Preparation method of spherical nano solid-state electrolyte ceramic powder, solid-state electrolyte and solid-state battery

Abstract

The invention discloses a preparation method of spherical nano solid-state electrolyte ceramic powder, a solid-state electrolyte and a solid-state battery, and belongs to the technical field of new energy. The preparation method comprises the following steps: mixing an oil phase and a surfactant to obtain a mixed solution; adding a precursor aqueous solution into the mixed solution to obtain a reverse microemulsion; wherein the precursor aqueous solution comprises hydrates of other metal elements except the lithium element in the solid electrolyte; adding a precipitator into the microemulsion, and separating out precursor powder; and calcining the mixed powder obtained by mixing the precursor powder and a lithium source to obtain the spherical nano solid electrolyte ceramic powder. The solid electrolyte ceramic powder prepared by the method has smaller particle size and higher sphericity degree, the subsequent calcination temperature is obviously reduced compared with that of a traditional solid phase method, and the spherical nano solid electrolyte ceramic powder with excellent performance is obtained while the energy consumption is reduced.

Description

Technical Field

[0001] This application relates to the field of new energy technology, and in particular to a method for preparing spherical nano-solid electrolyte ceramic powder, a solid electrolyte, and a solid battery. Background Technology

[0002] Solid-state electrolytes possess high mechanical strength, excellent density, and a certain ability to resist lithium dendrite growth. They also lack the volatile, flammable, and explosive properties of liquid organic electrolytes, making them a core component of next-generation battery technology due to their high safety and high performance. Solid-state electrolyte materials mainly include three categories: inorganic ceramic solid-state electrolytes, organic polymer solid-state electrolytes, and inorganic ceramic / polymer composite solid-state electrolytes. For the preparation of ceramic powders for inorganic ceramic solid-state electrolytes, ensuring high purity, good chemical homogeneity, fine and uniform particle size, regular particle sphericity, and good dispersibility is crucial to guaranteeing their excellent performance. Generally, the most ideal shape for ceramic particles is spherical, due to their advantages such as good flowability and high packing density. This promotes uniform grain growth and eliminates pores, facilitating densification during molding and sintering, ultimately improving product performance. Therefore, in the preparation of fine ceramic powders, spherical powder particles are often preferred. Furthermore, nanostructures have a positive impact on the thermal and fracture properties of ceramic materials. Generally, the thermal conductivity of a material is affected by defects and grain boundaries. Powders with smaller average particle sizes have more grain boundaries, resulting in stronger phonon scattering and correspondingly lower thermal conductivity. Numerous grain boundaries in nanomaterials can effectively delay crack propagation and improve fracture toughness. Furthermore, nanoparticles have a high specific surface area, which can significantly reduce the activation energy of chemical reactions, allowing them to sinter at lower temperatures and reduce energy consumption.

[0003] Currently, the main methods for preparing inorganic ceramic solid electrolyte powders include solid-phase method, self-propagating method, co-precipitation method, hydrothermal method, sol-gel method, etc. However, the products obtained by the above methods are usually uneven in composition and have poor reproducibility, and the powder particles exhibit various irregular morphologies. In addition, preparation methods such as solid-phase method require high calcination temperature to form a pure phase in the subsequent phase formation, which increases energy consumption, and the particle size of the obtained powder is mostly in the micrometer range.

[0004] Therefore, there is an urgent need to provide a method for preparing nanoscale ceramic solid electrolyte powder with high sphericity. Summary of the Invention

[0005] In view of this, this application provides a method for preparing spherical nano solid electrolyte ceramic powder, a solid electrolyte, and a solid battery, aiming to improve the problems of large particle size, irregular morphology, or uneven distribution of inorganic ceramic solid electrolyte powder prepared by existing methods.

[0006] In a first aspect, embodiments of this application provide a method for preparing spherical nano-solid electrolyte ceramic powder, the preparation method comprising the following steps: An oil phase, a surfactant, and a co-surfactant are mixed to obtain a mixed solution; wherein, by mass, the ratio of the oil phase: the surfactant: the co-surfactant in the mixed solution is (2~5):(1~2):(1~2); A precursor aqueous solution is added to the mixed solution to obtain a reverse microemulsion; wherein, the precursor aqueous solution includes hydrates of other metal elements besides lithium in the solid electrolyte ceramic powder to be prepared; the mass ratio of the oil phase to the precursor aqueous solution is (10~20):1; A precipitant is added to the microemulsion, and the precursor powder is separated. The precursor powder and the lithium source were mixed and calcined to obtain spherical nano solid electrolyte ceramic powder.

