Lanthanum aluminate-cerium oxide composite electrolyte and preparation method thereof

Abstract

The invention provides a lanthanum aluminate-cerium oxide composite electrolyte and a preparation method thereof, and relates to the technical field of solid oxide fuel cells. The lanthanum aluminate-cerium oxide composite electrolyte comprises a LaAl < 0.9 > Cu < 0.1 > O < 3-delta >-Ce < 0.8 > Gd < 0.2 > O < 2-delta > composite material, and the total conductivity of the LaAl < 0.9 > Cu < 0.1 > O < 3-delta >-Ce < 0.8 > Gd < 0.2 > O < 2-delta > composite material is 0.028 S / cm.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cells, and particularly relates to a lanthanum aluminate-cerium oxide composite electrolyte and a preparation method thereof. Background Art

[0002] A solid oxide fuel cell (SOFC) is an all-solid-state fuel cell that efficiently converts the chemical energy of various fuel gases, such as natural gas, landfill gas, coal gas, methanol, etc., into electrical energy at medium and high temperatures. Due to its easy use, low cost, and no potential safety risks, it has attracted wide attention in the current energy market.

[0003] The most common electrolyte of SOFC is yttria-stabilized zirconia (Zr 0.9 Y 0.1 O 1.9 ; YSZ), lanthanum strontium gallium magnesium oxide (La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-δ ; LSGM), rare earth zirconates, samarium-doped ceria (SDC), gadolinium-doped ceria (GDC or CGO), etc. These electrolytes have low ionic conductivity, and limited by the low ionic conductivity of the existing electrolytes, the operating temperature needs to be about 1000 °C, which greatly increases the difficulties in the selection and preparation of battery and system supporting materials. Therefore, providing an electrolyte with higher ionic conductivity has become a technical problem that urgently needs to be solved in the field of solid oxide fuel cells. Summary of the Invention

[0004] (1) Technical Problem to be Solved

[0005] Aiming at the deficiencies of the prior art, the present invention provides a lanthanum aluminate-cerium oxide composite electrolyte and a preparation method thereof, which solve the technical problem of low ionic conductivity of the electrolyte of the existing solid oxide fuel cell.

[0006] (2) Technical Solution

[0007] To achieve the above object, the present invention is realized through the following technical solutions:

[0008] In the first aspect, the present invention provides a lanthanum aluminate-cerium oxide composite electrolyte, including a LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material.

[0009] In a second aspect, the present invention provides a method for preparing the lanthanum aluminate-cerium oxide composite electrolyte described in the first aspect, comprising the following steps:

[0010] S1. Provide La2O3, Al2O3, and CuO powders. Put the La2O3, Al2O3, and CuO powders into any one of liquid flammable alkanes, alcohols, ketones, aldehydes, and ethers and grind for 1 - 3 h, then calcine at 800 - 1000 °C for 5 - 7 h to obtain LaAl 0.9 Cu 0.1 O 3-δ powder; Add the LaAl 0.9 Cu 0.1 O 3-δ powder to a 4 - 6% PVA solution, grind and sieve through 90 - 110 mesh, then press into tablets at 9 - 11 MPa, and then keep warm at 1100 - 1300 °C for 3 - 5 h. After cooling, obtain LaAl 0.9 Cu 0.1 O 3-δ ceramics;

[0011] S2. Provide CeO2 and Gd2O3 powders. After mixing, put them into any one of liquid flammable alkanes, alcohols, ketones, aldehydes, and ethers and grind for 1 - 3 h, calcine at 800 - 1000 °C for 5 - 7 h, cool to obtain a dry powder mixture. Then add a 4 - 6% PVA solution to the dry powder mixture, grind and sieve through 90 - 110 mesh, press into tablets at 7 - 9 MPa, and sinter in air at 1200 - 1400 °C for 5 - 7 h. After cooling, obtain Ce 0.8 Gd 0.2 O 2-δ ceramics;

[0012] S3. Mix the LaAl 0.9 Cu 0.1 O 3-δ ceramics and Ce 0.8 Gd 0.2 O 2-δ ceramics evenly, heat by microwave, with a microwave power of 500 - 700 W, a heating rate of 8 - 12 ° / min, control the temperature at 700 - 900 °C, keep warm for 20 - 40 min, cool to room temperature, grind into powder again. Add a 4 - 6% PVA solution to the powder, mix evenly, press into tablets at 9 - 11 MPa, and sinter in air at 1100 - 1300 °C for 3 - 5 h. After cooling to room temperature, obtain LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material.

