Search

The commercialization of reversible protonic ceramic electrochemical cells is hindered by the lack of highly active and durable air electrodes exposed to high concentration of steam under operating conditions. Here, findings that dramatically enhance the electrocatalytic activity and stability of a conventional (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ (LSCF) air electrode by a multiphase catalyst coating composed of a conformal Pr1−xBaxCoO3−δ thin film and exsolved BaCoO3−δ nanoparticles, are reported. At 600 °C, the catalyst coating decreases the polarization resistance of the LSCF air electrode by a factor of 25 (from 1.09 to 0.043 Ω cm2) in air and the degradation rate by two orders of magnitude (from 1.0 × 10−2 to 1.8 × 10−4Ω cm2 h−1 in humidified air with 30 vol% H2O). Further, a single cell with the catalyst‐coated LSCF air electrode at 600 °C demonstrates a high peak power density of 1.04 W cm−2 in the fuel cell mode and a high current density of 1.82 A cm−2 at 1.3 V in the electrolysis mode. The significantly enhanced performance of the LSCF air electrode is attributed mainly to the high rate of surface oxygen exchange, fast surface proton diffusion, and the rapid H2O and O2 dissociation on the catalysts. [ABSTRACT FROM AUTHOR]

One of the main bottlenecks that limit the performance of reversible protonic ceramic electrochemical cells (R‐PCECs) is the sluggish kinetics of the oxygen reduction and evolution reactions (ORR and OER). Here, the significantly enhanced ORR and OER kinetics and stability of a conventional La0.6Sr0.4Co0.2Fe0.8O3–δ (LSCF) air electrode by an efficient catalyst coating of barium cobaltite (BCO) is reported. The polarization resistance of a BCO‐coated LSCF air electrode at 600 °C is 0.16 Ω cm2, about 30% of that of the bare LSCF air electrode under the same conditions. Further, an R‐PCEC with the BCO‐coated LSCF air electrode shows exceptional performance in both fuel cell (peak power density of 1.16 W cm−2 at 600 °C) and electrolysis (current density of 1.80 A cm−2 at 600 °C at 1.3 V) modes. The performance enhancement is attributed mainly to the facilitated rate of oxygen surface exchange. [ABSTRACT FROM AUTHOR]

Intermediate temperature solid oxide fuel cells (IT‐SOFCs) are cost‐effective and efficient energy conversion systems. The sluggish oxygen reduction reaction (ORR) and the degradation of cathodes are critical challenges to the commercialization of IT‐SOFCs. Here, a highly efficient multiphase (MP) catalyst coating, consisting of Ba1−xCo0.7Fe0.2Nb0.1O3−δ (BCFN) and BaCO3, to enhance the ORR activity and durability of the state‐of‐the‐art lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3−δ, LSCF) cathode is reported. The conformal MP catalyst‐coated LSCF cathode shows a polarization resistance (Rp) of 0.048 Ω cm2 at 650 °C, about one order of magnitude smaller than that of the bare LSCF. In an accelerated Cr‐poisoning test, the degradation rate of the catalyst‐coated LSCF electrode is 10−3 Ω cm2 h−1 (0.59% h−1) over 200 h, only one fifth of the degradation rate of the bare LSCF electrode at 750 °C. In addition, anode‐supported single cells with the MP catalyst‐coated LSCF cathode show a dramatically enhanced peak power density (1.4 W cm−2 vs 0.67 W cm−2 at 750 °C) and increased durability against Cr and H2O. Both experimental results and density functional theory‐based calculations indicate that the BCFN phase improves the ORR activity while the BaCO3 phase enhances the stability of the LSCF cathode. [ABSTRACT FROM AUTHOR]

Reversible solid oxide cells based on ceramic proton conductors have potential to be the most efficient system for large‐scale energy storage. The performance and long‐term durability of these systems, however, are often limited by the ionic conductivity or stability of the proton‐conducting electrolyte. Here new family of solid oxide electrolytes, BaHfxCe0.8−xY0.1Yb0.1O3−δ (BHCYYb), which demonstrate a superior ionic conductivity to stability trade‐off than the state‐of‐the‐art proton conductors, BaZrxCe0.8−xY0.1Yb0.1O3−δ (BZCYYb), at similar Zr/Hf concentrations, as confirmed by thermogravimetric analysis, Raman, and X‐ray diffraction analysis of samples over 500 h of testing are reported. The increase in performance is revealed through thermodynamic arguments and first‐principle calculations. In addition, lab scale full cells are fabricated, demonstrating high peak power densities of 1.1, 1.4, and 1.6 W cm−2 at 600, 650, and 700 °C, respectively. Round‐trip efficiencies for steam electrolysis at 1 A cm−2 are 78%, 72%, and 62% at 700, 650, and 600 °C, respectively. Finally, CO2H2O electrolysis is carried out for over 700 h with no degradation. [ABSTRACT FROM AUTHOR]

Here we report the electrochemical performance and long-term stability of La 0.8 Sr 0.2 CoO 3−δ (LSC), La 0.58 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF) and SmBa 0.5 Sr 0.5 Co 2.0 O 5+δ (SBSC) infiltrated (ZrO 2 ) 0.89 (Sc 2 O 3 ) 0.1 (CeO 2 ) 0.01 (SSZ) cathodes at low temperatures. At 700 °C, the initial polarization resistance of the infiltrated cathodes increased in following order: SBSC-SSZ (0.054 Ω cm 2 )

