Sr- and Mo-deficiency Sr1.95TiMo1−xO6–δ double perovskites as anodes for solid-oxide fuel cells using H2S-containing syngas

Sr- and Mo-deficiency Sr_1.95TiMo_1−xO_6–δ (STM_1−xO; x = 0–0.075) double perovskites are prepared and applied as potential anodes for solid-oxide fuel cells (SOFCs) operated in sulfur-containing syngas. The effect of Sr- and Mo- deficiency on the crystalline nature, electrical and thermal properties and electrochemical performance are investigated. The STM_0.925O crystallizes in a single-phase cubic perovskite structure and has excellent thermal and chemical compatibilities with Ce_0.9Gd_0.1O_1.95, Ce_0.8Sm_0.2O_1.9 and La_0.9Sr_0.1Ga_0.8Mg_0.2O_3–δ electrolytes. The conductivities of STM_0.925O in H₂ at 550 °C–850 °C are higher than 160 S cm⁻¹. The polarization resistance (R_p) of STM_0.925O is recorded as 1.451 Ω cm² at 850 °C in H₂, which is 51% lower than that in pristine Sr₂TiMoO₆, and the maximum power density (P_max) at 800 °C in H₂ shows 41% increment as compared to Sr₂TiMoO₆. The electrochemical performance of STM_0.925O is further enhanced by impregnation of Pd: the R_p is decreased from 0.73 Ω cm² to 0.33 Ω cm² for STM_0.925O and Pd-impregnated STM_0.925O (Pd-STM_0.925O) anodes, while the corresponding P_max in H₂ increased from 649 to 1051 mW cm⁻² at 850 °C. The Pd-STM_0.925O shows high electrochemical property and durability in simulated coal syngas containing sulfur (3% H₂O), making it a promising anode for hydrocarbon-fueled SOFCs.     

Synthesis and characterization of lithium aluminum-doped spinel (LiAlxMn2−xO4) for lithium secondary battery

LiAl_xMn_2−xO₄ has been synthesized using various aluminum starting materials, such as Al(NO₃)₃, Al(OH)₃, AlF₃ and Al₂O₃ at 600–800°C for 20 h in air or oxygen atmosphere. A melt-impregnation method was used to synthesize Al-doped spinel with good battery performance in this research. The Al-doped content and the intensity ratio of (3 1 1)/(4 0 0) peaks can be important parameters in synthesizing Al-doped spinel which satisfies the requirements of high discharge capacity and good cycleability at the same time. The decrease in Mn³⁺ ion by Al substitution induces a high average oxidation state of Mn ion in the LiAl_xMn_2−xO₄ material. The electrochemical behavior of all samples was studied in Li/LiPF₆-EC/DMC (1:2 by volume)/LiAl_xMn_2−xO₄ cells. Especially, the initial and last discharge capacity of LiAl_0.09Mn_1.97O₄ using LiOH, Mn₃O₄ and Al(OH)₃ complex were 128.7 and 115.5 mAh/g after 100 cycles. The Al substitution in LiMn₂O₄ was an excellent method of enhancing the cycleability of stoichiometric spinel during electrochemical cycling.     

Synthesis,characterization and kinetic study of the Sr2FeMoO6-δ double perovskite: New findings on the calcination of one of its precursors

Sr₂FeMoO_6-δ double perovskites are widely-recognized due to several important factors: high electronic conductivity and electrocatalytic activity, structural stability under reducing atmospheres, high transition temperature, enormous magnetoresistance, reasonable tolerance to carbon formation, and their desirable capacity to avoid sulfur poisoning. One of the methods most commonly-used to synthetize these perovskites is solid-state reaction. The precursor phases usually associated with this method are the oxides SrMoO₄ and SrFeO_3-δ when Fe2O₃, SrCO₃, and MoO₃ are the initial reagents used. Morphological, XRD (Rietveld), and thermogravimetry (calcination and reduction) analyses are steps or routes towards achieving the final result. While recent studies suggest that the temperature of calcination is always 900 °C and that reduction occurs at 1200 °C, they fail to explain why this occurs. This article demonstrates, according to the results of thermogravimetric analysis (TGA), that as calcination advances weight loss increases until a temperature of 850 °C is reached. In addition, it stresses the importance of the ball milling technique at ambient temperature to prevent sublimation of the MoO₃ compound at 700 °C in the later steps of synthesis, such as calcination and reduction. According to the kinetic study, the values of activation energy (Ea) and reaction order (n) were 130.47 kJ/mol and 1 respectively.     

