Area Specific Resistance Values Research Articles

Synthesis and properties of Sr doped Pr2NiO4 cathode material for intermediate temperature solid oxide fuel cells

A series of cathode materials of Pr2-xSrxNiO4 (x = 0, 0.3, 0.5, 0.7, 1, 1.5) are synthesized by the EDTA-citric acid route. The results show that the Pr1.7Sr0.3NiO4, Pr1.5Sr0.5NiO4, Pr1.3Sr0.7NiO4 and PrSrNiO4 exhibit excellent structural stability and carbon dioxide resistance, and also exhibit good chemical compatibility and thermal matching with the SDC electrolyte. It is also found that the Sr doping is beneficial in improving the high temperature conductivity of Pr2-xSrxNiO4. At 800 °C, the electrical conductivity of Pr1.5Sr0.5NiO4 and Pr1.3Sr0.7NiO4 reaches 185 S cm−1 and 317 S cm−1, respectively. In addition, the area-specific resistance (ASR) value increases significantly with Sr doping, which reduces the catalytic activity of the material. Acceptable ASR values are obtained for Pr1.5Sr0.5NiO4 and Pr1.3Sr0.7NiO4, with ASR values of 0.079 Ω cm2 and 0.082 Ω cm2 at 800 °C, respectively. Additionally, the most interesting result is the ASR value obtained after high-temperature thermal decomposition of Pr2NiO4, where Pr2NiO4* (decomposed) has the lowest ASR value of only 0.027 Ω cm2 at 800 °C, showing the best catalytic activity. The maximum power densities of Pr2-xSrxNiO4 (x = 0.5 and 0.7) and Pr2NiO4* are found to be 515, 430, and 548 mW cm−2 at 800 °C, respectively. These results show that when the Sr doping amount is less than 1.5, the stability of the Pr2-xSrxNiO4 cathode material can be effectively improved, but its catalytic performance is partially sacrificed.

Optimizing Bilayer Electrolyte Thickness Ratios for High-Performing Low-Temperature Solid Oxide Fuel Cells

Abstract Bilayer electrolytes for low-temperature solid oxide fuel cells (LT-SOFCs) offer the potential for higher power density by lowering the ohmic area specific resistance (ASR) and increasing the open circuit voltage (OCV) of mixed ionic/electronic conducting (MIEC) type electrolyte (e.g., GDC). However, optimizing the bilayer electrolyte thickness ratio is essential to achieve high power densities at low-temperatures (650-500℃). Herein we provide a systematic study of GDC/YCSB bilayer thickness ratios on anode-supported LT-SOFCs. In all cases the bilayer maximum power density (MPD) is higher than single-layer GDC based cells with reduced ohmic ASR values. Specifically, a high MPD of ~1 W/cm2 at 650℃ was achieved on a GDC(20 μm)/YCSB(12 μm) bilayer electrolyte based SOFC, which is 62% higher than single-layer GDC based SOFC (0.64 W/cm2) operating on humidified H2 as fuel. Such enhancement is due to the 9.3% improvement in OCV and 36% reduction in ohmic ASR values with the addition of the YCSB layer. The reduction in ohmic ASR of the bilayer electrolyte SOFCs is due to an increase of GDC electrical conductivity caused by the lower pO2 at the YCSB/GDC interface which must be considered in optimizing the thickness ratio of the bilayer electrolyte for achieving higher power density LT-SOFCs.

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.

Comparative Analysis of LiCo0.6Sr0.4O2 Cathode Electrochemical Performance in Oxide- and Proton-Conducting Intermediate-Temperature Solid Fuel Oxide Cells

Solid fuel oxide cells (SOFCs) are made up of three main parts: anode, electrolyte, and cathode. The main challenge in SOFCs is their high operating temperature, which can reach 1000 °C and lead to cell degradation issues. To address this, the utilization of lithium-based materials is suggested for the cathode component, facilitating intermediate-temperature SOFC operation within the temperature range of 500 to 800 °C. Previous studies have demonstrated the potential of producing high-quality lithium-based cathode ink using a triple-roll mill (TRM). By employing the fabrication parameters recommended in these studies, the lithium-based cathode (LCSO) was tested in different working environments, specifically the oxide-conducting SOFC and proton-conducting SOFC. The LCSO inks were screen-printed on SDC for oxide-conducting SOFC and BCZY for proton-conducting SOFC electrolyte before the analysis. Electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) are used to characterize the electrochemical performance and morphology of the LCSO cathode. Based on the results, the LCSO cathode is found to respond well in oxide-conducting SOFC environment with an area-specific resistance (ASR) value of 0.75 ohms-cm2 compared to proton-conducting SOFC which shows an ASR value higher by 11.45 ohms-cm2.

