Redox-Stable High-Performance Thin-Film Solid Oxide Fuel Cell

Abstract

In this work, a mechanically redox-stable SOFC with a 1 µm thin-film sol-gel electrolyte is presented. With this electrolyte a power output larger than 1.25 W/cm2 at 0.7 V and an operating temperature of 600 °C could be demonstrated. Half cells were re-oxidized in excess air, in order to test the redox stability of these SOFCs. No cracks were found in the sol-gel electrolyte after re-oxidation for 4 hours at 600 °C and 30 minutes at 800 °C, respectively. Due to the fact, that the energy release rate is proportional to the thickness of the thin-film, a thinner film is more stable against cracking than a thicker film at constant tensile stresses. The SOFC with the thin-film sol-gel electrolyte can be considered as stable against re-oxidation, because the long re-oxidation time of 4 hours at an operating temperature of 600 °C is unlikely to happen under real conditions.