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

Abstract The row of oxide cathode materials with Ruddlesden-Popper structure and Sr 2 Fe 1.5 Mo 0.5 O 6−δ anode material were investigated as promising electrodes for La 10 (SiO 4 ) 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 Pr 2 NiO 4+δ -Nd 1.9 NiO 4+δ -La 2 NiO 4+δ . The lowest value of polarization resistance was obtained for the double-layer cathode La 2 NiO 4+δ -LaFe 0.6 Ni 0.4 O 3−δ and was about 0.3 Ω·cm 2 at 800 °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 Sr 2 Fe 1.5 Mo 0.5 O 6−δ anode in H 2  + H 2 O and H 2 O + CH 4 (1:1 vol%) gas mixtures at 800 °C was detected about 0.4 Ω·cm 2 . The oxygen transport in Sr 2 Fe 1.5 Mo 0.5 O 6−δ anode and surface dissociation of hydrogen were suggested as the rate-determining stages of hydrogen oxidation on the Sr 2 Fe 1.5 Mo 0.5 O 6−δ anode.