[0013] Preferably, in the step S3, LaAl 0.9 Cu 0.1 O 3-δ ceramics and Ce 0.8 Gd 0.2 O 2-δ ceramics have a molar ratio of 90:10 to 75:25.

[0014] Preferably, the molar ratio of LaAl 0.9 Cu 0.1 O 3-δ ceramics and Ce 0.8 Gd 0.2 O 2-δ ceramics is 80:20.

[0015] Preferably, when the molar ratio of LaAl 0.9 Cu 0.1 O 3-δ ceramics and Ce 0.8 Gd 0.2 O 2-δ ceramics is 80:20, the LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material has an ionic conductivity of 0.022 S / cm at 800 °C.

[0016] Preferably, when the molar ratio of LaAl 0.9 Cu 0.1 O 3-δ ceramics and Ce 0.8 Gd 0.2 O 2-δ ceramics is 80:20, the LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material has an ionic conductivity of 0.028 S / cm at 850 °C.

[0017] (III) Beneficial effects

[0018] The present invention provides a lanthanum aluminate-cerium oxide composite electrolyte and a preparation method thereof. Compared with the prior art, the following beneficial effects are achieved:

[0019] The lanthanum aluminate-cerium oxide composite electrolyte provided by the present invention includes LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd0.2 O 2-δ Composite material, using Cu-doped lanthanum aluminate as the matrix material, introducing Gd-doped cerium oxide to prepare LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ Composite material, in LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ In the composite material, LaAl 0.9 Cu 0.1 O 3-δ and Ce 0.8 Gd 0.2 O 2-δ formed a heterojunction interface. Due to the differences in charge carrier concentration and redox potential, this heterojunction interface induced the generation of a space charge layer, resulting in an increase in the oxygen vacancy concentration and a decrease in the migration energy barrier in the interface region, thereby constructing an efficient ion migration path, and thus improving the ionic conductivity of LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material. In addition, introducing LaAl 0.8 Gd 0.2 O 2-δ into the Ce 0.9 Cu 0.1 O 3-δ material caused a decrease in the grain boundary resistance, thereby improving the conductivity of LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material. The total conductivity of the prepared LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material was increased to 0.028 S / cm. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 are the XRD patterns of the LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite ceramic materials W1, W2, W3, and W4 prepared in Examples 1-4;

[0022] Figure 2 are the LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ scanning electron microscope (SEM) images of the composite ceramic materials W1, W2, W3, and W4 prepared in Examples 1-4,

[0023] wherein,

[0024] a - W1, b - W2, c - W3, and d - W4;

[0025] Figure 3 are the LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ electrochemical impedance diagrams of the composite ceramic materials W1, W2, W3, and W4;

[0026] Figure 4 are the LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ total conductivity curves of the composite ceramic materials W1, W2, W3, and W4 at different temperatures;

[0027] Figure 5 are the LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2O 2-δ Arrhenius plots of composite ceramic materials W1, W2, W3, and W4

[0028] Figure 6 is LaAl prepared in Example 3 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ Coefficient of thermal expansion of composite ceramic material W3

[0029] Figure 7 is LaAl of Examples 1 to 4 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ Schematic diagram of the preparation process of the composite ceramic material Detailed implementation manners

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] To better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the accompanying drawings of the specification and specific implementation manners.

[0032] Examples 1 to 4

[0033] This example provides a preparation method for a lanthanum aluminate-cerium oxide composite electrolyte. The raw materials used in the experiment are pure La2O3, Al2O3, CuO, CeO2 (purity 99.99%, Aladdin), and Gd2O3 (purity 99.99%, Aladdin) powders. As Figure 7 shown, it includes the following steps:

[0034] First step: Calculate the experimental drugs according to the amount of the target product of the experiment and record them in a table.

[0035] Second step: After cleaning the mortar and tablet press mold with alcohol, dry them, and then clean a certain number of crucibles and dry them for standby.

[0036] Step 3: Take 0.005 mol of La2O3, 0.0045 mol of Al2O3, and 0.001 mol of CuO powder, add them to 20 mL of ethanol, and grind for 2 hours to ensure full contact of the powders. Transfer the powders to a crucible and calcine in a high-temperature furnace at 900 °C for 6 h to obtain LaAl 0.9 Cu 0.1 O 3-δ powder.

