Performance Of Membrane Electrode Assembly Research Articles

Enhancement of Characteristics of Nitrogen-Doped Graphene Composite Materials Prepared by Ball Milling of Graphite with Melamine: Effect of Milling Speed and Material Ratios

Nitrogen-doped graphene has been prepared using the ball milling method that is known to be eco-friendly, scalable and economic. The parameters studied in the synthesis were the mass ratio of starting materials (graphite and melamine) and speed of the ball milling. To determine its structure and properties, the nitrogen-doped graphene was characterized using Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray (FESEM-EDX), RAMAN Spectroscopy and X-Ray Diffraction (XRD). Based on FESEM-EDX analysis, the doped composite exhibited nitrogen content of ~3.5%. The nitrogen-doped graphene was examined as a replacement for platinum catalysts in fuel cells. Different composite catalysts were evaluated using a Rotating Disk Electrode (RDE) to test the Oxidation Reduction Reaction (ORR) performance. Based on ORR performance comparison, the composite with highest performance was then used to fabricate a Membrane Electrode Assembly (MEA). Testing on MEA performance was conducted on a Fuel Cell Station, where Open Circuit Voltage (VOC) of 0.14 V was obtained. The results indicate that the ball milling method may produce an efficient nitrogen-doped graphene MEA electrode from graphite and melamine only. Compared with a platinum counterpart, the new composite material electrode showed soundly high current-potential characteristics and fuel conversion efficiency.

Platinum-Nickel Nanowires with Improved Hydrogen Evolution Performance in Anion Exchange Membrane-Based Electrolysis.

Platinum-nickel (Pt-Ni) nanowires were developed as hydrogen evolving catalysts for anion exchange membrane electrolyzers. Following synthesis by galvanic displacement, the nanowires had Pt surface areas of 90 m2 gPt-1. The nanowire specific exchange current densities were 2-3 times greater than commercial nanoparticles and may benefit from the extended nanostructure morphology that avoids fringe facets and produces higher quantities of Pt{100}. Hydrogen annealing was used to alloy Pt and Ni zones and compress the Pt lattice. Following annealing, the nanowire activity improved to 4 times greater than the as-synthesized wires and 10 times greater than Pt nanoparticles. Density functional theory calculations were performed to investigate the influence of lattice compression and exposed facet on the water-splitting reaction; it was found that at a lattice of 3.77 Å, the (100) facet of a Pt-skin grown on Ni3Pt weakens hydrogen binding and lowers the barrier to water-splitting as compared to pure Pt(100). Moreover, the activation energy of water-splitting on the (100) facet of a Pt-skin grown on Ni3Pt is particularly advantageous at 0.66 eV as compared to the considerably higher 0.90 eV required on (111) surfaces of pure Pt or Pt-skin grown on Ni3Pt. This favorable effect may be slightly mitigated during further optimization procedures such as acid leaching near-surface Ni, necessary to incorporate the nanowires into electrolyzer membrane electrode assemblies. Exposure to acid resulted in slight dealloying and Pt lattice expansion, which reduced half-cell activity, but exposed Pt surfaces and improved single-cell performance. Membrane electrode assembly performance was kinetically 1-2 orders of magnitude greater than Ni and slightly better than Pt nanoparticles while at one tenth the Pt loading. These electrocatalysts potentially exploit the highly active {100} facets and provide an ultralow Pt group metal option that can enable anion exchange membrane electrolysis, bridging the gap to proton exchange membrane-based systems.

Effect of the fabrication condition of membrane electrode assemblies with carbon-supported ordered PtCo electrocatalyst on the durability of polymer electrolyte membrane fuel cells

Electrode structure improvement is one of the most promising paths for improving the durability of polymer electrolyte membrane fuel cells (PEMFCs). As strategies to prevent structural deformation and enhance the durability of membrane electrode assemblies (MEAs) with structurally ordered PtCo/C-based cathodes, we evaluated the effect of hot pressing and reinforcing the electrode's structure by increasing the ionomer content. Even though the initial performances of the hot-pressed MEA (HP) and the MEA with extra cathode ionomer (EI) were lower than that of the conventional MEA (CE) by 13.6% and 19.1%, respectively, CE degraded much more significantly than HP and EI after an accelerated degradation test. Therefore, HP and EI could deliver significantly higher single cell performances than CE (22.7% and 43.7%, respectively). The improvements in the durability of HP and EI could be correlated with the structural stability which could be evaluated by structure and electrochemical analysis including electrochemical impedance spectroscopy.

