Solid electrolyte, preparation method thereof and battery

Abstract

The invention provides a solid electrolyte, a preparation method thereof and a battery. The solid electrolyte takes double rare earth doped barium zirconate as a main phase and aluminum oxide as a second phase, the double rare earth doping elements are yttrium element and ytterbium element. Through the synergistic effect of a double-rare-earth doping mechanism and a second-phase pinning effect, the solid electrolyte has relatively good conductivity, the mechanical stability and the thermal stability of the solid electrolyte are also improved, and the thermal mechanical stability of the solid electrolyte is favorably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a solid electrolyte, a preparation method thereof, and a battery. Background Art

[0002] Solid electrolytes are an important component of solid-state batteries, affecting their safety and electrochemical performance. To be successfully applied in solid-state batteries, solid electrolytes must possess high ionic conductivity, a wide electrochemical window, good chemical stability, and interfacial compatibility.

[0003] However, many existing solid electrolytes have a highly ordered crystal structure, which often makes them less susceptible to plastic deformation under external forces and more susceptible to cracking or fracture. Under mechanical stress or thermal cycling, solid electrolytes are prone to localized cracking, which can deteriorate the interface with the electrode, destroying the interface structure and affecting the thermal safety and stability of the battery. Summary of the Invention

[0004] The present invention aims to provide a solid electrolyte, a preparation method thereof, and a battery, so as to solve the problem that existing solid electrolytes are prone to local cracks under the action of mechanical stress or thermal cycling.

[0005] To solve the above problems, the first aspect of the present invention provides a solid electrolyte comprising double rare earth doped barium zirconate as a main phase and aluminum oxide as a second phase;

[0006] Wherein, the double rare earth doping elements are yttrium and ytterbium.

[0007] A second aspect of the present invention provides a method for preparing a solid electrolyte, for preparing the solid electrolyte according to the first aspect, the preparation method comprising:

[0008] The barium source, the zirconium source, the yttrium source and the ytterbium source are mixed evenly to prepare double rare earth doped barium zirconate;

[0009] The double rare earth doped barium zirconate and aluminum oxide are uniformly mixed to prepare a precursor, and the precursor is sintered to prepare a solid electrolyte.

[0010] A third aspect of the present invention provides a battery comprising the solid electrolyte described in the first aspect, or the solid electrolyte prepared by the preparation method described in the second aspect.

[0011] The solid electrolyte of the present invention is based on double rare earth doped barium zirconate. After Y and Yb with larger atomic radius and higher electronegativity are doped into the barium zirconate matrix, Y in ionic state is formed. 3+ and Yb 3+Entering the barium zirconate crystal, Yb 3+ Partially replace Ba 2+ , Y 3+ Partially replace Zr 4+ , producing lattice distortion, reducing the activation energy of oxygen vacancy migration, and strengthening the grain boundaries, through Y 3+ and Yb 3+ The synergistic effect between the two is conducive to optimizing the structural stability and conductivity of the main phase and improving the conductivity of the solid electrolyte. With alumina as the second phase, after the second phase is compounded with the main phase, alumina particles can be distributed in the grain boundaries or lattice gaps of the double rare earth doped barium zirconate. These alumina particles produce a Zener pinning effect at the grain boundaries, preventing abnormal grain growth and dislocation migration at the grain boundaries or within the crystals, which is conducive to improving the structural strength and thermal stability of the solid electrolyte. In addition, Yb in the main phase 3+ and Y 3+ The charge compensation effect can provide nucleation sites for the second phase particles, and Yb 3+ and Y 3+ The co-segregation effect at the grain boundary can reduce the interfacial energy, and the charge compensation effect and co-segregation effect are conducive to promoting the formation or stability of the second phase particles, so that the second phase can be more stably distributed in the main phase, thereby further enhancing the Zener pinning effect of the second phase to further prevent grain boundary movement and dislocation migration; and Yb 3+ and Y 3+ It can adjust the electronic structure of the main phase, enhance the interfacial bonding force, and enable the second phase particles to function more effectively, which is conducive to further enhancing the mechanical and thermal stability of the solid electrolyte. In the present invention, through the synergistic effect of the dual rare earth doping mechanism and the second phase pinning effect, it not only ensures that the solid electrolyte has good electrical conductivity, but also improves the mechanical and thermal stability of the solid electrolyte, which is conducive to improving the thermomechanical stability of the solid electrolyte.