Electrochemical performance of Pr0.6Sr0.4Fe0.8Co0.2O3−δ as potential cathode material for IT-SOFC

Solid oxide fuel cells (SOFCs) are renowned for being effective energy sources that have potential to influence how energy is developed in future. SOFCs operate at low temperatures provides different benefits for widespread commercialization. In the present study a perovskite material Pr0.6Sr0.4Fe0.8Co0.2O3−δ (PSFCo) was investigated as cathode for SOFC in intermediate temperature range. Glycine nitrate process was used for the preparation of the samples. PSFCo exhibited cubic structure having small particle size (100–200 nm). The electrical conductivity of the PSFCo was measured as function of temperature up to 850 ℃. The sample displayed maximum electrical conductivity of 370 Scm−1 at around 550–600 ℃. The polarization behavior of PSFCo was calculated by means of AC impedance with Sm0.8Ce0.2O2 (SDC) as electrolyte. The value of area specific resistance (ASR) was calculated as 0.146 Ωcm2 at 800 ℃ and 0.248 Ωcm2 at 700 ℃.

Effects of Mn concentration on durability of Fe-Cr ferritic steels dispersed with La2O3 for solid oxide fuel cell interconnects

This study investigates the effect of Mn concentration in La2O3-dispersed ferritic steel on the oxidation behavior, area-specific resistance (ASR), and chromium volatilization for solid oxide fuel cell (SOFC) interconnects. The results show that increasing Mn concentrations lead to a gradual increase in the oxidation rate of the alloy samples. The alloy with 0.3 wt% Mn primarily forms Cr2O3 during the initial oxidation stage, whereas the alloys containing more than 1.0 wt% Mn promote the growth of (Mn,Cr)3O4, leading to an accelerated oxidation rate. The ASR value exhibits a decreasing trend initially, followed by an increasing trend, as the Mn concentration in the alloy increases from 0.3 to 2.0 wt%. The alloy with 1.0 wt% Mn shows the lowest ASR value of 12.2 mΩ cm2 after 1000 h. The alloys demonstrate a tendency to reduce chromium volatilization as the Mn concentration increases, which can be attributed to the growth of (Mn,Cr)3O4 at the topmost layer of the oxide. The study suggests that controlling the Mn concentration in the Fe-Cr alloys can help in reducing the ASR values and Cr volatilization, making the ferritic steel alloy with 1.0 wt% Mn an effective choice for SOFC interconnects.

Pathway to high performance, low temperature thin-film solid oxide cells grown on porous anodised aluminium oxide

Reversible solid oxide cells (rSOCs) present a promising solution to future energy challenges through the efficient conversion between electrical and chemical energy. To date, the benefits of rSOC technology have been off-limits to portable power and electrolysis applications due to the excessive polarisation resistance of the oxygen electrode at low temperatures, characterised by high area specific resistance (ASR) values below 500 °C. In this work we demonstrate growth of symmetric and complete rSOC structures based on state-of-the-art vertically aligned nanocomposite (VAN) films grown by pulsed laser deposition (PLD) on porous Pt-coated anodised aluminium oxide (AAO) substrates. The symmetric rSOC structures give the first demonstration of an rSOC oxygen electrode with ASR below 0.1 Ωcm2 at temperatures less than 450 °C. This is achieved through oxygen vacancy tuning by annealing, as confirmed by Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA) and Rutherford Backscattering Spectrometry (RBS) measurements. Thus, the present work describes a promising route towards future high-performance rSOC devices for portable power applications.

