Composite solvent for sulfide electrolyte sanding, method for preparing nanoscale sulfide electrolyte, and all-solid-state battery
By using a composite solvent composed of aliphatic ethers and hydrofluoroethers in a specific mass ratio, the problems of low refining efficiency and safety hazards of sulfide electrolytes caused by alkane solvents are solved, realizing the efficient preparation and high electronic conductivity of nanoscale sulfide electrolytes, which are suitable for the cathode of all-solid-state batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI XUANYI NEW ENERGY DEV CO LTD
- Filing Date
- 2026-02-13
- Publication Date
- 2026-06-05
AI Technical Summary
In the prior art, when alkane-based nonpolar solvents are used for sand milling of sulfide electrolytes, the refining efficiency is too low and there are safety hazards. Furthermore, the electrolyte ionic conductivity decreases after the addition of dispersants.
A composite solvent composed of aliphatic ether and hydrofluoroether in a specific mass ratio is used for sand milling of sulfide electrolytes to avoid the addition of dispersants, achieve wetting and stable dispersion, improve refining efficiency, and prepare nanoscale sulfide electrolytes by vacuum drying.
The efficient preparation of nanoscale sulfide electrolytes has been achieved, improving the electronic conductivity and safety of the electrolytes and meeting the requirements for cathode applications.
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Figure CN122141830A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of solid-state battery technology, and more specifically, to a composite solvent for milling sulfide electrolytes, a method for preparing nanoscale sulfide solid electrolytes, and an all-solid-state battery. Background Technology
[0002] With the global energy structure shifting towards cleaner and lower-carbon energy sources, high-energy-density, high-safety all-solid-state lithium batteries have become the most promising next-generation electrochemical energy storage devices. Solid-state electrolytes, as the core component of all-solid-state batteries, have received extensive research. Sulfide solid-state electrolytes, due to their ultra-high ionic conductivity, good mechanical properties, and low interfacial impedance, are considered one of the commercially viable materials.
[0003] Currently, electrolytes prepared by large-scale sintering of sulfide electrolytes are usually in bulk form. After being pulverized by roller milling or air jet milling, they can only reach a micrometer-level size, suitable only for electrolyte film layers. However, the particle size (D50) of electrolyte particles used in the cathode typically needs to be less than 1 micrometer. Excessively large electrolyte particles in the cathode result in too many internal pores, preventing the formation of a continuous three-dimensional conductive network, which is detrimental to lithium-ion transport and affects the electrochemical performance of the battery. Large-scale preparation of electrolytes smaller than 1 micrometer is usually achieved through sand milling using non-polar solvents such as alkanes. However, because the solvent and electrolyte do not wet each other, the refining efficiency is usually too low, and alkanes have low flash points, posing safety hazards. To improve dispersion performance, dispersants are added to the solvent to improve electrolyte dispersion. However, existing dispersants often react with the electrolyte or have high boiling points, making complete evaporation difficult and resulting in low electrolyte ionic conductivity.
[0004] In view of the above, this application is hereby submitted. Summary of the Invention
[0005] The main objective of this application is to provide a composite solvent for milling sulfide electrolytes, a method for preparing nanoscale sulfide electrolytes, and an all-solid-state battery. This addresses the problem in the prior art where alkane-based nonpolar solvents are used as milling solvents for sulfide electrolytes. This is because the alkane-based nonpolar solvents do not wet the electrolyte, resulting in excessively low refining efficiency and posing significant safety hazards due to the low flash point of alkane-based solvents.
[0006] To achieve the above objectives, according to one aspect of this application, a composite solvent for sulfide electrolyte milling is provided, the composite solvent comprising aliphatic ether and hydrofluoroether, wherein the mass ratio of the two is 2:98 to 10:90.
[0007] Furthermore, the fatty ether is selected from at least one of n-butyl ether, ethylene glycol dimethyl ether, and methyl propyl ether.
[0008] Furthermore, the hydrofluoroether is selected from at least one of tetrafluoroethyl tetrafluoropropyl ether, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, trifluoroethyl nonafluorobutyl ether, hexafluoropropyl methyl ether, tetrafluoroethyl trifluoroethyl ether, and methyl heptafluoropropyl ether.
