Intermediate Temperature Solid Oxide Fuel Cells Research Articles

Role of charge-compensation process on the structural, microstructure and electrical properties of pure and Nb-doped Sr2SnO4

Abstract This article explores the charge compensation method by synthesising Sr2SnO4, Sr2Sn0.99Nb0.01O4, and Sr1.995Sn0.99Nb0.01O4. The synthesis of a monophasic, tetragonal sample was achieved using a typical ceramic approach and high-temperature heat treatment. The XRD followed by Rietveld refinement, confirmed the crystallization of material under the space group I4/mmm. The crystallite sizes for all samples determined to be less than 50 nm, while the micro-strain falls within the range of (1.78-2.93)x10-3. The microstructure exhibits a cuboidal shape for all samples, and the grain size is observed to decrease with the addition of Nb. The dielectric characteristics of the samples indicate the existence of Maxwell-Wagner and Orientational polarization in the sample. The sample Sr2Sn0.99Nb0.01O4 demonstrates a greater conductivity value compared to Sr1.995Sn0.99Nb0.01O4. This is attributed to the presence of excess electrons that compensate for the overall charge, as opposed to Sr1.995Sn0.99Nb0.01O4 where the extra charge is compensated by a cationic vacancy V_Sr^''. The time-temperature-superposition principle (TTSP) is applicable to all compositions and indicates that similar sources are responsible for both conduction and relaxation processes. The dielectric permittivity and dissipation factor are found to be in the range of 150 to 175 and 0.2 to 0.5, respectively. This suggests that they have potential for future use in millimeter-wave communication with dielectric resonator antennas (DRAs). Due to the presence of oxygen ions and the ability to conduct both ions and electrons, at temperatures above 400℃, it is a suitable choice for electrode materials in the application of intermediate temperature solid oxide fuel cell (IT-SOFCs). Exploring the manipulation of defects using electrical and ionic charge compensation methods shows potential for enhancing materials in semiconductor technology.

Evaluation of selected Fe–Cr steels under single- and dual-atmosphere conditions for intermediate-temperature solid oxide fuel cell interconnect applications

For Intermediate-Temperature SOFC, the lower operating temperature allows for a broader range of steel grades to be used as interconnects. This work compares the oxidation performances of six Cr2O3-forming steels and one Al2O3-forming steel, under single- and dual-atmosphere conditions.Single-atmosphere exposures in combination with Cr(VI) evaporation measurements were carried out at 600 °C. Except for AISI 430 all the Cr2O3-forming steels showed protective behaviour with similar Cr(VI) evaporation values and low area specific resistance (ASR) values. Kanthal EF101 showed the lowest level of Cr(VI) vaporisation but substantially higher ASR values.Dual-atmosphere exposures were carried out at 600 °C in Ar-5%H2–3%H2O//air-3%H2O. All Cr2O3-forming steels suffered various degrees of breakaway corrosion. Therefore, operation under dual-atmosphere conditions is likely the life-time-limiting failure mode.

CO2-tolerant and cobalt-free La4Ni3-xCuxO10±δ (x = 0, 0.3, 0.5 and 0.7) cathodes for intermediate-temperature solid oxide fuel cells

Cu is doped to La4Ni3O10±δ to improve its electrochemical performance as a potential intermediate-temperature solid oxide fuel cell (IT-SOFC) cathode material. A new higher-order Ruddlesden-Popper (R-P) phase composition La4Ni3-xCuxO10±δ, (L4N3-xCx, 0.0 ≤ x ≤ 0.7) is synthesized using an EDTA-citrate process. The L4N3-xCx cathode has a good chemical compatibility with the La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) electrolyte. A thermodynamic stability test shows that L4N3-xCx is stable after 72 h exposure to 600, 700, and 800 °C in air. The L4N3-xCx cathode shows chemical stability against CO2, and a stable structure over 12 h in CO2 has been demonstrated. The thermal expansion coefficients (TECs) have been determined to be in the range of 14.1–14.6 × 10−6 K−1, close to that of the LSGM electrolyte. The Cu content (x) significantly affects the electrical conductivity and sinter density of L4N3-xCx. La4Ni2.7Cu0.3O10 (L4N2.7C0.3) displays the highest electrical conductivity value of which reaches about 383 to 319 S cm−1 at 600–800 °C. In addition, Cu doping improves the electrochemical performance of L4N3-xCx. The area specific resistance (ASR) of the La4Ni2.5Cu0.5O10 (L4N2.5C0.5) cathode was found to be 0.045 Ω cm2 at 800 °C, which is significantly better than that of L4N3. The peak power density of a single cell using the L4N2.5C0.5 cathode is 526 mW cm−2 at 800 °C, and a 200 h long-term test demonstrates good stability. These results indicate that La4Ni3-xCuxO10±δ cathode is a promising cathode material for IT-SOFCs.

