Oxide of garnet structure and method for its production and use

Abstract

In view of the problem of low ionic conductivity of LLZO prepared by existing heat preservation sintering, the application provides a garnet structure oxide and a preparation method and application thereof; the oxide material has a chemical composition represented by the following general formula (1): Li 7‑a‑3b‑ c Na a Ga b La3Zr 2‑c Ta c O 12 (1) wherein 0 The garnet structure oxide material provided by the application is doped with sodium, lanthanum, gallium, zirconium and / or tantalum metal, the oxide material is a multi-cation doped medium / high-entropy garnet structure oxide fast ionic conductor, and the ionic conductivity is high.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to an oxide with a garnet-type structure, its preparation method, and its application. Background Technology

[0002] Li7La3Zr2O 12 LLZO is an important inorganic material widely used in lithium-ion batteries. LLZO-based powders have the advantage of high ionic conductivity; in all-solid-state lithium-ion batteries, it can be used in solid electrolytes (in ceramic sheet form), inorganic-organic composite separators, polymeric film coatings (dispersed particle form), positive electrode material coatings, and negative electrode material ionic conductive agents. Given its versatility, expanding LLZO-based products has significant value in terms of product and technological accumulation.

[0003] As a key component of solid-state lithium metal batteries, garnet-type electrolyte Li7La3Zr2O 12 (LLZO) has been extensively studied. Generally, these electrolytes possess high strength, a wide electrochemical window, high thermal stability, and are easy to handle and use; their corresponding conductivity is typically 10⁻⁴ to 10⁻³ S cm⁻¹. -1 LLZO is typically prepared by high-temperature sintering, with the most common and low-cost method being atmospheric pressure sintering. The green blank is placed in a crucible (corundum, zirconium oxide, magnesium oxide, platinum, etc.) and heated to a set temperature in a conventional muffle furnace for holding and sintering. However, LLZO prepared by holding and sintering suffers from low ionic conductivity. Summary of the Invention

[0004] The technical problem to be solved by this invention is the low ionic conductivity of LLZO prepared by existing heat preservation sintering. This application provides an oxide with a garnet-type structure, its preparation method and application.

[0005] To solve the above-mentioned technical problems, the present invention provides an oxide material with a garnet-type structure, wherein the oxide material has a chemical composition represented by the following general formula (1):

[0006] Li 7-a-3b-c Na a Ga b La3Zr 2-c Ta c O 12 (1)

[0007] Where 0 < a < 0.2, 0 < b < 0.3, and 0 ≤ c < 0.5.

[0008] Preferably, the crystal space group of the oxide material is: One or two of them.

[0009] Preferably, the cell parameters of the crystal structure of the oxide material are as follows:

[0010] Preferably, the oxide material has diffraction peaks in the range of 15° to 16° and 33° to 35° in the X-ray diffraction peaks.

[0011] Preferably, the ionic conductivity σ of the oxide material is greater than 1.0 mS / cm.

[0012] Secondly, this application provides a method for preparing the above-described garnet-type oxide material, comprising the following steps:

[0013] According to the stoichiometric ratio in the general formula (1), the lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source are subjected to wet ball milling to obtain a precursor, and the precursor is subjected to a first sintering to obtain a first material;

[0014] The first material was subjected to wet ball milling again to obtain the second material;

[0015] The second material undergoes a first post-processing to obtain a sheet material, which is then sintered a second time to obtain the garnet-type oxide material.

[0016] Preferably, the precursor obtained by wet ball milling of lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source according to the stoichiometric ratio in the general formula (1) includes the following steps:

[0017] The lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source are obtained according to the stoichiometric ratio in the general formula (1), wherein the amount of lithium in the general formula (1) is x mol and the amount of lithium source added is 1.05 to 1.15x mol;

[0018] The lanthanum source was pretreated at 800℃~1000℃ for 5~12h.

[0019] The total material of lithium source, sodium source, gallium source, pretreated lanthanum source, zirconium source and / or tantalum source is added to a container containing ball milling beads and wet ball milling media for wet ball milling. After wet ball milling, the precursor is dried to obtain the precursor.

[0020] The rotation speed of the wet ball mill is 400-500 RPM, and the total duration of the wet ball mill is 12-24 hours.

[0021] The mass ratio of total material to milling beads is (3-5):1;

[0022] And / or, the wet ball milling media includes alcohol solvents;

[0023] And / or, the grinding balls include zirconia grinding balls.

[0024] Preferably, the lithium source includes one or more of LiOH-H2O, Li2CO3, and Li2O; the sodium source includes one or more of NaOH, Na2CO3, Na2O, NaCOOH, and CH3COONa.

[0025] The lanthanum source includes La2O3;

[0026] The zirconium source includes ZrO2;

[0027] The tantalum source includes Ta2O5;

[0028] The gallium source includes Ga2O3;

[0029] The temperature for the first sintering is 800–900℃, and the sintering time is 5–10 hours.

