Tuning Ba0.5Sr0.5Co0.8Fe0.2O3-δ cathode to high stability and activity via Ce-doping for ceramic fuel cells

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) fuel-cell cathode stands out because of its ultrahigh ionic conductivity and excellent electrocatalytic activity, but it is still very subject to instability. Here, a new strategy of Ce doping is proposed to boost the stability and activity of the BSCF cathode. A one-pot combustion method is employed to synthesize (Ba_0.5Sr_0.5)_1–xCe_xCo_0.8Fe_0.2O_3-δ (x=0–0.2) cathodes. Both BSCF and (Ba_0.5Sr_0.5)_0.9Ce_0.1Co_0.8Fe_0.2O_3-δ have a cubic perovskite structure. (Ba_0.5Sr_0.5)_0.8Ce_0.2Co_0.8Fe_0.2O_3-δ shows two phases of cubic perovskite and fluorite ceria. Proper Ce doping can boost the electrical conductivity of BSCF, and can dramatically reduce the polarization resistance of BSCF cathode. Ce doping significantly improved BSCF cathode long-term stability by 160 h. Moreover, ten-percent Ce doping in BSCF highly improves single-cell output performance from 516.33 mW cm^?2 to 629.75 mW cm^?2 at 750 °C. The results reveal that Ce doping as a potential strategy for enhancing the stability and activity of BSCF cathode is promising.     

A novel lanthanum strontium cobalt iron composite membrane synthesised through beneficial phase reaction for oxygen separation

Composite ceramic membrane is one of the most attractive concepts which combines the advantages of different phases into a single membrane matrix. Recently, the reported significant increased oxygen surface kinetics on the Perovskite/Ruddlesden-Popper composite system because of the formation of novel and fast oxygen transport paths along the hetero-interface has been implanted into the oxygen permeation membrane system. In this work, a novel La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ-(La_0.5Sr_0.5)₂CoO_4+δ (LSCF-LSC) composite hollow fiber membrane is synthesized with oxygen permeation flux of 4.52 mL min⁻¹ cm⁻² at 950 °C. It presents round 4 times and 2.3 times of that of the single LSCF membrane and LSC-coated LSCF membrane at 900 °C. For better comparison, (La_0.576Sr_0.424)_1.136Co_0.3Fe_0.7O_3-δ (LSCF-new) is prepared based on the composition of LSCF-LSC composite. The enhanced oxygen permeability was further investigated through electrochemical impedance spectroscopy (EIS) measurements. We also confirm that LSCF-LSC shows significantly lower area specific resistance (ASRs) for LSCF-LSC|Ce_0.8Sm_0.2O_1.9 (SDC)|LSCF-LSC symmetrical cell relative to other symmetrical cells. This novel LSCF-LSC composite membrane also presents high CO₂ tolerance, with stable oxygen permeation fluxes round 2.6 mL min⁻¹ cm⁻² at 900 °C for 100 h.     

High permittivitty (La0.5Sr0.5)CoO3-δ-La(Co0.5Ti0.5)O3-δ ceramic composites for next generation MIM capacitors

Dielectrics with low capacitance loss and high relative permittivity are of high demand in metal-insulator-metal (MIM) capacitor that offers higher level of miniaturization, flexibility and performance. In order to achieve high relative permittivity, developing ceramics with metallic inclusions, has been suggested as a working strategy. But such materials may have high leakage currents and often lack thermal stability. With the objective for MIM applications, a series of (1-x)La(Co_0.5Ti_0.5)O_3-δ-x(La_0.5Sr_0.5)CoO_3-δ ceramics [x?=?0.0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 1] were developed. The crystal structure analysis was performed for La(Co_0.5Ti_0.5)O_3-δ, (La_0.5Sr_0.5)CoO_3-δ and 0.5La(Co_0.5Ti_0.5)O_3-δ-0.5(La_0.5Sr_0.5)CoO_3-δ using X-pert High Score Plus. The composite with x?=?0.5 in (1-x)La(Co_0.5Ti_0.5)O_3-δ-x(La_0.5Sr_0.5)CoO₃-_δ showed a maximum relative permittivity of 4920 with promising ac electrical resistivity (～202?Ω-cm). The thermal, electrical and dielectric properties together suggest that the composition 0.5La(Co_0.5Ti_0.5)O_3-δ-0.5(La_0.5Sr_0.5)CoO₃-_δ is suitable for MIM capacitors in DRAM and RF devices.     