Tailoring of Electrocatalyst Inks for Performance Enhancement in Proton Exchange Membrane Fuel Cells

Solvent-based processing is the most favored method for the fabrication of electrocatalyst layers of proton exchange membrane fuel cells. In this process, the catalyst supported on carbon and stabilized by an ionomer is dispersed in a continuous solvent medium, forming a catalyst ink. Although the importance of ink processing has been realized, it is still governed by empiricism. To this end, we systematically investigated the effects of catalyst ink processing on the colloidal stability and the electrochemical performance of membrane electrode assemblies (MEAs). Analytical centrifugation and electron microscopy were employed to characterize the catalyst inks. It was found that high-pressure homogenization produced the most stable ink with maximum MEA performance in comparison to dispersion by ultrasonication. This study paves the way for a better understanding of the process-structure-property relationships towards the development of knowledge-based electrocatalyst inks.

Proton Transport in Aluminum-Substituted Mesoporous Silica Channel-Embedded High-Temperature Anhydrous Proton-Exchange Membrane Fuel Cells

Polymer composite membrane technology is promising for enhancing the performance of membrane electrode assemblies for high-temperature fuel cells. In this study, we developed a novel anhydrous proton-exchange polybenzimidazole (m-PBI) composite membrane using Al-substituted mesoporous silica (Al-MCM-41) as a proton-carrier support. The surface-substituted Al-MCM-41 formed effective proton-transport pathways via its periodic hexagonal channel and improved the proton conductivity. The proton conductivity of an m-PBI filled with 9 wt.% filler was 0.356 S cm-1 at 160 °C and 0% humidity, representing an increase of 342% compared to that of a pristine m-PBI. Further, the current density at 0.6 V and maximum power density of m-PBI composite membranes were increased to 0.393 A cm-2 and 0.516 W cm-2, respectively. The enhanced fuel-cell performance was attributed to the proton-transfer channels and H3PO4 reservoirs formed by the mesopores of the Al-MCM-41 shell. The results indicated that Al-MCM-41 is suitable with respect to the hybrid homologues for enhancing the proton transport of the m-PBI membrane.

Cathode starvation as an accelerated conditioning procedure for perfluorosulfonic acid ionomer fuel cells

Abstract Freshly assembled proton exchange fuel cells (PEMFC) require conditioning to reach maximum power density. This process may last up to tens of hours and adds to the cost of commercial fuel cell technology. We present an accelerated conditioning procedure involving starving the cathode of oxidant. In single cells, this procedure conditions a membrane electrode assembly (MEA) within 40 min, without compromising durability. The performance and durability of MEAs conditioned using this technique are compared with US Department of Energy (DOE) and European Union (EU) harmonized protocols, and to an amperometric conditioning protocol. The time to reach peak power density using cathode starvation conditioning is

Novel Dendritic Structure for Both Durable and High Performance of PEMFC Using Electrospray Deposition

The degradation of the proton exchange membrane (PEM) induced by various physical and chemical causes is one of the critical obstacles for the commercialization of proton exchange membrane fuel cells (PEMFCs). Among them, the free radical attack is the main reason for conductivity decrease, membrane thinning and pinholes. Thus, it is crucial to develop a durable electrolyte membrane that can resist free radical attacks while retaining high performance. In this work, we introduce a novel multifunctional dendritic structure composed of a perfluorinated sulfonic acid (PFSA) ionomer and CeO2 nanoparticles using a simple electrospray deposition (ESD) method. The dendritic structure on the cathode side of the membrane enhanced the power performance of membrane electrode assembly (MEA) about 15% owing to the effective utilization of the active sites and enhanced mass transport by voids between the electrode and gas diffusion layer. Moreover, the CeO2 nanoparticle incorporated structures effectively protected PEM from the free radical attacks. The chemical durability of MEA was investigated using Fenton’s test and OCV hold test and the electro-sprayed membrane showed a lower OCV drop rate (0.5mV/h), compared to that of the reference (1.2mV/h).

