Solid Oxide Fuel Cell Cathode Research Articles

CO2/Cr-tolerance and oxygen reduction reaction of novel high-entropy perovskite cathode for intermediate temperature solid oxide fuel cell

The development and exploration of cathode oxides with outstanding electrocatalytic activity are critical processes aimed at achieving a decrease in the operation temperature of solid oxide fuel cells (SOFC). Herein, a novel high-entropy oxide, La0.2Pr0.2Nd0.2Sm0.2Gd0.2BaCoFeO5+δ (HEP), which incorporates five lanthanide species (La, Pr, Nd, Sm, and Gd) in the A-site of perovskite, has been specifically developed and assessed as selected cathode for intermediate-temperature SOFC. Investigations of phase structure, chemical compatibility, oxygen transport characteristics, oxygen reaction kinetic, thermal expansion, surface chemical state, conductivity, as well as CO2/Cr-durability are thoroughly performed to assess the basic physicochemical properties of the HEP cathodes. The HEP cathode possesses good operational stability, moderate thermal expansion behavior, fast oxygen transport dynamics, and superior chemical compatibility with the electrolyte. At 700 °C, the polarization resistance low to 0.072 Ω cm2 and output power density high to 332.2 mW cm−2 were obtained for the symmetrical and electrolyte-supported single cells. Furthermore, a stable current density is obtained for the single cell operating at 600 °C and 0.5 V for 100 h. Analysis of electrochemical impedance spectra (EIS) and distribution of relaxation time (DRT) data at different oxygen partial pressures reveal that the charge-transfer and oxygen ions ionization processes at intermediate frequencies present a significant limiting step in the rate of the oxygen reduction reaction. However, under realistic utilization conditions, cathodes of cells often endure irreversible performance degradation owing to the Cr deposition from interconnects or CO2 poisoning in air. Hence, the behavior of Cr and CO2 poisoning is also systematically investigated in symmetrical cell measurements; the results confirm that the HEP cathode displays good resistance to Cr and CO2 poisoning. Overall, our findings indicate that the HEP material is regarded as a favored ceramic cathode for SOFC.

Characteristics of Ag-doped LaMnO3 perovskite oxide and its application as a solid oxide fuel cell cathode

Ag-doped LaMnO3 perovskite oxides were evaluated as new cathode materials for solid oxide fuel cells. Stable power generation properties were obtained, which indicated that the Ag acceptor was stable and was compatible with the YSZ electrolyte.

Optimisation of the electrochemical performance of (Nd,Gd)1/3Sr2/3CoO3−δ cathode for solid oxide fuel cells via spray-pyrolysis deposition and decoration with Ag nanoparticles

Improved electrochemical performance of (Nd,Gd)1/3Sr2/3CoO3−δ:Ce0.9(Gd,Nd)0.1O1.95 air electrode for SOFCs employing spray pyrolysis deposition and simultaneous decoration with Ag nanoparticles.

INVESTIGATION OF THE SOLID OXIDE FUEL CELL (SOFC) BY MEANS OF CFD SIMULATION

In this research, computational fluid dynamics simulations are employed to investigate the behavior of the flow and electrochemistry of planer-type solid oxide fuel cells (SOFCs). The flow distributions in the cathode and anode of an original SOFC are simulated, and the results well agree with the experiments. To reduce non-flow areas in the cathode and anode and hence increase the operating life of the cell, a number of improved flow channel layouts are proposed and simulated. The most effective layout shows a significant reduction of non-flow areas improving flow and temperature distributions throughout the cell. However, as compared to the original SOFC, the electrical power density of the most effective channel SOFC is 12.5% lower. Further investigations are required to improve the flow and temperature distributions and increase the output power.

