Sulfide electrolyte with two-dimensional structure and preparation method thereof

Abstract

The invention relates to the technical field of electrolyte materials, in particular to a sulfide electrolyte with a two-dimensional structure and a preparation method thereof, the chemical general formula of the sulfide electrolyte is Li < 6-x > PS < 5-x > Cl < 1 + x >, 0 < = x < = 0.99, and the sulfide electrolyte structurally comprises a two-dimensional structure layer; according to the structure of the sulfide electrolyte, a plurality of two-dimensional structures are stacked to form a two-dimensional structure layer, so that the effective contact area of an interface can be remarkably improved, the actual area of ion transmission is increased, the interface resistance is remarkably reduced, meanwhile, an ion transmission path is optimized, and the ion conductivity and stability of the sulfide electrolyte are improved; and the application performance of the sulfide electrolyte is improved.

Description

Technical Field

[0001] This application relates to the field of electrolyte materials technology, and in particular to a sulfide electrolyte with a two-dimensional structure and its preparation method. Background Technology

[0002] All-solid-state batteries have attracted widespread attention due to their potential for high safety, high energy density, and long cycle life. Among various solid electrolytes, sulfide electrolytes have become one of the key materials for realizing high-performance all-solid-state batteries due to their excellent overall performance.

[0003] The ion transport behavior of sulfide electrolytes mainly depends on the transport paths at grain boundaries and particle surfaces. Therefore, particle size has a crucial impact on ion migration efficiency and interfacial contact quality. Excessively large particle sizes increase the internal porosity of the electrolyte, reducing the effective contact area and leading to a longer ion transport path. Conversely, excessively small particle sizes can easily cause an increase in interfacial resistance between particles, and may even induce the formation of a high-resistivity phase. Therefore, controlling the particle size and specific surface area of ​​sulfide electrolytes is key to ensuring their performance as an ion transport medium in all-solid-state batteries.

[0004] To improve the overall performance of sulfide electrolytes, existing technologies generally employ sand milling to refine the sulfide electrolytes. However, since non-polar solvents are typically used in the sand milling process, it is difficult to guide the directional growth of particles through solvation, which makes the electrolyte particles prone to forming irregular morphologies, affecting the ionic conductivity and other properties of the sulfide electrolyte. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this application provides a sulfide electrolyte with a two-dimensional structure and a method for its preparation. The specific technical solution is as follows: On the one hand, this application provides a sulfide electrolyte with a two-dimensional structure, wherein the chemical formula of the sulfide electrolyte is Li. 6-x PS 5-x Cl 1+x Where 0≤x≤0.99, the structure of the sulfide electrolyte includes a two-dimensional structural layer.

[0006] In a possible implementation, the thickness of a single two-dimensional structure of the sulfide electrolyte ranges from 100 to 500 nm.

[0007] On the other hand, this application provides a method for preparing a sulfide electrolyte as described in any of the above embodiments, the method comprising: S1: Obtain a first mixed slurry, the first mixed slurry comprising a first solvent and crude sulfide electrolyte, wherein the first solvent is a poor solvent for the sulfide electrolyte; S2: The first mixed slurry is subjected to a grinding process to obtain a pre-grinded slurry; S3: The pre-ground slurry is mixed with a second solvent to obtain a second mixed slurry, wherein the second solvent is a good solvent capable of solubilizing the sulfide electrolyte; S4: The second mixed slurry is subjected to secondary grinding to form a two-dimensional structure of the sulfide electrolyte, and then dried to obtain a sulfide electrolyte with a two-dimensional structure.

[0008] In a possible implementation, the dielectric constant of the first solvent is lower than that of the second solvent.

[0009] In a possible implementation, the method satisfies at least one of the following characteristics: The first solvent includes at least one of benzene, toluene, xylene, n-hexane, cyclohexane, isobutyl isobutyrate, n-heptane, octane, carbon tetrachloride, isooctane, and petroleum ether; The second solvent includes at least one of methanol, ethanol, isopropanol, butanol, hexanol, benzyl alcohol, ethylene glycol, N,N-dimethylformamide, acetylacetone, acetone, pyridine, ethyl acetate, acetonitrile, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2,-tetrachloroethane, and diethyl ether.

[0010] In a possible implementation, the method satisfies at least one of the following characteristics: The mass ratio between the crude sulfide electrolyte and the first solvent is 1:(1~20); The mass ratio between the crude sulfide electrolyte and the second solvent is 1:(1~20).

[0011] In a possible implementation, the grinding speed in the first grinding process of step S2 is greater than or equal to the grinding speed in the second grinding process of step S4.

[0012] In a possible implementation, the method satisfies at least one of the following characteristics: The grinding speed range in the first grinding process of step S2 is 800~2000 rpm / min; The grinding speed range in the secondary grinding process of step S4 is 100~1000 rpm / min.