Nickel-doped NdBa0.5Sr0.5Co1.5Fe0.5O5+δ oxygen electrode material for high performance reversible protonic ceramic cells

To enhance the electrocatalytic activity in the oxygen reduction and the evolution reactions of air electrode materials, we fabricate a double perovskite structured NdBa0.5Sr0.5Co1.5Fe0.5-xNixO5+δ with triple-conducting properties for reversible protonic ceramic cells (RPCCs). In particular, Ni doping into B-site (of ABO3 perovskite structure) is used to tailor the surface properties and bulk diffusion of NdBa0.5Sr0.5Co1.5Fe0.5O5+δ perovskites. Among the various amounts of dopants, doping with 5 mol% Ni significantly increases the activity of oxygen electrodes in moist air, including the conductivity of protons and oxygen-ions. The area specific resistance (ASR) values of the NdBa0.5Sr0.5Co1.5Fe0.45Ni0.05O5+δ (NBSCFN5) electrode in the BaZr0.1Ce0.7Y0.1Yb0.1O3-δ electrolyte are 0.70 Ω·cm2 at 650 ℃. The electrical conductivity of NBSCFN5 is 423–714 S·cm−1 at the RPCCs operating temperature (500–700 ℃), which is significantly higher than that of the conventional perovskite air electrode materials. Furthermore, the ASR of the NBSCFN5 symmetrical cell decreases considerably from 9.02 to 6.86 Ω·cm2 in dry air to pH2O = 0.6 atm at 550 ℃, implying its excellent proton conduction. This suggests that NBSCFN5 is a promising air electrode material for next-generation high-performance RPCCs at lower temperatures.

(Digital Presentation) (La0.7-xNdx )Sr0.3Co1-YFeyO3- δ (x = 0.35, y = 0.2) a Novel Perovskite Type Air Electrode Material for Protonic Conducting Solid Oxide Cell (H-SOC)

Proton conducting solid oxide cell (H-SOC) is a highly efficient energy conversion device converting electrical energy into hydrogen by splitting water using solid oxide proton conductor at intermediate temperature range (500-700 0C) [1]. To enhance electrochemical performances in terms of efficient hydrogen generation, robust and durable air electrode materials are required to facilitate faster water oxidation and oxygen reduction reaction, which are the key steps for both electrolyser and fuel cell at a lower temperature [2-3]. In the present study, we have developed ‘La’ and ‘Nd’ A-site co-doped strontium cobaltite and cobalt ferrite: La0.35Nd0.35Sr0.3Co0.8Fe0.2O3-δ(LNSCF) a perovskite type cathode material exhibiting higher electrical and electrochemical performances. The electrical and O2- ion conductivity of the material shows metallic nature, and the highest conductivity values are 973 S cm-1 and 0.318 S cm-1 respectively at 400 oC. The higher value of electrical and ionic conductivity is attributed to highly efficient Co2+ to Co3+ and Fe3+ to Fe4+ transition. Electrochemical impedance spectroscopy analysis of the symmetrical cell (LNSCF/Zirconium and Yttrium doped Barium Cerate (BZCY)/LNSCF) revealed the value of Area Specific Resistance (ASR) to be 0.14, 0.47 and 3.06 Ω cm2 at 800,700 and 600 oC respectively. When operated in H-SOFC mode with humidified hydrogen as fuel and Air (3%H2O) as oxidant, the LNSCF based single cell: Ni-BZCY/BZCY (385m)/ LNSCF+BZCY achieves a maximum current density of 522, 383, and 231mA/cm2 at 800, 700, and 600 oC, respectively at 0.002 V. Whereas, in H-SOEC mode a maximum current density of -1380, -862 and -517 mA/cm2 are obtained at 800, 700, and 600 oC, respectively at 2.5 V. The contribution of different ions (O2- and H2+) and electrons (e-) in the electrochemical performances are evaluated using ion-blocking cells. The figure (1) below represents the Current Density versus Voltage (i-V) characteristic attributes for both H-SOFC and H-SOEC.

