Electrochemical and degradation behaviour of single cells comprising Ni-GDC fuel electrode under high temperature steam- and co-electrolysis conditions

Solid oxide electrolysis cells – current material development and industrial application

“…Analysis of the polarization resistance in gas atmospheres with 25% and 45% CO 2 resulted in R P values for Ni-SDC for both gas mixtures around 0.17 Ω cm 2 , whereas the R P values for Ni-YSZ were 0.46 Ω cm 2 and 0.53 Ω cm 2 in 25% and 45% CO 2 respectively. The performance of a Ni-GDC (65 : 35 wt%)/YSZ/GDC/LSCF cell configuration under steam and co-electrolysis operation was examined at a set voltage of 1.5 V. 362 Current densities in steam electrolysis reached −1.31 A cm −2 at 900 °C and −0.41 A cm −2 at 750 °C, while the corresponding R P increased from 0.061 Ω cm 2 to 0.31 Ω cm 2 with decreasing temperature. The current density value for co-electrolysis at 900 °C was −1.37 A cm −2 , corresponding to an R P of 0.089 Ω cm 2 .…”

“…Ni-GDC fuel electrodes were tested with the same cell composition in co-electrolysis and steam electrolysis operation at 900 °C with a current of −0.5 A cm −2 for 500 h. 362 In co-electrolysis conditions, the resulting degradation rate of 308 mV kh −1 was lower than the degradation observed for steam electrolysis (499 mV kh −1 ). The polarization resistance over time also increased from 0.07 Ω cm 2 to 0.28 Ω cm 2 in steam electrolysis, and from 0.10 Ω cm 2 to 0.16 Ω m 2 in co-electrolysis operation.…”

“…Besides the Ni agglomeration/particle growth, Ni depletion, and a loss of GDC percolation with GDC-covered Ni particles were found. 362 A long-term stability test of a 3Mo-3Au-Ni-GDC/YSZ/GDC/LSCF cell configuration was conducted for 1700 h at a temperature of 900 °C and in a 7% H 2 + 30% N 2 + 63% H 2 O atmosphere with a set current density of −0.3 A cm −2 . 363 During the 1700 h of operation, an increase in cell voltage from 0.99 V to 1.05 V was observed with an overall degradation rate of 33 mV kh −1 .…”

Comparison of the Electrochemical and Degradation Behaviour of Ni-YSZ and Ni-GDC Electrodes Under Steam, Co- and CO2 Electrolysis

“…Detailed cell fabrication steps are reported in [17]. To make the electrode paste, NiO-GDC powder was mixed in a solution of 6 wt.…”

“…The single cells were electrochemically characterized using a NorEcs Probostat™ set-up. For the electrochemical measurements, the cell was heated up to 900 °C (at 1°/min), followed by a gradual reduction of the Nickel oxide cermet (NiO-GDC) to Nickel (Ni-GDC) as reported in [17]. In the reduction procedure, the H 2 gas composition was systematically increased to 100% .…”