Here, stability of the metal-supported solid oxide fuel cell (MS-SOFC) with Ni–Ce 0.8 Sm 0.2 O 2−δ (SDC) infiltrated 430L anode and La 0.6 Sr 0.4 Fe 0.9 Sc 0.1 O 3−δ (LSFSc) infiltrated scandia-stabilized zirconia (SSZ) cathode is evaluated. It is found that the degradation rate defined as the voltage loss during a fixed period is faster at higher operation temperatures and larger current densities. Scanning electron microscopy (SEM) and energy dispersive X-ray spectra (EDS) analysis indicate that the degradation is mainly caused by the morphological change of the anode while metal element diffusion between Ni catalyst and 430L substrate contributes little. A 1500 h durability test measured at 650 °C and 0.9 A cm −2 shows a degradation rate of 1.3% kh −1 and the voltage decrease is mainly found in the initial 500 h. [ABSTRACT FROM AUTHOR]

A nanostructured architecture is proposed for reduced‐temperature solid oxide fuel cells, featuring thin scandium‐stabilized zirconia electrolytes sandwiched between two porous 430L metallic layers. Impregnating nanoscale catalysts into the porous 430L scaffolds—Ce0.8Sm0.2O1.9/Ni at the anodes and SmBa0.5Sr0.5Co2O5 at the cathodes—yields encouraging power densities of 1.02 W cm−2 at 600 °C and 0.6 W cm−2 at 550 °C. [ABSTRACT FROM AUTHOR]

Here we report a solid oxide electrolysis cell (SOEC) employing impregnated electrodes. The cell structure consisted of a porous 430 L metal support, a Ni-Ce 0.8 Sm 0.2 O 2 − δ (SDC) impregnated 430 L-zirconia stabilized zirconia (YSZ) hydrogen electrode, a scandia stabilized zirconia (SSZ) electrolyte and a Nd 2 O 3 -Nd 2 NiO 4 + δ (Nd 2 O 3 -NNO) impregnated SSZ oxygen electrode. The cell is prepared by tape casting, co-firing and impregnation techniques. At an applied voltage of 1.3 V and 50% steam content, current density of 2.05 A cm − 2 is obtained at 800 °C. The effect of the variation of H 2 O/H 2 ratio (3/97 to 70/30) on electrolysis performance at 750 °C is evaluated and the long-term stability in electrolysis mode is also investigated. [ABSTRACT FROM AUTHOR]

Sm0.2Ce0.8O2‐δ nanoparticles imbedded in macroporous 430L stainless steel demonstrate excellent catalytic activity for hydrogen electro‐oxidation. This is enabled by superior redox properties of ceria catalysts and high conductivities of the supporting 430L scaffolds. Thin yttria‐stabilized zirconia electrolyte fuel cells produce promising power densities of 0.94 W cm−2 at 800 °C and 0.55 W cm−2 at 700 °C. [ABSTRACT FROM AUTHOR]

Barriers to technological advancement of metal-supported SOFCs include nickel coarsening in the anode, metallic interdiffusion between the anode and the metal substrate, as well as poor cathode adhesion. Here we report a robust and novel architectured metal-supported SOFC that consists of a thin dense yttria-stabilized zirconia (YSZ) electrolyte layer sandwiched between a porous 430L stainless steel substrate and a porous YSZ thin layer. The key feature is simultaneous use of impregnated nano-scale SrFe 0.75 Mo 0.25 O 3− δ coatings on the internal surfaces of the porous 430L and YSZ backbones respectively as the anode and cathode catalyst. Such a fuel cell exhibits power densities of 0.74 W cm −2 at 800 °C and 0.40 W cm −2 at 700 °C when operating on hydrogen fuels and air oxidants. [ABSTRACT FROM AUTHOR]

Ni impregnated 430L anodes used for metal-supported solid oxide fuel cells are prepared and evaluated. The effects of catalysts loadings and heat treatment temperatures on the anode polarization resistances are investigated. The stabilities of the Ni impregnated 430L anodes are also measured and increasing the calcination temperature can enable a much more stable anode performance. Furthermore, by applying the Ni–Ce 0.8 Sm 0.2 O 2− δ (SDC) impregnated 430L composite anode, a low polarization resistance of 0.12 Ω cm 2 at 650 °C is obtained. The 1200 h durability test shows that the polarization resistance of the composite anode increases from 0.12 Ω cm 2 to 0.3 Ω cm 2 during the initial 500 h while no degradation is found during the subsequent measurement. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports on the fabrication of novel metal-supported solid oxide fuel cells containing porous 430L stainless steel substrates, YSZ electrolytes and porous YSZ cathode backbones. Such tri-layer structures are obtained by the tape casting, lamination and co-firing techniques. Redox-stable La0.6Sr0.4Fe0.9Sc0.1O3−δ (LSFSc) oxides are introduced as symmetric electrode catalysts onto the internal surfaces of porous 430L substrates and YSZ backbones using the solution impregnation method. The maximum power density is 0.65 W cm−2 measured at 800 °C. Impedance analyses show that the anode polarizations are the largest losses while the cathode polarizations make negligible contribution to the total cell resistances. [Copyright &y& Elsevier]

Abstract: Metal-supported solid oxide fuel cells (MS-SOFCs) containing porous 430L stainless steel supports, YSZ electrolytes and porous YSZ cathode backbones are fabricated by tape casting, laminating and co-firing in a reducing atmosphere. Nano-scale Ni and La0.6Sr0.4Fe0.9Sc0.1O3−δ (LSFSc) coatings are impregnated onto the internal surfaces of porous 430L and YSZ, acting as the anode and the cathode catalysts, respectively. The resulting MS-SOFCs exhibit maximum power densities of 193, 418, 636 and 907 mW cm−2 at 650, 700, 750 and 800 °C, respectively. Nevertheless, a continuous degradation in the fuel cell performance is observed at 650 °C and 0.7 V during a 200-h durability measurement. Possible degradation mechanisms were discussed in detail. [Copyright &y& Elsevier]

