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The purpose of this study is to investigate the approaches applied to analyze solid oxide fuel cell (SOFC) microstructural properties. Both manual and automated image processing approaches applied on SOFC microstructural images which are obtained from several types of tomography such as dual-beam focused ion beam with scanning electron microscopy (FIB-SEM), Electron Backscatter Diffraction (EBSD) and others are discussed. In fact, to achieve a realistic and accurate SOFC microstructural properties, such as average diameter, volume fraction, triple phase boundary (TPB), area interface density and tortuosity factor, the approaches of image processing and quantification are crucial for a reliable image generation for quantification purposes. The microstructural properties are optimized to improve SOFC electrode performance. Therefore, the image processing and quantification approaches are outlined and reviewed. Despite the automated image processing and quantification algorithms significantly outperform manual image processing and quantification approaches in terms of computing speed when evaluating and measuring microstructural properties, the efficiency and productivity are still extremely taken into concern. As a result, image processing and quantification approaches are concluded and presented respectively in this paper.

This work investigates a new nanostructured gas diffusion layer (nano-GDL) to improve the performance of air cathode single-chamber microbial fuel cells (a-SCMFCs). The new nano-GDLs improve the direct oxygen reduction reaction by exploiting the best qualities of nanofibers from electrospinning in terms of high surface-area-to-volume ratio, high porosity, and laser-based processing to promote adhesion. By electrospinning, nano-GDLs were fabricated directly by collecting two nanofiber mats on the same carbon-based electrode, acting as the substrate. Each layer was designed with a specific function: water-resistant, oxygen-permeable polyvinylidene-difluoride (PVDF) nanofibers served as a barrier to prevent water-based electrolyte leakage, while an inner layer of cellulose nanofibers was added to promote oxygen diffusion towards the catalytic sites. The maximum current density obtained for a-SCMFCs with the new nano-GDLs is 132.2 ± 10.8 mA m−2, and it doubles the current density obtained with standard PTFE-based GDL (58.5 ± 2.4 mA m−2) used as reference material. The energy recovery (EF) factor, i.e., the ratio of the power output to the inner volume of the device, was then used to evaluate the overall performance of a-SCMFCs. a-SCMFCs with nano-GDL provided an EF value of 60.83 mJ m−3, one order of magnitude higher than the value of 3.92 mJ m−3 obtained with standard GDL. [ABSTRACT FROM AUTHOR]

Flexible and rechargeable Zn–air batteries (ZAB) are promising candidates for attaining the high energy density required for next‐generation energy storage devices given their half‐open cathode configuration. However, the poor interfacial contact between the immobilized solid‐state electrolyte and porous cathode, and drying‐out of water in the electrolyte at low relative humidity (RH) of 30% or less, cause low performance and short lifespan. Herein, a novel hygroscopic dough‐type electrolyte with water‐absorbing and malleable free‐standing configuration originating from deliquescent KOH and severe gelation of sodium alginate (SA) by facile kneading is proposed. Because appropriate contents are required to absorb water from the atmosphere and obtain the manageable form of the dough used here, the materials composing the dough electrolyte, i.e., SA, water, and KOH, are precisely controlled to ensure high malleability, scalability, ionic conductivity, and good water retention capabilities. The optimized dough inhibits evaporation at low RH and lowers the interfacial resistance with the cathode via tight adhesion. The dough‐type ZABs show noteworthy maximum power density of 160 mW cm−2 with low catalyst mass loading (0.4 mg cm−2), specific capacity of 632 mAh gZn−1, and stability for 60 h at RH 30% and 120 h even at low temperature of −20 °C, producing reasonable output. [ABSTRACT FROM AUTHOR]

Catalyst utilization is an important determinant of proton exchange membrane fuel cell performance, and increasing the catalyst utilization is one of the most critical approaches to reducing the catalyst loading in PEMFC. 4-phase stochastic reconstruction method based on the variable-resolution Quartet Structure Generation Set (QSGS) algorithm is utilized to elucidate the influence of different parameters of electrode preparation, including the porosity, the dispersion degree of carbon agglomerate, ionomer content, and carbon support size, on the catalyst utilization in the catalyst layer. It was found that there exist optimal values for the porosity, dispersion degree of carbon agglomerate, ionomer content, and carbon support sizes in CLs and any deviations from these optimal values would lead to transport issues of electron, proton and mass within CLs. Taking electron, proton and mass transport into consideration simultaneously, the optimal Pt utilization is 46.55% among 48 cases in this investigation, taken at the carbon support diameter of 40 nm, the porosity of 0.4, the agglomerate spatial density of 25 μm−3 and I/C at 0.7. The selection of porosity, ultrasonic dispersion technique and ionomer content for conventional electrode preparation requires compromises on mass, electron and proton transport, leading to catalyst utilization in CLs hardly exceeding 50%. Therefore, the next generation of catalyst layer design and preparation technology is desired.

