Ceria doped with praseodymium instead of gadolinium as efficient interlayer for lanthanum nickelate SOFC oxygen electrode

- The praseodymium doped ceria is shown to be an efficient interlayer for SOFC cathodes.
- Interphases formed at high temperatures are beneficial for the oxide transfer.
- Using praseodymium doped ceria makes the series resistance of the cell minimized.
- The polarization resistance of the lanthanum nickelate is much decreased as well.

In the solid oxide fuel cell field, the gadolinium doped ceria (GDC) is widely used as interlayer between oxygen electrode and electrolyte materials, as for instance La2NiO4+δ (LNO) and 3 mol.% Y2O3-ZrO2 (TZ3Y), respectively. However, cation interdiffusion occurs between GDC and LNO/TZ3Y during their sintering steps at high temperature, which finally lowers the electrochemical performance of the cathode for the oxygen reduction reaction (ORR). In this paper, an alternative interlayer is proposed, the praseodymium doped ceria (PrDC with 30 at.% Pr). It is shown that reactivity occurs between PrDC and TZ3Y, but the compounds formed seem to favour the ORR. Besides, little reactivity is detected between LNO and PrDC. As a result, the total resistances, i.e. series and polarization resistance obtained with a LNO//PrDC//TZ3Y half-cell from 500 °C to 800 °C are much lower than those obtained with a LNO//GDC//TZ3Y half-cell, sintered in the same conditions. In addition, differences in the shape of the impedance diagrams are observed depending on the interlayer: this feature is discussed throughout the paper.