Solid electrolyte material, preparation method thereof and solid-state battery

Abstract

The invention provides a solid electrolyte material, a preparation method thereof and a solid-state battery, the solid electrolyte material comprises electrolyte powder, and the electrolyte powder is spherical and / or sphere-like; the average particle size of the electrolyte powder is 40 nm to 200 nm; the morphology of the electrolyte powder is spherical and / or sphere-like, and the particle size of the solid electrolyte material is nanoscale, so that the solid electrolyte material can form a stable cubic phase LLZO, the ionic conductivity of the solid electrolyte is improved, and the technical problem that the ionic conductivity is reduced due to doping of metal elements is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a solid electrolyte material, a preparation method thereof, and a solid battery. Background Art

[0002] Lithium lanthanum zirconium oxide (LLZO) with a garnet structure is a key component of current oxide solid electrolytes. LLZO is divided into two types: tetragonal phase and cubic phase. Among them, cubic-phase LLZO (c-LLZO) has high ionic conductivity, a wide electrochemical window, acid-base stability, and high lithium stability.

[0003] In related technologies, doping specific metal elements into LLZO can significantly improve the room-temperature stability of cubic-phase LLZO, and the lithium vacancies formed after doping can effectively improve the lithium-ion transport channels, thereby significantly improving the ionic conductivity of cubic-phase LLZO.

[0004] However, for solid electrolytes doped with specific metal elements, the doped metal elements may affect the growth of grains in the solid electrolyte, increase the particle size of the solid electrolyte powder, and thus affect the ionic conductivity of the solid electrolyte. Summary of the Invention

[0005] Embodiments of the present invention provide a solid electrolyte material, a preparation method thereof, and a solid battery, which can solve the technical problem that the ionic conductivity of the solid electrolyte is affected by doping metal elements.

[0006] In a first aspect, embodiments of the present invention provide a solid electrolyte material, the solid electrolyte material including electrolyte powder, the electrolyte powder being spherical and / or quasi-spherical; and / or The average particle size of the electrolyte powder is 40 nm to 200 nm.

[0007] In one embodiment, the average particle size of the electrolyte powder is 70 nm to 120 nm.

[0008] In one embodiment, the solid electrolyte material includes a substance with the following chemical formula: Li a La3Zr b M c O 12 ; wherein, M is any one of doped metals Al, Ta, Ti, and Ga; The value of a is greater than or equal to 5 and less than or equal to 7; The value of b is greater than or equal to 1.2 and less than or equal to 2; The value of c is greater than or equal to 0.1 and less than or equal to 0.7.

[0009] In one embodiment, if the valence state of M is k, then a, b, c, and k satisfy a + 4b + kc = 15.

[0010] In one embodiment, M is Al; The solid electrolyte material includes a substance with the following chemical formula: Li 7-3c La3Zr2Al c O 12 , where the value range of c is from 0.2 to 0.4.

[0011] In one embodiment, M is Ti; The solid electrolyte material includes a substance with the following chemical formula: Li7La3Zr 2-c Ti c O 12 , where the value range of c is from 0.5 to 0.7.

[0012] In one embodiment, M is Ta; The solid electrolyte material includes a substance with the following chemical formula: Li 7-c La3Zr 2-c Ta c O 12 , where the value range of c is from 0.3 to 0.7.

[0013] In one embodiment, the conductivity of the solid electrolyte material at 25 °C is 0.62×10 -3 ~1.24×10 -3 .

[0014] In a second aspect, an embodiment of the present invention provides a method for preparing a solid electrolyte material, including the following steps: Provide lanthanum salts, zirconium salts, lithium salts, and doped metal salts; Dissolve the lanthanum salts, zirconium salts, and doped metal salts in a first solvent to obtain a first mixed solution; Perform gasification treatment on the first mixed solution to obtain an LZO precursor; Wet-mix the LZO precursor with the lithium salts and dry to obtain an LLZO precursor; Perform solid-phase sintering on the LLZO precursor in the temperature range of 400 °C to 600 °C to obtain the solid electrolyte material as described above.

