A kind of inter-doped two-phase composite cathode material and preparation method thereof

Abstract

The present invention provides a mutually doped dual-phase composite cathode material and a preparation method thereof, belonging to the technical field of solid oxide fuel cells. The present invention provides a mutually doped dual-phase composite cathode material, the chemical composition of which is (1- x )Sr 1‑ax / (1‑x) Ce ax / (1‑x) Co 0.8 Fe 0.2 O 3‑δ ‑ x Ce 1‑a Sr a O 2‑δ , where 0 < x <1. The two-phase components of the inter-doped dual-phase composite cathode material provided by the present invention are prepared synchronously in one pot. The inter-doped dual-phase composite cathode material provided by the present invention has a reduced cobalt content, a reduced thermal expansion coefficient of the cathode material, and can be sintered more firmly with the electrolyte, thereby improving the electrochemical performance of the cathode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid oxide fuel cells, and in particular relates to an inter-doped two-phase composite cathode material and a preparation method thereof. Background Art

[0002] Solid oxide fuel cells (SOFCs) are power generation devices that directly convert hydrocarbon fuels into electricity, offering advantages such as high efficiency, low pollution, and fuel flexibility. Traditional SOFCs operate at temperatures exceeding 1000°C, placing stringent demands on electrode materials, cell components, and ancillary equipment. This also increases the construction and operation and maintenance costs of the cells. Therefore, medium- and low-temperature technologies (operating at 800°C and below) have become a major focus of SOFC development.

[0003] In medium and low temperature SOFC, SrCo 0.8 Fe 0.2 O 3-δ (SCF82, among which, δ Oxygen vacancies (OVs) have attracted significant attention. This cathode material, with its excellent catalytic performance and high electrical conductivity, holds great promise as a medium- and low-temperature SOFC cathode material. However, due to the influence of the cobalt crystal field and electron spin state, this cathode material has a large thermal expansion coefficient, making it difficult to sinter with mainstream SOFC electrolytes, resulting in reduced electrochemical performance. Therefore, improving the electrochemical performance of cathode materials has become a pressing technical challenge in this field. Summary of the Invention

[0004] The object of the present invention is to provide a co-doped dual-phase composite cathode material and a preparation method thereof. The co-doped dual-phase composite cathode material provided by the present invention has excellent electrochemical properties.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a mutually doped dual-phase composite cathode material, the chemical composition of which is (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ - x Ce 1-a Sr a O 2-δ , where 0 < x <1;

[0007] described x The second phase Ce 1-a Sr a O 2-δThe amount of material in the inter-doped dual-phase composite cathode material;

[0008] described a is the inter-doping concentration of Sr and Ce elements in the inter-doped dual-phase composite cathode material, a According to (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ and Ce 1-a Sr a O 2-δ The composition ratio and synthesis temperature of the product vary with the specific conditions. a <0.1;

[0009] described δ It is a general representation of lattice oxygen vacancies.

[0010] Preferably, the x is 0.15, 0.3, 0.45, 0.5, 0.6, 0.7, 0.8 or 0.9.

[0011] The present invention also provides a method for preparing the inter-doped dual-phase composite cathode material described in the above technical solution, comprising the following steps:

[0012] (1) mixing a strontium salt, a cobalt salt, an iron salt, a cerium salt, a first solvent, a complexing agent, and a second solvent to obtain a mixed solution;

[0013] (2) gelling and drying the mixed solution obtained in step (1) to obtain a xerogel;

[0014] (3) The dry gel obtained in step (2) is sequentially calcined and annealed to obtain an inter-doped dual-phase composite cathode material.

[0015] Preferably, the complexing agent in step (1) comprises citric acid and ethylenediaminetetraacetic acid.

[0016] Preferably, in step (1), the molar ratio of total metal ions, citric acid and ethylenediaminetetraacetic acid in the strontium salt, cobalt salt, iron salt and cerium salt is 1:(1-2):(1-2).

[0017] Preferably, the temperature of the gel in step (2) is 70-90°C.

[0018] Preferably, the drying temperature in step (2) is 150-180°C.

[0019] Preferably, the calcination temperature in step (3) is 400-450° C., and the calcination time is 5-10 h.

