A lithium lanthanum zirconium oxide solid electrolyte material, a preparation method thereof, a solid electrolyte, and a solid-state lithium-ion battery

Abstract

The present invention provides a lithium lanthanum zirconium oxide solid electrolyte material, a preparation method thereof, a solid electrolyte, and a solid-state lithium-ion battery. The preparation method includes the following steps: S1, mixing a lithium source, an aluminum source, a lanthanum source, a zirconium source, and a dispersant A, drying, and then performing a first calcination treatment to obtain a calcined material; S2, mixing the calcined material with a CuI solution to obtain a mixed slurry, and then performing solid-liquid separation to obtain a liquid phase and a precursor material; S3, performing a second calcination treatment on the precursor to obtain a lithium lanthanum zirconium oxide solid electrolyte material. The lithium lanthanum zirconium oxide solid electrolyte material of the present invention can effectively solve the problem of poor chemical stability of the lithium lanthanum zirconium oxide solid electrolyte material in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of solid electrolytes, and more particularly, to a lithium lanthanum zirconium oxide solid electrolyte material, a preparation method thereof, a solid electrolyte, and a solid state lithium ion battery. Background Art

[0002] The emergence of new energy provides an important means for energy shortage and environmental protection. After continuous development, nowadays, new energy vehicles equipped with new energy batteries are everywhere on the streets. However, all new energy batteries currently used in the market are liquid batteries, which have the potential hazards of organic liquid leakage and thermal runaway inducing battery explosion and combustion.

[0003] Solid electrolytes have witnessed a research upsurge in recent decades due to their obvious safety advantages, and garnet-type materials have been widely studied. Li7La3Zr2O 12 (LLZO) compounds are divided into cubic phase and tetragonal phase. There are many lithium ion vacancies in the cubic phase crystals, making Li + migration easier, so the cubic phase has high ionic conductivity. However, researchers have also found that the cubic phase LLZO material will form Li2CO3 on the surface and grain boundaries after being exposed to air for a period of time. After the formation of Li2CO3, the total ionic conductivity of the LLZO solid electrolyte material decreases significantly, and the interface stability becomes poor. Therefore, people have gradually started to pay attention to the Li2CO3 problem on the surface of LLZO.

[0004] In view of this, it is necessary to invent a lithium lanthanum zirconium oxide (LLZO) solid electrolyte material with good chemical stability. Summary of the Invention

[0005] The main object of the present invention is to provide a lithium lanthanum zirconium oxide solid electrolyte material, a preparation method thereof, a solid electrolyte, and a solid state lithium ion battery, so as to solve the problem of poor chemical stability of the lithium lanthanum zirconium oxide (LLZO) solid electrolyte material in the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, a preparation method of a lithium lanthanum zirconium oxide solid electrolyte material is provided, and the preparation method includes the following steps:

[0007] S1, mixing a lithium source, an aluminum source, a lanthanum source, a zirconium source and a dispersant A, drying, and then performing a first calcination treatment to obtain a calcined material;

[0008] S2, mixing the calcined material with a CuI solution to obtain a mixed slurry, and then performing solid-liquid separation to obtain a liquid phase and a precursor material;

[0009] S3, performing a second calcination treatment on the precursor to obtain a lithium lanthanum zirconium oxide solid electrolyte material.

[0010] Furthermore, the CuI solution is prepared by the following preparation method:

[0011] Mix a copper halide, a chelating agent, a dispersant B, and a solvent A to obtain a first mixed solution; secondly, mix an alkali metal iodide with the first mixed solution to obtain a second mixed solution; then, subject the second mixed solution to a solvothermal reaction to obtain a CuI solution;

[0012] Among them, the copper halide is copper chloride and / or copper bromide.

[0013] Furthermore, the solvothermal reaction includes:

[0014] Heat-treat the second mixed solution to carry out a solvothermal reaction to obtain a CuI solution.

[0015] Furthermore, in the heat treatment, the temperature is 120-180°C, and the time of the heat treatment is 4-10 h.

