Two-phase composite material powder, method for preparing two-phase composite material powder based on cooperation of sol-gel method and spray drying and application of two-phase composite material powder

Abstract

The invention provides two-phase composite material powder, a method for preparing the two-phase composite material powder based on cooperation of a sol-gel method and spray drying and application of the two-phase composite material powder, and belongs to the technical field of composite material preparation. The preparation method comprises the following steps: carrying out spray drying and calcination on a sol precursor aqueous solution containing a first-phase metal source and a second-phase metal source to obtain two-phase composite material powder; the first-phase metal source and the second-phase metal source independently comprise nitrate and / or acetate, metal elements in the first-phase metal source comprise first rare earth metal and first transition metal, and metal elements in the second-phase metal source comprise second rare earth metal and / or second transition metal; and when the first-phase metal source and the second-phase metal source in the sol precursor aqueous solution are both nitrate, the sol precursor aqueous solution also comprises alpha-hydroxycarboxylic acid. The two-phase composite material powder prepared by the method provided by the invention has uniform components, and is suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material preparation, and particularly relates to a two-phase composite material powder and a method for preparing the two-phase composite material powder based on a sol-gel method and spray drying and application. BACKGROUND

[0002] The global consumption of fossil fuels continues to increase, leading to an increase in carbon dioxide emissions. A solid oxide fuel cell (SOFC) is a power generation device that directly converts chemical energy of fuel into electrical energy, and has higher efficiency because it is not limited by the Carnot cycle. A solid oxide electrolytic cell (SOEC) can be regarded as the reverse mode of the SOFC, and its high-temperature working condition can overcome the disadvantage of limited electrolysis reaction activity at low temperature, realizing efficient electrolysis of water and carbon dioxide to produce hydrogen, carbon monoxide and other renewable fuels. The cycle of realizing hydrogen production and power generation based on SOFC / SOEC (hereinafter collectively referred to as Solid Oxide Cell, SOC) technology not only achieves the purpose of energy storage, but also realizes the resource utilization of carbon dioxide.

[0003] The SOC includes three main parts: electrolyte, fuel electrode and oxygen electrode. The oxygen electrode often involves a complex four-electron (4e - ) transfer process, which is one of the main kinetic bottlenecks in high-temperature SOC. The oxygen electrode material needs a porous structure to facilitate the diffusion and release of air / oxygen, and also requires high catalytic activity, ionic and electronic conductivity, and phase structure stability at high temperature, and does not react with the electrolyte material and matches the thermal expansion coefficient to prevent the formation of high resistance phases and the generation of thermal stress to cause the oxygen electrode to crack and delaminate from the electrolyte material. In order to improve the ionic conductivity of the oxygen electrode material, an electronic conductor material or a mixed oxygen ion and electronic conductor material is usually compounded with a high ionic conductivity electrolyte material to prepare a composite electrode material. At the same time, the above method can realize the extension of the electrolyte material in the oxygen electrode, extending the length of the three-phase boundary (TPB) and effectively increasing the reaction active sites.

[0004] The current method for preparing the composite electrode material mainly includes mechanical ball milling and hydrothermal method, wherein the mechanical ball milling method has the problems of component segregation and poor interface contact; the hydrothermal method has high pressure and long time consumption, and is not suitable for large-scale production. SUMMARY

[0005] The application aims to provide a two-phase composite powder and a method and application for preparing the two-phase composite powder based on a sol-gel method and spray drying.

[0006] To achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0007] The application provides a method for preparing a two-phase composite powder based on a sol-gel method and spray drying, comprising the following steps.

[0008] Spray drying the sol precursor aqueous solution to obtain a precursor powder;

[0009] Calcining the precursor powder to obtain the two-phase composite powder;

[0010] The sol precursor aqueous solution comprises a first-phase metal source and a second-phase metal source; the metal oxide formed by the first-phase metal source constitutes a mixed ionic-electronic conductor phase, and the metal oxide formed by the second-phase metal source constitutes an ionic conductor phase;

[0011] The first-phase metal source comprises a nitrate and / or an acetate, and the metal elements in the first-phase metal source comprise a first rare earth metal and a first transition metal; the second-phase metal source comprises a nitrate and / or an acetate, and the metal elements in the second-phase metal source comprise a second rare earth metal and / or a second transition metal;

[0012] When the first-phase metal source and the second-phase metal source in the sol precursor aqueous solution are both only nitrates, the sol precursor aqueous solution further comprises an alpha-hydroxy carboxylic acid.

[0013] Preferably, the first rare earth metal comprises one or more of La, Pr, Nd, Sm and Gd; and the first transition metal comprises one or more of Fe, Co, Ni, Mn and Cu.

[0014] The second rare earth metal comprises one or more of Pr, Nd, Ce, Sm, Gd and Y; and the second transition metal comprises one or more of Fe, Co, Ni, Mn and Cu.

[0015] Preferably, the metal elements in the first-phase metal source further comprise an alkaline earth metal, and the alkaline earth metal comprises one or more of Sr, Ca and Ba.

[0016] Preferably, the alpha-hydroxyl carboxylic acid comprises citric acid and / or tartaric acid; when the alpha-hydroxyl carboxylic acid is included in the sol precursor aqueous solution, the molar ratio of the alpha-hydroxyl carboxylic acid to the metal elements in the sol precursor aqueous solution is ≤ 2, and the molar amount of the metal elements is the total molar amount of the metal elements in the sol precursor aqueous solution.

