Sulfide solid electrolyte, preparation method thereof and solid-state battery

Abstract

The invention discloses a sulfide solid-state electrolyte, a preparation method thereof and a solid-state battery, and the preparation method comprises the following steps: mixing a Prussian blue analogue and raw materials according to a stoichiometric ratio in an inert atmosphere to obtain solid-state electrolyte precursor powder; tabletting the solid electrolyte precursor powder in an inert atmosphere to obtain a solid electrolyte precursor sheet; calcining the solid electrolyte precursor sheet to obtain a solid electrolyte sheet; and crushing the solid electrolyte sheet to obtain the product sulfide solid electrolyte. By introducing the Prussian blue analogue, grain boundary defects in the sulfide solid electrolyte are effectively reduced, and the electrolyte powder with good ionic conductivity is obtained.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a sulfide solid electrolyte and its preparation method, and a solid battery. Background Technology

[0002] As the global energy structure shifts towards cleaner and lower-carbon energy, high-performance energy storage technology has become a research hotspot. Lithium-ion batteries are widely used in consumer electronics and electric vehicles, but their energy density is approaching its theoretical limit, and the use of organic liquid electrolytes poses safety hazards such as flammability and leakage. All-solid-state batteries, which use solid electrolytes instead of liquid electrolytes, are expected to fundamentally solve safety issues and can significantly improve energy density by matching high-capacity cathodes (such as lithium-rich manganese-based materials) with metallic lithium anodes, making them a strategic development direction for next-generation energy storage technology.

[0003] When preparing sulfide solid electrolytes using traditional sintering processes, sulfur volatilization leads to sulfur vacancies in the crystal lattice, forming ion transport barriers. This results in high grain boundary resistance, severely reducing lithium-ion transport efficiency and causing the macroscopic ionic conductivity of the bulk material to be far lower than the theoretical value; it also becomes a mechanical weak point, easily leading to electrolyte sheet cracking; and it induces lithium dendrite growth along grain boundaries, causing battery short circuits.

[0004] Therefore, there is an urgent need to develop a method for preparing sulfide solid electrolytes that can effectively eliminate grain boundary defects in order to obtain high density and high ion conductivity. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a sulfide solid electrolyte and its preparation method, as well as a solid-state battery, which can effectively eliminate grain boundary defects in the sulfide solid electrolyte and the prepared sulfide solid electrolyte has high ion conductivity.

[0006] To achieve one or more of the above objectives or other objectives, the first aspect of this application provides a method for preparing a sulfide solid electrolyte, the method comprising:

[0007] Prussian blue analogues and raw materials in stoichiometric proportions were mixed in an inert atmosphere to obtain solid electrolyte precursor powder.

[0008] The solid electrolyte precursor powder was compressed into tablets under an inert atmosphere to prepare solid electrolyte precursor tablets.

[0009] The solid electrolyte precursor sheet is calcined to obtain a solid electrolyte sheet.

[0010] The solid electrolyte sheet is pulverized to obtain the product sulfide solid electrolyte.

[0011] Furthermore, the raw materials include Li2S, P2S5 and LiCl, and the stoichiometric ratio of the raw materials is a molar ratio of Li2S:P2S5:LiCl of (1-3):(0.1-3):1.

[0012] Furthermore, the chemical formula of the Prussian blue analogue is A. x M[M'(CN)6] y ·zH2O, wherein M and M' are independently selected from one or more of Fe, Mn, Co, Ni, and Cu, and A is an alkali metal ion or a vacancy, wherein 0≤x≤2, 0≤y<1, and 0≤z≤5.

[0013] Furthermore, the mass ratio of the Prussian blue analogue to the total amount of the raw material is (0.01-5):1.

[0014] Further, the step of mixing the Prussian blue analogue and raw materials in stoichiometric proportions under an inert atmosphere to obtain a solid electrolyte precursor powder includes:

[0015] The Prussian blue analogue and the raw materials in stoichiometric proportions are mixed in an inert atmosphere and placed in a shearing machine. The mixture is sheared 1 to 10 times at a shearing power of 10,000 to 50,000 watts, with each shearing lasting 1 to 10 seconds, to obtain the solid electrolyte precursor powder.

[0016] Further, the step of compressing the solid electrolyte precursor powder under an inert atmosphere to prepare a solid electrolyte precursor tablet includes:

[0017] The solid electrolyte precursor powder is placed in a tablet press, which is placed in an inert atmosphere and pressed into tablets at a pressure of 20 MPa to 400 MPa for 1 to 10 minutes to obtain the solid electrolyte precursor tablets.

[0018] Further, the step of calcining the solid electrolyte precursor sheet to obtain the solid electrolyte sheet includes:

[0019] The solid electrolyte precursor sheet is placed in a sealed container, and the sealed container is placed in a calcination device for segmented calcination treatment. The segmented calcination process includes heating the calcination device to 100℃~300℃ at a heating rate of 0.5℃ / min~4℃ / min for 1h~3h; heating the calcination device to 300℃~400℃ at a heating rate of 0.5℃ / min~10℃ / min for 1h~3h; and heating the calcination device to 400℃~800℃ at a heating rate of 5℃ / min~10℃ / min for 1h~4h.