[0016] Furthermore, the process of mixing the copper halide, the chelating agent, the dispersant B, and the solvent A is carried out at -10 to 5°C.

[0017] Furthermore, the molar ratio of the copper halide to the alkali metal iodide is 1:(1-1.05).

[0018] Furthermore, the molar ratio of the copper halide, the chelating agent, and the dispersant B is 1:(0.01-0.05):(0.02-0.05).

[0019] Furthermore, the weight ratio of the total weight of the copper halide, the chelating agent, and the dispersant B to the weight of the solvent B is (3-6):10.

[0020] Furthermore, the chelating agent is dimethylglyoxime and / or dithizone; preferably, the dispersant is sodium dodecylbenzenesulfonate and / or polyvinylpyrrolidone.

[0021] Furthermore, the weight ratio of the calcined material to the CuI solution is (1-5):100, preferably (2-3):100.

[0022] Furthermore, the dispersant A is an alcohol solvent, preferably ethanol and / or isopropanol.

[0023] Furthermore, the temperature of the first calcination treatment is 900-1100°C, and the time is 4-20 h.

[0024] Furthermore, the temperature of the second calcination treatment is 300-450°C, and the time is 2-6 h.

[0025] Further, the lithium source is one or more of lithium hydroxide, lithium carbonate, and lithium oxalate; preferably, the aluminum source is one or more of aluminum oxide, lithium carbonate, and aluminum dihydrogen phosphate; the lanthanum source is one or more of lanthanum trioxide, lanthanum nitrate, and lanthanum carbonate; preferably, the zirconium source is one or more of zirconium dioxide, zirconium nitrate, and zirconium carbonate.

[0026] Further, the molar ratio of the lithium source, aluminum source, lanthanum source, and zirconium source is Li:Al:La:Zr = (7 - 3x):x:3:(1.8 - 2); wherein, 0 < x ≤ 0.3.

[0027] To achieve the above object, according to one aspect of the present invention, there is provided a lithium lanthanum zirconium oxide solid electrolyte material prepared by the above preparation method.

[0028] According to another aspect of the present invention, there is provided a solid electrolyte, which comprises the above lithium lanthanum zirconium oxide solid electrolyte material.

[0029] According to another aspect of the present invention, there is provided a solid-state lithium ion battery, which comprises the above solid electrolyte.

[0030] By applying the technical solution of the present invention, a modified LLZO solid electrolyte material is obtained. In the present invention, the CuI material is uniformly coated on the surface of the LLZO material. In the modified LLZO material, the CuI coating layer has the effect of improving the ionic conductivity of the LLZO material. At the same time, the CuI material is a superhydrophobic material with a contact angle of 155°. The present invention utilizes its excellent hydrophobic performance to construct a modified LLZO material with a core-shell structure, achieving the effect of physically isolating moisture and air, fundamentally inhibiting the generation of lithium carbonate on the surface of the LLZO material, and further enabling the modified LLZO material to maintain good chemical stability at room temperature and adapt to large-scale continuous production under more extensive conditions. Specific Embodiments

[0031] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0032] To solve the above problems existing in the prior art, according to one aspect of the present invention, there is provided a preparation method of a lithium lanthanum zirconium oxide solid electrolyte material, and the preparation method comprises the following steps:

[0033] S1, mixing a lithium source, an aluminum source, a lanthanum source, a zirconium source, and a dispersant A, drying, and then performing a first calcination treatment to obtain a calcined material;

[0034] S2. Mix the calcined material with the CuI solution to obtain a mixed slurry, and then perform solid-liquid separation to obtain a liquid phase and a precursor material;

[0035] S3. Perform a second calcination treatment on the precursor to obtain a lithium lanthanum zirconium oxide solid electrolyte material.

