Investigating the electrochemical performance of Nd1-xSrxCo0.8Fe0.2O3−δ (0 ≤ x ≤ 0.85) as cathodes for intermediate temperature solid oxide fuel cells

Perovskite-type structure oxides with the nominal chemical composition Nd_1-xSr_xCo_0.8Fe_0.2O_3−δ (0 ≤ x ≤ 0.85) (NSCF) were synthesized by solid-state method to investigate the effect of Sr-doping on the crystal structure and electrochemical performance in the intermediate temperature range of 600 °C–750 °C. The electrical conductivity of the sintered NSCF pellets was found to be in the range of 300–1000 S cm⁻¹. All the NSCF compositions showed a transition from semiconducting to metallic behavior with an increase in temperature. NSCF showed reactivity with the La_0.8Sr_0.2Ga_0.8Mg_0.2O_3−δ (LSGM) electrolyte. The electrochemical performance was tested by preparing the symmetrical cells with the configuration 70 wt% NSCF +30 wt% LSGM using LSGM electrolyte in the temperature range of 650–800 °C. AC-impedance results showed a decrease in polarization resistance (Rp) of the cathode with increase in Sr-doping due to increase in electrical conductivity. Among the samples studied, composite electrode of Nd_0.3Sr_0.7Co_0.8Fe_0.2O_3−δ – LSGM showed the lowest area specific resistance (ASR) of 0.1 Ω cm² at 750 °C in air. It was chosen to investigate the effect of pO₂ on the electrochemical performance of the cathode to determine the rate determining step (RDS) in oxygen reduction reaction (ORR). Dissociation of molecular oxygen into oxygen atoms seems to be the RDS in the ORR.     

Performance and optimization of perovskite-type La1·4Ca0·6CoMnO5+δ cathode for intermediate-temperature solid oxide fuel cells

There has been a considerable interest in improving electrocatalytical activity of doped lanthanum manganite and thermal stability of cobaltite cathodes. In the current work, a perovskite-type oxide La_1·4Ca_0·6CoMnO_5+δ (LCCM), as a combination of manganite and cobaltite perovskites, is developed as a potential cathode for intermediate-temperature solid oxide fuel cells. The LCCM has a monoclinic structure and highly structural stability at RT-900 °C. The LCCM exhibits good chemical compatibility and relatively matched thermal expansion coefficient with the La_0·9Sr_0.1Ga_0.8Mg_0·2O_3–δ (LSGM) and Sm_0.2Ce_0·8O_1.9 (SDC) electrolytes up to 1000 °C. The mixed valence states of Co^2+/3+ and Mn^3+/4+ coexist in the LCCM. The LCCM exhibits a typical p-type semiconducting behavior, and the sample sintered at 1300 °C possesses the highest conductivity of 223 S cm⁻¹ at 800 °C. The maximum power density of NiO-SDC/SDC/LSGM/LCCM single cell is 445 mW cm⁻² at 800 °C. The electrochemical performance, thermal expansion behavior and stability of LCCM are further improved by adding appropriate amounts of SDC. The LCCM-30 wt% SDC composite cathode shows the best electrochemical performance: the area specific resistance is decreased by 68% at 800 °C, and the maximum power density is increased by 22%.     

Highly conductive proton-conducting electrolyte with a low sintering temperature for electrochemical ammonia synthesis

BaCe_0·7Zr_0.1Gd_0.2O_3-δ (BCZG) powder is synthesized by a citrate sol-gel method, and different amounts of Li₂CO₃ are introduced to lower the sintering temperature. The densification temperature of BCZG ceramic is decreased drastically to 1250 °C by using Li₂CO₃ as sintering aid. BCZG with 2.5 wt% of Li₂CO₃ (BCZG-2.5L) can not only remarkably promote the sintering process of BCZG but also enhance its electrical conductivity. The total ionic conductivity of BCZG-2.5L attains to 1.9 × 10⁻² S cm⁻¹ at 600 °C in a wet H₂ atmosphere. Ammonia synthesis at atmospheric pressure is conducted on (2K, 10Fe)/Ni-BCZG | BCZG-2.5L | Ni-BCZG electrolytic cell with an applied voltage of 0.2–1.6 V at a temperature of 450–600 °C. The highest NH₃ formation rate of 1.87 × 10⁻¹⁰ mol s⁻¹ cm⁻² and the highest current efficiency of 0.53% is achieved at 500 °C with an applied voltage of 0.8 V.     

