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Sample records for proton-exchange membrane fuel

  1. Proton Exchange Membranes for Fuel Cells

    SciTech Connect

    Devanathan, Ramaswami

    2010-11-01

    Proton exchange membrane, also known as polymer electrolyte membrane, fuel cells (PEMFCs) offer the promise of efficient conversion of chemical energy of fuel, such as hydrogen or methanol, into electricity with minimal pollution. Their widespread use to power zero-emission automobiles as part of a hydrogen economy can contribute to enhanced energy security and reduction in greenhouse gas emissions. However, the commercial viability of PEMFC technology is hindered by high cost associated with the membrane electrode assembly (MEA) and poor membrane durability under prolonged operation at elevated temperature. Membranes for automotive fuel cell applications need to perform well over a period comparable to the life of an automotive engine and under heavy load cycling including start-stop cycling under sub-freezing conditions. The combination of elevated temperature, changes in humidity levels, physical stresses and harsh chemical environment contribute to membrane degradation. Perfluorinated sulfonic acid (PFSA)-based membranes, such as Nafion®, have been the mainstay of PEMFC technology. Their limitations, in terms of cost and poor conductivity at low hydration, have led to continuing research into membranes that have good proton conductivity at elevated temperatures above 120 °C and under low humidity conditions. Such membranes have the potential to avoid catalyst poisoning, simplify fuel cell design and reduce the cost of fuel cells. Hydrocarbon-based membranes are being developed as alternatives to PFSA membranes, but concerns about chemical and mechanical stability and durability remain. Novel anhydrous membranes based on polymer gels infused with protic ionic liquids have also been recently proposed, but considerable fundamental research is needed to understand proton transport in novel membranes and evaluate durability under fuel cell operating conditions. In order to advance this promising technology, it is essential to rationally design the next generation

  2. Electronic circuit model for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Yu, Dachuan; Yuvarajan, S.

    The proton exchange membrane (PEM) fuel cell is being investigated as an alternate power source for various applications like transportation and emergency power supplies. The paper presents a novel circuit model for a PEM fuel cell that can be used to design and analyze fuel cell power systems. The PSPICE-based model uses bipolar junction transistors (BJTs) and LC elements available in the PSPICE library with some modification. The model includes the phenomena like activation polarization, ohmic polarization, and mass transport effect present in a PEM fuel cell. The static and dynamic characteristics obtained through simulation are compared with experimental results obtained on a commercial fuel cell module.

  3. Proton exchange membrane fuel cell technology for transportation applications

    SciTech Connect

    Swathirajan, S.

    1996-04-01

    Proton Exchange Membrane (PEM) fuel cells are extremely promising as future power plants in the transportation sector to achieve an increase in energy efficiency and eliminate environmental pollution due to vehicles. GM is currently involved in a multiphase program with the US Department of Energy for developing a proof-of-concept hybrid vehicle based on a PEM fuel cell power plant and a methanol fuel processor. Other participants in the program are Los Alamos National Labs, Dow Chemical Co., Ballard Power Systems and DuPont Co., In the just completed phase 1 of the program, a 10 kW PEM fuel cell power plant was built and tested to demonstrate the feasibility of integrating a methanol fuel processor with a PEM fuel cell stack. However, the fuel cell power plant must overcome stiff technical and economic challenges before it can be commercialized for light duty vehicle applications. Progress achieved in phase I on the use of monolithic catalyst reactors in the fuel processor, managing CO impurity in the fuel cell stack, low-cost electrode-membrane assembles, and on the integration of the fuel processor with a Ballard PEM fuel cell stack will be presented.

  4. Percolation in a Proton Exchange Membrane Fuel Cell Catalyst Layer

    SciTech Connect

    Stacy, Stephen; Allen, Jeffrey

    2012-07-01

    Water management in the catalyst layers of proton exchange membrane fuel cells (PEMFC) is confronted by two issues, flooding and dry out, both of which result in improper functioning of the fuel cell and lead to poor performance and degradation. At the present time, the data that has been reported about water percolation and wettability within a fuel cell catalyst layer is limited. A method and apparatus for measuring the percolation pressure in the catalyst layer has been developed based upon an experimental apparatus used to test water percolation in porous transport layers (PTL). The experimental setup uses a pseudo Hele-Shaw type testing where samples are compressed and a fluid is injected into the sample. Testing the samples gives percolation pressure plots which show trends in increasing percolation pressure with an increase in flow rate. A decrease in pressure was seen as percolation occurred in one sample, however the pressure only had a rising effect in the other sample.

  5. Physical Chemistry Research Toward Proton Exchange Membrane Fuel Cell Advancement.

    PubMed

    Swider-Lyons, Karen E; Campbell, Stephen A

    2013-02-07

    Hydrogen fuel cells, the most common type of which are proton exchange membrane fuel cells (PEMFCs), are on a rapid path to commercialization. We credit physical chemistry research in oxygen reduction electrocatalysis and theory with significant breakthroughs, enabling more cost-effective fuel cells. However, most of the physical chemistry has been restricted to studies of platinum and related alloys. More work is needed to better understand electrocatalysts generally in terms of properties and characterization. While the advent of such highly active catalysts will enable smaller, less expensive, and more powerful stacks, they will require better understanding and a complete restructuring of the diffusion media in PEMFCs to facilitate faster transport of the reactants (O2) and products (H2O). Even Ohmic losses between materials become more important at high power. Such lessons from PEMFC research are relevant to other electrochemical conversion systems, including Li-air batteries and flow batteries.

  6. A Novel Unitized Regenerative Proton Exchange Membrane Fuel Cell

    NASA Technical Reports Server (NTRS)

    Murphy, O. J.; Cisar, A. J.; Gonzalez-Martin, A.; Salinas, C. E.; Simpson, S. F.

    1996-01-01

    A difficulty encountered in designing a unitized regenerative proton exchange membrane (PEM) fuel cell lies in the incompatibility of electrode structures and electrocatalyst materials optimized for either of the two functions (fuel cell or electrolyzer) with the needs of the other function. This difficulty is compounded in previous regenerative fuel cell designs by the fact that water, which is needed for proton conduction in the PEM during both modes of operation, is the reactant supplied to the anode in the electrolyzer mode of operation and the product formed at the cathode in the fuel cell mode. Drawbacks associated with existing regenerative fuel cells have been addressed. In a first innovation, electrodes function either as oxidation electrodes (hydrogen ionization or oxygen evolution) or as reduction electrodes (oxygen reduction or hydrogen evolution) in the fuel cell and electrolyzer modes, respectively. Control of liquid water within the regenerative fuel cell has been brought about by a second innovation. A novel PEM has been developed with internal channels that permit the direct access of water along the length of the membrane. Lateral diffusion of water along the polymer chains of the PEM provides the water needed at electrode/PEM interfaces. Fabrication of the novel single cell unitized regenerative fuel cell and results obtained on testing it are presented.

  7. A novel unitized regenerative proton exchange membrane fuel cell

    NASA Technical Reports Server (NTRS)

    Murphy, O. J.; Cisar, A. J.; Gonzalez-Martin, A.; Salinas, C. E.; Simpson, S. F.

    1995-01-01

    A difficulty encountered in designing a unitized regenerative proton exchange membrane (PEM) fuel cell lies in the incompatibility of electrode structures and electrocatalyst materials optimized for either of the two functions (fuel cell or electrolyzer) with the needs of the other function. This difficulty is compounded in previous regenerative fuel cell designs by the fact that water, which is needed for proton conduction in the PEM during both modes of operation, is the reactant supplied to the anode in the electrolyzer mode of operation and the product formed at the cathode in the fuel cell mode. Drawbacks associated with existing regenerative fuel cells have been addressed in work performed at Lynntech. In a first innovation, electrodes function either as oxidation electrodes (hydrogen ionization or oxygen evolution) or as reduction electrodes (oxygen reduction or hydrogen evolution) in the fuel cell and electrolyzer modes, respectively. Control of liquid water within the regenerative fuel cell has been brought about by a second innovation. A novel PEM has been developed with internal channels that permit the direct access of water along the length of the membrane. Lateral diffusion of water along the polymer chains of the PEM provides the water needed at electrode/PEM interfaces. Fabrication of the novel unitized regenerative fuel cell and results obtained on testing it will be presented.

  8. A Novel Unitized Regenerative Proton Exchange Membrane Fuel Cell

    NASA Technical Reports Server (NTRS)

    Murphy, O. J.; Cisar, A. J.; Gonzalez-Martin, A.; Salinas, C. E.; Simpson, S. F.

    1996-01-01

    A difficulty encountered in designing a unitized regenerative proton exchange membrane (PEM) fuel cell lies in the incompatibility of electrode structures and electrocatalyst materials optimized for either of the two functions (fuel cell or electrolyzer) with the needs of the other function. This difficulty is compounded in previous regenerative fuel cell designs by the fact that water, which is needed for proton conduction in the PEM during both modes of operation, is the reactant supplied to the anode in the electrolyzer mode of operation and the product formed at the cathode in the fuel cell mode. Drawbacks associated with existing regenerative fuel cells have been addressed. In a first innovation, electrodes function either as oxidation electrodes (hydrogen ionization or oxygen evolution) or as reduction electrodes (oxygen reduction or hydrogen evolution) in the fuel cell and electrolyzer modes, respectively. Control of liquid water within the regenerative fuel cell has been brought about by a second innovation. A novel PEM has been developed with internal channels that permit the direct access of water along the length of the membrane. Lateral diffusion of water along the polymer chains of the PEM provides the water needed at electrode/PEM interfaces. Fabrication of the novel single cell unitized regenerative fuel cell and results obtained on testing it are presented.

  9. A novel unitized regenerative proton exchange membrane fuel cell

    NASA Technical Reports Server (NTRS)

    Murphy, O. J.; Cisar, A. J.; Gonzalez-Martin, A.; Salinas, C. E.; Simpson, S. F.

    1995-01-01

    A difficulty encountered in designing a unitized regenerative proton exchange membrane (PEM) fuel cell lies in the incompatibility of electrode structures and electrocatalyst materials optimized for either of the two functions (fuel cell or electrolyzer) with the needs of the other function. This difficulty is compounded in previous regenerative fuel cell designs by the fact that water, which is needed for proton conduction in the PEM during both modes of operation, is the reactant supplied to the anode in the electrolyzer mode of operation and the product formed at the cathode in the fuel cell mode. Drawbacks associated with existing regenerative fuel cells have been addressed in work performed at Lynntech. In a first innovation, electrodes function either as oxidation electrodes (hydrogen ionization or oxygen evolution) or as reduction electrodes (oxygen reduction or hydrogen evolution) in the fuel cell and electrolyzer modes, respectively. Control of liquid water within the regenerative fuel cell has been brought about by a second innovation. A novel PEM has been developed with internal channels that permit the direct access of water along the length of the membrane. Lateral diffusion of water along the polymer chains of the PEM provides the water needed at electrode/PEM interfaces. Fabrication of the novel unitized regenerative fuel cell and results obtained on testing it will be presented.

  10. Gold Nanoparticles-Enhanced Proton Exchange Membrane (PEM) Fuel Cell

    NASA Astrophysics Data System (ADS)

    Li, Hongfei; Pan, Cheng; Liu, Ping; Zhu, Yimei; Adzic, Radoslav; Rafailovich, Miriam

    Proton exchange membrane fuel cells have drawn great attention and been taken as a promising alternated energy source. One of the reasons hamper the wider application of PEM fuel cell is the catalytic poison effect from the impurity of the gas flow. Haruta has predicted that gold nanoparticles that are platelet shaped and have direct contact with the metal oxide substrate to be the perfect catalysts of the CO oxidization, yet the synthesis method is difficult to apply in the Fuel Cell. In our approach, thiol-functionalized gold nanoparticles were synthesized through two-phase method developed by Brust et al. We deposit these Au particles with stepped surface directly onto the Nafion membrane in the PEM fuel cell by Langmuir-Blodgett method, resulting in over 50% enhancement of the efficiency of the fuel cell. DFT calculations were conducted to understand the theory of this kind of enhancement. The results indicated that only when the particles were in direct surface contact with the membrane, where AuNPs attached at the end of the Nafion side chains, it could reduce the energy barrier for the CO oxidation that could happen at T<300K.

  11. Analysis performance of proton exchange membrane fuel cell (PEMFC)

    NASA Astrophysics Data System (ADS)

    Mubin, A. N. A.; Bahrom, M. H.; Azri, M.; Ibrahim, Z.; Rahim, N. A.; Raihan, S. R. S.

    2017-06-01

    Recently, the proton exchange membrane fuel cell (PEMFC) has gained much attention to the technology of renewable energy due to its mechanically ideal and zero emission power source. PEMFC performance reflects from the surroundings such as temperature and pressure. This paper presents an analysis of the performance of the PEMFC by developing the mathematical thermodynamic modelling using Matlab/Simulink. Apart from that, the differential equation of the thermodynamic model of the PEMFC is used to explain the contribution of heat to the performance of the output voltage of the PEMFC. On the other hand, the partial pressure equation of the hydrogen is included in the PEMFC mathematical modeling to study the PEMFC voltage behaviour related to the input variable input hydrogen pressure. The efficiency of the model is 33.8% which calculated by applying the energy conversion device equations on the thermal efficiency. PEMFC’s voltage output performance is increased by increasing the hydrogen input pressure and temperature.

  12. Optimal microporous layer for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Yan, Wei-Mon; Wu, Dong-Kai; Wang, Xiao-Dong; Ong, Ai-Lien; Lee, Duu-Jong; Su, Ay

    This study elucidates how fabrication processes (screen-printing and spraying) and constituent materials (carbon paper as backing, Acetylene Black (AB) carbon (42 nm), XC-72R carbon (30 nm) or BP2000 (15 nm) as carbon powders, and 10-50% fluorinated ethylene propylene (FEP) as hydrophobic substances) for microporous layers (MPLs) affect the performance of proton exchange membrane fuel cells. The screen-printing process produces MPLs with smaller surface fractures than does the spraying process. The effect of optimal FEP content on cell performance is noted. The presence of an optimal FEP content is due to the counterbalance between enhanced performance produced with increased gas permeability and decreased performance yielded with small contact area and electrical conductivity with excess FEP. The MPL with large carbon powders is preferred when oxygen supply is limited; otherwise, small carbon powders should be utilized. Optimal MPL design should address negative effects possibly associated with contact resistance, gas permeation resistance, and excess water resistance.

  13. Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Belieres, Jean-Philippe

    2004-01-01

    There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research

  14. Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Belieres, Jean-Philippe

    2004-01-01

    There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research

  15. Fault tolerance control for proton exchange membrane fuel cell systems

    NASA Astrophysics Data System (ADS)

    Wu, Xiaojuan; Zhou, Boyang

    2016-08-01

    Fault diagnosis and controller design are two important aspects to improve proton exchange membrane fuel cell (PEMFC) system durability. However, the two tasks are often separately performed. For example, many pressure and voltage controllers have been successfully built. However, these controllers are designed based on the normal operation of PEMFC. When PEMFC faces problems such as flooding or membrane drying, a controller with a specific design must be used. This paper proposes a unique scheme that simultaneously performs fault diagnosis and tolerance control for the PEMFC system. The proposed control strategy consists of a fault diagnosis, a reconfiguration mechanism and adjustable controllers. Using a back-propagation neural network, a model-based fault detection method is employed to detect the PEMFC current fault type (flooding, membrane drying or normal). According to the diagnosis results, the reconfiguration mechanism determines which backup controllers to be selected. Three nonlinear controllers based on feedback linearization approaches are respectively built to adjust the voltage and pressure difference in the case of normal, membrane drying and flooding conditions. The simulation results illustrate that the proposed fault tolerance control strategy can track the voltage and keep the pressure difference at desired levels in faulty conditions.

  16. High power density proton exchange membrane fuel cells

    NASA Technical Reports Server (NTRS)

    Murphy, Oliver J.; Hitchens, G. Duncan; Manko, David J.

    1993-01-01

    Proton exchange membrane (PEM) fuel cells use a perfluorosulfonic acid solid polymer film as an electrolyte which simplifies water and electrolyte management. Their thin electrolyte layers give efficient systems of low weight, and their materials of construction show extremely long laboratory lifetimes. Their high reliability and their suitability for use in a microgravity environment makes them particularly attractive as a substitute for batteries in satellites utilizing high-power, high energy-density electrochemical energy storage systems. In this investigation, the Dow experimental PEM (XUS-13204.10) and unsupported high platinum loading electrodes yielded very high power densities, of the order of 2.5 W cm(exp -2). A platinum black loading of 5 mg per cm(exp 2) was found to be optimum. On extending the three-dimensional reaction zone of fuel cell electrodes by impregnating solid polymer electrolyte into the electrode structures, Nafion was found to give better performance than the Dow experimental PEM. The depth of penetration of the solid polymer electrolyte into electrode structures was 50-70 percent of the thickness of the platinum-catalyzed active layer. However, the degree of platinum utilization was only 16.6 percent and the roughness factor of a typical electrode was 274.

  17. Spatial proton exchange membrane fuel cell performance under bromomethane poisoning

    NASA Astrophysics Data System (ADS)

    Reshetenko, Tatyana V.; Artyushkova, Kateryna; St-Pierre, Jean

    2017-02-01

    The poisoning effects of 5 ppm CH3Br in the air on the spatial performance of a proton exchange membrane fuel cell (PEMFC) were studied using a segmented cell system. The presence of CH3Br caused performance loss from 0.650 to 0.335 V at 1 A cm-2 accompanied by local current density redistribution. The observed behavior was explained by possible bromomethane hydrolysis with the formation of Br-. Bromide and bromomethane negatively affected the oxygen reduction efficiency over a wide range of potentials because of their adsorption on Pt, which was confirmed by XPS. Moreover, the PEMFC exposure to CH3Br led to a decrease in the anode and cathode electrochemical surface area (∼52-57%) due to the growth of Pt particles through agglomeration and Ostwald ripening. The PEMFC did not restore its performance after stopping bromomethane introduction to the air stream. However, the H2/N2 purge of the anode/cathode and CV scans almost completely recovered the cell performance. The observed final loss of ∼50 mV was due to an increased activation overpotential. PEMFC exposure to CH3Br should be limited to concentrations much less than 5 ppm due to serious performance loss and lack of self-recovery.

  18. Numerical modeling transport phenomena in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Suh, DongMyung

    To study the coupled phenomena occurring in proton exchange membrane fuel cells, a two-phase, one-dimensional, non-isothermal model is developed in the chapter 1. The model includes water phase change, proton transport in the membrane and electro-osmotic effect. The thinnest, but most complex layer in the membrane electrode assembly, catalyst layer, is considered an interfacial boundary between the gas diffusion layer and the membrane. Mass and heat transfer and electro-chemical reaction through the catalyst layer are formulated into equations, which are applied to boundary conditions for the gas diffusion layer and the membrane. Detail accounts of the boundary equations and the numerical solving procedure used in this work are given. The polarization curve is calculated at different oxygen pressures and compared with the experimental results. When the operating condition is changed along the polarization curve, the change of physicochemical variables in the membrane electrode assembly is studied. In particular, the over-potential diagram presents the usage of the electrochemical energy at each layer of the membrane electrode assembly. Humidity in supplying gases is one of the most important factors to consider for improving the performance of PEMFE. Both high and low humidity conditions can result in a deteriorating cell performance. The effect of humidity on the cell performance is studied in the chapter 2. First, a numerical model based on computational fluid dynamics is developed. Second, the cell performances are simulated, when the relative humidity is changed from 0% to 100% in the anode and the cathode channel. The simulation results show how humidity in the reactant gases affects the water content distribution in the membrane, the over-potential at the catalyst layers and eventually the cell performance. In particular, the rapid enhancement in the cell performance caused by self-hydrating membrane is captured by the simulation. Fully humidifying either H2

  19. High temperature polymers for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Einsla, Brian Russel

    Novel proton exchange membranes (PEMs) were investigated that show potential for operating at higher temperatures in both direct methanol (DMFC) and H 2/air PEM fuel cells. The need for thermally stable polymers immediately suggests the possibility of heterocyclic polymers bearing appropriate ion conducting sites. Accordingly, monomers and random disulfonated poly(arylene ether) copolymers containing either naphthalimide, benzoxazole or benzimidazole moieties were synthesized via direct copolymerization. The ion exchange capacity (IEC) was varied by simply changing the ratio of disulfonated monomer to nonsulfonated monomer in the copolymerization step. Water uptake and proton conductivity of cast membranes increased with IEC. The water uptake of these heterocyclic copolymers was lower than that of comparable disulfonated poly(arylene ether) systems, which is a desirable improvement for PEMs. Membrane electrode assemblies were prepared and the initial fuel cell performance of the disulfonated polyimide and polybenzoxazole (PBO) copolymers was very promising at 80°C compared to the state-of-the-art PEM (NafionRTM); nevertheless these membranes became brittle under operating conditions. Several series of poly(arylene ether)s based on disodium-3,3'-disulfonate-4,4 '-dichlorodiphenylsulfone (S-DCDPS) and a benzimidazole-containing bisphenol were synthesized and afforded copolymers with enhanced stability. Selected properties of these membranes were compared to separately prepared miscible blends of disulfonated poly(arylene ether sulfone) copolymers and polybenzimidazole (PBI). Complexation of the sulfonic acid groups with the PBI structure reduced water swelling and proton conductivity. The enhanced proton conductivity of NafionRTM membranes has been proposed to be due to the aggregation of the highly acidic side-chain sulfonic acid sites to form ion channels. A series of side-chain sulfonated poly(arylene ether sulfone) copolymers based on methoxyhydroquinone was

  20. Proton exchange membrane fuel cell conductivity and system analysis

    NASA Astrophysics Data System (ADS)

    Han, Qian

    A fuel cell converts chemical energy to electrical energy. It is a device that uses the electrochemical reaction of hydrogen and an oxidant, to produce electrical energy silently, without combustion. The role of the electrolyte in a PEM fuel cell is played by a proton exchange membrane. NafionRTM and its derivatives are the most widely used and studied polymers. Percolation theory holds a key to understanding the behavior of these polymers. In this dissertation, the percolation phenomenon was first simulated for the thermal conductivity of a representative polymer material. The simulation program was based on the finite element method, using Ansys software, which not only simplifies the method of calculation, but also increases the accuracy of the result. Ansys programs were developed to study the effects of matrix thickness, filler particle volume percentage, and various conductivities of the base material and filler particles. Comparison with existing experimental results and other models showed that the results from the finite element method were more accurate than the other models, especially the three-dimensional model. A similar Ansys program was utilized to predict the percolation threshold for the polymer electric conductivity, and its relationship with extra water content over the studied temperature range. The result showed that the percolation threshold varied with temperature and is in the range of 22% to 26% at room temperature, and matches the experimental data within 10% error margin. A natural gas fuel cell (NGFC) is a direct-energy conversion system which uses natural gas as the hydrogen carrier. A parametric model was developed to predict the overall system performance of a natural-gas-fueled PEM fuel cell system sized for a residential or small commercial building. The model accounts for interactions between various operating parameters: fuel consumption, air and water requirements, power produced, and heat and waste water discharge. For example

  1. Durability of sulfonated aromatic polymers for proton-exchange-membrane fuel cells.

    PubMed

    Hou, Hongying; Di Vona, Maria Luisa; Knauth, Philippe

    2011-11-18

    As a key component of proton-exchange-membrane fuel cells (PEMFCs), proton-exchange membranes (PEMs) must continuously withstand very harsh environments during long-term fuel cell operations. With the coming commercialization of PEMFCs, investigations into the durability and degradation of PEMs are becoming more and more urgent and interesting. Herein, various recent attempts and achievements to improve the durability of sulfonated aromatic polymers (SAPs) are reviewed and some further developments are predicted. Extensive investigations into inexpensive SAPs as alternative electrolyte membranes include modification of available polymer materials; design, synthesis, and optimization of new macromolecules; durability testing; and exploring the degradation mechanisms.

  2. Durability of symmetrically and asymmetrically porous polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Jheng, Li-Cheng; Chang, Wesley Jen-Yang; Hsu, Steve Lien-Chung; Cheng, Po-Yang

    2016-08-01

    Two types of porous polybenzimidazole (PBI) membranes with symmetric and asymmetric morphologies were fabricated by the template-leaching method and characterized by scanning electron microscope (SEM). Their physicochemical properties were compared in terms of acid-doping level, proton conductivity, mechanical strength, and oxidative stability. The durability of fuel cell operation is one of the most challenging for the PBI based membrane electrode assembly (MEA) used in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). In the present work, we carried out a long-term steady-state fuel cell test to compare the effect of membrane structure on the cell voltage degradation. It has also been demonstrated that the asymmetrically porous PBI could bring some notable improvements on the durability of fuel cell operation, the fuel crossover problem, and the phosphoric acid leakage.

  3. The application of Dow Chemical's perfluorinated membranes in proton-exchange membrane fuel cells

    NASA Technical Reports Server (NTRS)

    Eisman, G. A.

    1989-01-01

    Dow Chemical's research activities in fuel cell devices revolves around the development and subsequent investigation of the perfluorinated inomeric membrane separator useful in proton-exchange membrane systems. Work is currently focusing on studying the effects of equivalent weight, thickness, water of hydration, pretreatment procedures, as well as the degree of water management required for a given membrane separator in the cell. The presentation will include details of certain aspects of the above as well as some of the requirements for high and low power generation.

  4. The application of Dow Chemical's perfluorinated membranes in proton-exchange membrane fuel cells

    NASA Technical Reports Server (NTRS)

    Eisman, G. A.

    1989-01-01

    Dow Chemical's research activities in fuel cells revolve around the development of perfluorosulfonic acid membranes useful as the proton transport medium and separator. Some of the performance characteristics which are typical for such membranes are outlined. The results of tests utilizing a new experimental membrane useful in proton-exchange membrane fuel cells are presented. The high voltage at low current densities can lead to higher system efficiencies while, at the same time, not sacrificing other critical properties pertinent to membrane fuel cell operation. A series of tests to determine response times indicated that on-off cycles are on the order of 80 milliseconds to reach 90 percent of full power. The IR free voltage at 100 amps/sq ft was determined and the results indicating a membrane/electrode package resistance to be .15 ohm-sq cm at 100 amps/sq ft.

  5. Proton exchange membrane fuel cells with chromium nitridenanocrystals as electrocatalysts

    SciTech Connect

    Zhong, Hexiang; Chen, Xiaobo; Zhang, Huamin; Wang, Meiri; Mao,Samuel S.

    2007-07-01

    Polymer electrolyte membrane fuel cells (PEMFCs) are energy conversion devices that produce electricity from a supply of fuel, such as hydrogen. One of the major challenges in achieving efficient energy conversion is the development of cost-effective materials that can act as electrocatalysts for PEMFCs. In this letter, we demonstrate that, instead of conventional noble metals, such as platinum, chromium nitride nanocrystals of fcc structure exhibit attractive catalytic activity for PEMFCs. Device testing indicates good stability of nitride nanocrystals in low temperature fuel cell operational environment.

  6. Hydrocarbon-based polymer electrolyte cerium composite membranes for improved proton exchange membrane fuel cell durability

    NASA Astrophysics Data System (ADS)

    Lee, Hyejin; Han, Myungseong; Choi, Young-Woo; Bae, Byungchan

    2015-11-01

    Hydrocarbon-based cerium composite membranes were prepared for proton exchange membrane fuel cell applications to increase oxidative stability. Different amounts of cerium ions were impregnated in sulfonated poly(arylene ether sulfone) (SPES) membranes and their physicochemical properties were investigated according to the cerium content. Field-emission scanning electron microscopy and inductively coupled plasma analyses confirmed the presence of cerium ions in the composite membranes and 1H NMR indicated the successful coordination of sulfonic acid groups with the metal ions. Increasing amounts of cerium ions resulted in decreases in the proton conductivity and water uptake, but enhanced oxidative stability. The oxidative stability of the composite membranes was proven via a hydrogen peroxide exposure experiment which mimicked fuel cell operating conditions. In addition, more than 2200 h was achieved with the composite membrane under in situ accelerated open circuit voltage (OCV) durability testing (DOE protocol), whereas the corresponding pristine SPES membrane attained only 670 h.

  7. Nonhumidified High-Temperature Membranes Developed for Proton Exchange Membrane Fuel Cells

    NASA Technical Reports Server (NTRS)

    Kinder, James D.

    2005-01-01

    Fuel cells are being considered for a wide variety of aerospace applications. One of the most versatile types of fuel cells is the proton-exchange-membrane (PEM) fuel cell. PEM fuel cells can be easily scaled to meet the power and space requirements of a specific application. For example, small 100-W PEM fuel cells are being considered for personal power for extravehicular activity suit applications, whereas larger PEM fuel cells are being designed for primary power in airplanes and in uninhabited air vehicles. Typically, PEM fuel cells operate at temperatures up to 80 C. To increase the efficiency and power density of the fuel cell system, researchers are pursuing methods to extend the operating temperature of the PEM fuel cell to 180 C. The most widely used membranes in PEM fuel cells are Nafion 112 and Nafion 117--sulfonated perfluorinated polyethers that were developed by DuPont. In addition to their relatively high cost, the properties of these membranes limit their use in a PEM fuel cell to around 80 C. The proton conductivity of Nafion membranes significantly decreases above 80 C because the membrane dehydrates. The useful operating range of Nafion-based PEM fuel cells can be extended to over 100 C if ancillary equipment, such as compressors and humidifiers, is added to maintain moisture levels within the membrane. However, the addition of these components reduces the power density and increases the complexity of the fuel cell system.

  8. Polymers application in proton exchange membranes for fuel cells (PEMFCs)

    NASA Astrophysics Data System (ADS)

    Walkowiak-Kulikowska, Justyna; Wolska, Joanna; Koroniak, Henryk

    2017-07-01

    This review presents the most important research on alternative polymer membranes with ionic groups attached, provides examples of materials with a well-defined chemical structure that are described in the literature. Furthermore, it elaborates on the synthetic methods used for preparing PEMs, the current status of fuel cell technology and its application. It also briefly discusses the development of the PEMFC market.

  9. Impedance study of membrane dehydration and compression in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Le Canut, Jean-Marc; Latham, Ruth; Mérida, Walter; Harrington, David A.

    Electrochemical impedance spectroscopy (EIS) is used to measure drying and rehydration in proton exchange membrane fuel cells running under load. The hysteresis between forward and backward acquisition of polarization curves is shown to be largely due to changes in the membrane resistance. Drying tests are carried out with hydrogen and simulated reformate (hydrogen and carbon dioxide), and quasi-periodic drying and rehydration conditions are studied. The membrane hydration state is clearly linked to the high-frequency arc in the impedance spectrum, which increases in size for dry conditions indicating an increase in membrane resistance. Changes in impedance spectra as external compression is applied to the cell assembly show that EIS can separate membrane and interfacial effects, and that changes in membrane resistance dominate. Reasons for the presence of a capacitance in parallel with the membrane resistance are discussed.

  10. Modeling of gaseous flows within proton exchange membrane fuel cells

    SciTech Connect

    Weisbrod, K.R.; Vanderborgh, N.E.; Grot, S.A.

    1996-12-31

    Development of a comprehensive mechanistic model has been helpful to understand PEM fuel cell performance. Both through-the-electrode and down-the-channel models have been developed to support our experimental effort to enhance fuel cell design and operation. The through-the-electrode model was described previously. This code describes the known transport properties and dynamic processes that occur within a membrane and electrode assembly. Key parameters include transport through the backing layers, water diffusion and electroosmotic transport in the membrane, and reaction electrochemical kinetics within the cathode catalyst layer. In addition, two geometric regions within the cathode layer are represented, the first region below saturation and second with liquid water present. Although processes at high gas stoichiometry are well represented by more simple codes, moderate stoichiometry processes require a two dimensional representation that include the gaseous composition and temperature along flow channel. Although usually PEM hardware utilizes serpentine flow channels, this code does not include such geometric features and thus the flow can be visualized along a single channel.

  11. An inorganic-organic proton exchange membrane for fuel cells with a controlled nanoscale pore structure.

    PubMed

    Moghaddam, Saeed; Pengwang, Eakkachai; Jiang, Ying-Bing; Garcia, Armando R; Burnett, Daniel J; Brinker, C Jeffrey; Masel, Richard I; Shannon, Mark A

    2010-03-01

    Proton exchange membrane fuel cells have the potential for applications in energy conversion and energy storage, but their development has been impeded by problems with the membrane electrode assembly. Here, we demonstrate that a silicon-based inorganic-organic membrane offers a number of advantages over Nafion--the membrane widely used as a proton exchange membrane in hydrogen fuel cells--including higher proton conductivity, a lack of volumetric size change, and membrane electrode assembly construction capabilities. Key to achieving these advantages is fabricating a silicon membrane with pores with diameters of approximately 5-7 nm, adding a self-assembled molecular monolayer on the pore surface, and then capping the pores with a layer of porous silica. The silica layer reduces the diameter of the pores and ensures their hydration, resulting in a proton conductivity that is two to three orders of magnitude higher than that of Nafion at low humidity. A membrane electrode assembly constructed with this proton exchange membrane delivered an order of magnitude higher power density than that achieved previously with a dry hydrogen feed and an air-breathing cathode.

  12. Crosslinked sulfonated poly(ether ether ketone) proton exchange membranes for direct methanol fuel cell applications

    NASA Astrophysics Data System (ADS)

    Zhong, Shuangling; Cui, Xuejun; Cai, Hongli; Fu, Tiezhu; Zhao, Chengji; Na, Hui

    In the present study, a series of the crosslinked sulfonated poly(ether ether ketone) (SPEEK) proton exchange membranes were prepared. The photochemical crosslinking of the SPEEK membranes was carried out by dissolving benzophenone and triethylamine photo-initiator system in the membrane casting solution and then exposing the resulting membranes after solvent evaporation to UV light. The physical and transport properties of crosslinked membranes were investigated. The membrane performance can be controlled by adjusting the photoirradiation time. The experimental results showed that the crosslinked SPEEK membranes with photoirradiation 10 min had the optimum performance for proton exchange membranes (PEMs). Compared with the non-crosslinked SPEEK membranes, the crosslinked SPEEK membranes with photoirradiation 10 min markedly improved thermal stabilities and mechanical properties as well as hydrolytic and oxidative stabilities, greatly reduced water uptake and methanol diffusion coefficients with only slight sacrifice in proton conductivities. Therefore, the crosslinked SPEEK membranes with photoirradiation 10 min were particularly promising as proton exchange membranes for direct methanol fuel cell (DMFC) applications.

  13. Polymer-zeolite nanocomposite membranes for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Holmberg, Brett Anderson

    2005-07-01

    Proton exchange membrane fuel cells (PEMFCs) have recently received a great deal of attention for their potential as compact, high efficiency power sources for portable, distributed generation, and transportation applications. Unfortunately, current proton exchange membrane (PEM) technology hinders fuel cell performance by limiting fuel cell operation temperature and methanol feed concentration in direct methanol fuel cells (DMFCs). Nafion-zeolite nanocomposite membranes that take advantage of the hydrophilicity, selectivity, and proton conductivity of zeolite nanocrystals have been developed to address these problems. All known zeolite topologies were evaluated as potential additives to Nafion proton exchange membranes. Zeolites Y and beta were determined to have great potential as additives due to their low framework density, three dimensional pore structure, and high hydrophilicity. Zeolite Y nanocrystal syntheses were optimized to enhance yield and produce smaller crystal size. Significant improvement of the acid stability of the zeolite Y nanocrystals was not achieved with both ammonium hexafluorosilicate treatments and direct high silica nanocrystal synthesis. However, control of zeolite Y nanocrystal framework Si/Al ratio was demonstrated in the range of SiO2/Al2O3 = 4.38 to 5.84 by manipulating the tetramethylammonium structure directing agent hydroxide content. Zeolite beta nanocrystals were investigated due to their inherent high silica content and high acid stability. Zeolite beta nanocrystals were hydrothermally synthesized with and without phenethyl (called PE-BEA and BEA respectively) organic functional groups. Sulfonic acid functionalized zeolite beta (SAPE-BEA) was generated by treating the PE-BEA nanocrystals with a concentrated sulfuric acid post synthesis treatment. SAPE-BEA samples demonstrated proton conductivities up to 0.01 S/cm at room temperature under water-saturated conditions using a newly developed characterization technique. With

  14. Heat sources in proton exchange membrane (PEM) fuel cells

    NASA Astrophysics Data System (ADS)

    Ramousse, Julien; Lottin, Olivier; Didierjean, Sophie; Maillet, Denis

    In order to model accurately heat transfer in PEM fuel cell, a particular attention had to be paid to the assessment of heat sources in the cell. Although the total amount of heat released is easily computed from its voltage, local heat sources quantification and localization are not simple. This paper is thus a discussion about heat sources/sinks distribution in a single cell, for which many bold assumptions are encountered in the literature. The heat sources or sinks under consideration are: (1) half-reactions entropy, (2) electrochemical activation, (3) water sorption/desorption at the GDL/membrane interfaces, (4) Joule effect in the membrane and (5) water phase change in the GDL. A detailed thermodynamic study leads to the conclusion that the anodic half-reaction is exothermic (Δ Sr ev a = - 226 J mo l-1 K-1) , instead of being athermic as supposed in most of the thermal studies. As a consequence, the cathodic half-reaction is endothermic (Δ Sr ev c = + 62.8 J mo l-1 K-1) , which results in a heat sink at the cathode side, proportional to the current. In the same way, depending on the water flux through the membrane, sorption can create a large heat sink at one electrode and an equivalent heat source at the other. Water phase change in the GDL - condensation/evaporation - results in heat sources/sinks that should also be taken into account. All these issues are addressed in order to properly set the basis of heat transfer modeling in the cell.

  15. Preparation and performance of nano silica/Nafion composite membrane for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Keping; McDermid, Scott; Li, Jing; Kremliakova, Natalia; Kozak, Paul; Song, Chaojie; Tang, Yanghua; Zhang, Jianlu; Zhang, Jiujun

    Composite membranes made from Nafion ionomer with nano phosphonic acid-functionalised silica and colloidal silica were prepared and evaluated for proton exchange membrane fuel cells (PEMFCs) operating at elevated temperature and low relative humidity (RH). The phosphonic acid-functionalised silica additive obtained from a sol-gel process was well incorporated into Nafion membrane. The particle size determined using transmission electron microscope (TEM) had a narrow distribution with an average value of approximately 11 nm and a standard deviation of ±4 nm. The phosphonic acid-functionalised silica additive enhanced proton conductivity and water retention by introducing both acidic groups and porous silica. The proton conductivity of the composite membrane with the acid-functionalised silica was 0.026 S cm -1, 24% higher than that of the unmodified Nafion membrane at 85 °C and 50% RH. Compared with the Nafion membrane, the phosphonic acid-functionalised silica (10% loading level) composite membrane exhibited 60 mV higher fuel cell performance at 1 A cm -2, 95 °C and 35% RH, and 80 mV higher at 0.8 A cm -2, 120 °C and 35% RH. The fuel cell performance of composite membrane made with 6% colloidal silica without acidic group was also higher than unmodified Nafion membrane, however, its performance was lower than the acid-functionalised silica additive composite membrane.

  16. Graphene-doped electrospun nanofiber membrane electrodes and proton exchange membrane fuel cell performance

    NASA Astrophysics Data System (ADS)

    Wei, Meng; Jiang, Min; Liu, Xiaobo; Wang, Min; Mu, Shichun

    2016-09-01

    A rational electrode structure can allow proton exchange membrane (PEM) fuel cells own high performance with a low noble metal loading and an optimal transport pathway for reaction species. In this study, we develop a graphene doped polyacrylonitile (PAN)/polyvinylident fluoride (PVDF) (GPP) electrospun nanofiber electrode with improved electrical conductivity and high porosity, which could enhance the triple reaction boundary and promote gas and water transport throughout the porous electrode. Thus the increased electrochemical active surface area (ECSA) of Pt catalysts and fuel cell performance can be expected. As results, the ECSA of hot-pressed electrospun electrodes with 2 wt% graphene oxide (GO) is up to 84.3 m2/g, which is greatly larger than that of the conventional electrode (59.5 m2/g). Significantly, the GPP nanofiber electrospun electrode with Pt loading of 0.2 mg/cm2 exhibits higher fuel cell voltage output and stability than the conventional electrode.

  17. Theoretical Studies in Enhancing the Efficiency of Cathode and Anode Materials in PEMFC (Proton Exchange Membrane Fuel Cells)

    DTIC Science & Technology

    2011-03-04

    efficiency of cathode and anode materials in PEMFC (Proton Exchange Membrane Fuel Cells) 5a. CONTRACT NUMBER FA23861014012 5b. GRANT NUMBER 5c. PROGRAM...Rev. 8-98) Prescribed by ANSI Std Z39-18 Theoretical studies in enhancing the efficiency of cathode and anode materials in PEMFC (Proton Exchange

  18. Conductivity Measurements of Synthesized Heteropoly Acid Membranes for Proton Exchange Membrane Fuel Cells

    SciTech Connect

    Record, K.A.; Haley, B.T.; Turner, J.

    2006-01-01

    Fuel cell technology is receiving attention due to its potential to be a pollution free method of electricity production when using renewably produced hydrogen as fuel. In a Proton Exchange Membrane (PEM) fuel cell H2 and O2 react at separate electrodes, producing electricity, thermal energy, and water. A key component of the PEM fuel cell is the membrane that separates the electrodes. DuPont’s Nafion® is the most commonly used membrane in PEM fuel cells; however, fuel cell dehydration at temperatures near 100°C, resulting in poor conductivity, is a major hindrance to fuel cell performance. Recent studies incorporating heteropoly acids (HPAs) into membranes have shown an increase in conductivity and thus improvement in performance. HPAs are inorganic materials with known high proton conductivities. The primary objective of this work is to measure the conductivity of Nafion, X-Ionomer membranes, and National Renewable Energy Laboratory (NREL) Developed Membranes that are doped with different HPAs at different concentrations. Four-point conductivity measurements using a third generation BekkTech conductivity test cell are used to determine membrane conductivity. The effect of multiple temperature and humidification levels is also examined. While the classic commercial membrane, Nafion, has a conductivity of approximately 0.10 S/cm, measurements for membranes in this study range from 0.0030 – 0.58 S/cm, depending on membrane type, structure of the HPA, and the relative humidity. In general, the X-ionomer with H6P2W21O71 HPA gave the highest conductivity and the Nafion with the 12-phosphotungstic (PW12) HPA gave the lowest. The NREL composite membranes had conductivities on the order of 0.0013 – 0.025 S/cm.

  19. Nanostructure-based proton exchange membrane for fuel cell applications at high temperature.

    PubMed

    Li, Junsheng; Wang, Zhengbang; Li, Junrui; Pan, Mu; Tang, Haolin

    2014-02-01

    As a clean and highly efficient energy source, the proton exchange membrane fuel cell (PEMFC) has been considered an ideal alternative to traditional fossil energy sources. Great efforts have been devoted to realizing the commercialization of the PEMFC in the past decade. To eliminate some technical problems that are associated with the low-temperature operation (such as catalyst poisoning and poor water management), PEMFCs are usually operated at elevated temperatures (e.g., > 100 degrees C). However, traditional proton exchange membrane (PEM) shows poor performance at elevated temperature. To achieve a high-performance PEM for high temperature fuel cell applications, novel PEMs, which are based on nanostructures, have been developed recently. In this review, we discuss and summarize the methods for fabricating the nanostructure-based PEMs for PEMFC operated at elevated temperatures and the high temperature performance of these PEMs. We also give an outlook on the rational design and development of the nanostructure-based PEMs.

  20. Commercialization of proton exchange membrane fuel cells for transportation applications

    SciTech Connect

    Wismer, L.

    1996-04-01

    Environmental concerns with air quality and global warming have triggered strict federal ambient ozone air quality standards. Areas on non-attainment of these standards exist across the United States. Because it contains several of the most difficult attainment areas, the State of California has adopted low emission standards including a zero emission vehicle mandate that has given rise to development of hybrid electric vehicles, both battery-powered and fuel-cell powered. Fuel cell powered vehicles, using on-board hydrogen as a fuel, share the non-polluting advantage of the battery electric vehicle while offering at least three times the range today`s battery technology.

  1. Semi-analytical proton exchange membrane fuel cell modeling

    NASA Astrophysics Data System (ADS)

    Cheddie, Denver F.; Munroe, Norman D. H.

    Mathematical techniques are presented which allow for analytical solutions of the catalyst layer transport and electrochemical problem in PEM fuel cells. These techniques transform the volumetric reaction terms to boundary flux terms, thereby eliminating the need for computational solving of the catalyst layer problem. The result is a semi-analytical fuel cell model-a computational model that entails analytical rather than computational catalyst layer solutions. This helps to alleviate the meshing difficulties inherent in the catalyst layers caused by large geometric aspect ratios, and hence reduce the computational requirements for fuel cell models. These analytical solutions are implemented in a 3D PEM fuel cell model, and the results of the semi-analytical model match well with the full computational model in terms of the polarization performance and species concentration distribution. In addition, these analytical solutions were able to reduce the required computational memory by a factor of approximately 3, and the computational time by a factor of approximately 4.

  2. Proton Exchange Membrane (PEM) fuel Cell for Space Shuttle

    NASA Technical Reports Server (NTRS)

    Hoffman, William C., III; Vasquez, Arturo; Lazaroff, Scott M.; Downey, Michael G.

    1999-01-01

    Development of a PEM fuel cell powerplant (PFCP) for use in the Space Shuttle offers multiple benefits to NASA. A PFCP with a longer design life than is delivered currently from the alkaline fuel will reduce Space Shuttle Program maintenance costs. A PFCP compatible with zero-gravity can be adapted for future NASA transportation and exploration programs. Also, the commercial PEM fuel cell industry ensures a competitive environment for select powerplant components. Conceptual designs of the Space Shuttle PFCP have resulted in identification of key technical areas requiring resolution prior to development of a flight system. Those technical areas include characterization of PEM fuel cell stack durability under operational conditions and water management both within and external to the stack. Resolution of the above issues is necessary to adequately control development, production, and maintenance costs for a PFCP.

  3. Proton Exchange Membrane (PEM) fuel Cell for Space Shuttle

    NASA Technical Reports Server (NTRS)

    Hoffman, William C., III; Vasquez, Arturo; Lazaroff, Scott M.; Downey, Michael G.

    1999-01-01

    Development of a PEM fuel cell powerplant (PFCP) for use in the Space Shuttle offers multiple benefits to NASA. A PFCP with a longer design life than is delivered currently from the alkaline fuel will reduce Space Shuttle Program maintenance costs. A PFCP compatible with zero-gravity can be adapted for future NASA transportation and exploration programs. Also, the commercial PEM fuel cell industry ensures a competitive environment for select powerplant components. Conceptual designs of the Space Shuttle PFCP have resulted in identification of key technical areas requiring resolution prior to development of a flight system. Those technical areas include characterization of PEM fuel cell stack durability under operational conditions and water management both within and external to the stack. Resolution of the above issues is necessary to adequately control development, production, and maintenance costs for a PFCP.

  4. Proton Exchange Membrane (PEM) Fuel Cells for Space Applications

    NASA Technical Reports Server (NTRS)

    Bradley, Karla

    2004-01-01

    This presentation will provide a summary of the PEM fuel cell development at the National Aeronautics and Space Administration, Johnson Space Center (NASA, JSC) in support of future space applications. Fuel cells have been used for space power generation due to their high energy storage density for multi-day missions. The Shuttle currently utilizes the alkaline fuel cell technology, which has highly safe and reliable performance. However, the alkaline technology has a limited life due to the corrosion inherent to the alkaline technology. PEM fuel cells are under development by industry for transportation, residential and commercial stationary power applications. NASA is trying to incorporate some of this stack technology development in the PEM fuel cells for space. NASA has some unique design and performance parameters which make developing a PEM fuel cell system more challenging. Space fuel cell applications utilize oxygen, rather than air, which yields better performance but increases the hazard level. To reduce the quantity of reactants that need to be flown in space, NASA also utilizes water separation and reactant recirculation. Due to the hazards of utilizing active components for recirculation and water separation, NASA is trying to develop passive recirculation and water separation methods. However, the ability to develop recirculation components and water separators that are gravity-independent and successfully operate over the full range of power levels is one of the greatest challenges to developing a safe and reliable PEM fuel cell system. PEM stack, accessory component, and system tests that have been performed for space power applications will be discussed.

  5. Proton Exchange Membrane (PEM) Fuel Cells for Space Applications

    NASA Technical Reports Server (NTRS)

    Bradley, Karla

    2004-01-01

    This presentation will provide a summary of the PEM fuel cell development at the National Aeronautics and Space Administration, Johnson Space Center (NASA, JSC) in support of future space applications. Fuel cells have been used for space power generation due to their high energy storage density for multi-day missions. The Shuttle currently utilizes the alkaline fuel cell technology, which has highly safe and reliable performance. However, the alkaline technology has a limited life due to the corrosion inherent to the alkaline technology. PEM fuel cells are under development by industry for transportation, residential and commercial stationary power applications. NASA is trying to incorporate some of this stack technology development in the PEM fuel cells for space. NASA has some unique design and performance parameters which make developing a PEM fuel cell system more challenging. Space fuel cell applications utilize oxygen, rather than air, which yields better performance but increases the hazard level. To reduce the quantity of reactants that need to be flown in space, NASA also utilizes water separation and reactant recirculation. Due to the hazards of utilizing active components for recirculation and water separation, NASA is trying to develop passive recirculation and water separation methods. However, the ability to develop recirculation components and water separators that are gravity-independent and successfully operate over the full range of power levels is one of the greatest challenges to developing a safe and reliable PEM fuel cell system. PEM stack, accessory component, and system tests that have been performed for space power applications will be discussed.

  6. Novel niobium carbide/carbon porous nanotube electrocatalyst supports for proton exchange membrane fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Nabil, Y.; Cavaliere, S.; Harkness, I. A.; Sharman, J. D. B.; Jones, D. J.; Rozière, J.

    2017-09-01

    Niobium carbide/carbon nanotubular porous structures have been prepared using electrospinning and used as electrocatalyst supports for proton exchange membrane fuel cells. They were functionalised with 3.1 nm Pt particles synthesised by a microwave-assisted polyol method and characterised for their electrochemical properties. The novel NbC-based electrocatalyst demonstrated electroactivity towards the oxygen reduction reaction as well as greater stability over high potential cycling than a commercial carbon-based electrocatalyst. Pt/NbC/C was integrated at the cathode of a membrane electrode assembly and characterised in a single fuel cell showing promising activity and power density.

  7. Hydrogen-oxygen proton-exchange membrane fuel cells and electrolyzers

    NASA Technical Reports Server (NTRS)

    Baldwin, R.; Pham, M.; Leonida, A.; Mcelroy, J.; Nalette, T.