[0037] Step 4: Add the prepared LaAl 0.9 Cu 0.1 O 3-δ powder to 1 mL of 5% PVA solution, grind, and sieve through 100 mesh. At a standard of 0.5 g / tablet, uniaxially press into circular tablets in a stainless-steel mold at a pressure of 10 MPa. Then place in a muffle furnace, heat to 1200 °C at a rate of 4 °C / min, sinter at 1200 °C for 4 h, and after cooling and taking out, obtain LaAl 0.9 Cu 0.1 O 3-δ black ceramic blocks, which are crushed and ground into powder.

[0038] Step 5: Prepare Ce 0.8 Gd 0.2 O 2-δ , take 0.02 mol of CeO2 and 0.0025 mol of Gd2O3 powder, mix them, and grind in 30 mL of ethanol for 2 hours. Then calcine the powder in a high-temperature furnace at 900 °C for 6 h and slowly cool in a muffle furnace to obtain a dry powder mixture.

[0039] Step 6: Then add 1 mL of 5% PVA solution to the dry powder mixture to enhance the binding between powder particles. Grind and sieve the prepared powder through 100 mesh again. Use a tablet press to press into a circular tablet with a diameter of 12 mm and a thickness of 2 mm at 8 MPa, and sinter in air at 1300 °C for 6 hours. After cooling and taking out, obtain Ce 0.8 Gd 0.2 O 2-δ yellow ceramic blocks, which are crushed and ground into powder.

[0040] Step 7: According to the LaAl 0.9 Cu 0.1 O 3-δ and Ce 0.8 Gd 0.2 O 2-δ compound molar ratio in Table 1, mix the prepared LaAl 0.9 Cu 0.1 O 3-δ black ceramic powder and Ce 0.8 Gd 0.2 O2-δ The yellow ceramic powder is mixed evenly, placed in a crucible, and put into a microwave oven for heating. The microwave power is set to 600 W, the heating rate is 10 ° / min, the temperature is controlled at 800 °C, and it is kept warm for 30 min to promote the reaction. The sample is taken out, ground again after cooling to room temperature, and the agglomerated particles are broken up to obtain powder A. The obtained powder A is mixed evenly with 1 mL of 5% PVA solution as a binder, pressed into a disc at 10 MPa, and sintered in air at 1200 °C for 4 hours. After sintering is completed, it is cooled to room temperature, the sample is taken out, and pure LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite ceramic material.

[0041] Table 1 shows the molar ratios of LaAl 0.9 Cu 0.1 O 3-δ and Ce 0.8 Gd 0.2 O 2-δ in Examples 1 to 4.

[0042]

[0043] Comparative Example 1

[0044] The difference between this comparative example and Example 1 is that it only includes the fifth and sixth steps for preparing Ce 0.8 Gd 0.2 O 2-δ . The prepared Ce 0.8 Gd 0.2 O 2-δ ceramic material is numbered W0.

[0045] The LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite ceramic materials (i.e., LACO-CGO composite materials) W1, W2, W3, W4 prepared in Examples 1 to 4 and the Ce 0.8 Gd 0.2 O 2-δ ceramic material W0 prepared in Comparative Example 1 are subjected to performance tests as follows.

[0046] (1) XRD analysis

[0047] XRD tests are respectively carried out on the composite materials W1, W2, W3 and W4, and their XRD patterns are shown in Figure 1 . It includes its base material LaAl 0.9Cu 0.1 O 3-δ (LACO) and Ce 0.8 Gd 0.2 O 2-δ (CGO). The symbols and “●” represent LACO and CGO respectively.

[0048] From Figure 1 it can be seen that there is no impurity phase in the LACO-CGO composites W1, W2, W3 and W4, indicating that no significant chemical reaction or phase change occurred during the composite process. The main peak of LACO is still obvious, indicating that the material maintains its perovskite structure. As the content of CGO increases, the intensity of its corresponding diffraction peak gradually increases, but weakens at W4, indicating that the content of the CGO phase gradually increases and then decreases in the composite material. In addition, the full width at half maximum of each diffraction peak does not change significantly, indicating that the grain size distribution of the prepared LACO-CGO composites W1, W2, W3 and W4 is relatively uniform, and no obvious lattice distortion is caused by the introduction of CGO.

[0049] (2) Grain size

[0050] The grain sizes of W0, W1, W2, W3 and W4 are calculated using the Scherrer formula:

[0051]

[0052] where D is the grain size,

[0053] λ is the X-ray wavelength,

[0054] β is the full width at half maximum of the diffraction peak of the measured sample,

[0055] θ is the Bragg diffraction angle.

