We observed the memory effect, the working voltage lowering, which occurred due to the repeated partial charge-discharge cycling of a Ni-capacity-limited alkaline cell, for example 50–70% state of charge, and γ-NiOOH in the Ni electrode was identified as the cause of the memory effect. During this condition, γ-NiOOH is proposed to be formed by partial overcharging due to the heterogeneity of the conductive materials such as cobalt compounds in the Ni electrode. Using nano-sized conductive materials homogeneously dispersed in the electrode leads to a significant effect on the suppression of the memory effect occurring due to the repeated partial charge-discharge cycling.
Al secondary batteries with the ambient-temperature chloroaluminate molten salt electrolyte have been developed. Various conducting polymers were evaluated in order to improve the positive electrode. Among them, the electrochemical characteristics of poly-p-phenylene (PPP) film were the most excellent. In the case of the charging below 50 mAh g−1, the charge/discharge efficiency was around 100%. It was found that the PPP film electrode operated well as the positive electrode for Al secondary battery.
Anodic electrodes for ozone generation were prepared with lead dioxide particles of various diameters. The lead dioxide particles were characterized with X-ray diffraction analysis, and the electrodes were characterized and performed for ozone generation. It was revealed that both the diameters of the lead dioxide particles and the contents of the pore forming agent have great effect on the performance of the electrodes. With decreasing of the diameters of the lead dioxide particles from the range of 55–74 µm to the range of 15–35 µm, the performance of the electrodes improved. But no further improvement was found with further decreasing of the particle diameters to the range of 5–15 µm. However, by employing an appropriate amount of pore forming agent during the electrode preparations, the performance of the anodic electrode can be improved. The optimized weight ratio of ammonium oxalate to lead dioxide is 1.33/100.
We report on the control of photo-assisted electrodeposition of several kinds of noble metal on p-type Si by adjusting the illumination condition. In the case of Pt and Cu, the deposition rate and the particle density of metal deposits under illumination were considerably higher than those obtained in the dark, because illumination produces photo-excited electrons and enables another channel through the conduction band for charge transfer in addition to the channel through the valence band which is used in the dark. Using this difference in deposition rate between these two conditions, we have succeeded in control of the morphology of Cu layer on p-type Si without changing applied potential, as well as the Pt system. The nucleation of metal particles could be controlled by modulating illumination duration and light intensity, and the nuclei could be grown in the dark. On the other hand, it was difficult to control the deposition of Pd and Au by modulating illumination, because they were spontaneously deposited even in the dark by their rapid immersion plating rate on p-type Si.