Coated sulfide solid electrolyte and preparation method thereof
By generating an organic lithium compound coating layer on the surface of the sulfide electrolyte, the problem of the nanoscale sulfide electrolyte reacting with the solvent during the drying process is solved, thus improving the air stability and conductivity of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-03-13
AI Technical Summary
Nanoscale sulfide electrolytes readily form sulfur/phosphorus complexes with solvents during the drying process, which are difficult to remove, affecting performance and reducing air stability and structural stability.
Ester compounds are used as milling solvents to refine sulfide electrolyte particles through milling. These particles are then mixed with organic lithium compounds to generate new organic lithium compounds that coat the surface of the sulfide electrolyte, forming an in-situ coating layer that improves the air stability and structural stability of the material.
It effectively prevents the reaction between sulfide electrolytes and solvents, improves the air stability and structural stability of the material, and enhances Li+ transport capability, thus alleviating the problem of decreased conductivity.
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Figure CN121662960A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of solid-state battery technology, specifically to a coated sulfide solid electrolyte and its preparation method. Background Technology
[0002] Solid-state batteries have been extensively studied due to their potential for high safety, high energy density, and long cycle life. Among them, sulfide solid electrolytes have become a key material with great application prospects in the field of solid-state batteries due to their excellent comprehensive performance.
[0003] The main preparation method for sulfide solid electrolytes is the solid-phase method. However, the particles are mostly micrometer-sized and cannot be used directly. Further wet refining with organic solvents is required to achieve nanoscale size, followed by centrifugation and drying to obtain dry powder. However, nanoscale sulfide electrolytes, due to their excessively large specific surface area, easily form sulfur / phosphorus complexes with solvents, which are difficult to remove during drying, thus affecting their performance. Furthermore, the increased specific surface area of nanoscale sulfide electrolytes significantly reduces their air stability and structural stability. Summary of the Invention
[0004] To address the aforementioned technical problems, this application provides a technical solution for a coated sulfide solid electrolyte and its preparation method, as described below: On one hand, embodiments of this application provide a method for preparing a coated sulfide solid electrolyte, the method comprising: The sulfide electrolyte and the sand milling solvent are mixed and then sand milled to obtain a sulfide electrolyte slurry; the sand milling solvent is an ester compound. The sulfide electrolyte slurry is filtered to obtain a wet sulfide electrolyte. The wet sulfide electrolyte is mixed with an organic lithium compound and then dried to obtain a coated sulfide solid electrolyte.
[0005] In one possible implementation, the step of mixing the wet sulfide electrolyte with an organolithium compound and then drying it to obtain a coated sulfide solid electrolyte includes: The sulfide electrolyte wet material is mixed with the organolithium compound to allow the milling solvent in the sulfide electrolyte wet material to undergo a lithiation reaction with the organolithium compound, thereby obtaining a mixed wet material. The mixed wet material is subjected to vacuum drying to obtain the coated sulfide solid electrolyte.
[0006] In one possible implementation, the mass ratio of the sulfide electrolyte to the organic lithium compound is 20:1 to 1000:1.
[0007] In one possible implementation, the sulfide electrolyte has the chemical formula Li6. x PS5 x Cl 1+x , where x = 0~0.99; The organolithium compound is at least one of ethyl lithium, butyl lithium, and phenyl lithium.
[0008] In one possible implementation, the step of mixing the sulfide electrolyte and the milling solvent and then milling them to obtain a sulfide electrolyte slurry includes: The sulfide electrolyte and the milling solvent are mixed to obtain the sulfide electrolyte mixture; The sulfide electrolyte mixture is subjected to sand milling until it is milled to the target particle size, thereby obtaining the sulfide electrolyte slurry.
[0009] In one possible implementation, the target particle size includes D50 ≤ 1 μm; The conditions for the sand milling process are: the sand milling speed is 800 rpm to 2000 rpm, and the sand milling temperature is 20℃ to 60℃.
[0010] In one possible implementation, the filtration of the sulfide electrolyte slurry to obtain a wet sulfide electrolyte comprises: The sulfide electrolyte slurry is centrifuged and filtered to obtain the sulfide electrolyte wet material, wherein the solvent content of the sulfide electrolyte wet material is less than or equal to 20%.