[0030] Preferably, the first post-processing includes the following steps: screening the second material into particles, then compressing it into tablets to obtain tablets, with a compression pressure of 200-800 MPa and a compression time of 1-5 min;

[0031] The second sintering of the sheet material includes the following steps: the sheet material is sintered a second time, which includes a first-step sintering and a second-step sintering.

[0032] The temperature of the first step sintering is 1000-1200℃, and the sintering time of the first step is 5-60 min;

[0033] The second-step sintering temperature is 950–1200℃, and the second-step sintering time is 60–600 min;

[0034] The heating rate for both the first-step sintering and the second-step sintering is 1–20 °C / min.

[0035] Secondly, this application provides the application of the oxide material with the garnet-type structure described above or the oxide material prepared by the preparation method of the oxide material with the garnet-type structure described above in lithium-ion batteries, lithium metal batteries, and solid-state batteries.

[0036] The garnet-type oxide material provided in this application is doped with sodium, lanthanum, gallium, zirconium and / or tantalum metals. The oxide material is a multi-cation-doped medium / high entropy garnet structure oxide fast ion conductor with high ionic conductivity.

[0037] Instruction manual with accompanying drawings

[0038] Figure 1These are the X-ray diffraction patterns of the garnet-type oxide materials prepared in Examples Z-1, Z-4, and Z-3.

[0039] Figure 2 Here is a SEM image of the garnet-type oxide material prepared in Example Z-4;

[0040] Figure 3 Here is a SEM image of the garnet-type oxide material prepared in Example Z-1;

[0041] Figure 4 Here is a SEM image of the garnet-type oxide material prepared in Example Z-3;

[0042] Figure 5 These are impedance test diagrams of the garnet-type oxide materials prepared in Examples Z-1, Z-4, and Z-3. Detailed Implementation

[0043] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] This application provides an oxide material with a garnet-type structure, the oxide material having a chemical composition represented by the following general formula (1):

[0045] Li 7-a-3b-c Na a Ga b La3Zr 2-c Ta c O 12 (1)

[0046] Where 0 < a < 0.2, 0 < b < 0.3, and 0 ≤ c < 0.5.

[0047] Specifically, when c is 0, there is no tantalum doping; when 0 < c < 0.5, there is tantalum doping.

[0048] The garnet-type oxide material provided in this application is doped with sodium, lanthanum, gallium, zirconium and / or tantalum metals. The oxide material is a multi-cation-doped medium / high entropy garnet structure oxide fast ion conductor with high ionic conductivity.

[0049] In some embodiments, the crystal space group of the oxide material is: One or two of them.

[0050] Specifically, the garnet-type oxide material provided in this application has a cubic LLZO crystal structure or is predominantly cubic LLZO, with space group [space group number missing]. At least one of them.

[0051] In some embodiments, the cell parameters of the crystal structure of the oxide material are:

[0052] Specifically, the length of edge a in the unit cell parameters of the crystal structure of garnet-type oxide materials is... Within the range.

[0053] In some embodiments, the 2θ of the X-ray diffraction peak of the oxide material has diffraction peaks in the ranges of 15° to 16° and 33° to 35°.

[0054] Possesses, such as Figure 1 The image shows several representative X-ray powder diffraction patterns (Si internal standard determination) of the garnet-type oxide material provided in this application. As the type or content of doping elements changes, new diffraction peaks appear in the 2θ diagram of the X-ray diffraction peaks of the garnet-type oxide material when the horizontal axis 2θ is within the range of 15°~16° and 33°~35°. This indicates that the garnet-type oxide material is doped with Na and Ga elements. As the doping amount of Na and Ga elements changes, the intensity of the new diffraction peaks changes or even disappears. It should be noted that the intensity change or disappearance of the new diffraction peaks does not have a clear linear relationship with the doping amount.

[0055] In some embodiments, the room temperature ionic conductivity σ of the oxide material is greater than 1.0 mS / cm.

[0056] Specifically, the room temperature ionic conductivity σ of the garnet-type oxide material provided in this application is greater than 1.0 mS / cm, which helps to improve the internal ionic conductivity of the battery and optimize the battery's electrochemical performance.

[0057] The room temperature is 25±5℃.

[0058] In some preferred embodiments, the ionic conductivity σ of the oxide material is in the range of 1.0 mS / cm < σ ≤ 5.0 mS / cm.

[0059] Secondly, this application provides a method for preparing the above-described garnet-type oxide material, comprising the following steps:

[0060] According to the stoichiometric ratio in the general formula (1), the lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source are subjected to wet ball milling to obtain a precursor, and the precursor is subjected to a first sintering to obtain a first material;

[0061] The first material was subjected to wet ball milling again to obtain the second material;

[0062] The second material is subjected to a first post-processing to obtain a sheet material, and the sheet material is subjected to a second sintering to obtain the oxide material with the garnet-type structure.

