High performance La2NiO4+δ oxygen and Ni–Ce0.9Gd0.1O2−δ fuel electrodes for thin film reversible solid oxide cells

Abstract

Thin film reversible solid oxide cells (TF-rSOCs) are attracting a great deal of interest as they promise to operate at much lower temperatures (400–600 °C) than state-of-the-art commercial fuel electrode-supported cells (600–800 °C). However, in all-ceramics TF-rSOCs the high polarization resistance of the electrodes limits the cell performance. To overcome this limitation, high performing oxygen and fuel electrodes were selected and their nanostructure was optimized. Thin nanoporous films of La₂NiO_4+δ were deposited as oxygen electrode by Pulsed Injection Metal Organic Chemical Vapor Deposition (PI-MOCVD) with different thickness. As for the fuel electrode, thin films of Ni–Ce_0.9Gd_0.1O_2−δ (NiCGO) were deposited by Pulsed Laser Deposition (PLD) at various temperatures and pO₂. The electrochemical activity of the oxygen and fuel electrodes was measured by Electrical Conductivity Relaxation (ECR) and Electrochemical Impedance Spectroscopy (EIS), respectively. The optimized electrodes were then deposited on a YSZ single crystal electrolyte and the cell was measured in fuel cell and electrolysis modes showing high performance with a power density of 70 mW cm⁻² at 0.7 V and a current density of −44 mA cm⁻² at 1.3 V at a low operating temperature of 600 °C. These results demonstrate the potential of using these materials as electrodes in TF-rSOCs.