Validation of a pseudo 2D analytical model for high temperature PEM fuel cell impedance valid at typical operative conditions

Abstract

High temperature polymer electrolyte membrane fuel cells (HT-PEMFC) are a promising technology for carbon-free, combined heat and power generation. Analytical impedance models have the potential to support the creation of effective control logics with short response time. In this work an exact pseudo 2D model for HT-PEMFC impedance is developed, in which the anode has been neglected. The model considers losses due to kinetics and oxygen transport across the gas diffusion layer. Moreover, the cathode catalyst layer is assumed totally flooded and an additional oxygen transport loss is attributed to diffusion inside spherical agglomerates with a simplified approach. The model is tested against experiments on HT-PEMFC at different cathode stoichiometries, oxygen molar concentrations, and current densities. A simple fitting procedure is described to use the model. Moreover, sensitivity analysis is performed to assess the contribution of the physical phenomena to impedance spectra. Finally, the effect of the channel at different stoichiometries is discussed and a zero-frequency resistance is derived.