    1989-01-01

    Hydrogen-oxygen solid polymer electrolyte (SPE) fuel cells and SPE electrolyzers (products of Hamilton Standard) both use a Proton-Exchange Membrane (PEM) as the sole electrolyte. These solid electrolyte devices have been under continuous development for over 30 years. This experience has resulted in a demonstrated ten-year SPE cell life capability under load conditions. Ultimate life of PEM fuel cells and electrolyzers is primarily related to the chemical stability of the membrane. For perfluorocarbon proton exchange membranes an accurate measure of the membrane stability is the fluoride loss rate. Millions of cell hours have contributed to establishing a relationship between fluoride loss rates and average expected ultimate cell life. This relationship is shown. Several features have been introduced into SPE fuel cells and SPE electrolyzers such that applications requiring greater than or equal to 100,000 hours of life can be considered. Equally important as the ultimate life is the voltage stability of hydrogen-oxygen fuel cells and electrolyzers. Here again the features of SPE fuel cells and SPE electrolyzers have shown a cell voltage stability in the order of 1 microvolt per hour. That level of stability has been demonstrated for tens of thousands of hours in SPE fuel cells at up to 500 amps per square foot (ASF) current density.

  8. Effect of gas diffusion layer and membrane properties in an annular proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Khazaee, I.; Ghazikhani, M.; Esfahani, M. Nasr

    2012-01-01

    A complete three-dimensional and single phase computational dynamics model for annular proton exchange membrane (PEM) fuel cell is used to investigate the effect of changing gas diffusion layer and membrane properties on the performances, current density and gas concentration. The proposed model is a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations are solved in a single domain; therefore no interfacial boundary condition is required at the internal boundaries between cell components. This computational fluid dynamics code is used as the direct problem solver, which is used to simulate the two-dimensional mass, momentum and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC that cannot be investigated experimentally. The results show that by increasing the thickness and decreasing the porosity of GDL the performance of the cell enhances that it is different with planner PEM fuel cell. Also the results show that by decreasing the thickness of the membrane the performance of the cell increases.

  9. Transport in Proton Exchange Membranes for Fuel Cell Applications-A Systematic Non-Equilibrium Approach.

    PubMed

    Rangel-Cárdenas, Angie L; Koper, Ger J M

    2017-05-25

    We hypothesize that the properties of proton-exchange membranes for fuel cell applications cannot be described unambiguously unless interface effects are taken into account. In order to prove this, we first develop a thermodynamically consistent description of the transport properties in the membranes, both for a homogeneous membrane and for a homogeneous membrane with two surface layers in contact with the electrodes or holder material. For each subsystem, homogeneous membrane, and the two surface layers, we limit ourselves to four parameters as the system as a whole is considered to be isothermal. We subsequently analyze the experimental results on some standard membranes that have appeared in the literature and analyze these using the two different descriptions. This analysis yields relatively well-defined values for the homogeneous membrane parameters and estimates for those of the surface layers and hence supports our hypothesis. As demonstrated, the method used here allows for a critical evaluation of the literature values. Moreover, it allows optimization of stacked transport systems such as proton-exchange membrane fuel cell units where interfacial layers, such as that between the catalyst and membrane, are taken into account systematically.

  10. Transport in Proton Exchange Membranes for Fuel Cell Applications—A Systematic Non-Equilibrium Approach

    PubMed Central

    Rangel-Cárdenas, Angie L.; Koper, Ger J. M

    2017-01-01

    We hypothesize that the properties of proton-exchange membranes for fuel cell applications cannot be described unambiguously unless interface effects are taken into account. In order to prove this, we first develop a thermodynamically consistent description of the transport properties in the membranes, both for a homogeneous membrane and for a homogeneous membrane with two surface layers in contact with the electrodes or holder material. For each subsystem, homogeneous membrane, and the two surface layers, we limit ourselves to four parameters as the system as a whole is considered to be isothermal. We subsequently analyze the experimental results on some standard membranes that have appeared in the literature and analyze these using the two different descriptions. This analysis yields relatively well-defined values for the homogeneous membrane parameters and estimates for those of the surface layers and hence supports our hypothesis. As demonstrated, the method used here allows for a critical evaluation of the literature values. Moreover, it allows optimization of stacked transport systems such as proton-exchange membrane fuel cell units where interfacial layers, such as that between the catalyst and membrane, are taken into account systematically. PMID:28772939

  11. Diffusion-driven proton exchange membrane fuel cell for converting fermenting biomass to electricity.

    PubMed

    Malati, P; Mehrotra, P; Minoofar, P; Mackie, D M; Sumner, J J; Ganguli, R

    2015-10-01

    A membrane-integrated proton exchange membrane fuel cell that enables in situ fermentation of sugar to ethanol, diffusion-driven separation of ethanol, and its catalytic oxidation in a single continuous process is reported. The fuel cell consists of a fermentation chamber coupled to a direct ethanol fuel cell. The anode and fermentation chambers are separated by a reverse osmosis (RO) membrane. Ethanol generated from fermented biomass in the fermentation chamber diffuses through the RO membrane into a glucose solution contained in the DEFC anode chamber. The glucose solution is osmotically neutral to the biomass solution in the fermentation chamber preventing the anode chamber from drying out. The fuel cell sustains >1.3 mW cm(-2) at 47°C with high discharge capacity. No separate purification or dilution is necessary, resulting in an efficient and portable system for direct conversion of fermenting biomass to electricity.

  12. Photoregenerative I-/I3- couple as a liquid cathode for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Wang, Yadong; Ai, Xinping; Tu, Wenmao; Pan, Mu

    2014-10-01

    A photoassisted oxygen reduction reaction (ORR) through I-/I3- redox couple was investigated for proton exchange membrane (PEM) fuel cell cathode reaction. The I-/I3--based liquid cathode was used to replace conventional oxygen cathode, and its discharge product I- was regenerated to I3- by photocatalytic oxidation with the participation of oxygen. This new and innovative approach may provide a strategy to eliminate the usage of challenging ORR electrocatalysts, resulting in an avenue for developing low-cost and high-efficiency PEM fuel cells.

  13. The use of 1H NMR microscopy to study proton-exchange membrane fuel cells.

    PubMed

    Feindel, Kirk W; Bergens, Steven H; Wasylishen, Roderick E

    2006-01-16

    To understand proton-exchange membrane fuel cells (PEMFCs) better, researchers have used several techniques to visualize their internal operation. This Concept outlines the advantages of using 1H NMR microscopy, that is, magnetic resonance imaging, to monitor the distribution of water in a working PEMFC. We describe what a PEMFC is, how it operates, and why monitoring water distribution in a fuel cell is important. We will focus on our experience in constructing PEMFCs, and demonstrate how 1H NMR microscopy is used to observe the water distribution throughout an operating hydrogen PEMFC. Research in this area is briefly reviewed, followed by some comments regarding challenges and anticipated future developments.

  14. Novel proton exchange membrane fuel cell electrodes to improve performance of reversible fuel cell systems

    NASA Astrophysics Data System (ADS)

    Brown, Tim Matthew

    Proton exchange membrane (PEM) fuel cells react fuel and oxidant to directly and efficiently produce electrical power, without the need for combustion, heat engines, or motor-generators. Additionally, PEM fuel cell systems emit zero to virtually zero criteria pollutants and have the ability to reduce CO2 emissions due to their efficient operation, including the production or processing of fuel. A reversible fuel cell (RFC) is one particular application for a PEM fuel cell. In this application the fuel cell is coupled with an electrolyzer and a hydrogen storage tank to complete a system that can store and release electrical energy. These devices can be highly tailored to specific energy storage applications, potentially surpassing the performance of current and future secondary battery technology. Like all PEM applications, RFCs currently suffer from performance and cost limitations. One approach to address these limitations is to improve the cathode performance by engineering more optimal catalyst layer geometry as compared to the microscopically random structure traditionally used. Ideal configurations are examined and computer modeling shows promising performance improvements are possible. Several novel manufacturing methods are used to build and test small PEM fuel cells with novel electrodes. Additionally, a complete, dynamic model of an RFC system is constructed and the performance is simulated using both traditional and novel cathode structures. This work concludes that PEM fuel cell microstructures can be tailored to optimize performance based on design operating conditions. Computer modeling results indicate that novel electrode microstructures can improve fuel cell performance, while experimental results show similar performance gains that bolster the theoretical predictions. A dynamic system model predicts that novel PEM fuel cell electrode structures may enable RFC systems to be more competitive with traditional energy storage technology options.

  15. A self-sustained, complete and miniaturized methanol fuel processor for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Yang, Mei; Jiao, Fengjun; Li, Shulian; Li, Hengqiang; Chen, Guangwen

    2015-08-01

    A self-sustained, complete and miniaturized methanol fuel processor has been developed based on modular integration and microreactor technology. The fuel processor is comprised of one methanol oxidative reformer, one methanol combustor and one two-stage CO preferential oxidation unit. Microchannel heat exchanger is employed to recover heat from hot stream, miniaturize system size and thus achieve high energy utilization efficiency. By optimized thermal management and proper operation parameter control, the fuel processor can start up in 10 min at room temperature without external heating. A self-sustained state is achieved with H2 production rate of 0.99 Nm3 h-1 and extremely low CO content below 25 ppm. This amount of H2 is sufficient to supply a 1 kWe proton exchange membrane fuel cell. The corresponding thermal efficiency of whole processor is higher than 86%. The size and weight of the assembled reactors integrated with microchannel heat exchangers are 1.4 L and 5.3 kg, respectively, demonstrating a very compact construction of the fuel processor.

  16. Proton exchange membrane fuel cells for electrical power generation on-board commercial airplanes.

    SciTech Connect

    Curgus, Dita Brigitte; Munoz-Ramos, Karina; Pratt, Joseph William; Akhil, Abbas Ali; Klebanoff, Leonard E.; Schenkman, Benjamin L.

    2011-05-01

    Deployed on a commercial airplane, proton exchange membrane fuel cells may offer emissions reductions, thermal efficiency gains, and enable locating the power near the point of use. This work seeks to understand whether on-board fuel cell systems are technically feasible, and, if so, if they offer a performance advantage for the airplane as a whole. Through hardware analysis and thermodynamic and electrical simulation, we found that while adding a fuel cell system using today's technology for the PEM fuel cell and hydrogen storage is technically feasible, it will not likely give the airplane a performance benefit. However, when we re-did the analysis using DOE-target technology for the PEM fuel cell and hydrogen storage, we found that the fuel cell system would provide a performance benefit to the airplane (i.e., it can save the airplane some fuel), depending on the way it is configured.

  17. Proton Exchange Membrane Fuel Cells for Electrical Power Generation On-Board Commercial Airplanes

    SciTech Connect

    Pratt, Joesph W.; Klebanoff, Leonard E.; Munoz-Ramos, Karina; Akhil, Abbas A.; Curgus, Dita B.; Schenkman, Benjamin L.

    2011-05-01

    Deployed on a commercial airplane, proton exchange membrane fuel cells may offer emissions reductions, thermal efficiency gains, and enable locating the power near the point of use. This work seeks to understand whether on-board fuel cell systems are technically feasible, and, if so, if they offer a performance advantage for the airplane as a whole. Through hardware analysis and thermodynamic and electrical simulation, we found that while adding a fuel cell system using today’s technology for the PEM fuel cell and hydrogen storage is technically feasible, it will not likely give the airplane a performance benefit. However, when we re-did the analysis using DOE-target technology for the PEM fuel cell and hydrogen storage, we found that the fuel cell system would provide a performance benefit to the airplane (i.e., it can save the airplane some fuel), depending on the way it is configured.

  18. Proton exchange membrane fuel cell system diagnosis based on the signed directed graph method

    NASA Astrophysics Data System (ADS)

    Hua, Jianfeng; Lu, Languang; Ouyang, Minggao; Li, Jianqiu; Xu, Liangfei

    The fuel-cell powered bus is becoming the favored choice for electric vehicles because of its extended driving range, zero emissions, and high energy conversion efficiency when compared with battery-operated electric vehicles. In China, a demonstration program for the fuel cell bus fleet operated at the Beijing Olympics in 2008 and the Shanghai Expo in 2010. It is necessary to develop comprehensive proton exchange membrane fuel cell (PEMFC) diagnostic tools to increase the reliability of these systems. It is especially critical for fuel-cell city buses serving large numbers of passengers using public transportation. This paper presents a diagnostic analysis and implementation study based on the signed directed graph (SDG) method for the fuel-cell system. This diagnostic system was successfully implemented in the fuel-cell bus fleet at the Shanghai Expo in 2010.

  19. Performance Analysis of Air Breathing Proton Exchange Membrane Fuel Cell Stack (PEMFCS) At Different Operating Condition

    NASA Astrophysics Data System (ADS)

    Sunil, V.; Venkata siva, G.; Yoganjaneyulu, G.; Ravikumar, V. V.

    2017-08-01

    The answer for an emission free power source in future is in the form of fuel cells which combine hydrogen and oxygen producing electricity and a harmless by product-water. A proton exchange membrane (PEM) fuel cell is ideal for automotive applications. A single cell cannot supply the essential power for any application. Hence PEM fuel cell stacks are used. The effect of different operating parameters namely: type of convection, type of draught, hydrogen flow rate, hydrogen inlet pressure, ambient temperature and humidity, hydrogen humidity, cell orientation on the performance of air breathing PEM fuel cell stack was analyzed using a computerized fuel cell test station. Then, the fuel cell stack was subjected to different load conditions. It was found that the stack performs very poorly at full capacity (runs only for 30 min. but runs for 3 hours at 50% capacity). Hence, a detailed study was undertaken to maximize the duration of the stack’s performance at peak load.

  20. A review on the performance and modelling of proton exchange membrane fuel cells

    SciTech Connect

    Boucetta, A. Ghodbane, H. Bahri, M.; Ayad, M. Y.

    2016-07-25

    Proton Exchange Membrane Fuel Cells (PEMFC), are energy efficient and environmentally friendly alternative to conventional energy conversion for various applications in stationary power plants, portable power device and transportation. PEM fuel cells provide low operating temperature and high-energy efficiency with near zero emission. A PEM fuel cell is a multiple distinct parts device and a series of mass, energy, transport through gas channels, electric current transport through membrane electrode assembly and electrochemical reactions at the triple-phase boundaries. These processes play a decisive role in determining the performance of the Fuel cell, so that studies on the phenomena of gas flows and the performance modelling are made deeply. This paper gives a comprehensive overview of the state of the art on the Study of the phenomena of gas flow and performance modelling of PEMFC.

  1. A review on the performance and modelling of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Boucetta, A.; Ghodbane, H.; Ayad, M. Y.; Bahri, M.

    2016-07-01

    Proton Exchange Membrane Fuel Cells (PEMFC), are energy efficient and environmentally friendly alternative to conventional energy conversion for various applications in stationary power plants, portable power device and transportation. PEM fuel cells provide low operating temperature and high-energy efficiency with near zero emission. A PEM fuel cell is a multiple distinct parts device and a series of mass, energy, transport through gas channels, electric current transport through membrane electrode assembly and electrochemical reactions at the triple-phase boundaries. These processes play a decisive role in determining the performance of the Fuel cell, so that studies on the phenomena of gas flows and the performance modelling are made deeply. This paper gives a comprehensive overview of the state of the art on the Study of the phenomena of gas flow and performance modelling of PEMFC.

  2. New High-Temperature Membranes Developed for Proton Exchange Membrane Fuel Cells

    NASA Technical Reports Server (NTRS)

    Kinder, James D.

    2004-01-01

    Fuel cells are receiving a considerable amount of attention for potential use in a variety of areas, including the automotive industry, commercial power generation, and personal electronics. Research at the NASA Glenn Research Center has focused on the development of fuel cells for use in aerospace power systems for aircraft, unmanned air vehicles, and space transportation systems. These applications require fuel cells with higher power densities and better durability than what is required for nonaerospace uses. In addition, membrane cost is a concern for any fuel cell application. The most widely used membrane materials for proton exchange membrane (PEM) fuel cells are based on sulfonated perfluorinated polyethers, typically Nafion 117, Flemion, or Aciplex. However, these polymers are costly and do not function well at temperatures above 80 C. At higher temperatures, conventional membrane materials dry out and lose their ability to conduct protons, essential for the operation of the fuel cell. Increasing the operating temperature of PEM fuel cells from 80 to 120 C would significantly increase their power densities and enhance their durability by reducing the susceptibility of the electrode catalysts to carbon monoxide poisoning. Glenn's Polymers Branch has focused on developing new, low-cost membranes that can operate at these higher temperatures. A new series of organically modified siloxane (ORMOSIL) polymers were synthesized for use as membrane materials in a high-temperature PEM fuel cell. These polymers have an organic portion that can allow protons to transport through the polymer film and a cross-linked silica network that gives the polymers dimensional stability. These flexible xerogel polymer films are thermally stable, with decomposition onset as high as 380 C. Two types of proton-conducting ORMOSIL films have been produced: (1) NASA-A, which can coordinate many highly acid inorganic salts that facilitate proton conduction and (2) NASA-B, which has been

  3. Hydrogen-oxygen proton-exchange membrane fuel cells and electrolyzers

    NASA Technical Reports Server (NTRS)

    Baldwin, R.; Pham, M.; Leonida, A.; Mcelroy, J.; Nalette, T.

    1989-01-01

    Hydrogen-oxygen SPE fuel cells and SPE electrolyzers (products of Hamilton Standard) both use a Proton-Exchange Membrane (PEM) as the sole electrolyte. The SPE cells have demonstrated a ten year life capability under load conditions. Ultimate life of PEM fuel cells and electrolyzers is primarily related to the chemical stability of the membrane. For perfluorocarbon proton-exchange membranes an accurate measure of the membrane stability is the fluoride loss rate. Millions of cell hours have contributed to establishing a relationship between fluroride loss rates and average expected ultimate cell life. Several features were introduced into SPE fuel cells and SPE electrolyzers such that applications requiring greater than or equal to 100,000 hours of life can be considered. Equally important as the ultimate life is the voltage stability of hydrogen-oxygen fuel cells and electrolyzers. Here again the features of SPE fuel cells and SPE electrolyzers have shown a cell voltage stability in the order of 1 microvolt per hour. That level of stability were demonstrated for tens of thousands of hours in SPE fuel cells at up to 500 amps per square foot (ASF) current density. The SPE electrolyzers have demonstrated the same at 1000 ASF. Many future extraterrestrial applications for fuel cells require that they be self recharged. To translate the proven SPE cell life and stability into a highly reliable extraterrestrial electrical energy storage system, a simplification of supporting equipment is required. Static phase separation, static fluid transport and static thermal control will be most useful in producting required system reliability. Although some 200,000 SPE fuel cell hours were recorded in earth orbit with static fluid phase separation, no SPE electrolyzer has, as yet, operated in space.

  4. In-situ Monitoring of Internal Local Temperature and Voltage of Proton Exchange Membrane Fuel Cells

    PubMed Central

    Lee, Chi-Yuan; Fan, Wei-Yuan; Hsieh, Wei-Jung

    2010-01-01

    The distribution of temperature and voltage of a fuel cell are key factors that influence performance. Conventional sensors are normally large, and are also useful only for making external measurements of fuel cells. Centimeter-scale sensors for making invasive measurements are frequently unable to accurately measure the interior changes of a fuel cell. This work focuses mainly on fabricating flexible multi-functional microsensors (for temperature and voltage) to measure variations in the local temperature and voltage of proton exchange membrane fuel cells (PEMFC) that are based on micro-electro-mechanical systems (MEMS). The power density at 0.5 V without a sensor is 450 mW/cm2, and that with a sensor is 426 mW/cm2. Since the reaction area of a fuel cell with a sensor is approximately 12% smaller than that without a sensor, but the performance of the former is only 5% worse. PMID:22163556

  5. In-situ monitoring of internal local temperature and voltage of proton exchange membrane fuel cells.

    PubMed

    Lee, Chi-Yuan; Fan, Wei-Yuan; Hsieh, Wei-Jung

    2010-01-01

    The distribution of temperature and voltage of a fuel cell are key factors that influence performance. Conventional sensors are normally large, and are also useful only for making external measurements of fuel cells. Centimeter-scale sensors for making invasive measurements are frequently unable to accurately measure the interior changes of a fuel cell. This work focuses mainly on fabricating flexible multi-functional microsensors (for temperature and voltage) to measure variations in the local temperature and voltage of proton exchange membrane fuel cells (PEMFC) that are based on micro-electro-mechanical systems (MEMS). The power density at 0.5 V without a sensor is 450 mW/cm(2), and that with a sensor is 426 mW/cm(2). Since the reaction area of a fuel cell with a sensor is approximately 12% smaller than that without a sensor, but the performance of the former is only 5% worse.

  6. Catalyst layers for proton exchange membrane fuel cells prepared by electrospray deposition on Nafion membrane

    NASA Astrophysics Data System (ADS)

    Chaparro, A. M.; Ferreira-Aparicio, P.; Folgado, M. A.; Martín, A. J.; Daza, L.

    The electrospray deposition method has been used for preparation of catalyst layers for proton exchange membrane fuel cells (PEMFC) on Nafion membrane. Deposition of Pt/C + ionomer suspensions on Nafion 212 gives rise to layers with a globular morphology, in contrast with the dendritic growth observed for the same layers when deposited on the gas diffusion layer, GDL (microporous carbon black layer on carbon cloth) or on metallic Al foils. Such a change is discussed in the light of the influence of the Nafion substrate on the electrospray deposition process. Nafion, which is a proton conductor and electronic insulator, gives rise to the discharge of particles through proton release and transport towards the counter electrode, compared with the direct electron transfer that takes place when depositing on an electronic conductor. There is also a change in the electric field distribution in the needle to counter-electrode gap due to the presence of Nafion, which may alter conditions for the electrospray effect. If discharging of particles is slow enough, for instances with a low membrane protonic conductivity, the Nafion substrate may be charged positively yielding a change in the electric field profile and, with it, in the properties of the film. Single cell characterization is carried out with Nafion 212 membranes catalyzed by electrospray on the cathode side. It is shown that the internal resistance of the cell decreases with on-membrane deposited cathodic catalyst layers, with respect to the same layers deposited on GDL, giving rise to a considerable improvement in cell performance. The lower internal resistance is due to higher proton conductivity at the catalyst layer-membrane interface resulting from on-membrane deposition. On the other hand, electroactive area and catalyst utilization appear little modified by on-membrane deposition, compared with on-GDL deposition.

  7. Direct-hydrogen-fueled proton-exchange-membrane fuel cell system for transportation applications

    SciTech Connect

    Oei, D.; Adams, J.A.; Kinnelly, A.A.

    1997-07-01

    In partial fulfillment of the U.S. Department of Energy Contract No. DE-ACO2-94CE50389, {open_quotes}Direct Hydrogen-Fueled Proton-Exchange-Membrane (PEM) Fuel Cell System for Transportation Applications{close_quotes}, this conceptual vehicle design report addresses the design and packaging of battery augmented fuel cell powertrain vehicles. This report supplements the {open_quotes}Conceptual Vehicle Design Report - Pure Fuel Cell Powertrain Vehicle{close_quotes} and includes a cost study of the fuel cell power system. The three classes of vehicles considered in this design and packaging exercise are the same vehicle classes that were studied in the previous report: the Aspire, representing the small vehicle class; the AIV (Aluminum Intensive Vehicle) Sable, representing the mid-size vehicle; and the E-150 Econoline, representing the van-size class. A preliminary PEM fuel cell power system manufacturing cost study is also presented. As in the case of the previous report concerning the {open_quotes}Pure Fuel Cell Powertrain Vehicle{close_quotes}, the same assumptions are made for the fuel cell power system. These assumptions are fuel cell system power densities of 0.33 kW/ka and 0.33 kW/l, platinum catalyst loading of less than or equal to 0.25 mg/cm{sup 2} total, and hydrogen tanks containing compressed gaseous hydrogen under 340 atm (5000 psia) pressure. The batteries considered for power augmentation of the fuel cell vehicle are based on the Ford Hybrid Electric Vehicle (HEV) program. These are state-of-the-art high power lead acid batteries with power densities ranging from 0.8 kW/kg to 2 kW/kg. The results reported here show that battery augmentation provides the fuel cell vehicle with a power source to meet instant high power demand for acceleration and start-up. Based on the assumptions made in this report, the packaging of the battery augmented fuel cell vehicle appears to be as feasible as the packaging of the pure fuel cell powered vehicle.

  8. Advances in proton-exchange membranes for fuel cells: an overview on proton conductive channels (PCCs).

    PubMed

    Wu, Liang; Zhang, Zhenghui; Ran, Jin; Zhou, Dan; Li, Chuanrun; Xu, Tongwen

    2013-04-14

    Proton-exchange membranes (PEM) display unique ion-selective transport that has enabled a breakthrough in high-performance proton-exchange membrane fuel cells (PEMFCs). Elemental understanding of the morphology and proton transport mechanisms of the commercially available Nafion® has promoted a majority of researchers to tune proton conductive channels (PCCs). Specifically, knowledge of the morphology-property relationship gained from statistical and segmented copolymer PEMs has highlighted the importance of the alignment of PCCs. Furthermore, increasing efforts in fabricating and aligning artificial PCCs in field-aligned copolymer PEMs, nanofiber composite PEMs and mesoporous PEMs have set new paradigms for improvement of membrane performances. This perspective profiles the recent development of the channels, from the self-assembled to the artificial, with a particular emphasis on their formation and alignment. It concludes with an outlook on benefits of highly aligned PCCs for fuel cell operation, and gives further direction to develop new PEMs from a practical point of view.

  9. Detecting and localizing failure points in proton exchange membrane fuel cells using IR thermography

    NASA Astrophysics Data System (ADS)

    Bender, Guido; Felt, Wyatt; Ulsh, Michael

    2014-05-01

    An understanding of the potentially serious long-term performance degradation effects that coating and/or other fabrication irregularities might have in mass produced proton exchange membrane fuel cells (PEMFC) is essential to determine manufacturing tolerances of fuel cell components. An experimental setup and methodology is described that employs accelerated stress tests (ASTs) and IR thermography to accurately determine the location and severity of developing failure points in PEMFCs. The method entails a novel hardware that allows the spatial observation of a hydrogen crossover experiment within a fuel cell hardware. The application of the method is demonstrated by comparing the effects of an AST on pristine as well as defect-containing MEAs. The presented method is shown to be valuable for determining the areas within a fuel cell that are most stressed by aging processes.

  10. Proton exchange membrane fuel cell diagnosis by spectral characterization of the electrochemical noise

    NASA Astrophysics Data System (ADS)

    Maizia, R.; Dib, A.; Thomas, A.; Martemianov, S.

    2017-02-01

    Electrochemical noise analysis (ENA) has been performed for the diagnosis of proton-exchange membrane fuel cell (PEMFC) under various operating conditions. Its interest is related with the possibility of a non-invasive on-line diagnosis of a commercial fuel cell. A methodology of spectral analysis has been developed and an evaluation of the stationarity of the signal has been proposed. It has been revealed that the spectral signature of fuel cell, is a linear slope with a fractional power dependence 1/fα where α = 2 for different relative humidities and current densities. Experimental results reveal that the electrochemical noise is sensitive to the water management, especially under dry conditions. At RHH2 = 20% and RHair = 20%, spectral analysis shows a three linear slopes signature on the spectrum at low frequency range (f < 100 Hz). This results indicates that power spectral density, calculated thanks to FFT, can be used for the detection of an incorrect fuel cell water balance.

  11. Nanocomposite membranes based on polybenzimidazole and ZrO2 for high-temperature proton exchange membrane fuel cells.

    PubMed

    Nawn, Graeme; Pace, Giuseppe; Lavina, Sandra; Vezzù, Keti; Negro, Enrico; Bertasi, Federico; Polizzi, Stefano; Di Noto, Vito

    2015-04-24

    Owing to the numerous benefits obtained when operating proton exchange membrane fuel cells at elevated temperature (>100 °C), the development of thermally stable proton exchange membranes that demonstrate conductivity under anhydrous conditions remains a significant goal for fuel cell technology. This paper presents composite membranes consisting of poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI4N) impregnated with a ZrO2 nanofiller of varying content (ranging from 0 to 22 wt %). The structure-property relationships of the acid-doped and undoped composite membranes have been studied using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, wide-angle X-ray scattering, infrared spectroscopy, and broadband electrical spectroscopy. Results indicate that the level of nanofiller has a significant effect on the membrane properties. From 0 to 8 wt %, the acid uptake as well as the thermal and mechanical properties of the membrane increase. As the nanofiller level is increased from 8 to 22 wt % the opposite effect is observed. At 185 °C, the ionic conductivity of [PBI4N(ZrO2 )0.231 ](H3 PO4 )13 is found to be 1.04×10(-1)  S cm(-1) . This renders membranes of this type promising candidates for use in high-temperature proton exchange membrane fuel cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Study and development of sulfated zirconia based proton exchange fuel cell membranes

    NASA Astrophysics Data System (ADS)

    Kemp, Brittany Wilson

    With the increasing consumption of energy, fuel cells are among the most promising alternatives to fossil fuels, provided some technical challenges are overcome. Proton exchange membrane fuel cells (PEMFCs) have been investigated and improvements have been made, but the problem with NafionRTM, the main membrane for PEMFCs, has not been solved. NafionRTM restricts the membranes from operating at higher temperatures, thus preventing them from working in small electronics. The problem is to develop a novel fuel cell membrane that performs comparably to NafionRTM in PEMFCs. The membranes were fabricated by applying sulfated zirconia, via template wetting, to porous alumina membranes. The fabricated membranes showed a proton conductivity of 0.016 S/cm in comparison to the proton conductivity of Nafion RTM (0.05 S/cm). Both formic acid and methanol had a lower crossover flux through the sulfated zirconia membranes (formic acid- 2.89x10 -7 mols/cm2s and methanol-1.78x10-9 mols/cm2s) than through NafionRTM (formic acid-2.03x10 -8 mols/cm2s methanol-2.42x10-6 mols/cm 2s), indicating that a sulfated zirconia PEMFC may serve as a replacement for NafionRTM.

  13. Nonlinear robust control of proton exchange membrane fuel cell by state feedback exact linearization

    NASA Astrophysics Data System (ADS)

    Li, Q.; Chen, W.; Wang, Y.; Jia, J.; Han, M.

    By utilizing the state feedback exact linearization approach, a nonlinear robust control strategy is designed based on a multiple-input multiple-output (MIMO) dynamic nonlinear model of proton exchange membrane fuel cell (PEMFC). The state feedback exact linearization approach can achieve the global exact linearization via the nonlinear coordinate transformation and the dynamic extension algorithm such that H ∞ robust control strategy can be directly utilized to guarantee the robustness of the system. The proposed dynamic nonlinear model is tested by comparing the simulation results with the experimental data in Fuel Cell Application Centre in Temasek Polytechnic. The comprehensive results of simulation manifest that the dynamic nonlinear model with nonlinear robust control law has better transient and robust stability when the vehicle running process is simulated. The proposed nonlinear robust controller will be very useful to protect the membrane damage by keeping the pressure deviations as small as possible during large disturbances and prolong the stack life of PEMFC.

  14. Polarity governed selective amplification of through plane proton shuttling in proton exchange membrane fuel cells.

    PubMed

    Gautam, Manu; Chattanahalli Devendrachari, Mruthyunjayachari; Thimmappa, Ravikumar; Raja Kottaichamy, Alagar; Pottachola Shafi, Shahid; Gaikwad, Pramod; Makri Nimbegondi Kotresh, Harish; Ottakam Thotiyl, Musthafa

    2017-03-15

    Graphene oxide (GO) anisotropically conducts protons with directional dominance of in plane ionic transport (σ IP) over the through plane (σ TP). In a typical H2-O2 fuel cell, since the proton conduction occurs through the plane during its generation at the fuel electrode, it is indeed inevitable to selectively accelerate GO's σ TP for advancement towards a potential fuel cell membrane. We successfully achieved ∼7 times selective amplification of GO's σ TP by tuning the polarity of the dopant molecule in its nanoporous matrix. The coexistence of strongly non-polar and polar domains in the dopant demonstrated a synergistic effect towards σ TP with the former decreasing the number of water molecules coordinated to protons by ∼3 times, diminishing the effects of electroosmotic drag exerted on ionic movements, and the latter selectively accelerating σ TP across the catalytic layers by bridging the individual GO planes via extensive host guest H-bonding interactions. When they are decoupled, the dopant with mainly non-polar or polar features only marginally enhances the σ TP, revealing that polarity factors contribute to fuel cell relevant transport properties of GO membranes only when they coexist. Fuel cell polarization and kinetic analyses revealed that these multitask dopants increased the fuel cell performance metrics of the power and current densities by ∼3 times compared to the pure GO membranes, suggesting that the functional group factors of the dopants are of utmost importance in GO-based proton exchange membrane fuel cells.

  15. An non-uniformity voltage model for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Li, Kelei; Li, Yankun; Liu, Jiawei; Guo, Ai

    2017-01-01

    The fuel cell used in transportation has environmental protection, high efficiency and no line traction power system which can greatly reduce line construction investment. That makes it a huge potential. The voltage uniformity is one of the most important factors affecting the operation life of proton exchange membrane fuel cell (PEMFC). On the basis of principle and classical model of the PEMFC, single cell voltage is calculated and the location coefficients are introduced so as to establish a non-uniformity voltage model. These coefficients are estimated with the experimental datum at stack current 50 A. The model is validated respectively with datum at 60 A and 100 A. The results show that the model reflects the basic characteristics of voltage non-uniformity and provides the beneficial reference for fuel cell control and single cell voltage detection.

  16. Evaluation of the humidification requirements of new proton exchange membranes for fuel cells

    NASA Astrophysics Data System (ADS)

    Grot, Stephen; Hedstrom, J. C.; Vanderborgh, N. E.

    Measurements of PEM fuel cell device performance were made with different gas inlet temperatures and relative humidity using a newly-designed test fixture. Significant improvement in device performance was observed when the fuel inlet temperature was increased above the operating temperature of the cell. These measurements were then correlated to a model to describe energy and mass transport processes. Proton exchange membrane (PEM), fuel cells--the focus of this study--use an ion conducting polymer, especially polyperfluorosulfonic acid materials. These polymer materials, when imbibed with water, exhibit solution-like properties, but because the anions are chemically bound to the polymeric structure, the electrolyte is contained. Importantly, product water removal is simplified, as electrolyte dilution is not a concern. However, the proton transport rate is a function of the polymer geometry, which is set, in part, by the polymer water content. Consequently, dynamics of water flow are essential to understand the design of efficient conversion devices.

  17. A review of water flooding issues in the proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Li, Hui; Tang, Yanghua; Wang, Zhenwei; Shi, Zheng; Wu, Shaohong; Song, Datong; Zhang, Jianlu; Fatih, Khalid; Zhang, Jiujun; Wang, Haijiang; Liu, Zhongsheng; Abouatallah, Rami; Mazza, Antonio

    We have reviewed more than 100 references that are related to water management in proton exchange membrane (PEM) fuel cells, with a particular focus on the issue of water flooding, its diagnosis and mitigation. It was found that extensive work has been carried out on the issues of flooding during the last two decades, including prediction through numerical modeling, detection by experimental measurements, and mitigation through the design of cell components and manipulating the operating conditions. Two classes of strategies to mitigate flooding have been developed. The first is based on system design and engineering, which is often accompanied by significant parasitic power loss. The second class is based on membrane electrode assembly (MEA) design and engineering, and involves modifying the material and structural properties of the gas diffusion layer (GDL), cathode catalyst layer (CCL) and membrane to function in the presence of liquid water. In this review, several insightful directions are also suggested for future investigation.

  18. Improving dynamic performance of proton-exchange membrane fuel cell system using time delay control

    NASA Astrophysics Data System (ADS)

    Kim, Young-Bae

    Transient behaviour is a key parameter for the vehicular application of proton-exchange membrane (PEM) fuel cell. The goal of this presentation is to construct better control technology to increase the dynamic performance of a PEM fuel cell. The PEM fuel cell model comprises a compressor, an injection pump, a humidifier, a cooler, inlet and outlet manifolds, and a membrane-electrode assembly. The model includes the dynamic states of current, voltage, relative humidity, stoichiometry of air and hydrogen, cathode and anode pressures, cathode and anode mass flow rates, and power. Anode recirculation is also included with the injection pump, as well as anode purging, for preventing anode flooding. A steady-state, isothermal analytical fuel cell model is constructed to analyze the mass transfer and water transportation in the membrane. In order to prevent the starvation of air and flooding in a PEM fuel cell, time delay control is suggested to regulate the optimum stoichiometry of oxygen and hydrogen, even when there are dynamical fluctuations of the required PEM fuel cell power. To prove the dynamical performance improvement of the present method, feed-forward control and Linear Quadratic Gaussian (LQG) control with a state estimator are compared. Matlab/Simulink simulation is performed to validate the proposed methodology to increase the dynamic performance of a PEM fuel cell system.

  19. Influence of water and membrane microstructure on the transport properties of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Siu, Ana Rosa

    Proton transport in proton exchange membranes (PEMs) depends on interaction between water and acid groups covalently bound to the polymer. Although the presence of water is important in maintaining the PEM's functions, a thorough understanding of this topic is still lacking. The objective of this work is to provide a better understanding of how the nature water, confined to ionic domains of the polymer, influences the membrane's ability to transport protons, methanol and water. Understanding this topic will facilitate development of new materials with favorable transport properties for fuel cells use. Five classes of polymer membranes were used in this work: polyacrylonitrile-graft-poly(styrenesulfonic) acid (PAN-g-macPSSA); poly(vinylidene difluoride) irradiation-graft-poly(styrenesulfonic) acid (PVDF-g-PSSA); poly(ethylenetetrafluoroethylene) irradiation-graft-poly(styrenesulfonic) acid (ETFE-gPSSA); PVDF-g-PSSA with hydroxyethylmethacrylate (HEMA); and perfluorosulfonic acid membrane (Nafion). The nature of water within the polymers (freezable versus non-freezable states) was measured by systematically freezing samples, and observing the temperature at which water freezes and the amount of heat released in the process. Freezing water-swollen membranes resulted in a 4-fold decrease in the proton conductivity of the PEM. Activation energies of proton transport before and after freezing were ˜ 0.15 eV and 0.5 eV, consistent with proton transport through liquid water and bound water, respectively. Reducing the content of water in membrane samples decreased the amount of freezable and non-freezable water. Calorimetric measurements of membranes in various degrees of hydration showed that water molecules became non-freezable when lambda, (water molecules per sulfonic acid group) was less than ˜14. Proton conduction through membranes containing only non-freezable water was demonstrated to be feasible. Diffusion experiments showed that the permeability of methanol

  20. Development of large aperture projection scatterometry for catalyst loading evaluation in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Stocker, Michael T.; Barnes, Bryan M.; Sohn, Martin; Stanfield, Eric; Silver, Richard M.

    2017-10-01

    Widespread commercialization of proton exchange membrane fuel cells remains curbed by various manufacturing and infrastructure challenges. One such technical barrier identified by the U. S. Department of Energy is the need for high-speed, in-line process control of platinum-based catalyst layers in the membrane electrode assembly of the fuel cell. Using multiple reflectivity-based optical methods, such as optical scatterometry and large aperture projection scatterometry, we demonstrate in-line-capable catalyst loading measurements of carbon-supported Pt nanoparticle and Pt-alloy nanostructured thin film catalyst coated membranes. Large aperture projection scatterometry is a new high-throughput approach developed at the National Institute of Standards and Technology specifically for fuel cell manufacturing metrology. Angle- and wavelength-resolved measurements of these fuel cell soft goods validate the ability of reflectivity-based measurements to produce industrially relevant sensitivities to changes in Pt and Pt-alloy loading. The successful application of these optical methods to fuel cell manufacturing metrology directly addresses the shortage of high-throughput process control approaches needed to facilitate performance improvements and manufacturing cost-reductions required to make fuel cells commercially viable.

  1. Improved Electrodes for High Temperature Proton Exchange Membrane Fuel Cells using Carbon Nanospheres.

    PubMed

    Zamora, Héctor; Plaza, Jorge; Cañizares, Pablo; Lobato, Justo; Rodrigo, Manuel A

    2016-05-23

    This work evaluates the use of carbon nanospheres (CNS) in microporous layers (MPL) of high temperature proton exchange membrane fuel cell (HT-PEMFC) electrodes and compares the characteristics and performance with those obtained using conventional MPL based on carbon black. XRD, hydrophobicity, Brunauer-Emmett-Teller theory, and gas permeability of MPL prepared with CNS were the parameters evaluated. In addition, a short life test in a fuel cell was carried out to evaluate performance under accelerated stress conditions. The results demonstrate that CNS is a promising alternative to traditional carbonaceous materials because of its high electrochemical stability and good electrical conductivity, suitable to be used in this technology. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Fatigue Analysis of Proton Exchange Membrane Fuel Cell Stacks Based on Structural Stress Distribution

    NASA Astrophysics Data System (ADS)

    Wu, C. W.; Liu, B.; Wei, M. Y.; Liu, L. F.

    2017-05-01

    Proton exchange membrane fuel cell (PEMFC) stack usually undergoes various vibrations during packing, transportation and serving time, in particular for those used in the automobiles and portable equipment. Based on the Miner fatigue damage theory, the fatigue lives of the fuel cell components are first assessed. Then the component fatigue life contours of the stack are obtained under four working conditions, i.e. the three single-axial (in X-, Y- and Z-axis separately) and multi-axial random vibrations. Accordingly, the component damage under various vibrations is evaluated. The stress distribution on the gasket and PEM will greatly affect their fatigue lives. Finally, we compare the fatigue lives of 4-bolt- and 6-bolt-clamping stacks under the same total clamping force, and find that increasing the bolt number could improve the bolt fatigue lives.

  3. Inductive phenomena at low frequencies in impedance spectra of proton exchange membrane fuel cells - A review

    NASA Astrophysics Data System (ADS)

    Pivac, Ivan; Barbir, Frano

    2016-09-01

    The results of electrochemical impedance spectroscopy of proton exchange membrane (PEM) fuel cells may exhibit inductive phenomena at low frequencies. The occurrence of inductive features at high frequencies is explained by the cables and wires of the test system. However, explanation of inductive loop at low frequencies requires a more detailed study. This review paper discusses several possible causes of such inductive behavior in PEM fuel cells, such as side reactions with intermediate species, carbon monoxide poisoning, and water transport, also as their equivalent circuit representations. It may be concluded that interpretation of impedance spectra at low frequencies is still ambiguous, and that better equivalent circuit models are needed with clearly defined physical meaning of each of the circuit elements.

  4. The effect of materials on proton exchange membrane fuel cell electrode performance

    NASA Astrophysics Data System (ADS)

    Millington, Ben; Du, Shangfeng; Pollet, Bruno G.

    This paper describes the optimisation in the fabrication materials and techniques used in proton exchange membrane fuel cell (PEMFC) electrodes. The effect on the performance of membrane electrode assemblies (MEAs) from the solvents used in producing catalyst inks is reported. Comparison in MEA performances between various gas diffusion layers (GDLs) and the importance of microporous layers (MPLs) in gas diffusion electrodes (GDEs) are also shown. It was found that the best performances were achieved for GDEs using tetrahydrofuran (THF) as the solvent in the catalyst ink formulation and Sigracet 10BC as the GDL. The results also showed that our in-house painted GDEs were comparable to commercial ones (using Johnson Matthey HiSpec™ and E-TEK catalysts).

  5. Low energy plasma treatment of a proton exchange membrane used for low temperature fuel cells

    NASA Astrophysics Data System (ADS)

    Charles, C.; Ramdutt, D.; Brault, P.; Caillard, A.; Bulla, D.; Boswell, R.; Rabat, H.; Dicks, A.

    2007-05-01

    A low energy (~30 V) plasma treatment of Nafion, a commercial proton exchange membrane used for low temperature fuel cells, is performed in a helicon radiofrequency (13.56 MHz) plasma system. For argon densities in the 109-1010 cm-3 range, the water contact angle (hydrophobicity) of the membrane surface linearly decreases with an increase in the plasma energy dose, which is maintained below 5.1 J cm-2, and which results from the combination of an ion energy dose (up to 3.8 J cm-2) and a photon (mostly UV) energy dose (up to 1.3 J cm-2). The decrease in water contact angle is essentially a result of the energy brought to the surface by ion bombardment. The measured effect of the energy brought to the surface by UV light is found to be negligible.

  6. Towards neat methanol operation of direct methanol fuel cells: a novel self-assembled proton exchange membrane.

    PubMed

    Li, Jing; Cai, Weiwei; Ma, Liying; Zhang, Yunfeng; Chen, Zhangxian; Cheng, Hansong

    2015-04-18

    We report here a novel proton exchange membrane with remarkably high methanol-permeation resistivity and excellent proton conductivity enabled by carefully designed self-assembled ionic conductive channels. A direct methanol fuel cell utilizing the membrane performs well with a 20 M methanol solution, very close to the concentration of neat methanol.

  7. Vibration mode analysis of the proton exchange membrane fuel cell stack

    NASA Astrophysics Data System (ADS)

    Liu, B.; Liu, L. F.; Wei, M. Y.; Wu, C. W.

    2016-11-01

    Proton exchange membrane fuel cell (PEMFC) stacks usually undergo vibration during packing, transportation, and serving time, in particular for those used in the automobiles or portable equipment. To study the stack vibration response, based on finite element method (FEM), a mode analysis is carried out in the present paper. Using this method, we can distinguish the local vibration from the stack global modes, predict the vibration responses, such as deformed shape and direction, and discuss the effects of the clamping configuration and the clamping force magnitude on vibration modes. It is found that when the total clamping force remains the same, increasing the bolt number can strengthen the stack resistance to vibration in the clamping direction, but cannot obviously strengthen stack resistance to vibration in the translations perpendicular to clamping direction and the three axis rotations. Increasing the total clamping force can increase both of the stack global mode and the bolt local mode frequencies, but will decrease the gasket local mode frequency.

  8. Pt nanoparticle-reduced graphene oxide nanohybrid for proton exchange membrane fuel cells.

    PubMed

    Park, Dae-Hwan; Jeon, Yukwon; Ok, Jinhee; Park, Jooil; Yoon, Seong-Ho; Choy, Jin-Ho; Shul, Yong-Gun

    2012-07-01

    A platinum nanoparticle-reduced graphene oxide (Pt-RGO) nanohybrid for proton exchange membrane fuel cell (PEMFC) application was successfully prepared. The Pt nanoparticles (Pt NPs) were deposited onto chemically converted graphene nanosheets via ethylene glycol (EG) reduction. According to the powder X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) analysis, the face-centered cubic Pt NPs (3-5 nm in diameter) were homogeneously dispersed on the RGO nanosheets. The electrochemically active surface area and PEMFC power density of the Pt-RGO nanohybrid were determined to be 33.26 m2/g and 480 mW/cm2 (maximum values), respectively, at 75 degrees C and at a relative humidity (RH) of 100% in a single-cell test experiment.

  9. Carbon film coating on gas diffusion layer for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lin, Jui-Hsiang; Chen, Wei-Hung; Su, Shih-Hsuan; Liao, Yuan-Kai; Ko, Tse-Hao

    This study discusses a novel process to increase the performance of proton exchange membrane fuel cells (PEMFC). In order to improve the electrical conductivity and reduce the surface indentation of the carbon fibers, we modified the carbon fibers with pitch-based carbon materials (mesophase pitch and coal tar pitch). Compared with the gas diffusion backing (GDB), GDB-A240 and GDB-MP have 32% and 33% higher current densities at 0.5 V, respectively. Self-made carbon paper with the addition of a micro-porous layer (MPL) (GDL-A240 and GDL-MP) show improved performance compared with GDB-A240 and GDB-MP. The current densities of GDL-A240 and GDL-MP at 0.5 V increased by 37% and 31% compared with GDL, respectively. This study combines these two effects (carbon film and MPL coating) to promote high current density in a PEMFC.

  10. Potential oscillations in a proton exchange membrane fuel cell with a Pd-Pt/C anode

    NASA Astrophysics Data System (ADS)

    Lopes, Pietro P.; Ticianelli, Edson A.; Varela, Hamilton

    We report in this paper the occurrence of potential oscillations in a proton exchange membrane fuel cell (PEMFC) with a Pd-Pt/C anode, fed with H 2/100 ppm CO, and operated at 30 °C. We demonstrate that the use of Pd-Pt/C anode enables the emergence of dynamic instabilities in a PEMFC. Oscillations are characterized by the presence of very high oscillation amplitude, ca. 0.8 V, which is almost twice that observed in a PEMFC with a Pt-Ru/C anode under similar conditions. The effects of the H 2/CO flow rate and cell current density on the oscillatory dynamics were investigated and the mechanism rationalized in terms of the CO oxidation and adsorption processes. We also discuss the fundamental aspects concerning the operation of a PEMFC under oscillatory regime in terms of the benefit resulting from the higher average power output.

  11. Characterisation of porous carbon electrode materials used in proton exchange membrane fuel cells via gas adsorption

    NASA Astrophysics Data System (ADS)

    Watt-Smith, M. J.; Rigby, S. P.; Ralph, T. R.; Walsh, F. C.

    Porous carbon materials are typically used in both the substrate (typically carbon paper) and the electrocatalyst supports (often platinised carbon) within proton exchange membrane fuel cells. Gravimetric nitrogen adsorption has been studied at a carbon paper substrate, two different Pt-loaded carbon paper electrodes and three particulate carbon blacks. N 2 BET surface areas and surface fractal dimensions were determined using the fractal BET and Frenkel-Halsey-Hill models for all but one of the materials studied. The fractal dimensions of the carbon blacks obtained from gas adsorption were compared with those obtained independently by small angle X-ray scattering and showed good agreement. Density functional theory was used to characterise one of the carbon blacks, as the standard BET model was not applicable.

  12. Exergy analysis of an ethanol fuelled proton exchange membrane (PEM) fuel cell system for automobile applications

    NASA Astrophysics Data System (ADS)

    Song, Shuqin; Douvartzides, Savvas; Tsiakaras, Panagiotis

    An integrated ethanol fuelled proton exchange membrane fuel cell (PEMFC) power system was investigated following a second law exergy analysis. The system was assumed to have the typical design for automobile applications and was comprised of a vaporizer/mixer, a steam reformer, a CO-shift reactor, a CO-remover (PROX) reactor, a PEMFC and a burner. The exergy analysis was applied for different PEMFC power and voltage outputs assuming the ethanol steam reforming at about 600 K and the CO-shift reaction at about 400 K. A detailed parametric analysis of the plant is presented and operation guidelines are suggested for effective performance. In every case, the exergy analysis method is proved to allow an accurate allocation of the deficiencies of the subsystems of the plant and serves as a unique tool for essential technical improvements.

