Performance of double-perovskite Sr2−xSmxMgMoO6−δ as solid-oxide fuel-cell anodes

Double-perovskite Sr_2−xSm_xMgMoO_6−δ (SSMM, 0 ≤ x ≤ 0.8) is investigated as a possible anode material for solid-oxide fuel cells on La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM) electrolytes. Single-phase SSMM samples with 0 ≤ x ≤ 0.4 are prepared. At x ≥ 0.6, a small amount of SrMoO₄ and Sm₂O₃ impurities are observed. The Mg/Mo ordering in SSMM decreases with increasing Sm content. Substitution of Sm for Sr significantly improves the electrical conductivity of SSMM. At x = 0.6, the sample yields the highest conductivity, with values reaching 16 S cm⁻¹ in H₂ at 800 °C. The maximum power densities of single cells achieved with x = 0.0, 0.2, 0.4, 0.6, and 0.8 anodes on a 300 μm-thick LSGM electrolyte are 693, 770, 860, 907, and 672 mW cm⁻², respectively, in H₂ at 850 °C. The SSMM sample with x = 0.4 is considered as the best anode candidate because of the impurity formation seen in x ≥ 0.6 samples. The x = 0.4 sample not only has a thermal-expansion coefficient closer to that of the LSGM electrolyte but also exhibits good electrochemical performance and stability in commercial city gas containing H₂S, where the maximum power density achieved is 726 mW cm⁻² at 850 °C.     

Synthesis and electrochemical properties of (Pr–Nd)1−ySryMnO3−δ and (Pr1−xNdx)0.7Sr0.3MnO3−δ as cathode materials for IT-SOFC

(Pr–Nd)_1−ySr_yMnO_3−δ (P-NSM, y = 0.2, 0.25, 0.3, 0.35) powders made from commercial Pr–Nd mixed oxide, as well as (Pr_1−xNd_x)_0.7Sr_0.3MnO_3−δ (PN3SM, x = 0, 0.5, 0.7, 1) were synthesized by a glycine-nitrate process and characterized as cathode materials for intermediate temperature solid oxide fuel cell (IT-SOFC). XRD patterns showed the powders had formed pure perovskite phase after being calcined at 800 °C for 2 h. (Pr–Nd)_0.7Sr_0.3MnO_3−δ (P-N3SM) achieved a high conductivity of 194 S cm⁻¹ at 500 °C and showed a good chemical stability against YSZ at 1150 °C. And the thermal expansion coefficient of P-N3SM/YSZ cathode was 11.1 × 10⁻⁶ K⁻¹, which well matched YSZ electrolyte film. The tubular SOFC with P-N3SM/YSZ cathode exhibited the maximum power densities of 415, 367, 327 and 282 mW cm⁻² at 850, 800, 750 and 700 °C, respectively, which indicated P-N3SM was potentially applied in SOFC for low cost.     

New SrMo1−xCrxO3−δ perovskites as anodes in solid-oxide fuel cells

Oxides of composition SrMo_1−xCr_xO_3−δ (x = 0.1, 0.2) have been prepared, characterized and tested as anode materials in single solid-oxide fuel cells, yielding output powers higher than 700 mW cm⁻² at 850 °C with pure H₂ as a fuel. All the materials are suggested to present mixed ionic–electronic conductivity (MIEC) from neutron powder diffraction (NPD) experiments, complemented with transport measurements; the presence of a Mo⁴⁺/Mo⁵⁺ mixed valence at room temperature, combined with a huge metal-like electronic conductivity, as high as 340 S cm⁻¹ at T = 50 °C for x = 0.1, could make these oxides good materials for solid-oxide fuel cells. The magnitude of the electronic conductivity decreases with increasing Cr-doping content. The reversibility of the reduction–oxidation between the oxidized Sr(Mo,Cr)O_4−δ scheelite and the reduced Sr(Mo,Cr)O₃ perovskite phases was studied by thermogravimetric analysis, which exhibit the required cyclability for fuel cells. An adequate thermal expansion coefficient, without abrupt changes, and a chemical compatibility with electrolytes make these oxides good candidates for anodes in intermediate-temperature SOFC (IT-SOFCs).     

