Anode-supported microtubular cells fabricated with gadolinia-doped ceria nanopowders

Anode-supported microtubular SOFCs based on ceria 3 ± 0.2 mm diameter and about 100 mm in length have been prepared using gadolinia-doped ceria (GDC) nanopowders. Nanometric Ce0.9Gd0.1O1.95 (GDC) powders were deposited on NiO–Ce0.9Gd0.1O1.95 (NiO–GDC) anode supports by dip-coating technique. Fabrication conditions to obtain dense and gas tight electrolyte layers on porous microtubular supports were studied. Three different dispersing agents: commercial Beycostat C213 (CECA, France) and short chain monomer (≤4 carbon atoms) with alcohol or carboxylic acid functional groups were evaluated. By optimizing colloidal dispersion parameters and sintering process, gas tight and dense GDC layers were obtained. Significantly lower sintering temperatures than reported previously (≤1300 °C) were employed to reach ≥98% values of theoretical density within electrolyte layers of ∼10 μm in thickness. A composite cathode, LSCF–GDC 50 wt.% with about 50 μm thickness was dip coated on the co-fired half-cell and then sintered at 1050 °C for 1 h. The electrochemical performance of these cells has been tested. In spite of electronic conduction due to partial reduction of the thin-electrolyte layer, the I–V measurements show power densities of 66 mW cm−2 at 0.45 V at temperatures as low as 450 °C (using 100% H2 as fuel in the anodic compartment and air in the cathodic chamber).