Solid oxide fuel cell and preparation method thereof

Abstract

The present invention discloses a solid oxide fuel cell and a preparation method thereof, wherein the solid oxide fuel cell comprises a solid electrolyte and an anode and a cathode located on both sides of the solid electrolyte, wherein the material of the anode is Sr 1.95 Fe 1.5‑ x Co x Mo 0.5 O 6‑δ , where 0.2≤x≤0.3. The present invention found that B-site Co doping is beneficial to the reduction of Sr 1.95 The FCMx material precipitates more metal CoFe, which is beneficial to improving the catalytic activity of the anode catalyst material. According to the test results of SOFC single cells, the power density of the highest x = 0.2 reached 1113mW·cm at 800℃ in hydrogen. ‑2 , reaching 228 mW·cm in ethane at 750 °C ‑2 The ethane conversion rate reached 34.2%, enabling the cogeneration of electricity and ethylene in a SOFC. Stability testing results showed that the electrochemical performance remained stable after 20 hours of operation in an ethane atmosphere, with no noticeable carbon deposition. The B-site Co doping level of x = 0.2 exhibits excellent electrochemical performance, including excellent resistance to carbon deposition, stability, and electrocatalytic activity, making it an excellent anode material for SOFCs.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cells, and in particular to a solid oxide fuel cell and a preparation method thereof. Background Art

[0002] Solid oxide fuel cells (SOFCs) have attracted widespread attention as a green energy technology due to their excellent fuel flexibility and conversion efficiency. When using ethane as fuel, traditional nickel-based metal ceramic anodes show excellent power output and high catalytic activity, but they are prone to carbon deposition, which greatly affects the stability of the battery. Therefore, in order to seek materials that can be used as SOFC anodes under hydrocarbon fuels, double perovskite materials have received widespread attention. Among them, double perovskite Sr2Fe 1.5 Mo 0.5 O 6-δ As a mixed ion-electron conductor, SFM has excellent oxygen ion and electron conductivity properties, and its larger three-phase boundary area is conducive to accelerating the electrochemical reaction of hydrocarbon fuels. However, the catalytic activity of SFM materials still needs to be further improved.

[0003] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a solid oxide fuel cell and a preparation method thereof, aiming to solve the problem of poor performance of the fuel cell due to low anode catalytic activity in the existing solid oxide fuel cell.

[0005] The technical solutions of the present invention are as follows:

[0006] A solid oxide fuel cell, comprising a solid electrolyte and an anode and a cathode located on both sides of the solid electrolyte, wherein the material of the anode is Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ , where 0.2≤x≤0.3.

[0007] The solid oxide fuel cell, wherein the material of the anode is Sr 1.95 Fe 1.3 Co 0.2 Mo 0.5 O 6-δ .

[0008] In the solid oxide fuel cell, the material of the solid electrolyte is LSGM.

[0009] The solid oxide fuel cell, wherein the cathode is a composite cathode, the material of the composite cathode is LSCF-SDC, wherein LSCF is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ,SDC is Sm 0.2 Ce 0.8 O 1.9 .

[0010] A method for preparing a solid oxide fuel cell, comprising the steps of:

[0011] Provide an anode, wherein the material of the anode is Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ , where 0.2≤x≤0.3;

[0012] The anode and cathode are printed on both sides of the solid electrolyte, and the anode and cathode are connected via a wire to manufacture the solid oxide fuel cell.

[0013] The method for preparing the solid oxide fuel cell, wherein the preparation of the anode comprises the steps of:

[0014] Co(NO3)2, Sr(NO3)2, Fe(NO3)3·9H2O and (NH4)6Mo7O were added according to the set stoichiometric ratio. 24 4H2O is dissolved in an aqueous solution containing nitric acid until it is completely dissolved to obtain a first mixed solution;

[0015] According to n (CA) :n (EDTA) :n (total ions) =1.5:1:1 ratio, sequentially adding citric acid and ethylenediaminetetraacetic acid to the first mixed solution, stirring evenly to obtain a second mixed solution;

[0016] adding aqueous ammonia to the second mixed solution, adjusting the pH value of the second mixed solution to 7-7.5 to completely dissolve the EDTA, thereby obtaining a third mixed solution;

[0017] The third mixed solution is stirred to form a metal complex solution, and then heated to dryness at 200° C. until combustion occurs, and the precursor is collected;

[0018] The precursor is moved into a crucible and calcined to obtain the SFM perovskite structure anode.