Development of shape-engineered α-MnO2 materials as bi-functional catalysts for oxygen evolution reaction and oxygen reduction reaction in alkaline medium

In this work, three kinds of α-MnO₂ nano shapes, namely, nano-wires, nano-tubes and nano-particles have been prepared with a fine control over α-crystallographic form by employing hydrothermal procedure. The materials have been thoroughly characterized by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) spectrometry, field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. The MnO₂ nano shapes are used as a model system for examining the shape-influenced bi-functional electrocatalytic activity towards oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline medium. The bi-functional role has been investigated by cyclic voltammetry and linear sweep voltammetry with rotating ring disc electrode (RRDE) techniques. It is found that α-MnO₂ nano-wires possess enhanced electrocatalytic activity compared to other two shapes namely nano-tubes and nano-particles despite the nano-tubes having a much higher specific surface area. The insight of bi-functional electrocatalytic activity is analysed in terms of catalyst surface with the help of first principles density functional theory (DFT) calculations based on the fact of surface energies and adsorption of water on the surface for a facile reaction.     

An intelligent oxygen carrier of La2−xSrxNiO4−λ for hydrogen production by chemical looping reforming of ethanol

This work studied an intelligent perovskite of La_2?xSr_xNiO_4?λ as oxygen carrier (OC) to produce hydrogen in chemical looping reforming (CLR) process. It was prepared by co-precipitation method and investigated by XRD, TEM, ICP-OES, H₂-TPR, TGA technologies and fixed-bed experiment. The ‘intelligence’ refers to the self-regeneration ability and structural flexibility of perovskite. The former was verified by the movement that Ni ions repeatedly immerse into and out of perovskite bulk during CLR process. The movement suppressed the growth of Ni particles and maintained its high dispersion. The latter was confirmed by the addition of promoters. The insertion of Sr increased lattice oxygen mobility and greatly strengthened the reversible evolution of metallic Ni, which boosted the carbon-resistance and hold favorable stability of OC. The La_1.4Sr_0.6NiO_4?λ was the optimized composition owing to the superior activity, higher hydrogen selectivity (87%) and admirable stability. Moreover, shortened ‘dead time’ and more ideal self-regeneration property of perovskite were attained due to easier reducibility of Ni ions.     

Highly carbon– and sulfur–tolerant Sr2TiMoO6−δ double perovskite anode for solid oxide fuel cells

Ni-based cermets are most commonly used anode materials for solid-oxide fuel cells (SOFCs), but poor stability operating on hydrocarbon fuels seriously hampers their commercialization due to carbon deposition and sulfur poisoning. Here, we report a carbon– and sulfur–tolerant double perovskite anode Sr₂TiMoO_6−δ (STMO) combining the characteristics of two simple perovskites of SrTiO₃ and SrMoO₃. The STMO anode exhibits excellent thermal and chemical compatibility with La_0.9Sr_0.1Ga_0.8Mg_0.2O_3–δ (LSGM) and Ce_0.8Sm_0.2O_1.9 (SDC) electrolytes in 5% H₂/Ar. The single cell with STMO anode demonstrates good stability and excellent coking resistance and sulfur tolerance in H₂S-containing syngas during a 60-h period. The maximum power density (P_max) values of a LSGM-electrolyte-supported single cell with STMO anode are 505 and 275 mW cm⁻²at 850 °C in H₂ and H₂S-containing syngas, respectively. The electrochemical performance is further improved by impregnation of Pd nanoparticles, where the P_max values achieve 1009 and 586 mW cm⁻² at 850 °C under the same conditions, respectively, showing great potential as an anode material for SOFCs operating on H₂S-containing syngas. Our study provides a strategy to develop versatile double perovskite materials by combining the relevant characteristics of two separate perovskites.     