  13. Pendant dual sulfonated poly(arylene ether ketone) proton exchange membranes for fuel cell application

    NASA Astrophysics Data System (ADS)

    Nguyen, Minh Dat Thinh; Yang, Sungwoo; Kim, Dukjoon

    2016-10-01

    Poly(arylene ether ketone) (PAEK) possessing carboxylic groups at the pendant position is synthesized, and the substitution degree of pendant carboxylic groups is controlled by adjusting the ratio of 4,4-bis(4-hydroxyphenyl)valeric acid and 2,2-bis(4-hydroxyphenyl)propane. Dual sulfonated 3,3-diphenylpropylamine (SDPA) is grafted onto PAEK as a proton-conducting moiety via the amidation reaction with carboxylic groups. The transparent and flexible membranes with different degrees of sulfonation are fabricated so that we can test and compare their structure and properties with a commercial Nafion® 115 membrane for PEMFC applications. All prepared PAEK-SDPA membranes exhibit good oxidative and hydrolytic stability from Fenton's and high temperature water immersion test. SAXS analysis illustrates an excellent phase separation between the hydrophobic backbone and hydrophilic pendant groups, resulting in big ionic clusters. The proton conductivity was measured at different relative humidity, and its behavior was analyzed by hydration number of the membrane. Among a series of membranes, some samples (including B20V80-SDPA) show not only higher proton conductivity, but also higher integrated cell performance than those of Nafion® 115 at 100% relative humidity, and thus we expect these to be good candidate membranes for proton exchange membrane fuel cells (PEMFCs).

  14. Prolongation of lifetime of high temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Oono, Yuka; Sounai, Atsuo; Hori, Michio

    2013-11-01

    In a previous study on the long-term operation of high-temperature proton exchange membrane fuel cells (HT-PEMFCs) with polybenzimidazole (PBI) membranes, it was found that the main cause of the observed decrease in cell voltage with time was phosphoric acid depletion due to evaporation. Based on this result, in the present study, the effects of using a different kind of cell membrane were investigated. Instead of PBI membranes, phosphoric-acid-doped, chemically cross-linked poly(2,5-benzimidazole) (ABPBI) membranes were employed in HT-PEMFCs and long-term power generation tests were carried out. Two separate cells were operated for 1000 and 17,500 h at a temperature of 150 °C and a current density of 0.2 A cm-2. Their membrane electrode assemblies were then subjected to electron probe microanalysis. The results for the cell operated for 17,500 h were directly compared with those for a cell with a PBI membrane operated for 17,800 h in a previous study, allowing the mechanism of cell performance reduction in HT-PEMFCs to be further elucidated.

  15. Low power proton exchange membrane fuel cell system identification and adaptive control

    NASA Astrophysics Data System (ADS)

    Yang, Yee-Pien; Wang, Fu-Cheng; Chang, Hsin-Ping; Ma, Ying-Wei; Weng, Biing-Jyh

    This paper proposes a systematic method of system identification and control of a proton exchange membrane (PEM) fuel cell. This fuel cell can be used for low-power communication devices involving complex electrochemical reactions of nonlinear and time-varying dynamic properties. From a system point of view, the dynamic model of PEM fuel cell is reduced to a configuration of two inputs, hydrogen and air flow rates, and two outputs, cell voltage and current. The corresponding transfer functions describe linearized subsystem dynamics with finite orders and time-varying parameters, which are expressed as discrete-time auto-regression moving-average with auxiliary input models for system identification by the recursive least square algorithm. In the experiments, a pseudo-random binary sequence of hydrogen or air flow rate is fed to a single fuel cell device to excite its dynamics. By measuring the corresponding output signals, each subsystem transfer function of reduced order is identified, while the unmodeled, higher-order dynamics and disturbances are described by the auxiliary input term. This provides a basis of adaptive control strategy to improve the fuel cell performance in terms of efficiency, as well as transient and steady state specifications. Simulation shows that adaptive controller is robust to the variation of fuel cell system dynamics, and it has proved promising from the experimental results.

  16. Polymer Composites for High-Temperature Proton-Exchange Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Zhu, Xiuling; Liu, Yuxiu; Zhu, Lei

    Recent advances in composite proton-exchange membranes for fuel cell applications at elevated temperature and low relative humidity are briefly reviewed in this chapter. Although a majority of research has focused on new sulfonated hydrocarbon and fluorocarbon polymers and their blends to directly enhance high temperature performance, we emphasize on polymer/inorganic composite membranes with the aim of improving the mechanical strength, thermal stability, and proton conductivity, which depend on water retention at elevated temperature and low relative humidity conditions. The polymer systems include perfluoronated polymers such as Nafion, sulfonated poly(arylene ether)s, polybenzimidazoles (PBI)s, and many others. The inorganic proton conductors are silica, heteropolyacids (HPA)s, layered zirconium phosphates, and liquid phosphoric acid. Direct use of sol-gel silica requires pressurization of fuel cells to maintain 100% relative humidity for high proton conductivity above 100°C. Direct incorporation of HPAs such as phosphotungstic acid (PTA) into polyelectrolyte membranes is capable of improving both proton conductivity and fuel cell performance above 100°C; however, they tend to leach out of the membrane whenever fuel cell flooding happens. To prevent HPA leaching, amine-functionalized mesoporous silica is used to immobilize PTA in Nafion membranes, whose proton conductivity and fuel cell performance are discussed. Compared with Nafion, sulfonated poly(arylene ether)s such as sulfonated poly(arylene ether sulfone)s are cost-effective materials with excellent thermal and electrochemical stability. Their composites with HPAs show increased proton conductivity at elevated temperatures when fully hydrated. Organic/inorganic hybrid membranes from acid-doped PBIs and other polymers are also discussed.

  17. Design and Development of Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cell

    NASA Astrophysics Data System (ADS)

    Kasat, Harshal Anil

    This work aimed to characterize and optimize the variables that influence the Gas Diffusion Layer (GDL) preparation using design of experiment (DOE) approach. In the process of GDL preparation, the quantity of carbon support and Teflon were found to have significant influence on the Proton Exchange Membrane Fuel Cell (PEMFC). Characterization methods like surface roughness, wetting characteristics, microstructure surface morphology, pore size distribution, thermal conductivity of GDLs were examined using laser interferometer, Goniometer, SEM, porosimetry and thermal conductivity analyzer respectively. The GDLs were evaluated in single cell PEMFC under various operating conditions of temperature and relative humidity (RH) using air as oxidant. Electrodes were prepared with different PUREBLACKRTM and poly-tetrafluoroethylene (PTFE) content in the diffusion layer and maintaining catalytic layer with a Pt-loading (0.4 mg cm-2). In the study, a 73.16 wt.% level of PB and 34 wt.% level of PTFE was the optimal compositions for GDL at 70°C for 70% RH under air atmosphere. For most electrochemical processes the oxygen reduction is very vita reaction. Pt loading in the electrocatalyst contributes towards the total cost of electrochemical devices. Reducing the Pt loading in electrocatalysts with high efficiency is important for the development of fuel cell technologies. To this end, this thesis work reports the approach to lower down the Pt loading in electrocatalyst based on N-doped carbon nanotubes derived from Zeolitic Imidazolate Frameworks (ZIF-67) for oxygen reduction. This electrocatalyst perform with higher electrocatalytic activity and stability for oxygen reduction in fuel cell testing. The electrochemical properties are mainly due to the synergistic effect from N-doped carbon nanotubes derived from ZIF and Pt loading. The strategy with low Pt loading forecasts in emerging highly active and less expensive electrocatalysts in electrochemical energy devices. This

  18. PEM (Proton exchange membrane) fuel cell stack heat and mass measurement

    SciTech Connect

    Vanderborgh, N.E.; Kimble, M.C.; Huff, J.R.; Hedstrom, J.C.

    1992-01-01

    PEM stacks are under evaluation as candidates for future space power technology. Results of long-term operation on a set of contemporary stacks fitted with different proton exchange membrane materials are given. Data on water balances show effects of membrane materials on stack performance. 15 refs.

  19. Proton exchange membrane fuel cell modeling and simulation using Ansys Fluent

    NASA Astrophysics Data System (ADS)

    Arvay, Adam

    Proton exchange membrane fuel cells (PEMFCs) run on pure hydrogen and oxygen (or air), producing electricity, water, and some heat. This makes PEMFC an attractive option for clean power generation. PEMFCs also operate at low temperature which makes them quick to start up and easy to handle. PEMFCs have several important limitations which must be overcome before commercial viability can be achieved. Active areas of research into making them commercially viable include reducing the cost, size and weight of fuel cells while also increasing their durability and performance. A growing and important part of this research involves the computer modeling of fuel cells. High quality computer modeling and simulation of fuel cells can help speed up the discovery of optimized fuel cell components. Computer modeling can also help improve fundamental understanding of the mechanisms and reactions that take place within the fuel cell. The work presented in this thesis describes a procedure for utilizing computer modeling to create high quality fuel cell simulations using Ansys Fluent 12.1. Methods for creating computer aided design (CAD) models of fuel cells are discussed. Detailed simulation parameters are described and emphasis is placed on establishing convergence criteria which are essential for producing consistent results. A mesh sensitivity study of the catalyst and membrane layers is presented showing the importance of adhering to strictly defined convergence criteria. A study of iteration sensitivity of the simulation at low and high current densities is performed which demonstrates the variance in the rate of convergence and the absolute difference between solution values derived at low numbers of iterations and high numbers of iterations.

  20. Single-wall carbon nanotube-based proton exchange membrane assembly for hydrogen fuel cells.

    PubMed

    Girishkumar, G; Rettker, Matthew; Underhile, Robert; Binz, David; Vinodgopal, K; McGinn, Paul; Kamat, Prashant

    2005-08-30

    A membrane electrode assembly (MEA) for hydrogen fuel cells has been fabricated using single-walled carbon nanotubes (SWCNTs) support and platinum catalyst. Films of SWCNTs and commercial platinum (Pt) black were sequentially cast on a carbon fiber electrode (CFE) using a simple electrophoretic deposition procedure. Scanning electron microscopy and Raman spectroscopy showed that the nanotubes and the platinum retained their nanostructure morphology on the carbon fiber surface. Electrochemical impedance spectroscopy (EIS) revealed that the carbon nanotube-based electrodes exhibited an order of magnitude lower charge-transfer reaction resistance (R(ct)) for the hydrogen evolution reaction (HER) than did the commercial carbon black (CB)-based electrodes. The proton exchange membrane (PEM) assembly fabricated using the CFE/SWCNT/Pt electrodes was evaluated using a fuel cell testing unit operating with H(2) and O(2) as input fuels at 25 and 60 degrees C. The maximum power density obtained using CFE/SWCNT/Pt electrodes as both the anode and the cathode was approximately 20% better than that using the CFE/CB/Pt electrodes.

  1. Development of novel proton exchange membrane fuel cells using stamped metallic bipolar plates

    NASA Astrophysics Data System (ADS)

    Jung, Shiauh-Ping; Lee, Chun-I.; Chen, Chi-Chang; Chang, Wen-Sheng; Yang, Chang-Chung

    2015-06-01

    This study presents the development of novel proton exchange membrane fuel cells using stamped metallic bipolar plates. To achieve uniformly distributed and low pressure-drop flow fields within fuel cells, a novel bipolar plate with straight channels is designed and verification of a fuel-cell short stack using this bipolar plate is performed. In the experiments, low-temperature and low-humidity operations and high-temperature and high-humidity operations are adopted to evaluate effects of stack temperature and inlet relative humidity on performance at various outlet pressures. Experimental results show that under low-temperature and low-humidity operations, increasing the outlet pressure enhances stack performance and reduces performance differences between various stack temperatures. Under high-temperature and high-humidity operations, stack performance increases with increasing outlet pressures, while the extent of their increase becomes smaller. Compared to low-temperature and low-humidity operations, high-temperature and high-humidity operations have better electrochemical reactions and membrane hydration and, thus, better stack performance. In this study, the operation with a stack temperature of 80 °C and outlet pressure of 4 atm produces the best performance of 1100 mA cm-2 at 0.646 V.

  2. Performance of gas diffusion layer from coconut waste for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Widodo, H.; Destyorini, F.; Insiyanda, D. R.; Subhan, A.

    2017-04-01

    The performance of Gas Diffusion Layer (GDL) synthesized from coconut waste. Gas Diffusion Layer (GDL), produced from coconut waste, as a part of Proton Exchange Membrane Fuel Cell (PEMFC) component, has been characterized. In order to know the performance, the commercial products were used as the remaining parts of PEMFC. The proposed GDL possesses 69% porosity for diffusion of Hydrogen fuel and Oxygen, as well as for transporting electron. With the electrical conductivity of 500 mS.cm-1, it also has hydrophobic properties, which is important to avoid the reaction with water, with the contact angle of 139°. The 5 × 5 cm2 GDL paper was co-assembled with the catalyst, Nafion membrane, bipolar plate, current collector, end plate to obtain single Stack PEMFC. The performance was examined by flowing fuel and gas with the flow rate of 500 and 1000 ml.min-1, respectively, and analyse the I-V polarization curve. The measurements were carried out at 30, 35, and 40°C for 5 cycles to ensure the repeatability. The results shows that the current density and the maximum power density reaches 203 mA.cm-2 and 143 mW.cm-2, respectively, with a given voltage 0.6 V, at 40°C.

  3. Performance improvement of proton exchange membrane fuel cell by using annular shaped geometry

    NASA Astrophysics Data System (ADS)

    Khazaee, I.; Ghazikhani, M.

    2011-03-01

    A complete three-dimensional and single phase CFD model for a different geometry of proton exchange membrane (PEM) fuel cell is used to investigate the effect of using different connections between bipolar plate and gas diffusion layer on the performances, current density and gas concentration. The proposed model is a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations are solved in a single domain; therefore no interfacial boundary condition is required at the internal boundaries between cell components. This computational fluid dynamics code is used as the direct problem solver, which is used to simulate the three-dimensional mass, momentum and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC that cannot be investigated experimentally. The results show that the predicted polarization curves by using this model are in good agreement with the experimental results. Also the results show that by increasing the number of connection between GDL and bipolar plate the performance of the fuel cell enhances.

  4. Design and simulation of novel flow field plate geometry for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ruan, Hanxia; Wu, Chaoqun; Liu, Shuliang; Chen, Tao

    2016-10-01

    Bipolar plate is one of the many important components of proton exchange membrane fuel cell (PEMFC) stacks as it supplies fuel and oxidant to the membrane-electrode assembly (MEA), removes water, collects produced current and provides mechanical support for the single cells in the stack. The flow field design of a bipolar plate greatly affects the performance of a PEMFC. It must uniformly distribute the reactant gases over the MEA and prevent product water flooding. This paper aims at improving the fuel cell performance by optimizing flow field designs and flow channel configurations. To achieve this, a novel biomimetic flow channel for flow field designs is proposed based on Murray's Law. Computational fluid dynamics based simulations were performed to compare three different designs (parallel, serpentine and biomimetic channel, respectively) in terms of current density distribution, power density distribution, pressure distribution, temperature distribution, and hydrogen mass fraction distribution. It was found that flow field designs with biomimetic flow channel perform better than that with convectional flow channel under the same operating conditions.

  5. A water and heat management model for proton-exchange-membrane fuel cells

    SciTech Connect

    Nguyen, T.V.; White, R.E. . Dept. of Chemical Engineering)

    1993-08-01

    Proper water and heat management are essential for obtaining high-power-density performance at high energy efficiency for proton-exchange-membrane fuel cells. A water and heat management model was developed and used to investigate the effectiveness of various humidification designs. The model accounts for water transport across the membrane by electro-osmosis and diffusion, heat transfer from the solid phase to the gas phase and latent heat associated with water evaporation and condensation in the flow channels. Results from the model showed that at high current (> 1A/cm[sup 2]) ohmic loss in the membrane accounts for a large fraction of the voltage loss in the cell and back diffusion of water from the cathode side of the membrane is insufficient to keep the membrane hydrated (i.e., conductive). Consequently, to minimize this ohmic loss the anode stream must be humidified, and when air is used instead of pure oxygen the cathode stream must also be humidified.

  6. Highly efficient sulfonated polybenzimidazole as a proton exchange membrane for microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Singha, Shuvra; Jana, Tushar; Modestra, J. Annie; Naresh Kumar, A.; Mohan, S. Venkata

    2016-06-01

    Although microbial fuel cells (MFCs) represent a promising bio-energy technology with a dual advantage (i.e., electricity production and waste-water treatment), their low power densities and high installation costs are major impediments. To address these bottlenecks and replace highly expensive Nafion, which is a proton exchange membrane (PEM), the current study focuses for the first time on membranes made from an easily synthesizable and more economical oxy-polybenzimidazole (OPBI) and its sulfonated analogue (S-OPBI) as alternate PEMs in single-chambered MFCs. The S-OPBI membrane exhibits better properties, with high water uptake, ion exchange capacity (IEC) and proton conductivity and a comparatively smaller degree of swelling compared to Nafion. The membrane morphology is characterized by atomic force microscopy, and the bright and dark regions of the S-OPBI membrane reveals the formation of ionic domains in the matrix, forming continuous water nanochannels when doped with water. These water-filled nanochannels are responsible for faster proton conduction in S-OPBI than in Nafion; therefore, the power output in the MFC with S-OPBI as the PEM is higher than in other MFCs. The open circuit voltage (460 mV), current generation (2.27 mA) and power density profile (110 mW/m2) as a function of time, as well as the polarization curves, exhibits higher current and power density (87.8 mW/m2) with S-OPBI compared to Nafion as the PEM.

  7. Numerical simulation of proton exchange membrane fuel cells at high operating temperature

    NASA Astrophysics Data System (ADS)

    Peng, Jie; Lee, Seung Jae

    A three-dimensional, single-phase, non-isothermal numerical model for proton exchange membrane (PEM) fuel cell at high operating temperature (T ≥ 393 K) was developed and implemented into a computational fluid dynamic (CFD) code. The model accounts for convective and diffusive transport and allows predicting the concentration of species. The heat generated from electrochemical reactions, entropic heat and ohmic heat arising from the electrolyte ionic resistance were considered. The heat transport model was coupled with the electrochemical and mass transport models. The product water was assumed to be vaporous and treated as ideal gas. Water transportation across the membrane was ignored because of its low water electro-osmosis drag force in the polymer polybenzimidazole (PBI) membrane. The results show that the thermal effects strongly affect the fuel cell performance. The current density increases with the increasing of operating temperature. In addition, numerical prediction reveals that the width and distribution of gas channel and current collector land area are key optimization parameters for the cell performance improvement.

  8. Detecting proton exchange membrane fuel cell hydrogen leak using electrochemical impedance spectroscopy method

    NASA Astrophysics Data System (ADS)

    Mousa, Ghassan; Golnaraghi, Farid; DeVaal, Jake; Young, Alan

    2014-01-01

    When a proton exchange membrane (PEM) fuel cell runs short of hydrogen, it suffers from a reverse potential fault that, when driven by neighboring cells, can lead to anode catalyst degradation and holes in the membrane due to local heat generation. As a result, hydrogen leaks through the electrically-shorted membrane-electrode assembly (MEA) without being reacted, and a reduction in fuel cell voltage is noticed. Such voltage reduction can be detected by using electrochemical impedance spectroscopy (EIS). To fully understand the reverse potential fault, the effect of hydrogen crossover leakage in a commercial MEA is measured by EIS at different differential pressures between the anode and cathode. Then the signatures of these leaky cells were compared with the signatures of a no-leaky cells at different oxygen concentrations with the same current densities. The eventual intent of this early stage work is to develop an on-board diagnostics system that can be used to detect and possibly prevent cell reversal failures, and to permit understanding the status of crossover or transfer leaks versus time in operation.

  9. Stereochemistry-Dependent Proton Conduction in Proton Exchange Membrane Fuel Cells.

    PubMed

    Thimmappa, Ravikumar; Devendrachari, Mruthyunjayachari Chattanahalli; Kottaichamy, Alagar Raja; Tiwari, Omshanker; Gaikwad, Pramod; Paswan, Bhuneshwar; Thotiyl, Musthafa Ottakam

    2016-01-12

    Graphene oxide (GO) is impermeable to H2 and O2 fuels while permitting H(+) shuttling, making it a potential candidate for proton exchange membrane fuel cells (PEMFC), albeit with a large anisotropy in their proton transport having a dominant in plane (σIP) contribution over the through plane (σTP). If GO-based membranes are ever to succeed in PEMFC, it inevitably should have a dominant through-plane proton shuttling capability (σTP), as it is the direction in which proton gets transported in a real fuel-cell configuration. Here we show that anisotropy in proton conduction in GO-based fuel cell membranes can be brought down by selectively tuning the geometric arrangement of functional groups around the dopant molecules. The results show that cis isomer causes a selective amplification of through-plane proton transport, σTP, pointing to a very strong geometry angle in ionic conduction. Intercalation of cis isomer causes significant expansion of GO (001) planes involved in σTP transport due to their mutual H-bonding interaction and efficient bridging of individual GO planes, bringing down the activation energy required for σTP, suggesting the dominance of a Grotthuss-type mechanism. This isomer-governed amplification of through-plane proton shuttling resulted in the overall boosting of fuel-cell performance, and it underlines that geometrical factors should be given prime consideration while selecting dopant molecules for bringing down the anisotropy in proton conduction and enhancing the fuel-cell performance in GO-based PEMFC.

  10. Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications

    PubMed Central

    Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T.C. Mike

    2015-01-01

    This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young’s modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO2• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications. PMID:26690232

  11. Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications.

    PubMed

    Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T C Mike

    2015-12-04

    This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young's modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO₂• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

  12. Prognostics of Proton Exchange Membrane Fuel Cells stack using an ensemble of constraints based connectionist networks

    NASA Astrophysics Data System (ADS)

    Javed, Kamran; Gouriveau, Rafael; Zerhouni, Noureddine; Hissel, Daniel

    2016-08-01

    Proton Exchange Membrane Fuel Cell (PEMFC) is considered the most versatile among available fuel cell technologies, which qualify for diverse applications. However, the large-scale industrial deployment of PEMFCs is limited due to their short life span and high exploitation costs. Therefore, ensuring fuel cell service for a long duration is of vital importance, which has led to Prognostics and Health Management of fuel cells. More precisely, prognostics of PEMFC is major area of focus nowadays, which aims at identifying degradation of PEMFC stack at early stages and estimating its Remaining Useful Life (RUL) for life cycle management. This paper presents a data-driven approach for prognostics of PEMFC stack using an ensemble of constraint based Summation Wavelet- Extreme Learning Machine (SW-ELM) models. This development aim at improving the robustness and applicability of prognostics of PEMFC for an online application, with limited learning data. The proposed approach is applied to real data from two different PEMFC stacks and compared with ensembles of well known connectionist algorithms. The results comparison on long-term prognostics of both PEMFC stacks validates our proposition.

  13. Superhydrophobic PAN nanofibers for gas diffusion layers of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Salahuddin, Mohammad; Hwang, Gisuk; Asmatulu, Ramazan

    2016-04-01

    Proton exchange membrane (PEM) fuel cells are considered to be the promising alternatives of natural resources for generating electricity and power. An optimal water management in the gas diffusion layers (GDL) is critical to high fuel cell performance. Its basic functions include transportation of the reactant gas from flow channels to catalyst effectively, draining out the liquid water from catalyst layer to flow channels, and conducting electrons with low humidity. In this study, polyacrylonitrile (PAN) was dissolved in a solvent and electrospun at various conditions to produce PAN nanofibers prior to the stabilization at 280 °C for 1 hour in the atmospheric pressure and carbonization at 850 °C for 1 hour. The surface hydrophobicity values of the carbonized PAN nanofibers were adjusted using superhydrophobic and hydrophilic agents. The thermal, mechanical, and electrical properties of the new GDLs depicted much better results compared to the conventionally used ones. The water condensation tests on the surfaces (superhydrophobic and hydrophilic) of the GDL showed a crucial step towards improved water managements in the fuel cell. This study may open up new possibilities for developing high- performing GDL materials for future PEM fuel cell applications.

  14. Contact behavior modelling and its size effect on proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Qiu, Diankai; Peng, Linfa; Yi, Peiyun; Lai, Xinmin; Janßen, Holger; Lehnert, Werner

    2017-10-01

    Contact behavior between the gas diffusion layer (GDL) and bipolar plate (BPP) is of significant importance for proton exchange membrane fuel cells. Most current studies on contact behavior utilize experiments and finite element modelling and focus on fuel cells with graphite BPPs, which lead to high costs and huge computational requirements. The objective of this work is to build a more effective analytical method for contact behavior in fuel cells and investigate the size effect resulting from configuration alteration of channel and rib (channel/rib). Firstly, a mathematical description of channel/rib geometry is outlined in accordance with the fabrication of metallic BPP. Based on the interface deformation characteristic and Winkler surface model, contact pressure between BPP and GDL is then calculated to predict contact resistance and GDL porosity as evaluative parameters of contact behavior. Then, experiments on BPP fabrication and contact resistance measurement are conducted to validate the model. The measured results demonstrate an obvious dependence on channel/rib size. Feasibility of the model used in graphite fuel cells is also discussed. Finally, size factor is proposed for evaluating the rule of size effect. Significant increase occurs in contact resistance and porosity for higher size factor, in which channel/rib width decrease.

  15. Multiple model predictive control for a hybrid proton exchange membrane fuel cell system

    NASA Astrophysics Data System (ADS)

    Chen, Qihong; Gao, Lijun; Dougal, Roger A.; Quan, Shuhai

    This paper presents a hierarchical predictive control strategy to optimize both power utilization and oxygen control simultaneously for a hybrid proton exchange membrane fuel cell/ultracapacitor system. The control employs fuzzy clustering-based modeling, constrained model predictive control, and adaptive switching among multiple models. The strategy has three major advantages. First, by employing multiple piecewise linear models of the nonlinear system, we are able to use linear models in the model predictive control, which significantly simplifies implementation and can handle multiple constraints. Second, the control algorithm is able to perform global optimization for both the power allocation and oxygen control. As a result, we can achieve the optimization from the entire system viewpoint, and a good tradeoff between transient performance of the fuel cell and the ultracapacitor can be obtained. Third, models of the hybrid system are identified using real-world data from the hybrid fuel cell system, and models are updated online. Therefore, the modeling mismatch is minimized and high control accuracy is achieved. Study results demonstrate that the control strategy is able to appropriately split power between fuel cell and ultracapacitor, avoid oxygen starvation, and so enhance the transient performance and extend the operating life of the hybrid system.

  16. Interim report re: component parts for proton-exchange membrane fuel cells

    SciTech Connect

    George Marchetti

    1999-10-01

    The purpose of the first phase of the grant project is to design, develop and test a simplified fuel cell electrode structure for use in proton-exchange membrane fuel cells (''PEMFC''). By simplifying the structure of the electrode, mass production manufacturing efficiencies can be brought into play which will result in significant cost reductions for this fuel cell component. With a reduction in the cost of this key fuel cell component overall costs for PEMFC's can be brought within the commercialization target range of about US$100 per kilowatt for the fuel cell stack. Fuel cell electrodes are necessarily ''multi-layered'' composites. Multi-layers are required because of the several functions that the electrode must be able to perform in the working PEM fuel cell. The current generation of state-of-the-art porous fuel cell electrodes for PEMFC's is comprised of three primary layers. The first layer is the catalyst layer. Since hydrogen is the fuel used in this project and air is used as the oxidant, the catalyst must be capable of adsorbing hydrogen and oxygen from the air. While work is constantly on-going with respect to new hydrogen or oxygen catalysts, the best available catalyst at present for both of the reactant gases is platinum. To be effective, the catalyst (1) must be exposed to a constant flow of the respective reactant gas; (2) must be in intimate contact with the proton-exchange membrane; and (3) must be a finely divided catalyst and have a large specific surface area, especially on the oxidant side where the electrochemical reaction is slower by several orders of magnitude. The second layer is the substrate layer. The substrate layer provides structural support for the finely divided catalyst. It also functions as an electronic junction for conducting electricity produced by the electrochemical reaction from the catalyst layer to the bipolar plate of the fuel cell. In state-of-the-art PEMFC's, this layer is comprised of carbon particles (onto which

  17. Investigation of high temperature operation of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Adjemian, Kevork Tro

    Proton exchange membrane fuel cells (PEMFCs) have garnered much attention in the media over the past years as they can provide a clean, environmentally friendly alternative to internal combustion engines. PEMFCs also have the flexibility to operate on many different types of fuels, thereby diminishing our reliance on foreign oil. PEMFCs, however, suffer from many drawbacks which need to be overcome before mass production becomes viable. One drawback is the expense of the fuel cell system, costing several times more than existing technologies. Another problem is that if the fuel cell is running on reformed fuels, trace amounts of carbon monoxide (10 ppm) in the hydrogen gas stream will completely poison the anode electrocatalyst, killing the PEMFC. Also, as a lot of waste heat is generated, a very elaborate cooling system needs to be used, making the overall system more expensive and complex. A possible solution to both the carbon monoxide poisoning and thermal management of a PEMFC is to elevate its operating temperature above 100°C. Unfortunately, current state-of-the-art electrolytes used in PEMFCs, i.e. Nafion 115, rely on water for the conduction of protons and by elevating the temperature, water loss occurs due to evaporation resulting in inadequate PEMFC performance. This thesis delves into the modification of Nafion and similar electrolytes to permit PEMFC operation above 100°C. This was accomplished by impregnating the pores of the Nafion with hydrophilic inorganic materials-silicon oxide via sol-gel processing and various inorganic particles. By performing these modifications to the various electrolytes, several composite membranes performed exceptionally well at an operating temperature of 130°C and demonstrated carbon monoxide tolerance of up to 500 ppm. In addition, a theory on how these materials help improve the water management characteristics of Nafion was developed, laying the foundation for the development of a completely novel membrane to

  18. Comparison of platinum/MWCNTs Nanocatalysts Synthesis Processes for Proton Exchange Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Liu, Xuan

    Due to the growing concerns on the depletion of petroleum based energy resources and climate change; fuel cell technologies have received much attention in recent years. Proton exchange membrane fuel cell (PEMFCs) features high energy conversion efficiency and nearly zero greenhouse gas emissions, because of its combination of the hydrogen oxidation reaction (HOR) at anode side and oxygen reduction reaction (ORR) at cathode side. Synthesis of Pt nanoparticles supported on multi walled carbon nanotubes (MWCNTs) possess a highly durable electrochemical surface area (ESA) and show good power output on proton exchange membrane (PEM) fuel cell performance. Platinum on multi-walled carbon nanotubes (MWCNTs) support were synthesized by two different processes to transfer PtCl62- from aqueous to organic phase. While the first method of Pt/MWCNTs synthesis involved dodecane thiol (DDT) and octadecane thiol (ODT) as anchoring agent, the second method used ammonium lauryl sulfate (ALS) as the dispersion/anchoring agent. The particle size and distribution of platinum were examined by high-resolution transmission electron microscope (HRTEM). The TEM images showed homogenous distribution and uniform particle size of platinum deposited on the surface of MWCNTs. The single cell fuel cell performance of the Pt/MWCNTs synthesized thiols and ALS based electrode containing 0.2 (anode) and 0.4 mg (cathode) Pt.cm-2 were evaluated using Nafion-212 electrolyte with H2 and O2 gases at 80 °C and ambient pressure. The catalyst synthesis with ALS is relatively simple compared to that with thiols and also showed higher performance (power density reaches about 1070 mW.cm -2). The Electrodes with Pt/MWCNTs nanocatalysts synthesized using ALS were characterized by cyclic voltammetry (CV) for durability evaluation using humidified H2 and N2 gases at room temperature (21 °C) along with commercial Pt/C for comparison. The ESA measured by cyclic voltammetry between 0.15 and 1.2 V showed significant

  19. A small portable proton exchange membrane fuel cell and hydrogen generator for medical applications.

    PubMed

    Adlhart, O J; Rohonyi, P; Modroukas, D; Driller, J

    1997-01-01

    Small, lightweight power sources for total artificial hearts (TAH), left ventricular assist devices (LVAD), and other medical products are under development. The new power source will provide 2 to 3 times the capacity of conventional batteries. The implications of this new power source are profound. For example, for the Heartmate LVAD, 5 to 8 hours of operation are obtained with 3 lb of lead acid batteries (Personal Communication Mr. Craig Sherman, Thermo Cardiosystems, Inc TCI 11/29/96). With the same weight, as much as 14 hours of operation appear achievable with the proton exchange membrane (PEM) fuel cell power source. Energy densities near 135 watt-hour/L are achievable. These values significantly exceed those of most conventional and advanced primary and secondary batteries. The improvement is mission dependent and even applies for the short deployment cited above. The comparison to batteries becomes even more favorable if the mission length is increased. The higher capacity requires only replacement of lightweight hydride cartridges and logistically available water. Therefore, when one spare 50 L hydride cartridge weighing 115 g is added to the reactant supply the energy density of the total system increases to 230 watt-hour/kg. This new power source is comprised of a hydrogen fueled, air-breathing PEM fuel cell and a miniature hydrogen generator (US Patent No 5,514,353). The fuel cell is of novel construction and differs from conventional bipolar PEM fuel cells by the arrangement of cells on a single sheet of ion-exchange membrane. The construction avoids the weight and volume penalty of conventional bipolar stacks. The hydrogen consumed by the fuel cell is generated load-responsively in the miniature hydrogen generator, by reacting calcium hydride with water, forming in the process hydrogen and lime. The generator is cartridge rechargeable and available in capacities providing up to several hundred watt-hours of electric power.

  20. High energy density proton exchange membrane fuel cell with dry reactant gases

    SciTech Connect

    Srinivasan, S.; Gamburzev, S.; Velev, O.A.

    1996-12-31

    Proton exchange membrane fuel cells (PEMFC) require careful control of humidity levels in the cell stack to achieve a high and stable level of performance. External humidification of the reactant gases, as in the state-of-the-art PEMFCs, increases the complexity, the weight, and the volume of the fuel cell power plant. A method for the operation of PEMFCs without external humidification (i.e., self-humidified PEMFCs) was first developed and tested by Dhar at BCS Technology. A project is underway in our Center to develop a PEMFC cell stack, which can work without external humidification and attain a performance level of a current density of 0.7 A/cm{sup 2} at a cell potential of 0.7 V, with hydrogen/air as reactants at 1 atm pressure. In this paper, the results of our efforts to design and develop a PEMFC stack requiring no external humidification will be presented. This paper focuses on determining the effects of type of electrodes, the methods of their preparation, as well as that of the membrane and electrode assembly (MEA), platinum loading and types of electrocatalyst on the performance of the PEMFC will be illustrated.

  1. A new stochastic algorithm for proton exchange membrane fuel cell stack design optimization

    NASA Astrophysics Data System (ADS)

    Chakraborty, Uttara

    2012-10-01

    This paper develops a new stochastic heuristic for proton exchange membrane fuel cell stack design optimization. The problem involves finding the optimal size and configuration of stand-alone, fuel-cell-based power supply systems: the stack is to be configured so that it delivers the maximum power output at the load's operating voltage. The problem apparently looks straightforward but is analytically intractable and computationally hard. No exact solution can be found, nor is it easy to find the exact number of local optima; we, therefore, are forced to settle with approximate or near-optimal solutions. This real-world problem, first reported in Journal of Power Sources 131, poses both engineering challenges and computational challenges and is representative of many of today's open problems in fuel cell design involving a mix of discrete and continuous parameters. The new algorithm is compared against genetic algorithm, simulated annealing, and (1+1)-EA. Statistical tests of significance show that the results produced by our method are better than the best-known solutions for this problem published in the literature. A finite Markov chain analysis of the new algorithm establishes an upper bound on the expected time to find the optimum solution.

  2. Proton Exchange Membrane Fuel Cell Engineering Model Powerplant. Test Report: Benchmark Tests in Three Spatial Orientations

    NASA Technical Reports Server (NTRS)

    Loyselle, Patricia; Prokopius, Kevin

    2011-01-01

    Proton exchange membrane (PEM) fuel cell technology is the leading candidate to replace the aging alkaline fuel cell technology, currently used on the Shuttle, for future space missions. This test effort marks the final phase of a 5-yr development program that began under the Second Generation Reusable Launch Vehicle (RLV) Program, transitioned into the Next Generation Launch Technologies (NGLT) Program, and continued under Constellation Systems in the Exploration Technology Development Program. Initially, the engineering model (EM) powerplant was evaluated with respect to its performance as compared to acceptance tests carried out at the manufacturer. This was to determine the sensitivity of the powerplant performance to changes in test environment. In addition, a series of tests were performed with the powerplant in the original standard orientation. This report details the continuing EM benchmark test results in three spatial orientations as well as extended duration testing in the mission profile test. The results from these tests verify the applicability of PEM fuel cells for future NASA missions. The specifics of these different tests are described in the following sections.

  3. An analytical model and parametric study of electrical contact resistance in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Wu, Zhiliang; Wang, Shuxin; Zhang, Lianhong; Hu, S. Jack

    This paper presents an analytical model of the electrical contact resistance between the carbon paper gas diffusion layers (GDLs) and the graphite bipolar plates (BPPs) in a proton exchange membrane (PEM) fuel cell. The model is developed based on the classical statistical contact theory for a PEM fuel cell, using the same probability distributions of the GDL structure and BPP surface profile as previously described in Wu et al. [Z. Wu, Y. Zhou, G. Lin, S. Wang, S.J. Hu, J. Power Sources 182 (2008) 265-269] and Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Results show that estimates of the contact resistance compare favorably with experimental data by Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Factors affecting the contact behavior are systematically studied using the analytical model, including the material properties of the two contact bodies and factors arising from the manufacturing processes. The transverse Young's modulus of chopped carbon fibers in the GDL and the surface profile of the BPP are found to be significant to the contact resistance. The factor study also sheds light on the manufacturing requirements of carbon fiber GDLs for a better contact performance in PEM fuel cells.

  4. Characterization techniques for gas diffusion layers for proton exchange membrane fuel cells - A review

    NASA Astrophysics Data System (ADS)

    Arvay, A.; Yli-Rantala, E.; Liu, C.-H.; Peng, X.-H.; Koski, P.; Cindrella, L.; Kauranen, P.; Wilde, P. M.; Kannan, A. M.

    2012-09-01

    The gas diffusion layer (GDL) in a proton exchange membrane fuel cell (PEMFC) is one of the functional components that provide a support structure for gas and water transport. The GDL plays a crucial role when the oxidant is air, especially when the fuel cell operates in the higher current density region. There has been an exponential growth in research and development because the PEMFC has the potential to become the future energy source for automotive applications. In order to serve in this capacity, the GDL requires due innovative analysis and characterization toward performance and durability. It is possible to achieve the optimum fuel cell performance only by understanding the characteristics of GDLs such as structure, pore size, porosity, gas permeability, wettability, thermal and electrical conductivities, surface morphology and water management. This review attempts to bring together the characterization techniques for the essential properties of the GDLs as handy tools for R&D institutions. Topics are categorized based on the ex-situ and in-situ characterization techniques of GDLs along with related modeling and simulation. Recently reported techniques used for accelerated durability evaluation of the GDLs are also consolidated within the ex-situ and in-situ methods.

  5. Binary and ternary nano-catalysts as cathode materials in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Trimm, Bryan Dunning

    The need for alternative energy, in order to reduce dependence on petroleum based fuels, has increased in recent years. Public demand is at an all-time high for low emitting or none polluting energy sources, driving the research for cleaner technology. Lithium batteries and fuel cells have the ability to produce this alternative energy with much cleaner standards, while allowing for portability and high energy densities. This work focuses on the performance of nanocatalysts in Proton Exchange Membrane Fuel Cell or PEMFC. A key technical challenge is the sluggish rate for oxygen reduction reaction at the cathode of PEMFC, which requires highly-active and stable catalysts. Our investigation is directed at increasing stability and durability as well as reducing high loading of noble metals in these catalyst materials. Binary and ternary structured nanomaterials, e.g., Pt51V1Co48/C and Pd xCu1-x/C, have been synthesized and tested in a PEMFC, in order to gain a better understanding of their durability and efficiency. In addition to electrochemical characterization, synchrotron x-ray techniques at the Advance Photon Source in Argonne National Lab have also been used for the structural characterization.

  6. Synthesis and characterization of Nafion/TiO2 nanocomposite membrane for proton exchange membrane fuel cell.

    PubMed

    Kim, Tae Young; Cho, Sung Yong

    2011-08-01

    In this study, the syntheses and characterizations of Nafion/TiO2 membranes for a proton exchange membrane fuel cell (PEMFC) were investigated. Porous TiO2 powders were synthesized using the sol-gel method; with Nafion/TiO2 nanocomposite membranes prepared using the casting method. An X-ray diffraction analysis demonstrated that the synthesized TiO2 had an anatase structure. The specific surface areas of the TiO2 and Nafion/TiO2 nanocomposite membrane were found to be 115.97 and 33.91 m2/g using a nitrogen adsorption analyzer. The energy dispersive spectra analysis indicated that the TiO2 particles were uniformly distributed in the nanocomposite membrane. The membrane electrode assembly prepared from the Nafion/TiO2 nanocomposite membrane gave the best PEMFC performance compared to the Nafion/P-25 and Nafion membranes.

  7. Impact of heat and water management on proton exchange membrane fuel cells degradation in automotive application

    NASA Astrophysics Data System (ADS)

    Nandjou, F.; Poirot-Crouvezier, J.-P.; Chandesris, M.; Blachot, J.-F.; Bonnaud, C.; Bultel, Y.

    2016-09-01

    In Proton Exchange Membrane Fuel Cells, local temperature is a driving force for many degradation mechanisms such as hygrothermal deformation and creep of the membrane, platinum dissolution and bipolar plates corrosion. In order to investigate and quantify those effects in automotive application, durability testing is conducted in this work. During the ageing tests, the local performance and temperature are investigated using in situ measurements of a printed circuit board. At the end of life, post-mortem analyses of the aged components are conducted. The experimental results are compared with the simulated temperature and humidity in the cell obtained from a pseudo-3D multiphysics model in order to correlate the observed degradations to the local conditions inside the stack. The primary cause of failure in automotive cycling is pinhole/crack formation in the membrane, induced by high variations of its water content over time. It is also observed that water condensation largely increases the probability of the bipolar plates corrosion while evaporation phenomena induce local deposits in the cell.

  8. Conducting polymer-coated corrosion resistant metallic bipolar plates for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Joseph, Shine

    2005-11-01

    Concerns over depleting stocks of natural resources and a growing awareness of the environmental damage caused by widespread burning of fossil fuels, and more energy demands brought the idea of alternative energy systems. Proton Exchange Membrane (PEM) fuel cells are one of the fast growing alternative energy technologies. PEM fuel cells generate electricity from an electrochemical reaction between hydrogen and oxygen and produce electricity, a small amount of heat and water and therefore, they are environmentally friendly. Fuel cells are more efficient than internal combustion engines and operate continuously as long as fuel is supplied from an external tank. Fuel cells in stacks are used for most applications because the current output of a PEM fuel cell is around 0.3--0.5 A/cm2. In fuel cell stacks, bipolar plates combine two cells in series with anode and cathode of adjacent cells. The main functions of bipolar plates are electron and gas transport. Bipolar plates are major components in weight and volume of the PEM fuel cell stack and are a significant contributor to the stack cost. The bipolar plate is therefore a key component if power density is to increase and cost to come down. Bipolar plate material should be corrosion resistant, conductive, gas impermeable, light weight (mobile applications) and economical. Graphite plates are used for bipolar plate applications but they are expensive, are brittle to make in thin plates with gas channels on sides, have high manufacturing cost and are gas permeable if too thin. Metals are preferable for bipolar plate application because of better mechanical properties, higher electrical conductivity, lower gas permeability and low cost. In this work Al 6061 and 304 stainless steel alloys are the materials selected for bipolar plates. These metals form non-conductive surface oxides in a PEM fuel cell environment and cause a high contact resistance. This internal resistance lowers the efficiency of PEM fuel cell system. In

  9. Pt nanoparticle-dispersed graphene-wrapped MWNT composites as oxygen reduction reaction electrocatalyst in proton exchange membrane fuel cell.

    PubMed

    Aravind, S S Jyothirmayee; Ramaprabhu, Sundara

    2012-08-01

    Chemical and electrical synergies between graphite oxide and multiwalled carbon nanotube (MWNT) for processing graphene wrapped-MWNT hybrids has been realized by chemical vapor deposition without any chemical functionalization. Potential of the hybrid composites have been demonstrated by employing them as electrocatalyst supports in proton exchange membrane fuel cells. The defects present in the polyelectrolyte, which have been wrapped over highly dispersed MWNT, act as anchoring sites for the homogeneous deposition of platinum nanoparticles. Single-cell proton exchange membrane fuel cells show that the power density of the hybrid composite-based fuel cells is higher compared to the pure catalyst-support-based fuel cells, because of enhanced electrochemical reactivity and good surface area of the nanocomposites.

  10. The detection of palladium particles in proton exchange membrane fuel-cell water by laser-induced breakdown spectroscopy (LIBS).

    PubMed

    Snyder, Stuart C; Wickun, William G; Mode, Jeremy M; Gurney, Brian D; Michels, Fred G

    2011-06-01

    Laser-induced breakdown spectroscopy (LIBS) using conditional data analysis was applied to aqueous suspensions of palladium particles in the reformate water of palladium-based proton exchange membrane fuel cells. A significant amount of palladium was found in the water, indicating degradation of the fuel-cell cathode catalytic layers. The palladium particle-size detection limit was found to be about 400 nm. Calibration procedures to quantify the palladium concentration are discussed.

  11. Graphene oxide based nanohybrid proton exchange membranes for fuel cell applications: An overview.

    PubMed

    Pandey, Ravi P; Shukla, Geetanjali; Manohar, Murli; Shahi, Vinod K

    2017-02-01

    In the context of many applications, such as polymer composites, energy-related materials, sensors, 'paper'-like materials, field-effect transistors (FET), and biomedical applications, chemically modified graphene was broadly studied during the last decade, due to its excellent electrical, mechanical, and thermal properties. The presence of reactive oxygen functional groups in the grapheme oxide (GO) responsible for chemical functionalization makes it a good candidate for diversified applications. The main objectives for developing a GO based nanohybrid proton exchange membrane (PEM) include: improved self-humidification (water retention ability), reduced fuel crossover (electro-osmotic drag), improved stabilities (mechanical, thermal, and chemical), enhanced proton conductivity, and processability for the preparation of membrane-electrode assembly. Research carried on this topic may be divided into protocols for covalent grafting of functional groups on GO matrix, preparation of free-standing PEM or choice of suitable polymer matrix, covalent or hydrogen bonding between GO and polymer matrix etc. Herein, we present a brief literature survey on GO based nano-hybrid PEM for fuel cell applications. Different protocols were adopted to produce functionalized GO based materials and prepare their free-standing film or disperse these materials in various polymer matrices with suitable interactions. This review article critically discussed the suitability of these PEMs for fuel cell applications in terms of the dependency of the intrinsic properties of nanohybrid PEMs. Potential applications of these nanohybrid PEMs, and current challenges are also provided along with future guidelines for developing GO based nanohybrid PEMs as promising materials for fuel cell applications.

  12. Proton exchange membrane materials for the advancement of direct methanol fuel-cell technology

    DOEpatents

    Cornelius, Christopher J.

    2006-04-04

    A new class of hybrid organic-inorganic materials, and methods of synthesis, that can be used as a proton exchange membrane in a direct methanol fuel cell. In contrast with Nafion.RTM. PEM materials, which have random sulfonation, the new class of materials have ordered sulfonation achieved through self-assembly of alternating polyimide segments of different molecular weights comprising, for example, highly sulfonated hydrophilic PDA-DASA polyimide segment alternating with an unsulfonated hydrophobic 6FDA-DAS polyimide segment. An inorganic phase, e.g., 0.5 5 wt % TEOS, can be incorporated in the sulfonated polyimide copolymer to further improve its properties. The new materials exhibit reduced swelling when exposed to water, increased thermal stability, and decreased O.sub.2 and H.sub.2 gas permeability, while retaining proton conductivities similar to Nafion.RTM.. These improved properties may allow direct methanol fuel cells to operate at higher temperatures and with higher efficiencies due to reduced methanol crossover.

  13. Ex-situ characterisation of gas diffusion layers for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    El-kharouf, Ahmad; Mason, Thomas J.; Brett, Dan J. L.; Pollet, Bruno G.

    2012-11-01

    This paper presents the first part of a complete ex-situ characterisation of a wide range of commercial Gas Diffusion Layers (GDLs) used in low temperature and high temperature Proton Exchange Membrane (PEM) fuel cells. Physical and electrical characteristics of the GDLs are reported. The results show that the substrate structure has a significant effect on the mechanical and electrical properties of the GDL. Moreover, the Micro Porous Layer (MPL) structure determines the roughness of the surface, and affects the permeability and porosity of the GDL. It was found that the substrate treatment with PTFE affects the GDL characteristics; PTFE loading increases the GDLs hydrophobicity and permeability, however, decreases its overall porosity and resistivity. Adding a MPL to the substrate, results in a decrease in porosity and permeability and an increase in resistivity. The contact resistance of the GDL and the bipolar plate increases when the GDL thickness and PTFE loading are increased. This technical paper shows a close relationship between GDL materials and their physical characteristics and highlights the importance of optimising GDLs for fuel cell applications.

  14. A review of fault tolerant control strategies applied to proton exchange membrane fuel cell systems

    NASA Astrophysics Data System (ADS)

    Dijoux, Etienne; Steiner, Nadia Yousfi; Benne, Michel; Péra, Marie-Cécile; Pérez, Brigitte Grondin

    2017-08-01

    Fuel cells are powerful systems for power generation. They have a good efficiency and do not generate greenhouse gases. This technology involves a lot of scientific fields, which leads to the appearance of strongly inter-dependent parameters. This makes the system particularly hard to control and increases fault's occurrence frequency. These two issues call for the necessity to maintain the system performance at the expected level, even in faulty operating conditions. It is called ;fault tolerant control; (FTC). The present paper aims to give the state of the art of FTC applied to the proton exchange membrane fuel cell (PEMFC). The FTC approach is composed of two parts. First, a diagnosis part allows the identification and the isolation of a fault; it requires a good a priori knowledge of all the possible faults. Then, a control part allows an optimal control strategy to find the best operating point to recover/mitigate the fault; it requires the knowledge of the degradation phenomena and their mitigation strategies.

  15. Operating proton exchange membrane fuel cells without external humidification of the reactant gases

    SciTech Connect

    Buechi, F.N.; Srinivasan, S.

    1997-08-01

    Operation of proton exchange membrane fuel cells (PEMFC) without external humidification of the reactant gases is advantageous for the PEMFC system, because it eliminates the need for a gas-humidification subsystem. The gas-humidification subsystem is a burden in the fuel cell system with respect to weight, complexity, cost, and parasitic power. A model for the operation of PEMFC with internal humidification of the gases is presented and the range of operating conditions for a PEMFC using dry H{sub 2}/air was investigated. The model predicts that dry air, entering at the cathode, can be fully internally humidified by the water produced by the electrochemical reaction at temperatures up to 70 C. This model was experimentally verified for cell temperatures up to 60 C by long-term operation of a PEMFC with dry gases for up to 1,800 h. The current densities, obtained at 0.6 V, were 20 to 40% lower than those measured when both gases were humidified. The water distribution in the cell, while operating with dry gases, was investigated by measuring the amount of product water on the anode and cathode sides. It was found that the back-diffusion of product water to the anode is the dominant process for water management in the cell over a wide range of operating conditions. The dominating water back-diffusion also allows internal humidification of the hydrogen reactant and prevents drying out of the anode.