[0020] Further, the step of pulverizing the solid electrolyte sheet to obtain the product sulfide solid electrolyte includes:

[0021] The solid electrolyte sheet is placed in a shearing machine and sheared 1 to 5 times at a shearing power of 10,000 to 50,000 watts, with a single shearing time of 1 to 10 seconds, to obtain the product sulfide solid electrolyte.

[0022] The second aspect of this application provides a sulfide solid electrolyte, which is prepared by the above-described method for preparing sulfide solid electrolytes.

[0023] Furthermore, the chemical formula of the sulfide solid electrolyte includes Li6PS5Cl, Li 5.6 PS 4.6 Cl 1.4 Li 5.5 PS 4.5 Cl 1.5 and Li 5.4 PS 4.4 Cl 1.6 One or at least two of them.

[0024] A third aspect of this application provides a solid-state battery, comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, wherein the positive electrode layer and / or the solid electrolyte layer comprises a sulfide solid electrolyte prepared by the above-described method for preparing a sulfide solid electrolyte.

[0025] The sulfide solid electrolyte and its preparation method, as well as the solid battery provided in this application, involve adding a Prussian blue analogue during the preparation of the sulfide solid electrolyte. Utilizing its three-dimensional open framework structure, the sulfur species volatilized during calcination are efficiently adsorbed and temporarily immobilized through its internal nanopores and metal sites. Controllable desorption of sulfur species is achieved during subsequent heating, creating a high-sulfur-pressure microenvironment locally within the particles. This drives sulfur to diffuse directionally towards grain boundary defects and achieves in-situ filling, effectively reducing sulfur vacancy defects, optimizing the grain boundary structure, and suppressing the generation of grain boundary impurities. It exhibits excellent ion conductivity, helps suppress lithium dendrite growth, and enhances the safety of battery use. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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.

[0027] in:

[0028] Figure 1 Raman spectra of the electrolytes prepared in Case 1 and Comparative Example 2;

[0029] Figure 2 The ionic conductivity spectra of the sulfide solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-3 are shown.

[0030] Figure 3 The graph shows a comparison of the first charge-discharge performance of the solid-state batteries prepared in Examples 1-3 and Comparative Examples 1-3. Detailed Implementation

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0032] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0034] This application provides a method for preparing a sulfide solid electrolyte, the method comprising:

[0035] S1: Prussian blue analogue and raw materials in stoichiometric ratio are mixed in an inert atmosphere to obtain solid electrolyte precursor powder;

[0036] S2: The solid electrolyte precursor powder is compressed into tablets under an inert atmosphere to obtain solid electrolyte precursor tablets.

[0037] S3: The solid electrolyte precursor sheet is calcined to obtain a solid electrolyte sheet;

[0038] S4: The solid electrolyte sheet is crushed to obtain the product sulfide solid electrolyte.

[0039] In this embodiment, to address the issue of sulfur loss due to the vigorous volatilization of raw materials such as P2S5 during high-temperature calcination of sulfide electrolytes, which leads to the formation of numerous sulfur vacancy defects at grain boundaries and severely degrades ionic conductivity, a Prussian blue analogue is introduced as a sulfur capture and release agent during the reaction process. The Prussian blue analogue efficiently adsorbs and temporarily immobilizes volatilized sulfur through its internal nanopores and metal sites; it then desorbs during subsequent heating, creating a high-sulfur-pressure microenvironment locally within the precursor powder particles. This drives sulfur to diffuse directionally to grain boundary defects and achieves in-situ filling, thereby suppressing sulfur loss at its source, repairing sulfur vacancies at grain boundaries in situ, significantly reducing grain boundary impedance, and thus greatly improving the ionic conductivity and electrochemical performance of the electrolyte.

[0040] In step S1 above, the Prussian blue analogue and the raw material are uniformly mixed. Specifically, this can be done by pre-mixing in an inert atmosphere glove box before transferring the mixture to a sealed mixing device. The mixing device can be a shearing machine or other commonly used equipment in the field, which achieves uniform mixing of the raw material and the Prussian blue analogue through high-frequency shearing to obtain a uniform solid electrolyte precursor powder.

[0041] In step S2 above, mechanical pressure is applied to form a dense preform from the precursor powder, shortening the diffusion path of sulfur species during subsequent calcination. This facilitates the formation of a stable high-sulfur-pressure microenvironment locally from the sulfur released by the Prussian blue analogue. Specifically, a tablet press is used for tableting, and the tablet press can be placed in an inert atmosphere glove box. After tableting, the precursor tablets have a uniform thickness, preferably controlled between 0.5 mm and 5 mm, which is beneficial for tablet formation and reducing porosity.

[0042] In step S3 above, the sulfur adsorption-desorption behavior of Prussian blue analogues is controlled by programmed temperature increase, while the raw material reaction is driven to generate the target crystal phase, and grain boundary repair and impurity transformation are carried out, thereby forming a sulfide solid electrolyte with virtually no grain boundary defects.

[0043] In step S4 above, the block-shaped solid electrolyte sheet is processed into a powder product, which makes it easier to obtain electrolyte particles of uniform size for subsequent electrode assembly or electrolyte layer forming in solid-state batteries.