Preparation and application of Ce/ZrO2−TiO2/SO42− as solid catalyst for the esterification of fatty acids

To develop heterogeneous and reusable catalyst for the esterification of fatty acids, in presence of triglycerides, sulfate species has been incorporated over Ce/ZrO₂–TiO₂ support. The catalyst activity was found to be a function of its Bronsted acidic sites which in turn depends on the cerium concentration in catalyst. The esterification of oleic acid with methanol or ethanol in presence of prepared catalyst has followed the first order kinetics and Koros–Nowak test has demonstrated that reaction rates are independent from diffusion limitations. An increase in acid or alcohol alkyl chain length (steric factor) was found to show negative effect on the esterification activity of catalyst. Although, the catalyst was able to catalyze the esterification even in presence of up to 12 wt% moisture (with respect to fatty acids), however, a decrease in turn over frequency (TOF) was observed. The catalyst has shown excellent stability as negligible sulfate leaching was observed and recovered catalyst was reused in five successive runs without significant loss in activity.Even in presence of triglyceride (vegetable oil) the catalyst was able to convert >98% free fatty acids into respective esters. The esterified oils were fruitfully employed, without any pre-neutralization and water washing, in homogeneous alkali catalyzed transesterification to achieve >98% fatty acid methyl ester (FAME) yield.     

Cobalt-free perovskite Ba0.95La0.05FeO3-δ as efficient and durable oxygen electrode for solid oxide electrolysis cells

Solid oxide electrolysis cells (SOECs) have been demonstrated as an efficient technique to improve energy utilization and alleviate the greenhouse effect. The commercialization of SOECs is limited by the oxygen electrodes, whose problems include high costs and unexpected degradation of cobalt/strontium. In this work, we systematically evaluated the oxygen evolution reaction (OER) performance of a cobalt-free and strontium-free material Ba_0.95La–FeO_3-δ (BLF) and the application of BLF as an oxygen electrode of SOECs by combining DFT calculation and experimental. We found that the BLF has excellent OER performance due to its low oxygen vacancy formation energies and oxygen adsorption energies on the surfaces. Under an applied electrolysis voltage of 1.5 V, the current density reaches 3.17 and 1.53 A cm⁻² at 850 °C with 50%H₂–50%H₂O and 50%H₂–50%CO₂, respectively. The superb stability of the electrolysis cell was shown in the 200 h testing, which further demonstrated that BLF is a promising material for oxygen electrodes of SOECs.     

In-depth study of the Ruddlesden-Popper LaxSr2−xMnO4±δ family as possible electrode materials for symmetrical SOFC

The Ruddlesden Popper (RP) manganites La_xSr_2?xMnO_4±δ with compositions 0.25 ≤ x ≤ 0.6 have been successfully synthesized as single phases by solid-state reaction in air. All those materials are not only stable in reducing atmosphere but they also maintain the K₂NiF₄-type structure with I4/mmm symmetry under redox cycling conditions with limited volume changes. The x = 0.5 phase was analyzed by in situ high temperature neutron powder diffraction (HTNPD), under flowing hydrogen, showing the formation of oxide-ion vacancies on the equatorial sites of the perovskite planes, during reduction process. The total electrical conductivity was optimized and found maximum for x = 0.5 with values of 35.6 S cm^?1 and 1.9 S cm^?1 at 800 °C in air and 3% H₂/Ar, respectively, what is judged to be sufficient for an active layer of symmetrical SOFC electrode. First Electrochemical Impedance Spectroscopy (EIS) measurements in both oxidizing and reducing conditions, using an YSZ electrolyte and a GDC buffer layer, are presented giving rise to promising values.     

Compositional effect on oxygen reduction reaction in Pr excess double perovskite Pr1+xBa1-xCo2O6-δ cathode materials

The kinetics of oxygen reduction reaction (ORR), being a prime requisite for electrode materials after the higher conductivity. Further, electrodes are observed to dissolute on reaction at triple phase boundary. However, the compositional effect on ORR is least understood. In order to inspect the ORR mechanism with substitution, a series of (1 + x) PrCoO₃ − (1 − x) BaCoO₃ (x = 0.2 to 1.0 with step of 0.2) compositions are prepared using conventional solid-state route method. The Rietveld refinement of X-ray diffractograms and specific heat curves confirms the formation of double phase comprising orthorhombic Pmmm phase corresponding to PrBaCo₂O_6-δ and Pnma phase corresponding to PrCoO₃ for x = 0.2 to 0.8 with well connected and porous microstructure. The triple phase boundary reactions suggest the formation of Co(OH)₃ along with H₂ gas on reaction of these composite electrodes with H₂O during electrochemical dissolution. However, chronoamperometric studies prove the suitability of x = 0.6 sample with higher ORR and liberation of H₂ gas at room temperature.     

