Pr Doped Barium Cerate as the Cathode Material for Proton‐Conducting SOFCs

BaCe_0.8Pr_0.2O₃ (BCP20) and BaCe_0.6Pr_0.4O₃ (BCP40) powders are successfully synthesized through the Pechini method and used as the cathode materials for proton‐conducting solid state oxide fuel cells (SOFCs). The prepared cells consisting of the structure of a BaZr_0.1Ce_0.7Y_0.2O_3–δ (BZCY7)‐NiO anode substrate, a BZCY7 anode functional layer, a BZCY7 electrolyte membrane, and a cathode layer, are measured from 600 to 700 °C with humidified hydrogen (∼3% H₂O) as the fuel and static air as the oxidant. The electricity results show that the cell with BCP40 cathode has a higher power density, which could obtain an open‐circuit potential of 0.99 V and a maximum power density of 378 mW cm^–2 at 700 °C. The polarization resistance measured at the open‐circuit condition of BCP40 is only 0.16 Ω cm² at 700 °C, which was less than BCP20.     

A New Composite Material Ca3Co4O9+δ+La0.7Sr0.3CoO3 Developed for Intermediate‐Temperature SOFC Cathode

In this study, Ca₃Co₄O_9+δ (CCO) and La_0.7Sr_0.3CoO₃ (LSC) have been mixed as mass fraction by 1:1, to prepare novel two‐phase composites with high electrical conductivity and low thermal expansion coefficient (TEC), for potential application in intermediate‐temperature solid oxide fuel cells. The conductivity of the composite, Ca₃Co₄O_9+δ (50 wt.%) + La_0.7Sr_0.3CoO₃ (50 wt.%) (CCO‐LSC50), is improved to be three times that of single phase CCO material. And, the TEC of CCO‐LSC50 has been effectively improved to be 15.3 × 10^–6 °C^–1, about 20% lower than single phase LSC cathode, which ensures better chemical compatibility with adjacent electrolyte. As a result, compared with pure LSC and CCO cathodes, CCO‐LSC50 composite cathode improves the electrochemical performance, a percentage of 16 and 84%, respectively, according to the impedance spectra experiments. In addition, cathodic overpotential and oxygen reduction kinetics have also been researched to reveal what is driving the results. The microstructures and phases of cathodes were also compared and analyzed.     

Co‐synthesis of Sm0.5Sr0.5CoO3‐Sm0.2Ce0.8O1.9 Composite Cathode with Enhanced Electrochemical Property for Intermediate Temperature SOFCs

A 70 wt.% Sm_0.5Sr_0.5CoO₃ – 30 wt.% Sm_0.2Ce_0.8O_1.9 (SSC–SDC73) composite cathode was co‐synthesized by a facile one‐step sol–gel method, which showed lower polarization resistance and overpotential than those of physically mixed SSC–SDC73 cathode. The polarization resistance of co‐synthesized SSC–SDC73 cathode at 800 °C was as low as 0.03 Ω cm² in air. Scanning electron microscopy (SEM) images showed that the enhanced electrochemical property was mainly attributed to the smaller grains and good dispersion of SSC and SDC phases within the composite cathode, leading to an increase in three‐phase boundary length. The dependence of polarization resistance with oxygen partial pressure indicated that the rate‐limiting step for oxygen reduction reaction was the dissociation of molecular oxygen to atomic oxygen process. An anode supported fuel cell with a co‐synthesized SSC–SDC73 cathode exhibited a peak power density of 924 mW cm⁻² at 800 °C. Our results suggested that co‐synthesized composite was a promising cathode for intermediate temperature solid oxide fuel cells (IT‐SOFCs).     

The Effect of Plasma Spraying Power on La0.58Sr0.4Co0.2Fe0.8O3–δ–La0.8Sr0.2Ga0.8Mg0.2O3–δ Composite Cathode Interlayer Microstructure and Cell Performance