[0007] In some embodiments of this application, the oil phase includes at least one of cyclohexane, n-heptane, isooctane, and n-hexane.

[0008] In some embodiments of this application, the surfactant includes at least one of polyethylene glycol octylphenyl ether, hexadecyltrimethylammonium bromide, or polyoxyethylene sorbitan monostearate.

[0009] In some embodiments of this application, the co-surfactant includes alcohol solvents.

[0010] In some embodiments of this application, the cation concentration in the precursor aqueous solution is 0.8~2 mol / L; And / or, the precipitant includes ammonia.

[0011] In some embodiments of this application, the solid electrolyte includes at least one of LLTO-type solid electrolyte, NASICON-type solid electrolyte, LISICON-type solid electrolyte, and LATP solid electrolyte.

[0012] In some embodiments of this application, the solid electrolyte includes the element La, and the hydrate of La includes La(NO3)3·6H2O; And / or, the solid electrolyte includes Zr element, and the Zr hydrate includes at least one of ZrO(NO3)2·xH2O or ZrOCl2·8H2O; And / or, the solid electrolyte includes Al, and the hydrate of Al includes Al(NO3)3·9H2O; And / or, the lithium source includes at least one of Li2CO3 and LiOH·H2O; And / or, the step of mixing the solid particles with the lithium source includes mixing the precursor powder and the lithium source using a ball milling process.

[0013] In some embodiments of this application, the calcination temperature is 600~700℃; And / or, the calcination time is 6 to 12 hours.

[0014] A second aspect of this application provides a solid electrolyte, which is prepared by the aforementioned preparation method.

[0015] A third aspect of this application provides a solid-state battery, the solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte.

[0016] Beneficial effects: This application employs a reverse microemulsion method to prepare spherical nano-solid electrolyte ceramic powder. An immiscible oil phase and an aqueous precursor solution of the ceramic solid electrolyte are mixed under the action of a surfactant to form a water-in-oil (W / O) microemulsion. The ratio of the oil phase:surfactant:co-surfactant in the mixed solution is (2-5):(1-2):(1-2), and the mass ratio of the oil phase to the aqueous precursor solution is (10-20):1. The reactants are confined within independent spherical microemulsion droplets for reaction, nucleation, and growth, ultimately forming uniform and fine spherical nanoparticles. This preparation method ensures that the water nuclei in the oil phase are of essentially uniform size, resulting in ceramic nanoparticles with controllable morphology and particle size. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0018] Figure 1 This is a powder scanning electron microscope image of the precursor powder prepared in Example 1 of this application after drying.

[0019] Figure 2 This is a scanning electron microscope image of the spherical nano-solid electrolyte ceramic powder prepared in Example 1.

[0020] Figure 3 This is the XRD pattern of the spherical nano-solid electrolyte ceramic powder prepared in Example 1.

[0021] Figure 4 This is a scanning electron microscope image of the spherical nano-solid electrolyte ceramic powder prepared in Example 2.

[0022] Figure 5 This is a scanning electron microscope image of the spherical nano-solid electrolyte ceramic powder prepared in Example 3.

[0023] Figure 6 This is a scanning electron microscope image of the spherical nano-solid electrolyte ceramic powder prepared in Example 4.

[0024] Figure 7 This is a scanning electron microscope image of the solid electrolyte ceramic powder prepared in Comparative Example 7. Detailed Implementation

[0025] The experimental examples described in this application are merely some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this application.

[0026] 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 invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] In the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are used merely as illustrative purposes and do not impose numerical requirements or establish an order.

