A method for preparing a oxyfluoride solid-state electrolyte, and an oxyfluoride solid-state electrolyte

Abstract

The application relates to a preparation method of a fluorine oxide solid electrolyte and the fluorine oxide solid electrolyte. The preparation method comprises the following steps: grinding a lithium source material, a lanthanum source material, a material containing a doped element, a pore-forming agent and a solvent in a grinding machine to obtain a mixed slurry; performing spray granulation on the mixed slurry to obtain initial microparticles; placing the initial microparticles in a boiling bed reactor, performing sintering under an air atmosphere to remove the pore-forming agent and residual solvent, obtaining porous microparticles, switching the atmosphere to a fluorine-containing gas to perform sintering again, making the fluorine-containing active body decomposed from the fluorine-containing gas react with the porous microparticles, naturally cooling to room temperature under an inert gas atmosphere, obtaining a fluorine oxide solid electrolyte block, and performing crushing treatment to obtain the fluorine oxide solid electrolyte. The fluorine oxide solid electrolyte prepared by the preparation method has the characteristics of high compactness and high ionic conductivity, can be widely applied in lithium batteries, and is especially applied in full solid-state lithium batteries.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte materials technology, and in particular to a method for preparing a fluoride oxide solid electrolyte and the fluoride oxide solid electrolyte itself. Background Technology

[0002] Lithium-ion batteries are widely used in various fields. Most lithium-ion batteries use liquid organic electrolytes, while all-solid-state batteries, which employ solid electrolytes, offer numerous advantages over liquid electrolytes, such as non-flammability, high safety, a wide electrochemical window, and good thermal stability. They are considered key materials for next-generation battery technology. Among these, fluorine oxide solid electrolytes have attracted widespread attention due to their excellent ionic conductivity and electrochemical stability.

[0003] However, existing technologies for preparing fluorine oxide solid electrolytes still present several challenges. Firstly, while the high-temperature solid-state method is simple, it requires prolonged high-temperature calcination. Solid electrolytes prepared using this method often exhibit large particles, high hardness, intact crystals, and low sintering activity. Densification requires extremely high sintering temperatures and long holding times, leading to impurities and excessive loss of volatile substances in the final product. Secondly, conventional sintering processes struggle to balance high material density with low energy consumption, resulting in either low ionic conductivity or excessively high energy consumption. Furthermore, existing research on the preparation of fluorine oxide solid electrolytes is relatively limited, particularly for multi-element doped fluorine oxide solid electrolyte materials. The preparation process for these materials is not yet fully optimized, making it difficult to simultaneously achieve both high density and high ionic conductivity.

[0004] Therefore, there is an urgent need to develop a method for preparing fluorine oxide solid electrolyte materials that can achieve uniform mixing of raw materials, improve sintering efficiency, reduce production energy consumption, and simultaneously enhance the density and ionic conductivity of the materials. Summary of the Invention

[0005] The purpose of this invention is to address the deficiencies of existing technologies by providing a method for preparing a fluoride oxide solid electrolyte and a fluoride oxide solid electrolyte.

[0006] This invention reduces the initial particle size of non-fluorine source raw materials (referring to raw materials other than fluorine source materials for preparing fluorine oxide solid electrolytes) by grinding and mixing them with a pore-forming agent, thereby increasing the specific surface area and activity of the raw materials and improving the mixing uniformity. Then, spray granulation is used to instantly dehydrate the surface of the slurry droplets to form a gel shell, "freezing" the mixed raw materials within microspheres to obtain initial microparticles, providing conditions for subsequent preparation of porous structures. These initial microparticles are then placed in a fluidized bed reactor for a first-stage sintering process to remove the pore-forming agent and residual solvent, resulting in porous microparticles. These porous microparticles can be further sintered in a second stage. The fluorination reaction provides a large reaction interface, allowing porous particles to react with fluorine-containing gaseous solids, improving reaction uniformity and enabling fluorine to be uniformly incorporated into the crystal lattice. This enhances the consistency of the final product's composition and structure. The fluorination product is then pulverized. During pulverization, the connections within the porous structure of the fluorination product break, resulting in non-porous, smaller (submicron-scale) but dense fluoride oxide solid electrolyte crystal fragments. Because the fluorination product contains pores, the pulverization process breaks down the multi-point connections within these pores, achieving better pulverization results with lower energy consumption. The preparation method provided by this invention can be carried out at lower temperatures and in shorter times, thereby reducing energy consumption and improving efficiency.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a fluorine oxide solid electrolyte, the method comprising:

[0008] According to the stoichiometric ratio of the general chemical formula of fluoride oxide solid electrolyte, lithium source material, lanthanum source material, and material containing doped elements are weighed as raw materials, and placed together with pore-forming agent and solvent in a grinding mill for grinding to obtain a mixed slurry; wherein, the material containing doped elements includes one or more of the following: material containing M1 element, material containing M2 element, and material containing M3 element.

[0009] The mixed slurry is spray-granulated to obtain initial microparticles.

[0010] The initial microparticles are placed in a fluidized bed reactor and sintered in an air atmosphere to remove the pore-forming agent and residual solvent, thereby obtaining porous microparticles; the porous microparticles are oxide precursor particles with a porous structure.

[0011] The atmosphere in the fluidized bed reactor is switched to a fluorine-containing gas for a second-stage sintering process, whereby the fluorine-containing gas decomposes and / or the fluorine-containing active components react with the porous microparticles inside and on the surface of the oxide precursor particles. After sintering, heating is stopped, the atmosphere is switched to an inert gas atmosphere, and the mixture is allowed to cool naturally to room temperature to obtain the fluorine oxide solid electrolyte.

[0012] Preferably, the lithium source material includes one or more of lithium carbonate, lithium hydroxide, lithium oxalate, lithium acetate, and lithium nitrate.

[0013] The lanthanum source material includes one or more of the following: lanthanum trioxide, lanthanum carbonate, lanthanum nitrate, lanthanum hydroxide, and lanthanum fluoride.

