Water management is essential for high performance operation of PEFCs (Polymer Electrolyte Fuel Cells). In this study, a single cell of PEFC was operated for 180 seconds with various current densities, and at the same time, the water vapor concentrations in the anode and the cathode exhaust gases were measured in high accuracy. The water transport, concentration distribution, and the formation of liquid phase water in the cell were estimated based on the experimental data. The effects of gas flow rate, current density and humidity temperatures of the inlet gases on the behaviors of the water were also investigated. The cell current at which the condensation of the water in the cell begins was determined by extrapolating the water concentration change in the exhaust gases.
Iron porphyrin complexes were applied for the electrochemical detection of superoxide anion radical (O2−•). An electropolymerizable axial ligand, 1-(4-(3-thienyl)benzyl)imidazole was designed and synthesized for the application to a sensor for O2−•. The axial ligand was electropolymerized onto a grassy carbon (GC) electrode. This electrode was immersed into the solution of iron porphyrin complexes. UV-visible absorption spectrum showed that iron porphyrin complexes were successfully bound to the axial ligand, and differential pulse voltammograms showed redox responses near 0 to −0.3 V vs. Ag/AgCl due to Fe2+/3+. These electrodes were applied to detect O2−• produced by the xanthine oxidase (XOD)-catalyzed xanthine oxidation. These electrodes showed a linear relationship between the current and the O2−• concentration.
We investigated the dependence of property, crystal and electrode structure and electrode characteristics on heat treatment for Li1.041Ni0.8Co0.2Oy. Li1.041Ni0.8Co0.2O2 was prepared by solid-state method using performed heat treatment. Crystal structure was determined by X-ray and neutron diffractions using Rietveld analysis. The metal composition of the samples was determined by ICP. Nuclear and electron density images were calculated by MEM / Rietveld analysis using X-ray diffraction. All samples were determined to single phase with a well defined layered structure (R-3m) by XRD, and controlled the composition. From the charge-discharge test after the heat treatment in high PO2 (450°C, PO2 2.03 MPa, 48 h) and Ar reduction (600°C, Ar, 48 h) conditions, discharge capacity decreased. From the crystal structure analysis, the cation mixing of 3a (Li site) and 3b (transition metal site), the bond length between 3b and 6c (oxygen site) increased by heat treatment. From the distributions of electron density, the nature of covalent bond of 3b-6c was weakened by heat treatment. It was suggested that these factors should provide an effective electrode properties.
In recent decades, a Ba1−xSrxTiO3 film has been developed as a dielectric film for many electronic devices. In this work, we focused on an electrophoretic deposition method as a film-forming process, and prepared Ba1−xSrxTiO3 (x=0∼0.3) films by the method using dispersed Ba1−xSrxTiO3 slurries as the bath. As a result, it was found that the film thickness depended on the deposition voltage and time, and homogeneous film with a few µm of thickness could be obtained even with an electrophoretic deposition method by using the slurries. We also studied dielectric properties of the films after sintering. From the results, it was demonstrated that Ba0.9Sr0.1TiO3 film, which was deposited for 4 sec at 80 V and then heat-treated at 1000°C for 15 min under N2 flow, had 2.6 µm of a thickness, and exhibited 162 nF·cm−2 of a capacitance density, 476 of a dielectric constant, 3.4% of a dielectric loss and 3.96×10−8 A·cm−2 of a leak current.
A lithium ion battery module was applied to the running of light rail vehicle for 3 years. The battery was a 15 kWh Mn type lithium ion battery and the relations between running time and voltage, current and integrating electric power were investigated in detail. A running test was carried out during light rail transit to investigate charge performance due to regenerative energy. The lithium ion battery module was quickly charged three times at 150 A by use of a regenerative braking system. Energy savings were estimated at around 22% when charging the lithium ion battery from regenerative energy. From a practical viewpoint, the capacity and cycle performance of the lithium ion battery submodule was examined over a 3-year period and although discharge capacity decreased to about 70% of initial capacity, the battery exhibited good cycle stability.