Commercial Membrane Electrode Assembly Research Articles

Degradation Mechanisms in Advanced MEAs for PEM Water Electrolyzers Fabricated by Reactive Spray Deposition Technology

Proton exchange membrane water electrolyzers (PEMWEs) have demonstrated enormous potential as the next generation hydrogen production technology. The main challenges that the state-of-the-art PEMWEs are currently facing are excessive cost and poor durability. Understanding the failure modes in PEMWEs is a key factor for improving their durability, lowering the precious metal loading, and hence cost reduction. In this work, reactive spray deposition technology (RSDT) has been used to fabricate a membrane electrode assembly (MEA) with one order of magnitude lower Pt and Ir catalyst loadings (0.2–0.3 mgPGM cm−2) in comparison to the precious metal loadings in the stat-of-the-art commercial MEAs (2–3 mgPGM cm−2). As fabricated MEA with an active area of 86 cm2, has been tested for over 5000 h at steady-state conditions that are typical for an industrial hydrogen production system. Herein, we present and discuss the results from a comprehensive post-test analysis of the MEA of interest. The main degradation mechanisms, governing the performance loss in the RSDT fabricated MEA with ultra-low precious metal loadings, have been identified and discussed in detail. All failure modes are critically compared and the main degradation mechanism with the highest impact on the MEA performance loss among the others is identified.

Activation of bimetallic PtFe nanoparticles with zeolite-type cesium salts of vanadium-substituted polyoxometallates toward electroreduction of oxygen at low Pt loadings for fuel cells

The catalytic activity of commercial carbon-supported PtFe (PtFe/C) nanoparticles admixed with mesoporous polyoxometalate Cs3H3PMo9V3O40, (POM3-3–9), has been evaluated towards oxygen reduction reaction (ORR) in acid medium. The polyoxometalate cesium salt co-catalyst/co-support has been prepared by titration using the aqueous solution of phosphovanadomolibdic acid. The synthesized material has been characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results confirm formation of the polyoxometalate salt with the characteristic Keggin-type structure. The composite catalyst has been prepared by mixing the POM3-3–9 sample with the commercial PtFe/C by sonication. The diagnostic rotating ring-disk voltammetric studies are consistent with good performance of the system with low Pt loading during ORR. The fuel cell membrane electrode assembly (MEA) utilizing the PtFe/POM-based cathode has exhibited comparable or better performance (at relative humidity on the level of 100, 62, and 17%), in comparison to the commercial MEA with higher Pt loading at the cathode. Furthermore, based on the cell potential and power density polarization curves, noticeable improvements in the fuel cell behavior have been observed at the low relative humidity (17%). Finally, the accelerated stress test, which uses the potential square wave between 0.4 V and 0.8 V, has been performed to evaluate MEA stability for at least 100 h. It has been demonstrated that, after initial losses, the proposed catalytic system seems to retain stable performance and good morphological rigidity.

Experimental validation for enhancement of PEMFC cold start performance: Based on the optimization of micro porous layer

The cold start is one of the key research fields in PEMFC studies. The improvement of PEMFC’s (proton exchange membrane fuel cell) unassisted cold start performance has played a positive role in promoting the industrialization and commercialization of FCV (fuel cell vehicle). In this work, as the key point of MEA (membrane electrode assembly) structure optimization, MPL (micro porous layer) aims to make the generated water can be retained in the CLs (catalyst layer) and membrane in the form of membrane water at the initial period of cold start. And the cold start performance of the optimized MEA single cell and stack are observed and analyzed by the segmented cell technology. After comparing with the cold start performance of the commercial MEA single cell and stack under the same conditions, the improvement of the cold start performance is verified. The single cell of MEA1 could achieve a quick unassisted cold start at a start-up temperature of −15 °C, and the cold start time under 0.2 V in CV (constant voltage) mode is 153 s, while the commercial MEA single cell can only achieve a successful cold start under the minimum start-up temperature of −10 °C. The optimized MEA stack can realize a quick unassisted cold start at a startup temperature of −20 °C, and the cold start time under 0.1 V in CV mode is 63 s, while the commercial MEA stack can only achieve a successful cold start under the minimum startup temperature of −15 °C.

