Molybdenum substitution at the B-site of lanthanum strontium titanate anodes for solid oxide fuel cells

The effects of Mo doping into the B-site of La_0.3Sr_0.7TiO_3-δ perovskite on its ionic conductivity and catalytic activity as an anode material of solid oxide fuel cells have been investigated. The partial substitution of Ti by Mo reduces the bond energy between metal and oxygen ions in the perovskite. The concentration of Mo⁵⁺/Mo⁶⁺ redox couples increases with the rise of the content of Mo, while the oxygen ionic conductivity decreases simultaneously. The doping of Mo significantly reduces the anodic polarization resistance and improves the performance of the single cell. The cell with La_0.3Sr_0.7Ti_0.97Mo_0.03O_3-δ anode and La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ electrolyte exhibits a maximum power density of 135 mW cm^?2 at 850 °C with hydrogen as fuel.     

Preparation and electrical properties of yttrium-doped strontium titanate with B-site deficiency

Yttrium-doped strontium titanate with B-site deficiency (Y_0.08Sr_0.92Ti_1−xO_3−δ) is synthesized via conventional solid-state reaction. The effect of B-site deficiency on the lattice parameter, sinterability, microstructure and electrical properties of Y_0.08Sr_0.92TiO_3−δ is investigated. The charge compensation mechanism for B-site deficiency is proposed. The limit of B-site deficiency in Y_0.08Sr_0.92Ti_1−xO_3−δ is below 5 mol % in Ar with 5% H₂ at 1500 °C. The sinterability of Y_0.08Sr_0.92Ti_1−xO_3−δ decreases slightly with increasing deficiency level (x). Compared with Y_0.08Sr_0.92TiO_3−δ, the electrical conductivity of Y_0.08Sr_0.92Ti_1−xO_3−δ samples decreases while the ionic conductivity increases with increasing B-site deficient amount. It is assumed that the deficiency of Ti in Y_0.08Sr_0.92Ti_1−xO_3−δ is charge compensated by the increase of oxygen vacancy concentration and the decrease of Ti³⁺ concentration. Y_0.08Sr_0.92Ti_1−xO_3−δ shows a relatively stable electrical conductivity at different oxygen partial pressures and displays an excellent chemical compatibility with YSZ electrolyte below 1200 °C.     

Investigation of La0.6Sr0.4Co1-xNixO3-δ (x=0, 0.2, 0.4, 0.6, 0.8) catalysts on solid oxide fuel cells anode for biogas dry reforming

The introduction of catalyst on anode of solid oxide fuel cell (SOFC) has been an effective way to alleviate the carbon deposition when utilizing biogas as the fuel. A series of La_0.6Sr_0.4Co_1-xNi_xO_3-δ (x = 0, 0.2, 0.4, 0.6, 0.8) oxides are synthesized by sol-gel method and used as catalysts precursors for biogas dry reforming. The phase structure of La_0.6Sr_0.4Co_1-xNi_xO_3-δ oxides before and after reduction are characterized by X-ray diffraction (XRD). The texture properties, carbon deposition, CH₄ and CO₂ conversion rate of La_0.6Sr_0.4Co_1-xNi_xO_3-δ catalysts are evaluated and compared. The peak power density of 739 mW cm^?2 is obtained by a commercial SOFC with La_0.6Sr_0.4Co_0.4Ni_0.6O_3-δ catalyst at 850 °C when using a mixture of CH₄: CO₂ = 2:1 as fuel. This shows a great improvement from the cell without catalyst for internal dry reforming, which is attributed to the formation of NiCo alloy active species after reduction in H₂ atmosphere. The results indicate the benefits of inhibiting the carbon deposition on Ni-based anode through introducing the La_0.6Sr_0.4Co_0.4Ni_0.6O_3-δ catalyst precursor. Additionally, the dry reforming technology will also help to convert part of the exhaust heat into chemical energy and improve the efficiency of SOFC system with biogas fuel.     