Novel SrCo1−yNbyO3−δ cathodes for intermediate-temperature solid oxide fuel cells

Perovskite oxides SrCo_1−yNb_yO_3−δ (SCNy, y = 0.00-0.20) are investigated as potential cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) on La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM) electrolyte. Compared to the undoped SrCoO_3−δ, the Nb doping significantly improves the thermal stability and enhances the electrical conductivity of the SCNy oxides. The cubic phase of the SCNy oxides with high thermal stability can be totally obtained when the Nb doping content y ≥ 0.10. Among the investigated compositions, the SrCo_0.9Nb_0.1O_3−δ oxide exhibits the highest electrical conductivity of 461-145 S cm⁻¹ over the temperature range of 300-800 °C in air. The SCNy cathode has a good chemical compatibility with the LSGM electrolyte for temperatures up to 1050 °C for 5 h. The area specific resistances of SCNy with y = 0.10, 0.15 and 0.20 cathodes on LSGM electrolyte are 0.083, 0.099 and 0.110 Ω cm² at 700 °C, respectively. At y = 0.10, 0.15 and 0.20, the maximum power densities of a single-cell with SCNy cathodes on 300-μm thick LSGM electrolyte achieve 675, 642 and 625 mW cm⁻² at 800 °C, respectively. These results indicate that SCNy perovskite oxides with cubic phase are potential cathode materials for application in IT-SOFCs.     

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.     

Phase stability and conductivity of Ba1−ySryCe1−xYxO3−δ solid oxide fuel cell electrolyte

The structure, phase stability, and electrical properties of BaCe_1−xY_xO_3−δ (x = 0-0.4) in humidity air and CO₂ atmosphere are investigated. XRD results indicate that the BaCe_0.9Y_0.1O_3−δ sample has a symmetric cubic structure, and its phase changes to tetragonal as the Y³⁺ doping amount increases to 20 mol%. The conductivity of BaCe_1−xY_xO_3−δ increases with temperature, and it depends on the amount of yttrium doping and the atmosphere. BaCe_0.8Y_0.2O_3−δ exhibits the highest conductivity of 0.026 S cm⁻¹ at 750 °C. The activation energy for conductivity depends on yttrium doping amount and temperature. The conductivity of BaCe_0.8Y_0.2O_3−δ is 0.025 S cm⁻¹ in CO₂ atmosphere at 750 °C which is 3.8% lower than that in air due to reactions with CO₂ and BaCO₃ and the CeO₂ impure phases formed. The structure of BaCe_0.8Y_0.2O_3−δ is unstable in water and decomposes to Ba(OH)₂ and CeO₂ phases. It is found that the activation energy of samples in CO₂ atmosphere is higher than that of sample in air. Sr-doped Ba_1−ySr_yCe_0.8Y_0.2O_3−δ (y = 0-0.2) is prepared to improve the phase stability of BaCe_0.8Y_0.2O_3−δ in water. The conductivity of Ba_0.9Sr_0.1Ce_0.8Y_0.2O_3−δ is 0.023 S cm⁻¹ at 750 °C which was 11% lower than that of BaCe_0.8Y_0.2O_3−δ, however, the phase stability of Ba_0.9Sr_0.1Ce_0.8Y_0.2O_3−δ is much better than that of BaCe_0.8Y_0.2O_3−δ in water.     

