A low-cost preparation method for water-phase synthesis of modified sodium-ion sulfide solid-state electrolyte

Abstract

The application discloses a low-cost preparation method of a water-phase synthesis modified sodium ion sulfide solid-state electrolyte, and belongs to the technical field of sodium ion batteries. The low-cost sodium sulfide nonahydrate is used to replace the expensive anhydrous sodium sulfide as raw material, and the water phase is used to avoid the production risk caused by the thermal evaporation of the organic solvent and the influence on the sample purity. Compared with the traditional solid-phase mechanical chemical method for synthesizing the sodium ion sulfide solid-state electrolyte, the production cost is reduced, and the large-batch preparation is realized, so that the method has a good commercialization prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sodium ion batteries, in particular to a low-cost preparation method for water-phase synthesis of modified sodium ion sulfide solid electrolyte. BACKGROUND

[0002] Lithium ion batteries are an important part of modern life and have been widely used in electric power, new energy vehicles and clean energy storage. The rising price of lithium and the abundant reserves of sodium have become one of the choices to replace lithium ion batteries. The liquid electrolyte of the traditional sodium ion battery uses ester organic compounds, which are extremely flammable under high temperature or collision conditions, so using solid electrolyte with excellent thermal stability and strong mechanical quality to replace liquid electrolyte is an important way to improve safety performance. Current research on sodium ion solid electrolyte mainly focuses on Na3PS, Na7PS6, Na3SbS4, Na 11 Sn2PS 12 , Na 10 GeP2S 12 and their doped derivatives. However, current sodium ion sulfide solid electrolyte needs to use high-priced and low-purity anhydrous Na2S as raw material and uses mechanical chemical ball milling for synthesis, which greatly limits its commercial application.

[0003] Therefore, how to prepare a high-performance sodium ion solid electrolyte at low cost has become a key to the development of the next generation of sodium ion batteries. SUMMARY

[0004] In view of the above shortcomings of the prior art, the purpose of the present application is to provide a low-cost preparation method for water-phase synthesis of modified sodium ion sulfide solid electrolyte, which aims to solve the problem that the current sodium ion sulfide solid electrolyte needs to use high-priced and low-purity anhydrous Na2S as raw material and uses mechanical chemical ball milling for synthesis, which greatly limits its commercial application.

[0005] The technical scheme of the present application is as follows:

[0006] A low-cost preparation method for water-phase synthesis of modified sodium ion sulfide solid electrolyte, wherein the modified sodium ion sulfide solid electrolyte is Na 3-x-y Sb 1-x A x S 4-y B y , wherein 0 3-x-y Sb 1-x A x S 4-y By The preparation method of the compound of formula (I) comprises the following steps:

[0007] (1) dissolving Na2S·9H2O in water to obtain a sodium sulfide solution;

[0008] (2) adding sublimed sulfur to the sodium sulfide solution obtained in step (1) until the sulfur is completely dissolved to obtain a sodium polysulfide solution;

[0009] (3) adding Sb2O3 to the sodium polysulfide solution obtained in step (2) and stirring to obtain a Na3SbS4 solution;

[0010] (4) adding an oxide of A and a Na salt of B to the sodium sulfide solution prepared according to step (1) and stirring;

[0011] (5) mixing the solutions obtained in steps (3) and (4) and stirring, and then sequentially performing ice bath, filtration, washing, and drying on the stirred solution to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

[0012] Optionally, the molar ratio of Na2S·9H2O to water in step (1) is 1: 6-8. Na2S·9H2O is added to the water in step (1), and the molar ratio of C Na = 6.5-8 mol / L in the sodium sulfide solution.

[0013] Optionally, the molar ratio of sublimed sulfur to the sodium sulfide solution in step (1) is 1: 6-8.

[0014] Optionally, the filtration in step (3) is performed using filter paper with a pore size of ≤4 μm, and the filtration in step (5) is performed using filter paper with a pore size of ≤4 μm.

[0015] Optionally, the oxide of A in step (4) is at least one of WO3, MoO3, SnO2, SiO2, TiO2, GeO2, ZnO2, and MnO2, and the Na salt of B is at least one of NaF, NaCl, NaBr, and Nal.

