PEMFCs multiscale modeling: Determination of overpotential with description of electron transfer in cathodic EDL at different O-2 concentrations

摘要

The effect of the formation of the electrical double layer (EDL) as a function of O-2 concentrations in Pt/H2O interface in a proton-exchange membrane fuel cell (PEMFC) is analyzed in this work. The over-potential associated with the existence of the EDL is calculated at typical fuel cell O-2 concentrations by using molecular dynamics (MD). The calculated overpotentials are in the range of -8.865 x 10(-6) e 0:0086 V for oxygen molar fractions in the cathode between 0 and 0:1273. These overpotential values are included in the ORR kinetic equations of a multiscale model for PEMFCs developed in a previous work to estimate the global electroosmotic drag coefficient and compare it with experimental data from literature. It was found an improvement of the accuracy of the model, at air fed hydration levels of 50% and 70% in the cathode, if the overpotential calculation is carried out considering the electron transfer in the entire interface, not only in the outer Helmholtz plane (OHP) thus, modifying the Frumkin effect calculation. (c) 2019 Elsevier Ltd. All rights reserved.