[0014] The chemical formula of the fluoride oxide solid electrolyte is Li x La y M1 a M2 b M3 c O6F, where x, y, a, b, and c are the molar percentages of the corresponding elements, and 1 < x + 3y < 5, 0 < x ≤ 2, 1 / 3 < y < 5 / 3, 0 ≤ a ≤ 2, 0 ≤ b ≤ 2, 0 ≤ c ≤ 2, a + b + c = 2, element M1 is a tetravalent cation, element M2 is a pentavalent cation, and element M3 is a hexavalent cation.

[0015] The pore-forming agent includes one or more of polyethylene glycol, polyvinylpyrrolidone, starch, and polymethyl methacrylate; the mass of the pore-forming agent accounts for 1% to 20% of the total mass of the raw materials.

[0016] Preferably, the M1 element specifically includes one or more of Zr, Ti, Hf, Si, Ge, and Sn.

[0017] The M2 element specifically includes one or more of Nb, Sb, Bi, V, and Ta.

[0018] The M3 element specifically includes one or more of W, Cr, Mo, and Mn.

[0019] Preferably, the solvent includes one or more of deionized water, ethanol, NMP, isopropanol, and acetone.

[0020] The grinding mill's rotation speed is set to 1000 rpm to 3000 rpm, and the grinding process takes 1 hour to 6 hours.

[0021] The solid content of the mixed slurry is 10wt% to 45wt%.

[0022] Preferably, the spray granulation equipment is a spray dryer; the inlet temperature of the spray dryer is 180℃~240℃, and the outlet temperature is 60℃~120℃.

[0023] Preferably, the air velocity in the fluidized bed reactor is 0.01 m / s to 1 m / s.

[0024] The first sintering stage specifically includes: heating the fluidized bed reactor from room temperature to 300℃ to 500℃ at a heating rate of 1℃ / min to 8℃ / min, and holding it at that temperature for 1 hour to 8 hours.

[0025] The porosity of the porous microparticles is 30% to 50%.

[0026] Preferably, the fluorine-containing gas includes one or more of nitrogen tetrafluoride, nitrogen trifluoride, hydrogen fluoride vapor, polytetrafluoroethylene, and ammonium fluoride; the flow rate of the fluorine-containing gas in the fluidized bed reactor is 0.01 m / s to 1 m / s.

[0027] The second stage of sintering specifically includes: heating the fluidized bed reactor to 600℃ to 900℃ at a heating rate of 1℃ / min to 8℃ / min, and holding it at that temperature for 1 hour to 12 hours.

[0028] The inert gas includes one or more of nitrogen, argon, and helium; the flow rate of the inert gas in the fluidized bed reactor is 0.01 m / s to 1 m / s.

[0029] Preferably, after the natural cooling to room temperature, the preparation method further includes: pulverizing the fluorine oxide solid electrolyte block.

[0030] The equipment used for the pulverization process is a fluidized bed jet mill or a flat jet mill.

[0031] The pressure of the compressed air during the pulverization process is between 0.5 MPa and 3 MPa, and the dew point of the compressed air is less than -20°C.

[0032] Secondly, the present invention provides a fluoride oxide solid electrolyte prepared by the preparation method described in the first aspect above, wherein the chemical formula of the fluoride oxide solid electrolyte is Li. x La y M1 a M2 b M3 c O6F, where x, y, a, b, and c are the molar percentages of the corresponding elements, and 1 < x + 3y < 5, 0 < x ≤ 2, 1 / 3 < y < 5 / 3, 0 ≤ a ≤ 2, 0 ≤ b ≤ 2, 0 ≤ c ≤ 2, a + b + c = 2, element M1 is a tetravalent cation, element M2 is a pentavalent cation, and element M3 is a hexavalent cation.

[0033] The particle size Dv50 of the fluorine oxide solid electrolyte is 200 nm to 2.0 μm.

[0034] The density of the fluorine oxide solid electrolyte is greater than 90%.

[0035] The ionic conductivity of the fluorine oxide solid electrolyte is greater than 6 mS / cm.

[0036] Preferably, the M1 element specifically includes one or more of Zr, Ti, Hf, Si, Ge, and Sn.

[0037] The M2 element specifically includes one or more of Nb, Sb, Bi, V, and Ta.

[0038] The M3 element specifically includes one or more of W, Cr, Mo, and Mn.

[0039] Thirdly, the present invention provides a lithium battery comprising a fluorine oxide solid electrolyte prepared by the preparation method described in the first aspect, or a fluorine oxide solid electrolyte as described in the second aspect.

[0040] The present invention provides a method for preparing a fluoride oxide solid electrolyte and a fluoride oxide solid electrolyte, which has the following technical effects.

[0041] (1) The present invention provides a method for preparing a solid electrolyte of fluorine oxides. First, a non-fluorine raw material is ground and mixed with a pore-forming agent and a solvent to form a slurry. Then, the slurry is spray-granulated to obtain initial microparticles. The initial microparticles are placed in a fluidized bed reactor for a first-stage sintering to remove the pore-forming agent and residual solvent from the initial microparticles and obtain porous microparticles. Then, a fluorine source gas is introduced for a second-stage sintering to allow the fluorine-containing active body decomposed by the fluorine source gas to fully react with the porous microparticles. The product after the reaction is then pulverized to obtain a solid electrolyte of fluorine oxides.

[0042] The preparation method of this invention reduces the initial particle size of the raw materials through grinding, thereby increasing the specific surface area, enhancing the activity of the raw materials, and improving the mixing uniformity. Spray granulation instantly dehydrates the surface of the slurry droplets to form a gel shell, "freezing" the mixed state of the raw materials within microspheres to obtain initial microparticles, providing conditions for subsequent preparation of porous structures. A two-stage sintering process is performed in a fluidized bed reactor. The first stage sintering forms porous microparticles, and the second stage sintering allows the porous microparticles to react with fluorine-containing gas, enabling uniform doping of fluorine into the crystal lattice. This improves the consistency of the final product in terms of composition and structure, resulting in stable performance of the obtained fluorine oxide solid electrolyte. The preparation method provided by this invention has low energy consumption, reduces costs, and improves efficiency.

