The present study concerns the influence of the micro/nano-structural properties of LSCF (La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ) and 60:40 vol.% LSCF/CGO (Ce_0.9Gd_0.1O_2-δ) composite cathode films on their electrochemical behavior. Electrostatic spray deposition technique is used to deposit 10 μm-thick functional films (Fig. 1). Contrary to expectations, pure LSCF showed a better response compared to the composite material. It exhibits Area Specific Resistance (ASR) values as low as 0.021 and 0.068 Ω.cm² at 650 ˚C and 600 ˚C respectively. These values are, to the best of our knowledge, one of the lowest reported to date for LSCF-6428 composition in open circuit voltage (OCV) condition.¹ To better comprehend the complex relationships between material properties, processing, micro/nano structure and electrode performance, a simplified geometry representing the typical 10x10x10 μm³ porous columns of the electrodes is modelled by 3D finite element (FEM).² ASR is computed with real microstructural parameters obtained from 3D FIB/SEM technique. On the other hand, it is also calculated by a simple volume-averaged analytical model (1D-ALS model)³ within an assumed macrohomogeneous geometry. The computed ASRs with these two relatively simple models are compared to experimental results and the relevance of such models for inhomogeneous microstructures like ‘columnar’ is discussed.

Figure 1: Microstructural characterization of the films a-c) LSCF, e-g)  60/40 vol.% LSCF/CGO composite films observed by SEM. 3D reconstructed images by FIB/SEM technique of  (d) LSCF and (h) 60:40 LSCF/CGO composite.

1. Celikbilek, O., Jauffres, D., Dessemond, L., Burriel, M., Martin, C.L., Djurado, E.,(2015), to be submitted to J. Mat. Chem. A
2. Haffelin, A., Joos, J., Ender, M., Weber, A., Ivers-Tiffee, E. (2013). J. Electrochem. Soc. 160, F867–F876
3.  Adler, S. B., Lane, J. A. & Steele, B. C. H. (1996). J. Electrochem. Soc. 143, 3554–3564