[0063] Specifically, according to general formula (1) Li 7-a-3b-c Na a Ga b La3Zr 2-c Ta c O 12 The stoichiometric ratios are used to obtain lithium, sodium, gallium, lanthanum, zirconium, and / or tantalum sources. The lithium, sodium, gallium, lanthanum, zirconium, and / or tantalum sources are first subjected to wet ball milling. The wet ball milling media thoroughly wets the particle surface, improving milling efficiency and also helping to more thoroughly and uniformly mix the lithium, sodium, gallium, lanthanum, zirconium, and / or tantalum sources.

[0064] The preparation method provided in this application yields a first material after the first sintering, which conforms to general formula (1). The first material is then subjected to wet ball milling again to obtain a second material, the wet ball milling process being the same as that in the precursor preparation steps described above. The prepared powder is then pressed into tablets, and the tablets are sintered a second time, which is beneficial for obtaining garnet-type oxide materials with high ionic conductivity.

[0065] In some embodiments, obtaining a precursor by wet ball milling of a lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source according to the stoichiometric ratio in the general formula (1) includes the following steps:

[0066] The lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source are obtained according to the stoichiometric ratio in the general formula (1), wherein the amount of lithium in the general formula (1) is x mol and the amount of lithium source added is 1.05 to 1.15x mol;

[0067] The lanthanum source was pretreated at a temperature of 800℃ to 1000℃ for 5 to 12 hours.

[0068] The total material consisting of lithium source, sodium source, gallium source, pretreated lanthanum source, zirconium source and / or tantalum source is added to a container containing ball milling beads and wet ball milling media for wet ball milling. After wet ball milling, the precursor is dried to obtain the precursor.

[0069] Specifically, in general formula (1), the amount of lithium is x mol, and the amount of lithium source added is 1.05 to 1.15 x mol; the purpose is to reduce the impact of Li volatilization on the chemical composition during high-temperature sintering. For example, the amount of lithium source added can be in the following ranges: 1.05 x mol to 1.08 x mol, 1.08 x mol to 1.10 x mol, 1.10 x mol to 1.12 x mol, or 1.12 x mol to 1.15 x mol.

[0070] Before preparing the precursor, the lanthanum source was pretreated to remove the influence of moisture on the synthesis product.

[0071] The pretreatment heating temperature is 800℃~1000℃, and the pretreatment heating time is 5~12h. If the pretreatment heating temperature is too low and / or the pretreatment heating time is too short, the moisture in the lanthanum source cannot be completely removed. If the pretreatment temperature is too high and / or the pretreatment heating time is too long, the preparation cost will increase.

[0072] Wet ball milling media can wet the particle surface, reduce the roughness of the particle surface, and further grind the particles, thereby improving ball milling efficiency.

[0073] After wet ball milling, the precursor is dried to obtain the precursor. The drying method can be oven drying, such as using a forced-air drying oven. However, other methods, such as microwave drying, can also be used.

[0074] In some preferred embodiments, the lanthanum source is pretreated at a heating temperature of 800°C to 900°C for 5 to 10 hours.

[0075] In some preferred embodiments, the lanthanum source is pretreated at a heating temperature of 900°C to 1000°C for 8 to 12 hours.

[0076] Specifically, within the aforementioned preferred range, it is more advantageous to quickly remove moisture from the lanthanum source and reduce the impact on the garnet-type oxide material of the synthesized product.

[0077] In some embodiments, the wet ball milling speed is 400-500 RPM, and the wet ball milling time is 12-24 hours;

[0078] The mass ratio of total material to milling beads is (3-5):1.

[0079] Specifically, wet ball milling operates at speeds between 400 and 500 RPM, effectively grinding and thoroughly mixing lithium, sodium, gallium, pretreated lanthanum, zirconium, and / or tantalum source particles. If the wet ball milling speed is too low, it affects raw material mixing and the sintering quality of the material. If the wet ball milling speed is too high, the preparation cost increases.

[0080] In some embodiments, the wet ball milling media includes alcohol solvents.

[0081] Specifically, alcohol solvents include isopropanol, ethanol, propanol, etc., with isopropanol being the preferred alcohol solvent.

[0082] In some embodiments, the grinding balls include zirconia grinding balls.

[0083] In some embodiments, the lithium source includes one or more of LiOH-H2O, Li2CO3, and Li2O.

[0084] In some embodiments, the sodium source includes one or more of NaOH, Na2CO3, Na2O, NaCOOH, and CH3COONa.

[0085] In some embodiments, the lanthanum source includes La2O3.

[0086] In some embodiments, the zirconium source includes ZrO2.

[0087] In some embodiments, the tantalum source includes Ta2O5.

[0088] In some embodiments, the gallium source includes Ga2O3.

[0089] In some embodiments, the temperature of the first sintering is 800–900°C, and the time of the first sintering is 5–10 hours.

[0090] Specifically, the precursor is sintered for the first time. The sintering temperature and time of the first sintering must meet the above-mentioned ranges. The first material obtained conforms to general formula (1). If the first sintering temperature is too low or / and the first sintering time is too short, the first material conforming to general formula (1) cannot be obtained. If the first sintering temperature is too high or / and the first sintering time is too long, the precursor will be oxidized, and the impurity content of the first material obtained will be too high.

