Preparation and characterization of Pr1−xSrxFeO3 cathode material for intermediate temperature solid oxide fuel cells

A kind of cathode material of Pr_1−xSr_x FeO₃ (x = 0–0.5) for intermediate temperature solid oxide fuel cells (IT-SOFCs) was prepared by the coprecipitation method. Crystal structure, thermal expansion, electrical conductivity and electrochemical performance of the Pr_1−xSr_xFeO₃ perovskite oxide cathodes were studied by different methods. The results revealed that Pr_l−xSr_xFeO₃ exhibited similar orthorhombic structure from x = 0.1 to 0.3 and took cubic structure when x = 0.4–0.5. The unit cell volume decreased and the thermal expansion coefficient (TEC) of the materials increased as the strontium content increased. When 0 < x ≤ 0.3, the samples exhibited good thermal expansion compatibility with YSZ electrolyte. The electrical conductivity increased with the increasing of doped strontium content. When x = 0.3–0.5, the electrical conductivities were higher than 100 S cm⁻¹. The conductivity of Pr_0.8Sr_0.2FeO₃ was 78 S cm⁻¹ at 800 °C. Compared with the La_0.8Sr_0.2MnO₃ cathode, Pr_0.8Sr_0.2FeO₃ showed higher polarization current density and lower polarization resistance (0.2038 Ω cm²). The value of I₀ for Pr_0.8Sr_0.2FeO₃ at 800 °C is 123.6 mA cm⁻². It is higher than that of La_0.8Sr_0.2MnO₃. Therefore, Pr_1−xSr_xFeO₃ can be considered as a candidate cathode material for IT-SOFCs.     

PrBa0.5Sr0.5Co2O5+x as cathode material based on LSGM and GDC electrolyte for intermediate-temperature solid oxide fuel cells

PrBa_0.5Sr_0.5Co₂O_5+x (PBSC) oxides have been evaluated as cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) with Ce_0.9Gd_0.1O_1.95 (GDC) and La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM) as electrolytes. XRD results show that PBSC cathode is chemically compatible with the intermediate-temperature electrolyte materials GDC and LSGM. The maximum electrical conductivity is 1522 S cm⁻¹ at 100 °C and its value is higher than 581 S cm⁻¹ over the whole temperature range investigated. Microstructures show that the contact between PBSC and LSGM is better than that between PBSC and GDC. The area-specific resistances (ASRs) of PBSC cathode on GDC and LSGM electrolytes are 0.048 and 0.027 Ωcm² at 800 °C, respectively. The electrolyte-supported (thickness of electrolyte is 300 μm) fuel cells generate good performance with the maximum power densities of 617 mW cm⁻² on GDC electrolyte and 1021 mW cm⁻² on LSGM electrolyte at 800 °C. All results demonstrate that PBSC oxide is a very promising cathode material for application in IT-SOFCs and this cathode based on LSGM electrolyte obtained better performance than on GDC electrolyte.     

Electrochemical performance of La2Cu1−xCoxO4 cathode materials for intermediate-temperature SOFCs

K₂NiF₄-type structure oxides La₂Cu_1−xCo_xO₄ (x = 0.1, 0.2, 0.3) are synthesized and evaluated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). The materials are characterized by XRD, SEM and electrochemical impedance spectrum (EIS), respectively. The results show that no reaction occurs between La₂Cu_1−xCo_xO₄ electrode and Ce_0.9Gd_0.1O_1.95 (CGO) electrolyte at 1000 °C. The electrode forms good contact with the electrolyte after sintering at 800 °C for 4 h in air. The electrode properties of La₂Cu_1−xCo_xO₄ are studied under various temperatures and oxygen partial pressures. The optimum composition of La₂Cu_0.8Co_0.2O₄ results in 0.51 Ω cm² polarization resistance (R_p) at 700 °C in air. The rate limiting step for oxygen reduction reaction (ORR) is the charge transfer process. La₂Cu_0.8Co_0.2O₄ cathode exhibits the lowest overpotential of about 50 mV at a current density of 48 mA cm⁻² at 700 °C in air.     

