Electrochemical performance of Ln2NiO4+δ (Ln - La, Nd, Pr) And Sr2Fe1.5Mo0.5O6-δ oxide electrodes in contact with apatite-type La10(SiO6)4O3 electrolyte

The row of oxide cathode materials with Ruddlesden-Popper structure and Sr2Fe1.5Mo0.5O6-delta anode material were investigated as promising electrodes for La-10(SiO4)(6)O-3 electrolyte with apatite-type structure. XRD analysis confirmed their chemical compatibility with the electrolyte. It was observed that the cathode electrochemical activity increased in the row Pr2NiO4+delta-Nd1.9NiO4+delta-La2NiO4+delta. The lowest value of polarization resistance was obtained for the double-layer cathode La2NiO4+delta-LaFe0.6Ni0.4O3-delta and was about 0.3 Omega.cm(2) at 800 degrees C. It was established that three relaxation processes determined the overall cathode polarization resistance. The oxygen diffusion in the gas phase as the low-frequency process was proposed. The satisfactory activity of Sr2Fe1.5Mo0.5O6-delta anode in H-2 + H2O and H2O + CH4 (1:1 vol%) gas mixtures at 800 degrees C was detected about 0.4 Omega.cm(2). The oxygen transport in Sr2Fe1.5Mo0.5O6-delta anode and surface dissociation of hydrogen were suggested as the rate-determining stages of hydrogen oxidation on the Sr2Fe1.5Mo0.5O6-delta anode.