Composite solvent for ball-milling refinement of argyrodite phase sulfide electrolyte and method for refinement of argyrodite phase sulfide electrolyte

Abstract

The application provides a composite solvent for ball-milling refinement of argyrodite phase sulfide electrolyte and a refinement method of argyrodite phase sulfide electrolyte, and relates to the technical field of solid-state batteries. The composite solvent is composed of dodecyl triethoxysilane and a dispersion buffer solvent, wherein: the dodecyl triethoxysilane can form a coordination bond with the argyrodite phase sulfide electrolyte, so that the electrolyte powder has good dispersibility in the composite solvent, thereby obtaining finer powder after ball milling. At the same time, the dodecyl triethoxysilane can play a role in isolating water molecules from contacting the electrolyte, thereby improving the air stability of the refined powder. In addition, since the dodecyl triethoxysilane is directly used as a dispersant, the conductivity of the electrolyte will decrease, and by selecting a specific dispersion buffer solvent, the problem of conductivity decrease of the electrolyte in the refinement process can be effectively avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state batteries, in particular to a composite solvent for ball-milling refined argyrodite phase sulfide electrolyte and a method for refining argyrodite phase sulfide electrolyte. BACKGROUND

[0002] The existing sulfide electrolyte has two main uses in solid-state battery technology. One is used in composite positive electrode or composite negative electrode to provide ion conductivity. The other is processed into an electrolyte film to act as an intermediate layer to separate the positive electrode and the negative electrode. Regardless of the use, the particle size of the sulfide electrolyte is strictly required. The sulfide electrolyte is usually obtained by solid-phase sintering, and the particle size after grinding and crushing still reaches tens or even hundreds of microns, which cannot be directly used, so further refinement is required to obtain micron or sub-micron fine powder.

[0003] The argyrodite phase LiPSX (X is one or more of F, Cl, Br, and I) sulfide electrolyte has attracted widespread attention from researchers and enterprises in recent years because it can match or even exceed the lithium ion conductivity of electrolyte and is easy to process. However, it is difficult to produce on a large scale outside the glove box because it reacts with water to generate highly toxic hydrogen sulfide and its conductivity also decays rapidly. Currently, to achieve large-scale production of argyrodite phase LiPSX sulfide electrolyte, production needs to be carried out in a dry room with low water content, and the dew point temperature is generally controlled at about -60°C.

[0004] At the same time, the specific surface area of the argyrodite phase LiPSX sulfide electrolyte increases rapidly with the decrease of the particle size during the refinement process. The increase of the specific surface area greatly increases the contact between the powder and the water molecules in the air, which accelerates the deterioration of the electrolyte. Therefore, higher requirements are placed on the air stability of the argyrodite phase LiPSX sulfide electrolyte during the refinement process.

[0005] The existing scheme to improve the air stability of the sulfide electrolyte is ion doping. Based on the "hard-soft acid-base theory", S belongs to soft base and is more inclined to combine with soft acid. Elements such as Sn, Bi, and Sb with weaker acidity than P are usually doped at the "P site" to alleviate the reaction with H2O and improve the air stability. However, after refinement, the improvement of the air stability is not obvious. In addition, coating the micron-level powder after refinement with a hydrophobic solvent is also a feasible scheme, but it usually needs to be refined first, then a certain proportion of hydrophobic solvent is added, and then solvent coating is realized by stirring and other means, which is a complex process.

[0006] Therefore, it is necessary and urgent to develop a refinement method that can obtain sub-micron argyrodite phase LiPSX sulfide electrolyte fine powder and improve its air stability.

[0007] In view of the above, the present application is proposed. SUMMARY

[0008] The first object of the present application is to provide a composite solvent for ball-milling refinement of argyrodite phase sulfide electrolyte, which can effectively improve the air stability of the argyrodite phase sulfide electrolyte after the refinement of the argyrodite phase sulfide electrolyte.

[0009] The second object of the present application is to provide a refinement method of argyrodite phase sulfide electrolyte.