Preparation and electrochemical properties of Sr-doped Nd2NiO4 cathode materials for intermediate-temperature solid oxide fuel cells

Cathode materials Nd_2 − xSr_xNiO₄ were prepared by the glycine-nitrate process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), AC impendence spectroscopy and DC polarization method, respectively. The results show that no reaction occurred between the electrode and the CGO electrolyte at 1100 °C and the electrode formed good contact with the electrolyte after being sintered at 1000 °C for 4 h. The rate-limiting step for oxygen reduction reaction on Nd_1.6Sr_0.4NiO₄ electrode changed with oxygen partial pressure and measurement temperature. The Nd_1.6Sr_0.4NiO₄ electrode gave a polarization resistance of 0.93 Ω cm² at 700 °C in air, which indicates that Nd_2 − xSr_xNiO₄ electrode is a promising cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC).     

La2−xSrxCoO4−δ (x = 0.9, 1.0, 1.1) Ruddlesden-Popper-type layered cobaltites as cathode materials for IT-SOFC application

La_2−xSr_xCoO_4−δ (x = 0.9, 1.0, 1.1) compounds with Ruddlesden-Popper K₂NiF₄-type structure have been investigated as potential cathode materials for IT-SOFC application. Materials have been prepared by citrate-nitrate combustion method. Structural evolution analysed by XRD shows a shortened Co–O–Co bond length within the perovskite layer as Sr substitution increases, while the interlayer distance at the same time increases. An oxygen stoichiometry close to 4 has been found for all compositions at room temperature. Thermal expansion coefficients have been obtained from temperature-dependent XRD analysis and show large values (>20 × 10⁻⁶ K⁻¹) compared to the currently utilized electrolyte materials. Electrochemical characterisation has been performed by means of impedance spectroscopy on symmetric cells with CGO electrolyte. Pure electrodes have a high Area Specific Resistance, probably due to limited oxygen ion diffusion. By using composite electrode (50 wt.% CGO), an Area Specific Resistance of 0.25 Ω cm² is obtained at approximately 700 °C for all the three compounds suggesting promising electrochemical properties for IT-SOFCs.     

Co-doped Sr2FeNbO6 as cathode materials for intermediate-temperature solid oxide fuel cells

Sr₂Fe_1−xCo_xNbO₆ (0.1 ≤ x ≤ 0.9) (SFCN) oxides with perovskite structure have been developed as the cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). These materials are synthesized via solid-state reaction and characterized by XRD, SEM, electrical conductivity, AC impedance spectroscopy and DC polarization measurements. The reactivity tests show that the Sr₂Fe_1−xCo_xNbO₆ electrodes are chemically compatible with the Zr_0.85Y_0.15O_1.925 (YSZ) and Ce_1.9Gd_0.1O_1.95 (CGO) electrolytes at 1200 °C, and the electrode forms a good contact with the electrolyte after sintering at 1200 °C for 12 h. The total electrical conductivity that has a considerable effect on the electrode properties is determined in a temperature range from 200 °C to 800 °C. The highest conductivity of 5.7 S cm⁻¹ is found for Sr₂Fe_0.1Co_0.9NbO₆ at 800 °C in air. The electrochemical performances of these cathode materials are studied using impedance spectroscopy at various temperatures and oxygen partial pressures. Two different kinds of reaction rate-limiting steps exist on the Sr₂Fe_0.1Co_0.9NbO₆ electrode, depending on the temperature. The Sr₂Fe_0.1Co_0.9NbO₆ electrode on CGO electrolyte exhibits a polarization resistance of 0.74 Ω cm² at 750 °C in air, which indicates that the Sr₂Fe_0.1Co_0.9NbO₆ electrode is a promising cathode material for IT-SOFCs.     

Electrode properties of Co-doped Ca2Fe2O5 as new cathode materials for intermediate-temperature SOFCs

Brownmillerite oxide Ca₂Fe_2−xCo_xO₅ (x = 0.2, 0.4, 0.6) was characterized by XRD, SEM and electrochemical impedance spectrum (EIS), respectively. Ca₂Fe_2−xCo_xO₅ has no reaction with Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte at 1100 °C for 10 h in air. The thermal expansion coefficient (TEC) of Ca₂Fe_2−xCo_xO₅ increased with increasing Co content, and the TEC value was compatible with SDC. The electrode properties of Ca₂Fe_2−xCo_xO₅ were studied under various temperatures and oxygen partial pressures. The polarization resistance (R_p) of Ca₂Fe_2−xCo_xO₅ with x = 0.2, 0.4 and 0.6 are 0.23, 0.48 and 1.05 Ω cm² at 700 °C in air, respectively. The rate-limiting step for oxygen reduction reaction was the charge transfer process. Ca₂Fe_1.8Co_0.2O₅ cathode exhibits the lowest overpotential of about 50 mV at a current density of 70 mA cm⁻² at 700 °C in air.     