A Durable and Efficient Electrocatalyst for Saline Water Splitting with Current Density Exceeding 2000 mA cm−2

AbstractWater electrolysis is promising for industrial hydrogen production to achieve a sustainable and green hydrogen economy, but the high cost of the technology limits its market share. Developing efficient yet economic electrocatalysts is crucial to decrease the cost of electricity and electrolytic cell. Meanwhile, electrolysis in seawater electrolyte can further reduce feedstock cost. Here, a type of electrocatalyst is synthesized, where trace precious metals are strongly anchored on a corrosion‐resistive matrix. As an example, the produced Pt/Ni‐Mo electrocatalyst only needs an overpotential of 113 mV to reach an ultrahigh current density of 2000 mA cm−2 in the saline‐alkaline electrolyte, demonstrating the best performance reported thus far. It shows high activity and long durability in various electrolytes and under harsh conditions, including strong alkaline and simulated seawater electrolytes, and under elevated temperatures up to 80 °C. This electrocatalyst is produced on a large scale at a low cost and shows good performance in a commercial membrane electrode assembly stack, demonstrating its feasibility for practical water electrolysis.

Engineering sub-nano structures with highly jagged edges on the Pt surface of Pt/C electrocatalysts to promote oxygen reduction reactions

Improving the Pt mass activity (imPt) of electrocatalysts towards the oxygen reduction reactions requires an increase in Pt atom utilization efficiency. Through the combination of Cu underpotential deposition and Pt galvanic replacement (CuUPD-GAL), Pt nanoclusters (Ptcs<1 nm) with highly jagged edges (H-Ptcs) are specifically constructed on the Pt surface of a typical carbon-supported, Pt-nanoparticle (Pt/C) electrocatalyst. The H-Ptcs contribute to an imPt of 21.8 A mgPt−1 (at 0.9 V versus reversible hydrogen electrode), which exceeds that achieved by Pt/C (0.1–0.25 A mgPt−1) by a factor of 200. To facilitate a full-cell evaluation and to mimic the batch flow production of electrocatalysts, a sequential flow injection procedure is developed that enables the direct H-Ptcs modification on a commercial membrane electrode assembly (MEA), the heart of a fuel cell. In a full cell (real fuel cell), the contribution of the H-Ptcs to the current density of 3.5 A cm−2 at 0.7 V and maximum power density of 8.0 W cm−2 is higher than that of state-of-the-art Pt-containing catalysts (<1.5 A cm−2 and <1.4 W cm−2). A hybrid Ptc modification approach, in which an MEA is subjected to two sequential Ptc modification processes, improves the durability of the MEA while maximizing activity.

Membrane Electrode Assemblies Fabricated By Reactive Spray Deposition Technology for Advanced Proton Exchange Membrane Water Electrolyzers: Study of the Degradation Mechanisms