Micropatterned Ion-Exchange Membranes for Membrane Capacitive Deionization

US Marine missions require technologies that produce potable water from various water sources that include both seawater and ground water. Reverse osmosis (RO) is the most wide-spread and economical process for desalinating water from seawater. However, it is only cost-competitive and practical when deployed in large, centralized production facilities and is not conducive for marine squad units. Membrane capacitive deionization (MCDI) is an alternative water desalination platform that is enticing to military missions as it does not require high pressure piping and it does not generate significant acoustic, thermal, or electromagnetic signals. MCDI removes ions from the liquid solution using electrical energy, and the commercialized variant, flow-by MCDI, feature two porous electrodes covered by ion-exchange membranes(1). During deionization, the positively biased electrode has an anion exchange membrane (AEM) in front of it while the negatively biased electrode contains a cation exchange membrane (CEM) in front of it.Our previous research improved the energy efficiency of MCDI by using ion-exchange membranes with lower area-specific resistance (ASR) values(2) and porous ionic conductors in the spacer channel that augment solution conductivity and curtail ohmic losses(3). Reducing these resistances enabled the MCDI to operate at higher current density – which is important for shrinking the size of the MCDI unit and lowering the overall capital costs.This talk highlights our recent work examining ionic charge transport resistance at the membrane-electrode interface in MCDI. We studied the impact of this resistance on MCDI performance metrics (salt removal and energy normalized adsorbed salt (ENAS)) by systematically changing the interfacial area of the ion-exchange membrane-electrode interface via patterning of the ion-exchange membrane surfaces using soft-lithography. This strategy has been shown to be effective in reducing charge-transfer resistances in both proton exchange membrane (PEM)(4) and AEM(5) fuel cells and reducing the water dissociation kinetics resistance in bipolar membranes(6). Micropatterned AEMs and CEMs based upon poly(arylene ether) and all-carbon poly(arylene) backbones(7) were fabricated with periodic line and cylinder topographies and lateral feature sizes that vary from 2 to 20 μm. The patterned membranes were coated with graphitic carbon electrodes. It is posited that smaller lateral feature sizes, which gives rise to larger interfacial area values, reduces interfacial resistance values in MCDI and larger ENAS values. Keywords: Desalination, Membrane capacitive deionization, Ion exchange membranes, Soft lithography, Energy normalized adsorbed salt, Membrane electrode assembly References S. Porada, L. Zhang and J. E. Dykstra, Desalination, 488, 114383 (2020).V. M. Palakkal, J. E. Rubio, Y. J. Lin and C. G. Arges, ACS Sustainable Chemistry & Engineering, 6, 13778 (2018).V. M. Palakkal, M. L. Jordan, D. Bhattacharya, Y. J. Lin and C. G. Arges, Journal of The Electrochemical Society, 168, 033503 (2021).Y. Jeon, D. J. Kim, J. K. Koh, Y. Ji, J. H. Kim and Y.-G. Shul, Scientific Reports, 5, 16394 (2015).S. Jang, M. Her, S. Kim, J.-H. Jang, J. E. Chae, J. Choi, M. Choi, S. M. Kim, H.-J. Kim, Y.-H. Cho, Y.-E. Sung and S. J. Yoo, ACS Applied Materials & Interfaces, 11, 34805 (2019).S. Kole, G. Venugopalan, D. Bhattacharya, L. Zhang, J. Cheng, B. Pivovar and C. G. Arges, Journal of Materials Chemistry A, 9, 2223 (2021).W.-H. Lee, Y. S. Kim and C. Bae, ACS Macro Letters, 4, 814 (2015).

Optimizing Bilayer Electrolyte Thickness Ratios for High Performing Low-Temperature Solid Oxide Fuel Cells

