Sintering Behavior of (La,Sr)MnO3 Type Cathodes for Planar Anode-Supported SOFCs

Abstract

One of the main targets in the development of anode-supported solid oxide fuel cell (SOFCs) is to improve the electrochemical performance. This can be achieved by optimizing processing and microstructural parameters of the SOFCs. Variations of the thickness of the cathode functional layer and the cathode current collector layer, the grain size of the powders used for applying these layers, and the sintering temperature, can influence the electrochemical performance as such that lower operation temperatures become possible without detrimentally affecting the power output to a great extent. In this study the effect of variations of the sintering temperature of the cathode on (1) the microstructure, (2) the gas diffusivity and permeability in the cathode, and (3) electrochemical performance of FZJ-type anode-supported single cells, was investigated. The FZ-Jülich cell design is based on anode-supported type cells, which are characterized by a relatively thick anode (thickness: 1.0-1.5mm) consisting of a NiO/8YSZ cermet, a thin 8YSZ electrolyte, and a bi-layered cathode. The cathode distinguished two separated layers: first a cathode functional layer consisting of La0.65Sr0.3MnO3(LSM)∕Y2O3-stabilized ZrO2 (8YSZ) and a cathode current collector layer of pure La0.65Sr0.3MnO3 (LSM). This study can be considered as a follow-up of that (Journal of Power Sources 141 (2005) 216–226) describing the improvement of the cell performance by a systematic variation of the microstructure. The experiments described in this paper and the corresponding results are part of a more extensive study to investigate in more detail the effect of the sintering temperature on the electrochemical performance of LSM-type SOFCs. Since research is still going on, conclusions, drawn in this contribution, are yet not definitive.