Proton exchange membrane water electrolyzers (PEMWEs) have demonstrated great potential as the next generation hydrogen production technology1,2. The main challenges that the state-of-the-art PEMWEs are currently facing are: (i) high cost, (ii) low efficiency, and (iii) poor durability performance3. Understanding the failure modes of PEMWEs during the operation is a key factor for improving their durability performance, as well as for lowering the precious metal loading in the catalyst layers and hence for reducing their cost. However, the catalyst degradation mechanisms in PEMWEs during operation, especially for the Ir-based anode catalysts, have not been fully understood.In this work, reactive spray deposition technology (RSDT) has been used to fabricate membrane electrode assemblies (MEAs) with one order of magnitude lower Pt and Ir catalyst loadings in their cathode and anode catalyst layers, respectively, in comparison to the precious metals loading in the state-of-the-art commercial MEAs for PEMWEs 4–6. Two of as- fabricated MEAs with geometric area of 86 cm2, have been tested at steady-state conditions that are typical for commercial hydrogen production system. One of the cells was stopped and disassembled after 50 hours of operation, while the second one was disassembled after it failed after over 500 hours of operation. Herein we present a comprehensive comparative study of both MEAs, aimed at identifying and understanding the degradation mechanisms causing the MEAs failure. The pre- and post-test MEA characterizations are performed by scanning/transmission electron microscopy (S/TEM), scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD) and X-ray computed tomography (X-CT). In addition, rotating disk electrode (RDE) technique has been utilized for assessment of the catalytic activities of the RSDT-fabricated anode Ir/IrOx catalysts before and after the failure. The main degradation mechanisms, governing the failure modes in the MEAs of interest, have been identified and discussed. References Carmo, M., Fritz, D. L., Mergel, J. & Stolten, D. A comprehensive review on PEM water electrolysis. Int. J. Hydrogen Energy 38, 4901–4934 (2013).Babic, U. et al. Critical Review — Identifying Critical Gaps for Polymer Electrolyte Water Electrolysis Development Review — Identifying Critical Gaps for Polymer Electrolyte Water. (2017). doi:10.1149/2.1441704jesButtler, A. & Spliethoff, H. Current status of water electrolysis for energy storage, grid balancing and sector coupling via power-to-gas and power-to-liquids: A review. Renew. Sustain. Energy Rev. 82, 2440–2454 (2018).Roller, J. M. & Maric, R. A Study on Reactive Spray Deposition Technology Processing Parameters in the Context of Pt Nanoparticle Formation. J. Therm. Spray Technol. 24, 1529–1541 (2015).Roller, J. M., Kim, S., Kwak, T., Yu, H. & Maric, R. A study on the effect of selected process parameters in a jet diffusion flame for Pt nanoparticle formation. J. Mater. Sci. 52, 9391–9409 (2017).Yu, H. et al. Nano-size IrOx catalyst of high activity and stability in PEM water electrolyzer with ultra-low iridium loading. Appl. Catal. B Environ. 239, 133–146 (2018).

Degradation study of a proton exchange membrane water electrolyzer under dynamic operation conditions

Understanding degradation phenomena of polymer electrolyte water electrolyzers operating under dynamic conditions is imperative for developing and implementing efficient and reliable means of energy storage from fluctuating and intermittent renewable energy sources. Herein, a commercial membrane electrode assembly with an amorphous IrOx anode is subjected to potential sweeping (1.4–1.8 V) with short and long holds and few steady-state interims for overall 830 h at 60 °C and ambient pressure to simulate frequent alternating idle and nominal operation regimes. Systematic electrochemical diagnostics and physicochemical methods are applied to identify degradation sources. Mild kinetic deactivation (2.6 μV/h) is observed independent on the dynamic protocol, due to loss of electrochemical surface area via crystallization. The amount of Ir dissolved and redeposited in the ionomer anode phase and in the membrane is negligible in comparison to the current state-of-the-art Ir loadings. As compared to kinetic losses, the irreversible resistive losses are one order of magnitude higher and are thought to be caused by the degradation of the membrane close to the anode catalyst layer. These resistive losses are associated specifically with dynamic operation. The two orders of magnitude higher, but recoverable, degradation during steady-state interims is attributed to the growth of inhibiting or long-lived species.

Novel platinum group metal-free catalyst ink deposition system for combinatorial polymer electrolyte fuel cell performance evaluation