[0017] Preferably, the sol precursor aqueous solution further includes a polyhydric alcohol, and the polyhydric alcohol includes one or more of ethylene glycol, diethylene glycol and triethylene glycol; when the polyhydric alcohol is included in the sol precursor aqueous solution, the molar ratio of the polyhydric alcohol to the metal elements in the sol precursor aqueous solution is ≤ 8, and the molar amount of the metal elements is the total molar amount of the metal elements in the sol precursor aqueous solution.

[0018] Preferably, the total concentration of the metal elements in the sol precursor aqueous solution is 0.05-0.30 mol / L.

[0019] Preferably, the spray drying equipment used for the spray drying includes a blower, a heating system, a breaking gas system and a peristaltic pump; and the conditions of the spray drying include that the power of the blower is 60-80%, the inlet air temperature is 180-240℃, the breaking gas flow is 40-60 sccm, and the power of the peristaltic pump is 20-40%.

[0020] Preferably, the calcination temperature is 800-1200℃, and the holding time is 1-5 h.

[0021] The application provides a two-phase composite material powder prepared by the method, which includes a mixed ion-electron conductor phase and an ion conductor phase, the mixed ion-electron conductor phase is composed of a metal oxide formed by a first-phase metal source, the ion conductor phase is composed of a metal oxide formed by a second-phase metal source, and the molar ratio of the mixed ion-electron conductor phase to the ion conductor phase is 9:1-1:9.

[0022] The application provides an application of the two-phase composite material powder in a solid oxide fuel cell or a solid oxide electrolytic cell.

[0023] The application provides a method for preparing two-phase composite material powder based on sol-gel method and spray drying, comprising the following steps: spray drying a sol precursor aqueous solution to obtain a precursor powder; calcining the precursor powder to obtain the two-phase composite material powder; the sol precursor aqueous solution comprises a first-phase metal source and a second-phase metal source; a metal oxide formed by the first-phase metal source constitutes a mixed ionic-electronic conductor phase, and a metal oxide formed by the second-phase metal source constitutes an ionic conductor phase; the first-phase metal source comprises nitrate and / or acetate, and metal elements in the first-phase metal source comprise a first rare earth metal and a first transition metal; the second-phase metal source comprises nitrate and / or acetate, and metal elements in the second-phase metal source comprise a second rare earth metal and / or a second transition metal; when the first-phase metal source and the second-phase metal source in the sol precursor aqueous solution are both only nitrate, the sol precursor aqueous solution further comprises an alpha-hydroxycarboxylic acid. The application prepares two-phase composite material powder based on sol-gel method and spray drying, uses soluble metal salt as raw material, and selectively introduces alpha-hydroxycarboxylic acid as a complexing agent according to the type of soluble metal salt, so that molecular-level uniform mixing of the precursor can be realized, and then two-phase composite material powder is obtained by combining spray drying technology for rapid forming. Specifically, the application can form a sol precursor aqueous solution of molecular-level uniformity based on sol-gel method, in which a stable complex is formed by a complexing agent (acetate or alpha-hydroxycarboxylic acid) and metal ions (such as La 3+ , Sr 2+ , Co 2+ , Fe 3+ , Ce 4+ , Gd 3+ , etc.), which can effectively avoid local concentration difference, reduce component segregation during spray drying and has good particle dispersity, can realize atomic-level dispersion, and avoid the problem that hard agglomeration between particles is caused by rapid solvent volatilization when directly using the spray drying method, which affects sintering activity. The method of the application overcomes the problem of component segregation that is difficult to avoid in the traditional mechanical ball milling method, and finally the two-phase composite material powder obtained has uniform components, and the preparation steps are simple, the production cycle is short, high-pressure conditions are not required, batch stability is good, and the method is suitable for large-scale industrial production.

[0024] Further, the application can introduce polyhydric alcohol as a solvent regulator, which has weak acidity and weak reducing property in the system, which is beneficial to further inhibit metal element segregation and promote uniform distribution of components.

[0025] Further, by controlling the concentration of the sol precursor aqueous solution and the conditions of spray drying, the sol precursor aqueous solution can be directly atomized into uniform particles, and gelation and rapid dehydration drying can be simultaneously completed. Specifically, the sol precursor aqueous solution is first atomized into microdroplets during spray drying, and the microdroplets can quickly fix the precursor structure during millisecond drying (180-240 DEG C), effectively inhibit the migration of metal ions, and avoid phase separation and particle agglomeration. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 X-ray diffraction pattern of the two-phase composite powder prepared in Example 1;

[0027] Figure 2 SEM image of the cross-sectional structure of the fuel cell prepared using the two-phase composite powder in Example 1;

[0028] Figure 3 Performance test result graph of the fuel cell prepared using the two-phase composite powder in Example 1;

[0029] Figure 4 X-ray diffraction pattern of the two-phase composite powder prepared in Example 2;

[0030] Figure 5 X-ray diffraction pattern of the two-phase composite powder prepared in Example 5;

[0031] Figure 6 X-ray diffraction pattern of the two-phase composite powder prepared in Comparative Example 1;

[0032] Figure 7 Performance test result graph of the fuel cell prepared using the two-phase composite powder in Comparative Example 1 and the two-phase composite powder in Example 5. DETAILED DESCRIPTION

[0033] The present application provides a method for preparing a two-phase composite powder based on a sol-gel method and spray drying, comprising the following steps:

[0034] Spray drying the sol precursor aqueous solution to obtain a precursor powder;

[0035] Calcining the precursor powder to obtain the two-phase composite powder;

[0036] The sol precursor aqueous solution comprises a first-phase metal source and a second-phase metal source; the metal oxide formed by the first-phase metal source constitutes a mixed ionic-electronic conductor phase, and the metal oxide formed by the second-phase metal source constitutes an ionic conductor phase;

[0037] The first phase metal source comprises nitrate and / or acetate, and the metal elements in the first phase metal source comprise a first rare earth metal and a first transition metal; the second phase metal source comprises nitrate and / or acetate, and the metal elements in the second phase metal source comprise a second rare earth metal and / or a second transition metal.