SrCo1−xSbxO3−δ perovskite oxides as cathode materials in solid oxide fuel cells

The SrCo_1−xSb_xO_3−δ (x = 0.05, 0.1, 0.15 and 0.2) system was tested as possible cathode for solid oxide fuel cells (SOFCs). X-ray diffraction results show the stabilization of a tetragonal P4/mmm structure with Sb contents between x = 0.05 and x = 0.15. At x = 0.2 a phase transition takes place and the material is defined in the cubic Pm-3m space group. In comparison with the undoped hexagonal SrCoO₃ phase, the obtained compounds present high thermal stability without abrupt changes in the expansion coefficient. In addition, a great enhancement of the electrical conductivity was observed at low and intermediate temperatures (T ≤ 800 °C). The sample with x = 0.05 displays the highest conductivity value that reaches 500 S cm⁻¹ at 400 °C and is over 160 S cm⁻¹ in the usual working conditions of a cathode in SOFC (650-900 °C). Moreover, the impedance spectra of the SrCo_1−xSb_xO_3−δ/Ce_0.8Nd_0.2O_2−δ/SrCo_1−xSb_xO_3−δ (x ≥ 0.05) symmetrical cells reveal polarization resistances below 0.09 Ω cm² at 750 °C which are much smaller than that displayed by the pristine SrCoO_3−δ sample. The composition with x = 0.05 shows the lowest ASR values ranging from 0.009 to 0.23 Ω cm² in the 900-600 °C temperature interval with an activation energy of 0.82 eV.     

Pd-substituted (La,Sr)CrO3−δ-Ce0.9Gd0.1O2−δ solid oxide fuel cell anodes exhibiting regenerative behavior

Composite anodes consisting of Pd-substituted (La,Sr)CrO_3−δ mixed with 50 wt% Ce_0.9Gd_0.1O_2−δ were tested in La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ-electrolyte supported fuel cells at 800 °C with humidified H₂ fuel. Low anode polarization resistance was observed during the first several hours of operation, explained by the nucleation of Pd nano-particles on perovskite particle surfaces. Anode performance then degraded gradually before stabilizing. Redox cycling repeatedly restored the anodes to their initial peak performance, followed again by degradation. This regenerative behavior was explained by the observation that the Pd nano-particles were removed by oxidation, and then re-nucleated upon reduction.     

SrCo1−yTiyO3−δ as potential cathode materials for intermediate-temperature solid oxide fuel cells

The perovskites SrCo_1−yTi_yO_3−δ (SCTy, y = 0.00-0.20) are synthesized and assessed as potential cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) based on the La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM) electrolyte. SCTy composites with y ≥ 0.05 adopt a cubic perovskite structure with thermal stability between 30 °C and 1000 °C in air. Substitution of Ti significantly enhances the electrical conductivity of the SCTy composites relative to the undoped SrCoO_3−δ. The highest electrical conductivity of the sample with y = 0.05 varied from 430 S cm⁻¹ to 160 S cm⁻¹ between 300 °C to 800 °C in air. The area-specific resistances of the SCTy cathodes on the LSGM electrolyte gradually increase from 0.084 Ω cm² at y = 0.05 to 0.091 Ω cm² at y = 0.20 with increasing Ti content at 750 °C. Single-cells that used SCTy cathodes with y = 0.05, 0.10, 0.15, and 0.20 on a 300 μm-thick LSGM electrolyte achieve peak power densities of 793, 608, 525, and 425 mW cm⁻² at 800 °C, respectively. These novel SCTy cubic perovskites demonstrate considerable potential for application in IT-SOFC cathodes.     

La0.9−xCaxCe0.1CrO3−δ as potential anode materials for solid oxide fuel cells

LaCrO₃ doped with calcium and cerium on the A-site in the series of La_0.9−xCa_xCe_0.1CrO_3−δ (LCCC3060, LCCC4050, LCCC5040, LCCC6030 corresponding to x = 0.6, 0.5, 0.4, and 0.3 respectively), is synthesized by a sol–gel combustion method and evaluated as anode material for solid oxide fuel cells (SOFCs). Relatively higher Ca-doping on La in LaCrO₃ is found to improve both electronic and ionic conductivity. LCCC compositions have demonstrated good chemical stability in reducing atmospheres. Evaluation of the LCCC material as anode in symmetrical cell configuration shows that the highest Ca-doping composition results in the lowest activation energy and the lowest polarization resistance. La_0.8Sr_0.2Ga_0.83Mg_0.17O_3−δ (LSGM) electrolyte-supported single cells with LCCC3060 as the anode and La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF) as the cathode show that LCCC3060 can be a potential anode material for H₂, but not for CH₄.     