Preparation and characterization of high temperature Sr(Ce0.6Zr0.4)0.9Y0.1O3-δ/YBaCo2O5+δ mixed proton-electron composite membrane

In this study, the various Sr(Ce_0.6Zr_0.4)_0.9Y_0.1O_3-δ/YBaCo₂O_5+δ (SCZY/YBCO) composite ceramic membranes were prepared by sintering at different temperatures and used as proton membranes for hydrogen permeation. SCZY and YBCO powders were prepared by the citrate-ethylenediaminetetraacetic acid sol-gel process and solid-state reaction method, respectively. The chemical reaction, structure, morphology, thermal expansion, and electrical conductivity of SCZY/YBCO were investigated through X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermal mechanical analyzer (TMA) and direct current four-probe method. The relative sintered density of SCZY/YBCO membrane sintered at 1250 °C was as high as 99.5%. The conductivity of the SCZY/YBCO increased with the sintering temperature. The SCZY/YBCO sample sintered at 1250 °C exhibited the highest conductivity of 13.44 S/cm at 800 °C. The H₂ permeability of the SCZY/YBCO membrane was 3.83 mL min⁻¹ cm⁻², much higher than that of SCZY at 800 °C (1.37 mL min⁻¹ cm⁻²).     

Polyvinyl alcohol-induced low temperature synthesis of CeO2-based powders

Ce_0.8Sm_0.2O_1.9 (SDC) powders have been synthesized by a combustion method with polyvinyl alcohol (PVA) as the fuel and nitrate as oxidizer. A calcination temperature of 350 °C was found to be sufficient for the formation of pure SDC powders. The cell parameters were calculated using the peak positions determined from the XRD patterns, and it was found that stoichiometric SDC powder could be obtained only when stoichiometric PVA fuel contents were used. The as-prepared SDC pellets exhibited 98% of the theoretical density sintered at 1300 °C. This shows that the SDC powders obtained by this combustion method have excellent sintering properties, which can densified at a relatively low sintering temperature. The powders made by this method, due to its high conductivity of 0.033 S cm⁻¹ at 700 °C, are suitable for intermediate temperature solid oxide fuel cells (IT-SOFCs).     

Low-temperature sintering and electrical properties of strontium- and magnesium-doped lanthanum gallate with V2O5 additive

The effects of a V₂O₅ additive on the low-temperature sintering and ionic conductivity of strontium- and magnesium-doped lanthanum gallate (LSGM: La_0.8Sr_0.2Ga_0.8Mg_0.2O_2.8) are studied. The LSGM powders prepared by the glycine nitrate method are mixed with 0.5-2 at.% of VO_5/2 and then sintered at 1100-1400 °C in air for 4 h. The apparent density and phase purity of the LSGM specimens are increased with increasing sintering temperature and VO_5/2 concentration due to the enhanced sintering and mass transfer via the intergranular liquid phase. The 1 at.% VO_5/2-doped LSGM specimen sintered at 1300 °C exhibits a high oxide ion conductivity of ∼0.027 S cm⁻¹ at 700 °C over a wide range of oxygen partial pressure (PO₂=10⁻²⁷−1 atm), thereby demonstrating its potential as a useful electrolyte for anode-supported solid oxide fuel cells (SOFCs) without the requirement for any buffer layer between the electrolyte and anode.     

Behavior of lanthanum-doped ceria and Sr-, Mg-doped LaGaO3 electrolytes in an anode-supported solid oxide fuel cell with a La0.6Sr0.4CoO3 cathode

Anode-supported solid oxide fuel cells (SOFCs) with lanthanum-doped ceria (LDC)/Sr-, Mg-doped LaGaO₃ (LSGM) bilayered or LDC/LSGM/LDC trilayered electrolyte films were fabricated with a pure La_0.6Sr_0.4CoO₃ (LSC) cathode. The behaviors of the two electrolytes in cells were investigated by using scanning electron microscopy, impedance spectroscopy and cell performance measurements. The reactions between LSGM and anode material can be suppressed by applying a ca. 15 μm LDC film. Due to the Co diffusion from the LSC cathode to the LSGM electrolyte during high temperature sintering, the electronic conductivity of the LDC electrolyte cannot be completely blocked with an LSGM layer below 50 μm, which leads to open-circuit potentials of these cells of ca. 0.988 V at 800 °C. The electrical conductivities of LDC and LSGM electrolytes in the cells under operation conditions are obtained from the dependence of the cell ohmic resistance on the electrolyte thickness. The electrical conductivity of LDC electrolyte is ca. 0.117 S cm⁻¹ at 800 °C on the bilayered electrolyte cells with a 50 μm LSGM layer. The bilayer electrolyte cells with a 25 μm LDC layer at 800 °C, had a cell ohmic resistance two-stage linear dependence on the LSGM layer thickness, which showed the electrical conductivity of ca. 1.9 S cm⁻¹ for the LSGM layer below 50 μm and 0.22 S cm⁻¹ for the LSGM layer above 100 μm. With a LDC/LSGM/LDC trilayered electrolyte film for the anode-supported cell, an open-circuit potential of 1.043 V was achieved.     

