Preparation method of sulfide solid electrolyte

Abstract

The invention belongs to the field of batteries, and discloses a preparation method of a sulfide solid electrolyte, the chemical composition is LiaAxPSbBy (B is one of F, Cl and Br). The preparation method comprises the following steps: ball-milling and mixing a lithium source, an A-containing compound, a phosphorus source I and a sulfur source to obtain a first mixture for later use; grinding and mixing a sulfur source, a phosphorus source II and an M-containing compound, and adding a carbon material to obtain a second mixture; and finally, wrapping the first mixture into the second mixture, sintering, and grinding the sintered product to obtain the sulfide solid electrolyte. The low-cost raw materials are adopted, preparation can be completed in a common air environment, the production process is simplified, the preparation cost and equipment requirements are reduced, and the prepared electrolyte has relatively high ionic conductivity and relatively good total battery cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of batteries, specifically relating to a method for preparing a sulfide solid electrolyte. Background Technology

[0002] All-solid-state batteries are considered a candidate technology for next-generation high-performance energy storage devices. They are suitable for various fields, including electric vehicles, wearable devices, mobile electronic devices, and smart grids. The high energy density and safety performance of all-solid-state batteries give them revolutionary potential to drive the development of electrification and renewable energy.

[0003] Among the three types of solid-state electrolytes—oxides, sulfides, and halides—sulfides are the only solid-state electrolytes that simultaneously possess good anode compatibility (allowing them to be compatible with high-energy-density anodes such as lithium metal and silicon) and extremely low density (facilitating reduced battery weight and increased battery energy density). Currently, the manufacturing process of sulfide solid-state electrolytes mainly relies on raw materials such as Li₂S and P₂S₅. These raw materials readily react in air, leading to a complex and costly preparation process, which limits their application in large-scale industrial production. Therefore, developing an economical and environmentally friendly method for the large-scale production of sulfide solid-state electrolytes is a significant challenge currently facing process development. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing sulfide solid electrolytes to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing a sulfide solid electrolyte includes the following steps:

[0007] S1. The lithium source, the A-containing compound, the phosphorus source and the sulfur source are ball-milled and mixed to obtain the first mixture for later use.

[0008] S2. Grind and mix the sulfur source, phosphorus source II, B source and M-containing compound, then add carbon material to obtain a second mixture;

[0009] S3. After taking out the first mixture and the second mixture according to the mass ratio, wrap the first mixture into the second mixture in a cylindrical crucible and put it into a sintering furnace. Then remove the wrapping layer and grind the sintered product to obtain a sulfide solid electrolyte.

[0010] As a further aspect of the present invention: in step S1, the ball milling time is 1-20 hours, and the rotation speed is 200-800 r / min, so that the raw materials are fully mixed. The lithium source is a variety of lithium carbonate, lithium oxide, lithium chloride, lithium phosphate, lithium oxalate, lithium formate, lithium nitrate, lithium bromide, and lithium fluoride. The A-containing compound is one of A-containing chloride and A-containing carbonate, wherein A is one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, and gadolinium. The phosphorus source is one of phosphorus powder, phosphorus oxide, phosphorus nitride, triphenylphosphine, polyphosphoric acid, urea phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, pyrophosphate, hexametaphosphate, and tripolyphosphoric acid. The sulfur source is one of sulfur powder, ammonium thiocyanate, and thiourea.

[0011] As a further embodiment of the present invention: in step S1, the molar ratio of lithium source to element A in the compound containing A is 3:1-45:1, the molar ratio of sulfur source to element A in the compound containing A is 6:1-50:1, and the molar ratio of phosphorus source one to element A in the compound containing A is 3:1-16:1.