Dy doped SrTiO3: A promising anodic material in solid oxide fuel cells

The perovskite-type oxides, having a general formula ABO₃, are promising candidates for anode materials in solid oxide fuel cells. In particular, doped SrTiO₃ based perovskites are potential mixed ionic-electronic conductors and they are known to have excellent thermal and chemical stability along with carbon and sulfur tolerance. In this work, Dy_xSr_1-xTiO_3-δ system with x = 0.03, 0.05, 0.08 and 0.10 is studied to understand the influence of Dy content on its structural and electrical behavior. Electrochemical properties are measured, both in air and hydrogen atmosphere, and structural characterizations are performed before and after electrochemical tests and compared each other to study the stability. Results show that Dy_xSr_1-xTiO_3-δ powders with x ≤ 0.05, are single phase, while for x ≥ 0.08 a small amount of secondary phases is formed. In air, the conductivity is predominantly mixed ionic-electronic type for x ≤ 0.05, becoming ionic for x ≥ 0.08. It is observed that conductivity, for each composition, increases passing from air to hydrogen and activation energy decreases. Dy_0.05Sr_0.95TiO_3-δ shows the highest conductivity in air whereas Dy_0.08Sr_0.92TiO_3-δ in H₂ atmosphere. Degradation observed by XRD is negligible for x ≤ 0.05 but increases with higher Dy content.     

Highly active and stable Sr0.92Y0.08Ti1−xRuxO3−d in dry reforming for hydrogen production

Biofuels such as sewage gas and landfill gas, which can be used as fuels in solid oxide fuel cells, have suitable composition of CH₄ and CO₂ for dry reforming. We developed an Sr_0.92Y_0.08Ti_1−xRu_xO_3−d material as an anode for solid oxide fuel cells that use biofuels as a direct fuel and show an excellent performance in dry reforming. The Pechini method was used to synthesize the material using ruthenium substitution in the titanium site of an Sr_0.92Y_0.08TiO_3−d (SYT) material. X-ray diffraction analysis confirmed that the perovskite phase of the synthesized catalyst was maintained. Ruthenium-loaded catalysts were prepared by coprecipitating ruthenium onto SYT to compare with the Sr_0.92Y_0.08Ti_1−xRu_xO_3−d. The differences between Sr_0.92Y_0.08Ti_1−xRu_xO_3−d and ruthenium-loaded SYT materials during methane dry reforming and the thermal stability during long-term operation were evaluated. In particular, SYTRu10 exhibited higher methane conversion and carbon dioxide conversion than Ru10-loaded SYT at the temperature range of 600–900 °C and stable performance even in long-term operation. X-ray fluorescence and Brunauer–Emmett–Teller measurements were performed to measure the composition of the catalysts and the specific surface area, pore size, and pore volume of the catalysts. X-ray photoelectron spectroscopy and temperature-programmed reduction were used to investigate the state and behavior of ruthenium. Furthermore, transmission electron microscopy was performed to analyze the shape of the catalyst before and after the reaction.     

Sr0.92Y0.08TiO3−δ/Sm0.2Ce0.8O2−δ anode for solid oxide fuel cells running on methane

Yttria-doped strontium titanium oxide (Sr_0.92Y_0.08TiO_3−δ; SYT) was investigated as an alternative anode material for solid oxide fuel cells (SOFCs). The SYT synthesized by the Pechini method exhibits excellent phase stability during the cell fabrication processes and SOFC operation and good electrical conductivity (about 0.85 S/cm, porosity 30%) in reducing atmosphere. The performance of SYT anode is characterized by slow electrochemical reactions except for the gas-phase diffusion reactions. The cell performance with the SYT anode running on methane fuel was improved about 5 times by SDC film coating, which increased the number of reaction sites and also accelerated electrochemical reaction kinetics of the anode. In addition, the SDC-coated SYT anode cell was stably operated for 900 h with methane. These results show that the SDC-coated SYT anode can be a promising anode material for high temperature SOFCs running directly on hydrocarbon fuels.     

Enhanced ORR activity of A-site deficiency engineered BaCo0·4Fe0·4Zr0·1Y0·1O3-δ cathode in practical YSZ fuel cells

