High ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries

Abstract

The application belongs to the technical field of solid-state lithium metal batteries, and particularly relates to a high-ionic-conductivity double-doped cerium-based garnet electrolyte for solid-state batteries. 5+x+ y La3Ce x Zr y Ta 2‑x‑y O 12 , wherein 0.1

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid-state lithium metal batteries, and particularly relates to a high-ionic-conductivity cerium-based garnet electrolyte for solid-state batteries. BACKGROUND

[0002] Lithium-ion batteries have been widely used in portable electronic devices and electric vehicles, and the requirements for energy density and long battery life are increasingly high. Compared with commercial electrolytes, lithium metal batteries using inorganic solid-state electrolytes are expected to alleviate "battery anxiety" because they have potentially higher energy density and inherently relatively better safety.

[0003] Among inorganic electrolytes, garnet-type oxide electrolytes have attracted much attention due to their high lithium ion conductivity (>10 -4 S cm -1 ), thermal stability and wide electrochemical window. The most widely studied Li7La3Zr2O 12 (LLZO) exists in two different polymorphs, tetragonal and cubic, of which the ionic conductivity of the cubic phase is two orders of magnitude higher than that of the tetragonal phase. Allovalent doping at the cation site, usually Li + or Zr 4+ site, is a common means to stabilize the cubic phase. Al 3+ and Ga 3+ ions have been used to partially replace Li + site to stabilize the cubic phase, thereby improving the lithium ion conductivity of LLZO. In particular, Ga-doped LLZO derivatives exhibit an ionic conductivity of more than 10 -3 S cm -1 at room temperature, but Ga as a rare earth element is high in cost, limiting practical application. In addition, high-valence element doping into Zr 4+ site, such as Ta 5+ , Nb 5+ and W 6+ , can also promote the disordering of Li + sublattice by introducing lithium vacancies in the lattice, thereby promoting the stability of the cubic phase and fast ion conduction. However, their lithium ion conductivity is still low compared with liquid electrolytes.

[0004] Another major challenge for practical application of garnet electrolytes is that in order to obtain dense ceramic pellets, they usually require long-term sintering at high temperature (>1200 degrees) or special sintering techniques such as spark plasma sintering (SPS), hot isostatic pressing (HIP), microwave-assisted sintering and field-assisted sintering. These methods usually result in high energy consumption and limit large-scale production. Therefore, it is urgent to discover new components of garnet electrolytes to improve the limitations of their ionic conductivity and reduce the preparation temperature of material synthesis.

[0005] The present application aims to provide a high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries, which has high ionic conductivity and relatively mild preparation temperature. The Zr and Ta double-doped design optimizes the cerium-based garnet electrolyte, and the solid phase method technology is used to obtain new component garnet ceramic powder and ceramic sheet. Compared with zirconium-based garnet electrolyte, cerium-based garnet has a larger lattice size to expand the bottleneck size of ion transport; Zr and Ta double doping plays a role in stabilizing the cubic phase structure of the material to improve the ionic conductivity of the material. In addition, the cerium element is found to effectively improve the density of the material and reduce the sintering temperature of the ceramic. Finally, a new component cerium-based garnet electrolyte with high ionic conductivity at room temperature and relatively mild preparation temperature is obtained. SUMMARY

[0006] The present application aims to provide a high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries, which has high ionic conductivity and relatively mild preparation temperature. The Zr and Ta double-doped design optimizes the cerium-based garnet electrolyte, and the solid phase method technology is used to obtain new component garnet ceramic powder and ceramic sheet. Compared with zirconium-based garnet electrolyte, cerium-based garnet has a larger lattice size to expand the bottleneck size of ion transport; Zr and Ta double doping plays a role in stabilizing the cubic phase structure of the material to improve the ionic conductivity of the material. In addition, the cerium element is found to effectively improve the density of the material and reduce the sintering temperature of the ceramic. Finally, a new component cerium-based garnet electrolyte with high ionic conductivity at room temperature and relatively mild preparation temperature is obtained. In short, the present application solves the problem of low room temperature ionic conductivity of garnet materials; effectively reduces the preparation temperature of the garnet electrolyte; and effectively reduces the cost of the raw materials of the garnet electrolyte.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] A high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries has the chemical composition: Li 5+x+ y La3Ce x Zr y Ta 2-x-y O 12wherein 0.1 < x < 2.0, 0 < y < 1.5. Specific chemical compositions are: Li 6.32 La3Ce 0.66 Zr 0.66 Ta 0.68 O 12 , Li 6.35 La3Ce 0.45 Zr 0.9 Ta 0.65 O 12 , Li 6.367 La3Ce 0.273 Zr 1.092 Ta 0.365 O 12 , Li 6.38 La3Ce 0.1535 Zr 1.228 Ta 0.6185 O 12 , Li 6.25 La3Ce 1.25 Ta 0.75 O 12 , Li6La3CeTaO 12 .

