Low-cost preparation method of water-phase synthesis modified sodium ion sulfide solid electrolyte

Abstract

The invention discloses a low-cost preparation method of a water-phase synthesized modified sodium ion sulfide solid electrolyte, and belongs to the technical field of sodium ion batteries. According to the method, low-price sodium sulfide nonahydrate is adopted to replace expensive anhydrous sodium sulfide as a raw material, and the production risk caused by thermal evaporation of an organic solvent and the influence on the purity of a sample are avoided by using a water phase; the production cost is reduced, large-scale preparation is realized, and the method has a good commercialization prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium-ion batteries, and in particular to a low-cost preparation method for synthesizing and modifying a sodium-ion sulfide solid electrolyte in an aqueous phase. Background Art

[0002] Lithium-ion batteries are an important part of modern life and have been widely used in power electric, new energy vehicles, and clean energy storage. With the rising price of lithium, sodium with abundant reserves has become one of the options to replace lithium-ion batteries. The ester-based organic compound liquid electrolytes used in traditional sodium-ion batteries are extremely flammable under high-temperature or collision conditions. Therefore, replacing the liquid electrolyte with a solid electrolyte having excellent thermal stability and strong mechanical quality is an important way to improve safety performance. Currently, the research on sodium-ion solid electrolytes mainly focuses on Na3PS, Na7PS6, Na3SbS4, Na 11 Sn2PS 12 、Na 10 GeP2S 12 and their doped derivatives. However, the current sodium-ion sulfide solid electrolytes all require the use of expensive and low-purity anhydrous Na2S as raw materials and use mechanochemical ball milling for synthesis, which greatly limits their commercial application.

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

[0004] In view of the above deficiencies of the prior art, the purpose of the present invention is to provide a low-cost preparation method for synthesizing and modifying a sodium-ion sulfide solid electrolyte in an aqueous phase, aiming to solve the problem that the existing sodium-ion sulfide solid electrolytes need to use expensive and low-purity anhydrous Na2S as raw materials and use mechanochemical ball milling for synthesis, which greatly limits their commercial application.

[0005] The technical solution of the present invention is as follows:

[0006] A low-cost preparation method for synthesizing and modifying a sodium-ion sulfide solid electrolyte in an aqueous phase, wherein the modified sodium-ion sulfide solid electrolyte is Na 3-x-y Sb 1-x A x S 4-y B y , where 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, I; the Na 3-x-y Sb 1-x A x S 4-y By The preparation method comprises the following steps:

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

[0008] (2) adding the sublimated 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), stirring, and filtering to obtain a Na3SbS4 solution;

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

[0011] (5) The solutions obtained in step (3) and step (4) are mixed and stirred, and the stirred solution is successively subjected to ice bath, filtration, washing, and drying to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

[0012] Optionally, in molar ratios Na2S·9H2O is added to the water in step (1), wherein the sodium sulfide solution contains C Na =6.5~8mol / L.

[0013] Optionally, in molar ratios The sublimated sulfur is added to the sodium sulfide solution obtained in step (1).

[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 NaI.

[0016] Optionally, before placing the stirred solution in an ice bath in step (5), the step further includes adding isopropanol to the stirred solution.

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

[0018] Optionally, the Na obtained by filtering in step (5) 3-x-y Sb 1-x A x S4-y B y · 9H2O crystals were washed with 10-20 wt% NaOH solution.

[0019] Optionally, step (5) the Na 3-x-y Sb 1-x A x S 4-y B y ·9H2O crystals are dried in vacuum at 60-100℃ for 12-15h, and then heated in vacuum at 150-200℃ for 8-10h to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

[0020] Beneficial effects: The present invention adopts low-cost sodium sulfide nonahydrate to replace expensive anhydrous sodium sulfide as raw material, and uses aqueous phase to avoid production risks and influence on product purity caused by thermal evaporation of organic solvents, and solves the problem of low yield of traditional mechanochemical ball milling synthesis, thereby reducing the production cost of sodium ion sulfide solid electrolyte. The method is simple and efficient, the process equipment is simple, and it is easy to mass produce, which has good commercial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Figure 2 for 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 X-ray diffraction pattern of S4 (Comparative Example 2).