A new system for rapid and precise fabrication of polymer electrolyte fuel cell (PEFC) membrane-electrode assemblies (MEAs) is introduced to facilitate rapid testing and characterization of platinum group metal-free (PGM-free) catalysts, with minimal waste of materials, using commercial combinatorial hardware and multi-channel potentiostat. The commercial combinatorial system, designed for high-throughput catalyst activity evaluation (i.e., low overpotential and current densities) using gas-diffusion electrodes (GDEs), has been further developed to enable simultaneous evaluation of the high current density performance on air of twenty-five cathodes prepared by coating catalyst-ionomer inks directly onto the membrane using a newly-developed deposition system. A nanopipette or micropipette coupled to a precise peristaltic pump is being used for precise and even catalyst ink deposition onto the membrane in each of twenty-five circular electrodes with areas of <1 cm2 and in the precise locations required by the commercial combinatorial MEA hardware. The automated ink deposition system is coupled with a custom-designed heated vacuum table mounted on a computer-controlled XY stage to prevent deformation of the membrane and electrode layers during ink deposition onto the membrane. This system was utilized to evaluate the impact of ionomer to catalyst ratio on the hydrogen-air fuel cell performance of the PGM-free catalyst.

On/off cycling test of low-temperature PEM fuel cell at fully humidified conditions

ABSTRACTAccelerated stress testing is one of the most used approaches to characterize the performance and the degradation of the membrane electrode assembly (MEA) in low-temperature hydrogen polymer electrolyte membrane fuel cells (PEMFC). A standard JRC on/off testing procedure was used to characterize two sets of commercial MEAs, by ElectroChem and by PaxiTech, respectively. Performance characteristics prior to and after the on/off procedure were measured. The changes in the resistivity of the MEA were examined by electrochemical impedance spectroscopy (EIS). The EIS data were analyzed and interpreted by a suitable equivalent circuit that consisted of a resistor and the Voigt’s structure in series with constant phase elements. Water on the anode side and the cathode side of the PEMFC was collected during the on/off procedure. The fluoride emission rate was determined from the collected water to obtain information about the chemical degradation of the MEA samples.

Effect of Catalyst Loading on the Degradation of d-PtCo/C Cathode Catalyst

The Consortium for Fuel Cell Performance and Durability (FC-PAD) was formed by the U.S. Department of Energy Fuel Cell Technologies office (FCTO) in 2015 to improve the understanding of performance and durability issues in polymer electrolyte membrane fuel cells (PEMFCs) and to help meet the DOE 2020 targets. This talk will summarize some of the durability work performed within the consortium on commercial dealloyed-PtCo/C catalyst-based membrane electrode assemblies (MEAs). Commercial MEAs using Nafion®HP membranes, ElystPt300670 (30wt.%PtCo/high surface area C) cathode catalyst, and ElystPt200380 (20wt.%Pt/Graphitized carbon) anode catalyst were obtained from Umicore. The MEAs were assembled in a 5cm2differential cell reported by D. R. Baker et al.1and conditioned extensively before performing beginning of life (BOL) characterization. The conditioning protocol included a recovery step where the cell was operated at high RH and low temperatures and voltages to flush out impurities and maximize the performance.2,3The samples were then subjected to the DOE-recommended square wave catalyst accelerated stress test (AST) which is a 3 sec hold at 0.6V and 3 sec hold at 0.95V at 80oC and 100%RH.4Characterizations were performed after 15,000 and 30,000 cycles of the AST with the recovery protocol applied to the MEA before characterization. Electrochemical characterization included mass activity, electrochemical surface area, polarization curves, Electrochemical Impedance Spectroscopy (EIS), and oxygen transport measurements. The BOL and end-of-test catalysts were also characterized by electron microscopy, energy dispersive X-ray spectroscopy, X-ray absorption spectroscopy, and small-angle X-ray scattering to determine particle size and Pt to Co content. The oxygen reduction reaction mass activity, electrochemical surface area, and performance in the kinetic region of the catalysts degrade with AST cycling. This loss can be attributed to both Co leaching from the catalyst and catalyst particle size increase. The effect of this degradation was most pronounced in the high current region for the MEA with low Pt loading. For example, in Figure 1, the voltage loss at 1A/cm2after 30,000 AST cycles is ~50mV for the 0.15mgPt/cm2MEA and ~200mV for the 0.05mgPt/cm2MEA. This is primarily due to increases in the pressure-independent oxygen transport resistance. The non-Fickian oxygen transport resistance of low-loaded (0.05 mgPt/cm2) MEAs is significantly larger than those of the high-loaded MEAs even at BOL and worsens significantly with ageing of the catalyst. EIS experiments in HelOx (21% O2, balance He) also revealed that there was an increase in the pressure-dependent gas transport during the AST cycling. However, little or no change was observed in the ionomer sheet resistance over the course of the durability testing, independent of the catalyst loading. These results will be compared with recent results reported for pure Pt catalyst-based MEAs subjected to similar tests.5In this talk, the analysis of the cathode catalyst composition and morphology before and after the testing will be presented in detail and correlated to the observed performance losses. Acknowledgements This research is supported by the U.S. Department of Energy Fuel Cell Technologies Office, through the Fuel Cell Performance and Durability (FC-PAD) Consortium (Fuel Cells Program Manager: Dimitrios Papageorgopoulos and Technical Development Manager: Greg Kleen). References D. R. Baker, D. A. Caulk, K. C. Neyerlin, and M. W. Murphy, J. Electrochem. Soc.,V156(9), B991-B1003 (2009). https://doi.org/10.1149/1.3152226.Zhang, B. A. Litteer, F. D. Coms, and R. Makharia,. J. Electrochem. Soc., V159(7),F287-F293 (2012). https://doi.org/10.1149/2.063207jes.Zhang et al, U.S Patent Application Publication US 2011/0195324 A1, August 11 (2001).United States Department of Energy Fuel Cells Technologies Office Multi-Year Research, Development, and Demonstration Plan. https://www.energy.gov/sites/prod/files/2017/05/f34/fcto_myrdd_fuel_cells.pdf.G. S. Harzer, J. N. Schwammiein, A. M. Damjanovic, S. Ghosh, and H. A. Gasteiger, J. Electrochem. Soc.,V165(6), F3118-F3131 (2018). https://doi.org/10.1149/2.0161806jes Figure 1