[0012] The preparation method of the solid electrolyte of the present invention, by first preparing double rare earth doped barium zirconate, can improve the uniformity of yttrium source and ytterbium source doping in barium zirconate, which is beneficial to improving the structural stability and conductivity of barium zirconate with double rare earth parameters, and then after the double rare earth doped barium zirconate and aluminum oxide are evenly mixed, a precursor is prepared, which can make aluminum oxide uniformly dispersed in the double rare earth doped barium zirconate, reduce the agglomeration between aluminum oxides, and is beneficial to improving the effect of aluminum oxide pinning grain boundaries, and finally the precursor is sintered to prepare a solid electrolyte, which is beneficial to improving the density of the solid electrolyte, thereby improving the mechanical stability and thermal stability of the solid electrolyte. In addition, the preparation method of the solid electrolyte provided by the present invention is simple and easy to form, has low cost, is environmentally friendly, can reduce production costs, and is suitable for industrial mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a process flow chart for preparing a solid electrolyte according to an embodiment of the present invention. DETAILED DESCRIPTION

[0014] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0015] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0016] In addition, the terms "comprising", "including", "containing", and "having" are not restrictive, and other steps and other components that do not affect the results can be added. Unless otherwise specified, materials, equipment, and reagents are commercially available.

[0017] In addition, although the present invention describes the various steps in the preparation in the form of S110, S120 and S130, this description is only for ease of understanding. The form of S110, S120 and S130 does not limit the order of the steps.

[0018] To solve the above technical problems, a first aspect of an embodiment of the present application provides a solid electrolyte having double rare earth-doped barium zirconate as a main phase and aluminum oxide particles as a second phase;

[0019] Among them, the double rare earth doping elements are yttrium and ytterbium.

[0020] The chemical formula of barium zirconate is BaZrO3, the chemical formula of aluminum oxide is Al2O3, the chemical symbol of yttrium is Y, and the chemical symbol of ytterbium is Yb.

[0021] The solid electrolyte provided in this embodiment is mainly composed of double rare earth doped barium zirconate. After Y and Yb with larger atomic radius and higher electronegativity are doped into the barium zirconate matrix, Y in ionic state is formed. 3+ and Yb 3+ Entering the barium zirconate crystal, Yb 3+ Partially replace Ba 2+ , Y 3+ Partially replace Zr 4+ , producing lattice distortion, reducing the activation energy of oxygen vacancy migration, and strengthening the grain boundaries, through Y 3+ and Yb 3+The synergistic effect between the two is conducive to optimizing the structural stability and conductivity of the main phase and improving the conductivity of the solid electrolyte. With alumina as the second phase, after the second phase is compounded with the main phase, alumina particles can be distributed in the grain boundaries or lattice gaps of the double rare earth doped barium zirconate. These alumina particles produce a Zener pinning effect at the grain boundaries, preventing abnormal grain growth and dislocation migration at the grain boundaries or within the crystals, which is conducive to improving the structural strength and thermal stability of the solid electrolyte. In addition, Yb in the main phase 3+ and Y 3+ The charge compensation effect can provide nucleation sites for the second phase particles, and Yb 3+ and Y 3+ The co-segregation effect at the grain boundary can reduce the interfacial energy, and the charge compensation effect and co-segregation effect are conducive to promoting the formation or stability of the second phase particles, so that the second phase can be more stably distributed in the main phase, thereby further enhancing the Zener pinning effect of the second phase to further prevent grain boundary movement and dislocation migration; and Yb 3+ and Y 3+ It can adjust the electronic structure of the main phase, enhance interfacial bonding, and enable the second-phase particles to function more effectively, which is conducive to further enhancing the mechanical and thermal stability of the solid electrolyte. In this embodiment, the synergistic effect of the dual rare earth doping mechanism and the second-phase pinning effect not only ensures that the solid electrolyte has good electrical conductivity, but also improves the mechanical and thermal stability of the solid electrolyte, which is conducive to improving the thermomechanical stability of the solid electrolyte.