[0015] In one embodiment, the lanthanum salts include at least one of lanthanum acetate, lanthanum isobutyrate, lanthanum propanolate, lanthanum isopropanolate, lanthanum oxalate, lanthanum phosphate, lanthanum triacetate, lanthanum terephthalate; and / or The zirconium salt includes at least one of zirconium acetate, zirconium butyrate, zirconium isobutyrate, zirconium propoxide, zirconium isopropoxide, and zirconium benzoate; and / or The lithium salt includes any one of lithium hydroxide and lithium carbonate; and / or The first solvent includes one or a combination of propionic acid, ethanol, isopropanol, and isooctanoic acid; The doped metal salt includes any one of aluminum salts, tantalum salts, gallium salts, and titanium salts.

[0016] In one embodiment, before the gasification treatment of the first mixture, the following steps are further included: Stir the first mixture, and perform gasification treatment after stirring until it is completely dissolved and clarified; and / or The gasification treatment includes any one of spray pyrolysis, spray drying, and flame spray pyrolysis.

[0017] In a third aspect, an embodiment of the present invention provides a solid-state battery, including the aforementioned solid electrolyte material or the solid electrolyte material prepared by the aforementioned preparation method of the solid electrolyte material.

[0018] Advantages of the embodiments of the present invention: In the embodiments of the present invention, since the solid electrolyte material includes electrolyte powder, the morphology of the electrolyte powder is spherical and / or quasi-spherical, and the average particle size of the electrolyte powder is in the nanometer range, which is beneficial to the formation of a stable cubic phase LLZO, helps to improve the ionic conductivity of the solid electrolyte material, and thus solves the technical problem of reducing the ionic conductivity due to the doping of metal elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 is a transmission electron microscope image of the solid electrolyte material provided by the embodiment of the present invention; Figure 2 is a scanning electron microscope image of the solid electrolyte material provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention. In addition, it should be understood that the specific implementation manners described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise stated, the orientation words such as "upper" and "lower" usually refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the accompanying drawings; and "inner" and "outer" refer to the outline of the device.

[0022] In the related art, doping a specific metal element in LLZO can significantly improve the room temperature stability of cubic LLZO, and the lithium vacancies formed after doping can effectively improve the lithium ion transport channels, thereby significantly improving the ionic conductivity of cubic LLZO.

[0023] However, for the solid electrolyte doped with a specific metal element, the doped metal element may affect the growth of grains in the solid electrolyte, increase the particle size of the solid electrolyte powder, and thus affect the ionic conductivity of the solid electrolyte.

[0024] In view of this, according to the first aspect of the present application, a solid electrolyte material is provided. The solid electrolyte material includes electrolyte powder, and the electrolyte powder is spherical and / or quasi-spherical; and / or The average particle size of the electrolyte powder is 40 nm to 200 nm.

[0025] It should be noted that the electrolyte powder is nanoscale and spherical and / or quasi-spherical ( Figure 1 - Figure 2 ), which is beneficial to improving the ionic conductivity of cubic LLZO. The reason is as follows: 1. Spherical and quasi-spherical electrolyte powders are more likely to form a dense structure during the pyrolysis process. Their surfaces are more uniform and have fewer defects. The dense structure helps to reduce the resistance of ion transport, thereby improving the ionic conductivity; 2. The electrolyte powder being spherical and / or quasi-spherical is beneficial to making the diffusion path of lithium ions more uniform and continuous. Cubic LLZO has an isotropic three-dimensional lithium ion diffusion path, and this structure is beneficial to the rapid migration of lithium ions.

[0026] It should be noted that the average particle size refers to the d90 particle diameter, and the d90 particle diameter refers to the diameter of the particle whose cumulative volume corresponds to 90% of the volume in the particle size distribution.

[0027] In some embodiments of the present application, the average particle size of the electrolyte powder is from 70 nm to 120 nm. Exemplarily, the average particle size of the electrolyte powder is 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, and any value between two adjacent values above.