An excellent bismuth-doped perovskite cathode with high activity and CO2 resistance for solid-oxide fuel cells operating below 700 °C

Lowering the operating temperatures of solid-oxide fuel cells (SOFCs) is critical, although achieving success in this endeavor has proven challenging. Herein, Bi0.15Sr0.85Co0.8Fe0.2O3−δ (BiSCF) is systematically evaluated as a carbon dioxide (CO2)-tolerant and highly active cathode for SOFCs. BiSCF, which features Bi3+ with an ionic radius similar to Ba2+, exhibits activity (e.g., 0.062 Ω cm2 at 700 °C) comparable to that of Ba0.5Sr0.5Co0.8Fe0.2O3−δ and PrBaCo2O5+δ, while demonstrating a considerable advantage over Bi-doped cathodes. Moreover, BiSCF exhibits long-term stability over a period of 500 h, and an anode-supported cell with BiSCF achieves a power density of 912 mW cm−2 at 650 °C. The CO2-poisoned BiSCF exhibits quick reversibility or slight activation after returning to normal conditions. The exceptional CO2 tolerance of BiSCF can be attributed to its reduced basicity and high electronegativity, which effectively restrict surface Sr diffusion and hinder subsequent carbonate formation. These findings highlight the substantial potential of BiSCF for SOFCs operating below 700 °C.

Enhancing ORR activity and CO2 tolerance of Pr0.4Sr0.6Co0.2Fe0.8O3-δ-based SOFC cathode through synergistic doping and surface modification

The development of cathodes with high catalytic activity and stability remains a critical challenge for the commercialization of solid oxide fuel cells (SOFCs). In this study, a novel approach combining doping and surface modification was employed to enhance the catalytic activity and CO2 resistance of Pr0.4Sr0.6Co0.2Fe0.8O3-δ (PSCF) cathode. Initially, Ni was partially substituted for Fe in PSCF, resulting in the reduction of the average bond energy of metal–oxygen, thereby increasing oxygen vacancy concentration and electrochemical activity. The polarization resistance of PSCFN0.1 at 800 °C was found to be 0.025 Ω·cm2, representing a 32.4 % reduction compared to PSCF. Subsequently, Pr(NO3)3 solution was impregnated on the surface of the PSCFN0.1 using a spin-coating technique, resulting in the formation of a PrO2/PSCFN0.1 heterostructure that significantly improved the oxygen reduction reaction (ORR) kinetics. At 800 °C, the polarization resistance of PrO2-PSCFN0.1 was only 0.016 Ω·cm2, a 56.8 % reduction compared to PSCF. Moreover, the peak power density of PrO2-PSCFN0.1 reached 1190 mW·cm−2 at 800 °C, representing a substantial increase of 207.4 % compared to PSCF. Furthermore, PrO2-PSCFN0.1-based full cell exhibited excellent performance stability and CO2 resistance. This work provides an effective strategy to explore novel cathodes for SOFCs.

A way to limit the long-term degradation of solid oxide fuel cell cathode by decorating the surface with K2NiF4-Structure Pr4Ni3O10+δ phase

Prolonged annealing of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) at 700 °C for 1000 h resulted in phase segregation on the surface in the form of submicron-sized SrO on the grains and micron-sized CoFe2O4 particles near the grain boundaries during electrical conductivity relaxation (ECR) measurements. The presence of segregated particles results in a substantial decrease in the surface exchange coefficient, kchem. To mitigate this issue, the LSCF electrodes underwent a systematic coating process with the K2NiF4-structure Pr4Ni3O10+δ (PNO), while varying the loading content, thickness, and porosity. This is achieved by adjusting the gap between the nozzle exit and LSCF surface, ranging from 2 cm to 9 cm, coupled with the application of ultrasonic vibration of the nozzle chamber operating between 40 kHz and 180 kHz. Optimal surface coverage with a loading content of 0.28 mg cm−2 referred to as PNO5 results in a significant increase in kchem by up to one and a half order of magnitude compared to bare LSCF. The PNO coating effectively suppresses phase segregation during prolonged exposure, resulting in a substantial decrease in degradation. The improved performance is attributed to the optimal surface coverage of coated particulates, which enhances the active sites for oxygen reduction reaction (ORR) and the triple phase boundary (TPB) area. These exceptional characteristics position PNO coated LSCF as a highly promising cathode option for low temperature solid oxide fuel cells (SOFCs).

Mechanistic Study on the Corrosion of (La,Sr)(Co,Fe)O3-δ Cathodes Induced by CO2.

