Biased Expanded Polytetrafluoroethylene Reinforced Composite Membranes with Naturally Formed 3D Surface Structures for High-Performance Proton Exchange Membrane Fuel Cells

Abstract

As a crucial factor dictating the power performance of proton exchange membrane fuel cells, the interface combination between the proton exchange membrane and the catalyst layer should be considered seriously. Herein, we propose a facile interface optimization strategy in which an expanded polytetrafluoroethylene (ePTFE) skeleton layer is biasedly embedded on the surface of the perfluorosulfonic acid (PFSA) membrane bulk to form three-dimensional surface structures naturally. The experimental results show that the biased ePTFE-reinforced membranes (BRMs) demonstrate significantly enhanced surface roughness compared with conventional central ePTFE-reinforced membranes (CRMs), thus providing an enlarged cathode membrane/catalyst layer contact area. With optimized membrane/catalyst layer interface bonding, the fuel cells equipped with BRM1 and BRM2 (ionomer concentrations of 10 and 20 wt %, respectively) exhibit markedly reduced interfacial resistance, increased electrochemical surface area, and improved power performance compared with conventional CRMs. Furthermore, this biased reinforcing process does not weaken the mechanical reinforcing and dimension constraint function of ePTFE skeletons in PFSA membranes. Instead, the BRM membranes demonstrate the same level of mechanical properties, swelling rates, and hydrogen crossover as CRM membranes. After the wet/dry cycle test, BRM1 exhibits less mechanical degradation than CRMs due to enhanced interface bonding, reflected in lower hydrogen crossover and interfacial resistance increase.

A High-Performance Membrane Electrode Assembly with an Ultrathin Proton Exchange Membrane Based on a Wet-Combining Interface Forming Strategy

“…As shown in Figure b,c, the ePTFE reinforcement in the commercial Gore membrane of C-MEA has a thickness of ∼3.80 μm, which is thicker than that of the RM of R-MEA (∼2.25 μm). This thicker ePTFE reinforcement skeleton layer has a superior reinforcing function, thus making the Gore membrane possess a higher dimensional stability and a lower hydrogen crossover. , In general, the RM of the novel R-MEA shows the same level of I cross as the commercial Gore membrane of C-MEA, which reflects its practicality.…”

“…This thicker ePTFE reinforcement skeleton layer has a superior reinforcing function, thus making the Gore membrane possess a higher dimensional stability and a lower hydrogen crossover. 33,34 In general, the RM of the novel R-MEA shows the same level of I cross as the commercial Gore membrane of C-MEA, which reflects its practicality.…”

Preparation of an Integrated Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cells Using a Novel Wet-Bonding Strategy

“…It is noteworthy that the ionomer fills into the micropores of ePTFE reinforcement and no pore is observed in ePTFE/ionomer combination region . The electrolyte dispersion with preferred flowability can easily fill the micropores (78% porosity) of ePTFE reinforcement and reach the upper surface ePTFE reinforcement through the micropores. ,, This means that the ePTFE microporous reinforcement should not significantly affect the proton conductivity of PEM …”

“…38 The electrolyte dispersion with preferred flowability can easily fill the micropores (78% porosity) of ePTFE reinforcement and reach the upper surface ePTFE reinforcement through the micropores. 26,40,41 This means that the ePTFE microporous reinforcement should not significantly affect the proton conductivity of PEM. 41 As shown in Figure 2g, the thickness of the commercial GORE-SELECT PEM in MEA-CCM is ∼13−15 μm, and the middle is an ePTFE/Nafion combination region with a thickness of ∼4 μm.…”

Free-Standing Polymer Covalent Organic Framework Membrane with High Proton Conductivity and Structure Stability

“…To this end, some researchers incorporated highly conductive COFs into polymer matrices to prepare composite membranes, which realized excellent film-forming property. ,− However, the proton conduction property of these membranes is unsatisfactory because of the limited loading amount of COF particle and the blockage of transfer channel in COF by polymer chains . A feasible solution for this issue may reside in the direct involvement of polymer in the COF preparation process, which can better take advantage of both COFs and polymers.…”