[0028] In some embodiments of the present application, the solid electrolyte material comprises a substance having the following chemical formula: Li a La3Zr b M c O 12 ; wherein M is any one of the doped metals Al, Ta, Ti, Ga; The value of a is greater than or equal to 5 and less than or equal to 7; The value of b is greater than or equal to 1.2 and less than or equal to 2; The value of c is greater than or equal to 0.1 and less than or equal to 0.7.

[0029] In some embodiments of the present application, if the valence state of M is set as k, then a, b, c, and k satisfy a + 4b + kc = 15.

[0030] It should be noted that the valence state of M refers to the potential highest valence state of the metal ion corresponding to M. Exemplarily, if M is the doped metal Al, the valence state of M is 3; if M is the doped metal Zr, the valence state of M is 4.

[0031] An embodiment of the present application provides a solid electrolyte material, the chemical formula of which is Li a La3Zr b M c O 12 , which limits the value ranges of a, b, and c, that is, limits the doping ratio of the doped metal. By adjusting the doping ratio of the doped metal, a stable cubic phase can be prepared, thereby improving the ionic conductivity of the solid electrolyte material. If the content of the doped metal is higher than the above range, it will lead to too low lithium content, and then reduce the ionic conductivity of the solid electrolyte; if the content of the doped metal is lower than the above range, the solid electrolyte will tend to form a tetragonal phase LLZO, thereby reducing the stability of the solid electrolyte structure.

[0032] In some embodiments of the present application, when the doped metal M is Al, the chemical formula of the solid electrolyte material can be Li 7-3c La3Zr2Al c O 12, wherein, the value range of c is from 0.2 to 0.4. Further, the value range of c can be from 0.25 to 0.35. Exemplarily, the value of c can be 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35 and any value between two adjacent above-mentioned values.

[0033] In some embodiments of the present application, when the doped metal M is Ti, the chemical formula of the solid electrolyte material is Li7La3Zr 2-c Ti c O 12 , wherein, the value range of c is from 0.5 to 0.7. Further, the value range of c is from 0.55 to 0.65. Exemplarily, the value of c can be 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65 and any value between two adjacent above-mentioned values.

[0034] In some embodiments of the present application, when the doped metal M is Ta, the chemical formula of the solid electrolyte material is Li 7- c La3Zr 2-c Ta c O 12 , wherein, the value range of c is from 0.3 to 0.7. Further, the value range of c is from 0.5 to 0.6. Exemplarily, the value of c can be 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60 and any value between two adjacent above-mentioned values.

[0035] In some embodiments of the present application, the conductivity of the solid electrolyte material at 25 °C can have a value range of 0.75×10 -3 ~1.24×10 -3 . Further, the conductivity of the solid electrolyte material at 25 °C can be 0.94×10 -3 ~1.2×10 -3 , 1.07×10 -3 ~1.18×10 -3 or 1.16×10 -3 ~1.22×10 -3 .

[0036] Currently, the synthesis routes of LLZO include two types: solid phase and wet method. Among them, due to the high yield and simple method of the solid phase method, it is the most ideal large-scale production scheme at present. However, the solid phase method has a high reaction temperature and the particle size of the prepared material is large, which limits its large-scale application.

[0037] In the related art, the synthesis reaction temperature is reduced by changing the doping ratio, but it is likely to cause incomplete reaction, resulting in a high impurity content in the final product.

[0038] In view of this, in the second aspect of the present application, a preparation method of a solid electrolyte material is provided, including the following steps: S100: Provide lanthanum salt, zirconium salt, lithium salt, and doped metal salt; S200: Dissolve the lanthanum salt, zirconium salt, and doped metal salt in a first solvent to obtain a first mixed solution; S300: Perform gasification treatment on the first mixed solution to obtain an LZO precursor; S400: Perform wet ball milling on the LZO precursor and the lithium salt, and dry to obtain an LLZO precursor; S500: Perform solid-phase sintering on the LLZO precursor in the temperature range of 400°C to 600°C to obtain the aforementioned solid electrolyte material.

