Fabrication of micro-tubular solid oxide fuel cells using sulfur-free polymer binder via a phase inversion method

• Novel sulfur-free polymer binder was applied for PC-SOFC fabrication.
• Effect of polymer binder on anode substrate was systematically investigated.
• Influence of sulfide impurity on cell performance was analyzed.
• Power density of 0.45 Wcm−2 was achieved at 650 °C using PEI as polymer binder.

Three sulfur-free polymer binders (ethyl cellulose (EC), polyvinylidene fluoride (PVDF), polyetherimide (PEI)) and sulfur-containing polyethersulfone (PESf) polymer binder were used to fabricate NiO–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) anode substrates. The overall influence of polymer binder on the anode supports was evaluated. Sulfide impurity in the anode substrate was identified when sulfur-containing PESf was used as the polymer binder. Single cells based on different anode supports were characterized in anode-supported MT-SOFCs with the cell configuration of Ni-BZCYYb anode, BZCYYb proton-conducting electrolyte and La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF)-BZCYYb cathode at 650 °C, 600 °C and 550 °C, using humidified hydrogen as fuel and ambient air as oxidant. MT-SOFCs of the anode fabricated using PEI show maximum power density of 0.45 Wcm−2, 0.34 Wcm−2 and 0.23 Wcm−2 at 650 °C, 600 °C and 550 °C respectively, compared with 0.35 Wcm−2, 0.27 Wcm−2 and 0.18 Wcm−2 for cells fabricated with PESf. The difference in cell performance was attributed to the phase purity of the anode fabricated by different polymer binders. Sulfur-free polymer binder PEI exhibits advantages over the commonly applied PESf and other sulfur-free polymer binders, pointing to a new direction in the fabrication of micro-tubular oxide substrates for energy conversion and storage.