Tinglian Wen

Material research for planar SOFC stack

In the present paper, material research dealing with electrolyte, anode, cathode, interconnect and sealant for planar solid oxide fuel cell (SOFC) stack has been reported. Depending on the materials research, a two-cell stack and a 10-cell stack with cell size of 40x40 mm 2 were established and tested. The 10-cell stack at 1000 °C showed a power output of about 10 W and a power density of about 110 mW/cm 2 .

Characteristics of lanthanum strontium chromite prepared by glycine nitrate process

La 1-x Sr x CrO 3 (x=0, 0.1, 0.15, 0.2, and 0.3) (LSC) powder materials were synthesized by the glycine-nitrate-process. XRD analysis indicated that the powder exhibits a single phase with perovskite structure. The mean primary particle size of the powder was around 30 nm based on the morphology observation by TEM. The sinterability of the powder was improved as Sr doping content x increases in the investigated doping range. The electrical conductivity measurement of the sintered material revealed that LSC reached a maximum at x = 0.2. The synthesized La 0.8 Sr 0.2 2 CrO 3 powder was used to make a coating layer on the substrate of Cr plate by plasma flame spraying technique. The preliminary experimental results showed that LSC coated Cr could be used as the interconnect for SOFC.

A solid oxide cell yielding high power density below 600 °C

Here we report solid oxide cells with thin strontium- and magnesium-doped lanthanum gallate electrolytes that yield power densities of 1.06 W cm−2 at 550 °C and 0.81 W cm−2 at 500 °C when operated on humidified hydrogen and ambient air. Cost-effective ceramic processing and chemical solution impregnation methods were utilized, yielding a dual micron- and nano-scale architecture that is essential for achieving good low-temperature performance.

A study of (Pr, Nd, Sm)1−xSrxMnO3 cathode materials for solid oxide fuel cell

Abstract Rare earth (Pr, Nd, Sm) manganite cathode materials with formula Ln 1− x Sr x MnO 3 were obtained from oxides by solid reaction at temperature of 1400°C. The produced compounds display an orthorhombic perovskite structure similar to LaMnO 3 when x ≤0.5. The results of electrical conductivity measurement show that the three rare earth manganites exhibit about 0.5 to one order of magnitude higher in conductivity than La 1− x Sr x MnO 3 at above 500°C. Thick film of the synthesized manganites were formed on YSZ solid electrolyte by spin-coating technique. The morphology and reaction of the interface between the YSZ electrolyte and rare earth manganites cathode film were investigated by SEM and XRD.

Research on planar SOFC stack

The present paper reports the achievement of solid oxide fuel cell (SOFC) stack research in Shanghai Institute of Ceramics, Chinese Academy of Sciences. Single column SOFC stacks with internal manifolding and cross-flow structure were established and successfully operated. The investigation of materials and components relating the stacks are also briefly described.

Multilayer tape-casting method for anode-supported planar SOFCs

We have developed a multilayer tape-casting and co-sintering process to fabricate a large-area, anode-supported electrolyte film, which is critical for planar-type, reduced-temperature solid oxide fuel cells (SOFCs). Nickel/yttria-stabilized zirconia (Ni/YSZ), nickel/scandia-stabilized zirconia (Ni/ScSZ) cermets, ScSZ, Ce 0.8 Gd 0.2 O 1.9 (CGO), and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3δ (LSCF)–CGO were used as materials for anode substrate, anode functional layer, electrolyte, interlayer and cathode, respectively. The powders of these functional layers were ball-milled with organic additives to form slurries, which were assembled together with the multilayer tape-casting procedure to get the green tapes. After drying, the green tape was co-sintered at 1400°C for 4 h in air to get the large-area, anode-supported electrolyte film (thickness 15 μm). For cell preparation, the LSCF–CGO composite cathode was deposited by the screen-printing method and sintered at 1100°C for 3 h. The area-specific resistance (ASR) of the obtained single cell was found to be 0.99 ωcm 2 at 850°C with H 2 /O 2 as the operating gases, and the maximum power density achieved was 0.63 W/cm 2 . The thickness of the (Zr,Ce)O 2 -based solid solution formed at the ScSZ/CGO interface during high-temperature sintering was investigated. The results illustrate that fabrication of an anode-supported electrolyte film for planar SOFCs with a CGO interlayer is possible by the multilayer tape-casting procedure, which is both cost-effective and feasible.

Effect of samarium doped ceria nanoparticles impregnation on the performance of anode supported SOFC with (Pr0.7Ca0.3)0.9MnO3−δ cathode

Abstract Solid oxide fuel cell (SOFC) electrodes, after a high temperature sintering, may be impregnated to deposit nanoparticles within their pores to enhance the catalytic function. Samarium doped CeO 2 (SDC) nanoparticles were infiltrated into (Pr 0.7 Ca 0.3 ) 0.9 MnO 3−δ (PCM) cathode of anode supported SOFC cells. The cell with 2.6 mg/cm 2 SDC impregnated in cathode showed the maximum power density of 580 mW/cm 2 compared with 310 mW/cm 2 of the cell without impregnation at 850 °C. The cells were also characterized with the impedance spectra, and the SDC impregnation significantly reduced the polarization resistance. After performance test the cells were characterized with scanning electron microscopy (SEM), and the cathode morphology showed the impregnated SDC particles were nanosized and were deposited on the surface of the PCM framework. The possible mechanism for the performance improvement was discussed.

Chemical compatibility of RE0.6M0.4Mn0.8Co0.2O3-δ (RE = La, Pr, Nd, Sm and Gd; M = Sr and Ca) with yttria stabilized zirconia

Abstract The chemical compatibility of one new series, RE 0.6 M 0.4 Mn 0.8 Co 0.2 O 3-δ (RE=La, Pr, Nd, Sm and Gd; M=Sr and Ca), with yttria stabilized zirconia (YSZ) has been examined. Powder mixtures of perovskites and YSZ were annealed at 1200° for 24h in air. RE 0.6 M 0.4 Mn 0.8 Co 0.2 O 3-δ showed different compatibility towards YSZ for M=Sr and Ca, respectively. The formation of SrZrO 3 was identified by X-ray diffraction analysis as a reaction product for RE 0.6 Sr 0.4 Mn 0.8 Co 0.2 O 3-δ . In contrary, there is no reaction product for RE 0.6 Ca 0.4 Mn 0.8 Co 0.2 O 3-δ . EDX analysis revealed that there is a larger difference between the solubility of Sr and Ca in YSZ. The bond-valence model was used to discuss the different compatibility of Sr and Ca series perovskites with YSZ. The present studies also showed that the formation of SrZrO 3 was favored for larger disorder effect due to size difference between A-site RE 3+ and Sr 2+ in RE 0.6 Sr 0.4 Mn 0.8 Co 0.2 O 3-δ .

AES investigation of anodic film on HCT crystal

Auger Electron spectrum (AES) study has been carried out on the anodic film which was deposited by electrochemical method on the surface of Hg1-xCdxTe (HCT) crystal with x approximately equals 0.21. The element depth profile within the film and at the interface with substrate crystal was analyzed by means of Ar+ ions sputtering. The influences of current density, potential and electrolyte concentration during electrochemical deposition on the film structure are manifested.