[0009] Furthermore, the composite solvent is a mixed solution of n-butyl ether and tetrafluoroethyl tetrafluoropropyl ether, preferably the mass ratio of n-butyl ether to tetrafluoroethyl tetrafluoropropyl ether in the composite solvent is 3:97~10:90.
[0010] To achieve the above objectives, according to a second aspect of this application, a method for preparing a nanoscale sulfide electrolyte is provided. The method includes: step S1, mixing coarse sulfide electrolyte powder with a solvent and milling the mixture to obtain a nanoscale sulfide electrolyte slurry, wherein the solvent is the composite solvent provided in the first aspect; and step S2, removing the solvent from the nanoscale sulfide electrolyte slurry to obtain the nanoscale sulfide electrolyte.
[0011] Further, in step S1, the mass ratio of sulfide electrolyte coarse powder to composite solvent is 10:90~60:40, preferably 15:85~30:70.
[0012] Further, in step S1, the sand grinding is carried out in a sand mill, the size of the grinding beads is 0.2~2mm, and the filling rate of the grinding beads is 50%~80%.
[0013] Further, in step S1, the linear speed of the sand mill is 6~10m / s, and the sand milling time is 1~12h.
[0014] Further, in step S2, solvent removal is carried out by drying, which is vacuum drying. The temperature of vacuum drying is 100~200℃, preferably 120~180℃, and the time of vacuum drying is 2~48h, preferably 5~24h.
[0015] Furthermore, the particle size D50 of the sulfide electrolyte coarse powder is 10~20μm.
[0016] Furthermore, the particle size D50 of the nanoscale sulfide electrolyte is 0.5~1μm.
[0017] Furthermore, the material of the sulfide electrolyte coarse powder includes Li 7-m PS 6-m X m Or Li 10 MP2S 12 At least one of them, wherein Li 7-m PS 6-m X m In this context, X is a halogen, selected from at least one of F, Cl, Br, and I. <m<2;Li 10 MP2S12 In this context, M is at least one of Ge, Sn, and Si.
[0018] According to another aspect of this application, an all-solid-state battery is provided, the all-solid-state battery including a positive electrode, the positive electrode including an electrolyte, the electrolyte being a nanoscale sulfide electrolyte obtained by the preparation method provided in the second typical embodiment above.
[0019] By applying the technical solution of this application, the composite solvent for sand milling of sulfide electrolytes provided in this application, through the synergistic effect of aliphatic ether and hydrofluoroether in a specific mass ratio, can not only effectively wet the coarse powder of sulfide electrolyte without the need to add dispersant during the sand milling process, so that the sulfide electrolyte is stably dispersed in the composite solvent, improving the refining efficiency, but also is non-flammable, has high safety, and can effectively ensure the electronic conductivity of the electrolyte. Attached Figure Description
[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:
[0021] Figure 1 The SEM image of the nanoscale sulfide electrolyte provided in Example 1 is shown. Detailed Implementation
[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.
[0023] As described in the background section of this application, traditional methods use alkane-based nonpolar solvents as milling solvents for preparing nanoscale sulfide electrolytes. However, alkane-based nonpolar solvents do not wet the sulfide electrolyte, resulting in excessively low refining efficiency. Furthermore, the low flash point of alkane-based nonpolar solvents poses a significant safety hazard. Adding dispersants to alkane-based nonpolar solvents to improve dispersibility leads to a decrease in the electrolyte's ionic conductivity due to the reaction between the dispersant and the electrolyte. To address these issues, this application provides a composite solvent for milling sulfide electrolytes, a method for preparing nanoscale sulfide electrolytes, and an all-solid-state battery.
[0024] In a first typical embodiment of this application, a composite solvent for sulfide electrolyte sand milling is provided, which includes aliphatic ether and hydrofluoroether, and the mass ratio of the two is 2:98~10:90.