Additional Carbon/Nafion Covering Layer on Electrode in Polymer Electrolyte Membrane Fuel Cell for Effective Operation at Low Relative Humidity Condition

Demands for fuel cells that can operate in ambient conditions are increasing as their applications expand to portable devices and unmanned aircraft system. Particularly, maintaining high-hydration state of membrane electrode assembly (MEA) in the fuel cell in ambient condition is essential for prevention of performance degradation. At low relative humidity condition, the polymer electrolyte membrane exhibit poor ionic conductivity because the transfer of protons bonded with water molecules is severely limited. Therefore, developing the effective strategy to prevent dehydration in polymer electrolyte membrane fuel cell (PEMFC) is highly required. Herein, we successfully improve the MEA performance in low relative humidity condition by introducing a functional carbon-covering layer onto the catalyst layer on the cathode side. The carbon-covering layer plays an effective role to retain generated water and shows good compatibility with the MEA without interfering with the electrochemical reaction. Furthermore, we have investigated the optimized Nafion ionomer loading and the thickness of the carbon-covering layer for effective operation in both low and high relative humidity condition. Figure 1

Membrane electrode assembly performance of a standalone microporous layer on a metallic gas diffusion layer

Metallic gas diffusion layers (MGDLs) with controlled micro-porosity, offer mechanical and thermal stability in proton exchange membrane fuel cells. The MGDLs require tailored microporous layers (MPLs) to facilitate optimal gas diffusion and water management. In this study, a MGDL surface was first treated with PTFE and then coated with a standalone MPL (sa-MPL). The sa-MPL was made using a wet kneading method with a high aspect ratio of graphite flakes as filler. Conventional wet-coated MPLs (WC-MPLs) were produced with and without graphite flakes and coated onto MGDLs for physical and electrochemical comparison. SEM images showed degrees of macropore intrusion of the MPL into the MGDL which facilitate water removal and gas diffusion. Compared to the WC-MPLs, the produced sa-MPLs (20 μm) had a homogeneous surface with no cracking and uniform porosity due to the mechanical strength provided by the graphite filler. The sa-MPL/MGDL membrane electrode assembly (MEA) outperformed the commercial carbon GDL reaching 3.0 A cm−2 at 100% relative humidity (RH) with a low high frequency resistance (HFR). This study showed that the internal morphology and external form of the sa-MPL allowed for efficient capillary water removal and increased gas diffusion resulting in superior MEA performance.

Characterization of Electrode with Various of Pt-Ru/C Catalyst Loading and the Performance Test of Membrane Electrode Assembly (MEA) in Passive Direct Methanol Fuel Cell (DMFC)

Membrane Electrode Assembly (MEA) is the most important component in fuel cell devices. Electrodes composing MEA greatly determine the performance and durability of its application in passive Direct Methanol Fuel Cell (DMFC). Fabrication and characterization of electrodes with various loading Pt-Ru/C catalysts and their application to DMFC have been carried out. The XRD characterization results indicate the presence of C atoms which are indicated by the appearance of peaks at angles 2θ = 25°-30°. In areas, 44.4° and 45.1° indicate the presence of Ru even with low intensity and platinum in the area of 54.67°, 39.86°, 54.736°, 39.88°, and 68.3°. The highest ECSA value and electrical conductivity and low resistance showed the best catalytic activity possessed by electrodes with the loading of Pt-Ru/C catalyst 10 mg/cm2. MEA with a catalyst loading of 8 mg/cm2 is known to have a fairly large initial voltage before the load is given based on the results of Open Circuit Voltage (OCV) measurements. The MEA performance was observed based on I-V and I-P performance tests using the SMART2 WonAtech Fuel Cell Test Station on passive DMFC stacks with 3 M methanol as fuel. The best MEA shown in MEA with catalyst loading is 10 mg/cm2 because it can maintain and achieve a voltage and power density that is quite higher than other MEAs in each load increase in the form of current density.

Study of the influence of Nafion/C composition on electrochemical performance of PEM single cells with ultra-low platinum load

