Reactivity at the Ln_2NiO_(4+δ)/electrolyte interface (Ln = La, Nd) studied by Electrochemical Impedance Spectroscopy and Transmission Electron Microscopy

摘要

Chemical reactivity between Ln_2NiO_(4+δ) (Ln: La, Nd) electrodes and Y_(0.08)Zr_(0.92)O_(1.96) (YSZ) and Ce_(0.9)Gd_(0.1)O_(1.95) (CGO) electrolytes was analyzed by Electrochemical Impedance Spectroscopy (EIS) and Focused Ion Beam-Transmission Electron Microscopy (FIB-TEM) techniques. L_2NiO_(4+δ) electrodes were deposited onto CGO and YSZ electrolytes by aerography and treated at 900 ℃ during 1 h in order to promote electrode adhesion. EIS spectra were collected between 500 and 800 ℃ in dry air. The Polarization Resistances (PR) values for La_2NiO_4/CGO/La_2NiO_4 cell are higher than those of La_2NiO_4/YSZ/La_2NiO_4. The PR for both cells and its evolution in time suggest that chemical reactivity is developed at 900 ℃ during the adhesion treatment and at T higher than 650 ℃ during the EIS measurements. The PR for Nd_2NiO_4/CGO/Nd_2NiO_4 and Nd_2NiO_4/YSZ/Nd_2NiO_4 are much lower than those of La_2NiO_4/CGO/La_2NiO_4 and La_2NiO_4/YSZ/La_2NiO_4 cells. These values and the slight increase of PR with time for Nd_2NiO_4 (NNO) electrodes indicate that the strength of chemical reactivity is much lower than that of La_2NiO_4 (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.