[0043] (2) The fluorine oxide solid electrolyte prepared by the preparation method provided by the present invention has the characteristics of high density and high ionic conductivity, and can be widely used in lithium batteries, especially in all-solid-state lithium batteries. Attached Figure Description

[0044] Figure 1A flowchart illustrating the preparation method of a fluorine oxide solid electrolyte provided in an embodiment of the present invention.

[0045] Figure 2 The X-ray diffraction (XRD) patterns are of the solid electrolytes prepared in Examples 1, 1, 2 and 3 of this invention. Detailed Implementation

[0046] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0048] This invention provides a method for preparing a fluoride oxide solid electrolyte, such as... Figure 1 As shown, the specific steps include:

[0049] Step 110: According to the stoichiometric ratio of the general chemical formula of fluorine oxide solid electrolyte, weigh the lithium source material, lanthanum source material, and material containing doped elements as raw materials, and place them together with the pore-forming agent and solvent in a grinding mill for grinding to obtain a mixed slurry.

[0050] The general chemical formula of the fluoride oxide solid electrolyte to be prepared is Li. x La y M1 a M2 b M3 c O6F, where x, y, a, b, and c are the molar percentages of the corresponding elements, and 1 < x + 3y < 5, 0 < x ≤ 2, 1 / 3 < y < 5 / 3, 0 ≤ a ≤ 2, 0 ≤ b ≤ 2, 0 ≤ c ≤ 2, a + b + c = 2, M1 is a tetravalent cation, M2 is a pentavalent cation, and M3 is a hexavalent cation. Weigh the raw materials according to this chemical formula.

[0051] Lithium source materials include one or more of the following: lithium carbonate, lithium hydroxide, lithium oxalate, lithium acetate, and lithium nitrate.

[0052] Lanthanum source materials include one or more of the following: lanthanum trioxide, lanthanum carbonate, lanthanum nitrate, lanthanum hydroxide, and lanthanum fluoride.

[0053] Materials containing doped elements include one or more of the following: materials containing M1, materials containing M2, and materials containing M3. Specifically, M1 specifically includes one or more of Zr, Ti, Hf, Si, Ge, and Sn. M2 specifically includes one or more of Nb, Sb, Bi, V, and Ta. M3 specifically includes one or more of W, Cr, Mo, and Mn.

[0054] The pore-forming agent includes one or more of polyethylene glycol, polyvinylpyrrolidone, starch, and polymethyl methacrylate; the mass of the pore-forming agent accounts for 1% to 20% of the total mass of the raw materials.

[0055] Solvents include one or more of the following: deionized water, ethanol, NMP, isopropanol, and acetone.

[0056] The grinding speed is set to 1000rpm to 3000rpm, and can be any value within this range, such as 1000rpm, 1500rpm, 2000rpm, 2500rpm, 3000rpm, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] The grinding time is 1 to 6 hours, and can be any value within this range, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] The solid content of the mixed slurry is 10wt to 45wt.

[0059] In this step, grinding is used to reduce the initial particle size of the raw materials, thereby increasing the specific surface area of ​​the raw materials, improving the activity of the raw materials, and improving the uniformity of mixing of multiple materials.

[0060] Step 120: Spray granulation of the mixed slurry to obtain initial microparticles.

[0061] The equipment used for spray granulation is a spray dryer; the inlet temperature of the spray dryer is 180℃~240℃, and the outlet temperature is 60℃~120℃.

[0062] This step involves spray drying to instantly dehydrate the surface of the droplets of the mixed slurry, forming a gel shell. This "freezes" the mixed raw materials within the gel shell, resulting in initial microparticles and providing conditions for the subsequent preparation of porous particles.

[0063] Step 130: The initial microparticles are placed in a fluidized bed reactor and sintered in an air atmosphere to remove the pore-forming agent and residual solvent, thereby obtaining porous microparticles.

[0064] In the fluidized bed reactor, the air velocity is 1.5 m / s to 3.0 m / s.

[0065] The first stage of sintering specifically includes: heating the fluidized bed reactor from room temperature to 300℃ to 500℃ at a heating rate of 1℃ / min to 8℃ / min, and holding it at that temperature for 1 hour to 8 hours.

[0066] The porosity of porous microparticles is 30% to 50%.

[0067] The porous microparticles prepared in this step are oxide precursor particles with a porous structure. By using a fluidized bed reactor with uniform temperature, easy control, and sufficient interphase contact, porous microparticles are obtained by removing the pore-forming agent during the first-stage sintering heating. This greatly increases the specific surface area of ​​the particles, providing a large reaction interface for the subsequent fluorination reaction and providing channels for the diffusion of fluorine-containing gas. This allows the fluorine-containing gas to penetrate deep into the particle interior along the pores during the second-stage sintering, achieving a "from the inside out" or "simultaneous inside and outside" reaction. Compared with the traditional one-step preparation of fluorine oxide solid electrolytes, the distributed preparation can first form oxide precursor particles with a porous structure, thus fundamentally avoiding the problem of a dense outer shell formed directly in one-step preparation, which prevents the material interior from fully reacting with fluorine. In other words, it solves the problem of incomplete reaction caused by the "core-shell structure" easily generated in the traditional preparation process.

[0068] Step 140: Switch the atmosphere in the fluidized bed reactor to a fluorine-containing gas and carry out the second stage of sintering, so that the fluorine-containing gas and / or the fluorine-containing active body decomposed by the fluorine-containing gas react with the porous particles; after sintering, stop heating, switch the atmosphere to an inert gas atmosphere, and cool naturally to room temperature to obtain a fluorine oxide solid electrolyte.