Over the last several years, significant developments have been made in bilayer electrolytes (e.g. GDC(Ce0.9Gd0.1O2-δ)/ESB((Er0.20Bi0.80O1.5)) suitable for low-temperature operating solid oxide fuel cells (SOFCs). Such bilayer electrolytes offer the potential for developing high performing LT-SOFCs by lowering the ohmic area specific resistance (ASR), and by improving the open circuit voltage (OCV) of mixed ionic/electronic conducting (MIEC) type electrolyte (e.g., GDC). However, optimizing the thickness ratio of the bilayer electrolyte is essential to achieve high power densities at low-temperatures (650-500 ℃). Here, we made a systematic study by varying the thickness ratios between GDC and YCSB((Bi0.75Y0.25)1.86Ce0.14O3±δ) bilayer electrolytes on an anode-supported LT-SOFCs, in all cases, the maximum power density (MPD) of the bilayer electrolyte cells is higher than pristine GDC based cells with reduced ohmic ASR values. Specifically, a high MPD of ~1 W/cm2 at 650 ℃ was achieved on a GDC(20μm) / YCSB(12μm) bilayer electrolyte based SOFC, which is 62% higher than pristine GDC based SOFC (0.64 W/cm2) operating on humidified H2 as fuel. Such enhancement is due to the 9.3% improvement in OCV (from 0.791 to 0.865 V) and a considerable 36% reduction in ohmic ASR values (from 0.094 to 0.069 Ω.cm2). Such reduction in ohmic ASR of the GDC/YCSB bilayer electrolyte SOFCs is due to the increase of GDC electrical conductivity as a result of lower pO2 at the interface of YCSB and GDC, and hence, must be considered in optimizing the thickness ratio of the bilayer electrolyte for achieving higher power density SOFCs. Figure 1

Thermal plasma synthesis of (La,Sr)CoO3-(La,Sr)2CoO4 composite cathodes for intermediate temperature solid oxide fuel cells (IT-SOFC)

(La,Sr)CoO3 and (La,Sr)2CoO4 dual phase powders were synthesized via thermal plasma to be used as cathodes for intermediate temperature solid oxide fuel cells (IT-SOFC). This covered pure (La,Sr)CoO3 as well as the composites where the fraction of (La,Sr)2CoO4 was gradually increased reaching the mid-composition. Powders, all synthesized in the same condition, were extremely small in size, especially at mid-composition where they were close to 30 nm in size. Area specific resistance (ASR) determined from the symmetric cell imply improved cathodic performance at the mid-composition. Taking ASR = 0.15 Ω∗cm2 as benchmark, it was found that the (La,Sr)CoO3: (La,Sr)2CoO4 = 0.53:0.47 cathode may be used at temperatures close 750 °C. Measurements taken from several runs however imply that the cathode performance was not stable and ASR values increases with cycling. This was attributed to the powder form of the cathode which would be expected to coarsen rapidly due to accelerated surface diffusion.

Optimizing Bilayer Electrolyte Thickness Ratios for High Performing Low-Temperature Solid Oxide Fuel Cells

Over the last several years, significant developments have been made in bilayer electrolytes (e.g. GDC(Ce0.9Gd0.1O2-δ)/ESB((Er0.20Bi0.80O1.5)) suitable for low-temperature operating solid oxide fuel cells (SOFCs). Such bilayer electrolytes offer the potential for developing high performing LT-SOFCs by lowering the ohmic area specific resistance (ASR), and by improving the open circuit voltage (OCV) of mixed ionic/electronic conducting (MIEC) type electrolyte (e.g., GDC). However, optimizing the thickness ratio of the bilayer electrolyte is essential to achieve high power densities at low-temperatures (650-500 ℃). Here, we made a systematic study by varying the thickness ratios between GDC and YCSB((Bi0.75Y0.25)1.86Ce0.14O3±δ) bilayer electrolytes on an anode-supported LT-SOFCs, in all cases, the maximum power density (MPD) of the bilayer electrolyte cells is higher than pristine GDC based cells with reduced ohmic ASR values. Specifically, a high MPD of ~1 W/cm2 at 650 ℃ was achieved on a GDC(20μm) / YCSB(12μm) bilayer electrolyte based SOFC.