[0019] Beneficial effect: The anode powder Sr prepared by the combustion method of the present invention 1.95 FCMx (x = 0.1, x = 0.2, x = 0.3), a series of characterization tests were carried out on the anode materials, and finally applied to solid oxide fuel cells supported by oxygen ion conductor electrolytes, and the following conclusions were obtained: Co doping at the B site is beneficial to the reduction of Sr 1.95 The FCMx material precipitates more metal CoFe, which is beneficial to improving the catalytic activity of the anode catalyst material. According to the test results of SOFC single cells, the power density of the highest x = 0.2 reached 1113mW·cm at 800℃ in hydrogen. -2 , reaching 228 mW·cm in ethane at 750 °C -2 The ethane conversion rate reached 34.2%, enabling the cogeneration of electricity and ethylene in a SOFC. Stability testing results showed that the electrochemical performance remained stable after 20 hours of operation in an ethane atmosphere, with no noticeable carbon deposition. The B-site Co doping level of x = 0.2 exhibits excellent electrochemical performance, including excellent resistance to carbon deposition, stability, and electrocatalytic activity, making it an excellent anode material for SOFCs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 a in the equation is Sr 1.95 XRD patterns of FCMx (x = 0.1, 0.2, 0.3) samples after calcination at 1100 ° C for 4 h in air atmosphere, b is Sr 1.95 XRD patterns of FCMx (x = 0.1, 0.2, 0.3) samples at a scanning angle of 31-33° after calcination at 1100°C for 4 h in air atmosphere.

[0021] Figure 2 a in the equation is Sr 1.95 XRD patterns of FCMx (x = 0.1, 0.2, 0.3) samples after reduction at 800 ° C for 2 h in hydrogen atmosphere, b is Sr 1.95 XRD patterns of FCMx (x = 0.1, 0.2, 0.3) samples at a scanning angle of 44-48° after reduction at 800°C for 2 h in a hydrogen atmosphere.

[0022] Figure 3 a is the XRD pattern of SFM, LSGM and dry mixed composite powder SFM-LSGM (1:1, wt%); b is the XRD pattern of Sr 1.95 FCM 0.3 , LSGM and dry mixed composite powder Sr 1.95 XRD pattern of FCMx0.3-LSGM (1:1, wt%).

[0023] Figure 4 a in the equation is Sr 1.95FCM 0.2 SEM image of powder sample; b is Sr 1.95 FCM 0.2 Low magnification TEM image of the powder sample; c is the Sr after reduction 1.95 SEM micrograph of FCM0.2 powder sample; d is the Sr after reduction 1.95 FCM 0.2 High-magnification TEM image of the powder sample.

[0024] Figure 5 a in the equation is Sr 1.95 FCM 0.2 HAADF image of the powder sample; b is the EDS analysis graph of Fe, c is the EDS analysis graph of Co, d is the EDS analysis graph of Sr, e is the EDS analysis graph of Mo and f is the EDS analysis graph of O.

[0025] Figure 6 a is Sr after reduction 1.95 HAADF image of FCM0.2 powder sample, b is the EDS analysis diagram of Fe, c is the EDS analysis diagram of Co, d is the EDS analysis diagram of Sr, e is the EDS analysis diagram of Mo and f is the EDS analysis diagram of O.

[0026] Figure 7 Sr in 10% H2 / Ar at 100℃-850℃ 1.95 H2-TPR patterns of FCMx (x = 0.1, 0.2, 0.3).

[0027] Figure 8 a is Sr after reduction 1.95 Fitting analysis of the O1s XPS spectra of FCMx (x = 0.1, 0.2, 0.3) samples; b is the core-level spectrum of Co 2p and its fitting results analysis; c is the core-level spectrum of Fe 2p and its fitting results analysis; d is the core-level spectrum of Mo 3d and its fitting results analysis.

[0028] Figure 9 a is Sr in air atmosphere 1.95 FCM 0.2 The conductivity of the sample; b is the conductivity of Sr under H2 1.95 FCM 0.2 Conductivity of the sample.

[0029] Figure 10 (Sr 1.95 FCMx-LSGM-Sr 1.95 FCMx)(Sr 1.95 Impedance spectra of FCMx (x = 0.1, 0.2, 0.3) symmetric cells under H2 at open circuit voltages of 600-800 °C.

[0030] Figure 11 Figure a is the EIS curve of the symmetrical battery at 800°C; b is the DRT spectrum of the symmetrical battery in hydrogen at 800°C.

[0031] Figure 12 a in the equation is Sr 1.95 FCM 0.1 IV curve and corresponding IP curve of / LSGM / LSCF single cell measured under H2; c is Sr 1.95 FCM 0.2 IV curve and corresponding IP curve of / LSGM / LSCF single cell measured under H2; e is Sr 1.95 FCM 0.3 IV curve and corresponding IP curve of / LSGM / LSCF single cell measured under H2; b is Sr 1.95 FCM 0.1 IV curve and corresponding IP curve of / LSGM / LSCF single cell measured under C2H6; d is Sr 1.95 FCM 0.2 IV curve and corresponding IP curve of / LSGM / LSCF single cell measured under C2H6; f is Sr 1.95 FCM 0.3 IV curves and corresponding IP curves of a single LSGM / LSCF cell measured under C2H6.

[0032] Figure 13 In the figure, a is the ethane conversion rate of the symbiotic SOFC in the open circuit and working state at 650-750°C; b is the ethylene selectivity of the symbiotic SOFC in the open circuit and working state at 650-750°C.