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

[0024] Figure 4 is 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) of the electrochemical impedance spectra. Detailed implementation manners

[0025] The present invention provides a low-cost preparation method for aqueous-phase synthesis of modified sodium-ion sulfide solid electrolytes. To make the objectives, technical solutions and effects of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] An embodiment of the present invention provides a low-cost preparation method for aqueous-phase synthesis of modified sodium-ion sulfide solid electrolytes, wherein the modified sodium-ion sulfide solid electrolyte is Na 3-x-y Sb 1-x A x S 4-y B y , where 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, I; the preparation method of the Na 3-x-y Sb 1- x A x S 4-y B y includes the following steps:

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

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

[0029] (3) adding Sb2O3 to the sodium polysulfide 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 to the sodium sulfide solution prepared according to step (1) and stirring;

[0031] (5) The solutions obtained in step (3) and step (4) are mixed and stirred, and the stirred solution is successively subjected to ice bath, filtration, washing, and drying to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

[0032] Take Na 2.88 Sb 0.88 W 0.12 S4 is used as an example to illustrate the above preparation process. First, steps (1), (2), and (3) are to synthesize Na3SbS4 according to 6Na2S+2S+Sb2O3+3H2O→2Na3SbS4+6NaOH. Sb2O3 easily reacts with Na2S to generate Na3SbS3 (Sb2O3+6Na2S+3H2O→2Na3SbS3+6NaOH), and sublimed sulfur is not easy to participate in the reaction to generate Na3SbS4. Therefore, sublimed sulfur is first dissolved in sulfur. Sodium polysulfide is formed in the sodium sulfate solution to reduce the generation of by-products and improve the utilization rate of sublimated sulfur; and step (4) is to synthesize Na2WS4 according to WO3+2NaOH→Na2WO4+H2O and Na2WO4+4Na2S+4H2O→Na2WS4+8NaOH, wherein NaOH is produced by the hydrolysis of Na2S; and finally step (5) is to mix the two substances obtained above and then carry out the reaction according to 0.12Na2WS4+0.88Na3SbS4→Na 2.88 Sb 0.88 W 0.12 S4 obtains the target product.

[0033] The embodiment of the present invention uses sodium sulfide nonahydrate, a common low-cost sodium source, instead of anhydrous sodium sulfide as a raw material, which reduces the preparation cost of sodium ion sulfide solid electrolytes, and avoids the production risk caused by thermal evaporation of organic solvents and the impact on product purity by using an aqueous phase, and solves the problem of low yield of traditional mechanochemical ball milling synthesis. The method is simple and efficient, the process equipment is simple, and it is easy to mass produce, and has a good commercial prospect. In addition, by partially replacing and doping Sb and S in Na3SbS4 and inserting defects in the Na3SbS4 structure, a solid electrolyte with higher ion conductivity than Na3SbS4 can be obtained.

[0034] The modified sodium ion 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, I. By way of example, the Na 3-x-y Sb 1-x A x S 4-y B y can 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 includes: dissolving Na2S·9H2O in deionized water at 70 - 90 °C to prepare a sodium sulfide solution.

[0036] In one embodiment, according to 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 the air after being added to the sodium polysulfide solution to generate NaSb(OH)6 precipitation (Sb2O3+6Na2S+3H2O→2Na3SbS3+6NaOH, 2Na3SbS3+2NaOH+3H2O→2NaSb(OH)6↓+3Na2S2O3), NaSb(OH)6 can be converted back into Na3SbS4 (NaSb(OH)6+4Na2S→Na3SbS4+6NaOH) by adding an appropriate excess of Na2S·9H2O.

