Solid Oxide Electrolyser Cell Testing Up to the Above 30,000 h Time Range

Abstract

A running steam electrolysis test with a 10Sc1CeSZ electrolyte supported cell with Ni/GDC hydrogen and LSCF oxygen electrodes has passed 34,000 h with -0.6 Acm-2 current density. The high specific ionic electrolyte conductivity allowed a moderate initial cell temperature (~780°C) for operation with a cell voltage close to the thermal neutral voltage (U th ~1.29 V), i.e. with highest energy-conversion efficiency. Part of the wide margin for temperature increase was used for compensation of the voltage degradation, done after 20 and 31 kh, respectively. The resulting compensation rate of 0.9°C/kh extrapolates to a degradation compensated lifetime beyond current system requirements (>50,000 h). Compensation was traced with voltage-current curves and with impedance. Voltage degradation for constant temperature amounted, after several kh initial stabilisation, to (4 - 5) mV/kh (0.3 - 0.4 %/kh). Degradation was mainly ohmic, without clearly detectable non-ohmic electrode contributions. Non-ohmic terms therefore added to the compensation of ohmic degradation via temperature increase.