A nano cubic phase lithium lanthanum zirconium oxide and its preparation method and solid electrolyte

Abstract

The present application provides a nano-cubic lithium lanthanum zirconium oxide and its preparation method and solid electrolyte, which relates to the field of solid electrolyte materials. The preparation method of nano-cubic lithium lanthanum zirconium oxide includes: mixing a lithium source, a lanthanum source, a zirconium source, a solvent and a complexing agent to obtain a first mixture, spray-drying the first mixture to obtain micron-sized precursor particles; sintering the micron-sized precursor particles to obtain lithium lanthanum zirconium aluminum oxide precursor powder; mixing the lithium lanthanum zirconium aluminum oxide precursor powder and aluminum powder to obtain a second mixture, and in an inert gas and oxygen-containing atmosphere, electric explosion and laser annealing the second mixture to obtain nano-cubic lithium lanthanum zirconium oxide. The particle size of the nano-cubic lithium lanthanum zirconium oxide powder reaches the nanometer level through electric explosion and is evenly distributed.

Description

Technical Field

[0001] The present application relates to the field of solid electrolyte materials, and in particular to a nano cubic phase lithium lanthanum zirconium oxide, a preparation method thereof, and a solid electrolyte. Background Art

[0002] Lithium lanthanum zirconium oxide (LLZO) is a core electrolyte material for next-generation solid-state lithium batteries due to its high ionic conductivity and chemical stability. Traditional LLZO preparation methods (such as solid-phase method, co-precipitation method, and sol-gel method) have the following defects:

[0003] 1. Coarse particles: High temperature calcination causes particle agglomeration, requiring subsequent ball milling for refinement, which introduces impurities and consumes high energy;

[0004] 2. Unstable crystal phase: easy to generate impurity phase (such as tetragonal LLZO), which reduces ionic conductivity;

[0005] 3. Complex process: The multi-step synthesis cycle is long and the cost is high.

[0006] Therefore, there is an urgent need to provide a method for preparing cubic phase LLZO to solve the above problems. Summary of the Invention

[0007] The purpose of this application is to provide a nano cubic phase lithium lanthanum zirconium oxide and its preparation method and solid electrolyte to solve the above problems.

[0008] To achieve the above objectives, the present application provides a first aspect of a method for preparing nano cubic lithium lanthanum zirconium oxide, comprising:

[0009] mixing a lithium source, a lanthanum source, a zirconium source, a solvent, and a complexing agent to obtain a first mixture, and spray-drying the first mixture to obtain micron-sized precursor particles;

[0010] Sintering the micron-sized precursor particles to obtain lithium lanthanum zirconium aluminum oxide precursor powder;

[0011] The lithium lanthanum zirconium aluminum oxide precursor powder and aluminum powder are mixed to obtain a second mixture, and the second mixture is subjected to electric explosion and laser annealing in an inert gas and oxygen-containing atmosphere to obtain nano cubic lithium lanthanum zirconium oxide.

[0012] Optionally, the particle size of the nano cubic lithium lanthanum zirconium oxide is 10nm-50nm.

[0013] Optionally, the preparation method of the nano cubic lithium lanthanum zirconium oxide satisfies at least one of the following conditions:

[0014] A. the lithium source comprises one or more of lithium carbonate, lithium hydroxide, lithium nitrate and lithium acetate;

[0015] B. the lanthanum source comprises one or more of lanthanum oxide, lanthanum nitrate and lanthanum acetate;

[0016] C. the zirconium source comprises one or more of zirconium oxychloride, zirconium nitrate and zirconium isopropoxide;

[0017] D. the solvent comprises water;

[0018] E. The complexing agent includes one or more of ethylenediaminetetraacetic acid, citric acid and tartaric acid.