[0011] In one possible implementation, the milling solvent is at least one of ethyl acetate, isobutyl isobutyrate, isoamyl isovalerate, ethyl benzoate, etc. The mass ratio of the sulfide electrolyte to the milling solvent is between 1:1 and 1:20.
[0012] In one possible implementation, the mixing speed is 100 rpm to 500 rpm, and the mixing time is 10 min to 120 min; The drying temperature for the drying process is 80h~200℃, and the drying time is 5h-24h.
[0013] On the other hand, this application embodiment also provides a coated sulfide solid electrolyte, which is prepared by the above-described method for preparing coated sulfide solid electrolyte. The coated sulfide solid electrolyte includes a sulfide electrolyte and an organic lithium compound coated on the outer layer of the coated sulfide solid electrolyte.
[0014] On the other hand, embodiments of this application also provide a solid-state battery, which includes the above-mentioned coated sulfide solid electrolyte, or a solid electrolyte membrane prepared by the above-mentioned method for preparing coated sulfide solid electrolyte.
[0015] The coated sulfide solid electrolyte and its preparation method provided in this application have the following technical effects: (1) When organic lithium compounds are mixed with nanoscale sulfide electrolyte wet material obtained by sand milling and filtration, the organic lithium compounds react with the remaining solvent to generate new organic lithium compounds. During this process, the newly generated organic lithium compounds will uniformly coat the surface of sulfide electrolyte nanoparticles to form an in-situ coating layer, thereby improving the air stability and structural stability of the material. (2) The coating layer is an organic lithium compound, which has good Li+ transport capability and can alleviate the problem of the significant decrease in conductivity of sulfide electrolyte due to the decrease in particle size. (3) The organic lithium compounds have R′, R″ and R+ groups, which can prevent ester solvents from remaining on the surface of sulfide electrolyte nanoparticles during subsequent drying due to the mutual restraint between the same alkyl groups, thereby improving the drying effect of the material. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic flowchart of a method for preparing a coated sulfide electrolyte provided in an embodiment of this application.
[0018] Figure 2 This is a scanning electron microscope image of a coated sulfide electrolyte provided in the embodiments of this application.
[0019] Figure 3 This is an XRD pattern of a coated sulfide electrolyte provided in the embodiments of this application.
[0020] Figure 4 This is a particle size test diagram of a sulfide electrolyte slurry provided in the embodiments of this application. Detailed Implementation
[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0022] It should be noted that, in the description of this application, the following definitions shall apply unless a different definition is given elsewhere in the claims or this specification. All numerical values, whether or not explicitly indicated, are defined herein as being modified by the term "about". The term "about" generally refers to a range of numerical values that a person skilled in the art would consider equivalent to the stated values to produce substantially the same properties, functions, results, etc. A range of numerical values indicated by a low value and a high value is defined as including all numerical values within that range and all subranges included within that range.
[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.
[0024] On the one hand, embodiments of this application provide a method for preparing a coated sulfide solid electrolyte. Figure 1 This is a schematic flowchart illustrating a method for preparing a coated sulfide solid electrolyte according to an embodiment of this application. Figure 1 The preparation method includes: S10: The sulfide electrolyte and the sand milling solvent are mixed and then sand milled to obtain a sulfide electrolyte slurry; the sand milling solvent is an ester compound.
[0025] In this embodiment, the sulfide electrolyte and the milling solvent are first mixed and then milled. The purpose of milling is to refine the particle size of the sulfide electrolyte, thereby reducing the particle size of the sulfide particles. The milling solvent is an ester compound. Due to the steric hindrance effect in the ester structure, its derivatives are not easily crystallized. Therefore, using an ester compound as the milling solvent can effectively prevent flocculation and coarsening of the sulfide electrolyte, provide sustained dispersion stability, and reduce sedimentation. After milling, a sulfide electrolyte slurry is obtained.
[0026] In one feasible embodiment, the sulfide electrolyte has the chemical formula Li6. x PS5 x Cl 1+x Where x = 0~0.99. Exemplarily, the sulfide electrolyte in this application embodiment uses lithium phosphorus sulfur chloride (LPSC), i.e., Li6... x PS5 x X 1+x LPSC possesses core advantages such as high ionic conductivity and mechanical flexibility. Ester compounds are chosen as the milling solvent because LPSC does not react with ester compounds to produce byproducts.