Synthesis and electrochemical properties of Li[Li(1−2x)/3NixMn(2−x)/3]O2 as cathode materials for lithium secondary batteries

Layered Li[Li_(1−2x)/3Ni_xMn_(2−x)/3]O₂ materials with x=0.41, 0.35, 0.275 and 0.2 are synthesized by means of a sol–gel method. The layered structure is stabilized by a solid solution between LiNiO₂ and Li₂MnO₃. The discharge capacity increases with increasing lithium content at the 3a sites in the Li[Li_(1−2x)/3Ni_xMn_(2−x)/3]O₂. A Li[Li_0.2Ni_0.2Mn_0.6]O₂ electrode delivers discharge capacities of 200 and 240 mAh g⁻¹ with excellent cycleability at 30 and 55 °C, respectively.     

Synthesis and electrochemical characteristics of LiCrxNi0.5−xMn1.5O4 spinel as 5 V cathode materials for lithium secondary batteries

A series of electrochemical spinel compounds, LiCr_xNi_0.5−xMn_1.5O₄ (x=0, 0.1, 0.3), are synthesized by a sol–gel method and their electrochemical properties are characterized in the voltage range of 3.5–5.2 V. Electrochemical data for LiCr_xNi_0.5−xMn_1.5O₄ electrodes show two reversible plateaus at 4.9 and 4.7 V. The 4.9 V plateau is related to the oxidation of chromium while the 4.7 V plateau is ascribed to the oxidation of nickel. The LiCr_0.1Ni_0.4Mn_1.5O₄ electrode delivers a high initial capacity of 152 mAh g⁻¹ with excellent cycleability. The excellent capacity retention of the LiCr_0.1Ni_0.4Mn_1.5O₄ electrode is largely attributed to structural stabilization which results from co-doping (chromium and nickel) and increased theoretical capacity due to substitution of chromium.     

A-site Ba-deficiency layered perovskite EuBa1−xCo2O6−δ cathodes for intermediate-temperature solid oxide fuel cells: Electrochemical properties and oxygen reduction reaction kinetics

A-site Ba-deficiency layered perovskite oxides, EuBa_1?xCo₂O_6?δ (EB_1?xCO, x = 0.02 and 0.04), have been synthesized by a citric acid-ethylene diamine tetraacetic acid complexation sol-gel method, and evaluated as potential cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Room temperature powder X-ray diffraction patterns indicate that the EB_1?xCO oxides crystallize in an orthorhombic symmetry with space group Pmmm. Among all of components, EB_0.98CO exhibits a good chemical compatibility with Ce_0.9Gd_0.1O_1.95 (CGO) electrolyte, as evidenced by phase analysis of mixed EB_0.98CO-CGO after calcining at 950 °C for 12 h in air. Thermal expansion analysis gives an average thermal expansion coefficient of 16.7 × 10^?6 K^?1 for EB_0.98CO. Thermogravimetric measurement confirms the high oxygen nonstoichiometric characteristic of EB_0.98CO at elevated temperatures. The electrical conductivity values of EB_0.98CO exceed 300 S cm^?1 in the temperature range of 100–750 °C. When tested as cathode in IT-SOFCs, the polarization resistance of 0.107 Ω cm² and the overpotential of 10 mV at current density of 77 mA cm^?2 are achieved in the EB_0.98CO cathode at 700 °C in air. The EB_0.98CO cathode-based anode-supported single cell delivers the maximum power density of 505 mW cm^?2 at 700 °C. Finally the rate-limiting steps for oxygen reduction reaction at the EB_0.98CO cathode interface are determined to be the charge transfer reaction and gas-phase diffusion process.     

