Effect of anode configuration on electrical properties and cell polarization in planar anode supported SOFC

A detailed investigation is carried out to correlate configurational variation of SOFC anode with electrical characterizations. For this purpose, Ni-YSZ cermet anode (28-32 vol.% Ni) having a novel core-shell microstructure (prepared by electroless technique) has been used in conjunction with conventional cermet (40 vol.% Ni). Depending upon the thickness, electroless cermet is used in two configurations, viz. (i) as layered anode and (ii) as anode active layers (AAL). Thicknesses of electroless layer are varied sequentially for both these configurations for inducing functionality in the cermet. Layered anode with 140 μm electroless layer (32 vol.% Ni) shows maximum electrical conductivity (644 Scm^{- 1}) with only 7% degradation after 20 redox cycles at 800 C. A theoretical approach is attempted to explain the overall cell polarization behavior and to quantify the polarization components. Single cells fabricated with electroless AAL show lowest polarization (~ 0.3 Ω.cm²) with minimum contribution of charge transfer and concentration polarization. As a result, single cell having such a thin (~ 15 μm) AAL, exhibits the highest electrochemical performance (~ 3.7 A.cm^{- 2}) with significant low degradation rate (2.8% 1000 h ^{- 1}) at 800 C, 0.7 V.