Impedance based performance model for polymer electrolyte membrane fuel cells

In the development of fuel cells, electrochemical models, describing the losses in the cell, are required for simulations on electrode to system level. Models considering the physicochemical background of the loss processes in the cell enable not only a gross performance prediction but also provide information about internal states, which is required in cell or stack development, evaluation of operating strategies and system control. The parameterization of such models is challenging as a larger number of parameters has to be determined for the considered cell. In this work an impedance-based approach, successfully applied for Solid Oxide Cells, is transferred to Polymer Electrolyte Membrane Fuel Cells. Impedance spectra are measured over a wide range of operating conditions and subsequently analyzed by their distribution of relaxation times (DRT) to establish a physicochemically meaningful equivalent circuit model. Parameters from this model are transferred to a nonlinear 0-dimensional cell performance model that simulates the different loss contributions and calculates CV-characteristics for arbitrary operating conditions by an OCV minus losses approach. The straightforward application of the SOC-modeling approach to PEMFC revealed a number of hurdles successfully resolved in this paper. Validation with experimental data showed a good agreement over a wide range of operating conditions.