[0010] The third object of the present application is to provide an argyrodite phase sulfide electrolyte.

[0011] The fourth object of the present application is to provide a solid-state battery.

[0012] In order to achieve the above objects of the present application, the following technical solutions are adopted:

[0013] The present application provides a composite solvent for ball-milling refinement of argyrodite phase sulfide electrolyte, which comprises: dodecyl triethoxysilane and a dispersion buffer solvent.

[0014] The dispersion buffer solvent is dimethylbenzene.

[0015] The structural formula of the argyrodite phase sulfide electrolyte is: Li 7-y PS 6-y X y , wherein 0 < y < 1.7, and the X is at least one of F, Cl, Br and I.

[0016] Further, the mass fraction of the dodecyl triethoxysilane in the composite solvent is 0.1-5%.

[0017] The present application provides a refinement method of argyrodite phase sulfide electrolyte, which comprises:

[0018] The argyrodite phase sulfide electrolyte powder is dispersed in the above-mentioned composite solvent, and then ball-milled, dried to obtain the refined argyrodite phase sulfide electrolyte.

[0019] Further, the particle size of the argyrodite phase sulfide electrolyte powder before ball-milling is 5-30 µm, and Dmax≤30 µm.

[0020] The particle size of the refined argyrodite phase sulfide electrolyte powder is 0.5-5 µm, preferably 0.8-1.3 µm.

[0021] Further, the mass ratio of the argyrodite phase sulfide electrolyte powder and the composite solvent is 1:1-10, preferably 1:1-5.

[0022] Further, the ball milling processing mode comprises at least one of mechanical ball milling, vibration ball milling, sand milling and roll milling.

[0023] Preferably, the grinding balls used in the ball milling comprise at least one of zirconia, alumina, agate and stainless steel.

[0024] Preferably, the diameter of the grinding balls is 0.5-10 mm, preferably 0.5-5 mm.

[0025] Further, the ball-to-material ratio of the ball milling is 1-50:1, preferably 5-20:1.

[0026] Preferably, the rotation speed of the ball milling is 100-600 rpm / min, and the time is 2-10 h.

[0027] Further, the drying is vacuum drying.

[0028] Preferably, the vacuum degree of the vacuum drying is-0.02--0.1 MPa, the temperature of the vacuum drying is 50-150 DEG C, and the time of the vacuum drying is 2-8 h.

[0029] The argyrodite phase sulfide electrolyte prepared by the above refining method has a conductivity retention rate of 45-70% after exposure for 24 h.

[0030] The solid-state battery provided by the application comprises the above argyrodite phase sulfide electrolyte.

[0031] Compared with the prior art, the application has the following beneficial effects:

[0032] The application provides a composite solvent for ball milling and refining argyrodite phase sulfide electrolyte, which is composed of dodecyl triethoxysilane and a dispersion buffer solvent, and the dispersion buffer solvent is dimethylbenzene.

[0033] In addition, the applicant found in the research that directly using dodecyl triethoxysilane as a dispersant can cause rapid surface degradation of the LiPSX electrolyte, and then the conductivity is severely reduced. Therefore, the application can effectively avoid the problem of conductivity reduction of the electrolyte in the refinement process by selecting the above specific dispersion buffer solvent.

[0034] The application provides a refinement method of argyrodite phase sulfide electrolyte, the refinement method disperses argyrodite phase sulfide electrolyte powder in the composite solvent, and then performs ball milling and drying to obtain refined argyrodite phase sulfide electrolyte. The preparation method has the technical advantages of simple processing technology and easy operation.

[0035] The application provides an argyrodite phase sulfide electrolyte prepared by the refinement method, the refined argyrodite phase sulfide electrolyte powder has better particle size and air stability, and the conductivity retention rate of the refined argyrodite phase sulfide electrolyte powder after air exposure for 24 hours is 45-70% after detection.