[0025] The composite solvent for milling sulfide electrolytes provided in this application, by using a specific mass ratio of aliphatic ether and hydrofluoroether in synergy, can effectively wet the coarse sulfide electrolyte powder without the need to add a dispersant during the milling process, so that the sulfide electrolyte is stably dispersed in the composite solvent, improving the refining efficiency. Moreover, it is non-flammable, has high safety, and can effectively ensure the electronic conductivity of the electrolyte.
[0026] In the sulfide electrolyte sand milling composite solvent provided in this application, the mass ratio of aliphatic ether to hydrofluoroether is 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, 9:91, 10:90 or any two of these values.
[0027] The aforementioned aliphatic ethers are commonly used aliphatic ether solvents in the art, including but not limited to any one or more of n-butyl ether, ethylene glycol dimethyl ether, and methyl propyl ether.
[0028] The aforementioned hydrofluoroethers are commonly used hydrofluoroether solvents in the art, including but not limited to any one or more of tetrafluoroethyl tetrafluoropropyl ether, methyl nonafluorobutyl ether, trifluoroethyl nonafluorobutyl ether, hexafluoropropyl methyl ether, tetrafluoroethyl trifluoroethyl ether, and methyl heptafluoropropyl ether.
[0029] In some embodiments of this application, the composite solvent is a mixed solution of n-butyl ether and tetrafluoroethyltetrafluoropropyl ether, and the mass ratio of the two is 2:98 to 10:90, which is more conducive to effectively wetting the sulfide electrolyte, and thus more conducive to improving the sand milling efficiency of the sulfide electrolyte. In particular, when the mass ratio of n-butyl ether to tetrafluoroethyltetrafluoropropyl ether in the composite solvent is 3:97 to 10:90, its wetting effect on the sulfide electrolyte is better, and the sand milling efficiency is higher.
[0030] In a second typical embodiment of this application, a method for preparing nanoscale sulfide electrolyte is provided. The method includes: step S1, mixing coarse sulfide electrolyte powder with a solvent and milling it to obtain nanoscale sulfide electrolyte slurry, wherein the solvent is the composite solvent provided in the first typical embodiment above; step S2, removing the solvent from the nanoscale sulfide electrolyte slurry to obtain nanoscale sulfide electrolyte.
[0031] The method for preparing nanoscale sulfide electrolytes provided in this application uses a composite solvent formed by combining aliphatic ethers and hydrofluoroethers in a specific mass ratio as the solvent for milling sulfide electrolytes. This method not only eliminates the need to add dispersants during milling, but also effectively wets the coarse sulfide electrolyte powder, ensuring stable dispersion of the sulfide electrolyte in the composite solvent, preventing stratification and clogging of the mill, and improving refining efficiency. Furthermore, it is non-flammable, highly safe, and effectively guarantees the electronic conductivity of the electrolyte.
[0032] In some embodiments of this application, to further improve the preparation efficiency of nanoscale sulfide electrolytes, in step S1, the mass ratio of coarse sulfide electrolyte powder to composite solvent is 10:90 to 60:40, which is more conducive to preparing nanoscale sulfide electrolytes with uniform particle size. If the amount of composite solvent is too large, the preparation efficiency of nanoscale sulfide electrolytes is low, resulting in energy waste. If the amount of composite solvent is too small, it is not conducive to uniformly dispersing the coarse sulfide electrolyte powder in the composite solvent, which will lead to a decrease in refining efficiency and poor uniformity of the nanoscale sulfide electrolytes obtained by grinding. In particular, when the mass ratio of coarse sulfide electrolyte powder to composite solvent is 15:85 to 30:70, it is more conducive to improving the preparation efficiency of nanoscale sulfide electrolytes and improving the particle size dispersion uniformity of nanoscale sulfide electrolytes.
[0033] Specifically, in this application, the mass ratio of sulfide electrolyte powder to composite solvent is 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:55, 55:45, 60:40, or any range of two values.
[0034] In some embodiments of this application, in step S1 above, the grinding is performed in a sand mill, the size of the grinding beads is 0.2~2mm, and the filling rate of the grinding beads is 50%~80%, which is more conducive to improving the preparation efficiency of nano-scale sulfide electrolytes. Too low or too high a filling rate of the grinding beads is not conducive to improving the preparation efficiency of nano-scale sulfide electrolytes. Specifically, the size of the grinding beads is 0.2mm, 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 1.8mm, 2mm, or any two of these values; the filling rate of the grinding beads is 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any two of these values.