[0013] In a possible implementation, the method satisfies at least one of the following characteristics: The grinding time in the first grinding process of step S2 is 15min-45min; The grinding time in the secondary grinding process of step S4 is 20 min to 60 min; The sulfide electrolyte in the pre-ground slurry has a particle size range of 0.7µm-1.8µm; The sulfide electrolyte in the slurry after the secondary grinding treatment has a particle size range of 0.7µm-1.2µm.

[0014] In a possible implementation, the method satisfies at least one of the following characteristics: The drying temperature in step S4 is 80~300℃; The drying time in step S4 is 10-15 hours.

[0015] Based on the above technical solution, this application has the following beneficial effects: This application discloses a two-dimensional sulfide electrolyte and its preparation method, wherein the general chemical formula of the sulfide electrolyte is Li. 6-x PS 5-x Cl 1+x The sulfide electrolyte has a structure comprising a two-dimensional structural layer, where 0 ≤ x ≤ 0.99. The preparation method described in this application can solubilize the sulfide electrolyte, guiding its structure to transform into a two-dimensional structural layer composed of multiple stacked two-dimensional structures. This significantly increases the effective contact area at the interface and the actual area for ion transport, while also significantly reducing the interfacial resistance. Furthermore, it optimizes the ion transport path, improving the ionic conductivity and stability of the sulfide electrolyte, thereby enhancing its overall performance. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0017] Figure 1 This is a SEM image of the sulfide electrolyte obtained in Example 1.

[0018] Figure 2 The image shows the XRD pattern of the sulfide electrolyte obtained in Example 1.

[0019] Figure 3 This is a particle size distribution diagram of the sulfide electrolyte obtained in Example 1.

[0020] Figure 4 The Nyquist plot is for the sulfide electrolyte obtained in Example 1. 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] For the terms defined below, unless a different definition is given elsewhere in the claims or this specification, these definitions shall apply. All numerical values, whether explicitly indicated or not, 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 ​​included 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 orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0024] The following describes a sulfide electrolyte with a two-dimensional structure provided in the embodiments of this application. The general chemical formula of the sulfide electrolyte is Li. 6-x PS 5-x Cl 1+x For 0 ≤ x ≤ 0.99, the structure of the sulfide electrolyte includes a two-dimensional structural layer. Understandably, the upper limit of x can be, but is not limited to, 0.99, 0.98, 0.97, etc., and the lower limit of x can be, but is not limited to, 0, 0.01, 0.02, etc.; understandably, x can also be any point value within the above range, which will not be enumerated here.

[0025] Specifically, the two-dimensional structural layer is composed of several stacked sheet-like structures. This structure of the sulfide electrolyte, composed of multiple stacked sheet-like structures, significantly increases the effective contact area at the interface, increases the actual area for ion transport, significantly reduces interfacial resistance, optimizes the ion transport path, and improves the ionic conductivity and stability of the sulfide electrolyte, thereby enhancing its overall performance.

[0026] In some embodiments, 0 ≤ x ≤ 0.9. Understandably, the upper limit of x can be, but is not limited to, 0.9, 0.89, 0.88, etc., and the lower limit of x can be, but is not limited to, 0, 0.01, 0.02, etc.; it is also understood that x can be any point value within the above range, which will not be enumerated here.

[0027] In some embodiments, 0 ≤ x ≤ 0.6. Understandably, the upper limit of x can be, but is not limited to, 0.6, 0.59, 0.58, etc., and the lower limit of x can be, but is not limited to, 0, 0.01, 0.02, etc.; understandably, x can also be any value within the above range, which will not be enumerated here. Specifically, x can take the value of 0, 0.3, or 0.6. When x = 0.6, the chemical formula of the resulting sulfide electrolyte is Li. 5.4 PS 4.4 Cl 1.6 When x = 0.3, the general chemical formula of the resulting sulfide electrolyte is Li. 5.7 PS 4.7 Cl 1.3 When x=0, the chemical formula of the resulting sulfide electrolyte is Li6PS5Cl.

[0028] In some embodiments, the thickness of a single two-dimensional structure of the sulfide electrolyte ranges from 100 to 500 nm. Understandably, the thickness can be any value within this range, and is not enumerated here. In this embodiment, the thickness of a single two-dimensional structure of the sulfide is that of a single sulfide sheet, ranging from 100 to 500 nm. By limiting the thickness range, the path of lithium-ion diffusion across layers can be greatly shortened, resistance can be significantly reduced, and the ionic conductivity of the electrolyte can be improved, thereby improving the rate performance of the sulfide electrolyte in batteries. Preferably, the thickness of a single two-dimensional structure of the sulfide electrolyte ranges from 100 to 300 nm.