[0056] The grain sizes of W0, W1, W2, W3 and W4 are shown in Table 2. Due to the introduction of LACO, compared with W0, the grain sizes of W1, W2, W3 and W4 are larger, and their structures have more oxygen vacancies. Therefore, the electrical conductivities of W1, W2, W3 and W4 are higher than that of W0.

[0057] (3) Relative density

[0058] The relative densities of W0, W1, W2, W3 and W4 are calculated by the following formula:

[0059]

[0060] where ρ mThe volume density is measured according to Archimedes' principle. The test results are shown in Table 2. It can be seen that the relative densities of the LACO-CGO composites W1, W2, W3, and W4 are all above 90%, while that of W0 is only 85.6%. The higher the relative density, the more beneficial it is to ionic conduction and the higher the ionic conductivity.

[0061] Table 2 Test Results of the Prepared Materials in Examples 1-4 and Comparative Example 1

[0062] Sample Grain size D (nm) Conductivity at 800 °C (S / cm) <![CDATA[ρ m (g / cm 3 )]]> <![CDATA[ρ th (g / cm 3 )]]> <![CDATA[ρ relative (%)]]> W0 24 0.01 6.18 7.22 85.6 W1 30 0.018 6.07 6.58 92.3 W2 37 0.020 6.18 6.63 93.2 W3 45 0.022 6.35 6.66 95.4 W4 35 0.019 6.10 6.70 91.1

[0063] (4) SEM analysis

[0064] The microstructures of the LACO-CGO composites W1, W2, W3, and W4 were analyzed using a scanning electron microscope (SEM) to understand their surface morphologies. The microstructure analysis was carried out after the specimens were coated with platinum (Pt). Figure 2 The microstructural images of the LACO-CGO composites W1, W2, W3, and W4 are shown.

[0065] From Figure 2 it can be observed that the surfaces of the micro-particles in the LACO-CGO composites W1, W2, W3, and W4 are complete and smooth, without obvious pores, and the particle spacing is small, achieving a relatively high density. It shows that the sintering temperature of 1200 °C is sufficient to achieve a dense microstructure on the surface of the sintered samples.

[0066] (5) Electrochemical performance analysis

[0067] Impedance spectroscopy (EIS) represents the complex impedance as a Nyquist plot, with the real part and the negative imaginary part plotted on the x-axis and y-axis respectively. The impedance diagrams of all composite components were fitted using the equivalent circuit R(QR)(QR) by ZSimpwin software. This equivalent circuit consists of three parallel resistors (R) and constant phase elements (CPE) connected in series. The fitting provides information on the grain resistance (R gi ), the grain boundary resistance (R gb ), and the electrode polarization resistance (R el ). The total resistance (R t = R gi + R gb ) was calculated based on the intercept of the semi-circle, thereby studying the electrochemical characteristics of the LACO-CGO composites W1, W2, W3, and W4. The electrochemical impedance diagrams of W1, W2, W3, and W4 are shown in Figure 3 . By observing Figure 3 , the impedance data R t at 500 °C and 700 °C can be obtained, and then according to the formula:

[0068]

[0069] Among them,

[0070] σ t : Conductivity, with the unit of S·cm -1 ;

[0071] R t : Total resistance, with the unit of Ω;

[0072] d: Thickness of the electrolyte, with the unit of cm;

[0073] A: Cross-sectional area of the electrolyte, with the unit of cm 2 .

[0074] The ionic conductivities (σ t ) of the LACO-CGO composites W1, W2, W3, and W4 at 500 °C and 700 °C can be obtained. At 500 °C, the ionic conductivities of W1, W2, W3, and W4 are 0.0017 S / cm, 0.0021 S / cm, 0.0023 S / cm, and 0.0019 S / cm respectively. At 700 °C, the ionic conductivities of W1, W2, W3, and W4 are 0.0095 S / cm, 0.011 S / cm, 0.012 S / cm, and 0.0098 S / cm respectively.