This work investigates a new nanostructured gas diffusion layer (nano-GDL) to improve the performance of air cathode single-chamber microbial fuel cells (a-SCMFCs). The new nano-GDLs improve the direct oxygen reduction reaction by exploiting the best qualities of nanofibers from electrospinning in terms of high surface-area-to-volume ratio, high porosity, and laser-based processing to promote adhesion. By electrospinning, nano-GDLs were fabricated directly by collecting two nanofiber mats on the same carbon-based electrode, acting as the substrate. Each layer was designed with a specific function: water-resistant, oxygen-permeable polyvinylidene-difluoride (PVDF) nanofibers served as a barrier to prevent water-based electrolyte leakage, while an inner layer of cellulose nanofibers was added to promote oxygen diffusion towards the catalytic sites. The maximum current density obtained for a-SCMFCs with the new nano-GDLs is 132.2 ± 10.8 mA m−2, and it doubles the current density obtained with standard PTFE-based GDL (58.5 ± 2.4 mA m−2) used as reference material. The energy recovery (EF) factor, i.e., the ratio of the power output to the inner volume of the device, was then used to evaluate the overall performance of a-SCMFCs. a-SCMFCs with nano-GDL provided an EF value of 60.83 mJ m−3, one order of magnitude higher than the value of 3.92 mJ m−3 obtained with standard GDL.

Summary: Catalyst layer (CL) is the most important component in the high‐temperature proton exchange membrane fuel cell (HT‐PEMFC), as it offers reaction sites for hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR). As the electrochemical reactions take place at gas/electron/proton interface, the length of this triple‐phase boundary (TPB) in the CL governs the rate of electrochemical reactions. As the TPB in the HT‐PEMFC has not been studied yet, a numerical non‐isothermal 3D model and a percolation micro model were developed in this work to investigate the effect of CLs' properties on both the TPB length and cell performance. The volume fractions, particle size, and particle size ratio of ionomer and Pt/C were selected for optimization. The results show that peak current density could be achieved at an ionomer volume fraction of 52%. Further improvement of cell performance requires smaller particle size and smaller particle size ratio of ionomer. Novelty statement: A three‐dimensional non‐isothermal model of HT‐PEMFC was developed. By adopting the percolation model, length of triple phase boundary of HT‐PEMFC was successfully quantified. The particle parameters including the particle size and ionomer volume fraction can be optimized to increase the length of triple phase boundary, thus achieving higher cell performance. [ABSTRACT FROM AUTHOR]

Metal oxide La0.6Sr0.4CoO3 was chosen as a sensing electrode for the mixed potentiometric NO2 sensor based on yttria stabilization zirconia (YSZ). The La0.6Sr0.4CoO3 sensing electrodes were sintered at 800°C, 900°C, 1000°C, and 1100°C separately to obtain different microstructures. The relationship between the La0.6Sr0.4CoO3 sensing electrode microstructures and the NO2 sensing performances was described. The La0.6Sr0.4CoO3 sensing electrode sintered at 1000°C had the biggest porosity of 29.8%, while the sensor based on it exhibited the maximum response of 141.1 mV at 500 ppm NO2 and the first-rank sensitivity of 80.3 mV/decade at 400°C. The sensor also showed high stability and selectivity. Different microstructures of the sensing electrode corresponded to different triple-phase boundaries, which was the main place for NO2 detection, so the performances were affected. Moreover, the result of the electrochemical impedance spectrum also proved the triple-phase boundary played an important role in NO2 detection. [ABSTRACT FROM AUTHOR]