The metal‐supported intermediate temperature solid oxide fuel cells with a porous nickel substrate, a nano‐structured LDC (Ce_0.55La_0.45O_2–δ)–Ni composite anode, an LDC diffusion barrier layer, an LSGM (La_0.8Sr_0.2Ga_0.8Mg_0.2O_3–δ) electrolyte, an LSCF (La_0.58Sr_0.4Co_0.2Fe_0.8O_3–δ)–LSGM composite cathode interlayer and an LSCF cathode current collector are fabricated by atmospheric plasma spraying. Four different plasma spraying powers of 26, 28, 30, and 34 kW are used to fabricate the LSCF–LSGM composite cathode interlayers. Each cell with a prepared LSCF–LSGM composite cathode interlayer has been post‐heat treated at 960 °C for 2 h in air with an applied pressure of 450 g cm^–2. The current‐voltage‐power and AC impedance measurements indicate that the LSCF–LSGM composite cathode interlayer formed at 28 kW plasma spraying power has the best power performance and the smallest polarization resistance at temperatures from 600 to 800 °C. The microstructure of the LSCF–LSGM composite cathode interlayer shows to be less dense and composed of smaller dense regions as the plasma spraying power decreases to 28 kW. The durability test of the cell with an optimized LSCF–LSGM composite cathode interlayer gives a degradation rate of 1.1% kh^–1 at the 0.3 A cm^–2 constant current density and 750 °C test temperature.     

Synthesis and Electrochemical Properties of BaFe1−xCuxO3−δ Perovskite Oxide for IT‐SOFC Cathode

A series of iron‐based perovskite oxides BaFe_1−xCu_xO_3−δ (x = 0.10, 0.15, 0.20 and 0.25, abbreviated as BFC‐10, BFC‐15, BFC‐20 and BFC‐25, respectively) as cathode materials have been prepared via a combined EDTA‐citrate complexing sol‐gel method. The effects of Cu contents on the crystal structure, chemical stability, electrical conductivity, thermal expansion coefficient (TEC) and electrochemical properties of BFC‐x materials have been studied. All the BFC‐x samples exhibit the cubic phase with a space group Pm3m (221). The electrical conductivity decreases with increasing Cu content. The maximum electrical conductivity is 60.9 ± 0.9 S cm⁻¹ for BFC‐20 at 600 °C. Substitution of Fe by Cu increases the thermal expansion coefficient. The average TEC increases from 20.6 × 10⁻⁶ K⁻¹ for BFC‐10 to 23.7 × 10⁻⁶ K⁻¹ for BFC‐25 at the temperature range of 30–850 °C. Among the samples, BFC‐20 shows the best electrochemical performance. The area specific resistance (ASR) of BFC‐20 on SDC electrolyte is 0.014 Ω cm² at 800 °C. The single fuel cell with the configguration of BFC‐20/SDC/NiO‐SDC delivers the highest power density of 0.57 W cm⁻² at 800 °C. The favorable electrochemical activities can be attributed to the cubic lattice structure and the high oxygen vacancy concentration caused by Cu doping.     

Fabrication and Performance of Solid Oxide Fuel Cells with La0.2Sr0.7TiO3–δ as Anode Support and La2NiO4+δ as Cathode

A novel fabrication process for solid oxide fuel cells (SOFCs) with La_0.2Sr_0.7TiO_3–δ (LST_A–) as anode support and La₂NiO_4+δ (LNO) as cathode material, which avoids complicated impregnation process, is designed and investigated. The LST_A– anode‐supported half cells are reduced at 1,200 °C in hydrogen atmosphere. Subsequently, the LNO cathode is sintered on the YSZ electrolyte at 1,200 °C in nitrogen atmosphere and then annealed in situ at 850 °C in air. The results of XRD analysis and electrical conductivity measurement indicate that the structure and electrochemical characteristics of LNO appear similar before and after the sintering processes of the cathode. By using La_0.6Sr_0.4CoO_3–δ (LSC) as current collector, the cell with LNO cathode sintered in nitrogen atmosphere exhibits the power density at 0.7 V of 235 mW cm⁻² at 800 °C. The ohmic resistance (R_S) and polarization resistance (R_P) are 0.373 and 0.452 Ω cm², respectively. Compared to that of the cell with the LNO cathode sintered in air, the sintering processes of the cell with the LNO cathode sintered in nitrogen atmosphere can result in better electrochemical performance of the cell mainly due to the decrease in R_S. The microstructures of the cells reveal a good adhesion between each layer.     