  16. Proton Exchange Membrane fuel cell development with lightweight component materials, phase 1

    NASA Astrophysics Data System (ADS)

    Abens, Sandors

    1995-07-01

    Although the Proton Exchange Membrane (PEM) fuel cell is a leading candidate for an automobile power source through meeting the zero emission requirement, its power density is currently an order of magnitude below the 400 W/kg criterion proposed by the Department of Energy. The major contributors to stack weight are the bipolar gas distribution plates. This effort, performed jointly by Energy Research Corporation (ERC) and Texas A&M University (TAM U), focused on lightweight alternative bipolar plate materials and designs. The electronic conductivity of various candidate materials was evaluated. The emphasis was on conductive plastic materials and porous graphite. Several plastic materials with specific resistance between 0.5 and 0.8 ohm/cm were identified. Preliminary evaluation of lightweight materials was performed in single cell tests. The emphasis was on atmospheric pressure and internally humidified cell operation as a potential means of system simplification and reduction of PEM fuel cell ancillary equipment complexity and weight. The performance of single cells was nearly the same at 1 and 3 atm pressure. At a cell potential of O.6V, a current density of 230 mA/sq cm was reached at 1.7 stoichiometric air flow rate. With lightweight bipolar plates, the DOE power density target may be achieved with unpressurized, internally humidified cell stacks.

  17. Recovery mechanisms in proton exchange membrane fuel cells after accelerated stress tests

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Guo, Liejin; Liu, Hongtan

    2015-11-01

    The mechanisms of performance recovery after accelerated stress test (AST) in proton exchange membrane fuel cells (PEMFCs) are systematically studied. Experiments are carried out by incorporating a well-designed performance recovery procedure right after the AST protocol. The experiment results show that the cell performance recovers significantly from the degraded state after the AST procedure. The results from cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements further show that the performance recovery can be divided into kinetic and mass transport recoveries. It is further determined that the kinetic recovery, i.e. the recovery of electrochemical active area (ECA), is due to two distinct mechanisms: the reduction of platinum oxide and the re-attachment of detached platinum nanoparticles onto the carbon surface. The mass transport resistance is probably due to reduction of hydrophilic oxide groups on the carbon surface and the microstructure change that alleviates flooding. Performance comparisons show that the recovery procedure is highly effective, indicating the results of AST significantly over-estimate the true degradation in a PEM fuel cell. Therefore, a recovery procedure is highly recommended when an AST protocol is used to evaluate cell degradations to avoid over-estimating true performance degradations in PEMFCs.

  18. Photochemically modified ATO NPs as conductive support of Pt electrocatalysts for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ostrovsky, Stella; Larsen, Mikkel Juul; Peled, Anna; Lellouche, Jean-Paul

    2015-06-01

    Antimony-doped tin oxide (ATO) nanoparticles (NPs) were covalently modified with a benzophenone-silicate photoreactive organic molecule to enable the UV-mediated photoreduction of Pt(IV) on the surface of the ATO NPs to give Pt(0) NPs. The successfully synthesized Pt/ATO nanocomposites (NCs) that were based on these novel hybrid photoreactive ATO NPs showed a much better Pt dispersion than Pt/ATO NCs prepared by traditional methods. The size of the Pt NPs was below 2.8 nm for all the NCs. The prepared NCs were studied with respect to their properties as durable and active electrocatalysts for proton exchange membrane fuel cells. They were subjected to fuel-cell-relevant electrochemical characterization by rotating disc electrode cyclic voltammetry. The electrochemically active surface area was found to be significantly lower for the novel NCs than for the standard Pt/C catalyst, while on the other hand, their specific electrocatalytic activity towards the oxygen reduction reaction (ORR) was found to exceed that of the reference Pt/C by several times. The ORR activity in terms of the mass of Pt was comparable to, or greater than, that of the Pt/C. The stability towards electrochemical ageing was greatly improved for Pt/ATO NCs relative to Pt/C.

  19. Developing a 3D neutron tomography method for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Tang, Hong-Yue; Santamaria, Anthony; Kurniawan, Jonathan; Park, Jae Wan; Yang, Tae-Hyun; Sohn, Young-Jun

    Fuel cell visualization is an ongoing challenge in the world of hydrogen-based research. Neutron tomography is a powerful tool for acquiring otherwise unattainable information about the inner workings of a proton exchange membrane fuel cell. Advanced neutron imaging methods allow for validation of both cell design and run methods. The tomography techniques discussed in this paper show how 3D visualization provides a clear view of flow channel activity for water management analysis. A brief intro to tomography is explained via its mathematical construction, outlining how 2D radiographs can be reconstructed and layered to form 3D visualizations. The low attenuation aluminum cell designs used for imaging are described focusing on how they are specifically tailored for neutron tomography. Images of the flow channel and water distributions are shown in cross-sections throughout the cell, both perpendicular and along the channel length. Finally, 3D tomography images of the cell are shown, with the bipolar aluminum plates signal subtracted revealing a 3D water distribution of both cathode and anode layers.

  20. Chlorobenzene Poisoning and Recovery of Platinum-Based Cathodes in Proton Exchange Membrane Fuel Cells.

    PubMed

    Zhai, Yunfeng; Baturina, Olga; Ramaker, David; Farquhar, Erik; St-Pierre, Jean; Swider-Lyons, Karen

    2015-09-03

    The platinum electrocatalysts found in proton exchange membrane fuel cells are poisoned both reversibly and irreversibly by air pollutants and residual manufacturing contaminants. In this work, the poisoning of a Pt/C PEMFC cathode was probed by a trace of chlorobenzene in the air feed. Chlorobenzene inhibits the oxygen reduction reaction and causes significant cell performance loss. The performance loss is largely restored by neat air operation and potential cycling between 0.08 V and 1.2 V under H2/N2 (anode/cathode). The analysis of emissions, in situ X-ray absorption spectroscopy and electrochemical impedance spectra show the chlorobenzene adsorption/reaction and molecular orientation on Pt surface depend on the electrode potential. At low potentials, chlorobenzene deposits either on top of adsorbed H atoms or on the Pt surface via the benzene ring and is converted to benzene (ca. 0.1 V) or cyclohexane (ca. 0 V) upon Cl removal. At potentials higher than 0.2 V, chlorobenzene binds to Pt via the Cl atom and can be converted to benzene (less than 0.3 V) or desorbed. Cl(-) is created and remains in the membrane electrode assembly. Cl(-) binds to the Pt surface much stronger than chlorobenzene, but can slowly be flushed out by liquid water.

  1. Chlorobenzene Poisoning and Recovery of Platinum-Based Cathodes in Proton Exchange Membrane Fuel Cells

    PubMed Central

    Zhai, Yunfeng; Baturina, Olga; Ramaker, David; Farquhar, Erik; St-Pierre, Jean; Swider-Lyons, Karen

    2015-01-01

    The platinum electrocatalysts found in proton exchange membrane fuel cells are poisoned both reversibly and irreversibly by air pollutants and residual manufacturing contaminants. In this work, the poisoning of a Pt/C PEMFC cathode was probed by a trace of chlorobenzene in the air feed. Chlorobenzene inhibits the oxygen reduction reaction and causes significant cell performance loss. The performance loss is largely restored by neat air operation and potential cycling between 0.08 V and 1.2 V under H2/N2 (anode/cathode). The analysis of emissions, in situ X-ray absorption spectroscopy and electrochemical impedance spectra show the chlorobenzene adsorption/reaction and molecular orientation on Pt surface depend on the electrode potential. At low potentials, chlorobenzene deposits either on top of adsorbed H atoms or on the Pt surface via the benzene ring and is converted to benzene (ca. 0.1 V) or cyclohexane (ca. 0 V) upon Cl removal. At potentials higher than 0.2 V, chlorobenzene binds to Pt via the Cl atom and can be converted to benzene (less than 0.3 V) or desorbed. Cl− is created and remains in the membrane electrode assembly. Cl− binds to the Pt surface much stronger than chlorobenzene, but can slowly be flushed out by liquid water. PMID:26388963

  2. Two-phase flow and transport in the air cathode of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Z. H.; Wang, C. Y.; Chen, K. S.

    Two-phase flow and transport of reactants and products in the air cathode of proton exchange membrane (PEM) fuel cells is studied analytically and numerically. Single- and two-phase regimes of water distribution and transport are classified by a threshold current density corresponding to first appearance of liquid water at the membrane/cathode interface. When the cell operates above the threshold current density, liquid water appears and a two-phase zone forms within the porous cathode. A two-phase, multicomponent mixture model in conjunction with a finite-volume-based computational fluid dynamics (CFD) technique is applied to simulate the cathode operation in this regime. The model is able to handle the situation where a single-phase region co-exists with a two-phase zone in the air cathode. For the first time, the polarization curve as well as water and oxygen concentration distributions encompassing both single- and two-phase regimes of the air cathode are presented. Capillary action is found to be the dominant mechanism for water transport inside the two-phase zone of the hydrophilic structure. The liquid water saturation within the cathode is predicted to reach 6.3% at 1.4 A cm -2 for dry inlet air.

  3. Experimental study of a novel piezoelectric proton exchange membrane fuel cell with nozzle and diffuser

    NASA Astrophysics Data System (ADS)

    Ma, Hsiao-Kang; Huang, Shih-Han; Wang, Jyun-Sheng; Hou, Churng-Guang; Yu, Chen-Chiang; Chen, Bo-Ren

    The newly designed proton exchange membrane fuel cell with a piezoelectric actuation structure, called a PZT-PEMFC, can force air into an air-breathing PEMFC system. Previous studies indicated the PZT-PEMFC may solve the water-flooding problem and improve cell performance. In this experimental study, a PZT-PEMFC with nozzle and diffuser, PZT-PEMFC-ND, is built to verify the previous theoretical study. This innovative design may direct air flow into the cathode channel through the diffuser and prevent air backflow without valves. The performance test includes an analysis of PZT vibration frequencies, cell operation temperatures, gravity effect, and designs of the nozzle and diffuser. The optimal operating temperature for the PZT-PEMFC-ND is 323 K to avoid the risk of higher temperatures drying out the membrane electrode assembly (MEA). The optimal vibration frequency of the PZT-PEMFC-ND is 180 Hz, which may pump in enough air and solve the water-flooding problem in the cathode channel. This study also concludes that the innovative design of the PZT-PEMFC-ND, may reach the performance of an open cathode stack configuration, 0.18 W cm -2, without an external air supply device.

  4. Epoxy-crosslinked sulfonated poly (phenylene) copolymer proton exchange membranes

    DOEpatents

    Hibbs, Michael; Fujimoto, Cy H.; Norman, Kirsten; Hickner, Michael A.

    2010-10-19

    An epoxy-crosslinked sulfonated poly(phenylene) copolymer composition used as proton exchange membranes, methods of making the same, and their use as proton exchange membranes (PEM) in hydrogen fuel cells, direct methanol fuel cell, in electrode casting solutions and electrodes, and in sulfur dioxide electrolyzers. These improved membranes are tougher, have higher temperature capability, and lower SO.sub.2 crossover rates.

  5. Analysis and Test of a Proton Exchange Membrane Fuel Cell Power System for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Vasquez, Arturo; Varanauski, Donald; Clark, Robert, Jr.

    2000-01-01

    An effort is underway to develop a prototype Proton Exchange Membrane (PEM) Fuel Cell breadboard system for fuhlre space applications. This prototype will be used to develop a comprehensive design basis for a space-rated PEM fuel cell powerplant. The prototype system includes reactant pressure regulators, ejector-based reactant pumps, a 4-kW fuel cell stack and cooling system, and a passive, membranebased oxygen / water separator. A computer model is being developed concurrently to analytically predict fluid flow in the oxidant reactant system. Fuel cells have historically played an important role in human-rated spacecraft. The Gemini and Apollo spacecraft used fuel cells for vehicle electrical power. The Space Shuttle currently uses three Alkaline Fuel Cell Powerplants (AFCP) to generate all of the vehicle's 15-20kW electrical power. Engineers at the Johnson Space Center have leveraged off the development effort ongoing in the commercial arena to develop PEM fuel cel ls for terrestrial uses. The prototype design originated from efforts to develop a PEM fuel cell replacement for the current Space Shuttle AFCP' s. In order to improve on the life and an already excellent hi storical record of reliability and safety, three subsystems were focused on. These were the fuel cell stack itself, the reactant circulation devices, and reactant / product water separator. PEM fuel cell stack performance is already demonstrating the potential for greater than four times the useful life of the current Shuttle's AFCP. Reactant pumping for product water removal has historically been accomplished with mechanical pumps. Ejectors offer an effective means of reactant pumping as well as the potential for weight reduction, control simplification, and long life. Centrifugal water separation is used on the current AFCP. A passive, membrane-based water separator offers compatibility with the micro-gravity environment of space, and the potential for control simplification, elimination of

  6. Conceptual design report for a Direct Hydrogen Proton Exchange Membrane Fuel Cell for transportation application

    SciTech Connect

    1995-09-05

    This report presents the conceptual design for a Direct-Hydrogen-Fueled Proton Exchange Membrane (PEM) Fuel Cell System for transportation applications. The design is based on the initial selection of the Chrysler LH sedan as the target vehicle with a 50 kW (gross) PEM Fuel Cell Stack (FCS) as the primary power source, a battery-powered Load Leveling Unit (LLU) for surge power requirements, an on-board hydrogen storage subsystem containing high pressure gaseous storage, a Gas Management Subsystem (GMS) to manage the hydrogen and air supplies for the FCS, and electronic controllers to control the electrical system. The design process has been dedicated to the use of Design-to-Cost (DTC) principles. The Direct Hydrogen-Powered PEM Fuel Cell Stack Hybrid Vehicle (DPHV) system is designed to operate on the Federal Urban Driving Schedule (FUDS) and Hiway Cycles. These cycles have been used to evaluate the vehicle performance with regard to range and hydrogen usage. The major constraints for the DPHV vehicle are vehicle and battery weight, transparency of the power system and drive train to the user, equivalence of fuel and life cycle costs to conventional vehicles, and vehicle range. The energy and power requirements are derived by the capability of the DPHV system to achieve an acceleration from 0 to 60 MPH within 12 seconds, and the capability to achieve and maintain a speed of 55 MPH on a grade of seven percent. The conceptual design for the DPHV vehicle is shown in a figure. A detailed description of the Hydrogen Storage Subsystem is given in section 4. A detailed description of the FCS Subsystem and GMS is given in section 3. A detailed description of the LLU, selection of the LLU energy source, and the power controller designs is given in section 5.

  7. Channel geometric scales effect on performance and optimization for serpentine proton exchange membrane fuel cell (PEMFC)

    NASA Astrophysics Data System (ADS)

    Youcef, Kerkoub; Ahmed, Benzaoui; Ziari, Yasmina; Fadila, Haddad

    2017-02-01

    A three dimensional computational fluid dynamics model is proposed in this paper to investigate the effect of flow field design and dimensions of bipolar plates on performance of serpentine proton exchange membrane fuel cell (PEMFC). A complete fuel cell of 25 cm2 with 25 channels have been used. The aim of the work is to investigate the effect of flow channels and ribs scales on overall performance of PEM fuel cell. Therefore, geometric aspect ratio parameter defined as (width of flow channel/width of rib) is used. Influences of the ribs and openings current collector scales have been studied and analyzed in order to find the optimum ratio between them to enhance the production of courant density of PEM fuel cell. Six kind of serpentine designs have been used in this paper included different aspect ratio varying from 0.25 to 2.33 while the active surface area and number of channels are keeping constant. Aspect ratio 0.25 corresponding of (0.4 mm channel width/ 1.6mm ribs width), and Aspect ratio2.33 corresponding of (0.6 mm channel width/ 1.4mm ribs width. The results show that the best flow field designs (giving the maximum density of current) are which there dimensions of channels width is minimal and ribs width is maximal (Γ≈0.25). Also decreasing width of channels enhance the pressure drop inside the PEM fuel cell, this causes an increase of gazes velocity and enhance convection process, therefore more power generation.

  8. Membrane patterned by pulsed laser micromachining for proton exchange membrane fuel cell with sputtered ultra-low catalyst loadings

    NASA Astrophysics Data System (ADS)

    Cuynet, S.; Caillard, A.; Kaya-Boussougou, S.; Lecas, T.; Semmar, N.; Bigarré, J.; Buvat, P.; Brault, P.

    2015-12-01

    Proton exchange membranes were nano- and micro-patterned on their cathode side by pressing them against stainless steel molds previously irradiated by a Ti:Sapphire femtosecond laser. The membranes were associated to ultra-low loaded thin catalytic layers (25 μgPt cm-2) prepared by plasma magnetron sputtering. The Pt catalyst was sputtered either on the membrane or on the porous electrode. The fuel cell performance in dry conditions were found to be highly dependent on the morphology of the membrane surface. When nanometric ripples covered by a Pt catalyst were introduced on the surface of the membrane, the fuel cell outperformed the conventional one with a flat membrane. By combining nano- and micro-patterns (nanometric ripples and 11-24 μm deep craters), the performance of the cells was clearly enhanced. The maximum power density achieved by the fuel cell was multiplied by a factor of 3.6 (at 50 °C and 3 bar): 438 mW cm-2 vs 122 mW cm-2. This improvement is due to high catalyst utilization with a high membrane conductivity. When Pt is sputtered on the porous electrode (and not on the membrane), the contribution of the patterned membrane to the fuel cell efficiency was less significant, except in the presence of nanometric ripples. This result suggests that the patterning of the membrane must be consistent with the way the catalyst is synthesized, on the membrane or on the porous electrode.

  9. Transient computation fluid dynamics modeling of a single proton exchange membrane fuel cell with serpentine channel

    NASA Astrophysics Data System (ADS)

    Hu, Guilin; Fan, Jianren

    The proton exchange membrane fuel cell (PEMFC) has become a promising candidate for the power source of electrical vehicles because of its low pollution, low noise and especially fast startup and transient responses at low temperatures. A transient, three-dimensional, non-isothermal and single-phase mathematical model based on computation fluid dynamics has been developed to describe the transient process and the dynamic characteristics of a PEMFC with a serpentine fluid channel. The effects of water phase change and heat transfer, as well as electrochemical kinetics and multicomponent transport on the cell performance are taken into account simultaneously in this comprehensive model. The developed model was employed to simulate a single laboratory-scale PEMFC with an electrode area about 20 cm 2. The dynamic behavior of the characteristic parameters such as reactant concentration, pressure loss, temperature on the membrane surface of cathode side and current density during start-up process were computed and are discussed in detail. Furthermore, transient responses of the fuel cell characteristics during step changes and sinusoidal changes in the stoichiometric flow ratio of the cathode inlet stream, cathode inlet stream humidity and cell voltage are also studied and analyzed and interesting undershoot/overshoot behavior of some variables was found. It was also found that the startup and transient response time of a PEM fuel cell is of the order of a second, which is similar to the simulation results predicted by most models. The result is an important guide for the optimization of PEMFC designs and dynamic operation.

  10. Computational modeling of intermediate temperature proton exchange membrane (PEM) fuel cells

    NASA Astrophysics Data System (ADS)

    Cheddie, Denver Faron

    A two-phase three-dimensional computational model of an intermediate temperature (120--190°C) proton exchange membrane (PEM) fuel cell is presented. This represents the first attempt to model PEM fuel cells employing intermediate temperature membranes, in this case, phosphoric acid doped polybenzimidazole (PBI). To date, mathematical modeling of PEM fuel cells has been restricted to low temperature operation, especially to those employing Nafion RTM membranes; while research on PBI as an intermediate temperature membrane has been solely at the experimental level. This work is an advancement in the state of the art of both these fields of research. With a growing trend toward higher temperature operation of PEM fuel cells, mathematical modeling of such systems is necessary to help hasten the development of the technology and highlight areas where research should be focused. This mathematical model accounted for all the major transport and polarization processes occurring inside the fuel cell, including the two phase phenomenon of gas dissolution in the polymer electrolyte. Results were presented for polarization performance, flux distributions, concentration variations in both the gaseous and aqueous phases, and temperature variations for various heat management strategies. The model predictions matched well with published experimental data, and were self-consistent. The major finding of this research was that, due to the transport limitations imposed by the use of phosphoric acid as a doping agent, namely low solubility and diffusivity of dissolved gases and anion adsorption onto catalyst sites, the catalyst utilization is very low (˜1--2%). Significant cost savings were predicted with the use of advanced catalyst deposition techniques that would greatly reduce the eventual thickness of the catalyst layer, and subsequently improve catalyst utilization. The model also predicted that an increase in power output in the order of 50% is expected if alternative doping

  11. Modeling of cold start processes and performance optimization for proton exchange membrane fuel cell stacks

    NASA Astrophysics Data System (ADS)

    Zhou, Yibo; Luo, Yueqi; Yu, Shuhai; Jiao, Kui

    2014-02-01

    In this study, a cold start model for proton exchange membrane fuel cell (PEMFC) stacks is developed, and a novel start-up method, variable heating and load control (VHLC), is proposed and evaluated. The main idea is to only apply load to the neighboring still-active cells, and to apply external heating to certain cells inside the stack simultaneously (load is not applied to the cells fully blocked by ice, although these cells can gain heat from neighboring cells). With the VHLC method, it is found that the stack voltage first increases, then decreases due to the full blockage of ice in some of the individual cells, and finally the dead cells are heated by the other active cells and activated again one by one. Based on this method, the external heating power and the stack self-heating ability are utilized more efficiently. With proper implementation of the VHLC method, it is demonstrated that the cold stat performance can be improved significantly, which is critically important for PEMFC in automotive applications.

  12. Carbon composite bipolar plate for high-temperature proton exchange membrane fuel cells (HT-PEMFCs)

    NASA Astrophysics Data System (ADS)

    Lee, Dongyoung; Lee, Dai Gil

    2016-09-01

    A carbon/epoxy composite bipolar plate is an ideal substitute for the brittle graphite bipolar plate for lightweight proton exchange membrane fuel cells (PEMFCs) because of its high specific strength and stiffness. However, conventional carbon/epoxy composite bipolar plates are not applicable for high-temperature PEMFCs (HT-PEMFCs) because these systems are operated at higher temperatures than the glass transition temperatures of conventional epoxies. Therefore, in this study, a cyanate ester-modified epoxy is adopted for the development of a carbon composite bipolar plate for HT-PEMFCs. The composite bipolar plate with exposed surface carbon fibers is produced without any surface treatments or coatings to increase the productivity and is integrated with a silicone gasket to reduce the assembly cost. The developed carbon composite bipolar plate exhibits not only superior electrical properties but also high thermo-mechanical properties. In addition, a unit cell test is performed, and the results are compared with those of the conventional graphite bipolar plate.

  13. Anticorrosion properties of tin oxide coatings for carbonaceous bipolar plates of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kinumoto, Taro; Nagano, Keita; Yamamoto, Yuji; Tsumura, Tomoki; Toyoda, Masahiro

    2014-03-01

    An anticorrosive surface treatment of a carbonaceous bipolar plate used in proton exchange membrane fuel cells (PEMFCs) was demonstrated by addition of a tin oxide surface coating by liquid phase deposition (LPD), and its effectiveness toward corrosion prevention was determined. The tin oxide coating was deposited by immersion in tin fluoride and boric acid solutions, without any observable decrease in the bipolar plate electrical conductivity. Anticorrosion properties of a flat carbonaceous bipolar plate were investigated in an aqueous HClO4 electrolyte solution (10 μmol dm-3) at 80 °C. CO2 release due to corrosion was significant for the bare specimen above 1.3 V, whereas no CO2 release was noted for the tin-oxide-coated specimen, even approaching 1.5 V. Moreover, minimal changes in contact angle against a water droplet before and after treatment indicated suppressed corrosion of the surface-coated specimen. Anticorrosion properties were also confirmed for a model bipolar plate having four gas flow channels. The tin oxide layer remained on the channel surfaces (inner walls, corners and intersections) after durability tests. Based on these results, tin-oxide-based surface coatings fabricated by LPD show promise as an anticorrosion technique for carbonaceous bipolar plates for PEMFCs.

  14. Electron beam induced radiation damage in the catalyst layer of a proton exchange membrane fuel cell.

    PubMed

    He, Qianping; Chen, Jihua; Keffer, David J; Joy, David C

    2014-01-01

    Electron microscopy is an essential tool for the evaluation of microstructure and properties of the catalyst layer (CL) of proton exchange membrane fuel cells (PEMFCs). However, electron microscopy has one unavoidable drawback, which is radiation damage. Samples suffer temporary or permanent change of the surface or bulk structure under radiation damage, which can cause ambiguity in the characterization of the sample. To better understand the mechanism of radiation damage of CL samples and to be able to separate the morphological features intrinsic to the material from the consequences of electron radiation damage, a series of experiments based on high-angle annular dark-field-scanning transmission scanning microscope (HAADF-STEM), energy filtering transmission scanning microscope (EFTEM), and electron energy loss spectrum (EELS) are conducted. It is observed that for thin samples (0.3-1 times λ), increasing the incident beam energy can mitigate the radiation damage. Platinum nanoparticles in the CL sample facilitate the radiation damage. The radiation damage of the catalyst sample starts from the interface of Pt/C or defective thin edge and primarily occurs in the form of mass loss accompanied by atomic displacement and edge curl. These results provide important insights on the mechanism of CL radiation damage. Possible strategies of mitigating the radiation damage are provided. © 2013 Wiley Periodicals, Inc.

  15. Protective nitride formation on stainless steel alloys for proton exchange membrane fuel cell bipolar plates

    SciTech Connect

    Yang, Bing; Brady, Michael P; Wang, Heli; Turner, John; More, Karren Leslie; Young, David J; Tortorelli, Peter F; Payzant, E Andrew; Walker, Larry R

    2007-01-01

    Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni-Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr{sub 2}N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective Cr-nitride surface layer was found to be the initial formation of oxide during nitridation, which prevented the internal nitridation typically observed for these alloys, and resulted in external Cr-nitride layer formation. The addition of V to the alloy, which resulted in the initial formation of V{sub 2}O{sub 3}-Cr{sub 2}O{sub 3}, was found to enhance this effect, by making the initially formed oxide more amenable to subsequent nitridation. The Cr-nitride surface layer formed on model V-modified Fe-27Cr alloys exhibited excellent corrosion resistance and low interfacial contact resistance under simulated PEMFC bipolar plate conditions.

  16. Protective nitride formation on stainless steel alloys for proton exchange membrane fuel cell bipolar plates

    SciTech Connect

    Yang, B.; Brady, M. P.; Wang, H.; Turner, J. A.; More, K. L.; Young, D. J.; Tortorelli, P. F.; Payzant, E. A.; Walker, L. R.

    2007-09-07

    Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni–Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr2N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective Cr-nitride surface layer was found to be the initial formation of oxide during nitridation, which prevented the internal nitridation typically observed for these alloys, and resulted in external Cr-nitride layer formation. The addition of V to the alloy, which resulted in the initial formation of V2O3–Cr2O3, was found to enhance this effect, by making the initially formed oxide more amenable to subsequent nitridation. The Cr-nitride surface layer formed on model V-modified Fe–27Cr alloys exhibited excellent corrosion resistance and low interfacial contact resistance under simulated PEMFC bipolar plate conditions.

  17. Erythrocyte-like hollow carbon capsules and their application in proton exchange membrane fuel cells.

    PubMed

    Kim, Jung Ho; Yu, Jong-Sung

    2010-12-14

    Hierarchical nanostructured erythrocyte-like hollow carbon (EHC) with a hollow hemispherical macroporous core of ca. 230 nm in diameter and 30-40 nm thick mesoporous shell was synthesized and explored as a cathode catalyst support in a proton exchange membrane fuel cell (PEMFC). The morphology control of EHC was successfully achieved using solid core/mesoporous shell (SCMS) silica template and different styrene/furfuryl alcohol mixture compositions by a nanocasting method. The EHC-supported Pt (20 wt%) cathodes prepared have demonstrated markedly enhanced catalytic activity towards oxygen reduction reactions (ORRs) and greatly improved PEMFC polarization performance compared to carbon black Vulcan XC-72 (VC)-supported ones, probably due to the superb structural characteristics of the EHC such as uniform size, well-developed porosity, large specific surface area and pore volume. In particular, Pt/EHC cathodes exhibited ca. 30-60% higher ORR activity than a commercial Johnson Matthey Pt catalyst at a low catalyst loading of 0.2 mg Pt cm(-2).

  18. Phase change in the cathode side of a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Khajeh-Hosseini-Dalasm, N.; Fushinobu, Kazuyoshi; Okazaki, Ken

    A three-dimensional steady state two-phase non-isothermal model which highly couples the water and thermal management has been developed to numerically investigate the spatial distribution of the interfacial mass transfer phase-change rate in the cathode side of a proton exchange membrane fuel cell (PEMFC). A non-equilibrium evaporation-condensation phase change rate was incorporated in the model which allowed supersaturation and undersaturation take place. The most significant effects of phase-change rate on liquid saturation and temperature distributions are highlighted. A parametric study was also carried out to investigate the effects of operating conditions; namely as the channel inlet humidity, cell operating temperature, and inlet mass flow rate on the phase-change rate. It was also found that liquid phase assumption for produced water in the cathode catalyst layer (CL) changed the local distribution of phase-change rate. The maximum evaporation rate zone (above the channel near the CL) coincided with the maximum temperature zone and resulted in lowering the liquid saturation level. Furthermore, reduction of the channel inlet humidity and an increase of the operation temperature and inlet mass flow rate increased the evaporation rate and allowed for dehydration process of the gas diffusion layer (GDL) to take place faster.

  19. Current short circuit implementation for performance improvement and lifetime extension of proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Zhan, Yuedong; Guo, Youguang; Zhu, Jianguo; Li, Li

    2014-12-01

    To improve its performance, extend its lifetime, and overcome the problem of the slow dynamic during the start-up and the operation process of a proton exchange membrane fuel cell (PEMFC), this paper presents current short circuit and smart energy management approaches for a main PEMFC with auxiliary PEMFC, battery and supercapacitor as hybrid power source in parallel with an intelligent uninterrupted power supply (UPS) system. The hybrid UPS system consists of two low-cost 63-cell 300 W PEMFC stacks, 3-cell lead-acid battery, and 20-cell series-connected supercapacitors. Based on the designed intelligent hybrid UPS system, experimental tests and theoretical studies are conducted. Firstly, the modeling of PEMFC is obtained and evaluated. Then the performance improvement mechanism of the current short circuit is proposed and analyzed based on the Faradaic process and non-Faradaic process of electrochemical theory. Finally, the performances of the main PEMFC with the auxiliary PEMFC/battery/supercapacitor hybrid power source and intelligent energy management are experimentally measured and analyzed. The proposed current short circuit method can significantly extend the lifetime, improve the performance of PEMFC and decrease the size of the main FC for stationary, backup power sources and vehicular applications.

  20. An extended stochastic reconstruction method for catalyst layers in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kang, Jinfen; Moriyama, Koji; Kim, Seung Hyun

    2016-09-01

    This paper presents an extended, stochastic reconstruction method for catalyst layers (CLs) of Proton Exchange Membrane Fuel Cells (PEMFCs). The focus is placed on the reconstruction of customized, low platinum (Pt) loading CLs where the microstructure of CLs can substantially influence the performance. The sphere-based simulated annealing (SSA) method is extended to generate the CL microstructures with specified and controllable structural properties for agglomerates, ionomer, and Pt catalysts. In the present method, the agglomerate structures are controlled by employing a trial two-point correlation function used in the simulated annealing process. An off-set method is proposed to generate more realistic ionomer structures. The variations of ionomer structures at different humidity conditions are considered to mimic the swelling effects. A method to control Pt loading, distribution, and utilization is presented. The extension of the method to consider heterogeneity in structural properties, which can be found in manufactured CL samples, is presented. Various reconstructed CLs are generated to demonstrate the capability of the proposed method. Proton transport properties of the reconstructed CLs are calculated and validated with experimental data.

  1. Multivariable robust control of a proton exchange membrane fuel cell system

    NASA Astrophysics Data System (ADS)

    Wang, Fu-Cheng; Chen, Hsuan-Tsung; Yang, Yee-Pien; Yen, Jia-Yush

    This paper applies multivariable robust control strategies to a proton exchange membrane fuel cell (PEMFC) system. From the system point of view, a PEMFC can be modeled as a two-input-two-output system, where the inputs are air and hydrogen flow rates and the outputs are cell voltage and current. By fixing the output resistance, we aimed to control the cell voltage output by regulating the air and hydrogen flow rates. Due to the nonlinear characteristics of this system, multivariable robust controllers were designed to provide robust performance and to reduce the hydrogen consumption of this system. The study was carried out in three parts. Firstly, the PEMFC system was modeled as multivariable transfer function matrices using identification techniques, with the un-modeled dynamics treated as system uncertainties and disturbances. Secondly, robust control algorithms were utilized to design multivariable H ∞ controllers to deal with system uncertainty and performance requirements. Finally, the designed robust controllers were implemented to control the air and hydrogen flow rates. From the experimental results, multivariable robust control is shown to provide steady output responses and significantly reduce hydrogen consumption.

  2. Stable support based on highly graphitic carbon xerogel for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Jin, Hong; Zhang, Huamin; Ma, Yuanwei; Xu, Ting; Zhong, Hexiang; Wang, Meiri

    Highly graphitic carbon xerogel (GCX) is prepared by the modified sol-gel polymerization process using cobalt nitrate as the catalyst, followed by high temperature treatment at 1800 °C. The as-prepared GCX is explored as a stable support for Pt in proton exchange membrane fuel cells. The results of N 2 sorption measurement and X-ray diffraction analysis (XRD) reveal that GCX has a better mesoporous structure and a preferably higher degree of graphitization, compared with the commercial XC-72 carbon black. The transmission electron microscopy (TEM) image indicates that Pt nanoparticles are well dispersed on GCX and exhibit relatively narrow size distribution. Accelerated aging test (AAT) based on potential cycling is used to investigate the durability of the as-prepared Pt/GCX in comparison with the commercial Pt/C. Electrochemical analysis demonstrates that the catalyst with GCX as a support exhibits an alleviated degradation rate of electrochemical active surface area (39% for Pt/GCX and 53% for Pt/C). The results of single cell durability tests indicate that the voltage loss of Pt/GCX at 100 mA cm -2 is about 50% lower than that of Pt/C. GCX is expected to be a corrosion resistant electrocatalyst support.

  3. Carbon-supported Pt nanowire as novel cathode catalysts for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Bing; Yan, Zeyu; Higgins, Drew C.; Yang, Daijun; Chen, Zhongwei; Ma, Jianxin

    2014-09-01

    Carbon-supported platinum nanowires (PtNW/C) are successfully synthesized by a simple and inexpensive template-free methodology and demonstrated as novel, suitable cathode electrode materials for proton exchange membrane fuel cell (PEMFC) applications. The synthesis conditions, such as the amount of reducing agent and reaction time, were investigated to investigate the effect on the nanostructures and activities of the PtNW/C catalysts. High-resolution transmission electron microscopy (TEM) results show that the formic acid facilitated reduction is capable of producing uniformly distributed 1-dimensional PtNW with an average cross-sectional diameter of 4.0 ± 0.2 nm and length of 20-40 nm. Investigation of the electrocatalytic activity by half-cell electrochemical testing reveals that PtNW/C catalyst demonstrates significant oxygen reduction reaction (ORR) activity, superior to that of commercially available Pt/C. Using a loading of 0.4 mgPt cm-2 PtNW/C as the cathode catalyst, a maximum power density of 748.8 mW cm-2 in a 50 cm2 single cell of commercial Pt/C. In addition, accelerated degradation testing (ADT) showed that the PtNW/C catalyst exhibits better durability than commercial Pt/C, rendering PtNW/C as a promising replacement to conventional Pt/C as cathode electrocatalysts for PEMFCs applications.

  4. Improvement of proton exchange membrane fuel cell overall efficiency by integrating heat-to-electricity conversion

    NASA Astrophysics Data System (ADS)

    Xie, Chungang; Wang, Shuxin; Zhang, Lianhong; Hu, S. Jack

    Proton exchange membrane fuel cells (PEMFCs) have shown to be well suited for distributed power generation due to their excellent performance. However, a PEMFC produces a considerable amount of heat in the process of electrochemical reaction. It is desirable to use thermal energy for electricity generation in addition to heating applications. Based on the operating characteristics of a PEMFC, an advanced thermal energy conversion system using "ocean thermal energy conversion" (OTEC) technology is applied to exploit the thermal energy of the PEMFC for electricity generation. Through this combination of technology, this unique PEMFC power plant not only achieves the combined heat and power efficiency, but also adequately utilizes heat to generate more valuable electricity. Exergy analysis illustrates the improvement of overall efficiency and energy flow distribution in the power plant. Analytical results show that the overall efficiency of the PEMFC is increased by 0.4-2.3% due to the thermal energy conversion (TEC) system. It is also evident that the PEMFC should operate within the optimal load range by balancing the design parameters of the PEMFC and of the TEC system.

  5. The influence of hydrogen sulfide on proton exchange membrane fuel cell anodes

    NASA Astrophysics Data System (ADS)

    Shi, Weiyu; Yi, Baolian; Hou, Ming; Jing, Fenning; Yu, Hongmei; Ming, Pingwen

    The effect of hydrogen sulfide on proton exchange membrane fuel cell (PEMFC) anodes was studied by cyclic voltammetry (CV), potential steps and electrochemical impedance spectroscopy (EIS). The severity of the effect of H 2S varies depending on the H 2S concentration, current density and the cell temperature. The anode humidification does not impact the poisoning rate much when the anode is exposed to H 2S. The adsorption of H 2S on the anode is dissociative and this dissociation can produce adsorbed sulfur. The dissociation potential of H 2S was studied by potential steps, and the values of the dissociation potential are about 0.4 V at 90 °C, 0.5 V at 60 °C and 0.6 V at 30 °C, respectively. The adsorbed sulfur can be oxidized at a higher potential. During CV scans, two oxidation peaks for the adsorbed sulfur at 1.07 and 1.2 V were observed at 90 °C, however a single oxidation peak could be observed at 1.2 V at 60 °C and at 1.27 V at 30 °C. Application of EIS to a H 2S|H 2 half-cell shows that the charge transfer resistance increases when the anode is exposed to H 2S because of H 2S adsorption.

  6. Method to improve catalyst layer model for modelling proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxian; Gao, Yuan; Ostadi, Hossein; Jiang, Kyle; Chen, Rui

    2015-09-01

    Correctly describing oxygen reduction within the cathode catalyst layer (CL) in modelling proton exchange membrane fuel cell is an important issue remaining unresolved. In this paper we show how to derive an agglomerate model for calculating oxygen reactions by describing dissolved oxygen in the agglomerates using two independent random processes. The first one is the probability that an oxygen molecule, which dissolves in the ionomer film on the agglomerate surface, moves into and then remains in the agglomerates; the second one is the probability of the molecule being consumed in reactions. The first probability depends on CL structure and can be directly calculated; the second one is derived by assuming that the oxygen reduction is first-order kinetic. It is found that the distribution functions of the first process can be fitted to a generalised gamma distribution function, which enables us to derive an analytical agglomerate model. We also expend the model to include oxygen dissolution in the ionomer film, and apply it to simulate cathode electrodes. The results reveal that the resistance to oxygen diffusion in ionomer film and agglomerate in modern CL is minor, and that the main potential loss is due to oxygen dissolution in the ionomer film.

  7. Niobized AISI 304 stainless steel bipolar plate for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Wang, Lixia; Sun, Juncai; Li, Pengbin; Jing, Bo; Li, Song; Wen, Zhongsheng; Ji, Shijun

    2012-06-01

    AISI 304 stainless steel (SS) has been niobized by a plasma surface diffusion alloying method. A 3 μm niobized layer with dominant niobium elements has been formed on the 304 SS surface and the performances of the niobized 304 SS has been examined and evaluated as bipolar plate for proton exchange membrane fuel cell (PEMFC). Results show that the average contact angle with water for the niobized 304 SS is about 90.4°, demonstrating better hydrophobicity as compared with the untreated 304 SS (68.1°). The corrosion resistance of the 304 SS is considerably improved by the niobized layer with the corrosion current densities decreased at 0.2 and 0.4 μA cm-2 in simulated PEMFC anode purged with hydrogen and the cathode purged with air condition (0.05 M H2SO4 + 2 ppm F- solution at 70 °C), respectively. The interfacial contact resistance (ICR) for the as-prepared niobized 304 SS is 10.53 mΩ cm2 at the compaction of 140 N cm-2. Furthermore, after 4 h potentiostatic tests, the niobizied specimens exhibit much lower ICR than that for the untreated ones. Thus, the niobized layer can act as a conductively protective layer of the 304 SS bipolar plate for PEMFC.

  8. Chromium nitride films on stainless steel as bipolar plate for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Wu, Bo; Fu, Yu; Xu, Jun; Lin, Guoqiang; Hou, Ming

    A series of chromium nitride films are prepared on stainless steel substrates by pulsed bias arc ion plating (PBAIP) at different N 2 flow rate as bipolar plates for proton exchange membrane fuel cell (PEMFC). The film chemical composition and phase structure are characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The characterization results indicate that the nitrogen content of deposited films varies from 0.28 to 0.50, and the phase structure changes from mixtures of Cr + Cr 2N, pure Cr 2N through Cr 2N + CrN, to pure CrN. The interfacial contact resistance between samples and carbon paper is measured by Wang's method, and a minimum value of 5.8 mΩ cm 2 is obtained under 1.2 MPa compaction force. The anticorrosion property is examined by potentiodynamic test in the simulated corrosive circumstance of the PEMFC under 25 °C, and the lowest corrosive current density of 5.9 × 10 -7 A cm -2 is obtained at 0.6 V (vs. SCE). Stainless steel substrates coated by the film with lowest contact resistance are chosen as the bipolar plates to assemble cells. An average voltage value of 0.62 V is achieved at 500 mA cm -2, which is close to that of the cell with Ag-plated bipolar plates.

  9. Synthesis and characterization of carbon nanotubes supported platinum nanocatalyst for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lin, J. F.; Kamavaram, V.; Kannan, A. M.

    Multi-walled carbon nanotubes (MWCNTs) were used as catalyst support for depositing platinum nanoparticles by a wet chemistry route. MWCNTs were initially surface modified by citric acid to introduce functional groups which act as anchors for metallic clusters. A two-phase (water-toluene) method was used to transfer PtCl 6 2- from aqueous to organic phase and the subsequent sodium formate solution reduction step yielded Pt nanoparticles on MWCNTs. High-resolution TEM images showed that the platinum particles in the size range of 1-3 nm are homogeneously distributed on the surface of MWCNTs. The Pt/MWCNTs nanocatalyst was evaluated in the proton exchange membrane (PEM) single cell using H 2/O 2 at 80 °C with Nafion-212 electrolyte. The single PEM fuel cell exhibited a peak power density of about 1100 mW cm -2 with a total catalyst loading of 0.6 mg Pt cm -2 (anode: 0.2 mg Pt cm -2 and cathode: 0.4 mg Pt cm -2). The durability of Pt/MWCNTs nanocatalyst was evaluated for 100 h at 80 °C at ambient pressure and the performance (current density at 0.4 V) remained stable throughout. The electrochemically active surface area (64 m 2 g -1) as estimated by cyclic voltammetry (CV) was also similar before and after the durability test.

  10. On active disturbance rejection in temperature regulation of the proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Dazi; Li, Chong; Gao, Zhiqiang; Jin, Qibing

    2015-06-01

    Operating a Proton Exchange Membrane fuel cell (PEMFC) system to maintain the stack temperature stable is one of the key issues in PEMFC's normal electrochemical reaction process. Its temperature characteristic is easily affected by inlet gas humidity, external disturbances, and electrical load changes and so on. Because of the complexity and nonlinearity of the reaction process, it is hard to build a model totally consistent with the real characteristic of the process. If model uncertainty, external disturbances, parameters changes can be regarded as "total disturbance", which is then estimated and compensated, the accurate model is no longer required and the control design can be greatly simplified to meet the practical needs. Based on this idea, an active disturbance rejection control (ADRC) with a switching law is proposed for the problem of precise temperature regulation in PEMFC. Results of the work show that the proposed control system allows the PEMFC to operate successfully at the temperature of 343 K point in the presence of two different disturbances.

  11. Portable proton exchange membrane fuel-cell systems for outdoor applications

    NASA Astrophysics Data System (ADS)

    Oszcipok, M.; Zedda, M.; Hesselmann, J.; Huppmann, M.; Wodrich, M.; Junghardt, M.; Hebling, C.

    A hydrogen fuelled, 30 W proton exchange membrane fuel-cell (PEMFC) system is presented that is able to operate at an ambient temperature between -20 and 40 °C. The system, which comprises the fuel-cell stack, pumps, humidifier, valves and blowers is fully characterized in a climatic chamber under various ambient temperatures. Successful cold start-up and stable operation at -20 °C are reported as well as the system behaviour during long-term at 40 °C. A simple thermal model of the stack is developed and validated, and accounts for heat losses by radiation and convection. Condensation of steam is addressed as well as reaction gas depletion. The stack is regarded as a uniform heat source. The electrochemical reaction is not resolved. General design rules for the cold start-up of a portable fuel-cell stack are deduced by the thermal model and are taken into consideration for the design. The model is used for a comparison between active-assisted cold start-up procedures with a passive cold start-up from temperatures below 0 °C. It is found that a passive cold start-up may not be the most efficient strategy. Additionally, the influence of different stack concepts on the start-up behaviour is analysed by the thermal model. Three power classes of PEMFC stacks are compared: a Ballard Mk902 module for automotive applications with 85 kW, the forerunner stack Ballard Mk5 (5 kW) for medium power applications, and the developed OutdoorFC stack (30 W), for portable applications.

  12. Highly conductive epoxy/graphite polymer composite bipolar plates in proton exchange membrane (PEM) fuel cells

    NASA Astrophysics Data System (ADS)

    Du, Ling

    In this work, highly conductive carbon-filled epoxy composites were developed for manufacturing bipolar plates in proton exchange membrane (PEM) fuel cells. These composites were prepared by solution intercalation mixing, followed by compression molding and curing. The in-plane and through-plane electrical conductivity, thermal and mechanical properties, gas barrier properties, and hygrothermal characteristics were determined as a function of carbon-filler type and content. For this purpose, expanded graphite and carbon black were used as a synergistic combination. Mixtures of aromatic and aliphatic epoxy resin were used as the polymer matrix to capitalize on the ductility of the aliphatic epoxy and chemical stability of the aromatic epoxy. The composites showed high glass transition temperatures (Tg ˜ 180°C), high thermal degradation temperatures (T2˜ 415°C), and in-plane conductivity of 200-500 S/cm with carbon fillers as low as 50 wt%. These composites also showed strong mechanical properties, such as flexural modulus, flexural strength, and impact strength, which either met or exceeded the targets. In addition, these composites showed excellent thermal conductivity greater than 50 W/m/K, small values of linear coefficient of thermal expansion, and dramatically reduced oxygen permeation rate. The values of mechanical and thermal properties and electrical conductivity of the composites did not change upon exposure to boiling water, aqueous sulfuric acid solution and hydrogen peroxide solution, indicating that the composites provided long-term reliability and durability under PEM fuel cell operating conditions. Experimental data show that the composites developed in this study are suitable for application as bipolar plates in PEM fuel cells.

  13. Novel membranes for proton exchange membrane fuel cell operation above 120°C. Final report for period October 1, 1998 to December 31, 1999

    SciTech Connect

    Srinivasan, Supramaniam; Lee, Seung-Jae; Costamagna, Paola; Yang, Christopher; Adjemian, Kevork; Bocarsly, Andrew; Ogden, Joan M.; Benziger, Jay

    2000-05-01

    In this project we investigated the experimental performance of three new classes of membranes, composites of perfluorosulfonic acid polymers with heteropolyacides, hydrated oxides and fast proton conducting glasses, which are promising candidates as electrolytes for proton exchange membrane fuel cells (PEMFCs), capable of operation at temperatures above 120°C. The motivations for PEMFC's operation at this temperature are to: 1) minimize the CO poisoning problem (adsorption of CO onto the platinum catalyst is greatly reduced at these temperatures), 2) find better solutions for the water and thermal management problems in proton exchange membrane fuel cells, 3) find potentially lower cost materials for proton exchange membranes. We prepared and characterized a variety of novel membrane materials. The most promising of these have been evaluated for performance in a single, small area (5cm2) fuel cell run on hydrogen and oxygen. Our results establish the technical feasibility of PEMFC operation above 120°C.

  14. Transport phenomena within the porous cathode for a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Liu, Juanfang; Oshima, Nobuyuki; Kurihara, Eru; Saha, Litan Kumar

    A two-phase, one-dimensional steady model is developed to analyze the coupled phenomena of cathode flooding and mass-transport limiting for the porous cathode electrode of a proton exchange membrane fuel cell. In the model, the catalyst layer is treated not as an interface between the membrane and gas diffusion layer, but as a separate computational domain with finite thickness and pseudo-homogenous structure. Furthermore, the liquid water transport across the porous electrode is driven by the capillary force based on Darcy's law. And the gas transport is driven by the concentration gradient based on Fick's law. Additionally, through Tafel kinetics, the transport processes of gas and liquid water are coupled. From the numerical results, it is found that although the catalyst layer is thin, it is very crucial to better understand and more correctly predict the concurrent phenomena inside the electrode, particularly, the flooding phenomena. More importantly, the saturation jump at the interface of the gas diffusion layer and catalyst layers is captured, when the continuity of the capillary pressure is imposed on the interface. Elsewise, the results show further that the flooding phenomenon in the CL is much more serious than that in the GDL, which has a significant influence on the mass transport of the reactants. Moreover, the saturation level inside the cathode is determined, to a great extent, by the surface overpotential, the absolute permeability of the porous electrode, and the boundary value of saturation at the gas diffusion layer-gas channel interface. In order to prevent effectively flooding, it should remove firstly the liquid water accumulating inside the CL and keep the boundary value of liquid saturation as low as possible.