[0027] S30: The sulfide electrolyte slurry is filtered to obtain a wet sulfide electrolyte.
[0028] In this embodiment, to remove most of the milling solvent from the sulfide electrolyte slurry, the sulfide electrolyte slurry is filtered to obtain a wet sulfide electrolyte. It should be noted that the wet sulfide electrolyte still contains some residual milling solvent.
[0029] Optional filtration methods include, but are not limited to, centrifugation, atmospheric pressure filtration, vacuum filtration (slip filtration), and pressure filtration.
[0030] S50: The wet sulfide electrolyte is mixed with an organic lithium compound and then dried to obtain a coated sulfide solid electrolyte.
[0031] In this embodiment, the organolithium compound is an organometallic compound containing a carbon-lithium bond (C-Li), with the general formula RLi (R being a hydrocarbon group). After mixing the wet sulfide electrolyte and the organolithium compound, the organolithium compound and the milling solvent in the wet sulfide electrolyte, i.e., the organolithium compound and the ester compound, undergo a lithiation reaction to generate a new organolithium compound, which coats the surface of the sulfide electrolyte particles. During the mixing process, the mixture formed by the wet sulfide electrolyte and the organolithium compound is continuously stirred, so that the newly formed organolithium compound can uniformly coat the surface of the sulfide electrolyte. After drying, a coated sulfide solid electrolyte is obtained.
[0032] The reaction equations for the process of mixing the sulfide electrolyte wet material with the organic lithium compound are shown below: R′COOR″+ 2R + Li - →R′-C(OLi)(R + )2+ R″OLi; In the above equation, R′COOR″ represents an ester compound, R+Li- represents an organolithium compound, and R′-C(OLi)(R + R′-C(OLi)(R)2 and R″OLi are novel organolithium compounds. These newly formed organolithium compounds are insoluble in ester solvents and, during the reaction, can uniformly coat the surface of sulfide electrolyte nanoparticles, forming a complete coating layer. This effectively prevents the material from being damaged by water and oxygen in the air, improving its air stability and structural stability. Furthermore, R′-C(OLi)(R)2 and R″OLi are novel organolithium compounds. + )2 and R″OLi have certain Li + The transport capacity can alleviate the problem of a significant decrease in conductivity of sulfide electrolytes due to the reduction in particle size; at the same time, the presence of R′, R″, and R+ groups can prevent ester solvents from remaining on the surface of sulfide electrolyte nanoparticles during subsequent drying due to the holding effect between the same alkyl groups, thereby improving the drying effect.
[0033] Optionally, the median particle size of the resulting coated sulfide solid electrolyte is approximately 0.1 μm - 2 μm.
[0034] In one feasible implementation, the organolithium compound is at least one of ethyllithium, butyllithium, and phenyllithium. In the embodiments of this application, the organolithium compound can react with the organic solvent in the wet material to generate a new organolithium compound, achieving an in-situ coating effect. Furthermore, the organic groups in the organolithium compound can repel the organic solvent, i.e., the milling solvent, thereby improving the drying effect.
[0035] In one feasible embodiment, in step S50 above, the process of mixing the wet sulfide electrolyte with an organolithium compound and then drying it to obtain a coated sulfide solid electrolyte includes: S51: The sulfide electrolyte wet material is mixed with the organolithium compound to allow the milling solvent in the sulfide electrolyte wet material to undergo a lithiation reaction with the organolithium compound, thereby obtaining a mixed wet material; S53: The mixed wet material is subjected to vacuum drying to obtain the coated sulfide solid electrolyte.
[0036] In one feasible implementation, in step S50 above, the mixing speed is 100 rpm to 500 rpm and the mixing time is 10 to 120 min; the drying temperature is 80 h to 200 °C and the drying time is 5 h to 24 h.
[0037] In one feasible embodiment, the mass ratio of the sulfide electrolyte to the organolithium compound is 20:1 to 1000:1.
