Design and performance evaluation of a novel 1Â kW-class hydrogen production/power generation system

A 1 kW-class electrochemical reactor for hydrogen production was developed using bipolar plates. To fabricate thick, large-area electrodes, a particle electrode fabrication method was also introduced. Scanning electron microscopy with energy dispersive X-ray spectroscopy and galvanostatic performance measurements were performed to evaluate the particle electrodes. The results show that the particle electrodes exhibit an excellent charge performance despite the electrode material layer being relatively thick and highly porous. The electrochemical reactor contained 20 single cells stacked together with 30 A h of nickel hydroxide and 15 A h of metal hydride as the positive and negative electrodes, respectively. The electrochemical tests showed that the stack exhibited a high hydrogen production efficiency with a maximum current efficiency of 95.3% for hydrogen production and a hydrogen evolution amount per unit input electrical energy of 259.1 mL/W h at 0.2 C. At high current densities (2.0 C), a rapid temperature increase was also observed during the charging process, which led to a reduction of the hydrogen production efficiency. Therefore, further design modifications are needed to control heat generation during operation of the device.