[0038] When the first phase metal source and the second phase metal source in the aqueous sol precursor solution are both nitrate, the aqueous sol precursor solution further comprises an α-hydroxycarboxylic acid.

[0039] In the present application, if no special description is given, all the raw materials used are commercially available or prepared by methods known to those skilled in the art.

[0040] The present application first provides an aqueous sol precursor solution. The aqueous sol precursor solution comprises a first phase metal source and a second phase metal source. The metal oxide formed by the first phase metal source constitutes a mixed ionic-electronic conductor phase, and the metal oxide formed by the second phase metal source constitutes an ionic conductor phase. The types of the two are described in detail below.

[0041] The first phase metal source comprises nitrate and / or acetate, and can be nitrate or acetate. The metal elements in the first phase metal source comprise a first rare earth metal and a first transition metal. As an embodiment of the present application, the first rare earth metal can comprise one or more of La, Pr, Nd, Sm and Gd, and can be La, Pr, Nd, Sm or Gd. The first transition metal can comprise one or more of Fe, Co, Ni, Mn and Cu, and can be Fe, Co, Ni, Mn or Cu, or Fe and Co. As an embodiment of the present application, the metal elements in the first phase metal source can further comprise an alkaline earth metal, which can comprise one or more of Sr, Ca and Ba, and can be Sr, Ca or Ba.

[0042] The second phase metal source comprises nitrate and / or acetate, and can be nitrate or acetate. The metal elements in the second phase metal source comprise a second rare earth metal and / or a second transition metal. As an embodiment of the present application, the second rare earth metal can comprise one or more of Pr, Nd, Ce, Sm, Gd and Y, and can be Pr, Nd, Ce, Sm, Gd or Y, or Ce and Gd, or Ce and Y. The second transition metal can comprise one or more of Fe, Co, Ni, Mn and Cu, and can be Fe, Co, Ni, Mn or Cu, or Co and Mn.

[0043] As an embodiment of the present application, the total concentration of metal elements in the sol precursor aqueous solution can be 0.05-0.30 mol / L, and specifically can be 0.05 mol / L, 0.07 mol / L, 0.10 mol / L, 0.13 mol / L, 0.15 mol / L, 0.17 mol / L, 0.20 mol / L, 0.23 mol / L, 0.25 mol / L, 0.27 mol / L or 0.30 mol / L. Controlling the total concentration of metal elements in the present embodiment within the above range can control the hydrolysis kinetics of the first-phase metal source and the second-phase metal source, and is conducive to improving the uniformity of the morphology and structure of the final two-phase composite powder.

[0044] In the present application, when the first-phase metal source and the second-phase metal source in the sol precursor aqueous solution are both nitrate, the sol precursor aqueous solution further includes an α-hydroxycarboxylic acid. As an embodiment of the present application, when the first-phase metal source and the second-phase metal source in the sol precursor aqueous solution are both acetate, or are used in combination with acetate and nitrate, the sol precursor aqueous solution can or can not include an α-hydroxycarboxylic acid. The use of acetate in the present application can play the role of a complexing agent, and can achieve self-driven complexation without additional addition of an α-hydroxycarboxylic acid, which is conducive to improving the accuracy and uniformity of each component of the final two-phase composite powder.

[0045] As an embodiment of the present application, the α-hydroxycarboxylic acid can include citric acid and / or tartaric acid, and specifically can be citric acid or tartaric acid. As an embodiment of the present application, when the sol precursor aqueous solution includes an α-hydroxycarboxylic acid, the molar ratio of the α-hydroxycarboxylic acid to the metal elements in the sol precursor aqueous solution can be ≤2, and further can be 0.01-2, and specifically can be 0.01, 0.05, 0.1, 0.5, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2. The molar amount of the metal elements is the total molar amount of the metal elements in the sol precursor aqueous solution. The α-hydroxycarboxylic acid in the present application can act as a complexing agent, and the -COOH and -OH functional groups of the α-hydroxycarboxylic acid can chelate with metal ions to form an organic-metal complex network, which can achieve three-dimensional network gelation control and is conducive to increasing the pore structure of the material after spray drying and calcination.