[0028] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0029] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0030] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0031] Solid-state electrolytes possess high mechanical strength, excellent density, and a certain ability to resist lithium dendrite growth. They also lack the volatile, flammable, and explosive properties of liquid organic electrolytes, making them a core component of next-generation battery technology due to their high safety and high performance. Solid-state electrolyte materials mainly include three categories: inorganic ceramic solid-state electrolytes, organic polymer solid-state electrolytes, and inorganic ceramic / polymer composite solid-state electrolytes. For the preparation of ceramic powders for inorganic ceramic solid-state electrolytes, ensuring high purity, good chemical homogeneity, fine and uniform particle size, regular particle sphericity, and good dispersibility is crucial to guaranteeing their excellent performance. Generally, the most ideal shape for ceramic particles is spherical, due to their advantages such as good flowability and high packing density. This promotes uniform grain growth and eliminates pores, facilitating densification during molding and sintering, ultimately improving product performance. Therefore, in the preparation of fine ceramic powders, spherical powder particles are often preferred. Furthermore, nanostructures have a positive impact on the thermal and fracture properties of ceramic materials. Generally, the thermal conductivity of a material is affected by defects and grain boundaries. Powders with smaller average particle sizes have more grain boundaries, resulting in stronger phonon scattering and correspondingly lower thermal conductivity. Numerous grain boundaries in nanomaterials can effectively delay crack propagation and improve fracture toughness. Furthermore, nanoparticles have a high specific surface area, which can significantly reduce the activation energy of chemical reactions, allowing them to sinter at lower temperatures and reduce energy consumption.

[0032] Currently, the main methods for preparing inorganic ceramic solid electrolyte powders include solid-phase method, self-propagating method, co-precipitation method, hydrothermal method, sol-gel method, etc. However, the products obtained by the above methods are usually uneven in composition and have poor reproducibility, and the powder particles exhibit various irregular morphologies. In addition, preparation methods such as solid-phase method require high calcination temperature to form a pure phase in the subsequent phase formation, which increases energy consumption, and the particle size of the obtained powder is mostly in the micrometer range.

[0033] Therefore, there is an urgent need to provide a method for preparing inorganic ceramic solid electrolyte powder to improve the problems of large particle size, irregular morphology, or uneven distribution of inorganic ceramic solid electrolyte powder prepared by existing methods.

[0034] Therefore, this application provides a method for preparing spherical nano-solid electrolyte ceramic powder using a reverse microemulsion method, the method comprising the following steps: S100 Mixing an oil phase, a surfactant, and a co-surfactant to obtain a mixed solution; wherein, by mass, the ratio of the oil phase: the surfactant: the co-surfactant in the mixed solution is (2~5):(1~2):(1~2).

[0035] S200 Add the precursor aqueous solution to the mixed solution to obtain a reverse microemulsion; wherein, the precursor aqueous solution includes hydrates of other metal elements besides lithium in the solid electrolyte ceramic powder to be prepared; the mass ratio of the oil phase to the precursor aqueous solution is (10~20):1.

[0036] S300 Add a precipitant to the reverse microemulsion and then separate the precursor powder.

[0037] S400 The precursor powder and the lithium source are mixed and then calcined to obtain spherical nano solid electrolyte ceramic powder.

[0038] This application employs a reverse microemulsion method to prepare spherical nano-solid electrolyte ceramic powder. An immiscible oil phase and an aqueous solution of the ceramic solid electrolyte precursor are mixed in a water-in-oil (W / O) microemulsion under the action of a surfactant. The ratio of the oil phase:surfactant:co-surfactant in the mixed solution is (2-5):(1-2):(1-2). The reactants are confined within their own independent spherical microemulsion droplets for reaction, nucleation, and growth, ultimately forming uniform and fine spherical nanoparticles. This preparation method ensures that the water nuclei in the oil phase are of essentially uniform size, resulting in ceramic nanoparticles with controllable morphology and particle size.

[0039] It is important to emphasize that, taking the solid electrolyte lithium lanthanum zirconium oxide (LLZO) as an example, the inventors discovered through repeated experiments that adding a lithium source (e.g., LiOH·H2O) to the precursor aqueous solution in step S200 prevents the synthesis of pure-phase LLZO. To solve this problem, the inventors, through continuous exploration and experimentation, innovatively discovered that by preparing a lithium-free precursor powder, then mixing it with a lithium source (e.g., ball milling and blending the precursor powder and the lithium source) to obtain a mixed powder, and then calcining the mixed powder, the solid electrolyte lithium lanthanum zirconium oxide can be prepared. Furthermore, since the lithium-free precursor powder prepared by the method in this application is in nanoscale particles, the activation energy of the reaction is reduced, thus significantly lowering the subsequent calcination temperature compared to the traditional solid-state method. This reduces energy consumption while obtaining high-performance spherical nano-solid electrolyte ceramic powder.