[0036] The argyrodite phase sulfide electrolyte can be widely applied to the preparation of solid-state batteries. DETAILED DESCRIPTION

[0037] The technical solutions of the application will be described clearly and completely in combination with the embodiments. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0038] According to an aspect of the application, a composite solvent for ball milling and refining argyrodite phase sulfide electrolyte comprises dodecyl triethoxysilane and a dispersion buffer solvent.

[0039] The dispersion buffer solvent is dimethylbenzene.

[0040] The structural formula of the argyrodite phase sulfide electrolyte is Li 7-y PS 6-y X y wherein 0

[0041] In view of the technical problems of poor stability after refinement and complex micron-level powder preparation process of the existing argyrodite phase LiPSX (X is one or more of F, Cl, Br and I) sulfide electrolyte, the application provides a composite solvent composed of dodecyl triethoxysilane and a dispersion buffer solvent, wherein:

[0042] The polar group ethoxyl of the dodecyl triethoxysilane can be adsorbed on the Li site of the LiPSX electrolyte surface to form a coordination bond; so that the electrolyte powder has good dispersibility in the composite solvent, so that finer powder can be obtained after ball milling. At the same time, dodecyl triethoxysilane itself has a long carbon chain and strong hydrophobicity, which can prevent water molecules from contacting the electrolyte, alleviate the reaction between water molecules and the electrolyte, and ultimately improve the air stability of the refined sulfide electrolyte.

[0043] In addition, the applicant found in the research that directly using pure dodecyl triethoxysilane as a dispersant can cause rapid degradation of the LiPSX electrolyte surface, and thus the conductivity is severely reduced. Therefore, the application can effectively avoid the problem of conductivity reduction of the electrolyte in the refining process by selecting the specific dispersion buffer solvent of the application.

[0044] In a preferred embodiment of the application, the mass fraction of the dodecyl triethoxysilane in the composite solvent is 0.1-5%.

[0045] As a preferred embodiment, the application can obtain electrolyte powders of different particle sizes by controlling the ratio of dodecyl triethoxysilane to the dispersion buffer solvent, while the existing benzyl ether solvent and the like cannot adjust the particle size by adjusting the ratio.

[0046] According to one aspect of the application, a refining method of argyrodite phase sulfide electrolyte, the refining method comprises:

[0047] The argyrodite phase sulfide electrolyte powder is dispersed in the composite solvent, and then ball milled, dried to obtain the refined argyrodite phase sulfide electrolyte.

[0048] The application provides a refining method of argyrodite phase sulfide electrolyte, the refining method disperses argyrodite phase sulfide electrolyte powder in the composite solvent, and then ball mills and dries to obtain refined argyrodite phase sulfide electrolyte. The preparation method has the technical advantages of simple processing process and easy operation.

[0049] In a preferred embodiment of the application, the particle size of the argyrodite phase sulfide electrolyte powder before ball milling is 5-30 µm, and Dmax≤30 µm;

[0050] The particle size of the refined argyrodite phase sulfide electrolyte powder is 0.5-5 µm, preferably 0.8-1.3 µm.

[0051] In a preferred embodiment of the present application, the mass ratio of the argyrodite phase sulfide electrolyte powder to the composite solvent is 1:1-10, preferably 1:1-5.

[0052] As a preferred embodiment, the mass ratio of the argyrodite phase sulfide electrolyte powder to the composite solvent described above is 1:1-5, which has a better refinement effect. If the ratio is not within this range, for example, if the powder accounts for too high a proportion, the slurry will be too thick, resulting in a large particle size and uneven distribution. If the powder accounts for too small a proportion, i.e., the composite solvent is too much, it will affect the subsequent drying efficiency; secondly, too much solvent will not bring better refinement effect, but will increase the cost.

[0053] In a preferred embodiment of the present application, the ball milling method includes at least one of mechanical ball milling, vibration ball milling, sand milling, and roll milling.

[0054] Preferably, the grinding balls used in the ball milling include at least one of zirconia, alumina, agate, and stainless steel.

[0055] Preferably, the diameter of the grinding balls is 0.5-10 mm, preferably 0.5-5 mm.