[0046] As an embodiment of the present application, the polyhydric alcohol in the sol precursor aqueous solution can include one or more of ethylene glycol, diethylene glycol and triethylene glycol, and specifically can be ethylene glycol; when the sol precursor aqueous solution includes the polyhydric alcohol, the molar ratio of the polyhydric alcohol to the metal elements in the sol precursor aqueous solution can be ≤8, further can be 0.1-8, and specifically can be 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5 or 8; the molar amount of the metal elements is the total molar amount of the metal elements in the sol precursor aqueous solution. The polyhydric alcohol in the present application can serve as a solvent regulator, and has weak acidity and weak reducing property in the system, which is beneficial to reducing component segregation, such as selectively reconstructing the Sr-rich layer and inhibiting Sr segregation. For example, the surface Sr-rich layer of the perovskite LSCF is derived from the migration of A-site Sr ions, and the Co-O bond in the Sr-rich layer is less stable than that in the bulk phase, which further promotes the uniform distribution of Sr. 3d -O 2p The negative charge transfer between the orbits can give higher reactivity, while the bulk phase structure remains stable. Under weak acidic conditions, the Sr-O bond is easy to break (the La-O bond is stable), and the weak reducing environment makes the Co-O bond in the Sr-rich region less stable than that in the bulk phase, which further promotes the uniform distribution of Sr.

[0047] As an embodiment of the present application, the number of the metal elements in the sol precursor aqueous solution can be 4-6, and specifically can be 4, 5 or 6; the ratio of the metal elements in the sol precursor aqueous solution is based on the composition of the target two-phase composite powder. As an embodiment of the present application, the sol precursor aqueous solution can use any of the following formulations:

[0048] Formulation one: nitrate (the first-phase metal source and the second-phase metal source are both nitrate), α-hydroxycarboxylic acid, polyhydric alcohol and water; the nitrate can be lanthanum nitrate, strontium nitrate, cobalt nitrate, cerium nitrate and gadolinium nitrate, can be lanthanum nitrate, strontium nitrate, cobalt nitrate, cerium nitrate, iron nitrate, cerium nitrate and gadolinium nitrate, or can be lanthanum nitrate, nickel nitrate, cobalt nitrate and manganese nitrate.

[0049] Formulation two: acetate (the first-phase metal source and the second-phase metal source are both acetate), α-hydroxycarboxylic acid, polyhydric alcohol and water; the acetate can be gadolinium acetate, barium acetate, cobalt acetate, cerium acetate and yttrium acetate.

[0050] Formulation three: acetate (the first-phase metal source and the second-phase metal source are both acetate) and water; the acetate can be lanthanum acetate, strontium acetate, cobalt acetate, cerium acetate and gadolinium acetate.

[0051] As an embodiment of the present application, the water in the sol precursor aqueous solution can be deionized water.

[0052] As an embodiment of the present application, the preparation method of the sol precursor aqueous solution can comprise the following steps: mixing and stirring the components in the sol precursor aqueous solution to obtain the sol precursor aqueous solution; the stirring temperature can be 20-30°C, specifically room temperature (25°C); the stirring speed can be 200-400 rpm, specifically 300 rpm; and the stirring time can be 25-35 min, specifically 30 min. The stirring under the above conditions can ensure that the components are fully mixed, and the obtained sol precursor aqueous solution has high homogeneity.

[0053] After obtaining the sol precursor aqueous solution, the sol precursor aqueous solution is subjected to spray drying to obtain a precursor powder. As an embodiment of the present application, the spray drying equipment used for the spray drying comprises an air blower, a heating system, a breaking gas system and a peristaltic pump; and the spray drying conditions comprise: the air blower power can be 60-80%, specifically 60%, 65%, 70%, 75% or 80%; the inlet air temperature can be 180-240°C, specifically 180°C, 190°C, 200°C, 210°C, 220°C, 230°C or 240°C; the breaking gas flow rate can be 40-60 sccm, specifically 40 sccm, 45 sccm, 50 sccm, 55 sccm or 60 sccm; and the peristaltic pump power can be 20-40%, specifically 20%, 25%, 30%, 35% or 40%. In the embodiment of the present application, specifically, the homogeneous sol precursor aqueous solution can be transferred to the feed container of the spray drying equipment, the air blower is first turned on and the power is adjusted to 60-80%, then the heating system is started, the inlet air temperature is set to 180-240°C, after a stable hot air flow is formed in the interior of the spray drying equipment and the temperature reaches the set value, the breaking gas system (the flow rate is set to 40-60 sccm) and the peristaltic pump (the power is set to 20-50%) are sequentially turned on, so that the homogeneous sol precursor aqueous solution is atomized into the drying chamber at a constant rate, in the spray drying process, the atomized droplets fully contact with the high-temperature gas flow, instantaneous drying is realized, the processes of solvent evaporation and powder formation are simultaneously completed, and finally the dried precursor powder is collected in the collection bottle. The particle size of the precursor powder of the present application can be 0.1-2 μm.

[0054] In the spray drying process, the aqueous solution of the sol precursor is atomized to form microdroplets (1-10 μm in size), the microdroplets are instantaneously (in millisecond level) evaporated in a high-temperature gas flow (180-240 ℃) and rapidly gelled, directly converting the sol microdroplets into xerogel microspheres, skipping the traditional gel bulk drying step, and preventing cracking and composition gradient. Therefore, the spray drying of the present application can accelerate mass and heat transfer, inhibit component segregation, uniformly fix each metal ion during solvent evaporation, and form a core-shell or interpenetrating network structure through surface tension-driven directional arrangement of each component. The obtained two-phase composite powder is more dry and compact, facilitating collection. The solid oxide fuel cell and the solid oxide electrolytic cell prepared using the two-phase composite powder of the present application have better performance.