[0091] Specifically, the precursor is sintered for the first time to obtain the first material; wherein, when the precursor is sintered for the first time, the precursor is further placed in a covered corundum crucible and sintered in a muffle furnace.

[0092] In some embodiments, the first post-processing includes the following steps: screening the second material into particles, followed by tableting to obtain tablet material, with a tableting pressure of 200-800 MPa and a tableting time of 1-5 min.

[0093] Specifically, the second material undergoes particle screening, including the following steps: passing the second material through a sieve with a mesh size of 40-200 mesh. Specifically, the mesh size can be one or more of 40, 80, 100, 150, and 200 mesh. The tableting pressure is specifically in the range of 200-800 MPa, which is beneficial for further compressing the second material into tablets to obtain a tablet-like material. If the tableting pressure is too low, the density of the tablets cannot be guaranteed. If the tableting pressure is too high, the cost increases.

[0094] In some embodiments, the second sintering of the sheet material includes the following steps: sintering the sheet material a second time, wherein the second sintering includes a first-step sintering and a second-step sintering.

[0095] The temperature of the first step sintering is 1000-1200℃, and the sintering time of the first step is 5-60 min;

[0096] The second-step sintering temperature is 950–1200℃, and the second-step sintering time is 60–600 min;

[0097] The heating rate for both the first-step sintering and the second-step sintering is 1–20 °C / min.

[0098] Specifically, the sheet material is subjected to a second sintering. The sheet material is further added to a container containing powder and master powder for a second sintering. The second sintering helps to improve the density of the garnet-type oxide material and achieve a garnet-type oxide material with high ionic conductivity.

[0099] Specifically, the sheet material is placed in a covered MgO crucible, a Pt crucible, or an MgO crucible containing a Pt support. The sheet material is sandwiched between the master powder and the spread powder in the crucible for sintering. The master powder and the spread powder are both garnet-structured oxide powders, and their specific compositions can be the same as those of the sheet material. The second sintering is a gradient sintering, with the temperature increased at a rate of 1–20 °C / min to the first-stage sintering platform. The temperature of the first-stage sintering is 1000–1200 °C, and the sintering time is 5–60 min. Subsequently, the temperature is increased at a rate of 1–20 °C / min to the second-stage sintering platform. The temperature of the second-stage sintering is 950–1200 °C, and the sintering time is 60–600 min. After sintering, the temperature can be reduced to room temperature by programmed temperature control or natural cooling for subsequent processing and testing. Specifically, the heating rate for the first stage sintering can be within the following ranges: 1℃ / min~5℃ / min, 5℃ / min~8℃ / min, 8℃ / min~12℃ / min, 12℃ / min~15℃ / min, 15℃ / min~18℃ / min, or 18℃ / min~20℃ / min. The heating rate for the second stage sintering can be within the following ranges: 1℃ / min~5℃ / min, 5℃ / min~8℃ / min, 8℃ / min~12℃ / min, 12℃ / min~15℃ / min, 15℃ / min~18℃ / min, or 18℃ / min~20℃ / min. The sintering temperature for the first stage can be 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, etc. The sintering temperature for the second stage can be 950℃, 980℃, 1000℃, 1050℃, 1090℃, 1100℃, 1150℃, 1170℃, 1200℃, etc.

[0100] Thirdly, this application provides the application of the oxide material with the garnet-type structure described above or the oxide material prepared by the preparation method of the oxide material with the garnet-type structure described above in lithium-ion batteries, lithium metal batteries, and solid-state batteries.

[0101] Specifically, the garnet-type oxide material provided in this application or the oxide material prepared by the above-described method for preparing garnet-type oxide materials can be used in lithium-ion batteries and lithium metal batteries as a positive electrode material coating layer (e.g., to promote ion transport within the electrode by mixing / coating with the electrode material) or as a negative electrode material ion transport medium (e.g., to promote ion transport within the electrode material by mixing with the electrode material); when applied to solid-state batteries, it can be used as an electrolyte, a composite electrode, or as a high-performance polymer composite electrolyte prepared by mixing with a polymer electrolyte, thereby improving the ionic conductivity of the electrolyte.

[0102] Fourthly, this application provides a method for preparing polymer composite electrolytes using garnet-type oxide materials, comprising the following steps:

[0103] Under an argon atmosphere, PEO and LiN(SO2CF3)2 were weighed according to an EO:Li molar ratio of (10-100):(1-10), and stirred in ACN (acetonitrile). After the mixture was stirred evenly, garnet-structured oxide material was added, and stirring was continued to obtain a composite slurry. The composite slurry was then coated onto a carrier mold, and after the solvent evaporated, a composite electrolyte was obtained. The total mass of PEO, LiN(SO2CF3)2, and ACN was m, and the garnet-structured oxide material was m1, with a m1:m ratio of (2-20):(100-500).