[0040] In some embodiments of this application, the oil phase in step S100 includes at least one of cyclohexane, n-heptane, isooctane, and n-hexane.

[0041] In some embodiments of this application, the surfactant in step S100 includes at least one of polyethylene glycol octylphenyl ether (Trition X-100-100), hexadecyltrimethylammonium bromide (CTAB), or polyoxyethylene sorbitan monostearate (Tween 60).

[0042] In some embodiments of this application, step S200, adding the precursor aqueous solution to the mixed solution, includes: adding the precursor aqueous solution dropwise to the mixed solution under stirring conditions. Further, the stirring time is 0.5~2 hours.

[0043] In some embodiments of this application, in step S200, the cation concentration in the precursor aqueous solution is 0.8~2 mol / L. Exemplarily, the cation concentration in the precursor aqueous solution is 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2.0 mol / L, or any two of the above values. It should be noted that if the cation concentration in the precursor aqueous solution is too high, for example, exceeding 2 mol / L, it is difficult to form a reverse microemulsion, and the probability of collisions between droplets in the reverse microemulsion increases, easily leading to uneven particle size of the prepared product. If the cation concentration in the precursor aqueous solution is too low, for example, below 0.8 mol / L, the cations in the precursor aqueous solution are mainly used for grain growth, reducing the nucleation probability, resulting in a larger product particle size and lower yield.

[0044] In some embodiments of this application, the solid electrolyte includes LLTO (perovskite) solid electrolytes (e.g., lithium lanthanum titanium oxide / lithium lanthanum titanate), NASICON-type solid electrolytes (e.g., lithium titanium aluminum phosphate), and LISICON-type solid electrolytes (e.g., Li...). 10 GeP2S 12 At least one of the following.

[0045] In some embodiments of this application, the solid electrolyte is an oxide solid electrolyte, with Li 6.4 Al 0.2 La3Zr2O 12 For example, in step S200, adding the precursor aqueous solution to the mixed solution involves weighing hydrates containing La, Zr, and Al elements according to the molar fraction of the oxide solid electrolyte to prepare the precursor aqueous solution. That is, the precursor aqueous solution in step S200 includes hydrates containing La, Zr, and Al.

[0046] In some embodiments of this application, in step S200, the solid electrolyte includes the element La, and the hydrate of La includes La(NO3)3·6H2O.

[0047] In some embodiments of this application, in step S200, the solid electrolyte includes Zr element, and the Zr hydrate includes at least one of ZrO(NO3)2·xH2O or ZrOCl2·8H2O.

[0048] In some embodiments of this application, in step S200, the solid electrolyte includes Al element, and the Al hydrate includes Al(NO3)3·9H2O.

[0049] In some embodiments of this application, the co-surfactant includes an alcohol solvent. Exemplarily, the alcohol solvent includes at least one selected from n-butanol, n-hexanol, n-pentanol, and n-octanol.

[0050] In some embodiments of this application, the precipitant in step S300 can be ammonia. For example, the concentration of ammonia is 0.05 mol / L, and the amount of ammonia added is 2 ml to 10 ml.

[0051] In some embodiments of this application, step S300, before separating the precursor powder and after adding the precipitant, further includes ultrasonic treatment of the reverse microemulsion for a period of time. It should be noted that ultrasonic treatment mainly aims to fully disperse the droplets, which is beneficial for improving the stability of the microemulsion. It is important to note that the ultrasonic treatment time should not be too long, as excessively long ultrasonic treatment will lead to a sharp increase in temperature, ultimately destroying the microemulsion structure.

[0052] In some embodiments of this application, step S300, the step of separating the precursor powder, includes centrifuging the ultrasonicated microemulsion with anhydrous ethanol, exemplaryly, separating and washing the precipitate at least three times, and then drying to obtain the precursor powder. Exemplarily, the washed precipitate is dried in an 80°C oven to obtain dried precursor powder.