[0036] Applying the technical solution of the present invention, a modified LLZO solid electrolyte material is obtained. In the present invention, the CuI material is uniformly coated on the surface of the LLZO material. In the modified LLZO material, the CuI coating layer has the effect of improving the ionic conductivity of the LLZO material. At the same time, the CuI material is a superhydrophobic material with a contact angle of 155°. The present invention utilizes its excellent hydrophobic performance to construct a modified LLZO material with a core-shell structure, achieving the effect of physically isolating moisture and air, fundamentally inhibiting the generation of lithium carbonate on the surface of the LLZO material, and thus enabling the modified LLZO material to maintain good chemical stability at room temperature and be able to adapt to large-scale continuous production under more extensive conditions.

[0037] Specifically, the CuI material prepared by this process has superhydrophobic ability. After coating the LLZO material, it can prevent the contact between water and the LLZO material and inhibit the formation of lithium carbonate on the surface of the LLZO material. It is precisely by utilizing this excellent hydrophobic property of CuI that the inventors have achieved an increase in the ionic conductivity of the LLZO material.

[0038] In a preferred embodiment, the CuI solution is prepared by the following preparation method:

[0039] Mix a copper halide, a chelating agent, a dispersant B, and a solvent A to obtain a first mixed solution; secondly, mix an alkali metal iodide with the first mixed solution to obtain a second mixed solution; then, subject the second mixed solution to a solvothermal reaction to obtain a CuI solution;

[0040] Among them, the copper halide is copper chloride and / or copper bromide.

[0041] Preparing the CuI solution in the above preferred manner can make the particle size of CuI be nanoscale, so that CuI is more uniformly coated on the surface of the LLZO material, and thus a lithium lanthanum zirconium oxide solid electrolyte material with more excellent chemical stability can be obtained.

[0042] In a preferred embodiment, the solvothermal reaction includes:

[0043] Heat the second mixed solution to perform a solvothermal reaction to obtain a CuI solution.

[0044] According to the above preferred method, it is beneficial to prepare nano-CuI materials, and it is more beneficial to improve the chemical stability and ionic conductivity of lithium lanthanum zirconium oxide solid electrolyte materials.

[0045] In actual operation, preferably, the pressure treatment is carried out in a high-pressure reactor. In actual operation, the pressure applied is formed by the steam generated in a closed container.

[0046] More preferably, after the solvothermal reaction is completed, the obtained CuI solution is cooled. Cooling the CuI solution is more beneficial for the subsequent mixing of CuI and the calcined material at room temperature.

[0047] In a preferred embodiment, the temperature in the heat treatment is 120 - 180 °C, and the time of the heat treatment is 4 - 10 h. Preferred above reaction conditions are more beneficial for the full occurrence of the solvothermal reaction.

[0048] In a preferred embodiment, the process of mixing copper halide, chelating agent, dispersant B and solvent A is carried out at -10 - 5 °C. In actual operation, the above preferred reaction conditions can be achieved by using an ice-water bath.

[0049] In actual operation, preferably, the copper halide, chelating agent and dispersant B are mixed by stirring for 1 - 2 h. Through sufficient stirring, the above materials can be better mixed, which is more beneficial for the full progress of the reaction.

[0050] In a preferred embodiment, the molar ratio of copper halide to alkali metal iodide is 1:(1 - 1.05). The above molar ratio is more beneficial for the full occurrence of the reaction. In actual operation, more preferably, the molar ratio of copper halide to alkali metal iodide is 1:1.05.

[0051] In a preferred embodiment, the molar ratio of copper halide, chelating agent to dispersant B is 1:(0.01 - 0.05):(0.02 - 0.05). The addition ratios of the above chelating agent and dispersant B can better make the generated CuI particles in the nano-scale, which is beneficial for subsequent coating to obtain LLZO materials with excellent chemical stability.

[0052] In a preferred embodiment, the weight ratio of the total weight of copper halide, chelating agent and dispersant B to the weight of solvent A is (3 - 6):10. Preferred above weight ratio is more beneficial for the full occurrence of the reaction.