[0020] Preferably, the annealing holding temperature in step (3) is 900-1200° C., and the annealing holding time is 8-15 h.

[0021] Preferably, the annealing holding temperature in step (3) is 1000-1100° C., and the annealing holding time is 10 h.

[0022] The present invention provides a mutually doped dual-phase composite cathode material, the chemical composition of which is (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ - x Ce 1-a Sr a O 2-δ , where 0 < x <1; x The second phase Ce 1-a Sr a O 2-δ The amount ratio of the substance in the inter-doped dual-phase composite cathode material; a is the inter-doping concentration of Sr and Ce elements in the inter-doped dual-phase composite cathode material, a According to (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ and Ce 1-a Sr a O 2-δ The composition ratio and synthesis temperature of the product vary with the specific conditions. a <0.1; δ The inter-doped dual-phase composite cathode material provided by the present invention is dual-phase, one of which does not contain cobalt. When the two phases are combined together, compared with the single-phase cathode material SrCo 0.8 Fe 0.2 O 3-δ The cobalt content is reduced, the thermal expansion coefficient of the cathode material is reduced, and the cathode material can be sintered more firmly with the electrolyte, thereby improving the electrochemical performance of the cathode material. Experimental results show that the interfacial impedance between the interdoped dual-phase composite cathode material provided by the present invention and the electrolyte is 0.115~0.26Ω·cm 2 The single cell prepared with the inter-doped dual-phase composite cathode material provided by the present invention as the cathode has a maximum output power of 435~630mW·cm at 800℃. -2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is an SEM image of the inter-doped dual-phase composite cathode material prepared in Example 1;

[0024] Figure 2 The XRD pattern and standard PDF card of the inter-doped dual-phase composite cathode material prepared in Example 1;

[0025] Figure 3 This is the electrochemical impedance spectrum of the inter-doped dual-phase composite cathode material prepared in Example 1;

[0026] Figure 4 The curves of the operating voltage and power versus current density at 800° C. for a single cell prepared using the inter-doped dual-phase composite cathode material of Example 1 are shown;

[0027] Figure 5 This is an SEM image of the inter-doped dual-phase composite cathode material prepared in Example 2;

[0028] Figure 6 The XRD pattern and standard PDF card of the inter-doped dual-phase composite cathode material prepared in Example 2;

[0029] Figure 7 This is the electrochemical impedance spectrum of the inter-doped dual-phase composite cathode material prepared in Example 2;

[0030] Figure 8 The curves of the operating voltage and power versus current density at 800°C for a single cell prepared using the inter-doped dual-phase composite cathode material of Example 2 are shown;

[0031] Figure 9 The lattice atomic structure of the single-phase cathode material prepared in Comparative Example 1;

[0032] Figure 10 This is an SEM image of the single-phase cathode material prepared in Comparative Example 1;

[0033] Figure 11 The XRD pattern and standard PDF card of the single-phase cathode material prepared in Comparative Example 1;

[0034] Figure 12 This is the electrochemical impedance spectrum of the single-phase cathode material prepared in Comparative Example 1;

[0035] Figure 13 The curves of the operating voltage and power versus current density at 800°C for a single cell prepared using the inter-doped dual-phase composite cathode material of Comparative Example 1 are as follows;

[0036] Figure 14The lattice atomic structure of the electrolyte material CeO2 prepared in Comparative Example 2;

[0037] Figure 15 This is an SEM image of the electrolyte material CeO2 prepared in Comparative Example 2;

[0038] Figure 16 The XRD pattern and standard PDF card of the electrolyte material CeO2 prepared in Comparative Example 2;

[0039] Figure 17 This is an SEM image of the inter-doped dual-phase composite cathode material prepared in Example 3;

[0040] Figure 18 The XRD pattern and standard PDF card of the inter-doped dual-phase composite cathode material prepared in Example 3. DETAILED DESCRIPTION

[0041] The present invention provides a mutually doped dual-phase composite cathode material, the chemical composition of which is (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ - x Ce 1-a Sr a O 2-δ , where 0 < x <1. In the present invention, the x The second phase Ce 1- a Sr a O 2-δ The amount ratio of the substance in the inter-doped dual-phase composite cathode material; a is the inter-doping concentration of Sr and Ce elements in the inter-doped dual-phase composite cathode material, a According to (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ and Ce 1- a Sr a O 2-δ The specific conditions of the composition ratio, synthesis temperature and other factors vary, 0< a <0.1; δ It is a general representation of lattice oxygen vacancies.

