Discussion on a Percolating Conducting Network of a Composite Thin-Film Electrode (≤1 μm) for Micro-Solid Oxide Fuel Cell Application

Ni/Gd_0.1Ce_0.9O_2−δ (Ni/GDC) and La_0.6Sr_0.4Fe_0.8Co_0.2O_3−δ/Gd_0.1Ce_0.9O_2−δ (LSCF/GDC) porous thin-film electrodes with thicknesses between 120 and 500 nm were synthesized through templated sol–gel chemistry coupled with the dip-coating process and heat treatment. The thin films consist of two interpenetrated networks made of pores and inorganic materials. The porous structure was composed of multi-scale pores with dimensions ranging from macro- to nanosize and with an oriented columnar structure. The dimension of the percolation network is discussed as a function of the chemical nature of the percolating components and the particle/thickness ratio. A three-dimensional percolation network is achieved in the LSCF/GDC composite, while a two-dimensional percolation network is observed for the Ni/GDC composite. This difference is related to the microstructure of the composite thin film. An anisotropic columnar structure is observed for Ni/GDC, while an isotropic structure is achieved for LSCF/GDC