[0029] On the other hand, this embodiment also provides a method for preparing sulfide electrolytes as described in any of the above embodiments, the preparation method comprising: S1: Obtain a first mixed slurry, the first mixed slurry including a first solvent and crude sulfide electrolyte, the first solvent being a poor solvent for the sulfide electrolyte; Specifically, the general chemical formula of sulfide electrolytes is Li 6-x PS 5-x Cl 1+x 0 ≤ x ≤ 0.99. Understandably, the upper limit of x can be, but is not limited to, 0.99, 0.98, 0.97, etc., and the lower limit of x can be, but is not limited to, 0, 0.01, 0.02, etc.; understandably, x can also be any point value within the above range, which will not be enumerated here.

[0030] In some embodiments, 0 ≤ x ≤ 0.6. It is understood that the upper limit of x can be, but is not limited to, 0.6, 0.59, 0.58, etc., and the lower limit of x can be, but is not limited to, 0, 0.01, 0.02, etc.; it is also understood that x can be any value within the above range, which will not be enumerated here. Specifically, x can take the value of 0, 0.3, or 0.6. When x = 0, the chemical formula of the obtained sulfide electrolyte is Li6PS5Cl; when x = 0.3, the chemical formula of the obtained sulfide electrolyte is Li... 5.7 PS 4.7 Cl 1.3 When x = 0.6, the general chemical formula of the resulting sulfide electrolyte is Li. 5.4 PS 4.4 Cl 1.6 .

[0031] In some embodiments, obtaining the first mixed slurry includes mixing a sulfide electrolyte with a first solvent to obtain the first mixed slurry. Specifically, the mixing is carried out under stirring conditions.

[0032] In some embodiments, the first solvent includes at least one selected from benzene, toluene, xylene, n-hexane, cyclohexane, isobutyl isobutyrate, n-heptane, octane, carbon tetrachloride, isooctane, and petroleum ether. By using a low-polarity or non-polar solvent as the first solvent, during a high-speed single-pass milling process, the first solvent does not react with the sulfide electrolyte, thereby rapidly reducing the particle size of the material without damaging the internal structure of the electrolyte crystals. Preferably, the first solvent includes at least one selected from xylene, hexane, isobutyl isobutyrate, n-hexane, n-heptane, and octane. More preferably, the first solvent includes at least one selected from xylene, isobutyl isobutyrate, and n-heptane.

[0033] S2: The first mixed slurry is subjected to a grinding process to obtain a pre-ground slurry; Specifically, the first grinding process includes: pouring the first mixed slurry into a sand mill for a first grinding.

[0034] In some embodiments, the mass ratio between the crude sulfide electrolyte and the first solvent is 1:(1~20). Too much or too little first solvent will result in poor grinding and mixing. A suitable amount of first solvent can appropriately separate the electrolyte particles, allowing for a uniform distribution of mechanical energy, thereby generating fine and uniform sulfide electrolytes.

[0035] In some embodiments, the grinding speed range in the first grinding process of step S2 is 800~2000 rpm / min. The upper limit of the grinding speed can be, but is not limited to, 2000 rpm / min, 1999 rpm / min, 1998 rpm / min, etc., and the lower limit of the grinding speed can be, but is not limited to, 800 rpm / min, 801 rpm / min, 802 rpm / min, etc.; it is understood that the grinding speed can also be any value within the above range, which will not be enumerated here. By using a higher grinding speed in the first grinding process, the target particle size can be achieved quickly, significantly improving production efficiency.

[0036] In some embodiments, the grinding temperature in the first grinding process of step S2 is ≤50°C. It is understood that the grinding temperature can also be any value within the above range, and will not be enumerated here. During grinding, the grinding temperature is difficult to determine. The grinding temperature in the first grinding process of this invention only needs to be below 50°C. This application does not specifically limit the specific range of the grinding temperature in the first grinding process.

[0037] In some embodiments, the grinding time in step S2 is 15 min to 45 min. The upper limit of the grinding time can be, but is not limited to, 45 min, 44 min, 43 min, etc., and the lower limit of the grinding time can be, but is not limited to, 15 min, 16 min, 17 min, etc.; understandably, the grinding time can also be any value within the above range, which will not be enumerated here. By limiting the above grinding temperature and grinding time, an appropriate grinding temperature can avoid excessively high temperatures leading to electrolyte thermal decomposition or side reactions with trace amounts of moisture / oxygen, ensuring the purity of the product. At the same time, an appropriate grinding time can ensure that the slurry is thoroughly ground, improving grinding efficiency.

[0038] In some embodiments, the particle size range of the sulfide electrolyte in the slurry after preliminary grinding is 0.7µm-1.8µm. It is understood that the upper limit of the particle size can be, but is not limited to, 1.8µm, 1.7µm, 1.6µm, etc., and the lower limit of the particle size can be, but is not limited to, 0.7µm, 0.6µm, 0.5µm, etc.; it is also understood that the particle size can be any value within the above range, which will not be enumerated here. By limiting this particle size range, the particle size of the sulfide electrolyte after the first grinding is ensured to be small, thereby ensuring that the crystal growth process during the subsequent second grinding is more controllable and uniform, and thus maximizing the overall ionic conductivity of the electrolyte.