[0038] In this embodiment, before mixing the wet sulfide electrolyte with the organic lithium compound, the mass of the organic lithium compound is first determined based on the mass of the sulfide electrolyte added in step S10. The mass ratio of the sulfide electrolyte to the organic lithium compound is 20:1 to 1000:1. Controlling the sulfide electrolyte and organic lithium compound to a suitable ratio allows for control of the coating thickness and uniformity, and ensures that the performance of the sulfide electrolyte material itself is not affected while improving the material's air stability and structural stability.
[0039] Then, the wet sulfide electrolyte is mixed with the organic lithium compound so that, during the mixing process, the residual milling solvent in the wet sulfide electrolyte reacts with the organic lithium compound to form a new organic lithium compound.
[0040] Optionally, the mixing process can be carried out by mechanical mixing, that is, by using a mixer. When using mechanical mixing, the mixing speed is 100 rpm to 500 rpm and the mixing time is 10 min to 120 min.
[0041] Optionally, the mixing process can also employ ball milling, sand milling, or grinding. When using ball milling, sand milling, or grinding, the mixing time and other conditions should be adjusted adaptively according to the actual situation.
[0042] After thorough mixing, the resulting mixture, i.e., the wet mixture, is dried. Optionally, vacuum drying can be used, with a drying temperature of 80-200℃ and a drying time of 5-24 hours. Vacuum drying not only significantly shortens the drying time but also prevents the coated sulfide electrolyte from oxidizing at high temperatures. Furthermore, vacuum drying facilitates the gentle removal of solvents, reduces hard agglomeration caused by capillary stress between particles, and maintains the pore structure, thus ensuring excellent material structure and morphology. In addition, for battery materials, vacuum drying ensures key properties such as ionic conductivity and interfacial contact.
[0043] In one feasible embodiment, the step of mixing the sulfide electrolyte and the milling solvent and then milling them to obtain a sulfide electrolyte slurry includes: The sulfide electrolyte and the milling solvent are mixed to obtain the sulfide electrolyte mixture; The sulfide electrolyte mixture is subjected to sand milling until it is milled to the target particle size, thereby obtaining the sulfide electrolyte slurry.
[0044] In one feasible implementation, the target particle size includes D50≤1μm; the conditions for the sand milling process are: sand milling speed of 800rpm~2000rpm, and sand milling temperature of 20℃~60℃.
[0045] In one feasible embodiment, the milling solvent is at least one of ethyl acetate, isobutyl isobutyrate, isoamyl isovalerate, ethyl benzoate, etc. The mass ratio of the sulfide electrolyte to the milling solvent is between 1:1 and 1:20.
[0046] In this embodiment, the sulfide electrolyte and the milling solvent are first thoroughly mixed to obtain a sulfide electrolyte mixture. Then, the particle size of the sulfide electrolyte is refined by milling to ensure that the particle size of the sulfide electrolyte meets the requirement of D50≤1μm, resulting in a sulfide electrolyte slurry. The milling speed is 800rpm~2000rpm, and the milling temperature is 20℃~60℃. Thus, by selecting a suitable milling solvent and milling process, the sulfide electrolyte powder is refined.
[0047] Optionally, the milling time is 20-60 minutes, which can be adjusted according to the particle size test results during the actual preparation process.
[0048] In one feasible embodiment, the step of filtering the sulfide electrolyte slurry to obtain a wet sulfide electrolyte includes: centrifuging and filtering the sulfide electrolyte slurry to obtain the wet sulfide electrolyte, wherein the solvent content of the wet sulfide electrolyte is less than or equal to 20%.
[0049] Optionally, the parameters for centrifugal filtration can be a centrifugal speed of 3000 rpm to 6000 rpm and a centrifugation time of 10 min to 30 min; preferably, the centrifugal speed is 4000 rpm and the centrifugation time is 15 min.
[0050] In this embodiment, centrifugation is used to remove part of the solvent from the sulfide electrolyte slurry, resulting in a wet sulfide electrolyte with a solvent content of less than or equal to 20%. Using this wet sulfide electrolyte in the subsequent coating process allows the milling solvent in the wet material to react with the organolithium compounds, generating new organolithium compounds. Furthermore, using ester compounds as milling solvents effectively prevents the sulfide electrolyte from flocculating and coarsening due to the steric hindrance effect in the ester structure, thus providing sustained dispersion stability and reducing sedimentation.