  15. Chitosan/silica coated carbon nanotubes composite proton exchange membranes for fuel cell applications.

    PubMed

    Liu, Hai; Gong, Chunli; Wang, Jie; Liu, Xiaoyan; Liu, Huanli; Cheng, Fan; Wang, Guangjin; Zheng, Genwen; Qin, Caiqin; Wen, Sheng

    2016-01-20

    Silica-coated carbon nanotubes (SCNTs), which were obtained by a simple sol-gel method, were utilized in preparation of chitosan/SCNTs (CS/SCNTs) composite membranes. The thermal and oxidative stability, morphology, mechanical properties, water uptake and proton conductivity of CS/SCNTs composite membranes were investigated. The insulated and hydrophilic silica layer coated on CNTs eliminates the risk of electronic short-circuiting and enhances the interaction between SCNTs and chitosan to ensure the homogenous dispersion of SCNTs, although the water uptake of CS/SCNTs membranes is reduced owing to the decrease of the effective number of the amino functional groups of chitosan. The CS/SCNTs composite membranes are superior to the pure CS membrane in thermal and oxidative stability, mechanical properties and proton conductivity. The results of this study suggest that CS/SCNTs composite membranes exhibit promising potential for practical application in proton exchange membranes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. State-of-the-art in bipolar of proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Wang, Yun; Wang, Jingjing; Yin, Bi-feng; Xu, Zhen-ying; Ding, Sheng

    2010-10-01

    Proton exchange membrane fuel cell (PEMFC) has been the research focus because of the characteristics of compact structure, low-temperature starting, high specific energy density and power, environmental protection, prolonged service time. The bipolar plate in PEMFC has the function of isolating and uniformly distributing reactants, removing reaction products, collecting and inducing current, providing mechanical support for the cells in the stack collects, etc. The bipolar plate, which influences not only the cell stack performance but also the stack cost, is a vital component of PEMFC that is the choke point of industrialization. Compared with the conventional graphite bipolar plate, the metallic bipolar plate has the advantages of excellent electrical and thermal conductivity, high mechanical strength and power density, no leakage and good workability. Furthermore, the metal plate is especially suitable for production in mass. Therefore, metallic bipolar plate is considered to be a promising alternative for PEMFC bipolar. A review of the research work involves the material selection and processing of bipolar plate, flow-field type and the corresponding design, the forming methods of metallic bipolar plates. The materials of bipolar plate for PEMFC are focused on graphite, metal or alloy, and all kinds of composite materials. The disadvantages and advantages of these materials are compared. The flow channels of bipolar include dot-type, web-type, serpentine-type and the interdigital shape. Among them, serpentine-type flow channel plates are mentioned in detail. In this paper, we introduced the forming methods of metallic bipolar plates such as the electrochemical micro-fabrication, electroforming, thermoforming, micro-stamping and micro-milling. Finally, it points out that the prospective research about the PEMFC is minimization and industrialization.

  17. Non-platinum cathode catalyst layer composition for single Membrane Electrode Assembly Proton Exchange Membrane Fuel Cell

    NASA Astrophysics Data System (ADS)

    Olson, Tim S.; Chapman, Kate; Atanassov, Plamen

    The performance of nano-structured templated non-platinum-based cathode electrocatalysts for proton exchange membrane fuel cells (PEMFC) was evaluated for different catalyst layer compositions. The effect of non-platinum catalyst, Nafion, and 35 wt% Teflon modified Vulcan XC-72 Carbon Blacks (XC-35) loadings were measured under H 2/air and H 2/O 2 conditions. Transport hindrances that occur in the catalyst layers are evaluated with Δ E vs. i analysis. It is shown that transport limitations in the cathode catalyst layer can limit the performance of the cell at relatively low current densities if the catalyst layer composition is not optimized. Further, a procedure is outlined here to aid in the implementation of non-traditional catalyst materials into fuel cell systems (i.e. templated electrocatalyst as compared to the standard supported material).

  18. Non-precious metal catalysis for proton-exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Leonard, Nathaniel Dean

    Non-precious metal catalysts (NPMC) for proton exchange membrane fuel cells (PEMFC) are explored. Research into NPMCs is motivated by the growing need for cleaner, more efficient energy options. NPMCs are one option to make fuel cells more commercially viable. To this end, the present work studies and simulates the morphology and function of metal-nitrogen-carbon (MNC) oxygen reduction catalysts. A porosity study finds that mesoporosity is critical to high performance of autogenic pressure metal-nitrogen-carbon (APMNC) oxygen reduction catalysts. Various carbon materials are used as precursors to synthesis APMNC catalysts. The catalysts and the associated porous carbon materials are characterized morphologically, chemically, and electrochemically. The results indicated that substrates adsorbing the most nitrogen and iron show the highest activity. Furthermore, a relationship is found between mesoporosity and nitrogen content indicating the importance of transport to active site creation. A correlation is found between surface alkalinity and catalytic activity for APMNC catalysts. The basic site strength and quantity were calculated by two different methods, and it was shown that increased Bronsted- Lowry basicity correlates to more active catalysts. The relationship between alkalinity and catalytic activity could be the result of the impact of alkalinity on the electron density of the metal centers or basic sites could encourage active site formation. It is found that the oxygen reduction reaction (ORR) proceeds both via a direct four-electron pathway to water at high potentials and an indirect peroxide pathway at low potentials on an APMNC catalyst. At higher potential, site availability inhibits peroxide generation causing the direct four-electron reduction pathway to dominate. Oxygen reduction begins to shift to the indirect peroxide pathway due to fast kinetics and higher site availability around 0.6 V vs RHE. The net peroxide generation remains relatively low

  19. In-situ membrane hydration measurement of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lai, Yeh-Hung; Fly, Gerald W.; Clapham, Shawn

    2015-01-01

    Achieving proper membrane hydration control is one of the most critical aspects of PEM fuel cell development. This article describes the development and application of a novel 50 cm2 fuel cell device to study the in-situ membrane hydration by measuring the through-thickness membrane swelling via an array of linear variable differential transducers. Using this setup either as an air/air (dummy) cell or as a hydrogen/air (operating) cell, we performed a series of hydration and dehydration experiments by cycling the RH of the inlet gas streams at 80 °C. From the linear relationship between the under-the-land swelling and the over-the-channel water content, the mechanical constraint within the fuel cell assembly can suppress the membrane water uptake by 11%-18%. The results from the air/air humidity cycling test show that the membrane can equilibrate within 120 s for all RH conditions and that membrane can reach full hydration at a RH higher than 140% in spite of the use of a liquid water impermeable Carbel MP30Z microporous layer. This result confirms that the U.S. DOE's humidity cycling mechanical durability protocol induces sufficient humidity swings to maximize hygrothermal mechanical stresses. This study shows that the novel experimental technique can provide a robust and accurate means to study the in-situ hydration of thin membranes subject to a wide range of fuel cell conditions.

  20. Study of the cell reversal process of large area proton exchange membrane fuel cells under fuel starvation

    NASA Astrophysics Data System (ADS)

    Liang, Dong; Shen, Qiang; Hou, Ming; Shao, Zhigang; Yi, Baolian

    In this research, the fuel starvation phenomena in a single proton exchange membrane fuel cell (PEMFC) are investigated experimentally. The response characteristics of a single cell under the different degrees of fuel starvation are explored. The key parameters (cell voltage, current distribution, cathode and anode potentials, and local interfacial potentials between anode and membrane, etc.) are measured in situ with a specially constructed segmented fuel cell. Experimental results show that during the cell reversal process due to the fuel starvation, the current distribution is extremely uneven, the local high interfacial potential is suffered near the anode outlet, hydrogen and water are oxidized simultaneously in the different regions at the anode, and the carbon corrosion is proved to occur at the anode by analyzing the anode exhaust gas. When the fuel starvation becomes severer, the water electrolysis current gets larger, the local interfacial potential turns higher, and the carbon corrosion near the anode outlet gets more significant. The local interfacial potential near the anode outlet increases from ca. 1.8 to 2.6 V when the hydrogen stoichiometry decreases from 0.91 to 0.55. The producing rate of the carbon dioxide also increases from 18 to 20 ml min -1.

  1. Proton-Exchange-Membrane Fuel Cell Powerplants Developed and Tested for Exploration Missions

    NASA Technical Reports Server (NTRS)

    Hoberecht, Mark A.; Pham, Nang T.

    2005-01-01

    Proton-exchange-membrane fuel cell (PEMFC) technology has received major attention for terrestrial applications, such as the automotive and residential markets, for the past 20 years. This attention has significantly advanced the maturity of the technology, resulting in ever more compact, efficient, reliable, and inexpensive PEMFC designs. In comparison to the terrestrial operating environment, the space operating environment is much more demanding. Microgravity to high-gravity loads and the need to use pure oxygen (rather than air) as the fuel cell oxidizer place more stringent demands on PEMFC technology. NASA and its partners from industry are leveraging terrestrial PEMFC advancements by conducting parallel space technology development for future exploration missions. A team from the NASA Glenn Research Center, NASA Johnson Space Center, and NASA Kennedy Space Center recently completed the first phase of a PEMFC powerplant development effort for exploration missions. The industry partners for this phase of the development effort were ElectroChem, Inc., and Teledyne Energy Systems, Inc. Under contract to Glenn, both of these industry partners successfully designed, fabricated, and tested a breadboard PEMFC powerplant in the 1- to 5-kW power range. These powerplants were based on existing company-proprietary fuel cell stack designs, combined with off-the-shelf components, which formed the balance of the powerplant design. Subsequent to the contractor development efforts, both powerplants were independently tested at Johnson to verify operational and performance characteristics, and to determine suitability for further technology development in the second phase of the NASA-led effort. Following the independent NASA testing, Teledyne Energy Systems, Inc., was selected to develop an engineering model PEMFC powerplant. This effort was initiated by the 2nd Generation Reusable Launch Vehicle (RLV) Program Office in 2001; it transitioned to the Next Generation Launch

  2. Self-humidified proton exchange membrane fuel cells: Operation of larger cells and fuel cell stacks

    SciTech Connect

    Dhar, H.P.; Lee, J.H.; Lewinski, K.A.

    1996-12-31

    The PEM fuel cell is promising as the power source for use in mobile and stationary applications primarily because of its high power density, all solid components, and simplicity of operation. For wide acceptability of this power source, its cost has to be competitive with the presently available energy sources. The fuel cell requires continuous humidification during operation as a power source. The humidification unit however, increases fuel cell volume, weight, and therefore decreases its overall power density. Great advantages in terms of further fuel cell simplification can be achieved if the humidification process can be eliminated or minimized. In addition, cost reductions are associated with the case of manufacturing and operation. At BCS Technology we have developed a technology of self-humidified operation of PEM fuel cells based on the mass balance of the reactants and products and the ability of membrane electrode assembly (MEA) to retain water necessary for humidification under the cell operating conditions. The reactants enter the fuel cell chambers without carrying any form of water, whether in liquid or vapor form. Basic principles of self-humidified operation of fuel cells as practiced by BCS Technology, Inc. have been presented previously in literature. Here, we report the operation of larger self-humidified single cells and fuel cell stacks. Fuel cells of areas Up to 100 cm{sup 2} have been operated. We also show the self-humidified operation of fuel cell stacks of 50 and 100 cm{sup 2} electrode areas.

  3. High-temperature proton-exchange-membrane fuel cells using an ether-containing polybenzimidazole membrane as electrolyte.

    PubMed

    Li, Jin; Li, Xiaojin; Zhao, Yun; Lu, Wangting; Shao, Zhigang; Yi, Baolian

    2012-05-01

    Herein, poly[2,2'-(p-oxydiphenylene)-5,5'-benzimidazole] (PBI) is synthesized from 3,3'-diaminobenzidine and 4,4'-oxybisbenzoic acid, and the membrane is prepared by solvent casting. The main characteristics of PBI are studied. In the preparation of the PBI/H(3) PO(4) composite membrane, the absorbing temperature of H(3) PO(4) is 120 °C, which leads to a membrane with a high content of H(3) PO(4) . Membrane electrode assemblies (MEAs) are fabricated from PBI/H(3) PO(4) membranes with the catalyst layer made of Pt/C, PBI, and polyvinylidene fluoride (230:12:7 w/w). The fabricated MEA is tested at 150 °C with dry hydrogen and oxygen gas at 0.2 MPa for both anode and cathode feeds. No degradation of voltage is seen during stability testing of the PBI/H(3) PO(4) membrane at a constant current for 100 h. The maximum power density is 1.17 W cm(-2) , and the maximum current density is 6.0 A cm(-2) with a Pt loading of 0.5 mg cm(-2) . The high performance of these membrane materials demonstrates that PBI can be regarded as an alternative membrane material for high-temperature proton-exchange-membrane fuel cells.

  4. Nondestructive evaluation of acoustic properties of fuel cell proton-exchange membranes by vector contrast acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Kamanyi, Albert E.; Grill, Wolfgang

    2012-04-01

    In recent years, the interest in the research and development of "green energy" has increased dramatically, with numerous research grants and investment in the areas of wind power, solar power and fuel cell technology. We present results obtained from the evaluation of the acoustic properties of proton-exchange membranes used in hydrogen fuel cells, which relate directly to the microelastic properties of such membranes. These properties play an important role in the durability and applicability as well as the efficiency of such membranes. DuPont Nafion membranes are the most commonly used polymeric membranes in hydrogen/oxygen fuel cells and are therefore used as examples in this study. The microscope used in this non-destructive characterization study is a vector-contrast version of the scanning acoustic microscope which yields images in magnitude- and phase contrast.

  5. Nafion®/ODF-silica composite membranes for medium temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Treekamol, Yaowapa; Schieda, Mauricio; Robitaille, Lucie; MacKinnon, Sean M.; Mokrini, Asmae; Shi, Zhiqing; Holdcroft, Steven; Schulte, Karl; Nunes, Suzana P.

    2014-01-01

    A series of composite membranes were prepared by dispersing fluorinated polyoxadiazole oligomer (ODF)-functionalized silica nanoparticles in a Nafion® matrix. Both melt-extrusion and solvent casting processes were explored. Ion exchange capacity, conductivity, water uptake and dimensional stability, thermal stability and morphology were characterized. The inclusion of functionalized nanoparticles proved advantageous, mainly due to a physical crosslinking effect and better water retention, with functionalized nanoparticles performing better than the pristine silica particles. For the same filler loading, better nanoparticle dispersion was achieved for solvent-cast membranes, resulting in higher proton conductivity. Filler agglomeration, however, was more severe for solvent-cast membranes at loadings beyond 5 wt.%. The composite membranes showed excellent thermal stability, allowing for operation in medium temperature PEM fuel cells. Fuel cell performance of the composite membranes decreases with decreasing relative humidity, but good performance values are still obtained at 34% RH and 90 °C, with the best results obtained for solvent cast membranes loaded with 10 wt.% ODF-functionalized silica. Hydrogen crossover of the composite membranes is higher than that for pure Nafion® membranes, possibly due to porosity resulting from suboptimal particle-matrix compatibility.

  6. The Investigation and Development of Low Cost Hardware Components for Proton-Exchange Membrane Fuel Cells - Final Report

    SciTech Connect

    George A. Marchetti

    1999-12-15

    Proton exchange membrane (PEM) fuel cell components, which would have a low-cost structure in mass production, were fabricated and tested. A fuel cell electrode structure, comprising a thin layer of graphite (50 microns) and a front-loaded platinum catalyst layer (600 angstroms), was shown to produce significant power densities. In addition, a PEM bipolar plate, comprising flexible graphite, carbon cloth flow-fields and an integrated polymer gasket, was fabricated. Power densities of a two-cell unit using this inexpensive bipolar plate architecture were shown to be comparable to state-of-the-art bipolar plates.

  7. Photoregenerative I−/I3− couple as a liquid cathode for proton exchange membrane fuel cell

    PubMed Central

    Liu, Zhen; Wang, Yadong; Ai, Xinping; Tu, Wenmao; Pan, Mu

    2014-01-01

    A photoassisted oxygen reduction reaction (ORR) through I−/I3− redox couple was investigated for proton exchange membrane (PEM) fuel cell cathode reaction. The I−/I3−-based liquid cathode was used to replace conventional oxygen cathode, and its discharge product I− was regenerated to I3− by photocatalytic oxidation with the participation of oxygen. This new and innovative approach may provide a strategy to eliminate the usage of challenging ORR electrocatalysts, resulting in an avenue for developing low-cost and high-efficiency PEM fuel cells. PMID:25348812

  8. Oxidation-resistant catalyst supports for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Chhina, Harmeet

    In automotive applications, when proton exchange membrane fuel cells (PEMFCs) are subjected to frequent startup-shutdown cycles, a significant drop in performance is observed. One reason for this drop in performance is oxidation of the carbon in the catalyst layer when cathode potential excursions as high as 1.5V are observed. In this work, non-carbon based catalyst support materials were studied. The materials investigated include: tungsten carbide (WC), tungsten oxide (WOx), and niobium (Nb) or tungsten (W) doped titania. Platinum was dispersed on commercial samples of WC and WO x. Stability tests were performed by stepping the materials between 0.6 to 1.8V. Higher stability of both WC and WOx was observed compared to carbon based commercial catalyst (HiSpec 4000). The performance of Pt supported on WC or WOx was found to be lower than that of Pt/C due to poor dispersion of Pt on these low surface area commercial powders. High surface area Nb and W doped titania materials synthesized using sol-gel techniques were subjected to several heat treatments and atmospheres, and their resulting physical properties characterized. The materials' phase changes and their impact on electrical conductivity were evaluated. W doped titania was found to be resistive, and for Nb doped titania, the rutile phase was found to be more conductive than the anatase phase. Conventionally, 10-50 wt% Pt is supported on carbon, but as the non-carbon catalyst support materials have different densities, similar mass ratios of catalyst to support will not result in directly comparable performances. It is recommended that the ratio of Pt surface area to the support surface area should be similar when comparing Pt supported on carbon to Pt supported on a non-carbon support. A normalization approach was investigated in this work, and the ORR performance of 40wt.%Pt/C was found to be similar to that of 10wt.%Pt/Nb-TiO2. Fuel cell performance tests showed significantly higher stability of Pt on Nb

  9. Study of coupled heat and water transfer in proton exchange membrane fuel cells by the way of internal measurements

    NASA Astrophysics Data System (ADS)

    Thomas, A.; Maranzana, G.; Didierjean, S.; Dillet, J.; Lottin, O.

    2012-11-01

    Measurements of electrode temperatures within a proton exchange membrane fuel cell were performed using platinum wires. A temperature difference of 7°C between the electrodes and the bipolar plates was observed for a cell operating at a current density of 1.5 A.cm-2. These measurements show a strong non-uniformity of the temperature profile through membrane electrode assembly (MEA) that future phenomenological models must take into account. In addition, the simultaneous measurements of heat and water flux through the MEA leads to the conclusion that produced water crosses the diffusion layer in vapor phase. A very simple heat transfer model is proposed.

  10. UV-visible spectroscopy method for screening the chemical stability of potential antioxidants for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Banham, Dustin; Ye, Siyu; Knights, Shanna; Stewart, S. Michael; Wilson, Mahlon; Garzon, Fernando

    2015-05-01

    A novel method based on UV-visible spectroscopy is reported for screening the chemical stability of potential antioxidant additives for proton exchange membrane fuel cells, and the chemical stabilities of three CeOx samples of varying crystallite sizes (6, 13, or 25 nm) are examined. The chemical stabilities predicted by this new screening method are compared to in-situ membrane electrode assembly (MEA) accelerated stress testing, with the results confirming that this rapid and inexpensive method can be used to accurately predict performance impacts of antioxidants.

  11. A boron phosphate-phosphoric acid composite membrane for medium temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Mamlouk, M.; Scott, K.

    2015-07-01

    A composite membrane based on a non-stoichiometric composition of BPO4 with excess of PO4 (BPOx) was synthesised and characterised for medium temperature fuel cell use (120-180 °C). The electrolyte was characterised by FTIR, SS-NMR, TGA and XRD and showed that the B-O is tetrahedral, in agreement with reports in the literature that boron phosphorus oxide compounds at B:P < 1 are exclusively built of borate and phosphate tetrahedra. Platinum micro electrodes were used to study the electrolyte compatibility and stability towards oxygen reduction at 150 °C and to obtain kinetic and mass transport parameters. The conductivities of the pure BPOx membrane electrolyte and a Polybenzimidazole (PBI)-4BPOx composite membrane were 7.9 × 10-2 S cm-1 and 4.5 × 10-2 S cm-1 respectively at 150 °C, 5%RH. Fuel cell tests showed a significant enhancement in performance of BPOx over that of typical 5.6H3PO4-PBI membrane electrolyte. The enhancement is due to the improved ionic conductivity (3×), a higher exchange current density of the oxygen reduction (30×) and a lower membrane gas permeability (10×). Fuel cell current densities at 0.6 V were 706 and 425 mA cm-2 for BPOx and 5.6H3PO4-PBI, respectively, at 150 °C with O2 (atm).

  12. Sulfated Titania-Silica Reinforced Nafion Nanocomposite Membranes for Proton Exchange Membrane Fuel Cells.

    PubMed

    Abu Sayeed, M D; Kim, Hee Jin; Gopalan, A I; Kim, Young Ho; Lee, Kwang-Pill; Choi, Sang-June

    2015-09-01

    Sulfated titania-silica (SO4(2-)-/TiO2-SiO2) composites were prepared by a sol-gel method with sulfate reaction and characterized by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The nanometric diameter and geometry of the sulfated titania-silica (STS) was investigated by transmission electron microscopy (TEM). A small amount of the STS composite in the range of 0.5-3 wt% was then added as reinforcing into the Nafion membrane by water-assisted solution casting method to prepare STS reinforced Nafion nanocomposite membranes (STS-Nafion nanocomposite membranes). The additional functional groups, sulfate groups, of the nanocomposite membrane having more surface oxygenated groups enhanced the fuel cell membrane properties. The STS-Nafion nanocomposite membranes exhibited improved water uptake compared to that of neat Nafion membranes, whereas methanol uptake values were decreased dramatically improved thermal property of the prepared nanocomposite membranes were measured by thermogravimetric analysis (TGA). Furthermore, increased ion exchange capacity values were obtained by thermoacidic pretreatment of the nanocomposite membranes.

  13. Cross-linked high conductive membranes based on water soluble ionomer for high performance proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Guo, Xin; Zhang, Gang; Ni, Jing; Zhao, Chengji; Liu, Zhongguo; Zhang, Liyuan; Li, Mingyu; Xu, Shuai; Na, Hui

    2013-11-01

    In this paper, a series of proton exchange membranes prepared by “Click Reaction” are reported. The cross-linked membranes are based on water soluble sulfonated poly (ether ether ketone) containing dipropenyl groups (SDPEEK-nE/nH). Compared with self-crosslinked membranes (SDPEEK-nS), this “Click” cross-linked membranes using 1,2-Ethanedithiol and 1,6-Hexanedithiol as the cross-linker exhibit extremely reduced water uptake and swelling ratio. The lowest proton conductivity at 80 °C of the “Click” cross-linked membranes reaches to 0.168 S cm-1, and the highest methanol permeability of the “Click” cross-linked SDPEEK-8E is only 4.13 × 10-7 cm2 s-1, which is 5 times lower than that of Nafion 117 membrane. All the results imply that the cross-linked membranes with novel thiol cross-linker are promising alternative material for fuel cell application.

  14. Study of catalysts with high stability for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Yang, Fan

    The innovation and investigation of catalysts in proton exchange membrane fuel cells are included in this thesis. In the first part of this work, stability of the catalyst support of PEMFC catalyst is investigated. Nanoscale platinum particles were loaded on two different kinds of carbon supports, nano graphene sheets and functionalized carbon black/graphene hybrid were developed by the liquid phase reaction. The crystal structure of two kinds of catalysts was characterized by X-ray diffractometer (XRD). The morphology and particle size were characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). Pt loading was measured by thermal gravimetric analysis (TGA). The Brunauer, Emmett and Teller (BET) method was applied to test the surface area of the catalysts. The electrochemical surface area (ECSA) and mass activity during oxygen reduction reaction (ORR) process for two kinds of catalyst were tested by cyclic voltammetry method under different conditions. The stability of the catalysts were tested by accelerated durability test (ADT). The results show that although the mass activity of Pt/graphene is much lower, the stability of it is much better than that of the commercial catalyst. After adding functionalized carbon black (FCB) as spacer, the stability of the catalyst is preserved and at the meantime, the mass activity becomes higher than 20% Pt/XC72 catalyst. The lower mass activity of both catalysts are due to the limitation of the electrolyte diffusion into the carbon support because of the aggregation nature of graphene nano-sheets. After introducing functional carbon black as spacer, the mass activity and ECSA increased dramatically which proved that FCB can be applied to prevent the restacking of graphene and hence solved the diffusion problem. In the meantime, the durability was still keeping the same as Pt/graphene catalyst. In the second part of the work, the restacking problem was solved by introducing FCB as spacers

  15. Properties and degradation of the gasket component of a proton exchange membrane fuel cell--a review.

    PubMed

    Basuli, Utpal; Jose, Jobin; Lee, Ran Hee; Yoo, Yong Hwan; Jeong, Kwang-Un; Ahn, Jou-Hyeon; Nah, Changwoon

    2012-10-01

    Proton exchange membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the reactant gases within their respective regions. Gasket performance is integral to the successful long-term operation of a fuel cell stack. This review focuses on properties, performance and degradation mechanisms of the different polymer gasket materials used in PEM fuel cell under normal operating conditions. The different degradation mechanisms and their corresponding representative mitigation strategies are also presented here. Summary of various properties of elastomers and their advantages and disadvantages in fuel cell'environment are presented. By considering the level of chemical degradation, mechanical properties and cost effectiveness, it can be proposed that EPDM is one of the best choices for gasket material in PEM fuel cell. Finally, the challenges that remain in using rubber component as in PEM fuel cell, as well as the prospects for exploiting them in the future are discussed.

  16. Pressure pyrolysed non-precious oxygen reduction catalysts for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Nallathambi, Vijayadurga

    2011-12-01

    and increased the porosity, particularly micro and mesopores of the catalysts that led to increased active site density and reduced oxygen transport hindrances respectively. Collaborative efforts with the University of New Mexico facilitated XPS characterization of MNC catalysts. XPS analyses indicated that pyridinic nitrogen sites, present in the edge plane of the catalysts and pyridinic nitrogen coordinated to transition metals correlated to oxygen reduction activity. Further insight into the role of transition metal and the structure of active site was gained through EXAFS measurements, carried out in collaboration with Northeastern University. Electrochemical studies performed in the presence of poisoning anions such as cyanide in alkaline environment indicated a 25% decrease in oxygen reduction activity, suggesting that the metal is part of the active sites and participates in oxygen reduction. In-situ EXAFS analysis of the catalysts indicated the active reaction site for oxygen reduction to be Fe metal coordinated to 4 nitrogen atoms. These low cost MNC catalysts find direct application in Proton Exchange Membrane Fuel cells for transportation applications, where there is a huge drive to improve the economy of the fuel cell by reducing the costs associated with state-of the art platinum-based catalysts.

  17. Mass transport studies in conventional and microfabricated free convection proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Modroukas, Dean

    This thesis presents the design, modeling and testing of both conventional and non-conventional free convection proton exchange membrane fuel cells (PEMFC) which are particularly attractive for low power (<100W), man portable applications. As part of this investigation, experimental data coupled with computational simulations has provided a deeper understanding into the mechanisms that limit operability. In particular, the low temperatures of operation (<50°C) and lack of forced air convection generate high levels of saturation within the cell thereby reducing the available catalytic sites. A 2-D, single- and two-phase computational model for an open-cathode, free convection PEMFC was developed. The two-phase modeling has provided significant insight into the mass transport limitations caused primarily by liquid water flooding while the single phase simulations present an upper limit in performance assuming product water exists only in vapor form. A set of parametric experiments were performed using conventional gas diffusion media (GDM) along with numerous 1cm2 stainless steel grid-based current collectors having open area ratios of 10%, 25% and 50%. These experiments provided a data set that was used to "tune" and validate the model. Single cell polarization data experienced limiting currents ranging from 190mA/cm2 to 600mA/cm 2 at operating cell temperatures of 38°C-45°C, depending on the open area ratio. The two-phase model captured the effect of current collector porosity as well as the increase in limiting current associated with rising cell temperature. Once validated, the model was used with confidence as a design tool for MEMS-based tailored mass transfer media (TMTM) that provide more advanced functionality than customary GDM. They were based on a microfabricated hydrophobic silicon mesh comprised of square pores with discrete zones made to be hydrophilic using a carbon-polyethylene oxide treatment. The TMTM were engineered to localize the removal of

  18. Performance evaluation and characterization of metallic bipolar plates in a proton exchange membrane (PEM) fuel cell

    NASA Astrophysics Data System (ADS)

    Hung, Yue

    Bipolar plate and membrane electrode assembly (MEA) are the two most repeated components of a proton exchange membrane (PEM) fuel cell stack. Bipolar plates comprise more than 60% of the weight and account for 30% of the total cost of a fuel cell stack. The bipolar plates perform as current conductors between cells, provide conduits for reactant gases, facilitate water and thermal management through the cell, and constitute the backbone of a power stack. In addition, bipolar plates must have excellent corrosion resistance to withstand the highly corrosive environment inside the fuel cell, and they must maintain low interfacial contact resistance throughout the operation to achieve optimum power density output. Currently, commercial bipolar plates are made of graphite composites because of their relatively low interfacial contact resistance (ICR) and high corrosion resistance. However, graphite composite's manufacturability, permeability, and durability for shock and vibration are unfavorable in comparison to metals. Therefore, metals have been considered as a replacement material for graphite composite bipolar plates. Since bipolar plates must possess the combined advantages of both metals and graphite composites in the fuel cell technology, various methods and techniques are being developed to combat metallic corrosion and eliminate the passive layer formed on the metal surface that causes unacceptable power reduction and possible fouling of the catalyst and the electrolyte. The main objective of this study was to explore the possibility of producing efficient, cost-effective and durable metallic bipolar plates that were capable of functioning in the highly corrosive fuel cell environment. Bulk materials such as Poco graphite, graphite composite, SS310, SS316, incoloy 800, titanium carbide and zirconium carbide were investigated as potential bipolar plate materials. In this work, different alloys and compositions of chromium carbide coatings on aluminum and SS316

  19. Catalytic hydrogen/oxygen reaction assisted the proton exchange membrane fuel cell (PEMFC) startup at subzero temperature

    NASA Astrophysics Data System (ADS)

    Sun, Shucheng; Yu, Hongmei; Hou, Junbo; Shao, Zhigang; Yi, Baolian; Ming, Pingwen; Hou, Zhongjun

    Fuel cells for automobile application need to operate in a wide temperature range including freezing temperature. However, the rapid startup of a proton exchange membrane fuel cell (PEMFC) at subfreezing temperature, e.g., -20 °C, is very difficult. A cold-start procedure was developed, which made hydrogen and oxygen react to heat the fuel cell considering that the FC flow channel was the characteristic of microchannel reactor. The effect of hydrogen and oxygen reaction on fuel cell performance at ambient temperature was also investigated. The electrochemical characterizations such as I- V plot and cyclic voltammetry (CV) were performed. The heat generated rate for either the single cell or the stack was calculated. The results showed that the heat generated rate was proportional to the gas flow rate when H 2 concentration and the active area were constant. The fuel cell temperature rose rapidly and steadily by controlling gas flow rate.

  20. Studies of transient behavior of proton exchange membrane fuel cells (PEMFC)

    NASA Astrophysics Data System (ADS)

    Kim, Sunhoe

    The Proton Exchange Membrane Fuel Cell (PEMFC) is a technology with growing interest. The PEMFC is the most fascinating among other kinds of fuel cells for its high power density and zero emission pure water products. The use of PEMFCs will expose it to transient conditions. For instance, acceleration or deceleration in vehicle applications and turning on or off dishwashers in stationary applications may cause transient conditions of operation of PEMFCs. This dissertation presents experimental data that may be used to understand PEMFC behavior during these transients and these data may be used to verify the numerical simulations and models of PEMFC designs. The electrical load was changed with fixed inlet flowrates for the anode and cathode, and this caused hydrogen and air, stoichiometries to change. The transient experiments showed conditions and stoichiometric changes that gave the overshoot and undershoot behaviors. Data are presented to show the effects of voltage changes on the current response with four different cases of stoichiometry changes: from excess to normal, from normal to excess, from normal to starved, and from starved to normal. An overshoot behavior was observed when the cell stoichiometry changed from normal to starved condition. With a triple path flow field this overshoot was followed by an undershoot and this second order behavior is a result of, in this case, the air flowing back into the cell at the end of anode side to balance pressure. We named these phenomena as "vacuum effects" when the current density shows "undershoot" after "overshoot" behavior. For other conditions an undershoot behavior was observed when the voltage changed to cause a change from starved to normal conditions. In contrast, only exponential first order behavior was observed for voltage changes between excess and normal conditions. Various cell voltage ranges and change rates are presented to compare the overshoot and undershoot behaviors. Experiments were performed

  1. The effects of excess phosphoric acid in a Polybenzimidazole-based high temperature proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Matar, Saif; Higier, Andrew; Liu, Hongtan

    A series of experiments are conducted in order to investigate the performance of a proton exchange membrane (PEM) fuel cell using a commercially available polybenzimidazole (PBI)-based high temperature membrane. During the study a drastic degradation in performance is observed over time and a significant amount of solid material built-up is found in the flow field plate and the membrane-electrode assembly (MEA). The built-up material is examined by the use of a Scanning Electron Microscope (SEM). Further elemental analysis using Energy Dispersive X-ray Spectroscopy (EDS) finds that the built-up material contains large amount of phosphorus, thus relating it with the excess phosphoric acid found in the MEA. Additional experimental studies show that the built-up material is caused by the excess acid solution in the MEA, and when the excess phosphoric acid is removed from the MEA the fuel cell performance improves significantly and becomes very stable.

  2. Physico-chemical study of the degradation of membrane-electrode assemblies in a proton exchange membrane fuel cell stack

    NASA Astrophysics Data System (ADS)

    Ferreira-Aparicio, P.; Gallardo-López, B.; Chaparro, A. M.; Daza, L.

    A proton exchange membrane fuel cell stack integrated by 8-elements has been evaluated in an accelerated stress test. The application of techniques such as TEM analyses of ultramicrotome-sliced sections of some samples and XRD, XPS and TGA of spent electrodes reveal the effects of several degradation processes contributing to reduce the cells performance. The reduction of the Pt surface area at the cathode is favored by the oxidation of carbon black agglomerates in the catalytic layer, the agglomeration of Pt particles and by the partial dissolution of Pt, which migrates towards the anode and precipitates within the membrane. In the light of the TEM, EDAX and XPS results, two combined effects are probably responsible of the increase of the internal resistance of the stack cells: (i) a lower proton conductivity of the membranes due to the high affinity of the sulfonic acid groups for ions originated from Pt crystallites and other peripherical elements such as the silicone elastomeric gaskets and (ii) the increment of electrically isolated islands in the cathode gas diffusion electrodes resulting from carbon corrosion and the degradation of the perfluorinated polymers. Water accumulation and inhomogeneous gas distribution throughout the stack cells originate different degradation rates in them.

  3. Nanostructured TiOx as a catalyst support material for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Phillips, Richard S.

    Recent interest in the development of new catalyst support materials for proton exchange membrane fuel cells (PEMFCs) has stimulated research into the viability of TiO2-based support structures. Specifically, substoichiometric TiO2 (TiOx) has been reported to exhibit a combination of high conductivity, stability, and corrosion resistance. These properties make TiOx-based support materials a promising prospect when considering the inferior corrosion resistance of traditional carbon-based supports. This document presents an investigation into the formation of conductive and stable TiOx thin films employing atomic layer deposition (ALD) and a post deposition oxygen reducing anneal (PDORA). Techniques for manufacturing TiOx-based catalyst support nanostructures by means of ALD in conjunction with carbon black (CB), anodic aluminum oxide (AAO) and silicon nanowires (SiNWs) will also be presented. The composition and thickness of resulting TiOx thin films was determined with the aid of Auger electron spectroscopy (AES), Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). Film crystal structure was determined with X-ray diffraction (XRD) analysis. Film conductivity was calculated using four-point probe (4-PP) and film thickness measurement data. Resulting thin films show a significant decrease of oxygen in ALD TiOx films corresponding with a great increase in conductivity following the PDORA. The effectiveness of the PDORA was also found to be highly dependent on ALD process parameters. TiOx-based nanostructures were coated with platinum using one of three Pt deposition techniques. First, liquid phase deposition (LPD), which was performed at room temperature, provided equal access to catalyst support material surfaces which were suspended in solution. Second, plasma enhanced atomic layer deposition (PEALD), which was performed at 450°C, provided good Pt

  4. Enhancement of water retention in UV-exposed fuel-cell proton exchange membranes studied using terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Ray, Shaumik; Devi, Nirmala; Dash, Jyotirmayee; Rambabu, Gutru; Bhat, Santoshkumar D.; Pesala, Bala

    2016-02-01

    Proton Exchange Membrane (PEM) fuel cells are increasingly gaining importance as a clean energy source. PEMs need to possess high proton conductivity and should be chemically and mechanically stable in the fuel cell environment. Proton conductivity of PEM in fuel cells is directly proportional to water content in the membrane. Among the various PEMs available, Nafion has high proton conductivity even with low water content compared to SPEEK (Sulfonated Poly(ether ether ketone)) but is also expensive. SPEEK membranes and it's composites have better mechanical properties and have comparatively higher thermal stability. Operating the fuel cell at higher temperatures and at the same time maintaining the water content of the membrane is always a great challenge. In this paper, to increase water retention capacity, Nafion, SPEEK and it's composite (SPEEK PSSA-CNT) membranes are exposed to Ultra-Violet (UV) radiation for varied times. Terahertz Spectroscopy, in both pulsed and CW mode has been used as an efficient tool to quantify the water retention of the membrane. Results using Terahertz spectroscopy show that even though the initial water absorption capacity of Nafion membranes is more, SPEEK membranes and it's composites show considerable improvement in the water retention capacity upon high intensity UV irradiation.

  5. Direct alcohol fuel cells: toward the power densities of hydrogen-fed proton exchange membrane fuel cells.

    PubMed

    Chen, Yanxin; Bellini, Marco; Bevilacqua, Manuela; Fornasiero, Paolo; Lavacchi, Alessandro; Miller, Hamish A; Wang, Lianqin; Vizza, Francesco

    2015-02-01

    A 2 μm thick layer of TiO2 nanotube arrays was prepared on the surface of the Ti fibers of a nonwoven web electrode. After it was doped with Pd nanoparticles (1.5 mgPd  cm(-2) ), this anode was employed in a direct alcohol fuel cell. Peak power densities of 210, 170, and 160 mW cm(-2) at 80 °C were produced if the cell was fed with 10 wt % aqueous solutions of ethanol, ethylene glycol, and glycerol, respectively, in 2 M aqueous KOH. The Pd loading of the anode was increased to 6 mg cm(-2) by combining four single electrodes to produce a maximum peak power density with ethanol at 80 °C of 335 mW cm(-2) . Such high power densities result from a combination of the open 3 D structure of the anode electrode and the high electrochemically active surface area of the Pd catalyst, which promote very fast kinetics for alcohol electro-oxidation. The peak power and current densities obtained with ethanol at 80 °C approach the output of H2 -fed proton exchange membrane fuel cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Performance comparison between high temperature and traditional proton exchange membrane fuel cell stacks using electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Ying; Zhu, Wenhua H.; Tatarchuk, Bruce J.

    2014-06-01

    A temperature above 100 °C is always desired for proton exchange membrane (PEM) fuel cell operation. It not only improves kinetic and mass transport processes, but also facilitates thermal and water management in fuel cell systems. Increased carbon monoxide (CO) tolerance at higher operating temperature also simplifies the pretreatment of fuel supplement. The novel phosphoric acid (PA) doped polybenzimidazole (PBI) membranes achieve PEM fuel cell operations above 100 °C. The performance of a commercial high temperature (HT) PEM fuel cell stack module is studied by measuring its impedance under various current loads when the operating temperature is set at 160 °C. The contributions of kinetic and mass transport processes to stack impedance are analyzed qualitatively and quantitatively by equivalent circuit (EC) simulation. The performance of a traditional PEM fuel cell stack module operated is also studied by impedance measurement and EC simulation. The operating temperature is self-stabilized between 40 °C and 65 °C. An enhancement of the HT-PEM fuel cell stack in polarization impedance is evaluated by comparing to the traditional PEM fuel cell stack. The impedance study on two commercial fuel cell stacks reveals the real situation of current fuel cell development.

  7. Electrochemical durability of heat-treated carbon nanospheres as catalyst supports for proton exchange membrane fuel cells.

    PubMed

    Lv, Haifeng; Wu, Peng; Wan, Wei; Mu, Shichun

    2014-09-01

    Carbon nanospheres is wildly used to support noble metal nanocatalysts in proton exchange membrane (PEM) fuel cells, however they show a low resistance to electrochemical corrosion. In this study, the N-doped treatment of carbon nanospheres (Vulcan XC-72) is carried out in ammonia gas. The effect of heating treatment (up to 1000 degrees C) on resistances to electrochemical oxidation of the N-doped carbon nanospheres (HNC) is investigated. The resistance to electrochemical oxidation of carbon supports and stability of the catalysts are investigated with potentiostatic oxidation and accelerated durability test by simulating PEM fuel cell environment. The HNC exhibit a higher resistance to electrochemical oxidation than traditional Vulcan XC-72. The results show that the N-doped carbon nanospheres have a great potential application in PEM fuel cells.

  8. Long-term testing of a high-temperature proton exchange membrane fuel cell short stack operated with improved polybenzimidazole-based composite membranes

    NASA Astrophysics Data System (ADS)

    Pinar, F. Javier; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Lobato, Justo

    2015-01-01

    In this work, the feasibility of a 150 cm2 high-temperature proton exchange membrane fuel cell (HT-PEMFC) stack operated with modified proton exchange membranes is demonstrated. The short fuel cell stack was manufactured using a total of three 50 cm2 membrane electrode assemblies (MEAs). The PEM technology is based on a polybenzimidazole (PBI) membrane. The obtained results were compared with those obtained using a HT-PEMFC stack with unmodified membranes. The membranes were cast from a PBI polymer synthesized in the laboratory, and the modified membranes contained 2 wt.% micro-sized TiO2 as a filler. Long-term tests were performed in both constant and dynamic loading modes. The fuel cell stack with 2 wt.% TiO2 composite PBI membranes exhibited an irreversible voltage loss of less than 2% after 1100 h of operation. In addition, the acid loss was reduced from 2% for the fuel cell stack with unmodified membranes to 0.6% for the fuel cell stack with modified membranes. The results demonstrate that introducing filler into the membranes enhances the durability and stability of this type of fuel cell technology. Moreover, the fuel cell stack system also exhibits very rapid and stable power and voltage output responses under dynamic load regimes.

  9. Use of Multi-Functional Flexible Micro-Sensors for in situ Measurement of Temperature, Voltage and Fuel Flow in a Proton Exchange Membrane Fuel Cell

    PubMed Central

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased. PMID:22163545

  10. Use of multi-functional flexible micro-sensors for in situ measurement of temperature, voltage and fuel flow in a proton exchange membrane fuel cell.

    PubMed

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased.

  11. Modelling static and dynamic behaviour of proton exchange membrane fuel cells on the basis of electro-chemical description

    NASA Astrophysics Data System (ADS)

    Ceraolo, M.; Miulli, C.; Pozio, A.

    A simplified dynamical model of a fuel cell of the proton exchange membrane (PEM) type, based on physical-chemical knowledge of the phenomena occurring inside the cell has been developed by the authors. The model has been implemented in the MATLAB/SIMULINK environment. Lab tests have been carried out at ENEA's laboratories; and a good agreement has been found between tests and simulations, both in static and dynamic conditions. In a previous study [M. Ceraolo, R. Giglioli, C. Miulli, A. Pozio, in: Proceedings of the 18th International Electric Fuel Cell and Hybrid Vehicle Symposium (EVS18), Berlin, 20-24 October 2001, p. 306] the basic ideas of the model, as well as its experimental validation have been published. In the present paper, the full implementation of the model is reported in detail. Moreover, a procedure for evaluating all the needed numerical parameters is presented.

  12. Technique of laser calibration for wavelength-modulation spectroscopy with application to proton exchange membrane fuel cell measurements.

    PubMed

    Sur, Ritobrata; Boucher, Thomas J; Renfro, Michael W; Cetegen, Baki M

    2010-01-01

    A diode laser sensor was developed for partial pressure and temperature measurements using a single water vapor transition. The Lorentzian half-width and line intensity of the transition were calibrated for conditions relevant to proton exchange membrane (PEM) fuel cell operation. Comparison of measured and simulated harmonics from wavelength-modulation spectroscopy is shown to yield accuracy of +/-2.5% in water vapor partial pressure and +/-3 degrees C in temperature despite the use of a single transition over a narrow range of temperatures. Collisional half-widths in air or hydrogen are measured so that calibrations can be applied to both anode and cathode channels of a PEM fuel cell. An in situ calibration of the nonlinear impact of modulation on laser wavelength is presented and used to improve the accuracy of the numerical simulation of the signal.

  13. High temperature direct methanal-fuel proton exchange membrane fuel cells. Final report

    SciTech Connect

    Lvov, S. N.; Allcock, H. R.; Zhou, X. Y.; Hofmann, M. A.; Chalkova, E.; Fedkin, M. V.; Weston, J. A.; Ambler, C. M.

    2001-10-01

    The lack of proton conductive polymeric membranes stable at high temperatures is one of the main issues impeding the development of DMFCs. The currently employed Nafion membranes are not suitable at temperatures abouve 100 degrees C due to a substantial methanol crossover and poor thermal stability. Therefore, the development of a polymeric membrane stable at high temperatures for DMFCs was the main task of the project. Our approach is based on an interdisciplinary effort that brings together a research group with expertise in the design and synthesis of polyphosphazenes polymer membranes (Allcock Research Laboratory) and a team that has experience in the fields of high temperature electrochemistry and electrochemical energy conversion systems (Lvov Research Laboratory). We have synthesized a new class of ion-exchange membranes for DMFCs.

  14. Surface modification of a proton exchange membrane and hydrogen storage in a metal hydride for fuel cells

    NASA Astrophysics Data System (ADS)

    Andrews, Lisa

    Interest in fuel cell technology is rising as a result of the need for more affordable and available fuel sources. Proton exchange membrane fuel cells involve the catalysis of a fuel to release protons and electrons. It requires the use of a polymer electrolyte membrane to transfer protons through the cell, while the electrons pass through an external circuit, producing electricity. The surface modification of the polymer, NafionRTM, commonly researched as a proton exchange membrane, may improve efficiency of a fuel cell. Surface modification can change the chemistry of the surface of a polymer while maintaining bulk properties. Plasma modification techniques such as microwave discharge of an argon and oxygen gas mixture as well as vacuum-ultraviolet (VUV) photolysis may cause favorable chemical and physical changes on the surface of Nafion for improved fuel cell function. A possible increase in hydrophilicity as a result of microwave discharge experiments may increase proton conductivity. Grafting of acrylic acid from the surface of modified Nafion may decrease the permeation of methanol in a direct methanol fuel cell, a process which can decrease efficiency. Modification of the surface of Nafion samples were carried out using: 1) An indirect Ar/O2 gas mixture plasma investigating the reaction of oxygen radicals with the surface, 2) A direct Ar/O2 gas mixture plasma investigating the reaction of oxygen radicals and VUV radiation with the surface and, 3) VUV photolysis investigating exclusively the interaction of VUV radiation with the surface and any possible oxidation upon exposure to air. Acrylic acid was grafted from the VUV photolysed Nafion samples. All treated surfaces were analyzed using X-ray photoelectron spectroscopy (XPS). Fourier transform infrared spectroscopy (FTIR) was used to analyze the grafted Nafion samples. Scanning electron microscopy (SEM) and contact angle measurements were used to analyze experiments 2 and 3. Using hydrogen as fuel is a

  15. Proton exchange membrane fuel cells for space and electric vehicle applications: From basic research to technology development

    NASA Technical Reports Server (NTRS)

    Srinivasan, Supramaniam; Mukerjee, Sanjeev; Parthasarathy, A.; CesarFerreira, A.; Wakizoe, Masanobu; Rho, Yong Woo; Kim, Junbom; Mosdale, Renaut A.; Paetzold, Ronald F.; Lee, James

    1994-01-01

    The proton exchange membrane fuel cell (PEMFC) is one of the most promising electrochemical power sources for space and electric vehicle applications. The wide spectrum of R&D activities on PEMFC's, carried out in our Center from 1988 to date, is as follows (1) Electrode Kinetic and Electrocatalysis of Oxygen Reduction; (2) Optimization of Structures of Electrodes and of Membrane and Electrode Assemblies; (3) Selection and Evaluation of Advanced Proton Conducting Membranes and of Operating Conditions to Attain High Energy Efficiency; (4) Modeling Analysis of Fuel Cell Performance and of Thermal and Water Management; and (5) Engineering Design and Development of Multicell Stacks. The accomplishments on these tasks may be summarized as follows: (1) A microelectrode technique was developed to determine the electrode kinetic parameters for the fuel cell reactions and mass transport parameters for the H2 and O2 reactants in the proton conducting membrane. (2) High energy efficiencies and high power densities were demonstrated in PEMFCs with low platinum loading electrodes (0.4 mg/cm(exp 2) or less), advanced membranes and optimized structures of membrane and electrode assemblies, as well as operating conditions. (3) The modeling analyses revealed methods to minimize mass transport limitations, particularly with air as the cathodic reactant; and for efficient thermal and water management. (4) Work is in progress to develop multi-kilowatt stacks with the electrodes containing low platinum loadings.

  16. Develpment of Higher Temperature Membrane and Electrode Assembly (MEA) for Proton Exchange Membrane Fuel Cell Devices

    SciTech Connect

    Susan Agro, Anthony DeCarmine, Shari Williams

    2005-12-30

    Our work will fucus on developing higher temperature MEAs based on SPEKK polymer blends. Thse MEAs will be designed to operatre at 120 degrees C Higher temperatures, up to 200 degrees C will also be explored. This project will develop Nafion-free MEAs using only SPEKK blends in both membrane and catalytic layers.

  17. Preparation of catalyst coated membrane by modified decal transfer method for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Indriyati; Irmawati, Y.; Prihandoko, B.

    2017-07-01

    A new catalyst coated membrane (CCM) was prepared by modified decal transfer method. A structure of ionomer/catalyst/carbon/substrate was used to facilitate the transfer of catalyst layer from decal substrate to the membrane at quite low hot-pressing temperature (120 °C) for 8 min. Several decal substrates were tested to select a proper substrate, namely PTFE cloth, PTFE film, aluminium foil, and OHP transparent sheet. The transfer degree of catalyst layer was estimated. Elemental analysis and SEM-mapping were performed to evaluate the residue, whereas contact angle measurement was conducted to characterize the hydrophobicity of decal substrates. The results showed that PTFE cloth and PFTE film transferred approximately 90% of catalyst layer onto the membrane, while the other two substrates were around 70%. Furthermore, the elemental analysis of the residue on the substrate revealed that it was mainly composed of carbon and fluorine for PTFE cloth and PTFE film. This result supports other findings that PTFE cloth and PTFE film are suitable as decal substrate at low temperature hot pressing for fabricating CCM.