[0016] Optionally, before the ice bath in step (5), isopropanol is added to the stirred solution.

[0017] Optionally, the temperature of the ice bath in step (5) is 0-5°C, and the ice bath time is 1-2 h.

[0018] Optionally, the Na 3-x-y Sb 1-x A x S​4-y B y • 9H2O crystals are washed with 10-20 wt% NaOH solution.

[0019] Optionally, step (5) washes the obtained Na 3-x-y Sb 1-x A x S 4-y B y • 9H2O crystals are vacuum dried at 60-100°C for 12-15h, followed by vacuum heating at 150-200°C for 8-10h to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

[0020] Beneficial effects: The present application uses low-priced sodium sulfide nonahydrate to replace expensive anhydrous sodium sulfide as raw material, and uses aqueous phase to avoid the production risk caused by organic solvent thermal evaporation and the influence on product purity, and solves the problem of low yield of traditional mechanical chemical ball milling synthesis, realizes the reduction of production cost of sodium ion sulfide solid electrolyte, the method is simple and efficient, the process equipment is simple, easy to batch production, and has good commercialization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 SEM image of Na 2.88 Sb 0.88 W 0.12 S4 (Example 1).

[0022] Figure 2 SEM image of Na 2.88 Sb 0.88 W 0.12 S4 (Example 1), Na3SbS4 (Comparative Example 1) and NIS-Na 2.88 Sb 0.88 W 0.12 S4 (Comparative Example 2).

[0023] Figure 3 XRD pattern of Na 2.88 Sb 0.88 W 0.12 S4 (Example 1), Air-exposed Na 2.88 Sb 0.88 W 0.12 S4 (Example 1 air-exposed water absorption product) and Reheated Na 2.88 Sb 0.88 W 0.12 S4 (Comparative Example 3).

[0024] Figure 4 Na 2.88 Sb 0.88 W 0.12 S4(Example 1), Na3SbS4(Comparative Example 1), NIS-Na 2.88 Sb 0.88 W 0.12 S4(Comparative Example 2), Reheated Na 2.88 Sb 0.88 W 0.12 S4(Comparative Example 3), NER-Na 2.88 Sb 0.88 W 0.12 S4(Comparative Example 4), Na 2.94 Sb 0.94 W 0.06 S4(Comparative Example 5) and Na 2.82 Sb 0.82 W 0.18 S4(Comparative Example 6). DETAILED DESCRIPTION

[0025] The present application provides a low-cost preparation method for aqueous synthesis of modified sodium ion sulfide solid-state electrolyte. In order to make the purpose, technical scheme and effect of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0026] The present application provides a low-cost preparation method for aqueous synthesis of modified sodium ion sulfide solid-state electrolyte. In order to make the purpose, technical scheme and effect of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. 3-x-y Sb 1-x A x S 4-y B y , wherein 0 3-x-y Sb 1- x A x S 4-y B y The preparation method of the Na

[0027] (1) dissolving Na2S·9H2O in water to obtain a sodium sulfide solution;

[0028] (2) adding sublimed sulfur to the sodium sulfide solution obtained in step (1) until the sulfur is completely dissolved, to obtain a sodium polysulfide solution;

[0029] (3) adding Sb2O3 into the polysulfide sodium solution obtained in step (2), stirring, and filtering to obtain a Na3SbS4 solution;

[0030] (4) adding the oxide of A and the Na salt of B into the sodium sulfide solution re-prepared according to step (1), and stirring;

[0031] (5) mixing the solutions obtained in steps (3) and (4) after stirring, and sequentially performing ice bath, filtering, washing, and drying on the stirred solution to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

[0032] The preparation process is described by taking Na 2.88 Sb 0.88 W 0.12 S4 as an example. First, steps (1), (2), and (3) are to synthesize Na3SbS4 according to 6Na2S+2S+Sb2O3+3H2O→2Na3SbS4+6NaOH, wherein Sb2O3 is easy to react with Na2S to generate Na3SbS3 (Sb2O3+6Na2S+3H2O→2Na3SbS3+6NaOH), and sublimed sulfur is not easy to participate in the reaction to generate Na3SbS4, so the sublimed sulfur is dissolved in the sodium sulfide solution to form polysulfide sodium, so as to reduce the generation of by-products and improve the utilization rate of sublimed sulfur; step (4) is to synthesize Na2WS4 according to WO3+2NaOH→Na2WO4+H2O and Na2WO4+4Na2S+4H2O→Na2WS4, wherein NaOH is generated by the hydrolysis of Na2S; finally, step (5) is to obtain the target product according to 0.12Na2WS4+0.88Na3SbS4→Na 2.88 Sb 0.88 W 0.12 S4 by mixing the two substances obtained above.

