Temperature dependence of the polarization resistance of the O2,Au/La0.88Sr0.12Ga0.82Mg0.18O2.85 electrode system

Abstract

The impedance of a porous gold electrode in contact with solid electrolyte La 0.88 Sr 0.12 Ga 0.82 Mg 0.18 O 2.85 and the effect of the manufacture conditions on its polarization resistance are studied at 600-800°ë in air. The overall oxygen reaction rate on a gold electrode is described as the sum of two partial constituents, namely, the oxygen exchange at the gas/electrolyte interface at the gold/gas/electrolyte triple-phased boundary.

Interaction of solid electrolyte La0.88Sr0.12Ga0.82Mg0.18O2.85 with hydrogen, water vapor, and carbon dioxide

“…As it was shown previously in [1] that a change in the polarization resistance of a gold electrode is a sufficiently sensitive test with regard to a change in the electrolyte properties, studying impedance spectra was selected as an experimental method. For the manufacture of gold electrodes we used a paste on the basis of gold oxide-hydroxide.…”

“…In [12], where investigations of an electrolyte of the composition La 0.8 Sr 0.2 Ga 0.8 Mg 0.17 Fe 0.03 O 3 -α were conducted in close conditions, no change whatsoever was discovered in the electrolyte. As, in the course of 1 Here and in what follows the numbers show the percentage of substitution of strontium for lanthanum and magnesium for gallium, respectively. For example, the composition of the electrolyte used in this investigation La 0.88 Sr 0.12 Ga 0.82 Mg 0.18 O 2.85 has the designation LSGM12-18.…”

“…One summand was assumed to be associated with the properties of gold as an electrode and could presumably be attributed to a process at the triple-phase boundary. This summand was called σ η (1) . The magnitude of the partial polarization conductivity σ η (1) depends but weakly on the electrode manufacture conditions.…”

“…In the cases where the contribution of σ η (2) is small, i.e. where the overall polarization conductivity of the electrode is provided for only at the expense of σ η (1) , the xray diffraction pattern suggests that the electrolyte does not have a lattice of a cubic symmetry. Whereas initial specimens of the electrolyte, as well as the electrolyte of specimens that showed a tangible contribution made by σ η (2) , are cubic.…”

“…For example, the authors of [4] reported the results of long-term tests of an electrochemical cell with the LSGM20-17 electrolyte. 1 The tests were performed for 2500 h at a current density of 250 A cm -2 and a temperature of 800°ë . The properties of a cathodic half-cell (the cathode of La 0.6 Sr 0.4 CoO 3 -α ) remained invariant for 2500 h, which is the entire duration of experiment.…”