Platinum Nanoparticles on Plasma-Pretreated Carbon Nanotubes Prepared By Atomic Layer Deposition As Polymer Electrolyte Membrane Fuel Cell Catalysts

Polymer electrolyte fuel cells (PEMFC) are attracting attention as the next generation power supply for electric vehicles, unmanned aerial vehicles and submarines. However, the high price of fuel cell catalysts i.e. platinum (Pt) or platinum alloys is considered a major hurdle to the development of economical fuel cell electric vehicles. Another problem with Pt catalysts is the low stability of long term operation due to separation and aggregation of the catalyst from the carbon support resulting from repeated on-off switching. Recently, atomic layer deposition (ALD) has been proposed as a technique for synthesizing metal nanoparticles. ALD is considered to be the most advanced deposition technology that can control material size and composition in the atomic scale. In addition, ALD has demonstrated large scale conformal deposition of uniform films and particles over high aspect ratio trenches and complex three dimensional contours. In this study, Pt nanoparticles were successfully deposited on carbon nanotubes (CNTs) by ALD. The key to the success of high quality ALD Pt production has been found to be a plasma pretreatment that introduces functional groups that make the CNT surface ready to initiate the ALD nucleation. ALD Pt-CNT catalysts were evaluated as cathode catalysts for PEMFC membrane-electrode-assemblies (MEAs). As a result, even though the Pt load is significantly reduced, the performance is significantly improved compared to commercial PEMFC MEAs in terms of power and stability.

A Pathway to Significant Reduction of Hydrogen Crossover with Pt Recombination Layer in Proton Exchange Membrane Water Electrolyzers

