固体氧化物燃料电池阳极材料Sr_2Fe_(1.5)Mo_(0.5)O_6(SFM)/Sm_(0.2)Ce_(0.8)O_(1.9)(SDC)的研究

采用机械混合法合成了Sr2Fe1.5Mo0.5O6(SFM)和Sm0.2Ce0.8O1.9(SDC)质量比为7∶3的SFM/SDC复合材料。用X射线衍射(XRD)、扫描电镜(SEM)、H2-TPR、EIS等表征手段对其进行了表征,并以SFM/SDC|La0.8Sr0.2Ga0.83Mg0.17O3(LSGM)|Ba0.5Sr0.5Co0.8Fe0.2O3(BSCF)为单电池片进行电化学测试,对其性能进行评价。结果表明,复合材料取得了较好的放电性能,即以氢气为燃料气,850、800、750℃时分别取得了630.6、548.4、426 mW/cm2最大功率密度;以甲醇为燃料,850、800、750℃时分别取得了551.6、426.8、335.3 mW/cm2最大功率密度。     

Robust and reliable solid oxide fuel cells with modified thin film YSZ electrolyte

Reduce electrolyte thickness can improve solid oxide fuel cell (SOFC) performance. However, thinner electrolyte often contains prominent defects and flaws, which may decrease the yield and increase operation risk. This work proposes a method to modify the thin film YSZ electrolyte, to improve cell reliability and durability. The as-sintered anode supported half-cell with screen printed YSZ electrolyte was immersed in precursor solution of Y(NO₃)₃·6H₂O and Zr(NO₃)₄·5H₂O, and being treated under hydrothermal condition of 150°C for 12 h. As a result, the modified cells show slight increase in the OCV values. Furthermore, the hydrothermal modification effectively promotes interface sintering between YSZ electrolyte and GDC barrier layer, yielding a smaller ohmic resistance of .142 Ω·cm² (a decrease of ∼11%) and a higher peak power density of .964 W/cm² (an increase of ∼18%) at 750°C, than pristine cell. Moreover, the modified cell operates stably over 300 h, while the pristine cell presents large and irregular voltage fluctuations. This work suggests that the hydrothermal modification is an effective and promisingly industrial applicable method for thin film electrolyte recovery in SOFCs.     

Atmospheric plasma spraying to fabricate metal-supported solid oxide fuel cells with open-channel porous metal support

Metal-supported solid oxide fuel cells (MS-SOFCs) have been fabricated by applying phase-inversion tape-casting and atmospheric plasma spraying (APS). The effect of the binder amount of the phase-inversion slurries on the microstructure development of the 430L stainless steel metal support was investigated. The pore structures, the viscosity of the slurry, porosity and permeability of the as-prepared metal supports are significantly influenced by the amount of the binder. NiO–scandia-stabilized zirconia (ScSZ) anode, ScSZ electrolyte and La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF) cathode layers were consecutively deposited on the metal support with an ideal microstructure by APS process. The effect of plasma power of the APS on the microstructure of the electrolyte and cathode was investigated. A dense electrolyte layer and a porous cathode layer were successfully obtained at 40 and 6 kW of the APS plasma power, respectively. MS-SOFCs, with a cell configuration of 430L/Ni-ScSZ/ScSZ/LSCF, achieved a maximum cell power density of 1079 mW cm⁻² at 700°C using humidified H₂ as fuel and ambient air as oxidant. The corresponding ohmic resistance and total resistance of MS-SOFCs was 0.14 and 0.32 Ω cm², respectively. This work demonstrates the feasibility of fabricating high-performance MS-SOFCs with economical and scalable techniques.     

固体氧化物燃料电池阳极材料Ni-SDC的稳定性实验及热力学分析

以Ni-SDC作为固体氧化物燃料电池（SOFC）的阳极,研究了该阳极粉末在制备过程中以及5% H2S-N2硫化后的产物,并用热力学软件绘制相图对其在各种温度下的产物变化进行分析。结果表明：NiO-SDC在800 ℃煅烧和在850 ℃还原的产物与热力学分析结果是一致的。对比在5%的H2S-N2中硫化12 h前后的XRD表明Ni已经转化为NiS2,热力学分析验证了该结论。比较Ni-SDC和SDC硫化前后的Raman光谱和XRD结果得到：SDC硫化后主峰型没有发生明显变化,但强度变弱,说明粒径变大,可能因为有Ce-O-S键生成。     