Synthesis and characterization of Ca3-xLaxCo4-yCuyO9+δ cathodes for intermediate temperature solid oxide fuel cells

The calcium cobaltite Ca_3-xLa_xCo_4-yCu_yO_9+δ with x and y = 0 and 0.1 were synthesized and the electrical, thermal, and catalytic behaviors for the oxygen reduction reaction (ORR) for use as air electrodes in intermediate-temperature solid oxide fuel cells (IT-SOFCs) were evaluated. X?ray diffraction confirms the Ca_3-xLa_xCo_4-yCu_yO_9+δ samples were crystallized in a monoclinic structure and scanning electron microscopic image shows lamella-like grain formation. Introduction of dopants decreases slightly the loss of lattice oxygen and thermal expansion co-efficient. The Ca_3-xLa_xCo_4-yCu_yO_9+δ samples exhibit good phase stability for long-term operation, thermal expansion, and chemical compatibility with the Ce_0.8Gd_0.2O_2-δ electrolyte. Among the studied samples, Ca_2.9La_0.1Co₄O_9+δ shows a maximum conductivity of 176 Scm^?1 at 800 °C. Although the doped samples exhibit a higher total electrical conductivity, an improved symmetrical cell performance is displayed by the undoped sample. Comparing the sintering temperatures, the composite cathode Ca₃Co₄O_9+δ + Ce_0.8Gd_0.2O_2-δ sintered at 800 °C exhibit the lowest area specific resistance of 0.154 Ω cm² at 800 °C in air. In the Ca_3-xLa_xCo_4-yCu_yO_9+δ + GDC composite cathodes, the charge-transfer process at high frequencies presents a major rate limiting step for the oxygen reduction reaction.     

Consequences of lead incorporation in fluorite structured thoria

The outcome of incorporation of lead in fluorite structured thoria in terms of structure and electrical properties have been discussed. Samples with stoichiometries Th_1-xPb_xO_2-δ (x?=?0.00 to 0.70) have been synthesized by a solution combustion route and characterized extensively. The maximum solubility limit of lead in fluorite structured thoria was deduced to be 50?mol % from powder X-ray diffraction and Raman spectral measurements. The micro strain of the fluorite lattice increased with the introduction of lead. X-ray photoelectron spectroscopy analysis of Th_0·50Pb_0·50O_2-δ showed the existence of lead in both +2 and + 4 oxidation states. The ratio between the intensities of peaks located at 548 cm^?1 and T_2g mode (I₅₄₈/I_T2g) was found to increase with increase in lead content in the samples and quantified utilizing grain size and half width half maxima. The defect concentrations in these samples have been estimated in the range 10¹⁷-10²⁰?cm^?3. The direct band gap values shifted from the insulating regime (for thoria) to semiconducting regime (3.4–2?eV) for lead substituted samples. From the frequency dependent conductivity plots of Th_1-xPb_xO_2-δ samples over temperature range (323–773?K), highest conductivity of 1.62?×?10^?6 Scm^?1 was obtained for Th_0·50Pb_0·50O_2-δ at 773?K. From the impedance measurements of lead substituted thoria under flowing oxygen (1?atm), thermal motion of oxygen ion vacancies was found responsible for the observed conductivity.     

Oxygen permeability and structural stability of a novel tantalum‐doped perovskite BaCo0.7Fe0.2Ta0.1O3−δ

Dense BaCo_0.7Fe_0.2Ta_0.1O_3?δ (BCFT) perovskite membranes were successfully synthesized by a simple solid state reaction. In situ high‐temperature X‐ray diffraction indicated the good structure stability and phase reversibility of BCFT at high temperatures. The thermal expansion coefficient (TEC) of BCFT was determined to amount 1.02 × 10^?5 K^?1, which is smaller than those of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3?δ (BSCF) (1.15 × 10^?5 K^?1), SrCo_0.8Fe_0.2O_3?δ (SCF) (1.79 × 10^?5 K^?1), and BaCo_0.4Fe_0.4Zr_0.2O_3?δ (BCFZ) (1.03 × 10^?5 K^?1). It can be seen that the introduction of Ta ions into the perovskite framework could effectively lower the TEC. Thickness dependence studies of oxygen permeation through the BCFT membrane indicated that the oxygen permeation process was controlled by bulk diffusion. A membrane reactor made from BCFT was successfully operated for the partial oxidation of methane to syngas at 900°C for 400 h without failure and with the relatively high, stable oxygen permeation flux of about 16.8 ml/min cm². © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Single- and dual-phase capillary membranes prepared through plastic extrusion method for oxygen permeation

