Effect of coatings on long term behaviour of a commercial stainless steel for solid oxide electrolyser cell interconnect application in H2/H2O atmosphere

K41X (AISI 441) stainless steel evidenced a high electrical conductivity after 3000 h ageing in H₂/H₂O side when used as interconnect for solid oxide electrolyser cells (SOEC) working at 800 °C. Perovskite (La_1 − xSr_xMnO_3 − δ) and spinel (Co₃O₄) oxides coatings were applied on the surface of the ferritic steel for ageing at 800 °C for 3000 h. Both coatings improved the behaviour of the steel and give interesting opportunities to use the K41X steel as interconnect for hydrogen production via high temperature steam electrolysis. Co₃O₄ reduced into Co leading to a very good Area Specific Resistance (ASR) parameter, 0.038 Ω cm². Despite a good ASR (0.06 Ω cm²), La_1 − xSr_xMnO_3 − δ was less promising because it partially decomposed into MnO and La₂O₃ during ageing in H₂/H₂O atmosphere.     

Reactive Spray Deposition Technology - An one-step deposition technique for Solid Oxide Fuel Cell barrier layers

In order to reduce the cost of the manufacturing of Solid Oxide Fuel Cells (SOFC), and to enable metal supported cell fabrication, a new fabrication method called Reactive Spray Deposition Technology (RSDT) for direct deposition of the material onto ceramic or metal support for low temperature SOFC is currently being developed. The present work describes the effect on the performance of a SOFC when a Gd_0.2Ce_0.8O_1.9 (GDC) layer has been introduced as diffusion barrier layer between the yttria stabilized zirconia (YSZ) electrolyte and the La_0.6Sr_0.4CoO_3−δ (LSC) cathode. The dense, thin and fully crystalline GDC films were directly applied by RSDT, without any post-deposition heating or sintering step. The quality of the film and performance of the cell prepared by RSDT was compared to a GDC blocking layer deposited by screen printing (SP) and then sintered. The observed ohmic resistance of the ASC with a GDC layer deposited by RSDT is 0.24 Ω cm², which is close to the expected theoretical value of 0.17 Ω cm² for a 5-μm thick 8 mol% yttria YSZ (8YSZ) electrolyte at 873 K.     

Electrochemical performances of NdBa0.5Sr0.5Co2O5+x as potential cathode material for intermediate-temperature solid oxide fuel cells

Layered perovskite oxide NdBa_0.5Sr_0.5Co₂O_5+x is investigated as a cathode material for intermediate-temperature solid oxide fuel cells. The NBSC cathode is chemically compatible with the electrolyte La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM) at temperatures below 1000 °C. It is metallic in nature and the maximum and minimum conductivities are 1368 S cm⁻¹ at 100 °C and 389 S cm⁻¹ at 850 °C. The area specific resistance (ASR) value for the NBSC cathode is as low as 0.023 Ω cm² at 850 °C. The electrolyte-supported fuel cell generates good performance with the maximum power density of 904, 774 and 556 mW cm⁻² at 850, 800 and 750 °C, respectively. Preliminary results indicate that NBSC is promising as a cathode for IT-SOFCs.     

High performance metal-supported intermediate temperature solid oxide fuel cells fabricated by atmospheric plasma spraying

The LSGM(La_0.8Sr_0.2Ga_0.8Mg_0.2O₃) electrolyte based intermediate temperature solid oxide fuel cells (ITSOFCs) supported by porous nickel substrates with different permeabilities are prepared by plasma spray technology for performance studies. The cell having a porous nickel substrate with a permeability of 3.4 Darcy, an LSCM(La_0.75Sr_0.25Cr_0.5Mn_0.5O₃) interlayer on the nickel substrate, a nano-structured LDC(Ce_0.55La_0.45O₂)/Ni anode functional layer, an LDC interlayer, an LSGM/LSCF(La_0.58Sr_0.4Co_0.2Fe_0.8O₃) cathode interlayer and an LSCF cathode current collector layer shows remarkable electric output power densities such as 1270 mW cm⁻² (800 °C), 978 mW cm⁻² (750 °C) and 702 mW cm⁻² (700 °C) at 0.6 V cell voltage under 335 ml min⁻¹ H₂ and 670 ml min⁻¹ air flow rates. SEM, TEM, EDX, AC impedance, voltage and power data with related analyses are presented here to support this high performance. The durability test of the cell with the best power performance shows a degradation rate of about 3% kh⁻¹ at the test conditions of 400 mA cm⁻² constant current density and 700 °C. Results demonstrate the success of APS technology for fabricating high performance metal-supported and LSGM based ITSOFCs.     