[0039] The embodiment of the present application provides a preparation method of a solid electrolyte material. First, dissolve the lanthanum salt, zirconium salt, and doped metal salt in a solvent to prepare a first mixed solution, and perform gasification treatment on the first mixed solution to obtain an LZO precursor. The lanthanum salt, zirconium salt, and doped metal salt can volatilize during the gasification process to form precursor powders with better dispersion and smaller particle sizes, thereby greatly increasing the surface energy, which is beneficial to reducing the subsequent synthesis reaction temperature and realizing the preparation of cubic-phase LLZO with higher purity.

[0040] In some embodiments of the present application, in step S100, the lanthanum salt may include an organic lanthanum salt. Further, the organic lanthanum salt may include at least one of lanthanum acetate, lanthanum isobutyrate, lanthanum propanolate, lanthanum isopropanolate, lanthanum oxalate, lanthanum phosphate, lanthanum triacetate, and lanthanum terephthalate. Further still, the organic lanthanum salt may include lanthanum acetate or lanthanum terephthalate.

[0041] In some embodiments of the present application, in step S100, the lanthanum salt may also include an inorganic lanthanum salt, and the inorganic lanthanum salt includes any one of lanthanum nitrate, lanthanum carbonate, and lanthanum sulfate.

[0042] In some embodiments of the present application, in step S100, the zirconium salt may include an organic zirconium salt. Further, the organic zirconium salt may include at least one of zirconium acetate, zirconium butyrate, zirconium isobutyrate, zirconium n-propanolate, zirconium isopropanolate, and zirconium benzoate. Further still, the organic zirconium salt may also include zirconium n-propanolate or zirconium formate.

[0043] In some embodiments of the present application, in step S100, the zirconium salt may also include an inorganic zirconium salt, and the inorganic zirconium salt includes any one of zirconium nitrate, zirconium carbonate, and zirconium sulfate.

[0044] In some embodiments of the present application, in step S100, the lithium salt may include any one of lithium hydroxide and lithium carbonate. Further, the lithium salt may include hydrated lithium hydroxide.

[0045] In some embodiments of the present application, in step S100, the doped metal salt may include any one of aluminum salts, tantalum salts, gallium salts, and titanium salts. Further, the aluminum salt may include at least one of trimethylaluminum, triphenylaluminum, triethylaluminum, aluminum n-propoxide, aluminum isopropoxide, and aluminum propionate. Further, the tantalum salt may include diphenyl tantalate or triphenyl tantalate. Further, the gallium salt may include gallium isopropoxide. Further, the titanium salt may include tetrabutyl titanate.

[0046] In some embodiments of the present application, in step S100, the role of the gasification treatment is to be more conducive to the volatilization of the doped metal salt, so as to form precursor particles with better dispersibility and smaller particle size, greatly increasing the surface energy and being conducive to reducing the temperature of subsequent synthesis.

[0047] In some embodiments of the present application, in step S200, the first solvent may include one or a combination of propionic acid, ethanol, isopropanol, and isooctanoic acid. Further, the first solvent may include a combination of propionic acid and isopropanol or a combination of ethanol and isooctanoic acid. The role of the double solvent is to improve the solute dispersibility, regulate the particle formation and deposition processes during spraying, optimize the volatility and combustion rate during spraying, and regulate the surface tension of the droplets.

[0048] In some embodiments of the present application, in step S300, the gasification treatment includes any one of SP (spray pyrolysis), SD (spray drying), and FSP (flame spray pyrolysis).

[0049] In some embodiments of the present application, before the first mixture is subjected to gasification treatment in step S300, the following steps are further included: Stir the first mixture, and wait until it is completely dissolved and clarified before performing gasification treatment.

[0050] In some embodiments of the present application, in step S300, the gasification treatment includes any one of spray pyrolysis, flame spray pyrolysis, and spray drying.

[0051] In some embodiments of the present application, in step S400, wet ball milling may use solvents such as water, isopropanol, and ethanol.