Two capillary membranes, single-phase Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) and dual-phase 75 wt% Ce_0.85Sm_0.15O_1.925 - 25 wt% Sm_0.6Sr_0.4Cr_0.3Fe_0.7O_3-δ (SDC-SSCF), with dense cross section, were successfully prepared through the plastic extrusion method. The dual-phase capillary membrane shows higher strength compared to the BSCF counterpart, while the two capillary membranes exhibit much higher fracture strength than those of hollow fiber membranes. The oxygen permeation fluxes of both membranes increase with the increase of temperature and flow rate of sweep gas at the ambient pressure, and can be greatly improved by applying high pressures to the feed side. The oxygen permeation flux of BSCF capillary membrane is up to 19.5 mL cm^?2 min^?1 when 0.5 MPa air was applied to the feed side at 900 °C, which is one order of magnitude higher than that of SDC-SSCF capillary membrane. Thus, both capillary membranes have their own advantages and meet applications under different operation conditions.     

Synthesis and characterization of Mo-doped LiNi0.5Co0.2Mn0.3O2 cathode materials prepared by a hydrothermal process

The lithiated metal oxide precursor with α-NaFeO₂ structure and low crystallinity prepared by a hydrothermal process is verified to be Li-Ni-Co-Mn-Mo composite oxide. The layered Li(Ni_0.5Co_0.2Mn_0.3)_1-xMo_xO₂ (x=0, 0.005, 0.01 and 0.02) cathode material with high crystallinity for lithium ion batteries (LIBs) is obtained from the lithiated metal oxide precursor by heat treatment. The results of SEM and EDS mapping characterization indicate that the molybdenum is distributed in the materials homogeneously. The effects of molybdenum on the structure, morphology and electrochemical performances of the LiNi_0.5Co_0.2Mn_0.3O₂ are extensively studied. According to the results of electrochemical characterizations, the Li(Ni_0.5Co_0.2Mn_0.3)_0.99Mo_0.01O₂ sample exhibits the best discharge cycling performance with capacity retention of 97.0% after 50 cycles, and an excellent rate performance of 125.5 mAh·g⁻¹ at 8C rate. The Li(Ni_0.5Co_0.2Mn_0.3)_0.99Mo_0.01O₂ sample also shows a lower potential polarization, smaller impedance parameters and a larger Li⁺ diffusion by CV and EIS analyses.     

Creep behavior of porous La0.6Sr0.4Co0.2Fe0.8O3-δ substrate material for oxygen separation application

Advanced oxygen transport membrane designs consist of a thin functional layer supported by a porous substrate material that carries mechanical loads. Creep deformation behavior is to be assessed to warrant a long-term reliable operation at elevated temperatures. Aiming towards an asymmetric composite, the current study reports and compares the creep behavior of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) perovskite porous substrate material with different porosity and pore structures in air for a temperature range of 800–1000?°C. A porosity and pore structure independent average stress exponent and activation energy are derived from the deformation data, both being representative for the LSCF material. To investigate the structural stability of the dense layer in an asymmetric membrane, sandwich samples of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) and La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) with porous substrate and dense layers on both side were tested by three-point bending with respect to creep rupture behavior of the dense layer. Creep rupture cracks were observed in the tensile surface of BSCF, but not in the case of LSCF.     