Rare earth element doping is a popular methodology for improving the electrical and electrochemical properties of materials. Inspired by this ideology, garnet ferrite material Sm 3 Fe 5 O 12 (SFO) doped by rare earth (Yb, La) metal ions to form Sm 3-0.5 Yb 0.5 Fe 5 O 12 (SYFO) and Sm 3-0.5 La 0·5 Fe 5 O 12 (SLFO). The samples are synthesized by sol gel auto combustion and have been applied as electrolyte membrane for the first time in low temperature solid oxide fuel cell (LT-SOFC). The results indicate that the as-prepared materials have triple charge transport (H+/O−2/e−) carrier which promotes the hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR) in SOFC at triple phase boundary region (TPB). Electrochemical impedance spectroscopy (EIS) reveals that the polarization resistance of SLFO membrane significantly reduces from 0.92 Ω-cm2 to 0.45 Ω-cm2 and the power output improve from 310 mW/cm2 to 650 mW/cm2 at 550 °C temperature in comparison with that of SYFO and SFO electrolyte supported cells. UV-vis diffused spectroscopy explains the semiconducting nature of the prepared materials due to the existence of optical bandgap in the semiconductor region. The further investigation also verifies the protonic conduction of SLFO membrane by constructing oxygen ion blocking fuel cell with configuration of Ni-NCAL/BZCY/SLFO/BZCY/Ni-NCAL having 427.94 mW/Cm2 fuel cell performance with 1.03 OCV at 550 °C temperature. Image 1 • RE (Yb, La) doped SFO doped NPs with semiconducting nature were developed for LT- SOFC's. • The prepared SLFO and SYFO materials possess (H+/O−2/e−) triple charge conducting nature. • SLFO device achieved P max of 650 mW/cm2 with 1.05 V OCV at 550 °C. • The synthesized electrolyte membrane promotes HOR and ORR catalysis at TPB region. [ABSTRACT FROM AUTHOR]

A scheme to quantify surface coverages of reactants at triple phase boundary (TPB) by electrochemical measurements was constructed to evaluate the electrode performance of solid oxide fuel cells and electrolysis cells (SOFC/EC). The developments of electrode requires that the intrinsic properties of materials separated from the effect of geometric structure of the electrode. The proposed reaction model at TPB of H2/H2O electrodes is composed of competitive adsorptions and Langmure‐type surface reactions under the relationship between oxygen activity (aO) and the electrode potential. To determine the reaction constant (ka) and four adsorption equilibrium constants at TPB (KH, KH2O, KO and KOH), a mashine learning approach with a genetic algorithm as an optimization method and the experimental data of reversible SOFC/ECs with different H2/H2O partial pressures as the learning data was developed. As a result, even though all experimental curves of the current density vs. aO in SOFC operation were fitted by numerous sets of the five constants, the coverages under different conditions could be uniquely determined. Results suggest that TPB at 900 °C was almost vacant with a small amount of H2O in SOEC operation, and was not vacant and the OH coverage increased with increasing aO in SOFC operation. [ABSTRACT FROM AUTHOR]

Improvement of the sluggish oxygen reduction reaction (ORR) is the key to lower the operating temperature of conventional solid oxide fuel cells (SOFCs). Developing a novel nanostructure in the cathodic catalyst layer is one of the efficient ways to reduce the operating temperature while improving fuel cell performance. In this paper, all components of low-temperature SOFCs were prepared on a nanoporous substrate by the sputtering method. For the performance enhancement at low temperature, an ultrathin Pt-Gadolinium Doped Ceria (GDC) cermet interlayer was deposited on the cathode side of electrolyte and demonstrated. A significant improvement in electrochemical performance was observed in the Pt-GDC interlayer fuel cell compared to a reference cell. The peak power density of Pt-GDC cathodic cermet interlayer cell was 334 mW/cm2 at 500 °C, which was 42.7% higher than that of the reference cell. Through additional analysis, we confirmed that the observed performance enhancement was attributed to the ultrathin cathodic cermet interlayer, which increases the triple phase boundary and enhances the reaction kinetics for ORR. ● LT-SOFC with Pt-GDC cathodic interlayer was fabricated and characterized. ● Ultrathin (~50 nm) cermet interlayer was prepared by a simple co-sputtering process. ● Increased TPBs in the cermet interlayer improved the fuel cell performance by 42.7 %. [ABSTRACT FROM AUTHOR]

