A particle-tunable LaNi 0.6 Fe 0.4 O3 Contact Layer Materials and Applications

Abstract

This invention relates to solid oxide fuel cells / electrolytes, belonging to the field of new energy, and specifically discloses a LaNi 0.6 Fe 0.4 A method and application for controlling the particle size of O3 contact layer materials. The method involves: calcining the contact layer material powder at high temperature in air; pre-grinding the calcined powder; sieving the treated powder through a sieve to obtain the target powder; and mixing the sieved powder with a binder in a certain proportion to form a slurry for application. This invention successfully achieves the particle size control of LaNi. 0.6 Fe 0.4 The particle size of the O3 contact layer material was controllably adjusted; the effects of particle size on the electrochemical performance output, thermal stability, and degradation mechanism under load were investigated. This method is simple to prepare, requires no complex mechanical equipment, is easy to operate, and is suitable for large-scale industrial applications, demonstrating significant practical value.

Description

Technical Field

[0001] This invention relates to a particle-tunable LaNi 0.6 Fe 0.4 O3 contact layer materials, their preparation and control methods, and their applications, are used in solid oxide fuel cells / electrolytes, belonging to the field of new energy. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are all-solid-state energy conversion devices with advantages such as wide applicability of fuels, high energy conversion efficiency (approximately 45%–60% for primary power generation and approximately 90% for combined heat and power), long operating life (currently up to 80,000 hours), and modularity. They are an important component of my country's "clean, low-carbon, safe, and efficient" modern energy system.

[0003] The battery stack is the core component of an SOFC power generation system, consisting of individual cells, current collectors, connectors, seals, and other auxiliary frames stacked in a specific order. During assembly, if the cathode and connector are in direct contact for power extraction, it will result in significant contact resistance, affecting the stack's performance. Therefore, adding a cathode contact layer (also known as a current collector layer) is typically used to improve the contact between the cathode and connector and reduce contact resistance.

[0004] Currently, research on cathode-side contact layer materials for intermediate-temperature solid oxide fuel cells mainly focuses on three types: precious metal materials such as gold and silver, perovskite materials, and spinel materials. Among these, precious metal materials are limited in their use as contact materials due to their high cost and volatility at high temperatures. Spinel materials have poor sinterability, typically requiring sintering at temperatures above 1000℃, making them unsuitable for use as contact layer materials. The performance of different perovskite contact materials has been evaluated in numerous configurations, with lanthanide perovskite materials being the most widely studied as contact layer materials.

[0005] Among existing reports on contact layer materials, widely used cathode contact layer materials include LaNi. 0.6 Fe 0.4 O3 (LNF) exhibited excellent performance. For example, Rak-Hyun Song et al. used LaNi 0.6 Fe 0.4O3 (LNF) material, used as a protective coating between the cathode and the connector, achieved good long-term stability at an operating temperature of 800℃. (Nurhadi S. Waluyo, RakHyun Song, Seung Bok Lee, TakHyoung Lim, Seok Joo Park, JongWon Lee. Journal of The Electrochemical Society, 2016, 163(10).) In this study, the coating was prepared by electrophoretic deposition (EPD), and the coating thickness and microstructure were controlled by adjusting EPD parameters (including the solid content in the suspension, deposition time, and applied voltage). However, the particle size change was not significant, and the electrophoresis equipment was expensive and complex to operate. In addition, Wang Yu et al. found that using LaNi 0.6 Fe 0.4 While using O3 (LNF) material as a cathode contact layer and current collector improves electrical contact and enhances battery performance, it also reduces performance under low oxygen partial pressure, leading to a significant increase in impedance in the high-frequency region. This may be due to the additional LNF current collector layer hindering gas diffusion. (Wang Y, Lyu Q, Zhu T, et al. Journal of The Electrochemical Society, 2022, 169(4): 044531.) Although existing literature indicates that the particle size of the material is closely related to its performance, it does not provide a concise method for controlling the size. Morán-Ruiz et al. found that using LaNi between the cathode and the connector... 0.6 Fe 0.4 O3 (LNF) can effectively reduce sheet resistance as a contact layer, but under current load, the sheet resistance fluctuates significantly. (Moran-Ruiz, A., Vidal, K., Larranaga, A., Arriortua, MI. Fuel cells, 2016, 16(3).) Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a LaNi material with adjustable dimensions, in view of the above-mentioned technical status. 0.6 Fe 0.4 O3 contact layer material particles, their preparation method, control method, and applications. The preparation method of this invention is simple, requires no complex mechanical equipment, is easy to operate, suitable for large-scale industrial applications, and has good application value. This invention successfully achieves LaNi 0.6 Fe 0.4 The preparation and controllable adjustment of O3 contact layer materials were investigated, and the influence mechanism of particle size on conductivity and single-cell performance was studied. The prepared large-particle contact layer material has good application value.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0008] A size-controllable LaNi 0.6 Fe 0.4 O3 contact layer material