Novel spinel based high entropy oxide as electrode for symmetric SOFCs

Fabrication of symmetric electrodes for intermediate temperature SOFCs can significantly reduce fuel cell production costs without compromising efficiency. Herein, we report a novel spinel based high entropy oxide (CuLiFeCoNi)1.4Mn1.6O4-δ (CM-HEO) that exhibit better symmetric electrode properties than the parent spinel oxide, Cu1.4Mn1.6O4-δ (CM). The prepared HEO exhibited good structural and thermal stability up to 800 °C as inferred from the XRD, Raman and TGA-DSC results. Temperature-programmed reduction and desorption profiles of CM-HEO outperformed CM by exhibiting hydrogen adsorption and lower CO2 desorption across different temperature ranges. The enhancement of Lewis acid-base sites is evident from the XPS analysis validating the observed increase in HOR and ORR activity. The high electrocatalytic activity of the material arise from its lower activation energies (0.27 eV in air, 0.09 eV in dry H2 and 0.03 eV in dry CH4) with a polarisation resistances of 0.152 Ωcm2 under ambient atmosphere and 0.044 Ωcm2 under dry H2. These findings exalt CM-HEO as an efficient symmetric SOFC electrode material.

Structural, thermal, surface, and electrical properties of Bi2O3 ceramics co–doped with Er–Ho–Tb rare earths

Face–centered cubic–Bi2O3 (δ–phase) material is a better ion conductor when compared to other types of solid electrolytes that have been declared in the literature due to its anion–defective crystal configuration, and hence it can be a promising solid electrolyte choice for intermediate temperature SOFC applications. In this research, Er–Ho–Tb co–doped Bi2O3 compounds were successfully synthesized by the solid–state reaction method and characterized using the XRD, TG & DTA, FPPT, and FE–SEM techniques. Apart from sample 4Er4Ho4Tb, each sample became stable with a cubic δ–phase at room temperature, according to XRD patterns. The DTA curves revealed no exothermic or endothermic peaks, implying a phase change in the constant heating cycle. The conductivity of Ho–rich compositions was higher than that of others, confirming the impact of cation polarizability on conductivity. In addition, at 700 °C, the sample 4Er8Ho4Tb with 1:2:1 content ratios had the highest conductivity of 0.29 S/cm. The porosity on the grain boundaries increased with doping, leading to higher grain boundary resistance, which could be responsible for the conductivity drop.

Ni-doped Fe-based perovskite to obtain multifunctional and highly efficient electrocatalytic active IT-SOFC electrode

This paper systematically studies Ni doping at Fe sites in La0.6Sr0.4Co0.3Fe0.7O3-δ (LSCF) as an intermediate temperature solid oxide fuel cell (IT-SOFC) electrode. The electrocatalytic activity of Ni-doped electrodes in oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) modes was analyzed, rather than individual cathode or anode. The results indicate that Ni doping increases the internal vacancies, ORR activity, and charge transfer ability of La0.6Sr0.4Co0.3Fe0.6Ni0.15O3-δ (LSCFN15). In addition, compared to LSCF, LSCFN15 also reduces the energy barriers for surface oxygen exchange and bulk diffusion, thereby increasing the overall ORR kinetic rate. Combined with the distribution of relaxation time (DRT) analysis, it was confirmed that Ni-doped LSCFN15 increased the adsorption and dissociation rates of oxygen. At 750 ℃, the area-specific resistance (ASR) of LSCFN15 reached 0.045 Ω cm2, which is only 58.4 % of LSCF (0.077 Ω cm2). As a SOFC cathode, the peak power density (PPD) reached 1175 mW cm−2, 1.31 times that of LSCF (898 mW cm−2). As a SOFC anode, the current exchange density of LSCFN15 in OER mode reaches 164 mA cm−2, which is higher than the 125 mA cm−2 of LSCF, indicating that LSCFN15 also has the potential to serve as an anode for SOFC. In addition, Ni doping reduces the thermal expansion coefficient of the electrode and improves its thermal compatibility with traditional electrolytes. As an electrode, LSCFN15 exhibits excellent long-term stability in both SOFC and SOEC modes. Overall, Ni-doped Fe-based perovskite can improve the ORR and OER activities while enhancing the stability of cell operation and is expected to obtain multifunctional SOFC electrode materials.