[0053] In order to further reduce the size of the prepared CuI material, in a preferred embodiment, the chelating agent is dimethylglyoxime and / or dithizone; preferably, the dispersant B is sodium dodecylbenzenesulfonate and / or polyvinylpyrrolidone; preferably, the solvent A is an alcohol solvent, more preferably ethanol. The above chelating agent and dispersant B are more conducive to suppressing the agglomeration of secondary particles of the CuI material.

[0054] In a preferred embodiment, the weight ratio of the calcined material to the CuI solution is (1 - 5):100, preferably (2 - 3):100. The preferred weight ratio of the above calcined material to the CuI solution is more conducive to forming a coating layer with an appropriate thickness on the surface of LLZO by CuI, thereby being more conducive to improving the ionic conductivity of the LLZO material and having good chemical stability.

[0055] In actual operation, preferably, the calcined material and the CuI solution are mixed by ultrasonic means. The ultrasonic frequency is preferably 60 - 90 kHz, and the time is preferably 20 - 60 min. After the above treatment, it is more conducive to the full mixing of the calcined material and CuI, so that the coating of CuI is denser and more uniform.

[0056] In a preferred embodiment, the dispersant A is an alcohol solvent, preferably ethanol and / or isopropanol.

[0057] In order to carry out calcination more fully, in a preferred embodiment, the temperature of the first calcination treatment is 900 - 1100 °C, and the time is 4 - 20 h. Under the above preferred conditions, it is more conducive to obtaining a calcined material with high ionic conductivity.

[0058] In order to achieve coating more fully, in a preferred embodiment, the temperature of the second calcination treatment is 300 - 450 °C, and the time is 2 - 6 h. Under the above preferred calcination conditions, CuI can form a coating layer more fully, thereby better exerting its hydrophobic property and improving the ionic conductivity of the material.

[0059] In actual operation, preferably, before the second calcination treatment, the precursor is washed multiple times, preferably 3 times. Washing the precursor multiple times can wash away other impurities except the CuI material, thereby improving the coating efficiency of the LLZO material.

[0060] More preferably, after washing, the precursor is dried under vacuum conditions, and the drying conditions are 80 - 120 °C and the time is 2 - 6 h. Drying the precursor can remove the attached liquid, which is more conducive to the subsequent second calcination treatment.

[0061] In a preferred embodiment, the lithium source is one or more of lithium hydroxide, lithium carbonate, and lithium oxalate; preferably, the aluminum source is one or more of aluminum oxide, lithium carbonate, and aluminum dihydrogen phosphate; the lanthanum source is one or more of lanthanum trioxide, lanthanum nitrate, and lanthanum carbonate; preferably, the zirconium source is one or more of zirconium dioxide, zirconium nitrate, and zirconium carbonate. In actual operation, the lithium source, aluminum source, lanthanum source, and zirconium source are not limited to the above types, and those skilled in the art can adjust the specific type selection of the lithium source, aluminum source, lanthanum source, and zirconium source according to the actual application situation.

[0062] In a preferred embodiment, the molar ratio of the lithium source, aluminum source, lanthanum source, and zirconium source is Li:Al:La:Zr = (7 - 3x):x:3:(1.8 - 2); wherein, 0 < x ≤ 0.3. The above molar ratio is preferred, which is more conducive to obtaining LLZO materials with excellent ionic conductivity.

[0063] According to another aspect of the present invention, there is provided a lithium lanthanum zirconium oxide solid electrolyte material prepared by the above preparation method. The lithium lanthanum zirconium oxide solid electrolyte material has both good chemical stability and high ionic conductivity.

[0064] According to yet another aspect of the present invention, there is provided a solid electrolyte, which includes the above lithium lanthanum zirconium oxide solid electrolyte material. The solid electrolyte has good chemical stability and high ionic conductivity.

[0065] According to yet another aspect of the present invention, there is provided a solid-state lithium-ion battery, which includes the above solid electrolyte. The solid-state lithium-ion battery has good chemical stability and high ionic conductivity.