This paper reports on the fabrication in reducing atmospheres of SrFe0.75Mo0.25O3 (SFMO)–8 mol%Y2O3-stabilized ZrO2 (YSZ) composites by impregnating Sr2+-, Fe3+- and Mo7O24 6−-containing solutions into the porous YSZ backbones, which would find important applications as cathodes for co-fired metal-supported solid oxide fuel cells. X-ray diffraction examination shows that as-synthesized infiltrates consist of perovskite SFMO oxides and metallic Fe. In situ oxidation during the fuel cell operation eliminates metallic Fe, and SFMO oxides become the predominant component with some minor SrMoO4 impurities. Impedance measurements on symmetric cathode fuel cells show that such impregnated SFMO–YSZ composites exhibit low polarization resistances in air, e.g., 0.06 Ω cm2 at 800 °C. Metal-supported solid oxide fuel cells, consisting of porous 430L stainless steel substrates, Ni–YSZ active anodes, YSZ electrolytes and impregnated SFMO–YSZ composite cathodes, are fabricated using tape casting, tape lamination, co-sintering and solution impregnation techniques, and show maximum power densities of 438 mW cm−2 at 800 °C and 221 mW cm−2 at 700 °C. [ABSTRACT FROM AUTHOR]

Abstract: Metal-supported solid oxide fuel cells (SOFCs) containing porous 430L stainless steel support, Ni-YSZ anode and YSZ electrolyte were fabricated by tape casting, laminating and co-firing in a reduced atmosphere. (Bi2O3)0.7(Er2O3)0.3–Ag composite cathode was applied by screen printing and in-situ sintering. The polarization resistances of the composite cathode were 1.18, 0.48, 0.18, 0.09 Ω cm2 at 600, 650, 700 and 750 °C, respectively. A promissing maximum power density of 568 mW cm−2 at 750 °C was obtained of the single cell. Short-term stability was measured as well. [Copyright &y& Elsevier]

[Display omitted] • Improvement of electrochemical stability by doping Nb. • Enhancement of electrocatalytic activity by tuning Ba deficiency. • Peak power density of 1.5 and 1.0 W cm−2 at 600 °C for GDC and BZCYYb single cells. • Continuous operation of electrolysis cell for 1,000 h with minimal degradation. Solid oxide cells (SOCs) are considered the most efficient system for reversible conversion between chemical and electrical energy, thus having potential to be an attractive technology for a sustainable energy future. To achieve high round-trip efficiency, highly efficient and durable air electrode materials are needed to minimize energy loss associated with oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Here we report a bi-functional air electrode material, PrBa 0.9 Co 1.96 Nb 0.04 O 5+δ , demonstrating outstanding electrochemical performance (e.g., achieving peak power densities of over 1.5 and 1 W cm−2, respectively, for Gd 0.1 Ce 0.9 O 1.95 and BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ based fuel cells at 600 °C) while maintaining excellent stability (e.g., having a degradation rate of 40 mV per 1,000 h for H 2 O electrolysis cells). The excellent property of the new electrode is attributed to the improved stability from Nb doping and the enhanced electrocatalytic activity from tuning Ba deficiency, as confirmed by experimental results and computational analysis. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) cathode often suffers from the poisoning effect of the contaminants commonly encountered in air such as CO 2. Here we report an effective approach to enhancing the activity and CO 2 tolerance of the state-of-the-art La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) cathode enabled by a coating of BaCoO 3-δ (BCO), as verified by the electrochemical testings, Raman analyses, and density functional theory calculations. When surface modified with a thin-film BCO coating, LSCF displays a much enhanced ORR activity and an improved durability against CO 2. For example, anode supported SOFCs with the LSCF cathode coated with BCO coatings show a remarkable peak power density (P max) of 0.41 Wcm−2 and a significantly reduced degradation rate in current density of ∼0.08%h−1 at 0.8 V and 700 °C for a period of 300 hs when humidified H 2 (with 3 vol%H 2 O) was used as fuel and air with 8 vol% CO 2 as oxidant. The demonstrated performance is improved when compared with those of the cells with a blank LSCF electrode (a P max of ∼0.36 Wcm−2 and a degradation rate of ∼0.15%h−1) under the same conditions. The adsorption energy calculations suggests that BCO coating makes CO 2 adsorption much weaker than LSCF (−0.54 eV versus −1.07 eV). [Display omitted] • A BaCoO 3-δ coating has been deposited on La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 cathode surface. • The coating improves the ORR kinetics and durability of cathode in air with CO 2. • The CO 2 tolerance is confirmed by the experimental and simulation results. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) that can operate on hydrocarbon fuels offer an efficient and cost‐effective solution for electricity generation. However, broader commercialization of SOFCs is hindered by inadequate performance and limited durability due to the sluggish hydrocarbon reforming/oxidation kinetics and coking on the SOFC anode. Here it has been reported that these findings in design, synthesis, and characterization of a novel anode catalyst Ba(Zr0.8Y0.2)0.9(Ni0.5Ru0.5)0.1O3‐δ (BZYNR) that overcomes the problems, enabling direct utilization of nearly dry hydrocarbon fuels (e.g., methane, ethanol, and iso‐octane with only 3 vol% H2O) with exceptional power output for over 1000 h on both button cells and tubular cells. The outstanding performance of BZYNR is attributed to the high activity of hydrocarbon reforming and the accelerated water‐mediated carbon cleaning process on Ni‐based SOFC anode. [ABSTRACT FROM AUTHOR]