  18. An application of indirect model reference adaptive control to a low-power proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Yang, Yee-Pien; Liu, Zhao-Wei; Wang, Fu-Cheng

    2008-05-01

    Nonlinearity and the time-varying dynamics of fuel cell systems make it complex to design a controller for improving output performance. This paper introduces an application of a model reference adaptive control to a low-power proton exchange membrane (PEM) fuel cell system, which consists of three main components: a fuel cell stack, an air pump to supply air, and a solenoid valve to adjust hydrogen flow. From the system perspective, the dynamic model of the PEM fuel cell stack can be expressed as a multivariable configuration of two inputs, hydrogen and air-flow rates, and two outputs, cell voltage and current. The corresponding transfer functions can be identified off-line to describe the linearized dynamics with a finite order at a certain operating point, and are written in a discrete-time auto-regressive moving-average model for on-line estimation of parameters. This provides a strategy of regulating the voltage and current of the fuel cell by adaptively adjusting the flow rates of air and hydrogen. Experiments show that the proposed adaptive controller is robust to the variation of fuel cell system dynamics and power request. Additionally, it helps decrease fuel consumption and relieves the DC/DC converter in regulating the fluctuating cell voltage.

  19. Dimensionally-stable phosphoric acid-doped polybenzimidazoles for high-temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Xiaobai; Ma, Hongwei; Shen, Yanchao; Hu, Wei; Jiang, Zhenhua; Liu, Baijun; Guiver, Michael D.

    2016-12-01

    Phosphoric acid-doped polybenzimidazole (PA-m-PBI) membranes are widely investigated for high temperature proton exchange membrane fuel cells because of their low cost and high performance. For this system, a major challenge is in achieving a good compromise between the phosphoric acid doping level and the membrane dimensional-mechanical stability. Different from the established PA-m-PBI system, the present work investigates two types of PA-PBI membranes incorporating flexible ether linkages and asymmetric bulky pendants (phenyl and methylphenyl), which exhibit much better dimensional-mechanical stability after immersing in PA solution, even at high temperature for an extended period. This superior stability allowed higher acid doping levels (20.6 and 24.6) to be achieved, thus increasing proton conductivity (165 and 217 mS cm-1 at 200 °C under anhydrous conditions) as well as significantly improving fuel cell performance. The peak power densities in hydrogen/air fuel cell were 279 and 320 mW cm-2 at 160 °C, without humidification. Molecular simulation, density and fractional free volume, and wide-angle X-ray diffraction were used to investigate their structure-property relationships.

  20. Investigating the effects of proton exchange membrane fuel cell conditions on carbon supported platinum electrocatalyst composition and performance

    SciTech Connect

    Patel, Anant; Artyushkova, Kateryna; Atanassov, Plamen; Colbow, Vesna; Dutta, Monica; Harvey, Davie; Wessel, Silvia

    2011-12-01

    Changes that carbon-supported platinum electrocatalysts undergo in a proton exchange membrane fuel cell environment were simulated by ex situ heat treatment of catalyst powder samples at 150 C and 100% relative humidity. In order to study modifications that are introduced to chemistry, morphology, and performance of electrocatalysts, XPS, HREELS and three-electrode rotating disk electrode experiments were performed. Before heat treatment, graphitic content varied by 20% among samples with different types of carbon supports, with distinct differences between bulk and surface compositions within each sample. Following the aging protocol, the bulk and surface chemistry of the samples were similar, with graphite content increasing or remaining constant and Pt-carbide decreasing for all samples. From the correlation of changes in chemical composition and losses in performance of the electrocatalysts, we conclude that relative distribution of Pt particles on graphitic and amorphous carbon is as important for electrocatalytic activity as the absolute amount of graphitic carbon present

  1. Investigating the effects of proton exchange membrane fuel cell conditions on carbon supported platinum electrocatalyst composition and performance

    SciTech Connect

    A. Patel; K. Artyushkova; P. Atanassov; V. Colbow; M. Dutta; D. Harvey; S. Wessel

    2012-04-30

    Changes that carbon-supported platinum electrocatalysts undergo in a proton exchange membrane fuel cell environment were simulated by ex situ heat treatment of catalyst powder samples at 150 C and 100% relative humidity. In order to study modifications that are introduced to chemistry, morphology, and performance of electrocatalysts, XPS, HREELS and three-electrode rotating disk electrode experiments were performed. Before heat treatment, graphitic content varied by 20% among samples with different types of carbon supports, with distinct differences between bulk and surface compositions within each sample. Following the aging protocol, the bulk and surface chemistry of the samples were similar, with graphite content increasing or remaining constant and Pt-carbide decreasing for all samples. From the correlation of changes in chemical composition and losses in performance of the electrocatalysts, we conclude that relative distribution of Pt particles on graphitic and amorphous carbon is as important for electrocatalytic activity as the absolute amount of graphitic carbon present

  2. Enhancement of proton exchange membrane fuel cell performance by doping microporous layers of gas diffusion layers with multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Schweiss, Rüdiger; Steeb, Marcus; Wilde, Peter M.; Schubert, Tim

    2012-12-01

    Microporous layers (MPLs) of gas diffusion layers (GDLs) were modified by multiwall carbon nanotubes (MWCNTs) using a wet-chemical approach. Carbon nanotubes were dispersed along with other MPL components and coated onto a GDL backing. The electronic resistance of the GDL was significantly reduced by the addition of MWCNTs. A larger mean pore diameter was obtained as compared to the reference substrates. The improved performance of proton exchange membrane fuel cells (PEMFCs) using such CNT-doped GDLs is attributed to a lower electronic resistance along with improved mass transport. Synergy effects of different carbon materials with MWCNTs and advanced dispersion processes were found to play a key role in achieving the performance improvements.

  3. Hydrocarbon and partially fluorinated sulfonated copolymer blends as functional membranes for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Arnett, Natalie Y.; Harrison, William L.; Badami, Anand S.; Roy, Abhishek; Lane, Ozma; Cromer, Frank; Dong, Limin; McGrath, James E.

    Polymer blending is recognized as a valuable technique used to modify and improve the mechanical, thermal, and surface properties of two different polymers or copolymers. This paper investigated the solution properties and membrane properties of a biphenol-based disulfonated poly (arylene ether sulfone) random copolymer (BPS-35) with hexafluoroisopropylidene bisphenol based sulfonated poly (arylene ether sulfone) copolymers (6FSH) and an unsulfonated biphenol-based poly (arylene ether sulfone)s. The development of blended membranes with desirable surface characteristics, reduced water swelling and similar proton conductivity is presented. Polymer blends were prepared both in the sodium salt and acid forms from dimethylacetamide (DMAc). Water uptake, specific conductivity, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact angles were used to characterize the blended films. Surface enrichment of the fluorinated component is illustrated by an significant increase in the water-surface contact angle was observed when 10 wt.% 6FBPA-00 (106°) was added to BPS 35 (80°). Water weight gain was reduced by a factor of 2.

  4. Analytical Investigation and Improvement of Performance of a Proton Exchange Membrane (Pem) Fuel Cell in Mobile Applications

    NASA Astrophysics Data System (ADS)

    Khazaee, I.

    2015-05-01

    In this study, the performance of a proton exchange membrane fuel cell in mobile applications is investigated analytically. At present the main use and advantages of fuel cells impact particularly strongly on mobile applications such as vehicles, mobile computers and mobile telephones. Some external parameters such as the cell temperature (Tcell ) , operating pressure of gases (P) and air stoichiometry (λair ) affect the performance and voltage losses in the PEM fuel cell. Because of the existence of many theoretical, empirical and semi-empirical models of the PEM fuel cell, it is necessary to compare the accuracy of these models. But theoretical models that are obtained from thermodynamic and electrochemical approach, are very exact but complex, so it would be easier to use the empirical and smi-empirical models in order to forecast the fuel cell system performance in many applications such as mobile applications. The main purpose of this study is to obtain the semi-empirical relation of a PEM fuel cell with the least voltage losses. Also, the results are compared with the existing experimental results in the literature and a good agreement is seen.

  5. In situ measurements of water transfer due to different mechanisms in a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Husar, Attila; Higier, Andrew; Liu, Hongtan

    Water management is of critical importance in a proton exchange membrane (PEM) fuel cell, in particular, those based on a sulfonic acid polymer, which requires water to conduct protons. Yet there are limited in situ studies of water transfer through the membrane and no data are available for water transfer due to individual mechanisms through the membrane in an operational fuel cell. Thus it is the objective of this study to measure water transfer through the membrane due to each individual mechanism in an operational PEM fuel cell. The three different mechanisms of water transfer, i.e., electro-osmotic drag, diffusion and hydraulic permeation are isolated by specially imposed boundary conditions. Therefore water transfer through the membrane due to each mechanism is measured separately. In this study, all the data is collected in an actual assembled operational fuel cell. The experimental results show that water transfer due to hydraulic permeation, i.e. the pressure difference between the anode and cathode is at least an order of magnitude lower than those due to the other two mechanisms. The data for water transfer due to diffusion through the membrane are in good agreement with some of the ex situ data in the literature. The data for electro-osmosis show that the number of water molecules dragged per proton increases not only with temperature but also with current density, which is different from existing data in the literature. The methodology used in this study is simple and can be easily adopted for in situ water transfer measurement due to different mechanisms in other PEM fuel cells without any cell modifications.

  6. Proton exchange membrane fuel cell degradation: A parametric analysis using Computational Fluid Dynamics

    NASA Astrophysics Data System (ADS)

    Ozden, Ender; Tari, Ilker

    2016-02-01

    A Polymer Electrolyte Membrane (PEM) fuel cell is numerically investigated both as fresh and as degraded with the help of observed degradation patterns reported in the literature. The fresh fuel cell model is validated and verified with the data from the literature. Modifying the model by varying the parameters affected by degradation, a degraded PEM fuel cell model is created. The degraded fuel cell is parametrically analyzed by using a commercial Computational Fluid Dynamics (CFD) software. The investigated parameters are the membrane equivalent weight, the Catalyst Layer (CL) porosity and viscous resistance, the Gas Diffusion Layer (GDL) porosity and viscous resistance, and the bipolar plate contact resistance. It is shown for the first time that PEM fuel cell overall degradation can be numerically estimated by combining experimental data from degraded individual components. By comparing the simulation results for the fresh and the degraded PEM fuel cells for two years of operation, it is concluded that the effects of overall degradation on cell potential is significant - estimated to be 17% around the operating point of the fuel cell at 0.95 V open circuit voltage and 70 °C operating temperature.

  7. Improved durability of proton exchange membrane fuel cells by introducing Sn (IV) oxide into electrodes using an ion exchange method

    NASA Astrophysics Data System (ADS)

    Poulsen, M. G.; Larsen, M. J.; Andersen, S. M.

    2017-03-01

    Electrodes of Proton Exchange Membrane Fuel Cells (PEMFCs), consisting of catalyst-coated gas diffusion layers, were subjected to an optimized ion exchange procedure, in which tin (IV) oxide (SnO2) nanoparticles were introduced into them. Both methanol and sulfuric acid were tested as ion exchange solvents. SnO2 has previously been shown to exhibit radical scavenging abilities towards radicals inside the electrocatalyst layers. Its presence inside the electrodes was confirmed using X-ray photoelectron spectroscopy and X-ray fluorescence. After exposure to an accelerated stress test in a three-electrode setup, the electrodes containing SnO2 were found to have retained approximately 73.0% of their original Pt, while only 53.2% was retained in electrodes treated identically, but without Sn. Similarly, the SnO2-treated electrodes also experienced a smaller loss in electrochemical surface area in comparison to before the accelerated stress test. A membrane electrode assembly (MEA) constructed with a SnO2-containing anode was evaluated over 500 h. The results showed remarkably reduced OCV decay rate and end of test hydrogen crossover compared to the control MEA, indicating that SnO2 aids in impeding membrane thinning and pinhole formation. The results point toward a positive effect of SnO2 on fuel cell durability, by reducing the degradation of the membrane as well as of the ionomer in the electrocatalyst layer.

  8. Low platinum loading for high temperature proton exchange membrane fuel cell developed by ultrasonic spray coating technique

    NASA Astrophysics Data System (ADS)

    Su, Huaneng; Jao, Ting-Chu; Barron, Olivia; Pollet, Bruno G.; Pasupathi, Sivakumar

    2014-12-01

    This paper reports use of an ultrasonic-spray for producing low Pt loadings membrane electrode assemblies (MEAs) with the catalyst coated substrate (CCS) fabrication technique. The main MEA sub-components (catalyst, membrane and gas diffusion layer (GDL)) are supplied from commercial manufacturers. In this study, high temperature (HT) MEAs with phosphoric acid (PA)-doped poly(2,5-benzimidazole) (AB-PBI) membrane are fabricated and tested under 160 °C, hydrogen and air feed 100 and 250 cc min-1 and ambient pressure conditions. Four different Pt loadings (from 0.138 to 1.208 mg cm-2) are investigated in this study. The experiment data are determined by in-situ electrochemical methods such as polarization curve, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The high Pt loading MEA exhibits higher performance at high voltage operating conditions but lower performances at peak power due to the poor mass transfer. The Pt loading 0.350 mg cm-2 GDE performs the peak power density and peak cathode mass power to 0.339 W cm-2 and 0.967 W mgPt-1, respectively. This work presents impressive cathode mass power and high fuel cell performance for high temperature proton exchange membrane fuel cells (HT-PEMFCs) with low Pt loadings.

  9. Improving a free air breathing proton exchange membrane fuel cell through the Maximum Efficiency Point Tracking method

    NASA Astrophysics Data System (ADS)

    Higuita Cano, Mauricio; Mousli, Mohamed Islam Aniss; Kelouwani, Sousso; Agbossou, Kodjo; Hammoudi, Mhamed; Dubé, Yves

    2017-03-01

    This work investigates the design and validation of a fuel cell management system (FCMS) which can perform when the fuel cell is at water freezing temperature. This FCMS is based on a new tracking technique with intelligent prediction, which combined the Maximum Efficiency Point Tracking with variable perturbation-current step and the fuzzy logic technique (MEPT-FL). Unlike conventional fuel cell control systems, our proposed FCMS considers the cold-weather conditions, the reduction of fuel cell set-point oscillations. In addition, the FCMS is built to respond quickly and effectively to the variations of electric load. A temperature controller stage is designed in conjunction with the MEPT-FL in order to operate the FC at low-temperature values whilst tracking at the same time the maximum efficiency point. The simulation results have as well experimental validation suggest that propose approach is effective and can achieve an average efficiency improvement up to 8%. The MEPT-FL is validated using a Proton Exchange Membrane Fuel Cell (PEMFC) of 500 W.

  10. Local area water removal analysis of a proton exchange membrane fuel cell under gas purge conditions.

    PubMed

    Lee, Chi-Yuan; Lee, Yu-Ming; Lee, Shuo-Jen

    2012-01-01

    In this study, local area water content distribution under various gas purging conditions are experimentally analyzed for the first time. The local high frequency resistance (HFR) is measured using novel micro sensors. The results reveal that the liquid water removal rate in a membrane electrode assembly (MEA) is non-uniform. In the under-the-channel area, the removal of liquid water is governed by both convective and diffusive flux of the through-plane drying. Thus, almost all of the liquid water is removed within 30 s of purging with gas. However, liquid water that is stored in the under-the-rib area is not easy to remove during 1 min of gas purging. Therefore, the re-hydration of the membrane by internal diffusive flux is faster than that in the under-the-channel area. Consequently, local fuel starvation and membrane degradation can degrade the performance of a fuel cell that is started from cold.

  11. Local Area Water Removal Analysis of a Proton Exchange Membrane Fuel Cell under Gas Purge Conditions

    PubMed Central

    Lee, Chi-Yuan; Lee, Yu-Ming; Lee, Shuo-Jen

    2012-01-01

    In this study, local area water content distribution under various gas purging conditions are experimentally analyzed for the first time. The local high frequency resistance (HFR) is measured using novel micro sensors. The results reveal that the liquid water removal rate in a membrane electrode assembly (MEA) is non-uniform. In the under-the-channel area, the removal of liquid water is governed by both convective and diffusive flux of the through-plane drying. Thus, almost all of the liquid water is removed within 30 s of purging with gas. However, liquid water that is stored in the under-the-rib area is not easy to remove during 1 min of gas purging. Therefore, the re-hydration of the membrane by internal diffusive flux is faster than that in the under-the-channel area. Consequently, local fuel starvation and membrane degradation can degrade the performance of a fuel cell that is started from cold. PMID:22368495

  12. Deactivation of Pt/VC proton exchange membrane fuel cell cathodes by SO2, H2S and COS

    NASA Astrophysics Data System (ADS)

    Gould, Benjamin D.; Baturina, Olga A.; Swider-Lyons, Karen E.

    Sulfur contaminants in air pose a threat to the successful operation of proton exchange membrane fuel cells (PEMFCs) via poisoning of the Pt-based cathodes. The deactivation behavior of commercial Pt on Vulcan carbon (Pt/VC) membrane electrode assemblies (MEAs) is determined when exposed to 1 ppm (dry) of SO 2, H 2S, or COS in air for 3, 12, and 24 h while held at a constant potential of 0.6 V. All the three sulfur compounds cause the same deactivation behavior in the fuel cell cathodes, and the polarization curves of the poisoned MEAs have the same decrease in performance. Sulfur coverages after multiple exposure times (3, 12, and 24 h) are determined by cyclic voltammetry (CV). As the exposure time to sulfur contaminants increases from 12 to 24 h, the sulfur coverage of the platinum saturates at 0.45. The sulfur is removed from the cathodes and their activity is partially restored both by cyclic voltammetry, as shown by others, and by successive polarization curves. Complete recovery of fuel cell performance is not achieved with either technique, suggesting that sulfur species permanently affect the surface of the catalyst.

  13. Modeling hydrogen starvation conditions in proton-exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ohs, Jan Hendrik; Sauter, Ulrich; Maass, Sebastian; Stolten, Detlef

    In this study, a steady state and isothermal 2D-PEM fuel cell model is presented. By simulation of a single cell along the channel and in through-plane direction, its behaviour under hydrogen starvation due to nitrogen dilution is analysed. Under these conditions, carbon corrosion and water electrolysis are observed on the cathode side. This phenomenon, causing severe cell degradation, is known as reverse current decay mechanism in literature. Butler-Volmer equations are used to model the electrochemical reactions. In addition, we account for permeation of gases through the membrane and for the local water content within the membrane. The results show that the membrane potential locally drops in areas starved from hydrogen. This leads to potential gradients >1.2 V between electrode and membrane on the cathode side resulting in significant carbon corrosion and electrolysis reaction rates. The model enables the analysis of sub-stoichiometric states occurring during anode gas recirculation or load transients.

  14. Preparation and properties of high performance nanocomposite proton exchange membrane for fuel cell

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Feng; Yen, Chuan-Yu; Ma, Chen-Chi M.; Liao, Shu-Hang; Hung, Chih-Hung; Hsiao, Yi-Hsiu

    Various spatially enlarged organoclays were prepared by using poly(oxyproplene)-backboned quaternary ammonium salts of various molecular weights M w 230, 400 and 2000 as the intercalating agents for Na +-montmorillonite. The modified MMT was utilized to improve the compatibility with Nafion ®. Sufficient interaction of the modified MMT with Nafion ® was studied by using X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS). The performance of the Nafion ®/ m-MMT composite membranes for direct methanol fuel cell (DMFCs) was evaluated in terms of water uptake, ion exchange capacity (IEC), methanol permeability, proton conductivity, and cell performance. The methanol permeability of the composite membrane decreased with the increasing of m-MMT content. The proton conductivity of the membrane was lowered slightly from that of pristine Nafion ® membrane. These results led to an essential improvement in the single-cell performance of DMFCs.

  15. Electrolyte incorporation into composite electrodes for proton-exchange membrane fuel cells and lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Oh, Jung Min

    2011-12-01

    This dissertation describes research on the preparation and characterization of composite electrodes for use in proton-exchange membrane (PEM) fuel cells and lithium ion batteries. The general focus of the research was on high-surface-area carbon supports for platinum catalysts in fuel cells, and integration of electrolytes, particularly fluoropolymer electrolytes, into composite electrodes both batteries and fuel cells. Results are described for work in the following three specific topical areas. (1) Carbon nanofibers for use as platinum (Pt) catalyst supports in fuel cells were prepared by carbonization of electrospun acrylic fibers. The resulting carbon nanofibers were found to contain mainly micropores. Following grinding to a powder form, the carbon nanofibers were used as supports for Pt nanoparticles. The pulverized carbon nanofibers were found to be not suitable as supports for Pt catalysts because the microporosity of the individual carbon nanofibers cannot provide continuous porous channels in the electrode. As a result, the Pt utilization was found to be low. (2) Mesoporous carbon composites containing nanoscale embedded zirconia particles (ZCS) were prepared and found to be highly porous and electrically conductive. Surface modification of the composites with organic compounds having phenylphosphonic acid groups (e.g., phenylphosphonic acid, m-sulfophenylphosphonic acid, or sulfonated fluoropolymer ionomer having terminal phosphonic acid groups) was accomplished by simple exposure of the carbon composite to organophosphonate solutions. Nanoscale ZrO2 surfaces present in the composite skeleton acted as reactive sites for anchoring of phosphonates through formation of robust Zr--O--P bonding. Proton-exchange sites were introduced onto the nanocomposite surface by grafting m-sulfophenylphosphonic acid or a sulfonated fluoropolymer ionomer. Modification with the ionomer provided an increase in proton-exchange capacity relative to that found following

  16. Analysis of the behavior and degradation in proton exchange membrane fuel cells with a dead-ended anode

    NASA Astrophysics Data System (ADS)

    Yu, Jianliang; Jiang, Zuwei; Hou, Ming; Liang, Dong; Xiao, Yu; Dou, Meiling; Shao, Zhigang; Yi, Baolian

    2014-01-01

    Proton exchange membrane fuel cells (PEMFCs) with a dead-ended anode (DEA) can obtain high hydrogen utilization by a comparatively simple system. Nevertheless, the accumulation of the nitrogen and the water in the anode channels can lead to a local fuel starvation, which degrades the performance and durability of PEMFCs. In this paper, the behaviors of PEMFCs with a DEA are explored experimentally by detecting the current distribution and the local potentials. The results indicate that the current distribution is uneven during the DEA operation. The local current firstly decreases at the region near the anode outlet, and then extends to the inlet region along the channels with time. The complete fuel starvation near the anode outlet leads to a high local potential and carbon corrosion on the cathode side. The SEM images of the cathode electrode reveal that the significant thickness reduction and the collapse of the electrode's porous structure happen in the cathode catalyst layer, leading to the irreversible decline of the performance. The comparison of the experiments with different oxidants and fuels reveals that the nitrogen crossover from cathode to anode is the dominant factor on the performance decline under the DEA operations.

  17. Understanding the gas diffusion layer in proton exchange membrane fuel cells. I. How its structural characteristics affect diffusion and performance

    NASA Astrophysics Data System (ADS)

    Morgan, Jason M.; Datta, Ravindra

    2014-04-01

    The proton exchange membrane fuel cell (PEMFC) has a significant potential in transportation, backup, and portable power applications, although there still are remaining technical and cost challenges. A key current goal is improving the performance while reducing the cost of the gas diffusion layer (GDL). Designing a commercial GDL, however, is far more complex than simply making a porous, sturdy, conductive layer, because of the trade-offs among performance, manufacturability, and cost. An improved understanding of its multifarious functions in the fuel cell can help attain this goal. Here, we identify 11 key characteristic parameters of the GDL and their significance to its performance. We begin a discussion of some of these parameters in this paper, specifically those related to the structure of the GDL substrate and the microporous layer (MPL), how these are measured experimentally ex-situ, how they influence fuel cell performance, and how they can be altered via the manufacturing process. In particular, we investigate the correlation between ex-situ measured effective diffusivity of water vapor and in-situ performance and limiting current density in a PEM fuel cell. Further, we examine the effect of adding multiple MPLs, MPL loading, and MPL particle size on cell performance under both wet and dry operating conditions.

  18. Influence of various carbon nano-forms as supports for Pt catalyst on proton exchange membrane fuel cell performance

    NASA Astrophysics Data System (ADS)

    Bharti, Abha; Cheruvally, Gouri

    2017-08-01

    In this study, we discuss the influence of various carbon supports for Pt on proton exchange membrane (PEM) fuel cell performance. Here, Pt supported on various carbon nano-forms [Pt/carbon black (Pt/CB), Pt/single-walled carbon nanotubes (Pt/SWCNT), Pt/multi-walled carbon nanotubes (Pt/MWCNT) and Pt/graphene (Pt/G)] are synthesized by a facile, single step, microwave-assisted, modified chemical reduction route. Their physical, chemical and electrochemical characteristics pertaining to oxygen reduction reaction (ORR) catalytic activity and stability in PEM fuel cell are studied in detail by various techniques and compared. The study shows that the different carbon supports does not significantly affect the Pt particle size during synthesis, but leads to different amount of defective sites in the carbon framework which influence both the availability of active metal nano-catalysts and metal-support interaction. In-situ electrochemical investigations reveal that the different carbon supports influence both ORR catalytic activity and stability of the catalyst. This is further corroborated by the demonstration of varying polarization characteristics on PEM fuel cell performance by different carbon supported Pt catalysts. This study reveals MWCNT as the most suitable carbon support for Pt catalyst, exhibiting high activity and stability for ORR in PEM fuel cell.

  19. Issues associated with modelling of proton exchange membrane fuel cell by computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Bednarek, Tomasz; Tsotridis, Georgios

    2017-03-01

    The objective of the current study is to highlight possible limitations and difficulties associated with Computational Fluid Dynamics in PEM single fuel cell modelling. It is shown that an appropriate convergence methodology should be applied for steady-state solutions, due to inherent numerical instabilities. A single channel fuel cell model has been taken as numerical example. Results are evaluated for quantitative as well qualitative points of view. The contribution to the polarization curve of the different fuel cell components such as bi-polar plates, gas diffusion layers, catalyst layers and membrane was investigated via their effects on the overpotentials. Furthermore, the potential losses corresponding to reaction kinetics, due to ohmic and mas transport limitations and the effect of the exchange current density and open circuit voltage, were also investigated. It is highlighted that the lack of reliable and robust input data is one of the issues for obtaining accurate results.

  20. Membrane electrode assembly with enhanced platinum utilization for high temperature proton exchange membrane fuel cell prepared by catalyst coating membrane method

    NASA Astrophysics Data System (ADS)

    Liang, Huagen; Su, Huaneng; Pollet, Bruno G.; Linkov, Vladimir; Pasupathi, Sivakumar

    2014-11-01

    In this work, membrane electrode assemblies (MEAs) prepared by catalyst coating membrane (CCM) method are investigated for reduced platinum (Pt) loading and improved Pt utilization of high temperature proton exchange membrane fuel cell (PEMFC) based on phosphoric acid (PA)-doped poly(2,5-benzimidazole) (AB-PBI) membrane. The results show that CCM method exhibits significantly higher cell performance and Pt-specific power density than that of MEAs prepared with conventional gas diffusion electrode (GDE) under a low Pt loading level. In-suit cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) show that the MEAs prepared by the CCM method have a higher electrochemical surface area (ECSA), low cell ohmic resistance and low charge transfer resistance as compared to those prepared with GDEs at the same Pt loading.

  1. Three-dimensional two-phase flow model of proton exchange membrane fuel cell with parallel gas distributors

    NASA Astrophysics Data System (ADS)

    Liu, Xunliang; Lou, Guofeng; Wen, Zhi

    A non-isothermal, steady-state, three-dimensional (3D), two-phase, multicomponent transport model is developed for proton exchange membrane (PEM) fuel cell with parallel gas distributors. A key feature of this work is that a detailed membrane model is developed for the liquid water transport with a two-mode water transfer condition, accounting for the non-equilibrium humidification of membrane with the replacement of an equilibrium assumption. Another key feature is that water transport processes inside electrodes are coupled and the balance of water flux is insured between anode and cathode during the modeling. The model is validated by the comparison of predicted cell polarization curve with experimental data. The simulation is performed for water vapor concentration field of reactant gases, water content distribution in the membrane, liquid water velocity field and liquid water saturation distribution inside the cathode. The net water flux and net water transport coefficient values are obtained at different current densities in this work, which are seldom discussed in other modeling works. The temperature distribution inside the cell is also simulated by this model.

  2. Non-covalent bonding interaction of surfactants with functionalized carbon nanotubes in proton exchange membranes for fuel cell applications.

    PubMed

    Sayeed, M Abu; Kim, Young Ho; Park, Younjin; Gopalan, A I; Lee, Kwang-Pill; Choi, Sang-June

    2013-11-01

    Dispersion of functionalized multiwalled carbon nanotubes (MWCNTs) in proton exchange membranes (PEMs) was conducted via non-covalent bonding between benzene rings of various surfactants and functionalized MWCNTs. In the solution casting method, dispersion of functionalized MWCNTs in PEMs such as Nafion membranes is a critical issue. In this study, 1 wt.% pristine MWCNTs (p-MWCNTs) and oxidized MWCNTs (ox-MWCNTs) were reinforced in Nafion membranes by adding 0.1-0.5 wt.% of a surfactant such as benzalkonium chloride (BKC) as a cationic surfactant with a benzene ring, Tween-80 as a nonanionic surfactant without a benzene ring, sodium dodecylsulfonate (SDS) as an anionic surfactant without a benzene ring, or sodium dodecylben-zenesulfonate (SDBS) as an anionic surfactant with a benzene ring and their effects on the dispersion of nanocomposites were then observed. Among these surfactants, those with benzene rings such as BKC and SDBS produced enhanced dispersion via non-covalent bonding interaction between CNTs and surfactants. Specifically, the surfactants were adsorbed onto the surface of functionalized MWCNTs, where they prevented re-aggregation of MWCNTs in the nanocomposites. Furthermore, the prepared CNTs reinforced nanocomposite membranes showed reduced methanol uptake values while the ion exchange capacity values were maintained. The enhanced properties, including thermal property of the CNTs reinforced PEMs with surfactants, could be applicable to fuel cell applications.

  3. Polymeric nanocomposite proton exchange membranes prepared by radiation-induced polymerization for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Kim, Young-Seok; Seo, Kwang-Seok; Choi, Seong-Ho

    2016-01-01

    The vinyl group-modified montmorillonite clay (F-MMT), vinyl group-modified graphene oxide (F-GO), and vinyl group-modified multi-walled carbon nanotube (F-MWNT) were first prepared by ion exchange reaction of 1-[(4-ethylphenyl)methyl]-3-butyl-imidazolium chloride in order to use the materials for protection against methanol cross-over in direct methanol fuel cell (DMFC) membrane. Then polymeric nanocomposite membranes with F-MMT, F-GO, and F-MWNT were prepared by the solvent casting method after radiation-induced polymerization of vinyl monomers in water-methanol mixture solvents. The proton conductivity, water uptake, ion-exchange capacity, methanol permeability, and DMFC performance of the polymeric nanocomposite membranes with F-MMT, F-GO, and F-MWNT were evaluated.

  4. Improvement the equation of polarization curve of a proton exchange membrane fuel cell at different channel geometry

    NASA Astrophysics Data System (ADS)

    Khazaee, I.

    2015-12-01

    The polarization curve of a proton exchange membrane fuel cell is an important parameter which is expressed by the change of voltage and current of it that indicates the performance of the cell. The voltage of the cell is a function of temperature that is expressed by the Nernst equation and the equation of voltage losses such as activation loss, ohmic loss and concentration loss. In this study a new correlation for polarization curve is obtained that it in addition to temperature, a new parameter is involved in it that shows the effect of the geometry of cross-section area of channels. For this purpose three PEM fuel cells with different channels geometry of rectangular, elliptical and triangular have constructed. The active area of each cell is 25 cm2 that its weight is 1300 g. The material of the gas diffusion layer is carbon clothes, the membrane is nafion 117 and the catalyst layer is a plane with 0.004 g/cm2 platinum. Also a test bench designed and constructed for testing the cell and a series of experiments are carried out to investigate the influence of the geometry of the cell on performance of the cell. The results show that when the geometry of channel is rectangular the performance of the cell is better than the triangular and elliptical channel.

  5. Synthesis of transport layers with controlled anisotropy and application thereof to study proton exchange membrane fuel cell performance

    NASA Astrophysics Data System (ADS)

    Todd, Devin; Mérida, Walter

    2016-04-01

    We report on a novel method for the synthesis of fibre-based proton exchange membrane (PEM) fuel cell porous transport layers (PTLs) with controllable fibre alignment. We also report the first application of such layers as diagnostics tools to probe the effect of within-plane PTL anisotropy upon PEM fuel cell performance. These structures are realized via adaptation of electrospinning technology. Electrospun layers with progressive anisotropy magnitude are produced and evaluated. This novel approach is distinguished from the state-of-the-art because an equivalent study using commercially available materials is impossible due to lack of structurally similar substrates with different anisotropies. The anisotropy is visualized via scanning electron microscopy, and quantified using electrical resistivity. The capacity is demonstrated to achieve fibre alignment, and the associated impact on transport properties. A framework is presented for assessing the in-situ performance, whereby transport layer orientation versus bipolar plate flow-field geometry is manipulated. While an effect upon the commercial baseline cannot be discerned, electrospun transport layers with greater anisotropy magnitude suggest greater sensitivity to orientation; where greater performance is obtained with fibres cross-aligned to flow-field channels. Our approach of electrospun transport enables deterministic structures by which fuel cell performance can be explained and optimized.

  6. A review of composite and metallic bipolar plates in proton exchange membrane fuel cell: Materials, fabrication, and material selection

    NASA Astrophysics Data System (ADS)

    Taherian, Reza

    2014-11-01

    Proton exchange membrane (PEM) fuel cells offer exceptional potential for a clean, efficient, and reliable power source. The bipolar plate (BP) is a key component in this device, as it connects each cell electrically, supplies reactant gases to both anode and cathode, and removes reaction products from the cell. BPs have primarily been fabricated from high-density graphite, but in recent years, much attention has been paid to develop the cost-effective and feasible alternative materials. Recently, two different classes of materials have been attracted attention: metals and composite materials. This paper offers a comprehensive review of the current researches being carried out on the metallic and composite BPs, covering materials and fabrication methods. In this research, the phenomenon of ionic contamination due to the release of the corrosion products of metallic BP and relative impact on the durability as well as performance of PEM fuel cells is extensively investigated. Furthermore, in this paper, upon several effective parameters on commercialization of PEM fuel cells, such as stack cost, weight, volume, durability, strength, ohmic resistance, and ionic contamination, a material selection is performed among the most common BPs currently being used. This material selection is conducted by using Simple Additive Weighting Method (SAWM).

  7. Improvement of proton-exchange membrane fuel cell performance using platinum-loaded carbon black entrapped in crosslinked chitosan

    NASA Astrophysics Data System (ADS)

    Phompan, Waranya; Hansupalak, Nanthiya

    To improve the performance of proton-exchange membrane fuel cells which use hydrogen and oxygen as fuels, the application of small proton-conducting polymer to extend the three-phase boundary into the primary pores of catalyst-loaded carbon black agglomerates is of interest. An alternative and simple crosslinking method is proposed in place of the complicated polymer-grafting methods. Platinum-loaded carbon black is entrapped in epichlorohydrin-crosslinked chitosan of low molecular weight. Morphology and pore analyses of carbon black prior and post treatment are assessed, as well as performances of fuel cells fabricated with the treated and the untreated carbon black at 40 °C and 100% humidity. Results indicate the existence of chitosan chains in the primary pores of the carbon black agglomerates, corresponding to a decline in the activation overvoltage and resulting in significantly better cell performance. An increase in chitosan amount, however, does not necessarily enhance the cell performance because effects of ohmic and concentration losses may become more dominant than that of the raised exchange current density of the cell.

  8. High energy efficiency and high power density proton exchange membrane fuel cells: Electrode kinetics and mass transport

    NASA Technical Reports Server (NTRS)

    Srinivasan, Supramaniam; Velev, Omourtag A.; Parthasathy, Arvind; Manko, David J.; Appleby, A. John

    1991-01-01

    The development of proton exchange membrane (PEM) fuel cell power plants with high energy efficiencies and high power densities is gaining momentum because of the vital need of such high levels of performance for extraterrestrial (space, underwater) and terrestrial (power source for electric vehicles) applications. Since 1987, considerable progress has been made in achieving energy efficiencies of about 60 percent at a current density of 200 mA/sq cm and high power densities (greater than 1 W/sq cm) in PEM fuel cells with high (4 mg/sq cm) or low (0.4 mg/sq cm) platinum loadings in electrodes. The following areas are discussed: (1) methods to obtain these high levels of performance with low Pt loading electrodes - by proton conductor impregnation into electrodes, localization of Pt near front surface; (2) a novel microelectrode technique which yields electrode kinetic parameters for oxygen reduction and mass transport parameters; (3) demonstration of lack of water transport from anode to cathode; (4) modeling analysis of PEM fuel cell for comparison with experimental results and predicting further improvements in performance; and (5) recommendations of needed research and development for achieving the above goals.

  9. High energy efficiency and high power density proton exchange membrane fuel cells: Electrode kinetics and mass transport

    NASA Technical Reports Server (NTRS)

    Srinivasan, Supramaniam; Velev, Omourtag A.; Parthasathy, Arvind; Manko, David J.; Appleby, A. John

    1991-01-01

    The development of proton exchange membrane (PEM) fuel cell power plants with high energy efficiencies and high power densities is gaining momentum because of the vital need of such high levels of performance for extraterrestrial (space, underwater) and terrestrial (power source for electric vehicles) applications. Since 1987, considerable progress has been made in achieving energy efficiencies of about 60 percent at a current density of 200 mA/sq cm and high power densities (greater than 1 W/sq cm) in PEM fuel cells with high (4 mg/sq cm) or low (0.4 mg/sq cm) platinum loadings in electrodes. The following areas are discussed: (1) methods to obtain these high levels of performance with low Pt loading electrodes - by proton conductor impregnation into electrodes, localization of Pt near front surface; (2) a novel microelectrode technique which yields electrode kinetic parameters for oxygen reduction and mass transport parameters; (3) demonstration of lack of water transport from anode to cathode; (4) modeling analysis of PEM fuel cell for comparison with experimental results and predicting further improvements in performance; and (5) recommendations of needed research and development for achieving the above goals.

  10. Analysis of the control structures for an integrated ethanol processor for proton exchange membrane fuel cell systems

    NASA Astrophysics Data System (ADS)

    Biset, S.; Nieto Deglioumini, L.; Basualdo, M.; Garcia, V. M.; Serra, M.

    The aim of this work is to investigate which would be a good preliminary plantwide control structure for the process of Hydrogen production from bioethanol to be used in a proton exchange membrane (PEM) accounting only steady-state information. The objective is to keep the process under optimal operation point, that is doing energy integration to achieve the maximum efficiency. Ethanol, produced from renewable feedstocks, feeds a fuel processor investigated for steam reforming, followed by high- and low-temperature shift reactors and preferential oxidation, which are coupled to a polymeric fuel cell. Applying steady-state simulation techniques and using thermodynamic models the performance of the complete system with two different control structures have been evaluated for the most typical perturbations. A sensitivity analysis for the key process variables together with the rigorous operability requirements for the fuel cell are taking into account for defining acceptable plantwide control structure. This is the first work showing an alternative control structure applied to this kind of process.

  11. Experimental diagnostics and modeling of inductive phenomena at low frequencies in impedance spectra of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Pivac, Ivan; Šimić, Boris; Barbir, Frano

    2017-10-01

    Representation of fuel cell processes by equivalent circuit models, involving resistance and capacitance elements representing activation losses on both anode and cathode in series with resistance representing ohmic losses, cannot capture and explain the inductive loop that may show up at low frequencies in Nyquist diagram representation of the electrochemical impedance spectra. In an attempt to explain the cause of the low-frequency inductive loop and correlate it with the processes within the fuel cell electrodes, a novel equivalent circuit model of a Proton Exchange Membrane (PEM) fuel cell has been proposed and experimentally verified here in detail. The model takes into account both the anode and the cathode, and has an additional resonant loop on each side, comprising of a resistance, capacitance and inductance in parallel representing the processes within the catalyst layer. Using these additional circuit elements, more accurate and better fits to experimental impedance data in the wide frequency range at different current densities, cell temperatures, humidity of gases, air flow stoichiometries and backpressures were obtained.

  12. Proton exchange membranes for application in fuel cells: grafted silica/SPEEK nanocomposite elaboration and characterization.

    PubMed

    Reinholdt, Marc X; Kaliaguine, Serge

    2010-07-06

    Hydrogen technologies and especially fuel cells are key components in the battle to find alternate sources of energy to the highly polluting and economically constraining fossil fuels in an aim to preserve the environment. The present paper shows the synthesis of surface functionalized silica nanoparticles, which are used to prepare grafted silica/SPEEK nanocomposite membranes. The nanoparticles are grafted either with hexadecylsilyl or aminopropyldimethylsilyl moieties or both. The synthesized particles are analyzed using XRD, NMR, TEM, and DLS to collect information on the nature of the particles and the functional groups, on the particle sizes, and on the hydrophilic/hydrophobic character. The composite membranes prepared using the synthesized particles and two SPEEK polymers with sulfonation degrees of 69.4% and 85.0% are characterized for their proton conductivity and water uptake properties. The corresponding curves are very similar for the composites prepared with both polymers and the nanoparticles bearing the two functional groups. The composites prepared with the nanoparticles bearing solely the aminopropyldimethylsilyl moiety exhibit lower conductivity and water uptake, possibly due to higher interaction of the polymer sulfonic acid sites with the amine groups. The composites prepared with the nanoparticles bearing solely the hexadecylsilyl moiety were not further investigated because of very high particles segregation. A study of the proton conductivity as a function of temperature was performed on selected membranes and showed that nanocomposites made with nanoparticles bearing both functional moieties have a higher conductivity at higher temperatures.

  13. Effective Transport Properties Accounting for Electrochemical Reactions of Proton-Exchange Membrane Fuel Cell Catalyst Layers

    SciTech Connect

    Pharoah, Jon; Choi, Hae-Won; Chueh, Chih-Che; Harvey, David

    2011-07-01

    There has been a rapidly growing interest in three-dimensional micro-structural reconstruction of fuel cell electrodes so as to derive more accurate descriptors of the pertinent geometric and effective transport properties. Due to the limited accessibility of experiments based reconstruction techniques, such as dual-beam focused ion beam-scanning electro microscopy or micro X-Ray computed tomography, within sample micro-structures of the catalyst layers in polymer electrolyte membrane fuel cells (PEMFCs), a particle based numerical model is used in this study to reconstruct sample microstructure of the catalyst layers in PEMFCs. Then the reconstructed sample structure is converted into the computational grid using body-fitted/cut-cell based unstructured meshing technique. Finally, finite volume methods (FVM) are applied to calculate effective properties on computational sample domains.

  14. Mechanical and transport properties of layer-by-layer electrospun composite proton exchange membranes for fuel cell applications.

    PubMed

    Mannarino, Matthew M; Liu, David S; Hammond, Paula T; Rutledge, Gregory C

    2013-08-28

    Composite membranes composed of highly conductive and selective layer-by-layer (LbL) films and electrospun fiber mats were fabricated and characterized for mechanical strength and electrochemical selectivity. The LbL component consists of a proton-conducting, methanol-blocking poly(diallyl dimethyl ammonium chloride)/sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (PDAC/sPPO) thin film. The electrospun fiber component consists of poly(trimethyl hexamethylene terephthalamide) (PA 6(3)T) fibers in a nonwoven mat of 60-90% porosity. The bare mats were annealed to improve their mechanical properties, which improvements are shown to be retained in the composite membranes. Spray LbL assembly was used as a means for the rapid formation of proton-conducting films that fill the void space throughout the porous electrospun matrix and create a fuel-blocking layer. Coated mats as thin as 15 μm were fabricated, and viable composite membranes with methanol permeabilities 20 times lower than Nafion and through-plane proton selectivity five and a half times greater than Nafion are demonstrated. The mechanical properties of the spray coated electrospun mats are shown to be superior to the LbL-only system and possess intrinsically greater dimensional stability and lower mechanical hysteresis than Nafion under hydrated conditions. The composite proton exchange membranes fabricated here were tested in an operational direct methanol fuel cell. The results show the potential for higher open circuit voltages (OCV) and comparable cell resistances when compared to fuel cells based on Nafion.

  15. Anisotropic amplification of proton transport in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Thimmappa, Ravikumar; Fawaz, Mohammed; Devendrachari, Mruthyunjayachari Chattanahalli; Gautam, Manu; Kottaichamy, Alagar Raja; Shafi, Shahid Pottachola; Thotiyl, Musthafa Ottakam

    2017-07-01

    Though graphene oxide (GO) membrane shuttles protons under humid conditions, it suffer severe disintegration and anhydrous conditions lead to abysmal ionic conductivity. The trade-off between mechanical integrity and ionic conductivity challenge the amplification of GO's ionic transport under anhydrous conditions. We show anisotropic amplification of GO's ionic transport with a selective amplification of in plane contribution under anhydrous conditions by doping it with a plant extract, phytic acid (PA). The hygroscopic nature of PA stabilized interlayer water molecules and peculiar geometry of sbnd OH functionalities around saturated hydrocarbon ring anisotropically enhanced ionic transport amplifying the fuel cell performance metrics.

  16. Poly(organophosphazenes) with azolylmethylphenoxy and pyridinoxy side groups to be used as proton exchange membranes in fuel cells

    NASA Astrophysics Data System (ADS)

    Ekanayake, Sujeewani K.

    2011-12-01

    Proton Exchange Membrane Fuel Cells (PEMFCs) are of great importance to many stationary and portable applications. The development of a more efficient, high-temperature tolerant membrane with a high protonic conductivity has become critical to the better performance of PEMFCs. Consequently, the focus of current research is more focused on synthesizing membranes which can function at a non-humidified high temperature environment. Because N-heterocycles such as azoles substituted on a polyphosphazene backbone have been found to be one of the best polymers in this regard, the focus of this dissertation is primarily on developing PEMs (proton exchange membranes) based on azole and pyridine substituted phosphazenes. In Chapter 1, an overview on PEMFCs as well as PEMs that have been synthesized to date is presented. The first part of the introduction is devoted to sulfonated fluorocarbon-based membrane, NafionRTM. Then the focus slowly shifts towards PEMs based on hydrocarbon polymers. The rest of Chapter 1 mainly revolves around polyphosphazene based PEMs. Chapter 2 describes the synthesis of trimeric, small-molecule, model compounds for high polymers. A series of hexakis(azolylmethylphenoxy)cyclotriphosphazenes where the azolyl groups are pyrazol, 1,2,4-triazol and 5-methyltetrazol and all three isomers of hexakis(pyridinoxy)cyclotriphosphazenes have been synthesized and characterized. The focus of Chapter 3 is on the synthesis of poly(dichlorophosphazene) by modifying a literature procedure reported by Wang (Macromolecules 2005, 38, 643--645) via one-pot in situ polycondensation. Chapter 3 also presents a preliminary study on ring opening polymerization. The focus of Chapter 4 is completely on the synthesis and characterization of azole and pyridine substituted polyphosphazenes. Chapter 5 includes film casting studies from both triazolphenol trimer and polymer to obtain corresponding composites and blends by mixing with commercially available poly(PMDA-ODA) amic acid

  17. Computational modeling of transport and electrochemical reactions in proton-exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Um, Sukkee

    A comprehensive, multi-physics computational fuel cell dynamics (CFCD) model integrating electrochemical kinetics, charge transport, mass transport (particularly water transport), and flow dynamics is developed in this thesis. The numerical model is validated against published experimental data and utilized to generate results that reveal the internal operation of a PEM fuel cell. A number of model applications are demonstrated in the present work. First, the CFCD model is applied to explore hydrogen dilution effects in the anode feed. Detailed two-dimensional electrochemical and flow/transport simulations are provided to examine substantial anode concentration polarization due to hydrogen depletion at the reaction sites. A transient simulation of the cell current response to a step change in cell voltage is also attempted to elucidate characteristics of the dynamic response of a fuel cell for the first time. After the two-dimensional computational study, the CFCD model is applied to illustrate three-dimensional interactions between mass transfer and electrochemical kinetics. Emphasis is placed on obtaining a fundamental understanding of fully three-dimensional flow in the air cathode with interdigitated flowfield design and how it impacts the transport and electrochemical reaction processes. The innovative design concept for enhanced oxygen transport to, and effective water removal from the cathode, is explored numerically. Next, an analytical study of water transport is performed to investigate various water transport regimes of practical interest. The axial locations characteristic of anode water loss and cathode flooding are predicted theoretically and compared with numerical results. A continuous stirred fuel cell reactor (CSFCR) model is also proposed for the limiting situation where the anode and cathode sides reach equilibrium in water concentration with a thin ionomer membrane in between. In addition to the analytical solutions, a detailed water transport

  18. Effect of System Contaminants on the Performance of a Proton Exchange Membrane Fuel Cell

    DOE PAGES

    Mehrabadi, Bahareh Alsadat Tavakoli; Dinh, Huyen N.; Bender, Guido; ...

    2016-11-10

    The performance loss and recovery of the fuel cell due to Balance of Plant (BOP) contaminants was identified via a combination of experimental data and a mathematical model. The experiments were designed to study the influence of organic contaminants (e.g. those from BOP materials) on the resistance of the catalyst, ionomer and membrane, and a mathematical model was developed that allowed us to separate these competing resistances from the data collected on an operating fuel cell. For this reason, based on the functional groups, four organic contaminants found in BOP materials, diethylene glycol monoethyl ether (DGMEE), diethylene glycol monoethyl ethermore » acetate (DGMEA), benzyl alcohol (BzOH) and 2,6-diaminotoluene (2,6-DAT) were infused separately to the cathode side of the fuel cell. The cell voltage and high frequency impedance resistance was measured as a function of time. The contaminant feed was then discontinued and voltage recovery was measured. It was determined that compounds with ion exchange properties like 2,6-DAT can cause voltage loss with non-reversible recovery, so this compound was studied in more detail. Finally, the degree of voltage loss increased with an increase in concentration, and/or infusion time, and increased with a decrease in catalyst loadings.« less

  19. Effect of System Contaminants on the Performance of a Proton Exchange Membrane Fuel Cell

    SciTech Connect

    Mehrabadi, Bahareh Alsadat Tavakoli; Dinh, Huyen N.; Bender, Guido; Weidner, John W.

    2016-11-10

    The performance loss and recovery of the fuel cell due to Balance of Plant (BOP) contaminants was identified via a combination of experimental data and a mathematical model. The experiments were designed to study the influence of organic contaminants (e.g. those from BOP materials) on the resistance of the catalyst, ionomer and membrane, and a mathematical model was developed that allowed us to separate these competing resistances from the data collected on an operating fuel cell. For this reason, based on the functional groups, four organic contaminants found in BOP materials, diethylene glycol monoethyl ether (DGMEE), diethylene glycol monoethyl ether acetate (DGMEA), benzyl alcohol (BzOH) and 2,6-diaminotoluene (2,6-DAT) were infused separately to the cathode side of the fuel cell. The cell voltage and high frequency impedance resistance was measured as a function of time. The contaminant feed was then discontinued and voltage recovery was measured. It was determined that compounds with ion exchange properties like 2,6-DAT can cause voltage loss with non-reversible recovery, so this compound was studied in more detail. Finally, the degree of voltage loss increased with an increase in concentration, and/or infusion time, and increased with a decrease in catalyst loadings.