Phase interaction and oxygen transport in oxide composite materials

Abstract

The oxygen permeability of oxide composite membranes containing similar volume fractions of the components, including (La_0.9 Sr_0.1)_0.98 Ga_0.8 Mg_0.2 O_3-δ(LSGM)–La_0.8 Sr_0.2Fe_0.8Co_0.2O_3-δ (LSFC), LSGM–La₂Ni_0.8Cu_0.2O_4+δ (LNC), SrCoO_3-δ–Sr₂Fe₃O_{6.5 ±δ}, Ce_0.8Gd_0.2O_2-δ (CGO)–LSFC and CGO–La_0.7Sr_0.3MnO_3-δ (LSM), was studied at 973–1223 K. In most cases, oxygen transport is substantially affected by component interaction, decreasing ionic conductivity due to cation interdiffusion, and formation of intermediate phases and/or blocking layers at grain boundaries. This interaction is maximised in systems where the phase components have similar structure and thus may form continuous solid solutions, for example LSGM–LSFC, or intermediate compounds such as Roddlesden–Popper phases in LSGM–LNC composites. The results show that, in addition to knowledge of the transport properties and volume fractions of percolating phases, analysis of ionic conduction in oxide composite materials requires assessment of phase interaction and grain boundary processes.     

Structure and thermal properties of La0.6Sr0.4Co0.2Fe0.8O3−δ-SDC carbonate composite cathodes for intermediate- to low-temperature solid oxide fuel cells

The structure and thermal properties of La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ-SDC carbonate (LSCF-SDC carbonate) composite cathodes were investigated with respect to the calcination temperatures and the weight content of the samarium-doped ceria (SDC) carbonate electrolyte. The composite cathode powder has been prepared from La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ and SDC carbonate powders using the high-energy ball milling technique in air at room temperature. Different powder mixtures at 30 wt%, 40 wt% and 50 wt% of SDC carbonate were calcined at 750-900 °C. The findings indicated that the structure and thermal properties of the composite cathodes were responsive to the calcination temperature and the content of SDC carbonate. The absence of any new phases as confirmed via XRD analysis demonstrated the excellent compatibility between the cathode and electrolyte materials. The particle size of the composite cathode powder was ∼0.3-0.9 μm having a surface area of 4-15 m² g⁻¹. SEM investigation revealed the presence of large particles in the resultant powders resulting from the increased calcination temperature. The composite cathode containing 50 wt% SDC carbonate was found to exhibit the best thermal expansion compatibility with the electrolyte.     

Ba1−xPrxCo1−yFeyO3−δ as cathode materials for low temperature solid oxide fuel cells

Ba_1−xPr_xCo_1−yFe_yO_3−δ (BPCF) perovskite oxides have been synthesized and investigated as cathode materials for low temperature solid oxide fuel cells (LT-SOFCs). Compared with those of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF) and Sm_0.5Sr_0.5CoO₃ (SSCo) cathode materials, BPCF has a lower polarization resistance at decreased temperatures. In particular, Ba_0.5Pr_0.5Co_0.8Fe_0.2O_3−δ showed the lowest polarization loss among the different compositions as a cathode material for LT-SOFCs. The area specific resistance (ASR) of Ba_0.5Pr_0.5Co_0.8Fe_0.2O_3−δ as a cathode material is 0.70 and 0.185 Ω cm² at 500 °C and 550 °C, respectively. The maximum power density of the cell BPCF/SDC/Ni-SDC with humidified hydrogen as fuel and air as oxidant reaches 860 mW cm⁻² at 650 °C.     

Preparation of thin electrolyte film via dry pressing/heating /quenching/calcining for electrolyte-supported SOFCs

The development of technologies used to prepare thin electrolyte films will stimulate the application of electrolyte-supported SOFCs since thin electrolyte films typically have low ohmic resistances and good electrochemical performance. This paper presents a novel method for the preparation of thin electrolyte films for yttria-stabilized zirconia (YSZ)-supported solid oxide fuel cells (SOFCs) via dry pressing/heating/quenching/calcining. The thicknesses of the as-prepared YSZ films were as low as 78?μm, which is significantly thinner than those prepared using a traditional method (greater than 200?μm) via dry pressing/calcining/polishing. More importantly, the preparation process was quicker. Using this novel method, a YSZ-supported cell with a configuration of (La_0.6Sr_0.4)_0.9Co_0.8Fe_0.2O_3-δ (LSCF)–Ce_0.8Sm_0.2O_2-δ(SDC)/SDC/YSZ/SDC/Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3?δ(BSCF)–SDC was fabricated and tested. The results showed promising electrochemical performance and a peak power density of 0.64?W?cm^?2 at 850?°C was obtained, which was much higher than the cell fabricated using the traditional method (0.29?W?cm^?2). The ohmic resistance (R_O) at 850?°C is 0.19?Ω?cm², which is much lower than that of the cell fabricated using the traditional method (0.33?Ω?cm²) at an identical temperature. The modified method described in this work is shown to be a promising technique to prepare thin electrolyte films for high-performance, electrolyte-supported SOFCs.     