Influence of rare-earth doping on the phase composition,sinterability, chemical stability and conductivity of BaHf0.8Ln0.2O3-δ (Ln = Yb,Y, Dy,Gd) proton conductors

BaHf_0.8Ln_0.2O_3-δ doped with rare earth elements with different ionic radii (Ln = Yb, Y, Dy and Gd) as candidate materials for solid oxide fuel cells and H₂ separation membrane have been prepared. Their phase composition, sinterability, chemical stability and conductivity were studied systematically. The rare earth elements are successfully incorporated into the main phase crystal lattice of barium hafnate to generate a single perovskite phase. The relative density of all samples sintered at 1600 °C reaches above 90%, and Y-doped BaHfO₃ has the highest relative density (94.7%) and the biggest grain size (about 1 μm) among all samples. The conductivities of the samples firstly increase and then decrease with the increase of the doped ion radius. Among all samples the conductivity of BaHf_0.8Y_0.2O_3-δ is the highest and reaches 6.02 × 10⁻³ S cm⁻¹ in wet air at 700 °C, which is attributed to the good sinterability and suitable crystal structure (tolerance factor and free volume). All samples also show excellent chemical stability in the test atmospheres, including saturated H₂O steam, pure H₂ and CO₂, 200 ppm H₂S/Ar and boiling water. The Pt/BaHf_0.8Y_0.2O_3-δ electrolyte/Pt single cell was fabricated with a 530 μm-thick disk and its electrochemical properties were tested. The peak power density reaches 10.21 mW cm⁻² at 700 °C, which is comparable to similar fuel cells reported. These results suggest that BaHf_0.8Y_0.2O_3-δ is a promising electrolyte candidate for proton-conducting fuel cells.     

High-performance solid oxide fuel cells with fiber-based cathodes for low-temperature operation

Low-temperature operation of solid oxide fuel cells (SOFCs) results in deterioration in electrochemical performance due to sluggish oxygen reduction reaction (ORR) at the cathode. To enhance the reaction pathway for ORR, La_0.8Sr_0.2MnO₃ (LSM) nanofibers were fabricated by electrospinning and used for low-temperature solid oxide fuel cells operated at 600–700 °C. The morphological and structural characteristics show that the electrospun LSM nanofiber has a highly crystallized perovskite structure with a uniform elemental distribution. The average diameter of the LSM nanofiber after sintering is 380 nm. A symmetric cell of nanofiber-based LSM cathode on scandia-stabilized zirconia (SSZ) electrolyte pellet exhibits much lower area specific resistances compared to commercial LSM powder-based cathode. A single cell based on the nanofiber LSM cathode on yttrium-doped barium cerate-zirconia (BCZY) electrolyte exhibits a power density of 0.35 Wcm⁻² at 600 °C, which increases to 0.85 Wcm⁻² at 700 °C. The cell has an area specific resistance (ASR) of 0.46 Ωcm² at 600 °C, which decreases to 0.07 Ωcm² at 700 °C. The results indicate that the LSM electrode fabricated by the electrospinning process produces a nanostructured porous electrode which optimizes the microstructure and significantly enhances the ORR at the cathode of SOFCs.     

Zr doped BaFeO3-δ as a robust electrode for symmetrical solid oxide fuel cells

A BaFe_0.9Zr_0.1O_3-δ (BFZ) is successfully synthesized and its characteristics are investigated. The oxide exhibits high stability and a cubic perovskite structure in a reducing atmosphere. A La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-δ (LSGM) supported symmetrical solid oxide fuel cell (SOFC) with BFZ electrode demonstrates a maximum power density of 1097 mW cm⁻² using humidified H₂ as the fuel and ambient air as the oxidant at 800 °C. And as low as 0.190 Ω cm² of polarization resistance of single cell is observed at 650 °C. Moreover, the electrode demonstrates high stability in 100 h test, as well as redox stability in both oxidizing and reducing atmospheres. The high electrochemical property and good stability suggest that the BFZ is promising candidate for symmetrical SOFC electrode.     