The electrochemical performance of membrane electrode assemblies (MEAs) with ultra-low platinum load (0.02 mgPt cm−2) and different compositions of Nafion/C in the catalytic layer have been investigated. The electrodes were fabricated depositing the catalytic ink, prepared with commercial catalyst (HiSPEC 2000), onto the gas diffusion layers by wet powder spraying. The MEAs were electrochemically tested using current-voltage curves and electrochemical impedance spectroscopy measurements. The experiments were carried out at 70 °C in H2/O2 and H2/air as reactant gases at 1 and 2 bar pressure and 100% of relative humidity. For all MEAs tested, power density increases when the gasses pressure is increased from 1 to 2 bar. On the other hand, power density also increased when oxygen is used instead of air as oxidant gas in cathode. The lower power density (34 mW cm−2) and power per Pt loading (0.86 kW gPt−1) corresponds to the MEA prepared without Nafion in anode and cathode catalytic layers working with hydrogen and air at 1 bar pressure as reactants gas. The MEA with 30% wt Nafion/C reached the highest power density (422 mW cm−2) and power per Pt loading (10.60 kW gPt−1) using hydrogen and oxygen at 2 bar pressure. Finally, electrode surface microstructure and cross sections of MEAs were analyzed by Scanning Electron Microscopy (SEM). Examination of the electrodes, revealed that the most uniform ionomer network surface corresponds to the electrode with 40 wt% Nafion/C, and MEA ionomer-free catalytic layer shows delamination, it leads to low electrochemical performance.

Low-PGM and PGM-Free Catalysts for Proton Exchange Membrane Fuel Cells: Stability Challenges and Material Solutions.

Fuel cells as an attractive clean energy technology have recently regained popularity in academia, government, and industry. In a mainstream proton exchange membrane (PEM) fuel cell, platinum-group-metal (PGM)-based catalysts account for ≈50% of the projected total cost for large-scale production. To lower the cost, two materials-based strategies have been pursued: 1) to decrease PGM catalyst usage (so-called low-PGM catalysts), and 2) to develop alternative PGM-free catalysts. Grand stability challenges exist when PGM catalyst loading is decreased in a membrane electrode assembly (MEA)-the power generation unit of a PEM fuel cell-or when PGM-free catalysts are integrated into an MEA. More importantly, there is a significant knowledge gap between materials innovation and device integration. For example, high-performance electrocatalysts usually demonstrate undesired quick degradation in MEAs. This issue significantly limits the development of PEM fuel cells. Herein, recent progress in understanding the degradation of low-PGM and PGM-free catalysts in fuel cell MEAs and materials-based solutions to address these issues are reviewed. The key factors that degrade the MEA performance are highlighted. Innovative, emerging material concepts and development of low-PGM and PGM-free catalysts are discussed.

Current understanding of catalyst/ionomer interfacial structure and phenomena affecting the oxygen reduction reaction in cathode catalyst layers of proton exchange membrane fuel cells

Abstract To improve the performance of membrane electrode assemblies used in proton exchange membrane fuel cells, a better understanding is necessitated regarding the nano/microstructure of the catalyst layer and the physicochemical phenomena responsible for the oxygen reduction reaction (ORR) occurring on this layer. In particular, it is very important to understand catalyst/ionomer interfaces in the cathode catalyst layer to apply the advanced ORR catalysts to the cathode catalyst layer in membrane electrode assemblies, which have solid-phase electrolytes; these catalysts are primarily developed under liquid electrolyte conditions. A closer observation of the catalyst/ionomer interfacial structure shows that all the transport processes required for ORR are controlled by the ionomer thin film covering the catalyst. Therefore, this review addresses this issue and introduces recent studies on catalyst/ionomer interfaces. We discuss the current understanding of the structure of the catalyst/ionomer interface, which depends on the surface characteristics of the catalyst and the ionomer, as well as transport of water, ions, and gas; these factors are in turn dependent on the structure of the interface. In addition, we introduce research efforts for improving the properties of catalyst inks, which form the basis for controlling the catalyst/ionomer interfacial structure. Based on the findings of these studies, we propose further opportunities and challenges in the study of catalyst/ionomer interfaces.

Green and Low-Cost Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cells: Effect of Double-Layer Electrodes and Gas Diffusion Layer

The success of fuel cells depends on the design structure meanwhile catalysts electrodes and membrane allowing easy access of oxygen and protons. Using non-precious catalyst electrodes based on recyclable carbon nanostructures is most important to produce clean energy and increase the ability to commercialize the fuel cells. Herein, reduced graphene oxide (rGO) and graphene/magnetic iron oxide nanocomposite (rGO/MIO) are successfully synthesized as anode and cathode respectively from polyethylene terephthalate (PET) waste bottles using easy steps in order to simplify the method and reducing the production cost. While, the membrane is prepared from low cost and eco-friendly ternary polymers blend which are polyvinyl alcohol (PVA), polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP) then doped with sulfonated graphene oxide. The prepared electrodes have characteristic high porosity and their electrocatalytic performances are evaluated using three-electrode cell electrochemical studies as cyclic voltammetry and linear scan voltammetry combined with rotating disk electrode. A new assembly of the membrane between two non-precious catalyst electrodes as a single polymer electrolyte membrane fuel cell (PEMFC) was developed using a catalyst-coated membrane technique. The membrane electrode assembly (MEA) design parameters which affect its performance in hydrogen fuel cells as number of used catalyst layers (CL) or using gas diffusion layer (GDL) were evaluated in a single cell set-up with H2/O2 operation and the results revealed that the performance MEA was enhanced with using GDL more than that of MEA without GDL by 66% at a current density of 0.8 A cm−2 while the performance with double CL was better than that of the conventional single CL by 30 % at a current density of 0.98 mA cm−2.