Preparation and electrochemical properties of a Sm2−xSrxNiO4 cathode for an IT-SOFC

Cathodic materials Sm_2−xSr_xNiO₄ (0.5 ≤ x ≤ 1.0) for an IT-SOFC (intermediate temperature solid oxide fuel cell) were prepared by the glycine-nitrate process and characterized by XRD, SEM, ac impedance spectroscopy and dc polarization measurements. The results showed that no reaction occurred between the Sm_2−xSr_xNiO₄ electrode and the Ce_0.9Gd_0.1O_1.9 (CGO) electrolyte at 1100 °C, and the electrode formed good contact with the electrolyte after sintering at 1000 °C for 2 h. The electrochemical properties of these cathode materials were studied using impedance spectroscopy at various temperatures and oxygen partial pressures. Sm_1.0Sr_1.0NiO₄ exhibited the lowest cathodic overpotential. The area specific resistance (ASR) was 3.06 Ω cm² at 700 °C in air.     

La substituted Sr2MnO4 as a possible cathode material in SOFC

Sr_2−xLa_xMnO_4+δ (x = 0.4, 0.5, 0.6) oxides were studied as the cathode material for solid oxide fuel cells (SOFC). The reactivity tests indicated that no reaction occurred between Sr_2−xLa_xMnO_4+δ and CGO at annealing temperature of 1000 °C, and the electrode formed good contact with the electrolyte after being sintered at 1000 °C for 4 h. The total electrical conductivity, which has strong effect on the electrode properties, was determined in a temperature range from 100 to 800 °C. The maximum value of 5.7 S cm⁻¹ was found for the x = 0.6 phase at 800 °C in air. The cathode polarization and AC impedance results showed that Sr_1.4La_0.6MnO_4+δ exhibited the lowest cathode overpotential. The area specific resistance (ASR) was 0.39 Ω cm² at 800 °C in air. The charge transfer process is the rate-limiting step for oxygen reduction reaction on Sr_1.4La_0.6MnO_4+δ electrode.     

Electrochemical performance of a solid oxide fuel cell based on Ce0.8Sm0.2O2−δ electrolyte synthesized by a polymer assisted combustion method

A polyvinyl alcohol assisted combustion synthesis method was used to prepare Ce_0.8Sm_0.2O_2−δ (SDC) powders for an intermediate temperature solid oxide fuel cell (IT-SOFC). The XRD results showed that this combustion synthesis route could yield phase-pure SDC powders at a relatively low calcination temperature. A thin SDC electrolyte film with thickness control was produced by a dry pressing method at a lower sintering temperature of 1250 °C. With Sm_0.5Sr_0.5Co₃-SDC as the composite cathode, a single cell based on this thin SDC electrolyte was tested from 550 to 650 °C. The maximum power density of 936 mW cm⁻² was achieved at 650 °C using humidified hydrogen as the fuel and stationary air as the oxidant.     

Investigation on thermal, electrical, and electrochemical properties of scandium-doped Pr0.6Sr0.4(Co0.2Fe0.8)(1−x)ScxO3−δ as cathode for IT-SOFC

A systematic study and evaluation were performed on the effect of scandium doping at the B site of Pr_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (PSCF) on key material properties as cathode for intermediate temperature solid oxide fuel cells (IT-SOFC). The doped products Pr_0.6Sr_0.4(Co_0.2Fe_0.8)_(1−x)Sc_xO_3−δ (PSCFS_x, x=0.0-0.2) retained perovskite structure confirmed by X-ray diffraction, and their particles were smaller than the non-doped materials as evidenced by TEM. The electrical conductivity (EC) of PSCFS_x decreased with increasing Sc³⁺ content, but EC values were still larger than 100 S cm⁻¹ in temperature range of 300-800 °C as x ≤ 0.1. The thermal expansion coefficients (TEC) of PSCFS_x were observed to generally decrease with increasing x especially at lower temperature range of 50-600 °C. In addition, the AC impedance revealed better electrochemical performance of PSCFS_x cathode as x ≤ 0.1 than that of the undoped sample PSCF. Therefore, PSCFS_x (x ≤ 0.1) shows some potential as cathode electrode for IT-SOFC. The function of Sc³⁺ dopant was tentatively elucidated and discussed.     