[0012] As a further aspect of the present invention: in step S2, the ball milling time is 1-12 hours, and the rotation speed is 100-800 r / min, ensuring thorough mixing of the raw materials. The compound containing M is one of lithium carbonate, lithium sulfate, lithium phosphate, sodium carbonate, sodium sulfate, sodium chloride, sodium phosphate, potassium carbonate, calcium carbonate, barium carbonate, potassium nitrate, calcium nitrate, iron oxide, and copper oxide. The phosphorus source is one of urea phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, pyrophosphate, hexametaphosphate, and tripolyphosphate. The carbon material is one of activated carbon, graphite, hard carbon, and carbon fiber powder.

[0013] As a further embodiment of the present invention: in step S2, the source B is one of 4-fluorotrifluorotoluene, 3-fluorotrifluorotoluene, fluorinated benzene, trifluorotoluene, bromoacetyl bromide, p-bromobenzyl bromide, 3-bromobenzyl bromide, bromoisobutyryl bromide, chloroacetyl chloride, p-chlorobenzyl chloride, trichloroacetyl chloride, and dichloroacetyl chloride.

[0014] As a further embodiment of the present invention: in step S3, the sintering furnace is one of a muffle furnace, a box furnace, or a tube furnace, the sintering atmosphere is an air atmosphere, the sintering temperature is 500-1000℃, and the sintering time is 1-12h. Attached Figure Description

[0015] Figure 1 Impedance spectra of the sulfide solid electrolytes prepared in Examples 1-6;

[0016] Figure 2 The results of the full battery prepared in Example 1 were obtained after 40 charge-discharge cycles at 0.1C.

[0017] Figure 3The xrd plot of the sulfide solid electrolyte prepared in Example 1; Detailed Implementation

[0018] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0019] Example 1:

[0020] The present invention prepares Li3Sm using the present invention. 0.3 PS4Cl 0.9 Sulfide solid electrolyte. 0.954 mol of lithium carbonate, 0.3 mol of lithium oxalate, 0.3 mol of samarium chloride, 0.6 mol of phosphorus oxide, and 6 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added and the mixture was ball-milled for 16 hours at 450 r / min to obtain the first mixture. Then, sulfur, chloroacetyl chloride, diammonium hydrogen phosphate, calcium carbonate, and activated carbon granules were extracted in a molar ratio of 2:2:2:0.001:1. The sulfur, chloroacetyl chloride, diammonium hydrogen phosphate, and calcium carbonate were then placed in a jar mill and ball-milled for 4 hours at 600 r / min. Activated carbon granules were added again to obtain the second mixture. Finally, the first and second mixtures were extracted in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 600°C for 3 hours in air. After cooling to room temperature, the mixture was removed, the wrapping layer was removed, and the sintered product was ground and pressed into tablets to obtain Li3Sm. 0.3 PS4Cl 0.9 The sulfide solid electrolyte had a room-temperature ionic conductivity of 7.2 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 94%.

[0021] Example 2:

[0022] Preparation of Li using the present invention 3.5 La 0.5 PS 4.3 Br 1.4Sulfide solid electrolyte. 1.4 mol of lithium bromide, 1.2 mol of lithium oxalate, 0.05 mol of lithium carbonate, 0.5 mol of lanthanum carbonate, 1.4 mol of phosphorus powder, and 6.9 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added and the mixture was ball-milled for 10 hours at 800 r / min to obtain the first mixture for later use. Then, sulfur, bromoacetyl bromide, ammonium dihydrogen phosphate, barium carbonate, and activated carbon granules were removed according to a molar ratio of 2:2:2:0.001:1. The sulfur, bromoacetyl bromide, and phosphoric acid were then... Ammonium dihydrogen phosphate and barium carbonate were placed in a ball mill and milled at 700 rpm for 3 hours. Activated carbon granules were then added to obtain a second mixture. Finally, the first and second mixtures were taken out at a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 1000°C for 5 hours in air. After cooling to room temperature, the mixture was removed, the wrapping layer was removed, and the sintered product was ground and pressed into tablets to obtain Li. 3.5 La 0.5 PS 4.3 Br 1.4 The sulfide solid electrolyte had a room-temperature ionic conductivity of 7.34 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 95.1%.