Solid oxide fuel cell (SOFC) is becoming more and more attractive because of enormous progress, like high-performance and durable BaCo_0·4Fe_0·4Zr_0·1Y_0·1O_3-δ (BCFZY) perovskite cathode at intermediate-to-low temperatures. Here, we propose an A-site deficient strategy to further enhance the oxygen reduction reaction (ORR) activity of BCFZY perovskite cathode for intermediate-temperature SOFC based upon commercial 8 mol% yttria-stabilized zirconia (YSZ) electrolyte. Both A-site deficient and stoichiometric BCFZY show a cubic perovskite structure without any impurity phases from room temperature to 1000 °C in air. A ten percent A-site deficiency in BCFZY cathode can dramatically reduce the area specific resistances (ARSs) from 0.73 Ω · cm² to 0.13 Ω · cm² at 650 °C in air, by a factor of 5.6 as compared with the stoichiometric BCFZY cathode. The YSZ-based SOFC with A-site deficient Ba_0·9Co_0·4Fe_0·4Zr_0·1Y_0·1O_3-δ cathode showed the maximum power density of 730 mW · cm^?2 at 800 °C increased to more than 2 times in comparison with stoichiometric BCFZY and the long-term stability of more than 50 hours without any degradation. The results have indicated that the introduction of A-site deficiency can dramatically improve the ORR activity of BCFZY, showing great promise as potential cathode materials in practical YSZ-based fuel cells.     

Performance of an anode-supported tubular solid oxide fuel cells stack with two single cells connected by a co-sintered ceramic interconnector

Two anode-supported tubular solid oxide fuel cells (SOFCs) have been connected by a co-sintered ceramic interconnector to form a stack. This novel bilayered ceramic interconnector consists of La-doped SrTiO₃ (La_0.4Sr_0.6TiO₃) and Sr-doped lanthanum manganite (La_0.8Sr_0.2MnO₃), which is fabricated by co-sintering with green anode at 1380 °C for 3 h. La_0.4Sr_0.6TiO₃ (LST) acts as a barrier avoiding the outward diffusion of H₂ to the cathode; while La_0.8Sr_0.2MnO₃ (LSM) prevents O₂ from diffusing inward to the anode. The compatibility of LST and LSM, as well as their microstructure which co-sintered with anode are both studied. The resistances between anode and LST/LSM interconnector at different temperatures are determined by AC impedance spectra. The results have showed that the bilayered LST/LSM is adequate for SOFC interconnector application. The active area is 2 cm² for interconnector and 16 cm² for the total cathode of the stack. When operating at 900 °C, 850 °C, 800 °C with H₂ as fuel and O₂ as oxidant, the maximum power density of the stack are 353 mW cm⁻², 285 mW cm⁻² and 237.5 mW cm⁻², respectively, i.e., approximately 80% power output efficiency can be achieved compared with the total of the two single cells.     

BaZr0.1Ce0.7Y0.1Yb0.1O3−δ as highly active and carbon tolerant anode for direct hydrocarbon solid oxide fuel cells

BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ (BZCYYb) perovskite is synthesized and examined as an alternative anode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) based on direct hydrocarbon fuels, using polarization and electrochemical impedance spectroscopy techniques. Single-phased BZCYYb anode shows an excellent activity for both hydrogen and methane oxidation reactions, achieving a polarization resistance of 0.25 and 0.93 Ω cm², and overpotential of 20 and 202 mV at 100 mA cm⁻² and 750 °C in wet H₂ (3% H₂O/97% H₂) and wet CH₄ (3% H₂O/97% CH₄), respectively. The electrocatalytic activity of BZCYYb anodes is significantly higher than that of the (La,Sr)(Cr,Mn)O₃ anodes as reported in the literature. Furthermore, BZCYYb exhibits excellent resistance to carbon deposition. The present study demonstrates that BZCYYb perovskite is a promising alternative anode material for direct hydrocarbon fuels based SOFCs.     

Synthesis and properties of Y-doped SrTiO3 as an anode material for SOFCs

Y-doped SrTiO₃ was synthesized via solid-state reaction. The effects of Y-doping on the sinterability and the electrical conductivity of Y_xSr_1−xTiO₃ were investigated. Y-doping can increase the sintering activity and the electrical conductivity of SrTiO₃ when yttrium amount is less than 0.09 in Y_xSr_1−xTiO₃. Excessive yttrium will cause the generation of an insulating phase Y₂Ti₂O₇, which impedes the densification process and decreases the electrical conductivity of Y_xSr_1−xTiO₃ material. With the increased temperature, the electrical conductivity of Y-doped SrTiO₃ increases first and then decreases gradually, showing a mixed conduction behavior of semi-conductors and metals. The optimized Y_0.09Sr_0.91TiO₃ possesses an electrical conductivity on the order of 32.5–195.8 S cm⁻¹ in the temperature range of 25–1000 °C and being 73.7 S cm⁻¹ at 800 °C in forming gas. The thermal cycling in air does not remarkably affect the electrical conductivity and the conduction behavior of Y_0.09Sr_0.91TiO₃ at high temperatures. Y_0.09Sr_0.91TiO₃ displays a relatively stable electrical conductivity at different oxygen partial pressures and excellent chemical compatibility with YSZ at temperatures lower than 1300 °C.     