[0033] Figure 14 a in the equation is Sr 1.95 FCM 0.2 Stability curve of a single cell with anode at 750℃ and 0.7V constant voltage, as well as (b) Raman spectrum of the anode after testing, (c) battery cross section, and (d) SEM morphology of the anode surface. DETAILED DESCRIPTION

[0034] The present invention provides a solid oxide fuel cell and a method for preparing the same. To make the objectives, technical solutions, and effects of the present invention more clear and explicit, the present invention is further described below in detail. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0035] In the early stage of the present invention, Sr 2-x Fe 1.4 Co 0.1 Mo0.5 O 6-δ The material was modified and it was found that Sr 1.95 Fe 1.4 Co 0.1 Mo 0.5 O 6-δ The catalyst material's electrical conductivity, electrocatalytic activity, and single-cell discharge performance were effectively improved, successfully demonstrating that A-site vacancy modification of double perovskite materials is a viable modification method. Compared with A-site vacancy, B-site doping is also a commonly used and effective method for improving material properties. By doping the B-site with varying amounts of catalytically active elements (Co, Fe, Ni, etc.), more numerous, more uniform, and more stably anchored nano-alloy particles are precipitated in a reducing atmosphere, providing active sites for fuel oxidation, thereby improving the material's catalytic activity and electrochemical performance.

[0036] Based on this, the present invention provides a solid oxide fuel cell, which includes a solid electrolyte and an anode and a cathode located on both sides of the solid electrolyte, wherein the material of the anode is Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ , where 0.2≤x≤0.3.

[0037] In this embodiment, the material of the solid electrolyte is LSGM, namely La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ The cathode is a composite cathode, the composite cathode material is LSCF-SDC, wherein LSCF is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ,SDC is Sm 0.2 Ce 0.8 O 1.9 .

[0038] In some embodiments, a method for preparing a solid oxide fuel cell is also provided, which comprises the steps of: providing an anode, wherein the material of the anode is Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ , wherein 0.2≤x≤0.3; printing the anode and cathode on both sides of the solid electrolyte, and connecting the anode and cathode through a wire to obtain the solid oxide fuel cell.

[0039] In this embodiment, the preparation of the anode includes the following steps: Co(NO3)2, Sr(NO3)2, Fe(NO3)3·9H2O and (NH4)6Mo7O are mixed according to a set stoichiometric ratio. 24 4H2O is dissolved in an aqueous solution containing nitric acid to completely dissolve it, thereby obtaining a first mixed solution; (CA) :n (EDTA) :n (total ions) =1.5:1:1, citric acid and ethylenediaminetetraacetic acid are sequentially added to the first mixed solution and stirred evenly to obtain a second mixed solution; ammonia water is added to the second mixed solution, and the pH value of the second mixed solution is adjusted to 7-7.5 to completely dissolve the ethylenediaminetetraacetic acid to obtain a third mixed solution; the third mixed solution is stirred to form a metal complex solution, and then heated to dryness at 200° C. until combustion occurs, and a precursor is collected; the precursor is transferred into a crucible and calcined to obtain the SFM perovskite structure anode.

[0040] The present invention will be further explained below by means of specific embodiments:

[0041] The present invention has excellent performance of Sr 1.95 Fe 1.4 Co 0.1 Mo 0.5 O 6-δ Further modification research was carried out and Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ (Sr 1.95 The FCMx (x = 0.1, 0.2, 0.3) series of anode materials were studied to explore the effects of different Co doping amounts at the B site while A is vacant. The focus was on the phase structure, morphology, element valence, electrochemical properties and catalytic activity of the materials under SOFC operating conditions.

[0042] Example 1

[0043] Preparation of anode material Sr by citrate combustion method 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ (Sr 1.95 FCMx, x = 0.1, 0.2, 0.3), its preparation process is as follows:

[0044] (1) Co(NO3)2(≥99.0%), Sr(NO3)2(≥99.5%), Fe(NO3)3·9H2O(≥99.99%) and (NH4)6Mo7O were added according to the set stoichiometric ratio. 24 4H2O (≥99.0%) is dissolved in an aqueous solution containing an appropriate amount of nitric acid until it is completely dissolved;

[0045] (2) According to n (CA) :n (EDTA) :n (total ions) =1.5:1:1 ratio, citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) were added to the above solution in sequence and stirred evenly;

[0046] (3) Add an appropriate amount of ammonia water to adjust the pH value of the solution to 7-7.5 to completely dissolve the EDTA;

[0047] (4) After stirring for about 2 h, the metal complex solution is fully formed, and then heated at 200 °C to evaporate to dryness until combustion occurs, and the precursor is collected;

[0048] (5) The precursor was transferred into a crucible and calcined at 1100° C. for 4 h to obtain the prepared anode material powder.