[0066] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0067] Example 1:

[0068] A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material includes the following steps:

[0069] S1. Weigh lithium hydroxide, aluminum oxide, lanthanum trioxide, and zirconium dioxide according to the stoichiometric ratio of Li:Al:La:Zr elements of 6.7:0.1:3:2, place them in absolute ethanol and stir evenly, dry at 80 °C for 2 h, and calcine at 800 °C for 6 h in an air atmosphere to obtain a calcined material;

[0070] S2. Under the condition of an ice-water bath at 0 °C, weigh out a mixed material of CuCl2, dimethylglyoxime, and sodium dodecylbenzenesulfonate according to a molar ratio of 1:0.02:0.03, put it into absolute ethanol, stir for 1 h, then add KI according to a Cu:I stoichiometric ratio of 1:1, stir well, transfer it to a high-pressure reactor, place it in an oven at 150 °C, and keep the temperature for 5 h; cool to obtain a CuI solution;

[0071] S3. Add the calcined material to the CuI solution. The mass ratio of the added calcined material to CuI is 100:2. Ultrasonic at 80 KHz for 30 min, wash and filter 3 times. After drying the filter cake at 85 °C for 2 h, a CuI-modified lithium lanthanum zirconium oxide solid electrolyte material is obtained.

[0072] Example 2:

[0073] A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material includes the following steps:

[0074] S1. Weigh out lithium oxalate, lanthanum nitrate, aluminum oxide, and zirconium dioxide according to a Li:Al:La:Zr stoichiometric ratio of 6.55:0.15:3:2, place them in isopropanol and stir evenly, dry at 85 °C for 4 h, and calcine at 750 °C for 8 h in an air atmosphere to obtain a calcined material;

[0075] S2. Under the condition of -10 °C, weigh out a mixed material of CuCl2, dimethylglyoxime, and polyvinylpyrrolidone according to a molar ratio of 1:0.015:0.02, put it into absolute ethanol, stir for 1.1 h, then add KI according to a Cu:I stoichiometric ratio of 1:1, stir well, transfer it to a high-pressure reactor, place it in an oven at 140 °C, and keep the temperature for 5 h; cool to obtain a CuI solution;

[0076] S3. Add the calcined material to the CuI solution. The mass ratio of the added calcined material to CuCl2 is 100:2. Ultrasonic at 75 KHz for 35 min, wash and filter 3 times. After drying the filter cake at 100 °C for 4 h, a CuI-modified lithium lanthanum zirconium oxide solid electrolyte material is obtained.

[0077] Example 3:

[0078] A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material includes the following steps:

[0079] S1. Weigh out lithium carbonate, lanthanum trioxide, aluminum oxide, and zirconium nitrate according to a Li:Al:La:Zr stoichiometric ratio of 6.1:0.3:3:2, place them in isopropanol and stir evenly, dry at 86 °C for 6 h, and calcine at 800 °C for 20 h in an air atmosphere to obtain a calcined material;

[0080] S2. Under the condition of 5 °C, weigh the mixed materials of CuCl2, dimethylglyoxime and sodium dodecylbenzenesulfonate according to the molar ratio of 1:0.02:0.015, put them into absolute ethanol, stir for 1.3 h, then add KI according to the stoichiometric ratio of Cu:I element of 1:1, stir well, transfer to a high-pressure reaction kettle, put it into an oven at 150 °C, and keep the temperature for 10 h; cool to obtain a CuI solution;

[0081] S3. Add the calcined lithium lanthanum zirconium oxide material to the CuI solution. The mass ratio of the added calcined material to CuCl2 is 100:5. Ultrasonic for 45 min at 80 KHz, wash and filter 3 times. After the filter cake is dried at 105 °C for 5 h, a CuI-modified lithium lanthanum zirconium oxide solid electrolyte material is obtained.

