Quantitative Characterization of SOFC Nickel-YSZ Anode Microstructure Degradation Based on Focused-Ion-Beam 3D-Reconstruction Technique

Abstract

The anode microstructural evolution is correlated to its electrochemical characteristics during a long time discharge for conventional nickel-yttria-stabilized zirconia composite anode. Self made anode performance degraded with operation time in humidified hydrogen, with the increases of both ohmic and polarization losses. The anode samples after different discharging times were analysized by 3dimensional microstructure reconstruction based on focused ion beam-scanning electron microscopy technique. Nickel connectivity, nickel-yttria-stabilized zirconia interface area and the active three-phases-boundary length were correlated to the anode degradation. The influences of bulk gas humidity and current density were also investigated to reveal their contributions to the anode degradation.

3D reconstruction size effect on the quantification of solid oxide fuel cell nickel–yttria-stabilized-zirconia anode microstructural information using scanning electron microscopy-focused ion beam technique

“…It has been proven in Ref. [6] that YSZ can be treated as a stable phase without morphological change in the current operation environment. In order to quantify the microstructure change in operation, the phase volume fractions of percolated, isolated and unknown-status Ni phases were measured based on the 3D reconstructions and summarized in Table 1.…”

“…The details of dual-beam FIB-SEM observation technique have been introduced in Refs. [6,11]. The 3D microstructure of the Ni-YSZ anodes before and after 500 h operation were virtually reconstructed based on 2D image series, as shown in Figs Ni phase (red isolated particle, yellow unknown-status particle) and c YSZ phase after reduction.…”

“…The usual operation temperature for SOFC anode made of nickel-yttria-stabilized zirconia (Ni-YSZ) [1], ranged from 973 to 1273 K, results in the challenge of long time stability and durability of SOFC electrodes. The SOFC anode degradation mechanism has been intensively investigated, which is mainly caused by Ni coarsening, especially during the initial operation period [2][3][4][5][6]. Recently, three-dimensional (3D) reconstructions of SOFC electrode has been achieved by applying focused ion beamscanning electron microscopy (FIB-SEM) technique [6][7][8][9][10][11].…”

“…The SOFC anode degradation mechanism has been intensively investigated, which is mainly caused by Ni coarsening, especially during the initial operation period [2][3][4][5][6]. Recently, three-dimensional (3D) reconstructions of SOFC electrode has been achieved by applying focused ion beamscanning electron microscopy (FIB-SEM) technique [6][7][8][9][10][11]. This technique provides quantitative information of composite cermet microstructure in 3D, which can be correlated to the electrode performance via specific surface areas and active three-phase boundary density [1].…”

Degradation study by 3D reconstruction of a nickel–yttria stabilized zirconia cathode after high temperature steam electrolysis operation

“…It is worth noting that several 3D reconstructions of this electrode have been already reported in literature [12e21]. Nevertheless, among all these studies, very few have been dedicated to assess the three dimensional cermet microstructure change in operation [14,15,20,21]. For instance, Wilson et al [14] and Nelson et al [15] have compared the microstructure of a reference cell and a cell that was tested up to 1130 h in SOFC mode.…”