[0009] LaNi 0.6 Fe 0.4 O3, used as a contact layer material, has an average particle size of 1–2 μm.

[0010] The above-mentioned LaNi 0.6 Fe 0.4 O3 contact layer material; the contact material has electronic conductivity in air, primarily electronic conductivity; its coefficient of thermal expansion ranges from 5 to 25 x 10⁻⁵. -6 K -1 It is between; and possesses a certain degree of sintering activity.

[0011] The above-mentioned LaNi with controllable morphology 0.6 Fe 0.4 The preparation method of O3 contact layer material includes the following steps:

[0012] (1) The contact layer material powder is calcined at high temperature in an air atmosphere;

[0013] (2) The calcined powder is subjected to preliminary grinding treatment; the treated powder is sieved through a sieve to obtain the target powder.

[0014] According to a preferred embodiment of the present invention, in step (1): the calcination temperature is higher than the powder preparation temperature and the SOFC operating temperature, preferably 1000–1300℃; the calcination time is 1–24 h, preferably 4–8 h. The calcination temperature and calcination time need to be appropriate, otherwise the present invention cannot be achieved. The calcination temperature has a significant impact on the particle size of the final contact layer material; if the calcination temperature is too high, the powder coarsens, the particle size increases but the catalytic activity decreases; if the calcination temperature is too low, the powder particle size remains essentially unchanged, and there is no effect.

[0015] According to a preferred embodiment of the present invention, in step (2): the calcined powder is subjected to preliminary grinding treatment for 1 to 60 minutes; the ground powder is then sieved through a sieve, the sieve being between 80 and 200 mesh, preferably 100 to 200 mesh. The selection of the sieve for powder sieving has a significant impact on the particle size of the final contact layer material; if the selected sieve wire diameter is too small, the sieved powder particles will be small and have no obvious effect; if the selected sieve size is too large, the obtained powder will be a simple particle agglomeration, not its true morphology and size, and the powder will be uneven in size, making it unsuitable for subsequent use.

[0016] According to the preferred embodiment of the present invention, the particle size of the contact layer material is controlled by controlling the high-temperature calcination temperature and calcination time in step (1) and the screen wire diameter in step (2).

[0017] The method for preparing the above-mentioned morphology-controllable contact layer material includes the following steps:

[0018] (1) The contact layer material powder is calcined at high temperature in an air atmosphere;

[0019] (2) The calcined powder is subjected to preliminary grinding treatment; the treated powder is sieved through a sieve to obtain the target powder.

[0020] (3) The particle size of the contact layer material is controlled by controlling the high-temperature calcination temperature and calcination time in step (1) and the wire diameter of the screen in step (2).

[0021] According to the preferred embodiment of the present invention, the particle size of the contact layer material is controlled by controlling the high-temperature calcination temperature and calcination time in step (1) and the screen wire diameter in step (2); preferably, increasing the calcination temperature increases the particle size; increasing the calcination time increases the particle size.

[0022] LaNi obtained by the above preparation method 0.6 Fe 0.4 The application of O3 contact layer materials involves preparing contact layers from powders of different particle sizes using various methods, and then applying them to solid oxide fuel cells / stacks. This is in contrast to the application of untreated LaNi after high-temperature calcination. 0.6 Fe 0.4 As the particle size of the O3 contact layer material increases, the porosity and conductivity of the resulting contact layer increase, while the surface resistivity decreases and remains stable, unaffected by the discharge current. Methods for preparing the contact layer include, but are not limited to, screen printing, brushing, extrusion molding, and wet spraying.

