Aluminum-doped garnet type LLZO lithium ion conductor, preparation method and application

Abstract

The invention belongs to the technical field of new energy materials, and discloses an aluminum-doped garnet type LLZO lithium ion conductor, and a preparation method and application thereof. The aluminum-doped garnet type LLZO lithium ion conductor is of a cubic phase garnet structure, the structural expression is Li < 7-3x > La < 3 > Zr < 2 > Al < x > O < 12 >, and x is equal to 0.20-1.00; meanwhile, the invention provides a preparation method. According to the invention, the Al element enters a garnet unit cell to replace part of Li and brings two extra Li vacancies. And the LLZO is easy to form a cubic phase. And meanwhile, due to the existence of aluminum ions, the aluminum ions are easy to interact with the Li element at the sintering temperature to form LiAlO2, and pores of the LLZO solid electrolyte ceramic in the sintering process can be filled, so that compact ceramic is formed.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials, and in particular relates to an aluminum-doped garnet-type LLZO lithium ion conductor, a preparation method and an application thereof. Background Art

[0002] Lithium-ion batteries have penetrated into every aspect of life and are widely used in small devices such as mobile phones and computers, as well as new energy vehicles. With the rapid development of science and technology, users' demand for battery performance is increasing. However, traditional lithium-ion batteries use liquid electrolytes, which are not only difficult to match with large-capacity lithium metal negative electrodes, but also have the risk of flammability. Garnet-type solid electrolyte Li7La3Zr2O 12 (LLZO), due to its stability to metallic lithium negative electrode, high ionic conductivity, good thermal stability and other advantages, can be directly applied to the next generation of high-safety, high-energy-density all-solid-state batteries. LLZO has two crystal forms: tetragonal phase and cubic phase. The lithium position in the tetragonal phase is completely occupied, while the cubic phase has a higher ionic conductivity due to the presence of a higher lithium vacancy concentration, but it is unstable at room temperature and needs to be doped with overvalent elements to stabilize its cubic phase structure. Due to the abundant reserves and low cost of aluminum, it is often used as a dopant to improve the performance of materials. In the process of doping LLZO, one aluminum ion occupies a lithium ion position and produces two lithium vacancies, thereby stabilizing the cubic phase structure of LLZO.

[0003] At present, the traditional synthesis methods of LLZO are mainly solid-phase method, sol-gel method, co-precipitation method, etc. However, due to the fact that the traditional synthesis methods still have a series of shortcomings such as long synthesis cycle, large product particle size, wide particle size distribution, and complicated process, there is currently no mature preparation method to achieve large-scale commercial production of LLZO solid electrolytes.

[0004] Flame spray pyrolysis is a new method for preparing nanomaterials. It has the advantages of simple equipment, uniform particle size, continuous production and easy industrial scale-up. It is possible to achieve commercial production of cubic LLZO solid electrolyte. In recent years, Richard M. Laine team of a certain university [YI E, WANGW, KIEFFER J, et al. Flame made nanoparticles permit processing of dense, flexible, Li+ conducting ceramic electrolyte thin films of cubic-Li7La3Zr2O 12(c-LLZO)[J].Journal ofMaterials Chemistry A,2016,4(33):12947-12954.;YI E,WANG W,KIEFFER J,et al.Key parameters governing thedensification of cubic-Li7La3Zr2O 12 Li+conductors[J].Journal of Power Sources,2017,352:156-164.], Hartmut Wiggers team from another university [ALI MY,ORTHNER H,WIGGERSH.Spray Flame Synthesis(SFS)of Lithium Lanthanum Zirconate(LLZO)Solid Electrolyte[J].Materials,2021,14(13):3472.] and a team from another college [MULDOON VL.Scalable Synthesis of Solid-State Electrolytes Using Flame-Assisted Spray Pyrolysis[D].Massachusetts Institute of Technology,2022.] respectively used flame spray pyrolysis to synthesize cubic phase LLZO and achieved its rapid preparation. However, lithium easily sublimates and volatilizes at high temperatures (above 1000°C), so an excess of 30%-50% lithium needs to be added to the precursor to compensate for the lithium loss during flame spray pyrolysis, which increases the production cost of LLZO. Summary of the invention