Experimental review of the performances of protective coatings for interconnects in solid oxide fuel cells

Ferritic stainless steel interconnects are used in solid oxide fuel cells; however, coatings are required to improve their performance. Although several types of coatings have been proposed, they have been scarcely investigated under similar conditions. This study compares the characteristics of uncoated Crofer 22 APU and eight different coatings on Crofer 22 APU for up to 3000 h at 800 °C. The coatings were deposited at various research laboratories around the world, and the experiments were performed at Chalmers University of Technology, Sweden. Cross-sections of the samples were analysed using scanning electron microscopy and energy-dispersive x-ray spectroscopy. The (Co,Mn)-based coated steels showed more than 50-fold lower chromium evaporation and at least 3 times thinner Cr2O3 scale thickness compared to uncoated steel. The coated steel samples showed lower area-specific resistance (ASR) values than the uncoated steel after 3000 h of exposure, irrespective of the coating thickness, composition and deposition method.

Evaluation of perovskite-type contact paste materials for reversible solid oxide fuel cell stacks

At the electrode/interconnect interface in reversible solid oxide fuel cells (RSOFC), a contact paste is applied during stack fabrication. Careful selection of a contact paste material (CPM) is essential for improving the robustness of the RSOFC stack. For the successful industrialization of RSOFC technology, development of optimized CPM is required. Herein, three lanthanum-based perovskite compositions, LaNi0.6Fe0.2Cu0.2O3-δ (LNFCu), LaNi0.6Fe0.3Cr0.1O3-δ (LNFCr), and LaNi0.5Co0.2Cu0.3O3-δ (LNCCu) were investigated as air electrode CPMs employed in between Crofer 22 APU interconnect (IC) and La0.3Ca0.7Fe0.7Cr0.3O3-δ (LCFCr) electrode. More specifically, the three candidates were screened for thermal expansion coefficient (TEC), chemical compatibility with adjacent stack components, area specific resistance (ASR), and their performance as an air electrode CPM in a symmetrical LCFCr RSOFC. All three materials show good chemical compatibility with both the IC and LCFCr, excellent match of TEC with cell components, as well as markedly low ASR values. Most notably, from electrochemical impedance spectroscopy (EIS) study, LNFCr, and LNCCu CPMs exhibit polarization resistance values (Rp), at 800 °C, of ca. 0.83 Ω cm2, which is comparable to that of Au (0.63 Ω cm2), a material commonly regarded as the state-of-the-art. Of the three CPMs studied, it was concluded that LNFCr is the best candidate.

Effects of roller speed on the structural and electrochemical properties of LiCo0.6Sr0.4O2 cathode for solid oxide fuel cell application

The solid oxide fuel cell (SOFC) is one of the most anticipated green and sustainable energy technologies. Numerous considerations and ongoing studies into the basic elements of technology make its commercialization challenging, especially since a particular functional reaction necessitates a system with a certain microstructure. For instance, the microstructure can be modified by improving the oxidation reduction process to form cathode material (ORR). The glycine nitrate combustion technique produces LiCo0.6Sr0.4O2 (LCSO) cathodes and the slurry production is characterized by the aim of decreasing the area specific resistance (ASR) of the symmetrical cell and accelerating the ORR process for application in IT-SOFCs. Then, a predefined process with the triple roll milling technique is used to alter the process character, producing slurries/inks of differing characteristics. Field emission scanning electron microscopy (FESEM) analysis of the surface and cross section showed the uniformity and strong adhesion of the film to the substrate. When the speed parameter was varied between 300 and 500 rpm, the lowest ASR value of 16.17 Ω cm2 was obtained using the LCSO ink processed at 300 rpm. In addition, this study validates the importance of processing technique as a key parameter discovered by the study for optimizing the electrochemical performances.

Basic properties of low thermal expansion coefficient (Y0.5Ca0.5)1−xInxBaCo3ZnO7+δ (x=0, 0.1, 0.2, 0.3) solid solutions for solid oxide fuel cell cathode materials