[0044] The preparation method of this embodiment adds a Prussian blue analogue during the preparation of the sulfide solid electrolyte, thereby suppressing sulfur loss and preventing the formation of sulfur vacancies to a certain extent during calcination. By temporarily adsorbing and fixing the volatilized sulfur and then desorbing it under high-temperature conditions, a local high-sulfur-pressure microenvironment is formed, driving sulfur to diffuse directionally towards grain boundary defects and achieving in-situ repair of these defects. The sulfide solid electrolyte obtained by this method essentially eliminates grain boundary defects, exhibits high material density, and possesses excellent ion conductivity, thus enabling further improvement of the electrochemical performance of solid-state batteries.

[0045] In some embodiments, the raw materials include Li₂S, P₂S₅, and LiCl, and the stoichiometric ratio of the raw materials is a molar ratio of Li₂S:P₂S₅:LiCl of (1-3):(0.1-3):1. The stoichiometric ratio of the raw materials is determined according to the molecular formula of the target product, which includes, for example, Li₆PS₅Cl, Li 5.6 PS 4.6 Cl 1.4 Li 5.5 PS 4.5 Cl 1.5 and Li 5.4 PS 4.4 Cl 1.6 One or at least two of them.

[0046] In some embodiments, the chemical formula of the Prussian blue analogue is A x M[M'(CN)6] y • zH₂O, wherein M and M' are independently selected from one or more of Fe, Mn, Co, Ni, and Cu, and A is an alkali metal ion or a vacancy, wherein 0 ≤ x ≤ 2, 0 ≤ y < 1, and 0 ≤ z ≤ 5. Preferably, the alkali metal ion is selected from Li. + Na + K + One or more of the following. The nanopores inside the Prussian blue analogue synergistically interact with the M and M' metal sites, enabling efficient adsorption and temporary fixation of sulfur generated from P2S5 volatilization during the low-temperature calcination stage; during subsequent heating, sulfur can be controllably desorbed, creating a high-sulfur-pressure microenvironment locally in the precursor particles, driving sulfur to diffuse directionally to grain boundary defects and achieve in-situ filling, thereby improving the grain boundary properties of the sulfide solid electrolyte and enhancing the ionic conductivity of the electrolyte.

[0047] In some embodiments, the mass ratio of the Prussian blue analogue to the total amount of the raw materials is (0.01-5):1. The mass ratio of the raw materials is the mass ratio of a mixture of Li₂S, P₂S₅, and LiCl. Exemplarily, this mass ratio can be selected as 0.01:1, 0.03:1, 0.05:1, 1:1, 1.5:1, 2:1, 3:1, 4:1, 5:1, etc. When the mass ratio is within this range, effective adsorption and desorption of sulfur can be achieved. If the ratio is below the lower limit of this range, the adsorption capacity of the Prussian blue analogue is insufficient, and effective sulfur control cannot be achieved, leading to unstable product quality; if the ratio is above the upper limit, although the adsorption capacity is excessive, new problems such as transition metal contamination, increased costs, and process complexity will be introduced. Preferably, the mass ratio of the Prussian blue analogue to the total amount of the raw materials is (0.01~1):1, which can ensure the sulfur control effect and grain boundary optimization while taking into account raw material costs and product purity. More preferably, the mass ratio of the Prussian blue analogue to the total amount of the raw material is (0.01~1):1.

[0048] In some embodiments, step S1, which involves mixing a Prussian blue analogue and raw materials in stoichiometric proportions under an inert atmosphere to obtain a solid electrolyte precursor powder, includes:

[0049] The Prussian blue analogue and the raw materials in stoichiometric proportions are mixed in an inert atmosphere and placed in a shearing machine. The mixture is sheared 1 to 10 times at a shearing power of 10,000 to 50,000 watts, with each shearing lasting 1 to 10 seconds, to obtain the solid electrolyte precursor powder.

[0050] Specifically, the Prussian blue analogue and the raw material are initially mixed in an argon-atmospheric glove box, and then the mixture is transferred to the sealed chamber of a shearing machine. Exemplarily, the shearing power can be 10 kW, 20 kW, 30 kW, 40 kW, 50 kW, etc.; the number of shearing cycles can be 1, 2, 5, 8, 10, etc.; and the duration of each shearing cycle can be 1 second, 2 seconds, 5 seconds, 8 seconds, 10 seconds, etc. For example, a combination of parameters can be used: 20 kW power for 5 shearing cycles with a duration of 3 seconds; or 40 kW power for 3 shearing cycles with a duration of 8 seconds; or 10 kW power for 10 shearing cycles with a duration of 1 second. The shearing and mixing process ensures that the raw material and the Prussian blue analogue are uniformly mixed.

[0051] In some embodiments, step S2, which involves compressing the solid electrolyte precursor powder under an inert atmosphere to prepare a solid electrolyte precursor sheet, includes:

[0052] The solid electrolyte precursor powder is placed in a tablet press, which is placed in an inert atmosphere and pressed into tablets at a pressure of 20 MPa to 400 MPa for 1 to 10 minutes to obtain the solid electrolyte precursor tablets.