[0022] Based on the above embodiment, as an optional implementation, the molar ratio of yttrium to ytterbium in the double rare earth doped barium zirconate is 2:1 to 3:1. 3+ Excessive Y2O3 segregation phase is likely to form, and the doped Y 3+ Too little will lead to reduced mechanical strength and poor thermal stability of the solid electrolyte. Therefore, setting the molar ratio of yttrium to ytterbium to 2:1 to 3:1 is beneficial to further improve the mechanical strength and thermal stability of the solid electrolyte.

[0023] Based on the above embodiment, as an optional embodiment, the chemical formula of double rare earth doped barium zirconate is BaZr x Y y Yb z O w, where 0.75≤x≤0.95, 0.1≤y≤0.2, 0.03≤z≤0.07, and 2.85≤w≤3.05. For example, x can be 0.75, 0.8, 0.85, 0.9, and 0.95, y can be 0.1, 0.12, 0.15, 0.18, and 0.2, z can be 0.03, 0.04, 0.05, 0.06, and 0.07, and w can be 2.85, 2.9, 2.95, 3, and 3.05. Thus, Y 3+ and Yb 3+ The difference between the ionic radii makes Y 3+ It can reduce the activation energy of oxygen vacancy migration, Yb 3+ It can strengthen the grain boundaries by 3+ and Yb 3+ Limiting the doping amount between the two to within the above range can further optimize the structural stability and conductivity of the main phase and further enhance the mechanical stability and thermal stability of the solid electrolyte.

[0024] Based on the above embodiment, as an optional implementation, the mass of aluminum oxide in the solid electrolyte is 8wt% to 10wt% of the mass of the main phase, that is, the mass of aluminum oxide is 8wt% to 10wt% of the mass of the double rare earth doped barium zirconate, for example, the mass of aluminum oxide is 8wt%, 9wt% or 10wt% of the mass of the double rare earth doped barium zirconate. Since Al2O3 is an insulator, if excessive Al2O3 is added to the solid electrolyte, it will block the continuous conductive network of the main phase, which may cause the migration path of protons or ions to be isolated, resulting in a sharp decrease in conductivity. Al2O3 may even form an insulating layer or agglomerates, hindering the transfer of charge and greatly affecting the conductivity of the solid electrolyte. If the amount of Al2O3 added to the solid electrolyte is too small, it cannot effectively pin the grain boundaries, resulting in accelerated grain boundary migration at high temperature and abnormal grain growth, resulting in a decrease in the creep resistance of the solid electrolyte and an increase in brittleness, affecting the stability of the mechanical structure of the solid electrolyte. Therefore, in this embodiment, by setting the mass of aluminum oxide in the solid electrolyte to 8% to 10% of the mass of the main phase, while ensuring good conductivity of the solid electrolyte, it is also beneficial to further improve the mechanical stability of the solid electrolyte. As a preferred embodiment, the mass of aluminum oxide in the solid electrolyte is 10wt% of the mass of the main phase.

[0025] Based on the above embodiment, as an optional implementation, the aluminum oxide is nano-aluminum oxide with a particle size of 20 nm to 50 nm, for example, the aluminum oxide particle size is 20 nm, 30 nm, 40 nm, or 50 nm. As a result, the nano-aluminum oxide can be better distributed within the grain boundaries or interstices of the double rare earth-doped barium zirconate, more effectively pinning the grain boundaries. Furthermore, the small particles of nano-aluminum oxide can avoid affecting the continuous conductive network of the main phase.