[0104] Fifthly, this application provides a method for using garnet-type oxide materials to prepare composite electrodes in solid-state batteries, comprising the following steps:

[0105] The electrode materials LiFePO4, Super-P, and garnet-type oxide materials are ground and mixed by low-speed ball milling in a mass ratio of (90-95):(2-3):(2-3) to obtain a composite electrode material. The resulting composite electrode can be directly pressed onto the electrolyte surface in powder form for battery assembly.

[0106] Alternatively, PEO and LiN(SO2CF3)2 can be stirred evenly in ACN (acetonitrile) to mix the electrode material, garnet-type oxide material, and conductive carbon, and continue stirring until a uniform electrode is formed. Then, the electrode is coated onto a template and dried for later use, or it can be directly coated onto the surface of an electrodeless ceramic electrolyte sheet for battery preparation.

[0107] The mass ratio of PEO, LiN(SO2CF3)2, and ACN is (10-100):(1-10):(200-500).

[0108] The mass ratio of electrode material, garnet-type oxide material, and conductive carbon is (90-95):(1-5):(1-5).

[0109] The present invention will be further illustrated by the following examples.

[0110] Specifically, this invention discloses the garnet-type oxide materials, their preparation methods, and applications.

[0111] The preparation method of garnet-type oxide materials includes the following steps:

[0112] Example Z-1

[0113] LiOH-H2O, Na2CO3, Ga2O3, La2O3, and ZrO2 are arranged according to Li 6.39 Na 0.01 Ga 0.2 La3Zr2O 12 Weigh the chemical formula according to the stoichiometric ratio. The amount of lithium in general formula (1) is 6.39 mol. The amount of LiOH-H2O added is 0.639 mol more than 6.39 mol to reduce the influence of Li volatilization on the chemical composition during high-temperature sintering. La2O3 is pretreated to remove the influence of water on the synthesis product. The pretreatment heating temperature is 950℃ and the pretreatment heating time is 10h.

[0114] The total material of LiOH-H2O, Na2CO3, Ga2O3, pretreated La2O3, and ZrO2 was added to a mill jar containing zirconia grinding beads and isopropanol as the wet grinding media for wet ball milling. The wet ball milling speed was 400 RPM, and the wet ball milling time was 12 hours. During the ball milling process, the material was allowed to stand for 5 minutes after every 10 minutes of milling. The mass ratio of the total material to the zirconia grinding beads was 3:1. The slurry obtained from the ball milling was poured into a pan and dried in a forced-air drying oven to obtain the precursor.

[0115] The precursor was further placed in a covered corundum crucible and sintered for the first time in a muffle furnace to obtain the first material; wherein the first sintering temperature was 800℃ and the first sintering time was 10h.

[0116] The first material is subjected to the same wet ball milling and drying steps again to obtain the second material.

[0117] The second batch of material is subjected to particle screening, passing through a sieve (200 mesh) for particle separation. The secondary powder selected from the 200-mesh sieve is then compressed into tablets under a pressure of 700 MPa to obtain tablet material.

[0118] The sheet material was then placed in a covered magnesium oxide crucible with a sandwich structure, embedded between the master powder and the powder layer, and transferred to a muffle furnace for a second sintering. The temperature was increased to the first-stage sintering platform at a rate of 5°C / min, with a first-stage sintering temperature of 1100°C and a first-stage sintering time of 60 min. Subsequently, the temperature was increased to the second-stage sintering platform at a rate of 5°C / min, with a second-stage sintering temperature of 1200°C and a second-stage sintering time of 600 min. After the second sintering, the temperature was reduced to room temperature by programmed temperature control or natural cooling to obtain the electrolyte ceramic sheet, which is the garnet-type oxide material.

[0119] Before conducting electrochemical tests, the obtained electrolyte ceramic sheet was polished with sandpaper of different grits until the surface was smooth, and gold sputtering was performed on the surface of the ceramic sheet to increase the electrical contact between the electrode current collector and the ceramic sheet.

[0120] Example Z-2

[0121] Example Z-2 is largely the same as Example Z-1, except that the chemical formula of the garnet-type oxide material is different, with a being 0.1, specifically Li. 6.3 Na 0.1 Ga 0.2 La3Zr2O 12 LiOH-H2O, Na2CO3, Ga2O3, La2O3, and ZrO2 are mixed according to Li 6.3 Na 0.1 Ga 0.2 La3Zr2O 12 Weigh the chemical formula according to the stoichiometric ratio; the remaining steps are the same as in Example Z-1.

[0122] Example Z-3

[0123] Example Z-3 is largely the same as Example Z-1, except that the chemical formula of the garnet-type oxide material is different, specifically Li 5.99 Na 0.01 Ga 0.2 La3Zr 1.6 Ta 0.4 O 12 Mix LiOH-H2O, Na2CO3, Ga2O3, Ta2O5, La2O3, and ZrO2 according to Li 5.99 Na 0.01 Ga 0.2 La3Zr 1.6 Ta 0.4 O 12 Weigh the chemical formula according to the stoichiometric ratio; the remaining steps are the same as in Example Z-1.