[0023] Example 3:

[0024] Preparation of Li4Ce using the present invention 0.1 PS3F 3.3 Sulfide solid electrolyte. 3.3 mol of lithium fluoride, 0.8 mol of lithium nitrate, 0.1 mol of cerium carbonate, 0.6 mol of phosphorus nitride, and 4.5 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added, and the mixture was ball-milled for 20 hours at 600 rpm to obtain a first mixture. Then, sulfur, fluorinated benzene, pyrophosphate, potassium nitrate, and activated carbon granules were removed in a molar ratio of 2:2:2:0.001:1. The sulfur, fluorinated benzene, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 6 hours at 550 rpm. Activated carbon granules were added again to obtain a second mixture. Finally, the first and second mixtures were removed in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 700°C for 12 hours in air. After cooling to room temperature, the coating layer was removed, and the sintered product was ground and pressed into tablets to obtain Li₄Ce. 0.1 PS3F 3.3 The sulfide solid electrolyte had a room-temperature ionic conductivity of 7.1 × 10⁻⁶.-3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 96.7%.

[0025] Example 4:

[0026] Preparation of Li using the present invention 5.3 Gd 0.3 PS 4.4 Cl 2.4 Sulfide solid electrolyte. 2.4 mol lithium chloride, 1.6 mol lithium oxalate, 0.3 mol gadolinium carbonate, 0.6 mol phosphorus oxide, and 7 mol sulfur were weighed and poured into a ball mill jar. Zirconia balls were added, and the mixture was ball-milled for 12 hours at 300 rpm to obtain a first mixture. Then, sulfur, trichloroacetyl chloride, pyrophosphate, potassium nitrate, and activated carbon granules were extracted in a molar ratio of 2:2:2:0.001:1. The sulfur, trichloroacetyl chloride, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 6 hours at 350 rpm. Activated carbon granules were added again to obtain a second mixture. Finally, the first and second mixtures were extracted in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 900°C for 12 hours in air. After cooling to room temperature, the encapsulation layer was removed, and the sintered product was ground and pressed into tablets to obtain Li. 5.3 Gd 0.3 PS 4.4 Cl 2.4 The sulfide solid electrolyte had a room-temperature ionic conductivity of 6.5 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 94.7%.

[0027] Example 5:

[0028] Preparation of Li using the present invention 4.3 Pr 0.1 PS 3.4 Br 2.8Sulfide solid electrolyte. 2.8 mol of lithium bromide, 0.9 mol of lithium oxide, 0.1 mol of praseodymium carbonate, 0.5 mol of phosphorus nitride, and 6 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added, and the mixture was ball-milled for 15 hours at 700 r / min to obtain a first mixture. Then, sulfur, p-benzyl bromide, pyrophosphate, potassium nitrate, and activated carbon particles were removed in a molar ratio of 2:2:2:0.001:1. The sulfur, p-benzyl bromide, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 5 hours at 600 r / min. Activated carbon particles were added again to obtain a second mixture. Finally, the first and second mixtures were removed in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 800°C for 5 hours in air. After cooling to room temperature, the coating layer was removed, and the sintered product was ground and pressed into tablets to obtain Li. 4.3 Pr 0.1 PS 3.4 Br 2.8 The sulfide solid electrolyte had a room-temperature ionic conductivity of 5.2 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 94.2%.

