Electrochemical Study of La0.31Sr0.58Ti0.97Ni0.03O3-δ Thin Film and Pt-10Sc1CeSZ Electrodes

Abstract

La and Ni-doped Sr-titanates, LaxSr1-xTi1-yNiyO3- d, are considered to be promising solid oxide fuel cell anode materials with Ni exsolution possibilities [1]. In this work two different types of La0.31Sr0.58Ti0.97Ni0.03O3-δ (LSTN) thin film microelectrodes were studied. Electrodes with photolitographycally microstructured Pt current collectors under ceramic electrode layer [2] and microelectrodes without current collectors were made using pulsed laser deposition and measured using EIS at different temperatures around 650 ℃ in water-hydrogen atmosphere at reduced pressures (0.5, 1 and 1 mbar) and at 1 atm ambient pressure. Measurements were carried out using single chamber 2-electrode configuration where large area porous GDC-Pt electrode was used as counter electrode [3]. Main aim of this study was to collect additional information to understand electrochemical data collected during in situ NAP-XPS measurements of LSTN thin film electrode and also link the data collected at ambient pressure with data measured at pressures where NAP-XPS experiments are performed. The measurements showed differences between electrodes with Pt current collectors and microelectrodes without Pt current collectors. LSTN electrodes without Pt showed weak relationship between anodic overpotential and polarization resistance suggesting that overpotential acted mainly on LSTN defect chemistry while electrodes with Pt current collectors were activated more by anodic overpotential. Oxide ion transport resistance from electrolyte to thin film | gas phase surface seems to be the main contributor to the resistance of the electrodes. J. T. S. Irvine et al., Nature Energy, 1, 15014 (2016).A. Nenning, A. K. Opitz, T. M. Huber, and J. Fleig, Phys. Chem. Chem. Phys., 16, 22321–22336 (2014).A. Nenning and J. Fleig, Surface Science, 680, 43–51 (2019).