Journal article
Microstructural Degradation of Ni/YSZ Electrodes in Solid Oxide Electrolysis Cells under High Current
Department of Energy Conversion and Storage, Technical University of Denmark1
Mixed Conductors, Department of Energy Conversion and Storage, Technical University of Denmark2
Imaging and Structural Analysis, Department of Energy Conversion and Storage, Technical University of Denmark3
Applied Electrochemistry, Department of Energy Conversion and Storage, Technical University of Denmark4
Ni/yttria stabilized zirconia (YSZ) supported solid oxide electrolysis cells (SOECs) were exposed to long-term galvanostatic electrolysis tests, under different testing conditions (temperature, gas composition, current density etc.) with an emphasis on high current density (above −1 A/cm2). Detailed post-mortem characterizations were carried out to investigate microstructural changes after long-term galvanostatic tests, focusing on the Ni/YSZ electrode.
Formation of ZrO2 nano-particles on Ni surfaces was observed in cells exposed to −1 or −1.5 A/cm2 at 800 or 850°C, but not in those tested at current densities below −0.75 A/cm2. The formation of ZrO2 nano-particles deteriorates Ni percolation and presumably decreases the number of active triple phase boundaries (TPBs) and is therefore considered a degradation phenomenon.
It is hypothesized that the degradation of the Ni surface is a result of Ni-YSZ interfacial reactions, taking place under the conditions prevailing under strong polarization. A mechanism for the formation of ZrO2 nano-particles on the Ni surface under the electrolysis cell testing is proposed and the possibility of Ni-YSZ interfacial reactions under such conditions (T, p(O2)) is further elucidated by thermodynamic calculations.
Language: | English |
---|---|
Publisher: | The Electrochemical Society |
Year: | 2013 |
Pages: | 20F883-F891 |
ISSN: | 19457111 and 00134651 |
Types: | Journal article |
DOI: | 10.1149/2.098308jes |
ORCIDs: | Chen, Ming , Bentzen, Janet Jonna , Sun, Xiufu , Hauch, Anne , Bowen, Jacob R. and Hendriksen, Peter Vang |