[0042] In the present invention, the xPreferably it is 0.15, 0.3, 0.45, 0.5, 0.6, 0.7, 0.8 or 0.9.

[0043] In the present invention, the Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ The structure of is preferably a cubic perovskite structure; the Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ The space group is preferably Pm-3m (No.221); Ce in the inter-doped dual-phase composite cathode material 1-a Sr a O 2-δ The structure is preferably a cubic fluorite structure; the Ce 1-a Sr a O 2-δ The space group is preferably Fm-3m (No.225).

[0044] Compared with SOFC single-phase cathode material SrCo 0.8 Fe 0.2 O 3-δ (SCF82), Ce in the dual-phase composite cathode material provided by the present invention 1-a Sr a O 2-δ It can improve the oxygen ion transport performance of single-phase cathode materials, making Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ The grains of the phases are refined and the particles are more dispersed, so that the dual-phase composite cathode material exhibits better electrochemical performance; the dual-phase composite cathode material provided by the present invention has a lower cobalt content, which reduces the thermal expansion coefficient of the cathode material and can be sintered more firmly with the electrolyte, thereby improving the electrochemical performance of the cathode material and making the battery prepared using the dual-phase composite cathode material more stable.

[0045] The present invention also provides a method for preparing the inter-doped dual-phase composite cathode material described in the above technical solution, comprising the following steps:

[0046] (1) mixing a strontium salt, a cobalt salt, an iron salt, a cerium salt, a first solvent, a complexing agent, and a second solvent to obtain a mixed solution;

[0047] (2) gelling and drying the mixed solution obtained in step (1) to obtain a xerogel;

[0048] (3) The dry gel obtained in step (2) is sequentially calcined and annealed to obtain an inter-doped dual-phase composite cathode material.

[0049] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0050] The invention mixes strontium salt, cobalt salt, iron salt, cerium salt, a first solvent, a complexing agent and a second solvent to obtain a mixed solution.

[0051] In the present invention, the strontium salt is preferably a soluble strontium salt, more preferably strontium nitrate or strontium acetate; the cobalt salt is preferably a soluble cobalt salt, more preferably cobalt nitrate or cobalt acetate; the iron salt is preferably a soluble iron salt, more preferably ferric nitrate or ferric citrate; and the cerium salt is preferably a soluble strontium salt, more preferably cerium nitrate. In the present invention, the strontium salt, cobalt salt, iron salt, and cerium salt are used to provide the metal ions required in the interdoped dual-phase composite cathode material.

[0052] The present invention has no special limitation on the ratio of the strontium salt, cobalt salt, iron salt and cerium salt, which can be determined according to the actual required chemical composition.

[0053] In the present invention, the first solvent is preferably an inorganic solvent, more preferably deionized water. The present invention has no particular limitation on the amount of the first solvent, as long as the strontium salt, cobalt salt, iron salt and cerium salt are completely dissolved.

[0054] In the present invention, the complexing agent preferably includes citric acid and ethylenediaminetetraacetic acid. The present invention uses citric acid and ethylenediaminetetraacetic acid as complexing agents, which are low in cost, easy to obtain, and can improve the complexing effect.

[0055] In the present invention, the molar ratio of the total metal ions in the strontium salt, cobalt salt, iron salt, and cerium salt, citric acid, and ethylenediaminetetraacetic acid is preferably 1:(1-2):(1-2), more preferably 1:1:1. Limiting the molar ratio of the total metal ions in the strontium salt, cobalt salt, iron salt, and cerium salt, citric acid, and ethylenediaminetetraacetic acid to the above range can enhance the complexing effect.

[0056] In the present invention, the second solvent is preferably concentrated aqueous ammonia. The present invention has no particular limitation on the concentration and amount of the concentrated aqueous ammonia. Concentrated aqueous ammonia well known to those skilled in the art can be used as long as it dissolves the EDTA in the complexing agent and maintains the pH of the mixed solution within the range of 8 to 9.