[0052] In some embodiments of the present application, the solid electrolyte material prepared in step S500 has a cubic crystal structure, abbreviated as c-LLZO.

[0053] In some embodiments of the present application, in step S500, during the solid-phase sintering process, the temperature is raised from 1 °C / min to 10 °C / min to 400 °C to 600 °C. Further, the temperature is raised from 2 °C / min to 8 °C / min to 450 °C to 550 °C.

[0054] In some embodiments of the present application, in step S500, after the temperature is raised to 400 °C to 600 °C, it is kept warm for 0.5 h to 12 h.

[0055] In the preparation method of the embodiments of the present application, the synthesis temperature is relatively low, so the degree of lithium excess is much lower than that of the prior art, which can reduce costs and reduce the possibility of lithium compounds appearing in the target product.

[0056] According to the third aspect of the present application, a solid-state battery is provided, including the aforementioned solid electrolyte material or the solid electrolyte material prepared by the preparation method of the aforementioned solid electrolyte material.

[0057] The present application will be specifically described below through specific examples. The following examples are only some embodiments of the present application and do not limit the present application. The raw materials used in the following examples are all commercially available products unless otherwise specified.

[0058] Example 1 A solid electrolyte material was prepared by the following method: The lanthanum salt was lanthanum acetate, the zirconium salt was zirconium n-propoxide, the doped metal salt was aluminum isopropoxide, the lithium salt was lithium hydroxide hydrate, and the solvent was a combination of propionic acid and isopropanol with a volume ratio of 1:1; Lanthanum acetate, zirconium n-propoxide, aluminum isopropoxide, and lithium hydroxide hydrate were configured according to a molar ratio of 3:2:0.32:6.04; Lanthanum acetate, zirconium n-propoxide, and aluminum isopropoxide were successively added to the solvent to obtain a first mixed solution; The first mixed solution was gasified by a spray dryer, with an inlet temperature of 350 °C and an outlet temperature of 150 °C, to obtain an LZO precursor; The LZO precursor and lithium hydroxide hydrate were dissolved in water and wet ball-milled at a rotation speed of 400 rpm for 12 h, and then dried to obtain p-LLZO; The p-LLZO was heated to 450 °C at a heating rate of 3 °C / min by a rotary kiln for solid-phase sintering, and kept warm for 1 h to obtain c-LLZO.

[0059] Example 2 A solid electrolyte material, which is different from that in Example 1 in that the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide hydrate are 3:2:0.2:6.4.

[0060] Example 3 A solid electrolyte material, which is different from that in Example 1 in that the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide hydrate are 3:2:0.4:5.8.

[0061] Example 4 A solid electrolyte material, which is different from that in Example 1 in that the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide hydrate are 3:2:0.1:6.7.

[0062] Example 5 A solid electrolyte material, which is different from that in Example 1 in that the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide hydrate are 3:2:0.5:5.5.

[0063] Example 6 A solid electrolyte material, which is different from that in Example 1 in that the lanthanum salt and aluminum salt are different. In this example, lanthanum terephthalate is used as the lanthanum salt, zirconium propoxide is used as the zirconium salt, and trimethylaluminum is used as the aluminum salt.

[0064] Example 7 A solid electrolyte material, which is different from that in Example 1 in that the solvent is different. In this example, a combination of ethanol and isooctanoic acid with a volume ratio of 1:1 is used as the solvent.

[0065] Example 8 A solid electrolyte material, which is different from that in Example 1 in that M is different. In this example, tetrabutyl titanate is used as the doped metal salt, and the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are 3:1.5:0.5:7.

[0066] Example 9 A solid electrolyte material, which is different from that in Example 8 in that the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are 3:1.45:0.55:7.

[0067] Example 10 A solid electrolyte material, which is different from that of Example 8 in that the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are 3:1.4:0.6:7.

[0068] Example 11 A solid electrolyte material, which is different from that of Example 8 in that the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are 3:1.35:0.65:7.

[0069] Example 12 A solid electrolyte material, which is different from that of Example 8 in that the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, tetrabutyl titanate and lithium hydroxide hydrate are 3:1.3:0.7:7.