[0039] S3: Mix the pre-ground slurry with the second solvent to obtain a second mixed slurry. The second solvent is a good solvent that can solubilize sulfide electrolytes. In some embodiments, the dielectric constant of the first solvent is lower than that of the second solvent. During the secondary milling process, introducing a second solvent with a high dielectric constant (such as a polar solvent containing ester or ketone groups) can optimize the microstructure of the sulfide electrolyte through its strong solvation effect. The mechanism is as follows: the strongly polar functional groups in the solvent molecules (such as ketone groups -CO-) can interact with the PS4 groups on the surface of the electrolyte particles. 3- Tetrahedral units generate dipole interactions, forming a stable solvation layer. This layer not only weakens the attraction between particles, improving dispersibility and preventing agglomeration during subsequent drying, but more importantly, under the gentle shear force provided by low-speed grinding, this surface interaction can directionally promote the exposure of (001) crystal planes, causing the electrolyte to tend towards a layered structure. The resulting lamellar two-dimensional structure can provide more efficient lithium-ion transport channels, thereby improving ionic conductivity. At the same time, the lower grinding speed avoids excessive mechanical force damaging the crystal bulk structure, ensuring the structural integrity of the electrolyte.

[0040] In some embodiments, the second solvent includes at least one selected from methanol, ethanol, isopropanol, butanol, hexanol, benzyl alcohol, ethylene glycol, N,N-dimethylformamide, acetylacetone, acetone, pyridine, ethyl acetate, acetonitrile, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, and diethyl ether. The second solvents in this embodiment are all highly polar, capable of solubilizing the sulfide electrolyte, thereby promoting the formation of a two-dimensional structural layer of the sulfide electrolyte. Furthermore, secondary milling using the aforementioned second solvent can effectively promote crystal growth, reduce lattice defects, and "clean" amorphous or impurity phases at grain boundaries, thus significantly reducing grain boundary resistance and improving the ionic conductivity of the electrolyte. Preferably, the second solvent includes at least one selected from ethyl acetate, chloroform, and isopropanol.

[0041] In some embodiments, the mass ratio between the crude sulfide electrolyte and the second solvent is 1:(1~20). When the amount of the second solvent is large, the high solubility may easily lead to larger grain size, while a small amount of the second solvent may lead to insufficient crystallinity, more grain boundary defects, and thus greater resistance to ion migration. A suitable mass ratio can form an electrolyte with smaller size but acceptable crystallinity, thereby improving the overall performance of the sulfide electrolyte.

[0042] S4: The second mixed slurry is subjected to secondary grinding to form a two-dimensional structure of sulfide electrolyte, and then dried to obtain a sulfide electrolyte with a two-dimensional structure.

[0043] In some embodiments, the grinding speed in the first grinding process of step S2 is greater than or equal to the grinding speed in the second grinding process of step S4. The higher grinding speed in the first grinding process, and the absence of reaction between the first solvent and the sulfide electrolyte, rapidly reduces the electrolyte particle size without damaging the internal structure of the sulfide electrolyte crystals. In contrast, the lower grinding speed in the second grinding process, and the presence of a second solvent that solubilizes the sulfide electrolyte, allows for the directional exposure of more (001) crystal planes, thereby forming a two-dimensional structural layer. By limiting the grinding speed, not only is production efficiency improved, but the directional transformation of the sulfide electrolyte structure is also promoted, thus enhancing its overall performance.

[0044] In some embodiments, the grinding speed in the secondary grinding process of step S4 ranges from 100 to 1000 rpm / min. The upper limit of the grinding speed can be, but is not limited to, 1000 rpm / min, 999 rpm / min, 998 rpm / min, etc., and the lower limit can be, but is not limited to, 100 rpm / min, 101 rpm / min, 102 rpm / min, etc.; understandably, the grinding speed can also be any value within the above range, which will not be enumerated here. By limiting this grinding speed, it helps the sulfide electrolyte form a more regular two-dimensional structure, reduces amorphous residues and defects at grain boundaries, and improves ionic conductivity.

[0045] In some embodiments, the grinding temperature in the secondary grinding process of step S4 is ≤50°C. It is understood that the grinding temperature can also be any value within the above range, and will not be enumerated here. During grinding, the grinding temperature is difficult to determine. The grinding temperature in the secondary grinding process of this invention only needs to be below 50°C. This application does not specifically limit the specific range of the grinding temperature in the secondary grinding process.

[0046] In some embodiments, the grinding time in the secondary grinding process of step S4 is 20 min to 60 min. The upper limit of the grinding time can be, but is not limited to, 60 min, 59 min, 58 min, etc., and the lower limit of the grinding time can be, but is not limited to, 20 min, 21 min, 22 min, etc.; it is understood that the grinding time can also be any value within the above range, which will not be enumerated here. The selective adsorption and solvation of polar solvent molecules of the second solvent on specific crystal planes is the key to the formation of layered structures. By limiting the above grinding temperature and grinding time, it is possible to promote the growth of particles along the (001) crystal plane through directional adhesion, thereby forming a layered structure with better crystallinity and completeness, while ensuring the structural integrity of the material.