Reversible proton‐conducting solid oxide cells (R‐PSOCs) are considered to be one of the most promising devices for efficient power generation and hydrogen production. However, the requirement of high catalytic activity for fast oxygen reduction/evolution reaction (ORR/OER) and durability under high steam concentration of air electrode materials remains the major challenge for the practical application of R‐PSOCs. Here, a series of cobalt‐free Ruddlesden–Popper perovskite of Nd0.8Sr1.2Ni1‐xFexO4±δ are reported with mixed conductivity for enhanced ORR/OER kinetics. The R‐PSOCs with an optimal Nd0.8Sr1.2Ni0.7Fe0.3O4±δ air electrode show a high peak power density of 1.28 W cm−2 in the fuel cell mode and a promising current density of 3.24 A cm−2 at 1.3 V in the electrolysis cell mode at 700 °C. In addition, the R‐PSOCs show favorable stability under the fuel cell, electrolysis, and reversible modes for hundreds of hours. This work demonstrates that the Ruddlesden–Popper materials can be utilized as suitable air electrodes for R‐PSOCs. [ABSTRACT FROM AUTHOR]

A new catalytic combustion hydrogen (H 2) sensor is developed using the electrodeposition method and the Pd catalyst layer is directly deposited on a Pt filament without carrier. The sensing performance was investigated by altering the electroplating time to control the thickness of the Pd catalyst layer. The sensitivity is changed with the increase of the Pd layer's thickness and the highest sensitivity (26.8) was obtained when the thickness is 1.635 μm. In addition, the new sensor exhibits great selectivity, while having the advantages of low power consumption (25 mW) and high vibration resistance. The achievement of this carrier-free sensor is expected to meet the requirement for H 2 energy vehicles. • A carrier-free catalytic combustion H 2 sensor has been fabricated using the electrodeposition method. • The influence of catalytic layer on sensing performance was discussed. • The vibration resistance of sensors was demonstrated. [ABSTRACT FROM AUTHOR]

Controlling electrochemical deposition of lithium sulfide (Li2S) is a major challenge in lithium–sulfur batteries as premature Li2S passivation leads to low sulfur utilization and low rate capability. In this work, the solvent's roles in controlling solid Li2S deposition are revealed, and quantitative solvent‐mediated Li2S growth models as guides to solvent selection are developed. It is shown that Li2S electrodeposition is controlled by electrode kinetics, Li2S solubility, and the diffusion of polysulfide/Li2S, which is dictated by solvent's donicity, polarity, and viscosity, respectively. These solvent‐controlled properties are essential factors pertaining to the sulfur utilization, energy efficiency and reversibility of lithium–sulfur batteries. It is further demonstrated that the solvent selection criteria developed in this study are effective in guiding the search for new and more effective electrolytes, providing effective screening and design criteria for computational and experimental electrolyte development for lithium–sulfur batteries. Quantitative solvent‐mediated Li2S growth models and property–performance relationships of solvents are developed for solvent selection in Li–S batteries. An effective solvent, propionitrile, is identified as a promising alternative solvent based on guidelines developed in this study. [ABSTRACT FROM AUTHOR]

The cell consists of a highly efficient anode designed for the internal reforming of liquid hydrocarbons to H 2 and CO, promoted by a catalyst with a nominal composition of Ce 0.95 Ru 0.05 O 2–δ. Under operating conditions, the catalyst is restructured to a reduced frame (Ce 0.95 Ru 0.05– x O 2–δ , CR 5– x O) coated with Ru nanoparticles. DFT calculations support that Ru/CR 5– x O can lower the reaction barrier of the rate-limiting step of CH 3 OH decomposition and expedite the COH* intermediate by forming an efficient OH* supply from Ru/CR 5– x O and carbon species. [Display omitted] The commercialization of solid oxide fuel cells (SOFCs) that run on liquid hydrocarbon fuels is hindered by the poor coking tolerance of the state-of-the-art anode. Among the strategies developed, modulating the reforming reaction site's local steam/carbon ratios to enhance the coking tolerance is efficient but challenging. Here we report our rational design of a ceria-based catalyst (with a nominal composition of Ce 0.95 Ru 0.05 O 2– δ , CR 5 O) that demonstrates remarkable tolerance to coking while maintaining excellent activity for direct utilization of liquid fuels in SOFCs. Under operating conditions, the catalyst is transformed to a partially reduced oxide frame covered with Ru nanoparticles (Ru/Ce 0.95 Ru 0.05– x O 2– δ , Ru/CR 5– x O), as confirmed by experimental analyses. The Ru/CR 5– x O demonstrates excellent self-hydration capability to remove the coke. When applied to the Ni-yttria-stabilized zirconia (Ni-YSZ) anode of an SOFC with liquid fuels, the catalyst enables excellent performance, achieving a peak power density of 1.010 W cm−2 without coking for ∼200 h operation (on methanol) at 750 °C. Furthermore, density functional theory calculations reveal that the high activity and coking tolerance of the Ru/CR 5– x O catalyst-coated Ni-YSZ anode is attributed to the reduced energy barrier for the rate-limiting step and the formation of a COH intermediate for rapid carbon removal. [ABSTRACT FROM AUTHOR]