Biodiesel formulations as fuel for internally reforming solid oxide fuel cell

Biodiesel (alkyl ester of rapeseed oil) is prepared using various, methyl, ethyl and butyl alcohols through the transesterification process. Sodium hydroxide and sulfuric acid are used as catalyst for methyl alcohol, ethyl alcohol and butyl alcohol respectively. Biodiesel-water formulations are formulated using water and emulsifiers like sodium lauryl sulphate (SLS) and SPAN 80 in a high shear mixer. The formulations are tested at 800 °C as fuel for internal reforming in solid oxide fuel cells (SOFCs). The formulations based on methyl and butyl esters require the use of emulsifiers to prepare stable emulsions, while ethyl esters are able to form stable emulsions without emulsifiers. The decrease in the biodiesel concentration of formulation does not have any effect on the power density of the ethyl ester formulation. Fuel cells fuelled with 20% formulations lasted longer than 50% formulations in all the formulations tested as result of increase in steam carbon ratio resulting in effective removal of carbon deposited on the anode surface. Butyl ester formulations exhibited the worst performance in both types of formulation tests. The best performance was exhibited by 20% ethyl formulation in terms of life of the cell but 50% methyl ester formulations exhibit the highest power density.     

Development of LSM/YSZ composite cathode for anode-supported solid oxide fuel cells

This paper presents the effect of (La,Sr)MnO₃ (LSM) stoichiometry on the polarization behaviour of LSM/Y₂O₃-ZrO₂ (YSZ) composite cathodes. The composite cathode made of A-site deficient (La_0.85Sr_0.15)_0.9MnO₃ (LSM-B) showed much lower electrode interfacial resistance and overpotential losses than that made of stoichiometric (La_0.85Sr_0.15)_1.0MnO₃ (LSM-A). The much poorer performance of the latter is believed to be due to the formation of resistive substances such as La₂Zr₂O₇/SrZrO₃ between LSM and YSZ phases in the composite electrode. A slight A-site deficiency (∼0.1) was effective in inhibiting the formation of these resistive substances. A power density of ∼1 W cm⁻² at 800 °C was achieved with an anode-supported cell using an LSM-B/YSZ composite cathode. In addition, the effects of cathodic current treatment and electrolyte surface grinding on the performance of composite cathodes were also studied.     

Effect of powder composition upon plasma spray-physical vapor deposition of 8YSZ columnar coating

Agglomerated 8YSZ nano-powders for thermal barrier coating (TBC) were prepared by spray drying method. The morphology and diameter of 8YSZ powders were adjusted through controlling the solid content of the suspensions. Using prepared agglomerated 8YSZ nano-powders, columnar-structured coatings were obtained on Ni-based superalloy substrates by plasma spray-physical vapor deposition (PS-PVD). The experimental results proved that the spray dried powders characteristics were related to the solid content of suspensions. During the PS-PVD process, the deposition efficiency of the powders was improved with the increase of powder diameter due to the existence of thermophoresis. Moreover, it can be concluded by mathematical derivations that the top area of the plasma flame was sufficient for powder evaporation.     

Fabrication of electrolyte materials for solid oxide fuel cells by tape-casting

In this research, solid oxide fuel cell electrolytes were fabricated by aqueous tape-casting technique. The basic compositions for SOFC electrolyte systems were focused on yttria-stabilized zirconia (YSZ) system. The powders used in this study were from different sources. ZrO₂-based system doped with 3, 8, and 10 mol% of Y₂O₃, and 8YSZ electrolyte tape illustrated the desirable properties. The grain size of the sintered electrolyte tapes was in the range of 0.5–1 μm with 98–99% of theoretical density. Phase and crystal structure showed the pure cubic fluorite structure for 8–10 mol% YSZ and tetragonal phase for 3 mol% doped. The electrolyte tapes sintered at 1450 °C for 4 h had the highest ionic conductivity of 30.11 × 10⁻³ S/cm which was measured at 600 °C. The flexural strengths were in the range of 100–180 MPa for 8–10 mol% YSZ, and 400–680 MPa for 3 mol% YSZ.     