[0055] After obtaining the precursor powder, the precursor powder is calcined to obtain the two-phase composite powder. As an embodiment of the present application, the calcination temperature can be 800-1200 ℃, specifically 800 ℃, 900 ℃, 1000 ℃, 1100 ℃ or 1200 ℃; the holding time can be 1-5 h, specifically 1 h, 2 h, 3 h, 4 h or 5 h. As an embodiment of the present application, the heating rate for heating to the calcination temperature can be 1-10 ℃ / min, specifically 1 ℃ / min, 5 ℃ / min, 8 ℃ / min or 10 ℃ / min; the calcination is followed by cooling, and the cooling rate can be 1-10 ℃ / min, specifically 1 ℃ / min, 5 ℃ / min, 8 ℃ / min or 10 ℃ / min. The calcination of the present application can be performed in an air atmosphere. The calcination under the above conditions in the present application can control the crystal phase transformation and grain growth, which is beneficial to improve the structural integrity of the finally obtained two-phase composite powder.

[0056] The "one-pot" single batch synthesis process of the present application can realize uniform compounding of five or more metal elements (such as La, Sr, Co, Fe, Ce, Gd, etc.) at the molecular scale; through the synergistic regulation of the sol-gel method and the spray drying technology, the precise compounding of multi-metal oxides is realized innovatively. Specifically, first, due to the significant difference in the hydrolysis rates of different metal ions (such as the hydrolysis rate of Ce 4+ is higher than that of Sr 2+The phase separation of the two-phase composite material is prone to occur in the process of phase formation (by 1-2 orders of magnitude), and the phase separation of more than 5 elements is prone to occur in the process of phase formation. The present application is based on the preparation of a precursor sol solution by a sol-gel method, and the uniform kinetic balance can be realized by using ion-ligand complexation chemistry, so that the components are uniformly phase-formed at the molecular level. Secondly, the rapid drying can be realized by spray drying, which promotes the directional arrangement of the sol components (such as metal ion-organic complex), forms open pores, and successfully prepares the precursor powder, which is beneficial to the lattice matching in the subsequent calcination process; thirdly, the decomposition of the organic components produces gas (CO2, H2O) by calcination, which is helpful to enhance the porous structure, and finally the two-phase composite material powder is prepared, and the solid oxide fuel cell and the solid oxide electrolytic cell prepared by using the two-phase composite material powder have better performance.

[0057] The method of the present application is suitable for the preparation of various two-phase composite material powders, such as perovskite oxide / rare earth doped ceria two-phase composite material powder, and perovskite oxide / spinel two-phase composite material powder. Specifically, the method of the present application is suitable for the preparation of ABO3 type perovskite phase, A2BO4 type RP phase, AA'BB'O6 type double perovskite phase, and rare earth doped ceria (Re x Ce 1-x O 2-δ , Re=Gd, Sm or Y), and transition metal salt constructed spinel phase.

[0058] The two-phase composite material powder prepared by the method of the above technical solution provided by the present application comprises a mixed ionic-electronic conductor phase and an ionic conductor phase, the mixed ionic-electronic conductor phase is composed of a metal oxide formed by a first phase metal source, the ionic conductor phase is composed of a metal oxide formed by a second phase metal source, and the molar ratio of the mixed ionic-electronic conductor phase to the ionic conductor phase is 9:1-1:9, which can be 8:2, 7:3, 6:4, 5:5, 4:6 or 3:7. As an embodiment of the present application, the mixed ionic-electronic conductor phase can comprise ABO3 type perovskite phase, A2BO4 type RP phase or AA'BB'O6 type double perovskite phase; and the ionic conductor phase can comprise rare earth doped ceria phase or transition metal salt.

[0059] The present application provides the application of the two-phase composite material powder in a solid oxide fuel cell or a solid oxide electrolytic cell. As an embodiment of the present application, the two-phase composite material powder can be used as an electrode material of a solid oxide fuel cell or a solid oxide electrolytic cell, and specifically can be used as an oxygen electrode material. The application method of the two-phase composite material powder is not specially limited in the present application, and the method well known to those skilled in the art can be used.

[0060] The technical solutions in the present application will be clearly and completely described below in combination with the embodiments in the present application. Apparently, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative effort belong to the scope of the present application.

[0061] The raw materials used in the following experiments are all commercially available, wherein the purity of La(NO3)3·6H2O is ≥99.9%, the purity of Sr(NO3)2 is ≥99.5%, the purity of Co(NO3)2·6H2O is ≥99.9%, the purity of Ce(NO3)3·6H2O is ≥99.9%, the purity of Gd(NO3)3·6H2O is ≥99.9%, the purity of Fe(NO3)3·9H2O is ≥99.9%, the purity of Ni(NO3)2·6H2O is ≥99.9%, the purity of Mn(NO3)2 is ≥99.9%, the purity of Gd(CH3COO)3·4H2O is ≥99.9%, the purity of Ba(CH3COO)2 is ≥99.5%, the purity of Co(CH3COO)2·4H2O is ≥99.9%, the purity of Ce(CH3COO)3·H2O is ≥99.9%, the purity of Y(CH3COO)3·4H2O is ≥99.9%, the purity of La(CH3COO)3 is ≥99.9%, the purity of Sr(CH3COO)2 is ≥99.9%; the purity of citric acid (C6H8O7) is ≥99.5%, and the purity of ethylene glycol (C2H6O2) is ≥99.0%.