A high-performance composite cathode based on thermal expansion complementation for SOFC

The discrepancy in thermal expansion coefficients (TECs) between the cobalt-based cathode and the electrolyte presents a notable obstacle in attaining optimal performance levels for solid oxide fuel cells (SOFCs). Here we propose to introduce negative thermal expansion (NTE) component Sm0.85Zn0.15MnO3 (SZM) to SrNb0.1Co0.9O3−δ (SNC) cathode to prepare SNC-xSZM (x = 0, 10, 20 and 30 %) composite cathode materials. The impact of incorporating negative thermal expansion material on the composition and properties of the matrix materials were examined by X-ray diffraction, thermal dilatometer, high-resolution transmission electron microscopy, and electrochemical workstation. The results show that SNC-xSZM can achieve more ideal thermal matching with Ce0.8Gd0.2O1.9 (GDC), and the thermal expansion coefficient decreases observably from 25.47 × 10−6 K−1 for x = 0 to 13.74 × 10−6 K−1 for x = 30 %. The optimal comprehensive electrochemical performance is obtained for SNC-20SZM, which possesses the minimum polarization resistance (Rp) of 0.012 Ω cm2 at 700 °C. The SNC-20SZM-based cell shows a maximum peak power density (PPD) of 1.22 W cm−2 while exhibiting stable operation for a continuous duration of 120 h at a constant current of 0.8 A cm−2, with performance remaining optimal. Moreover, SNC-20SZM demonstrates exceptional durability and stability over prolonged durations even in high CO2 atmospheres. An innovative approach for enhancing the development of intermediate-temperature solid oxide fuel cells (IT-SOFCs) involves incorporating SZM in the SNC cathode, thereby augmenting electrochemical performance and narrowing the gap in the thermal expansion coefficient among SOFC modules.

CO2/Cr-tolerance and oxygen reduction reaction of novel high-entropy perovskite cathode for intermediate temperature solid oxide fuel cell

The development and exploration of cathode oxides with outstanding electrocatalytic activity are critical processes aimed at achieving a decrease in the operation temperature of solid oxide fuel cells (SOFC). Herein, a novel high-entropy oxide, La0.2Pr0.2Nd0.2Sm0.2Gd0.2BaCoFeO5+δ (HEP), which incorporates five lanthanide species (La, Pr, Nd, Sm, and Gd) in the A-site of perovskite, has been specifically developed and assessed as selected cathode for intermediate-temperature SOFC. Investigations of phase structure, chemical compatibility, oxygen transport characteristics, oxygen reaction kinetic, thermal expansion, surface chemical state, conductivity, as well as CO2/Cr-durability are thoroughly performed to assess the basic physicochemical properties of the HEP cathodes. The HEP cathode possesses good operational stability, moderate thermal expansion behavior, fast oxygen transport dynamics, and superior chemical compatibility with the electrolyte. At 700 °C, the polarization resistance low to 0.072 Ω cm2 and output power density high to 332.2 mW cm−2 were obtained for the symmetrical and electrolyte-supported single cells. Furthermore, a stable current density is obtained for the single cell operating at 600 °C and 0.5 V for 100 h. Analysis of electrochemical impedance spectra (EIS) and distribution of relaxation time (DRT) data at different oxygen partial pressures reveal that the charge-transfer and oxygen ions ionization processes at intermediate frequencies present a significant limiting step in the rate of the oxygen reduction reaction. However, under realistic utilization conditions, cathodes of cells often endure irreversible performance degradation owing to the Cr deposition from interconnects or CO2 poisoning in air. Hence, the behavior of Cr and CO2 poisoning is also systematically investigated in symmetrical cell measurements; the results confirm that the HEP cathode displays good resistance to Cr and CO2 poisoning. Overall, our findings indicate that the HEP material is regarded as a favored ceramic cathode for SOFC.