[0056] In a preferred embodiment of the present application, the ball-to-material ratio of the ball milling is 1-50:1, preferably 5-20:1.

[0057] Preferably, the number of revolutions of the ball milling is 100-600 rpm / min, and the time is 2-10 h.

[0058] More preferably, the number of revolutions of the ball milling is 200-450 rpm / min, and the time is 4-8 h.

[0059] In a preferred embodiment of the present application, the drying is vacuum drying.

[0060] Preferably, the vacuum degree of the vacuum drying is -0.02 to -0.1 MPa, the temperature of the vacuum drying is 50-150°C, and the time of the vacuum drying is 2-8 h.

[0061] Preferably, the refinement method of the argyrodite phase sulfide electrolyte includes:

[0062] S1. The buffer (dimethylbenzene) and the dispersant (dodecyltriethoxysilane) are weighed according to the proportion respectively.

[0063] S2. The weighed buffer and dispersant are transferred to a sealed container, and magnetic stirring is performed to fully mix them.

[0064] S3. The LiPSX electrolyte coarse powder is weighed according to the proportion and transferred to a zirconia ball milling tank.

[0065] S4, transfer the composite solvent to the above-mentioned ball mill tank;

[0066] S5, weigh the zirconium oxide grinding balls in proportion, transfer them to the above-mentioned ball mill tank and seal it;

[0067] S6, transfer the above-mentioned ball mill tank to the ball mill, set and run the program;

[0068] S7, take out the slurry in the ball mill tank and transfer it to the drying equipment for drying;

[0069] S8, obtain the dried powder and test it.

[0070] According to one aspect of the present application, the argyrodite sulfide electrolyte prepared by the above-mentioned refinement method has a 45-70% conductivity retention rate after being exposed to air for 24 hours.

[0071] The argyrodite sulfide electrolyte prepared by the refinement method of the present application has a better particle size and air stability. The argyrodite sulfide electrolyte powder after refinement has a 45-70% conductivity retention rate after being exposed to air for 24 hours, and preferably 48-58.33%.

[0072] According to one aspect of the present application, a solid-state battery comprises the above-mentioned argyrodite sulfide electrolyte.

[0073] The argyrodite sulfide electrolyte of the present application can be widely used in the preparation of solid-state batteries.

[0074] The technical solutions of the present application will be further described below in conjunction with examples.

[0075] Example 1

[0076] A refinement method of an argyrodite sulfide electrolyte, the refinement method comprising:

[0077] 1. Weigh 0.03 g of dodecyltriethoxysilane and 29.97 g of dimethylbenzene, respectively;

[0078] That is, the proportion of dodecyltriethoxysilane in the composite solvent of this embodiment is 0.1%.

[0079] 2. Mix the weighed dodecyltriethoxysilane and dimethylbenzene, and fully mix them by magnetic stirring to obtain a composite solvent;

[0080] 3. Weigh 10 g of Li 5.4 PS 4.4 Cl1.6 Electrolyte coarse powder (5-30 µm, Dmax < 30 µm) is transferred into a zirconia ball mill jar;

[0081] 4. The composite solvent is transferred into the above ball mill jar, and the Li 5.4 PS 4.4 Cl 1.6 The mass ratio of electrolyte coarse powder to composite solvent is 1:5;

[0082] 5. 200 g of zirconia grinding balls with a diameter of 0.5-5 mm are weighed and transferred into the above ball mill jar and sealed, and the ball-to-material ratio is 20:1;

[0083] 6. The above ball mill jar is transferred into a ball mill, and the rotation speed is set to 450 rpm / min, the ball milling time is 8 h, and the operation program is set;

[0084] 7. The slurry in the ball mill jar is taken out and transferred into a vacuum drying oven;

[0085] 8. The vacuum drying oven is set to a vacuum degree of -0.05 Mpa and a temperature of 100°C, and the vacuum is maintained for 5 h;

[0086] 9. The powder is obtained and tested.