[0023] This invention provides a simple, efficient method for controlling LaNi without requiring complex equipment. 0.6 Fe 0.4 The method and application of O3 contact layer material particles were studied, and the influence mechanism of particle size on conductivity and single-cell performance was clarified. Furthermore, the contact layer structure formed using this method is stable, exhibiting stable resistance under current load with almost no attenuation.

[0024] Technical features and beneficial effects of the present invention:

[0025] 1. The preparation process of this invention is simple, time-saving, resource-saving, requires no complex equipment, and is conducive to large-scale production; the raw materials are almost undamaged during the preparation process of this invention, which is in line with green chemistry and beneficial to environmental protection.

[0026] 2. In the preparation process of this invention, the high-temperature calcination temperature, calcination time, and the wire diameter of the sieve used for sieving all affect the obtained LaNi 0.6 Fe 0.4 The particle size of the O3 contact layer material has a significant impact; by controlling the calcination temperature, calcination time, and the wire diameter of the sieve used for sieving, the particle size of LaNi can be optimized. 0.6 Fe 0.4 Effective control of particle size in O3 contact layer material; LaNi prepared in this invention 0.6 Fe 0.4 The average particle size of the O3 contact layer material can be controllably adjusted within the range of 1 to 10 μm, and the morphology is uniform.

[0027] 3. The LaNi prepared by this invention 0.6 Fe 0.4 Due to their unique particle size, the O3 contact layer particles exhibit excellent electrochemical performance. Furthermore, the high-temperature calcination process prevents the powder particles from easily agglomerating, resulting in a more numerous and stable porous structure with lower diffusion resistance, higher conductivity, and lower sheet resistivity. This facilitates oxygen diffusion and transport, reduces sensitivity to changes in oxygen partial pressure, and clarifies the mechanism by which the particle size of the contact layer material affects conductivity and single-cell performance. This also points to a direction for future contact layer optimization: future optimization may require a trade-off between material activity and particle size, ensuring that increasing particle size does not significantly alter the catalytic activity of the powder. This approach has significant practical application value. Attached Figure Description

[0028] Figure 1 This is a statistical diagram of the particle size distribution of LNF contact layer particles obtained in Example 1 of the present invention.

[0029] Figure 2 SEM image of LNF contact layer particles prepared in Application Example 2 of the present invention after being applied to a single cell.

[0030] Figure 3 The AC impedance spectrum of the LNF contact layer particles prepared in Application Example 2 of the present invention is used for single cell testing.

[0031] Figure 4 This is a statistical diagram of the particle size distribution of LNF contact layer particles obtained in Example 3 of the present invention.

[0032] Figure 5 SEM image of LNF contact layer particles prepared in Application Example 4 of the present invention after being applied to a single cell.

[0033] Figure 6 The AC impedance spectrum of the LNF contact layer particles prepared in Application Example 4 of the present invention is used for single cell testing.

[0034] Figure 7 The above is a statistical diagram of the particle size distribution of the contact layer particles in the commercial LNF as a comparative example 1.

[0035] Figure 8 For comparison, here are SEM images of commercial LNF contact layer particles applied to a single cell in Application Example 2.

[0036] Figure 9 For comparison, the AC impedance spectrum of commercial LNF contact layer particles used in single cell testing in Application Example 2 is shown.

[0037] Figure 10 The graph shows the performance comparison of the LNF contact layer particles prepared in Example 2 of this invention applied to single-cell testing, the LNF contact layer particles prepared in Example 4 of this invention applied to single-cell testing, and the performance comparison of the commercial LNF contact layer particles in Example 2 applied to single-cell testing.

[0038] Figure 11 The diagram shows the LNF contact layer particles prepared in Application Example 2 of this invention applied to simulated fuel cell stack testing, and a comparison of the discharge performance of commercial LNF contact layer particles applied to simulated fuel cell stack testing in Application Example 2. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments and accompanying drawings, for those skilled in the art to understand and read, and is not intended to limit the conditions under which the present invention can be implemented, and therefore has no substantial technical significance.