The influence of activated carbon as an additive in anode materials for low temperature solid oxide fuel cells

The effects of activated carbon (AC) as an additive in multi-oxide nano composite LiNiCuZn–O for application as anode in solid oxide fuel cell (SOFC) is reported. The composite was synthesized using solid state reactions method with varying content of AC in range 0.1%–0.9% for use as anode in the cell. The cell was composed of the synthesized composite as anode, LiNiCuZn–O as cathode and Samaria doped ceria (SDC) as electrolyte. The prepared composites were characterized for morphology and crystal structure by scanning electron microscope (SEM) and x-ray diffraction (XRD) respectively. Furthermore, the crystallite sizes of LiNiCuZn–O and LiNiCuZn–O with AC as an additive have been found in the range from 50 nm to 70 nm. The prepared composite materials were observed porous and the porosity of the sample having 0.5% additive was found highest. The conductivity and power density of the SOFC were studied at temperature of 600 °C. The maximum value of conductivity was found as 4.79 S/cm for the composite containing 0.5% AC as measured by using 4-probe method. The maximum value of power density of the fuel cell with anode comprising of 0.5% AC along with the mentioned cathode and the electrolyte was 455 mW/cm². Therefore, out of the compositions studied, the composite comprising of LiNiCuZn–O with 0.5% AC offered best performance for anode in the cell. This oxide composite is reported as a potential candidate for use as anode in low temperature SOFCs.     

Low-temperature constrained sintering of YSZ electrolyte with Bi2O3 sintering sacrificial layer for anode-supported solid oxide fuel cells

Solid oxide fuel cells (SOFCs) have strong potential for next-generation energy conversion systems. However, their high processing temperature due to multi-layer ceramic components has been a major challenge for commercialization. In particular, the constrained sintering effect due to the rigid substrate in the fabrication process is a main reason to increase the sintering temperature of ceramic electrolyte. Herein, we develop a bi-layer sintering method composed of a Bi₂O₃ sintering sacrificial layer and YSZ main electrolyte layer to effectively lower the sintering temperature of the YSZ electrolyte even under the constrained sintering conditions. The Bi₂O₃ sintering functional layer applied on the YSZ electrolyte is designed to facilitate the densification of YSZ electrolyte at the significantly lowered sintering temperature and is removed after the sintering process to prevent the detrimental effects of residual sintering aids. Subsequent sublimation of Bi₂O₃ was confirmed after the sintering process and a dense YSZ monolayer was formed as a result of the sintering functional layer-assisted sintering process. The sintering behavior of the Bi₂O₃/YSZ bi-layer system was systematically analyzed, and material properties including the microstructure, crystallinity, and ionic conductivity were analyzed. The developed bi-layer sintered YSZ electrolyte was employed to fabricate anode-supported SOFCs, and a cell performance comparable to a conventional high temperature sintered (1400 °C) YSZ electrolyte was successfully demonstrated with significantly reduced sintering temperature (<1200 °C).     

Cu-Ce-Zr-O／YSZ阳极材料以甲烷为燃料时的抗积炭性能

为研究甲烷在固体氧化物燃料电池中操作稳定性,分别采用共沉淀法和柠檬酸溶胶.凝胶法制备了10%CuO-Ce0.15Zr0.85O2催化剂,并以此为阳极催化剂、LSM为阴极制成了YSZ电解质支撑的SOFC单电池.用XRD对材料进行表征;用SEM对阳极,阴极进行表征.以甲烷为燃料对单电池发电性能进行测试,研究了两种不同方法制备的Cu-Ce-Zr-O阳极催化剂的抗积炭性能.相对于共沉淀法,溶胶-凝胶法制备的阳极结构和发电性能都要优于前者.长期稳定性方面,共沉淀法和溶胶.凝胶法制备的Cu-Ce-Zr-O/YSZ阳极都较传统的Ni-YSZ阳极更能够长期稳定运行.     

Durability and thermal cycling of Ni/YSZ cermet anodes for solid oxide fuel cells

The long-term properties of Ni/yttria stabilized zirconia (YSZ) cermet anodes for solid oxide fuel cells were evaluated experimentally. A total of 13 anodes of three types based on two commercial NiO powders were examined. The durability was evaluated at temperatures of 850 C, 1000 C and 1050 C over 1300 to 2000h at an anodic d.c. load of 300mA cm^–2 in hydrogen with 1 to 3% water. The anode-related polarization resistance, R _P, was measured by impedance spectroscopy and found to be in the range of 0.05 to 0.7 cm². After an initial stabilization period of up to 300h, R _P varied linearly with time within the experimental uncertainty. At 1050 C no degradation was observed. At 1000 C a degradation rate of 10 m cm² per 1000 h was found. The degradation rate was possibly higher at 850 C. A single anode was exposed to nine thermal cycles from 1000 to below 100 C at 100 C h^–1. An increase in R _P of about 30m cm² was observed over the first two cycles. For the following thermal cycles R _P was stable within the experimental uncertainty.     