[0069] The fluorine-containing gases include one or more of nitrogen tetrafluoride, nitrogen trifluoride, hydrogen fluoride vapor, polytetrafluoroethylene, and ammonium fluoride; the flow rate of the fluorine-containing gases in the fluidized bed reactor is 1.5 m / s to 3.0 m / s; the fluorine-containing active substances are highly reactive fluorine-containing materials, including elemental fluorine, fluorine radicals, hydrogen fluoride, and small molecule fluorocarbons; small molecule fluorocarbons include hexafluoroethylene, carbon tetrafluoride, and octafluorocyclobutane. Different fluorine-containing gases are selected and decomposed at high temperatures to obtain different fluorine-containing active substances. The fluorine-containing gases themselves or the decomposed fluorine-containing active substances can react with porous particles inside the pores and on the surface of the porous oxide precursor particles.

[0070] The second stage of sintering specifically includes: heating the fluidized bed reactor to 600℃~900℃ at a heating rate of 1℃ / min~8℃ / min, and holding it at that temperature for 1 hour~12 hours.

[0071] Inert gases include one or more of nitrogen, argon, and helium; the flow rate of inert gases in the fluidized bed reactor is 1.5 m / s to 3.0 m / s.

[0072] In the second stage of sintering in this step, due to the porous structure formed by the first stage of sintering, the fluorine-containing gas can fully react with the porous microparticles in gas-solid contact, and the fluorine element can be uniformly doped into the crystal lattice. This not only improves the density of the fluorine oxide solid electrolyte, but also ensures the uniformity of composition and structure, thereby promoting ion transport and significantly improving ionic conductivity.

[0073] Step 150: The fluorine oxide solid electrolyte is pulverized.

[0074] The equipment used for pulverization is either a fluidized bed jet mill or a flat jet mill.

[0075] The pressure of the compressed air during the pulverization process is between 0.5MPa and 3MPa, and the dew point of the compressed air is less than -20℃.

[0076] The chemical formula of the fluoride oxide solid electrolyte prepared in this embodiment of the invention is Li. x La y M1 a M2 b M3 c O6F, where x, y, a, b, and c are the molar percentages of the corresponding elements, and 1 < x + 3y < 5, 0 < x ≤ 2, 1 / 3 < y < 5 / 3, 0 ≤ a ≤ 2, 0 ≤ b ≤ 2, 0 ≤ c ≤ 2, a + b + c = 2. Element M1 is a tetravalent cation, element M2 is a pentavalent cation, and element M3 is a hexavalent cation. Specifically, element M1 includes one or more of Zr, Ti, Hf, Si, Ge, and Sn. Element M2 includes one or more of Nb, Sb, Bi, V, and Ta. Element M3 includes one or more of W, Cr, Mo, and Mn.

[0077] The particle size Dv50 of the fluorine oxide solid electrolyte prepared by the preparation method provided in this embodiment of the invention is between 200 nm and 2.0 μm, and can be any value within this range, such as: 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0078] The fluorine oxide solid electrolyte prepared in this embodiment of the invention has a density greater than 90%.

[0079] The ionic conductivity of the fluorine oxide solid electrolyte prepared in this embodiment of the invention is greater than 6 mS / cm.

[0080] The fluorine oxide solid electrolyte prepared in the embodiments of the present invention can be used in lithium batteries, for example, as an additive in the preparation of negative electrode and / or positive electrode, and / or as a solid electrolyte membrane in the assembly of all-solid-state batteries.

[0081] To better understand the technical solution provided by the present invention, the preparation method and characteristics of the fluoride oxide solid electrolyte of the present invention are illustrated below with several specific examples.

[0082] Example 1

[0083] This invention provides a fluoride oxide solid electrolyte Li 1.25 La 0.58 The preparation method of Nb2O6F specifically includes the following steps.

[0084] (1) According to the chemical formula of the fluoride oxide solid electrolyte, Li 1.25 La 0.58 To obtain Nb₂O₆F, lithium carbonate, lanthanum trioxide, and niobium pentoxide were weighed as raw materials and placed together with polyethylene glycol and deionized water in a grinding mill. The mixture was ground at 1800 rpm for 3.5 hours to obtain a mixed slurry with a solid content of 25 wt%. Polyethylene glycol accounted for 10% of the raw materials.

[0085] (2) The mixed slurry is placed in a spray dryer for spray granulation. The inlet temperature of the spray dryer is 220℃ and the outlet temperature is 120℃ to obtain initial microparticles.

[0086] (3) The initial particles were placed in a fluidized bed reactor. Under an air atmosphere, the air velocity in the fluidized bed reactor was 0.15 m / s. The fluidized bed reactor was heated from room temperature to 450°C at a heating rate of 5°C / min and kept at that temperature for 6 hours to remove the pore-forming agent and residual solvent, resulting in porous particles with a porosity of 36.7%.

[0087] (4) The atmosphere in the fluidized bed reactor was switched to nitrogen tetrafluoride gas with a flow rate of 0.10 m / s. The fluidized bed reactor was heated to 850°C at a heating rate of 5°C / min and kept at that temperature for 6 hours to allow the fluorine-containing active body decomposed by nitrogen tetrafluoride gas to react with the porous particles. After sintering, the heating was stopped, the atmosphere was switched to nitrogen atmosphere, and the reactor was naturally cooled to room temperature to obtain fluorine oxide solid electrolyte.

[0088] (5) The fluorine oxide solid electrolyte is pulverized using an air jet mill to obtain the pulverized fluorine oxide solid electrolyte Li.1.25 La 0.58 Nb₂O₆F; wherein, the compressed air pressure during the pulverization process is 2 MPa, and the dew point of the compressed air is -30℃.

[0089] The fluoride oxide solid electrolyte Li prepared in this embodiment 1.25 La 0.58 XRD pattern of Nb2O6F, as shown Figure 2 As shown, the horizontal axis represents the diffraction angle (2-Theta, in degrees, symbol °), and the vertical axis represents the intensity of the diffraction peak (in arb.unit).