Characterization and electrochemical performances of Ba2−xSrxFeO4+δ as a novel cathode material for intermediate-temperature solid oxide fuel cells

Novel cathode materials, Ba_2−xSr_xFeO_4+δ (x = 0.5, 0.6, 0.7, 0.8, 1.0), for intermediate-temperature solid oxide fuel cells on a samaria-doped ceria (SDC) electrolyte were prepared by the glycine–nitrate route and characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric (TG) analysis, electrochemical impedance spectroscopy and steady-state polarization measurement. SEM results showed that the electrode formed a good contact with the SDC electrolyte after sintering at 1000 °C for 2 h. The value of δ in Ba_1.0Sr_1.0FeO_4+δ materials was calculated from the TG results. The electrochemical impedance spectra revealed that Ba_2−xSr_xFeO_4+δ had a better electrochemical performance than that of Ln₂NiO₄ (Ln = La, Pr, Nd, Sm). In the Ba_2−xSr_xFeO_4+δ (x = 0.5, 0.6, 0.7, 0.8, 1.0) family, the composition Ba_1.0Sr_1.0FeO_4+δ exhibited the best electrochemical activity for oxygen reduction. The polarization resistance of Ba_1.0Sr_1.0FeO_4+δ on SDC electrolyte was 1.11 Ω cm² at 700 °C, which was less than half that reported for Ln₂NiO₄ at the same temperature.     

Preparation and characterization of new cobalt-free cathode Pr0.5Sr0.5Fe0.8Cu0.2O3−δ for IT-SOFC

A new cobalt-free perovskite oxide Pr_0.5Sr_0.5Fe_0.8Cu_0.2O_3−δ (PSFC) has been synthesized and evaluated as cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The chemical compatibility of PSFC with Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte has be proven by XRD, and its electrical conductivity reaches the maximum value of 264.1 S cm⁻¹ at 475 °C. Symmetrical cells with the configuration of PSFC/SDC/PSFC are used for the impedance study and the polarization resistance (Rp) of PSFC cathode is as low as 0.050 Ω cm² at 700 °C. Single cells, consisting of Ni–YSZ/YSZ/SDC/PSFC structure, are assembled and tested from 550 °C to 800 °C with wet hydrogen (∼3% H₂O) as fuel and static air as oxidant. A maximum power density of 1077 mW cm⁻² is obtained at 800 °C. All the results suggest that the cobalt-free perovskite oxide PSFC is a very promising cathode material for application in IT-SOFC.     

Electrochemical performance of (Ba0.5Sr0.5)0.9Sm0.1Co0.8Fe0.2O3−δ as an intermediate temperature solid oxide fuel cell cathode

This study presents the electrochemical performance of (Ba_0.5Sr_0.5)_0.9Sm_0.1Co_0.8Fe_0.2O_3−δ (BSSCF) as a cathode material for intermediate temperature solid oxide fuel cells (IT-SOFC). AC-impedance analyses were carried on an electrolyte supported BSSCF/Sm_0.2Ce_0.8O_1.9 (SDC)/Ag half-cell and a Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF)/SDC/Ag half-cell. In contrast to the BSCF cathode half-cell, the total resistance of the BSSCF cathode half-cell was lower, e.g., at 550 °C; the values for the BSSCF and BSCF were 1.54 and 2.33 Ω cm², respectively. The cell performance measurements were conducted on a Ni-SDC anode supported single cell using a SDC thin film as electrolyte, and BSSCF layer as cathode. The maximum power densities were 681 mW cm⁻² at 600 °C and 820 mW cm⁻² at 650 °C.     