[0062] Example 1

[0063] According to La 0.6 Sr 0.4 CoO 3-δ -Ce 0.8 Gd 0.2 O 2-δ The raw materials were accurately weighed according to the stoichiometric ratio: the perovskite phase precursor included 16.7337 g of La(NO3)3·6H2O, 5.4526 g of Sr(NO3)2 and 18.7461 g of Co(NO3)2·6H2O; the rare earth doped ceria phase precursor included 12.3608 g of Ce(NO3)3·6H2O and 3.2129 g of Gd(NO3)3·6H2O; 63.1723 g of citric acid was used as a complexing agent, and 81.6386 g of ethylene glycol was used as a solvent regulator; the above raw materials were placed in a 1 L beaker, deionized water was added to make up to 1 L, a polytetrafluoroethylene coated magnetic rotor was added to the obtained mixed solution, and stirring was performed at a speed of 300 rpm at room temperature (25°C) for 30 min to form a clear and transparent homogeneous sol precursor aqueous solution (i.e. the solute was completely dissolved and a uniform and stable precursor solution was formed);

[0064] The homogeneous sol-gel precursor aqueous solution is transferred to the feed container of the spray drying equipment, first turn on the air blower and adjust the power to 80%, then start the heating system, set the inlet air temperature to 240℃, after the internal heat air flow of the spray drying equipment is stable and the temperature reaches the set value, open the crushing gas system (flow rate set to 50sccm) and peristaltic pump (power set to 20%) in turn, so that the homogeneous sol-gel precursor aqueous solution is atomized into the drying chamber at a constant rate, in the process of spray drying, the atomized droplets are in full contact with the high-temperature gas flow, realizing instantaneous drying, and at the same time completing the process of solvent evaporation and powder formation, finally the dried precursor powder (particle size 0.1-10μm) is collected in the collection bottle;

[0065] The precursor powder is placed in a high-purity alumina crucible and put into a high-temperature calcining furnace, and heated from room temperature to 1000℃ at a rate of 10℃ / min in an air atmosphere, and kept for 3h to realize full crystallization; then cooled to room temperature at the same rate to obtain a two-phase composite material powder (denoted as sample 1B); the two-phase composite material powder comprises a mixed ionic-electronic conductor phase and an ionic conductor phase, the mixed ionic-electronic conductor phase is a perovskite phase, the ionic conductor phase is a rare earth doped cerium oxide phase, and the molar ratio of the mixed ionic-electronic conductor phase to the ionic conductor phase is 7:3.

[0066] The two-phase composite material powder is prepared according to the above method, except that the molar ratio of the mixed ionic-electronic conductor phase to the ionic conductor phase is 8:2, 6:4, 5:5, 4:6, 3:7, respectively, and the finally obtained two-phase composite material powders are denoted as samples 1A, 1C, 1D, 1E, 1F, respectively.

[0067] Figure 1 The X-ray diffraction (XRD) pattern of the two-phase composite material powder prepared in Example 1 is shown in the figure, and 8:2, 7:3, 6:4, 5:5, 4:6, 3:7 correspond to samples 1A, 1B, 1C, 1D, 1E, 1F, respectively. The results show that the two-phase composite material powder is a complex powder with a single perovskite phase (i.e. lanthanum-strontium-cobalt oxide, abbreviated as LSC) and a fluorite phase (CGO), i.e. LSC-CGO complex powder.

[0068] Figure 2 The SEM image of the cross-sectional structure of the fuel cell prepared using the two-phase composite material powder (specifically sample 1B) in Example 1 is shown in the figure, wherein the fuel cell is prepared by screen printing method, and can be prepared according to the prior art (Example 1 of Chinese patent with publication number CN119542434A). It can be seen from the figure that the two-phase composite material powder is closely bonded with the electrolyte. Figure 2 It can be seen that the two-phase composite material powder is closely bonded with the electrolyte.

[0069] Figure 3The graph shows the performance test results of the fuel cell prepared using the two-phase composite material powder (specifically sample 1B) from Example 1. The test was conducted in the fuel cell's operating mode (FC mode), and the test conditions can be referenced from existing technology (Chinese Patent Publication No. CN212134904U). Figure 3 It can be seen that the maximum power density of the fuel cell at 850℃ is 0.5W / cm³. 2 .

[0070] Example 2

[0071] First, according to La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ -Ce 0.8 Gd 0.2 O 2-δ The raw materials were precisely weighed according to stoichiometry: the perovskite phase precursor included 16.7337g La(NO3)3·6H2O, 5.4526g Sr(NO3)2, 3.7638g Co(NO3)2·6H2O, and 20.8980g Fe(NO3)3·9H2O; the rare earth-doped cerium oxide phase precursor included 12.3608g Ce(NO3)3·6H2O and 3.2129g... Gd(NO3)3·6H2O was used; 63.1723g of citric acid was used as a complexing agent and 81.6386g of ethylene glycol was used as a solvent regulator; then, a two-phase composite material powder (denoted as sample 2B) was prepared according to the method of Example 1. The two-phase composite material powder includes a mixed ion-electron conductor phase and an ion conductor phase. The mixed ion-electron conductor phase is a perovskite phase and the ion conductor phase is a rare earth-doped cerium oxide phase. The molar ratio of the mixed ion-electron conductor phase to the ion conductor phase is 7:3.

[0072] Two-phase composite material powders were prepared according to the above method, except that the molar ratios of the mixed ion-electron conductor phase and the ion conductor phase were 8:2, 6:4, 5:5, 4:6, and 3:7, respectively. The resulting two-phase composite material powders were designated as samples 2A, 2C, 2D, 2E, and 2F, respectively.

