Performance Improvement of $(La,Sr)MnO3$ and $(La,Sr)(Co,Fe)O3$-Type Anode-Supported SOFCs

Targets in the development of anode-supported or planar solid oxide fuel cells (SOFCs) are low operation temperatures, high durability, high reliability, high power density, and low production costs. During the past ten years steps have already been taken at Forschungszentrum Jülich to lower the operating temperatures while maintaining the power output. This was achieved by optimizing processing and microstructural parameters of the electrodes. This paper presents the latest results concerning performance improvement through variations of the processing route and the microstructure of $La0.65Sr0.3MnO3$ (LSM) and $La0.58Sr0.4Co0.2Fe0.8O3−δ$ (LSCF)-type SOFCs. In the case of the LSM-type single cells, the following aspects relating to the electrochemical performance were investigated in more detail: (1) production of the anode substrate by tape casting versus warm pressing; (2) deposition of the anode functional layer (AFL) and electrolyte by screen printing versus vacuum slip casting; (3) use of noncalcined and non-ground YSZ for applying the cathode functional layer (CFL); and (4) sintering temperature of the CFL and cathode current collector layer (CCCL). In the case of LSCF-type cells, a systematic approach was initiated for optimizing the $Ce0.8Gd0.2O2−δ$ (CGO) diffusion barrier layer: (1) deposition techniques of the CGO layer and (2) sintering temperature of the screen-printed CGO layer. Results have shown that certain modifications of the processing route led to a slightly lower electrochemical performance, whereas others did not affect the performance at all. Regarding LSCF-type SOFCs, a slight improvement of the performance was achieved by optimizing the sintering temperature of the CGO layer.