ChemInform Abstract: Preparation of Thin Layer Materials with Macroporous Microstructure for SOFC Applications (original) (raw)
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Preparation of thin layer materials with macroporous microstructure for SOFC applications
Journal of Solid State Chemistry, 2008
A facile and versatile method using polymethyl methacrylate (PMMA) microspheres as pore formers has been developed to prepare thin layer oxide materials with controlled macroporous microstructure. Several mixed oxides with fluorite and perovskite-type structures, i.e. doped zirconia, ceria, ferrites, manganites, and NiO-YSZ composites have been prepared and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and mercury porosimetry. The synthesised materials are nanocrystalline and present a homogeneous pore distribution and relatively high specific surface area, which makes them interesting for SOFC and catalysis applications in the intermediate temperature range. r
Journal of Power Sources, 2010
A facile solid-phase conversion route is proposed to fabricate a micro-framework of ␣-MnO 2 with a nanofibrous structure and high porosity. The fabrication is achieved by a three-step process using a preformed manganese tartrate with a rectangular framework as the precursor followed by thermal annealing and hydrothermal oxidation to form the final nanofibrous structure. Evolution of the phase and the morphology are characterized by FESEM, XRD, TG-DTA, and TEM measurements. The electrochemically active material ␣-MnO 2 exhibits both attractive stability of the Coulombic efficiency after long-term cyclic charging/discharging and acceptable specific capacitance.
Review on microfabricated micro-solid oxide fuel cell membranes
Journal of Power Sources, 2009
Micro-solid oxide fuel cells (-SOFC) are promising power sources for portable electronic devices. This review presents the current status of development of microfabricated micro-solid oxide fuel cell membranes for power delivery. The -SOFC membranes are developed using micro-electro-mechanical system (MEMS) fabrication and machining techniques. The different designs of free-standing -SOFC membranes and -SOFCs deposited on porous substrates are presented. The materials used in the -SOFC anode, electrolyte and cathode are discussed and compared along with their microstructures. The electrical performance data of the different -SOFC designs are compared and discussed. High -SOFC performances of 677 mW cm −2 were demonstrated at temperatures as low as 400 • C.
Pyrolyzable pore-formers for the porous-electrode formation in solid oxide fuel cells: A review
Ceramics International, 2018
Porosity is a key property that plays a crucial role in enhancing the performance of solid oxide fuel cell (SOFC) electrodes. The addition of pyrolyzable pore-formers to the electrode materials of SOFCs can generate suitable porous microstructures with the required porosity, pore sizes, and morphology. The present review provides details on the characterization and microstructural analysis, firing profile, electrical conductivity, mechanical strength, and gas permeability of the porous electrodes of SOFCs. A better understanding of these relationships can help to design optimized porous microstructures for generating higher power densities of the cells.
Ceramics International, 2015
We describe the manufacture and electrochemical characterization of micro-tubular anode supported solid oxide fuel cells (mT-SOFC) operating at intermediate temperatures (IT) using porous gadolinium-doped ceria (GDC: Ce 0.9 Gd 0.1 O 2−δ) barrier layers. Rheological studies were performed to determine the deposition conditions by dip coating of the GDC and cathode layers. Two cell configurations (anode/electrolyte/barrier layer/cathode): single-layer cathode (Ni-YSZ/YSZ/GDC/LSCF) and double-layer cathode (Ni-YSZ/YSZ/GDC/LSCF-GDC/LSCF) were fabricated (YSZ: Zr 0.92 Y 0.16 O 2.08 ; LSCF: La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ). Effect of sintering conditions and microstructure features for the GDC layer and cathode layer in cell performance was studied. Current density-voltage (j-V) curves and impedance spectroscopy measurements were performed between 650-800 °C, using wet H 2 as fuel and air as oxidant. The doublecathode cells using a GDC layer sintered at 1400 °C with porosity about 50% and pores and grain sizes about 1 µm, showed the best electrochemical response, achieving maximum power densities of up to 160 mW cm −2 at 650 °C and about 700 mW cm −2 at 800 °C. In this case GDC electrical bridges between cathode and electrolyte are preserved free of insulating phases. A preliminary test under operation at 800 °C shows no degradation at least during the first 100 h. ! ! 2! These results demonstrated that these cells could compete with standard IT-SOFC, and the presented fabrication method is applicable for industrial-scale.