Structure and Electrochemical Characterization of Nd0.5Ba0.5Zr0.8Fe0.2O3+δ Cobalt-Free Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cells: An Experimental Investigation

Compared to other energy-generating technologies and energy conversion devices, intermediate-temperature solid oxide fuel cells (IT-SOFCs) have gained significant attention from energy experts due to its high energy density, moderate operating temperature (600 – 800 ℃), low emissions, and reliability. Enhancing the performance of IT-SOFCs requires suitable and excellent cathode materials. Thus, a perovskite-type Nd0.5Ba0.5Zr0.8Fe0.2O3+δ (NBZFO) material was synthesised via traditional solid-state reaction technique and analysed as a potential cathode material for IT-SOFCs. Analysis of x-ray diffraction data (XRD) revealed a single-phase perovskite material that crystallises in cubic space group (pm-3m). The thermal and electrochemical properties were analysed with the aid of thermogravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS). NBZFO has an electrical conductivity in air of 80 S/cm at 400 ℃, and a polarization resistance (PR) of 0.106 Ω∙cm2 at 800 ℃. TGA analysis reveals a slight loss in weight of about 0.58%, thereby suggesting a highly stable cathode material for IT-SOFC. Electrochemical investigation shows that NBZFO has good electronic and ionic conductivity and excellent oxygen stichometry. Further studies are required to understand the effects of varying B-site composition of the cathode material.

In situ construction of A-site high-entropy perovskites with interfacial CeO2 for a high-performance IT-SOFC air-electrode.

Developing an intermediate-temperature solid oxide fuel cell (IT-SOFC) is one of the most promising ways of achieving carbon neutrality, but its air-electrode is restricted by the conflict between the sluggish catalytic activity and durability. Herein, an A-site high-entropy perovskite composite La0.2Ba0.2Sr0.2Ca0.2Ce0.2-xCoO3-δ-xCeO2 (LBSCCC-CeO2) air-electrode material is fabricated via a one-step self-constructing strategy, which shows excellent oxygen reduction activity and stability due to the high-entropy structure and the synergy effect between LBSCCC and interfacial CeO2. This work provides a new way of fabricating high-performance air-electrodes in IT-SOFCs.

Boosting the electrochemical performance of oxygen electrodes via the formation of LSCF-BaCe0.9–xMoxY0.1O3–δ triple conducting composite for solid oxide fuel cells: Part II

This research is the continuation of our previous work, in which we introduced novel proton-conducting electrolytes BaCe0.9–xMoxY0.1O3–δ (BCMxY; x = 0.025, 0.05). In this study, we explore the potential of the proton-conducting BCM0.025Y electrolyte by creating a composite with La0.6Sr0.4Co0.2Fe0.8O3–δ (LSCF) to form triple conducting electrodes for solid oxide fuel cells (SOFC). The formation of the LSCF-BCM0.025Y composite enhances both the three-phase reaction interface length and the concentration of oxygen vacancies, contributing to improved dissociation rates and enhanced oxygen adsorption. The desired characteristics, including density, structure, composition, electrochemical performance, and thermal stability, have been confirmed through a comprehensive set of analyses including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS), and thermogravimetric analysis (TGA) coupled with differential scanning calorimetry (DSC), respectively. The cell configuration of Ni-YSZ | BCZY | LSCF-BCM0.025Y exhibited a remarkable maximum power density (MPD) of 418.7 mW cm−2, which is approximately 29 % higher than that achieved with a typical LSCF cathode (325.6 mW cm−2) at an operating temperature of 600 °C. The outstanding performance and enduring stability of the LSCF-BCM0.025Y composite over a 500 h period demonstrate its potential as a promising cathode material for intermediate-temperature SOFCs.