[0087] Example 2

[0088] This example is the same as Example 1 except that in Step 1, “0.3 g of dodecyl triethoxysilane and 29.7 g of xylene are weighed separately”.

[0089] That is, the proportion of dodecyl triethoxysilane in the composite solvent of this example is 1%.

[0090] Example 3

[0091] This example is the same as Example 1 except that in Step 1, “1.5 g of dodecyl triethoxysilane and 28.5 g of xylene are weighed separately”.

[0092] That is, the proportion of dodecyl triethoxysilane in the composite solvent of this example is 5%.

[0093] Example 4

[0094] This example is the same as Example 1 except that in Step 1, “2 g of dodecyl triethoxysilane and 28 g of xylene are weighed separately”.

[0095] That is, the proportion of dodecyl triethoxysilane in the composite solvent of this example is 6.6%.

[0096] Comparative Example 1 (dry method, without solvent refinement)

[0097] A method of refining a argyrodite phase sulfide electrolyte, the method of refining comprising:

[0098] 1. Weigh 10 g Li 5.4 PS 4.4 Cl 1.6 electrolyte coarse powder (5-30 pm, Dmax < 30 pm) and transfer to a zirconia ball mill jar;

[0099] 2. Weigh 200 g zirconia grinding balls with a diameter of 0.5-5 mm, transfer to the above ball mill jar and seal, ball to material ratio is 20:1;

[0100] 3. Transfer the above ball mill jar to a ball mill, set the rotation speed to 150 rpm / min, ball milling time is 20 h, run the program;

[0101] 4. Obtain the powder and test.

[0102] Comparative Example 2 (existing scheme using anisole for refinement)

[0103] A method of refining a argyrodite phase sulfide electrolyte, the method of refining comprising:

[0104] 1. Weigh 10 g Li 5.4 PS 4.4 Cl 1.6 electrolyte coarse powder (5-30 pm, Dmax < 30 pm) and transfer to a zirconia ball mill jar;

[0105] 2. Weigh 30 g anisole, transfer the weighed anisole to the zirconia ball mill jar, the mass ratio of the Li 5.4 PS 4.4 Cl 1.6 electrolyte coarse powder to anisole is 1:5;

[0106] 3. Weigh 200 g zirconia grinding balls with a diameter of 0.5-5 mm, transfer to the above ball mill jar and seal, ball to material ratio is 20:1;

[0107] 4. Transfer the above ball mill jar to a ball mill, set the rotation speed to 450 rpm / min, ball milling time is 8 h, run the program;

[0108] 5. Take out the slurry in the ball mill jar and transfer to a vacuum drying oven;

[0109] 6. Set the vacuum drying oven: vacuum degree is -0.05 Mpa, temperature is 100°C, continue vacuumizing for 5 h;

[0110] 7. Obtain the powder and test.

[0111] Comparative Example 3

[0112] This example is the same as Comparative Example 2 except that "benzyl ether" is replaced by "dodecyl triethoxysilane".

[0113] This comparative example is verified that the powder will be seriously agglomerated after ball milling, and the drying test cannot be carried out.

[0114] Comparative Example 4 (using ethanol instead of dodecyl triethoxysilane)

[0115] A method for refining a argyrodite phase sulfide electrolyte, the method comprising:

[0116] 1. 0.3 g of ethanol, 29.7 g of dimethylbenzene were weighed respectively;

[0117] 2. The weighed ethanol and dimethylbenzene were mixed, and the two were fully mixed and uniformly mixed by magnetic stirring to obtain a composite solvent;

[0118] 3. 10 g of Li 5.4 PS 4.4 Cl 1.6 electrolyte coarse powder (5-30 µm, Dmax < 30 µm) was weighed and transferred to a zirconia ball mill jar;

[0119] 4. The composite solvent was transferred to the above ball mill jar, and the Li 5.4 PS 4.4 Cl 1.6 The mass ratio of the composite solvent to the Li

[0120] 5-9, the same as Example 1.

