Cerium Oxide Decorated Polymer Nanofibers as Effective Membrane Reinforcement for Durable, High‐Performance Fuel Cells

Abstract

High‐power, durable composite fuel cell membranes are fabricated here by direct membrane deposition (DMD). Poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) nanofibers, decorated with CeO2 nanoparticles are directly electrospun onto gas diffusion electrodes. The nanofiber mesh is impregnated by inkjet‐printed Nafion ionomer dispersion. This results in 12 µm thin multicomponent composite membranes. The nanofibers provide membrane reinforcement, whereas the attached CeO2 nanoparticles promote improved chemical membrane durability due to their radical scavenging properties. In a 100 h accelerated stress test under hot and dry conditions, the reinforced DMD fuel cell shows a more than three times lower voltage decay rate (0.39 mV h−1) compared to a comparably thin Gore membrane (1.36 mV h−1). The maximum power density of the DMD fuel cell drops by 9%, compared to 54% measured for the reference. Impedance spectroscopy reveals that ionic and mass transport resistance of the DMD fuel cell are unaffected by the accelerated stress test. This is in contrast to the reference, where a 90% increase of the mass transport resistance is measured. Energy dispersive X‐ray spectroscopy reveals that no significant migration of cerium into the catalyst layers occurs during degradation. This proves that the PVDF‐HFP backbone provides strong anchoring of CeO2 in the membrane.

Rational Design of Ultrathin Gas Barrier Layer via Reconstruction of Hexagonal Boron Nitride Nanoflakes to Enhance the Chemical Stability of Proton Exchange Membrane Fuel Cells

“…The OCV holding test maximizes the gas crossover and accelerates the chemical deterioration of the key components due to the formation of a number of OH • radicals . To clearly observe the structural change of MEAs, any electrochemical test was not conducted during the OCV hold test . Instead, the polarization curves and EIS Nyquist plots of the MEAs were recorded after the ASTs, and the resulting characteristics change of the MEAs are summarized in Table 1 .…”

“…[1,39] To clearly observe the structural change of MEAs, any electrochemical test was not conducted during the OCV hold test. [13] Instead, the polarization curves and EIS Nyquist plots of the MEAs were recorded after the ASTs, and the resulting characteristics change of the MEAs are summarized in Table 1.…”

“…Recently, transition metal oxides have been inserted in the PFSA membrane or the catalyst layer since the transition metal ions are able to scavenge the radicals by donating or accepting electrons via switching their oxidation states. [9][10][11][12][13][14][15] However, the radical-scavenging effects by transition metal oxides are rapidly mitigated during the PEMFC operation because of low chemical stability of the metal oxide in acidic condition. [16][17][18] As a direct approach to reduce the gas crossover and thus to prevent chemical degradation of the MEA, additional gas barrier layers can be introduced between the polymer membrane and the catalyst layer.…”

Effect of Pretreatment on Microstructure and Mechanical Properties of Nafion™ XL Composite Membrane

“…While remarkable changes in microstructure are observed in this study, pretreating membranes by heating them in 70 °C water does not result in much changes in microstructure . As the reinforced membranes are normally tested at 80 °C, no significant decay in durability is reported , . With increasing demand to work at elevated temperature or low relative humidity, composite membranes with short‐side‐chain (SSC) PFSA ionomer were found to have great potential to meet such requirement .…”

Improving the water management in anion-exchange membrane fuel cells via ultra-thin, directly deposited solid polymer electrolyte

“…To determine the electrical resistance of the AEMFCs, the respective GDLs without MEAs were placed in the fuel cell xture in order to determine the ionic component in the resistance measurements of the cell. 20 Then the cell potential was gradually swept, in steps of 1 mV from 0 V to 20 mV. The slope of the resulting I-V curve represents the electrical resistance of the fuel cell, which was determined to be 25.2 mOhm cm.…”