Performance of (La,Sr)(Co,Fe)O3−x double-layer cathode films for intermediate temperature solid oxide fuel cell

In this study the performance evaluation of (La,Sr)(Co,Fe)O_3−x (LSCF) double-layer films characterized by impedance spectroscopy between 403 and 603 °C to be used for intermediate temperature solid oxide fuel cells (IT-SOFCs) is presented. Two LSCF layers with different microstructures were sequentially deposited onto Ce_0.9Gd_0.1O_1.95 (CGO) substrates in a symmetrical fashion. A first layer of La_0.6Sr_0.4Co_0.2Fe_0.8O_3−x with a thickness of 7 μm and a nano-scaled particle size was deposited by electrostatic spray deposition (ESD) technique. Different deposition conditions were used in preparing the ESD films to evaluate the influence of film morphology on the electrochemical performance. After annealing, a current collector layer of La_0.58Sr_0.4Co_0.2Fe_0.8O_3−x with ∼45 μm in thickness and a larger particle size was deposited by screen printing. Area specific resistances (ASRs) were determined from impedance spectroscopy measurements performed in air between 403 and 603 °C, at 25 °C steps. A dependence of electrochemical performance on the morphology of the LSCF layer deposited by ESD was observed. The lowest ASR, measured during 130 h of isothermal dwelling at 603 °C, averaged 0.13 Ω cm² with negligible variation and is the lowest reported value for this composition, to the best of our knowledge. Reported results assure an excellent suitability of this type of assembly for IT-SOFCs.     

Improvement of (La0.74Bi0.10Sr0.16)MnO3–Bi1.4Er0.6O3 composite cathodes for intermediate-temperature solid oxide fuel cells

Porous composite cathodes including (La_0.74Bi_0.10Sr_0.16)MnO_3−δ (LBSM) and Bi_1.4Er_0.6O₃ (ESB) were fabricated and characterized using AC impedance spectroscopy. In our earlier work, the growth and aggregation of ESB particles were found in LBSM–ESB composite cathodes. In this study, therefore, two approaches were used to restrain the growth and aggregation of ESB particles. First, the sintering temperature of the composite cathode was reduced by introducing a sintering function layer, which caused a 22% reduction in the initial polarization resistance (R), but the cathode polarization resistance decreased at a rate of 2.15 × 10⁻⁴ Ω cm² h⁻¹ at 700 °C during a period of 100 h. Second, nano-sized Gd-doped ceria powder (CGO) was added to the composite cathode system. Stability improvement was achieved at 10 vol% CGO, and the degradation rate at 700 °C was 4.01 × 10⁻⁵ Ω cm² h⁻¹ during a period of 100 h.     

A new anode material for intermediate solid oxide fuel cells

A new anode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) with a composite of La_0.7Sr_0.3Cr_1−xNi_xO₃ (LSCN), CeO₂ and Ni has been synthesized. EDX analysis showed that 1.19 at% Ni was doped into the perovskite-type La_0.7Sr_0.3CrO₃ and Ce could not be detected in the perovskite phases. Results showed that the fine CeO₂ and Ni were highly dispersed on the La_0.7Sr_0.3Cr_1−xNi_xO₃ substrates after calcining at 1450 °C and reducing at 900 °C. The thermal expansion coefficient (TEC) of the as-prepared anode material is 11.8 × 10⁻⁶ K⁻¹ in the range of 30–800 °C. At 800 °C, the electrical conductivity of the as-prepared anode material calcined at 1450 °C for 5 h is 1.84 S cm⁻¹ in air and 5.03 S cm⁻¹ in an H₂ + 3% H₂O atmosphere. A single cell with yttria-stabilized zirconia (YSZ, 8 mol% Y₂O₃) electrolyte and the new materials as anodes and La_0.8Sr_0.2MnO₃ (LSM)/YSZ as cathodes was assembled and tested. At 800 °C, the peak power densities of the single cell was 135 mW cm⁻² in an H₂ + 3% H₂O atmosphere.     