[0121] Effect Example 1

[0122] The submicron sulfide electrolyte fine powder prepared by Examples 1-4 and Comparative Examples 1, 2, and 4 was detected, and the test conditions were: a drying room, a dew point of -60°C, 0.5 g of powder was taken and laid on the desktop, the laying area was about 6 cm 2 .

[0123] The results are shown in Tables 1 and 2 as follows:

[0124] Table 1: Detection results of argyrodite phase sulfide electrolyte prepared by Examples 1-3:

[0125]

[0126] As can be seen from the above table, the argyrodite phase sulfide electrolyte fine powder prepared by Examples 1-3 of the present application not only has a better particle size, but also effectively improves the air stability of the argyrodite phase sulfide electrolyte.

[0127] The composite solvent of the embodiment 4 is firmly bonded to the electrolyte, and forms a very viscous slurry, which is difficult to dry into powder after ball milling. Therefore, the embodiment 4 is not detected.

[0128] Table 2: The detection results of the argyrodite sulfide electrolyte prepared in Comparative Examples 1, 2 and 4:

[0129]

[0130] As shown in the above table, compared with the embodiments of the present application, the embodiment of Comparative Example 1 uses dry method to refine the electrolyte, and does not perform hydrophobic solvent coating. It is more likely to adsorb water molecules and react to deteriorate, and the conductivity retention rate after exposure for 24 hours decreases significantly. Comparative Example 2 only uses a conventional organic dispersing solvent (anisole), which has no hydrophobic effect. Comparative Example 4 uses a composite solvent of buffer solvent + dispersant (ethanol), which can achieve refinement effect, but the dispersant (ethanol) itself has no hydrophobic effect, so the conductivity of the electrolyte after refinement is not ideal.

[0131] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A composite solvent for ball milling and refining sulfide electrolytes from silver-germanium sulfide minerals, characterized in that, The composite solvent includes: dodecyltriethoxysilane and a dispersion buffer solvent; The dispersion buffer solvent is xylene; The structural formula of the sulfide electrolyte in the silver-germanium sulfide phase is: Li 7-y PS 6-y X y Where 0 < y ≤ 1.7, and X is at least one of F, Cl, Br, and I; The dodecyltriethoxysilane has a mass ratio of 0.1% to 5% in the composite solvent.

2. A method for refining a sulfide electrolyte in a sulfide-silver-germanium mineral phase, characterized in that, The refinement method includes: The sulfur-silver-germanium mineral phase sulfide electrolyte powder was dispersed in the composite solvent described in claim 1, and then ball-milled and dried to obtain the refined sulfur-silver-germanium mineral phase sulfide electrolyte.

3. The refinement method according to claim 2, characterized in that, The particle size of the sulfur-silver-germanium mineral phase sulfide electrolyte powder before ball milling is 5~30 µm, and Dmax≤30µm; The particle size of the refined sulfide electrolyte powder of silver-germanium mineral phase is 0.5~5 µm.

4. The refinement method according to claim 2, characterized in that, The mass ratio of the sulfur-silver-germanium mineral phase sulfide electrolyte powder to the composite solvent is 1:1~10.

5. The refining method according to claim 2, characterized in that, The ball milling process includes at least one of mechanical ball milling, vibratory ball milling, sand milling, and roller milling; The grinding balls used in the ball mill include at least one of zirconium oxide, alumina, agate, and stainless steel.

6. The refinement method according to claim 5, characterized in that, The diameter of the grinding ball is 0.5~10mm.

7. The refining method according to claim 2, characterized in that, The ball-to-material ratio of the ball mill is 1~50:

1.

8. The refining method according to claim 2, characterized in that, The ball milling speed is 100~600 rpm / min, and the time is 2~10h.

9. The refinement method according to claim 2, characterized in that, The drying process is vacuum drying.

10. The refinement method according to claim 9, characterized in that, The vacuum degree of the vacuum drying is -0.02 to -0.1 MPa, the vacuum drying temperature is 50 to 150°C, and the vacuum drying time is 2 to 8 hours.

Images