[0047] In some embodiments, the particle size range of the sulfide electrolyte in the slurry after secondary grinding is 0.7µm to 1.2µm. Understandably, this particle size can also be any value within the above range, and will not be enumerated here. Too small a particle size may lead to an increase in grain boundary volume fraction, i.e., higher interfacial resistance, resulting in a decrease in the ionic conductivity of the material. Conversely, too large a particle size results in a smaller specific surface area, lower effective contact area, and a longer ion transport path. By limiting the above particle size range, the internal porosity of the electrolyte is reduced, the actual contact area for ion transport is increased, and the impedance is reduced.

[0048] In some embodiments, the method further includes centrifuging the slurry after secondary grinding before performing the drying step.

[0049] In some embodiments, the drying conditions in step S4 are vacuum.

[0050] In some embodiments, the drying temperature in step S4 is 80~300℃. The upper limit of the drying temperature can be, but is not limited to, 300℃, 290℃, 280℃, etc., and the lower limit of the drying temperature can be, but is not limited to, 80℃, 81℃, 82℃, etc.; it is understood that the drying temperature can also be any point value within the above range, which will not be enumerated here. Preferably, the drying temperature in step S4 is 80~200℃.

[0051] In some embodiments, the drying time in step S4 is 10-15 hours. The upper limit of the drying time can be, but is not limited to, 15 hours, 14.9 hours, 14.8 hours, etc., and the lower limit can be, but is not limited to, 10 hours, 10.1 hours, 10.2 hours, etc.; understandably, the drying time can also be any value within the above range, which will not be enumerated here. By limiting the above drying temperature and time, solvents that may be embedded in grain boundaries, lattice defects, or even the gaps in two-dimensional structural layers can be removed, avoiding solvent residue that could block ion migration channels. It also avoids excessively high drying temperatures that could lead to electrolyte decomposition or oxidation. Furthermore, an appropriate temperature can repair crystal defects caused by mechanical grinding, improve crystallinity, and reduce grain boundary resistance.

[0052] In the prior art, sand milling is generally used to refine the sulfide electrolyte in order to improve its overall performance. However, since non-polar solvents are generally used in the sand milling process, it is difficult to guide the directional growth of particles through solvation, which makes the electrolyte particles prone to irregular morphology, thus affecting the overall performance of the sulfide electrolyte. In order to solve this problem, this application performs a second sand milling on the sulfide electrolyte. In the first sand milling, the sulfide electrolyte particle size is relatively large. Therefore, a first solvent with a low dielectric constant is used during grinding, which can quickly reduce the particle size of the material without destroying the internal structure of the sulfide electrolyte crystal. In the second sand milling, a second solvent with a high dielectric constant is added, which can solvate the sulfide electrolyte. At the same time, the grinding speed is reduced, which exposes more (001) crystal planes of the sulfide electrolyte, and then tends to evolve into a layered structure, forming a layered structure composed of stacked plate-like structures. Furthermore, the solute molecules are solvated during the second grinding, which increases the dispersion effect and avoids agglomeration in the subsequent drying process.

[0053] The following describes specific embodiments of this application in conjunction with the above-described method for preparing sulfide electrolytes with two-dimensional structures. The following embodiments further describe the technical solutions of this application. These embodiments 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 embodiments are commercially available or synthesized using conventional methods and can be used directly without further processing. Similarly, the instruments and apparatus used in the embodiments are commercially available.