[0009] As an improvement of the high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries of the present invention, the crystal phase of the electrolyte is cubic phase. XRD and Raman characterization are used to ensure that the resulting phase is cubic.

[0010] As an improvement of the high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries of the present invention, the highest ionic conductivity of the electrolyte at 25°C is 1.1 mS·cm -1 .

[0011] As an improvement of the high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries of the present invention, 0.1 < x < 2.0.

[0012] As an improvement of the high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries of the present invention, 0 < y < 1.5.

[0013] As an improvement of the high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries of the present invention, the preparation method at least includes the following steps:

[0014] First step, ceramic powder is prepared by solid phase method, the oxide raw materials are mixed uniformly in proportion, calcined at high temperature to obtain cubic phase double-doped cerium-based Li 5+x+y La3Ce x Zr y Ta 2-x-y O12 ceramic powder;

[0015] Second, the powder obtained in the first step is ball milled to reduce the particle size, and then tabletting is performed at 1050-1100℃ to sinter to obtain a high-performance ceramic sheet for solid-state batteries.

[0016] As an improvement of the high-ionic-conductivity cerium-based garnet electrolyte for solid-state batteries of the present application, in the first step, the oxide raw materials include a lithium source, a lanthanum source, a cerium source, a zirconium source, and a tantalum source; wherein the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium oxide, and lithium nitrate; the lanthanum source is at least one of lanthanum dioxide, lanthanum chloride, and lanthanum nitrate; the cerium source is at least one of cerium dioxide, cerium hydroxide, and cerium oxalate; the zirconium source is at least one of zirconium dioxide, zirconium nitrate, and zirconium sulfate; and the tantalum source is at least one of tantalum pentoxide and tantalum oxalate. Preferably, the raw materials prepared are lithium carbonate, lanthanum trioxide, cerium dioxide, zirconium dioxide, and tantalum pentoxide, which are mixed in the proportions in the chemical formula to obtain the oxide powder for calcination.

[0017] As an improvement of the high-ionic-conductivity cerium-based garnet electrolyte for solid-state batteries of the present application, the calcination temperature in the first step is 900-1000℃, and the calcination time is 4-6 hours.

[0018] As an improvement of the high-ionic-conductivity cerium-based garnet electrolyte for solid-state batteries of the present application, in the second step, the particle size of the ball-milled powder is 300 nm or less, and the sintering temperature is 1050-1100℃.

[0019] Compared with the prior art, the present application has at least the following beneficial effects:

[0020] First, the problem of low ionic conductivity of the widely used LLZO-based garnet electrolyte is solved. Specifically, the room temperature ionic conductivity of the LLZO material is generally in the order of 10 -4 S·cm -1 The Ga-doped LLZO derivative exhibits an ionic conductivity of more than 10 -3 S·cm -1 at room temperature, but Ga as a rare earth element is high in cost, limiting its practical application. Therefore, the ionic conductivity of LLZO and its derivatives is still low relative to liquid electrolytes. Ce 4+ in the cerium-based garnet electrolyte can improve the ionic transport efficiency of the material due to its larger ionic radius. In addition, the double doping of Zr and Ta stabilizes the cubic phase, achieving a high room temperature ionic conductivity (1.1 mS·cm -1 at 25 degrees).