[0035] In some embodiments of this application, the linear speed of the sand mill is 6-10 m / s, and the milling time is 1-2 h, which is more conducive to improving the efficiency of sand milling and the preparation efficiency of nano-scale sulfide electrolyte. Specifically, the linear speed of the sand mill is 6 m / s, 6.5 m / s, 7 m / s, 7.5 m / s, 8 m / s, 8.5 m / s, 9 m / s, 9.5 m / s, 10 m / s, or any two of these values; the milling time is 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, or any two of these values.
[0036] In some embodiments of this application, the drying in step S2 is vacuum drying to further improve drying efficiency. In some specific embodiments, the vacuum drying temperature is 100~200℃, and the vacuum drying time is 2~48h, which helps to improve the drying efficiency of nano-scale sulfide electrolytes while saving energy. In particular, the drying efficiency of nano-scale sulfide electrolytes is higher when the vacuum drying temperature is 120~180℃ and the vacuum drying time is 5~24h. Specifically, the vacuum drying temperature is 100℃, 120℃, 125℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 200℃ or any two of these values; the vacuum drying time is 2h, 3h, 5h, 8h, 10h, 12h, 15h, 18h, 20h, 24h, 30h, 35h, 40h, 45h, 48h or any two of these values.
[0037] In some embodiments of this application, the particle size D50 of the sulfide electrolyte coarse powder is 10~20μm, so as to facilitate its uniform dispersion in the composite solvent and further improve the wetting efficiency of the composite solvent. Specifically, the particle size D50 of the sulfide electrolyte coarse powder is 10μm, 12μm, 15μm, 18μm, 20μm or any combination of two values.
[0038] In some embodiments of this application, the particle size D50 of the nano-scale sulfide electrolyte is 0.5~1μm, thereby enabling the nano-scale sulfide electrolyte to meet the particle size D50 requirements of electrolyte particles in the positive electrode, which is more conducive to expanding the application prospects of sulfide electrolytes in the positive electrode. Specifically, the particle size D50 of the nano-scale sulfide electrolyte is 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, or any range of two values.
[0039] In this application, the material of the aforementioned sulfide electrolyte crude powder is a sulfide electrolyte commonly used in the art, including but not limited to Li. 7-m PS 6-m X m Or Li 10 MP2S 12 At least one of them, wherein Li 7-m PS 6-m X m In this context, X is a halogen, selected from at least one of F, Cl, Br, and I. <m<2;Li 10 MP2S 12 In this context, M represents at least one of Ge, Sn, and Si. For example, the material of a sulfide electrolyte is Li. 5.5 PS 4.5Cl 1.5 wait.
[0040] In a third typical embodiment of this application, an all-solid-state battery is also provided, which includes a positive electrode and an electrolyte, wherein the electrolyte is a nanoscale sulfide solid electrolyte obtained according to the preparation method provided in the second typical embodiment described above.
[0041] The all-solid-state battery provided in this application uses a composite solvent formed by combining the above-mentioned specific mass ratio of aliphatic ether and hydrofluoroether as a solvent for milling the sulfide electrolyte, and applies the nanoscale sulfide electrolyte prepared by milling to the positive electrode. This not only helps to effectively ensure the electronic conductivity of the electrolyte, but also helps to improve the energy density of the positive electrode.
[0042] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.
[0043] Example 1
[0044] This embodiment provides a method for preparing nanoscale sulfide electrolytes, which are prepared according to the following steps:
[0045] (1) Weigh 4g of n-butyl ether and 76g of tetrafluoroethyl tetrafluoropropyl ether and mix them to prepare 80g of composite solvent.
[0046] (2) Add 20g of electrolyte Li 5.5 PS 4.5 Cl 1.5 Coarse powder (D50 of 15μm) and 80g of composite solvent were placed in the circulating mixing tank of a sand mill. 0.8mm grinding beads were placed in the grinding chamber of the sand mill, with a filling rate of 75%. The sand mill was started, the linear speed was set to 10m / s, and grinding was carried out for 4 hours to obtain nanoscale electrolyte slurry.