Effect of unsintered gadolinium-doped ceria buffer layer on performance of metal-supported solid oxide fuel cells using unsintered barium strontium cobalt ferrite cathode

In this study, a Gd_0.1Ce_0.9O_1.95 (GDC) buffer layer and a Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF) cathode, fabricated without pre-sintering, are investigated (unsintered GDC and unsintered BSCF). The effect of the unsintered GDC buffer layer, including the thickness of the layer, on the performance of solid oxide fuel cells (SOFCs) using an unsintered BSCF cathode is studied. The maximum power density of the metal-supported SOFC using an unsintered BSCF cathode without a buffer layer is 0.81 W cm⁻², which is measured after 2 h of operation (97% H₂ and 3% H₂O at the anode and ambient air at the cathode), and it significantly decreases to 0.63 W cm⁻² after 50 h. At a relatively low temperature of 800 °C, SrZrO₃ and BaZrO₃, arising from interaction between BSCF and yttria-stabilized zirconia (YSZ), are detected after 50 h. Introducing a GDC interlayer between the cathode and electrolyte significantly increases the durability of the cell performance, supporting over 1000 h of cell usage with an unsintered GDC buffer layer. Comparable performance is obtained from the anode-supported cell when using an unsintered BSCF cathode with an unsintered GDC buffer layer (0.75 W cm⁻²) and sintered GDC buffer layer (0.82 W cm⁻²). When a sintered BSCF cathode is used, however, the performance increases to 1.23 W cm⁻². The adhesion between the BSCF cathode and the cell can be enhanced by an unsintered GDC buffer layer, but an increase in the layer thickness (1-6 μm) increases the area specific resistance (ASR) of the cell, and the overly thick buffer layer causes delamination of the BSCF cathode. Finally, the maximum power densities of the metal-supported SOFC using an unsintered BSCF cathode and unsintered GDC buffer layer are 0.78, 0.64, 0.45 and 0.31 W cm⁻² at 850, 800, 750 and 700 °C, respectively.     

Synthesis and performance of Sr1.5LaxMnO4 as cathode materials for intermediate temperature solid oxide fuel cell

A-site non-stoichiometric materials Sr_1.5La_xMnO₄ (x = 0.35, 0.40, 0.45) are prepared via solid state reaction. The structure of these materials is determined to be tetragonal. Both the lattice volume and the thermal expansion coefficient reduce with the decrease of lanthanum content. On the contrary, the conductivity increases and the maximum value of 13.9 S cm⁻¹ is found for Sr_1.5La_0.35MnO₄ at 750 °C in air. AC impedance spectroscopy and DC polarization measurements are used to study the electrode performance. The optimum composition of Sr_1.5La_0.35MnO₄ results in 0.25 Ω cm² area specific resistance (ASR) at 750 °C in air. The oxygen partial pressure measurement indicates that the charge transfer process is the rate-limiting step of the electrode reactions.     

La substituted Sr2MnO4 as a possible cathode material in SOFC

Sr_2−xLa_xMnO_4+δ (x = 0.4, 0.5, 0.6) oxides were studied as the cathode material for solid oxide fuel cells (SOFC). The reactivity tests indicated that no reaction occurred between Sr_2−xLa_xMnO_4+δ and CGO at annealing temperature of 1000 °C, and the electrode formed good contact with the electrolyte after being sintered at 1000 °C for 4 h. The total electrical conductivity, which has strong effect on the electrode properties, was determined in a temperature range from 100 to 800 °C. The maximum value of 5.7 S cm⁻¹ was found for the x = 0.6 phase at 800 °C in air. The cathode polarization and AC impedance results showed that Sr_1.4La_0.6MnO_4+δ exhibited the lowest cathode overpotential. The area specific resistance (ASR) was 0.39 Ω cm² at 800 °C in air. The charge transfer process is the rate-limiting step for oxygen reduction reaction on Sr_1.4La_0.6MnO_4+δ electrode.     