[0026] Figure 1 The process flow chart of preparing solid electrolyte provided in the embodiment of the present invention is shown in FIG. Figure 1 A second aspect of the present invention provides a method for preparing a solid electrolyte, which is used to prepare the solid electrolyte described in the first aspect. The method comprises:

[0027] Step S110: Evenly mix the barium source, the zirconium source, the yttrium source, and the ytterbium source to prepare double rare earth doped barium zirconate.

[0028] Specifically, a barium source, a zirconium source, a yttrium source, a ytterbium source and an organic solvent are ball-milled to prepare a mixture; the mixture is pre-sintered to prepare a pre-sintered product; and the pre-sintered product is ball-milled to prepare double rare earth doped barium zirconate. Thus, by ball-milling the raw materials, the agglomeration between the components can be reduced, and pre-sintering after the mixture is prepared can promote atomic diffusion on the surface of the particles refined after ball milling, enhance the bonding force between the particles, and reduce the shrinkage rate during the subsequent sintering process. Pre-sintering can also remove the organic solvent and volatile matter added during the ball milling process. By ball-milling the pre-sintered product, the agglomerates formed by the pre-sintering can be broken, the pre-sintered product can be refined, and the uniformity of the double rare earth doping elements can be improved, which is conducive to further improving the structural stability and conductivity of the double rare earth doped barium zirconate.

[0029] Based on the above embodiment, as an optional embodiment, the components of the barium source, zirconium source, yttrium source, and ytterbium source are weighed according to the molar ratio, and an organic solvent is added as a medium for ball milling. The ball milling speed can be 300 rpm and the ball milling time can be 6 hours. The barium source can be BaCO3, the zirconium source can be ZrO2, the yttrium source can be Y2O3, the ytterbium source can be Yb2O3, and the organic solvent can be ethanol. Of course, those skilled in the art can also select other barium sources, zirconium sources, yttrium sources, ytterbium sources, and organic solvents commonly used in the art, and those skilled in the art can also adjust the ball milling speed and ball milling time according to actual conditions.

[0030] Based on the above embodiment, as an optional implementation manner, the mixture is pre-sintered to obtain a pre-sintered product, including:

[0031] In an air atmosphere, the mixture is heated from room temperature to a first preset temperature and maintained at the first preset temperature for 3 to 5 hours to produce a pre-sintered product. The first preset temperature is 1150°C to 1250°C, and the heating rate is 2°C / min to 4°C / min. Thus, pre-sintering the mixture from room temperature to the first preset temperature is beneficial for further strengthening the bonding force between the particles and reducing the shrinkage rate during the subsequent sintering process. By limiting the heating rate to the above range, it is possible to avoid excessively rapid heating, which may increase the brittleness of the pre-sintered product and affect the structural stability of the pre-sintered product.

[0032] Based on the above embodiment, as an optional embodiment, when the pre-sintered product is ball-milled, an organic solvent can be added as a medium for ball-milling to reduce the agglomeration between the powders. The ball-milling speed can be 300 rpm, and the ball-milling speed can be 1000 rpm. 50 =0.8 μm, the ball milling can be terminated to obtain double rare earth doped barium zirconate. The organic solvent can be ethanol. Of course, those skilled in the art can also choose other organic solvents commonly used in the art. Those skilled in the art can also adjust the ball milling speed according to actual conditions.

[0033] The double rare earth doped barium zirconate prepared in this embodiment has a D 50 The diameter of the nano-alumina is 0.8 μm, which is conducive to the entry of the nano-alumina into the grain boundaries or lattice gaps of the double rare earth doped barium zirconate, so that the nano-alumina and the double rare earth doped barium zirconate are in closer contact, thereby improving the effectiveness of the nano-alumina pinning the grain boundaries, thereby further enhancing the mechanical stability and thermal stability of the solid electrolyte.