Evaluation of Sr0.88Y0.08TiO3–CeO2 as composite anode for solid oxide fuel cells running on CH4 fuel

Sr_0.88Y_0.08TiO₃ (YST) was synthesized and the performance of a YST–CeO₂ composite as an alternative anode for the direct utilization of CH₄ in solid oxide fuel cells (SOFCs) was investigated. X-ray diffraction showed that YST had good chemical compatibility with CeO₂ and YSZ (8 mol% Y-doped ZrO₂). The shrinkage of the YST–CeO₂ composite on sintering was less than that of pure YSZ and CeO₂, and its thermal-expansion behavior was similar to that of YSZ. With YSZ as electrolyte, ScSZ (10 mol% Sc-doped ZrO₂)–LSM (La_0.8Sr_0.2MnO₃) as cathode, and YST–CeO₂ composite as anode, single cells were prepared and tested in both H₂ and CH₄. The maximum power density obtained at 900 °C was 161.7 mW cm⁻² in H₂ atmosphere and 141.3 mW cm⁻² in CH₄. The results demonstrated the potential of using YST–CeO₂ composite as the anode for SOFCs.     

In-situ exsolved NiFe alloy nanoparticles on Pr0.8Sr1.2(NiFe)O4-δ for direct hydrocarbon fuel solid oxide fuel cells

NiFe alloy (NFA) nanoparticles decorated Ruddlesden-Popper (RP) type layered perovskite structure Pr_0.8Sr_1.2(NiFe)O_4-δ (RP-PSNF) have been fabricated by in-situ reduction of cubic perovskite Pr_0.32Sr_0.48Ni_0.2Fe_0.8O_3-δ (P–PSNF) in H₂ at 800 °C. When used as the solid oxide fuel cell (SOFC) anode material, the RP-PSNF-NFA based ceramic anode demonstrates a comparable catalytic activity to Ni-based anode. The SOFC single cell with RP-PSNF-NFA-Gd_0.2Ce_0.8O_2−δ (GDC) anode exhibits a maximum power density of 983 and 770 mW cm⁻² in humidified H₂ and C₃H₈ at 800 °C, respectively. More importantly, the single cell shows a high durability at the current density of 250 mA cm⁻² in humidified C₃H₈ at 800 °C, demonstrating an excellent coking resistance. Overall, this work suggests that RP-PSNF-NFA is a promising anode for direct hydrocarbon fuel SOFCs.     

Electrochemical behaviour of an all-perovskite-based intermediate temperature solid oxide fuel cell

A solid oxide fuel cell (SOFC) has been manufactured using a Ni-modified perovskite and perovskite-based electrolyte and cathode. The SOFC has been investigated for operation at intermediate temperatures (800 °C). The electrical properties of La_0.8Sr_0.2Ga_0.8Mg_0.2O₃ (LSGM) perovskite have been compared to gadolinia-doped ceria (GDC) electrolyte. This has allowed to validate the promising properties of the perovskite electrolyte compared to ceria-based ceramic membranes for operation at intermediate temperatures. The reliability of the Ni-modified La_0.6Sr_0.4Fe_0.8Co_0.2O₃ perovskite-based anode for operation in combination with the LSGM electrolyte and a La_0.6Sr_0.4Fe_0.8Co_0.2O₃ (LSFC) cathode has been studied. A 50 h electrochemical test for the SOFC operating under different fuel feed compositions is reported. The all-perovskite SOFC shows promising fuel-flexibility characteristics.     