[0075] Using the above method, the conductivities of the LACO-CGO composites W1, W2, W3, and W4 at 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C, 800 °C, and 850 °C are respectively tested and calculated. The test results are shown in Figure 4 , and it can be seen from Figure 4 that the conductivities of the LACO-CGO composites W1, W2, W3, and W4 increase with the increase of temperature. At 800 °C, the conductivities of the LACO-CGO composites W1, W2, W3, and W4 are 0.018 S / cm, 0.020 S / cm, 0.022 S / cm, and 0.019 S / cm respectively. At 850 °C, the conductivity of W3 is 0.028 S / cm. While at 800 °C, the conductivity σ t of the CGO electrolyte material prepared in Comparative Example 1 is 0.01 S / cm, and at 850 °C, the conductivity σ tis 0.012 S / cm. Therefore, by modifying LACO with composite CGO, the ionic conductivity of LACO can be significantly improved. This is because when lanthanum aluminate doped with Cu is used as the matrix material, introducing gadolinium-doped ceria, a heterojunction interface is formed between LACO and CGO. Due to the differences in charge carrier concentration and redox potential at this heterojunction interface, a space charge layer is induced, resulting in an increase in the oxygen vacancy concentration and distribution uniformity in the interface region and a decrease in the migration energy barrier. Thus, an efficient ionic migration path is constructed, which is more conducive to ion transport and shows an increasing trend in ionic conductivity to a certain extent. The vacancies in CGO will interact with the lattice of LACO near the heterojunction interface, making the diffusion channels for ions, especially oxygen ions, in the LACO-CGO composite more unobstructed. In addition, when LACO is introduced into CGO, as the content of CGO increases and the content of LACO decreases, the grain boundary resistance increases, which hinders ion transport to a certain extent, and the conductivity shows a downward trend within a certain range. Considering the above two main factors, when the molar percentage of CGO in the LACO-CGO composite is 20%, the ionic conductivity reaches the maximum. When the proportion of CGO exceeds 20%, the influence of grain boundary resistance dominates, causing the ionic conductivity to decrease rapidly.

[0076] In addition, with the increase in temperature, the conductivity of the LACO-CGO composite also increases. This is because as the temperature rises, the resistance value of the grains becomes larger, while the resistance value of the grain boundaries becomes smaller. As a result, the diffusion resistance of ions is greatly reduced, the ion movement rate accelerates, and ion diffusion becomes more unobstructed, so the conductivity increases.

[0077] In the LACO-CGO composite, when the molar percentage of CGO in the LACO-CGO composite does not exceed 20%, the conductivity of the composite increases with the increase in the CGO composite amount. When the molar percentage of CGO in the LACO-CGO composite exceeds 20%, the conductivity of the composite gradually decreases. When the molar percentage of CGO in the LACO-CGO composite is 20% (i.e., W3), the conductivity of the prepared LACO-CGO composite is the highest, and its conductivity σ t at 850 °C is 0.028 S / cm. And as Figure 5 shown, the In(σ t ·T)-1000·T -1 relationship diagrams of the LACO-CGO composites W1, W2, W3, and W4 satisfy the Arrhenius relationship. The activation energy can be calculated from the slope of the simulated straight line. After calculation, the activation energy E a of W3 is 0.72 eV.

[0078] (6) Thermal expansion coefficient

[0079] The thermal expansion method was adopted to investigate the thermal expansion coefficient (TEC) of the LACO-CGO composite material W3, and the test results are shown in Figure 6 . TEC is a key factor determining the application of solid oxide fuel cells. As a valuable electrolyte material, the prepared composite material should exhibit a TEC that is coordinated with its surrounding environment. If this balance is not achieved, microcracks will form at the module joints, ultimately compromising the integrity of the battery.

[0080] Figure 6 shows the calculated values of the linear thermal expansion coefficient (ΔL / L0) of the LACO-CGO composite electrolyte W3 in the temperature range of 30 °C to 1000 °C. The thermal expansion coefficient was determined using the equation based on the thermal expansion curve of the LACO-CGO composite electrolyte:

[0081]

[0082] L0 and L represent the initial and final lengths, while T0 and T correspond to the start and end temperatures of the experiment. The calculated value of the thermal expansion coefficient (TEC) of W3 in the range of 30 - 1000 °C is 11.2×10 -6 K -1 . Therefore, within the specified temperature range, the TEC of the composite material W3 is consistent with existing electrode materials, such as the cathode materials LaNiO3, LaCoO3, and LaMnO3, Ni-YSZ, LaBaCo2O 5+δ , La 0.5 Pr 0.5 BaCo 2-x Fe x O 5+δ , La 0.75 Sr 0.25 , Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF), La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3 (LSCF), the anode materials BaCe 0.36 Fe 0.64 O 3-δ (BCF36), LaSrO 3-δ , SrTiO 3-δ , and it can be used as a potential solid electrolyte for solid oxide fuel cells.