In this study, we fabricated three dimensional yttria-stabilized zirconia (YSZ) interface engineering layer (IEL) by using a DC sputtering method to enhance oxygen reduction reactions (ORRs) of low temperature solid oxide fuel cells (LT-SOFCs). In order to deposit three dimensional YSZ IEL, a commercial Y–Zr metal alloy target was sputtered under various deposition pressure conditions (4, 8, 12 Pa) and then annealed at 800 °C for 6 h. Phase transformation of metal alloy Y–Zr to YSZ was identified by X-ray diffraction, X-ray photoelectron spectroscopy and high resolution-transmission electron microscope. The roughness of the three dimensional YSZ IELs were strongly related to the deposition pressure of the sputtering technique. After physical and chemical characterization, electrochemical examinations proved that the three dimensional YSZ IELs efficiently improved the ORR activity by geometrical effects. The fuel cell with the IEL fabricated at 8 Pa condition achieved the best power density (37.9 mW/cm2), which was 30.2% improved performance compared to the fuel cell without IEL (29.1 mW/cm2). Electrochemical impedance spectroscopy investigations also proved that rough three dimensional YSZ IELs efficiently enhance the performance of LT-SOFCs. [ABSTRACT FROM AUTHOR]

In order to improve the performance of the anode of solid oxide fuel cells, the cermet anodes were synthesized by employing a carbonate co-precipitation method and calcined at different temperatures (500 °C-800 °C). The fabrication of pellet from calcined powder was done by uniaxial pressing. These pellets were then characterized to investigate the effect of calcination temperature on their microstructure, thermal behavior, porosity, and carbonate bonding along with conductivity. The carbonates formed within the synthesis process has shown a strong effect over the properties of the Ni-SDC. It is observed that Ni-SDC maintained its chemical compatibility during each process. The thermal gravimetric analysis showed that more weight loss occurred for the specimen calcined at low temperature. Due to the porosity increases with calcination electronic conductivity and performance will also be enhanced. [ABSTRACT FROM AUTHOR]

Exploratory experiments on effects from a phase transition are reported for a low-melting microcrystalline anthraquinone (N,N,N′,N′-tetraoctyl-2,6-diamino-9,10-anthraquinone or TODAQ). Data for the solid-liquid phase transition are obtained by differential scanning calorimetry and then compared to data obtained by voltammetry. In preliminary electrochemical measurements, microcrystal deposits on a basal plane pyrolytic graphite electrode are shown to undergo a solid-state 2-electron 2-proton reduction in contact to aqueous 0.1 M HClO4 with a midpoint potential Emid,solid = − 0.24 V vs. SCE. The reduction mechanism is proposed to be limited mainly by the triple phase boundary line and some transport of TODAQ molecules towards the electrode surface for both solid and melt. A change in the apparent activation energy for this reduction is observed at 69 °C, leading to an enhanced increase in reduction current with midpoint potential Emid,liquid = − 0.36 V vs. SCE. A change of TODAQ transport along the crystal surface for solid microcrystalline material (for the solid) to diffusion within molten microdroplets (for the liquid) is proposed. Upon cooling, a transition at 60 °C back to a higher apparent activation energy is seen consistent with re-solidification of the molten phase at the electrode surface. Differential scanning calorimetry data for solid TODAQ dry and for TODAQ in contact to aqueous 0.1 M HClO4 confirm these transitions. [ABSTRACT FROM AUTHOR]

A Monte Carlo percolation model has been developed and utilized to characterize the factors controlling triple phase boundary (TPB) formation in an SOFC electrode. The model accounts for (1) electronic conductor, ionic conductor, and gas phase percolation, (2) competition between percolation of gas and electronically conducting phases, and (3) determination of continuous, though not necessarily fully percolating, paths from TPBs to the bulk phases. The model results show that physical processes near the TPB, such as sorbate transport, significantly affect TPB formation in a composite electrode. Active TPB formation is found to be most significantly dependent upon continuous and competing percolation of multiple phases. Simultaneously requiring continuous paths and accounting for non-continuous boundary conditions results in lower active TPB formation levels (up to 8% of possible sites) than presented in the literature (75% of possible sites). In addition, the varying ratio of active to potential TPB sites predicted by the current model (up to 80%) differs significantly from the constant reported in the literature (80%), which lacks analyses of three-phase percolation, gas phase paths, and gas/current collector boundary conditions. This dependence of active TPB formation on percolation of all three phases is important to understand as a basis for determining SOFC performance and optimization. © 2007 Elsevier Ltd. All rights reserved.