[0090] Example 2

[0091] This invention provides a fluoride oxide solid electrolyte Li 1.25 La 0.58 Ti 0.5 SbW 0.5 The preparation method of O6F specifically includes the following steps.

[0092] (1) According to the chemical formula of the fluoride oxide solid electrolyte, Li 1.25 La 0.58 Ti 0.5 SbW 0.5 To obtain the stoichiometric ratio of O6F, lithium carbonate, lanthanum trioxide, titanium dioxide, antimony pentoxide, and tungsten oxide were weighed as raw materials and placed together with polyethylene glycol and deionized water in a grinding mill. The mixture was ground at 2000 rpm for 3 hours to obtain a mixed slurry with a solid content of 30 wt%. Polyethylene glycol accounted for 15% of the raw materials.

[0093] (2) The mixed slurry is placed in a spray dryer for spray granulation. The inlet temperature of the spray dryer is 220℃ and the outlet temperature is 120℃ to obtain initial microparticles.

[0094] (3) The initial particles were placed in a fluidized bed reactor. Under an air atmosphere, the air velocity in the fluidized bed reactor was 0.20 m / s. The fluidized bed reactor was heated from room temperature to 500°C at a heating rate of 5°C / min and kept at that temperature for 5 hours to remove the pore-forming agent and residual solvent, resulting in porous particles with a porosity of 44.6%.

[0095] (4) The atmosphere in the fluidized bed reactor was switched to ammonium fluoride gas with a flow rate of 0.14 m / s. The fluidized bed reactor was heated to 850°C at a heating rate of 5°C / min and kept at that temperature for 4 hours to allow the fluorine-containing active body decomposed from the ammonium fluoride gas to react with the porous particles. After sintering, the heating was stopped, the atmosphere was switched to argon atmosphere, and the reactor was naturally cooled to room temperature to obtain fluorine oxide solid electrolyte.

[0096] (5) The fluorine oxide solid electrolyte is pulverized using an air jet mill to obtain the pulverized fluorine oxide solid electrolyte Li. 1.25 La 0.58 Ti 0.5 SbW 0.5 O6F; wherein, the compressed air pressure during the crushing process is 2MPa, and the dew point of the compressed air is -30℃.

[0097] Example 3

[0098] This invention provides a fluoride oxide solid electrolyte Li 1.2 La 0.6 The preparation method of TiWO6F specifically includes the following steps.

[0099] (1) According to the chemical formula of the fluoride oxide solid electrolyte, Li 1.2 La 0.6 The stoichiometric ratio of TiWO6F was determined by weighing lithium carbonate, lanthanum trioxide, titanium dioxide, and tungsten oxide as raw materials, and placing them together with polyvinylpyrrolidone and deionized water in a grinding mill. The mixture was ground at 2000 rpm for 4 hours to obtain a mixed slurry with a solid content of 30 wt%. Polyvinylpyrrolidone accounted for 15% of the raw materials.

[0100] (2) The mixed slurry is placed in a spray dryer for spray granulation. The inlet temperature of the spray dryer is 220℃ and the outlet temperature is 120℃ to obtain initial microparticles.

[0101] (3) The initial particles were placed in a fluidized bed reactor. Under an air atmosphere, the air velocity in the fluidized bed reactor was 0.15 m / s. The fluidized bed reactor was heated from room temperature to 500°C at a heating rate of 5°C / min and kept at that temperature for 5 hours to remove the pore-forming agent and residual solvent, resulting in porous particles with a porosity of 43.1%.

[0102] (4) The atmosphere in the fluidized bed reactor was switched to ammonium fluoride gas with a flow rate of 0.10 m / s. The fluidized bed reactor was heated to 850°C at a heating rate of 5°C / min and kept at that temperature for 6 hours to allow the fluorine-containing active body decomposed from the ammonium fluoride gas to react with the porous particles. After sintering, the heating was stopped, the atmosphere was switched to argon atmosphere, and the reactor was naturally cooled to room temperature to obtain fluorine oxide solid electrolyte.

[0103] (5) The fluorine oxide solid electrolyte is pulverized using an air jet mill to obtain the pulverized fluorine oxide solid electrolyte Li. 1.2 La 0.6 TiWO6F; wherein, the compressed air pressure during the crushing process is 1.2MPa, and the dew point of the compressed air is -30℃.

[0104] Example 4

[0105] This invention provides a fluoride oxide solid electrolyte Li 1.25 La 1.25 The preparation method of Ti2O6F specifically includes the following steps.

[0106] (1) According to the chemical formula of the fluoride oxide solid electrolyte, Li 1.25 La 1.25 To obtain Ti2O6F, lithium hydroxide, lanthanum carbonate, titanium oxide, and lithium fluoride were weighed as raw materials and placed together with polyvinylpyrrolidone and deionized water in a grinding mill. The mixture was ground at 2500 rpm for 3 hours to obtain a mixed slurry with a solid content of 20 wt%. Polyvinylpyrrolidone accounted for 10% of the raw materials.

[0107] (2) The mixed slurry is placed in a spray dryer for spray granulation. The inlet temperature of the spray dryer is 220℃ and the outlet temperature is 120℃ to obtain initial microparticles.

[0108] (3) The initial particles were placed in a fluidized bed reactor. Under an air atmosphere, the air velocity in the fluidized bed reactor was 0.20 m / s. The fluidized bed reactor was heated from room temperature to 500°C at a heating rate of 5°C / min and kept at that temperature for 5 hours to remove the pore-forming agent and residual solvent, resulting in porous particles with a porosity of 36.8%.

[0109] (4) The atmosphere in the fluidized bed reactor was switched to ammonium fluoride gas with a flow rate of 0.15 m / s. The fluidized bed reactor was heated to 850°C at a heating rate of 5°C / min and kept at that temperature for 6 hours to allow the fluorine-containing active body decomposed from the ammonium fluoride gas to react with the porous particles. After sintering, the heating was stopped, the atmosphere was switched to argon atmosphere, and the reactor was naturally cooled to room temperature to obtain fluorine oxide solid electrolyte.