[0051] On the other hand, this application embodiment also provides a coated sulfide solid electrolyte, which is prepared by the above-described method for preparing coated sulfide solid electrolyte. The coated sulfide solid electrolyte includes a sulfide electrolyte and an organic lithium compound coated on the outer layer of the coated sulfide solid electrolyte.
[0052] On the other hand, embodiments of this application also provide a solid-state battery, which includes the above-mentioned coated sulfide solid electrolyte, or a solid electrolyte membrane prepared by the above-mentioned method for preparing coated sulfide solid electrolyte.
[0053] For example, a solid-state battery includes a positive electrode layer, a negative electrode layer, and a separator layer, with the separator layer located between the positive electrode layer and the negative electrode layer. At least one of the positive electrode layer, the negative electrode layer, and the separator layer includes the aforementioned coated sulfide solid electrolyte. In some exemplary embodiments, the positive electrode layer, the negative electrode layer, or the separator layer includes the aforementioned coated sulfide solid electrolyte. In other exemplary embodiments, at least two of the positive electrode layer, the negative electrode layer, and the separator layer include the aforementioned coated sulfide solid electrolyte. In still other exemplary embodiments, the positive electrode layer, the negative electrode layer, and the separator layer all include the aforementioned coated sulfide solid electrolyte. Thus, the placement of the solid electrolyte is flexible and can meet the performance requirements of different battery materials, thereby meeting the performance improvement requirements of different all-solid-state batteries.
[0054] It is understood that the proportions between the components and the range of process parameters for the preparation method defined in the embodiments of this application include any point value within the above range, including endpoint values and any value between the ranges.
[0055] The technical solution of this application is further illustrated below with a description of the preparation method of the coated sulfide electrolyte. The following examples describe the technical solution of this application in more detail. These examples are for illustrative purposes only, as various modifications and variations within the scope of the disclosure of this application will be apparent to those skilled in the art. The reagents used in the examples are commercially available or synthesized using conventional methods and can be used directly without further processing. Similarly, the instruments and apparatus used in the examples are commercially available.
[0056] Example 1: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 50g of electrolyte crude powder Li 5.4 PS 4.4 Cl 1.6200g of ethyl acetate was stirred and mixed evenly and then put into a sand mill for fine grinding. The sand milling speed was 1000rpm and the sand milling time was 30min. The mass ratio of sulfide electrolyte to sand milling solvent was 1:4. (2) Take a small amount of slurry for particle size testing. D50=0.9µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 0.5g of butyllithium into a mixer and mix at 200rpm for 30min; (4) After mixing, take out the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 100°C for 12 hours to finally obtain the coated sulfide electrolyte.
[0057] Example 2: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 50g of electrolyte crude powder Li 5.4 PS 4.4 Cl 1.6 100g of isobutyl isobutyrate was stirred and mixed evenly and then put into a sand mill for fine grinding. The sand milling speed was 800rpm and the sand milling time was 45min. The mass ratio of sulfide electrolyte to sand milling solvent was 1:2. (2) Take a small amount of slurry for particle size testing. D50=0.9µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 1.0g of ethyl lithium into a mixer and mix at 200rpm for 30min; (4) After mixing, take out the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 100°C for 12 hours to finally obtain the coated sulfide electrolyte.
[0058] Example 3: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 100g of electrolyte crude powder Li 5.4 PS 4.4 Cl 1.6 100g of ethyl acetate was stirred and mixed evenly and then put into a sand mill for fine grinding. The sand milling speed was 1000rpm and the sand milling time was 45min. The mass ratio of sulfide electrolyte to sand milling solvent was 1:1. (2) Take a small amount of slurry for particle size testing. D50=0.7µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 2.0g of phenyl lithium into a mixer and mix at 500rpm for 30min; (4) After mixing, take out the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 100°C for 12 hours to finally obtain the coated sulfide electrolyte.