[0033] The embodiment of the present application uses common low-valence sodium source sodium sulfide nine hydrates to replace anhydrous sodium sulfide as raw materials, reduces the preparation cost of sodium sulfide solid electrolyte, avoids the production risk caused by the thermal evaporation of organic solvents and the influence on the purity of products in the aqueous phase, solves the problem of low yield in the traditional mechanical chemical ball milling synthesis, and has the advantages of simple method, high efficiency, simple process equipment, easy batch production, and good commercialization prospect. In addition, the partial replacement and doping of Sb and S in Na3SbS4 can insert defects in the structure of Na3SbS4, so that the solid electrolyte with higher ion conductivity than Na3SbS4 can be obtained.

[0034] The modified sodium sulfide solid electrolyte is Na 3-x-ySb 1-x A x S 4-y B y wherein 0 < x < 1, 0≤y<3, A is at least one of W, Mo, Sn, Si, Ti, Ge, Zn, Mn, and B is at least one of F, Cl, Br, and I. As an example, the Na 3-x-y Sb 1-x A x S 4-y B y may be Na 2.88 Sb 0.88 W 0.12 S4, Na 2.54 Sb 0.94 W 0.06 S 3.6 Cl 0.4 , Na 2.32 Sb 0.92 Mo 0.08 S 3.4 Br 0.6 , Na 2.32 Sb 0.92 Mo 0.08 S 3.4 Br 0.3 I 0.3 , Na 3.1 Sb 0.9 Si 0.1 S4, Na 3.2 Sb 0.8 Ti 0.2 S4, Na 2.7 SbS 3.7 Br 0.3 , Na 3.3 Sb 0.7 Sn 0.2 Ge 0.1 S4, Na 2.8 Sb 0.8 Ti 0.1 Ge 0.1 S 3.6 F 0.3 Br 0.1 , etc.

[0035] In one embodiment, step (1) specifically comprises dissolving Na2S·9H2O in deionized water at 70-90°C to prepare a sodium sulfide solution.

[0036] In one embodiment, the molar ratio n Na2S·9H2O ∶n Sb2O3= (6-6.2): 1 Na2S-9H2O is added to the water in step (1). Since Sb2O3 will react with sodium polysulfide solution after being added, and the side reaction will generate NaSb(OH)6 precipitate (Sb2O3+6Na2S+3H2O→2Na3SbS3+6NaOH, 2Na3SbS3+2NaOH+3H2O→2NaSb(OH)6↓+3Na2S2O3), by adding appropriate excess Na2S-9H2O, NaSb(OH)6 can be converted back to Na3SbS4 (NaSb(OH)6+4Na2S→Na3SbS4+6NaOH).

[0037] In one embodiment, the concentration of C Na = 6.5-8 mol / L.

[0038] In one embodiment, step (2) specifically comprises: adding sublimed sulfur to the sodium sulfide solution obtained in step (1) in a set ratio, stirring at a temperature of 70-90°C until the sulfur is completely dissolved, to obtain a sodium polysulfide solution.

[0039] In one embodiment, the sublimed sulfur is added in a molar ratio of Sublimed sulfur is added to the sodium sulfide solution obtained in step (1). Since the reaction between Sb2O3 and sodium sulfide is very rapid, if the sublimed sulfur does not participate in the reaction in time, NaSb(OH)6 precipitate will be generated, so the amount of sublimed sulfur is increased to reduce the generation of by-products.

[0040] In one embodiment, step (3) specifically comprises: adding Sb2O3 to the sodium polysulfide solution obtained in step (2), stirring at a temperature of 70-90°C for 30-60 min, and filtering using filter paper with a pore size of ≤4 μm, to obtain a Na3SbS4 solution. Using filter paper with a pore size of ≤4 μm can sufficiently remove NaSb(OH)6 precipitate, and improve the purity of the target product.