[0049] According to the above method, three different B-doped Sr 1.95 FCMx anode powder material Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ (x=0.1,0.2,0.3), respectively denoted as Sr 1.95 FCM 0.1 、Sr 1.95 FCM 0.2 、Sr 1.95 FCM 0.3 ; The anode powder material Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ (Sr 1.95 The XRD patterns of FCMx (x = 0.1, 0.2, 0.3) at room temperature are as follows Figure 1 As shown in a, the prepared samples all have cubic perovskite structure (PDF#34-0638) without any impurity phase, which indicates that the B-site doping of Co does not destroy the Sr 1.95 In the crystal structure of FCMx, the valence and radius of Co ions are similar to those of Fe ions (Fe 2+ :0.078nm;Fe3+ :0.065nm;Co 2+ :0.075nm;Co 3+ :0.061nm), which helps them to be successfully doped into the SFCoM lattice. In order to more clearly analyze the effect of B-site Co doping on the material structure, we magnified the test angle corresponding to the main peak around 32.4° in the XRD spectrum for mapping analysis. Figure 1 It can be clearly seen in b that with the increase of Co doping amount, the peak shifts slightly to a higher angle, indicating that the lattice decreases.

[0050] In order to study the structural stability of anode materials under reducing conditions and the precipitation of nano-alloy particles, Figure 2 a is the XRD pattern of the anode powder obtained by reduction in hydrogen atmosphere at 800℃ for 2h. It can be seen that Sr 1.95 FCMx maintains a stable perovskite structure. Figure 2 In the XRD magnified image of middle b, the peak of CoFe alloy precipitated at about 46.2° can be seen, which shows that under the reducing condition, Sr 1.95 CoFe alloy is in situ precipitated in the FCMx lattice without changing the material structure. CoFe alloy will be beneficial to improving the catalytic activity of the anode material.

[0051] In order to study the chemical compatibility between the electrolyte and the anode materials, Figure 3 LSGM electrolyte powder with Sr 1.95 The XRD pattern of FCMx anode powder material and SFM anode material mixed in a mass ratio of 1:1 and then calcined at 1100℃ in air atmosphere for 2h. It can be seen from the figure that both the electrode and electrolyte materials are prepared into pure phase structures, the XRD diffraction peaks of the two materials are obviously separated, and the diffraction peak of the mixture is just a simple superposition of the XRD patterns of the electrode and electrolyte materials. There is no obvious shift in the position of the diffraction peak, and no new diffraction peak is generated. Therefore, it shows that regardless of whether Co element is doped at the B position, the electrode material and the electrolyte material have good chemical compatibility, and there will be no chemical reaction even at the interface to produce insulating impurities, ensuring the good performance stability of the battery. Sr 1.95 FCMx electrodes can be applied in SOFCs supported by LSGM electrolyte.

[0052] Figure 4 a is Sr obtained by calcining at 1100℃ for 4h 1.95 The SEM image of the FCM0.2 anode material powder shows that the anode powder prepared in air has a smooth surface and is free of impurity particles. XRD analysis indicates that a CoFe alloy precipitates within the crystal structure of the anode material after reduction. The alloy particles precipitated in the reducing atmosphere can be more clearly seen in SEM and TEM images. Figure 4 Figure b is a SEM image of the anode material surface after reduction, which clearly shows that nanoparticles with an average particle size of 30 nm are uniformly precipitated on the substrate surface. Figure 4 In the TEM image of (c), it can be observed that the anode powder prepared in air has a clear and smooth grain outline, and the reduced particles grow in situ from the matrix. HR-TEM is used to further analyze the matrix and nanoparticles, such as Figure 4 As shown in Figure d, it can be seen that the matrix before reduction is an ordered lattice structure, and the measured interplanar spacing is 0.194nm, corresponding to SrFeO 3-x The interplanar spacing of the reduced alloy particles is 0.202 nm, corresponding to the (110) plane of the CoFe alloy phase (PDF#65-6829), while the interplanar spacing of the precipitated particles is 0.223 nm, corresponding to the (110) plane of the SrFeO phase (PDF#34-0638). 3-x The results of HR-TEM measurements are consistent with those of XRD. The CoFe alloy nanoparticles in situ precipitated from the substrate are not prone to agglomeration even in the reducing environment of high-temperature operation of SOFC, which can greatly improve the catalytic activity and stability of the anode material.

[0053] Figure 5 Sr is prepared in air 1.95 TEM-EDS image of FCM0.2 anode powder. The image shows uniform distribution of Sr, Fe, Co, Mo, and O elements in the sample, with no agglomeration. This indicates that B-site Co doping does not alter the phase structure, consistent with the XRD results, demonstrating that we have produced a pure anode powder.

[0054] Figure 6 is the reduced Sr 1.95 TEM-EDS image of FCM0.2 anode powder. The elemental distribution reveals that Fe and Co exist as nano-alloy particles on the surface of the matrix, while the distribution of all other elements is consistent with the double perovskite matrix structure. XRD and EDS further confirm that the nanoparticles observed in SEM and TEM are CoFe alloys precipitated after reduction. Elemental analysis also clearly demonstrates their distribution within the double perovskite matrix.