[0021] Second, to solve the technical problem of preparation of garnet electrolyte, effectively reduce the sintering temperature; garnet electrolyte usually needs to be sintered at high temperature (> 1200℃) for a long time, or special sintering technology is adopted. These methods usually result in high energy consumption and limit large-scale production. It is found that cerium element can effectively improve the density of the material. Cubic phase cerium-based garnet electrolyte lithium lanthanum cerium zirconium tantalum oxide can effectively reduce the sintering temperature of the material (1050-1100℃).

[0022] Third, the cost of raw materials is effectively reduced. The extraction and refining process of Zr is relatively complex, and the reserves on earth are relatively small, resulting in high production cost and relatively high price. Lithium lanthanum cerium zirconium tantalum oxide takes Ce as one of the main elements of B site, and Ce is one of the rare earth elements with higher abundance. Its mining and extraction are relatively easy, and the market supply is relatively sufficient, so the price is relatively low. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The schematic diagram of the crystal structure of the double-doped cerium-based garnet electrolyte provided by the present application is shown.

[0024] Figure 2 The EIS diagram of the material obtained in Example 1 at different temperatures.

[0025] Figure 3 The EIS diagram of the material obtained in Example 2 at different temperatures.

[0026] Figure 4 The EIS diagram of the material obtained in Example 3 at different temperatures.

[0027] Figure 5 The EIS diagram of the material obtained in Example 4 at different temperatures.

[0028] Figure 6 The EIS diagram of the material obtained in Comparative Example 1 at different temperatures.

[0029] Figure 7 The EIS diagram of the material obtained in Comparative Example 2 at different temperatures.

[0030] Figure 8 The EIS diagram of the material obtained in Comparative Example 3 at different temperatures. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0032] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods have not been described in detail in order not to unnecessarily obscure aspects of the present application.

[0033] In order to make the objects, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0034] Embodiment 1

[0035] The embodiment provides a high-ionic-conductivity double-doped cerium-based garnet electrolyte for a solid-state battery, which has a chemical composition of Li 6.32 La3Ce 0.66 Zr 0.66 Ta 0.68 O 12 The electrolyte has a cubic phase, and a schematic diagram of a crystal structure of the electrolyte is shown in FIG. 1. Figure 1

[0036] The preparation method at least includes the following steps:

[0037] In the first step, the oxide raw materials are mixed uniformly according to the proportions, and are calcined at a high temperature to obtain the cubic-phase double-doped cerium-based Li 6.32 La3Ce 0.66 Zr 0.66 Ta 0.68 O 12 The ceramic powder is ensured to have a cubic phase through X-ray diffraction;

[0038] In the second step, the powder obtained in the first step is ball milled to reduce the particle size, and is pressed into a sheet and sintered at 1050-1100 ℃ to obtain a high-performance ceramic sheet for a solid-state battery.

[0039] In the first step, the oxide raw materials include lithium carbonate (25% in excess), lanthanum trioxide, zirconium dioxide, cerium dioxide and tantalum pentoxide.

[0040] The calcination temperature in the first step is 950 ℃, and the particle size of the ball-milled particles in the second step is less than 300 nm.

[0041] The EIS of the material obtained in the embodiment at different temperatures is shown in FIG. 2. Figure 2

[0042] Embodiment 2

[0043] The embodiment provides a high-ionic-conductivity double-doped cerium-based garnet electrolyte for a solid-state battery, which has a chemical composition of Li 6.35 La3Ce 0.45 ​​Zr 0.9 Ta 0.65 O 12 The crystal phase of the electrolyte is cubic phase.

[0044] The preparation method comprises at least the following steps:

[0045] In the first step, ceramic powder is prepared by a solid phase method, oxide raw materials are uniformly mixed in proportion, and a cerium-doped Li 6.35 La3Ce 0.45 Zr 0.9 Ta 0.65 O 12 The ceramic powder is ensured to be in cubic phase by X-ray diffraction;

[0046] In the second step, the powder obtained in the first step is ball milled to reduce the particle size, and then tabletting is performed at 1050-1100 DEG C for sintering, so that a high-performance ceramic sheet for solid-state batteries is obtained.

[0047] In the first step, the oxide raw materials include: lithium carbonate (25% excess), lanthanum trioxide, zirconium dioxide, cerium dioxide and tantalum pentoxide. The calcination temperature in the first step is 1000 DEG C, and the particle size of the ball-milled particles in the second step is less than 300 nanometers.