Reversible protonic ceramic electrochemical cells (R‐PCECs) have received increasing focus for their good capability of converting and storing energy. However, the widely used cobalt‐based air electrodes are less thermomechanically compatible with the electrolyte and lack stability, which largely limits the development of R‐PCECs. Herein, a cobalt‐free perovskite with a nominal composition of PrBa0.8Ca0.2Fe1.8Ce0.2O6δ (PBCFC) is reported, which is in–situ engineered to a (Ba, Ce) deficient‐PBCFC phase, a BaCeO3, and a CeO2 phase under typical operating conditions, delivering a low area–specific resistance of 0.10 Ωcm2 at 700 oC. The generated BaCeO3 and CeO2 particles increase the conduction/transfer of protons and oxygen ions, thus providing extra active sites for the oxygen reactions. When utilized as an air electrode on a single cell, it achieves encouraging performance at 700 °C: a peak power density of 1.78 Wcm−2 and a current density of 5.00 Acm−2 at 1.3 V in the dual mode of the fuel cell (FC) and electrolysis (EL) mode with reasonable Faradaic efficiencies. In addition, the cells exhibit favorable operational durability of 65 h (FC mode), 95 h (EL mode), and promising cycling stability of 200 h. [ABSTRACT FROM AUTHOR]

In recent years, the hydrogen economy has been strongly favoured by governmental and industrial bodies worldwide. A tremendous number of papers are published every year on different aspects of protonic ceramic electrochemical cells (PCECs) due to their lower operation temperature, easier reversible operation, and brighter prospects for further development. While new progress is being made continuously, many critical challenges remain. The effort on PCEC investigation could be more aligned for greater collective impact, e.g. the academic community could devote more effort to overdue critical problems but less to incremental improvements. This review aims to provide some insightful perspectives on critical challenges facing the development of PCECs, to sort out priorities in future effort, and to suggest promising directions to pursue. In this way, it is hoped that the technical readiness level of PCECs might advance more quickly, toward field demonstrations and commercialization for a clean and sustainable energy era. [ABSTRACT FROM AUTHOR]

Highlights: Single-phase ternary GaSiP2with a disordered lattice and liquid metal was synthesized. GaSiP2 electrode achieved superior Li-storage performances in both half and full cells. Unique self-healing Li-storage mechanism of GaSiP2 was analyzed. Si is considered as the promising anode materials for lithium-ion batteries (LIBs) owing to their high capacities of 4200 mAh g−1 and natural abundancy. However, severe electrode pulverization and poor electronic and Li-ionic conductivities hinder their practical applications. To resolve the afore-mentioned problems, we first demonstrate a cation-mixed disordered lattice and unique Li storage mechanism of single-phase ternary GaSiP2 compound, where the liquid metallic Ga and highly reactive P are incorporated into Si through a ball milling method. As confirmed by experimental and theoretical analyses, the introduced Ga and P enables to achieve the stronger resistance against volume variation and metallic conductivity, respectively, while the cation-mixed lattice provides the faster Li-ionic diffusion capability than those of the parent GaP and Si phases. The resulting GaSiP2 electrodes delivered the high specific capacity of 1615 mAh g−1 and high initial Coulombic efficiency of 91%, while the graphite-modified GaSiP2 (GaSiP2@C) achieved 83% of capacity retention after 900 cycles and high-rate capacity of 800 at 10,000 mA g−1. Furthermore, the LiNi0.8Co0.1Mn0.1O2//GaSiP2@C full cells achieved the high specific capacity of 1049 mAh g−1 after 100 cycles, paving a way for the rational design of high-performance LIB anode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] The performance of reversible solid oxide electrochemical cells (R-SOECs) is largely hindered by the insufficient electroactivity and poor durability of the bifunctional air electrodes, where the oxygen reduction and evolution reactions (ORR and OER) occur. Here, we report our findings in boosting the electrochemical activity and durability of an air electrode with Pr 0.2 Ba 0.2 Sr 0.2 La 0.2 Ca 0.2 CoO 3-δ (PBSLCC) via an A-site entropy engineering. The PBSLCC electrode shows enhanced oxygen reaction activity and excellent durability compared to binary and ternary double perovskites (PrBaCo 2 O 5+δ and Pr 0.8 Ba 0.8 Ca 0.4 Co 2 O 5+δ , respectively). A low and nearly unchanged area-specific resistance of 0.042 Ω cm2 is achieved at 750 °C during the 225-h stability test. La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3 - δ electrolyte-supported cells with the PBSLCC air electrode show remarkable performance at 800 °C, demonstrating a peak power density of 1.2 W cm−2 in the fuel cell mode, and a current density of −1.1 A cm−2 at 1.3 V in the electrolysis mode while maintaining the excellent cycling durability of 228 h at ±0.5 A cm−2 under humidified H 2 (10% H 2 O). A bulk oxygen p -band center model is applied to verify that tailoring of the A-site entropy strongly influences the surface exchange coefficients (k* chem), leading to higher oxygen reaction activity of PBSLCC than the binary and ternary perovskites. This study opens a new class of high-entropy perovskites for the rational design of air electrodes for R-SOECs with high activity and durability. [ABSTRACT FROM AUTHOR]

Solid oxide electrochemical cells (SOECs) have demonstrated the potential to be highly efficient devices for electrochemical CO2 reduction (CO2R) at intermediate temperatures. However, the performance and widespread applications for CO2R largely hinge on the sluggish reaction kinetics and poor durability of the state‐of‐the‐art electrodes. Here, the findings in enhancing the reaction activity and durability of a perovskite‐based electrode are reported, Sr2Fe1.5Mo0.3Cu0.2O6‐δ (SF1.5MC), for electrochemical oxidation of H2 and reduction of CO2. Under typical operating conditions, the SF1.5MC electrode is elegantly reconstructed into three phases of oxygen vacancy‐rich double perovskite (DP), Ruddlesden‐popper (RP), and Cu‐Fe metals, as confirmed by X‐ray diffraction and scanning transmission electron microscopy. When applied as a fuel electrode for an electrolyte‐supported SOEC, decent performances are demonstrated at 800 °C, showing a maximum power density of 1.51 W cm−2 in fuel cell mode (on H2 fuel) and a current density of 1.94 A cm−2 at 1.4 V in electrochemical CO2R to CO with high Faradaic efficiencies of ≈100% and good durability. [ABSTRACT FROM AUTHOR]