Ce-doped promotes the phase stability and electrochemical performance of SrCoO3-δ cathode for intermediate-temperature solid oxide fuel cells

The development of cathode with high oxygen reduction reaction (ORR) activity is crucial for intermediate-temperature solid oxide fuel cells (IT-SOFCs). SrCoO3-δ oxides, a mixed ion-electron conductivity (MIEC), are promising cathode materials. However, pure SrCoO3-δ exhibits a hexagonal or rhombohedral structure with poor electrical properties, limiting its application in IT-SOFCs. In this work, high-valence Ce4+ is doped at the A-site of SrCoO3-δ perovskite to improve the phase structural stability and electrochemical activity of SrCoO3-δ. The findings reveal that Ce4+ doping in small amounts significantly advances the conductivity and ORR activity due to enhanced structural stability. Among the series of samples, Sr0.95Ce0.05Co3-δ (SCC005) presents the best electrochemical performance. Moreover, the addition of Ce0.8Gd0.2O2-δ (GDC) further reduces polarization resistance by about ∼7 times. The peak power density of 1.3 W cm−2 is obtained at 750 °C for the SCC05-30%GDC cathode. The results indicate that A-site Ce doping is a promising strategy to enhance the ORR activity of SrCoO3-δ oxides.

High entropy double perovskite cathodes with enhanced activity and operational stability for solid oxide fuel cells

Rare-earth site high entropy double perovskite oxides with different molar ratios have been evaluated as the cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFC). The effect of configuration entropy on crystal structure, electrical conductivity, electrochemical performance and stability are investigated. Our results reveal that the activity of all high entropy oxides show enhanced electrochemical activity. Among them, the equimolar one (HEO) exhibits the highest activity with a low polarization resistance of 0.05 Ω cm2 at 700 °C. Moreover, it exhibits excellent stability in the CO2-containing atmosphere. The enhanced activity and operational stability can be attributed to reduced surface Ba segregation and the formation of active and robust BaCoO3-δ nanoparticles on HEO surface, rather than BaCO3 and Co3O4 phases. This work indicates that configurational entropy engineering is very effective for rational surface composition regulation.

Structural and electrical properties of Gd and W co-doped La2Mo2O9 as electrolyte for IT-SOFCs

In this study, a modified sol-gel method was employed to synthesize Gd and W co-doped La2Mo2O9 (LMX). The impact of Gd and W co-doping on the pristine LMX lattice was examined using X-Ray diffraction, and the local structural parameters were analyzed through Rietveld refinement. The findings indicate that both the pure and co-doped LMX samples possess a cubic structure with a P213 space group. To investigate the electrical performance of the lanthanum molybdate (La2Mo2O9) both in its pure form and when co-doped with Gd and W, electrochemical impedance spectroscopy was conducted. The results demonstrated that co-doping enhances the conductivity of oxy-ions compared to pure LMX. Specifically, La1.7Gd0.3Mo1.7W0.3O9 (LMXG3) exhibited a higher ionic conductivity of approximately 2 x 10−2 Scm−1 at a temperature of 650 °C, surpassing the conductivity of the pure LMX sample and other co-doped LMX samples. This investigation highlights the potential of the Gd and W co-doped LMX system as a solid electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs).

Study of structural, electrical, and electrochemical properties of Sr3-xPrxFe1.8Co0.2O7-δ cathode for IT-SOFCs

Developing new cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) is still challenging. In this study, co-doped Sr3Fe2O7-δ Ruddlesden-Popper (R-P) (Sr3-xPrxFe1.8Co0.2O7-δ x = (0–0.3)) cathode is synthesized by the polymer complex technique as a cathode for IT-SOFCs. The synthesized powders show a desired tetragonal structure of Sr3-xPrxFe1.8Co0.2O7-δ with an I4/mmm space group. The effect of Pr and Co on the physical, thermal, electrical, and electrochemical properties of the cathodes is investigated. The results reveal that Pr/Co co-doping improves electrochemical properties while increasing the electrical resistivity and average thermal expansion coefficients (TECs). To evaluate the long-term thermal stability of the cathode, they are heated at 800 °C for 100 h in the air, and no contaminant is found. In the optimal amount of Pr and Co (Sr2.7Pr0.3Fe1.8Co0.2O7-δ), area-specific resistance (ASR) of 0.058 Ω.cm2 and maximum output power density of 745 mW/cm2 are obtained at 800 °C. Strong oxygen-reducing reaction (ORR) activity and long-term thermal stability make Sr2.7Pr0.3Fe1.8Co0.2O7-δ an appropriate alternative cathode material for IT-SOFC.