[0057] In the present invention, the strontium salt, cobalt salt, iron salt, cerium salt, first solvent, complexing agent, and second solvent are preferably mixed by mixing the strontium salt, cobalt salt, iron salt, cerium salt, and first solvent, and then sequentially adding the complexing agent and second solvent. The present invention adopts a step-by-step addition method to achieve more uniform mixing of the raw materials.

[0058] The present invention has no special limitation on the operation of mixing the strontium salt, cobalt salt, iron salt, cerium salt and the first solvent and then sequentially adding the complexing agent and the second solvent, as long as the mixture is uniform.

[0059] After obtaining the mixed solution, the present invention sequentially gels and dries the mixed solution to obtain a xerogel.

[0060] In the present invention, the temperature of the gel is preferably 70-90°C. In one embodiment, the temperature of the gel can be 75°C, 80°C, or 85°C. The present invention does not specifically limit the gelation time, as long as the gel state is reached. Limiting the gelation temperature to the above range prevents excessive temperatures from causing the gel to boil and cause gel loss.

[0061] In the present invention, the drying temperature is preferably 150-180°C. As an embodiment, the drying temperature can be 160-170°C. The present invention does not specifically limit the drying time; drying to constant weight is sufficient. Drying in the present invention can further fully dry the gel, thereby obtaining a xerogel.

[0062] After obtaining the dry gel, the present invention sequentially calcines and anneals the dry gel to obtain an inter-doped two-phase composite cathode material.

[0063] In the present invention, the calcination temperature is preferably 400-450°C, and the calcination time is preferably 5-10 hours. In one embodiment, the calcination temperature can be 410°C, 420°C, 430°C, or 440°C, and the calcination time can be 6 hours, 7 hours, 8 hours, or 9 hours. The calcination method of the present invention can decompose the organic matter in the xerogel to form a precursor.

[0064] In the present invention, the calcination is preferably carried out in an air atmosphere; the calcination is preferably carried out in a muffle furnace. The present invention has no particular limitation on the type of the muffle furnace, and any equipment familiar to those skilled in the art can be used.

[0065] After the calcination is completed, the calcined product is preferably ground and dried in sequence. The grinding operation is not particularly limited in the present invention, and the product can be ground into an ink-like state.

[0066] The present invention has no particular limitation on the drying operation, and the product may be dried to a constant weight.

[0067] In the present invention, the annealing temperature is preferably 900-1200°C, and the annealing time is preferably 8-15 hours. As an embodiment, the annealing temperature can be 1000°C or 1100°C, and the annealing time can be 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, or 14 hours. The annealing method of the present invention can form a specific crystalline structure in the precursor.

[0068] In the present invention, the annealing is preferably performed in an air furnace. The present invention has no particular limitation on the type of the air furnace, and any equipment well known to those skilled in the art can be used.

[0069] The present invention adopts a simple "one-pot" synchronous preparation method with a simple process flow and high material preparation efficiency, which is conducive to large-scale production and application; the "one-pot" synchronous preparation can make the Sr and Ce elements dissolve in each other between the two phases, thereby achieving the effect of mutual doping, thereby improving the ion and electron transport performance of the mutually doped two-phase composite cathode material, so that the mutually doped two-phase composite cathode material exhibits better electrochemical performance.

[0070] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0071] Example 1

[0072] A mutually doped dual-phase composite cathode material, the chemical composition of which is (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ - x Ce 1-a Sr a O 2-δ ,in, x is 0.15;

[0073] described x The second phase Ce 1-a Sr a O 2-δ The amount of material in the inter-doped dual-phase composite cathode material;

[0074] described a is the inter-doping concentration of Sr and Ce elements in the inter-doped dual-phase composite cathode material, a According to (1-x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ and Ce 1-a Sr a O 2-δ The composition ratio and synthesis temperature of the product vary with the specific conditions. a <0.1;

[0075] described δ is a general representation of lattice oxygen vacancies;

[0076] The preparation method of the inter-doped dual-phase composite cathode material comprises the following steps:

[0077] (1) mixing strontium nitrate, cobalt nitrate, iron nitrate, cerium nitrate and deionized water to obtain a nitrate solution;

[0078] (2) adding citric acid and ethylenediaminetetraacetic acid to the nitrate solution obtained in step (1), stirring, and then adding concentrated ammonia water to obtain a brown-red mixed solution; wherein the molar ratio of total metal ions, citric acid and ethylenediaminetetraacetic acid is 1:1:1; and the pH of the mixed solution is 8.5;

[0079] (3) placing the mixed solution obtained in step (2) into an oven, first gelling at 80°C, and then drying at 150°C to obtain a xerogel;

[0080] (4) The dry gel obtained in step (3) is placed in a muffle furnace and calcined at 450°C for 5 hours, then ground into an ink-like state and dried, and then annealed in an air furnace at 1000°C for 10 hours to obtain an inter-doped dual-phase composite cathode material.

