GAO Yue, HUANG Xiaoying, WANG Shuai, WU Yujie, LIU Jiehui, LYU Zhe
(School of Physics, Harbin Institute of Technology, Harbin 150001, Heilongjiang, China)
Abstract: During the long-term operation of Ni-YSZ anode-supported membrane solid oxide fuel cells (SOFCs), degradation in cell performance occurs due to the loss of Ni in the anode functional layer (AFL). However, there is still no reasonable explanation for the microscopic process and migration driving force of the Ni loss phenomenon. The variation in performance SOFC with dry and wet hydrogen as fuel was first tested. Then, scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) were used to characterize the distribution of Ni in the AFL region of the anode and different layers of the anode supporter. It was found that the performance of the cell using wet hydrogen fuel was less degraded and the Ni migration effect was depressed. Based on this observation, a Ni migration model was proposed, basing on the collisions of water molecules, hydrogen molecules and Ni(OH)2 molecules. It is assumed that the directional migrations of fuel hydrogen and product water vapor caused the difference in momentum-change of Ni(OH)2, thus proving that the driving force of Ni migration is from AFL to porous Ni-YSZ support.
Key words: SOFC; anode; Ni migration; performance degradation; molecular collision