[0070] Example 13 A solid electrolyte material, which is different from that of Example 1 in that M is different. In this example, the doped metal salt is diphenyl tantalate, and the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide hydrate are 3:1.7:0.3:6.7.

[0071] Example 14 A solid electrolyte material, which is different from that of Example 13 in that the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide hydrate are 3:1.5:0.5:6.5.

[0072] Example 15 A solid electrolyte material, which is different from that of Example 13 in that the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide hydrate are 3:1.45:0.55:6.45.

[0073] Example 16 A solid electrolyte material, which is different from that of Example 13 in that the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide hydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide hydrate are 3:1.4:0.6:6.4.

[0074] Example 17 A solid electrolyte material, which is different from that of Example 13 in that the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide monohydrate are different. In this example, the molar ratios of lanthanum acetate, zirconium propoxide, diphenyl tantalate and lithium hydroxide monohydrate are 3:1.3:0.7:6.3.

[0075] Example 18 A solid electrolyte material, which is different from that of Example 1 in that the gasification treatment is carried out by flame spray pyrolysis, specifically including: the first mixed solution is gasified through a flame spray pyrolysis reactor, the liquid feeding rate is 7 ml / min, the oxygen dispersion rate is 6 L / min, and the methane-oxygen ratio is 0.5 to obtain an LZO precursor.

[0076] Example 19 A solid electrolyte material, which is different from that of Example 1 in that the temperature of solid-phase sintering is different. In this example, the temperature is raised to 400 °C during the solid-phase sintering process, and the remaining steps are the same as those of Example 1.

[0077] Example 20 A solid electrolyte material, which is different from that of Example 1 in that the temperature of solid-phase sintering is different. In this example, the temperature is raised to 500 °C during the solid-phase sintering process, and it is kept warm for 30 min, and the remaining steps are the same as those of Example 1.

[0078] Example 21 A solid electrolyte material, which is different from that of Example 1 in that the temperature of solid-phase sintering is different. In this example, the temperature is raised to 600 °C during the solid-phase sintering process, and it is kept warm for 30 min, and the remaining steps are the same as those of Example 1.

[0079] Comparative Example 1 A solid electrolyte material, which is different from that of Example 1 in that the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide monohydrate are different. In this example, lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide monohydrate are configured according to the molar ratio of 3:2:0.05:6.85.

[0080] Comparative Example 2 A solid electrolyte material, which is different from that of Example 1 in that the molar ratios of lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide monohydrate are different. In this example, lanthanum acetate, zirconium propoxide, aluminum isopropoxide and lithium hydroxide monohydrate are configured according to the molar ratio of 3:2:0.8:4.6.

[0081] Detection method: 1. Particle size test: The morphologies of the powders in the examples and comparative examples are observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the particle sizes are measured.

[0082] 2. Ionic conductivity test: The powders of the solid electrolyte materials in the examples and comparative examples were pressed on the green ceramic blanks by a tablet press. Then, the pressed green ceramic blanks were placed in a crucible and then placed in a tube furnace and heated to 1150 °C and held for 2 h to obtain ceramic sheets. The conductivity of the ceramic sheets was measured using a conductivity meter: The conductivity σ is obtained from the calculation formula σ = L / RS, where R is the measured resistance value above, L is the thickness value of the electrolyte sheet, and S is the electrode area, and the conductivity at room temperature (25 °C) is calculated.