Solid Oxide Fuel Cell (SOFC) cathodes operating in ambient atmospheric conditions inevitably encounter CO2 contamination, leading to sustained performance deterioration. In this investigation, we examined the impact of CO2 on three variants of (La,Sr)(Co,Fe)O3-δ cathodes and employed the distribution of relaxation times method to distinguish distinct electrochemical processes based on impedance spectra analysis. We meticulously analyzed and discussed the corrosion resistance of these (La,Sr)(Co,Fe)O3-δ cathodes under high CO2 concentrations, relying on the experimental data. Electrochemical impedance spectroscopy results revealed that La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF-6428), La0.4Sr0.6Co0.2Fe0.8O3-δ (LSCF-4628), and La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ (LSCFN-46271) cathodes exhibited persistent degradation when exposed to CO2 at temperatures of 650 °C or 800 °C during the durability-testing period. An increase in electrode polarization resistance was observed upon CO2 introduction to the electrode, but electrode performance recovered upon returning to a pure air environment. Furthermore, X-ray diffraction and scanning electron microscopy analyses confirmed that CO2 did not cause permanent damage to the (La,Sr)(Co,Fe)O3-δ cathodes. These findings indicate that the (La,Sr)(Co,Fe)O3-δ cathodes exhibit excellent resistance to CO2-induced corrosion.

Design and sensitivity analysis of a multistage solid oxide fuel cell hybrid system with an inter-cooled-recuperated gas turbine and organic Rankine cycle

A solid oxide fuel cell (SOFC) hybrid system with an inter-cooled-recuperated gas turbine(ICRGT) and organic Rankine cycle (ORC) was designed to address exergy destruction in the burner of a conventional SOFC and gas turbine (GT) system. In unfired mode of this system, SOFC acts as the GT heater and reheater instead of burners; burners are used only to aid load regulation in fired mode. In unfired mode, the system electrical efficiency is 69.86 % and the overall efficiency is 82.22 %. The total exergy destruction of the system is 21.93 % lower than that in fired mode by exergy analysis, which indicates the effectiveness of reducing afterburner exergy destruction, and the superior energy efficiency of this mode. For the design analysis, we analyzed the influence of different factors on the system, including the number of SOFC modules, turbine outlet temperature, burner exhaust into the turbine, oxidant utilization of SOFC cathode(OUC), and fuel utilization of SOFC anode(FUA) on the system. For the sensitivity analysis, we determined the variation rules of the components and system parameters for fuel proportions of 70–105 %. This work provides a reference for optimizing the design and operation of SOFC-GT and other SOFC hybrid systems.

Advancements in Perovskite-Based Cathode Materials for Solid Oxide Fuel Cells: A Comprehensive Review.

The high-temperature solid oxide fuel cells (SOFCs) are the most efficient and green conversion technology for electricity generation from hydrogen-based fuel as compared to conventional thermal power plants. Many efforts have been made to reduce the high operating temperature (>800 °C) to intermediate/low operating temperature (400 °C<T<800 °C) in SOFCs in order to extend their life span, thermal compatibility, cost-effectiveness, and ease of fabrication. However, the major challenges in developing cathode materials for low/intermediate temperature SOFCs include structural stability, catalytic activity for oxygen adsorption and reduction, and tolerance against contaminants such as chromium, boron, and sulfur. This research aims to provide an updated review of the perovskite-based state-of-the-art cathode materials LaSrMnO3 (LSM) and LaSrCOFeO3 (LSCF), as well as the recent trending Ruddlesden-Popper phase (RP) and double perovskite-structured materials SOFCs technology. Our review highlights various strategies such as surface modification, codoping, infiltration/impregnation, and composites with fluorite phases to address the challenges related to LSM/LSCF-based electrode materials and improve their electrocatalytic activity. Moreover, this study also offers insight into the electrochemical performance of the double perovskite oxides and Ruddlesden-Popper phase materials as cathodes for SOFCs.

Supersonic spray derived Cu–Co oxide coating on SUS441 to protect the metallic interconnect and to increase stability of SOFC cathode

The interconnects for solid oxide fuel cells (SOFCs) are usually ferritic stainless steels such as SUS441. These steels have issues of oxidation and Cr diffusion under the operational high temperatures, which can cause serious deterioration of the cathode performance. In order to improve the electrode stability and the oxidation resistivity, this work deposits Cu–Co oxide coating on SUS441 interconnects via room-temperature supersonic spray using fine CuCo2O4 spinel-based oxide powders synthesized via a combustion process. The coating can significantly inhibit the growth of chromium oxide scale on the steel surface and increase the interconnect conductivity by a factor of 4.4 in 200-hr oxidation test in air. The coating effectively prevents Cr diffusion to the cell composed of La0·6Sr0·4FeO3-δ electrode and La0·8Sr0.2Ga0.8Mg0·2O3-δ electrolyte. As a result, the coating substantially increases the cathode performance by reducing the interfacial polarization resistance and improving the stability in 100-hr test at 800 °C. This study demonstrates that this high-performance protective Cu–Co oxide coating has a promising application prospect for SOFC interconnects.

