Nanostructured MIEC Ba0.5Sr0.5Co0.6Fe0.4O3−δ (BSCF5564) cathode for IT-SOFC by nitric acid aided EDTA–citric acid complexing process (NECC) (original) (raw)
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World Journal of Nano Science and Engineering, 2011
The nano ceramic Ba 0.5 Sr 0.5 Co 0.2 Fe 0.8 O 3 (BSCF) powders have been synthesized by Sol-Gel process using nitrate based chemicals for SOFC applications since these powders are considered to be more promising cathode materials for SOFC. Glycine was used as a chelant agent and ethylene glycol as a dispersant. The powders were calcined at 850˚C/3 hr in the air using Thermolyne 47,900 furnace. These powders were characterized by employing SEM/EDS, XRD and TGA/DTA techniques. The SEM images BSCF powder indicate the presence of highly porous spherical particles with nano sizes. The XRD results shows the formation of BSCF perovskite phase at the calcination temperature of 850˚C. From XRD line broadening technique, the average crystllite size of the BSCF powders were found to be around 9.15-11.83 nm and 13.63-17.47 nm for as prepared and after calcination at 850˚C respectively. The TGA plot shows that there is no weight loss after the temperature around 450˚C indicating completion of combustion.
Journal of Physics: Conference Series, 2019
Double perovskite-type BixSr2-xCo0.5Fe1.5O6-δ (BiSCF) oxides with various A-site (x = 0.6, 0.7, 0.8, designated as BiSCF06, BiSCF07, BiSCF08, respectively) have been synthesized by a solid-state reaction technique, and investigated on their structure properties of perovskite powder for application of intermediate-temperature solid oxide fuel cells (IT-SOFCs) purpose with related to the calcination temperatures at 950, 1000 and 1050C. The crystal structure of the BiSCF powder was analyzed by X-ray diffractometer (XRD), and determined by Rietveld refinement. The results show that BiSCF07 powder which calcined at 950 C shows the best structure of cubic perovskite with space group Pm-3m and a lowest impurity at room temperature indicated structure stability and offers a higher mobility of oxygen vacancies. Based on this result, BiSCF07 powder has a potential to be developed as cathode for IT-SOFCs applications.
Ionics, 2012
Ba 0.5 Sr 0.5 [Co x Zn 0.2-x ]Fe 0.8 O 3-δ, (x00, 0.04, 0.08, 0.12) cathode formulations were successfully synthesized by solid state reactions and the effect of cobalt doping at Zn site of Ba 0.5 Sr 0.5 Zn 0.2 Fe 0.8 O 3-δ (BSZF0.2) on the electrical conductivity, the polarization resistance and electrochemical behavior was evaluated. X-ray diffraction patterns indicate that a single cubic perovskite phase of Ba 0.5 Sr 0.4-Co 0.8 Fe 0.2 O 3-δ oxide is successfully obtained. Ba 0.5 Sr 0.5-Co 0.04 Zn 0.16 Fe 0.8 O 3-δ (BSCZF0.16) exhibited a high electrical conductivity of 10 S/cm at 400°C in comparison to the BSZF0.2 showing 5.5 S/cm. Further, BSCZF0.16 also possess a low polarization resistance as low as 0.22, 0.38, 0.87, and 1.55 Ω cm 2 at 750, 700, 650, and 600°C in air, respectively. Accordingly, a low activation energy value of 149.8 kJ/mol for BSCZF0.16 in comparison to 159.4 kJ/mol for BSZF0.2 indicates high catalytic efficiency. Enhancement of desirable properties such as electrical conductivity in combination with low-polarization resistance and lowactivation energy values can be attributed to the coexistence of Co and Zn in the B-site of BSCZF0.16 leading to the multivalent states which contributes to the enhanced electron transport properties demonstrating BSCZF0.16 as a better cathode for intermediate temperature solid oxide fuel cells applications.
Journal of Power Sources, 2009
The influence of titanium doping level in Ba 0.6 Sr 0.4 Co 1−y Ti y O 3−ı (BSCT) oxides on their phase structure, electrical conductivity, thermal expansion coefficient (TEC), and single-cell performance with BSCT cathodes has been investigated. The incorporation of Ti can lead to the phase transition of Ba 0.6 Sr 0.4 CoO 3−ı from hexagonal to cubic structure. The solid solution limitation of Ti in Ba 0.6 Sr 0.4 Co 1−y Ti y O 3−ı is 0.15-0.3 under 1100 • C. BSCT shows a small polaron conduction behavior and the electrical conductivity increases steadily in the testing temperature range (300-900 • C), leading to a relatively high conductivity at high temperatures. The electrical conductivity decreases with increasing Ti content. The addition of Ti deteriorates the cathode performance of BSCT slightly but decreases the TEC significantly. The TEC of BSCT is about 14 × 10 −6 K −1 , which results in a good physical compatibility of BSCT with Gd 0.2 Ce 0.8 O 2−ı (GDC) electrolyte. BSCT also shows excellent thermal cyclic stability of electrical conductivity and good chemical stability with GDC. These properties make BSCT a promising cathode candidate for intermediate temperature solid oxide fuel cells (IT-SOFCs).