[0081] The SEM morphology analysis of the inter-doped dual-phase composite cathode material prepared in Example 1 was performed, and the results were as follows: Figure 1 As shown, Figure 1 This is the SEM image of the inter-doped dual-phase composite cathode material prepared in Example 1.

[0082] from Figure 1 It can be seen that the dual-phase characteristics are obvious in the inter-doped dual-phase composite cathode material, and one phase is uniformly attached to the other phase.

[0083] The XRD test of the inter-doped dual-phase composite cathode material prepared in Example 1 was performed, and the results were as follows: Figure 2 As shown, Figure 2 The XRD pattern and standard PDF card of the inter-doped dual-phase composite cathode material prepared in Example 1.

[0084] from Figure 2 It can be seen that the inter-doped dual-phase composite cathode material sample prepared in Example 1 is pure, and no third phase impurity peak appears except the two phases of the designed composition.

[0085] The inter-doped dual-phase composite cathode material prepared in Example 1 and La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 Electrochemical impedance spectroscopy was performed on the electrolyte interface, and the results were as follows: Figure 3 As shown, Figure 3 This is the electrochemical impedance spectrum of the inter-doped dual-phase composite cathode material prepared in Example 1.

[0086] Combine Figure 3 It is concluded that the inter-doped dual-phase composite cathode material prepared in Example 1 and La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 The interfacial impedance of the electrolyte is about 0.26Ω·cm 2 .

[0087] A single cell was prepared using the inter-doped dual-phase composite cathode material prepared in Example 1 as the cathode, wherein the anode was Ni-Ce 0.8 Sm 0.2 O 2-δ (Ni-SDC), the electrolyte is La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 The buffer layer between the anode and cathode is SDC. The curves of the working voltage and power of a single cell at 800℃ versus current density are shown in the figure below. Figure 4 As shown, the maximum power of a single cell is about 435mW·cm at 800℃. -2 .

[0088] Example 2

[0089] A mutually doped dual-phase composite cathode material, the chemical composition of which is (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ - x Ce 1-a Sr a O 2-δ ,in, x is 0.3;

[0090] The preparation method of the inter-doped dual-phase composite cathode material is the same as that in Example 1.

[0091] The SEM morphology analysis of the inter-doped dual-phase composite cathode material prepared in Example 2 was performed, and the results were as follows: Figure 5 As shown, Figure 5 This is the SEM image of the inter-doped dual-phase composite cathode material prepared in Example 2.

[0092] from Figure 5 It can be seen that the dual-phase characteristics are obvious in the inter-doped dual-phase composite cathode material, and one phase is uniformly attached to the other phase.

[0093] The XRD test of the inter-doped dual-phase composite cathode material prepared in Example 2 was performed, and the results were as follows: Figure 6 As shown, Figure 6 The XRD pattern and standard PDF card of the inter-doped dual-phase composite cathode material prepared in Example 2.

[0094] from Figure 6 It can be seen that the inter-doped dual-phase composite cathode material prepared in Example 2 is relatively pure, with no impurity peaks appearing.

[0095] The inter-doped dual-phase composite cathode material prepared in Example 2 and La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 Electrochemical impedance spectroscopy was performed on the electrolyte interface, and the results were as follows: Figure 7 As shown, Figure 7 This is the electrochemical impedance spectrum of the inter-doped dual-phase composite cathode material prepared in Example 2.

[0096] Combine Figure 7 It is concluded that the inter-doped dual-phase composite cathode material prepared in Example 2 and La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 The interfacial impedance of the electrolyte is about 0.115Ω·cm 2 .