[0019] Optionally, the preparation method of the nano cubic phase lithium lanthanum zirconium oxide meets at least one of the following conditions:

[0020] A. The molar ratio of Li in the lithium source, the lanthanide in the lanthanum source, and the zirconium in the zirconium source is 7.3-7.8:3:2;

[0021] B. the molar ratio of the total metal ions in the first mixture, the solvent and the complexing agent is 1:1.2-1.5:50-80;

[0022] C. The mass ratio of the lithium lanthanum zirconium aluminum oxide precursor powder to the aluminum powder is 4-6:1;

[0023] D. The particle size of the aluminum powder is 1 μm-10 μm.

[0024] Optionally, the sintering temperature is 400° C.-500° C., and the sintering time is 1 h-2 h.

[0025] Optionally, the volume content of oxygen in the inert gas and oxygen-containing atmosphere is 3%-5%;

[0026] The inert gas includes argon and / or helium.

[0027] Optionally, the pulse voltage of the electric explosion is 3kV-6kV, and the current density is 10 6 A / cm 2 -10 8 A / cm 2 , the powder feeding rate is 150g / h-180g / h.

[0028] Optionally, the laser annealing is performed using a laser pulse, and the power density of the laser pulse is 1×10 5 W / cm 2 -1.5×10 5 W / cm 2 , repetition frequency is 10Hz-20Hz, temperature is 800℃-1000℃, heating rate is 1.0×10 3 K / s-1.2×10 3 K / s, holding time 20s-30s.

[0029] In a second aspect, the present application provides a nano-cubic lithium lanthanum zirconium oxide, which is prepared by the preparation method of the nano-cubic lithium lanthanum zirconium oxide.

[0030] The third aspect of the present application provides a solid electrolyte comprising the nano cubic phase lithium lanthanum zirconium oxide.

[0031] Compared with the prior art, the advantages of this application include:

[0032] The preparation method of nano cubic lithium lanthanum zirconium oxide provided by the present application first realizes multi-element atomic-level mixing by combining precursor spray drying with electric explosion instantaneous reaction. During the spray drying process, a homogeneous molecular-level solution of metal salt and complexing agent is atomized into 10-100 μm droplets through a nozzle. The droplets are heated in a hot air flow of 200-300 ° C for 10 - ³-10 - Dehydration occurs within 2 seconds to form porous microspheres, where metal ions are fixed in the complex network, suppressing element segregation and achieving spatial locking of stoichiometry at the micron scale. During the electric explosion process, ultra-high power pulse current is applied to the spray-dried microspheres, causing the plasma elements in the system to be randomly distributed within the electron mean free path. After ultra-fast cooling, atomic diffusion is suppressed, leaving no room for atomic segregation. Secondly, annealing in an inert gas and oxygen-containing atmosphere can effectively suppress lithium volatilization and promote the formation of a cubic phase. This is because some of the LLZO powders generated by the electric explosion method are mainly tetragonal lithium lanthanum zirconium oxide (t-LLZO) (low ionic conductivity). The ultra-fast heating of laser annealing quickly overcomes the phase transition energy barrier from the tetragonal phase to the cubic phase (c-LLZO), promoting the formation of the cubic phase, and the short-term laser heating limits the Li + The diffusion distance is shortened to avoid the composition segregation caused by Li volatilization in traditional annealing; finally, the particle size of the nano cubic lithium lanthanum zirconium oxide powder reaches the nanometer level and is evenly distributed through electric explosion.

[0033] The nano cubic lithium lanthanum zirconium oxide provided by the present application has no impurity phase generation and high ionic conductivity, resulting in good electrical conductivity.

[0034] The solid electrolyte provided in this application has excellent conductive properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0036] Figure 1 This is an SEM image of the nano-cubic lithium lanthanum zirconium oxide provided in Example 1;

[0037] Figure 2 The XRD patterns of Example 1 and Comparative Examples 1-5 are shown. DETAILED DESCRIPTION

[0038] As used herein:

[0039] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0040] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0041] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0042] In these examples, parts and percentages are by mass unless otherwise indicated.