[0073] Figure 4 The X-ray diffraction pattern of the two-phase composite powder prepared in Example 2 is shown. In the figure, 8:2, 7:3, 6:4, 5:5, 4:6, and 3:7 correspond to samples 2A, 2B, 2C, 2D, 2E, and 2F, respectively. The results show that the two-phase composite powder is a multiphase powder with a single perovskite phase (i.e., lanthanum strontium cobalt iron oxide, abbreviated as LSCF) and a fluorite phase (CGO), namely, LSCF-CGO multiphase powder.

[0074] Example 3

[0075] First, according to La2NiO 4+δ The raw materials were accurately weighed according to the stoichiometric ratio: the RP phase precursor included 21.5632 g of La(N03)3-6H20 and 7.2705 g of Ni(N03)2-6H20 (purity > 99.9%); the spinel phase precursor included 5.8253 g of Co(N03)2-6H20 and 7.1660 g of Mn(N03)2; 51.4271 g of citric acid was used as a complexing agent, and 66.3624 g of ethylene glycol was used as a solvent regulator; then the two-phase composite material powder was prepared according to the method of Example 1, denoted as sample 3A; the two-phase composite material powder included a mixed ionic-electronic conductor phase and an ionic conductor phase, the mixed ionic-electronic conductor phase was an RP phase, the ionic conductor phase was a spinel phase, and the molar ratio of the mixed ionic-electronic conductor phase to the ionic conductor phase was 10:8.

[0076] Example 4

[0077] First, according to GdBaCo2O 5+δ -Ce 0.85 Y 0.15 O 2-δ The raw materials were accurately weighed according to the stoichiometric ratio: the double perovskite phase precursor included 20.318 g of Gd(CH3COO)3-4H20, 12.771 g of Ba(CH3COO)2, and 24.908 g of Co(CH3COO)2-4H20; the rare earth doped cerium oxide phase precursor included 15.2763 g of Ce(CH3COO)3-H20 and 2.873 g of Y(CH3COO)3-4H20; 61.5382 g of citric acid was used as a complexing agent, and 79.3845 g of ethylene glycol was used as a solvent regulator; then the two-phase composite material powder was prepared according to the method of Example 1, denoted as sample 4A; the two-phase composite material powder included a mixed ionic-electronic conductor phase and an ionic conductor phase, the mixed ionic-electronic conductor phase was a double perovskite phase, the ionic conductor phase was a rare earth doped cerium oxide phase, and the molar ratio of the mixed ionic-electronic conductor phase to the ionic conductor phase was 5:5.

[0078] Example 5

[0079] First, according to La 0.6 Sr 0.4 CoO 3-δ -Ce 0.8 Gd 0.2 O 2-δThe raw materials were accurately weighed in stoichiometric ratio: the perovskite phase precursor included 5.8915 g La(CH3COO)3, 2.5565 g Sr(CH3COO)2 and 7.7388 g Co(CH3COO)2·4H2O, and the rare earth doped ceria phase precursor included 4.3385 g Ce(CH3COO)3·H2O and 1.3895 g Gd(CH3COO)3·4H2O; the raw materials were placed in a 1 L beaker, deionized water was added to make up to 1 L, a polytetrafluoroethylene coated magnetic rotor was added to the obtained mixed solution, and the solution was stirred at a speed of 300 rpm at room temperature (25 °C) for 30 min to form a clear and transparent homogeneous sol precursor aqueous solution (i.e. the solute was completely dissolved to form a uniform and stable precursor solution);

[0080] The homogeneous sol precursor aqueous solution was transferred to the feed container of the spray drying equipment, first the air blower was started and the power was adjusted to 80%, then the heating system was started, the inlet air temperature was set to 240 °C, after the internal part of the spray drying equipment formed a stable hot air flow and the temperature reached the set value, the crushing gas system (the flow rate was set to 40 sccm) and the peristaltic pump (the power was set to 20%) were sequentially started, so that the homogeneous sol precursor aqueous solution was atomized into the drying chamber at a constant rate, in the process of spray drying, the atomized droplets were in full contact with the high temperature gas flow, realizing instantaneous drying, and the process of solvent evaporation and powder formation was completed synchronously, and finally the dried precursor powder (particle size of 0.1-10 μm) was collected in the collection bottle;

[0081] The precursor powder was placed in a high-purity alumina crucible and put into a high-temperature calcination furnace, and was heated from room temperature to 1000 °C at a rate of 10 °C / min in an air atmosphere, and was kept at 1000 °C for 2 h to realize full crystallization; then the temperature was decreased to room temperature at the same rate, to obtain a two-phase composite material powder, which was recorded as sample 5A, and the molar ratio of the mixed ion-electronic conductor phase and the ion conductor phase was 7:3.

[0082] Figure 5 The X-ray diffraction pattern of the two-phase composite material powder prepared in Example 5 showed that the two-phase composite material powder was a complex phase powder having a single perovskite phase (LSC) and a fluorite phase (CGO), i.e. an LSC-CGO complex phase powder.