[0053] Specifically, the solid electrolyte precursor powder is transferred to an argon-atmosphere glove box. A cylindrical stainless steel tableting mold with a diameter of 10-20 mm is selected, and the precursor powder is evenly filled into the mold cavity. The mold is then moved into a hydraulic tablet press, and the tableting parameters are set and the tableting operation is performed: the tableting pressure is controlled within the range of 20MPa to 400MPa. For example, the shearing power can be 20MPa, 50MPa, 100MPa, 150MPa, 200MPa, 250MPa, 300MPa, 350MPa, 400MPa, etc., and the tableting time (i.e., holding time) is set to 1 minute to 10 minutes. For example, the tableting time can be 1 minute, 2 minutes, 5 minutes, 8 minutes, or 10 minutes. For example, a combination of parameters such as 30 MPa pressure for 8 minutes, 50 MPa pressure for 5 minutes, 80 MPa pressure for 2 minutes, or 100 MPa pressure for 1 minute can be used. After tableting, the pressure is slowly released, and a solid electrolyte precursor tablet with a thickness of 0.5 mm to 5 mm and a smooth surface is obtained. Tableting within the above pressure range and tableting time range can ensure close contact between precursor powder particles to shorten the reaction diffusion path during calcination, while avoiding excessively high pressure that would lead to excessively low porosity, ensuring that the sulfur desorbed from the Prussian blue analogue can diffuse smoothly inside during calcination.

[0054] In some embodiments, step S3, which involves calcining the solid electrolyte precursor sheet to obtain the solid electrolyte sheet, includes:

[0055] The solid electrolyte precursor sheet is placed in a sealed container, and the sealed container is placed in a calcination device for segmented calcination treatment. The segmented calcination process includes heating the calcination device to 100℃~300℃ at a heating rate of 0.5℃ / min~4℃ / min for 1h~3h; heating the calcination device to 300℃~400℃ at a heating rate of 0.5℃ / min~10℃ / min for 1h~3h; and heating the calcination device to 400℃~800℃ at a heating rate of 5℃ / min~10℃ / min for 1h~4h.

[0056] In this embodiment, the calcination process is carried out in a muffle furnace under an inert atmosphere to prevent oxidation of raw materials and products. The solid electrolyte precursor sheet is subjected to segmented calcination to finally obtain the solid electrolyte sheet. Specifically, in the first stage, the temperature is increased from room temperature to 200℃~300℃ at a relatively low rate, and then held for 1h~3h after reaching the target temperature. This slow heating method reduces the volatilization rate of P2S5, preventing the release rate of sulfur species from exceeding the adsorption capacity of the Prussian blue analogue. At this point, the Prussian blue analogue is in its strongest adsorption state, thus effectively capturing and temporarily fixing the volatilized sulfur species, preventing sulfur loss and sulfur vacancy generation due to sulfur discharge from the system, and reserving a sulfur source for subsequent grain boundary repair. In the second stage, the temperature is increased at a rate of 0.5℃ / min~10℃ / min. The heating rate is increased to 300℃~400℃ and held for 1h~3h. Within this temperature range, the three raw materials, Li2S, P2S5 and LiCl, gradually undergo chemical reactions in an inert atmosphere to form a stable target crystalline phase. In the third stage, the temperature is increased to 400℃~800℃ at a higher heating rate and held for 1h~4h. The high temperature environment at this time can promote the desorption reaction of PBA, releasing the sulfur species captured in the early stage. Due to the airtightness of the sealed container, the released sulfur species form a high-concentration high-sulfur-pressure microenvironment in the local part of the particles, driving sulfur to diffuse directionally to the grain boundary defects, realizing in-situ filling and repair of the grain boundaries, thereby effectively reducing grain boundary voids and defects and reducing ion transport resistance.

[0057] Furthermore, after the segmented calcination is completed, inert gas is continuously introduced, the heating device is turned off, and the solid electrolyte sheet is cooled to room temperature with the furnace, finally obtaining a solid electrolyte sheet with a dense structure and few grain boundary defects.

[0058] In some embodiments, step S4, which involves pulverizing the solid electrolyte sheet to obtain the product sulfide solid electrolyte, includes:

[0059] The solid electrolyte sheet is placed in a shearing machine and sheared 1 to 5 times at a shearing power of 10,000 to 50,000 watts, with a single shearing time of 1 to 10 seconds, to obtain the product sulfide solid electrolyte.

[0060] Specifically, the solid electrolyte sheet calcined and cooled to room temperature in step S3 is transferred to an argon-atmospheric glove box. Then, the solid electrolyte sheet is placed in a shearing machine, shearing parameters are set, and a pulverization operation is performed. For example, the shearing power can be 10,000 watts, 20,000 watts, 30,000 watts, 40,000 watts, 50,000 watts, etc.; the number of shearing cycles can be 1, 2, 3, 4, or 5 times; and the duration of each shearing cycle can be 1 second, 2 seconds, 5 seconds, 8 seconds, or 10 seconds, etc. For example, a combination of parameters can be used, such as 20,000 watts for 3 shearing cycles with a duration of 5 seconds, 40,000 watts for 2 shearing cycles with a duration of 3 seconds, or 10,000 watts for 5 shearing cycles with a duration of 8 seconds. After pulverization, the product is sieved through a 200-mesh sieve to obtain a product sulfide solid electrolyte powder with a uniform particle size distribution.

