodium ion battery according to claim 9, characterized in that The positive electrode is selected from any one of TiS2, FeS2, and Na2S, and the negative electrode is selected from any one of Na metal and Na-Sn alloy.

Images