[0055] Example 2

[0056] Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ TPR test of materials

[0057] The oxygen reduction capacity of the anode material is evaluated by H2-TPR test. Figure 7 In the temperature range of 100-850℃, 10% H2 / Ar atmosphere, Sr 2-x TPR curves of all FCMx samples. The reduction process can be roughly divided into two stages: low temperature (300-400℃) and high temperature (500-600℃). The reduction peak at low temperature is attributed to the reduction of adsorbed oxygen species, while Co 3+ →Co 2 + and Fe 3+ →Fe 2+ The valence state changes, and the high temperature reduction peak belongs to Co 2+ →Co 0 and Fe 2+ →Fe 0 Metal precipitation and Mo 6+ →Mo 5+ The valence state change and lattice oxygen species reduction. The area of ​​the reduction peak increases with the increase of Co doping amount, the amount of hydrogen consumed increases, the oxygen reduction ability of the catalyst is enhanced, and more CoFe alloy is precipitated, which is beneficial to improve the activity of the catalyst. The position of the reduction peak moves toward the low temperature direction with the increase of Co doping amount, indicating that as the reduction temperature of Co doped materials decreases, they are more easily reduced. Mo generated in a reducing atmosphere 6+ / Mo 5+ and Fe 3+ / Fe 2+ Redox pairs can effectively reduce the polarization impedance of the battery and improve the electrochemical performance of the material.

[0058] Example 3

[0059] Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ XPS analysis of materials

[0060] XPS technology was used to analyze the Sr 1.95 Valence analysis of the elements in the FCMx material was performed to explore the relationship between its electrochemical performance and elemental valence. Co doping at the B site affects the valence distribution of Fe and Mo. To simulate the operating environment of the anode material in a SOFC, XPS analysis was performed on sample powders reduced at 800°C for 2 hours in a hydrogen atmosphere. Figure 8 a in the equation is Sr 1.95 The XPS spectrum fitting analysis of O1s of FCMx shows that the lattice oxygen O lat. (529.7eV), adsorbed oxygen O 2- / O -(531.4 eV) and hydroxycarbonate species CO3 2- / OH - The peak position and peak value of (532.9eV) are obtained by fitting the peaks of these three oxygen species (see Table 1). When the Co doping amount x = 0.2, the lattice oxygen O lat. The ratio of Co doping amount x = 0.3 is the smallest, and the lattice oxygen O lat. The proportion of lattice oxygen O is the largest. lat. The small proportion of Co doping can effectively reduce the oxygen vacancy formation energy, which is beneficial to the formation of lattice oxygen O lat. To adsorb oxygen O 2- / O - and hydroxycarbonate species CO3 2- / OH - This can improve the oxygen ion transmission capacity and greatly help improve the electrochemical performance.

[0061] Table 1 Sr 1.95 XPS analysis results of FCMx (x = 0.1, 0.2, 0.3) samples

[0062]

[0063] Figure 8 b is the core-level spectrum of Co 2p and its fitting results. 1.95 A small amount of metallic Co was precipitated in the FCMx reduced sample. 0 、Co 2+ 、Co 3+ There are three valence states, and the fitting peak is located at 794.3eV with high binding energy and Co 0 2p 1 / 2 , 800.9eV and Co 2+ 2p 1 / 2 , 797.2eV and Co 3+ 2p 1 / 2 Correspondingly, the fitting peak is located at 779.3eV with low binding energy and Co 0 2p 3 / 2 , 785.9eV and Co 2+ 2p 3 / 2 , 782.2eV and Co 3+ 2p 3 / 2 Correspondingly, with the increase of Co doping amount, the Co 3+ The ratio of gradually decreases, indicating that the vacancy is conducive to the reduction of Co element in the reducing atmosphere, so that the valence state exists in a lower form. 0The ratio of Co to precipitate increases with the increase of Co doping amount, and a larger amount of monovalent Co metal is precipitated, which is beneficial to improve the activity of the catalyst. XPS also further proves the presence of Co metal in the precipitated nanoparticles.

[0064] Figure 8 c is the core-level spectrum of Fe2p and its fitting results. 1.95 A small amount of metallic Fe was precipitated in the FCMx-reduced sample. 0 、Fe 2+ 、Fe 3+ The three valence states are mixed, and the fitting peak is located at 721.3eV with high binding energy and Fe 0 2p 1 / 2 , 723.0eV and Fe 2+ 2p 1 / 2 , 725.1eV and Fe 3+ 2p 1 / 2 Correspondingly, the fitting peak is located at 708.2eV with low binding energy and Fe 0 2p 3 / 2 , 709.9eV and Fe 2+ 2p 3 / 2 , 712.0eV and Fe 3+ 2p 3 / 2 The peak area is fitted and calculated, as shown in the table, with the increase of Co doping amount, Fe 0 The proportion of Fe metal decreases slightly, which may be due to the preferential precipitation of a large amount of Co metal in the reducing atmosphere, which leads to the relative restriction of Fe metal precipitation. However, the amount of the overall precipitated alloy increases with the increase of Co doping. 3+ / Fe 2+ The ratio of electron pairs first increases and then decreases, reaching a maximum value of 1.33 when x = 0.2.