Effects of Bi2O3 doping on structural and electrical properties of Ce0.8Sm0.2O1.9 electrolyte for solid oxide fuel cells

The study investigates the impact of Bi2O3 doping on the crystal structure, density, and ionic conductivity of Ce0.8Sm0.2O1.9, a type of samarium-doped ceria oxide (SDC). The material is intended for use as a solid electrolyte in intermediate temperature solid oxide fuel cells (IT-SOFCs). The SDC-based electrolyte was created using the auto-combustion technique, with various molar ratios of Bi2O3. Phase compositions, microstructure, and ionic conductivity of all ceria ceramics were analysed using XRD, SEM and impedance analyses, respectively. The language is formal, clear, objective, and value-neutral, using high-level, standard language with consistent technical terms. Grammar, spelling, and punctuation are correct. Consistent citation and footnote style are maintained. The samples are single-phase ceramics that crystallise into a cubic fluorite type structure with space group Fm-3 m, as confirmed by the X-ray diffraction pattern. Technical abbreviations are explained. The structure ensures a logical flow of information with causal connections between statements. No filler words or biased language are used. SDC/Bi2O3 composite powders exhibit high sintering activity. The relative density of all samples sintered at 1300 ºC for 5 h was more than 96%, which is higher than that achieved by pure SDC electrolyte sintered at 1400 ºC (94.06%). Electrochemical performance results demonstrate that adding an appropriate amount of Bi2O3 can significantly enhance the conductivity of SDC materials. The SDC-based electrolyte containing 9 mol% of Bi2O3 (SDCB9) demonstrates the maximum conductivity of 43.5 mS·cm−1 at 800 °C, surpassing that of pure SDC which measures 26.86 mS·cm−1.

Experimental study and first-principles calculation of enhanced electrochemical properties of Bi0.7Sr0.3FeO3-δ (BSFO) – La0.8Sr0.2MnO3-δ (LSM) composite cathodes for intermediate-temperature solid oxide fuel cells

In order to enhance the electrochemical performance of cobalt-free Bi0.7Sr0.3FeO3-δ (BSFO) cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs), a composite cathode consisting of BSFO and La0.8Sr0.2MnO3-δ (LSM) is developed. The optimized polarization resistance of the composite cathode (0.11 Ω cm2 at 800 °C) is found to be only 61 % that of pure BSFO (0.18 Ω cm2 at 800 °C), indicating a significant improvement in performance. The first-principles calculation indicates that the enhanced electrochemical performance is mainly due to the domain of low oxygen vacancy formation energies of BSFO-LSM-L interfaces (Evac, −3.63 eV) and LSM (Evac, −3.11 eV). The anode-supported single cell of NiO-SDC/SDC/BSFO－LSM shows a peak power density of 825.83 mW cm−2 at 800 °C using wet H2 (∼3 vol% H2O) as fuels and ambient air as oxidants. In addition, the single cell exhibits a good stability at the electric current density 400 mA cm−2 for 50 h measured at 650 °C.

Study on the composite structure of cobalt-free oxides as cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs)