[0047] (3) Place the nano-sized electrolyte slurry in a vacuum oven at 160°C and dry it under vacuum for 6 hours to obtain nano-sized sulfide electrolyte powder.
[0048] Example 2
[0049] This embodiment provides a method for preparing nanoscale sulfide electrolytes, which are prepared according to the following steps:
[0050] (1) Weigh 4g of n-butyl ether and 76g of tetrafluoroethyl tetrafluoropropyl ether and mix them to prepare 80g of composite solvent.
[0051] (2) Add 20g of electrolyte Li 5.5 PS 4.5 Cl 1.5Coarse powder (D50 of 15μm) and 80g of composite solvent were placed in the circulating mixing tank of a sand mill. 0.8mm grinding beads were placed in the grinding chamber of the sand mill, with a filling rate of 60%. The sand mill was started, the linear speed was set to 10m / s, and grinding was carried out for 4 hours to obtain nanoscale electrolyte slurry.
[0052] (3) Place the nano-sized electrolyte slurry in a vacuum oven at 160°C and dry it under vacuum for 6 hours to obtain nano-sized sulfide electrolyte powder.
[0053] Example 3
[0054] This embodiment provides a method for preparing nanoscale sulfide electrolytes, which are prepared according to the following steps:
[0055] (1) Weigh 4g of n-butyl ether and 76g of tetrafluoroethyl tetrafluoropropyl ether and mix them to prepare 80g of composite solvent.
[0056] (2) Add 20g of electrolyte Li 5.5 PS 4.5 Cl 1.5 Coarse powder (D50 of 15μm) and 80g of composite solvent were placed in the circulating mixing tank of a sand mill. 0.5mm grinding beads were placed in the grinding chamber of the sand mill, with a filling rate of 75%. The sand mill was started, the linear speed was set to 10m / s, and grinding was carried out for 2 hours to obtain nanoscale electrolyte slurry.
[0057] (3) Place the nano-sized electrolyte slurry in a vacuum oven at 160°C and dry it under vacuum for 6 hours to obtain nano-sized sulfide electrolyte powder.
[0058] Example 4
[0059] The difference between this embodiment and Embodiment 1 is that, in step (1), the mass ratio of n-butyl ether and tetrafluoroethyl tetrafluoropropyl ether in the composite solvent is adjusted to 3:97.
[0060] Example 5
[0061] The difference between this embodiment and embodiment 1 is that, in step (1), the mass ratio of n-butyl ether and tetrafluoroethyl tetrafluoropropyl ether in the composite solvent is adjusted to 10:90.
[0062] Example 6
[0063] The difference between this embodiment and embodiment 1 is that, in step (1), the mass ratio of n-butyl ether and tetrafluoroethyl tetrafluoropropyl ether in the composite solution is adjusted to 2:98.
[0064] Example 7
[0065] The difference between this embodiment and Embodiment 1 is that in step (1), n-butyl ether is replaced with ethylene glycol dimethyl ether.
[0066] Example 8
[0067] The difference between this embodiment and Embodiment 1 is that in step (1), n-butyl ether is replaced with methyl propyl ether.
[0068] Example 9
[0069] The difference between this embodiment and Embodiment 1 is that in step (1), the composite solvent is replaced with a mixed solvent of ethylene glycol dimethyl ether and methyl nonafluorobutyl ether, and the mass ratio of the two is 4:76.
[0070] Example 10
[0071] The difference between this embodiment and embodiment 1 is that in step (1), the composite solvent is replaced with a mixed solvent of methyl propyl ether and ethyl nonafluorobutyl ether, and the mass ratio of the two is 5:75.
[0072] Example 11
[0073] The difference between this embodiment and embodiment 1 is that in step (1), the composite solvent is replaced with n-butyl ether and hexafluoropropyl methyl ether, and the mass ratio of the two is 6:74.