[0065] Figure 8 The d in the figure is the core-level spectrum of Mo 3d and its fitting results. 1.95 In the FCMx reduced sample, Mo is converted to Mo 5+ and Mo 6+ There are two forms, and the fitting peak is located at 234.6eV with high binding energy and Mo 5+ 3d 3 / 2 , 235.0eV and Mo 6+ 3d 5 / 2 Correspondingly, the fitting peak is located at 231.5eV with low binding energy and Mo 5+ 3d 3 / 2 , 231.9eV and Mo 6+ 3d 5 / 2Corresponding. By fitting the peak area, as shown in the table, Mo 5+ / Mo 6+ The ratio increases first and then decreases, reaching a maximum value of 0.826 when x = 0.2, which is consistent with the Fe 3+ / Fe 2+ The electron pairs change in the same way with Co doping.

[0066] After reduction, Sr 1.95 In the XPS results of FCMx samples, Co 0 and Fe 0 The peak is consistent with the CoFe that appears in the XRD of the reduced sample, proving that CoFe alloy particles have been precipitated. 1.95 The Co / Fe / Mo in FCMx samples are all in mixed valence state, which means that Sr 1.95 There is a small polar transition conductivity mechanism in FCMx materials. Because the EDS shows that each element is evenly distributed in the sample, the above-mentioned quantitative element valence analysis by XPS is effective and reliable. It can be seen from Table 2 that Fe 3+ / Fe 2 + Electron pairs and Mo 5+ / Mo 6+ The electron pair ratio changes in the same pattern as the Co doping amount increases, first increasing and then decreasing. 1.95 The conductivity of FCMx samples is affected by Fe 2+ +Mo 6+ →Fe 3+ +Mo 5+ The influence of chemical equilibrium is very large. When x=0.2, it reaches the maximum value. The equilibrium moves to the right to the greatest extent, which is likely to increase Sr 1.95 The electronic conductivity of FCMx is of great help, thereby further improving the electrochemical performance of the anode material.

[0067] Table 2 Sr 1.95 XPS analysis results of FCMx (x = 0.1, 0.2, 0.3) samples

[0068]

[0069] Example 4

[0070] Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ Conductivity testing of materials

[0071] Figure 9 a in the sentence is Sr 1.95The conductivity curve of FCMx anode obtained in air atmosphere test. It can be seen that different Co-doped Sr 1.95 The conductivity of FCMx increases with increasing temperature, reaches a maximum value, and then gradually decreases. In the low temperature range, its conductive behavior can be explained by the small pole transition conductivity mechanism. 3+ →Fe 2+ +Mo 4+ With 2Co 3+ →Co 2+ +Co 4+ The disproportionation reaction increases with increasing temperature, thereby increasing the conductivity. In the high temperature range, the conductivity decreases with increasing temperature, which can be attributed to the high temperature lattice oxygen O lat. The maximum conductivity values ​​of Co doping from x = 0.1 to x = 0.3 are 31, 33 and 29 S·cm, respectively. -1 , the conductivity is highest when x = 0.2.

[0072] Figure 9 b in the middle is Sr 1.95 The conductivity curve of FCMx anode obtained in hydrogen atmosphere test. It can be seen that Sr 1.95 The conductivity of FCMx increases gradually with the increase of temperature, and the conductivity increases first and then decreases with the increase of Co doping amount. 3+ / Co 2+ The average valence of Fe 3+ / Fe 2+ Low, doping Co instead of Fe will introduce more oxygen vacancies in the lattice. Appropriate oxygen vacancies can improve the conductivity of the material. However, if there are too many oxygen vacancies in the lattice, it will limit the mobility of carriers, resulting in a decrease in conductivity. The conductivity is the highest when the Co doping amount x = 0.2, corresponding to its Fe 3+ / Fe 2+ and Mo 5+ / Mo 6+ The electron pair ratio is the highest, and the ion valence is balanced Fe 2+ +Mo 6+ →Fe 3+ +Mo 5+ Proceed as far to the right as possible.

[0073] Example 5

[0074] Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ Electrochemical impedance spectroscopy analysis of anode materials

[0075] In order to study the effect of B-site Co doping on Sr 1.95The influence of the electrocatalytic performance of FCMx anode on the open circuit voltage of symmetrical cells supported by oxygen ion conductor LSGM electrolyte (Sr 1.95 FCMx-LSGM-Sr 1.95 Electrochemical impedance spectroscopy (EIS) analysis was performed on FCMx at 650-800°C in a hydrogen atmosphere. The ohmic impedance generated by the electrolyte was deducted and the electrode polarization impedance was directly compared. Figure 10 The AC impedance spectrum of the symmetrical battery obtained by testing is shown in Figure 2. The intercept of the low-frequency band of the real axis with the x-axis represents the electrode polarization impedance. The electrode polarization impedance reaches its minimum value when the Co doping level x = 0.2, which is the lowest polarization impedance and most conducive to the electrochemical reaction at the anode.