Sr1−xPrxCo0.95Sn0.05O3−δ ceramic as a cathode material for intermediate-temperature solid oxide fuel cells

In this study, the physical properties of the Sr_1−xPr_xCo_0.95Sn_0.05O_3−δ ceramics were measured and their potential for use as a cathode material of intermediate-temperature solid oxide fuel cells (IT-SOFCs) was evaluated. A cubic phase was retained in all of the Sr_1−xPr_xCo_0.95Sn_0.05O_3−δ ceramics. Analysis of the temperature-dependent conductivity found the SrCo_0.95Sn_0.05O_3−δ and Sr_0.9Pr_0.1Co_0.95Sn_0.05O_3−δ ceramics exhibiting semiconductor-like behavior below 550 °C and metal-like behavior above the same temperature. The Sr_0.8Pr_0.2Co_0.95Sn_0.05O_3−δ and Sr_0.7Pr_0.3Co_0.95Sn_0.05O_3−δ ceramics, however, reported a metal-like conductivity in the whole temperature range. The electrical conductivities of the Sr_0.8Pr_0.2Co_0.95Sn_0.05O_3−δ ceramic at 500 °C and 700 °C read respectively 1250 S/cm and 680 S/cm, both of which were superior than those in most of the common perovskites. Single cells with a structure of NiO–Sm_0.2Ce_0.8O_2−δ (SDC)/SDC/Sr_0.8Pr_0.2Co_0.95Sn_0.05O_3−δ-SDC were built and characterized. Addition of SDC in Sr_0.8Pr_0.2Co_0.95Sn_0.05O_3−δ emerged to be a crucial factor reducing the ohmic resistance (R₀) and polarization resistance (R_P) of the cell by facilitating a better adhesion to and electrical contact with the electrolyte layer. The R₀ and R_P of the cell read respectively 0.068 Ω cm² and 0.0571 Ω cm² at 700 °C and 0.298 Ω cm² and 1.310 Ω cm² at 550 °C. With no microstructure optimization and hermetic sealing of the cells, maximum power density (MPD) and open circuit voltage (OCV) reached respectively 0.872 W/cm² and 0.77 V at 700 °C and 0.482 W/cm² and 0.86 V at 550 °C. It is evident that Sr_1−xPr_xCo_0.95Sn_0.05O_3−δ is a promising cathode material for IT-SOFCs.     

Effect of Co doping on the electrochemical properties of Sr2Fe1.5Mo0.5O6 electrode for solid oxide fuel cell

Co is doped to Sr₂Fe_1.5Mo_0.5O₆ to enhance its electrochemical activity as the cathode for intermediate-temperature solid oxide fuel cells. Pure cubic perovskites of Sr₂Fe_1.5−xCo_xMo_0.5O₆ (SF_1.5−xC_xM, x = 0, 0.5, 1) are synthesized using a glycine-nitrate combustion progress. The average thermal expansion coefficient varies from 15.8 to 19.8 × 10⁻⁶ K⁻¹. The electrical conductivity increases while its activation energy decreases with increasing Co content. X-ray photoelectron spectroscopy analysis demonstrates mixed valences of Fe, Co and Mo, suggesting small polaron hopping mechanism. Electrical conductivity relaxation (ECR) measurement shows that the surface exchange coefficient increases about two orders of magnitude when the content increases from x = 0 to x = 1.0, i.e. from 2.55 × 10⁻⁵ to 2.20 × 10⁻³ cm s⁻¹ at 750 °C. ECR also exhibits that chemical diffusion coefficient increases with Co content. Density Functional Theory calculation demonstrates that oxygen vacancy formation energy decreases with Co content, suggesting high oxygen vacancy concentration at high Co content. Impedance spectroscopy on symmetric cells consisting of SF_1.5−xC_xM electrodes and La_0.8Sr_0.2Ga_0.8Mg_0.2O_3−δ electrolytes shows that Co doping is very effective in reducing the interfacial polarization resistance, from 0.105 Ω cm² to 0.056 Ω cm² at 750 °C. These results suggest that Co doping into Sr₂Fe_1.5Mo_0.5O₆ can substantially improve its electrochemical performance.     