  20. Effect of System Contaminants on the Performance of a Proton Exchange Membrane Fuel Cell

    SciTech Connect

    Mehrabadi, Bahareh Alsadat Tavakoli; Dinh, Huyen N.; Bender, Guido; Weidner, John W.

    2016-01-01

    The performance loss and recovery of the fuel cell due to Balance of Plant (BOP) contaminants was identified via a combination of experimental data and a mathematical model. The experiments were designed to study the influence of organic contaminants (e.g. those from BOP materials) on the resistance of the catalyst, ionomer and membrane, and a mathematical model was developed that allowed us to separate these competing resistances from the data collected on an operating fuel cell. For this reason, based on the functional groups, four organic contaminants found in BOP materials, diethylene glycol monoethyl ether (DGMEE), diethylene glycol monoethyl ether acetate (DGMEA), benzyl alcohol (BzOH) and 2,6-diaminotoluene (2,6-DAT) were infused separately to the cathode side of the fuel cell. The cell voltage and high frequency impedance resistance was measured as a function of time. The contaminant feed was then discontinued and voltage recovery was measured. It was determined that compounds with ion exchange properties like 2,6-DAT can cause voltage loss with non-reversible recovery, so this compound was studied in more detail. The degree of voltage loss increased with an increase in concentration, and/or infusion time, and increased with a decrease in catalyst loadings.

  1. Experimental investigation of irreversibility of a proton exchange membrane fuel cell at different channel geometry

    NASA Astrophysics Data System (ADS)

    Khazaee, I.; Ghazikhani, M.

    2012-12-01

    The geometry of the channels of a fuel cell is very important for performance and efficiency of it. For this reason, a thermodynamic analysis is performed for a PEM fuel cell at different channel geometry that three different fuel cells with rectangular, elliptical and triangular serpentine channels have constructed. The active area of each cell is 25 cm2 that its weight is 1300 g. The material of the gas diffusion layer is carbon clothes, the membrane is Nafion 112 and the catalyst layer is a plane with 0.004 g/cm2 Platinum. Also a test bench designed and constructed for testing the cell and a series of experiments are carried out to investigate the influence of the geometry of the cell on irreversibility under the normal conditions. The results show that the performance of the cell at T_{{{{O}}2 }} = 55 °C, T_{{{{H}}2 }} = 55 °C, T_{{cell}} = 60 °C, oxygen flow rate = 0.5 L/min, hydrogen flow rate = 0.3 L/min and P = 2.905 bar is higher about 12 % and 18 % when the geometry of the channels is rectangular in comparison of elliptical and triangular channels and the irreversibility is lower about 17 % and 33 % when the geometry of the channels is rectangular in comparison of elliptical and triangular channels.

  2. Method using gas chromatography to determine the molar flow balance for proton exchange membrane fuel cells exposed to impurities

    NASA Astrophysics Data System (ADS)

    Bender, G.; Angelo, M.; Bethune, K.; Dorn, S.; Thampan, T.; Rocheleau, R.

    An understanding of the potentially serious performance degradation effects that trace level contaminants can cause in proton exchange membrane fuel cells (PEMFCs) is crucial for the successful deployment of PEMFC for commercial applications. An experimental and analytic methodology is described that employs gas chromatography (GC) to accurately determine the concentration of impurity species in the fuel and oxidant streams of a PEMFC. In this paper we further show that the accurate determination of the contaminant concentrations at the anode and cathode inlets and outlets provides a means to quantify reactions of contaminants within the cell and to identify diffusive mass transport across the membrane. High data accuracy down to sub-ppm contaminant levels is required and was achieved by addressing several challenges pertaining to experimental setup and data analysis which are both discussed in detail. The application of the methodology is demonstrated using carbon monoxide and toluene which were injected into the cell at concentrations between 1 and 10 ppm and 20 and 60 ppm, respectively. Both impurities were observed to react in the fuel cell: carbon monoxide to carbon dioxide, and toluene to methylcyclohexane. For both contaminants closure of the molar flow balances to within 3% was achieved even at the low contaminant concentrations. This allowed the extent of both reactions at the applied operating conditions to be quantified. The presented methodology is shown to be a valuable tool for investigating the effects and reactions of trace contaminants in fuel cells and for providing critical insights into the mechanisms responsible for the associated performance degradation.

  3. Thermal and electrochemical durability of carbonaceous composites used as a bipolar plate of proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Kinumoto, Taro; Nagano, Keita; Tsumura, Tomoki; Toyoda, Masahiro

    Thermal and electrochemical durability of carbonaceous composite plates, which are made from graphite powders and a resin for use as bipolar plates of PEMFC (proton exchange membrane fuel cell), were investigated. The thermal durability was investigated by TG (thermal gravimetry) coupled with DTA (differential thermal analysis) technique under air up to 600 °C. A weight loss was significant over 300 °C, but the hydrophobicity was decreased after heated at 80 °C for 192 h. The electrochemical durability was investigated in 10 μmol dm -3 of hydrochloric acid solution under nitrogen or oxygen atmosphere by means of potential holding test from 0.8 to 1.5 V against RHE (reversible hydrogen electrode) at 80 °C. During the potential holding tests, CO 2 production due to the corrosion was quantified by a GC (gas-chromatography) and the production was detectable above 1.3 V irrespective with atmosphere; on the other hand, it was clarified from the contact angle measurements that the hydrophobicity was changed below 1.3 V. The results of this study showed that the carbonaceous composite plates were electrochemically degraded under PEMFC condition and were seriously degraded in URFC (unitized regenerative fuel cell) condition.

  4. Modeling the performance of hydrogen-oxygen unitized regenerative proton exchange membrane fuel cells for energy storage

    NASA Astrophysics Data System (ADS)

    Guarnieri, Massimo; Alotto, Piergiorgio; Moro, Federico

    2015-11-01

    Thanks to the independent sizing of power and energy, hydrogen-based energy storage is one of the very few technologies capable of providing long operational times in addition to the other advantages offered by electrochemical energy storage, for example scalability, site versatility, and mobile service. The typical design consists of an electrolyzer in charge mode and a separate fuel cell in discharge mode. Instead, a unitized regenerative fuel cell (URFC) is a single device performing both energy conversions, achieving a higher compactness and power-to-weight ratio. This paper presents a performance model of a URFC based on a proton exchange membrane (PEM) electrolyte and working on hydrogen and oxygen, which can provide high energy and power densities (>0.7 W cm-2). It provides voltage, power, and efficiency at varying load conditions as functions of the controlling physical quantities: temperature, pressure, concentration, and humidification. The model constitutes a tool for designing the interface and control sub-system as well as for exploring optimized cell/stack designs and operational conditions. To date, only a few of such analyses have been carried out and more research is needed in order to explore the true potential of URFCs.

  5. Proton exchange membrane fuel cell model for aging predictions: Simulated equivalent active surface area loss and comparisons with durability tests

    NASA Astrophysics Data System (ADS)

    Robin, C.; Gérard, M.; Quinaud, M.; d'Arbigny, J.; Bultel, Y.

    2016-09-01

    The prediction of Proton Exchange Membrane Fuel Cell (PEMFC) lifetime is one of the major challenges to optimize both material properties and dynamic control of the fuel cell system. In this study, by a multiscale modeling approach, a mechanistic catalyst dissolution model is coupled to a dynamic PEMFC cell model to predict the performance loss of the PEMFC. Results are compared to two 2000-h experimental aging tests. More precisely, an original approach is introduced to estimate the loss of an equivalent active surface area during an aging test. Indeed, when the computed Electrochemical Catalyst Surface Area profile is fitted on the experimental measures from Cyclic Voltammetry, the computed performance loss of the PEMFC is underestimated. To be able to predict the performance loss measured by polarization curves during the aging test, an equivalent active surface area is obtained by a model inversion. This methodology enables to successfully find back the experimental cell voltage decay during time. The model parameters are fitted from the polarization curves so that they include the global degradation. Moreover, the model captures the aging heterogeneities along the surface of the cell observed experimentally. Finally, a second 2000-h durability test in dynamic operating conditions validates the approach.

  6. Degradation of graphene coated copper in simulated proton exchange membrane fuel cell environment: Electrochemical impedance spectroscopy study

    NASA Astrophysics Data System (ADS)

    Ren, Y. J.; Anisur, M. R.; Qiu, W.; He, J. J.; Al-Saadi, S.; Singh Raman, R. K.

    2017-09-01

    Metallic materials are most suitable for bipolar plates of proton exchange membrane fuel cell (PEMFC) because they possess the required mechanical strength, durability, gas impermeability, acceptable cost and are suitable for mass production. However, metallic bipolar plates are prone to corrosion or they can passivate under PEMFC environment and interrupt the fuel cell operation. Therefore, it is highly attractive to develop corrosion resistance coating that is also highly conductive. Graphene fits these criteria. Graphene coating is developed on copper by chemical vapor deposition (CVD) with an aim to improving corrosion resistance of copper under PEMFC condition. The Raman Spectroscopy shows the graphene coating to be multilayered. The electrochemical degradation of graphene coated copper is investigated by electrochemical impedance spectroscopy (EIS) in 0.5 M H2SO4 solution at room temperature. After exposure to the electrolyte for up to 720 h, the charge transfer resistance (Rt) of the graphene coated copper is ∼3 times greater than that of the bare copper, indicating graphene coatings could improve the corrosion resistance of copper bipolar plates.

  7. The Priority and Challenge of High-Power Performance of Low-Platinum Proton-Exchange Membrane Fuel Cells.

    PubMed

    Kongkanand, Anusorn; Mathias, Mark F

    2016-04-07

    Substantial progress has been made in reducing proton-exchange membrane fuel cell (PEMFC) cathode platinum loadings from 0.4-0.8 mgPt/cm(2) to about 0.1 mgPt/cm(2). However, at this level of cathode Pt loading, large performance loss is observed at high-current density (>1 A/cm(2)), preventing a reduction in the overall stack cost. This next developmental step is being limited by the presence of a resistance term exhibited at these lower Pt loadings and apparently due to a phenomenon at or near the catalyst surface. This issue can be addressed through the design of catalysts with high and stable Pt dispersion as well as through development and implementation of ionomers designed to interact with Pt in a way that does not constrain oxygen reduction reaction rates. Extrapolating from progress made in past decades, we are optimistic that the concerted efforts of materials and electrode designers can resolve this issue, thus enabling a large step toward fuel cell vehicles that are affordable for the mass market.

  8. Effects of proton-exchange membrane fuel-cell operating conditions on charge transfer resistances measured by electrochemical impedance spectroscopy

    SciTech Connect

    Aaron, Doug S; Yiacoumi, Sotira; Tsouris, Costas

    2008-01-01

    Proton-exchange-membrane fuel cells (PEMFC) are highly dependent on operating conditions, such as humidity and temperature. This study employs electrochemical impedance spectroscopy (EIS) to measure the effects of operating parameters on internal proton and electron transport resistance mechanisms in the PEMFC. Current-density experiments have been performed to measure the power production in a 25 cm{sup 2} Nafion 117 PEMFC at varying operating conditions. These experiments have shown that low humidity and low temperature contribute to decreased power production. EIS is currently employed to provide a better understanding of the mechanisms involved in power production by calculating the specific resistances at various regions in the PEMFC. Experiments are performed at temperatures ranging from 30 to 50 C, feed humidities from 20 to 98%, and air stoichiometric ratios from 1.33 to 2.67. In all experiments, the hydrogen feed stoichiometric ratio was approximately 4.0. EIS is used to identify which transport steps limit the power production of the PEMFC over these ranges of conditions. The experimental data are analyzed via comparison to equivalent circuit models (ECMs), a technique that uses an electrical circuit to represent the electrochemical and transport properties of the PEMFC. These studies will aid in designing fuel cells that are more tolerant to wide-ranging operating conditions. In addition, optimal operating conditions for PEMFC operation can be identified.

  9. Real-Time Remote Monitoring of Temperature and Humidity Within a Proton Exchange Membrane Fuel Cell Using Flexible Sensors

    PubMed Central

    Kuo, Long-Sheng; Huang, Hao-Hsiu; Yang, Cheng-Hao; Chen, Ping-Hei

    2011-01-01

    This study developed portable, non-invasive flexible humidity and temperature microsensors and an in situ wireless sensing system for a proton exchange membrane fuel cell (PEMFC). The system integrated three parts: a flexible capacitive humidity microsensor, a flexible resistive temperature microsensor, and a radio frequency (RF) module for signal transmission. The results show that the capacitive humidity microsensor has a high sensitivity of 0.83 pF%RH−1 and the resistive temperature microsensor also exhibits a high sensitivity of 2.94 × 10−3 °C−1. The established RF module transmits the signals from the two microsensors. The transmission distance can reach 4 m and the response time is less than 0.25 s. The performance measurements demonstrate that the maximum power density of the fuel cell with and without these microsensors are 14.76 mW·cm−2 and 15.90 mW·cm−2, with only 7.17% power loss. PMID:22164099

  10. Modeling two-phase flow in three-dimensional complex flow-fields of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kim, Jinyong; Luo, Gang; Wang, Chao-Yang

    2017-10-01

    3D fine-mesh flow-fields recently developed by Toyota Mirai improved water management and mass transport in proton exchange membrane (PEM) fuel cell stacks, suggesting their potential value for robust and high-power PEM fuel cell stack performance. In such complex flow-fields, Forchheimer's inertial effect is dominant at high current density. In this work, a two-phase flow model of 3D complex flow-fields of PEMFCs is developed by accounting for Forchheimer's inertial effect, for the first time, to elucidate the underlying mechanism of liquid water behavior and mass transport inside 3D complex flow-fields and their adjacent gas diffusion layers (GDL). It is found that Forchheimer's inertial effect enhances liquid water removal from flow-fields and adds additional flow resistance around baffles, which improves interfacial liquid water and mass transport. As a result, substantial improvements in high current density cell performance and operational stability are expected in PEMFCs with 3D complex flow-fields, compared to PEMFCs with conventional flow-fields. Higher current density operation required to further reduce PEMFC stack cost per kW in the future will necessitate optimizing complex flow-field designs using the present model, in order to efficiently remove a large amount of product water and hence minimize the mass transport voltage loss.

  11. Study of acetylene poisoning of Pt cathode on proton exchange membrane fuel cell spatial performance using a segmented cell system

    NASA Astrophysics Data System (ADS)

    Reshetenko, Tatyana V.; St-Pierre, Jean

    2015-08-01

    Acetylene is a welding fuel and precursor for organic synthesis, which requires considering it to be a possible air pollutant. In this work, the spatial performance of a proton exchange membrane fuel cell exposed to 300 ppm C2H2 and different operating currents was studied with a segmented cell system. The injection of C2H2 resulted in a cell performance decrease and redistribution of segments' currents depending on the operating conditions. Performance loss was 20-50 mV at 0.1-0.2 A cm-2 and was accompanied by a rapid redistribution of localized currents. Acetylene exposure at 0.4-1.0 A cm-2 led to a sharp voltage decrease to 0.07-0.13 V and significant changes in current distribution during a transition period, when the cell reached a voltage of 0.55-0.6 V. A recovery of the cell voltage was observed after stopping the C2H2 injection. Spatial electrochemical impedance spectroscopy (EIS) data showed different segments' behavior at low and high currents. It was assumed that acetylene oxidation occurs at high cell voltage, while it reduces at low cell potential. A detailed analysis of the current density distribution, its correlation with EIS data and possible C2H2 oxidation/reduction mechanisms are presented and discussed.

  12. Study of the two-phase dummy load shut-down strategy for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Lin, R.; Cui, X.; Xia, S. X.; Yang, Z.; Chang, Y. T.

    2017-02-01

    This paper presents a new system strategy designed to alleviate the performance decay caused by start-up/shut-down (SU/SD) conditions in proton exchange membrane fuel cells (PEMFCs). The innovative method was tested using a two-phase dummy load composed of a linearly declined main load and a fixed small auxiliary load. The initial value of the main load must be controlled within a proper range, and a closed-ended air exhaust is necessary. According to the analysis of in-situ current density distribution during SD processes, the two-phase dummy load can continuously fit the process of oxygen reduction in the cathode, whereas the conventional dummy load leads to local air starvation. Polarization curves and cyclic voltammetry (CV) were employed to evaluate the performance decay during SU/SD repetition. After tests of 900 cycles, the highest voltage degradation rate of the PEMFC was 3.33 μV cycle-1 (800 mA cm-2), and the electrochemical surface area (ECSA) loss was 0.0046 m2 g-1 cycle-1 with the two-phase dummy load strategy. After comparing results with similar work on a single PEMFC, the authors confirmed the preeminent effectiveness of this strategy. This strategy will also improve fuel cell stack performance due to controllable SD duration and comparatively low performance decay rates.

  13. Coupled modeling of water transport and air-droplet interaction in the electrode of a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Esposito, Angelo; Pianese, Cesare; Guezennec, Yann G.

    In this work, an accurate and computationally fast model for liquid water transport within a proton exchange membrane fuel cell (PEMFC) electrode is developed by lumping the space-dependence of the relevant variables. Capillarity is considered as the main transport mechanism within the gas diffusion layer (GDL). The novelty of the model lies in the coupled simulation of the water transport at the interface between gas diffusion layer and gas flow channel (GFC). This is achieved with a phenomenological description of the process that allows its simulation with relative simplicity. Moreover, a detailed two-dimensional visualization of such interface is achieved via geometric simulation of water droplets formation, growth, coalescence and detachment on the surface of the GDL. The model is useful for optimization analysis oriented to both PEMFC design and balance of plant. Furthermore, the accomplishment of reduced computational time and good accuracy makes the model suitable for control strategy implementation to ensure PEM fuel cells operation within optimal electrode water content.

  14. Real-time remote monitoring of temperature and humidity within a proton exchange membrane fuel cell using flexible sensors.

    PubMed

    Kuo, Long-Sheng; Huang, Hao-Hsiu; Yang, Cheng-Hao; Chen, Ping-Hei

    2011-01-01

    This study developed portable, non-invasive flexible humidity and temperature microsensors and an in situ wireless sensing system for a proton exchange membrane fuel cell (PEMFC). The system integrated three parts: a flexible capacitive humidity microsensor, a flexible resistive temperature microsensor, and a radio frequency (RF) module for signal transmission. The results show that the capacitive humidity microsensor has a high sensitivity of 0.83 pF%RH(-1) and the resistive temperature microsensor also exhibits a high sensitivity of 2.94 × 10(-3) °C(-1). The established RF module transmits the signals from the two microsensors. The transmission distance can reach 4 m and the response time is less than 0.25 s. The performance measurements demonstrate that the maximum power density of the fuel cell with and without these microsensors are 14.76 mW·cm(-2) and 15.90 mW·cm(-2), with only 7.17% power loss.

  15. Scanning transmission X-ray microscopy of nano structured thin film catalysts for proton-exchange-membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lee, Vincent; Berejnov, Viatcheslav; West, Marcia; Kundu, Sumit; Susac, Darija; Stumper, Jürgen; Atanasoski, Radoslav T.; Debe, Mark; Hitchcock, Adam P.

    2014-10-01

    Scanning transmission X-ray microscopy (STXM) has been applied to characterize nano structured thin film (NSTF) catalysts implemented as electrode materials in proton-exchange-membrane (PEM) fuel cells. STXM is used to study all chemical constituents at various stages in the fabrication process, from the perylene red (PR149) starting material, through the formation of the uncoated perylene whiskers, their coated form with Pt-based catalyst, and toward the NSTF anode fully integrated into the catalyst coated membrane (CCM). CCM samples were examined prior to operational testing and after several different accelerated testing protocols: start-up/shut-down (SU/SD), and reversal tests. It was found that, while the perylene support material is present in the pre-test samples, it was completely absent in the post-test samples. We attribute this loss of perylene material to the presence of cracks in the catalyst combined with intensive hydrogenation processes happening at the anode during operation. Despite the loss of the perylene support, the platinum shells forming the NSTF anode catalyst layer performed well during the tests.

  16. Current density and ohmic resistance distribution in the land-channel direction of a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Shrivastava, Udit N.; Tajiri, Kazuya; Chase, Michael

    2015-12-01

    A highly instrumented segmented cell is designed to measure current density and ohmic resistance distribution in the land-channel direction of a proton exchange membrane fuel cell at resolution of 350 μm. A customized catalyst coated membrane with an active area of 9 mm2 is prepared, and a printed-circuit board technique is introduced to ease fabrication of segmented anode and to adapt design to any flow arrangement. Design of segmented cell is validated by electrochemical pumping of hydrogen from anode to cathode. Current density and ohmic resistance distribution are measured in two wet conditions (at 40 °C and 60 °C) and a dry condition at 60 °C. In all cases a strong correlation between current generation and ohmic resistance distribution is observed. Outcomes from these experiments revealed that the water distribution has a strong effect on the local current generation and ohmic resistance. In wet condition ohmic resistance is uniform but current generation found to be non-uniform because of the non-uniform liquid water distribution. In dry condition, on the other hand, non-uniform water generation resulted in both uneven current generation and ohmic resistance.

  17. Dry gas operation of proton exchange membrane fuel cells with parallel channels: Non-porous versus porous plates

    NASA Astrophysics Data System (ADS)

    Litster, Shawn; Santiago, Juan G.

    We present a study of proton exchange membrane (PEM) fuel cells with parallel channel flow fields for the cathode, dry inlet gases, and ambient pressure at the outlets. The study compares the performance of two designs: a standard, non-porous graphite cathode plate design and a porous hydrophilic carbon plate version. The experimental study of the non-porous plate is a control case and highlights the significant challenges of operation with dry gases and non-porous, parallel channel cathodes. These challenges include significant transients in power density and severe performance loss due to flooding and electrolyte dry-out. Our experimental study shows that the porous plate yields significant improvements in performance and robustness of operation. We hypothesize that the porous plate distributes water throughout the cell area by capillary action; including pumping water upstream to normally dry inlet regions. The porous plate reduces membrane resistance and air pressure drop. Further, IR-free polarization curves confirm operation free of flooding. With an air stoichiometric ratio of 1.3, we obtain a maximum power density of 0.40 W cm -2, which is 3.5 times greater than that achieved with the non-porous plate at the same operating condition.

  18. Water management in a single cell proton exchange membrane fuel cells with a serpentine flow field

    NASA Astrophysics Data System (ADS)

    Hassan, Nik Suhaimi Mat; Daud, Wan Ramli Wan; Sopian, Kamaruzzaman; Sahari, Jaafar

    Gas and water management is the key to achieving good performance from a polymer electrolyte membrane fuel cell (PEMFC) stack. Imbalance between production and evaporation rates can result in either flooding of the electrodes or membrane dehydration, both of which severely limit fuel cell performance. In the present study, a mathematical model was developed to evaluate moisture profiles of hydrogen and air flows in the flow field channels of both the anode and the cathode. For model validation, a single fuel cell was designed with an active area of 200 cm 2. Six humidity sensors were installed in the flow fields of both the anode and the cathode at 457 mm, 1266 mm and 2532 mm from the inlets. The experiment was performed using an Arbin Fuel Cell Test Station. The temperature was varied (25 °C, 40 °C, 50 °C and 60 °C), while hydrogen and air velocities were fixed at 3 L min -1 and 6 L min -1, respectively, during the operation of the single cell. The feed relative humidity at the anode was fixed at 1.0, while the feed relative humidity at the cathode was fixed at 0.005 (dry air). All humidity sensor readings were taken at steady state after 2 h of operation. Model predictions were then compared with experimental results by using the least squares algorithm. The moisture content was found to decrease along the flow field at the anode, but to increase at the cathode. The moisture content profile at the anode was shown to depend on the moisture Peclet number, which decreased with temperature. On the other hand, the moisture profile at the cathode was shown to depend on both the Peclet number and the Damkohler number. The trend of the Peclet number in the cathode followed closely that of the anode. The Damkohler number decreased with temperature, indicating increasing moisture mass transfer with temperature. The moisture profile models were successfully validated by the published data of the estimated overall mass transfer coefficient and moisture effective

  19. New theoretical model for convergent nozzle ejector in the proton exchange membrane fuel cell system

    NASA Astrophysics Data System (ADS)

    Zhu, Yinhai; Li, Yanzhong

    A new theoretical model for the convergent nozzle ejector in the anode recirculation line of the polymer electrolyte membrane (PEM) fuel cell system is established in this paper. A velocity function for analyzing the flow characteristics of the PEM ejector is proposed by employing a two-dimensional (2D) concave exponential curve. This treatment of velocity is an improvement compared to the conventional 1D "constant area mixing" or "constant pressure mixing" ejector theories. The computational fluid dynamics (CFD) technique together with the data regression and parameter identification methods are applied in the determination of the velocity function's exponent. Based on the model, the anode recirculation performances of a hybrid PEM system are studied under various stack currents. Results show that the model is capable of evaluating the performance of ejector in both the critical mode and subcritical mode.

  20. Characterization of proton exchange membrane materials for fuel cells by solid state nuclear magnetic resonance

    SciTech Connect

    Kong, Zueqian

    2010-01-01

    Solid-state nuclear magnetic resonance (NMR) has been used to explore the nanometer-scale structure of Nafion, the widely used fuel cell membrane, and its composites. We have shown that solid-state NMR can characterize chemical structure and composition, domain size and morphology, internuclear distances, molecular dynamics, etc. The newly-developed water channel model of Nafion has been confirmed, and important characteristic length-scales established. Nafion-based organic and inorganic composites with special properties have also been characterized and their structures elucidated. The morphology of Nafion varies with hydration level, and is reflected in the changes in surface-to-volume (S/V) ratio of the polymer obtained by small-angle X-ray scattering (SAXS). The S/V ratios of different Nafion models have been evaluated numerically. It has been found that only the water channel model gives the measured S/V ratios in the normal hydration range of a working fuel cell, while dispersed water molecules and polymer ribbons account for the structures at low and high hydration levels, respectively.

  1. Tolerance of non-platinum group metals cathodes proton exchange membrane fuel cells to air contaminants

    NASA Astrophysics Data System (ADS)

    Reshetenko, Tatyana; Serov, Alexey; Artyushkova, Kateryna; Matanovic, Ivana; Sarah Stariha; Atanassov, Plamen

    2016-08-01

    The effects of major airborne contaminants (SO2, NO2 and CO) on the spatial performance of Fe/N/C cathode membrane electrode assemblies were studied using a segmented cell system. The injection of 2-10 ppm SO2 in air stream did not cause any performance decrease and redistribution of local currents due to the lack of stably adsorbed SO2 molecules on Fe-Nx sites, as confirmed by density functional theory (DFT) calculations. The introduction of 5-20 ppm of CO into the air stream also did not affect fuel cell performance. The exposure of Fe/N/C cathodes to 2 and 10 ppm NO2 resulted in performance losses of 30 and 70-75 mV, respectively. DFT results showed that the adsorption energies of NO2 and NO were greater than that of O2, which accounted for the observed voltage decrease and slight current redistribution. The cell performance partially recovered when the NO2 injection was stopped. The long-term operation of the fuel cells resulted in cell performance degradation. XPS analyses of Fe/N/C electrodes revealed that the performance decrease was due to catalyst degradation and ionomer oxidation. The latter was accelerated in the presence of air contaminants. The details of the spatial performance and electrochemical impedance spectroscopy results are presented and discussed.

  2. Thermal-Conductivity Characterization of Gas Diffusion Layer in Proton Exchange Membrane Fuel Cells and Electrolyzers Under Mechanical Loading

    NASA Astrophysics Data System (ADS)

    Hamour, M.; Garnier, J. P.; Grandidier, J. C.; Ouibrahim, A.; Martemianov, S.

    2011-05-01

    Accurate information on the temperature field and associated heat transfer rates is particularly important for proton exchange membrane fuel cells (PEMFC) and PEM electrolyzers. An important parameter in fuel cell and electrolyzer performance analysis is the effective thermal conductivity of the gas diffusion layer (GDL) which is a solid porous medium. Usually, this parameter is introduced in modeling and performance analysis without taking into account the dependence of the GDL thermal conductivity λ (in W · m-1 · K-1) on mechanical compression. Nevertheless, mechanical stresses arising in an operating system can change significantly the thermal conductivity and heat exchange. Metrology allowing the characterization of the GDL thermal conductivity as a function of the applied mechanical compression has been developed in this study using the transient hot-wire technique (THW). This method is the best for obtaining standard reference data in fluids, but it is rarely used for thermal-conductivity measurements in solids. The experiments provided with Quintech carbon cloth indicate a strong dependence (up to 300%) of the thermal conductivity λ on the applied mechanical load. The experiments have been provided in the pressure range 0 < p < 8 MPa which corresponds to stresses arising in fuel cells. All obtained experimental results have been fitted by the equation λ = 0.9log(12 p + 17)(1 - 0.4e-50 p ) with 9% uncertainty. The obtained experimental dependence can be used for correct modeling of coupled thermo/electro-mechanical phenomena in fuel cells and electrolyzers. Special attention has been devoted to justification of the main hypotheses of the THW method and for estimation of the possible influence of the contact resistances. For this purpose, measurements with a different number of carbon cloth layers have been provided. The conducted experiments indicate the independence of the measured thermal conductivity on the number of GDL layers and, thus, justify the

  3. A Methanol Steam Reforming Micro Reactor for Proton Exchange Membrane Micro Fuel Cell System

    SciTech Connect

    Park, H G; Piggott, W T; Chung, J; Morse, J D; Havstad, M; Grigoropoulos, C P; Greif, R; Benett, W; Sopchak, D; Upadhye, R

    2003-07-28

    The heat, mass and momentum transfer from a fuel reforming packed bed to a surrounding silicon wafer has been simulated. Modeling showed quantitatively reasonable agreement with experimental data for fuel conversion efficiency, hydrogen production rate, outlet methanol mole fraction and outlet steam mole fraction. The variation in fuel conversion efficiency with the micro reformer thermal isolation can be used to optimize fuel-processing conditions for micro PEM fuel cells.

  4. Mesostructured platinum-free anode and carbon-free cathode catalysts for durable proton exchange membrane fuel cells.

    PubMed

    Cui, Xiangzhi; Shi, Jianlin; Wang, Yongxia; Chen, Yu; Zhang, Lingxia; Hua, Zile

    2014-01-01

    As one of the most important clean energy sources, proton exchange membrane fuel cells (PEMFCs) have been a topic of extensive research focus for decades. Unfortunately, several critical technique obstacles, such as the high cost of platinum electrode catalysts, performance degradation due to the CO poisoning of the platinum anode, and carbon corrosion by oxygen in the cathode, have greatly impeded its commercial development. A prototype of a single PEMFC catalyzed by a mesostructured platinum-free WO3/C anode and a mesostructured carbon-free Pt/WC cathode catalysts is reported herein. The prototype cell exhibited 93% power output of a standard PEMFC using commercial Pt/C catalysts at 50 and 70 °C, and more importantly, CO poisoning-free and carbon corrosion-resistant characters of the anode and cathode, respectively. Consequently, the prototype cell demonstrated considerably enhanced cell operation durability. The mesostructured electrode catalysts are therefore highly promising in the future development and application of PEMFCs. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Isothermal Ice Crystallization Kinetics in the Gas-Diffusion Layer of a Proton-Exchange-Membrane Fuel Cell

    SciTech Connect

    Dursch, Thomas J.; Ciontea, Monica A.; Radke, Clayton J.; Weber, Adam Z.

    2011-12-01

    Nucleation and growth of ice in the fibrous gas-diffusion layer (GDL) of a proton-exchange membrane fuel cell (PEMFC) are studied using isothermal differential scanning calorimetry (DSC). Isothermal crystallization rates and pseudo-steady-state nucleation rates are obtained as a function of subcooling from heat-flow and induction-time measurements. Kinetics of ice nucleation and growth are studied at two polytetrafluoroethylene (PTFE) loadings (0 and 10 wt %) in a commercial GDL for temperatures between 240 and 273 K. A nonlinear ice-crystallization rate expression is developed using Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory, in which the heat-transfer-limited growth rate is determined from the moving-boundary Stefan problem. Induction times follow a Poisson distribution and increase upon addition of PTFE, indicating that nucleation occurs more slowly on a hydrophobic fiber than on a hydrophilic fiber. The determined nucleation rates and induction times follow expected trends from classical nucleation theory. Finally, a validated rate expression is now available for predicting ice-crystallization kinetics in GDLs.

  6. New insights into non-precious metal catalyst layer designs for proton exchange membrane fuel cells: Improving performance and stability

    NASA Astrophysics Data System (ADS)

    Banham, Dustin; Kishimoto, Takeaki; Sato, Tetsutaro; Kobayashi, Yoshikazu; Narizuka, Kumi; Ozaki, Jun-ichi; Zhou, Yingjie; Marquez, Emil; Bai, Kyoung; Ye, Siyu

    2017-03-01

    The activity of non-precious metal catalysts (NPMCs) has now reached a stage at which they can be considered as possible alternatives to Pt for some proton exchange membrane fuel cell (PEMFC) applications. However, despite significant efforts over the past 50 years on catalyst development, only limited studies have been performed on NPMC-based cathode catalyst layer (CCL) designs. In this work, an extensive ionomer study is performed to investigate the impact of ionomer equivalent weight on performance, which has uncovered two crucial findings. Firstly, it is demonstrated that beyond a critical CCL conductance, no further improvement in performance is observed. The procedure used to determine this critical conductance can be used by other researchers in this field to aid in their design of high performing NPMC-based CCLs. Secondly, it is shown that the stability of NPMC-based CCLs can be improved through the use of low equivalent weight ionomers. This represents a completely unexplored pathway for further stability improvements, and also provides new insights into the possible degradation mechanisms occurring in NPMC-based CCLs. These findings have broad implications on all future NPMC-based CCL designs.

  7. Experimental study on the optimal purge duration of a proton exchange membrane fuel cell with a dead-ended anode

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Fen; Chen, Yong-Song

    2017-02-01

    When a proton exchange membrane fuel cell (PEMFC) is operated with a dead-ended anode, impurities gradually accumulate within the anode, resulting in a performance drop. An anode purge is thereby ultimately required to remove impurities within the anode. A purge strategy comprises purge interval (valve closed) and purge duration (valve is open). A short purge interval causes frequent and unnecessary activation of the valve, whereas a long purge interval leads to excessive impurity accumulation. A short purge duration causes an incomplete performance recovery, whereas a long purge duration results in low hydrogen utilization. In this study, a series of experimental trials was conducted to simultaneously measure the hydrogen supply rate and power generation of a PEMFC at a frequency of 50 Hz for various operating current density levels and purge durations. The effect of purge duration on the cell's energy efficiency was subsequently analyzed and discussed. The results showed that the optimal purge duration for the PEMFC was approximately 0.2 s. Based on the results of this study, a methodical process for determining optimal purge durations was ultimately proposed for widespread application. Purging approximately one-fourth of anode gas can obtain optimal energy efficiency for a PEMFC with a dead-ended anode.

  8. Hybrid approach combining multiple characterization techniques and simulations for microstructural analysis of proton exchange membrane fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Cetinbas, Firat C.; Ahluwalia, Rajesh K.; Kariuki, Nancy; De Andrade, Vincent; Fongalland, Dash; Smith, Linda; Sharman, Jonathan; Ferreira, Paulo; Rasouli, Somaye; Myers, Deborah J.

    2017-03-01

    The cost and performance of proton exchange membrane fuel cells strongly depend on the cathode electrode due to usage of expensive platinum (Pt) group metal catalyst and sluggish reaction kinetics. Development of low Pt content high performance cathodes requires comprehensive understanding of the electrode microstructure. In this study, a new approach is presented to characterize the detailed cathode electrode microstructure from nm to μm length scales by combining information from different experimental techniques. In this context, nano-scale X-ray computed tomography (nano-CT) is performed to extract the secondary pore space of the electrode. Transmission electron microscopy (TEM) is employed to determine primary C particle and Pt particle size distributions. X-ray scattering, with its ability to provide size distributions of orders of magnitude more particles than TEM, is used to confirm the TEM-determined size distributions. The number of primary pores that cannot be resolved by nano-CT is approximated using mercury intrusion porosimetry. An algorithm is developed to incorporate all these experimental data in one geometric representation. Upon validation of pore size distribution against gas adsorption and mercury intrusion porosimetry data, reconstructed ionomer size distribution is reported. In addition, transport related characteristics and effective properties are computed by performing simulations on the hybrid microstructure.

  9. Hierarchical nanostructured hollow spherical carbon with mesoporous shell as a unique cathode catalyst support in proton exchange membrane fuel cell.

    PubMed

    Fang, Baizeng; Kim, Jung Ho; Kim, Minsik; Kim, Minwoo; Yu, Jong-Sung

    2009-03-07

    Hierarchical nanostructured spherical carbon with hollow macroporous core in combination with mesoporous shell has been explored to support Pt cathode catalyst with high metal loading in proton exchange membrane fuel cell (PEMFC). The hollow core-mesoporous shell carbon (HCMSC) has unique structural characteristics such as large specific surface area and mesoporous volume, ensuring uniform dispersion of the supported high loading (60 wt%) Pt nanoparticles with small particle size, and well-developed three-dimensionally interconnected hierarchical porosity network, facilitating fast mass transport. The HCMSC-supported Pt(60 wt%) cathode catalyst has demonstrated markedly enhanced catalytic activity toward oxygen reduction and greatly improved PEMFC polarization performance compared with carbon black Vulcan XC-72 (VC)-supported ones. Furthermore, the HCMSC-supported Pt(40 wt%) or Pt(60 wt%) outperforms the HCMSC-supported Pt(20 wt%) even at a low catalyst loading of 0.2 mg Pt cm(-2) in the cathode, which is completely different from the VC-supported Pt catalysts. The capability of supporting high loading Pt is supposed to accelerate the commercialization of PEMFC due to the anticipated significant reduction in the amount of catalyst support required, diffusion layer thickness and fabricating cost of the supported Pt catalyst electrode.

  10. Design and optimization of anode flow field of a large proton exchange membrane fuel cell for high hydrogen utilization

    NASA Astrophysics Data System (ADS)

    Yesilyurt, Serhat; Rizwandi, Omid

    2016-11-01

    We developed a CFD model of the anode flow field of a large proton exchange membrane fuel cell that operates under the ultra-low stoichiometric (ULS) flow conditions which intend to improve the disadvantages of the dead-ended operation such as severe voltage transient and carbon corrosion. Very small exit velocity must be high enough to remove accumulated nitrogen, and must be low enough to retain hydrogen in the active area. Stokes equations are used to model the flow distribution in the flow field, Maxwell-Stefan equations are used to model the transport of the species, and a voltage model is developed to model the reactions kinetics. Uniformity of the distribution of hydrogen concentration is quantified as the normalized area of the region in which the hydrogen mole fraction remains above a certain level, such as 0.9. Geometry of the anode flow field is modified to obtain optimal configuration; the number of baffles at the inlet, width of the gaps between baffles, width of the side gaps, and length of the central baffle are used as design variables. In the final design, the hydrogen-depleted region is less than 0.2% and the hydrogen utilization is above 99%. This work was supported by The Scientific and Technolo-gical Research Council of Turkey, TUBITAK-213M023.

  11. Application of a self-supporting microporous layer to gas diffusion layers of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi; Heo, Yun; Ishida, Masayoshi; Nakano, Akihiro; Someya, Satoshi; Munakata, Tetsuo

    2017-02-01

    The intrinsic effect of properties of a self-supporting microporous layer (MPL) on the performance of proton exchange membrane fuel cells (PEMFCs) is identified. First, a self-supporting MPL is fabricated and applied to a gas diffusion layer (GDL) of a PEMFC, when the GDL is either an integrated sample composed of a gas diffusion backing (GDB, i.e., carbon paper) combined with MPL or a sample with only MPL. Cell performance tests reveal that, the same as the MPL fabricated by the coating method, the self-supporting MPL on the GDB improves the cell performance at high current density. Furthermore, the GDL composed only of the MPL (i.e., GDB-free GDL) shows better performance than does the integrated GDB/MPL GDL. These results along with literature data strongly suggest that the low thermal conductivity of MPL induces a high temperature throughout the GDL, and thus vapor diffusion is dominant in the transport of product water through the MPL.

  12. Influence of the cathode architecture in the frequency response of self-breathing proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ferreira-Aparicio, P.; Chaparro, A. M.

    2014-12-01

    Self-breathing proton exchange membrane fuel cells are apparently simple devices, but efficient water management is critical for their performance. The cathode configuration should guarantee balanced rates between O2 accessibility from the circumventing air and H2O removal, and a good electric contact between catalyst layers and current collectors at the same time. By applying progressive modifications to the initial concept of a conventional PEMFC, the effect of the cathode architecture on cell performance has been analyzed. Frequency response analyses of the cell during steady-state potentiostatic stepping have yielded relevant information regarding limitations originated by the cathode impedance under high current load conditions. The primitive cell design has been optimized for self-breathing operation by means of this diagnostic tool. The thickness of the perforated plate in the cathode has been found to be one of the main factors contributing to limit oxygen accessibility when a high current load is demanded. Adequate cathode architecture is critical for reducing mass transport limitations in the catalytic layer and enhancing performance under self-breathing conditions.

  13. Dynamic analysis and linear control strategies for proton exchange membrane fuel cell using a distributed parameter model

    NASA Astrophysics Data System (ADS)

    Methekar, R. N.; Prasad, V.; Gudi, R. D.

    To satisfy high power density demand in proton exchange membrane fuel cells (PEMFCs), a robust control strategy is essential. A linear ratio control strategy is examined in this work. The manipulated variables are selected using steady-state relative gain array (RGA) analysis to be the inlet molar flow rates of hydrogen and coolant, and the controlled variables are average power density and average solid temperature, respectively. By selecting proper manipulated variables, the PEMFC does not exhibit sign change in gain and hence can be controlled by using a linear controller. Transfer function models obtained from step tests on the distributed parameter PEMFC model are used to design controllers for the multiple input-multiple output (MIMO) system. In addition, a ratio control strategy is proposed and evaluated, where the inlet molar flow rate of oxygen is used as a dependent manipulated variable and changed in a constant ratio with respect to the inlet molar flow rate of hydrogen. Simulation results show that the ratio control strategy provides a faster response than a MIMO control strategy. This ratio control strategy is able to circumvent the problem of oxygen starvation, and the increase in average solid temperature is small as compared to the MIMO control strategy.

  14. Isothermal ice crystallization kinetics in the gas-diffusion layer of a proton-exchange-membrane fuel cell.

    PubMed

    Dursch, T J; Ciontea, M A; Radke, C J; Weber, A Z

    2012-01-17

    Nucleation and growth of ice in the fibrous gas-diffusion layer (GDL) of a proton-exchange membrane fuel cell (PEMFC) are investigated using isothermal differential scanning calorimetry (DSC). Isothermal crystallization rates and pseudo-steady-state nucleation rates are obtained as a function of subcooling from heat-flow and induction-time measurements. Kinetics of ice nucleation and growth are studied at two polytetrafluoroethylene (PTFE) loadings (0 and 10 wt %) in a commercial GDL for temperatures between 240 and 273 K. A nonlinear ice-crystallization rate expression is developed using Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory, in which the heat-transfer-limited growth rate is determined from the moving-boundary Stefan problem. Induction times follow a Poisson distribution and increase upon addition of PTFE, indicating that nucleation occurs more slowly on a hydrophobic fiber than on a hydrophilic fiber. The determined nucleation rates and induction times follow expected trends from classical nucleation theory. A validated rate expression is now available for predicting ice-crystallization kinetics in GDLs.

  15. Design and synthesis of degradation-resistant core-shell catalysts for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Koh, Joon-Ho; Abbaraju, Ravikanth; Parthasarathy, Preethy; Virkar, Anil V.

    2014-09-01

    Core@shell catalysts supported on carbon with Ag core and Pt shell were synthesized by a chemical process. EDX spectra confirmed the formation of Ag@Pt core-shell catalysts. High resolution transmission electron microscopy (HRTEM) revealed that the Pt-shell was epitaxially matched to the Ag core. Electrochemical tests on proton exchange membrane (PEM) fuel cells made with Ag@Pt core-shell catalysts as cathode exhibited comparable performance to cells made using commercial Pt-Co-based catalysts as cathodes. Theoretical work suggested that Ag@Pt catalysts should be more stable in the PEMFC applications compared to monolithic Pt catalysts because Pt shell in Ag@Pt catalysts exhibits lower chemical potential of Pt than in monolithic Pt catalysts, thus reducing tendency for dissolution and Ostwald ripening. Lower chemical potential of Pt in the shell is attributed to larger lattice parameter of Ag compared to Pt, which puts the Pt shell in biaxial tension or reduced biaxial compression as compared to monolithic Pt catalysts. Preliminary out-of-cell tests show Ag@Pt catalysts to be stable in an environment containing ionic platinum.

  16. Numerical study of a novel micro-diaphragm flow channel with piezoelectric device for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ma, H. K.; Huang, S. H.; Chen, B. R.; Cheng, L. W.

    Previous studies have shown that the amplitude of the vibration of a piezoelectric (PZT) device produces an oscillating flow that changes the chamber volume along with a curvature variation of the diaphragm. In this study, an actuating micro-diaphragm with piezoelectric effects is utilized as an air-flow channel in proton exchange membrane fuel cell (PEMFC) systems, called PZT-PEMFC. This newly designed gas pump, with a piezoelectric actuation structure, can feed air into the system of an air-breathing PEMFC. When the actuator moves outward to increase the cathode channel volume, the air is sucked into the chamber; moving inward decreases the channel's volume and thereby compresses air into the catalyst layer and enhancing the chemical reaction. The air-standard PZT-PEMFC cycle is proposed to describe an air-breathing PZT-PEMFC. A novel design for PZT-PEMFCs has been proposed and a three-dimensional, transitional model has been successfully built to account for its major phenomena and performance. Moreover, at high frequencies, PZT actuation leads to a more stable current output, more drained water, higher sucked air, higher hydrogen consumption, and also overcomes concentration losses.

  17. On the estimation of high frequency parameters of Proton Exchange Membrane Fuel Cells via Electrochemical Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mainka, J.; Maranzana, G.; Dillet, J.; Didierjean, S.; Lottin, O.

    2014-05-01

    This paper is a discussion on the estimation of impedance parameters of H2/air fed Proton Exchange Membrane Fuel Cells (PEMFC). The impedance model corresponds to the Randles electrical equivalent circuit accounting for charge separation and transport processes in the cathode catalyst layer, as well as for oxygen diffusion through the backing layer. A sensitivity analysis confirms that the cathode parameters are not correlated and that the consideration of the anode has no significant impact on the estimation of their values. In addition, it is shown that the diffusion parameters have a significant impact in the low frequency domain only, at least with this model. The parameters characterizing charge separation and transport processes at the cathode can thus be estimated with the high frequency impedance data, independently of the oxygen transport model. Consequently, even in the absence of a fully validated oxygen transport impedance, EIS can be used as an alternative method (to classical steady-state methods) for the estimation of the parameters characterizing the cathode reaction: the Tafel slope b, the charge transfer coefficient α and possibly, the exchange current density j0. This reduces significantly the measuring time while enhancing the accuracy by comparison with steady-state methods.

  18. Air supply using an ionic wind generator in a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Kwon, Kilsung; Li, Longnan; Park, Byung Ho; Lee, Seung Jun; Kim, Daejoong

    2015-06-01

    A new air supply is demonstrated for a portable polymer electrolyte membrane fuel cell (PEMFC). The air supply is an ionic wind generator (IWG) with a needle-to-cylinder configuration. The IWG supplies air to the portable PEMFC owing to momentum transfer to the air by charged molecules generated by the corona discharge from a high applied potential. There is no difference in the performance of the PEMFC when compressed air and the IWG are used as the air supply. For the varying interelectrode distance, IWG performance is varied and measured in terms of the flow rate and current. At the interelectrode distance of 9.0 mm, the air flow rate is a suitable for the portable PEMFC with low power consumption. When the IWG is used to supply air to the portable PEMFC, it is found that the flow rate per unit power consumed decreases with the applied voltage, the gross power generation monotonously increases with the applied voltage, and the highest net power (268 mW) is obtained at the applied voltage of 8.5 kV. The parasitic power ratio reaches a minimum value of ∼0.06 with the applied IWG voltage of 5.5 kV.

  19. Carbon corrosion of proton exchange membrane fuel cell catalyst layers studied by scanning transmission X-ray microscopy

    NASA Astrophysics Data System (ADS)

    Hitchcock, Adam P.; Berejnov, Viatcheslav; Lee, Vincent; West, Marcia; Colbow, Vesna; Dutta, Monica; Wessel, Silvia

    2014-11-01

    Scanning Transmission X-ray Microscopy (STXM) at the C 1s, F 1s and S 2p edges has been used to investigate degradation of proton exchange membrane fuel cell (PEM-FC) membrane electrode assemblies (MEA) subjected to accelerated testing protocols. Quantitative chemical maps of the catalyst, carbon support and ionomer in the cathode layer are reported for beginning-of-test (BOT), and end-of-test (EOT) samples for two types of carbon support, low surface area carbon (LSAC) and medium surface area carbon (MSAC), that were exposed to accelerated stress testing with upper potentials (UPL) of 1.0, 1.2, and 1.3 V. The results are compared in order to characterize catalyst layer degradation in terms of the amounts and spatial distributions of these species. Pt agglomeration, Pt migration and corrosion of the carbon support are all visualized, and contribute to differing degrees in these samples. It is found that there is formation of a distinct Pt-in-membrane (PTIM) band for all EOT samples. The cathode thickness shrinks due to loss of the carbon support for all MSAC samples that were exposed to the different upper potentials, but only for the most aggressive testing protocol for the LSAC support. The amount of ionomer per unit volume significantly increases indicating it is being concentrated in the cathode as the carbon corrosion takes place. S 2p spectra and mapping of the cathode catalyst layer indicates there are still sulfonate groups present, even in the most damaged material.

  20. Polypyrrole layered SPEES/TPA proton exchange membrane for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Neelakandan, S.; Kanagaraj, P.; Sabarathinam, R. M.; Nagendran, A.