Innovative processing of dense LSGM electrolytes for IT-SOFC's

This paper reports for the first time the attempted synthesis of SrO- and MgO-doped LaGaO₃ (La_1−xSr_xGa_1−yMg_yO_3−0.5(x+y), LSGM) perovskite by an aqueous ‘regenerative’ solution route. This novel technique enabled recycling of the undesired product and subsequently yielded product with much better phase purity and density than that obtained from the solid-state route. La_0.8Sr_0.2Ga_0.85Mg_0.15O_2.825 (LSGM-2015) and LaGaO₃ were prepared using both the regenerative sol–gel (RSG) and conventional solid-state route at 1400 °C. Series of La_0.8Sr_0.2Ga_0.83Mg_0.17O_2.815 (LSGM-2017) pellets were also prepared by the RSG method at different sintering temperature (1200–1500 °C) and time. The effect of conventional and microwave sintering of samples obtained from both solid-state and regenerative route was also investigated. Microwave heating was carried out using SiC as a microwave susceptor. The LSGM pellets prepared by using different synthetic methods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and pellet density was determined by pycnometry. The LSGM-2015 prepared by RSG route exhibited conductivity σ_t = 0.066 and 0.029 S cm⁻¹ at 800 and 700 °C, respectively, and activation energy of the bulk, grain-boundary, and total are E_b = 0.97 eV, E_gb = 1.03 eV and E_t = 1.01 eV, respectively. The sintering temperature severely affected the grain size (<0.1–10 μm) and also the grain-boundary resistance (3–175 kΩ). The unique aspect of this RSG technique is that the final product can be recycled which makes the process cost effective and time saving compared to the solid-state ceramic technique and this technique would allow optimization of processing parameters in a cost effective and time saving manner for obtaining well sintered LSGM as an electrolyte for IT-SOFC's.     

Mn-rich SmBaCo0.5Mn1.5O5+δ double perovskite cathode material for SOFCs

SmBaCo_0.5Mn_1.5O_5+δ oxide with Sm-Ba cation-ordered perovskite-type structure is synthesized and examined in relation to whole RBaCo_0.5Mn_1.5O_5+δ series (R: selected rare earth elements). Presence of Sm and 3:1 ratio of Mn to Co allows to balance physicochemical properties of the composition, with moderate thermal expansion coefficient value of 18.70(1)·10⁻⁶ K⁻¹ in 300–900 °C range, high concentration of disordered oxygen vacancies in 600–900 °C range (δ = 0.16 at 900 °C), and good transport properties with electrical conductivity reaching 33 S cm⁻¹ at 900 °C in air. Consequently, the compound enables to manufacture catalytically-active cathode, with good electrochemical performance measured for the electrolyte-supported laboratory-scale solid oxide fuel cell with Ni-Gd_1.9Ce_0.1O_2-δ|La_0.4Ce_0.6O_2-δ|La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ|SmBaCo_0.5Mn_1.5O_5+δ configuration, for which 1060 mW cm⁻² power density is observed at 900 °C. Furthermore, the tested symmetrical SmBaCo_0.5Mn_1.5O_5+δ|La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ|SmBaCo_0.5Mn_1.5O_5+δ cell delivers 377 mW cm⁻² power density at 850 °C, which is a promising result.     

Electrochemical performance and distribution of relaxation times analysis of tungsten stabilized La0·5Sr0·5Fe0·9W0·1O3-δ electrode for symmetric solid oxide fuel cells

W-doped La_0·5Sr_0·5Fe_0·9W_0·1O_3-δ (LSFW) was prepared and evaluated as a symmetric electrode for solid oxide fuel cells (SSOFCs). Phase and structural stability of LSFW under both reducing and oxidizing atmospheres was studied. The oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) mechanisms were investigated by using electrochemical impedance spectra (EIS) and distribution of relaxation times (DRT). Electrode polarization resistance (R_p) of LSFW are 0.08 and 0.16 Ω cm² in air and wet hydrogen at 800 °C, respectively. DRT results indicate that the rate-limiting step of LSFW at 800 °C in cathodic conditions and anodic conditions are related to oxygen diffusion and hydrogen adsorption/diffusion, respectively. A La_0·8Sr_0.2Ga_0.8Mg_0·2O_3-δ (LSGM) electrolyte-supported single cell using LSFW electrodes shows a maximum power density of 617.3 mW cm⁻² at 800 °C with considerable stability and reversibility, which enables LSFW a promising SOFCs symmetric electrode material.     