Over the past decades, considerable efforts have been made to develop hierarchically porous electrodes for the high surface area, the fast velocity of fuels/products to/away from the reaction site, and the high loading of thermal‐ and/or electrochemical‐ catalysts. Manipulation of the hierarchical structure is one of the key steps for high performance in applications of efficient energy storage and conversion such as solid oxide cells. This review starts with a brief introduction to the basic concept of mass transport and how mass transport may affect performance. Then, the latest developments in enhancing the performance of cells through modification or optimization of the hierarchically porous electrode structures, including altering the geometry or morphology and increasing the triple‐phase boundaries length of electrodes are summarized. Subsequently, the unique characteristics of microstructures that are critical to enhancing electrode performance and provide important insights into the mechanisms of performance (activity and durability) enhancement, aiming at achieving the rational design of better electrode architecture are highlighted. Finally, the remaining challenges for the knowledge‐based design of highly efficient electrodes for electrochemical devices, together with possible directions and future perspectives for the development of highly efficient electrodes through optimization of microstructure are discussed. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel cells (PCFCs) are one of the most efficient energy conversion devices. However, the performance of current PCFCs is greatly limited by the sluggish oxygen reduction reaction (ORR) kinetics and the fast degradation of the cathode due to contaminants poisoning (such as Cr species and steam). Here, a surface regulation of a double perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) cathode by a Pr0.9Fe0.7Co0.3O3 (PFC) catalyst coating to enhance the ORR activity and stability is reported. When tested in direct contact with Cr in the air with 3% H2O at 650 °C, the polarization resistance (Rp) of the PFC coated PBSCF (PFC‐PBSCF) electrode increases from ≈0.39 to 0.45 Ω cm2 after 100 h operation; in contrast, the Rp of a PBSCF electrode increases from 0.63 to 0.82 Ω cm2. Further, a PCFC with the PFC‐PBSCF cathode demonstrates an excellent peak power density (≈1.08 W cm–2 at 650 °C) and significantly enhanced durability (degradation rate of 0.03% h−1), much better than those of the cells with a PBSCF cathode (≈0.75 W cm–2 and degradation rate of 0.12% h−1). Raman spectroscopy and density functional theory calculations indicate that the PFC catalyst coating diminishes the formation of Cr species, such as (Ba1‐xSrx)CrO4, on the cathode surface. [ABSTRACT FROM AUTHOR]

• BaZr 1-x Y x O 3-δ proton conductors were used as electrolyte in solid-state NH 3 sensors. • Electrolysis was proposed to detect ammonia by measuring the proton migration in BZY electrolytes. • The lowest detection limit of the amperometric NH 3 sensor can be 500 ppb. Ammonia (NH 3) sensor is a critical part in the selective catalytic reduction (SCR) system for the reduction of oxynitride emission. Here, novel amperometric NH 3 sensors are proposed based on BaZr (1-x) Y x O 3-δ (BZY, x = 0.1, 0.2, 0.3, 0.4) proton electrolytes. The influence of yttrium content on the structure, morphology and conductivity of BZY electrolytes is investigated systematically. Benefiting from the best conductivity of BaZr 0.8 Y 0.2 O 3-δ (BZY20) among these electrolytes, the sensor with the BZY20 electrolyte exhibits a low detection limit of 0.5 ppm at a relative low working temperature of 350℃. Furthermore, the sensor shows the highest sensitivity, good selectivity and repeatability to NH 3. This work opens the way for the promising application of solid-state NH 3 sensor for low detection limit at low working temperatures. [ABSTRACT FROM AUTHOR]

The development of active and durable air electrodes is of great significance to the maturity of reversible protonic ceramic electrochemical cells (R‐PCECs). This article reports the recent findings in the performance enhancement of R‐PCECs using a novel heterostructured air electrode, consisting of a double perovskite PrBaCo1.6Fe0.2Nb0.2O5+δ backbone covered with in situ exsolved nanoparticles of Nb‐deficient PrBaCo1.6Fe0.2Nb0.2−xO5+δ. Such a heterostructured electrode is induced by the benign interaction of the electrode and steam during the cell operation, showing a faster surface exchange process, as confirmed by a mapping of high‐angle annular dark‐field transmission electron microscopy image, and distribution of relaxation time analyses of the electrochemical impedance spectra. The in situ formed Nb‐deficient nanoparticles and Nb‐rich parental perovskite significantly enhance the catalytic activity and durability of the air electrode toward oxygen reduction/evolution reaction on single cells at 650 °C, achieving a peak power density of 1.059 W cm−2 in fuel cell mode, a current density of 2.148 A cm−2 at 1.3 V in electrolysis cell mode, and good durability of a cycling test at ±0.5 A cm−2 for 200 h in dual modes of fuel cell and electrolysis cell. [ABSTRACT FROM AUTHOR]