Ba0·5Sr0·5(Co0·8Fe0.2)1-xTaxO3-δ perovskite anode in solid oxide electrolysis cell for hydrogen production from high-temperature steam electrolysis

Among perovskite anodes in solid oxide electrolysis cell (SOEC), Ba_0·5Sr_0·5Co_0·8Fe_0·2O_3-δ (BSCF) has gained much attention due to its dominantly high performance. However, the BSCF still suffers from chemical instability. In this study, the B-site of BSCF is partially substituted by a higher valence Ta⁵⁺ (5, 10, 15 and 20 mol%) to improve its structural stability - Ba_0·5Sr_0·5(Co_0·8Fe_0.2)_1-xTa_xO_3-δ (BSCFTax, 0 ≤ x ≤ 0.20). It is found that doping with higher valence Ta⁵⁺ increases both chemical stability and electrochemical performance of BSCF. Although the BSCFTa0.10 shows the lowest oxygen vacancies indicating by the ratio of adsorbed oxygen vacancies (O_adsorbed) to lattice oxygen (O_lattice), the electrochemical performance increases. The decrease in Co³⁺/Co⁴⁺ ratio results in increasing electronic conductivity in the anode. It is likely that proper amount of Ta⁵⁺ doping provide a balance between ionic and electronic conductivity in the anode and improved electrochemical performance. The symmetrical half-cells with electrolyte support (BSCFTa/YSZ/BSCFTa) are fabricated to determine the area specific resistance (ASR) and activation energy of conduction - BSCFTa0.10 shows the best performance. Cathode-supported Ni-YSZ/YSZ/BSCFTa0.10 also shows higher durability than Ni-YSZ/YSZ/BSCF (operating at current density ?0.45 A cm^?2 in electrolysis mode, 80 h, 800 °C and H₂O to H₂ ratio of 70:30).     

Electrical conductivity and structural stability of La-doped SrTiO3 with A-site deficiency as anode materials for solid oxide fuel cells

A-site-deficient (La_0.3Sr_0.7)_1−xTiO_3−δ materials were synthesized by conventional solid-state reaction. The A-site deficiency limit in (La_0.3Sr_0.7)_1−xTiO_3−δ was below 10 mol% in 5%H₂/Ar at 1500 °C. A-site deficiency level promoted the sintering process of (La_0.3Sr_0.7)_1−xTiO_3−δ. The ionic conductivity increased but the electronic conductivity decreased with increasing A-site deficiency level. The ionic conductivity of (La_0.3Sr_0.7)_0.93TiO_3−δ sample was as high as 0.2–1.6 × 10⁻² S/cm in 500–950 °C and 1.0 × 10⁻² S/cm at 800 °C, over twice of La_0.3Sr_0.7TiO_3−δ. Its electrical conductivity was in the range of 83–299 S/cm in 50–950 °C and 145 S/cm at 800 °C. A-site deficiency improved the thermal stability of (La_0.3Sr_0.7)_1−xTiO_3−δ and ensured the material with a stable electrical performance in different atmospheres.     

La1-xSrxFeO3 perovskite-type oxides for chemical-looping steam methane reforming: Identification of the surface elements and redox cyclic performance

We report a family of perovskite-type oxides La_1-xSr_xFeO₃ (x = 0.1, 0.3, 0.5, 0.7, 1.0) prepared by combustion method as effective redox catalysts for methane partial oxidation and thermochemical water splitting in a cyclic redox scheme. The effect of Sr-doping on the characterizations and properties of these perovskite-type oxides were studied by means of X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). All the as-prepared and regenerated samples with various Sr substitutions exhibited pure crystalline perovskite structure. The oxygen carrying capacity of the La_1-xSr_xFeO₃ perovskites was improved by doping Sr into the La-site. Besides, Sr-substitution has obvious effects on the valences of the Fe cations in the B-site and the oxygen species distribution of the La_1-xSr_xFeO₃ perovskites. We recommend La_0.7Sr_0.3FeO₃ as the optimal oxygen carrier in the series because it gives the maximum O_la/O_ad (O_la and O_ad stand for lattice oxygen and adsorbed oxygen species, respectively.) ratio of 3.64:1, which can be regarded as a criterion for the reactivity and selectivity of partial oxidation of methane into syngas of the oxygen carriers. Up to 80% CH₄ conversion in the methane partial oxidation step and 96% of H₂ concentration in the water splitting step were achieved in ten successive redox tests conducted in a fixed bed reactor at 850 °C with La_0.7Sr_0.3FeO₃ as a redox catalyst. The electronic properties of the original LaFeO₃ cell and its lattice substituted by Sr were calculated based on the density functional theory method. Electronic structure analysis demonstrates that doping of Sr makes LaFeO₃ more electric conductive and its electron is prone to be excited. This is in agreement with the test results that La_0.7Sr_0.3FeO₃ exhibited better performance in chemical looping reactions.     