Preparation of La0.8Sr0.2Ga0.83Mg0.17O2.815 powders by microwave-induced poly(vinyl alcohol) solution polymerization

A new and simple chemical route, named microwave-induced poly(vinyl alcohol) (PVA) solution polymerization, has been used to prepare fine, homogeneous and high-density pellets of purer La_0.8Sr_0.2Ga_0.83Mg_0.17O_2.815 (denoted as LS_0.2GM_0.17). The effect of different contents of PVA as the polymeric carrier, was studied and we obtained an optimal amount of PVA (1.65:1 ratio of positively charged valences of the cations (Meⁿ⁺) to negatively charged hydroxyl (–OH⁻) groups of the organics), which could ensure homogenous distribution of the metal ions in the polymeric network structure and inhibit segregation. The behavior of the powder after calcination at different temperatures was studied. The PVA solution process consumed less organic material compared with the Pechini process, and consequently PVA was a more effective carrier in the preparation of LSGM. Higher heating rate and a more homogenous heating manner without thermal gradients in the microwave oven resulted in fewer secondary phases in the LS_0.2GM_0.17 powder after calcination at 1400 °C for 9 h and a smaller pellet grain size (2–3 μm) without segregation. The density of LS_0.2GM_0.17 pellet sintered at 1400 °C for 9 h was 6.19 g cm⁻³.     

Sintering and electrical properties of Ce0.8Y0.2O1.9 powders prepared by citric acid-nitrate low-temperature combustion process

Ce_0.8Y_0.2O_1.9 nanopowders were prepared using a citric acid-nitrate low-temperature combustion process. The effect of pH value of the solutions on the ionization of citric acid and the chelating of metal ions was studied. It was found that when the pH value of the solutions was bigger than 6, the citric acid was completely ionized and the stable complexes were formed between rare earth metal ions and the citric acid. Then the stable gels were obtained. The effect of the amount of oxidants (Φ) on the combustion fashions and combustion reaction time of the gels, the properties of the as-synthesized powders, the sintering behavior of the as-synthesized powders and the conductivity of the sintered pellets was also investigated. The results showed that the green density, sintered density and the ionic conductivity of the specimens increased with Φ. When Φ was equal to 1.5, the powders with good dispersion and compressibility were obtained, and the green density of the powders was 52.5%. The relative density of the sintered sample was over 95% at 1350 °C for 4 h and the conductivity of the sintered specimen was 0.034 S cm⁻¹ at 700 °C.     

Fluorine doping as a feasible method to enhancing functional properties of Ce0.8Sm0.2O1.9 electrolyte

In this work, materials with a fluorite structure of the Ce_0.8Sm_0.2O_1.9-(3х)/2F_3х series are obtained and studied for the first time. The synthesis method has been developed based on the solid-phase interaction of SmF₃ with a highly dispersed precursor obtained in reactions of solution combustion synthesis (SCS) of cerium and samarium nitrates with a mixture of glycine and citric acid. The materials in the range of 0.01 = x ≤ 0.1 possess a cubic structure (Fm-3m space group), the unit cell parameter decreases according to the size factor. The Raman spectra study shows that for Ce_0.8Sm_0.2O_1.9 the main Raman peak is described by the sum of two components with maxima at 460.5 cm⁻¹, FWHM = 28.1 cm⁻¹ and at 484.5 cm⁻¹, FWHM = 18.3 cm⁻¹. After the introduction of fluorine, the third component appears at ∼461.2 cm⁻¹ with a much smaller FWHM equal to12.1 cm⁻¹. Thus, the Raman spectra analysis allows the presence of fluorine in the fluorite-like materials including sintered ceramics to be identified. The conductivity maximum (3.7 mS cm⁻¹ at 600 °C, E_a = 0.95 eV) and the maximal electrolyte domain boundary value (1.58 × 10⁻²² atm) is reached at x = 0.10 of fluorine content, which generally determines the prospects for the fluorine-doped material application in the SOFC technology.     