Crystal Structure and Ionic Conductivity Study of Ni- Doped BSCF Cathode for Low Temperature SOFCS
Bonfring
Nickel doped BSCF (Ba0.5Sr0.5Co1-xFe0.6NixO3-δ (BSCFNi); x=0.05, 0.1, 0.15, and 0.2) cathode materials were synthesized using sol-gel citrate method for low temperature (300-500oC) Solid Oxide Fuel Cell (SOFC) application. The nanopowders of BSCFNi were then calcinated at various temperatures in the range of 600-1000oC. The nanopowders were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and differential scanning calorimeter (DSC). A cubic perovskite structure was observed in the X-ray diffraction measurements. The average crystallite size of the nanopowder obtained varies between 40-60 nm. DSC result, measured in the temperature range of 200-600oC, shows no phase transition. Ionic conductivity of the BSCFNi for varying concentration of nickel was measured in the temperature range of 200 oC to 500 oC. An emphasis is made on the effect of Ni doping on these properties.
Electrochemistry Communications, 2011
Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (BSCF)+ Co 3 O 4 composites with different Co 3 O 4 contents were synthesized, and their properties and performance as cathodes in IT-SOFCs were investigated. The diffraction patterns of the composites were well indexed based on the physical mixture of the BSCF phase and the Co 3 O 4 phase. A surprising increase in the total conductivity of the composites was observed even though Co 3 O 4 is a p-type semiconductor with a low conductivity. Electrochemical impedance spectra of symmetric cells indicated that both the area specific resistance and the activation energy were reduced in samples with Co 3 O 4 contents of 5-20 wt.% with minimum values reaching 10 wt.%. A synergistic effect likely occurred between BSCF and Co 3 O 4 that led to the better performance. An anode-supported single cell with 90 wt.% BSCF + 10 wt.% Co 3 O 4 delivered a promising peak power density of 1150 mW cm − 2 at 600°C.
Fuel cell studies of perovskite-type materials for IT-SOFC
Journal of Power Sources, 2006
The electrochemical performance of solid oxide fuel cells (SOFCs) based on perovskite-type materials (ABO 3 ) was investigated. La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3−δ (LSGM) ceramics were used as electrolyte and a composite containing La 0.8 Sr 0.2 MnO 3 (LSM) as cathode. Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (BSCF) was also used as cathode and La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3−δ (LSCM) as anode materials. Furthermore, fluoritetype Sm 0.15 Ce 0.85 O 2−δ (SDC) material was used as buffer layer between the electrolyte and the anode to avoid possible interfacial reactions. The maximum power density value of BSCF/LSGM/LSCM with 1.5 mm thick electrolyte supported cell was 160 mW cm −2 at 1073 K, using moist H 2 diluted with N 2 as fuel and air as oxidant.
Complex Perovskite system Dy0.5- x Bax Sr0.5 Co0.80 Fe0.20 O3-δ : As cathode for IT-SOFCs
International Journal of Applied Ceramic Technology, 2018
The present work is intended to study mixed conductivity of complex pervoskite oxide of chemical formula Dy 0.5-x Ba x Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (DBSCF-x) (0 x 0.07) to check its suitability as cathode for intermediate temperature solid oxide fuel cell (IT-SOFCs). Low temperature sol-gel combustion route has been used to prepare DBSCF-x systems. Structures are confirmed by X-ray diffraction (XRD); exhibit single phase perovskite structures with orthorhombic symmetry (space group Pbnm) for all compositions. Thermogravimety (TG) results indicate lattice oxygen loss in Ba doped DBSCF system by heat treatment in temperature interval 50 to 850°C, which is enhanced in N 2 atmosphere then air; in contrast to that lattice oxygen gain is observed for DBSCF-0 system. Temperature profile of DC conductivity exhibits metallic behaviour of DBSCF-x system; however the DBSCF-0 system shows semiconductor-to-metal transition at temperature around 450 o C. DBSCF-0.03 system displays maximum electronic conductivity. Electrochemical performance of electrodes is studied in three layers symmetrical cell configuration DBSCF-x/Ce 0.85 Sm 0.15 O 2- /DBSCF-x by complex impedance spectroscopy (CIS). Impedance diagram reveals presence of three processes mainly associated with (i) diffusion of oxide ions/oxygen intermediates through electrode/electrolyte interface, (ii) atomic oxygen diffusion within the electrode and (iii) oxide ion diffusion in the crystal lattice. ASR of the DBSCF-0.05 system is found 2.21 ohm cm 2 at 700 o C, which is lowest amongst all studied compositions. Results show that it is possible to modify the electrochemical properties of the DBSCF-x system by changing the Accepted Article This article is protected by copyright. All rights reserved. composition, but much more work even including optimisation of layer thickness and microstructure will be needed to reduce the ASR to the level of the state-of-art-electrodes and thereby better utilise the potential of the DBSCF-x system. .