Optimization on the electrochemical properties of La_2NiO_(4+δ) cathodes by tuning the cathode thickness

摘要

The electrochemical properties of La2NiO4+delta electrodes were investigated as a function of the electrode thickness based on three-electrode half cells. The electrocatalytic activity of the electrodes with the varied thicknesses ranging from 5 to 30 mu m was surveyed by electrochemical impedance spectroscopy technique under open-current voltage conditions. The cathodic polarization curves of these electrodes were also inspected. The results indicated that the electrochemical properties of these electrodes were highly dependent on their thickness. The polarizations of involved electrode reaction processes displayed different variations with changing the electrode thickness. Tuning the electrode thickness was confirmed to be effective for optimizing the electrochemical properties. Among the investigated electrodes, the electrode with a thickness of similar to 20 mu m achieved the optimal properties. At 800 degrees C in air, this electrode exhibited a polarization resistance of 0.24 Omega cm(2), an exchange current density of 201 mA cm(-2) and an overpotential of 40 mV at 200 mA cm(-2). On this ground, an anode-supported single cell with similar to 20 mu m thick La2NiO4+delta cathode was fabricated. At 800 degrees C and using hydrogen fuel, this single cell attained a maximum powder density of 500 mW cm(-2). (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.