[0110] (5) The fluorine oxide solid electrolyte is pulverized using an air jet mill to obtain the pulverized fluorine oxide solid electrolyte Li. 1.25 La 1.25 Ti2O6F; wherein, the compressed air pressure during the pulverization process is 1.2MPa, and the dew point of the compressed air is -30℃.

[0111] To better illustrate the effects of the embodiments of the present invention, a comparative example is provided to be made with the embodiments described above.

[0112] Comparative Example 1

[0113] This comparative example provides a method for preparing a fluorine oxide solid electrolyte. Unlike Example 1, no pore-forming agent is introduced during the preparation process. The specific preparation process is as follows.

[0114] (1) According to the chemical formula of the fluoride oxide solid electrolyte, Li 1.25 La 0.58 To determine the stoichiometric ratio of Nb₂O₆F, weigh lithium carbonate, lanthanum trioxide, and niobium pentoxide, mix them thoroughly, and obtain a mixture raw material.

[0115] (2) The mixture of raw materials is placed in a fluidized bed reactor and nitrogen tetrafluoride gas with a flow rate of 0.15 m / s is introduced. Then, the fluidized bed reactor is heated to 850°C at a heating rate of 5°C / min and kept at that temperature for 6 hours to allow the fluorine-containing active body decomposed by nitrogen tetrafluoride gas to react with the mixture of raw materials. After sintering, heating is stopped, the atmosphere is switched to nitrogen atmosphere, and the mixture is naturally cooled to room temperature to obtain fluorine oxide solid electrolyte.

[0116] (3) The fluorine oxide solid electrolyte is pulverized using an air jet mill to obtain the pulverized fluorine oxide solid electrolyte Li. 1.25 La 0.58 Nb₂O₆F; wherein, the compressed air pressure during the pulverization process is 2 MPa, and the dew point of the compressed air is -30℃.

[0117] The fluoride oxide solid electrolyte Li prepared in Comparative Example 1 1.25 La 0.58 XRD pattern of Nb2O6F, as shown Figure 2 As shown.

[0118] Comparative Example 2

[0119] This comparative example provides a method for preparing a fluorine oxide solid electrolyte. Unlike Example 1, this method does not use a fluidized bed reactor but instead performs sintering directly in a box furnace. The specific preparation process is as follows.

[0120] (1) The process of preparing the mixed slurry is the same as in Example 1.

[0121] (2) The process for preparing the initial particles is the same as in Example 1.

[0122] (3) The initial particles were placed in a box furnace and heated from room temperature to 500°C at a heating rate of 5°C / min under air atmosphere. The temperature was maintained for 5 hours to remove the pore-forming agent and residual solvent, and porous particles with a porosity of 37.3% were obtained.

[0123] (4) The atmosphere in the box furnace is switched to nitrogen tetrafluoride gas with a flow rate of 0.01 m / s. The box furnace is heated to 1000°C at a heating rate of 5°C / min and held for 6 hours to allow the fluorine-containing active body decomposed by nitrogen tetrafluoride gas to react with the porous particles. After sintering, heating is stopped, the atmosphere is switched to nitrogen atmosphere, and the furnace is naturally cooled to room temperature to obtain fluorine oxide solid electrolyte.

[0124] (5) The fluorine oxide solid electrolyte is pulverized using an air jet mill to obtain the pulverized fluorine oxide solid electrolyte Li. 1.25 La 0.58 Nb₂O₆F; wherein, the compressed air pressure during the pulverization process is 2 MPa, and the dew point of the compressed air is -30℃.

[0125] The fluoride oxide solid electrolyte Li prepared in Comparative Example 2 1.25 La 0.58 XRD pattern of Nb2O6F, as shown Figure 2 As shown.

[0126] Comparative Example 3

[0127] This comparative example provides a conventional preparation method for a fluorine oxide solid electrolyte. The difference from Example 1 is that a pore-forming agent and a fluidized bed reactor are not used. The specific preparation process is as follows.

[0128] (1) According to the chemical formula of the fluoride oxide solid electrolyte, Li 1.25 La 0.58 To determine the stoichiometric ratio of Nb₂O₆F, weigh out lithium carbonate, lanthanum trioxide, niobium pentoxide, and lithium fluoride, mix them thoroughly, and obtain a mixture raw material.

[0129] (2) The mixture of raw materials is placed in a box furnace and heated to 1000°C at a heating rate of 5°C / min under a nitrogen atmosphere and held for 6 hours. After sintering, heating is stopped, the atmosphere is switched to nitrogen atmosphere, and the mixture is naturally cooled to room temperature to obtain fluorine oxide solid electrolyte.

[0130] (3) The fluorine oxide solid electrolyte is pulverized using an air jet mill to obtain the pulverized fluorine oxide solid electrolyte Li. 1.25 La 0.58 Nb₂O₆F; wherein, the compressed air pressure during the pulverization process is 2 MPa, and the dew point of the compressed air is -30℃.

[0131] The fluoride oxide solid electrolyte Li prepared in Comparative Example 3 1.25 La 0.58 XRD pattern of Nb2O6F, as shown Figure 2 As shown.

[0132] pass Figure 2A comparison of the XRD patterns of Comparative Examples 1-3 with that of Example 1 shows that no impurity peaks appeared in the XRD of Example 1. This is because the preparation method provided in Example 1, which involves pre-forming porous microparticles, reacting them uniformly with a fluorine source, and finally pulverizing them, avoids the problem of forming a dense outer shell on the surface of the raw materials, which would lead to incomplete reaction. The preparation method provided in Example 1 improves the uniformity of the reaction, and the resulting fluoride solid electrolyte phase has no other impurity peaks and exhibits better phase characteristics.