[0048] The EIS of the material obtained in the example at different temperatures is shown in the following table. Figure 3

[0049] Example 3

[0050] The example provides a cerium-doped Li 6.367 La3Ce 0.273 Zr 1.092 Ta 0.365 O 12 The crystal phase of the electrolyte is cubic phase.

[0051] The preparation method comprises at least the following steps:

[0052] In the first step, ceramic powder is prepared by a solid phase method, oxide raw materials are uniformly mixed in proportion, and a cerium-doped Li 6.367 La3Ce 0.273 Zr 1.092 Ta 0.365 O 12 The ceramic powder is ensured to be in cubic phase by X-ray diffraction;

[0053] In the second step, the powder obtained in the first step is ball milled to reduce the particle size, and then tabletting is performed at 1050-1100 DEG C for sintering, so that a high-performance ceramic sheet for solid-state batteries is obtained.​

[0054] In the first step, the oxide raw materials include: lithium carbonate (excess 25%), lanthanum oxide, zirconium dioxide, cerium dioxide and tantalum pentoxide.

[0055] The calcination temperature in the first step is 1000°C.

[0056] The particle size of the particles after ball milling in the second step is below 300 nm.

[0057] The EIS of the material obtained in this example at different temperatures is shown in Figure 4 .

[0058] Example 4

[0059] This example provides a high ionic conductivity double-doped cerium-based garnet electrolyte for solid-state batteries, which has a chemical composition of: Li 6.38 La3Ce 0.1535 Zr 1.228 Ta 0.6185 O 12 , and the crystal phase of the electrolyte is cubic phase.

[0060] The preparation method thereof at least includes the following steps:

[0061] In the first step, ceramic powder is prepared by a solid phase method, the oxide raw materials are mixed uniformly in proportion, and cubic phase double-doped cerium-based Li 6.38 La3Ce 0.1535 Zr 1.228 Ta 0.6185 O 12 ceramic powder is obtained by calcination at high temperature, and the phase is ensured to be cubic phase by X-ray diffraction;

[0062] In the second step, the powder obtained in the first step is ball milled to reduce the particles, and the tablet is sintered at 1050-1100°C to obtain a high-performance ceramic sheet for solid-state batteries.

[0063] In the first step, the oxide raw materials include: lithium carbonate (excess 25%), lanthanum trioxide, zirconium dioxide, cerium dioxide and tantalum pentoxide.

[0064] The calcination temperature in the first step is 1000°C.

[0065] The particle size of the particles after ball milling in the second step is below 300 nm.

[0066] The EIS of the material obtained in this example at different temperatures is shown in Figure 5 .

[0067] Comparative Example 1

[0068] This example provides a Ta 5+doped Li7La3Ce2O 12 with a chemical composition of Li 6.25 La3Ce 1.25 Ta 0.75 O 12 The EIS of the material obtained in this example at different temperatures is shown in Figure 6 After the powder of this example was ball-milled to reduce the particle size, the tablet was sintered at 1100°C to obtain a high-performance ceramic sheet for solid-state batteries.

[0069] Comparative Example 2

[0070] This comparative example provides a Ta 5+ doped Li7La3Ce2O 12 with a chemical composition of Li6La3CeTaO 12。 The EIS of the material obtained in this example at different temperatures is shown in Figure 7 .

[0071] After the powder of this example was ball-milled to reduce the particle size, the tablet was sintered at 1150°C to obtain a high-performance ceramic sheet for solid-state batteries.

[0072] Comparative Example 3

[0073] This comparative example provides a Ta 5+ doped Li7La3Zr2O 12 (LLZO) with a chemical composition of Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The EIS of the material obtained in this example at different temperatures is shown in Figure 8 . After the powder of this example was ball-milled to reduce the particle size, the tablet was sintered at 1250°C to obtain a high-performance ceramic sheet for solid-state batteries.