[0037] In one embodiment, the sodium sulfide solution contains C Na =6.5~8mol / L.

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

[0039] In one embodiment, the molar ratio 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 fails to participate in the reaction in time, NaSb(OH)6 precipitation will be generated. Therefore, the amount of sublimed sulfur in the reactant 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 to 90°C for 30 to 60 minutes, 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 fully remove NaSb(OH)6 precipitation 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 a 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 re-prepared according to step (1) according to a set ratio, stirring at a temperature of 70 to 90° C. for 30 to 60 minutes to obtain a mixed solution.

[0042] In one embodiment, before placing the stirred solution in an ice bath in step (5), isopropanol is added to the stirred solution. Adding isopropanol can promote the Na 3-x-y Sb 1-x Ax S 4-y B y ·9H₂O crystals precipitate, refining the purity of the target product, thereby enhancing the ionic conductivity.

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

[0044] Mix the solutions obtained in steps (3) and (4) in a set ratio, and stir for more than 30 min at a temperature of 70 - 90 °C to obtain Na 3-x-y Sb 1-x A x S 4-y B y solution (where 0 < x < 1 and 0 ≤ y < 3);

[0045] Add a certain amount of isopropanol to the obtained Na 3-x-y Sb 1-x A x S 4-y B y solution, ice-bath the obtained solution in an environment of 0 - 5 °C for 1 - 2 h, then filter with a filter paper having a pore size ≤ 4 μm, and wash with a 10 - 20 wt% NaOH solution to obtain Na 3-x- y Sb 1-x A x S 4-y B y ·9H₂O crystals;

[0046] Vacuum-dry the Na 3-x-y Sb 1-x A x S 4-y B y ·9H₂O crystals at 60 - 100 °C for 12 - 15 h;

[0047] Vacuum-heat the dried Na 3-x-y Sb 1-x A x S 4-y B y ·9H₂O at 150 - 200 °C 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 invention provides a modified sodium-ion sulfide solid electrolyte, which is prepared by using the low-cost preparation method of the water-phase synthesis modified sodium-ion sulfide solid electrolyte described in the embodiment of the present invention.

[0049] The present invention is further described in detail below through several specific embodiments.

[0050] Example 1

[0051] This embodiment provides a Na 2.88 Sb 0.88 W 0.12 The preparation method of S4 material comprises the following steps:

[0052] S1, molar ratio Prepare a sodium sulfide solution by dissolving 11.8656 g of Na2S·9H2O in 6 mL of deionized water at 80°C.

[0053] S2, 0.5171 g of sublimated sulfur was added to the sodium sulfide solution obtained in step S1, and stirred at 80° C. until the sulfur was completely dissolved to obtain a sodium polysulfide solution;

[0054] S3, adding 2.332 g of Sb2O3 to the sodium polysulfide solution obtained in step S2, stirring at 80°C for 30 min to obtain a mixed solution;

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

[0056] S5, dissolving 2.6967 g Na2S·9H2O in 4 mL deionized water at 80°C, then adding 0.5059 g WO3, stirring at 80°C for 30 min, to prepare a Na2WS4 solution;

[0057] S6, mixing the solutions obtained in step S4 and S5 and stirring at 80°C for 30 min to obtain Na 2.88 Sb 0.88 W 0.12 S4 solution;

[0058] S7, adding 4 mL of isopropanol to the solution obtained in step S6;

[0059] S8, the solution obtained in step S7 was placed in an ice bath at 0-5°C for 1 hour, filtered using filter paper with a pore size of ≤4 μm, and washed with 10 wt% NaOH solution. 2.88 Sb 0.88 W 0.12 S4·9H2O;

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

[0061] S10, the Na 2.88 Sb 0.88 W 0.12 S4·9H2O was heated at 180℃ in vacuum for 8h to obtain Na 2.88 Sb 0.88 W 0.12 S4.