[0076] In order to further study the electrochemical process, we performed a relaxation time distribution (DRT) analysis on the impedance spectrum and used the L1R1 (R2 / / CPE1) (R3 / / CPE2) (R4 / / CPE3) (R5 / / CPE4) equivalent circuit to fit the impedance spectrum. CPE1, CPE2, CPE3, and CPE4 are constant phase elements. L1 and R1 represent the inductance and ohmic impedance of the conductor, current collector, and electrolyte, respectively. R2 represents the high frequency (R H ), R3 represents the intermediate frequency (R M ), R4 and R5 represent the low frequency (R L ) polarization impedance, the total polarization impedance R p =R H +R M +R L Total polarization impedance R p It is mainly caused by the adsorption and dissociation of gas on the surface of the material, ion exchange at the interface and charge transfer. Among them, the high frequency part is related to charge transfer, the medium frequency part is related to oxygen ion transfer, and the low frequency part is related to gas diffusion, adsorption and dissociation. We can see that Sr 1.95 The DRT peak area of ​​the FCMx sample is the largest in the low-frequency part, indicating that the main controlling factors of the reaction steps are gas diffusion, adsorption and dissociation.

[0077] In order to more clearly compare the effects of different Co doping amounts on polarization impedance, the Sr 1.95 Compare the impedance curve of FCMx with the DRT graph, such as Figure 11 As shown. It can be seen that with the increase of Co doping amount, the DRT peak area first decreases and then increases, and the polarization impedance R p First decrease and then increase (specific value changes are shown in the table), R p The minimum value is reached when x=0.2, and the conductivity test at this Co doping amount is the maximum value. The increase in conductivity is beneficial to R pIn addition, the precipitated CoFe nano-alloy particles improve the material's ability to adsorb gas, which can reduce the low-frequency R L The overall polarization impedance is reduced, and the catalytic activity and electrochemical performance are improved.

[0078] Example 6

[0079] Study on the discharge performance of single battery

[0080] Sr with different Co doping amounts 1.95 FCMx (x = 0.1, 0.2, 0.3) was used as the anode material, LSGM as the supporting electrolyte, and LSCF as the cathode material to prepare a SOFC single cell for discharge performance testing to explore the effect of Co doping amount on the performance of the single cell. Figure 12 Figures a, c, and e show the discharge performance at 650-800°C in a hydrogen atmosphere. Within the test temperature range, the open circuit voltage of the single cell remained above 1.0V, ensuring good battery sealing. The test data is authentic and valid for comparison. For a single cell with x=0.1 as the anode, the power density reached 721, 587, 393, and 184 mW·cm at 800, 750, 700, and 650°C, respectively. -2 The power density of the single cell with x = 0.2 as the anode is 1113, 545, 284 and 121 mW·cm at 800, 750, 700 and 650 °C, respectively. -2 The power density of the single cell with x = 0.3 as the anode is 712, 285, 163 and 99 mW·cm at 800, 750, 700 and 650 °C, respectively. -2 When the Co doping amount x=0.2, the power density in hydrogen atmosphere is the highest.

[0081] Figure 12 Figures b, d, and f show the discharge performance at 650-750°C in an ethane atmosphere. For a single cell with x = 0.1 as the anode, the power density reached 175, 99, and 33 mW·cm at 750, 700, and 650°C, respectively. -2 The power density of the single cell with x = 0.2 as the anode is 229, 83 and 60 mW·cm at 750, 700 and 650 °C, respectively. -2 The power density of the single cell with x = 0.3 as the anode is 165, 115 and 47 mW cm at 750, 700 and 650 °C, respectively. -2 The power density in ethane is lower than that in hydrogen because the electrochemical oxidation process of ethane is more difficult than that of hydrogen.

[0082] The power density is highest when the Co doping level x = 0.2, whether in hydrogen or ethane atmospheres. This is likely due to its highest electrical conductivity and lowest polarization impedance. Appropriate Co doping precipitates a uniformly dispersed CoFe alloy that anchors to the substrate surface, improving electronic conductivity and promoting the creation of electrochemically active sites, thus significantly contributing to enhanced catalytic activity. This facilitates electrochemical reactions and significantly improves the electrochemical performance of the anode material.

[0083] A single cell with the best electrochemical performance, a Co doping level of x = 0.2, was selected as the anode. The anode reaction tail gas products were directly fed into a gas chromatograph (GC). The corresponding product peak areas were calculated to determine ethane conversion and ethylene selectivity, which serve as a measure of the ability of the co-generated SOFC to produce chemical value-added products. As shown in Figure 13, ethane conversion gradually increases with increasing temperature, reaching 34.2% at 750°C. Ethylene selectivity, however, decreases with increasing temperature. This is due to the production of more byproducts at high temperatures, with CH4, C3H8, and C3H6 being the primary byproducts. Comparing the product profiles under open circuit voltage (OCV) and constant current discharge, the ethane conversion at 750°C was 25.5% under OCV and 34.2% under constant current. The introduction of current promotes the transport of oxygen ions, facilitating the electrochemical oxidation of ethane and, consequently, its conversion. The use of an oxygen ion electrolyte prevents overoxidation of ethane, avoiding the production of excessive byproducts and improving the selectivity of ethane oxidation to ethylene. The advantage of symbiotic SOFC over traditional SOFC is that it can convert ethane into value-added chemicals such as ethylene while generating electricity, effectively achieving the symbiosis of electricity and ethylene.