[0059] Example 4: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 100g of electrolyte crude powder Li 5.4 PS 4.4 Cl 1.6 500g of isobutyl isobutyrate was stirred and mixed evenly and then put into a sand mill for fine grinding at a speed of 1500rpm for 30min. (2) Take a small amount of slurry for particle size testing. D50=0.8µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 5.0g of butyllithium into a mixer and mix at 200rpm for 30min; (4) After mixing, take out the wet material, put it into a vacuum oven, and vacuum dry at 120°C for 12 hours to finally obtain the coated sulfide electrolyte.
[0060] Example 5: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 50g of electrolyte crude powder Li 5.4 PS 4.4 Cl 1.6 200g of isobutyl isobutyrate was stirred and mixed evenly and then put into a sand mill for fine grinding at a speed of 1000 rpm for 30 minutes. (2) Take a small amount of slurry for particle size testing. D50=0.9µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 1.0g of ethyl lithium into a mixer and mix at 100rpm for 60min; (4) After mixing, take out the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 80°C for 16 hours to finally obtain the coated sulfide electrolyte.
[0061] Example 6 This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 50g of electrolyte crude powder Li 5.7 PS 4.4 Cl 1.3100g of isoamyl isovalerate was stirred and mixed evenly and then put into a sand mill for fine grinding at a speed of 1500rpm for 30min. (2) Take a small amount of slurry for particle size testing. D50=0.8µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 1.0g of ethyl lithium into a mixer and mix at 200rpm for 45min; (4) After mixing, take out the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 100°C for 12 hours to finally obtain the coated sulfide electrolyte.
[0062] Example 7: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 50g of electrolyte crude powder Li 5.7 PS 4.4 Cl 1.3 100g of ethyl acetate was stirred and mixed evenly and then put into a sand mill for fine grinding at a speed of 1000rpm for 45min. (2) Take a small amount of slurry for particle size testing. D50=0.8µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 2.0g of phenyl lithium into a mixer and mix at 200rpm for 30min; (4) After mixing, take out the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 100°C for 12 hours to finally obtain the coated sulfide electrolyte.
[0063] Example 8: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 100g of electrolyte crude powder Li 5.7 PS 4.4 Cl 1.3 200g of ethyl benzoate, stir and mix evenly and put into a sand mill for fine grinding. The sand mill speed is 1500rpm and the sand milling time is 45min. (2) Take a small amount of slurry for particle size testing. D50=0.7µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 0.5g of butyllithium into a mixer and mix at 200rpm for 30min; (4) After mixing, remove the wet material and put it into a vacuum oven. Dry it at 120°C for 12 hours to obtain the sulfide electrolyte material coated with organic compounds.
[0064] Example 9: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 50g of electrolyte crude powder Li 5.7 PS 4.4 Cl 1.3 200g of isoamyl isovalerate was stirred and mixed evenly and then put into a sand mill for fine grinding at 1000 rpm for 30 minutes. (2) Take a small amount of slurry for particle size testing. D50=0.8µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 0.5g of butyllithium into a mixer and mix at 100rpm for 30min; (4) After mixing, remove the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 120°C for 8 hours to finally obtain the coated sulfide electrolyte.
[0065] Example 10: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 25g of electrolyte crude powder Li6PS5Cl and ethyl acetate, stir and mix evenly, and put them into a sand mill for fine grinding. The sand mill speed is 800rpm and the sand milling time is 45min. (2) Take a small amount of slurry for particle size testing. D50=0.8µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 1.0g of ethyl lithium into a mixer and mix at 100rpm for 60min; (4) After mixing, take out the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 80°C for 16 hours to finally obtain the coated sulfide electrolyte.
[0066] Example 11: This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 50g of electrolyte coarse powder Li6PS5Cl and 500g of isobutyl isobutyrate, stir and mix evenly and put into a sand mill for sand milling and refining. The sand milling speed is 1000rpm and the sand milling time is 45min. (2) Take a small amount of slurry for particle size testing. D50=0.7µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 0.5g of phenyl lithium into a mixer and mix at 500rpm for 15min; (4) After mixing, take out the wet material, put it into a vacuum oven, and vacuum dry at 100°C for 8 hours to finally obtain the coated sulfide electrolyte.