[0041] In one embodiment, step (4) specifically comprises: adding an oxide of A (an oxide that can react with NaOH solution, such as at least one of WO3, MoO3, SnO2, SiO2, TiO2, GeO2, ZnO2, MnO2, etc.), and a Na salt of B (such as at least one of NaF, NaCl, NaBr, NaI, etc.) to the sodium sulfide solution prepared according to step (1) in a set ratio, stirring at a temperature of 70-90°C for 30-60 min, to obtain a mixed solution.

[0042] In one embodiment, before the solution after stirring in step (5) is subjected to ice bath, the method further comprises adding isopropyl alcohol to the solution after stirring. The addition of isopropyl alcohol can promote the precipitation of Na 3-x-y Sb 1-x Ax S 4-y B y ·9H2O crystal precipitates, the purity of the target product is refined, thereby improving the ionic conductivity.

[0043] In one embodiment, step (5) specifically comprises:

[0044] The solutions obtained in steps (3) and (4) are mixed in a set ratio, and then stirred at a temperature of 70-90℃ for 30 min or more to obtain a Na 3-x-y Sb 1-x A x S 4-y B y solution (x is 0

[0045] A certain amount of isopropanol is added to the obtained Na 3-x-y Sb 1-x A x S 4-y B y solution, and the obtained solution is ice-bathed at 0-5℃ for 1-2 h, then filtered using filter paper with a pore size of ≤4 μm, washed with a 10-20 wt% NaOH solution, to obtain Na 3-x- y Sb 1-x A x S 4-y B y ·9H2O crystal;

[0046] The Na 3-x-y Sb 1-x A x S 4-y B y ·9H2O crystal is vacuum dried at 60-100℃ for 12-15 h;

[0047] The dried Na 3-x-y Sb 1-x A x S 4-y B y ·9H2O is vacuum heated at 150-200℃ for 8-10 h to obtain Na 3-x- y Sb 1-x A x S 4-y B y .

[0048] The embodiment of the present application provides a modified sodium ion sulfide solid-state electrolyte, wherein the modified sodium ion sulfide solid-state electrolyte is prepared by using the low-cost preparation method for synthesizing the modified sodium ion sulfide solid-state electrolyte in an aqueous phase.

[0049] The application will be further described in detail by means of several specific examples.

[0050] Example 1

[0051] This example provides a Na 2.88 Sb 0.88 W 0.12 A preparation method of S4 material, comprising the following steps:

[0052] S1, dissolving 11.8656g of Na2S·9H2O in 80℃ 6mL of deionized water to obtain a sodium sulfide solution; Take 11.8656g Na2S·9H2O and dissolve it in 80℃ 6mL of deionized water to obtain a sodium sulfide solution;

[0053] S2, Take 0.5171g of sublimed sulfur and add it to the sodium sulfide solution obtained in step S1, stir at a temperature of 80℃ until the sulfur is completely dissolved, and obtain a sodium polysulfide solution;

[0054] S3, add 2.332g of Sb2O3 to the sodium polysulfide solution obtained in step S2, stir at a temperature of 80℃ for 30min to obtain a mixed solution;

[0055] S4, filter the mixed solution obtained in step S3 using filter paper with a pore size ≤4μm to obtain a Na3SbS4 solution;

[0056] S5, dissolve 2.6967g of Na2S·9H2O in 80℃ 4mL of deionized water, then add 0.5059g of WO3, and stir at a temperature of 80℃ for 30min to obtain a Na2WS4 solution;

[0057] S6, mix the solutions obtained in steps S4 and S5, and stir at a temperature of 80℃ for 30min to obtain a Na 2.88 Sb 0.88 W 0.12 S4 solution;

[0058] S7, add 4mL of isopropyl alcohol to the solution obtained in step S6;

[0059] S8, after ice-bath for 1h in an environment of 0~5℃, filter the solution obtained in step S7 using filter paper with a pore size ≤4μm, and wash the Na 2.88 Sb 0.88 W 0.12 S4·9H2O with 10wt% NaOH solution;

[0060] S9, vacuum dry the Na 2.88 Sb 0.88 W 0.12 S4·9H2O obtained in step S8 at 80℃ for 12h;

[0061] S10, Na2WS4obtained in step S9 was dried at 180 °C for 8 h under vacuum. 2.88 Sb 0.88 W 0.12 S4·9H2O was heated at 180 °C for 8 h under vacuum to obtain Na2WS4. 2.88 Sb 0.88 W 0.12 S4.

