High performance electrodes for an advanced intermittently operated 10-kW alkaline water electrolyzer

A 10-kW electrolyzer was modified to be used as a technology carrier for components of advanced, intermittently operated alkaline water electrolysis. Activated Mo-containing Raney nickel cathodes and Raney nickel/Co3O4 matrix composite anodes of 600 cm(2) size produced by the vacuum plasma spraying (VPS) technology were used as electrodes in a bipolar electrolyzer of "zero gap" configuration. During various operation modes (constant operation, intermittent operation with and without a protective current during electrolysis standstill) the cell voltage was monitored over a period of 15,000 hours. The electrode performance was studied by measuring temperature dependent polarization curves. The results of the electrochemical investigations and of the degradation behaviour during the different operation modes are presented. The cell voltage measured between cathode and anode at defined reference conditions (300 mA/cm(2), 80 degrees C) was in the range of 1.6-1.65 V which means a specific energy consumption of 3.85-3.95 kWh/Nm(3) and proved stable during the whole test period. (C) 1998 international Association for Hydrogen Energy.