The effect of the presence of fine YSZ particles on the performance of porous nickel electrodes

The electrochemical performance of a porous nickel electrode with its surface modified by deposition with fine yttria-stabilised zirconia (YSZ) powder is compared with that of the 'bare' electrode. Image analysis of the electrode microstructure yields values for the triple phase boundary (TPB) length in the range of 45-61 m cm(-2). The nickel coverage is in the range of 55-72%. The hydrogen oxidation reaction studied on the two types of electrodes indicates that the electrode reaction is dominated by one process, suggesting a common rate-determining step. The total electrode conductivity increases with increasing TPB length. However, at similar TPB length the electrode conductivity of the modified porous nickel electrode is considerably higher than that of the bare nickel electrode. This result indicates that the presence of fine YSZ particles on the nickel electrode surface creates additional active sites onto which the electrode reaction can proceed. The data of this study are interpreted to reflect an active role for YSZ in the Ni/YSZ SOFC cermet anode. (C) 2000 Elsevier Science B.V. All rights reserved.