[0061] An embodiment of this application also provides a sulfide solid electrolyte, which is prepared by the above-described method for preparing sulfide solid electrolytes.

[0062] In some embodiments, the chemical formula of the sulfide solid electrolyte includes Li6PS5Cl, Li 5.6 PS 4.6 Cl 1.4 Li 5.5 PS 4.5 Cl 1.5 and Li 5.4 PS 4.4 Cl 1.6 One or at least two of them.

[0063] The sulfide solid electrolyte provided in this application is prepared by the preparation method of the aforementioned embodiments. Through the three-dimensional open framework structure of Prussian blue analogue, it efficiently adsorbs and temporarily fixes sulfur species volatilized during calcination by means of its internal nanopores and metal sites. During subsequent heating, it achieves controllable desorption of sulfur species, creates a high sulfur pressure microenvironment in the local particles, drives sulfur to diffuse directionally to grain boundary defects and achieves in-situ filling, effectively reduces sulfur vacancy defects, optimizes the grain boundary structure, and inhibits the generation of grain boundary impurities. It has excellent ion conduction performance, helps to suppress lithium dendrite growth, and enhances the safety of battery use.

[0064] Embodiments of this application also provide a solid-state battery, including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, wherein the positive electrode layer and / or the solid electrolyte layer comprises a sulfide solid electrolyte prepared by the above-described method for preparing a sulfide solid electrolyte. Solid-state batteries using the sulfide solid electrolyte prepared in the foregoing embodiments exhibit superior electrochemical performance and better safety.

[0065] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be further described in detail below with reference to the accompanying drawings and several preferred embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Unless otherwise specified, the test methods in the following embodiments are performed under conventional conditions. Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0066] Example 1

[0067] Step 1: In an argon-filled glove box, 3.45g Li2S, 4.17g P2S5, 2.39g LiCl, and 0.5g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.25:0.32:1, and the mass ratio of Mn-PBA to the raw materials is 0.05:1. The mixture is then sheared 6 times at a shearing power of 30,000 watts, with each shearing lasting 6 seconds, to obtain the solid electrolyte powder precursor powder.

[0068] Step 2: Press the solid electrolyte precursor powder at 300 MPa for 5 minutes to obtain solid electrolyte precursor tablets.

[0069] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 300℃ at a heating rate of 0.5℃ / min for 2 hours. Then, heat the calcination equipment to 400℃ at a heating rate of 2℃ / min for 2 hours. Finally, heat the calcination equipment to 500℃ at a heating rate of 5℃ / min for 4 hours. Then, allow it to cool naturally to room temperature.

[0070] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it 5 times at a shearing power of 30,000 watts, each time for 1 second, to obtain the final product, sulfide solid electrolyte Li. 5.5 PS 4.5 Cl 1.5 .

[0071] Example 2

[0072] Step 1: In an argon-filled glove box, 3.28g Li2S, 4.17g P2S5, 2.55g LiCl, and 0.5g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.18:0.32:1, and the mass ratio of Mn-PBA to the raw materials is 0.05:1. The mixture is then sheared 10 times at a shearing power of 10,000 watts for 10 seconds each time to obtain the solid electrolyte powder precursor powder.

[0073] Step 2: Press the solid electrolyte precursor powder at 100 MPa for 10 minutes to obtain solid electrolyte precursor tablets.

[0074] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 250°C at a heating rate of 4°C / min for 3 hours. Then, heat the calcination equipment to 300°C at a heating rate of 0.5°C / min for 3 hours. Finally, heat the calcination equipment to 800°C at a heating rate of 10°C / min for 1 hour. Then, allow it to cool naturally to room temperature.

[0075] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it three times at a shearing power of 10,000 watts, each time for 5 seconds, to obtain the final product, sulfide solid electrolyte Li. 5.4 PS 4.4 Cl 1.6 .

[0076] Example 3

[0077] Step 1: In an argon-filled glove box, 3.61g Li2S, 4.16g P2S5, 2.22g LiCl, and 0.5g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.56:0.36:1, and the mass ratio of Mn-PBA to the raw materials is 0.05:1. The mixture is then sheared once with a shearing power of 50,000 watts, with each shearing lasting 1 second, to obtain the solid electrolyte powder precursor powder.

[0078] Step 2: Press the solid electrolyte precursor powder at 300 MPa for 5 minutes to obtain solid electrolyte precursor tablets.

[0079] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 200℃ at a heating rate of 2℃ / min for 1 hour. Then, heat the calcination equipment to 350℃ at a heating rate of 5℃ / min for 1 hour. Finally, heat the calcination equipment to 600℃ at a heating rate of 8℃ / min for 3 hours. Then, allow it to cool naturally to room temperature.

[0080] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it once with a shearing power of 50,000 watts for 10 seconds each time to obtain the final product, sulfide solid electrolyte Li. 5.6 PS 4.6 Cl 1.4 .