[0062] Comparative Example 1

[0063] The difference from Example 1 is that in step S6, Na2WS4solution obtained in step S5 was not added, and the others were the same as Example 1. The target product obtained was Na3SbS4.

[0064] Comparative Example 2

[0065] The difference from Example 1 is that in step S7, isopropanol was not added, and the others were the same as Example 1. The target product obtained was NIS-Na3SbS4. 2.88 Sb 0.88 W 0.12 S4 (NIS: No isopropanol).

[0066] Comparative Example 3

[0067] The difference from Example 1 is that a new step S11 was added, and Na2WS4obtained in step S10 was exposed to air for 48 h to obtain Air-exposed Na2WS4. 2.88 Sb 0.88 W 0.12 S4 (Air-exposed: exposed to air for 48 h). 2.88 Sb 0.88 W 0.12 S4, and then heated at 180 °C for 10 h under vacuum, and the others were the same as Example 1. The target product obtained was Reheated Na2WS4. 2.88 Sb 0.88 W 0.12 S4.

[0068] Comparative Example 4

[0069] The difference from Example 1 is that in step S1, the molar ratio of Na2S·9H2O to S was 1:1.5, and the others were the same as Example 1. 11.5192 g of Na2S·9H2O was taken; in step S2, the molar ratio of Na2S·9H2O to S was 1:1.5, and the others were the same as Example 1. The target product obtained was NER-Na3SbS4. 0.5120 g of sulfur was taken, and the others were the same as Example 1. The target product obtained was NER-Na3SbS4. 2.88 Sb 0.88 W 0.12 S4 (NER: No excess of reactants).

[0070] Comparative Example 5

[0071] The difference from Example 1 is that in step S5, 1.2624 g of Na2S-9H2O and 0.2368 g of WO3 are taken, and the rest is the same as in Example 1, and the target product obtained is Na 2.94 Sb 0.94 W 0.06 S4.

[0072] Comparative Example 6

[0073] The difference from Example 1 is that in step S5, 4.3412 g of Na2S-9H2O and 0.8143 g of WO3 are taken, and the rest is the same as in Example 1, and the target product obtained is Na 2.82 Sb 0.82 W 0.18 S4.

[0074] 1. Evaluation process

[0075] The solid-state electrolyte products of all the above examples and comparative examples are analyzed by using a Smartlab 3KW model X-ray diffractometer (XRD) produced by Japan Rigaku. The specific operation process is as follows: the target test sample is loaded into a specially designed (air-tight) sample stage, 0.02° / step, and the test range is 10-80°.

[0076] The ion conductivity of the solid-state electrolyte products of all the above examples and comparative examples is analyzed by using a Modulab XM model electrochemical comprehensive tester produced by Britain Zhi Li Qiang. The specific operation process is as follows: in an argon-filled glove box, 100 mg of the target test sample is placed in a polytetrafluoroethylene sleeve and pressed by a tablet press, and then assembled into a mold and connected to the electrochemical comprehensive tester.

[0077] 2. Evaluation results

[0078] Figure 1 is the SEM image of Na 2.88 Sb 0.88 W 0.12 S4 prepared in Example 1, and from the figure it can be seen that the product obtained is uniform particles of 500 nm-1 μm, with obvious agglomeration phenomenon.

[0079] Figure 2 Na 2.88 Sb 0.88 W 0.12 S4 (Example 1), Na3SbS4 (Comparative Example 1), NIS-Na 2.88 Sb 0.88 W 0.12The XRD diffraction peaks of S4 (Comparative Example 2) are similar to those of Na3SbS4 standard card. By comparison, it can be seen that Comparative Example 1 is pure phase Na3SbS4. Since the ionic radius of W 6+ and Sb 5+ are similar, it leads to Na 2.88 Sb 0.88 W 0.12 S4 and Na3SbS4 have basically the same peak position. By comparison with Na 2.88 Sb 0.88 W 0.12 S4 (Example 1), it can be seen that NIS-Na 2.88 Sb 0.88 W 0.12 S4 (Comparative Example 2) has many impurity peaks, which proves that the product obtained without adding isopropanol is not high enough in purity, which further illustrates the importance of isopropanol in the present application to the purity of the refined solid electrolyte product.

