Optimization of Ni–YSZ solid oxide fuel cell anodes by surface laser melting

Abstract

a b s t r a c tA cermet composed of a metallic component (nickel) and a ceramic matrix (yttria stabilized zirconia) is commonly used as the anode for solid oxide fuel cells (SOFC). In the present work we intend to improve the performance of Ni-YSZ anodes by surface laser melting. Symmetrical cells, consisting of two NiO-YSZ anodes (∼20 m thickness) separated by a relatively thin YSZ electrolyte (∼500 m) were fabricated by convectional ceramic techniques. Subsequently, laser melting treatments of both anodes were performed using a CO 2 laser system, producing a NiO-YSZ eutectic lamellar microstructure. Laser power of 100 W and processing rates of 1 mm s −1 were determined as the optimum processing conditions. Symmetrical processed plates (eutectic sample) were electrically characterized by impedance spectroscopy (EIS), and the results were compared with non-processed plates (ceramic sample). Preliminary EIS results showed that the polarization resistance at higher temperatures (in the range of 900 • C) is about 0.5 cm 2 for both the eutectic and the ceramic sample. However, at lower temperatures (in the range of 800 • C) the polarization resistance for both samples differs considerably (2.9 and 1.6 cm 2 for the ceramic and eutectic sample, respectively). These experiments confirmed that optimization of the microstructure by laser surface treatment plays a crucial role in the electrochemical properties of the anode cermets.

Microstructure and long-term stability of Ni–YSZ anode supported fuel cells: a review

“…Similar eutectic compositions were later proposed as candidates for SOFC anodes by Merino et al [68]. In addition to a lower polarization resistance in comparison with conventional Ni-YSZ cermets [69], they also present superior ageing stability, as the low-energy interfaces formed between the metallic Ni particles and the YSZ prevent particle coarsening [70]. In fact, further studies using transmission electron microscopy (TEM) and x-ray pole figure experiments confirmed that during NiO reduction, nickel undergoes an interface-induced crystallographic reorientation to form a lower energy interface, and as a consequence more stable Ni is formed [71].…”

Temperature‐controlled microextrusion printing for mesoscale interfacial designing in solid oxide fuel cells

“…However, it was reported that the grooved structures fabricated by the subtractive techniques are difficult to control precisely. Also, the cell components are prone to damage during mechanical processing [12,15,16]. Alternatively, a microextrusion-printing-based additive manufacturing technique is appreciated because of less material waste, free contact with printed objects, and the capability to fabricate precise structures [17].…”

Bulk nanocomposite made of ZnO lamellae embedded in the ZnWO4 matrix: growth from the melt

“…Recently, directional solidification of eutectics was utilized for energy materials such as solid-oxide fuel cells [11,12] and electrodes for hydrogen generation [13,14], and optical materials such as photonic crystals [15,16]; THz polaritonic materials [17,18]; metamaterials [19][20][21][22][23] and nanoplasmonic materials [24][25][26]. It has been also shown that eutectic composites could exhibit unusual geometries when properly engineered [27][28][29], in addition to being grown as bulk materials [30] even on the industrial scale and also printed [31].…”