Proton exchange membrane water electrolyzers (PEMWEs) are the major components of the green source of high-purity hydrogen for chemical applications as well as energy storages. However, some technical and economic problems have restricted their widespread development. One of the principal technical issues hampering the extensive use of PEMWEs is hydrogen crossover. The produced hydrogen in the PEMWE cathode compartment is typically stored at high pressure through either an external compressor or electrochemical compression with high pressure PEMWEs which leads to a high overall efficiency [1-3]. However, some produced hydrogen passes through the proton exchange membrane restricting the cell performance, especially when operating under pressure [1, 4]. The hydrogen crossover also causes a serious safety hazard in the anodic compartment where the oxygen is produced because the lower explosion limit of hydrogen in oxygen content is about 4 vol.%. It has been shown that a mitigation strategy is needed to reach this value with a safety margin of 2 vol.% [4, 5]. Although several mitigation strategies have been utilized, the integration of a recombination layer incorporated directly into the membrane has shown the best performance. Recently, Klose et al. [4] showed that integrating Pt nanoparticles as a recombination layer with Pt loading of 0.02 mg cm-2 between a NR-212 and a N115 membrane of a PEMWE can significantly overcome the safety issue. The results indicated no hydrogen in oxygen after 245 hours at 1 A cm-2 which demonstrates the Pt recombination layer effect on hydrogen crossover reduction. However, a strong increase for hydrogen in oxygen content was observed at higher current densities (>1 A cm-2). Thus, a further investigation is still needed to achieve a better recombination layer by optimizing Pt nanoparticles distribution or the position of the recombination layer. In this work, a novel electrode fabrication method, reactive spray deposition technique (RSDT), was employed to deposit a Pt recombination layer directly introduced into the membrane. The microstructural characteristics of the Pt recombination layer were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thereafter, the stability and cell performance of a full RSDT catalyst coated membrane (86 cm2) were investigated using diagnostic tests including polarization analysis, cyclic voltammetry, and electrochemical impedance spectroscopy. The results revealed significant stability for 1000 hours at 1.8 A cm-2, 50 °C, 400 psi hydrogen pressure with lower catalyst loading compared to commercial membrane electrode assemblies (MEAs) and > 65% reduction in hydrogen crossover.

2 kW Modular PEM fuel cell stack for space applications: Development and test for operation under relevant conditions

A polymer electrolyte fuel cell stack of 2 kW of peak power has been designed, manufactured and tested. Such a fuel cell stack has been envisaged to be applied for manned lunar exploration missions, as secondary energy source for both mobile vehicles and fixed power plants. The stack has been bread-boarded in order to test and demonstrate the technology. The following constraints have been considered during the study: (i) operation with pure hydrogen and oxygen (ii) low humidification levels (iii) use of commercial Membrane Electrode Assemblies. The breadboard has been made consisting of two modules, each of 500 W of nominal power. Specific tests have been conducted to prove the effect of gravity on the breadboard performance and verify its ability to follow variable load profiles over time, representative of different lunar surface exploration missions. The bread-board has shown a good performance during the test campaign, even if some failures of the Membrane Electrode Assemblies have been observed. The study has demonstrated the high performance of the developed stack and the potential of fuel cell technology for use in future human lunar exploration missions. At the same time, it has highlighted serious criticalities related to the reliability and robustness of the commercially available Membrane Electrode Assemblies, which need to be investigated further, before the use of this technology in a real space exploration mission can be possible.

Design and experimental validation of an HT-PEFC stack with metallic BPP

This paper provides detailed insight into the design, construction, production and verification of a metallic bipolar plate for High Temperature Polymer Electrolyte Fuel Cell stacks. With a focusing on applications with power demands of 5–10 kW, the active cell area is set to a maximum of 100 cm2. The double-plate-concept allows for liquid cooling in the inner bipolar plate compartment. Due to the bipolar plate production by hydroforming of thin stainless steel foils the structure of the coolant compartment is dependent on the gas flow field design. To ensure proper cooling functionality a co-design is necessary. The flow field design, in conjunction with the flow configuration of the reactants (reformate, air) and coolant, considers the effects of hydrogen and oxygen depletion on current density distribution, as well as the temperature profile on carbon monoxide poisoning. These specifications are based on previously published results. For validation, a 5-cell stack with commercial Membrane Electrode Assemblies was operated at 160 °C and 0.2 A/cm2 and regularly interrupted for the polarization curve measurement. After 4700 h of continuous operation, the test was terminated due to a rapid voltage drop in one of the cells. In this paper, it is shown that novel metallic bipolar plates from thin metal sheets can be used for the long-term operation of High Temperature Polymer Electrolyte Fuel Cell stacks.