[0080] Figure 3 The XRD diffraction peaks of S4 (Example 1), Air-exposed Na 2.88 Sb 0.88 W 0.12 S4 (Example 1), Reheated Na 2.88 Sb 0.88 W 0.12 S4 (Example 1 air-exposed water absorption product), and Reheated Na 2.88 Sb 0.88 W 0.12 S4 (Comparative Example 3) are compared with NaSbS4, NaSbS4·9H2O standard card. Na 2.88 Sb 0.88 W 0.12 S4 (Example 1) after air exposure and water absorption for 48 h has the same XRD spectrum as Na3SbS4·9H2O, indicating that a hydrate is formed. Air-exposed Na 2.88 Sb 0.88 W 0.12 S4 is heated at 180°C to remove the combined water to form Reheated Na 2.88 Sb 0.88 W 0.12 S4 (Comparative Example 3) has the same XRD spectrum as Na 2.88 Sb 0.88 W 0.12 S4 (Example 1), indicating that Na 2.88 Sb 0.88 W 0.12 S4 has high air stability.

[0081] Figure 4 The XRD diffraction peaks of S4 (Example 1), Air-exposed Na 2.88 Sb 0.88 W 0.12 S4 (Example 1), Reheated Na 2.88 Sb 0.88 W 0.12 S4 (Example 1 air-exposed water absorption product), and Reheated Na 2.88 Sb 0.88 W 0.12 S4 (Comparative Example 3) are compared with NaSbS4, NaSbS4·9H2O standard card. Na 2.88 Sb 0.88 W 0.12 S4 (Example 1) after air exposure and water absorption for 48 h has the same XRD spectrum as Na3SbS4·9H2O, indicating that a hydrate is formed. Air-exposed Na 2.88 Sb 0.88 W 0.12 S4 is heated at 180°C to remove the combined water to form Reheated Na 2.88 Sb 0.88 W 0.12 S4 (Comparative Example 3) has the same XRD spectrum as Na 2.88 Sb 0.88 W 0.12 S4 (Example 1), indicating that Na 2.88 Sb 0.88 W 0.12 S4 has high air stability.2.88 Sb 0.88 W 0.12 S4(Example 1), Na3SbS4(Comparative Example 1), NIS-Na 2.88 Sb 0.88 W 0.12 S4(Comparative Example 2), Reheated Na 2.88 Sb 0.88 W 0.12 S4(Comparative Example 3), NER-Na 2.88 Sb 0.88 W 0.12 S4(Comparative Example 4), Na 2.94 Sb 0.94 W 0.06 S4(Comparative Example 5), Na 2.82 Sb 0.82 W 0.18 S4(Comparative Example 6). Na 2.88 Sb 0.88 W 0.12 S4(Example 1) has the lowest impedance and is significantly better than other comparative examples. It should also be noted that in step S3, due to the solution constantly contacting air, side reactions occur (Sb2O3+ 6Na2S + 3H2O→ 2Na3SbS3+ 6NaOH, 2Na3SbS3+ 2NaOH + 3H2O→ 2NaSb(OH)6↓+ 3Na2S2O3, ) to generate NaSb(OH)6precipitate, and NaSb(OH)6can react with Na2S to regenerate Na3SbS4(NaSb(OH)6+ 4Na2S→ Na3SbS4+ 6NaOH), so in order to reduce the generation of NaSb(OH)6, the amount of reactants Na2S·9H2O and S needs to be increased to improve the purity of the product.

[0082] The results of Example 1 and Comparative Examples 1-6 are shown in Table 1.