Effect of calcination temperature on the microstructure,composition and properties of nanometer agglomerated 8YSZ powders for plasma spray-physical vapor deposition (PS-PVD) and coatings thereof

Homemade nano-agglomerated powders 8YSZ powders for PS-PVD were prepared by the spray drying, then calcination processes at four different temperatures (500 °C, 700 °C, 900 °C and 1100 °C) were carried out on the spray-dried powders. Checked by laser particle sizer, scanning electron microscope (SEM) and X-ray diffraction (XRD), the physical properties, microstructure and phase constitutions of the calcined powders were investigated. The results show that the size of powders calcined at 500 °C is increased relative to the spray-dried powder, whereas the powders calcined at 700 °C, 900 °C and 1100 °C possess smaller size. The binding force of the primary particles tend to rise with the increase of calcination temperature. When the temperature was up to 900 °C and above, it was found that the sintering neck indicating with strong binding was formed between the primary particles. In parallel, the powders underwent an m-ZrO₂ to t-ZrO₂ transition as the calcination temperature rose. It is also found that the PS-PVD prepared coatings which were obtained by using the above powders undergo a transformation from a feather-like to a dense laminate structure as the calcination temperature rises. It is noteworthy that the coating obtained by the powders calcined at 700 °C have a special three-layer composite structure of near dense surface layer, columnar intermediate layer and dense sub-layer. The composite structural coating has excellent adhesion and thermal shock resistance, with a bonding strength of 81MPa and no major spalling when water quenched 100 cycles at 1100 °C.     

Tailoring the electron-blocking layer by addition of YSZ to Ba-containing anode for improvement of ceria-based solid oxide fuel cell

The in-situ fabrication of an electron-blocking layer between the Ba-containing anode and the ceria-based electrolyte is an effective approach in suppressing the internal electronic leakage in ceria-based solid oxide fuel cell (SOFC). To improve the thickness of the electron-blocking layer and to research the effect of the layer thickness on the improvement of SOFC, a Ba-containing compound (0.6NiO-0.4BaZr_0.1Ce_0.7Y_0.2O_3-δ) modified by Y stabilized zirconia (YSZ) was employed as a composite anode in this research. SEM analyses demonstrated that the thickness of the interlayer can be simply controlled by regulating the proportion of YSZ at anode. The in-situ formed interlayer in the cell with the anode modified by 20?mol% YSZ possesses a thickness of 0.9?µm which is more suitable for the cell achieving an enhanced performance.     

Single‐step fabrication of an anode supported planar single‐chamber solid oxide fuel cell

We present single‐step‐co‐sintering manufacture of a planar single‐chamber solid oxide fuel cell (SC‐SOFC) with porous multilayer structures consisting of NiO/CGO, CGO and CGO‐LSCF as anode, electrolyte, and cathode, respectively. Their green tapes were casted with 20 μm thickness and stacked into layers of anode, electrolyte, and cathode (10:2:2), then hot‐pressed at 2 MPa and 60°C for 5 minutes (deemed optimal). Subsequently, hot laminated layers were cut into 40 × 40 mm cells and co‐sintered up to 1200°C via different sintering profiles. Shrinkage behavior and curvature developments of cells were characterized, determining the best sintering profile. Hence, anode‐supported SC‐SOFCs were fabricated via a single‐step co‐sintering process, albeit with curvature formation at edges. Subsequently, anode thickness was increased to 800 μm and electrolyte reduced to 20 μm to obtain SOFCs with drastically reduced curvature with the help of a porous alumina cover plate.     

Electric field-assisted sintering anode-supported single solid oxide fuel cell

Cosintering (La_0.84Sr_0.16MnO₃ thin-film cathode/ZrO₂: 8 mol% Y₂O₃ thin-film solid electrolyte/55 vol.% ZrO₂:8 mol% Y₂O₃ + 45 vol.% NiO anode, ϕ = 12 × 1.5 mm thick pellet) was achieved by applying an electric field for 5 min at 1200°C. Impedance spectroscopy measurements of the anode-supported three-layer cell show an improvement of the electrical conductivity in comparison to that of a conventionally sintered cell. The scanning electron microscopy images of the cross-sections of electric field-assisted pressureless sintered cells show a fairly dense electrolyte and porous anode and cathode. Joule heating, resulting from the electric current due to the application of the AC electric field, is suggested as responsible for sintering. Dilatometric shrinkage curves, electric voltage and current profiles, impedance spectroscopy diagrams, and scanning electron microscopy micrographs show how anode-electrolyte-cathode ceramic cells can be cosintered at temperatures lower than the usually required.     