[0124] Example Z-4

[0125] Example Z-4 ​​is largely the same as Example Z-1, except that the chemical formula of the garnet-type oxide material is different, and b is 0.1, specifically Li. 6.69 Na 0.01 Ga 0.1 La3Zr2O 12 LiOH-H2O, Na2CO3, Ga2O3, La2O3, and ZrO2 are mixed according to Li 6.59 Na 0.01 La3Zr 1.6 Ta0.4 O 12 Weigh the chemical formula according to the stoichiometric ratio; the remaining steps are the same as in Example Z-1.

[0126] Example Z-5

[0127] Example Z-5 is largely the same as Example Z-1, except that the wet ball milling and drying steps described above are not repeated on the first batch of material; subsequent steps include particle screening, tableting, and a second sintering. The particle screening, tableting, and second sintering steps are the same as in Example Z-1. The remaining steps are the same as in Example Z-1.

[0128] Example Z-6

[0129] Example Z-6 is the same as Example Z-1 in most steps, except that the first sintering temperature is 900°C and the first sintering time is 5 hours. The remaining steps are the same as in Example Z-1.

[0130] Example Z-7

[0131] Example Z-7 is the same as Example Z-1 in most steps, except that the first sintering temperature is 700°C and the first sintering time is 10 hours. The remaining steps are the same as in Example Z-1.

[0132] Example Z-8

[0133] Example Z-8 is largely the same as Example Z-1, except that the temperature and time of the first sintering stage and the second sintering stage are different in the second sintering. Specifically, the temperature of the first sintering stage is 1200℃ and the time is 5 minutes, while the temperature of the second sintering stage is 1000℃ and the time is 180 minutes. The remaining steps are the same as in Example Z-1.

[0134] Example Z-9

[0135] Example Z-9 is the same as Example Z-1 in most steps, except that the tableting pressure is different, being 300 MPa. The remaining steps are the same as in Example Z-1.

[0136] Example Z-10

[0137] Example Z-10 is the same as Example Z-1 in most steps, except that the tableting pressure is different, being 100 MPa. The remaining steps are the same as in Example Z-1.

[0138] Example Z-11

[0139] Example Z-11 is the same as Example Z-1 in most steps, except that the second material is not subjected to particle screening. The remaining steps are the same as in Example Z-1.

[0140] Comparative Example Z-1

[0141] Comparative Example Z-1 is largely the same as Example Z-1, except that in Comparative Example Z-1, the garnet-type oxide material has 0 a and no Na2CO3 is added. Instead, LiOH-H2O, Ga2O3, La2O3, and ZrO2 are mixed according to the Li... 6.4 Ga 0.2 La3Zr2O 12 Weigh the chemical formula according to the stoichiometric ratio, and the remaining steps are the same as in Example Z-1.

[0142] Comparative Example Z-2

[0143] Comparative Example Z-2 is largely the same as Example Z-1, except that in Comparative Example Z-2, b is 0 in the garnet-type oxide material, and Ga2O3 is not added. Instead, LiOH-H2O, Na2CO3, La2O3, and ZrO2 are mixed according to the order of Li 6.99 Na 0.01 La3Zr2O 12 Weigh the chemical formula according to the stoichiometric ratio, and the remaining steps are the same as in Example Z-1.

[0144] Comparative Example Z-3

[0145] Comparative Example Z-3 is largely the same as Example Z-3, except that in Comparative Example Z-3, b is 0 in the garnet-type oxide material, and Ga2O3 is not added. Instead, LiOH-H2O, Na2CO3, Ta2O5, La2O3, and ZrO2 are prepared according to the order of Li 6.99 Na 0.01 La3Zr 1.6 Ta 0.4 O 12 Weigh the chemical formula according to the stoichiometric ratio, and the remaining steps are the same as in Example Z-3.

[0146] Comparative Example Z-4

[0147] Comparative Example Z-4 ​​is largely the same as Example Z-3, except that in Comparative Example Z-3, the garnet-type oxide material has 0 a and no Na2CO3 is added; instead, LiOH-H2O, Ga2O3, Ta2O5, La2O3, and ZrO2 are prepared according to Li6Ga 0.2 La3Zr 1.6 Ta 0.4 O 12Weigh the chemical formula according to the stoichiometric ratio, and the remaining steps are the same as in Example Z-3.

[0148] Comparative Example Z-5

[0149] Comparative Example Z-5 is largely the same as Example Z-1, except that in Comparative Example Z-1, the a value in the garnet-type oxide material is 0.2, and LiOH-H2O, Na2CO3, Ga2O3, La2O3, and ZrO2 are mixed according to the order of Li 6.2 Na 0.2 Ga 0.2 La3Zr2O 12 Weigh the chemical formula according to the stoichiometric ratio, and the remaining steps are the same as in Example Z-1.

[0150] Comparative Example Z-6

[0151] Comparative Example Z-6 is largely the same as Example Z-1, except that b is 0.3 in the garnet-type oxide material of Comparative Example Z-2, and LiOH-H2O, Na2CO3, Ga2O3, La2O3, and ZrO2 are arranged according to Li 6.09 Na 0.01 Ga 0.3 La3Zr2O 12 Weigh the chemical formula according to the stoichiometric ratio, and the remaining steps are the same as in Example Z-1.