[0133] The performance of the fluoride oxide solid electrolytes of Examples 1-4 and Comparative Examples 1-3 was tested. The specific test items and test methods are as follows.

[0134] Test 1, the test of density α, was conducted using the following method.

[0135] Sample preparation: Fluorine oxide solid electrolyte was pressed into ceramic sheets using a tablet press. The ceramic sheets were sintered at 1000℃ for 5 hours to densify them, and the resulting densified ceramic sheet samples were placed in a drying oven at 110℃ for 2 hours.

[0136] The mass W of the fluoride oxide solid electrolyte in air was measured using an analytical balance. (空气） .

[0137] The ceramic sample was placed on the sample holder, which was then connected to an analytical balance to test the sample mass. The sample holder was then placed in deionized water to obtain the mass W of the fluoride oxide solid electrolyte in the deionized water under the influence of buoyancy. (水） .

[0138] Calculate the packing density using the formula:

[0139] ρ=ρ (水) ×W (空气） / (W) (空气） -W (水） );

[0140] Packing density α = (ρ / ρ0) * 100%;

[0141] ρ is the bulk density of the fluorine oxide compound solid electrolyte ceramic sheet, expressed in grams per cubic centimeter (g / cm³). 3 );

[0142] W (空气） The mass of the fluorine oxide solid electrolyte ceramic sheet in air is expressed in grams (g).

[0143] W (水） The mass of the fluoride oxide solid electrolyte ceramic sheet in deionized water is expressed in grams (g).

[0144] ρ (水) This refers to the density of water, expressed in grams per cubic centimeter (g / cm³).3 );

[0145] ρ0 is the theoretical density of the fluorine oxide compound solid electrolyte ceramic sheet, in grams per cubic centimeter (g / cm³). 3 ).

[0146] Test 2, the test of ionic conductivity, was conducted using the following method.

[0147] Fluorine oxide solid electrolyte powder was ground evenly, pressed into ceramic sheets, and then sintered at 1000℃ for 2 hours to densify it, resulting in a densified ceramic sheet sample.

[0148] The two circular surfaces of the sintered ceramic sheet were polished smooth using 400-grit, 1000-grit, and 3000-grit sandpaper, respectively, so that the entire surface of the circular sheet was flat, clean, and free of defects.

[0149] The thickness L of the ceramic sheet is measured using a digital thickness gauge, and the diameter of the ceramic sheet is measured using a vernier caliper. The cross-sectional area of ​​the circular surface of the ceramic sheet is then calculated and denoted as S.

[0150] The surface of the polished solid electrolyte sheet sample is coated with conductive silver paste, and then the conductive silver paste on the side of the solid electrolyte sheet is polished off.

[0151] The test was conducted at a temperature of (25±2)℃ and a humidity of less than 50%. The Zahner electrochemical workstation was set with the perturbation voltage at 10mV and the frequency at 0.1 Hz to 10 Hz. 6 Hz, test impedance curve.

[0152] The resistance R was obtained by fitting and calculating using Zahner Analysis software, and the room temperature ionic conductivity of the solid electrolyte was calculated according to the ionic conductivity formula.

[0153] Formula for ionic conductivity testing: σ = L / (R*S);

[0154] In the formula: σ is the ionic conductivity of the fluorine oxide solid electrolyte ceramic sheet, in Siemens units per centimeter (S / cm).

[0155] L represents the thickness of the fluoride oxide solid electrolyte ceramic sheet, in centimeters (cm).

[0156] R is the fitted impedance value of the fluoride oxide solid electrolyte ceramic sheet, in ohms (Ω).

[0157] S represents the cross-sectional area of ​​the circular surface of the fluoride oxide solid electrolyte ceramic sheet, expressed in square centimeters (cm²). 2 ).

[0158] Test 3: Test the particle size Dv50 of the fluoride oxide solid electrolyte.

[0159] The particle size Dv50 of a material refers to its median particle size by volume, which is the median value sorted by volume. In the embodiments of this invention, the median particle size sorted by volume is specifically used, representing the particle size in a 50% volumetric slurry mixture. The particle size Dv50 is a well-known concept in the art. The particle size Dv50 of the material provided in the embodiments of this invention can be determined using instruments and conventional methods known in the art. Specifically, in the embodiments of this invention, a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd. (UK) is used to determine the particle size Dv50.

[0160] Table 1 summarizes the test data for Examples 1-4 and Comparative Examples 1-3.

[0161]

[0162] Table 1

[0163] The density test data in Table 1 show that the density of Examples 1-4 is much higher than that of Comparative Examples 1-3. This is because, in the preparation methods provided in Examples 1-4, the raw materials are granulated and shaped by grinding and spraying, and the pore-forming agent is uniformly mixed with the raw materials. In the subsequent sintering process, porous microparticles are formed. These porous microparticles undergo a solid-gas contact reaction with fluorine-containing gas. In the further sintering process, the fluorine-containing active body decomposed from the fluorine source can be uniformly distributed in the porous structure of the microparticles and react fully with the microparticles. This allows the raw materials on the surface and inside the pores of the porous microparticles to react with the fluorine-containing active body, thereby densifying them and improving the density of the final fluorine oxide solid electrolyte.

[0164] As can be seen from the comparison of ionic conductivity in Table 1, the ionic conductivity of Examples 1-4 is better than that of Comparative Examples 1-3. This is because the fluorine oxide solid electrolytes prepared in Examples 1-4 have high density, and the increase in density can improve the ion transport efficiency in the solid electrolyte, thereby improving the ionic conductivity of the solid electrolyte.

[0165] The particle size test data in Table 1 show that the fluorine oxide solid electrolytes prepared in Examples 1-4 have a better pulverization effect than those in Comparative Examples 1-3. This is because the fluorine oxide solid electrolyte blocks in Examples 1-4 have a porous structure before pulverization, and the internal connections of the porous structure are easier to break. The fluorine oxide solid electrolyte blocks prepared by Comparative Examples 1 and 3 using conventional methods do not have a porous structure, so their pulverization effect is inferior to that of Examples 1-4. Although Comparative Example 2 has a porous structure, it is sintered in a box furnace, and the material is in a static state. During the sintering process, some porous particles are in static contact, which may lead to pore blockage and structural collapse, affecting the subsequent pulverization results.