Solid Oxide Fuel Cells at intermediate operating temperatures require high catalytic activity and compatibility of cathode material with electrolyte to reduce interfacial polarisation losses. In the present work, Brownmillerite structured composite based on Ca 2 Fe 2 O 5 and Ca 2 Co 2 O 5 [CFO-CCO] was studied for its cathodic properties. The Mixed Ionic and Electronic conducting (MIEC) properties of this composite material improves the Oxygen Reduction Reaction (ORR), catalytic activity and interfacial polarisation resistance. The structural, morphological and elemental analysis of the composite was carried out by XRD, BET, XPS, SEM and EDX. Electrical studies revealed that the Composite Cathode [CFO-CCO] has better ionic conductivity and sufficient electronic conductivity at 800 °C. Impedance analysis of Half-cell[CFO-CCO/SDC] and Symmetric-cell [CFO-CCO/SDC/CFO-CCO] at 800 °C shows the Area Specific Resistance (ASR) of 10.45 Ω cm2 and 1.14 Ω cm2 respectively. Performance of full cell [NiO-SDC/SDC/CFO-CCO] with Samarium doped Ceria (SDC) as electrolyte yields a power density of 160 mW/cm2. Electrochemical Impedance spectroscopy (EIS) measured at open circuit voltage (OCV) shows lower polarisation loss but higher ohmic loss due to the thicker electrolyte. The CFO-CCO composite material shows promising results, attributed to its microstructure and mixed conducting properties, enabling application for Intermediate Temperature solid oxide fuel cells (SOFCs). • One of the best ionic conductivities of cathode composite reported in literature. • Low cathode interfacial charge transfer resistance of 0.457 Ω cm2 at 800 °C for composite cathode in symmetric cell. • Better Activation energy of symmetric cell with the composite cathode [84.9 KJ/mol] indicating improved ORR kinetics. [ABSTRACT FROM AUTHOR]

[Display omitted] The oxygen adsorption at the surface ionomer film is quantified by means of a self-built system based on quartz crystal microbalance (QCM), exhibiting a quasi-logarithmic increase with increasing oxygen partial pressure, and its inhomogeneity arises from the distinct oxygen adsorption properties of the phase-separated structure, where the extended form of the Toth adsorption isotherm could be more suitable to describe the adsorption behavior. • Oxygen adsorption is quantified by a self-built system based on QCM. • Surface oxygen adsorption on ionomer film exhibits a quasi-logarithmic law. • Ionomer surface exhibits heterogeneity in morphology and oxygen interaction. • Extended Toth model is the most appropriate for ionomer surface oxygen adsorption. Reducing Pt loading of proton exchange membrane fuel cells (PEMFCs) without sacrificing performance remains challenging due to the severe oxygen transport resistance in cathode, especially the local oxygen transport resistance (R Local) at the gas/ionomer/electrocatalyst triple phase boundary (TPB). Here, the detailed oxygen adsorption mechanism at surface ionomer is quantified for the first time via a self-built characterization system based on quartz crystal microbalance (QCM). The results show that the surface oxygen adsorption amount quasi-logarithmically increases as oxygen partial pressure increases. The ionomer surface is further investigated by molecular dynamics simulations and it is found that there exists not only non-uniformity in morphology, but also separation of hydrophilic and hydrophobic phase, which leads an inhomogeneity of interaction with oxygen. As a consequence, the extended form of Toth model is proved to be more appropriate for the surface oxygen adsorption on ionomer film due to higher correlation coefficients R 2, better applicability at low pressure and varying temperature. Ultimately, we successfully predict the oxygen adsorption amount and the corresponding trend of R Local at practical fuel cell operating condition with the adsorption model disclosed in this work, which is potential to estimate the oxygen adsorption in other type of electrochemical devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unveiling the first high-performance propionaldehyde sensor based on mixed-potential principle. • Sensor design incorporates Gd 2 Zr 2 O 7 electrolyte and SmSbO 4 electrode for efficient triple phase boundary. • Demonstrated exceptional sensor stability, reproducibility, and selectivity. • Mixed potential model provides a robust explanation for sensor's performance. • Sensor's performance and design validated through comprehensive theoretical and experimental discussions. Propionaldehyde, a volatile industrial chemical, poses significant environmental and health risks due to its toxicity. To address the need for sensitive and reliable detection of this compound, we developed a mixed potential sensor with an efficient triple phase boundary, employing a Gd 2 Zr 2 O 7 solid electrolyte and a SmSbO 4 sensing electrode. The sensor's optimal sensitivity to propionaldehyde was achieved at a working temperature of 560 °C, with a remarkably low detection limit of 0.2 ppm—far beneath the safe environmental threshold for propionaldehyde. The sensor's response demonstrated a linear relationship with Propionaldehyde concentrations between 0.2 and 2 ppm, and a logarithmic linear relationship within the 2–100 ppm range. Based on the linear fitting line, the sensor's sensitivities in these ranges were −8.7 mV/ppm and −59.7 mV/decade, respectively. This sensor behavior aligns with the mixed potential sensing mechanism. The sensor's robust repeatability, humidity resistance, selectivity, and long-term stability underscore its reliability for practical applications, making it a valuable tool for effective environmental monitoring of propionaldehyde concentrations. [ABSTRACT FROM AUTHOR]