The main barrier to symmetrical solid oxide fuel cells (SOFCs), where the same catalytic materials are used simultaneously as the anodes and the cathodes, is to identify a redox-stable catalyst that exhibits superior catalytic activities for both fuel oxidation and oxygen reduction reactions. Here we report a Sc-substituted La0.6Sr0.4FeO3−δ oxide, La0.6Sr0.4Fe0.9Sc0.1O3−δ , that shows great promise as a new symmetrical electrode material with good structural stability and reasonable conductivities in air and hydrogen. We further demonstrate that nano-scale La0.6Sr0.4Fe0.9Sc0.1O3−δ catalysts impregnated into the porous La0.9Sr0.1Ga0.8Mg0.2O3−δ backbones exhibit good catalytic activities for oxygen reduction and hydrogen oxidation reactions and thereby yield low polarization resistances, e.g., 0.015 Ω cm2 in air and 0.29 Ω cm2 in hydrogen with appropriate current collection at 800 °C. Thin La0.9Sr0.1Ga0.8Mg0.2O3−δ electrolyte fuel cells with such symmetrical La0.6Sr0.4Fe0.9Sc0.1O3−δ catalysts showed maximum power densities of 0.56 and 0.32 W cm−2 when operating on 97% H2–3% H2O at 800 and 700 °C, respectively. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction (SCR) utilizing urea hydrolysis to generate ammonia (NH 3) is the most efficient technology to reduce the emission of nitrogen oxides (NO x). NH 3 detection is crucial in the closed-loop feedback system for the precise urea injection. In this work, a high-temperature NH 3 sensor using a BaZr 0.8 Y 0.2 O 3-δ (BZY) proton conductor as the electrolyte and a BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY) H+/e–/O2– triple conductor as the sensing electrode (SE) is reported. The effect of the micromorphology of the BCFZY SE on the sensing performance is investigated by varying the sintering temperature of SE. The sensor shows high sensitivity to NH 3 with response currents of 0.39, 1.31, 3.03, and 1.81 μA/ppm at 350, 400, 450, and 500 °C, respectively. Furthermore, the sensor shows excellent selectivity and repeatability. This work demonstrates that the BCFZY-based sensor has great potential for the high-temperature NH 3 detection. • BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ triple conductor was used as the sensing electrode for ammonia detection. • A novel ammonia sensor was proposed based on the BZY proton electrolyte. • The influence of the morphology of BCFZY on the sensing performance was investigated. [ABSTRACT FROM AUTHOR]

Abstract: (La0.8Sr0.2)0.95MnO3 (LSM95) cathode supported Zr0.89Sc0.1Ce0.01O2−x (SSZ) electrolytes with LSM-SSZ active cathode layers were fabricated using the tape-casting, lamination and co-sintering techniques. The loadings of pore-formers in the cathode support layers and the active cathode layers were optimized through impedance measurement on symmetrical cathode fuel cells. The pore size distribution and porosity of cathode-support substrates were measured using the mercury intrusion porosimetry. The open circuit voltage and maximum power density of cathode-support solid oxide fuel cells with NiO/SSZ cermet anodes were 1.10 V and 0.325 W cm−2 at 750 °C with H2 as fuels and air as oxidants. [Copyright &y& Elsevier]

• A ppb level alcohols gas sensor was discovered based on YSZ electrolyte and LSM sensing electrode. • The interface between YSZ and LSM is a critical boundary on sensing performance. • The 90 % response time would be extened byexcesssive resistance on the YSZ and LSM interface. A mixed potential type alcohols gas sensor based on an yttrium stabilized zirconia (YSZ) electrolyte and an La 0.8 Sr 0.2 MnO 3 (LSM) sensing electrode was fabricated. The influences of YSZ-LSM interface on sensing performance were studied by multiple methods including X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis and differential scanning calorimetry (TG-DSC) and electrochemical impendence spectroscopy (EIS). The sensor with 1150 °C-sintered interface showed an ultralow detection limit of 50 ppb alcohols (methanol and ethanol) at 500 °C in air. The response voltage was independent of water, CO, CO 2 and NO x. The sensor exhibited a reasonable selectivity towards alcohols under the existence of several kinds of volatile organic compounds. Meanwhile, the sensor showed a good repeatability and a suitable long-term stability. Based on the polarization curves and EIS results, a mixed potential mechanism was proposed. These results demonstrate the promising potential of using the LSM-based sensor for human exhale test. [ABSTRACT FROM AUTHOR]

The air electrode with strontium and cobalt elements has the elemental diffusion or delamination issue on the air electrode/electrolyte interface in reversible protonic ceramic cells (RPCCs). Hence the development of strontium and cobalt-free triple conducting (H+/O2-/e-) air electrodes with high electrochemical activity and stability is urgent. Here, we report a strontium and cobalt-free Ba 0.8 Ca 0.2 FeO 3-δ (BCF82) air electrode with high catalytic activity and electrochemical stability for oxygen reduction/evolution reactions. A RPCC with the BCF82 air electrode shows a high peak power density of 1.14 W cm−2 in the fuel cell mode and a current density of 3.49 A cm−2 under 1.3 V in the electrolysis mode at 700 °C. Furthermore, the cell demonstrates suitable stability in the fuel cell, electrolysis and reversible modes at 600 °C for hundreds of hours without elemental segregation and delamination issue. This work offers an efficient approach to develop low-cost and durable air electrodes for RPCCs. [Display omitted] • Ba 0.8 Ca 0.2 FeO 3-δ (BCF82) shows good steam adsorption and ion diffusion capacities. • BCF82 air electrode shows high activity and stability. • Reversible cells with the BCF82 air electrode show suitable performance and stability. [ABSTRACT FROM AUTHOR]

