Speaker
Description
Mixed conducting Ruddlesden-Popper (RP) type oxides are promising materials for application as air electrode materials for solid oxide fuel cells (SOFCs) and solid oxide electrolyser cells (SOECs). Within the rare earth RP series Lnn+1BnO3n+1, first order (n=1) RP type nickelates with Ln=La, Nd, Pr and B=Ni show high oxygen diffusivities, high catalytic activity for the oxygen reduction reaction as well as good electronic and ionic conductivities.
In this work, structure-composition-property–relationships were examined for the Pr2NiO4+δ system. The effect of A-site substitution of Pr with La as well as B-site substitution of Ni with Cobalt was investigated with respect to crystal structure, thermodynamic stability, oxygen non-stoichiometry, electronic conductivity as well as oxygen surface exchange and transport properties. In cases where material characterisation was problematic due to difficulties in obtaining densely sintered samples with high phase purity, electrochemical impedance spectroscopy (EIS) measurements on microelectrodes were applied in order to obtain reliable results for oxygen surface exchange rates. Substitution of Ni by 10% of Co in Pr2NiO4+δ results in increased oxygen surface exchange rates especially at lower oxygen partial pressures. Pr2Ni0.9Co0.1O4+δ could successfully be applied as SOEC air electrode on anode supported full cells for water electrolysis at 800°C, allowing current densities up to 900 mA/cm2. Moreover, the resistance of Pr2NiO4+δ and La2NiO4+δ against Cr-poisoning was examined by electrochemical impedance spectroscopy and current-voltage measurements on symmetrical cells at 800°C in dry and humid atmospheres, showing that both electrodes are stronger effected by chromium in the SOFC mode and that especially Pr2NiO4+δ exhibits increased resilience against Cr-poisoning in the SOEC mode [1].
References
[1] N. Schrödl, A. Egger, J. Lammer, F. Hofer, W. Sitte, J. Electrochem. Soc., 2021, 168, 014509.
| Speaker Country | Austria |
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