[0074] Example 12
[0075] The difference between this embodiment and Embodiment 1 is that, in step (2), the electrolyte Li 5.5 PS 4.5 Cl 1.5 The mass ratio of coarse powder (D50 is 15μm) to composite solvent is 15:85.
[0076] Example 13
[0077] The difference between this embodiment and Embodiment 1 is that, in step (2), the electrolyte Li 5.5 PS 4.5 Cl 1.5 The mass ratio of coarse powder (D50 is 15μm) to composite solvent is 30:70.
[0078] Example 14
[0079] The difference between this embodiment and Embodiment 1 is that, in step (2), the electrolyte Li 5.5 PS 4.5 Cl 1.5 The mass ratio of coarse powder (D50 is 15μm) to composite solvent is 10:90.
[0080] Example 15
[0081] The difference between this embodiment and Embodiment 1 is that, in step (2), the electrolyte Li 5.5 PS 4.5 Cl 1.5 The mass ratio of coarse powder (D50 is 15μm) to composite solvent is 60:40.
[0082] Comparative Example 1
[0083] This comparative example provides a nanoscale sulfide electrolyte, which is prepared according to the following steps:
[0084] (1) Take 20g of electrolyte Li 5.5 PS 4.5 Cl 1.5 Coarse powder (D50 of 15μm) and 80g of heptane were placed in the circulating mixing tank of a sand mill. 0.8mm grinding beads were placed in the grinding chamber of the sand mill, with a filling rate of 75%. The sand mill was started, the linear speed was set to 10m / s, and grinding was carried out for 4 hours to obtain nanoscale electrolyte slurry.
[0085] (2) Place the nano-sized electrolyte slurry in a vacuum oven at 160°C and dry it under vacuum for 6 hours to obtain nano-sized sulfide electrolyte powder.
[0086] Comparative Example 2
[0087] This comparative example provides a nanoscale sulfide electrolyte, which is prepared according to the following steps:
[0088] (1) Weigh 1g of n-butyl ether and 79g of tetrafluoroethyl tetrafluoropropyl ether and mix them to prepare 80g of composite solvent.
[0089] (2) Add 20g of electrolyte Li 5.5 PS 4.5 Cl 1.5 Coarse powder (D50 of 15μm) and 80g of composite solvent were placed in the circulating mixing tank of a sand mill. 0.8mm grinding beads were placed in the grinding chamber of the sand mill, with a filling rate of 75%. The sand mill was started, the linear speed was set to 10m / s, and grinding was carried out for 4 hours to obtain nanoscale electrolyte slurry.
[0090] (3) Place the nano-sized electrolyte slurry in a vacuum oven at 160°C and dry it under vacuum for 6 hours to obtain nano-sized sulfide electrolyte powder.
[0091] Comparative Example 3
[0092] This comparative example provides a nanoscale sulfide electrolyte, which is prepared according to the following steps:
[0093] (1) Weigh 40g of n-butyl ether and 40g of tetrafluoroethyl tetrafluoropropyl ether and mix them to prepare 80g of composite solvent.
[0094] (2) Add 20g of electrolyte Li 5.5 PS 4.5 Cl 1.5 Coarse powder (D50 of 15μm) and 80g of composite solvent were placed in the circulating mixing tank of a sand mill. 0.8mm grinding beads were placed in the grinding chamber of the sand mill, with a filling rate of 75%. The sand mill was started, the linear speed was set to 10m / s, and grinding was carried out for 4 hours to obtain nanoscale electrolyte slurry.
[0095] (3) Place the nano-sized electrolyte slurry in a vacuum oven at 160°C and dry it under vacuum for 6 hours to obtain nano-sized sulfide electrolyte powder.
[0096] Comparative Example 4
[0097] This comparative example provides a nanoscale sulfide electrolyte, which is prepared according to the following steps:
[0098] (1) Take 20g of electrolyte Li 5.5 PS 4.5 Cl 1.5 Coarse powder (D50 of 15μm) and 80g of n-butyl ether were placed in the circulating mixing tank of a sand mill. 0.8mm grinding beads were placed in the grinding chamber of the sand mill, with a filling rate of 75%. The sand mill was started, the linear speed was set to 10m / s, and grinding was carried out for 4 hours to obtain a nano-sized electrolyte slurry.