Structure, chemical stability and mixed proton-electron conductivity in BaZr0.9−xPrxGd0.1O3−δ

BaZr_0.9−xPr_xGd_0.1O_3−δ (x = 0.3 and 0.6) was prepared by combustion synthesis and characterised with respect to conductivity and stability in an attempt to combine the desirable properties of the end members. The polycrystalline materials exhibit a cubic or pseudo-cubic structure as determined by X-ray synchrotron radiation and transmission electron microscopy. The chemical stability of the compositions is strongly dependent on the praseodymium content, the materials with more Pr present lower stability. Electron holes dominate the conductivity under oxidising atmospheres in BaZr_0.3Pr_0.6Gd_0.1O_3−δ, while BaZr_0.6Pr_0.3Gd_0.1O_3−δ exhibits a mixed electron hole-proton conducting behaviour. Substitution of Zr by Pr in acceptor-doped BaZrO₃ decreases the sintering temperature and increases the grain growth rate.     

Electrical performance and structural analysis of La1−xBaxGa0.8Mg0.2O3−δ solid electrolyte

The aim of this study was to develop La_1−xBa_xGa_1−yMg_yO_3−δ (x = 0.03–0.1, y = 0.2–0.25) (LBGM) electrolytes for intermediate-temperature solid-oxide fuel cells (SOFCs); these electrolytes were synthesized via a solid-state reaction. In the study, the La_1−xBa_xGa_1−yMg_yO_3−δ samples crystallized in an orthorhombic (Imma) structure, and a BaLaGa₃O₇ phase was detected for x ≥ 0.08 at a fixed y = 0.2. The solubility limit of the Ba ions increased with an increase in the Mg content in the matrix. Two active Raman bands at ca. 677 and 739 cm⁻¹ were observed, and they were attributed to the oxygen vacancies. The La_0.95Ba_0.05Ga_0.75Mg_0.25O_3−δ sample had a higher conductivity ca. 0.1 S/cm at 800 °C, and an activation energy of ca. 0.83–1.27 eV at 500–800 °C. The thermal expansion coefficient (TEC) of the LBGM samples at 200–800 °C was in the range of 10 × 10⁻⁶ to 14 × 10⁻⁶/°C.     

The effect of doping in the electrochemical performance of (Ln1−xMx)FeO3−δ SOFC cathodes

A family of iron perovskites with the general formula AFeO_3−δ (A = Ln_1−xM_x; Ln = La, Nd and/or Pr; M = Sr or/and Ca) has been prepared keeping fixed the A cation radius 〈r_A〉 and cation size mismatch to isolate the effect of divalent dopant concentration from the A-cation steric effects. The electrochemical behaviour of these compounds for their application as SOFC cathodes was evaluated by using I-V curve measurements and ac impedance spectroscopy over three electrodes electrolyte supported cells processed under identical conditions. In contrast with the bulk behaviour, trends are more difficult to observe due to microstructural effects, but results seem to indicate that the doping level, x, does not influence in a significant way the electrochemical performance of iron perovskites with identical 〈r_A〉 and σ²(r_A).     

Scandium-doped PrBaCo2−xScxO6−δ oxides as cathode material for intermediate-temperature solid oxide fuel cells

Scandium-doped PrBaCo_2−xSc_xO_6−δ(PBCS-x, x = 0.00–1.00) oxides have been evaluated as cathode materials of intermediate-temperature solid oxide fuel cells (IT-SOFCs) with respect to phase structure, oxygen content, thermal expansion behavior and electrical and electrochemical properties. The XRD results have demonstrated a phase transition in PBCS-x due to Sc³⁺ doping from tetragonal double-layered perovskite structure at x = 0.00–0.20, bi-phase mixtures at x = 0.30–0.40, to cubic perovskite structure at x = 0.50–0.90. The oxygen contents (6-δ) and average valences of cobalt ions in PBCS-x decrease with the higher Sc³⁺ content and increasing temperatures in air. Sc³⁺ doping has also led to decreased thermal expansion coefficients, lowered electrical conductivities and enhanced electrochemical reaction activities for PBCS-x characterized by decreased area-specific resistances (ASRs) and smaller reaction activation energies. Among the studied samples, the PBCS-0.50 oxide with Sc³⁺-doping content of x = 0.50 exhibits the best electrochemical performance on Ce_0.9Gd_0.1O_1.95 electrolyte. Its ASR values range from 0.123 Ω cm² at 600 °C to 0.022 Ω cm² at 750 °C, which are much lower than the related cathode materials. These results have demonstrated that the PBCS-0.50 oxide is a promising cathode material for IT-SOFCs.     

