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 f or components of advanced, intermittently operated alkaline water elec trolysis. Activated Mo-containing Raney nickel cathodes and Raney nick el/Co3O4 matrix composite anodes of 600 cm(2) size produced by the vac uum plasma spraying (VPS) technology were used as electrodes in a bipo lar electrolyzer of ''zero gap'' configuration. During various operati on 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. T he results of the electrochemical investigations and of the degradatio n behaviour during the different operation modes are presented. The ce ll voltage measured between cathode and anode at defined reference con ditions (300 mA/cm(2), 80 degrees C) was in the range of 1.6-1.65 V wh ich means a specific energy consumption of 3.85-3.95 kWh/Nm(3) and pro ved stable during the whole test period. (C) 1998 international Associ ation for Hydrogen Energy.