[0005] In order to overcome the problems existing in the related art, the disclosed embodiments of the present invention provide an aluminum-doped garnet-type LLZO lithium ion conductor, a preparation method and application thereof, and specifically relate to an efficient preparation method of an aluminum-doped cubic garnet-type LLZO lithium ion conductor based on flame spray pyrolysis.

[0006] The technical solution is as follows: a method for preparing an aluminum-doped garnet-type LLZO lithium ion conductor, the preparation method comprising the following steps:

[0007] S1, preparing a mixed aqueous solution of a lanthanum source, an aluminum source, and a zirconium source in a molar ratio, and stirring until clarified to prepare a metal nitrate mixed solution as a precursor solution;

[0008] S2, using an ultrasonic atomizer to atomize the precursor liquid into droplets, and the carrier gas sends the atomized droplets into a coaxial burner through a preheating section to continuously synthesize nanoparticles; a collecting device uses negative pressure to quickly deposit the nanoparticles on the glass fiber membrane, and obtains metal oxide precursor nanopowder from the glass fiber membrane;

[0009] S3, according to the molar ratio of metal ions, the obtained metal oxide precursor and the lithium source are ground and mixed evenly with an agate mortar, wherein lithium is in excess; then they are placed in a crucible for calcination, and when the furnace temperature drops to room temperature, the aluminum-doped garnet-type LLZO lithium ion conductor sample is taken out.

[0010] In step S1, a lanthanum source, an aluminum source, and a zirconium source are configured into a mixed aqueous solution in a molar ratio, including: a lanthanum source, an aluminum source, and a zirconium source with a molar ratio of La:Al:Zr=3.00:x:2.00 are configured into a mixed aqueous solution, x=0.20-1.00, and stirred for 12 hours until clarified to prepare a metal nitrate mixed solution as a precursor solution; the lanthanum source is La(NO3)3, the aluminum source is Al(NO3)3, and the zirconium source is ZrO(NO3)2.

[0011] In step S2, the precursor liquid is atomized into droplets using an ultrasonic atomizer, including: the precursor liquid is atomized into droplets with an average diameter of 3-100 μm using an ultrasonic atomizer.

[0012] In step S2, the carrier gas delivers the atomized droplets into the coaxial burner through the preheating section to continuously synthesize nanoparticles, including: the carrier gas N2 delivers the atomized droplets into the coaxial burner through the 70-300° C. preheating section to continuously synthesize nanoparticles.

[0013] In step S3, the obtained metal oxide precursor and the lithium source are ground and mixed evenly using an agate mortar according to the molar ratio of metal ions Li:La:Al:Zr=7.04:3.00:x:2.00, x=0.20-1.00; the lithium source is Li2CO3.

[0014] In step S3, the excess amount of lithium is 5%-50%.

[0015] In step S3, the calcination temperature is set to 600-1050°C, the heating rate is 2-10°C / min, the calcination atmosphere is oxygen, and the calcination time is 1-12h.

[0016] Another object of the present invention is to provide an aluminum-doped garnet-type LLZO lithium ion conductor, wherein the aluminum-doped garnet-type LLZO lithium ion conductor is prepared by using the preparation method of the aluminum-doped garnet-type LLZO lithium ion conductor, and the aluminum-doped garnet-type LLZO lithium ion conductor is a cubic garnet structure, and the structural expression is Li 7- 3x La3Zr2Alx O 12 , x=0.20-1.00.

[0017] Furthermore, the particle size distribution of the aluminum-doped garnet-type LLZO lithium ion conductor is 3-100 μm.

