Influence of Anode Functional Layers on Electrochemical Performance and Mechanical Strength in Microtubular Solid Oxide Fuel Cells Fabricated by Gel-Casting

Abstract

Anode-supported micro-tubular solid oxide fuel cells (mT-SOFCs) using samaria-doped ceria (SDC) as electrolyte were fabricated, varying the composition and number of anode functional layers (AFLs), by combining the aqueous gel-casting and spraycoating techniques. Suitable aqueous slurry formulation of NiO-SDC was prepared using agarose as a gelling agent for gel-casting of tubular supports. Afterwards, 40:60 and 50:50 wt.% NiO-SDC as AFLs and SDC electrolyte were deposited by spraycoating, and subsequently co-sintered. Finally, mT-SOFCs with 2.5 mm outer diameter and thicknesses of 380 µm support; 0, 12 and 24 µm AFLs; 15 µm electrolyte; and 30 µm cathode were obtained. The influence of AFLs on the performance and mechanical integrity was investigated for the three cells. For this purpose, electrochemical and mechanical tests at both macroscopic and micro-/nanometric scales (at the AFLs region) were determined by flexural strength and nanoindentation techniques, respectively. The results evidence that the use of AFLs with an adequate composition and microstructure in the mT-SOFCs is required to improve the performance and mechanical strength of cell. The cell with a single-layer AFL of 50:50 wt.% NiO-SDC and 12 µm thickness exhibited the best performance (0.52 Wcm-2) at 650ºC using hydrogen as fuel and air as oxidant.

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

“…Traditionally, 40-50 vol.% Ni is used in the functional layer and in the support for a Ni-YSZ electrode. The thickness and grain sizes of both YSZ and Ni as well as the Ni/YSZ ratio also play a crucial role on the mechanical strength of the cell [35]. Increasing the content of Ni or YSZ leads to an increase in electronic conductivity or ionic conductivity of the electrode, respectively.…”

Modulating the active phase in perovskite LaCoO3 with B-site doping of Cu for efficient methanol reforming to produce hydrogen

“…Methanol serves as an optimal carrier for chemical hydrogen storage due to its high hydrogen storage density, H/C ratio and mild hydrogen conversion conditions. 1 Hydrogen production through methanol steam reforming (MSR) is a promising strategy to solve the future energy challenges. Catalysts play a critical role in methanol steam reforming (MSR) by accelerating reaction rates and enhancing hydrogen output.…”

Microextrusion Printing of Multilayer Hierarchically Organized Planar Nanostructures Based on NiO, (CeO2)0.8(Sm2O3)0.2 and La0.6Sr0.4Co0.2Fe0.8O3−δ

“…It has been reported in a number of works that a cathode containing 50 wt% La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ and 50 wt% (CeO 2 ) 0.8 (Sm 2 O 3 ) 0.2 is characterized by restraining electrode grain growth and the formation of a microstructure that facilitates diffusion and surface exchange, as well as a lower total polarization resistance in comparison with similar cathodes [ 19 , 20 ]. According to the literature [ 21 , 22 ], the ratio of 50 wt% NiO to 50 wt% (CeO 2 ) 0.8 (Sm 2 O 3 ) 0.2 is one of the classic variants for anode or anode functional layer formation since this material can have a more developed triple-phase boundary surface (the area where NiO, SDC and hydrogen phases contact), which has a positive effect on HOR efficiency. In addition, this composition demonstrates sufficiently low resistance values and long-term stability.…”