[0099] (2) Place the nano-sized electrolyte slurry in a vacuum oven at 160°C and dry it under vacuum for 6 hours to obtain nano-sized sulfide electrolyte powder.
[0100] Comparative Example 5
[0101] The difference between this comparative example and Example 1 is that, in step (1), the mass ratio of n-butyl ether and tetrafluoroethyl tetrafluoropropyl ether in the composite solvent is adjusted to 12:68.
[0102] Experimental Example 1
[0103] The flammability of the sand milling solvent used in the above examples and comparative examples was tested, and the results are shown in Table 1 below.
[0104] The flammability test method is as follows: A 5cm x 5cm piece of non-woven fabric is immersed in a sanding solvent for 5 minutes. Then, the fabric is removed and placed over an alcohol lamp flame. The flammability of the fabric is observed within 5 seconds. The flammability level of the solvent is determined based on the time t required for flammability. A flammability time t < 5 seconds indicates flammability; 5 seconds ≤ t < 20 seconds indicates flammability; 20 seconds ≤ t < 60 seconds indicates low flammability; and t ≥ 60 seconds indicates non-flammability.
[0105] The nanoscale electrolyte slurries prepared in the above examples and comparative examples were left to stand at room temperature for 10 minutes to observe whether they settled. The results are shown in Table 1 below.
[0106] The nanoscale sulfide electrolyte powders provided in the above examples and comparative examples were subjected to particle size D50 and ionic conductivity tests, and the results are shown in Table 1 below.
[0107] Among them, (1) the test method for particle size D50 is: the measurement is performed using a laser diffraction / scattering particle size distribution measuring device (Mastersizer 3000). The specific steps include: using dehydrated butyl butyrate solvent as a dispersion medium, injecting 50 mL of dispersion medium into the flow cell of the device, circulating it, adding nano-sized sulfide electrolyte powder and performing ultrasonic treatment, and then measuring the particle size distribution.
[0108] (2) The method for testing ionic conductivity is as follows: The nano-sized sulfide electrolyte is assembled into a blocking battery with carbon-coated aluminum foil on both sides. The specific steps include: weighing 300 mg of nano-sized sulfide electrolyte powder and placing it into a mold with a diameter of 10 mm, placing it on a press, applying a pressure of 3 t, holding the pressure for 5 min, obtaining an electrolyte sheet, and then placing carbon-coated aluminum foil on both sides of the electrolyte sheet as current collectors to assemble a blocking battery.
[0109] EIS impedance was measured by placing the blocking battery in a constant temperature chamber at 25°C for 1 hour to allow the temperature of the electrolyte inside the battery to reach 25°C. The battery was then connected to Su Liqiang's electrochemical workstation, and the constant voltage AC impedance was measured in the range of 1MHz to 1Hz. The ionic conductivity of the prepared electrolyte was obtained after conversion.
[0110] Table 1
[0111]
[0112] Figure 1 SEM image of the nanoscale sulfide electrolyte powder provided in Example 1, from Figure 1 It can be seen that after ball milling with mixed solvents, the particle size of the prepared sulfide electrolytes is basically less than 1 μm.
[0113] As can be seen from the data in Table 1, comparing the data of Example 1 and Example 3, it can be seen that using smaller-sized grinding beads can achieve a similar refining effect in a shorter time.
[0114] Comparing the data of Example 1 and Comparative Example 1, it can be seen that the grinding effect of the composite solvent is higher than that of heptane, and it can also avoid the risks of short-term sedimentation of slurry and solvent flammability.
[0115] Comparing Examples 1, 4, 5, and 6 with Comparative Examples 2, 3, 4, and 5, it can be seen that if the proportion of n-butyl ether in the composite solvent is too low, the grinding efficiency of the composite solvent will also decrease. When the proportion of n-butyl ether is too high, although the refining efficiency is improved, due to the polarity of n-butyl ether, it will react with the electrolyte, resulting in a significant decrease in the ionic conductivity of the electrolyte after refining.