[0018] Another object of the present invention is to provide an application of an aluminum-doped garnet-type LLZO lithium ion conductor in the preparation of a lithium battery, and to use the aluminum-doped garnet-type LLZO lithium ion conductor as a solid electrolyte for an all-solid-state lithium battery or a lithium ion battery, or as a solid electrolyte for metal lithium-air or metal lithium-sulfur batteries.

[0019] Combining all the above technical solutions, the beneficial effects of the present invention are as follows: the aluminum-doped cubic garnet-type LLZO ceramic lithium ion conductor prepared by the present invention has good electrochemical stability to metallic lithium and can be used as a solid electrolyte for all-solid-state lithium batteries or lithium ion batteries, and can also be used as a solid electrolyte for metallic lithium-air and metallic lithium-sulfur batteries. The lithium ion conductor of the present invention has a basic structural expression of Li 6.4 La3Zr2Al 0.2 O 12 , which is a cubic phase structure. The Al element enters the garnet unit cell to replace part of the Li position and brings two additional Li vacancies. This makes LLZO easy to form a cubic phase. At the same time, due to the presence of aluminum ions, it is easy to interact with the Li element at the sintering temperature to form LiAlO2, which can fill the pores of the LLZO solid electrolyte ceramic during the sintering process to form a dense ceramic. Compared with the prior art, the aluminum-doped cubic garnet-type structure LLZO ceramic lithium ion conductor prepared based on the present invention has a particle size distribution of 1-100μm, and does not require long-term ball milling, and can directly and continuously produce micro-nano powders. Compared with the prior art, the lithium ion conductor of the present invention only needs to be calcined in a shorter time to obtain a cubic phase LLZO, which shortens the preparation time, and the steps are simple, which is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings herein are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the description, serve to explain the principles of the present disclosure;

[0021] Figure 1 It is a flow chart of a method for preparing an aluminum-doped garnet-type LLZO lithium ion conductor provided by an embodiment of the present invention;

[0022] Figure 2 The structure provided by the embodiment of the present invention is Li 6.4 La3Zr2Al 0.2 O 12, Spectrum of aluminum-doped garnet-type LLZO lithium-ion conductor with 10% lithium excess;

[0023] Figure 3 The structure provided by the embodiment of the present invention is Li 6.4 La3Zr2Al 0.2 O 12 , Image of aluminum-doped garnet-type LLZO lithium-ion conductor with 10% lithium excess;

[0024] Figure 4 The structure provided by the embodiment of the present invention is Li 5.2 La3Zr2Al 0.6 O 12 , Spectrum of aluminum-doped garnet-type LLZO lithium-ion conductor with 20% lithium excess;

[0025] Figure 5 The structure provided by the embodiment of the present invention is Li 5.2 La3Zr2Al 0.6 O 12 , Image of aluminum-doped garnet-type LLZO lithium-ion conductor with 20% lithium excess;

[0026] Figure 6 The structure provided by the embodiment of the present invention is Li 4.0 La3Zr2Al 1.0 O 12 , Spectrum of aluminum-doped garnet-type LLZO lithium-ion conductor with 10% lithium excess;

[0027] Figure 7 The structure provided by the embodiment of the present invention is Li 4.0 La3Zr2Al 1.0 O 12 , Image of aluminum-doped garnet-type LLZO lithium-ion conductor with 10% lithium excess;

[0028] Figure 8 It is Li7La3Zr2O provided by the existing technology 12 Particle size distribution diagram;

[0029] Fig. 9 It is Li7La3Zr2O provided by the existing technology 12 A typical spectrum of XRD phase structure analysis. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0031] Example 1: The raw materials used in the aluminum-doped garnet-type LLZO lithium ion conductor of the present invention are water-soluble metal inorganic salts, for example, the lithium source is Li2CO3; the lanthanum source is La(NO3)3; the aluminum source is Al(NO3)3; and the zirconium source is ZrO(NO3)2.