Micro solid oxide fuel cells Status challenges and chances 2009 Monatshefte fur Chemie
Micro-solid oxide fuel cells (micro-SOFC) are predicted to be of high energy density and are potential power sources for portable electronic devices. A micro-SOFC system consists of a fuel cell comprising a positive electrode-electrolyte-negative electrode (i.e. PEN) element, a gas-processing unit, and a thermal system where processing is based on micro-electro-mechanical-systems fabrication techniques. A possible system approach is presented. The critical properties of the thin film materials used in the PEN membrane are discussed, and the unsolved subtasks related to micro-SOFC membrane development are pointed out. Such a micro-SOFC system approach seems feasible and offers a promising alternative to state-of-the-art batteries in portable electronics. Keywords Micro-solid oxide fuel cell Á Thin film deposition Á MEMS Á Microfabrication Á Gas processing Á Thermal system
Thin films for micro solid oxide fuel cells
Journal of Power Sources, 2007
Thin film deposition as applied to micro solid oxide fuel cell (SOFC) fabrication is an emerging and highly active field of research that is attracting greater attention. This paper reviews thin film (thickness ≤1 m) deposition techniques and components relevant to SOFCs including current research on nanocrystalline thin film electrolyte and thin-film-based model electrodes. Calculations showing the geometric limits of SOFCs and first results towards fabrication of SOFCs are also discussed.
2008 Micro-solid oxide fuel cells.pdf
Micro-solid oxide fuel cells (micro-SOFC) are predicted to be of high energy density and are potential power sources for portable electronic devices. A micro-SOFC system consists of a fuel cell comprising a positive electrode-electrolyte-negative electrode (i.e. PEN) element, a gas-processing unit, and a thermal system where processing is based on micro-electro-mechanical-systems fabrication techniques. A possible system approach is presented. The critical properties of the thin film materials used in the PEN membrane are discussed, and the unsolved subtasks related to micro-SOFC membrane development are pointed out. Such a micro-SOFC system approach seems feasible and offers a promising alternative to state-of-the-art batteries in portable electronics. Keywords Micro-solid oxide fuel cell Á Thin film deposition Á MEMS Á Microfabrication Á Gas processing Á Thermal system
Solid State Ionics, 2008
This paper reports a study on the deposition of sol particles for the preparation of thin and ultra-thin electrolyte membrane layers (thickness b 5 μm-50 nm), which cannot be produced with regular powder-based processes. For the deposition process, a range of coating liquids with varying particle sizes, covering the complete range between standard suspensions with a particle size of several 100 nm and nano-particle sols, was prepared. In the first part, it is demonstrated that a colloidal sol route can be used for membrane formation on a regular macroporous SOFC anode (NiO/zirconia), when the sol particle size is adapted to the pore structure of the anode (particle size ∼ 200 nm). SEM characterization indicated a thickness in the range 3-4 μm after calcination at 600°C and ca. 2 μm after sintering at 1400°C, far below the limit for conventional powder-based deposition methods. In the second part, ultra-thin zirconia and ceria membrane films are prepared by spraying sols containing nanoparticles (average size 5-6 nm). The layers show a thickness of ∼ 100 nm, a very narrow particle size distribution and tight ultra-microporous structure, which allows a sintering treatment below 1000°C, and can be used as an additional electrolyte layer for improving the leak rate of the cell or as diffusion barrier.
Micro-solid-oxide-fuel-cells-Status,-challenges,-and-chances_2009_Monatshefte-fur-Chemie.pdf
Micro-solid oxide fuel cells (micro-SOFC) are predicted to be of high energy density and are potential power sources for portable electronic devices. A micro-SOFC system consists of a fuel cell comprising a positive electrode-electrolyte-negative electrode (i.e. PEN) element, a gas-processing unit, and a thermal system where processing is based on micro-electro-mechanical-systems fabrication techniques. A possible system approach is presented. The critical properties of the thin film materials used in the PEN membrane are discussed, and the unsolved subtasks related to micro-SOFC membrane development are pointed out. Such a micro-SOFC system approach seems feasible and offers a promising alternative to stateof-the-art batteries in portable electronics.