[0081] Example 4

[0082] Step 1: In an argon-filled glove box, 3.45g Li2S, 4.17g P2S5, 2.39g LiCl, and 0.1g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.25:0.32:1, and the mass ratio of Mn-PBA to the raw materials is 0.01:1. The mixture is then sheared 6 times at a shearing power of 30,000 watts, with each shearing lasting 6 seconds, to obtain the solid electrolyte powder precursor powder.

[0083] Step 2: Press the solid electrolyte precursor powder at 300 MPa for 8 minutes to obtain solid electrolyte precursor tablets.

[0084] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 200℃ at a heating rate of 3℃ / min for 3 hours. Then, heat the calcination equipment to 400℃ at a heating rate of 10℃ / min for 2 hours. Finally, heat the calcination equipment to 500℃ at a heating rate of 5℃ / min for 4 hours. Then, allow it to cool naturally to room temperature.

[0085] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it 5 times at a shearing power of 30,000 watts, each time for 1 second, to obtain the final product, sulfide solid electrolyte Li. 5.5 PS 4.5 Cl 1.5 .

[0086] Example 5

[0087] Step 1: In an argon-filled glove box, 3.45g Li2S, 4.17g P2S5, 2.39g LiCl, and 50g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.25:0.32:1, and the mass ratio of Mn-PBA to the raw materials is 5:1. The mixture is then sheared 6 times at a shearing power of 30,000 watts, with each shearing lasting 6 seconds, to obtain the solid electrolyte powder precursor powder.

[0088] Step 2: Press the solid electrolyte precursor powder at 300 MPa for 5 minutes to obtain solid electrolyte precursor tablets.

[0089] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 300℃ at a heating rate of 0.5℃ / min for 2 hours. Then, heat the calcination equipment to 400℃ at a heating rate of 2℃ / min for 2 hours. Finally, heat the calcination equipment to 500℃ at a heating rate of 5℃ / min for 4 hours. Then, allow it to cool naturally to room temperature.

[0090] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it 5 times at a shearing power of 30,000 watts, each time for 1 second, to obtain the final product, sulfide solid electrolyte Li. 5.5 PS 4.5 Cl 1.5 .

[0091] Example 6

[0092] Step 1: In an argon-filled glove box, 3.45g Li2S, 4.17g P2S5, 2.39g LiCl, and 0.5g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.25:0.32:1, and the mass ratio of Mn-PBA to the raw materials is 0.05:1. The mixture is then sheared 6 times at a shearing power of 30,000 watts, with each shearing lasting 6 seconds, to obtain the solid electrolyte powder precursor powder.

[0093] Step 2: Press the solid electrolyte precursor powder at a pressure of 20 MPa for 5 minutes to obtain solid electrolyte precursor tablets.

[0094] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 300℃ at a heating rate of 0.5℃ / min for 2 hours. Then, heat the calcination equipment to 400℃ at a heating rate of 2℃ / min for 2 hours. Finally, heat the calcination equipment to 500℃ at a heating rate of 5℃ / min for 4 hours. Then, allow it to cool naturally to room temperature.

[0095] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it 5 times at a shearing power of 30,000 watts, each time for 1 second, to obtain the final product, sulfide solid electrolyte Li. 5.5 PS 4.5 Cl 1.5 .

[0096] Example 7

[0097] Step 1: In an argon-filled glove box, 3.45g Li2S, 4.17g P2S5, 2.39g LiCl, and 0.5g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.25:0.32:1, and the mass ratio of Mn-PBA to the raw materials is 0.05:1. The mixture is then sheared 6 times at a shearing power of 30,000 watts, with each shearing lasting 6 seconds, to obtain the solid electrolyte powder precursor powder.

[0098] Step 2: Press the solid electrolyte precursor powder at 400 MPa for 5 minutes to obtain solid electrolyte precursor tablets.

[0099] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 300℃ at a heating rate of 0.5℃ / min for 2 hours. Then, heat the calcination equipment to 400℃ at a heating rate of 2℃ / min for 2 hours. Finally, heat the calcination equipment to 500℃ at a heating rate of 5℃ / min for 4 hours. Then, allow it to cool naturally to room temperature.

[0100] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it 5 times at a shearing power of 30,000 watts, each time for 1 second, to obtain the final product, sulfide solid electrolyte Li. 5.5 PS 4.5 Cl 1.5 .

[0101] Example 8

[0102] Step 1: In an argon-filled glove box, 3.45g Li2S, 4.17g P2S5, 2.39g LiCl, and 0.5g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.25:0.32:1, and the mass ratio of Mn-PBA to the raw materials is 0.05:1. The mixture is then sheared 6 times at a shearing power of 30,000 watts, with each shearing lasting 6 seconds, to obtain the solid electrolyte powder precursor powder.

[0103] Step 2: Press the solid electrolyte precursor powder at 300 MPa for 5 minutes to obtain solid electrolyte precursor tablets.

[0104] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 300℃ at a heating rate of 0.5℃ / min for 2 hours. Then, heat the calcination equipment to 300℃ at a heating rate of 2℃ / min for 2 hours. Finally, heat the calcination equipment to 400℃ at a heating rate of 5℃ / min for 4 hours. Then, allow it to cool naturally to room temperature.

[0105] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it 5 times at a shearing power of 30,000 watts, each time for 1 second, to obtain the final product, sulfide solid electrolyte Li. 5.5 PS 4.5 Cl 1.5 .