[0097] A single cell was prepared using the inter-doped dual-phase composite cathode material prepared in Example 2 as the cathode, wherein the anode was Ni-SDC and the electrolyte was La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815The buffer layer between the anode and cathode is SDC. The curves of the working voltage and power of a single cell at 800℃ versus current density are shown in the figure below. Figure 8 As shown, the maximum power of a single cell is about 630mW·cm at 800℃. -2 , higher than the single-phase cathode SrCo 0.8 Fe 0.2 O 3-δ electrochemical performance.

[0098] Comparative Example 1

[0099] The chemical composition of the single-phase cathode material is SrCo 0.8 Fe 0.2 O 3-δ , that is, on the basis of Example 1 x Set to 0, and a is 0;

[0100] The preparation method of the single-phase cathode material comprises the following steps:

[0101] (1) mixing strontium nitrate, cobalt nitrate, iron nitrate and deionized water to obtain a nitrate solution;

[0102] (2) adding citric acid and ethylenediaminetetraacetic acid to the nitrate solution obtained in step (1), stirring, and then adding concentrated ammonia water to obtain a brown-red mixed solution; wherein the molar ratio of total metal ions, citric acid and ethylenediaminetetraacetic acid is 1:1:1; and the pH of the mixed solution is 8.5;

[0103] (3) placing the mixed solution obtained in step (2) into an oven, first gelling at 80°C, and then drying at 150°C to obtain a xerogel;

[0104] (4) The dry gel obtained in step (3) was placed in a muffle furnace and calcined at 450°C for 5 hours, then ground into an ink-like state and dried, and then annealed in an air furnace at 1000°C for 10 hours to obtain a single-phase cathode material.

[0105] The lattice atomic structure of the single-phase cathode material prepared in Comparative Example 1 is as follows: Figure 9 As shown in the figure, the 8 vertices represent CoFe, and the small ball in the middle represents Sr +2 , the remaining large balls represent O -2 .

[0106] from Figure 9 It can be seen that the single-phase cathode material SrCo 0.8 Fe 0.2 O 3-δ It has a cubic perovskite structure.

[0107] The single-phase cathode material prepared in Comparative Example 1 was subjected to SEM morphology analysis, and the results were as follows: Figure 10 As shown, Figure 10 This is the SEM image of the single-phase cathode material prepared in Comparative Example 1.

[0108] from Figure 10 It can be seen that SrCo 0.8 Fe 0.2 O 3-δ The particles are easily sintered and agglomerated at high temperatures. It can be seen that the grains are coarse and the grain boundaries are obvious, which is not conducive to expanding the catalytic surface.

[0109] The single-phase cathode material prepared in Comparative Example 1 was subjected to XRD testing, and the results were as follows: Figure 11 As shown, Figure 11 The XRD pattern and standard PDF card of the single-phase cathode material prepared in Comparative Example 1.

[0110] from Figure 11 It can be seen that the single-phase cathode material sample prepared in Comparative Example 1 is pure, without the appearance of impurity peaks.

[0111] Comparative Example 1 prepared single-phase cathode material and La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 Electrochemical impedance spectroscopy was performed on the electrolyte interface, and the results were as follows: Figure 12 As shown, Figure 12 This is the electrochemical impedance spectrum of the single-phase cathode material prepared in Comparative Example 1.

[0112] Combine Figure 12 It is concluded that the single-phase cathode material prepared in Comparative Example 1 is 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 The interfacial impedance of the electrolyte is about 0.28Ω·cm 2 .

[0113] A single cell was prepared using the single-phase cathode material prepared in Comparative Example 1 as the cathode, wherein the anode was Ni-SDC and the electrolyte was La 0.8 Sr 0.2 Ga 0.83 Mg 0.17 O 2.815 The buffer layer between the anode and cathode is SDC. The curves of the working voltage and power of a single cell at 800℃ versus current density are shown in the figure below. Figure 13 As shown, the maximum power of a single cell is about 402mW·cm at 800℃. -2 .

[0114] Comparative Example 2

[0115] On the basis of Example 1 x If set to 1, the electrolyte material CeO2 is obtained, which is not suitable for use as a cathode alone.

[0116] The lattice atomic structure of the electrolyte material CeO2 prepared in Comparative Example 2 is as follows Figure 14 As shown, the small balls in the figure represent Ce +4 , the big ball represents O -2 .