[0062] Comparative Example 1

[0063] The difference from Example 1 is that in step S6, the Na2WS4 solution obtained in S5 is not added, and the rest is the same as Example 1. The target product obtained is Na3SbS4.

[0064] Comparative Example 2

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

[0066] Comparative Example 3

[0067] The difference from Example 1 is that: a new step S11 is added to convert Na 2.88 Sb 0.88 W 0.12 Air-exposed Na was obtained after S4 was exposed to air and absorbed water for 48 hours. 2.88 Sb 0.88 W 0.12 S4, then heated at 180°C in vacuum for 10 h, and the rest was the same as in Example 1. The target product obtained was Reheated Na 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 Take 11.5192g Na2S·9H2O; in step S2, in molar ratio Take 0.5120g of sublimed sulfur, and the rest is the same as in Example 1. The target product is NER-Na 2.88 Sb 0.88 W 0.12 S4 (NER: No excess of reactants, meaning no excess of reactants).

[0070] Comparative Example 5

[0071] The difference from Example 1 is that in step S5, 1.2624 g Na2S·9H2O and 0.2368 g WO3 are taken, and the rest is the same as in Example 1. 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 Na2S·9H2O and 0.8143 g WO3 are taken, and the rest is the same as in Example 1. The target product obtained is Na 2.82 Sb 0.82 W 0.18 S4.

[0074] 1. Evaluation process

[0075] The solid electrolyte products of all the above embodiments and comparative examples were analyzed using a Smartlab3KW X-ray diffraction (XRD) analyzer produced by Rigaku Corporation. The specific operation process is as follows: the target test sample is placed in a special (air-proof) sample stage, 0.02° / step, and the test range is 10-80°.

[0076] The solid electrolyte products of all the above embodiments and comparative examples were subjected to ion conductivity analysis using a ModulabXM electrochemical comprehensive tester produced by Transtron in the UK. The specific operation process is as follows: in a glove box filled with argon, 100 mg of the target test sample was placed in a polytetrafluoroethylene sleeve and pressed with a tablet press, and the mold was assembled and connected to the electrochemical comprehensive tester.

[0077] 2. Evaluation results

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

[0079] Figure 2 for 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) and the standard card peaks of Na3SbS4. By comparison, it can be seen that Comparative Example 1 is pure phase Na3SbS4. 6+ and Sb 5+ The ionic radius of Na 2.88 Sb 0.88 W 0.12 The peak positions of S4 and Na3SbS4 are basically the same. 2.88 Sb 0.88 W 0.12 S4 (Example 1) comparison, it can be seen that NIS-Na 2.88 Sb 0.88 W 0.12 S4 (Comparative Example 2) showed many impurity peaks, proving that the purity of the obtained product was not high enough without the addition of isopropanol, which further illustrates the importance of isopropanol in the present invention to the purity of the refined solid electrolyte product.

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

[0081] Figure 4 for Na2.88 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 Electrochemical impedance spectrum of S4 (Comparative Example 6). 2.88 Sb 0.88 W 0.12 S4 (Example 1) has the lowest impedance and is significantly better than other comparative examples. In addition, it should be noted that in step S3, due to the continuous contact of the solution with air, side reactions (Sb2O3+6Na2S+3H2O→2Na3SbS3+6NaOH, 2Na3SbS3+2NaOH+3H2O→2NaSb(OH)6↓+3Na2S2O3) will occur to generate NaSb(OH)6 precipitate, and NaSb(OH)6 can react with Na2S to regenerate Na3SbS4 (NaSb(OH)6+4Na2S→Na3SbS4+6NaOH), so in order to reduce the generation of NaSb(OH)6, it is necessary to increase the amount of reactants Na2S·9H2O and S to improve the purity of the product.