[0053] In some embodiments of this application, step S400, mixing the solid particles with the lithium source, includes weighing the dried powder and the lithium source according to a stoichiometric ratio and ball-milling them until uniform. Exemplarily, the ball-milling time is 8-12 hours.

[0054] In some embodiments of this application, in step S400, the Li element in the Li source is in excess by 10% to 15% according to the stoichiometric ratio of the solid electrolyte.

[0055] In some embodiments of this application, in step S400, the lithium source includes at least one of Li2CO3 and LiOH·H2O.

[0056] In some embodiments of this application, step S400, calcining the mixed powder, includes calcining the mixed powder in a muffle furnace to obtain spherical nano-solid electrolyte ceramic powder. Exemplarily, the calcination temperature is 600-700°C, and the calcination time is 6-12 hours.

[0057] Example 1 Weigh 20g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300rpm for 30min to prepare mixture A1. Simultaneously, prepare a 0.8mol / L nitrate aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al according to the stoichiometric ratio. Add 1.5g of solution B1 (the mass ratio of oil phase to solution B1 is approximately 13.3:1) dropwise to mixture A1. Mix and stir at 300rpm for 1h at room temperature to obtain a reverse microemulsion. Add 2ml of ammonia (precipitant) to the prepared reverse microemulsion and sonicate for 0.5h. Then, centrifuge the reverse microemulsion with ammonia at 4500rpm to obtain a precipitate. Wash the precipitate three times with anhydrous ethanol by centrifugation. Dry the washed precipitate in a forced-air drying oven at 80℃ for 3h to obtain precursor powder. The scanning electron microscope image is shown below. Figure 1 As shown, the powder particles are extremely fine, with a particle size of about tens of nanometers, and the powder shape can be roughly seen to be spherical. An excess of 10% Li₂CO₃ was weighed and ball-milled with the precursor powder for 12 hours to mix evenly. Subsequently, it was calcined at 600℃ for 12 hours to obtain the final solid electrolyte powder. Its scanning electron microscope image is shown below. Figure 2 As shown, the XRD diffraction pattern is as follows: Figure 3 As shown. By Figure 2It can be seen that the calcined powder grows slightly, but the particle size is around 200 nm, and the spherical morphology remains relatively intact. Figure 3 To ensure the successful preparation of LLZO garnet pure phase powder, an appropriate amount of powder was finally pressed and sintered (sintering temperature 1200℃; time 10min), and lithium was attached to both sides to assemble a symmetrical cell for critical current density testing.

[0058] Example 2 The difference between this example and Example 1 lies in the different amounts of cyclohexane and precursor aqueous solution added during the preparation of the reverse microemulsion, as detailed below: Weigh 50g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L, according to the stoichiometric ratio. Add 3.5g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 14.3:1). Mix and stir at 300 rpm for 1 h at room temperature to obtain a reverse microemulsion. The scanning electron microscope image of the prepared precursor powder is shown below. Figure 4 As shown.

[0059] Example 3 The difference between this example and Example 1 lies in the different amounts of cyclohexane and precursor aqueous solution added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L, according to the stoichiometric ratio. Add 3g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 11.7:1). Mix and stir at 300 rpm for 1 h at room temperature to obtain a reverse microemulsion. The scanning electron microscope image of the prepared precursor powder is shown below. Figure 5 As shown.

[0060] Example 4 The difference between this and Example 3 lies in the type of Tritium X-100 (surfactant) added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 10g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L, according to the stoichiometric ratio. Add 3g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 11.7:1). Mix and stir at 300 rpm for 1 h at room temperature to obtain a reverse microemulsion. The scanning electron microscope image of the prepared precursor powder is shown below. Figure 6 As shown.

[0061] Example 5 The difference between this and Example 3 lies in the type of Tritium X-100 (surfactant) added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 20g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 3g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 11.7:1). Mix and stir at 300 rpm for 1 h at room temperature to obtain a reverse microemulsion.

[0062] Example 6 The difference between this example and Example 3 lies in the type of n-butanol (co-surfactant) added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 10g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 3g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 11.7:1). Mix and stir at 300 rpm for 1 h at room temperature to obtain a reverse microemulsion.

[0063] Example 7 The difference between this example and Example 3 lies in the type of n-butanol (co-surfactant) added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 20g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 3g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 11.7:1). Mix and stir at 300 rpm for 1 h at room temperature to obtain a reverse microemulsion.