[0054] Example 1 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The general chemical formula of the sulfide electrolyte is: Li 5.4 PS 4.4 Cl 1.6 The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 200g of xylene and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1500 rpm / min and the sand milling time is 30 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.2µm. S300: Add 50g of ethyl acetate to the sand mill to mix the initially ground slurry with ethyl acetate and then perform a second sand milling at a speed of 500rpm / min for 30min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.7µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 100℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0055] Example 2 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.4 PS 4.4 Cl 1.6 The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 100g of xylene and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1500 rpm / min and the sand milling time is 20 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.5µm. S300: Add 50g of chloroform to the sand mill to mix the pre-ground slurry with chloroform and then perform a second sand milling at a speed of 800rpm / min for 20min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.9µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 100℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0056] Example 3 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.4 PS 4.4 Cl 1.6 The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 200g of isobutyl isobutyrate and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 2000 rpm / min and the sand milling time is 15 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 0.8µm. S300: Add 100g of ethyl acetate to the sand mill to mix the initially ground slurry with ethyl acetate and then perform a second sand milling at a speed of 500rpm / min for 30min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.7µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 80℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0057] Example 4 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.4 PS 4.4 Cl 1.6 The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 100g of n-heptane and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1500 rpm / min and the sand milling time is 30 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.2µm. S300: Add 50g of ethyl acetate to the sand mill to mix the pre-ground slurry with ethyl acetate and then perform a second sand milling at a speed of 500rpm / min for 30min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.9µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 80℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0058] Example 5 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.4 PS 4.4 Cl 1.6 The preparation method includes: S100: Mix 25g of crude sulfide electrolyte and 500g of isobutyl isobutyrate and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1000 rpm / min and the sand milling time is 45 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.3µm. S300: Add 50g of isopropanol to the sand mill to mix the pre-ground slurry with isopropanol and then perform a second sand milling at a speed of 500rpm / min for 45min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 1.0µm. Then centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 150℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0059] Example 6 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.4 PS 4.4 Cl1.6 The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 200g of isobutyl isobutyrate and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 800 rpm / min and the sand milling time is 45 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.6µm. S300: Add 100g of chloroform to the sand mill to mix the pre-ground slurry with chloroform and then perform a second sand milling at a speed of 800rpm / min for 45min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 1.1µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 100℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0060] Example 7 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.7 PS 4.7 Cl 1.3 The preparation method includes: S100: Mix 25g of crude sulfide electrolyte and 200g of xylene and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 800 rpm / min and the sand milling time is 45 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.2µm. S300: Add 200g of isopropanol to the sand mill to mix the initially ground slurry with isopropanol and then perform a second sand milling at a speed of 500rpm / min for 45min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.9µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 200℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0061] Example 8 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.7 PS 4.7 Cl 1.3 The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 250g of n-heptane and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1500 rpm / min and the sand milling time is 30 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.3µm. S300: Add 50g of ethyl acetate to the sand mill to mix the initially ground slurry with ethyl acetate and then perform a second sand milling at a speed of 500rpm / min for 45min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 1.0µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 100℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0062] Example 9 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.7 PS 4.7 Cl 1.3 The preparation method includes: S100: Mix 25g of crude sulfide electrolyte and 500g of isobutyl isobutyrate and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 800 rpm / min and the sand milling time is 45 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.8µm. S300: Add 25g of chloroform to the sand mill to mix the pre-ground slurry with chloroform and then perform a second sand milling at a speed of 500rpm / min for 60min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 1.2µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 150℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0063] Example 10 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is: Li 5.7 PS 4.7 Cl 1.3 The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 200g of isobutyl isobutyrate and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1500 rpm / min and the sand milling time is 30 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.3µm. S300: Add 50g of isopropanol to the sand mill to mix the initially ground slurry with isopropanol and then perform a second sand milling at a speed of 100rpm / min for 60min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 1.0µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 100℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0064] Example 11 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is Li6PS5Cl. The preparation method includes: S100: Mix 25g of crude sulfide electrolyte and 200g of xylene and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 2000 rpm / min and the sand milling time is 20 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 0.9µm. S300: Add 25g of ethyl acetate to the sand mill to mix the initially ground slurry with ethyl acetate and then perform a second sand milling at a speed of 100rpm / min for 30min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.8µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 200℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0065] Example 12 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is Li6PS5Cl. The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 250g of isobutyl isobutyrate and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1500 rpm / min and the sand milling time is 45 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 0.7µm. S300: Add 100g of isopropanol to the sand mill to mix the initially ground slurry with isopropanol and then perform a second sand milling. Sand mill for 30 minutes at a speed of 500 rpm / min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.7µm. Then centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 100℃ for 12 hours to obtain a sulfide electrolyte with a two-dimensional structure.

[0066] Example 13 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is Li6PS5Cl. The preparation method includes: S100: Mix 25g of crude sulfide electrolyte and 200g of n-heptane and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1500 rpm / min and the sand milling time is 30 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.1µm. S300: Add 500g of chloroform to the sand mill to mix the pre-ground slurry with chloroform and then perform a second sand milling at a speed of 500rpm / min for 30min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.8µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 80℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0067] Example 14 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is Li6PS5Cl. The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 250g of xylene and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1500 rpm / min and the sand milling time is 15 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.5µm. S300: Add 50g of isopropanol to the sand mill to mix the initially ground slurry with isopropanol and then perform a second sand milling at a speed of 800 rpm / min for 45 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 0.8µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 100℃ for 12 h to obtain a sulfide electrolyte with a two-dimensional structure.

