Characteristic Length of Oxide-Ion Conduction for Prediction of Active Thickness in SOFC Anode

Active thickness in SOFC anodes is investigated by using one-dimensional numerical simulation. The effects of the operating conditions and the microstructural parameters of the porous anodes on the active thickness are systematically investigated. The non-linearity of the Butler-Volmer equation used for the electrochemical reaction model is found to be the key to explain the behaviour of the active thickness. The characteristic length of oxide-ion conduction is introduced by taking the ratio between the oxide-ion conductivity and the electrochemical reaction rate, which can be used as a designing parameter to predict the active thickness.