Pressure-induced evolution in the durability of nickel-metal hydride batteries under high-current charge.

We found that an AAA-type battery (min. 750 mAh) pressurized with Ar or N at pressures of up to 5 MPa exhibited a significant durability enhancement even under high-current conditions. As an example of a charge-discharge cycle test at 3 amperes, the residual ratio of capacity at atmospheric pressure decreased to approximately 90% of the standard capacity before 50 cycles.

Kinetic Modelling of Electroless Nickel-Phosphorus Plating under High Pressure.

In electroless nickel-phosphorus plating (ENPP), growth of the plated layer under high pressure was found to be faster than under ambient pressure. To quantitatively elucidate the effect of high pressure on the mechanism of the ENPP reaction, we propose a kinetic model that takes into account both mass transfer and reaction of the chemical species present in the plating solution. We solved the mass balance equations between the chemical species to calculate the transient changes in the thickness of the plated layer as well as the concentrations of the chemical species in the plating solution.

Catalytic activity of noble metals for metal-assisted chemical etching of silicon.

Metal-assisted chemical etching of silicon is an electroless method that can produce porous silicon by immersing metal-modified silicon in a hydrofluoric acid solution without electrical bias. We have been studying the metal-assisted hydrofluoric acid etching of silicon using dissolved oxygen as an oxidizing agent. Three major factors control the etching reaction and the porous silicon structure: photoillumination during etching, oxidizing agents, and metal particles.