[0068] Example 15 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The chemical formula of the sulfide electrolyte is Li6PS5Cl. The preparation method includes: S100: Mix 50g of crude sulfide electrolyte and 200g of n-heptane and stir evenly to obtain the first mixed slurry; S200: The first mixed slurry is put into a sand mill for one sand milling, wherein the sand milling speed is 1000 rpm / min and the sand milling time is 30 min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after preliminary grinding is 1.2µm. S300: Add 100g of isopropanol to the sand mill to mix the initially ground slurry with isopropanol and then perform a second sand milling at a speed of 800rpm / min for 30min. At this time, the particle size (D50) of the sulfide electrolyte in the slurry after the second sand milling is 1.0µm. Then, centrifuge the slurry after the second sand milling and dry it in a vacuum drying oven at 100℃ for 12h to obtain a sulfide electrolyte with a two-dimensional structure.

[0069] Example 16 This embodiment provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The similarities to those in Example 2 will not be repeated here. The difference lies in the chemical formula of the sulfide electrolyte: Li 5.1 PS 4.1 Cl 1.9 .

[0070] Comparative Example 1 This comparative example provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The similarities with Example 2 will not be repeated. The difference between this method and Example 2 is as follows: S100: 50g of crude sulfide electrolyte and 100g of chloroform are mixed and stirred evenly to obtain a first mixed slurry.

[0071] Comparative Example 2 This comparative example provides a method for preparing a sulfide electrolyte with a two-dimensional structure. The similarities with Example 2 will not be repeated here. The difference between this method and Example 2 is that chloroform is not added in step S300.

[0072] The above embodiments and comparative examples adopted the following test methods: 1. SEM Test: The morphology of the sulfide electrolyte obtained in Example 1 was observed using a scanning electron microscope (ZEISS Sigma 300). The test results are shown in the attached figure. Figure 1As shown, the sulfide electrolyte prepared in Example 1 has a layered structure formed by stacking sheets, with the thickness of a single sheet ranging from 100 to 300 nm.

[0073] 2. XRD Testing: The relevant X-ray diffraction data of the sulfide electrolyte obtained in Example 1 were measured using an X-ray diffractometer. The conditions were set as follows: accelerating voltage 40 kV, Cu target, incident light wavelength between 0.1 and 1.54 nm. The test results are as follows: Figure 2 As shown in the figure, the XRD peak positions and intensities perfectly match those of Li. 5.4 PS 4.4 Cl 1.6 Standard card (as attached) Figure 2 As shown in the figure, this indicates that the electrolyte is a pure phase substance without impurities.

[0074] 3. Particle size testing: The sulfide electrolyte prepared in the examples was dissolved in ethyl acetate to obtain a dispersion with a concentration of 10 mg / mL. The particle size was measured using a MicroDandong Baite BT-200 laser particle size analyzer. The test results are shown in the attached figure. Figure 3 As shown, the sulfide electrolyte prepared in Example 1 has a particle size range of 0.1~20μm and a narrow particle size distribution.

[0075] 4. Ionic Conductivity and Nyquist Plot Tests: Under an argon atmosphere, the sulfide electrolyte powder prepared in the examples was filled into a pressure molding die. Inside the die, upper and lower punches applied a pressure of 500 MPa to the solid electrolyte powder. Maintaining the applied pressure, the upper and lower parts of the punches were connected to a potentiostat equipped with a frequency response analyzer. The ionic conductivity and Nyquist plot of the solid electrolyte material were measured using electrochemical impedance spectroscopy. The real value of the impedance at the measurement point where the absolute value of the complex impedance phase is the smallest was taken as the resistance of the solid electrolyte material for ion conduction. The test results are attached. Figure 4 As shown in Table 1, from the appendix Figure 4 It can be seen that the diameter of the ring is small, indicating that the charge transfer resistance of the electrolyte material prepared in Example 1 is small.

[0076] 5. Table 1 below summarizes the test data from the examples and comparative examples: Table 1

[0077] Referring to Table 1 and the accompanying drawings, and in conjunction with Examples 1 and 2, it can be seen that, compared with Example 2, the mass ratio between the coarse sulfide electrolyte powder and the first solvent in Example 1 is lower, resulting in lower ionic conductivity. This may be because when the amount of the first solvent is large, the uniformity of the sulfide electrolyte decreases, leading to irregular material structure during subsequent secondary grinding, which in turn leads to a decrease in ionic conductivity. It may also be because the particle size in the first sand milling of Example 1 is smaller than that in the first sand milling of Example 2, which may lead to a decrease in ionic conductivity.

[0078] As can be seen from Examples 3, 5 and 6, the first solvent is ethyl acetate, but the types of second solvents are all different, which will significantly affect the ionic conductivity of the sulfide electrolyte. The main reason may be that the stronger the polarity of the second solvent and the lower the rotation speed during the second grinding, the more (001) crystal faces can be exposed, so that more layered structures can be formed to improve the ionic conductivity of the sulfide electrolyte. The second solvent in Example 5 has the strongest polarity, so its ionic conductivity is higher than that in Examples 3 and 5. Based on Examples 3 and 4, it can be seen that the ionic conductivity in Example 3 is significantly lower than that in Example 4. This may be because the polarity of the first solvent in Example 3 is higher than that in Example 4. In one grinding process, the first solvent can solubilize the sulfide electrolyte in a small amount, thereby destroying the internal structure of the electrolyte crystal and resulting in a decrease in ionic conductivity. As can be seen from Examples 7-8, the types of the first and second solvents slightly affect the ionic conductivity of the material.