[0032] The aluminum-doped garnet-type LLZO lithium ion conductor of the present invention is a cubic garnet structure, and its structural expression is Li 7-3x La3Zr2Al x O 12 , x = 0.20-1.00;

[0033] Example 2: The raw materials used in the aluminum-doped garnet-type LLZO lithium ion conductor of the present invention are water-soluble metal inorganic salts, for example, the lithium source is Li2CO3; the lanthanum source is La(NO3)3; the aluminum source is Al(NO3)3; and the zirconium source is ZrO(NO3)2.

[0034] For example, the molar ratio of the metal ions is Li:La:Al:Zr=7.04:3.00:x:2.00, x=0.20-1.00, wherein the Li ion is prepared in double form.

[0035] Or it can be expressed as: the molar ratio of the lithium source, lanthanum source, aluminum source and zirconium source is Li2CO3:La(NO3)3:Al(NO3)3:ZrO(NO3)2=3.52:3.00:x:2.00, x=0.20-1.00.

[0036] Embodiment 3, as Figure 1 As shown, the preparation method of the aluminum-doped garnet-type LLZO lithium ion conductor of the present invention comprises the following steps:

[0037] S1, preparing a mixed aqueous solution of a lanthanum source, an aluminum source, and a zirconium source in a molar ratio, and stirring until clarified to prepare a metal nitrate mixed solution as a precursor solution;

[0038] S2, using an ultrasonic atomizer to atomize the precursor liquid into droplets, and the carrier gas sends the atomized droplets into a coaxial burner through a preheating section to continuously synthesize nanoparticles; a collecting device uses negative pressure to quickly deposit the nanoparticles on the glass fiber membrane, and obtains metal oxide precursor nanopowder from the glass fiber membrane;

[0039] S3, according to the molar ratio of metal ions, the obtained metal oxide precursor and the lithium source are ground and mixed evenly with an agate mortar, wherein lithium is in excess; then they are placed in a crucible for calcination, and when the furnace temperature drops to room temperature, the aluminum-doped garnet-type LLZO lithium ion conductor sample is taken out.

[0040] Exemplarily, in step S1, a lanthanum source, an aluminum source, and a zirconium source with a molar ratio of La:Al:Zr=3.00:x:2.00 are configured into a mixed aqueous solution, x=0.20-1.00, and stirred for 12 hours until clarified to prepare a metal nitrate mixed solution as a precursor solution.

[0041] Exemplarily, in step S2, an ultrasonic atomizer is used to atomize the precursor liquid into droplets with an average diameter of 3-100 μm, and the carrier gas N2 sends the atomized droplets into a coaxial burner through a 70-300° C. preheating section to continuously synthesize nanoparticles.

[0042] Exemplarily, in step S3, the obtained metal oxide precursor and an appropriate amount of lithium source are ground and mixed evenly with an agate mortar according to the stoichiometric ratio of Li:La:Al:Zr=7.04:3.00:x:2.00, x=0.20-1.00, wherein the excess lithium is 5%-50%; then placed in a crucible for calcination, the calcination temperature is set to 600-1050°C, the heating rate is 2-10°C / min, the calcination atmosphere is oxygen, the calcination time is 1-12h, and the sample is taken out when the furnace temperature drops to room temperature, i.e., an aluminum-doped garnet-type LLZO lithium ion conductor.

[0043] The obtained aluminum-doped garnet-type LLZO lithium-ion conductor (ceramic sample) was subjected to phase structure analysis using X-ray diffraction (XRD); the morphology and size of the sample were observed using a scanning electron microscope (SEM). When performing the SEM test, a gold film needs to be deposited on the surface of the aluminum-doped garnet-type LLZO lithium-ion conductor sample to increase the conductivity of the sample. The deposition method uses an ion sputtering method. All samples need to be stored in a glove box in an argon environment to prevent water vapor and CO2 in the air from reacting with the sample.