Cost and durability have become crucial hurdles for the commercialization of proton exchange membrane fuel cells (PEMFCs). Although a continuous reduction of Pt loading within the cathode catalyst layers (CCLs) can lead to cost savings, it also increases the oxygen transport resistance, which is further compounded by key material degradation. Hence, a further understanding of the mechanism of significant performance loss due to oxygen transport limitations at the triple phase boundaries (TPBs) during the degradation process is critical to the development of low Pt loading PEMFCs. The present study systematically investigates the impact of carbon corrosion in CCLs on the performance and oxygen transport process of low Pt loading PEMFCs through accelerated stress tests (ASTs) that simulate start-up/shutdown cycling. A decline in peak power density from 484.3 to 251.6 mW cm -2 after 1500 AST cycles demonstrates an apparent performance loss, especially at high current densities. The bulk and local oxygen transport resistances ( r bulk and R local ) of the pristine cell and after 200, 600, 1000, and 1500 AST cycles are quantified by combining the limiting current method with a dual-layer CCL design. The results show that r bulk increased from 1527 to 1679 s cm -2 , R local increased from 0.38 to 0.99 s cm -1 , and the local oxygen transport resistance with the normalized Pt surface area ( r local ) exhibited an increase from 18.5 to 32.0 s cm -1 , indicating a crucial impact on the structure collapse and changes in the chemical properties of the carbon supports in the CCLs. Further, the interaction between the ionomer and carbon supports during the carbon corrosion process is deeply studied via electrochemical quartz crystal microbalance and molecular dynamics simulations. It is concluded that the oxygen-containing functional groups on the carbon surface could impede the adsorption of ionomers on carbon supports by creating an excessively water-rich layer, which in turn aggravates the formation of ionomer agglomerations within the CCLs. This process ultimately leads to the destruction of the TPBs and hinders the transport of oxygen through the ionomer.

A double-layered electrode by coating a layer of nano-sized LiNiO 2 particles on a conventional electrode was fabricated to improve the performance of the cathode of the molten carbonate fuel cell. The layer consisting of nano-sized LiNiO 2 particles has a larger surface area than that of the conventional electrode, which is a lithiated NiO cathode. Therefore, it can provide numerous reaction sites and has higher electrical conductivity than the lithiated NiO electrode. Consequently, the cell performance can be improved at lower operating temperatures (600 °C or below). The performance of the nano LiNiO 2 -coated cathode was examined in various ways such as by single-cell operation and electrochemical impedance spectroscopy (EIS). The improvement in performance was demonstrated by high cell voltage of over 0.87 V at 600 °C and current density of 150 mA cm−2. This result was better than 0.81 V generated by the uncoated cathode cell. In the EIS analysis, the nano LiNiO 2 layer coating tended to significantly decrease the charge transfer resistance and increase the mass transfer resistance but caused an overall decrease in the cathode polarization. Thus, high performance was observed at low temperatures. • A lithiated NiO cathode coated with a nano-sized LiNiO 2 layer was fabricated. • The layer provides expanded electrode reaction site and low cell resistance. • High voltage of 0.87 V was obtained during testing at 600 °C. • EIS analysis with conventional cell showed lowered charge transfer resistance. [ABSTRACT FROM AUTHOR]

