Kazunari Sasaki

The influence of fuel impurity on power generation characteristics of solid oxide fuel cells (SOFCs) has been analyzed by measuring cell voltage at a constant current density, as a function of concentration, operational temperature, and fuel gas composition. Reversible cell voltage change was observed around , while fatal irreversible degradation occurred at a lower operational temperature, at a higher concentration, and at a lower fuel ratio. Sulfur tolerance of SOFCs was improved by using -dop

Using thermochemical data of ca. 300 compounds consisting of carbon, hydrogen, and oxygen, the amounts of equilibrium products have been calculated for various fuel cell fuels including alkanes alcohols alkenes, alicyclic hydrocarbons, and dimethyl ether, as well as for other hydrocarbon-containing fuels such as biogas and coke oven gas, in the temperature range between 100 and 1000°C. It has been revealed that the major constituents in typical fuel cell gases in thermodynamic equilibrium are CO

Because chemical compositions in thermodynamic equilibrium for various fuel gases are specified by the ratios among carbon, hydrogen, and oxygen, carbon-hydrogen-oxygen (C-H-O) ternary diagrams are useful to present relevant operational conditions of fuel cells. Such C-H-O ternary diagrams are constructed, describing the carbon deposition region, the fuel gas region, partial pressures of gaseous species including O 2 , H 2 , and CO, and electromotive force corresponding to the theoretical open c

Microstructure, cathodic polarization, and ohmic resistance on the cathode side of ‐based solid oxide fuel cells have been studied for the intermediate temperature operation range between 700 and 900°C. Starting powder characteristics, powder calcination temperature, and sintering temperature strongly influence the final microstructure of cathodes. Electrochemical performance depends on these processing parameters as well as on the cathode thickness and the contact spacing of current collectors.

Using oxides as examples, the defect chemistry is systematically analyzed for a low-temperature regime, at which the oxygen exchange equilibrium reaction is no longer reversible, while the internal defect equilibrium reactions (in particular, the electronic transfer processes) may still be reversible. For the partially frozen-in states as well as for the complete equilibrium cases, defect concentrations are numerically calculated for idealized model oxides including pure, acceptor-doped, and don

System durability is crucially important for the successful commercialization of fuel cell electric vehicles (FCEVs). Conventional accelerated durability testing protocols employ relatively high voltage to hasten carbon corrosion and/or platinum catalyst degradation. However, high voltages are strictly avoided in commercialized FCEVs such as the Toyota MIRAI to minimize these degradation modes. As such, conventional durability tests are not representative of real-world FCEV driving conditions. H

Redox-stable solid oxide fuel cell (SOFC) anodes are developed in order to improve durability at higher fuel utilization, as a possible alternative to conventional Ni-zirconia cermet anodes. Ce0.9Gd0.1O2 (GDC) is utilized as a mixed ionic and electronic conductor (MIEC), in combination with Sr0.9La0.1TiO3 (LST) as an electronic conductor. The stability of noble metals (Rh, Pt, and Pd) is analyzed via thermochemical calculation of stable phases. Noble metal catalyst nanoparticles are incorporated

Power generation characteristics of solid oxide fuel cells (SOFCs) for alcohol-based fuels are measured and compared with those for simulated reformed gas in equilibrium compositions. We demonstrate direct-alcohol SOFCs for methanol, ethanol, propanol, and butanol. Current-voltage characteristics for the methanol-based fuel are comparable to those for the simulated reformed gas at 1000°C because of fast kinetics for thermal decomposition of methanol with With increasing carbon number of alcohols

Current-voltage (I-V) characteristics and electrode impedance of a tubular-type solid oxide fuel cell (SOFC) were analyzed for mixed fuel gases, consisting mainly of CO, and a carrier gas, as simulated reformed gas of hydrocarbons or coal gas. I-V characteristics of a single cell were measured as a function of various operational parameters including the -to-CO ratio, the type of carrier gas such as He, and Ar, the temperature, the fuel-to-carrier gas ratio, and the water vapor concentration. It

Durability of electrocatalysts under severe operational conditions of polymer electrolyte fuel cells (PEFCs) is one of the most important technological issues to be improved. Alternative electrocatalyst support materials are desired, the use of which may solve problems such as oxidation-induced carbon support corrosion. One interesting solution is to use conductive oxide-based catalyst support. We focus our attention to SnO2, known as an oxide semiconductor with a high electronic conductivity. N