In situ self-assembled NdBa0.5Sr0.5Co2O5+δ/Gd0.1Ce0.9O2-δ hetero-interfaces enable enhanced electrochemical activity and CO2 durability for solid oxide fuel cells

The development of solid oxide fuel cells (SOFCs) faces impediments in terms of challenges associated with oxygen reduction activity and CO2 durability. Therefore, a series of novel composite cathode materials, consisting of NdBa0.5Sr0.5Co2O5+δ (NBSC) and Gd0.1Ce0.9O2-δ (GDC), were designed and synthesized using a one-pot strategy through a self-assembly process. The incorporation of GDC leads to a significant increase in the number of active sites. Furthermore, it alters the anisotropic transport properties of oxygen ions within layered double perovskite materials, consequently creating a three-dimensional conduit for O2– transportation. Simultaneously, the in-situ formation of closely intertwined heterogeneous interfaces between NBSC and GDC particles can facilitate the charge transfer processes and oxygen ion transport, thereby improving the kinetics of the oxygen reduction reaction (ORR). The NBSC-10GDC cathode, prepared through the one-pot method, exhibits reduced polarization resistances and enhanced CO2 tolerance in comparison to the mechanically mixed cathode. At 750 °C, the one-pot NBSC-10GDC exhibits a low area-specific resistance (ASR) of 0.029 Ω cm2, which is 69.8% lower than the ASR of single-phase NBSC and 42.0% lower than mechanically mixed NBSC-10GDC. Additionally, the one-pot NBSC-10GDC demonstrates a remarkable maximum power density (MPD) of 1.36 W cm−2 at 750 °C. These findings highlight the considerable potential of the one-pot NBSC-10GDC as a promising material for SOFC cathode.

Surface electron modulation of metal oxide‐based electrochemical devices by surface additives—linking sensors and fuel cells

AbstractThe interaction between ambient oxygen and the metal oxide surface is central to various electrochemical devices. Solid oxide fuel cell cathodes and semiconducting metal oxide gas sensors are two prominent examples. Parallels between these two systems are highlighted in this perspective. In both cases, the presence of foreign surface species has been found to significantly alter the interactions of the metal oxides’ surfaces with oxygen. On the one hand, interactions are hindered due to the presence of certain impurities, such as the degradation of fuel cell cathode by Si‐species that originate from processing or from operating environments. On the other hand, electrochemically active noble metal additives have been intentionally used to tune the sensor response of metal oxides. In the case of electrochemically active additives, the need for operando spectroscopies to elucidate the mechanism is discussed. Electronic coupling of the surface additive with the metal oxide is found to play a central role in both cases. We use these results to demonstrate that insights gained from either field can be effectively applied to the other.

The effects of sintering temperature and current contacting layer on the performance of lanthanum nickelate electrodes in Solid Oxide Fuel Cells

The Ruddlesden-Popper phase La2NiO4+δ (LNO214) has received a significant level of research attention with respect to its employment as a Solid Oxide Fuel Cell cathode material. However, it is known that there are many factors that are capable of influencing the performance of this phase when utilised in this role. One such factor that can impact on electrode behaviour is the choice of sintering temperature. In this paper, a study of this effect is detailed. This is achieved via the use of both symmetrical and single cell testing configurations, with additional investigation provided by ex-situ analysis. It is shown that a sizeable improvement in electrode performance can be achieved via an increase in sintering temperature. This is despite observations on the reactivity between LNO214 and the contact electrolyte material Ce0.9Gd0.1O2-δ. Further, it is also demonstrated that the addition of a noble metal contacting layer can dramatically improve the performance of an LNO214 electrode. In comparison, the impact of a contacting layer on a state-of-the-art La0.6Sr0.4Co0.2Fe0.8O3-δ composition is shown to be relatively minor. This has implications towards SOFC testing methodologies given the widespread employment of noble metal contacting pastes.