A cobalt-free Sm0.5Sr0.5FeO3−δ–BaZr0.1Ce0.7Y0.2O3−δ composite cathode for proton-conducting solid oxide fuel cells

A cobalt-free Sm_0.5Sr_0.5FeO_3−δ–BaZr_0.1Ce_0.7Y_0.2O_3−δ (SSF–BZCY) was developed as a composite cathode material for proton-conducting solid oxide fuel cells (H-SOFC) based on proton-conducting electrolyte of stable BZCY. The button cells of Ni-BZCY/BZCY/SSF–BZCY were fabricated and tested from 550 to 700 °C with humidified H₂ (～3% H₂O) as a fuel and ambient oxygen as oxidant. An open-circuit potential of 1.024 V, maximum power density of 341 mW cm⁻², and a low electrode polarization resistance of 0.1 Ω cm² were achieved at 700 °C. The experimental results indicated that the SSF–BZCY composite cathode is a good candidate for cathode material.     

Synthesis and properties of La0.6Sr0.4CoO3−δ nanopowder

Uniform nanopowders of La_0.6Sr_0.4CoO_3−δ (LSC) were synthesized by the combined citrate–EDTA method. The precursor solution was prepared from nitrates of the constituent metal ion, citric acid and EDTA with a pH value controlled by ammonia. The obtained product was characterized by TG/DTA, XRD, SEM, and BET measurements. The single perovskite phase could form completely after sintering at the temperature of 900 °C. There was no significant effect of the precursor solution pH value on the perovskite phase formation temperature; however, LSC powders prepared from the precursors with different pH values showed specific shapes. The morphology of La_0.6Sr_0.4CoO_3−δ powder was also optimized with proper surfactant addition. The sintered La_0.6Sr_0.4CoO_3−δ bulk samples exhibited an electrical conductivity of 1867 S cm⁻¹ in air at 800 °C. The impedance spectra of a symmetric LSC cathode on a GDC electrolyte substrate were measured and polarization resistance (R_p) values of 0.17 Ω cm² at 700 °C and 0.07 Ω cm² at 750 °C in air were obtained.     

Electrode redox properties of Ba1−xLaxFeO3−δ as cobalt free cathode materials for intermediate-temperature SOFCs

Cobalt-free perovskite oxides Ba_1−xLa_xFeO_3−δ (x = 0.1–0.4) were synthesized by glycine-nitrate combustion method and investigated as a candidate cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs). Cubic perovskite structure was obtained when 10–20 mol% La was substituted at Ba-site in Ba_1−xLa_xFeO_3−δ, and the crystal structure was transformed from cubic structure into orthorhombic one at x ≥ 0.2 with an addition of lanthanum doping. The thermal expansion coefficients of Ba_1−xLa_xFeO_3−δ oxides decreased gradually with La content due to increasing electrostatic attraction forces. A gradual increase existed in electrical conductivity tendency with La content due to disproportionation of Fe³⁺ and the larger extent of electron clouds. The electrode redox performance was investigated by electrochemical impedance spectroscopy. Among Ba_1−xLa_xFeO_3−δ series oxides, Ba_0.9La_0.1FeO_3−δ exhibited the best electrochemical performance. The area specific resistance (ASR) of Ba_0.9La_0.1FeO_3−δ was 0.079 Ω cm², 0.37 Ω cm², and 2.15 Ω cm² at 800, 700 and 600 °C under open circuit potential. To investigate electrochemical performances after cathodic polarization, bias potentials were employed on Ba_1−xLa_xFeO_3−δ cathode at 650–800 °C. The results demonstrated the potential applications for Ba_0.9La_0.1FeO_3−δ as cathode materials for IT-SOFCs as a tradeoff between electrochemical and thermal expansion performance.     