[0079] Based on Examples 9-10, it can be seen that the ionic conductivity of Example 10 is slightly lower than that of Example 9. This may be because the grinding speed in the secondary grinding process in Example 10 is relatively low, which may result in the solvent not being able to fully contact the material, and the layered structure of some materials not being fully transformed, thus leading to a decrease in ionic conductivity.

[0080] As can be seen from Examples 11-15, the ionic conductivity of Example 13 is slightly lower, possibly because the second solvent in Example 13 has a lower polarity, which prevents it from promoting more (001) crystal plane exposure and thus reduces the ionic conductivity of the material.

[0081] Based on Example 2 and Comparative Example 1, it can be seen that the ionic conductivity of Comparative Example 1 is lower than that of Example 2. This may be because chloroform is highly polar and reacts with sulfide electrolytes, thereby destroying its internal crystal structure and leading to a decrease in ionic conductivity.

[0082] As can be seen from Example 2 and Comparative Example 2, no chloroform was added during the second grinding in Comparative Example 2, which resulted in a significant reduction in ionic conductivity.

[0083] The foregoing description has fully disclosed the specific embodiments of this application. It should be noted that any modifications made by those skilled in the art to the specific embodiments of this application do not depart from the scope of the claims. Accordingly, the scope of the claims of this application is not limited to the foregoing specific embodiments.

Claims

1. A sulfide electrolyte with a two-dimensional structure, characterized in that, The general chemical formula of the sulfide electrolyte is Li 6-x PS 5-x Cl 1+x Where 0≤x≤0.99, the structure of the sulfide electrolyte includes a two-dimensional structural layer.

2. The sulfide electrolyte according to claim 1, characterized in that, The thickness of a single two-dimensional structure of the sulfide electrolyte ranges from 100 to 500 nm.

3. A method for preparing a sulfide electrolyte as described in any one of claims 1-2, characterized in that, The preparation method includes: S1: Obtain a first mixed slurry, the first mixed slurry comprising a first solvent and crude sulfide electrolyte, wherein the first solvent is a poor solvent for the sulfide electrolyte; S2: The first mixed slurry is subjected to a grinding process to obtain a pre-grinded slurry; S3: The pre-ground slurry is mixed with a second solvent to obtain a second mixed slurry, wherein the second solvent is a good solvent capable of solubilizing the sulfide electrolyte; S4: The second mixed slurry is subjected to secondary grinding to form a two-dimensional structure of the sulfide electrolyte, and then dried to obtain a sulfide electrolyte with a two-dimensional structure.

4. The preparation method according to claim 1, characterized in that, The dielectric constant of the first solvent is lower than that of the second solvent.

5. The preparation method according to claim 1, characterized in that, The method satisfies at least one of the following characteristics: The first solvent includes at least one of benzene, toluene, xylene, n-hexane, cyclohexane, isobutyl isobutyrate, n-heptane, octane, carbon tetrachloride, isooctane, and petroleum ether; The second solvent includes at least one of methanol, ethanol, isopropanol, butanol, hexanol, benzyl alcohol, ethylene glycol, N,N-dimethylformamide, acetylacetone, acetone, pyridine, ethyl acetate, acetonitrile, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2,-tetrachloroethane, and diethyl ether.

6. The preparation method according to claim 1, characterized in that, The method satisfies at least one of the following characteristics: The mass ratio between the crude sulfide electrolyte and the first solvent is 1:(1~20); The mass ratio between the crude sulfide electrolyte and the second solvent is 1:(1~20).

7. The preparation method according to claim 1, characterized in that, The grinding speed in the first grinding process of step S2 is greater than or equal to the grinding speed in the second grinding process of step S4.

8. The preparation method according to any one of claims 3-7, characterized in that, The method satisfies at least one of the following characteristics: The grinding speed range in the first grinding process of step S2 is 800~2000 rpm / min; The grinding speed range in the secondary grinding process of step S4 is 100~1000 rpm / min.

9. The preparation method according to any one of claims 3-7, characterized in that, The method satisfies at least one of the following characteristics: The grinding time in the first grinding process of step S2 is 15 min to 45 min; The grinding time in the secondary grinding process of step S4 is 20 min to 60 min; The sulfide electrolyte in the pre-ground slurry has a particle size range of 0.7µm to 1.8µm; The sulfide electrolyte in the slurry after the secondary grinding treatment has a particle size range of 0.7µm to 1.2µm.

10. The preparation method according to any one of claims 3-7, characterized in that, The method satisfies at least one of the following characteristics: The drying temperature in step S4 is 80~300℃; The drying time in step S4 is 10-15 hours.

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