[0043] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. For example, if we say that the parts by mass of component A are a parts and the parts by mass of component B are b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the parts by mass of all components is not limited to 100 parts.

[0044] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0045] It should be noted that the particle size of industrialized nano-LLZO on the market is mostly micron-level. Even if it reaches the nanometer level, the particle size is still in the range of 200-500nm. This particle size belongs to the submicron level, and the particle stacking gap size is large. At high temperatures, the grain boundary migration rate is greater than the pore shrinkage rate, which will form pore defects and lead to a decrease in ionic conductivity. In addition, the interface resistance of submicron-level LLZO is high, the interface compatibility is poor, and the energy density of the prepared battery is low. Nano-level LLZO less than 50nm can effectively improve the electrochemical performance. Therefore, how to prepare lithium lanthanum zirconium oxide of 50nm and below is a technical problem that needs to be solved urgently.

[0046] The first aspect of the present application provides a method for preparing nano cubic lithium lanthanum zirconium oxide, comprising:

[0047] mixing a lithium source, a lanthanum source, a zirconium source, a solvent, and a complexing agent to obtain a first mixture, and spray-drying the first mixture to obtain micron-sized precursor particles;

[0048] Sintering the micron-sized precursor particles to obtain lithium lanthanum zirconium aluminum oxide precursor powder;

[0049] The lithium lanthanum zirconium aluminum oxide precursor powder and aluminum powder are mixed to obtain a second mixture, and the second mixture is subjected to electric explosion and laser annealing in an inert gas and oxygen-containing atmosphere to obtain nano cubic lithium lanthanum zirconium oxide.

[0050] It should be noted that aluminum powder can not only enhance the conductivity of powder, but also be doped. The entry of Al replaces Li, making Li + At the position where the tetrahedron and octahedron of the unit cell are connected, Li + The transmission bridge is built. At the same time, the vacancy in the lattice increases, the lithium ion arrangement is disordered, which is conducive to ion migration. The LLZO crystal structure transforms from the tetragonal phase with poor conductivity to the cubic phase with better conductivity. Therefore, Al doping utilizes the high valence to form lithium vacancies, which also plays a role in stabilizing the LLZO cubic phase and improving the conductivity.

[0051] In some embodiments, the particle size of the nano-cubic lithium lanthanum zirconium oxide is 10 nm to 50 nm.

[0052] Optionally, the particle size of the nano-cubic lithium lanthanum zirconium oxide can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm or any value between 10 nm and 50 nm.

[0053] In some embodiments, the method for preparing nano cubic lithium lanthanum zirconium oxide satisfies at least one of the following conditions:

[0054] A. the lithium source comprises one or more of lithium carbonate, lithium hydroxide, lithium nitrate and lithium acetate;

[0055] B. the lanthanum source comprises one or more of lanthanum oxide, lanthanum nitrate and lanthanum acetate;

[0056] C. the zirconium source comprises one or more of zirconium oxychloride, zirconium nitrate and zirconium isopropoxide;

[0057] D. the solvent comprises water;

[0058] E. The complexing agent includes one or more of ethylenediaminetetraacetic acid, citric acid and tartaric acid.

[0059] It should be noted that the complexing agent complexes with metal ions, thereby improving the uniformity of the precursor, and after low-temperature sintering of LLZO, the residual carbon skeleton of the complexing agent can enhance the electrical conductivity and reduce the initiation threshold during electric explosion.