[0029] Example 6:

[0030] Preparation of Li6Eu using the present invention 0.2 PS 4.9 Cl 1.8 Sulfide solid electrolyte. 1.8 mol of lithium chloride, 2.3 mol of lithium oxalate, 0.1 mol of europium carbonate, 0.5 mol of phosphorus nitride, and 7.3 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added, and the mixture was ball-milled for 18 hours at 400 r / min to obtain a first mixture for later use. Then, sulfur, dichloroacetyl chloride, pyrophosphate, potassium nitrate, and activated carbon granules were taken out in a molar ratio of 2:2:2:0.001:1. The sulfur, dichloroacetyl chloride, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 2 hours at 800 r / min. Activated carbon granules were then added to obtain a second mixture for later use. Finally, the first mixture and the second mixture were taken out in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 900°C for 6 hours in air atmosphere. After cooling to room temperature, the mixture was removed, the wrapping layer was removed, and the sintered product was ground and pressed into tablets to obtain Li6Eu. 0.2 PS 4.9 Cl 1.8The sulfide solid electrolyte had a room-temperature ionic conductivity of 4.95 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C, the capacity retention rate was 95.6% after 40 cycles.

[0031] Example 7:

[0032] The present invention prepares Li3Pm using the present invention. 0.3 PS4Cl 0.9 Sulfide solid electrolyte. 0.954 mol of lithium carbonate, 0.3 mol of lithium oxalate, 0.3 mol of promethium chloride, 0.6 mol of phosphorus oxide, and 6 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added and the mixture was ball-milled for 16 hours at 450 r / min to obtain the first mixture. Then, sulfur, chloroacetyl chloride, diammonium hydrogen phosphate, calcium carbonate, and activated carbon granules were taken out in a molar ratio of 2:2:2:0.001:1. The sulfur, chloroacetyl chloride, diammonium hydrogen phosphate, and calcium carbonate were then placed in a jar mill and ball-milled for 4 hours at 600 r / min. Activated carbon granules were then added to obtain the second mixture. Finally, the first and second mixtures were taken out in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 600°C for 3 hours in air. After cooling to room temperature, the mixture was removed, the wrapping layer was removed, and the sintered product was ground and pressed into tablets to obtain Li3Pm. 0.3 PS4Cl 0.9 The sulfide solid electrolyte had a room-temperature ionic conductivity of 4.35 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 92.8%.

[0033] Example 8:

[0034] Preparation of Li using the present invention 3.5 Nd 0.5 PS 4.3 Br 1.4Sulfide solid electrolyte. 1.4 mol of lithium bromide, 1.2 mol of lithium oxalate, 0.05 mol of lithium carbonate, 0.5 mol of neodymium carbonate, 1.4 mol of phosphorus powder, and 6.9 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added and the mixture was ball-milled for 10 hours at 800 r / min to obtain the first mixture for later use. Then, sulfur, bromoacetyl bromide, ammonium dihydrogen phosphate, barium carbonate, and activated carbon granules were removed according to a molar ratio of 2:2:2:0.001:1. The sulfur, bromoacetyl bromide, and phosphoric acid were then... Ammonium dihydrogen phosphate and barium carbonate were placed in a ball mill and milled at 700 rpm for 3 hours. Activated carbon granules were then added to obtain a second mixture. Finally, the first and second mixtures were taken out at a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 1000°C for 5 hours in air. After cooling to room temperature, the mixture was removed, the wrapping layer was removed, and the sintered product was ground and pressed into tablets to obtain Li. 3.5 Nd 0.5 PS 4.3 Br 1.4 The sulfide solid electrolyte had a room-temperature ionic conductivity of 5.3 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 91.8%.

[0035] Example 9:

[0036] Preparation of Li4Gd using the present invention 0.1 PS3F 3.3 Sulfide solid electrolyte. 3.3 mol of lithium fluoride, 0.8 mol of lithium nitrate, 0.1 mol of gadolinium carbonate, 0.6 mol of phosphorus nitride, and 4.5 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added, and the mixture was ball-milled for 20 hours at 600 r / min to obtain a first mixture for later use. Then, sulfur, fluorinated benzene, pyrophosphate, potassium nitrate, and activated carbon particles were taken out in a molar ratio of 2:2:2:0.001:1. The sulfur, fluorinated benzene, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 6 hours at 550 r / min. Activated carbon particles were then added to obtain a second mixture for later use. Finally, the first mixture and the second mixture were taken out in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 700°C for 12 hours in an air atmosphere. After cooling to room temperature, the mixture was removed, the wrapping layer was removed, and the sintered product was ground and pressed into tablets to obtain Li4Gd. 0.1 PS3F 3.3 The sulfide solid electrolyte had a room-temperature ionic conductivity of 3.76 × 10⁻⁶.-3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C, the capacity retention rate was 91.7% after 40 cycles.