Effect of calcite/activated carbon-based post-combustion CO2 capture system in a biodiesel-fueled CI engine—An experimental study

The present study aims to reduce carbon dioxide (CO₂) emission from a CI engine using calcite/activated carbon-based post-combustion CO₂ capture system fueled with Calophyllum inophyllum biodiesel (B100). The tests were conducted in a two-cylinder CI engine used in tractors at different load conditions. The performance and emission parameters of diesel and B100 with and without calcite and activated carbon-based CO₂ capture system were studied. The results show that compared to diesel, CO₂ emission increased by 19% for B100 due to high fuel-bound oxygen and carbon. Higher NO emission with a slightly reduced smoke opacity is observed with B100 combustion. CO₂ emission is reduced with the CO₂ capture system for both diesel and B100. CO₂ emission is reduced by 11.5% and 7.3% for diesel with calcite and activated carbon, respectively, and reduced by 15.8% and 10.5% for B100 with calcite and activated carbon. Due to the adsorption capacity of both calcite and activated carbon, NO and smoke opacity are reduced considerably. The results display that calcite is better in reducing CO₂ compared to activated carbon-based CO₂ capture system. It is perceived that the combination of biofuel and calcite-based CO₂ capture system can both reduce engine-out emissions and cause a net negative CO₂ emission as it is renewable aiding in mitigation of global warming effects.     

Co-deficient PrBaCo2−xO6−δ perovskites as cathode materials for intermediate-temperature solid oxide fuel cells: Enhanced electrochemical performance and oxygen reduction kinetics

Co-deficient PrBaCo_2?xO_6?δ perovskites (x = 0, 0.02, 0.06 and 0.1) are synthesized by a solid-state reaction, and the effects of Co-deficiency on the crystal structure, oxygen nonstoichiometry and electrochemical properties are investigated. The PrBaCo_2?xO_6?δ samples have an orthorhombic layered perovskite structure with double c axis. The degree of oxygen nonstoichiometry increases with decreasing Co content (0 ≤ x ≤ 0.06) and then slightly decreases at x = 0.1. All the samples exhibit the electrical conductivity values of >300 S cm^?1 in the temperature range of 100–800 °C in air, which match well the requirement of cathode. With significantly enhanced electrochemical performance and good chemical compatibility between PrBaCo_2?xO_6?δ and CGO, this system of Co-deficient perovskite is promising cathode material for IT-SOFCs. Among all these components, PrBaCo_1.94O_6?δ gives lowest polarization resistance of 0.059 Ω cm² at 700 °C in air. When tested as cathode in fuel cell, the anode-supported Ni-YSZ|YSZ|CGO|PrBaCo_1.94O_6?δ cell delivers a maximum peak power density of 889 mW cm^?2 at 650 °C, which is higher than that of PrBaCoO_6?δ cathode-based cell (764 mW cm^?2). The oxygen reduction kinetics at the PrBaCo_1.94O_6?δ cathode interface is also explored, and the rate-limiting steps for oxygen reduction reaction are determined.     

Utilizing waste heat of the flue gas for post-combustion CO2 capture—A comparative study for different process layouts

The inlet flue gas entering the absorber column must be ~40°C and hence needs cooling. In this article, it is proposed that waste heat be recovered from the flue gas using a condensing heat exchanger. This recovered heat is utilized as partial supplement to subsequent heating in stripper during CO₂ capture. System layouts—one for base case and two others—have been conceptualized. ASPEN Plus^® simulation results for the other two layouts are discussed for energy savings with respect to the base case. Results show that, for the other two layouts, reboiler heat duty decreases though carbon capture efficiency also decreases.     

Synthesis and characterization of GO-PpPDA/Ni–Mn nanocomposite as a novel catalyst for methanol electrooxidation

The graphene oxide-poly (p-phenylene diamine) (GP) composite is synthesized through in-situ polymerization of p-phenylene diamine on GO sheets and used as an efficient support material for electrodeposition of Ni and Mn. The resulting GP/Ni–Mn catalyst shows high catalytic activity, stability and durability for methanol electrooxidation. The surface area of GP composite is calculated to be about 28% and 36% higher than GO and PpPDA, respectively. In addition, combining Ni and Mn demonstrated some synergetic effect for methanol electrooxidation. The electrochemical active surface area of GP/Ni–Mn is about 1.625 cm², which is much higher than GP/Ni and GP/Mn. GP/Ni–Mn nanocomposite presented 87.3% of the peak current after 5 h and almost 83.16% of the maximum current for 500 cycles. The excellent characteristics of this composite are attributed to high surface area, high electrochemical active surface area and fine distribution of metallic particles on the support material.     