[0083] The average particle sizes and ionic conductivities of the examples and comparative examples are shown in Table 1 Table 1

[0084] Comparing Examples 1-5 with Comparative Examples 1-2, the difference between Examples 1-3 is that the molar ratio of aluminum isopropoxide is changed, that is, the doping amount of Al in the solid electrolyte is changed. Combining Table 1, it can be seen that when the doping amount of Al is 0.2 to 0.4, the average particle size of the prepared solid electrolyte material is 72 nm to 88 nm, the particle size is moderate, and the ionic conductivity of the solid electrolyte reaches 0.94 S / cm to 1.2 S / cm. In Example 4, the doping amount of Al was reduced, and the amount of aluminum salt input was reduced. Correspondingly, the average particle size of the prepared solid electrolyte powder was also reduced, and the ionic conductivity of the solid electrolyte also decreased. In Example 5, the molar ratio of aluminum isopropoxide was increased, that is, the doping amount of Al was increased. The particle size of the prepared solid electrolyte powder did not change much, but the ionic conductivity of the solid electrolyte decreased slightly. In Comparative Example 1, the doping amount of Al was significantly reduced. Correspondingly, the average particle size of the prepared solid electrolyte material no longer continued to decrease, and the ionic conductivity continued to decrease, only 0.60 S / cm; in Comparative Example 2, the doping amount of Al was increased so that the value of c reached 0.8. The particle size of the prepared solid electrolyte was similar to the average particle size of Example 3, but the ionic conductivity of the solid electrolyte decreased significantly.

[0085] Comparing Examples 6-7 with Example 1, in Example 6, the types of lanthanum salt, zirconium salt and aluminum salt were changed, and the addition amounts of these metal salts were the same as those in Example 1. Therefore, the average particle size of the prepared solid electrolyte was not much different from that of Example 1. Combining Table 1, it can be seen that after changing the types of lanthanum salt, zirconium salt and aluminum salt, the ionic conductivity of the prepared solid electrolyte was similar to that of Example 1. In Example 7, the type of the first solvent was changed, and the first solvent was a combination of ethanol and isooctanoic acid, which had little effect on the ionic conductivity of the solid electrolyte.

[0086] Comparing Examples 8 - 12 with Example 1, in Example 8, tetrabutyl titanate was used as the doped metal salt, and in Examples 9 - 12, the addition amount of tetrabutyl titanate was changed. From Table 1, it can be seen that as the addition amount of tetrabutyl titanate increases, the particle size of the prepared solid electrolyte becomes larger, but all are in the range of 90 - 120 nm. The ionic conductivity of the prepared solid electrolyte first increases and then decreases. When the addition amount of tetrabutyl titanate exceeds 0.6, the ionic conductivity of the solid electrolyte no longer increases but shows a downward trend.

[0087] Comparing Examples 13 - 17 with Example 1, in Example 13, diphenyl tantalate was used as the doped metal salt, and in Examples 14 - 17, the addition amount of diphenyl tantalate was changed. From Table 1, it can be seen that as the molar ratio of diphenyl tantalate increases, the average particle size of the powder of the prepared solid electrolyte also gradually increases, but the ionic conductivity first increases and then decreases. Especially when the c value of the doped metal salt is between 0.5 and 0.6, the ionic conductivity of the prepared solid electrolyte remains at a relatively high level.

[0088] Comparing Example 18 with Example 1, in Example 18, the gasification treatment method was changed. From Table 1, it can be seen that the average particle size and ionic conductivity of the prepared solid electrolyte are similar to the test results of Example 1.

[0089] Comparing Examples 19 - 21 with Example 1, in Examples 19 - 21, the solid-phase sintering temperature was changed. From Table 1, it can be seen that when the solid-phase sintering temperature is between 400°C and 600°C, solid electrolytes with relatively high ionic conductivity can be obtained, achieving a lower solid-phase sintering temperature during the preparation of solid electrolytes.

[0090] In summary, when the doped metal is Al and the doping ratio of Al is 0.2 to 0.4, when the doped metal is Ti and the doping ratio of Ti is 0.55 to 0.65, and when the doped metal is Ta and the doping ratio of Ta is 0.5 to 0.6, the prepared solid electrolyte can obtain relatively high ionic conductivity. This shows that when doping is carried out within the above ratios, a stable cubic phase can be formed through doping, thereby improving the ionic conductivity of the solid electrolyte. However, if the doping ratio is higher than this range, it will lead to too low lithium content and too many vacancies, resulting in a decrease in ionic conductivity; if the doping ratio is lower than this range, the solid electrolyte tends to form a tetragonal phase, which is not conducive to the stability of the overall structure of the solid electrolyte.