[0037] Example 10:

[0038] Preparation of Li using the present invention 5.3 La 0.3 PS 4.4 Cl 2.4 Sulfide solid electrolyte. 2.4 mol lithium chloride, 1.6 mol lithium oxalate, 0.3 mol lanthanum carbonate, 0.6 mol phosphorus oxide, and 7 mol sulfur were weighed and poured into a ball mill jar. Zirconia balls were added, and the mixture was ball-milled for 12 hours at 300 r / min to obtain a first mixture. Then, sulfur, trichloroacetyl chloride, pyrophosphate, potassium nitrate, and activated carbon granules were extracted in a molar ratio of 2:2:2:0.001:1. The sulfur, trichloroacetyl chloride, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 6 hours at 350 r / min. Activated carbon granules were added again to obtain a second mixture. Finally, the first and second mixtures were extracted in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 900°C for 12 hours in air. After cooling to room temperature, the encapsulation layer was removed, and the sintered product was ground and pressed into tablets to obtain Li. 5.3 La 0.3 PS 4.4 Cl 2.4 The sulfide solid electrolyte had a room-temperature ionic conductivity of 5.4 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C, the capacity retention rate was 94.5% after 40 cycles.

[0039] Example 11:

[0040] Preparation of Li using the present invention 4.3 Eu 0.1 PS 3.4 Br 2.8Sulfide solid electrolyte. 2.8 mol of lithium bromide, 0.9 mol of lithium oxide, 0.1 mol of europium carbonate, 0.5 mol of phosphorus nitride, and 6 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added, and the mixture was ball-milled for 15 hours at 700 rpm to obtain a first mixture. Then, sulfur, p-benzyl bromide, pyrophosphate, potassium nitrate, and activated carbon particles were removed in a molar ratio of 2:2:2:0.001:1. The sulfur, p-benzyl bromide, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 5 hours at 600 rpm. Activated carbon particles were added again to obtain a second mixture. Finally, the first and second mixtures were removed in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 800°C for 5 hours in air. After cooling to room temperature, the coating layer was removed, and the sintered product was ground and pressed into tablets to obtain Li. 4.3 Eu 0.1 PS 3.4 Br 2.8 The sulfide solid electrolyte had a room-temperature ionic conductivity of 6.7 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 94.7%.

[0041] Example 12:

[0042] Preparation of Li6Eu using the present invention 0.2 PS 4.9 Cl 1.8 Sulfide solid electrolyte. 1.8 mol of lithium chloride, 2.3 mol of lithium oxalate, 0.1 mol of europium carbonate, 0.5 mol of phosphorus nitride, and 7.3 mol of sulfur were weighed and poured into a ball mill jar. Zirconia balls were added, and the mixture was ball-milled for 18 hours at 400 r / min to obtain a first mixture for later use. Then, sulfur, dichloroacetyl chloride, pyrophosphate, potassium nitrate, and activated carbon granules were taken out in a molar ratio of 2:2:2:0.001:1. The sulfur, dichloroacetyl chloride, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 2 hours at 800 r / min. Activated carbon granules were then added to obtain a second mixture for later use. Finally, the first mixture and the second mixture were taken out in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible, which was placed in a sintering furnace and sintered at 900°C for 6 hours in air atmosphere. After cooling to room temperature, the mixture was removed, the wrapping layer was removed, and the sintered product was ground and pressed into tablets to obtain Li6Eu. 0.2 PS 4.9 Cl 1.8The sulfide solid electrolyte had a room-temperature ionic conductivity of 6.4 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 91.4%.

