Large gas permeability nickel/alumina substrates with hierarchical pore structure for solid oxide fuel cells derived from particle-stabilized emulsions

A new design of high-porosity substrates with large gas permeability for segmented-in-series solid oxide fuel cells (SIS-SOFCs) is presented in this paper. The use of particle-stabilized emulsions provides high mechanical strength struts and hierarchical pore structures in the substrates. Ni-Al2O3 composites with Ni content of 0-30 vol. % are prepared, and their microstructures, flexural strengths, permeability, bending behavior and thermal expansions are investigated. The results show that porous and crack-free substrates are successfully obtained after sintering at 1450 °C for 5 h. Porosities of the substrates range from 75 to 85 % for an initial oil/water volume ratio in the suspension of 1:1. The flexural strength of the samples investigated are ranging from 7.5 to 9.8 MPa. The resulting porous substrates (30 vol% Ni) exhibit a suitable thermal expansion coefficient for use with a Ni-8YSZ anode and good bending behavior during sintering. Most importantly, these substrates have a very large gas permeability of 1.51 × 10−3 [m2].