Assessment of the durability of low-cost Al bipolar plates for High Temperature PEM fuel cells

Abstract The present research aims to assess the durability of a single cell formed by a commercial high-temperature membrane electrode assembly (MEA) and Al bipolar plates (Al-BPPs) coated with Ni-P. To this end, an accelerated degradation test based on voltage load cycles is carried out, and the effects of the degradation on the MEA and its impact on the Al-coated bipolar plates are analyzed. They are compared with the results obtained testing a similar cell formed by the same MEA with graphite plates. MEAs from both cells were analyzed by different characterization techniques before and after the degradation tests (XRD, SEM, TEM). The performance of the Al-based cell is initially better, but it suffers a faster deterioration mainly due to the degradation of the Ni-P surface coating. A green deposit is formed, probably due to the chemical reaction of the phosphoric acid leached from the MEA. These deposits cause an increase in the contact resistance of the plates, local channel blockages and, eventually, a larger degradation. This work proves that PBI membranes still need to be improved to ensure their long-term durability.

A practical low-cost approach to build membrane electrode assemblies using decal transfer technique

Membrane electrode assembly (MEA) is the heart of a proton exchange membrane (PEM) fuel cell. In this paper, a practical and low-cost approach to build membrane electrode assemblies in lab using decal transfer technique is described and verified. The procedure is based on current literatures but using different materials for convenience and cost-saving. All devices and tools used are easy to find in normal labs and all materials used are affordable and easy to obtain from market. Two Membrane electrode assemblies are built and tested using a PEM fuel cell test and control system. Two MEAs showed voltages of about 0.82V and 0.70V respectively, measured with a digital multimeter, which are lower than that of the commercial MEA. It is found that the unscratched MEA with more catalyst has a lower voltage, but can generate higher current density and much water. Some water oozed through the bipolar plates which usually is not seen in a single cell test

Durable MEA with Functionalized Catalysts for PEMFC and Its Development Status for Automotive Application

Their is significantly growing interests in a polymer electrolyte membrane fuel cell (PEMFC)as a promising alternative electric power generation system for stationary, backup power, and automotive applications because of high power density, low operating temperature, and reduced release of environmental pollutants relative to converntional energy conversion and storage devices [1]. In this regard, a high level of activities in materials science and engineering research for the PEMFC have been made to realize its potential applications as the advanced sustainable energy sourcecs.For realizing the widespread commercialization of the PEMFC, there are still technical hurdles including high cost, performance loss, and insufficient durability with long-term cycles [2]. Especially in automotive condition, startup/shutdown and load-cycling cause a significant degradation of Pt nanoparticles supported on high surface area carbon. Although several types of Pt-based catalysts with enhanced catalytic activity and/or durability have emerged, they are still in development [3]. Therefore,it is still of great importance to develop efficient electro-catalysts with enhancing stability as well as sustaining catalytic acitvity under the wide ranges of operating conditions.The development of a functional carbon supported Pt catalyst that has both high oxygen reduction activity and high durability would significantly contribute to the commercialization of automotive PEMFC. Herein we report a diazonium-functionalized graphitized carbon (DFGC) support prepared by grafting different types of end-functional groups on a GC support via simple diazonium chemistry that can improve the dispersion of Pt nanoparticles and reduce their sintering phenomena, resulting in higher electrochemical durability with enhanced catalytic activity as compared to the unmodified GC support. The membrane-electrode assembly (MEA) fabricated with the Pt/DFGC series as the cathode catalysts shows a power density higher than 1.0 W/cm2 under an automotivce operating condition at a low catalyst loading of 0.25 mgPt/cm2. The durability of the MEA was measured by electrocatalyst cycling and catalytst support cycling tests according to the procedures of DOE-FCTT accelerated stress test (AST) protocols. THe AST results reveal that the MEA series with the Pt/DFGC catalysts exhibit higher durability event at 30% lower catalyst loading compared to a commercial MEA. These results demonstrate that the catalyst design strategy based on simple diazonium chemistry is an effective way to fabricate highly durable catalysts with enhanced catalytic activity for the PEMFC, providing a design guide of a high performance MEA for automotive applications.We also present current development status of our developed MEA for automotive applications. Our research and development focus on the fabrication of a cost-competitive MEA with high power performance and longer durability even at lower Pt amount for automotive PEMFC systems. To achieve these goals, a high level of activities have been made to develop the MEA design for high temperature and low humidified operation including the design of highly active catalyst layer, the functionalization of polymer electrolyte membrane and interfaces in the MEA, and cost-effective manufacturing process. The development of a cost-competitive MEA with high power output, long durability, and operation flexibility is expected to contribute the widespread commercialization of automotive PEMFC systems. Further development of the MEA for automotive applications would be performed by balancing high performance against long-term durability and manufacturing cost.