Impact of Polyvinylidene Fluoride on Nanofiber Cathode Structure and Durability in Proton Exchange Membrane Fuel Cells

The impact of polyvinylidene fluoride (PVDF) as a binder component on the durability of Pt/C cathodes in a proton exchange membrane fuel cell membrane-electrode-assembly (MEA) during a carbon corrosion accelerated stress test (AST) was examined using electrochemical fuel cell data and visual inspection/analysis of the cathode morphology via electron-microscopy. Electrospun nanofiber cathode mat MEAs with a Nafion®/PVDF or Nafion/poly(acrylic acid) (PAA) binder or a slurry cathode MEA with neat Nafion or a Nafion/PVDF binder were investigated. The presence of PVDF had profound effects on the structure and chemical/electrochemical properties of a fuel cell cathode; its hydrophobic property slowed the rate of carbon loss and its robust mechanical properties added strength to the binder. Thus, the extent of carbon loss during an AST was inversely proportional to the PVDF content of the binder and there was no observable cathode thinning nor any change in cathode porosity after the AST, when the cathode binder contained at least 50 wt% PVDF. In terms of long-term durability, these beneficial structural effects outweighed the lower Nafion/PVDF binder conductivity and the associated lower initial power output of a Nafion/PVDF cathode MEA. For hydrophilic slurry and nanofiber cathodes with neat Nafion or Nafion/PAA fibers, low power after the carbon corrosion AST was due to greater carbon losses, cathode thinning and the collapse of cathode pores, which dominated MEA performance even though the initial cathode ECSA and mass activity were high for these two MEAs.

Feed gas exchange (startup/shutdown) effects on Pt/C cathode electrocatalysis and surface Pt-oxide behavior in polymer electrolyte fuel cells as revealed using in situ real-time XAFS and high-resolution STEM measurements.

The synchronizing measurements of both cyclic voltammograms (CVs) and real-time quick XAFSs (QXAFSs) for Pt/C cathode electrocatalysts in a membrane electrode assembly (MEA) of polymer electrolyte fuel cells (PEFCs) treated by anode-gas exchange (AGEX) and cathode-gas exchange (CGEX) cycles (startup/shutdown conditions of FC vehicles) were performed for the first time to understand the opposite effects of the AGEX and CGEX treatments on the Pt/C performance and durability and also the contradiction between the electrochemical active surface area (ECSA) decrease and the performance increase by CGEX treatment. While the AGEX treatment decreased both the ECSA and performance of MEA Pt/C due to carbon corrosion, it was found that the CGEX treatment decreased the ECSA but increased the Pt/C performance significantly due to high-index (331) facet formation (high-resolution STEM) and hence the suppression of strongly bound Pt-oxide formation at cathode Pt nanoparticle surfaces. Transient QXAFS time-profile analysis for the MEA Pt/C also revealed a direct relationship between the electrochemical performance or durability and transient kinetics of the Pt/C cathode.

Anode structure with double-catalyst layers for improving the direct ethanol fuel cell performance