[0043] Example 13:

[0044] Preparation of Li6Eu using the present invention 0.2 PS 4.9 F 1.8 Sulfide solid electrolyte. 4.1 mol lithium oxalate, 0.1 mol europium carbonate, 0.5 mol phosphorus nitride, 7.3 mol sulfur, and 1.8 mol benzene fluoride were weighed and poured into a ball mill jar. Zirconia balls were added and the mixture was ball-milled for 18 hours at 400 r / min to obtain a first mixture for later use. Then, sulfur, benzene fluoride, pyrophosphate, potassium nitrate, and activated carbon granules were taken out in a molar ratio of 2:2:2:0.001:1. Sulfur, benzene fluoride, pyrophosphate, and potassium nitrate were then placed in a jar mill and ball-milled for 2 hours at 800 r / min. Activated carbon granules were then added to obtain a second mixture for later use. Finally, the first mixture and the second mixture were taken out in a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible and placed in a sintering furnace. Sintering was carried out at 900°C for 6 hours in air atmosphere. After cooling to room temperature, the coating layer was removed, and the sintered product was ground and pressed into tablets to obtain Li6Eu. 0.2 PS 4.9 F 1.8 The sulfide solid electrolyte had a room-temperature ionic conductivity of 5.2 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C for 40 cycles, the capacity retention rate was 92.5%.

[0045] Example 14:

[0046] Preparation of Li4Gd using the present invention 0.1 PS3Br 3.3Sulfide solid electrolyte. 3.8 mol lithium nitrate, 0.1 mol gadolinium carbonate, 0.6 mol phosphorus nitride, 4.5 mol sulfur, and 1.65 mol p-benzyl bromide were weighed and poured into a ball mill jar. Zirconia balls were added and the mixture was ball-milled for 20 hours at 600 r / min to obtain the first mixture for later use. Then, sulfur, p-benzyl bromide, pyrophosphate, potassium nitrate, and activated carbon particles were removed according to a molar ratio of 2:2:2:0.001:1. The sulfur, p-benzyl bromide, pyrophosphate, and nitric acid were then... Potassium was placed in a ball mill and milled for 6 hours at a speed of 550 r / min. Activated carbon granules were then added to obtain a second mixture for later use. Finally, the first and second mixtures were taken out at a mass ratio of 1.25:1. The first mixture was then wrapped around the second mixture in a cylindrical crucible and placed in a sintering furnace. Sintering was carried out at 700°C for 12 hours in air atmosphere. After cooling to room temperature, the coating layer was removed, and the sintered product was then ground and pressed into tablets to obtain Li4Gd. 0.1 PS3Br 3.3 The sulfide solid electrolyte had a room-temperature ionic conductivity of 5.32 × 10⁻⁶. -3 S cm -1 A composite cathode prepared with lithium cobalt oxide and solid electrolyte in a ratio of 7:3 was used as the positive electrode, and a lithium sheet was used as the negative electrode. After constant current charge-discharge test at 0.1C, the capacity retention rate was 92% after 40 cycles.

[0047] Performance testing

[0048] Conductivity test: The above Examples 1-6 were loaded into the pressure battery test mold, and the assembled pressure battery (both positive and negative electrodes are stainless steel, and the electrolyte is the example electrolyte) was subjected to impedance test at a test temperature of 25°C.

[0049] Cycle stability of sulfide solid-state batteries was tested: The all-solid-state batteries (positive electrode: lithium cobalt oxide and target electrolyte mixture, 5 mg, LiCoO2:electrolyte = 7:3, negative electrode: lithium sheet, electrolyte: example electrolyte) prepared in Examples 1-5 and Comparative Examples 1-2 were tested under constant current charge and discharge at 0.1C, with a charge and discharge range of 3V-4.2V and a test temperature of 25°C at room temperature.

