Electrochemical impedance spectroscopy and electric equivalent circuit modeling for open-cathode PEM fuel cell performance: A review

Abstract

This review synthesizes recent research on the performance prediction of open-cathode polymer electrolyte membrane fuel cells (PEMFCs) using electrochemical impedance spectroscopy (EIS) and electrical equivalent circuit (EEC) modeling. Open-cathode PEMFCs offer advantages such as reduced system mass and simplified air management, making them attractive for lightweight applications, but their direct exposure to ambient conditions complicates performance prediction. EIS is a widely used technique to characterize electrochemical systems. When impedance spectra obtained from EIS are fitted to EEC models, these models enable the quantitative interpretation of the underlying phenomena. However, an analysis of the existing EEC topologies reveals that there is no consensus on a universal model. Most topologies rely on phenomenological interpretations rather than physics-based formulations of PEMFCs and are often tailored to specific applications. Furthermore, EECs have rarely been applied to describe performance under the dynamic conditions typically experienced by open-cathode systems. This review also examines different emerging EIS-based measurement techniques, including instantaneous impedance spectra, nonlinear EIS, and distribution of relaxation times (DRT), which aim to increase the information extracted from measurements. Despite extensive work on closed-cathode systems, literature addressing the performance of open-cathode PEMFCs under realistic environmental conditions remains limited, revealing a significant gap in modeling. © 2026 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.