Featured Application: Solid oxide fuel cells (SOFC) are one of the power-generated devices that have received much attention over the last decade due to advantages, such as a high efficiency, quietness, multiple fuels, and the inexpensive catalyst nature. To improve the performance of SOFC, the electrospun electrode is introduced to the SOFC, which can be achieved by impregnating nanoscale particles on the backbone surface of fibers. In this paper, a theoretical model was developed for the electrospun electrode. This model captures the key geometric parameters and their interrelationships, which can be used to design the microstructure parameters, such as the particle radius, fiber radius, and impregnation loading. Electrospinning is a new state-of-the-art technology for the preparation of electrodes for solid oxide fuel cells (SOFC). Electrodes fabricated by this method have been proven to have an experimentally superior performance compared with traditional electrodes. However, the lack of a theoretic model for electrospun electrodes limits the understanding of their benefits and the optimization of their design. Based on the microstructure of electrospun electrodes and the percolation threshold, a theoretical model of electrospun electrodes is proposed in this study. Electrospun electrodes are compared to fibers with surfaces that were coated with impregnated particles. This model captures the key geometric parameters and their interrelationship, which are required to derive explicit expressions of the key electrode parameters. Furthermore, the length of the triple phase boundary (TPB) of the electrospun electrode is calculated based on this model. Finally, the effects of particle radius, fiber radius, and impregnation loading are studied. The theory model of the electrospun electrode TPB proposed in this study contributes to the optimization design of SOFC electrospun electrode. [ABSTRACT FROM AUTHOR]

It is of importance to establish stable and well‐connected proton path in the catalyst layer to promote the fuel cell performance. Here, we describe a novel method to fabricate stable and efficient proton path for high temperature polymer electrolyte fuel cells (HT‐PEFCs), in which the ionic liquid is doped into the platinum electrocatalyst. The electrochemical results depict that ionic liquid doped electrocatalyst exhibits comparable electrochemical surface area (ESA) and enhanced durability indicating that ionic liquid negligibly affects the hydrogen adsorption/desorption process and protects the electrocatalyst from carbon corrosion. Interestingly, the catalyzing activity toward oxygen reduction reaction (ORR) of Pt electrocatalyst is boosted after doping with ionic liquid mainly due to the modified electronic structures of Pt atoms induced by nitrogen atoms from ionic liquid resulting in weak interaction between Pt atoms and intermediates. The fuel cell performance of ionic liquid doped electrocatalyst is much improved ascribed to the homogeneously dispersed ionic liquid on the surface of Pt electrocatalyst facilitating the fabrication of triple phase boundaries (TPBs) as a result of efficient proton conduction in the catalyst layer. The fuel cell performance only decreases 10 % after 100,000 potential cycles from 1.0 to 1.5 V versus RHE suggesting that ionic liquid forms a stable proton path in the catalyst layer. Thus, the ionic liquid doped Pt electrocatalyst is applicable for the real HT‐PEFC operation. Layer up. Coating the Pt electrocatalyst with ionic liquid facilitates the formation of well‐connect and stable proton path for high temperature polymer electrolyte fuel cells. Meanwhile, the intrinsic oxygen reduction reaction (ORR) activity of Pt electrocatalyst is also boosted. [ABSTRACT FROM AUTHOR]