[0166] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a fluoride oxide solid electrolyte, characterized in that, The preparation method includes: According to the stoichiometric ratio of the general chemical formula for fluoride oxide solid electrolytes, lithium source material, lanthanum source material, and material containing doped elements are weighed as raw materials and placed together with pore-forming agent and solvent in a grinding mill for grinding to obtain a mixed slurry; wherein, the material containing doped elements includes one or more of the following: material containing element M1, material containing element M2, and material containing element M3; specifically, element M1 includes one or more of Zr, Ti, Hf, Si, Ge, and Sn; element M2 specifically includes one or more of Nb, Sb, Bi, V, and Ta; and element M3 specifically includes one or more of W, Cr, Mo, and Mn; The mixed slurry is spray-granulated to obtain initial microparticles; The initial microparticles are placed in a fluidized bed reactor and sintered in an air atmosphere to remove the pore-forming agent and residual solvent, thereby obtaining porous microparticles; the porous microparticles are oxide precursor particles with a porous structure. The atmosphere in the fluidized bed reactor is switched to a fluorine-containing gas for a second-stage sintering process, whereby the fluorine-containing gas and / or the fluorine-containing active substances decomposed from the fluorine-containing gas react with the porous microparticles inside and on the surface of the oxide precursor particles. After sintering, heating is stopped, the atmosphere is switched to an inert gas atmosphere, and the mixture is allowed to cool naturally to room temperature. The solid electrolyte block of fluorine oxide is then pulverized to obtain the solid electrolyte of fluorine oxide. The first sintering stage specifically includes: heating the fluidized bed reactor from room temperature to 300℃ to 500℃ at a heating rate of 1℃ / min to 8℃ / min, and holding it at that temperature for 1 hour to 8 hours; The second stage of sintering specifically includes: heating the fluidized bed reactor to 600℃ to 900℃ at a heating rate of 1℃ / min to 8℃ / min, and holding it at that temperature for 1 hour to 12 hours.

2. The preparation method according to claim 1, characterized in that, The lithium source material includes one or more of lithium carbonate, lithium hydroxide, lithium oxalate, lithium acetate, and lithium nitrate. The lanthanum source material includes one or more of the following: lanthanum trioxide, lanthanum carbonate, lanthanum nitrate, lanthanum hydroxide, and lanthanum fluoride; The chemical formula of the fluoride oxide solid electrolyte is Li x La y M1 a M2 b M3 c O6F, where x, y, a, b, and c are the molar percentages of the corresponding elements, and 1 < x + 3y < 5, 0 < x ≤ 2, 1 / 3 < y < 5 / 3, 0 ≤ a ≤ 2, 0 ≤ b ≤ 2, 0 ≤ c ≤ 2, a + b + c = 2, element M1 is a tetravalent cation, element M2 is a pentavalent cation, and element M3 is a hexavalent cation; The pore-forming agent includes one or more of polyethylene glycol, polyvinylpyrrolidone, starch, and polymethyl methacrylate; the mass of the pore-forming agent accounts for 1% to 20% of the total mass of the raw materials.

3. The preparation method according to claim 1, characterized in that, The solvent includes one or more of the following: deionized water, ethanol, NMP, isopropanol, and acetone; The grinding mill's rotation speed is set to 1000 rpm to 3000 rpm, and the grinding process takes 1 hour to 6 hours. The solid content of the mixed slurry is 10wt% to 45wt%. The equipment for spray granulation is a spray dryer; the inlet temperature of the spray dryer is 180℃~240℃, and the outlet temperature is 60℃~120℃.

4. The preparation method according to claim 1, characterized in that, The air velocity in the fluidized bed reactor is 0.01 m / s to 1 m / s; The porosity of the porous microparticles is 30% to 50%.

5. The preparation method according to claim 1, characterized in that, The fluorine-containing gas includes one or more of nitrogen tetrafluoride, nitrogen trifluoride, hydrogen fluoride vapor, polytetrafluoroethylene, and ammonium fluoride; the flow rate of the fluorine-containing gas in the fluidized bed reactor is 0.01 m / s to 1 m / s; The inert gas atmosphere includes one or more of nitrogen, argon, and helium; the flow rate of the inert gas atmosphere in the fluidized bed reactor is 0.01 m / s to 1 m / s.

6. The preparation method according to claim 1, characterized in that, The equipment used for the pulverization process is a fluidized bed jet mill or a flat jet mill; The pressure of the compressed air during the pulverization process is between 0.5 MPa and 3 MPa, and the dew point of the compressed air is less than -20°C.

7. A fluorine oxide solid electrolyte prepared by any one of the preparation methods according to claims 1-6, characterized in that, The chemical formula of the fluoride oxide solid electrolyte is Li x La y M1 a M2 b M3 c O6F, where x, y, a, b, and c are the molar percentages of the corresponding elements, and 1 < x + 3y < 5, 0 < x ≤ 2, 1 / 3 < y < 5 / 3, 0 ≤ a ≤ 2, 0 ≤ b ≤ 2, 0 ≤ c ≤ 2, a + b + c = 2, element M1 is a tetravalent cation, element M2 is a pentavalent cation, and element M3 is a hexavalent cation; The particle size Dv50 of the fluorine oxide solid electrolyte is 200 nm to 2.0 μm; The density of the fluoride solid electrolyte is greater than 90%. The ionic conductivity of the fluorine oxide solid electrolyte is greater than 6 mS / cm.

8. A lithium battery, characterized in that, The lithium battery includes a fluorine oxide solid electrolyte prepared by any of the preparation methods described in claims 1-6, or a fluorine oxide solid electrolyte as described in any of claims 7.

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