[0050] Figure 1 The figures show the EIS impedance diagrams of the sulfide solid electrolytes prepared in Examples 1-6. As can be seen from the figures, the solid electrolytes obtained in Examples 1-6 have high conductivity.

[0051] Figure 2 The figure shows the performance test results of the full cell prepared in Example 1 under 40 charge-discharge cycles at 0.1C. It can be seen from the figure that the sulfide all-solid-state battery prepared in Example 1 is stable to the lithium anode and has a high discharge capacity retention rate.

Claims

1. A method for preparing a sulfide solid electrolyte, characterized in that, The chemical composition is: Li a A x PS b B y (B is one of F, Cl, or Br), where 0.1 ≤ x ≤ 0.5, 0.5 ≤ y ≤ 5, 1 ≤ a ≤ 6, 2 ≤ b ≤ 5. The preparation method includes the following steps: (1) The lithium source, the A-containing compound, the phosphorus source and the sulfur source were ball-milled and mixed to obtain a first mixture for later use; (2) Grind and mix the sulfur source, phosphorus source II, B source and M-containing compound, and then add carbon material to obtain a second mixture; (3) After taking out the first mixture and the second mixture according to the mass ratio, wrap the first mixture into the second mixture in a cylindrical crucible and put it into a sintering furnace. Then remove the wrapping layer and grind the sintered product to obtain a sulfide solid electrolyte.

2. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, In step (1), the ball milling time is 1-20h and the rotation speed is 200-800r / min, so that the raw materials are fully mixed.

3. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, In step (1), the molar ratio of lithium source to element A in the compound containing A is 3:1-45:1, the molar ratio of sulfur source to element A in the compound containing A is 6:1-50:1, and the molar ratio of phosphorus source one to element A in the compound containing A is 3:1-16:

1.

4. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, The compound containing A is one of A-containing chloride and A-containing carbonate, wherein A is one of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, and gadolinium.

5. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, The sulfur source is one of sulfur powder, ammonium thiocyanate, or thiourea.

6. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, The compound containing M is one of lithium carbonate, lithium sulfate, lithium phosphate, sodium carbonate, sodium sulfate, sodium chloride, sodium phosphate, potassium carbonate, calcium carbonate, barium carbonate, potassium nitrate, calcium nitrate, iron oxide, and copper oxide.

7. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, Phosphorus source one is one of phosphorus powder, phosphorus oxide, phosphorus nitride, triphenylphosphine, polyphosphoric acid, urea phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, pyrophosphate, hexametaphosphate, and tripolyphosphoric acid. Phosphorus source two is one of urea phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, pyrophosphate, hexametaphosphate, and tripolyphosphoric acid.

8. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, The lithium source is one of several lithium carbonate, lithium oxide, lithium chloride, lithium phosphate, lithium oxalate, lithium formate, lithium nitrate, lithium bromide, and lithium fluoride.

9. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, The source B is one of 4-fluorotrifluorotoluene, 3-fluorotrifluorotoluene, fluorinated benzene, trifluorotoluene, bromoacetyl bromide, p-bromobenzyl bromide, 3-bromobenzyl bromide, bromoisobutyryl bromide, chloroacetyl chloride, p-chlorobenzyl chloride, trichloroacetyl chloride, and dichloroacetyl chloride.

10. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, In step (2), the ball milling time is 1-12 hours and the rotation speed is 100-800 r / min. The carbon material is one of activated carbon, graphite, hard carbon, or carbon fiber powder.

11. The method for preparing a sulfide solid electrolyte according to claim 1, characterized in that, In step (3), the sintering furnace is one of a muffle furnace, a box furnace, or a tube furnace, the sintering atmosphere is an air atmosphere, the sintering temperature is 500-1000℃, and the sintering time is 1-12h.

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