[0091] The above has introduced the embodiments of the present invention in detail. Specific examples are used herein to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A solid electrolyte material, characterized in that, the solid electrolyte material includes electrolyte powder, and the electrolyte powder is spherical and / or quasi-spherical; and / or the average particle size of the electrolyte powder is 40 nm to 200 nm.

2. The solid electrolyte material according to claim 1, wherein The average particle size of the electrolyte powder is 70 nm to 120 nm.

3. The solid electrolyte material according to any one of claims 1 to 2, characterized in that, the solid electrolyte material includes a substance with the following chemical formula: Li a La3Zr b M c O 12 ; wherein, M is a doped metal, selected from any one of Al, Ta, Ti, and Ga; the value of a is greater than or equal to 5 and less than or equal to 7; the value of b is greater than or equal to 1.2 and less than or equal to 2; the value of c is greater than or equal to 0.1 and less than or equal to 0.

7.

4. The solid electrolyte material according to claim 3, characterized in that, If the valence state of M is k, then a, b, c, and k satisfy a + 4b + kc = 15.

5. The solid electrolyte material according to claim 3, characterized in that, The M is Al; the solid electrolyte material includes a substance with the following chemical formula: Li 7-3c La3Zr2Al c O 12 , wherein the value range of c is from 0.2 to 0.

4.

6. The solid electrolyte material according to claim 3, characterized in that, The M is Ti; the solid electrolyte material includes a substance with the following chemical formula: Li7La3Zr 2-c Ti c O 12 , where the value range of c is from 0.5 to 0.

7.

7. The solid electrolyte material according to claim 3, wherein The M is Ta; the solid electrolyte material includes a substance with the following chemical formula: Li 7-c La3Zr 2-c Ta c O 12 , wherein, the value range of c is from 0.3 to 0.

7.

8. The solid electrolyte material according to claim 1, characterized in that, The conductivity of the solid electrolyte material at 25 °C is 0.75×10 -3 ~1.24×10 -3 .

9. A method for preparing a solid electrolyte material, characterized in that, it includes the following steps: providing lanthanum salt, zirconium salt, lithium salt, and doped metal salt; dissolving the lanthanum salt, zirconium salt, and doped metal salt in a solvent to obtain a first mixed solution; performing gasification treatment on the first mixed solution to obtain an LZO precursor; performing wet mixing on the LZO precursor and the lithium salt, and stirring to obtain an LLZO precursor; performing solid-phase sintering on the LLZO precursor in the temperature range of 400 °C to 600 °C to obtain the solid electrolyte material according to any one of claims 1 to 8.

10. The preparation method of the solid electrolyte material according to claim 9, characterized in that, the lanthanum salt includes at least one of lanthanum acetate, lanthanum isobutyrate, lanthanum propanolate, lanthanum isopropanolate, lanthanum oxalate, lanthanum phosphate, lanthanum triacetate, lanthanum terephthalate; and / or the zirconium salt includes at least one of zirconium acetate, zirconium butyrate, zirconium isobutyrate, zirconium propanolate, zirconium isopropanolate, zirconium benzoate; and / or the lithium salt includes any one of lithium hydroxide and lithium carbonate; and / or the solvent includes one or a combination of propionic acid, ethanol, isopropanol, and isooctanoic acid; the doped metal salt includes any one of aluminum salt, tantalum salt, gallium salt, and titanium salt.

11. The preparation method of the solid electrolyte material according to claim 9, characterized in that, before the gasification treatment of the first mixed solution, the following steps are further included: stirring the first mixed solution, and performing gasification treatment after stirring until it is completely dissolved and clarified; and / or the gasification treatment includes any one of spray pyrolysis, spray drying, and flame spray pyrolysis.

12. A solid-state battery, characterized in that, A solid electrolyte material prepared by using the solid electrolyte material according to any one of claims 1 to 8 or the preparation method of the solid electrolyte material according to any one of claims 9 to 11.

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