[0083] Table 1

[0084]

[0085] The following results are obtained from the comparative examples: ① From Comparative Examples 1, 5 and 6, it can be seen that W doping can improve the ionic conductivity of Na3SbS4; ② From Comparative Example 2, it can be seen that isopropanol can refine the purity of the target product to improve the ionic conductivity; ③ From Comparative Example 3, it can be seen that Na 2.88 Sb 0.88 W 0.12S4 can restore performance by pyrolysis to remove bound water after being exposed to air for 48 hours; 4. According to the comparative example 4, the ion conductivity can be appropriately improved by 3% and 1% excess of Na2S·9H2O and S respectively; 5. According to the comparative examples 5 and 6, the performance is best when W is doped and substituted by 12% of Sb.

[0086] In summary, the application provides a low-cost preparation method for water-phase synthesis of modified sodium ion sulfide solid-state electrolyte. The application uses low-priced sodium sulfide nonahydrate to replace expensive anhydrous sodium sulfide as raw material, and uses water phase to avoid the production risk and the influence on product purity caused by organic solvent thermal evaporation, and solves the problem of low yield in traditional mechanical chemical ball milling synthesis, realizes the reduction of production cost of sodium ion sulfide solid-state electrolyte, and the method is simple and efficient, the process equipment is simple, easy to mass production, and has good commercialization prospect.

[0087] It should be understood that the application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the application.

Claims

1. A low-cost production method of aqueous-phase synthesis of modified sodium-ion sulfide solid-state electrolyte, characterized by, The modified sodium ion sulfide solid-state electrolyte is Na 3-x-y Sb 1-x A x S 4-y B y , wherein 0 3-x-y Sb 1-x A x S 4-y B y The preparation method of the modified sodium ion sulfide solid-state electrolyte comprises the following steps: (1) Dissolve Na2S·9H2O in water to prepare a sodium sulfide solution; (2) Add sublimed sulfur to the sodium sulfide solution prepared in step (1) until the sulfur is completely dissolved to prepare a sodium polysulfide solution; (3) Add Sb2O3 to the sodium polysulfide solution prepared in step (2) and stir, and filter to prepare a Na3SbS4 solution; (4) Add the oxide of A and the Na salt of B to the sodium sulfide solution prepared in step (1) and stir; (5) After mixing the solutions obtained in steps (3) and (4), the mixed solution is stirred, and the stirred solution is subjected to ice-bath, filtration, washing, and drying in this order to obtain Na 3-x-y Sb 1-x A x S 4-y B y ; Molar ratio ∶ = (2-2.05):1 sublimed sulfur is added to the sodium sulfide solution obtained in step (1); Before the solution after stirring in step (5) is subjected to ice bath, isopropyl alcohol is further added to the solution after stirring; Step (5) The washed Na 3-x-y Sb 1-x A x S 4-y B y • 9H2O crystals are dried in vacuum at 60-100°C for 12-15 h, followed by vacuum heating at 150-200°C for 8-10 h to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

2. The low-cost preparation method of water-phase synthetic modified sodium-ion sulfide solid-state electrolyte according to claim 1, characterized in that, Molar ratio ∶ = (6-6.2) : 1 Na2S-9H2O is added to the water of step (1), and the concentration of sodium sulfide in the solution is C Na = 6.5-8 mol / L.

3. The low cost preparation method of aqueous phase synthetic modified sodium-ion sulfide solid-state electrolyte according to claim 1, characterized in that, The filtering in step (3) is performed using filter paper with a pore size of ≤4 μm, and the filtering in step (5) is performed using filter paper with a pore size of ≤4 μm.

4. The low cost preparation method of aqueous phase synthetic modified sodium-ion sulfide solid-state electrolyte according to claim 1, characterized in that, The oxide of A in step (4) is at least one of WO3, MoO3, SnO2, SiO2, TiO2, GeO2, ZnO2 and MnO2, and the Na salt of B is at least one of NaF, NaCl, NaBr and NaI.

5. The low cost preparation method of aqueous phase synthetic modified sodium-ion sulfide solid-state electrolyte according to claim 1, characterized in that, The temperature of the ice bath in step (5) is 0-5 ℃, and the time of the ice bath is 1-2 h.

6. The low cost preparation method of aqueous phase synthetic modified sodium-ion sulfide solid-state electrolyte according to claim 1, characterized in that, Step (5) The obtained Na 3-x-y Sb 1-x A x S 4-y B y • 9H2O crystals are washed using 10-20 wt% NaOH solution.

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