La0.5Sr0.5Fe0.9Mo0.1O3-δ-CeO2 anode catalyst for Co-Producing electricity and ethylene from ethane in proton-conducting solid oxide fuel cells

A La_0.5Sr_0.5Fe_0.9Mo_0.1O_3-δ-CeO₂ (LSFM-CeO₂) composite was prepared by impregnating CeO₂ into porous La_0.5Sr_0.5Fe_0.9Mo_0.1O_3-δ perovskite and was used as an anode material for proton-conducting solid oxide fuel cells (SOFCs). The maximum power densities of the BaZr_0.1Ce_0.7Y_0.2O_3-δ (BZCY) electrolyte-supported single cell with LSFM-CeO₂ as the anode reached 291 mW cm^?2 and 190 mW cm^?2 in hydrogen and ethane fuel at 750 °C, respectively, which are significantly higher than those of a single cell with only LSFM as the anode. Additionally, the ethylene selectivity and ethylene yield from ethane for the fuel cell at 750 °C were as high as 93.4% and 37.1%, respectively. The single cell also showed negligible degradation in performance and no carbon deposition during continuous operation for 22 h under an ethane fuel atmosphere. The improved electrochemical performance due to the impregnation of CeO₂ can be a result of enhanced electronic and ionic conductivity, abundant active sites, and a broad three-phase interface in the resultant composite anode. The LSFM-CeO₂ composite is believed to be a promising anode material for proton-conducting SOFCs for co-producing electricity and high-value chemicals from hydrocarbon fuels.     

Effect of optimal GDC loading on long-term stability of La0.8Sr0.2Co0.2Fe0.8O3-δ/Gd0.2Ce0.8O1.9 composite cathodes

Three types of La_0.8Sr_0.2Co_0.2Fe_0.8O_3-δ/Gd_0.2Ce_0.8O_1.9 (LSCF/GDC) composite cathodes with different optimal GDC loading are fabricated through electrospinning, screen printing and solution infiltration method. Constant current polarization with current density of 100 mA cm^?2 at 750°C is applied to test the stability of LSCF/GDC composite cathodes. After constant current polarization for 144 h, the polarization resistance (R_p) of 280 nm-nanofiber skeletal LSCF/GDC composite cathode after pore-forming exhibits the minimum increase, from 0.062 Ω cm² to 0.098 Ω cm². Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) results show that the microstructure and surface chemical composition of the cathode maintain stable during the constant current polarization. Combined with the X-ray diffraction (XRD) result, a relationship among GDC loading, stress, Sr surface segregation and long-term stability is established.     

Facile synthesis and electrochemical performance of nitrogen-doped porous hollow coaxial carbon fiber/Co3O4 composite

Economy and efficiency are two important indexes of lithium-ion batteries (LIBs) materials. In this work, nitrogen doped hollow porous coaxial carbon fiber/Co₃O₄ composite (N-PHCCF/Co₃O₄) is fabricated using the fibers of waste bamboo leaves as the template and carbon resource by soaking and thermal treatment, respectively. The N-PHCCF/Co₃O₄ exhibits an outstanding electrochemical performance as anode material for lithium ion batteries, due to the nitrogen doping, coaxial configuration and porous structure. Specifically, it delivers a high discharge reversible specific capacity of 887 mA h g^?1 after 100 cycles at the current density of 100 mA g^?1. Furthermore a high capability of 415 mA h g^?1 even at 1 A g^?1 is exhibited. Most impressively, the whole process is facile and scalable，exhibiting recycling of resource and turning waste into treasure in an eco-friendly way.     