[0034] Step S120: Evenly mix double rare earth doped barium zirconate and aluminum oxide to obtain a precursor, and sinter the precursor to obtain a solid electrolyte.

[0035] Specifically, double rare earth doped barium zirconate and aluminum oxide are ball-milled and mixed to prepare a precursor; under a wet H2 atmosphere, the precursor is subjected to a first stage sintering at a second preset temperature to obtain a first sintered product; under a wet H2 atmosphere, the first sintered product is subjected to a second stage sintering at a third preset temperature to obtain a solid electrolyte; wherein the second preset temperature is higher than the third preset temperature. Therefore, by ball-milling the double rare earth doped barium zirconate and alumina, the alumina can be evenly dispersed in the double rare earth doped barium zirconate and the agglomeration between the aluminas can be reduced. The precursor is sintered in the first stage at the second preset temperature to promote the densification of the main phase, which is beneficial to improving the density and mechanical properties of the main phase. The temperature is then lowered for the second stage sintering, which can slow down the migration rate of the alumina grain boundaries and effectively avoid excessive growth of alumina grains due to excessive diffusion rate, resulting in increased brittleness of the solid electrolyte. In addition, in this embodiment, sintering in a wet H2 atmosphere can promote the formation of proton defects, and the reduction effect of hydrogen can suppress the generation of electronic defects (such as free electrons) in the material, so that ionic conductivity dominates, which is beneficial to improving the conductivity of the solid electrolyte.

[0036] Based on the above embodiment, as an optional implementation manner, the ball milling speed of the double rare earth doped barium zirconate and aluminum oxide can be 200 rpm, and the ball milling time can be 4 hours to ensure that the double rare earth doped barium zirconate and aluminum oxide can be evenly mixed.

[0037] Based on the above embodiment, as an optional implementation manner, before the double rare earth doped barium zirconate and alumina are ball-milled and mixed, the following steps are further included:

[0038] Alumina is dispersed in a dispersant and uniformly mixed to pretreat the alumina and prevent agglomeration of the nano-alumina particles, which would otherwise affect the alumina's ability to pin grain boundaries. Alternatively, the dispersant may be PVP, and the amount of dispersant added may be 0.4 to 0.6 weight percent (i.e., 0.4 to 0.6 weight percent) of the total amount of alumina.

[0039] Based on the above embodiment, as an optional implementation method, the second preset temperature is 1400℃ to 1500℃, and the first sintering time is 2h; the third preset temperature is 1250℃ to 1350℃, and the second sintering time is 6h; the second preset temperature is reduced to the third preset temperature at a cooling rate of 1℃ / min to 3℃ / min, and after the second stage sintering is completed, the cooling rate is 1℃ / min to 3℃ / min, and after the temperature drops below 1000℃, the sintering furnace is turned off and allowed to cool naturally. Therefore, by setting the second preset temperature within the above range, the atomic diffusion capacity of the main phase can be enhanced, the pores are quickly closed, and the density and mechanical properties of the main phase are improved; by setting the third preset temperature within the above range, the migration rate of the alumina grain boundary can be further slowed down; by controlling the cooling rate between 1℃ / min and 3℃ / min, it is possible to avoid the cooling rate being too fast, which will increase the brittleness of the solid electrolyte and affect the structural stability of the solid electrolyte.

[0040] Based on the above embodiment, as an optional implementation manner, the wet H2 atmosphere refers to a gas environment containing 3% H2O. Therefore, sintering in this environment is beneficial to further promote the formation of proton defects.

