Clarifying the Butler-Volmer equation and related approximations for calculating activation losses in solid oxide fuel cell models

This paper shows the importance of including the activation losses in a model designed to accurately predict the voltage-current relationship of a modern solid oxide fuel cell. The governing equation for voltage drop due to activation losses, the Butler-Volmer equation, is discussed and the derivation and applicability of several approximations is investigated. Finally, the assumptions required to combine the separate anode and cathode activation loss calculations into a single-term equation are clarified.