The conventional anode design of direct ethanol fuel cells (DEFCs) usually encounter a problem on the performance stability and ethanol mass transport, i.e., ethanol crossover. Aiming to alleviate these issues, in this study, the anode with different configurations for DEFC was designed and fabricated with different catalyst layer (CL) and microporous layer (MPL) arrangements. The four types of membrane electrode assembly (MEA) is named with MEA-1 (with pretreated carbon paper (PCP) and PtCL), MEA-2 (with PCP, MPL and PtCL), MEA-3 (with PCP, MPL, PtCL and PdCL) and MEA-4 (with PCP, MPL, PtCL, MPL and PdCL). The performance, stability and ethanol crossover of MEAs were tested and measured for continuous long-term operation for 120 h, while the morphological characterization was analyzed. Based on the results, power density for each MEA decreased with time, while ethanol crossover increased gradually. The MEA-3 with additional PdCL shows a highest performance and stability about 20 W/m2, and has a lowest ethanol crossover's magnitude. The highest ethanol crossover was obtained using MEA-1 at 3.7 mg/m2·s. Higher ethanol crossover had caused low stability of DEFC performance which result higher irreversible degradation. Moreover, based on characterization, elemental mapping and EDX illustrated phenomena of membrane swelling, delamination of electrode from membrane, and CL loss after stability test for 5 days for all MEAs. The significance of anode structure design was proven in this current study. The anode design of double-layered CL has potential to use at anode structure to reduce ethanol crossover rate, thereby improving DEFC performance and stability.

In situ long-term membrane performance evaluation of hydrogen-bromine flow batteries

Because of the impracticality of long life time testing of hydrogen bromine flow batteries (HBFBs) under real, cyclic operating conditions, we utilized a high-frequency cycling load accelerated lifetime test (ALT) to evaluate the membrane electrode assembly performance in HBFBs. Four different membrane chemistries were tested to assess the relative long-term performance and durability of the corresponding HBFBs and to understand the main long-term failure mechanism in HBFB technology. The high-frequency cycling load ALT is a highly valuable method to assess long-term HBFB (components) stability and to understand the degradation/failure mechanism. The results showed that the utilization of long side chain perfluorosulfonic acid (LSC PFSA, i.e. Nafion®) membranes result in stable HBFB operation until a sudden cell failure at the end of the cycle life. The use of a more selective (lower bromine species crossover) reinforced LSC PFSA membrane results in approx. five times longer life times. In contrast, the use of a grafted polyvinylidene fluoride (SPVDF) membrane results in a slow incremental performance decrease (or area resistance increase) during the ALT and, again, a sudden cell failure at the end of the cycle life. After the ALT, the LSC PFSA membrane still shows high chemical stability. On the other hand, the grafted SPVDF and SPE membranes show clear membrane degradation visible as a strong decrease in IEC and an increase in ohmic AR. Gradual Pt catalyst degradation-dissolution, that results in insufficient Pt catalyst loading and subsequently low hydrogen reaction kinetics, is the main failure mechanism of the HBFBs. The membrane bromine species crossover rate is directly related to the rate of Pt catalyst degradation-dissolution and scales almost linearly with the cell total ampere-hours. As long as the catalyst loading is sufficient and does not reach a minimum value, this observed Pt degradation-dissolution rate does not significantly impact the cell performance.

Improving cell performance and alleviating performance degradation by constructing a novel structure of membrane electrode assembly (MEA) of DMFCs

The conventional electrodes of direct methanol fuel cells (DMFCs) usually encounter a problem that the catalysts sink into the diffusion layer after a period of operation, causing a lowered catalyst utilization and degraded cell performance. Aiming to alleviate this problem, in this work a novel anode electrode structure is proposed, in which a microporous layer containing Nafion polymer is added between the catalyst layer and the microporous layer with PTFE. The presence of the Nafion-contained layer can expand the three-phase interface region of the electrochemical reactions and improve the utilization of the catalyst. The single cell test showed that the peak power densities of the novel membrane electrode assembly (MEA) fed with 0.5 M and 2 M methanol solutions reached 38.35 mW cm−2 and 101.82 mW cm−2, which increased by 100.42% and 15.27% compared with those of conventional single microporous layer. Electrochemical impedance spectroscopy (EIS) measurements indicated the charge transfer resistance of the conventional MEA structure was increased by 303.78%, while the new one was decreased by 47.91% after continuously operating for 48 h. The anode electrochemical active surface area (ECSA) values of the novel MEA and the conventional MEA were 52.6 m2 g-1 and 44.3 m2 g-1. These experimental results showed that the performance of the double microporous layer MEA was higher than that of the conventional MEA. This new microporous layer structure is promising to be used in fuel cells to improve cell performance and alleviate performance degradation after long-term operating.

Layered Lanthanide Sulfophosphonates and Their Proton Conduction Properties in Membrane Electrode Assemblies

Metal phosphonates containing acidic groups exhibit a wide range of proton conduction properties, which may enhance the performance of membrane electrode assemblies (MEAs). In this work, focus is p...