Parametrization of a 0D solid oxide cell performance model—a detailed investigation including temperature dependencies of kinetic parameters

The performance of a solid oxide cell (SOC) under given operating conditions is often predicted by using cell models that subtract the different voltage loss contributions from the theoretical Nernst voltage, also called open circuit voltage minus losses models. The determination of kinetic parameters for Butler–Volmer-type equations describing activation losses at fuel and air electrodes, respectively, is therefore originally conducted at a single operating temperature, resulting in temperature-independent values for these parameters. Yet, significant temperature gradients across both the cell area and the height of the stack occur in SOC applications; thus, a proper representation of the temperature dependency of all electrochemical parameters is required. We therefore examine possible temperature dependencies of the kinetic parameters and their impact on cell performance. To this end, the kinetic parameters are experimentally determined within the operating window of the investigated cell (600 °C–700 °C), showing nonnegligible temperature dependencies for all parameters of the Butler–Volmer-type equation. The impact of these temperature dependencies on cell performance is evaluated by comparing the error between measurements and simulations with and without temperature-dependent parameters. ... mehrAccounting for temperature-dependent parameters reduces the maximum cell voltage error between simulation and measurement. This reduction was from −5.4% to −5.1% in the electrolysis mode and from −9.7% to −7.9% in the fuel cell mode when the parametrization temperature matched the operating temperature (compared to a 100 K offset). Although the cell voltage improvement was moderate, a significant impact was observed on activation overpotentials, where neglecting temperature dependence led to deviations of up to 56% for the investigated cell.