Performance of an Active Micro Direct Methanol Fuel Cell Using Reduced Catalyst Loading MEAs

The micro direct methanol fuel cell (MicroDMFC) is an emergent technology due to its special interest for portable applications. This work presents the results of a set of experiments conducted at room temperature using an active metallic MicroDMFC with an active area of 2.25 cm2. The MicroDMFC uses available commercial materials with low platinum content in order to reduce the overall fuel cell cost. The main goal of this work is to provide useful information to easily design an active MicroDMFC with a good performance recurring to cheaper commercial Membrane Electrode Assemblies MEAs. A performance/cost analysis for each MEA tested is provided. The maximum power output obtained was 18.1 mW/cm2 for a hot-pressed MEA with materials purchased from Quintech with very low catalyst loading (3 mg/cm2 Pt–Ru at anode side and 0.5 mg/cm2 PtB at the cathode side) costing around 15 euros. Similar power values are reported in literature for the same type of micro fuel cells working at higher operating temperatures and substantially higher cathode catalyst loadings. Experimental studies using metallic active micro direct methanol fuel cells operating at room temperature are very scarce. The results presented in this work are, therefore, very useful for the scientific community.

On the Experimental Investigation of the Clamping Pressure Effects on the Proton Exchange Membrane Water Electrolyser Cell Performance

Recently, research on Proton Exchange Membrane Water Electrolysis (PEMWE) has inched towards operating conditions, such as: increased operating temperature and cathode-anode high differential pressure operation, flow field design, stack development, and numerical modeling. In this work, the effect of clamping pressure (Pc) on the PEMWE cell performance is studied. A 50 cm2 active area PEMWE cell with double serpentine flow field channels for anode and cathode with a commercial membrane electrode assembly (MEA) consisting of 3 mg.cm-2 Iridium Ruthenium Oxide and 3 mg.cm-2 Platinum Black on the anode and cathode side, respectively, deposited on Nafion® 115 membrane is utilized in this study. The IV curves and the electrochemical impedance spectroscopy (EIS) are measured at different clamping pressures. The PEMWE cell performance increases with increasing the clamping pressure. This can be elucidated by the EIS measurements, which predict an increment in ohmic and activation resistance at lower clamping pressure.

Innovative anode catalyst designed to reduce the degradation in ozone generation via PEM water electrolysis

Abstract Membrane electrode assemblies (MEAs) using commercial PbO 2 powder as the anode catalyst to generate ozone via water electrolysis were traditionally adopted. We found that commercial MEAs evinced the typical degradation phenomenon after a current interruption and restart during operation, where the performance degraded and partially recovered after the resumption of current. In this study, homemade MEAs using PbO 2 powder and additives were developed, which ameliorated the degradation phenomenon. SEM and XRD analysis were used to compare the anode structure of the homemade to commercial MEAs after short–and long–term operation post–resumption of current after an interruption.