[0060] In some embodiments, the method for preparing nano cubic lithium lanthanum zirconium oxide satisfies at least one of the following conditions:

[0061] A. The molar ratio of Li in the lithium source, the lanthanide in the lanthanum source, and the zirconium in the zirconium source is 7.3-7.8:3:2;

[0062] Optionally, the molar ratio of Li in the lithium source, the lanthanide in the lanthanum source, and the zirconium in the zirconium source can be 7.3:3:2, 7.4:3:2, 7.5:3:2, 7.6:3:2, 7.7:3:2, 7.8:3:2, or any value between 7.3 and 7.8:3:2;

[0063] B. the molar ratio of the total metal ions in the first mixture, the solvent and the complexing agent is 1:1.2-1.5:50-80;

[0064] Optionally, the molar ratio of the total metal ions, the solvent, and the complexing agent in the first mixture may be 1:1.2:50, 1:1.3:50, 1:1.4:50, 1:1.5:50, 1:1.2:60, 1:1.2:70, 1:1.2:80, 1:1.5:80, or any value between 1:1.2-1.5:50-80;

[0065] C. The mass ratio of the lithium lanthanum zirconium aluminum oxide precursor powder to the aluminum powder is 4-6:1;

[0066] Optionally, the mass ratio of the lithium lanthanum zirconium aluminum oxide precursor powder to the aluminum powder can be 4:1, 5:1, 6:1 or any value between 4 and 6:1;

[0067] It should be noted that when the mass ratio of lithium lanthanum zirconium aluminum oxide precursor powder to aluminum powder is lower than 4:1, the excessive aluminum content will generate impurities such as lanthanum aluminate and lithium aluminate, reducing the electrical conductivity of LLZO. When the mass ratio is higher than 6:1, the aluminum content is too low, which has a poor effect on improving the conductivity of the powder and the subsequent electric explosion synthesis of LLZO stabilizing the cubic phase.

[0068] D. The particle size of the aluminum powder is 1 μm-10 μm.

[0069] Optionally, the particle size of the aluminum powder may be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any value between 1 μm and 10 μm.

[0070] It should be noted that when the particle size is less than 1 μm, aluminum powder is extremely dangerous to handle in the air and is prone to spontaneous combustion or even explosion. When the particle size of aluminum powder is greater than 10 μm, the specific surface area is small, making it difficult to heat and explode quickly, and the effect of promoting the electro-explosion synthesis of LLZO is not good.

[0071] In some embodiments, the sintering temperature is 400° C.-500° C., and the sintering time is 1 h-2 h.

[0072] Optionally, the sintering temperature may be 400° C., 450° C., 500° C., or any value between 400° C. and 500° C., and the sintering time may be 1 h, 1.5 h, 2 h, or any value between 1 h and 2 h.

[0073] In some embodiments, the volume content of oxygen in the inert gas and oxygen-containing atmosphere is 3%-5%;

[0074] Optionally, the volume content of oxygen may be 3%, 4%, 5%, or any value between 3% and 5%;

[0075] It should be noted that an appropriate amount of O2 can form Li-O bonds, slowing down the volatilization rate of lithium and making Li + Maintain stability and participate in lattice construction;

[0076] The inert gas includes argon and / or helium.

[0077] In some embodiments, the pulse voltage of the electric explosion is 3kV-6kV, and the current density is 10 6 A / cm 2 -10 8 A / cm 2 , the powder feeding rate is 150g / h-180g / h.

[0078] Optionally, the pulse voltage of the electric explosion can be 3kV, 4kV, 5kV, 6kV or any value between 3kV and 6kV, and the current density can be 10 6 A / cm 2 , 10 7 A / cm 2 , 10 8 A / cm 2 or 10 6 A / cm 2 -10 8 A / cm 2 The powder feeding rate can be 150g / h, 160g / h, 170g / h, 180g / h or any value between 150g / h and 180g / h.

[0079] It should be noted that when the relevant parameters of the electric explosion are set within the above range, the lithium lanthanum zirconium aluminum oxide precursor powder and the aluminum powder can be evenly dispersed to avoid accumulation leading to incoherent explosion or energy fluctuation.

[0080] In some embodiments, the laser annealing is performed using a laser pulse, and the power density of the laser pulse is 1×10 5 W / cm 2 -1.5×10 5 W / cm 2 , repetition frequency is 10Hz-20Hz, temperature is 800℃-1000℃, heating rate is 1.0×10 3 K / s-1.2×10 3 K / s, holding time 20s-30s.