[0082] Example 4:

[0083] A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material, which includes the following steps:

[0084] S1. Weigh lithium oxalate, lanthanum nitrate, aluminum trioxide, and zirconium nitrate according to the stoichiometric ratio of Li:Al:La:Zr elements of 6.4:0.2:3:2, place them in absolute ethanol and stir evenly, dry at 100 °C for 6 h, and calcine at 900 °C for 4 h under an air atmosphere to obtain a calcined material;

[0085] S2. Under the condition of an ice-water bath at 0 °C, weigh the mixed materials of CuCl2, dimethylglyoxime and polyvinylpyrrolidone according to the molar ratio of 1:0.05:0.02, put them into absolute ethanol, stir for 2 h, then add KI according to the stoichiometric ratio of Cu:I element of 1:1, stir well, transfer to a high-pressure reaction kettle, put it into an oven at 180 °C, and keep the temperature for 10 h; cool to obtain a CuI solution;

[0086] S3. Add the calcined material to the CuI solution. The mass ratio of the added calcined material to CuCl2 is 100:4. Ultrasonic for 20 min at 90 KHz, wash and filter 3 times. After the filter cake is dried at 80 °C for 5 h, a CuI-modified lithium lanthanum zirconium oxide solid electrolyte material is obtained.

[0087] Example 5:

[0088] A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material, which includes the following steps:

[0089] S1. Weigh lithium carbonate, lanthanum nitrate, aluminum trioxide, and zirconium nitrate according to the stoichiometric ratio of Li:Al:La:Zr elements of 6.25:0.25:3:2, place them in isopropyl alcohol and stir evenly, dry at 80 °C for 6 h, and calcine at 850 °C for 10 h under an air atmosphere to obtain a calcined material;

[0090] S2. Under the condition of an ice-water bath at 0 °C, weigh the mixed materials of CuCl2, dimethylglyoxime, and sodium dodecylbenzenesulfonate according to a molar ratio of 1:0.03:0.05, put them into absolute ethanol, stir for 2 h, then add KI according to a Cu:I stoichiometric ratio of 1:1, stir well, transfer to a high-pressure reaction kettle, place it in an oven at 120 °C, and keep warm for 6 h; cool to obtain a CuI solution;

[0091] S3. Add the calcined material to the CuI solution. The mass ratio of the added calcined material to CuCl2 is 100:4. Ultrasonic at 60 kHz for 60 min, wash and filter 3 times. After drying the filter cake at 100 °C for 4 h, a CuI-modified lithium lanthanum zirconium oxide solid electrolyte material is obtained.

[0092] Example 6:

[0093] A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material, which includes the following steps:

[0094] S1. Weigh lithium hydroxide, lanthanum nitrate, aluminum oxide, and zirconium dioxide according to a Li:Al:La:Zr stoichiometric ratio of 6.4:0.2:3:2, place them in isopropanol and stir evenly, dry at 95 °C for 4 h, and calcine at 800 °C for 5 h in an air atmosphere to obtain a calcined material;

[0095] S2. Under the condition of an ice-water bath at 0 °C, weigh the mixed materials of CuCl2, dimethylglyoxime, and polyvinylpyrrolidone according to a molar ratio of 1:0.03:0.02, put them into absolute ethanol, stir for 1 h, then add KI according to a Cu:I stoichiometric ratio of 1:1, stir well, transfer to a high-pressure reaction kettle, place it in an oven at 140 °C, and keep warm for 5 h; cool to obtain a CuI solution;

[0096] S3. Add the calcined material to the CuI solution. The mass ratio of the added calcined material to CuCl2 is 100:3. Ultrasonic at 75 kHz for 50 min, wash and filter 3 times. After drying the filter cake at 120 °C for 3 h, a CuI-modified lithium lanthanum zirconium oxide solid electrolyte material is obtained.