[0064] Example 8 The difference between this example and Example 3 lies in the different amounts of precursor aqueous solution added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 3.5g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 10:1). Mix and stir at 300 rpm for 1 h at room temperature to obtain a reverse microemulsion.

[0065] Example 9 The difference between this example and Example 3 lies in the different amounts of precursor aqueous solution added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 1.75g ​​of solution B1 (the mass ratio of oil phase to solution B1 is approximately 20:1) dropwise to mixture A1. Mix and stir at 300 rpm for 1 h at room temperature to obtain a reverse microemulsion.

[0066] Comparative Example 1 The difference between this example and Example 1 lies in the mass of cyclohexane (oil phase) added during the preparation of the reverse microemulsion, as detailed below: Weigh 10g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300rpm for 30min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8mol / L according to the stoichiometric ratio. Add 1.5g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 6.7:1). After mixing and stirring at 300rpm for 1h at room temperature, a reverse microemulsion cannot be obtained.

[0067] Comparative Example 2 The difference between this example and Example 3 lies in the mass of Tritium X-100 (surfactant) added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 5g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 3g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 11.7:1). After mixing and stirring at 300 rpm for 1 h at room temperature, a reverse microemulsion cannot be obtained.

[0068] Comparative Example 3 The difference between this example and Example 3 lies in the mass of Tritium X-100 (surfactant) added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 30g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 3g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 11.7:1). After mixing and stirring at 300 rpm for 1 h at room temperature, a reverse microemulsion cannot be obtained.

[0069] Comparative Example 4 The difference between this example and Example 3 lies in the mass of n-butanol (co-surfactant) added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 5g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 3g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 11.7:1). After mixing and stirring at 300 rpm for 1 h at room temperature, a reverse microemulsion cannot be obtained.

[0070] Comparative Example 5 The difference between this example and Example 3 lies in the mass of the precursor aqueous solution added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 1g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 35:1). After mixing and stirring at 300 rpm for 1 h at room temperature, a reverse microemulsion cannot be obtained.

[0071] Comparative Example 6 The difference between this example and Example 3 lies in the mass of the precursor aqueous solution added during the preparation of the reverse microemulsion, as detailed below: Weigh 35g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300 rpm for 30 min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution) containing La, Zr, and Al with a cation concentration of 0.8 mol / L according to the stoichiometric ratio. Add 4g of solution B1 dropwise to mixture A1 (the mass ratio of oil phase to solution B1 is approximately 8.75:1). After mixing and stirring at 300 rpm for 1 h at room temperature, a reverse microemulsion cannot be obtained.

[0072] Comparative Example 7 The difference between this and the previous example is that the lithium source is directly added to the precursor aqueous solution, and no lithium source is added during the ball milling stage.

[0073] Weigh 20g of cyclohexane (oil phase), 15g of Tritium X-100 (surfactant), and 15g of n-butanol (co-surfactant). Mix them thoroughly at 300rpm for 30min to prepare mixture A1. Simultaneously, prepare an aqueous solution B1 (precursor aqueous solution, with a 10% excess Li source) containing La, Zr, Al nitrates and LiOH at a stoichiometric concentration of 0.8mol / L. Figure 7 As shown.

[0074] Experimental Test This experiment used a JSM IT210 scanning electron microscope manufactured by JEOL Corporation of Japan to observe the microstructure, with an accelerating voltage of 10 kV.

[0075] Particle size was measured using an Omec laser particle size analyzer. The sample had a refractive index of 1.4 and an absorbance of 0.1. XRD tests were performed using a Rigaku Miniflex diffractometer from Rigaku Corporation of Japan, with a scanning angle of 10°–60° and a scanning speed of 10° / min.

[0076] Electrolyte conductivity was tested using an Autolab electrochemical workstation. A blocking electrode was constructed by sputtering gold onto both sides, and the electrolyte sheet was directly placed on a clip for testing. The testing frequency ranged from 0.01 to 1,000,000 Hz.

[0077] The critical current density was tested using a blue-chip device. The specific procedure involved assembling a lithium-ion symmetric battery, starting from 0.1 mA / cm². 2 Start at 0.1 mA / cm 2 The current density gradually increases until the battery voltage drops sharply, which is the current density at which the CCD is reached.