[0040] Furthermore, the experimental methods described in the following examples are all conventional methods unless otherwise specified; reagents and materials, unless otherwise specified, are all commercially available. For example, the commonly used commercial contact layer material LaNi... 0.6 Fe 0.4 For example, O3(LNF):

[0041] Example 1

[0042] A LaNi with controllable particle size 0.6 Fe 0.4 The preparation method of O3 contact layer material includes the following steps:

[0043] The specific preparation process involves placing a certain mass of LaNi in an air atmosphere. 0.6 Fe 0.4 O3 (LNF) was calcined in a muffle furnace at 1100℃ for 5 hours. The calcined LNF powder was then ground in a mortar for 5 minutes. The ground powder was then sieved between 100 mesh and 200 mesh sieves to separate the powder with a particle size between 100 and 200 mesh, thus obtaining a powder with a uniform and appropriate particle size, which was denoted as LNF-1100.

[0044] The particle size distribution diagram of the LNF powder particles prepared in Example 1 is as follows: Figure 1 As shown, its D50 particle size (the particle size corresponding to a cumulative particle size distribution percentage of 50% in a sample) is approximately 6.85 μm.

[0045] Application Example 2

[0046] The application of a contact layer material with controllable particle size includes the following steps:

[0047] The specific preparation process involves grinding the sieved LNF-1100 powder and binder in a mortar at a weight ratio of 1:1.5 for 30 minutes to ensure uniform mixing. Then, an LNF-1100 slurry is prepared using a three-roll mill. This slurry is screen-printed onto the cathode surface of a YSZ||Ni-YSZ|GDC||LSCF-GDC|LSCF full cell as a current collector layer. The cell is then calcined at 750℃. Finally, a silver mesh is screen-printed onto the surface, and silver wires are attached. The mixture is then tested and ready for use. During the test, the battery was sealed in the battery testing device with silver paste. N2 was introduced into the anode at a flow rate of 50 mL / min, and then the temperature was increased at 2℃ / min. After heating to 750℃, the gas was switched to room temperature humidified (3% H2O) H2. After holding at this temperature for 5 hours, the test was started. After discharging at a voltage of 0.9V for 15 hours and stabilizing for 1 hour, the oxygen partial pressure was adjusted by adjusting the O2-N2 ratio (1, 0.21, 0.14, 0.07, 0.03 atm). Each time the oxygen partial pressure was switched, it was necessary to hold the temperature for a period of time (~10 min) to allow it to stabilize before testing.

[0048] The prepared LNF-1100 slurry was applied to a contact layer ASR resistance testing device. The device was then placed in a muffle furnace and heated to 750°C, followed by a current density of 1 A / cm². 2 The current was subjected to long-term testing for 200 hours.

[0049] SEM images of the LNF-1100 contact layer particles prepared in Example 2 applied to a single cell are shown below. Figure 2 As shown, its grain boundaries are clear, the powder is rounded, and the particle size is about 1.1 μm.

[0050] The AC impedance spectra of the LNF-1100 contact layer particles prepared in Example 2 for single-cell testing are shown below. Figure 3 As shown, compared to the untreated LNF, the ohmic impedance of the LNF-1100 is 0.21 Ωcm. 2 It dropped to 0.17 Ωcm 2 This represents a 19% reduction. Furthermore, the sensitivity of polarization impedance to oxygen partial pressure is slightly reduced.

[0051] Example 3

[0052] A method for preparing a contact layer material with controllable particle size includes the following steps:

[0053] The specific preparation process involves placing a certain mass of LaNi in an air atmosphere. 0.6 Fe 0.4 O3 (LNF) was calcined in a muffle furnace at 1200℃ for 5 hours. The calcined LNF powder was then ground in a mortar for 5 minutes. The ground powder was then sieved between 100 mesh and 200 mesh sieves to separate the powder with a particle size between 100 and 200 mesh, thus obtaining a powder with a uniform and appropriate particle size, which was denoted as LNF-1200.

[0054] The particle size distribution diagram of the LNF powder particles prepared in Example 3 is as follows: Figure 4 As shown, its D50 particle size (the particle size corresponding to a cumulative particle size distribution percentage of 50% in a sample) is approximately 7.12 μm.