Achieving Fast Oxygen Reduction on Oxide Electrodes by Creating 3D Multiscale Micro-Nano Structures for Low-Temperature Solid Oxide Fuel Cells.

Fast oxygen reduction reaction (ORR) at the cathode is a key requirement for the realization of low-temperature solid oxide fuel cells (SOFCs). While the design of three-dimensional (3D) structures has emerged as a new and promising approach to improving the electrochemical performance of SOFC cathodes, achieving versatile structures and structural stability is still challenging. In this study, we demonstrate a novel architectural design for a superior cathode with fast ORR activity. By employing a completely new fabrication process comprising a 3D printing technique and pulsed laser deposition (PLD), we design 3D La0.8Sr0.2CoO3-δ (LSC) micro-nano structures with the desired shape. 3D-printed yttria-stabilized ZrO2 (YSZ) microstructures significantly increase the ratio of surface area to volume while maintaining suitable ionic conductivity comparable to that of single-crystalline YSZ substrates. Scanning electron microscopy and energy dispersive X-ray microanalysis reveal the formation of crack- or void-free YSZ microstructures and the uniform deposition of LSC films by PLD on the YSZ microstructures. The 3D LSC micro-nano structures show significantly enhanced oxygen surface exchange coefficients (kchem) extracted from electrical conductivity relaxation (ECR) measurements by up to 3 orders of magnitude relative to the bulk LSC. Furthermore, electrochemical impedance spectroscopy measurements verify the kchem values from ECR and no directional difference in the measured ORR activity depending on the shape of 3D microstructures. The dramatic enhancement of the ORR activity of LSC is attributed to the increased film surface areas resulting from the 3D YSZ microstructures.

Enhanced oxygen reduction kinetics of SrCoO3-δ by Ta/Cu or Nb/Cu co-doping as high-performance cathodes for SOFC

Cathodes demonstrating elevated electrochemical catalysis and CO2 endurance are fundamental for solid oxide fuel cells (SOFCs). Herein, Ta/Cu co-doped SrCo0.8Ta0.1Cu0.1O3-δ (SCTC) and Nb/Cu co-doped SrCo0.8Nb0.1Cu0.1O3-δ (SCNC) perovskite oxides were prepared and comparative studied as high-performance SOFC cathodes. Due to the synergistic effects of Ta/Cu and Nb/Cu, the oxygen vacancy content, the ratio of Co3+/Co4+, the average bonding energy and the critical radius in the material are well regulated, resulting in the reduction of TEC and enhanced electrochemical catalytic activity in SCTC and SCNC. At 800 °C, SCTC exhibits an ASR of 0.033 Ω cm2, while it is 0.038 Ω cm2 for SCNC. Additionally, SCTC demonstrates a considerable output performance of 0.89 W cm-2, representing a 15.65% improvement over SCNC. This work offers a highly effective approach to developing materials for next-generation energy transformation devices.

Enhancing oxygen exchange kinetics of solid oxide fuel cell cathode: Unleashing the potential of higher order Ruddlesden-Popper phase surface modification

Tailoring the electrode surface represents a promising strategy to enhance electrochemical performance while preserving base material integrity. Achieving appropriate surface coverage with catalytic active oxide material is critical for efficient oxygen transport at the triple phase boundary (TPB). To further explore this approach, the perovskite structure La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) is decorated with a higher order Ruddlesden-Popper phase Pr4Ni3O10+δ (PNO). This combination is being investigated using electrical conductivity relaxation (ECR) technique to study the oxygen exchange kinetics. Samples with varying surface coverage of PNO are examined in a temperature range of 650 °C–850 °C, with a step change in pO2 between 0.1 atm and 0.21 atm. The chemical diffusion coefficient, Dchem, remains invariant across all the samples, however, the surface exchange coefficient, kchem, varies with the surface coverage of PNO. Notably, the coated sample with a PNO loading content of 0.28 mg cm−2, referred to as PNO5, demonstrates a significant enhancement of nearly two orders of magnitude in kchem compared to bare LSCF at 650 °C. This substantial improvement is ascribed to the increased active sites of ORR within the TPB region and the facilitated electron access through tunneling from LSCF to the coated phase. Pulse isotopic exchange (PIE) measurements on the fractionated powders confirm the fast surface exchange kinetics of PNO. Such remarkable oxygen exchange characteristics encourage the use of PNO, along with LSCF, as potential candidates for SOFC cathodes.