Palladium and ceria infiltrated La0.8Sr0.2Co0.5Fe0.5O3−δ cathodes of solid oxide fuel cells

La_0.8Sr_0.2Co_0.5Fe_0.5O_3−δ (LSCF) cathodes infiltrated with electrocatalytically active Pd and (Gd,Ce)O₂ (GDC) nanoparticles are investigated as high performance cathodes for the O₂ reduction reaction in intermediate temperature solid oxide fuel cells (IT-SOFCs). Incorporation of nano-sized Pd and GDC particles significantly reduces the electrode area specific resistance (ASR) as compared to the pure LSCF cathode; ASR is 0.1 Ω cm² for the reaction on a LSCF cathode infiltrated with 1.2 mg cm⁻² Pd and 0.06 Ω cm² on a LSCF cathode infiltrated with 1.5 mg cm⁻² GDC at 750 °C, which are all significantly smaller than 0.22 Ω cm² obtained for the reaction on a conventional LSCF cathode. The activation energy of GDC- and Pd-impregnated LSCF cathodes is 157 and 176 kJ mol⁻¹, respectively. The GDC-infiltrated LSCF cathode has a lower activation energy and higher electrocatalytic activity for the O₂ reduction reaction, showing promising potential for applications in IT-SOFCs.     

Electrochemical characterisation of solid oxide cell electrodes for hydrogen production

Oxygen electrodes and steam electrodes are designed and tested to develop improved solid oxide electrolysis cells for H₂ production with the cell support on the oxygen electrode. The electrode performance is evaluated by impedance spectroscopy testing of symmetric cells at open circuit voltage (OCV) in a one-atmosphere set-up. For the oxygen electrode, nano-structured La_0.75Sr_0.25MnO₃ (LSM25) is impregnated into a LSM25/yttria stabilised zirconia (YSZ) composite, whereas for the steam electrode, nano-structured Ni and Ce_0.8Gd_0.2O_2−δ (CGO) is impregnated into a Sr_0.94Ti_0.9Nb_0.10O_3−δ (STN) backbone. In the present study, the best performing oxygen electrode is a LSM25-YSZ composite with 20% porosity and impregnated with a LSM25 solution measuring a polarisation resistance (R_p) of 0.12 Ω cm² at 850 °C in oxygen. For the steam electrode, the best performance is obtained for a STN backbone, sintered at 1200 °C and impregnated with CGO/Ni, with an R_p of 0.08 Ω cm² at 850 °C in 3% H₂O/H₂.     

La2NiO4+δ potential cathode material on La0.9Sr0.1Ga0.8Mg0.2O2.85 electrolyte for intermediate temperature solid oxide fuel cell

La₂NiO_4+δ, a mixed ionic-electronic conducting oxide with K₂NiF₄ type structure, has been studied as cathode material with La_0.9Sr_0.1Ga_0.8Mg_0.2O_2.85 (LSGM) electrolyte for intermediate solid oxide fuel cells (IT-SOFCs). XRD results reveal excellent chemical compatibility between the La₂NiO_4+δ sample and LSGM electrolyte.A single cell (0.22 cm² active area) was fabricated with La₂NiO_4+δ as cathode, Ni-Sm_0.2Ce_0.8O_1.9 (2:1; w/w) as anode and LSGM as electrolyte. A thin buffer layer of Sm_0.2Ce_0.8O_1.9 (SDC) between anode and electrolyte was used to avoid possible interfacial reactions. The cell was tested under humidified H₂ and stationary air as fuel and oxidant, respectively. The electrochemical behaviour was evaluated by means of current-voltage curves and impedance spectroscopy. Microstructure and morphology of the cell components were analysed by SEM-EDX after testing.The maximum power densities were 160, 226, and 322 mW cm⁻² at 750, 800 and 850 °C, respectively with total polarisation resistances of 0.77, 0.48 and 0.31 Ω cm² at these temperatures. Cell performance remained stable when a current density of 448 mA cm⁻² was demanded for 144 h at 800 °C, causing no apparent degradation in the cell. The performance of this material may be further improved by reducing the electrolyte thickness and optimisation of the electrode microstructure.     