[0044] The XRD phase structure analysis result of the aluminum-doped garnet-type LLZO lithium ion conductor dense ceramic powder obtained by the present invention is basically consistent with the standard card-control, indicating that the obtained powder is garnet-type cubic phase LLZO; the spectrum has a trace impurity phase, and the XRD peak is slightly shifted to the left relative to the standard card, indicating that aluminum ions have entered the unit cell of the garnet-type LLZO and caused a certain unit cell expansion.

[0045] The aluminum-doped garnet-type cubic phase LLZO ceramic lithium ion conductor of the present invention has good electrochemical stability to metallic lithium, can be used as a solid electrolyte for all-solid-state lithium batteries or lithium ion batteries, and can also be used as a solid electrolyte for metallic lithium-air and metallic lithium-sulfur batteries.

[0046] Example 4: This embodiment of the present invention provides an aluminum-doped garnet-type LLZO lithium ion conductor, which has a cubic garnet structure and a structural expression of Li 7-3x La3Zr2Al x O 12 , x = 0.20-1.00 The preparation method is as follows:

[0047] Step 1, prepare a mixed aqueous solution of lanthanum source, aluminum source and zirconium source with a molar ratio of La:Al:Zr=3.00:x:2.00, stir until clear, and prepare a metal nitrate mixed solution as a precursor solution; the lithium source is Li2CO3; the lanthanum source is La(NO3)3; the aluminum source is Al(NO3)3; and the zirconium source is ZrO(NO3)2.

[0048] Step 2, using an atomizer to atomize the precursor liquid into droplets with an average diameter of 3-100 μm, and the carrier gas sends the atomized droplets into a coaxial burner through a 70-300°C preheating section to continuously synthesize nanoparticles. The atomized droplets are sent to the coaxial burner for pyrolysis to synthesize nanoparticles, and the collection device uses negative pressure to quickly deposit the nanoparticles on the glass fiber membrane, and obtain metal oxide precursor nanopowder from the glass fiber membrane; the synthesis method of the metal oxide precursor is flame spray pyrolysis.

[0049] Step 3, according to the stoichiometric ratio, the obtained metal oxide precursor and an appropriate amount of lithium source are ground and mixed evenly in a mortar, wherein the excess lithium is 10-50%. Then, it is placed in an alumina crucible for calcination, the calcination temperature is 900-1050°C, the heating rate is 1-10°C / min, the calcination atmosphere is oxygen, and the calcination time is 6-12h. When the furnace temperature drops to room temperature, the aluminum-doped garnet-type LLZO lithium ion conductor sample is taken out and placed in a glove box for storage.

[0050] In step 3, the particle size distribution of the aluminum-doped garnet-type LLZO lithium ion conductor is 3-100 μm.

[0051] The aluminum-doped garnet-type LLZO lithium-ion conductor is used as a solid electrolyte for lithium-ion batteries.

[0052] Example 5: The solid electrolyte aluminum-doped garnet-type LLZO lithium ion conductor in this example has a chemical composition of Li 6.4 La3Zr2Al 0.2 O 12 , the lithium excess is 10%.

[0053] The preparation method of the aluminum-doped garnet-type LLZO lithium ion conductor comprises:

[0054] Step a, using La(NO3)3, Al(NO3)3 and ZrO(NO3)2 as raw materials, the molar ratio of which is La(NO3)3:Al(NO3)3:ZrO(NO3)2=3.00:0.20:2.00. Dissolve the raw materials in water in molar ratio to form a solution, and stir for 12 hours until the solution is clear;

[0055] Step b, putting the stirred solution into an ultrasonic atomizer; using the ultrasonic atomizer to atomize the precursor liquid into droplets with an average diameter of 3 μm, and using carrier gas N2 to send the atomized droplets into a coaxial burner through a 70° C. preheating section to continuously synthesize nanoparticles. The atomized droplets are sent into the coaxial burner for pyrolysis to synthesize nanoparticles, and a collecting device uses negative pressure to quickly deposit the nanoparticles on the glass fiber membrane, and a metal oxide precursor nanopowder is obtained from the glass fiber membrane.