Summary: Solid Oxide Fuel Cells (SOFCs) represent a promising technology for efficient and clean energy conversion. This study focuses on the design and development of a novel cathode material for SOFCs, specifically exploring the use of a free-cobalt cathode within a composite structure. Investigating the structure of cobalt-free composites of Ba0.5Sr0.5FeO3-δ (BSF) and Ba0.5Sr0.5Fe0.8B0.2O3-δ (B=Cu, Zn) (BSFB) have been prepared and evaluated as cathodes for IT-SOFCs. The solid-state reaction was employed for generating and modifying the composite structure of the model system. The decomposition reaction and the formation of perovskite structure have been observed using thermal gravimetric analysis and X-ray diffraction. The study encompasses experimental procedures, data processing using GSAS software, and the application of the Rietveld method to achieve precise analysis results. Rietveld analysis outcomes offer intricate details about the crystal structure, encompassing crystal unit parameters, and scale factors. The solid-state reaction led to the reduction in the weight of the composite during the heating process. The decomposition reaction of oxides was generated between 650 to 950 oC. The average of total weight loss during the period treatment was achieved up to 18 % and the perovskite phase formed in the composite structure. A single-phase perovskite from a cubic structure with space group Pm-3m was demonstrated by all composite’s models. The lattice parameter and a unit cell volume were obtained from the model system of BSF, BSFC and BSFZ, respectively. This study explores the potential development of SOFCs technology with the hope of making a positive contribution to advancing clean and sustainable energy solutions in the future

Towards sustainable electrochemistry: green synthesis and sintering aid modulations in the development of BaZr0.87Y0.1M0.03O3−δ (M = Mn, Co, and Fe) IT-SOFC electrolytes

In this study, BaZr0.87Y0.1M0.03O3−δ perovskite electrolytes with sintering aids (M = Mn, Co, and Fe) were synthesized by a sustainable approach using spinach powder as a chelating agent and then compared with chemically synthesized BaZr0.87Y0.1M0.03O3−δ (M = Mn, Co, and Fe) electrolytes for intermediate temperature SOFCs. This is the first example of such a sustainable synthesis of perovskite materials with sintering aids. Structural analysis revealed the presence of a cubic perovskite structure in BaZr0.87Y0.1M0.03O3−δ (M = Mn, Co, and Fe) samples synthesized by both green and conventional chemical methods. No significant secondary phases were observed in the samples synthesized by a sustainable approach. The observed phenomena of plane shift were because of the disparities between ionic radii of the dopants, impurities, and host materials. The surface morphology analysis revealed a denser microstructure for the electrolytes synthesized via green routes due to metallic impurities in the organic chelating agent. The absence of significant impurities was also observed by compositional analysis, while functional groups were identified through Fourier-transform infrared spectroscopy. Conductivity measurements showed that BaZr0.87Y0.1M0.03O3−δ (M = Mn, Co, and Fe) electrolytes synthesized by oxalic acid have higher conductivities compared to BaZr0.87Y0.1M0.03O3−δ (M = Mn, Co, and Fe) electrolytes synthesized by the green approach. The button cells employing BaZr0.87Y0.1Co0.03O3−δ electrolytes synthesized by the chemical and green routes achieved peak power densities 344 and 271 mW·cm−2 respectively, suggesting that the novel green route can be applied to synthesize SOFC perovskite materials with minimal environmental impact and without significantly compromising cell performance.

Sr-deficient medium-entropy Sr1-xCo0.5Fe0.2Ti0.1Ta0.1Nb0.1O3-δ cathodes with high Cr tolerance for solid oxide fuel cells

In this work, Sr-deficiency is proposed as an effective strategy to improve the oxygen reduction reaction (ORR) activity and Cr tolerance of medium-entropy Sr1-xCo0.5Fe0.2Ti0.1Ta0.1Nb0.1O3-δ (S1-xCFTTN, x=0–0.15) cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). With proper Sr-deficiency, S0.95CFTTN possesses the highest electrical conductivity and fastest oxygen exchange kinetics within tested samples. The optimized cathode yields outstanding ORR activity with a polarization resistance of 0.024 Ω cm2 at 700 °C, much lower than 0.037 Ω cm2 for SCFTTN cathode. Based on these, an anode-supported cell with S0.95CFTTN cathode exhibits a peak power density of 1153.5 mW cm−2 at 800 °C, much higher than that with SCFTTN cathode. Moreover, the S0.95CFTTN cathode displays dramatically enhanced Cr tolerance ability, which is due to the Sr-deficient diminishes surface Sr segregation and subsequent the formation of SrCrO4. Our results indicate appropriate Sr-deficiency is an effective approach to enhance the ORR activity and stability of SOFC cathodes.