Heuristic Approach to Predict the Performance Degradation of a Solid Oxide Fuel Cell Cathode.

The present work aims to predict the degradation in the performance of a solid oxide fuel cell (SOFC) cathode owing to cation interdiffusion between the electrolyte and cathode and surface segregation. Cation migration in the (La0.60Sr0.40)0.95Co0.20Fe0.80O3-x (LSCF)-Gd0.10Ce0.90O1.95 (GDC) composite cathode is evaluated in relation to time up to 1000 h using scanning transmission electron microscopy (STEM)-energy-dispersive X-ray spectroscopy (EDXS). The resulting insulating phase formed within the GDC interlayer is quantified by means of the volume fraction using a two-dimensional (2D) image analysis technique. For the very first time, the amount of the insulating phase in the GDC interlayer is quantified, and the corresponding performance degradation of the LSCF cathode is predicted. Mathematical relationships are established for the estimation of degradation due to surface segregation of the cathode. The ohmic resistance between the cathode and the GDC interlayer/electrolyte interface and the polarization resistance of the cathode, characterized by electrochemical impedance spectroscopy (EIS), show an excellent match with the predicted results. The combined degradation analysis and modeling for the cathode lifetime prediction provide a systematic understanding of the time-dependent cation migration and segregation behavior.

Enhancing the oxygen reduction reaction activity of SOFC cathode via construct a cubic fluorite/perovskite heterostructure

Pr2NiO4+δ-based (Ruddlesden-Popper) perovskite-structured oxide materials are promising candidates for low and intermediate temperature solid oxide fuel cells (SOFCs) systems. In this study, we prepared a high-performance cubic-fluorite/perovskite heterostructure Pr6O11-Pr1.2Sr0.8NiO4+δ (PO-PSNO) cathode for intermediate temperature SOFCs by solution impregnation method. By changing the impregnation amount of Pr6O11, the micro-morphology of the heterostructure was regulated, so that the heterostructure interface had the best reactive site. The oxygen reduction reaction (ORR) performance of Pr1.2Sr0.8NiO4+δ is improved, and the content of surface Sr in the heterostructure electrode material is reduced. Our results indicate that the synergistic effect of PO particles and PSNO skeleton makes the heterostructure exhibit a high oxygen surface exchange properties and catalytic performance. When the impregnation amount of PO particles reaches about 10% of the PSNO skeleton, the heterostructure has the best ORR activity. The oxygen surface exchange coefficient (Kchem) of 2-PO-PSNO is 5.8 × 10-4 cm·s−1, being 1.45 times as that of PSNO at 750 °C. Meanwhile, the polarization impedance (Rp) of 2-PO-PSNO is reduced by 66% to only 0.114 Ω cm2. Our study provides a new approach for developing high-performance RP structured perovskite cathodes and demonstrates practical applications in the field of SOFCs.

Nanostructured Mg-doped Mn–Cr spinel oxide cathodes for solid oxide fuel cells with optimized performance

The cathode properties are critical for solid oxide fuel cells (SOFCs) performance and a major challenge for commercialization. This study employs the impregnation method to produce uniformly distributed Mg-doped manganese-chromium spinel oxide nanoparticles infiltrated into a network on the Gd0.1Ce0.9O1.95 (GDC) skeleton as SOFC cathodes. The effects of Mg doping on the performance of these nanostructured spinel oxides are investigated. Both experimental results and density functional theory (DFT) calculations demonstrate that Mg doping can optimize the electronic structure of the manganese-chromium spinel oxide, increase the oxygen vacancy concentration, and significantly enhance the electrical conductivity and oxygen reduction reaction (ORR) catalytic activity. The Mg-doped manganese-chromium spinel oxide cathode exhibits superior performance, with an area-specific polarization resistance of 0.33 Ω cm2 and a maximum power density of 976 mW cm−2 at 800 °C. Moreover, the nanostructures of the cathode barely change after 100 h of cell operation. These findings provide a new strategy for optimizing the performance of SOFC spinel oxide cathodes.