[0097] Example 7:

[0098] A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material, which includes the following steps:

[0099] S1. Weigh lithium hydroxide, lanthanum nitrate, aluminum oxide, and zirconium dioxide according to a Li:Al:La:Zr stoichiometric ratio of 6.4:0.2:3:2, place them in isopropanol and stir evenly, dry at 95 °C for 4 h, and calcine at 800 °C for 5 h in an air atmosphere to obtain a calcined material;

[0100] S2. Under the condition of an ice-water bath at 0 °C, weigh CuCl₂ and absolute ethanol according to a weight ratio of 5:10, stir for 1 h, then add KI according to the Cu:I element stoichiometric ratio of 1:1, stir well, transfer to a high-pressure reactor, place in an oven at 140 °C, and keep warm for 5 h; cool to obtain a CuI solution;

[0101] S3. Add the calcined material to the CuI solution. The mass ratio of the added calcined material to CuI is 100:3. Ultrasonic at 75 KHz for 50 min, wash and filter 3 times, and dry the filter cake at 120 °C for 3 h to obtain a CuI-modified lithium lanthanum zirconium oxide solid electrolyte material.

[0102] Comparative Example 1:

[0103] Weigh lithium hydroxide, aluminum oxide, lanthanum oxide, and zirconium dioxide according to the Li:Al:La:Zr element stoichiometric ratio of 6.7:0.1:3:2, place them in absolute ethanol and stir evenly, dry at 80 °C for 2 h, and calcine at 800 °C for 6 h in an air atmosphere to obtain a lithium lanthanum zirconium oxide material.

[0104] Comparative Example 2:

[0105] A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material includes the following steps:

[0106] S1. Weigh lithium hydroxide, aluminum oxide, lanthanum oxide, and zirconium dioxide according to the Li:Al:La:Zr element stoichiometric ratio of 6.7:0.1:3:2, place them in absolute ethanol and stir evenly, dry at 80 °C for 2 h, and calcine at 800 °C for 6 h in an air atmosphere to obtain a calcined material;

[0107] S2. After adding Fe₂O₃ powder to the ethanol solution, add the calcined material. The mass ratio of the added calcined material to Fe₂O₃ is 100:2. Ultrasonic at 80 KHz for 30 min, wash and filter, and dry the filter cake at 85 °C for 2 h to obtain an Fe₂O₃-modified lithium lanthanum zirconium oxide solid electrolyte material.

[0108] The test data of Examples 1-7 and Comparative Examples 1-2 are shown in Table 1.

[0109] Test method:

[0110] 1. Residual alkali after standing for three days:

[0111] 2. Ionic conductivity: Pressurize the prepared powder at 10 MPa for 2 min, then place it in a muffle furnace at 1100 °C and keep warm for 10 h. After cooling, spray gold on both sides of the tablet, and use an electrochemical workstation to test EIS, where the frequency range is (10 6 ~0.01) Hz, the amplitude is 10 mV, and the ionic conductivity of the material is calculated through the following formula:

[0112]

[0113] In the formula:

[0114] σ——ionic conductivity, unit: Siemens per centimeter (S / cm);

[0115] L——thickness of the sintered sample, unit: centimeter (cm);

[0116] π——takes the value of 3.14;

[0117] D——bottom diameter of the sintered sample, unit: centimeter (cm);

[0118] R1——fitted bulk impedance of the sample, unit: ohm (Ω);

[0119] R2——fitted grain boundary impedance of the sample, unit: ohm (Ω).

[0120] Table 1

[0121]

[0122] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0123] Compared with the LLZO materials without coating or coated with other materials, the residual alkali content of the LLZO materials of the present invention has been significantly reduced after being placed for three days, indicating its excellent hydrophobicity. At the same time, its ionic conductivity has also been greatly improved compared with the comparative example, and it has good market application prospects.

[0124] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a lithium lanthanum zirconium oxide solid electrolyte material, characterized in that, The preparation method includes the following steps: S1. Mix a lithium source, an aluminum source, a lanthanum source, a zirconium source, and dispersant A, dry them, and then conduct a first calcination treatment to obtain a calcined material; S2. Mix the calcined material with a CuI solution to obtain a mixed slurry, and then perform solid-liquid separation to obtain a liquid phase and a precursor material; S3. Conduct a second calcination treatment on the precursor to obtain the lithium lanthanum zirconium oxide solid electrolyte material.

