Composition-dependent microstructural connectivity and mechanical stability of NiO–YSZ cermets in anode-supported solid oxide fuel cells

Microstructural optimization of NiO–YSZ cermet anodes is critical for achieving mechanically robust porous structures in anode-supported SOFCs. Here, a quantitative design framework is established by controlling NiO–YSZ composition and pore former content within a defect-free processing window. Pellets with NiO–YSZ ratios from 3:7 to 7:3 were analyzed using backscattered electron microscopy and image-based phase segmentation. The reduced Ni–YSZ–pore structure was strongly influenced by the initial composition due to volumetric contraction during NiO reduction. A 60:40 wt% ratio exhibited optimal phase connectivity, ensuring continuous Ni and YSZ networks with sufficient porosity. For the supporting layer, the effect of starch pore former content on pore architecture and compressive behavior was evaluated. Although higher pore former content increased porosity, excessive addition (≥15 wt%) caused internal cracking and instability. A 10 wt% pore former maintained structural integrity while providing uniform pores, offering practical guidelines for designing mechanically reliable NiO–YSZ anodes.