[0074] According to the impedance value of the EIS spectrum, and the thickness of the ceramic (about 900 microns) and the gold paste area (diameter 6.5 mm), it can be calculated that: Figures 2 to 8

[0075] In Experimental Example 1, the Li 6.32 La3Ce 0.66 Zr 0.66 Ta 0.68 O 12 The ionic conductivity of the material at different temperatures was 0.81 mS·cm -1 (20.5°C), 1.07 mS·cm -1 (25°C), 1.88 mS·cm -1 (38.5°C), and 2.96 mS·cm​-1 (49.6°C), 4.59 mS-cm -1 (60.4°C), 6.53 mS-cm -1 (69.4°C), 8.92 mS-cm -1 (80.8°C), 12.4 mS-cm -1 (92°C).

[0076] In Experimental Example 2, Li 6.35 La3Ce 0.45 Zr 0.9 Ta 0.65 O 12 The ionic conductivities of the material at different temperatures are 0.85 mS-cm -1 (20.5°C), 1.02 mS-cm -1 (25°C), 1.91 mS-cm -1 (39.5°C), 2.94 mS-cm -1 (48.7°C), 4.56 mS-cm -1 (57.7°C), 6.37 mS-cm -1 (69.1°C), 8.89 mS-cm -1 (78.4°C), 12.2 mS-cm -1 (86.8°C).

[0077] In Experimental Example 3, Li 6.367 La3Ce 0.273 Zr 1.092 Ta 0.365 O 12 The ionic conductivities of the material at different temperatures are 0.86 mS-cm -1 (21°C), 1.04 mS-cm -1 (25°C), 2.05 mS-cm -1 (41.1°C), 2.96 mS-cm -1 (49.6°C), 4.34 mS-cm -1 (59.5°C), 6.58 mS-cm -1 (71.8°C), 9.13 mS-cm -1 (81.5°C), 12.6 mS-cm -1 (92.5°C).

[0078] In Experimental Example 4, Li 6.38 La3Ce 0.1535 Zr 1.228 Ta 0.6185 O 12 The ionic conductivities of the material at different temperatures are 0.68 mS-cm-1 (19.8°C), 0.94 mS-cm -1 (25°C), 1.85 mS-cm -1 (40.5°C), 2.83 mS-cm -1 (49.7°C), 4.17 mS-cm -1 (61.6°C), 6.25 mS-cm -1 (71.3°C), 8.70 mS-cm -1 (81.8°C), 12.1 mS-cm -1 (91.7°C).

[0079] In Comparative Example 1, Li 6.25 La3Ce 1.25 Ta 0.75 O 12 The ionic conductivities of the material at different temperatures are 0.73 mS-cm -1 (20°C), 0.87 mS-cm -1 (25°C), 1.09 mS-cm -1 (30°C), 1.77 mS-cm -1 (39°C), 2.71 mS-cm -1 (49.3°C), 4.07 mS-cm -1 (59.1°C), 5.83 mS-cm -1 (69.3°C), 8.19 mS-cm -1 (80.8°C), 11.4 mS-cm -1 (92.8°C).

[0080] In Comparative Example 2, Li6La3CeTaO 12 The ionic conductivities of the material at different temperatures are 0.49 mS-cm -1 (25°C), 1.06 mS-cm -1 (40.7°C), 1.72 mS-cm -1 (50.3°C), 2.76 mS-cm -1 (61.9°C), 5.89 mS-cm -1 (80.4°C), 7.34 mS-cm -1 (86.6°C).

[0081] In Comparative Example 3, Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The ionic conductivities of the material at different temperatures are 0.57 mS-cm -1 (20°C), 0.74 mS-cm-1 (25 °C), 1.63 mS-cm -1 (38.9 °C), 2.56 mS-cm -1 (51 °C), 3.95 mS-cm -1 (62.6 °C), 5.17 mS-cm -1 (71.3 °C), 9.05 mS-cm -1 (82.8 °C), 11.2 mS-cm -1 (93.8 °C).

[0082] The room temperature ionic conductivities of Examples 1-5 and Comparative Examples 1-3 were tested by polishing the obtained ceramic sheets to a thickness of about 900 microns using a polisher, and then polishing the surfaces to smoothness using 600, 1200, and 2000 mesh sandpaper. Gold paste was applied to both sides of the ceramic, and the ceramic was dried at 800-900 °C for 1 hour. Impedance was tested on an electrochemical workstation, and the test range was 1-13 MHz.