[0152] Comparative Example Z-7

[0153] Comparative Example Z-7 is largely the same as Example Z-3, except that the chemical formula of the garnet-type oxide material is different, specifically Li 5.89 Na 0.01 Ga 0.2 La3Zr 1.5 Ta 0.5 O 12 Mix LiOH-H2O, Na2CO3, Ga2O3, Ta2O5, La2O3, and ZrO2 according to Li 5.89 Na 0.01 Ga 0.2 La3Zr 1.5 Ta 0.5 O 12 Weigh the chemical formula according to the stoichiometric ratio; the remaining steps are the same as in Example Z-1.

[0154] Examples of applications of garnet-type oxide materials are as follows:

[0155] Example Y-1

[0156] Under an argon atmosphere, PEO and LiN(SO2CF3)2 were weighed at an EO / Li molar ratio of 100:10 and stirred in ACN (acetonitrile). After thorough mixing, the garnet-structured oxide material prepared in Example Z-3 was added, and stirring continued to obtain a composite slurry. The composite slurry was then coated onto a carrier mold, and the composite electrolyte was obtained after the solvent evaporated. The total mass of PEO, LiN(SO2CF3)2, and ACN was m, and the garnet-structured oxide material was m1, with a m1:m ratio of 20:300. The ionic conductivity of this electrolyte membrane at 60℃ was 1.2 × 10⁻⁶. -3 S / cm

[0157] Example Y-2

[0158] A composite electrode material was obtained by grinding and low-speed ball milling LiFePO4, Super-P, and the garnet-type oxide material prepared in Example Z-1 at a mass ratio of 95:2:3. The resulting composite electrode can be directly pressed onto the electrolyte surface in powder form for battery assembly. This battery can stably cycle for more than 300 times at 0.2C rate and 60 degrees Celsius.

[0159] The garnet-type oxide materials prepared in Examples Z-1 to Z-11 and Comparative Examples Z1 to 7 were subjected to conductivity tests, crystal structure tests, cell parameters tests, and X-ray tests. The test results are recorded in Table 1.

[0160] For the solid-state battery prepared with the composite electrolyte obtained in Example Y-1, electrical performance tests were performed; for the solid-state battery prepared with the composite electrode obtained in Examples Y-2 to Y-3, electrical performance tests were performed.

[0161] Table 1

[0162]

[0163] As shown in Table 1, comparing Example Z-1 and Comparative Example Z-1, a is 0, indicating the oxide material contains neither sodium nor tantalum. Comparing Example Z-2 and Comparative Example Z-2, b is 0, indicating the oxide material contains neither gallium nor tantalum. The resulting garnet-type oxide material has low electrical conductivity. Comparing Comparative Examples Z-5 and Z-6 with Example Z-1, even with the addition of sodium and gallium, the oxide material still exhibits low electrical conductivity. Comparing Example Z-3 and Comparative Example Z-4, a is 0, indicating the oxide material contains no sodium. Comparing Example Z-3 and Comparative Example Z-4, b is 0, indicating the oxide material contains no gallium. Although Comparative Examples Z-3 and Z-4 added tantalum compared to Comparative Examples Z-1 and Z-2, the oxide material still exhibits low electrical conductivity. A comparison between Comparative Example Z-7 and Example Z-3 shows that even with the addition of tantalum, excessive tantalum content results in low conductivity of the oxide material. The above comparison illustrates that oxide materials have the following chemical composition represented by the general formula (1): Li 7-a-3b-c Na a Ga b La3Zr 2-c Ta c O 12 (1) Where 0 < a < 0.2, 0 < b < 0.3, 0 ≤ c < 0.5, the prepared oxide material with garnet-type structure doped with sodium, lanthanum, gallium, zirconium and / or tantalum metal has high ionic conductivity.

[0164] Examples Z-1 to Z-4 illustrate the oxide materials Li satisfying general formula (1). 7-a-3b-c Na a Ga b La3Zr 2-c Ta c O 12 (1) Where 0 < a < 0.2, 0 < b < 0.3, 0 ≤ c < 0.5, it has a high ionic conductivity. Comparing Example Z-1 and Example Z-5, in Example Z-5, the first material was not subjected to wet ball milling treatment, and the resulting oxide material had a lower ionic conductivity, indicating that wet ball milling treatment of the first material can increase the ionic conductivity of the oxide material.

[0165] A comparison of Examples Z-1, Z-6, and Z-7 shows that a first sintering temperature in the range of 800–900°C and a first sintering time in the range of 5–10 hours helps to improve the ionic conductivity of the oxide material. A comparison of Examples Z-1, Z-9, and Z-10 shows that when the material is pressed into tablets for the second time, excessively low pressing pressure reduces the ionic conductivity of the oxide material. This indicates that a pressing pressure in the range of 200–800 MPa yields oxide materials with higher ionic conductivity.