[0055] Application Example 4

[0056] The application of a contact layer material with controllable particle size includes the following steps:

[0057] The specific preparation process involves grinding the sieved LNF-1200 powder and binder in a mortar at a weight ratio of 1:1.5 for 30 minutes to ensure uniform mixing. Then, an LNF-1200 slurry is prepared using a three-roll mill. This slurry is screen-printed onto the cathode surface of a YSZ||Ni-YSZ|GDC||LSCF-GDC|LSCF full cell as a current collector layer. The cell is then calcined at 750℃. Finally, a silver mesh is screen-printed onto the surface, and silver wires are attached. The mixture is then tested and ready for use. During the test, the battery was sealed in the battery testing device with silver paste. N2 was introduced into the anode at a flow rate of 50 mL / min, and then the temperature was increased at 2℃ / min. After heating to 750℃, the gas was switched to room temperature humidified (3% H2O) H2. After holding at this temperature for 5 hours, the test was started. After discharging at a voltage of 0.9V for 15 hours and stabilizing for 1 hour, the oxygen partial pressure was adjusted by adjusting the O2-N2 ratio (1, 0.21, 0.14, 0.07, 0.03 atm). Each time the oxygen partial pressure was switched, it was necessary to hold the temperature for a period of time (~10 min) to allow it to stabilize before testing.

[0058] SEM images of the LNF-1200 contact layer particles prepared in Example 4 applied to a single cell are shown below. Figure 5 As shown, its grain boundaries are clear, the powder is rounded, and the particle size is about 1.5 μm.

[0059] The AC impedance spectra of the LNF-1200 contact layer particles prepared in Example 4 for single-cell testing are shown below. Figure 6 As shown, compared to the untreated LNF, the ohmic impedance of the LNF-1200 is 0.21 Ωcm.2 It dropped to 0.15Ωcm 2 This represents a 29% reduction. This indicates that larger powder particle size leads to better cathode current collection and accelerates electron transfer at the cathode interface. Furthermore, the sensitivity of polarization impedance to oxygen partial pressure is significantly reduced.

[0060] Comparative Example 1

[0061] A method for preparing a contact layer material includes the following steps:

[0062] The specific preparation process is as follows: LNF powder is ball-milled in a planetary ball mill for 24 hours and then dried. The dried powder is then ground in a mortar and sieved through a 200-mesh sieve to separate fine LNF-untreated powder.

[0063] The particle size distribution diagram of the LNF powder particles prepared in Comparative Example 1 is shown below. Figure 7 As shown, its D50 particle size (the particle size corresponding to a cumulative particle size distribution percentage of 50% in a sample) is approximately 2.09 μm.

[0064] Comparative Application Example 2

[0065] The application of a contact layer material includes the following steps:

[0066] The specific preparation process involves grinding the sieved LNF-untreated powder and binder in a mortar at a weight ratio of 1:1.5 for 30 minutes to ensure uniform mixing, and then preparing the LNF-untreated slurry on a three-roll mill. The slurry is then screen-printed onto the cathode surface of a YSZ||Ni-YSZ|GDC||LSCF-GDC|LSCF full cell as a current collector layer, followed by calcination at 750℃. A silver mesh is then screen-printed and silver wires are attached for testing and future use. During the test, the battery was sealed in the battery testing device with silver paste. N2 was introduced into the anode at a flow rate of 50 mL / min, and then the temperature was increased at 2℃ / min. After heating to 750℃, the gas was switched to room temperature humidified (3% H2O) H2. After holding at this temperature for 5 hours, the test was started. After discharging at a voltage of 0.9V for 15 hours and stabilizing for 1 hour, the oxygen partial pressure was adjusted by adjusting the O2-N2 ratio (1, 0.21, 0.14, 0.07, 0.03 atm). Each time the oxygen partial pressure was switched, it was necessary to hold the temperature for a period of time (~10 min) to allow it to stabilize before testing.

[0067] The prepared LNF-untreated slurry was applied to an ASR resistance testing device for the contact layer. The device was then placed in a muffle furnace and heated to 750°C, followed by a current density of 1 A / cm². 2 The current was subjected to long-term testing for 200 hours.