2. The preparation method according to claim 1, wherein, The CuI solution is prepared by the following preparation method: Mix a copper halide, a chelating agent, dispersant B, and solvent A to obtain a first mixed solution; secondly, mix an alkali metal iodide with the first mixed solution to obtain a second mixed solution; then, subject the second mixed solution to a solvothermal reaction to obtain the CuI solution; Wherein, the copper halide is copper chloride and / or copper bromide.

3. The preparation method according to claim 2, wherein, The solvothermal reaction includes: Heat the second mixed solution to conduct the solvothermal reaction to obtain the CuI solution.

4. The preparation method according to claim 3, characterized in that, In the heating treatment, the temperature is 120-180°C, and the time of the heating treatment is 4-10h.

5. The preparation method according to claim 2, characterized in that, The process of mixing the copper halide, the chelating agent, dispersant B, and solvent A is carried out at -10 to 5°C.

6. The preparation method according to claim 2, characterized in that, The molar ratio of the copper halide to the alkali metal iodide is 1:(1-1.05).

7. The preparation method according to claim 2, characterized in that, The molar ratio of the copper halide, the chelating agent, and dispersant B is 1:(0.01-0.05):(0.02-0.05).

8. The preparation method according to claim 2, characterized in that, The weight ratio of the total weight of the copper halide, the chelating agent, and dispersant B to the weight of solvent A is (3-6):

10.

9. The preparation method according to claim 2, wherein The chelating agent is dimethylglyoxime and / or dithizone.

10. The preparation method according to claim 2, characterized in that, The dispersant B is sodium dodecylbenzenesulfonate and / or polyvinylpyrrolidone.

11. The preparation method according to claim 2, characterized in that, The solvent A is an alcohol solvent.

12. The preparation method according to claim 11, characterized in that, The solvent A is ethanol.

13. The preparation method according to any one of claims 1 to 12, characterized in that, The weight ratio of the calcined material to the CuI solution is (1-5):

100.

14. The preparation method according to any one of claims 1 to 12, characterized in that, The weight ratio of the calcined material to the CuI solution is (2-3):

100.

15. The preparation method according to any one of claims 1 to 12, characterized in that, The dispersant A is an alcohol solvent.

16. The preparation method according to claim 15, characterized in that, The dispersant A is ethanol and / or isopropanol.

17. The preparation method according to any one of claims 1 to 12, characterized in that, The temperature of the first calcination treatment is 900-1100°C, and the time is 4-20h.

18. The preparation method according to any one of claims 1 to 12, characterized in that, The temperature of the second calcination treatment is 300-450°C, and the time is 2-6h.

19. The preparation method according to any one of claims 1 to 12, characterized in that, The lithium source is one or more of lithium hydroxide, lithium carbonate, and lithium oxalate.

20. The preparation method according to any one of claims 1 to 12, characterized in that, The aluminum source is one or more of aluminum oxide, lithium carbonate, and aluminum dihydrogen phosphate.

21. The preparation method according to any one of claims 1 to 12, characterized in that, The lanthanum source is one or more of lanthanum oxide, lanthanum nitrate, and lanthanum carbonate.

22. The preparation method according to any one of claims 1 to 12, characterized in that, The zirconium source is one or more of zirconium dioxide, zirconium nitrate, and zirconium carbonate.

23. The preparation method according to any one of claims 1 to 12, characterized in that, The molar ratio of the lithium source, the aluminum source, the lanthanum source, and the zirconium source is Li:Al:La:Zr=(7-3x):x:3:(1.8-2); wherein, 0 < x ≤ 0.

3.

24. A lithium lanthanum zirconium oxide solid electrolyte material prepared by the preparation method according to any one of claims 1 to 23.

25. A solid electrolyte, characterized in that, The solid electrolyte includes the lithium lanthanum zirconium oxide solid electrolyte material according to claim 24.

26. A solid-state lithium-ion battery, characterized in that, The solid-state lithium-ion battery includes the solid electrolyte described in claim 25.

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