[0083] This application discloses a lanthanum aluminate-ceria composite ionic semiconductor electrolyte. Using Cu-doped lanthanum aluminate as the matrix material, Gd-doped ceria is introduced to prepare LaAl0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ Composite material, with high ionic conductivity, significantly improves the working efficiency of fuel cells. The XRD results show that there is no impurity phase in the composite material, indicating that no significant chemical reaction or phase change occurs during the composite process. The full width at half maximum of each diffraction peak does not change significantly, indicating that the grain size distribution of the composite material is relatively uniform and there is no obvious lattice distortion caused by the introduction of CGO. The SEM results show that the surface of the microscopic particles is complete and smooth, without obvious pores, and the particle spacing is small, achieving a relatively high density. Electrochemical analysis shows that when the molar percentage of CGO in the LACO-CGO composite material is 20%, the conductivity of the prepared LACO-CGO composite material is the highest. The conductivity σ t at 850 °C is 0.028 S / cm, and the activation energy E a = 0.72 eV, enabling the LACO-CGO composite material to have a high ion transport ability and enhancing the ion transport rate of the LACO-CGO composite material. In addition, the LACO-CGO composite material prepared in this application has good performance compatible with its surrounding environment, can ensure the stable performance output of fuel cell devices, and has good compatibility with existing electrode materials, and is a promising electrolyte material.

[0084] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0085] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0086] The present invention illustrates the detailed process flow of the present invention through the above embodiments. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A lanthanum aluminate-cerium oxide composite electrolyte, characterized in that, including LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material 2. The preparation method of the lanthanum aluminate-cerium oxide composite electrolyte according to claim 1, characterized in that, The steps include the following: S1. Provide La2O3, Al2O3, and CuO powders. Put the La2O3, Al2O3, and CuO powders into at least one of liquid flammable alkanes, alcohols, ketones, aldehydes, and ethers and grind for 1 - 3 h, then calcine at 800 - 1000 °C for 5 - 7 h to obtain LaAl 0.9 Cu 0.1 O 3-δ powder; Add the LaAl 0.9 Cu 0.1 O 3-δ powder to a 4 - 6% PVA solution, grind and sieve through 90 - 110 mesh, then press into tablets at 9 - 11 MPa, and then keep warm at 1100 - 1300 °C for 3 - 5 h. After cooling, obtain LaAl 0.9 Cu 0.1 O 3-δ ceramics; S2. Provide CeO2 and Gd2O3 powders. After mixing, put them into at least one of liquid flammable alkanes, alcohols, ketones, aldehydes, and ethers, ethanol, and grind for 1 - 3 h. Then calcine at 800 - 1000 °C for 5 - 7 h, and cool to obtain a dry powder mixture. Next, add a 4 - 6% PVA solution to the dry powder mixture, grind and sieve through 90 - 110 meshes, press into tablets under 7 - 9 MPa, and sinter in air at 1200 - 1400 °C for 5 - 7 h. After cooling, obtain Ce 0.8 Gd 0.2 O 2-δ ceramics; S3. Mix the LaAl 0.9 Cu 0.1 O 3-δ ceramics and Ce 0.8 Gd 0.2 O 2-δ ceramics evenly, heat them by microwave with a microwave power of 500 - 700 W, a heating rate of 8 - 12 °C / min, control the temperature at 700 - 900 °C, keep warm for 20 - 40 min, cool to room temperature, grind them into powder again, add a 4 - 6% PVA solution to the powder, press them into tablets evenly at 9 - 11 MPa, sinter them in air at 1100 - 1300 °C for 3 - 5 h, cool to room temperature to obtain the LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material.

3. The preparation method according to claim 2, characterized in that In S3, LaAl 0.9 Cu 0.1 O 3-δ and Ce 0.8 Gd 0.2 O 2-δ have a molar ratio of 90:10 to 75:

25.

4. The preparation method according to claim 3, characterized in that, The LaAl 0.9 Cu 0.1 O 3-δ ceramics and Ce 0.8 Gd 0.2 O 2-δ ceramics have a molar ratio of 80:

20.

5. The preparation method according to claim 4, characterized in that, The LaAl 0.9 Cu 0.1 O 3-δ Ceramics and Ce 0.8 G 0.2 O 2-δ When the ceramic molar ratio is 80:20, the prepared LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 G 0.2 O 2-δ The ionic conductivity of the composite material at 800℃ is 0.022S / cm.

6. The preparation method according to claim 4, characterized in that, The LaAl 0.9 Cu 0.1 O 3-δ ceramics and Ce 0.8 Gd 0.2 O 2-δ When the molar ratio of the ceramics is 80:20, the prepared LaAl 0.9 Cu 0.1 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ composite material has an ionic conductivity of 0.028 S / cm at 850 °C.

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