[0106] Example 9

[0107] Step 1: In an argon-filled glove box, 3.45g Li2S, 4.17g P2S5, 2.39g LiCl, and 0.5g Mn-PBA (Prussian blue analogue) are initially mixed. The molar ratio of Li2S:P2S5:LiCl is 1.25:0.32:1, and the mass ratio of Mn-PBA to the raw materials is 0.05:1. The mixture is then sheared 6 times at a shearing power of 30,000 watts, with each shearing lasting 6 seconds, to obtain the solid electrolyte powder precursor powder.

[0108] Step 2: Press the solid electrolyte precursor powder at 300 MPa for 5 minutes to obtain solid electrolyte precursor tablets.

[0109] Step 3: Place the solid electrolyte precursor sheet in a crucible and seal it. Then place it in a muffle furnace for calcination. First, heat the calcination equipment to 300℃ at a heating rate of 0.5℃ / min for 2 hours. Then, heat the calcination equipment to 400℃ at a heating rate of 2℃ / min for 2 hours. Finally, heat the calcination equipment to 800℃ at a heating rate of 5℃ / min for 4 hours. Then, allow it to cool naturally to room temperature.

[0110] Step 4: Place the solid electrolyte sheet into a shearing machine and shear it 5 times at a shearing power of 30,000 watts, each time for 1 second, to obtain the final product, sulfide solid electrolyte Li. 5.5 PS 4.5 Cl 1.5 .

[0111] Comparative Example 1

[0112] The difference between this comparative example and Example 1 is that step three uses the following steps:

[0113] The solid electrolyte precursor sheet was placed in a muffle furnace for calcination. The calcination process was carried out at a heating rate of 2℃ / min. After heating to 500℃, it was kept at a constant temperature for 8 hours and then cooled naturally to room temperature.

[0114] Everything else is the same as in Example 1.

[0115] Comparative Example 2

[0116] The difference between this comparative example and Example 1 is that Mn-PBA is not added.

[0117] Comparative Example 3

[0118] The difference between this comparative example and Example 1 is that Mn-PBA was added, and the mass ratio of Mn-PBA to the raw material was 15:1.

[0119] Raman spectroscopy was performed on the sulfide solid electrolytes obtained in Example 1 and Comparative Example 2. The test spectra are shown below. Figure 1 As shown. From Figure 1 The Raman spectra of Example 1 show that the main peak is close to that of PS4. 3- The standard vibration wavenumber of the group was significantly different from that of Comparative Example 2, while the main peak of Comparative Example 2 was significantly shifted. This indicates that the addition of Prussian blue analogues can effectively reduce sulfur vacancy defects in sulfide solid electrolytes, thereby further improving the ionic conductivity and other properties of the electrolyte.

[0120] The ionic conductivity of the sulfide solid electrolytes prepared in the above embodiments and comparative examples was tested. Specifically, the ionic conductivity testing method was as follows: 100 mg of the prepared solid electrolyte was weighed into a 10 mm stainless steel pressing mold, and the electrolyte sheet was pressed under a pressure of 400 MPa. Then, carbon-coated aluminum foil was added to both sides of the electrolyte sheet for encapsulation. The battery mold was removed, placed in a battery clamp, and pressed under a pressure of 50 MPa to obtain a sandwich-type all-solid-state battery. Then, the ionic conductivity of the solid electrolyte was measured.

[0121] The sulfide solid electrolytes obtained using the above embodiments and comparative examples were used to prepare solid-state batteries for electrochemical performance testing.

[0122] Specifically, the method for preparing all-solid-state batteries is as follows:

[0123] (1) Preparation of NCM811 composite cathode material: NCM811, the solid electrolyte prepared in the above examples or comparative examples, and vapor-grown carbon fiber (VGCF) were weighed into a mortar at a mass ratio of 75:24:1. The total mass of the materials was 2g. After manual grinding for 20min, NCM811 composite cathode material was finally obtained.

[0124] (2) Preparation of solid electrolyte sheets:

[0125] 100 mg of the prepared solid electrolyte was weighed into a 10 mm stainless steel pressing mold and pressed into an electrolyte sheet under a pressure of 250 MPa. Then, 10 mg of the NCM811 composite positive electrode material prepared by the above method was added to one side of the solid electrolyte sheet, and it was pressed again under a pressure of 350 MPa. The sheet was then demolded and placed into a suitable battery testing mold. A 9 mm lithium indium sheet was then added to the other side of the solid electrolyte sheet. Finally, an Al current collector was placed on the positive electrode side and a Cu current collector was placed on the negative electrode side to complete the encapsulation. The battery testing mold was removed, placed in a battery fixture, and pressed under a pressure of 50 MPa to obtain a sandwich-type all-solid-state battery.

[0126] The performance testing method for all-solid-state batteries is as follows:

[0127] The assembled all-solid-state battery was subjected to a capacitor discharge test at a rate of 0.1C at room temperature to test the battery's first discharge specific capacity.

[0128] The test results of the above embodiments and comparative examples are listed in Table 1 below. Figure 2 The ionic conductivity spectra of the sulfide solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-3 are shown. Figure 3 The graph shows a comparison of the first charge-discharge performance of the solid-state batteries prepared in Examples 1-3 and Comparative Examples 1-3.