Low-temperature solid oxide fuel cells with La1−xSrxMnO3 as the cathodes

La_1−xSr_xMnO₃ (LSM) has been widely developed as the cathode material for high-temperature solid oxide fuel cells (SOFCs) due to its chemical and mechanical compatibilities with the electrolyte materials. However, its application to low-temperature SOFCs is limited since its electrochemical activity decreases substantially when the temperature is reduced. In this work, low-temperature SOFCs based on LSM cathodes are developed by coating nanoscale samaria-doped ceria (SDC) onto the porous electrodes to significantly increase the electrode activity of both cathodes and anodes. A peak power density of 0.46 W cm⁻² and area specific interfacial polarization resistance of 0.36 Ω cm² are achieved at 600 °C for single cells consisting of Ni-SDC anodes, LSM cathodes, and SDC electrolytes. The cell performances are comparable with those obtained with cobalt-based cathodes such as Sm_0.5Sr_0.5CoO₃, and therefore encouraging in the development of low-temperature SOFCs with high reliability and durability.     

SmBaCo2O5+x double-perovskite structure cathode material for intermediate-temperature solid-oxide fuel cells

SmBaCo₂O_5+x (SBCO), an oxide with double-perovskite structure, has been developed as a novel cathode material for intermediate-temperature solid-oxide fuel cells (IT-SOFCs). The electrical conductivity of an SBCO sample reaches 815–434 S cm⁻¹ in the temperature range 500–800 °C. XRD results show that an SBCO cathode is chemically compatible with the intermediate-temperature electrolyte materials Sm_0.2Ce_0.8O_1.9 (SDC) and La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM). The polarization resistances of an SBCO cathode on SDC and LSGM electrolytes are 0.098 and 0.054 Ω cm² at 750 °C, respectively. The maximum power densities of a single cell with an SBCO cathode on SDC and LSGM electrolytes reach 641 and 777 mW cm⁻² at 800 °C, respectively. The results of this study demonstrate that the double-perovskite structure oxide SBCO is a very promising cathode material for use in IT-SOFCs.     

Electrical conductivity,thermal expansion and electrochemical performances of Ba-doped SrCo0.9Nb0.1O3−δ cathodes for IT-SOFCs

Perovskite-type oxides Ba_xSr_1−xCo_0.9Nb_0.1O_3−δ (BSCNx, x = 0.0–0.8) were synthesized and investigated as cathodes for IT-SOFCs. Ba doping improves chemical compatibility between BSCNx oxides and Ce_0.9Gd_0.1O_1.95 (GDC) electrolyte. Effects of Ba doping on electrical conductivity, thermal expansion and electrochemical performances were systematically elucidated and discussed. Both thermal expansion coefficient (TEC) and polarization resistance (R_p) decrease with increasing Ba doping level up to x = 0.6, attain a minimum at x = 0.6 and then increase with further increasing x > 0.6. The decrease of TEC with the incorporation of Ba can be attributed to the weakened chemical expansion and the decrease of R_p with Ba is due to the increase of oxygen vacancy concentration and oxygen vacancy diffusion coefficient. With a 300 μm-thick GDC as electrolyte and BSCN0.6 as the cathode, the maximum power density of a single-cell achieves 778 mW cm⁻² at 800 °C. All these results indicate that the BSCN0.6 oxide is a promising cathode material for IT-SOFC.     

Synthesis and performance of Sr1.5LaxMnO4 as cathode materials for intermediate temperature solid oxide fuel cell

A-site non-stoichiometric materials Sr_1.5La_xMnO₄ (x = 0.35, 0.40, 0.45) are prepared via solid state reaction. The structure of these materials is determined to be tetragonal. Both the lattice volume and the thermal expansion coefficient reduce with the decrease of lanthanum content. On the contrary, the conductivity increases and the maximum value of 13.9 S cm⁻¹ is found for Sr_1.5La_0.35MnO₄ at 750 °C in air. AC impedance spectroscopy and DC polarization measurements are used to study the electrode performance. The optimum composition of Sr_1.5La_0.35MnO₄ results in 0.25 Ω cm² area specific resistance (ASR) at 750 °C in air. The oxygen partial pressure measurement indicates that the charge transfer process is the rate-limiting step of the electrode reactions.