[0081] Optionally, the power density of the laser pulse can be 1×10 5 W / cm 2 , 1.1×10 5 W / cm 2 , 1.2×10 5 W / cm 2 , 1.3×10 5 W / cm 2 , 1.4×10 5 W / cm 2 , 1.5×10 5 W / cm 2 or 1×10 5 W / cm 2 -1.5×10 5 W / cm 2The repetition frequency can be 10 Hz, 15 Hz, 20 Hz or any value between 10 Hz and 20 Hz. The temperature can be 800 ° C, 900 ° C, 1000 ° C or any value between 800 ° C and 1000 ° C. The heating rate can be 1.0 × 10 3 K / s, 1.1×10 3 K / s, 1.2×10 3 K / s or 1.0×10 3 K / s-1.2×10 3 K / s, and the holding time can be 20s, 25s, 30s or any value between 20s-30s.

[0082] In some embodiments, a laser-assisted heating module is added to the reaction chamber to perform in-situ short-term annealing on the powder after electric explosion. Laser-assisted heating can achieve the following effects through the synergistic effect of ultrafast high-temperature field (thermodynamics) and local atomic migration (kinetics): phase change regulation, breaking through the cubic phase nucleation barrier in milliseconds, inhibiting Li volatilization and impurity phase; defect repair, selectively eliminating lithium vacancies and interstitial Li + and grain boundary dislocations, optimizing Li + transmission channel;

[0083] Laser annealing solves the contradiction between Li loss, grain coarsening and defect residue in traditional annealing, and provides a new way for the controllable preparation of high-performance LLZO solid electrolytes; trace oxygen can promote the formation of molten alumina in aluminum powder during electric explosion, which can inhibit lithium volatilization, and at the same time Al 3+ Doping into LLZO promotes the formation of cubic phase; on the other hand, trace amounts of O2 fill oxygen vacancies and slow down the volatilization rate of lithium by forming Li-O bonds, making Li + Maintain stability and participate in lattice construction to stabilize the cubic phase.

[0084] It should also be noted that when the electric explosion temperature is controlled at 800℃-1000℃, the formation of cubic phase can be ensured; when the heating rate is 1.0×10 3 K / s-1.2×10 3 K / s, the grain growth can be inhibited; when the holding time is 20-30s, the decomposition of the cubic phase can be prevented.

[0085] In a second aspect, the present application provides a nano-cubic lithium lanthanum zirconium oxide, which is prepared by the preparation method of the nano-cubic lithium lanthanum zirconium oxide.

[0086] The third aspect of the present application provides a solid electrolyte comprising the nano cubic phase lithium lanthanum zirconium oxide.

[0087] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0088] Example 1

[0089] This embodiment provides a nano cubic phase lithium lanthanum zirconium oxide and a preparation method thereof, and the specific preparation steps are as follows:

[0090] S1: mixing a lithium source (lithium carbonate), a lanthanum source (lanthanum nitrate), a zirconium source (zirconium oxychloride), water, and a complexing agent (citric acid), and spray-drying the resulting mixture to obtain micron-sized precursor particles; wherein the molar ratio of Li in the lithium source, the lanthanide element in the lanthanum source, and the zirconium in the zirconium source is 7.5:3:2, and the molar ratio of the total metal ions, water, and complexing agent in the mixture is 1:1.3:60;

[0091] S2: Sintering the micron-sized precursor particles to obtain lithium lanthanum zirconium aluminum oxide precursor powder, obtaining lithium lanthanum zirconium aluminum oxide precursor powder, the sintering temperature is 450° C., and the sintering time is 2 hours;

[0092] S3: Mix the lithium lanthanum zirconium aluminum oxide precursor powder and aluminum powder (particle size of 1μm-10μm) in a mass ratio of 4:1, load the mixture into the high-voltage reaction chamber of the electric explosion device, and introduce inert gas and trace oxygen (volume content of 3%) into the chamber. Set the pulse voltage to 6kV and the current density to 10 6 A / cm 2 , the powder feeding rate is 150g / h, and the precursor is instantly vaporized and quickly condensed by electric explosion to form nano-scale LLZO primary powder;