[0116] Comparing Examples 1, 7, 8, 9, 10, and 11, it is evident that n-butyl ether and tetrafluoroethyltetrafluoropropyl ether are the two ether combinations with the best ionic conductivity and particle size after refining. Comparing Examples 1, 12, 13, 14, and 15, it is evident that when the ratio of electrolyte coarse powder to composite solvent is 15:85 to 30:70, the ball milling efficiency of the electrolyte is the highest and the particle size is the smallest.
[0117] As can be seen from the above description, the above embodiments of this application achieve the following technical effects: The composite solvent for sand milling of sulfide electrolytes provided by this application, by using a specific mass ratio of aliphatic ether and hydrofluoroether to work synergistically, can effectively wet the coarse powder of sulfide electrolytes without the need to add dispersant during the sand milling process, so that the sulfide electrolytes are stably dispersed in the composite solvent, improving the refining efficiency. Moreover, it is not flammable, has high safety, and can effectively ensure the electronic conductivity of the electrolyte.
[0118] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A composite solvent for sulfide electrolyte milling, characterized in that, The composite solvent includes aliphatic ethers and hydrofluoroethers, and the mass ratio of the two is 2:98 to 10:
90.
2. The composite solvent according to claim 1, characterized in that, The fatty ether is selected from at least one of n-butyl ether, ethylene glycol dimethyl ether and methyl propyl ether; And / or, the hydrofluoroether is selected from at least one of tetrafluoroethyl tetrafluoropropyl ether, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, trifluoroethyl nonafluorobutyl ether, hexafluoropropyl methyl ether, tetrafluoroethyl trifluoroethyl ether, and methyl heptafluoropropyl ether.
3. The composite solvent according to claim 1 or 2, characterized in that, The composite solvent is a mixed solution of n-butyl ether and tetrafluoroethyl tetrafluoropropyl ether, preferably in which the mass ratio of n-butyl ether to tetrafluoroethyl tetrafluoropropyl ether is 3:97 to 10:
90.
4. A method for preparing a nanoscale sulfide electrolyte, characterized in that, The preparation method includes: Step S1: The coarse sulfide electrolyte powder is mixed with a solvent and then milled to obtain a nano-sized sulfide electrolyte slurry; wherein the solvent is a composite solvent as described in any one of claims 1 to 3. Step S2: Solvent removal is performed on the nano-scale sulfide electrolyte slurry to obtain the nano-scale sulfide electrolyte.
5. The preparation method according to claim 4, characterized in that, In step S1, the mass ratio of the crude sulfide electrolyte powder to the composite solvent is 10:90~60:40, preferably 15:85~30:
70.
6. The preparation method according to claim 4, characterized in that, In step S1, the sand grinding is carried out in a sand mill, the size of the grinding beads is 0.2~2mm, and the filling rate of the grinding beads is 50%~80%. And / or, the linear velocity of the sand mill is 6~10m / s, and the sand milling time is 1~12h.
7. The preparation method according to claim 4, characterized in that, In step S2, the solvent is removed by drying, which is vacuum drying. The temperature of the vacuum drying is 100~200℃, preferably 120~180℃, and the time of the vacuum drying is 2~48h, preferably 5~24h.
8. The preparation method according to any one of claims 4 to 7, characterized in that, The particle size D50 of the sulfide electrolyte coarse powder is 10~20μm; And / or, the particle size D50 of the nanoscale sulfide electrolyte is 0.5~1μm.
9. The preparation method according to any one of claims 4 to 7, characterized in that, The material of the sulfide electrolyte coarse powder includes Li 7-m PS 6-m X m Or Li 10 MP2S 12 At least one of them; Among them, Li 7-m PS 6-m X m In this context, X is a halogen, and the halogen is selected from at least one of F, Cl, Br, and I. <m<2;Li 10 MP2S 12 In this context, M is at least one of Ge, Sn, and Si.
10. An all-solid-state battery, characterized in that, The all-solid-state battery includes a positive electrode, and the positive electrode includes an electrolyte, wherein the electrolyte is a nanoscale sulfide solid electrolyte obtained by the preparation method according to any one of claims 4 to 9.