In situ sinterable cathode with nanocrystalline La0.6Sr0.4Co0.2Fe0.8O3−δ for solid oxide fuel cells

A nanocrystalline powder with a lanthanum based iron- and cobalt-containing perovskite, La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF), is investigated for solid oxide fuel cell (SOFC) applications at a relatively low operating temperature (600-800 °C). A LSCF powder with a high surface area of 88 m² g⁻¹, which is synthesized via a complex method with using inorganic nano dispersants, is printed onto an anode supported cell as a cathode electrode. A LSCF cathode without a sintering process (in situ sintered cathode) is characterized and compared with that of a sintering process at 780 °C (ex situ sintered cathode). The in situ sintered SOFC shows 0.51 A cm⁻² at 0.9 V and 730 °C, which is comparable with that of the ex situ sintered SOFC. The conventional process for SOFCs, the ex situ sintered SOFC, including a heat treatment process after printing the cathodes, is time consuming and costly. The in situ sinterable nanocrystalline LSCF cathode may be effective for making the process simple and cost effective.     

Investigation of structural,electrical and electrochemical properties of La0.6Sr0.4Fe0.8Mn0.2O3-δ as an intermediate temperature solid oxide fuel cell cathode

La_0.6Sr_0.4Fe_0.8Mn_0.2O₃ (LSFM) compound is synthesized by sol-gel method and evaluated as a cathode material for the intermediate temperature solid oxide fuel cell (IT-SOFC). X-ray diffraction (XRD) indicates that the LSFM has a rhombohedral structure with R-3c space group symmetry. The XRD patterns reveal very small amount of impurity phase in the LSFM and Y₂O₃-stabilized ZrO₂ (YSZ) mixture powders sintered at 600, 700, 800 and 850 °C for a week. The maximum electrical conductivity of LSFM is about 35.35 S cm⁻¹ at 783 °C in the air. The oxygen chemical diffusion coefficients, D_Chem, are increased from 1.39 × 10⁻⁶ up to 1.44 × 10⁻⁵ cm² s⁻¹. Besides, the oxygen surface exchange coefficients, k_Chem, are obtained to lie between 2.9 × 10⁻³ and 1.86 × 10⁻² cm s⁻¹ in a temperature range of 600–800 °C. The area-specific resistances (ASRs) of the LSFM symmetrical cell are 7.53, 1.53, 1.13, 0.46 and 0.31 Ω cm² at 600, 650, 700, 750 and 800 °C respectively, and related activation energy, E_a, is about 1.23 eV.     

Fast ion channels for crab shell-based electrolyte fuel cells

Biomaterials possess abundant micro and macrospores in their microstructures, which can be functionalized as higher ion-transport channels. Herein we report calcined crab shell (CCS) forming nanocomposites with La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF) perovskite as functional electrolytes for low temperature solid oxide fuel cells (LTSOFCs). The single CCS electrolyte fuel cell achieved open circuit voltage (OCV) at 0.9 V and a peak power density of 70 mW cm⁻² at 550 °C; while the highest OCV of 1.21 V and a maximum power density of 440 mW cm⁻² were achieved for the CCS-LSCF (40 wt. % LSCF) electrolyte fuel cell. The results are attributed to the ion channel construction and interface effect built in the CCS-LSCF composite. This work may provide a new strategy to develop novel biomaterial-based materials for LTSOFCs.     

Microwave sintering of high-performance BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) electrolytes for intermediate-temperature solid oxide fuel cells

As a promising electrolyte material for solid oxide fuel cells (SOFCs), BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δ (BZCYYb) often surfers from its high sintering temperature, which causes Ba evaporation and sluggish grain growth, thus reducing the electrical conductivity. In this work, densified BZCYYb electrolytes were fabricated at temperatures as low as 1400 °C using the microwave sintering technique. Comparing with the conventional sintered ones, a temperature decrease of 150 °C is achieved. The Ba evaporation is effectively suppressed, and large grain sizes of ～4 μm are obtained. The total conductivity for microwave sintered symmetric cell measured in wet air at 700 °C is 3.8 × 10^?2 S cm^?1, benefiting from both enhanced bulk conductivities by 1–2 times and grain boundary conductivities by 50 times. With the microwave sintered BZCYYb as electrolyte, an anode-supported cell reaches a maximum power density of 0.64 W cm^?2 at 700 °C.