[0093] S4: A laser-assisted heating module was added to the reaction chamber to perform laser in-situ short-term annealing on the nano-scale LLZO primary powder after electric explosion to obtain nano-cubic lithium lanthanum zirconium oxide. The power density of the annealing laser pulse was 1×10 5 W / cm 2 , repetition frequency is 15 Hz, temperature is 800 °C, heating rate is 1.0 × 10 3 K / s, holding time 20s.

[0094] The SEM of the nano cubic lithium lanthanum zirconium oxide is as follows Figure 1 shown.

[0095] Example 2

[0096] The difference from Example 1 is that the pulse voltage of the electric explosion is 3kV and the current density is 108 A / cm 2 , the powder feeding rate is 180g / h.

[0097] Example 3

[0098] The difference from Example 1 is that the power density of the annealing laser pulse is 1.5×10 5 W / cm 2 , repetition frequency is 20 Hz, temperature is 1000℃, heating rate is 1.2×10 3 K / s, holding time 30s.

[0099] Comparative Example 1

[0100] The difference from Example 1 is that no complexing agent is added.

[0101] Comparative Example 2

[0102] The difference from Example 1 is that no aluminum powder is added.

[0103] Comparative Example 3

[0104] The difference from Example 1 is that the electric explosion is replaced by a solid phase method, which specifically includes:

[0105] Lithium carbonate, lanthanum oxide, zirconium oxide and aluminum oxide are fully and evenly mixed to obtain a mixture, and the mixture is calcined at a high temperature (temperature of 1300° C., time of 20 hours) to obtain lithium lanthanum zirconium oxide.

[0106] Comparative Example 4

[0107] The difference from Example 1 is that no laser annealing is performed.

[0108] Comparative Example 5

[0109] The difference from Example 1 is that when the electric explosion is carried out, oxygen is not introduced and the process is carried out in an inert atmosphere.

[0110] The particle sizes of the lithium lanthanum zirconium oxide prepared in the above examples and comparative examples are shown in Table 1.

[0111] Table 1 Particle size

[0112]

[0113] The lithium lanthanum zirconium oxide and carbon material graphene prepared in the above examples and comparative examples were respectively placed in a tube furnace at a mass ratio of 100:0.25, and heat treated in an argon environment at 1150°C for 12 hours with a heating rate of 10°C / min. After the heat treatment, the sample was placed in a tube furnace for natural cooling. During the cooling process, argon gas must be kept flowing to prevent the sample from being oxidized at high temperature. After cooling, the heat-treated powder was ultrasonically dispersed to avoid agglomeration. The ultrasonic powder was placed in a mold for uniaxial tableting, and the obtained solid electrolyte ceramic sheet was sintered at high temperature under argon. The reaction conditions were 1150°C, the sintering time was 10 hours, and the heating rate was 4°C / min. The cooled solid electrolyte ceramic sheet was polished to make its surface smooth, and then the prepared solid electrolyte ceramic sheet was used for conductivity testing. The specific test results are shown in Table 2.

[0114] Table 2 Conductivity test

[0115]

[0116] analyze:

[0117] From the above tests and Figure 2 From the XRD of lithium lanthanum zirconium oxide prepared in Example 1 and Comparative Examples 1-5, it can be seen that the particle sizes of Examples 1, 2, and 3 are all within 50 nm, and the electrical conductivity is higher than that of Comparative Examples 1-2 orders of magnitude; Example 1 is cubic phase LLZO and does not contain impurity phase; Failure to add a complexing agent will lead to uneven mixing of metal ions and component segregation, and the product will mostly be tetragonal phase LLZO and impurity phase with extremely low electrical conductivity; Failure to add aluminum powder will seriously affect the electrical conductivity of the electric explosion powder, and the presence of lanthanum zirconate impurity phase will affect the electrical conductivity; the LLZO particle size synthesized by the solid phase method is submicron, much higher than the particle size of the implementation case of this application, and lanthanum zirconate and impurity phase are present in XRD; without the laser annealing step, a small part of the tetragonal phase has not been transformed into the cubic phase, and the electrical conductivity is low; no oxygen is passed during the electric explosion, which will cause lithium to volatilize during the electric explosion, and the product will contain lanthanum zirconate impurity phase, which affects the conductivity. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0118] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and to form distinct embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is intended solely to enhance understanding of the overall background of this application and should not be construed as an admission or any implication that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing nano cubic lithium lanthanum zirconium oxide, characterized in that: include: mixing a lithium source, a lanthanum source, a zirconium source, a solvent, and a complexing agent to obtain a first mixture, and spray-drying the first mixture to obtain micron-sized precursor particles; Sintering the micron-sized precursor particles to obtain lithium lanthanum zirconium aluminum oxide precursor powder; The lithium lanthanum zirconium aluminum oxide precursor powder and aluminum powder are mixed to obtain a second mixture, and the second mixture is subjected to electric explosion and laser annealing in an inert gas and oxygen-containing atmosphere to obtain nano cubic lithium lanthanum zirconium oxide.

2. The method for preparing nano cubic lithium lanthanum zirconium oxide according to claim 1, characterized in that: The particle size of the nano cubic lithium lanthanum zirconium oxide is 10nm-50nm.

3. The method for preparing nano cubic lithium lanthanum zirconium oxide according to claim 1, characterized in that: At least one of the following conditions is met: A. the lithium source comprises one or more of lithium carbonate, lithium hydroxide, lithium nitrate and lithium acetate; B. the lanthanum source comprises one or more of lanthanum oxide, lanthanum nitrate and lanthanum acetate; C. the zirconium source comprises one or more of zirconium oxychloride, zirconium nitrate and zirconium isopropoxide; D. the solvent comprises water; E. The complexing agent includes one or more of ethylenediaminetetraacetic acid, citric acid and tartaric acid.

4. The method for preparing nano cubic lithium lanthanum zirconium oxide according to claim 1, characterized in that: At least one of the following conditions is met: A. The molar ratio of Li in the lithium source, the lanthanide in the lanthanum source, and the zirconium in the zirconium source is 7.3-7.8:3:2; B. the molar ratio of the total metal ions in the first mixture, the solvent and the complexing agent is 1:1.2-1.5:50-80; C. The mass ratio of the lithium lanthanum zirconium aluminum oxide precursor powder to the aluminum powder is 4-6:1; D. The particle size of the aluminum powder is 1 μm-10 μm.

5. The method for preparing nano cubic lithium lanthanum zirconium oxide according to claim 1, characterized in that: The sintering temperature is 400° C.-500° C., and the sintering time is 1 h-2 h.

6. The method for preparing nano cubic lithium lanthanum zirconium oxide according to claim 1, characterized in that: The volume content of oxygen in the inert gas and oxygen-containing atmosphere is 3%-5%; The inert gas includes argon and / or helium.

7. The method for preparing nano cubic lithium lanthanum zirconium oxide according to claim 1, characterized in that: The pulse voltage of the electric explosion is 3kV-6kV, and the current density is 10 6 A / cm 2 -10 8 A / cm 2 , the powder feeding rate is 150g / h-180g / h.

8. The method for preparing nano cubic lithium lanthanum zirconium oxide according to any one of claims 1 to 7, characterized in that: The laser annealing is performed using a laser pulse, the power density of the laser pulse is 1×10 5 W / cm 2 -1.5×10 5 W / cm 2 , repetition frequency is 10Hz-20Hz, temperature is 800℃-1000℃, heating rate is 1.0×10 3 K / s-1.2×10 3 K / s, holding time 20s-30s.

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