[0056] Step c, according to the stoichiometric ratio, the obtained metal oxide precursor and an appropriate amount of lithium source (i.e., Li2CO3) are ground and mixed evenly with an agate mortar, wherein the excess lithium is 10%. Then, it is placed in a magnesium oxide crucible for calcination, the calcination temperature is set to 1050°C, the heating rate is 5°C / min, the calcination atmosphere is oxygen, and the calcination time is 12h to obtain a cubic phase LLZO powder, i.e., an aluminum-doped garnet-type LLZO lithium ion conductor.

[0057] The particle size distribution of the aluminum-doped garnet-type LLZO lithium ion conductor powder sample obtained in Example 5 is 10 μm-100 μm. The aluminum-doped garnet-type LLZO lithium ion conductor (ceramic sample) is subjected to XRD phase structure analysis, and its typical spectrum is as follows: Figure 2 As shown, it is basically consistent with the standard card PDF#97-023-8690, indicating that the obtained ceramic is garnet-type cubic phase LLZO. The above ceramic sample was observed by SEM, and its typical photo is as follows Figure 3 As shown, it shows that the grains of cubic phase LLZO are well developed and the grain boundaries are clear.

[0058] Example 6: The solid electrolyte aluminum-doped garnet-type LLZO lithium ion conductor in this example has a chemical composition of Li 5.2 La3Zr2Al 0.6 O 12 , the lithium excess is 20%.

[0059] The preparation method of the aluminum-doped garnet-type LLZO lithium ion conductor comprises:

[0060] Step (1), using La(NO3)3, Al(NO3)3 and ZrO(NO3)2 as raw materials, the molar ratio of which is La(NO3)3:Al(NO3)3:ZrO(NO3)2=3.00:0.60:2.00. The raw materials are dissolved in water in molar ratio to form a solution, and stirred for 12 hours until the solution is clear;

[0061] Step (2), placing the stirred solution into an ultrasonic atomizer; using the ultrasonic atomizer to atomize the precursor liquid into droplets with an average diameter of 3 μm, and using carrier gas N2 to send the atomized droplets into a coaxial burner through a 70° C. preheating section to continuously synthesize nanoparticles. The collection device uses negative pressure to quickly deposit the nanoparticles on the glass fiber membrane, and obtains metal oxide precursor nanopowder from the glass fiber membrane.

[0062] Step (3), according to the stoichiometric ratio, the obtained metal oxide precursor and an appropriate amount of lithium source (i.e., Li2CO3) are ground and mixed evenly with an agate mortar, wherein the excess lithium is 10%. Then, it is placed in an alumina crucible for calcination, the calcination temperature is set to 1000°C, the heating rate is 5°C / min, the calcination atmosphere is oxygen, and the calcination time is 7h to obtain cubic phase LLZO powder. That is, aluminum-doped garnet-type LLZO lithium ion conductor.

[0063] Example 6: The particle size distribution of the obtained powder sample is 2 μm-10 μm. The above ceramic powder sample is subjected to XRD phase structure analysis, and its typical spectrum is as follows: Figure 4 As shown, it is basically consistent with the standard card PDF#97-023-8690, indicating that the obtained ceramic powder is garnet-type cubic phase LLZO. The above ceramic sample was observed by SEM, and its typical photo is as follows Figure 5 As shown, it shows that the granules of LLZO are well developed with clear edges.

[0064] Example 7: The solid electrolyte aluminum-doped garnet-type LLZO lithium ion conductor in this example has a chemical composition of Li 4.0 La3Zr2Al 1.0 O 12 , the lithium excess is 10%.