[0082] The results of Example 1 and Comparative Examples 1 to 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 and thus improve the ionic conductivity; ③ From comparative example 3, it can be seen that Na 2.88 Sb 0.88 W 0.12After S4 was exposed to air for 48 hours, the performance was restored by pyrolysis to remove bound water; ④ From Comparative Example 4, it can be seen that 3% and 1% excess of Na2S·9H2O and S respectively can appropriately improve the ionic conductivity; ⑤ From Comparative Examples 5 and 6, it can be seen that the performance is best when W doping replaces 12% of Sb.

[0086] In summary, the present invention provides a low-cost preparation method for aqueous phase synthesis of modified sodium ion sulfide solid electrolytes. The present invention uses low-cost sodium sulfide nonahydrate to replace expensive anhydrous sodium sulfide as a raw material, and uses an aqueous phase to avoid the production risks and the impact on product purity caused by thermal evaporation of organic solvents, and solves the problem of low yield of traditional mechanochemical ball milling synthesis, thereby reducing the production cost of sodium ion sulfide solid electrolytes. The method is simple and efficient, the process equipment is simple, and it is easy to mass produce, and has good commercial prospects.

[0087] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A low-cost preparation method for aqueous phase synthesis of modified sodium ion sulfide solid electrolyte, characterized in that: The modified sodium-ion sulfide solid electrolyte is Na 3-x-y Sb 1-x A x S 4-y B y , where 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, I; the preparation method of the Na 3-x-y Sb 1-x A x S 4-y B y includes the following steps: (1) Dissolve Na2S·9H2O in water to prepare a sodium sulfide solution; (2) adding the sublimated sulfur to the sodium sulfide solution obtained in step (1) until the sulfur is completely dissolved to obtain a sodium polysulfide solution; (3) adding Sb2O3 to the sodium polysulfide solution obtained in step (2), stirring, and filtering to obtain a Na3SbS4 solution; (4) adding the oxide of A and the Na salt of B to the sodium sulfide solution prepared according to step (1) and stirring; (5) The solutions obtained in step (3) and step (4) are mixed and stirred, and the stirred solution is successively subjected to ice bath, filtration, washing, and drying to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

2. The low-cost preparation method of aqueous phase synthesized modified sodium ion sulfide solid electrolyte according to claim 1, characterized in that: More Na2S·9H2O is added to the water in step (1), wherein the sodium sulfide solution contains C Na =6.5~8mol / L.

3. The low-cost preparation method of aqueous phase synthesized modified sodium ion sulfide solid electrolyte according to claim 1, characterized in that: More The sublimated sulfur is added to the sodium sulfide solution obtained in step (1).

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

5. The low-cost preparation method of aqueous phase synthesized modified sodium ion sulfide solid 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.

6. The low-cost preparation method of aqueous phase synthesized modified sodium ion sulfide solid electrolyte according to claim 1, characterized in that: Before placing the stirred solution in an ice bath in step (5), the step further includes adding isopropanol to the stirred solution.

7. The low-cost preparation method of aqueous phase synthesized modified sodium ion sulfide solid electrolyte according to claim 1, characterized in that: The temperature of the ice bath in step (5) is 0 to 5° C., and the time of the ice bath is 1 to 2 hours.

8. The low-cost preparation method of aqueous phase synthesized modified sodium ion sulfide solid electrolyte according to claim 1, characterized in that: Step (5) Filter the obtained Na 3-x-y Sb 1-x A x S 4-y B y · 9H2O crystals were washed with 10-20 wt% NaOH solution.

9. The low-cost preparation method of aqueous phase synthesized modified sodium ion sulfide solid electrolyte according to claim 1, characterized in that: Step (5) washing the Na 3-x-y Sb 1-x A x S 4-y B y ·9H2O crystals are dried in vacuum at 60-100℃ for 12-15h, and then heated in vacuum at 150-200℃ for 8-10h to obtain Na 3-x-y Sb 1-x A x S 4-y B y .

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