[0068] The SEM image of the LNF contact layer particles prepared in Comparative Application Example 2 after application to a single cell is shown below. Figure 8 As shown, its grain boundaries are blurred, and the grain size is small, with a grain size of about 0.4 μm.

[0069] The AC impedance spectra of the LNF contact layer particles prepared in Comparative Application Example 2 for single-cell testing are shown below. Figure 9 As shown, the ohmic impedance is ~0.21Ωcm 2 .

[0070] Figure 10 To compare the performance of the LNF contact layer particles prepared in Application Example 2, the LNF contact layer particles prepared in Application Example 4 of this invention, and the commercial LNF contact layer particles from Application Example 2 in single-cell testing, a performance comparison graph is provided. The graph clearly shows that as the LNF powder particle size increases, the peak power of the single cell significantly improves at all oxygen partial pressures. This indicates that larger LNF powder particle sizes result in lower sintering activity, leading to increased porosity between powder particles, which facilitates oxygen diffusion and transport, thus improving the single-cell performance output. With further increases in calcination temperature, the performance output of LNF-1200 decreases under high oxygen partial pressure, but significantly increases under low oxygen partial pressure. High-temperature calcined powder has larger particle sizes and lower activity, but the resulting pore structure is the most stable and conducive to oxygen diffusion and transport. Therefore, the single-cell performance decreases under high oxygen partial pressure and increases under low oxygen partial pressure.

[0071] Figure 11 The figures show a comparison of the discharge performance of LNF contact layer particles prepared in Application Example 2 of this invention, applied to simulated fuel cell stack testing, and the discharge performance of commercially available LNF contact layer particles applied to simulated fuel cell stack testing. As can be seen from the figures, before treatment, the surface resistivity of the LNF showed a significant decreasing trend in the initial stage of discharge; however, after treatment, its discharge curve was smooth with almost no decrease. Because LNF-1100 undergoes high-temperature (1100℃) calcination, its contact layer structure is the most stable, therefore the current load has a limited impact on its sintering degree.

Claims

1. A LaNi 0.6 Fe 0.4 A method for controlling the particle size distribution of O3 contact layer materials, characterized in that: LaNi 0.6 Fe 0.4 O3 was used as the contact layer material and subjected to high-temperature calcination; the LaNi 0.6 Fe 0.4 The specific steps for controlling the O3 contact layer material are as follows: (1) In an air atmosphere, the contact layer material powder with an average particle size of 1~2μm is calcined at a high temperature of 1000~1300℃. (2) The calcined powder is subjected to preliminary grinding treatment; the treated powder is sieved through a sieve to obtain the target powder, and the average particle size of the treated particles is 6.85μm~10μm; The particle size of the contact layer material is controlled by adjusting the high-temperature calcination temperature and calcination time in step (1) and the wire diameter of the screen in step (2); specifically: increasing the calcination temperature increases the particle size; increasing the calcination time increases the particle size.

2. The particle control method for the contact layer material according to claim 1, characterized in that, Step (1) includes one or more of the following conditions: i. The calcination temperature is higher than the powder preparation temperature and the SOFC operating temperature; ii. Calcination time: 1~24h.

3. The particle control method for the contact layer material according to claim 2, characterized in that, The calcination time is 4 to 8 hours.

4. The method for particle control of the contact layer material according to claim 2, characterized in that, Step (2) includes one or more of the following conditions: i. The calcined powder is subjected to preliminary grinding treatment for 1 to 60 minutes; ii. Sift the ground powder through a sieve with a mesh size between 80 and 200.

5. The method for particle control of the contact layer material according to claim 4, characterized in that, The screen should be 100-200 mesh.

6. LaNi obtained by any one of the particle control methods according to claims 1 to 5 0.6 Fe 0.4 The application of O3 contact layer material is characterized by: LaNi with different particle sizes were obtained 0.6 Fe 0.4 O3 powder is used to prepare contact layers for application in solid oxide fuel cells / stacks.

7. The application according to claim 6, characterized in that: Methods for preparing the contact layer include screen printing, brushing, extrusion molding, or wet spraying.

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