Preparation and characterization of one-dimensional nano-structured composite cathodes for solid oxide fuel cells

La0.8Sr0.2MnO3/Zr0.92Y0.08O2 (LSM/YSZ) composite nanotubes of different diameters were co-synthesized by a pore-wetting technique as cathode materials for solid oxide fuel cells. A fast firing method was introduced to improve the contact between the LSM/YSZ composite cathode and the YSZ electrolyte, and to retain the original nanotube structure. The influence of heating and cooling rates, as well as the diameter of the nanotubes, on the microstructure and further on the electrochemical performance of the LSM/YSZ composite cathodes were studied. The microstructure study indicated that the LSM/YSZ composite cathodes, which underwent a 1100 °C heat treatment, exhibited nanotube and nanorod structures using heating and cooling rates of 200 and 100 °C min−1. Area-specific resistance (ASR) of composite cathodes was characterized by electrochemical impedance spectroscopy. The nanotube-structured cathodes prepared using the heating and cooling rates of 200 °C min−1 exhibited lower ASR than the nanorod-structured cathodes. For the nanotube structured LSM/YSZ composite cathodes of different diameters, the cathode prepared using the 400 nm template exhibited the lowest ASR. At 700 °C, 750 °C, and 800 °C, the ASRs were 0.55, 0.40, and 0.26 Ω cm2, respectively. The low ASR was mainly due to the small grain size, homogeneous particle distribution, and fine pore structure of the material.