[0041] The preparation method of the solid electrolyte provided in this embodiment, by first preparing double rare earth doped barium zirconate, can improve the uniformity of yttrium source and ytterbium source doping in barium zirconate, which is beneficial to improving the structural stability and conductivity of barium zirconate with double rare earth parameters, and then after the double rare earth doped barium zirconate and aluminum oxide are evenly mixed, a precursor is prepared, which can make aluminum oxide uniformly dispersed in the double rare earth doped barium zirconate, reduce the agglomeration between aluminum oxides, and is beneficial to improving the effect of aluminum oxide pinning grain boundaries. Finally, the precursor is sintered to prepare a solid electrolyte, which is beneficial to improving the density of the solid electrolyte, thereby improving the mechanical stability and thermal stability of the solid electrolyte. In addition, the preparation method of the solid electrolyte provided in this embodiment is simple and easy to form, low in cost, environmentally friendly, can reduce production costs, and is suitable for industrial mass production.

[0042] A third aspect of the embodiments of the present application provides a battery, comprising the solid electrolyte as described in the first aspect, or the solid electrolyte prepared by the preparation method as described in the second aspect.

[0043] In this embodiment, by adding the above-mentioned solid electrolyte to the battery, the electrical performance of the battery is improved while also helping to improve the thermal mechanical stability of the battery, thereby improving the safety performance of the battery.

[0044] In order to further explain the present invention in detail, the present invention will be further described below with reference to specific examples. Unless otherwise specified, the experimental methods used in the examples of the present invention are conventional methods; unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention are all purchased from the market.

[0045] Example 1

[0046] This embodiment provides a method for preparing a solid electrolyte, comprising the following steps:

[0047] (1) Calculate the masses of BaCO3, ZrO2, Y2O3, and Yb2O3 based on the molar ratio of BaCO3:ZrO2:Y2O3:Yb2O3 of 1:0.8:0.075:0.025, and weigh BaCO3, ZrO2, Y2O3, and Yb2O3 respectively. Then, weigh nano-Al2O3 powder based on the mass of alumina being 10 wt% of the mass of the main phase, where the mass of the main phase refers to the sum of the masses of BaCO3, ZrO2, Y2O3, and Yb2O3;

[0048] (2) BaCO3, ZrO2, Y2O3 and Yb2O3 were added to a ball mill and ethanol was added as a medium to the ball mill for ball milling at a ball milling speed of 300 rpm for 6 h to obtain a mixture. The mixture was heated from room temperature to 1200°C at a heating rate of 3°C / min in an air atmosphere and kept at 1200°C for 4 h to obtain a pre-sintered product. The pre-sintered product was added to a ball mill and ethanol was added as a medium to ball milling at a ball milling speed of 300 rpm until D 50 =0.8μm, the ball milling is terminated, and then the powders can be manually ground to mix evenly, and a small amount of ethanol can be added during the grinding process to reduce the agglomeration between the powders. After manual grinding, double rare earth doped barium zirconate is obtained.

[0049] (3) Alumina is dispersed in PVP, the amount of PVP added is 0.5wt%, and the alumina and PVP are mixed uniformly to obtain pretreated alumina; the pretreated alumina and the double rare earth doped barium zirconate in step (2) are added to a ball mill, and planetary ball milling is performed, the ball milling speed is set to 200rpm, the ball milling time is 4h, and the ball milling is uniformly mixed to obtain a precursor; in order to facilitate the performance test of the solid electrolyte, a manual tablet press is used to press the precursor into a disc, and the tableting pressure is about 20MP a. The diameter of the disc is 10 mm and the thickness is 2 mm. The disc is placed in a sintering furnace and sintered at 1450°C for a first stage for 2 hours in a wet H2 atmosphere to obtain a first sintered product. The temperature is then lowered at 2°C / min to 1300°C. The first sintered product is sintered at 1300°C for a second stage in a wet H2 atmosphere. After sintering for 6 hours, the temperature is lowered at 2°C / min to below 1000°C. The sintering furnace is then closed and allowed to cool naturally to obtain a solid electrolyte.

[0050] The chemical formula of the solid electrolyte in this embodiment is BaZr 0.8 Y 0.15 Yb 0.05 O3.10wt%Al2O3.