In this study, perovskite-type oxides of Sr 2 Fe 1+x Mo 1−x O 6−δ (x = 0, 0.2, 0.35, 0.5) were synthesized and the phase stabilities both in oxidizing and reducing atmosphere were investigated. When calcined in the air atmosphere, pure perovskite phase can be obtained for the composition of Sr 2 Fe 1.5 Mo 0.5 O 6−δ while a large portion of SrMoO 4 second phase was detected in other compositions. Further reducing the above powders showed a pure phase for Sr 2 Fe 1+x Mo 1−x O 6−δ (x = 0, 0.2, 0.35) while minor amount of Fe was precipitated from the Sr 2 Fe 1.5 Mo 0.5 O 6−δ . Due to the highest electrical conductivity and lowest polarization resistance of Sr 2 FeMoO 6−δ , such composition has been applied as the cell anode for a cathode supported solid oxide fuel cell (CS-SOFC). Maximum power densities of 463 and 331 mW cm −2 have obtained for the fuel cell when measured at 800 °C using hydrogen and propane as fuel, respectively. The durability test in propane indicated that Sr 2 FeMoO 6−δ could be a potential anode material with good tolerance ability toward coking formation. [ABSTRACT FROM AUTHOR]

Nickel-based cermet anode-supported protonic ceramic fuel cells (PCFCs) show great potential for direct utilization of ammonia. However, the insufficient activity of anode and the deterioration of anode activity/durability caused by the undesired interaction between nickel and ammonia greatly limit the application. Here, we report tubular PCFCs embedded with a catalytic iron layer. Such cells show peak power densities of 1.507 W cm-2 and 1.078 W cm-2 at 700 °C when using H 2 and NH 3 as fuel, respectively, which are the highest tubular PCFC performance so far ever reported. In addition, the stability of cells with the catalyst layer has been dramatically enhanced when compared with that of cells without the catalyst layer. The enhancement of activity and durability is attributed to the catalytic activity of iron for ammonia decomposition, through which the direct contact between nickel and ammonia has been minimized and the anode structure has therefore been protected. [Display omitted] • A robust tubular cell has been fabricated via a phase inversion process. • The cell delivers excellent peak power densities of 1.507 W cm-2 on H 2 , and 1.078 W cm-2 on NH 3 at 700 °C. • The cell durability is greatly enhanced when integrated with a catalytic Fe layer. • A DFT study indicates that the Fe layer can effectively decompose the NH 3. [ABSTRACT FROM AUTHOR]

Nano-structured Nd 2 NiO 4+δ (NNO) impregnated scandia stabilized zirconia (SSZ) is studied as the oxygen electrode of solid oxide electrolysis cells (SOECs). The hydrogen electrode-supported single cell with Ni–Zr 0.92 Y 0.16 O 2.08 (YSZ) hydrogen electrode, SSZ electrolyte and impregnated NNO-SSZ composite oxygen electrode is prepared by a tape casting, co-firing and impregnation method. The electrochemical properties of the cell are investigated in the electrolysis mode. At the voltage of 1.3 V, current densities of 1.081, 0.677, 0.441 and 0.23 A cm −2 are obtained at 800, 750, 700 and 650 °C respectively. The cell also exhibits comparable performance with variation of the steam-to-hydrogen ratio (50/50 to 80/20) at 750 °C. Additionally, the short-term durability in the electrolysis mode of the cell is also studied. [ABSTRACT FROM AUTHOR]

In this work, copper and nickel oxides (CuO–NiO) powders with various mole ratios were synthesized by the glycine nitrate process (GNP) and the Cu–Ni alloy was obtained by reducing the CuO–NiO powders at 600 °C for 0.75 h. Furthermore, Cu 1−x Ni x (alloy) -CeO 2 impregnated YSZ anodes were fabricated by the impregnation method and the optimized anode composition was evaluated. It was found that the optimized mole ratio of Cu:Ni was 5:5, while the weight ratio of Cu–Ni alloy to CeO 2 was 3:1. Additionally, impregnated anode with 40 wt % loading of Cu 0.5 Ni 0.5 (alloy)-CeO 2 exhibited the best performance and the polarization resistance of such anode was only 0.097, 0.115, 0.145 and 0.212 Ω cm 2 at 750, 700, 650 and 600 °C, respectively. Finally, the performance of the optimized anode in methane (CH 4 ) was investigated and the carbon deposition is greatly suppressed compared to the Ni-based anode. [ABSTRACT FROM AUTHOR]

To study the performance of opposed piston opposed cylinder (OPOC) engine, a unique computation model for OPOC engine is established with GT-power software, and its key design parameters, such as intake and exhaust port diameters, intake pressure, injection timing and the number and diameter of nozzle holes are optimized. The results indicate that the model suits to the performance simulation of OPOC engine, with its performance indicators in three typical operating conditions achieving expected objectives. [ABSTRACT FROM AUTHOR]

Si‐based anodes with a stiff diamond structure usually suffer from sluggish lithiation/delithiation reaction due to low Li‐ion and electronic conductivity. Here, a novel ternary compound ZnSi2P3 with a cation‐disordered sphalerite structure, prepared by a facile mechanochemical method, is reported, demonstrating faster Li‐ion and electron transport and greater tolerance to volume change during cycling than the existing Si‐based anodes. A composite electrode consisting of ZnSi2P3 and carbon achieves a high initial Coulombic efficiency (92%) and excellent rate capability (950 mAh g−1 at 10 A g−1) while maintaining superior cycling stability (1955 mAh g−1 after 500 cycles at 300 mA g−1), surpassing the performance of most Si‐ and P‐based anodes ever reported. The remarkable electrochemical performance is attributed to the sphalerite structure that allows fast ion and electron transport and the reversible Li‐storage mechanism involving intercalation and conversion reactions. Moreover, the cation‐disordered sphalerite structure is flexible to ionic substitutions, allowing extension to a family of Zn(Cu)Si2+xP3 solid solution anodes (x = 0, 2, 5, 10) with large capacity, high initial Coulombic efficiency, and tunable working potentials, representing attractive anode candidates for next‐generation, high‐performance, and low‐cost Li‐ion batteries. [ABSTRACT FROM AUTHOR]