Sr2Fe1.5Mo0.5O6–δ – Zr0.84Y0.16O2–δ Materials as Oxygen Electrodes for Solid Oxide Electrolysis Cells

The high‐temperature solid oxide electrolysis cell (SOEC) is one of the most promising devices for hydrogen mass production. To make SOEC suitable from an economical point of view, each component of the SOEC has to be optimized. At this level, the optimization of the oxygen electrode is of particular interest since it contributes to a large extent to the cell polarization resistance. The present paper is focused on an alternative oxygen electrode of Zr_0.84Y_0.16O_2–δ‐Sr₂Fe_1.5Mo_0.5O_6–δ (YSZ‐SFM). YSZ‐SFM composite oxygen electrodes were fabricated by impregnating the YSZ matrix with SFM, and the ion‐impregnated YSZ‐SFM composite oxygen electrodes showed excellent performance. For a voltage of 1.2 V, the electrolysis current was 223 mA cm⁻², 327 mA cm⁻² and 310 mA cm⁻² at 750 °C for the YSZ‐SFM10, YSZ‐SFM20, and YSZ‐SFM30 oxygen electrode, respectively. A hydrogen production rate as high as 11.46 NL h⁻¹ has been achieved for the SOEC with the YSZ‐SFM20 electrode at 750 °C. The results demonstrate that YSZ‐SFM fabricated by impregnating the YSZ matrix with SFM is a promising composite electrode for the SOEC.     

Decreasing the Polarization Resistance of BaCo0.7Fe0.2Nb0.1O3–δ Cathodes by Infiltration of Ce0.8Y0.2O2–δ

Ce_0.8Y_0.2O_2–δ (YDC) was infiltrated into a BaCo_0.7Fe_0.2Nb_0.1O_3–δ (BCFN) cathode of intermediate temperature sold oxide full cells (IT‐SOFCs) in order to decrease its cathodic polarization resistance. BCFN and YDC infiltrated BCFN electrodes were fabricated on dense Ce_0.8Gd_0.2O_2–δ (GDC) thin pellets to form symmetrical cells. The electrochemical impedance spectra of the symmetrical cells were investigated in this present study. Firstly, the thickness of BCFN electrodes was optimized, and controlled at 30 µm for further study. The effects of infiltrated YDC amount and firing temperature on electrode polarization resistance were studied. The symmetrical cells infiltrated with 30 μL YDC solution and fired at 900 °C exhibited the lowest electrode polarization resistance in all samples. It was suggested that infiltration of YDC resulted in more active sites and prolonged TPBs in electrodes, improving the surface oxygen exchange, and finally improved the electrode performance.     

Preparation of BaZr0.1Ce0.7Y0.2O3–δ Based Solid Oxide Fuel Cells with Anode Functional Layers by Tape Casting

Solid oxide fuel cells (SOFCs) based on the proton conducting BaZr_0.1Ce_0.7Y_0.2O_3–δ (BZCY) electrolyte were prepared and tested in 500–700 °C using humidified H₂ as fuel (100 cm³ min^–1 with 3% H₂O) and dry O₂ (50 cm³ min^–1) as oxidant. Thin NiO‐BZCY anode functional layers (AFL) with 0, 5, 10 and 15 wt.% carbon pore former were inserted between the NiO‐BZCY anode and BZCY electrolyte to enhance the cell performance. The anode/AFL/BZCY half cells were prepared by tape casting and co‐sintering (1,300 °C/8 h), while the Sm_0.5Sr_0.5CoO_3–δ (SSC) cathodes were prepared by thermal spray deposition. Well adhered planar SOFCs were obtained and the test results indicated that the SOFC with an AFL containing 10 wt.% pore former content showed the best performance: area specific resistance as low as 0.39 Ω cm² and peak power density as high as 0.863 W cm^–2 were obtained at 700 °C. High open circuit voltages ranging from 1.00 to 1.12 V in 700–500 °C also indicated negligible leakage of fuel gas through the electrolyte.     

Preparation and Electrochemical Properties of Sr‐doped K2NiF4‐type Cathode Material Pr1.7Sr0.3CuO4 for IT‐SOFCs