A novel bilayered Sr0.6La0.4TiO3/La0.8Sr0.2MnO3 interconnector for anode-supported tubular solid oxide fuel cell via slurry-brushing and co-sintering process

Considering that conventional lanthanum chromate (LaCrO₃) interconnector is hard to be co-sintered with green anode, we have fabricated a novel bilayered interconnector which consists of La-doped SrTiO₃ (Sr_0.6La_0.4TiO₃) and Sr-doped lanthanum manganite (La_0.8Sr_0.2MnO₃). Sr_0.6La_0.4TiO₃ is conductive and stable in reducing atmosphere, locating on the anode side; while La_0.8Sr_0.2MnO₃ is on the cathode side. A slurry-brushing and co-sintering method is applied: the Sr_0.6La_0.4TiO₃ and La_0.8Sr_0.2MnO₃ slurries are successively brushed onto green anode specimen, followed by co-firing course to form a dense bilayered Sr_0.6La_0.4TiO₃/La_0.8Sr_0.2MnO₃ interconnector. For operating with humidified hydrogen and oxygen at 900 °C, the ohmic resistances between anode and cathode/interconnector are 0.33 Ω cm² and 0.186 Ω cm², respectively. The maximum power density is 290 mW cm⁻² for a cell with interconnector, and 420 mW cm⁻² for a cell without it, which demonstrates that nearly 70% of the power output can be achieved using this bilayered Sr_0.6La_0.4TiO₃/La_0.8Sr_0.2MnO₃ interconnector.     

Enhanced performance of a single-chamber solid oxide fuel cell with an SDC-impregnated cathode

The electrochemical performance of anode-supported single-chamber solid oxide fuel cells (SC-SOFCs) with and without SDC-impregnated cathodes was compared in a diluted methane–oxygen mixture. These cells were made of conventional materials including yttrium-stabilized zirconia (YSZ) thin film, a Ni + YSZ anode and a La_0.7Sr_0.3MnO₃ (LSM) cathode. Our results showed that the cell performance was greatly enhanced with the SDC-impregnated LSM cathode. At a furnace temperature of 750 °C, the maximum power density was as high as 404 mW cm⁻² for a CH₄ to O₂ ratio of 2:1, which was 4.0 times higher than the cell with a pure LSM cathode (100 mW cm⁻²). The overall polarization resistance of the impregnated cell was 1.6 Ω cm², which was much smaller than that of the non-impregnated one (4.2 Ω cm²). The impregnation introduced SDC nanoparticles greatly extended the electrochemical active zone and hence greatly improved the cell performance.     

A mixed proton, oxygen ion, and electron conducting cathode for SOFCs based on oxide proton conductors

A composite cathode, consisting of Ba(Zr_0.1Ce_0.7Y_0.2)O_3−δ (BZCY) and La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF), has shown high catalytic activity toward oxygen reduction, demonstrating a peak power density of 855 mW cm⁻² at 750 °C. The chemical compatibility between BZCY and LSCF is excellent since there was no evidence of chemical reaction between the two after being fired at 1100 °C for 10 h. The stability of the composite cathode is further shown in single cells operated at 750 and 600 °C for 100 h without observable degradation in performance.     

Low-temperature ceria-electrolyte solid oxide fuel cells for efficient methanol oxidation

Low temperature anode-supported solid oxide fuel cells with thin films of samarium-doped ceria (SDC) as electrolytes, graded porous Ni-SDC anodes and composite La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF)-SDC cathodes are fabricated and tested with both hydrogen and methanol fuels. Power densities achieved with hydrogen are between 0.56 W cm⁻² at 500 °C and 1.09 W cm⁻² at 600 °C, and with methanol between 0.26 W cm⁻² at 500 °C and 0.82 W cm⁻² at 600 °C. The difference in the cell performance can be attributed to variation in the interfacial polarization resistance due to different fuel oxidation kinetics, e.g., 0.21 Ω cm² for methanol versus 0.10 Ω cm² for hydrogen at 600 °C. Further analysis suggests that the leakage current densities as high as 0.80 A cm⁻² at 600 °C and 0.11 A cm⁻² at 500 °C, resulting from the mixed electronic and ionic conductivity in the SDC electrolyte and thus reducing the fuel efficiency, can nonetheless help remove any carbon deposit and thereby ensure stable and coking-free operation of low temperature SOFCs in methanol fuels.     