[0083] The test results of each example and each comparative example are shown in Table 1.

[0084] Table 1: Densities, room temperature ionic conductivities, and activation energies of Examples 1-4 and Comparative Examples 1-3

[0085]

[0086] As can be seen from Table 1, compared to the material Li 6.4 La3Zr 1.4 Ta 0.6 O 12 , after the addition of Ce elements in Examples 1-3, the room temperature ionic conductivities were all significantly improved, the corresponding activation energies decreased, and the material densities increased to varying degrees. Compared to the separate Ta 5+ doping of the cerium-based garnet material in Comparative Examples 1 and 2, Examples 1-3 used a Zr 4+ and Ta 5+ double-doping method, and the room temperature ionic conductivities were significantly improved, and the results were close. Among them, Example 1 material Li 6.32 La3Ce 0.66 Zr 0.66 Ta 0.68 O 12 achieved the highest room temperature ionic conductivity (1.07 mS-cm -1 ) and the lowest activation energy (0.35 eV).

[0087] Those skilled in the art can make various modifications and changes to the above embodiments according to the disclosure and teachings herein. Therefore, the application is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the application shall fall within the protection scope of the claims of the application. In addition, although some specific terms are used in the specification, these terms are only for convenience of description and do not constitute any limitation on the application.

Claims

1. A high ionic conductivity double doped cerium based garnet electrolyte for solid state batteries, characterized in that, Chemical composition: Li 6.32 La3Ce 0.66 Zr 0.66 Ta 0.68 O 12 , Li 6.35 La3Ce 0.45 Zr 0.9 Ta 0.65 O 12 , Li 6.367 La3Ce 0.273 Zr 1.092 Ta 0.36 5O 12 or Li 6.38 La3Ce 0.1535 Zr 1.228 Ta 0.6185 O 12 .

2. The high ionic conductivity double doped cerium based garnet electrolyte for solid state battery according to claim 1, characterized in that: The crystal phase of the electrolyte is a cubic phase.

3. The high ionic conductivity double doped cerium based garnet electrolyte for solid state battery according to claim 1, characterized in that: The electrolyte has a maximum ion conductivity of 1.1 mS / cm at 25 DEG C.

4. The high ionic conductivity double doped cerium based garnet electrolyte for solid state battery according to claim 1, characterized in that, The preparation method comprises at least the following steps: First, ceramic powder was prepared by solid phase method. Oxide raw materials were mixed uniformly according to the proportion, and calcined at high temperature to obtain cubic phase double-doped cerium-based Li 6.32 La3Ce 0.66 Zr 0.66 Ta 0.68 O 12 ceramic powder, Li 6.35 La3Ce 0.45 Zr 0.9 Ta 0.65 O 12 ceramic powder, Li 6.367 La3Ce 0.273 Zr 1.092 Ta 0.365 O 12 ceramic powder or Li 6.38 La3Ce 0.1535 Zr 1.228 Ta 0.6185 O 12 ceramic powder; In the second step, the powder obtained in the first step is sintered at 1050-1100 DEG C after being reduced in particle size by ball milling to obtain a high-performance ceramic sheet for solid-state batteries.

5. The high ionic conductivity double doped cerium based garnet electrolyte for solid state battery according to claim 4, characterized in that, In the first step, the oxide raw materials comprise a lithium source, a lanthanum source, a cerium source, a zirconium source and a tantalum source; the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium oxide and lithium nitrate; the lanthanum source is at least one of lanthanum dioxide, lanthanum chloride and lanthanum nitrate; the cerium source is at least one of cerium dioxide, cerium hydroxide and cerium oxalate; the zirconium source is at least one of zirconium dioxide, zirconium nitrate and zirconium sulfate; and the tantalum source is at least one of tantalum pentoxide and tantalum oxalate.

6. The high ionic conductivity double doped cerium based garnet electrolyte for solid state battery according to claim 4, characterized in that, The calcination temperature in the first step is 900-1000 DEG C, and the calcination time is 4-6 hours.

7. The high ionic conductivity double doped cerium based garnet electrolyte for solid state battery according to claim 4, characterized in that, The particle size of the particles after ball milling in the second step is 300 nm or less.

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