A novel K₂NiF₄‐type oxide Pr_1.7Sr_0.3CuO₄ (PSCu) is studied to obtain its electrochemical properties as the cathode for intermediate‐temperature solid oxide fuel cells (IT‐SOFCs). The PSCu cathode powder and Ce_0.8Sm_0.2O_1.9 (SDC) electrolyte powder were synthesized by sol‐gel method and glycine‐nitrate method, respectively. The crystal structure of PSCu powder and PSCu‐SDC composite powder were identified with X‐ray diffraction (XRD). It is shown that PSCu belongs to tetragonal K₂NiF₄‐type and has good chemical compatibility with SDC. The thermal expansion coefficient (TEC) of PSCu is close to that of SDC. The conductivity of PSCu tested with four‐probe method exhibits a semiconductor‐pseudometal transformation at 400–450 °C, where the maximum conductivity of 103.6 S cm⁻¹ is obtained. The polarization test indicates the area specific resistance (ASR) of PSCu decreases with increasing temperature, reaching 0.11 Ω cm² at 800 °C. The activation energy of oxygen reduction reaction during 600–800 °C is 1.19 eV. The single fuel cell performance test reveals the open circuit voltage (OCV) and resistivity of PSCu reduce with increasing temperature, but the power density ascends with increasing temperature. The maximal power density is 243 mW cm⁻² at 800 °C, and the corresponding current density and OCV are 633 mA cm⁻² and 0.77 V, respectively.     

Characterization of Sr1–xDyxCoO3–δ (x = 0.1, 0.2, 0.3) Cathode Materials for IT‐SOFCs

The cobaltate perovskites Sr_1–xDy_xCoO_3–δ (SDCO, x = 0.1, 0.2, 0.3) materials were synthesized and evaluated as cathode for La_0.8Sr_0.2Ga_0.8Mg_0.2O_3–δ solid electrolyte supported intermediate‐temperature‐solid oxide fuel cells (IT‐SOFCs). The crystal structure of Sr_0.9Dy_0.1CoO_3–δ was defined in the cubic Pm–3m space group (No. 221), Sr_0.8Dy_0.2CoO_3–δ and Sr_0.7Dy_0.3CoO_3–δ had a tetragonal I4/mmm structure. The electrical conductivities were all higher than 100 S cm^–1 in the temperature of 170–800 °C. The polarization resistance (R_p) and its activation energy (E_a) increased with increasing x. SEM analysis confirmed the porous microstructure of the SDCO cathodes and good LSGM|LDC|SDCO adherence. Sr_0.9Dy_0.1CoO_3–δ exhibited the best cathode characteristics with a maximum test‐cell power density of 841 mW cm^–2, being a high potential candidate of cathode material for IT‐SOFCs.     

Fabrication of BaZr0.1Ce0.7Y0.2O3 – δ ‐Based Proton‐Conducting Solid Oxide Fuel Cells Co‐Fired at 1,150 °C

Dense proton‐conducting BaZr_0.1Ce_0.7Y_0.2O_{3 – δ} (BZCY) electrolyte membranes were successfully fabricated on NiO–BZCY anode substrates at a low temperature of 1,150 °C via a combined co‐press and co‐firing process. To fabricate full cells, the LaSr₃Co_1.5Fe_1.5O_{10 – δ}–BZCY composite cathode layer was fixed to the electrolyte membrane by two means of one‐step co‐firing and two‐step co‐firing, respectively. The SEM results revealed that the cathode layer bonded more closely to the electrolyte membrane via the one‐step co‐firing process. Correspondingly, determined from the electrochemical impedance spectroscopy measured under open current conditions, the electrode polarisation and Ohmic resistances of the one‐step co‐fired cell were dramatically lower than the other one for its excellent interface adhesion. With humidified hydrogen (2% H₂O) as the fuel and static air as the oxidant, the maximum power density of the one‐step co‐fired single cell achieved 328 mW cm^–2 at 700 °C, showing a much better performance than that of the two‐step co‐fired single cell, which was 264 mW cm^–2 at 700 °C.     

Flame Spray Synthesis of Nanoscale La0.6Sr0.4Co0.2Fe0.8O3–δ and Ba0.5Sr0.5Co0.8Fe0.2O3–δ as Cathode Materials for Intermediate Temperature Solid Oxide Fuel Cells

Electrochemical performance and degradation was analysed by conductivity measurements as well as thermogravimetric analysis (TGA) under different atmospheres. CO₂ was identified as a critical parameter in terms of carbonate formation from Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3–δ and causes a strong increase in the material resistivity, whereas La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ is unaffected. The oxygen exchange kinetic of both compositions is affected by CO₂ containing atmospheres.     