[0084] In order to evaluate the stability of the anode single cell with Co doping amount x = 0.2, Figure 14 a is in ethane atmosphere at 750℃ (10ml·min -1 ) and apply a constant potential of 0.7 V, and record the curve of the current density changing with time. Figure 14 It can be seen that during the 20h test, the current density was stable and there was no obvious attenuation, which shows that the output power of the battery is stable and has good stability under hydrocarbon fuels. After the stability test, the surface of the anode of the battery was characterized by SEM, and it was observed that its structure did not collapse and remained intact, without cracking or stratification. The Raman infrared spectroscopy test conducted after the stability test did not show obvious characteristic peaks of carbon, which can indicate that the x=0.2 anode has good resistance to carbon deposition. This may be due to the strong interaction between the CoFe alloy nanoparticles precipitated in situ on the surface of the substrate, which can effectively avoid the agglomeration and deposition of carbon deposits at the anode, leading to deactivation, so that the battery maintains stable operation in a hydrocarbon fuel atmosphere, ensuring the stability of the battery's electrochemical performance.

[0085] In summary, through the study of Sr 1.95 The discharge performance and electrocatalytic performance of FCMx (x = 0.1, x = 0.2, x = 0.3) anode materials of symbiotic SOFC were tested to explore the effect of B-site Co doping in the double perovskite matrix on the material structure and performance. The following conclusions were obtained: 1) Through XRD analysis of the material phase, pure B-site Co doped Sr 1.95 In FCMx materials, the radius of Co ions is slightly smaller than that of Fe ions, and the unit cell volume decreases after doping. After reduction, CoFe alloy is precipitated without phase change, maintaining the stability of the material structure. 2) XPS analysis shows that Fe 3+ / Fe 2+ with Mo 5+ / Mo 6+ The electron ratio reaches its maximum when the Co doping amount x=0.2, and the B-site Co doping affects the Fe 2+ +Mo 6+ →Fe 3+ +Mo 5+ Chemical equilibrium, which greatly affects the conductivity of the anode material. Co doping at the B site is beneficial to the reduction of Sr 1.95 The FCMx material precipitates more metallic CoFe, which helps improve the catalytic activity of the anode catalyst material. 3) Electrochemical impedance spectroscopy analysis shows that the in-situ precipitated CoFe alloy nanoparticles enhance catalytic activity and thus reduce the polarization impedance of the electrode. At x = 0.2, the resistance is 0.221Ω·cm in a hydrogen atmosphere at 800°C. 2 4) According to the test results of SOFC single cell, the highest power density x = 0.2 reached 1113mW·cm at 800℃ in hydrogen. -2 , reaching 228 mW·cm in ethane at 750 °C -2 The ethane conversion rate reached 34.2%, enabling the cogeneration of electricity and ethylene in a SOFC. Stability testing results showed that the electrochemical performance remained stable after 20 hours of operation in an ethane atmosphere, with no noticeable carbon deposition. The B-site Co doping level of x = 0.2 exhibits excellent electrochemical performance, including excellent resistance to carbon deposition, stability, and electrocatalytic activity, making it an excellent anode material for SOFCs.

[0086] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A solid oxide fuel cell, characterized in that: It includes a solid electrolyte and an anode and a cathode located on both sides of the solid electrolyte, wherein the material of the anode is Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ , where x=0.2; The material of the solid electrolyte is LSGM; The cathode material is LSCF-SDC, wherein LSCF is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ,SDC is Sm 0.2 Ce 0.8 O 1.9 .

2. A method for preparing a solid oxide fuel cell according to claim 1, characterized in that: The steps include: providing an anode, wherein the material of the anode is Sr 1.95 Fe 1.5-x Co x Mo 0.5 O 6-δ , where x=0.2; The anode and cathode are printed on both sides of the solid electrolyte, and the anode and cathode are connected via a wire to manufacture the solid oxide fuel cell.

3. The method for preparing a solid oxide fuel cell according to claim 2, wherein: The preparation of the anode comprises the steps of: Co(NO3)2, Sr(NO3)2, Fe(NO3)3·9H2O and (NH4)6Mo7O were added according to the set stoichiometric ratio. 24 4H2O is dissolved in an aqueous solution containing nitric acid until it is completely dissolved to obtain a first mixed solution; According to n (CA) :n (EDTA) :n (total ions) =1.5:1:1, sequentially adding citric acid and ethylenediaminetetraacetic acid to the first mixed solution, stirring evenly to obtain a second mixed solution; adding aqueous ammonia to the second mixed solution, adjusting the pH value of the second mixed solution to 7-7.5 to completely dissolve the EDTA, thereby obtaining a third mixed solution; The third mixed solution is stirred to form a metal complex solution, and then heated at 200° C. to evaporate to dryness until combustion occurs, and the precursor is collected; The precursor is moved into a crucible and calcined to obtain the anode.

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