[0078] The conductivity of electrolyte sheets prepared by pressing and sintering the solid electrolyte powders of each embodiment and comparative example was tested, and the conductivity values ​​are shown in Table 1.

[0079] Table 1

[0080] In Examples 1-9, the mass ratio of oil phase, surfactant, and co-surfactant satisfies (2-5):(1-2):(1-2), and the mass ratio of oil phase to precursor aqueous solution is (10-20):1, thus obtaining a uniform and stable microemulsion. Figures 1 to 6As shown in Table 1, the ceramic powder particles prepared by this method have a narrow and relatively uniform particle size distribution, ranging from 100 to 220 nm, with no large micron-sized particles. However, for Comparative Examples 1-6, since the proportion of one of the phases exceeded the specified range, stable and transparent microemulsions could not be obtained. The resulting solutions were turbid and uneven, which contradicted the property of clear and transparent microemulsions. Therefore, no further characterization was performed.

[0081] The difference between Example 1 and Comparative Example 7 is that the precursor aqueous solution in Example 1 does not include a lithium source; the precursor powder is prepared and then mixed with a lithium source for calcination. In contrast, the precursor aqueous solution in Comparative Example 7 also includes a lithium source. Figure 7 It can be seen that the powder XRD phase prepared by preparing a precursor aqueous solution with lithium source and other elements is La2Z2O7, indicating that lithium did not precipitate and could not form LLZO.

[0082] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing spherical nano-solid electrolyte ceramic powder, characterized in that, The preparation method includes the following steps: An oil phase, a surfactant, and a co-surfactant are mixed to obtain a mixed solution; wherein, by mass, the ratio of the oil phase: the surfactant: the co-surfactant in the mixed solution is (2~5):(1~2):(1~2); A precursor aqueous solution is added to the mixed solution to obtain a reverse microemulsion; wherein, the precursor aqueous solution includes hydrates of other metal elements besides lithium in the solid electrolyte ceramic powder to be prepared; the mass ratio of the oil phase to the precursor aqueous solution is (10~20):1; A precipitant is added to the microemulsion, and the precursor powder is separated. The precursor powder and the lithium source were mixed and calcined to obtain spherical nano solid electrolyte ceramic powder.

2. The preparation method according to claim 1, characterized in that, The oil phase includes at least one of cyclohexane, n-heptane, isooctane, and n-hexane.

3. The preparation method according to claim 1, characterized in that, The surfactant includes at least one of polyethylene glycol octylphenyl ether, hexadecyltrimethylammonium bromide, or polyoxyethylene sorbitan monostearate.

4. The preparation method according to claim 1, characterized in that, The co-surfactant includes alcohol solvents.

5. The preparation method according to claim 1, characterized in that, The cation concentration in the precursor aqueous solution is 0.8 mol / L to 2 mol / L; And / or, the precipitant includes ammonia.

6. The preparation method according to claim 1, characterized in that, The solid electrolyte includes at least one of LLTO type solid electrolyte, NASICON type solid electrolyte, LISICON type solid electrolyte, and LATP solid electrolyte.

7. The preparation method according to claim 1, characterized in that, The solid electrolyte includes the element La, and the hydrate of La includes La(NO3)3·6H2O; And / or, the solid electrolyte includes Zr element, and the Zr hydrate includes at least one of ZrO(NO3)2·xH2O or ZrOCl2·8H2O; And / or, the solid electrolyte includes Al, and the hydrate of Al includes Al(NO3)3·9H2O; And / or, the lithium source includes at least one of Li2CO3 and LiOH·H2O; And / or, the step of mixing the solid particles with the lithium source includes mixing the precursor powder and the lithium source using a ball milling process.

8. The preparation method according to claim 1, characterized in that, The calcination temperature is 600~700℃; And / or, the calcination time is 6 to 12 hours.

9. A solid electrolyte, characterized in that, The solid electrolyte comprises spherical nano-solid electrolyte ceramic powder prepared by the preparation method according to any one of claims 1 to 8.

10. A solid-state battery, characterized in that, The solid-state battery includes a positive electrode, a negative electrode, and the solid electrolyte as described in claim 9.

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