Tailoring Electrochemical Property of Layered Perovskite Cathode by Cu‐doping for Proton‐Conducting IT‐SOFCs

Layered perovskite oxide YBaCuCoO_5+x (YBCC) was synthesized by an EDTA‐citrate complexation process and was investigated as a novel cathode for proton‐conducting intermediate temperature solid oxide fuel cells (IT‐SOFCs). The thermal expansion coefficient (TEC) of YBCC was 15.3 × 10⁻⁶ K⁻¹ and the electrical conductivity presented a semiconductor‐like behavior with the maximum value of 93.03 Scm⁻¹ at 800 °C. Based on the defect chemistry analysis, the electrical conductivity gradually decreases by the introduction of Cu into Co sites of YBaCo₂O_5+x and the conductor mechanism can transform from the metallic‐like behavior to the semiconductor‐like behavior. Thin proton‐conducting (BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3–δ) BZCYYb electrolyte and NiO–BZCYYb anode functional layer were prepared over porous anode substrates composed of NiO–BZCYYb by a one‐step dry‐pressing/co‐firing process. Laboratory‐sized quad‐layer cells of NiO‐BZCYYb / NiO‐BZCYYb / BZCYYb / YBCC with a 20 μm‐thick BZCYYb electrolyte membrane exhibited the maximum power density as high as 435 mW cm⁻² with an open‐circuit potential (OCV) of 0.99 V and a low interfacial polarization resistance of 0.151 Ωcm² at 700 °C. The experimental results have indicated that the layered perovskite oxide YBCC can be a cathode candidate for utilization as proton‐conducting IT‐SOFCs.     

Subcritical crack growth behavior of a perovskite‐structured Ba0.5Sr0.5Co0.8Fe0.2O3−δ oxygen transport membrane

This paper herein studies subcritical crack growth (SCG) behavior of a perovskite‐structured Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3?δ (BSCF) as an oxygen transport membrane material. The SCG behavior of BSCF is evaluated by a constant load method and constant stress rate method at room temperature (RT) and 800°C in air, respectively. The low crack velocity measurements are carried out by ring‐on‐ring bending tests while the high crack velocity measurements by compact tension tests. The stress rates vary approximately from 0.1012 to 101.2 MPa/min. The fracture stress increases with increasing stress rate at 800°C. The SCG parameter, n, of BSCF is determined to be 24.32 and 13.83 at RT and 800°C in air, respectively. This indicates that BSCF is more susceptible to SCG at 800°C. The strength‐probability‐time (SPT) diagram is constructed for design proposes. The stress for a lifetime of 40 years should not exceed 27.21 MPa at RT or 4.53 MPa at 800°C to assure a failure probability below 1%.     

A Layered Perovskite EuBaCo2O5+δ for Intermediate‐Temperature Solid Oxide Fuel Cell Cathode

A layered perovskite EuBaCo₂O_5+δ (EBCO) has been prepared by a solid‐state reaction, and evaluated as potential cathode for intermediate‐temperature solid oxide fuel cells. Structural characterizations are determined at room temperature using powder X‐ray diffraction and transmission electron microscopy technique. The good fits to the XRD data by Rietveld refinement method are obtained in the orthorhombic space group (Pmmm). The lower average thermal expansion coefficient, 14.9 × 10^–6 °C^–1 between 100 and 800 °C, indicates its better thermal expansion compatibility with conventional electrolytes, compared with the other cobalt‐containing cathode materials. The high electrical conductivity and large oxygen nonstoichiometry at intermediate temperatures suggest the effective charge transfer reactions including electron conduction and oxide‐ion motion in cathode. As a result, a highly electrochemical activity towards the oxygen reduction reaction is achieved between 600 and 700 °C, as evidenced by low area‐specific resistances, e.g. 0.14–0.5 Ω cm². In addition, cathodic overpotential and oxygen reduction kinetics of the EBCO cathode have also been studied.     

Degradation of La0.6Sr0.4Co0.2Fe0.8O3–δ–Ce0.8Sm0.2O1.9 Cathodes on Coated and Uncoated Porous Metal Supports

The degradation of composite LSCF‐SDC cathodes on porous 430 stainless steel supports was investigated. Two degradation mechanisms were observed: a multi‐layer oxide scale, believed to consist of Cr₂O₃ and SrCrO₄, formed at the support‐cathode interface, and small amounts of chromium were detected within the cathodes. To reduce degradation, La₂O₃ and Y₂O₃ reactive element oxide coatings were deposited on the internal pore surfaces of the metal supports. The reactive element oxide coatings reduced the amount of volatile chromium that deposited in the cathodes. As a result, the degradation rates of the cathodes on coated supports were significantly lower than the degradation rates of cathodes made on uncoated metal supports. In cathode symmetrical cells, polarization resistance degradation rates as low as 2.56 × 10⁻⁶ Ω cm² h⁻¹ were observed over 100 hours on coated metal supports, compared to an average of 1.23 × 10⁻⁴ Ω cm² h⁻¹ on uncoated supports.     