In this study, the effects of the strontium (x = 0.2–0.7) contents on oxygen permeation properties of 60 wt% Ce 0.8 Sm 0.2 O 2-d − 40 wt% Sm 0.8 Sr 0.2 Cu 0.2 Fe 0.8 O 3-d (SDC-8228) and 60 wt% Ce 0.8 Sm 0.2 O 2-d − 40 wt% Sm 0.3 Sr 0.7 Cu 0.2 Fe 0.8 O 3-d (SDC-3728) dual-phase (DP) ceramic membranes obtained by one-pot synthesis of a pure Ionic Conducting (IC) phase with a Mixed Ionic–Electronic Conducting (MIEC) phase were investigated under different conditions of temperature (800–1000 °C) and CO 2 atmosphere (0–100%). As a result, it was confirmed that the oxygen permeation properties of selected IC/MIEC DP membranes had increased when the Strontium content (Sr x ) of the MIEC phase increased from Sr x = 0.2 to Sr x = 0.7 . The results showed that the SDC-3728 DP membrane exhibits higher oxygen flux than the SDC-8228 DP membrane. In detail, the oxygen permeation flux reached ∼0.5 mL min −1 cm −2 at 1000 °C, which was about was one and a half times higher than the SDC-8228 DP membrane. An additional performance improvement was achieved by coating the SDC-3728 DP membrane with a pure Electron Conductor (EC) like Palladium (Pd) by the electroless deposition technique. The oxygen permeation flux of the Pd surface-modified SDC-3728 DP membrane was ∼2.0 mL min −1 cm −2 in 100% CO 2 at 1000 °C, which was about three times higher than the SDC-8228 DP membrane. [ABSTRACT FROM AUTHOR]

The semiconductor-ionic composite membrane has been recently developed for a novel solid oxide fuel cell (SOFC), i.e., the semiconductor-ion membrane fuel cell (SIMFC). In this work, the perovskite-type SrFeO 3-δ (SFO) as semiconductor material was composited with ionic conductor Ce 0.8 Sm 0.2 O 2-δ (SDC) to form the SFO-SDC composite membrane for SIMFCs. The SFO-SDC SIMFCs using the optimized weight ratio of 3:7 SFO-SDC membrane obtained the best performances, 780 mW cm −2 at 550 °C, compared to 348 mW cm −2 obtained from the pure SDC electrolyte fuel cell. Introduction of SFO into SDC can extend the triple phase boundary and provide more active sites for accelerating the fuel cell reactions, thus significantly enhanced the cell power output. Moreover, SFO was employed as the cathode, and a higher power output, 907 mW cm −2 was achieved, suggesting that SFO cathode is more compatible for the SFO-SDC system in SIMFCs. This work provides an attractive strategy for the development of low temperature SOFCs. [ABSTRACT FROM AUTHOR]

The agglomeration of nickel (Ni) particles in a Ni-cermet anode is a significant degradation phenomenon for solid oxide fuel cells (SOFCs). This work aims to predict the performance degradation of SOFCs due to Ni grain growth by using a simplified approach. Accelerated aging of Ni-scandia stabilized zirconia (SSZ) as an SOFC anode is carried out at 900 °C and subsequent microstructural evolution is investigated every 100 h up to 1000 h using scanning electron microscopy (SEM). The resulting morphological changes are quantified using a two-dimensional image analysis technique that yields the particle size, phase proportion, and triple phase boundary (TPB) point distribution. The electrochemical properties of an anode-supported SOFC are characterized using electrochemical impedance spectroscopy (EIS). The changes of particle size and TPB length in the anode as a function of time are in excellent agreement with the power-law coarsening model. This model is further combined with an electrochemical model to predict the changes in the anode polarization resistance. The predicted polarization resistances are in good agreement with the experimentally obtained values. This model for prediction of anode lifetime provides deep insight into the time-dependent Ni agglomeration behavior and its impact on the electrochemical performance degradation of the SOFC anode. [ABSTRACT FROM AUTHOR]

Electrospinning is a new state-of-the-art technology for the preparation of electrodes for solid oxide fuel cells (SOFC). Electrodes fabricated by this method have been proven to have an experimentally superior performance compared with traditional electrodes. However, the lack of a theoretic model for electrospun electrodes limits the understanding of their benefits and the optimization of their design. Based on the microstructure of electrospun electrodes and the percolation threshold, a theoretical model of electrospun electrodes is proposed in this study. Electrospun electrodes are compared to fibers with surfaces that were coated with impregnated particles. This model captures the key geometric parameters and their interrelationship, which are required to derive explicit expressions of the key electrode parameters. Furthermore, the length of the triple phase boundary (TPB) of the electrospun electrode is calculated based on this model. Finally, the effects of particle radius, fiber radius, and impregnation loading are studied. The theory model of the electrospun electrode TPB proposed in this study contributes to the optimization design of SOFC electrospun electrode.