An Analytical Approximation for the Ionomer Film Model in PEMFC

The ionomer film and its transport resistances for oxygen are considered to be an important aspect for PEMFC performance. Ionomer film sub-models are therefore frequently used in PEMFC modeling to account for this effect. Mathematically these are expressed by a non-linear equation for the oxygen concentration, which depending on the reaction order cannot be solved analytically. Typically, a numerical solution of this equation, e.g., using the Newton-method is needed. Here, we derive highly accurate approximate analytical solution for the ionomer film model. This enables faster computation, which is particularly important for computationally demanding higher dimensional PEMFC models.