[0051] Comparative Example 1

[0052] In this comparative example, BaZrO3 is used as the solid electrolyte. BaZrO3 is obtained by mixing BaCO3 and ZrO2 as raw materials through ball milling.

[0053] Comparative Example 2

[0054] This comparative example provides a method for preparing a solid electrolyte. The preparation process of the solid electrolyte is the same as that of Example 1, except that:

[0055] According to the molar ratio of BaCO3:ZrO2:Y2O3:Yb2O3 of 1:0.8:0.105:0.025, the masses of BaCO3, ZrO2, Y2O3 and Yb2O3 were calculated respectively, and BaCO3, ZrO2, Y2O3 and Yb2O3 were weighed respectively. Then, nano-Al2O3 powder was weighed according to the mass percentage of aluminum oxide being 10wt%.

[0056] Comparative Example 3

[0057] This comparative example provides a method for preparing a solid electrolyte. The preparation process of the solid electrolyte is the same as that of Example 1, except that:

[0058] Alumina was not added to the solid electrolyte as the second phase, that is, the double rare earth doped barium zirconate prepared in step (2) of Example 1 was used as the solid electrolyte in this comparative example.

[0059] Comparative Example 4

[0060] This comparative example provides a method for preparing a solid electrolyte. The preparation process of the solid electrolyte is the same as that of Example 1, except that:

[0061] In this comparative example, BaZrO3 is used as the main phase. BaZrO3 is obtained by ball milling with BaCO3 and ZrO2 as raw materials. 10wt% of nano-alumina is added to the main phase as the second phase. BaZrO3 and alumina are ball milled to obtain a precursor. Under a wet H2 atmosphere, the precursor is subjected to a first sintering at a second preset temperature to obtain a first sintered product. Under a wet H2 atmosphere, the first sintered product is subjected to a second sintering at a third preset temperature to obtain a solid electrolyte. For the specific preparation method, see step (3) in Example 1.

[0062] Comparative Example 5

[0063] This comparative example provides a method for preparing a solid electrolyte. The preparation process of the solid electrolyte is the same as that of Example 1, except that:

[0064] According to the molar ratio of BaCO3:ZrO2:Y2O3:Yb2O3 of 1:0.8:0.045:0.025, the masses of BaCO3, ZrO2, Y2O3 and Yb2O3 were calculated respectively, and BaCO3, ZrO2, Y2O3 and Yb2O3 were weighed respectively. Then, nano-Al2O3 powder was weighed according to the mass percentage of aluminum oxide being 10wt%.

[0065] Comparative Example 6

[0066] This comparative example provides a method for preparing a solid electrolyte. The preparation process of the solid electrolyte is the same as that of Example 1, except that:

[0067] According to the molar ratio of BaCO3:ZrO2:Y2O3:Yb2O3 of 1:0.8:0.075:0.025, the masses of BaCO3, ZrO2, Y2O3 and Yb2O3 were calculated respectively, and BaCO3, ZrO2, Y2O3 and Yb2O3 were weighed respectively. Then, according to the mass percentage of aluminum oxide being 11wt%, nano-Al2O3 powder was weighed.

[0068] The properties of the solid electrolytes prepared in Example 1 and Comparative Examples 1 to 6 were tested:

[0069] CTE test: thermal dilatometer (RT setting 1000°C, heating rate 5°C / min);

[0070] Three-point bending test: span 10 mm, loading rate 0.5 mm / min;

[0071] Impedance spectroscopy: measuring electrical conductivity (400℃~800℃, frequency 0.1Hz~1MHz);

[0072] Long-term thermal cycle test: ( Cracks were observed after 50 cycles).