[0067] Example 12 This embodiment provides a method for preparing a coated sulfide electrolyte, the method comprising: (1) Weigh 50g of electrolyte coarse powder Li6PS5Cl and 200g of ethyl benzoate, stir and mix them evenly, and put them into a sand mill for sand milling and refining. The sand milling speed is 800rpm and the sand milling time is 30min. (2) Take a small amount of slurry for particle size testing. D50=0.9µm, which meets the requirements. Take out the slurry and centrifuge it to obtain sulfide electrolyte wet material. (3) Add the wet material and 1.0g of butyllithium into a mixer and mix at 200rpm for 30min; (4) After mixing, take out the wet material and put it into a vacuum oven. Dry it in a vacuum oven at 100°C for 12 hours to finally obtain the coated sulfide electrolyte.
[0068] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that no organic lithium compound is used for coating. After obtaining the wet sulfide electrolyte in step (2), the wet sulfide electrolyte is directly placed in a vacuum oven and vacuum dried at 100°C for 12 hours to obtain the sulfide electrolyte.
[0069] Comparative Example 2: The difference between Comparative Example 1 and Example 1 is that the sulfide electrolyte is coated by dry mixing. Specifically, the sulfide electrolyte obtained in Comparative Example 1 and the organic lithium compound are put into a mixer and mixed at a speed of 200 rpm for 30 minutes to obtain a dry-coated sulfide electrolyte.
[0070] Comparative Example 3: The difference between Comparative Example 1 and Example 6 is that no organic lithium compound is used for coating. After obtaining the wet sulfide electrolyte in step (2), the wet sulfide electrolyte is directly placed in a vacuum oven and vacuum dried at 100°C for 12 hours to obtain the sulfide electrolyte.
[0071] Comparative Example 4: The difference between Comparative Example 1 and Example 10 is that no organic lithium compound is used for coating. After obtaining the wet sulfide electrolyte in step (2), the wet sulfide electrolyte is directly placed in a vacuum oven and vacuum dried at 80°C for 16 hours to obtain the sulfide electrolyte.
[0072] Scanning electron microscope (SEM) images of the coated sulfide electrolyte obtained in Example 1 are shown below. Figure 2 As shown, by Figure 2 It can be confirmed that the coated sulfide electrolyte has a uniform particle size and is evenly dispersed, with no obvious agglomeration observed. The XRD structure of the coated sulfide electrolyte obtained in Example 1 is as follows. Figure 3 As shown, by Figure 3 It can be seen that the microstructure of the sulfide electrolyte was not altered after coating with the organolithium compound, meaning that the organolithium compound did not chemically react with the sulfide electrolyte. The particle size distribution after sand milling in Example 1 is shown in the figure below. Figure 4 As shown, by Figure 4 It can be seen that the median particle size D50 of the coated sulfide electrolyte is less than 1 μm, indicating that sand milling is effective in controlling particle size. It should be noted that in the XRD structure diagram, because the content of organolithium compounds in the coated sulfide electrolyte is extremely low, it exceeds the detection limit of XRD. Therefore, only the structural peaks of the sulfide electrolyte can be seen in the XRD pattern. Furthermore, organolithium compounds do not have obvious characteristic peaks, usually appearing as small-peaked bulges. Compared with the strong characteristic peaks, the XRD structure diagram cannot reveal the characteristic peaks of organolithium compounds.
[0073] Table 1 summarizes the raw materials and process conditions for Examples 1-12.
[0074] Table 1
[0075] The ionic conductivity of the electrolyte materials obtained in Examples 1-12 and Comparative Examples 1-2 was tested, and the results are shown in Table 2. The testing methods used are existing technologies and will not be described in detail here.
[0076] Table 2
[0077] As shown in Tables 1 and 2, comparing Examples 1-5 with Comparative Example 1, Examples 6-9 with Comparative Example 3, and Examples 10-12 with Comparative Example 4, it is evident that the ionic conductivity of the sulfide solid electrolyte after wet coating is significantly higher than that of the uncoated sulfide electrolyte. This indicates that the coating layer, being an organic lithium compound, possesses excellent Li+ transport capabilities, mitigating the problem of a substantial decrease in conductivity caused by the reduction in particle size of the sulfide electrolyte. Comparing Examples 1-5 with Comparative Example 2, it is clear that the wet coating method yields a higher ionic conductivity of the sulfide electrolyte compared to the dry coating method. This is because the wet coating method causes a chemical reaction between the organic lithium compound and the milling solvent, forming a new organic lithium compound. This newly generated organic lithium compound then uniformly coats the surface of the sulfide electrolyte nanoparticles, forming an in-situ coating layer with better coating effect.