A high-performance solid oxide fuel cell with a layered electrolyte for reduced temperatures

The application of conventional zirconia-based electrolytes is limited to relatively high temperatures (ie > 750°C) due to their poor conductivities at low temperatures. Doped ceria has much higher conductivities; however, when exposed to fuel, electronic current develops within the material, which impairs cell performance and efficiency. Herein, we report a novel layered electrolyte structure consisting of a 10 µm samaria-doped ceria primary layer and a 2 µm scandia-ceria-stabilized zirconia protection layer on the fuel side. The cell had five layers and was fabricated using a tape casting and ultrasonic spraying technique. By carefully selecting the raw materials, the bilyer electrolyte was sintered to full density at a low temperature of 1250°C. The adverse interdiffusion and undesirable reactions between the two layers were largely avoided. A fuel cell with the layered electrolyte structure, operated on hydrogen fuel, produced a high open circuit voltage 1.07 V and a power density of 321 mW/cm² at 0.8 V and 600°C, 76% improvement compared to the fuel cell with a scandia-stabilized zirconia/samaria-doped ceria bilayer electrolyte reported in literature.     

Nanostructured engineering of nickel cermet anode for solid oxide fuel cell using inkjet printing

A single-step wet-chemical synthesis of NiO-SDC (Sm³⁺ doped ceria) colloidal ink for the inkjet printing (IJP) of nanostructured anodic layers with enhanced catalytic activity for solid oxide fuel cells (SOFCs) is developed and characterized. Dynamic light scattering, scanning electron microscope, and Raman spectroscopy revealed stable nanoparticles with the main size of 11.85 nm within the ink solution. Rheology parameters were analyzed, and the anode was printed. Porous post-sintered Ni-cermet layer, with a thickness of 15?25 μm contained near-spherical nanoparticles of 40?80 nm, was obtained. X-ray diffraction confirmed the phase composition of the cermet layer. Electrical impedance spectroscopy demonstrated a significant reduction, by more than 80 %, in the area-specific resistance of the IJP half-cell in comparison with the Screen-printed half-cell. The microstructure engineering using IJP provides fabrication of the cermet NiO-SDC layer with a conjugated structure, which ultimately enhances the catalytic activity of the SOFC.     

Synthesis and characterization of co-doped ceria-based electrolyte material for low temperature solid oxide fuel cell

Co-doped CeO₂ (Ba_0.10Ga_0.10Ce_0.80O_3–δ) was synthesized via a cost-effective co-precipitation technique, and the electrochemical properties of the solid oxide fuel cell were studied. The microstructural and surface morphological properties were investigated by XRD and SEM, respectively. The structure of the prepared material was found to be cubic fluorite with an average crystallite size of 36?nm. The ionic conductivity of the prepared BGC (Ba_0.10Ga_0.10Ce_0.80O_3–δ) electrolyte material was measured as 0.071?S?cm^?1. The activation energy was found to be 0.46?eV using an Arrhenius plot. The maximum power density and current density achieved were 375?mW?cm^?2 and 893?mA?cm^?2, respectively, at 650?°C with hydrogen as a fuel. This study shows that the prepared co-doped electrolyte material could be used as a potential electrolyte to lower the operating temperature of solid oxide fuel cells.     

Characterization of core-shell structured Ni@GDC anode materials synthesized by ultrasonic spray pyrolysis for solid oxide fuel cells

Core-shell structured NiO@GDC powders with NiO cores and GDC shells were synthesized by ultrasonic spray pyrolysis (USP) with a four-zone furnace. The morphology of the as-synthesized powders can be modified by controlling parameters such as the precursor pH, carrier gas flow rate, and zone temperature. At high carrier gas flow rates, the as-synthesized core-shell structured NiO@GDC powders have raisin-like morphology with a rough surface; this is due to fast gas exhaustion and insufficient particle ordering. The core-shell structured Ni@GDC anode showed considerable electrochemical performance enhancement compared to the conventionally-mixed Ni-GDC anode. The polarization resistance (R_p) of conventionally-mixed Ni-GDC anodes increases gradually as a function of the operation time. Alternatively, the core-shell structured Ni@GDC anode synthesized by USP does not exhibit any significant performance degradation, even after 500 h of operation. This is the case because the rigid GDC ceramic shell in the core-shell structured Ni@GDC may restrain Ni aggregation.