[0083] Comparative Example 1

[0084] First, La 0.6 Sr 0.4 CoO 3-δ -Ce 0.8 Gd 0.2 O 2-δThe raw materials were accurately weighed in stoichiometric ratio: the perovskite phase precursor included 8.3668 g of La(NO3)3·6H2O, 2.7263 g of Sr(NO3)2, and 9.3730 g of Co(NO3)2·6H2O, and the rare earth doped ceria phase precursor included 6.1804 g of Ce(NO3)3·6H2O and 1.6065 g of Gd(NO3)3·6H2O; the above raw materials were placed in a 1 L beaker, deionized water was added to make up to 500 mL, a polytetrafluoroethylene coated magnetic rotor was added to the obtained mixed solution, and stirring was performed at a speed of 300 rpm at room temperature (25℃) for 30 min to obtain a precursor solution; then, the two-phase composite material powder was prepared according to the method of Example 1, and was recorded as sample 1#.

[0085] Figure 6 The X-ray diffraction pattern of the two-phase composite material powder prepared for Comparative Example 1 showed that the two-phase composite material powder was a composite powder formed by a perovskite phase and a heterogeneous phase (RP phase) and a fluorite phase (Ce 0.8 Gd 0.2 O 2-δ ) corresponding to lanthanum strontium cobalt oxide (La 0.6 Sr 0.4 CoO 3-δ ).

[0086] Figure 7 The performance test results of the fuel cell prepared by using the two-phase composite material powder (i.e., sample 1#) in Comparative Example 1 and the two-phase composite material powder (i.e., sample 5A) in Example 5 are shown in the figure, wherein the fuel cell was prepared by a screen printing method, and can be prepared according to the prior art (Example 1 in Chinese Patent Publication No. CN119542434A), the fuel cell was tested in SOFC mode, and the test conditions can be referred to the prior art (Chinese Patent Publication No. CN212134904U). It can be seen that Figure 7 at 850℃, the maximum power density of the fuel cell corresponding to Example 5 was 0.46 W / cm 2 , and the maximum power density of the fuel cell corresponding to Comparative Example 1 was 0.35 W / cm 2 .

[0087] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a two-phase composite powder based on a sol-gel method and spray drying, comprising the following steps: spray drying a sol precursor aqueous solution to obtain a precursor powder; calcining the precursor powder to obtain the two-phase composite powder; wherein the sol precursor aqueous solution comprises a first-phase metal source and a second-phase metal source; a metal oxide formed by the first-phase metal source constitutes a mixed ionic-electronic conductor phase, and a metal oxide formed by the second-phase metal source constitutes an ionic conductor phase; the first-phase metal source comprises a nitrate and / or an acetate, and the metal elements in the first-phase metal source comprise a first rare earth metal and a first transition metal; the second-phase metal source comprises a nitrate and / or an acetate, and the metal elements in the second-phase metal source comprise a second rare earth metal and / or a second transition metal; when the first-phase metal source and the second-phase metal source in the sol precursor aqueous solution are both only nitrates, the sol precursor aqueous solution further comprises an α-hydroxycarboxylic acid. The first rare earth metal comprises one or more of La, Pr, Nd, Sm and Gd; and the first transition metal comprises one or more of Fe, Co, Ni, Mn and Cu. The second rare earth metal comprises one or more of Pr, Nd, Ce, Sm, Gd and Y; and the second transition metal comprises one or more of Fe, Co, Ni, Mn and Cu. The metal elements in the first-phase metal source further comprise an alkaline earth metal, and the alkaline earth metal comprises one or more of Sr, Ca and Ba. The α-hydroxycarboxylic acid comprises citric acid and / or tartaric acid; when the sol precursor aqueous solution comprises the α-hydroxycarboxylic acid, the molar ratio of the α-hydroxycarboxylic acid to the metal elements in the sol precursor aqueous solution is ≤2, and the molar amount of the metal elements is the total molar amount of the metal elements in the sol precursor aqueous solution. The sol precursor aqueous solution further comprises a polyhydric alcohol, and the polyhydric alcohol comprises one or more of ethylene glycol, diethylene glycol and triethylene glycol; when the sol precursor aqueous solution comprises the polyhydric alcohol, the molar ratio of the polyhydric alcohol to the metal elements in the sol precursor aqueous solution is ≤8, and the molar amount of the metal elements is the total molar amount of the metal elements in the sol precursor aqueous solution.

2. The method of claim 1, wherein, The total concentration of the metal elements in the sol precursor aqueous solution is 0.05-0.30 mol / L. The spray drying equipment used for the spray drying comprises a blower, a heating system, a cracking gas system and a peristaltic pump; and the conditions for the spray drying comprise: a blower power of 60-80%, an inlet air temperature of 180-240℃, a cracking gas flow rate of 40-60 sccm, and a peristaltic pump power of 20-40%.

3. The method of claim 2, wherein, The calcination temperature is 800-1200℃, and the holding time is 1-5 h.

4. The method of claim 1, wherein, ​ 5. The method according to any one of claims 1 to 4, characterized in that, ​ 6. The method of claim 5, wherein, ​ 7. The method according to any one of claims 1 to 4, characterized in that, ​ 8. The method according to any one of claims 1 to 4, characterized in that, ​ 9. A two-phase composite powder comprising a mixed ionic-electronic conductor phase and an ionic conductor phase, the mixed ionic-electronic conductor phase consisting of a metal oxide formed from a first metal source, the ionic conductor phase consisting of a metal oxide formed from a second metal source, the molar ratio of the mixed ionic-electronic conductor phase to the ionic conductor phase being from 9:1 to 1:9, produced by the method of any one of claims 1 to 8.

10. Use of the two-phase composite powder of claim 9 in a solid oxide fuel cell or a solid oxide electrolysis cell.

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