[0065] The preparation method of the aluminum-doped garnet-type LLZO lithium ion conductor comprises:

[0066] The first step is to use La(NO3)3, Al(NO3)3 and ZrO(NO3)2 as raw materials, and the molar ratio is La(NO3)3:Al(NO3)3:ZrO(NO3)2=3.00:1.00:2.00. The raw materials are dissolved in water in molar ratio to form a solution, and stirred for 12 hours until the solution is clear;

[0067] In the second step, the stirred solution is placed in an ultrasonic atomizer; the precursor liquid is atomized into droplets with an average diameter of 3 μm by the ultrasonic atomizer, and the carrier gas N2 sends the atomized droplets into a coaxial burner through a 70°C preheating section to continuously synthesize nanoparticles. The collection device uses negative pressure to quickly deposit the nanoparticles on the glass fiber membrane, and obtains metal oxide precursor nanopowder from the glass fiber membrane.

[0068] The third step is to grind and mix the obtained metal oxide precursor and an appropriate amount of lithium source (i.e., Li2CO3) in an agate mortar according to the stoichiometric ratio, wherein the excess lithium is 10%. Then, the precursor is placed in an alumina crucible for calcination, and the calcination temperature is set to 1000°C, the heating rate is 5°C / min, the calcination atmosphere is oxygen, and the calcination time is 7 hours to obtain a cubic LLZO ceramic powder.

[0069] The particle size distribution of the powder sample obtained in Example 7 is 1 μm-5 μm. The above ceramic powder sample is subjected to XRD phase structure analysis, and its typical spectrum is as follows: Figure 6 As shown, it is basically consistent with the standard card PDF#97-023-8690, indicating that the obtained ceramic is garnet-type cubic phase LLZO. The above ceramic powder sample was observed by SEM, and its typical photo is as follows Figure 7 As shown, it shows that the LLZO particles are well developed and the particle edges are clear.

[0070] Comparative Example: The solid electrolyte in this comparative example has a chemical composition of Li7La3Zr2O 12 , with a lithium excess of 10%, from the Jae-Myung Lee team [LEE J, KIM T, BAEK S, et al. High lithium ion conductivity of Li7La3Zr2O12 synthesized by solid state reaction[J]. Solid State Ionics, 2014, 258: 13-17.].

[0071] Li7La3Zr2O 12 The preparation method comprises:

[0072] In the first step, LiOH, La2O3 and ZrO2 are used as raw materials, and the molar ratio thereof is LiOH:La2O3:ZrO2=7.70:1.50:2.00.

[0073] In the second step, the raw materials are dispersed in isopropanol in a molar ratio and placed in a ball mill for 12 hours at 400 rpm. The mixed solution after ball milling is placed in a drying oven and dried at 100°C to obtain a uniform and fine powder. It is then placed in an alumina crucible for calcination. The calcination temperature is set to 900°C, the heating rate is 4.8°C / min, the calcination atmosphere is air, and the calcination time is 12 hours to obtain cubic phase LLZO powder.

[0074] In step 3, the obtained cubic LLZO powder was dispersed in isopropanol and placed in a ball mill for 12 h at 400 rpm and 500 rpm, respectively, to obtain refined cubic LLZO ceramic powders LLZ400 and LLZ500.

[0075] The particle size distribution of the above powder samples was obtained by laser scattering particle size distribution analyzer. The typical particle size distribution is as follows: Figure 8 As shown, the particle size distribution of the powder sample obtained in the comparative example is 400 μm-3000 μm. The above powder sample was subjected to XRD phase structure analysis, and its typical spectrum is as follows Fig. 9 As shown, it is basically consistent with the standard card of cubic phase LLZO, indicating that the obtained ceramic powder is garnet-type cubic phase LLZO. Compared with the comparative example, the present invention shortens the preparation time of cubic phase LLZO, does not require long-term ball milling, and can obtain cubic phase LLZO powder with narrow particle size distribution after calcination for 7 hours.

