Despite being the most employed polymer electrolyte for proton exchange membrane fuel cells (PEMFCs), Nafion^® has several limitations: expensiveness, poor performance when exposed to temperatures higher than 80 °C, and its potential as a source of environmentally persistent and toxic compounds (i.e., per- and polyfluoroalkyl substances, known as PFASs) when disposed of. This work explores the functional and environmental performances of three potential PFAS-free alternatives to Nafion^® as electrolytic membranes in PEMFCs: sulfonated graphene oxide (SGO), graphene oxide-naphthalene sulfonate (GONS), and borate-reinforced sulfonated graphene oxide (BSGO). Investigated via ATR-FTIR spectroscopy, TGA, and cross-sectional SEM, the membranes show an effective functionalization of GO and good thermal stability. Functional properties are determined via Ion Exchange Capacity (IEC) evaluation, Electrochemical Impedance Spectroscopy, and tensile tests. In terms of IEC, the innovative materials outperform Nafion^® 212. Proton conductivities at 80 °C of SGO (1.15 S cm⁻¹) and GONS (1.71 S cm⁻¹) are higher than that of the commercial electrolyte (0.56 S cm⁻¹). At the same time, the membranes are investigated via Life Cycle Assessment (LCA) to uncover potential environmental hotspots. Results show that energy consumption during manufacture is the main environmental concern for the three membranes. A sensitivity analysis demonstrates that the impact could be significantly reduced if the production procedures were scaled up. Among the three alternatives, SGO shows the best trade-off between proton conductivity and environmental impact, even though performance results from real-life applications are needed to determine the actual environmental consequences of replacing Nafion^® in PEMFCs.

This paper discusses the possibility to use the current ripple introduced by switch mode power converters for low-cost monitoring of polymer electrolyte membrane (PEM) fuel cell (FC) state-of-health, suitable for commercial applications that cannot afford dedicated instrumentation. In more details, an estimate of the ohmic resistance, which is a good indicator of the membrane water content, can be obtained from the high-frequency ripple response by data processing in the frequency domain, while lower frequency ripple at 100/120 Hz (when present) is in the typical frequency range of activation processes. All the available impedance estimates, together with the dc voltage measurement, can be used to promptly detect FC drying and flooding, that are the two opposite failure modes as far as water balance is concerned. The proposed diagnostic approach is tested on a single PEM FC in drying and flooding conditions, by emulating three-phase and single-phase inverter ripples by means of an electronic load.

In this paper, a low-cost approach for polymer electrolyte membrane fuel cell (FC) drying and flooding diagnosis based on power converter ripple is presented, suitable to be implemented in commercial applications. If proper signal processing algorithms are employed, the high-frequency ripple inherently produced by switch-mode converters allows one to monitor the FC ohmic resistance, which is a good indicator for membrane drying, while an ad hoc switching control of the converter allows one to monitor also the low-frequency impedance, which is an indicator for cell flooding. This technique is tested with a dc/dc boost converter directly connected to a single cell, discussing how different FC operation modes (such as constant current or constant voltage) may affect the sensitivity required to the diagnostic algorithm to correctly recognize drying and flooding occurrences.