[0073] The performance test results of each embodiment 1 and comparative examples 1 to 6 are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] It can be seen from Example 1 and Comparative Examples 1 to 6 in Table 1 that by doping an appropriate amount of Y 3+ and Yb 3+ As the main phase, and adding an appropriate amount of nano-alumina as the second phase, the prepared solid electrolyte not only has good electrical conductivity, but also has good mechanical stability and thermal stability. 3+ When the doping amount is too much or too little, it will affect the mechanical stability and thermal stability of the solid electrolyte. When the amount of nano-alumina added to the solid electrolyte is too much, it will not only affect the electrical conductivity of the solid electrolyte, but also the mechanical stability and thermal stability of the solid electrolyte. When the amount of nano-alumina added to the solid electrolyte is too little, it will increase the brittleness of the solid electrolyte and make the solid electrolyte difficult to shape.

[0078] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A solid electrolyte, characterized in that The solid electrolyte has double rare earth doped barium zirconate as a main phase and aluminum oxide as a second phase; Wherein, the double rare earth doping elements are yttrium and ytterbium.

2. The solid electrolyte according to claim 1, characterized in that The molar ratio of yttrium to ytterbium in the double rare earth doped barium zirconate is 2:1 to 3:

1.

3. The solid electrolyte according to claim 1 or 2, characterized in that The chemical formula of the double rare earth doped barium zirconate is BaZr x Y y Yb z O w , among which, 0.75≤x≤0.95, 0.1≤y≤0.2, 0.03≤z≤0.07, 2.85≤w≤3.

05.

4. The solid electrolyte according to claim 1, characterized in that The mass of the aluminum oxide in the solid electrolyte is 8wt% to 10wt% of the mass of the main phase, and the aluminum oxide is nano-aluminum oxide.

5. A method for preparing a solid electrolyte, characterized in that: For preparing the solid electrolyte according to any one of claims 1 to 4, the preparation method comprises: The barium source, the zirconium source, the yttrium source and the ytterbium source are mixed evenly to prepare double rare earth doped barium zirconate; The double rare earth doped barium zirconate and aluminum oxide are uniformly mixed to prepare a precursor, and the precursor is sintered to prepare a solid electrolyte.

6. The method for preparing a solid electrolyte according to claim 5, wherein: The barium source, zirconium source, yttrium source and ytterbium source are uniformly mixed to prepare double rare earth doped barium zirconate, comprising: ball-milling a barium source, a zirconium source, a yttrium source, a ytterbium source, and an organic solvent to prepare a mixture; Pre-sintering the mixture to obtain a pre-sintered product; The pre-sintered product is ball-milled to prepare double rare earth-doped barium zirconate.

7. The method for preparing a solid electrolyte according to claim 6, wherein: The method of pre-sintering the mixture to obtain a pre-sintered product comprises: Under an air atmosphere, the mixture is heated from room temperature to a first preset temperature and kept at the first preset temperature for 3 to 5 hours to obtain the pre-sintered product, wherein the first preset temperature is 1150°C to 1250°C and the heating rate is 2°C / min to 4°C / min.

8. The method for preparing a solid electrolyte according to claim 5, wherein: The double rare earth doped barium zirconate and aluminum oxide are uniformly mixed to prepare a precursor, and the precursor is sintered to prepare a solid electrolyte, comprising: ball-milling the double rare earth-doped barium zirconate and alumina to prepare a precursor; In a wet H2 atmosphere, the precursor is subjected to a first sintering step at a second preset temperature to obtain a first sintered product; In a wet H2 atmosphere, the first sintered product is subjected to a second sintering step at a third preset temperature to produce a solid electrolyte; Wherein, the second preset temperature is higher than the third preset temperature.

9. The method for preparing a solid electrolyte according to claim 8, wherein: The second preset temperature is 1400° C. to 1500° C., and the first sintering time is 2 hours; The third preset temperature is 1250° C. to 1350° C., and the second sintering time is 6 hours; The second preset temperature is lowered to the third preset temperature at a cooling rate of 1°C / min to 3°C / min.

10. A battery, characterized in that: The invention comprises the solid electrolyte according to any one of claims 1 to 4, or the solid electrolyte prepared by the preparation method according to any one of claims 5 to 9.

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