[0117] from Figure 14 It can be seen that the single-phase CeO2 has a fluorite structure.

[0118] The electrolyte material CeO2 prepared in Comparative Example 2 was subjected to SEM morphology analysis, and the results were as follows: Figure 15 As shown, Figure 15 This is the SEM image of the electrolyte material CeO2 prepared in Comparative Example 2.

[0119] from Figure 15 It can be seen that the poor conductivity of the electrolyte material CeO2 prepared in Comparative Example 2 causes a certain degree of distortion in the imaging.

[0120] The electrolyte material CeO2 prepared in Comparative Example 2 was subjected to XRD test, and the results were as follows: Figure 16 As shown, Figure 16 The XRD pattern and standard PDF card of the electrolyte material CeO2 prepared in Comparative Example 2.

[0121] from Figure 16 It can be seen that the electrolyte material CeO2 sample prepared in Comparative Example 2 is pure and has no impurity peak.

[0122] Example 3

[0123] On the basis of Example 1 x It is set to 0.45, and other conditions remain unchanged to obtain an inter-doped two-phase composite cathode material.

[0124] The SEM morphology analysis of the inter-doped dual-phase composite cathode material prepared in Example 3 was performed, and the results were as follows: Figure 17 As shown, Figure 17 This is the SEM image of the inter-doped dual-phase composite cathode material prepared in Example 3.

[0125] from Figure 17 It can be seen that the dual-phase characteristics are obvious in the inter-doped dual-phase composite cathode material, and one phase is uniformly attached to the other phase.

[0126] The XRD test of the inter-doped dual-phase composite cathode material prepared in Example 3 was performed, and the results were as follows: Figure 18 As shown, Figure 18 The XRD pattern and standard PDF card of the inter-doped dual-phase composite cathode material prepared in Example 3.

[0127] from Figure 18 It can be seen that the inter-doped dual-phase composite cathode material prepared in Example 3 has a pure phase composition and no impurity peak appears.

[0128] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An inter-doped dual-phase composite cathode material, characterized in that: The chemical composition is (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ - x Ce 1-a Sr a O 2-δ ,in, described x The second phase Ce 1-a Sr a O 2-δ The amount of material in the inter-doped dual-phase composite cathode material; described a is the inter-doping concentration of Sr and Ce elements in the inter-doped dual-phase composite cathode material, a According to (1- x )Sr 1-ax / (1-x) Ce ax / (1-x) Co 0.8 Fe 0.2 O 3-δ and Ce 1-a Sr a O 2-δ The composition ratio and synthesis temperature of the product vary with the specific conditions. a <0.1; described δ is a general representation of lattice oxygen vacancies; described x is 0.

3.

2. A method for preparing an inter-doped dual-phase composite cathode material, using the inter-doped dual-phase composite cathode material according to claim 1, characterized in that: The steps include: (1) mixing a strontium salt, a cobalt salt, an iron salt, a cerium salt, a first solvent, a complexing agent, and concentrated ammonia water to obtain a mixed solution; (2) gelling and drying the mixed solution obtained in step (1) to obtain a xerogel; (3) The dry gel obtained in step (2) is sequentially calcined and annealed to obtain an inter-doped dual-phase composite cathode material.

3. The preparation method according to claim 2, characterized in that The complexing agent in step (1) includes citric acid and ethylenediaminetetraacetic acid.

4. The preparation method according to claim 3, characterized in that In the step (1), the molar ratio of total metal ions, citric acid and ethylenediaminetetraacetic acid in the strontium salt, cobalt salt, iron salt and cerium salt is 1:(1-2):(1-2).

5. The preparation method according to claim 2, characterized in that The temperature of the gel in step (2) is 70-90°C.

6. The preparation method according to claim 2, characterized in that The drying temperature in step (2) is 150-180°C.

7. The preparation method according to claim 2, characterized in that The calcination temperature in step (3) is 400-450° C., and the calcination time is 5-10 hours.

8. The preparation method according to claim 2, characterized in that The annealing holding temperature in step (3) is 900-1200° C., and the annealing holding time is 8-15 hours.

9. The preparation method according to claim 8, characterized in that The annealing holding temperature in step (3) is 1000-1100° C., and the annealing holding time is 10 h.

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