Ni-doped A-site-deficient La0.7Sr0.3Cr0.5Mn0.5O3-δ perovskite as anode of direct carbon solid oxide fuel cells

A Ni-doped A-site-deficient La_0.7Sr_0.3Cr_0.5Mn_0.5O_3-δ perovskite (N-LSCM) was synthesized and systematically characterized towards the application as the anode electrode for direct carbon solid oxide fuel cells (DC-SOFCs). The microstructure and electrochemical properties of N-LSCM under the operation conditions of DC-SOFCs have been evaluated. An in-situ exsolution of Ni nanoparticles on the N-LSCM perovskite matrix is found, revealing a maximum power density of 153 mW cm⁻² for the corresponding DC-SOFC at 850 °C, compared to 114 mW cm⁻² of the cell with stoichiometric LSCM. The introduction of Ni nanoparticles exsolution and A-site deficient is believed to boost the formation of highly mobile oxygen vacancies and electrochemical catalytic activity, and further improves the output performance of the DC-SOFC. It thus promises as a suitable anode candidate for DC-SOFCs with whole-solid-state configuration.     

Pd-impregnated SYT/LDC composite as sulfur-tolerant anode for solid oxide fuel cells

An Sr_0.88Y_0.08TiO_3−δ (SYT)/La_0.4Ce_0.6O_1.8 (LDC) composite impregnated with Pd was evaluated as a sulfur-tolerant anode for the La_0.8Sr_0.2Ga_0.83Mg_0.17O_3−δ (LSGM)-supported cells. The impregnation of Pd into the porous SYT/LDC anode was found to significantly enhance the anode performance. With the addition of 1.5 wt.% Pd into the anode, the anodic overpotential was reduced to about half of the original value. The single cell with the Pd-impregnated SYT/LDC anode showed a maximum power density of 1006 and 577 mW cm⁻² at 850 and 800 °C in dry H₂, respectively, which was more than twice of that prior to impregnation. The Pd-impregnated composite anode exhibited good tolerance to sulfur, with essentially no decay in performance in H₂ containing up to 50 ppm H₂S.     

Optimizing the modification method of zinc-enhanced sintering of BaZr0.4Ce0.4Y0.2O3−δ-based electrolytes for application in an anode-supported protonic solid oxide fuel cell

The effects of zinc modification methods on membrane sintering, electrical conductivity of BaZr_0.4Ce_0.4Y_0.2O_3−δ (BZCY4) and the thermo-mechanical match of the BZCY4 electrolyte with anode were systematically investigated. Three modification methods are pursued, including the physical mixing of BZCY4 with a ZnO solid (method 1), introducing zinc during the solution stage of the sol–gel synthesis (method 2) and doping zinc into a perovskite lattice by synthesis of a new compound with a nominal composition of BaZr_0.4Ce_0.4Y_0.16Zn_0.04O_3−δ (method 3). Method 1 turned out to be the most effective at reducing the sintering temperature, which can mainly be attributed to a reactive sintering although ZnO doping into the BZCY4 lattice also facilitates the sintering. While all three modification methods facilitated the membrane sintering, only the electrolyte from method 3 had similar shrinkage behavior to the anode. An anode-supported thin-film BZCY4-3 electrolyte solid oxide fuel cell (SOFC) was successfully fabricated, and the fuel cell delivered an attractive performance with a peak power density of ∼307 mW cm⁻² at 700 °C.     

Stabilisation of composite LSFCO–CGO based anodes for methane oxidation in solid oxide fuel cells

A La_0.6Sr_0.4Fe_0.8Co_0.2O₃–Ce_0.8Gd_0.2O_1.9 (LSFCO–CGO) composite anode material was investigated for the direct electrochemical oxidation of methane in intermediate temperature solid oxide fuel cells (IT-SOFCs). A maximum power density of 0.17 W cm⁻² at 800 °C was obtained with a methane-fed ceria electrolyte-supported SOFC. A progressive increase of performance was recorded during 140 h operation with dry methane. The anode did not show any structure degradation after the electrochemical testing. Furthermore, no formation of carbon deposits was detected by electron microscopy and elemental analysis. Alternatively, this perovskite material showed significant chemical and structural modifications after high temperature treatment in a dry methane stream in a packed-bed reactor. It is derived that the continuous supply of mobile oxygen anions from the electrolyte to the LSFCO anode, promoted by the mixed conductivity of CGO electrolyte at 800 °C, stabilises the perovskite structure near the surface under SOFC operation and open circuit conditions.