Reactivity at the Ln2NiO4+δ/electrolyte interface (Ln = La, Nd) studied by Electrochemical Impedance Spectroscopy and Transmission Electron Microscopy

Chemical reactivity between Ln2NiO4+δ (Ln: La, Nd) electrodes and Y0.08Zr0.92O1.96 (YSZ) and Ce0.9Gd0.1O1.95 (CGO) electrolytes was analyzed by Electrochemical Impedance Spectroscopy (EIS) and Focused Ion Beam-Transmission Electron Microscopy (FIB-TEM) techniques. Ln2NiO4+δ electrodes were deposited onto CGO and YSZ electrolytes by aerography and treated at 900 °C during 1 h in order to promote electrode adhesion. EIS spectra were collected between 500 and 800 °C in dry air. The Polarization Resistances (PR) values for La2NiO4/CGO/La2NiO4 cell are higher than those of La2NiO4/YSZ/La2NiO4. The PR for both cells and its evolution in time suggest that chemical reactivity is developed at 900 °C during the adhesion treatment and at T higher than 650 °C during the EIS measurements. The PR for Nd2NiO4/CGO/Nd2NiO4 and Nd2NiO4/YSZ/Nd2NiO4 are much lower than those of La2NiO4/CGO/La2NiO4 and La2NiO4/YSZ/La2NiO4 cells. These values and the slight increase of PR with time for Nd2NiO4 (NNO) electrodes indicate that the strength of chemical reactivity is much lower than that of La2NiO4 (LNO). TEM results confirmed that reactivity between CGO and LNO is much higher than that of YSZ and LNO and also confirm that the strength of reactivity is appreciably lower for NNO as electrode material.