Abstract
Anode‐supported solid oxide fuel cells with yttria‐stabilized zirconia (YSZ) electrolyte, Sr‐doped 
(LSM) + YSZ cathode, and Ni + YSZ anode were fabricated and their performance was evaluated between 650 and 800°C with humidified hydrogen as the fuel and air as the oxidant. Maximum power densities measured were 
at 800°C and 
at 650°C. Voltage (V) vs. current density (i) traces were nonlinear; V vs. i exhibited a concave‐up curvature 
at low values of i and a convex‐up curvature 
at higher values of i, typical of many low temperature fuel cells. Analysis of concentration polarization based on transport of gaseous species through porous electrodes, in part, is used to explain nonlinear V vs. i traces. The effects of activation polarization in the Tafel limit are also included. It is shown that in anode‐supported cells, the initial concave‐up curvature can be due either to activation or concentration polarization, or both. By contrast, in cathode‐supported cells, the initial concave‐up curvature is entirely due to activation polarization. From the experimentally observed V vs. i traces for anode‐supported cells, effective binary diffusivity of gaseous species on the anodic side was estimated to be between 
at 650°C and 
at 800°C. The area specific resistance of the cell (ohmic part), varied between 
at 650°C and 
at 800°C with an activation energy of ∼65 kJ/mol. © 1999 The Electrochemical Society. All rights reserved.