A simple and effective process for Sr0.995Ce0.95Y0.05O3−δ and BaCe0.9Nd0.1O3−δ solid electrolyte ceramics

A simple and effective reaction-sintering process for Sr_0.995Ce_0.95Y_0.05O_3−δ and BaCe_0.9Nd_0.1O_3−δ solid electrolyte ceramics was investigated in this study. Without any calcination involved, the mixture of raw materials was pressed and sintered directly. Sr_0.995Ce_0.95Y_0.05O_3−δ ceramics with 98.4% of the theoretical density were obtained after being sintered at 1350 °C for 2 h. A total conductivity 1.42 mS cm⁻¹ at 900 °C could be obtained in Sr_0.995Ce_0.95Y_0.05O_3−δ sintered at 1500 °C for 4 h. BaCe_0.9Nd_0.1O_3−δ ceramics with 91.7% of the theoretical density were obtained after being sintered at 1500 °C for 2 h. A total conductivity 11.54 mS cm⁻¹ at 900 °C could be obtained in BaCe_0.9Nd_0.1O_3−δ sintered at 1350 °C for 6 h. The reaction-sintering process has proven a simple and effective method to obtain useful Sr_0.995Ce_0.95Y_0.05O_3−δ and BaCe_0.9Nd_0.1O_3−δ ceramics for solid electrolyte applications in solid oxide fuel cells.     

High performance proton-conducting solid oxide fuel cells with a stable Sm0.5Sr0.5Co3−δ-Ce0.8Sm0.2O2−δ composite cathode

A Sm_0.5Sr_0.5CoO_3−δ-Ce_0.8Sm_0.2O_2−δ (SSC-SDC) composite is employed as a cathode for proton-conducting solid oxide fuel cells (H-SOFCs). BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY) is used as the electrolyte, and the system exhibits a relatively high performance. An extremely low electrode polarization resistance of 0.066 Ω cm² is achieved at 700 °C. The maximum power densities are: 665, 504, 344, 214, and 118 mW cm⁻² at 700, 650, 600, 550, and 500 °C, respectively. Moreover, the SSC-SDC cathode shows an essentially stable performance for 25 h at 600 °C with a constant output voltage of 0.5 V. This excellent performance implies that SSC-SDC, which is a typical cathode material for SOFCs based on oxide ionic conductor, is also a promising alternative cathode for H-SOFCs.     

Cobalt-site cerium doped SmxSr1−xCoO3−δ oxides as potential cathode materials for solid-oxide fuel cells

A series of new oxides with the nominal composition of Sm_xSr_1−xCo_1−yCe_yO_3−δ (x = 0.1, 0.3, 0.5; y = 0.05, 0.1) were synthesized. Their crystal structure, morphology, thermal expansion and electrochemical properties were systematically investigated. A phase-pure perovskite-type Sm_0.3Sr_0.7Co_0.95Ce_0.05O_3−δ oxide is obtained, while the other samples are actually composed of B-site cation deficient Sm_xSr_1−xCo_1−yCe_y−zO_3−δ (0 < z < y) and CeO₂ mixed phases. These two-phase samples exhibit larger oxygen nonstoichiometry (δ) and higher average thermal expansion coefficients (TEC), while the single-phase Sm_0.3Sr_0.7Co_0.95Ce_0.05O_3−δ oxide shows a smaller δ and a lower TEC as compared to Sm_0.3Sr_0.7CoO_3−δ. The introduction of cerium also effectively suppresses the chemical expansion and the growth of grain particles. The smaller grain size is beneficial in improving the electrode surface area. In addition, the electrical conductivities of Ce-doped Sm_xSr_1−xCoO_3−δ are all higher than 200 S cm⁻¹. EIS tests demonstrate that partially substituting Co with Ce and the B-site deficiency improve the cathode performance. Sm_0.3Sr_0.7Co_0.95Ce_0.05O_3−δ shows the lowest area specific resistance (ASR) among the others. Through proper cobalt-site cerium doping, the Sm_xSr_1−xCoO_3−δ related oxides could be developed into promising cathode materials for SOFC.