Study of steam electrolysis using a microtubular ceramic reactor

Steam electrolysis was carried out using a microtubular ceramic reactor with the following cell configuration: La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF)–Ce_0.8Gd_0.2O_1.9 (CGO) electrode/CGO buffer layer/(ZrO₂)_0.89(Sc₂O₃)_0.1(CeO₂)_0.01 (ScSZ) electrolyte/Ni-ScSZ electrode supporting tube. 10% H₂/Ar gas was used as steam carrier gas, and 18% steam was supplied to the ceramic reactors. The cell performance was as follows: 1.43 V at 0.1 A cm⁻² and 650 °C (Area specific resistance: 4.7 Ω cm²) or 1.37 V at 0.1 A cm⁻² and 700 °C (4.3 Ω cm²). During steam electrolysis, hydrogen production proportionally increased with current density according to Faraday's law, and heat generation at a low current density was observed by an electrochemical technique. Voids and Zr diffusion from the ScSZ electrolyte were confirmed in the CGO buffer layer. Such factors near the surface probably influenced the increase in ohmic loss and electrode polarization.     

On the synthesis and performance of flame-made nanoscale La0.6Sr0.4CoO3−δ and its influence on the application as an intermediate temperature solid oxide fuel cell cathode

Flame spray synthesis (FSS), a large-scale powder processing technique is used to prepare nanoscale La_0.6Sr_0.4CoO_3−δ powder for solid oxide fuel cell cathodes from water-based nitrate solutions. Influence of processing is investigated on basis of the as-synthesised powders by X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA), nitrogen adsorption (BET) and electron microscopy (SEM and TEM).Against the background of a nanostructured cathode morphology for an intermediate temperature solid oxide fuel cell (IT-SOFC) at 600 °C, an optimised and high surface area flame-made La_0.6Sr_0.4CoO_3−δ nanopowder of 29 m² g⁻¹ is used to investigate its performance and chemical reaction with common electrolytes (Y_0.16Zr_0.84O_2−δ, Ce_0.9Gd_0.1O_2−δ and Sc_0.20Ce_0.01Zr_0.79O_2−δ). Secondary phase analysis from XRD measurements revealed a substantially lower La₂Zr₂O₇ and SrZrO₃ formation in comparison to conventional spray pyrolysed and submicron powder of about 9 m² g⁻¹. TGA and resistivity measurements proofed that La_0.6Sr_0.4CoO_3−δ is non-sensitive towards carbonate formation under CO₂ containing atmospheres. Electronic bulk conductivity of 2680 S cm⁻¹ (600 °C) and 3340 S cm⁻¹ (500 °C) were measured in air and as function of oxygen partial pressure (2 × 10⁵ Pa > p(O₂) > 1.2 × 10⁻² Pa) in the temperature range between 400 and 900 °C. Electrochemical performance is determined by impedance spectroscopy on symmetrical cells of screen printed nanoscale La_0.6Sr_0.4CoO_3−δ on Ce_0.9Gd_0.1O_2−δ substrates from which an area specific resistance (ASR) of 0.96 Ω cm² at 600 °C and 0.14 Ω cm² at 700 °C were obtained.     

NiMn2O4 spinel as an alternative coating material for metallic interconnects of intermediate temperature solid oxide fuel cells

In an effort to improve the performance of SUS 430 alloy as a metallic interconnect material, a low cost and Cr-free spinel coating of NiMn₂O₄ is prepared on SUS 430 alloy substrate by the sol-gel method and evaluated in terms of the microstructure, oxidation resistance and electrical conductivity. A oxide scale of 3-4 μm thick is formed during cyclic oxidation at 750 °C in air for 1000 h, consisting of an inner layer of doped Cr₂O₃ and an outer layer of doped NiMn₂O₄ and Mn₂O₃; and the growth of Cr₂O₃ and formation of MnCr₂O₄ are depressed. The oxidation kinetics obeys the parabolic law with a rate constant as low as 4.59 × 10⁻¹⁵ g² cm⁻⁴ s⁻¹. The area specific resistance at temperatures between 600 and 800 °C is in the range of 6 and 17 mΩ cm². The above results indicate that NiMn₂O₄ is a promising coating material for metallic interconnects of the intermediate temperature solid oxide fuel cells.