Enhancing oxygen permeation via multiple types of oxygen transport paths in hepta‐bore perovskite hollow fibers

The multiple types of efficient oxygen transport paths were demonstrated in high‐mechanical‐strength hepta‐bore Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3‐δ hollow fiber membranes. These types of paths play a prominent role in enhancing oxygen permeation fluxes (17.6 mL min^?1 cm^?2 at 1223 K) which greatly transcend the performance of state‐of‐the‐art Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3‐δ hollow fiber membranes, showing a good commercialization prospect. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4273–4277, 2017     

Carbon nanotubes branch on cobalt oxide nanowires core as enhanced high-rate cathodes of alkaline batteries

Directional synthesis of carbon/metal oxide core-branch arrays is of great importance for development of advanced high-rate alkaline batteries. In this work, we report a facile hydrothermal-chemical vapor deposition (CVD) method for controllable fabrication of Co₃O₄ @CNTs core-branch arrays. Interestingly, free-standing Co₃O₄ core nanowires are intimately decorated by cocoon-like branch CNTs with diameters of 20–30?nm, which act as a highly conductive network and structure stabilizer. The electrochemical performance of the designed Co₃O₄ @CNTs core-branch arrays are tested as cathodes of alkaline batteries. Arising from enhanced electrical conductivity, larger surface area and improved structural stability, the Co₃O₄ @CNTs arrays show superior high-rate electrochemical performance with a higher capacity (116 mAh g^?1 at 2.5?A?g^?1), lower polarization and better cycling stability than the pure Co₃O₄ nanowires arrays (76 mAh g^?1 at 2.5?A?g^?1). Our directional composite strategy can be extended to preparation of other carbon-based core-branch arrays for applications in electrochemical batteries and catalysis.     

Modulation of electrical transport in calcium cobaltite ceramics and thick films through microstructure control and doping

Ca₃Co₄O₉ is a promising p-type thermoelectric oxide material having intrinsically low thermal conductivity. With low cost and opportunities for automatic large scale production, thick film technologies offer considerable potential for a new generation of micro-sized thermoelectric coolers or generators. Here, based on the chemical composition optimized by traditional solid state reaction for bulk samples, we present a viable approach to modulating the electrical transport properties of screen-printed calcium cobaltite thick films through control of the microstructural evolution by optimized heat-treatment. XRD and TEM analysis confirmed the formation of high-quality calcium cobaltite grains. By creating 2.0 at% cobalt deficiency in Ca_2.7Bi_0.3Co₄O_9+δ, the pressureless sintered ceramics reached the highest power factor of 98.0 μWm^?1 K^-2 at 823 K, through enhancement of electrical conductivity by reduction of poorly conducting secondary phases. Subsequently, textured thick films of Ca_2.7Bi_0.3Co_3.92O_9+δ were efficiently tailored by controlling the sintering temperature and holding time. Optimized Ca_2.7Bi_0.3Co_3.92O_9+δ thick films sintered at 1203 K for 8 h exhibited the maximum power factor of 55.5 μWm^?1 K^-2 at 673 K through microstructure control.     

Conductivity and electrochemical performance of (Ba0.5Sr0.5)0.8La0.2Fe1−xMnxO3−δ cathode prepared by the citrate-EDTA complexing method

This study reports the successful preparation of single-phase perovskite (Ba_0.5Sr_0.5)_0.8La_0.2Fe_1−xMn_xO_3−δ (x = 0-0.2) by the citrate-EDTA complexing method. The crystal structure, thermal gravity analysis, coefficient of thermal expansion, electrical conductivity, and electrochemical performance of (Ba_0.5Sr_0.5)_0.8La_0.2Fe_1−xMn_xO_3−δ were investigated to determine its suitability as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The lattice parameter a of (Ba_0.5Sr_0.5)_0.8La_0.2Fe_1−xMn_xO_3−δ decreases as the amount of Mn doping increases. The coefficients of thermal expansion of the samples are in the range of 21.6-25.9 × 10⁻⁶ K⁻¹ and show an abnormal expansion at around 400 °C associated with the loss of lattice oxygen. The electrical conductivity of the (Ba_0.5Sr_0.5)_0.8La_0.2Fe_1−xMn_xO_3−δ samples decreases as the amount of Mn-doping increases. The electrical conductivity of the samples reaches a maximum value at around 400 °C and then decreases as the temperature increases. The charge transfer resistance, diffusion resistance and total resistance of a (Ba_0.5Sr_0.5)_0.8La_0.2Fe_0.8Mn_0.15O_3-δ-Ce_0.8Sm_0.2O_1.9 composite cathode electrode at 800 °C are 0.11 Ω cm², 0.24 Ω cm² and 0.35 Ω cm², respectively.