Synthesis,characterization and electrochemical properties of La2-xEuxNiO4+δ Ruddlesden-Popper-type layered nickelates as cathode materials for SOFC applications

Eu doped La₂NiO₄ powders, with the general formula La_2-xEu_xNiO_4+δ denoted as LENO_x (for x = 0, 0.2, 0.4, 0.6 and 0.8), were synthesized via the mechanical milling reaction method. The Eu³⁺ doping content has a remarkable influence on structural and electrochemical properties. The phase identification and morphology were studied by X-ray diffraction (XRD), Raman spectroscopy, Infrared spectroscopy (IR), A laser size analyzer and scanning electron microscopy (SEM). Lattice parameters were calculated using the Rietveld method. It was observed that the lattice parameter values in LENO_x systems varied with the amount of Eu³⁺. The latter was symmetrically deposited by spin coating on both surfaces of an Ce_0.8Sm_0.2O_1.9 (SDC) electrolyte and studied using AC impedance spectroscopy. The electrochemical properties were studied using two-probe impedance spectroscopy and results showed that the ASR of LENO_x was enhanced by the Eu³⁺ dopant content x. Results also showed that LNEO_0.2 had the lowest Area specific resistance (ASR) at 700 °C and it was therefore concluded that doping with the appropriate amount of Eu³⁺ can further improve the properties of a nickelate cathode.     

Synthesis and characterization of Nanocrystalline Ba0·6Sr0·4Co0·8Fe0·2O3 for application as an efficient anode in solid oxide electrolyser cell

Nanocrystalline Ba_0·6Sr_0·4Co_0·8Fe_0·2O₃ (BSCF-6482) powder is synthesized by combustion synthesis technique. Powder calcined at 1000 °C reveals phase pure cubic perovskite. Transmission electron microscopic (TEM) analysis exhibits soft agglomerates of average size ∼50 nm wherein interplanar spacing for (110) and (221) resembles to the cubic lattice. While DC electrical conductivity of 23 S cm⁻¹@800 °C is observed, interfacial polarization measured by electrochemical impedance spectroscopy is found to be the least @850 °C (0.18 Ω cm²). Cell performance has been compared among BSCF-6482, BSCF-5582 and LSCF-6482 mixed ionic and electronic conducting (MIEC) and conventional electrode (LSM). Higher performance (1.37 A/cm²@1.3 V,800 °C) with high hydrogen generation rate (0.57 Nl/cm²/h) is found during steam electrolysis with cell fabricated using BSCF-6482 having minimal area specific resistance 0.33 Ω cm². Under similar operating condition, BSCF-5582, LSCF-6482 and LSM exhibit hydrogen generation rate of 0.35, 0.28 and 0.23 Nl/cm²/h respectively. Cell microstructure is clinically correlated with the higher reactivity of BSCF-6482 air electrode in steam electrolysis.     

Tuning oxygen vacancy of the Ba0·95La0·05FeO3−δ perovskite toward enhanced cathode activity for protonic ceramic fuel cells

Innovation of highly active cathode is of great significance to the development of protonic ceramic fuel cells (PCFCs). Herein, tailoring oxygen vacancies in Zn-doped Ba_0·95La_0·05FeO_3?δ (BLFZ) perovskite is proved to be beneficial for promoting the formation of proton defects. Hydration ability of the triple conducting BLFZ perovskites is confirmed by electrical conductivity relaxation (ECR). The results demonstrate that BLFZ exhibits a proton surface exchange coefficient of 1.34 × 10^?3 cm s^?1 at 600 °C, which greatly extends active sites from the electrolyte/cathode interface to the entire electrode. Mechanism and process elementary steps of the oxygen reduction reaction (ORR) of BLFZ-BaCe_0.7Zr_0·1Y_0.1Yb_0.1O_3?δ (BCZYYb) are detailedly studied. It is found that the rate-determining step of ORR is surface dissociative adsorption of oxygen on BLFZ-BCZYYb cathode. A maximum power density of 673 mW cm^?2 at 700 °C is achieved and BLFZ-BCZYYb based single-cell shows no obvious degradation at 600 °C for 200 h. The good performance is ascribed to the rapid proton diffusion of BLFZ-BCZYYb composite electrode by regulating the oxygen vacancies.