[0078] In summary, the use of organolithium compounds to react with the esters in the refined wet sulfide electrolyte material generates new organolithium compounds, forming an in-situ coating layer that improves the coating effect. Simultaneously, the presence of this coating layer significantly enhances the material's air stability and structural stability. Using organolithium compounds with good Li+ transport capabilities for coating can alleviate the problem of a significant decrease in conductivity caused by the reduction in particle size of the sulfide electrolyte. Furthermore, the presence of R′, R″, and R+ groups in the organolithium compounds allows for the retention of ester solvents on the surface of the sulfide electrolyte nanoparticles during subsequent drying due to the inter-alkyl group relationship, thus improving the material's drying effect.
[0079] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0080] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for preparing a coated sulfide solid electrolyte, characterized in that, The preparation method includes: The sulfide electrolyte and the sand milling solvent are mixed and then sand milled to obtain a sulfide electrolyte slurry; the sand milling solvent is an ester compound. The sulfide electrolyte slurry is filtered to obtain a wet sulfide electrolyte. The wet sulfide electrolyte is mixed with an organic lithium compound and then dried to obtain a coated sulfide solid electrolyte.
2. The preparation method according to claim 1, characterized in that, The process of mixing the wet sulfide electrolyte with an organic lithium compound and then drying it to obtain a coated sulfide solid electrolyte includes: The sulfide electrolyte wet material is mixed with the organolithium compound to allow the milling solvent in the sulfide electrolyte wet material to undergo a lithiation reaction with the organolithium compound, thereby obtaining a mixed wet material. The mixed wet material is subjected to vacuum drying to obtain the coated sulfide solid electrolyte.
3. The preparation method according to claim 1, characterized in that, The mass ratio of the sulfide electrolyte to the organic lithium compound is 20:1 to 1000:
1.
4. The preparation method according to claim 1, characterized in that, The chemical formula of the sulfide electrolyte is Li6. x PS5 x Cl 1+x , where x = 0~0.99; The organolithium compound is at least one of ethyl lithium, butyl lithium, and phenyl lithium.
5. The preparation method according to claim 1, characterized in that, The process of mixing sulfide electrolyte and milling solvent and then milling to obtain sulfide electrolyte slurry includes: The sulfide electrolyte and the milling solvent are mixed to obtain the sulfide electrolyte mixture; The sulfide electrolyte mixture is subjected to sand milling until it is milled to the target particle size, thereby obtaining the sulfide electrolyte slurry.
6. The preparation method according to claim 5, characterized in that, The target particle size includes D50≤1μm; The conditions for the sand milling process are: the sand milling speed is 800 rpm to 2000 rpm, and the sand milling temperature is 20℃ to 60℃.
7. The preparation method according to claims 1-6, characterized in that, The step of filtering the sulfide electrolyte slurry to obtain a wet sulfide electrolyte includes: The sulfide electrolyte slurry is centrifuged and filtered to obtain the sulfide electrolyte wet material, wherein the solvent content of the sulfide electrolyte wet material is less than or equal to 20%.
8. The preparation method according to any one of claims 1-6, characterized in that, The milling solvent is at least one of ethyl acetate, isobutyl isobutyrate, isoamyl isovalerate, ethyl benzoate, etc. The mass ratio of the sulfide electrolyte to the milling solvent is between 1:1 and 1:
20.
9. The preparation method according to any one of claims 1-6, characterized in that, The mixing speed is 100 rpm to 500 rpm, and the mixing time is 10 min to 120 min. The drying temperature for the drying process is 80h~200℃, and the drying time is 5h-24h.
10. A coated sulfide solid electrolyte, characterized in that, The coated sulfide solid electrolyte is prepared by the preparation method of the coated sulfide solid electrolyte according to any one of claims 1-9. The coated sulfide solid electrolyte includes a sulfide electrolyte and an organic lithium compound coated on the outer layer of the coated sulfide solid electrolyte.