[0129] Table 1

[0130]

[0131] From Table 1 and Figure 2 , Figure 3 The test data show that the addition of Prussian blue analogues is beneficial to improving the ionic conductivity and first-cycle discharge specific capacity of sulfide solid electrolytes. Examples (such as Example 1) with an appropriate amount of Prussian blue analogue added show an ionic conductivity of 11.8 mS·cm. -1 First discharge capacity: 195mAh·g -1 The performance of this sample is significantly superior to other samples. Neither the addition of Prussian blue analogues nor the addition of excessive amounts leads to a significant decrease in material performance. This is because without Prussian blue analogues, sulfur loss results in grain boundary defects; while excessive Prussian blue analogues introduce excessive transition metal impurities. After adding Prussian blue analogues, a suitable segmented calcination mechanism is required during the calcination process to effectively improve the electrochemical performance of the sulfide solid electrolyte.

[0132] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A method for preparing a sulfide solid electrolyte, characterized in that, The preparation method includes: Prussian blue analogues and raw materials in stoichiometric proportions were mixed in an inert atmosphere to obtain solid electrolyte precursor powder. The solid electrolyte precursor powder was compressed into tablets under an inert atmosphere to prepare solid electrolyte precursor tablets. The solid electrolyte precursor sheet is calcined to obtain a solid electrolyte sheet. The solid electrolyte sheet is pulverized to obtain the product sulfide solid electrolyte.

2. The method for preparing the sulfide solid electrolyte as described in claim 1, characterized in that, The raw materials include Li2S, P2S5 and LiCl, and the stoichiometric ratio of the raw materials is (1-3):(0.1-3):1, where the molar ratio of Li2S:P2S5:LiCl is (1-3):(0.1-3):

1.

3. The method for preparing the sulfide solid electrolyte as described in claim 1, characterized in that, The chemical formula of the Prussian blue analogue is A. x M[M'(CN)6] y ·zH2O, wherein M and M' are independently selected from one or more of Fe, Mn, Co, Ni, and Cu, and A is an alkali metal ion or a vacancy, wherein 0≤x≤2, 0≤y<1, and 0≤z≤5.

4. The method for preparing the sulfide solid electrolyte as described in claim 1, characterized in that, The mass ratio of the Prussian blue analogue to the total amount of the raw material is (0.01-5):

1.

5. The method for preparing the sulfide solid electrolyte as described in claim 1, characterized in that, The step of mixing the Prussian blue analogue and raw materials in stoichiometric proportions under an inert atmosphere to obtain a solid electrolyte precursor powder includes: The Prussian blue analogue and the raw materials in stoichiometric proportions are mixed in an inert atmosphere and placed in a shearing machine. The mixture is sheared 1 to 10 times at a shearing power of 10,000 to 50,000 watts, with each shearing lasting 1 to 10 seconds, to obtain the solid electrolyte precursor powder.

6. The method for preparing the sulfide solid electrolyte as described in claim 1, characterized in that, The step of compressing the solid electrolyte precursor powder under an inert atmosphere to prepare a solid electrolyte precursor tablet includes: The solid electrolyte precursor powder is placed in a tablet press, which is placed in an inert atmosphere and pressed into tablets at a pressure of 20 MPa to 400 MPa for 1 to 10 minutes to obtain the solid electrolyte precursor tablets.

7. The method for preparing the sulfide solid electrolyte as described in claim 1, characterized in that, The step of calcining the solid electrolyte precursor sheet to obtain the solid electrolyte sheet includes: The solid electrolyte precursor sheet is placed in a sealed container, and the sealed container is placed in a calcination device for segmented calcination treatment. The segmented calcination process includes: heating the calcination device to 100℃~300℃ at a heating rate of 0.5℃ / min~4℃ / min for 1h~3h; heating the calcination device to 300℃~400℃ at a heating rate of 0.5℃ / min~10℃ / min for 1h~3h; and heating the calcination device to 400℃~800℃ at a heating rate of 5℃ / min~10℃ / min for 1h~4h. And / or the step of pulverizing the solid electrolyte sheet to obtain the product sulfide solid electrolyte includes: The solid electrolyte sheet is placed in a shearing machine and sheared 1 to 5 times at a shearing power of 10,000 to 50,000 watts, with a single shearing time of 1 to 10 seconds, to obtain the product sulfide solid electrolyte.

8. A sulfide solid electrolyte, characterized in that, It is prepared by the method for preparing sulfide solid electrolyte as described in any one of claims 1-7.

9. The sulfide solid electrolyte as described in claim 8, characterized in that, The chemical formula of the sulfide solid electrolyte includes Li6PS5Cl, Li 5.6 PS 4.6 Cl 1.4 Li 5.5 PS 4.5 Cl 1.5 and Li 5.4 PS 4.4 Cl 1.6 One or at least two of them.

10. A solid-state battery, comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, characterized in that, The positive electrode layer and / or the solid electrolyte layer comprises a sulfide solid electrolyte prepared by the method for preparing a sulfide solid electrolyte as described in any one of claims 1-7.

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