[0076] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0077] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing an aluminum-doped garnet-type LLZO lithium ion conductor, characterized in that: The preparation method comprises the following steps: S1, preparing a mixed aqueous solution of a lanthanum source, an aluminum source, and a zirconium source in a molar ratio, and stirring until clarified to prepare a metal nitrate mixed solution as a precursor solution; S2, using an ultrasonic atomizer to atomize the precursor liquid into droplets, and the carrier gas sends the atomized droplets into a coaxial burner through a preheating section to continuously synthesize nanoparticles; a collecting device uses negative pressure to quickly deposit the nanoparticles on the glass fiber membrane, and obtains metal oxide precursor nanopowder from the glass fiber membrane; S3, according to the molar ratio of metal ions, the obtained metal oxide precursor and the lithium source are ground and mixed evenly with an agate mortar, wherein lithium is in excess; then they are placed in a crucible for calcination, and when the furnace temperature drops to room temperature, the aluminum-doped garnet-type LLZO lithium ion conductor sample is taken out.

2. The method for preparing the aluminum-doped garnet-type LLZO lithium ion conductor according to claim 1, characterized in that: In step S1, a lanthanum source, an aluminum source, and a zirconium source are configured into a mixed aqueous solution in a molar ratio, including: a lanthanum source, an aluminum source, and a zirconium source with a molar ratio of La:Al:Zr=3.00:x:2.00 are configured into a mixed aqueous solution, x=0.20-1.00, and stirred for 12 hours until clarified to prepare a metal nitrate mixed solution as a precursor solution; the lanthanum source is La(NO3)3, the aluminum source is Al(NO3)3, and the zirconium source is ZrO(NO3)2.

3. The method for preparing the aluminum-doped garnet-type LLZO lithium ion conductor according to claim 1, characterized in that: In step S2, the precursor liquid is atomized into droplets using an ultrasonic atomizer, including: the precursor liquid is atomized into droplets with an average diameter of 3-100 μm using an ultrasonic atomizer.

4. The method for preparing the aluminum-doped garnet-type LLZO lithium ion conductor according to claim 1, characterized in that: In step S2, the carrier gas delivers the atomized droplets into the coaxial burner through the preheating section to continuously synthesize nanoparticles, including: the carrier gas N2 delivers the atomized droplets into the coaxial burner through the 70-300° C. preheating section to continuously synthesize nanoparticles.

5. The method for preparing the aluminum-doped garnet-type LLZO lithium ion conductor according to claim 1, characterized in that: In step S3, the obtained metal oxide precursor and the lithium source are ground and mixed evenly using an agate mortar according to the molar ratio of metal ions Li:La:Al:Zr=7.04:3.00:x:2.00, x=0.20-1.00; the lithium source is Li2CO3.

6. The method for preparing the aluminum-doped garnet-type LLZO lithium ion conductor according to claim 1, characterized in that: In step S3, the excess amount of lithium is 5%-50%.

7. The method for preparing the aluminum-doped garnet-type LLZO lithium ion conductor according to claim 1, characterized in that: In step S3, the calcination temperature is set to 600-1050°C, the heating rate is 2-10°C / min, the calcination atmosphere is oxygen, and the calcination time is 1-12h.

8. An aluminum-doped garnet-type LLZO lithium ion conductor, characterized in that: The aluminum-doped garnet-type LLZO lithium ion conductor is prepared by the method for preparing an aluminum-doped garnet-type LLZO lithium ion conductor according to any one of claims 1 to 7. The aluminum-doped garnet-type LLZO lithium ion conductor has a cubic garnet structure, and the structural expression is Li 7-3x La3Zr2Al x O 12 , x=0.20-1.

00.

9. The aluminum-doped garnet-type LLZO lithium ion conductor according to claim 8, characterized in that: The particle size distribution of the aluminum-doped garnet-type LLZO lithium ion conductor is 3-100 μm.

10. An application of an aluminum-doped garnet-type LLZO lithium ion conductor in preparing a lithium battery, characterized in that: The aluminum-doped garnet-type LLZO lithium ion conductor described in claim 8 is used as a solid electrolyte for an all-solid-state lithium battery or a lithium ion battery, or as a solid electrolyte for a metal lithium-air or metal lithium-sulfur battery.

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