Degradation mechanism analysis of Ba0.5Sr0.5Co0.8Fe0.2O3‐δ membranes at intermediate‐low temperatures

The degradation of the permeation flux of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3‐δ membranes has typically been attributed to the phase transformation of the material at intermediate temperatures. In this study, the effect of the interfacial oxygen exchange steps was considered to give an overall view of the degradation mechanism. The changes in the interfacial exchange resistances, bulk resistance, and morphologies of the membranes were investigated via physical characterizations and a permeation model. The interfacial oxygen exchange resistances increased more quickly with time than bulk resistance. Meanwhile, BaSO₄ particles were detected on both surfaces of the membranes, and their contents reached maximum at 650°C. However, after the membrane surfaces were coated by Sm_0.5Sr_0.5CoO_3‐δ porous layers, the interfacial oxygen exchange resistances kept constant and the degradation rates were slowed down. The degradation was predominated by the increase of interfacial oxygen exchange resistances induced by the enrichment of BaSO₄ particles on membrane surfaces. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3879–3888, 2015     

Bi1.4Er0.6O3‐(La0.74Bi0.10Sr0.16) MnO3‐δ Cathodes Fabricated By Ion‐impregnating Method For IT‐SOFCs

Bi_1.4Er_0.6O₃‐(La_0.74Bi_0.10Sr_0.16)MnO_3‐δ (ESB‐LBSM) composite cathodes were fabricated by impregnating the ionic conducting ESB matrix with the LBSM electronic conducting materials. The ion‐impregnated ESB‐LBSM cathodes were beneficial for the O₂ reduction reactions, and the performance of these cathodes was investigated at temperatures below 700 °C by AC impedance spectroscopy and the results indicated that the ion‐impregnated ESB‐LBSM system had an excellent performance. At 700 °C, the lowest cathode polarisation resistance (R_p) was only 0.07 Ω cm² for the ion‐impregnated ESB‐LBSM system. For the performance testing of single cells, the maximum power density was 1.0 W cm^–2 at 700 °C for a cell with the ESB‐LBSM cathode. The results demonstrated that the unique combination of the ESB ionic conducting matrix with electronic conducting LBSM materials was a valid method to improve the cathode performance, and the ion‐impregnated ESB‐LBSM was a promising composite cathode material for the intermediate‐temperature solid oxide fuel cells.     

Ba and Gd Doping Effect in (BaxSr1–x)0.95Gd0.05Co0.8Fe0.2O3–δ (x = 0.1–0.9) Cathode on the Phase Structure and Electrochemical Performance

In this study, Ba_xSr_1–xCo_0.8Fe_0.2O_3–δ (BSCF) doped with trace of Gd were studied for phase structures and properties about thermal expansion, electrical conductivity, and electrocatalytic activity. The solution range of barium in Ba_xSr_1–xCo_0.8Fe_0.2O_3–δ can be extended to 0.1 ≤ x ≤ 0.7 after the introduction of small amount of Gd³⁺ ions (only for 5%) into the Ba/Sr‐site. The calculation results of the crystal structure and the crystal lattice energy show that the ratio of Ba/Sr and doping of Gd³⁺ lead to increase the lattice parameter and the Co/Fe ionic average valence state in B‐site. Moreover, the ratio of Ba/Sr and doping of Gd³⁺ were found to have significant impacts on the high‐temperature physical properties and electrochemical characteristics. All oxides exhibited decreases in the thermal expansion coefficient (TEC) and electrical conductivity with increasing Ba/Sr ratio. Barium insertion was found to change the area‐specific resistance (ASR) of porous (not dense) cathodes. An ASR values of 0.048, 0.072, 0.064, 0.121, and 0.059 Ω cm² under air condition were observed at 650 °C for BSGCF with x = 0.1, 0.2, 0.3, 0.5, and 0.7, respectively.