• A series of YCI x BCZ cathodes have been studied systematically. • Thermal expansion coefficients of YCI x BCZ are lower than some cobalt-containing cathodes. • The YCI x BCZ cathodes show active catalysis on oxygen reduction reaction. • The YCI 0.2 BCZ cathode displays excellent phase stability and CO 2 tolerance. In this investigation, In-doped (Y 0.5 Ca 0.5 ) 1−x In x BaCo 3 ZnO 7+δ (x=0, 0.1, 0.2, and 0.3, abbreviated as YCI x BCZ) swedenborgite oxides are successfully prepared, and the effects of In-doping on phase structure, electrical conductivity, TEC, thermal stability and electrochemical properties are investigated thoroughly. The partial substitution of In for Y and Ca has a slight effect on the phase structure, electrical conductivity, TEC and area-specific resistance (ASR) of YCI x BCZ. All the YCI x BCZ samples investigated show an excellent tolerance to CO 2 at 800 °C. Additionally, the YCI 0.2 BCZ phase are stable after 72 h exposure to air at 600, 700, and 800 °C, separately, while YCI x BCZ (x=0, 0.1 and 0.3) show instability at 700 °C in air. The optimal composition, YCI 0.2 BCZ, exhibits a relatively low ASR value (0.048 Ω cm 2 at 800°C) and a high power density (345 mW cm −2 at 800°C). The current results demonstrate that YCI 0.2 BCZ is promising cathode material for IT-SOFCs.

Investigation on high entropy alloys as interconnect material for intermediate temperature solid oxide fuel cells

Investigation of Solid Oxide Fuel Cells (SOFCs) is receiving great attention due to its higher efficiency and zero environmental pollution during operation. Interconnects are a critical part of the SOFC stack which connects the cells in series and combines the electricity produced. The present study aims to investigate High Entropy Alloys (HEAs) for interconnect application in intermediate temperature SOFC. Towards this, FeCoCrNi, FeCoCrNiMn0.1, FeCoCrNiMn0.5, and FeCoCrNiMn HEAs are prepared by vacuum arc melting and examined for its phase evaluation. Thermal stability, thermal expansion, resistivity, oxidation, and Area Specific Resistance (ASR) are investigated up to 800 °C. Oxidation studies show the formation of multicomponent oxide in the HEAs which suppresses the growth of Cr2O3 layer. FeCoCrNiMn0.1, FeCoCrNiMn0.5, and FeCoCrNiMn HEAs possess ASR values less than 100 mΩ.cm2 in the temperature range of 600–800 °C which ensure the superior performance of the SOFC stack.

Evaluation of the reactive-sintered (Mn,Co)3O4 spinel layer for SOFC cathode-side contact application

Simulated interconnect/contact/cathode cells are used to investigate the performance of different contact precursors that are reactively sintered into spinel contact layers with nominal compositions of Mn1.5Co1.5O4 and MnCo2O4, respectively. Both bare and Mn1.5Co1.5O4-coated interconnects are employed in this study, where the Mn1.5Co1.5O4 interconnect coating is also prepared via reactive sintering. The isothermal area specific resistance (ASR) of the test cells is evaluated at 800 °C in air for 2000 h. All the test cells exhibited excellent electrical behavior with ASR values of less than 10 mΩ·cm2 during the measurement. The presence of the dense Mn1.5Co1.5O4 coating leads to a better ASR performance. Cross-sectional observation of the test cells is conducted to assess the compatibility of the contact layer with adjacent components as well as its effectiveness in suppressing chromia scale growth and blocking Cr migration from the interconnect to the cathode.

Efficiencies of cobalt- and copper-based coatings applied by different deposition processes for applications in intermediate-temperature solid oxide fuel cells

Solid Oxide Fuel Cells (SOFCs) are electrochemical conversion devices that produce electricity directly by oxidising a fuel. The interconnects between the individual cells need to be coated to limit Cr(VI) evaporation from the steel and to preserve electrical conductivity. Physical Vapour Deposition (PVD)-coated samples with Ce/Co, Ce/Cu, and Ce/MnCu, and Thermal Spray (TS)-coated Mn/Co, Cu and Mn/Cu and AISI 441 steel samples were exposed at 650 °C for up to 1000 h. The PVD Ce/Co and Ce/Cu coatings, as well as the TS Mn/Co coating, exhibited the formation of a thin protective Cr2O3 scales underneath the coating. These samples also exhibited the lowest area-specific resistance (ASR) values. The remainder of the samples exhibited much higher mass gains and higher ASR values. Cr(VI) evaporation measurements showed that all the coatings behaved approximately the same despite the PVD coatings being only about one-tenth of the thickness of the TS coatings.