The possibility using a solar battery as a power source for the electrochemical disinfection of microorganisms was examined. A single solar battery with an open circuit voltage 20 V and a capacity of 1 A was used for laboratory scale-examination. The electrochemical disinfection cell containing palladium-coated carbon cloth electrodes was reported previously and a dominant parameter on the disinfection was found to be the concentration of chloride ions. The concentration of NaCl as a source of chloride ions was varied from 0.154 mol dm−3 (saline solution) to 0.00154 mol dm−3 (the concentration being four to ten times that of NaCl in tap water in Tokyo) in this study. Disinfection was examined in only one flow-passage of the microorganisms’ suspension across the electrolytic cell. Escherichia coli was selected as a model microorganism. Disinfection under a clear sky was complete, and was almost complete even under an obscured sky. The viability of E. coli at a current of 100 mA was less than 1×10−6 irrespective of the concentration of NaCl. The viability of E. coli at a current of 50 mA increased to 0.001 in the suspension containing 0.00154 mol dm−3 of NaCl.
Anomalies in tritium enrichment cannot be explained only by isotopic effects in water electrolysis. The temperature dependence of the enrichment factor had been reported as increasing with 1/T. However, the increase was difficult to explain on the basis of kinetics. In this study, electro-osmotic drag (EOD, number of water molecule accompanied by a proton) and tritium enrichment ratio were investigated using light water (H2O) and heavy water (D2O) by solid polymer electrolysis. The EOD decreased and tritium enrichment ratio increased at low temperature for H2O. Electrolysis showed no temperature dependence for D2O. It was revealed that proton hopping by a hydrogen bond network of water molecules (the Grotthuss mechanism) affects the temperature dependence of EOD and tritium enrichment in the case of H2O.
Ni-based electrode-supported cells with a Sc2O3-stabilized ZrO2 electrolyte have been evaluated as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) in intermediate-temperature operation. Using a Ag current collector, a power density of 1.68 W cm−2 at 2.87 A cm−2 and an electrolysis voltage of 1.42 V at 0.57 A cm−2 were obtained at 650°C. The current efficiency in steam electrolysis was almost 100%. This suggests that the high performance is related to decreases in current collector resistance and polarization of the air electrode, due to the formation of Ag current collecting paths on the air electrode. During a 450 h durability measurement in SOEC mode, a degradation rate of 0.056 mV h−1 was observed. Impedance measurements showed the polarization of the steam electrode increased, while the polarization of the air electrode and ohmic resistance showed no change, after the long-term SOEC operation.
Lithium ion pre-doping phenomena of lithium ion capacitor (LIC) and lithium ion battery (LIB) were studied using eight reference electrodes embedded around a negative electrode and a lithium metal electrode. The lithium metal electrode was set in the neighbor of the carbonaceous negative electrode. The negative electrode and the lithium metal electrode were short-circuited, and electric current was measured by using an ammeter. Just after the connection of the negative electrode and the lithium metal electrode, rushed current was observed and it was decreased gradually. The potentials of the negative electrode were decreased gradually from near the lithium metal electrode to the end of the negative electrode. However, the potentials in the horizontal plane of the negative electrode did not become uniform even after 60 hours. Slight electric current between the negative electrode and the lithium metal electrode also was observed even after 60 hours. Potential difference between the lithium metal electrode and the negative electrode becomes the biggest driving force. Temperature becomes an acceleration factor. Great difference was not observed between LIC and LIB in the pre-doping phenomena at 60°C.
In order to check the high rate performance of the Mg2Ge alloy in lithium batteries, the Mg2Ge anodes were prepared as thick films with different areas and/or thickness on copper foil substrates using an aerosol deposition method. A sample film with ca. φ 10 and a weight of 0.1 mg was generally obtained by one-shot deposit in our present equipment, which could be made wider or thicker by multiple shots. From the charge/discharge experiments with the current of more than 1 A g−1, the deposited films were found to work as anode active materials under high rate charge/discharge conditions for lithium secondary batteries, although we had some misgivings about capacity decay in case making films extremely thick. These results denoted that the Mg2Ge anode prepared by the aerosol-deposition method is valuable for development of a secondary battery with high energy and power densities.