[0166] A comparison of Examples Z-1 and Z-11 demonstrates that performing particle screening on the second material helps improve the ionic conductivity of the oxide material.

[0167] The unit cell parameters of the crystal structure of the garnet-type oxide materials prepared in Examples Z-1 to Z-11 are as follows: Within this range, the 2θ of the X-ray diffraction peaks of the oxide material exhibits diffraction peaks in the ranges of 15°–16° and 33°–35°; for example... Figure 1 The X-ray diffraction patterns of the garnet-type oxide materials prepared in Examples Z-1, Z-3, and Z-4 show that diffraction peaks exist at 2θ within the ranges of 15°–16° and 33°–35°. The positions of the two diffraction peaks in Example 1 are 15.2° and 33.4°. Figure 2-4 It refers to the cross-sectional morphology of ceramic sheets formed by sintering garnet-type oxide materials, which varies with the type or content of doping elements.

[0168] Figure 5 These are the impedance test spectra of the oxide materials in Examples Z-1, Z-3, and Z-4. The prepared oxides have low impedance and high conductivity.

[0169] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A garnet-type oxide material, characterized in that, The oxide material has a chemical composition represented by the following general formula (1): Li 7-a-3b-c Na a Ga b La3Zr 2-c The c The 12 (1) Where 0 < a < 0.2, 0 < b < 0.3, and 0 ≤ c < 0.

5.

2. The garnet-type oxide material according to claim 1, characterized in that, The crystal space group of the oxide material is: , One or two of them.

3. The garnet-type oxide material according to claim 1 or 2, characterized in that, The unit cell parameters of the crystal structure of the oxide material are 12.95 Å < a < 13.20 Å.

4. The garnet-type oxide material according to claim 1, characterized in that, The oxide material exhibits diffraction peaks in the range of 15°~16° and 33°~35° in the 2θ range of X-ray diffraction.

5. The garnet-type oxide material according to claim 1, characterized in that, The ionic conductivity σ of the oxide material is greater than 1.0 mS / cm.

6. A method for preparing a garnet-type oxide material according to any one of claims 1-5, characterized in that, Includes the following steps: According to the stoichiometric ratio in the general formula (1), the lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source are subjected to wet ball milling to obtain a precursor, and the precursor is subjected to a first sintering to obtain a first material; The first material was subjected to wet ball milling again to obtain the second material; The second material undergoes a first post-processing to obtain a sheet material, which is then sintered a second time to obtain the garnet-type oxide material.

7. The method for preparing the garnet-type oxide material according to claim 6, characterized in that, The precursor is obtained by wet ball milling of lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source according to the stoichiometric ratio in the general formula (1), including the following steps: The lithium source, sodium source, gallium source, lanthanum source, zirconium source and / or tantalum source are obtained according to the stoichiometric ratio in the general formula (1), wherein the amount of lithium in the general formula (1) is x mol and the amount of lithium source added is 1.05x~1.15x; The lanthanum source was pretreated at a temperature of 800 ℃ ~ 1000 ℃ for 5 h ~ 12 h. The total material of lithium source, sodium source, gallium source, pretreated lanthanum source, zirconium source and / or tantalum source is added to a container containing ball milling beads and wet ball milling media for wet ball milling. After wet ball milling, the precursor is dried to obtain the precursor. The rotational speed of the wet ball mill is 400 ~ 500 RPM, and the total duration of the wet ball mill is 12 ~ 24 h; The mass ratio of total material to milling beads is (3 ~ 5): 1; And / or, the wet ball milling media includes alcohol solvents; And / or, the grinding balls include zirconia grinding balls.

8. The method for preparing the garnet-type oxide material according to claim 6, characterized in that, The lithium source includes one or more of LiOH-H2O, Li2CO3, and Li2O; The sodium source includes one or more of NaOH, Na2CO3, Na2O, NaCOOH, and CH3COONa; The lanthanum source includes La2O3; The zirconium source includes ZrO2; The tantalum source includes Ta2O5; The gallium source includes Ga2O3; The temperature for the first sintering is 800~900℃, and the sintering time is 5~10h.

9. The method for preparing the garnet-type oxide material according to claim 6, characterized in that, The first post-processing includes the following steps: the second material is subjected to particle screening, and then tableting is performed to obtain tablet material. The tableting pressure is 200~800MPa and the tableting time is 1~5min. The second sintering of the sheet material includes the following steps: the sheet material is sintered a second time, which includes a first-step sintering and a second-step sintering. The temperature of the first step sintering is 1000~1200℃, and the sintering time of the first step is 5~60min; The second-step sintering temperature is 950~1200℃, and the second-step sintering time is 60~600min; The heating rate for both the first-step sintering and the second-step sintering is 1~20℃ / min.

10. The application of an oxide material with a garnet-type structure as described in any one of claims 1-6 or an oxide material with a garnet-type structure as described in any one of claims 7-9 prepared by a method thereof in lithium-ion batteries, lithium metal batteries, and solid-state batteries.

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