    2015-12-01

    Hybrid membranes based on sulfonated poly(1,4-phenylene ether ether sulfone) (SPEES)/tungstophosphoric acid (TPA) were prepared. SPEES/TPA membrane surfaces were modified with polypyrrole (Ppy) by in situ polymerization method to reduce the TPA leaching. The morphology and electrochemical property of the surface coated membranes were studied by SEM, AFM, water uptake, ion exchange capacity, proton conductivity, methanol permeability and tensile strength. The water uptake and the swelling ratio of the surface coated membranes decreased with increasing the Ppy layer. The surface roughness of the hybrid membrane was decreased with an increase in Ppy layer on the membrane surface. The methanol permeability of SPEES/TPA-Ppy4 hybrid membrane was significantly suppressed and found to be 2.1 × 10-7 cm2 s-1, which is 1.9 times lower than pristine SPEES membrane. The SPEES/TPA-Ppy4 membrane exhibits highest relative selectivity (2.86 × 104 S cm-3 s) than the other membrane with low TPA leaching. The tensile strength of hybrid membranes was improved with the introduction of Ppy layer. Combining their lower swelling ratio, high thermal stability and selectivity, SPEES/TPA-Ppy4 membranes could be a promising material as PEM for DMFC applications.

  1. Three order state space modeling of proton exchange membrane fuel cell with energy function definition

    NASA Astrophysics Data System (ADS)

    Becherif, M.; Hissel, D.; Gaagat, S.; Wack, M.

    The fuel cell is a complex system which is the centre of a lot of multidisciplinary research activities since it involves intricate application of various fields of study. The operation of a fuel cell depends on a wide range of parameters. The effect of one cannot be studied in isolation without disturbing the system which makes it very difficult to comprehend, analyze and predict various phenomena occurring in the fuel cell. In the current work, we present an equivalent electrical circuit of the pneumatics and fluidics in a fuel cell stack. The proposed model is based on the physical phenomena occurring inside fuel cell stack where we define the fluidic-electrical and pneumatic-electrical analogy. The effect of variation in temperature and relative humidity on the cell are considered in this model. The proposed model, according to the considered hypothesis, is a simple three order state space model which is suitable for the control purpose where a desired control structure can be formulated for high-end applications of the fuel cell as a subpart of a larger system, for instance, in hybrid propulsion of vehicles coupled with batteries and supercapacitors. Another key point of our work is the definition of the natural fuel cell stack energy function. The circuit analysis equations are presented and the simulated model is validated using the experimental data obtained using the fuel cell test bench available in Fuel Cell Laboratory, France.

  2. Proton Exchange Membrane (PEM) Fuel Cell Status and Remaining Challenges for Manned Space-Flight Applications

    NASA Technical Reports Server (NTRS)

    Reaves, Will F.; Hoberecht, Mark A.

    2003-01-01

    The Fuel Cell has been used for manned space flight since the Gemini program. Its power output and water production capability over long durations for the mass and volume are critical for manned space-flight requirements. The alkaline fuel cell used on the Shuttle, while very reliable and capable for it s application, has operational sensitivities, limited life, and an expensive recycle cost. The PEM fuel cell offers many potential improvements in those areas. NASA Glenn Research Center is currently leading a PEM fuel cell development and test program intended to move the technology closer to the point required for manned space-flight consideration. This paper will address the advantages of PEM fuel cell technology and its potential for future space flight as compared to existing alkaline fuel cells. It will also cover the technical hurdles that must be overcome. In addition, a description of the NASA PEM fuel cell development program will be presented, and the current status of this effort discussed. The effort is a combination of stack and ancillary component hardware development, culminating in breadboard and engineering model unit assembly and test. Finally, a detailed roadmap for proceeding fiom engineering model hardware to qualification and flight hardware will be proposed. Innovative test engineering and potential payload manifesting may be required to actually validate/certify a PEM fuel cell for manned space flight.

  3. Development of a Space-Rated Proton Exchange Membrane Fuel Cell

    NASA Technical Reports Server (NTRS)

    Hoffman, William C., III; Vasquez, Arturo; Lazaroff, Scott M.; Downey, Michael G.

    1999-01-01

    Power systems for human spacecraft have historically included fuel cells due to the superior energy density they offer over battery systems depending on mission length and power consumption. As space exploration focuses on the evolution of reusable spacecraft and also considers planetary exploration power system requirements, fuel cells continue to be a factor in the potential system solutions.

  4. Real Time Monitoring of Temperature of a Micro Proton Exchange Membrane Fuel Cell

    PubMed Central

    Lee, Chi-Yuan; Lee, Shuo-Jen; Hu, Yuh-Chung; Shih, Wen-Pin; Fan, Wei-Yuan; Chuang, Chih-Wei

    2009-01-01

    Silicon micro-hole arrays (Si-MHA) were fabricated as a gas diffusion layer (GDL) in a micro fuel cell using the micro-electro-mechanical-systems (MEMS) fabrication technique. The resistance temperature detector (RTD) sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10−3/°C, respectively. The best experimental performance was 9.37 mW/cm2 at an H2/O2 dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C. PMID:22573963

  5. Direct-hydrogen-fueled proton-exchange-membrane fuel cell system for transportation applications: Conceptual vehicle design report pure fuel cell powertrain vehicle

    SciTech Connect

    Oei, D.; Kinnelly, A.; Sims, R.; Sulek, M.; Wernette, D.

    1997-02-01

    In partial fulfillment of the Department of Energy (DOE) Contract No. DE-AC02-94CE50389, {open_quotes}Direct-Hydrogen-Fueled Proton-Exchange-Membrane (PEM) Fuel Cell for Transportation Applications{close_quotes}, this preliminary report addresses the conceptual design and packaging of a fuel cell-only powered vehicle. Three classes of vehicles are considered in this design and packaging exercise, the Aspire representing the small vehicle class, the Taurus or Aluminum Intensive Vehicle (AIV) Sable representing the mid-size vehicle and the E-150 Econoline representing the van-size class. A fuel cell system spreadsheet model and Ford`s Corporate Vehicle Simulation Program (CVSP) were utilized to determine the size and the weight of the fuel cell required to power a particular size vehicle. The fuel cell power system must meet the required performance criteria for each vehicle. In this vehicle design and packaging exercise, the following assumptions were made: fuel cell power system density of 0.33 kW/kg and 0.33 kg/liter, platinum catalyst loading less than or equal to 0.25 mg/cm{sup 2} total and hydrogen tanks containing gaseous hydrogen under 340 atm (5000 psia) pressure. The fuel cell power system includes gas conditioning, thermal management, humidity control, and blowers or compressors, where appropriate. This conceptual design of a fuel cell-only powered vehicle will help in the determination of the propulsion system requirements for a vehicle powered by a PEMFC engine in lieu of the internal combustion (IC) engine. Only basic performance level requirements are considered for the three classes of vehicles in this report. Each vehicle will contain one or more hydrogen storage tanks and hydrogen fuel for 560 km (350 mi) driving range. Under these circumstances, the packaging of a fuel cell-only powered vehicle is increasingly difficult as the vehicle size diminishes.

  6. Insight into proton transfer in phosphotungstic acid functionalized mesoporous silica-based proton exchange membrane fuel cells.

    PubMed

    Zhou, Yuhua; Yang, Jing; Su, Haibin; Zeng, Jie; Jiang, San Ping; Goddard, William A

    2014-04-02

    We have developed for fuel cells a novel proton exchange membrane (PEM) using inorganic phosphotungstic acid (HPW) as proton carrier and mesoporous silica as matrix (HPW-meso-silica) . The proton conductivity measured by electrochemical impedance spectroscopy is 0.11 S cm(-1) at 90 °C and 100% relative humidity (RH) with a low activation energy of ∼14 kJ mol(-1). In order to determine the energetics associated with proton migration within the HPW-meso-silica PEM and to determine the mechanism of proton hopping, we report density functional theory (DFT) calculations using the generalized gradient approximation (GGA). These DFT calculations revealed that the proton transfer process involves both intramolecular and intermolecular proton transfer pathways. When the adjacent HPWs are close (less than 17.0 Å apart), the calculated activation energy for intramolecular proton transfer within a HPW molecule is higher (29.1-18.8 kJ/mol) than the barrier for intermolecular proton transfer along the hydrogen bond. We find that the overall barrier for proton movement within the HPW-meso-silica membranes is determined by the intramolecular proton transfer pathway, which explains why the proton conductivity remains unchanged when the weight percentage of HPW on meso-silica is above 67 wt %. In contrast, the activation energy of proton transfer on a clean SiO2 (111) surface is computed to be as high as ∼40 kJ mol(-1), confirming the very low proton conductivity on clean silica surfaces observed experimentally.

  7. Effect of relative humidity cycles accompanied by intermittent start/stop switches on performance degradation of membrane electrode assembly components in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Qiu, Yanling; Zhong, Hexiang; Wang, Meiri; Zhang, Huamin

    2015-06-01

    The performance degradation of membrane electrode assembly (MEA) components in proton exchange membrane fuel cell (PEMFC) is studied by designing relative humidity (RH) cycles accompanied by intermittent start/stop switches. Cathode catalyst activity, permeability and resistance of proton exchange membrane (PEM) as well as cell performance are monitored during the test procedure. The interfaces of MEA, the catalyst particle distribution near the cathode inlet are characterized by SEM and TEM, respectively. The results demonstrate both the overall H2 permeability and crossover current of PEM are doubled compared with its initial properties. Signs of PEM degradation, including periodical thinning, cracks and pinholes formation, are observed after 300 RH cycles and 40 times of start/stop switches. The average Pt particle size increases by more than 75%, and the cathode electrochemical surface area decreases by 48% after the test procedure. Meanwhile, the cathode catalyst layer becomes looser due to the dissolution of some smaller Pt particles and catalyst agglomeration in the RH cycles and the high potential during the intermittent start/stop switches. The membrane resistance demonstrates downshift variation during the RH cycles. PEMFC performance, however, decays due to the chemical and electrochemical attack as well as the mechanical stresses.

  8. Experimental research on water management in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Yu, Li-jun; Chen, Wen-can; Qin, Ming-jun; Ren, Geng-po

    A simulated cathode flow channel experiment system was set up based on the gas flow rate and water flow rate in the PEM fuel cell. With the assistance of the visualization system, high-sensitivity double parallel conductance probes flow regime inspecting technique was adopted successfully in the experiment system to inspect the flow regime of the gas-liquid two-phase flow in the PEM fuel cell. The research results show that the double parallel conductance probes inspecting system and the flow regime image system for the gas-liquid two-phase flow in the PEM fuel cell simulated channel both can judge the slug flow and annular flow in it, and the double parallel conductance probes flow regime inspecting system can divide the annular flow into three subtypes. The main probes inspecting system and the assistant image system validate reciprocally, which enhances the experimental veracity. The typical flow regimes of the PEM fuel cell simulated channel include slug flow, annular flow with big water film wave, annular flow with small water film wave and annular flow without water film wave. With the increase of the liquid superficial velocity, the frequencies of liquid slug and wave of liquid film increase. The flow regime map in the flow channel of the PEM fuel cell was developed. The flow regime of the gas-liquid two-phase flow in a PEM fuel cell in different operating conditions can be forecasted with this map. With the PEM fuel cell operating condition in this study, the flow regimes of gas-liquid two-phase flow for different cases are all annular flow with small water film wave, and the liquid film waves more with bigger current density. With the location closer to the channel outlet, the liquid film waves are more for the same current density.

  9. Modeling the dynamic behavior of proton-exchange membrane fuel cell

    SciTech Connect

    Llapade, Peter O; Mukundan, Rangachary; Davey, John R; Borup, Rodney L; Meyers, Jeremy P

    2010-01-01

    A two-phase transient model that incorporates the permanent hysteresis observed in the experimentally measured capillary pressure of GDL has been developed. The model provides explanation for the difference in time constant between membrane hydration and dehydration observed in the HFR experiment conducted at LANL. When there is liquid water at the cathode catalyst layer, time constant of the water content in the membrane is closely tied to that of liquid water saturation in the CCL, as the vapor is already saturated. The water content in the membrane will not reach steady state as long as the liquid water flow in the CCL is not at steady state. Also, Increased resistance to proton transport in the membrane is observed when the cell voltage is stepped down to a very low value.

  10. Hydrogen-oxygen proton-exchange membrane fuel cells and electrolyzers

    NASA Technical Reports Server (NTRS)

    Baldwin, R.; Pham, M.; Leonida, A.; Mcelroy, J.; Nalette, T.

    1990-01-01

    A flight experiment is planned for the validation, in a microgravity environment, of several ground-proven simplification features relating to SPE fuel cells and SPE electrolyzers. With a successful experiment, these features can be incorporated into equipment designs for specific extraterrestrial energy storage applications.

  11. Hydrogen-oxygen proton-exchange membrane fuel cells and electrolyzers

    NASA Technical Reports Server (NTRS)

    Baldwin, R.; Pham, M.; Leonida, A.; Mcelroy, J.; Nalette, T.

    1990-01-01

    A flight experiment is planned for the validation, in a microgravity environment, of several ground-proven simplification features relating to SPE fuel cells and SPE electrolyzers. With a successful experiment, these features can be incorporated into equipment designs for specific extraterrestrial energy storage applications.

  12. Vanadium proton exchange membrane water electrolyser

    NASA Astrophysics Data System (ADS)

    Noack, Jens; Roznyatovskaya, Nataliya; Pinkwart, Karsten; Tübke, Jens

    2017-05-01

    In order to reverse the reactions of vanadium oxygen fuel cells and to regenerate vanadium redox flow battery electrolytes that have been oxidised by atmospheric oxygen, a vanadium proton exchange membrane water electrolyser was set up and investigated. Using an existing cell with a commercial and iridium-based catalyst coated membrane, it was possible to fully reduce V3.5+ and V3+ solutions to V2+ with the formation of oxygen and with coulomb efficiencies of over 96%. The cell achieved a maximum current density of 75 mA/cm2 during this process and was limited by the proximity of the V(III) reduction to the hydrogen evolution reaction. Due to the specific reaction mechanisms of V(IV) and V(III) ions, V(III) solutions were reduced with an energy efficiency of 61%, making this process nearly twice as energy efficient as the reduction of V(IV) to V(III). Polarisation curves and electrochemical impedance spectroscopy were used to further investigate the losses of half-cell reactions and to find ways of further increasing efficiency and performance levels.

  13. Surface area loss mechanisms of Pt3Co nanocatalysts in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Rasouli, S.; Ortiz Godoy, R. A.; Yang, Z.; Gummalla, M.; Ball, S. C.; Myers, D.; Ferreira, P. J.

    2017-03-01

    Pt3Co catalyst nanoparticles of 4.9 nm size present on the cathode side of a PEMFC membrane-electrode assembly (MEA) were analyzed by transmission electron microscopy after 10 K voltage cycles under different operating conditions. The operating conditions include baseline (0.4-0.95 V, 80° C, 100% Relative Humidity (RH)), high potential (0.4-1.05 V, 80° C, 100% RH), high temperature (0.4-0.95 V, 90° C, 100% RH), and low humidity (0.4-0.95 V, 80° C, 30% RH). Particle growth and particle loss to the membrane is more severe in the high potential sample than in the high temperature and baseline MEAs, while no significant particle growth and particle precipitation in the membrane can be observed in the low humidity sample. Particles with different morphologies were seen in the cathode including: 1-Spherical individual particles resulting from modified electro-chemical Ostwald ripening and 2-aggregated and coalesced particles resulting from either necking of two or more particles or preferential deposition of Pt between particles with consequent bridging. The difference in the composition of these morphologies results in composition variations through the cathode from cathode/diffusion media (DM) to the cathode/membrane interface.

  14. Cobalt molybdenum carbides as anode electrocatalyst for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Izhar, Shamsul; Nagai, Masatoshi

    Cobalt molybdenum (Co-Mo) carbides were prepared by the carburization of Co-Mo oxides at temperatures of 723-973 K in a stream of CH 4/H 2 gas. The carburized catalysts were evaluated using a single-stack fuel cell and three-electrode cell. The results showed high activities for the anodic electrooxidation of hydrogen over the Co-Mo catalysts carburized at 873 and 923 K. The 873 K carburized Co-Mo catalyst had the highest activity and achieved 10.9% of the performance of a commercial Pt/C catalyst in a single-stack fuel cell. The XRD, TPC, TPR and XPS results showed that the Co-Mo oxycarbide in the bulk and on the surface are the active species for the hydrogen oxidation reaction.

  15. Bipolar plate/diffuser for a proton exchange membrane fuel cell

    DOEpatents

    Besmann, Theodore M.; Burchell, Timothy D.

    2000-01-01

    A combination bipolar plate/diffuser fuel cell component includes an electrically conducting solid material having: a porous region having a porous surface; and a hermetic region, the hermetic region defining at least a portion of at least one coolant channel, the porous region defining at least a portion of at least one reactant channel, the porous region defining a flow field medium for diffusing the reactant to the porous surface.

  16. Bipolar plate/diffuser for a proton exchange membrane fuel cell

    DOEpatents

    Besmann, Theodore M.; Burchell, Timothy D.

    2001-01-01

    A combination bipolar plate/diffuser fuel cell component includes an electrically conducting solid material having: a porous region having a porous surface; and a hermetic region, the hermetic region defining at least a portion of at least one coolant channel, the porous region defining at least a portion of at least one reactant channel, the porous region defining a flow field medium for diffusing the reactant to the porous surface.

  17. Decentralized generation of electricity from biomass with proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Toonssen, Richard; Woudstra, Nico; Verkooijen, Adrian H. M.

    Biomass can be applied as the primary source for the production of hydrogen in the future. The biomass is converted in an atmospheric fluidized bed gasification process using steam as the gasifying agent. The producer gas needs further cleaning and processing before the hydrogen can be converted in a fuel cell; it is assumed that the gas cleaning processes are able to meet the requirements for a PEM-FC. The compressed hydrogen is supplied to a hydrogen grid and can be used in small-scale decentralized CHP units. In this study it is assumed that the CHP units are based on low temperature PEM fuel cells. For the evaluation of alternative technologies the whole chain of centralized hydrogen production from biomass up to and including decentralized electricity production in PEM fuel cells is considered. Two models for the production of hydrogen from biomass and three models for the combined production of electricity and heat with PEM fuel cells are built using the computer program Cycle-Tempo. Two different levels of hydrogen purity are considered in this evaluation: 60% and 99.99% pure hydrogen. The purity of the hydrogen affects both the efficiencies of the hydrogen production as well as the PEM-FC systems. The electrical exergy efficiency of the PEM-FC system without additional heat production is calculated to be 27.66% in the case of 60% hydrogen and 29.06% in the case of 99.99% pure hydrogen. The electrical exergy efficiencies of the whole conversion chain appear to be 21.68% and 18.74%, respectively. The high losses during purification of the hydrogen gas result in a higher efficiency for the case with low purity hydrogen. The removal of the last impurities strongly increases the overall exergy losses of the conversion chain.

  18. Polyphosphazene-Based Proton-Exchange Membranes for Direct Liquid Methanol Fuel Cells

    DTIC Science & Technology

    2005-11-04

    sulfonic acid site), as shown in Figure 9 and (ii) the neutralization of some sulfonic acid groups in SPOP due to complexation with PBI (see Figure 10...polybenzimidazole (for acid -base complexation crosslinking) prior to membrane casting. Some of the films containing poly[bis(3- methylphenoxy)phosphazene...sulfonated poly[bis(phenoxy)phosphazene] (SPOP) and polybenzimidazole ( PBI ) worked particularly well in a DMFC (at 60oC 1.0 M methanol, and ambient

  19. Degradation analyses of Ru85Se15 catalyst layer in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Zheng, Qiaoming; Cheng, Xuan; Jao, Ting-Chu; Weng, Fang-Bor; Su, Ay; Chiang, Yu-Chun

    2012-11-01

    Accelerated degradation tests (ADTs) for the H2/air single cell are carried out at 65 °C and ambient pressure by cycling the cell between 0 and 200 mA cm-2 up to 6000 cycles. Membrane electrode assemblies (MEAs) are prepared using the Nafion 212 membrane and the carbon supported platinum as an anode catalyst, as well as the carbon supported Ru85Se15 as a cathode catalyst prepared with five selected Nafion contents and Ru loads to represent the optimized (33% Nafion and 0.27 mg Ru cm-2), overloaded (43% Nafion and 0.61 mg Ru cm-2) and underloaded (20% Nafion and 0.14 mg Ru cm-2) conditions. The lowest cell performance loss of 44% in terms of peak power density is achieved with 33% Nafion and 0.27 mg Ru cm-2. Very severe losses of 80% and 82% are found for 20% and 43% Nafion contents, respectively, while relatively moderate losses of 57% and 64% for 0.14 and 0.61 mg Ru cm-2, respectively. Dissolution and migration of Se/Ru and corrosion of carbon support from the catalyst, together with the shrinkage and release of sulfonic acid from the membrane are identified and correlated to decayed cell performances.

  20. Iridium-decorated palladium-platinum core-shell catalysts for oxygen reduction reaction in proton exchange membrane fuel cell.

    PubMed

    Wang, Chen-Hao; Hsu, Hsin-Cheng; Wang, Kai-Ching

    2014-08-01

    Carbon-supported Pt, Pd, Pd-Pt core-shell (Pt(shell)-Pd(core)/C) and Ir-decorated Pd-Pt core-shell (Ir-decorated Pt(shell)-Pd(core)/C) catalysts were synthesized, and their physical properties, electrochemical behaviors, oxygen reduction reaction (ORR) characteristics and proton exchange membrane fuel cell (PEMFC) performances were investigated herein. From the XRD patterns and TEM images, Ir-decorated Pt(shell)-Pd(core)/C has been confirmed that Pt was deposited on the Pd nanoparticle which had the core-shell structure. Ir-decorated Pt(shell)-Pd(core)/C has more positive OH reduction peak than Pt/C, which is beneficial to weaken the binding energy of Pt-OH during the ORR. Thus, Ir-decorated Pt(shell)-Pd(core)/C has higher ORR activity than Pt/C. The maximum power density of H2-O2 PEMFC using Ir-decorated Pt(shell)-Pd(core)/C is 792.2 mW cm(-2) at 70°C, which is 24% higher than that using Pt/C. The single-cell accelerated degradation test of PEMFC using Ir-decorated Pt(shell)-Pd(core)/C shows good durability by the potential cycling of 40,000 cycles. This study concludes that Ir-decorated Pt(shell)-Pd(core)/C has the low Pt content, but it can facilitate the low-cost and high-efficient PEMFC. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Effects of proton exchange membrane on the performance and microbial community composition of air-cathode microbial fuel cells.

    PubMed

    Lee, Yun-Yeong; Kim, Tae Gwan; Cho, Kyung-Suk

    2015-10-10

    This study investigated the effects of proton exchange membranes (PEMs) on performance and microbial community of air-cathode microbial fuel cells (MFCs). Air-cathode MFCs with reactor volume of 1L were constructed in duplicate with or without PEM (designated as ACM-MFC and AC-MFC, respectively) and fed with a mixture of glucose and acetate (1:1, w:w). The maximum power density and coulombic efficiency did not differ between MFCs in the absence or presence of a PEM. However, PEM use adversely affected maximum voltage production and the rate of organic compound removal (p<0.05). Quantitative droplet digital PCR indicated that AC-MFCs had a greater bacterial population than ACM-MFCs (p<0.05). Likewise, ribosomal tag pyrosequencing revealed that the diversity index of bacterial communities was greater for AC-MFCs (p<0.05). Network analysis revealed that the most abundant genus was Enterococcus, which comprised ≥62% of the community and was positively associated with PEM and negatively associated with the rate of chemical oxygen demand (COD) removal (Pearson correlation>0.9 and p<0.05). Geobacter, which is known as an exoelectrogen, was positively associated with maximum power density and negatively associated with PEM. Thus, these results suggest that the absence of PEM favored the growth of Geobacter, a key player for electricity generation in MFC systems. Taken together, these findings demonstrate that MFC systems without PEM are more efficient with respect to power production and COD removal as well as exoelectrogen growth.

  2. Lithium polymer batteries and proton exchange membrane fuel cells as energy sources in hydrogen electric vehicles

    NASA Astrophysics Data System (ADS)

    Corbo, P.; Migliardini, F.; Veneri, O.

    This paper deals with the application of lithium ion polymer batteries as electric energy storage systems for hydrogen fuel cell power trains. The experimental study was firstly effected in steady state conditions, to evidence the basic features of these systems in view of their application in the automotive field, in particular charge-discharge experiments were carried at different rates (varying the current between 8 and 100 A). A comparison with conventional lead acid batteries evidenced the superior features of lithium systems in terms of both higher discharge rate capability and minor resistance in charge mode. Dynamic experiments were carried out on the overall power train equipped with PEM fuel cell stack (2 kW) and lithium batteries (47.5 V, 40 Ah) on the European R47 driving cycle. The usage of lithium ion polymer batteries permitted to follow the high dynamic requirement of this cycle in hard hybrid configuration, with a hydrogen consumption reduction of about 6% with respect to the same power train equipped with lead acid batteries.

  3. Degradation modeling of high temperature proton exchange membrane fuel cells using dual time scale simulation

    NASA Astrophysics Data System (ADS)

    Pohl, E.; Maximini, M.; Bauschulte, A.; vom Schloß, J.; Hermanns, R. T. E.

    2015-02-01

    HT-PEM fuel cells suffer from performance losses due to degradation effects. Therefore, the durability of HT-PEM is currently an important factor of research and development. In this paper a novel approach is presented for an integrated short term and long term simulation of HT-PEM accelerated lifetime testing. The physical phenomena of short term and long term effects are commonly modeled separately due to the different time scales. However, in accelerated lifetime testing, long term degradation effects have a crucial impact on the short term dynamics. Our approach addresses this problem by applying a novel method for dual time scale simulation. A transient system simulation is performed for an open voltage cycle test on a HT-PEM fuel cell for a physical time of 35 days. The analysis describes the system dynamics by numerical electrochemical impedance spectroscopy. Furthermore, a performance assessment is performed in order to demonstrate the efficiency of the approach. The presented approach reduces the simulation time by approximately 73% compared to conventional simulation approach without losing too much accuracy. The approach promises a comprehensive perspective considering short term dynamic behavior and long term degradation effects.

  4. Mechanisms for enhanced performance of platinum-based electrocatalysts in proton exchange membrane fuel cells.

    PubMed

    Su, Liang; Jia, Wenzhao; Li, Chang-Ming; Lei, Yu

    2014-02-01

    As a new generation of power sources, fuel cells have shown great promise for application in transportation. However, the expensive catalyst materials, especially the cathode catalysts for oxygen reduction reaction (ORR), severely limit the widespread commercialization of fuel cells. Therefore, this review article focuses on platinum (Pt)-based electrocatalysts for ORR with better catalytic performance and lower cost. Major breakthroughs in the improvement of activity and durability of electrocatalysts are discussed. Specifically, on one hand, the enhanced activity of Pt has been achieved through crystallographic control, ligand effect, or geometric effect; on the other hand, improved durability of Pt-based cathode catalysts has been realized by means of the incorporation of another noble metal or the morphological control of nanostructures. Furthermore, based on these improvement mechanisms, rationally designed Pt-based nanoparticles are summarized in terms of different synthetic strategies such as wet-chemical synthesis, Pt-skin catalysts, electrochemically dealloyed nanomaterials, and Pt-monolayer deposition. These nanoparticulate electrocatalysts show greatly enhanced catalytic performance towards ORR, aiming not only to outperform the commercial Pt/C, but also to exceed the US Department of Energy 2015 technical target ($30/kW and 5000 h). Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Modification and improvement of proton-exchange membrane fuel cells via treatment using peracetic acid

    NASA Astrophysics Data System (ADS)

    Xu, Zhiqiang; Qi, Zhigang; Kaufman, Arthur

    Electrodes and catalyst-coated membranes (CCMs) were treated using peracetic acid. After such a treatment, the properties and performance of these electrodes and CCMs were changed in several aspects. First, their catalytic activity was increased compared to the untreated counterparts. Second, their ability to hold water within the catalyst layers was increased so that the cathode did not need to be humidified. Third, if the cathode was humidified together with the anode, some of the electrodes were more readily to be flooded than the untreated counterparts.

  6. A model for hydrogen sulfide poisoning in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Shah, A. A.; Walsh, F. C.

    A polymer-electrolyte fuel cell model that incorporates the effects of hydrogen sulfide contaminant on performance is developed. The model is transient, fully two-phase and non-isothermal and includes a complex kinetic mechanism to describe the electrode reactions. Comparisons between the simulation results and data in the literature demonstrate that known trends are well captured. The effects of temperature and relative humidity variations in the anode stream are investigated, with further comparisons to experimental data and a proposed explanation for the nonlinear behaviour observed in the experiments of Mohtadi et al. [R. Mohatadi, W.-K. Lee, J. van Zee, Appl. Catal. B 56 (2005) 37-42)]. Extensions to the model and future work are discussed.

  7. Demonstrating hydrogen production from ammonia using lithium imide - Powering a small proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Hunter, Hazel M. A.; Makepeace, Joshua W.; Wood, Thomas J.; Mylius, O. Simon; Kibble, Mark G.; Nutter, Jamie B.; Jones, Martin O.; David, William I. F.

    2016-10-01

    Accessing the intrinsic hydrogen content within ammonia, NH3, has the potential to play a very significant role in the future of a CO2-free sustainable energy supply. Inexpensive light metal imides and amides are effective at decomposing ammonia to hydrogen and nitrogen (2NH3 → 3H2 + N2), at modest temperatures, and thus represent a low-cost approach to on-demand hydrogen production. Building upon this discovery, this paper describes the integration of an ammonia cracking unit with a post-reactor gas purification system and a small-scale PEM fuel cell to create a first bench-top demonstrator for the production of hydrogen using light metal imides.

  8. Homogeneous deposition of platinum nanoparticles on carbon black for proton exchange membrane fuel cell.

    PubMed

    Fang, Baizeng; Chaudhari, Nitin K; Kim, Min-Sik; Kim, Jung Ho; Yu, Jong-Sung

    2009-10-28

    A simple and efficient approach has been developed for synthesis of carbon-supported Pt nanoparticles (NPs) that combines homogeneous deposition (HD) of Pt complex species through a gradual increase of pH realized by in situ hydrolysis of urea and subsequent uniform reduction by ethylene glycol (EG) in a polyol process, giving control over the size and dispersion of Pt NPs. With increasing amount of urea in the starting Pt salt aqueous solution, the size of Pt complex species decreases and so does that of the metallic Pt NPs. The decrease in size of the Pt species is likely attributable to two determining factors: the steric contraction effect and the electrostatic charge effect. The excellent electrocatalysis ability of the Pt catalysts produced by HD-EG is demonstrated through the determination of electrochemical surface area and fuel-cell polarization performance. The Pt NPs deposited on Vulcan XC-72 (VC) carbon black by the HD-EG strategy show smaller size with more uniform dispersion, higher Pt utilization efficiency, and considerably improved fuel-cell polarization performance compared with the Pt NPs prepared by conventional sodium borohydride reduction or by a microwave-assisted polyol approach. Particularly important and significant is that this HD-EG method is very efficient for the synthesis of high Pt loading catalysts with tunable NP size and uniform particle dispersion. A high metal loading catalyst such as Pt(60 wt %)/VC fabricated by the HD-EG method outperforms ones with mid-to-low metal loadings (i.e., 40 and 20 wt %), even at a very low catalyst loading of 0.2 mg of Pt cm(-2) at the cathode, which is for the first time reported for the VC-supported Pt catalysts.

  9. Effect of mechanical vibration on platinum particle agglomeration and growth in proton exchange membrane fuel cell catalyst layer

    NASA Astrophysics Data System (ADS)

    Diloyan, Georgiy

    The objective of the current research is to study the effect of mechanical vibration on catalyst layer degradation via Platinum (Pt) particle agglomeration and growth in the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEM Fuel Cell). This study is of great importance, since many PEM fuel cells operate under a vibrating environment, such as the case of vehicular applications, and this may influence the catalyst layer degradation and fuel cell performance. Through extensive literature review, there are only few researches that have been studied the effect of mechanical vibration on PEM fuel cells. These studies focused only on PEM fuel cell performance under vibration for less than 50 hours and none of them considered the degradation of the fuel cell components, such as MEA and its catalyst layer. To study the effect of the mechanical vibration on the catalyst layer an accelerated test with potential cycling was specially designed to simulate a typical vehicle driving condition. The length of the accelerated test was designed to be 300 hour with potential cycling comprised of idle running, constant load, triangle (variable) load and overload running at various mechanical vibration conditions. These mechanical vibration conditions were as follows: 1g 20 Hz, 1g 40 Hz, 4g 20 Hz and 4g 40 Hz. No vibration tests were also conducted to study the influence of operating time and were used as a baseline for comparison study. The series of accelerated tests were followed by microscopy and spectroscopy analyses using environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM) and X-Ray diffraction (XRD). An ESEM was used to qualitatively analyze pristine and degraded catalyst. TEM and XRD were used to quantitatively analyze catalyst layer degradation via Pt agglomeration and growth in pristine and degraded states. For each test condition, PEM fuel cell performance by means of Voltage - Current (VI) curves was

  10. Wire rod coating process of gas diffusion layers fabrication for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kannan, A. M.; Sadananda, S.; Parker, D.; Munukutla, L.; Wertz, J.; Thommes, M.

    Gas diffusion layers (GDLs) were fabricated using non-woven carbon paper as a macro-porous layer substrate developed by Hollingsworth & Vose Company. A commercially viable coating process was developed using wire rod for coating micro-porous layer by a single pass. The thickness as well as carbon loading in the micro-porous layer was controlled by selecting appropriate wire thickness of the wire rod. Slurry compositions with solid loading as high as 10 wt.% using nano-chain and nano-fiber type carbons were developed using dispersion agents to provide cohesive and homogenous micro-porous layer without any mud-cracking. The surface morphology, wetting characteristics and pore size distribution of the wire rod coated GDLs were examined using FESEM, Goniometer and Hg porosimetry, respectively. The GDLs were evaluated in single cell PEMFC under various operating conditions (temperature and RH) using hydrogen and air as reactants. It was observed that the wire rod coated micro-porous layer with 10 wt.% nano-fibrous carbon based GDLs showed the highest fuel cell performance at 85 °C using H 2 and air at 50% RH, compared to all other compositions.

  11. Bulk and contact resistances of gas diffusion layers in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ye, Donghao; Gauthier, Eric; Benziger, Jay B.; Pan, Mu

    2014-06-01

    A multi-electrode probe is employed to distinguish the bulk and contact resistances of the catalyst layer (CL) and the gas diffusion layer (GDL) with the bipolar plate (BPP). Resistances are compared for Vulcan carbon catalyst layers (CL), carbon paper and carbon cloth GDL materials, and GDLs with microporous layers (MPL). The Vulcan carbon catalyst layer bulk resistance is 100 times greater than the bulk resistance of carbon paper GDL (Toray TG-H-120). Carbon cloth (CCWP) has bulk and contact resistances twice those of carbon paper. Compression of the GDL decreases the GDL contact resistance, but has little effect on the bulk resistance. Treatment of the GDL with polytetrafluoroethylene (PTFE) increases the contact resistance, but has little effect on the bulk resistance. A microporous layer (MPL) added to the GDL decreases the contact resistance, but has little effect on the bulk resistance. An equivalent circuit model shows that for channels less than 1 mm wide the contact resistance is the major source of electronic resistance and is about 10% of the total ohmic resistance associated with the membrane electrode assembly.

  12. Fabrication BaZrO3/PBI-based nanocomposite as a new proton conducting membrane for high temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Hooshyari, Khadijeh; Javanbakht, Mehran; Shabanikia, Akbar; Enhessari, Morteza

    2015-02-01

    Novel PBI (polybenzimidazole)-BaZrO3 (PBZ) nanocomposite membranes have been prepared for the high temperature proton exchange membrane (HT-PEM) fuel cells. The results showed that the water uptake, acid doping level and proton conductivity of the PBZ nanocomposite membranes were higher than that of virgin PBI membrane due to the presence of perovskite structure BaZrO3 nanoparticles, which as protonic conductor can perform as a special pathway for hydrogen transport. The proton conductivity of the PBZ nanocomposite membranes with 13 mol phosphoric acid per PBI repeat unit was obtained 125 mS/cm at 180 °C and 5% relative humidity. It was found that the performance of the fuel cells increases by increasing temperature; this was explained by faster reaction kinetic and higher proton conductivity. The power density and current density at 0.5 V 180 °C with 5% relative humidity were observed 0.56 W/cm2 and 1.12 A/cm2, respectively for PBZ nanocomposite membranes containing 4 wt% of the nanofillers. The results suggested that PBZ nanocomposite membranes are promising electrolytes for HT-PEM fuel cells with improved proton conductivity.

  13. TiO2/bi A-SPAES(Ds 1.0) composite membranes for proton exchange membrane in direct methanol fuel cell (DMFC).

    PubMed

    Zhang, Ni; Zhong, Chuanqing; Xie, Bing; Liu, Huiling; Wang, Xingzu

    2014-09-01

    A series of TiO2/bi A-SPAES(Ds 1.0) composite membranes with various contents of nano-sized TiO2 particles were prepared through sol-gel method. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These membranes were used for proton exchange membrane (PEM) for performance evaluation in direct methanol fuel cell (DMFC). These composite membranes showed good thermal stability and mechanical strength. It was found that the water uptake of these membranes enhanced with the TiO2 amount increasing in these composite membranes. Meanwhile, the introduction of TiO2 particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities of these composite membranes with 8% TiO2 particles (0.120 S/cm and 0.128 S/cm) were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) at 80 degrees C and 100 degrees C. Specially, the methanol diffusion coefficient (1.2 x 10(-7) cm2/s) of the composite membrane with 8% TiO2 content was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm2/s). As a result, the TiO2/bi A-SPAES composite membrane was considered as a promising material for PEM in DMFC.

  14. Application of proton exchange membrane fuel cells for the monitoring and direct usage of biohydrogen produced by Chlamydomonas reinhardtii

    NASA Astrophysics Data System (ADS)

    Oncel, S.; Vardar-Sukan, F.

    Photo-biologically produced hydrogen by Chlamydomonas reinhardtii is integrated with a proton exchange (PEM) fuel cell for online electricity generation. To investigate the fuel cell efficiency, the effect of hydrogen production on the open circuit fuel cell voltage is monitored during 27 days of batch culture. Values of volumetric hydrogen production, monitored by the help of the calibrated water columns, are related with the open circuit voltage changes of the fuel cell. From the analysis of this relation a dead end configuration is selected to use the fuel cell in its best potential. After the open circuit experiments external loads are tested for their effects on the fuel cell voltage and current generation. According to the results two external loads are selected for the direct usage of the fuel cell incorporating with the photobioreactors (PBR). Experiments with the PEM fuel cell generate a current density of 1.81 mA cm -2 for about 50 h with 10 Ω load and 0.23 mA cm -2 for about 80 h with 100 Ω load.

  15. Molecular-Level Modeling of the Structure and Proton Transport within the Membrane Electrode Assembly of Hydrogen Proton Exchange Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Selvan, Myvizhi Esai; Keffer, David J.

    The creation of proton exchange membrane fuel cells (PEMFCs) in the early 1960's attracted great interest with the prospect of serving as a highly efficient and eco-friendly power source. This nascent technology found a broad range of applications spanning from spacecrafts to automobiles and electronic devices. The PEMFC in its simplest form consists of an anode, where the hydrogen fuel is catalytically electro-oxidized (dissociated into protons and electrons), a cathode, where oxygen is catalytically electro-reduced (combined with protons to form water) and a polymer electrolyte membrane, which serves as the structural framework of the cell and transports protons from anode to cathode, while the electrons are forced through the external circuit generating electricity. Today, fuel cell remains one of the most promising means of generating energy from alternative fuels, with tremendous potential to reduce oil dependence and carbon emissions. However, current PEMFCs have a relatively narrow operational range and a high cost of production, thus requiring significant experimental and theoretical research to develop a thorough understanding of this technology (at both the molecular and macroscopic scale), which will ultimately render the fuel cell as an economically viable option.

  16. Addition of sulfonated silicon dioxide on an anode catalyst layer to improve the performance of a self-humidifying proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Lin, Chien-Liang; Hsu, Shih-Chieh; Ho, Wei-Yu

    2016-03-01

    Sulfonated SiO2 was added on an anode catalyst layer to manufacture a hygroscopic electrode for self-humidifying proton exchange membrane fuel cells (PEMFCs). The inherent humidity of a proton exchange membrane (PEM) determines the electrical performance of PEMFCs. To maintain the high moisture content of the PEM, self-humidifying PEMFCs can use the water produced by the fuel cell reaction and, thus, do not require external humidification. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and water contact angle measurement tests were performed to characterize the structures and properties of sulfonated SiO2 and the related electrodes, and the electric current and voltage (I-V) performance curve tests for the fuel cells were conducted under differing gas humidification conditions. When 0.01mg/cm2 of sulfonated SiO2 was added, the electrical performance of the fuel cells (50∘C) increased 29% and 59% when the fuel cell reaction gases were humidified at 70∘C and 50∘C, respectively.

  17. Structural and chemical analysis by transmission electron microscopy of Pt-Ru membrane precipitates in proton exchange membrane fuel cell aged under reformate

    NASA Astrophysics Data System (ADS)

    Henry, Philémon A.; Guétaz, Laure; Pélissier, Nathalie; Jacques, Pierre-André; Escribano, Sylvie

    2015-02-01

    Carbon supported platinum-ruthenium (Pt-Ru/C) nanoparticles are used as anode catalysts in proton exchange membrane fuel cells (PEMFCs) operated under reformate owing to their good carbon monoxide tolerance. The stability of these catalysts during fuel cell operation is still not well known. In this work, we have studied by transmission electron microscopy (TEM) the microstructural evolution of a membrane/electrode assembly after a 1000 h ageing test under reformate (26 ppm CO). The analyses clearly show dissolution of Ru from the Pt-Ru/C anode catalysts, its diffusion and precipitation within the anode micro-porous layer and within the membrane. The structure and the chemistry of the membrane precipitates were accurately analysed. The high resolution TEM images and EDS (Energy Dispersive X-Ray Spectroscopy) Pt, Ru elemental maps show that the largest precipitates display a singular flower shape consisting of a Pt-rich face-centred cubic (fcc) crystallographic structure core and Ru-rich hexagonal close-packed (hcp) crystallographic structure shell. These results suggest that within the membrane the Ru reduction is catalysed by Pt. Moreover, the localization of the precipitation band near the cathode seems to indicate that the Pt in the precipitates comes from the dissolution of cathodic Pt/C and that both Pt and Ru ions are reduced by the hydrogen crossover.

  18. The production of sulfonated chitosan-sodium alginate found in brown algae (Sargassum sp.) composite membrane as proton exchange membrane fuel cell (PEMFC)

    NASA Astrophysics Data System (ADS)

    Wafiroh, Siti; Pudjiastuti, Pratiwi; Sari, Ilma Indana

    2016-03-01

    The majority of energy was used in this period is from fossil fuel, which getting decreased in the future. The objective of this research is production and characterization of sulfonated chitosan-sodium alginate found in brown algae (Sargassum sp.) composite membrane as Proton Exchange Membrane Fuel Cell (PEMFC) for alternative energy. PEMFC was produced with 4 variations (w/w) ratio between chitosan and sodium alginate, 8 : 0, 8 : 1, 8 : 2, 8 : 4 (w/w). The production of membrane was mixed sodium alginate solution into chitosan solution and sulfonated with H2SO4 0.72 N. The characterization of the PEM was uses Modulus Young analysis, water swelling, ion exchange capacity, FTIR, SEM, DTA, methanol permeability and proton conductivity. The result of the research, showed that the optimum membrane was with ratio 8 : 2 (w/w) that the Modulus Young 8564 kN/m2, water swelling 31.86%, ion exchange capacity 1.020 meq/g, proton conductivity 8,8 × 10-6 S/cm, methanol permeability 1.90 × 10-8 g/cm2s and glass transition temperature (Tg) 100.9 °C, crystalline temperature (Tc) 227.6 °C, and the melting temperature (Tm) 267.9 °C.

  19. Development of membrane electrode assembly for high temperature proton exchange membrane fuel cell by catalyst coating membrane method

    NASA Astrophysics Data System (ADS)

    Liang, Huagen; Su, Huaneng; Pollet, Bruno G.; Pasupathi, Sivakumar

    2015-08-01

    Membrane electrode assembly (MEA), which contains cathode and anode catalytic layer, gas diffusion layers (GDL) and electrolyte membrane, is the key unit of a PEMFC. An attempt to develop MEA for ABPBI membrane based high temperature (HT) PEMFC is conducted in this work by catalyst coating membrane (CCM) method. The structure and performance of the MEA are examined by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and I-V curve. Effects of the CCM preparation method, Pt loading and binder type are investigated for the optimization of the single cell performance. Under 160 °C and atmospheric pressure, the peak power density of the MEA, with Pt loading of 0.5 mg cm-2 and 0.3 mg cm-2 for the cathode and the anode, can reach 277 mW cm-2, while a current density of 620 A cm-2 is delivered at the working voltage of 0.4 V. The MEA prepared by CCM method shows good stability operating in a short term durability test: the cell voltage maintained at ∼0.45 V without obvious drop when operated at a constant current density of 300 mA cm-2 and 160 °C under ambient pressure for 140 h.

  20. High performance polymer electrolytes based on main and side chain pyridine aromatic polyethers for high and medium temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Geormezi, M.; Chochos, C. L.; Gourdoupi, N.; Neophytides, S. G.; Kallitsis, J. K.

    Novel aromatic polyether type copolymers bearing side chain polar pyridine rings as well as combination of main and side chain pyridine units have been evaluated as potential polymer electrolytes for proton exchange membrane fuel cells (PEMFCs). The advanced chemical and physicochemical properties of these new polymers with their high oxidative stability, mechanical integrity and high glass transition temperatures (T g's up to 270 °C) and decomposition temperatures (T d's up to 480 °C) make them promising candidates for high and medium temperature proton exchange membranes in fuel cells. These copolymers exhibit adequate proton conductivities up to 0.08 S cm -1 even at moderate phosphoric acid doping levels. An optimized terpolymer chemical structure has been developed, which has been effectively tested as high temperature phosphoric acid imbibed polymer electrolyte. MEA prepared out of the novel terpolymer chemical structure is approaching state of the art fuel cell operating performance (135 mW cm -2 with electrical efficiency 45%) at high temperatures (150-180 °C) despite the low phosphoric acid content (<200 wt%) and the low platinum loading (ca. 0.7 mg cm -2). Durability tests were performed affording stable performance for more than 1000 h.

  1. CeO2 nanocubes-graphene oxide as durable and highly active catalyst support for proton exchange membrane fuel cell

    PubMed Central

    Lei, M.; Wang, Z. B.; Li, J. S.; Tang, H. L.; Liu, W. J.; Wang, Y. G.

    2014-01-01

    Rapid degradation of cell performance still remains a significant challenge for proton exchange membrane fuel cell (PEMFC). In this work, we develop novel CeO2 nanocubes-graphene oxide nanocomposites as durable and highly active catalyst support for proton exchange membrane fuel cell. We show that the use of CeO2 as the radical scavenger in the catalysts remarkably improves the durability of the catalyst. The catalytic activity retention of Pt-graphene oxide-8 wt.% CeO2 nanocomposites reaches as high as 69% after 5000 CV-cycles at a high voltage range of 0.8–1.23 V, in contrast to 19% for that of the Pt-graphene oxide composites. The excellent durability of the Pt-CeO2 nanocubes-graphene oxide catalyst is attributed to the free radical scavenging activity of CeO2, which significantly slows down the chemical degradation of Nafion binder in catalytic layers, and then alleviates the decay of Pt catalysts, resulting in the excellent cycle life of Pt-CeO2-graphene oxide nanocomposite catalysts. Additionally, the performance of single cell assembled with Nafion 211 membrane and Pt-CeO2-graphene oxide catalysts with different CeO2 contents in the cathode as well as the Pt-C catalysts in the anode are also recorded and discussed in this study. PMID:25491655

  2. CeO2 nanocubes-graphene oxide as durable and highly active catalyst support for proton exchange membrane fuel cell.

    PubMed

    Lei, M; Wang, Z B; Li, J S; Tang, H L; Liu, W J; Wang, Y G

    2014-12-10

    Rapid degradation of cell performance still remains a significant challenge for proton exchange membrane fuel cell (PEMFC). In this work, we develop novel CeO2 nanocubes-graphene oxide nanocomposites as durable and highly active catalyst support for proton exchange membrane fuel cell. We show that the use of CeO2 as the radical scavenger in the catalysts remarkably improves the durability of the catalyst. The catalytic activity retention of Pt-graphene oxide-8 wt.% CeO2 nanocomposites reaches as high as 69% after 5000 CV-cycles at a high voltage range of 0.8-1.23 V, in contrast to 19% for that of the Pt-graphene oxide composites. The excellent durability of the Pt-CeO2 nanocubes-graphene oxide catalyst is attributed to the free radical scavenging activity of CeO2, which significantly slows down the chemical degradation of Nafion binder in catalytic layers, and then alleviates the decay of Pt catalysts, resulting in the excellent cycle life of Pt-CeO2-graphene oxide nanocomposite catalysts. Additionally, the performance of single cell assembled with Nafion 211 membrane and Pt-CeO2-graphene oxide catalysts with different CeO2 contents in the cathode as well as the Pt-C catalysts in the anode are also recorded and discussed in this study.

  3. Direct-hydrogen-fueled proton-exchange-membrane (PEM) fuel cell system for transportation applications. Quarterly technical progress report No. 4, April 1, 1995--June 30, 1995

    SciTech Connect

    Oei, D.

    1995-08-03

    This is the fourth Technical Progress Report for DOE Contract No. DE-AC02-94CE50389 awarded to Ford Motor Company on July 1, 1994. The overall objective of this contract is to advance the Proton-Exchange-Membrane (PEM) fuel cell technology for automotive applications. Specifically, the objectives resulting from this contract are to: (1) Develop and demonstrate on a laboratory propulsion system within 2-1/2 years a fully functional PEM Fuel Cell Power System (including fuel cell peripherals, peak power augmentation and controls). This propulsion system will achieve, or will be shown to have the growth potential to achieve, the weights, volumes, and production costs which are competitive with those same attributes of equivalently performing internal combustion engine propulsion systems; (2) Select and demonstrate a baseline onboard hydrogen storage method with acceptable weight, volume, cost, and safety features and analyze future alternatives; and (3) Analyze the hydrogen infrastructure components to ensure that hydrogen can be safely supplied to vehicles at geographically widespread convenient sites and at prices which are less than current gasoline prices per vehicle-mile; (4) Identify any future R&D needs for a fully integrated vehicle and for achieving the system cost and performance goals.

  4. Modeling the cathode in a proton exchange membrane fuel cell using density functional theory How the carbon support can affect durability and activity of a platinum catalyst

    NASA Astrophysics Data System (ADS)

    Groves, Michael Nelson

    The current global energy and environmental challenges need to be addressed by developing a new portfolio of clean power producing devices. The proton exchange membrane fuel cell has the potential to be included and can fit into a variety of niches ranging from portable electronics to stationary residential applications. One of the many barriers to commercial viability is the cost of the cathode layer which requires too much platinum metal to achieve a comparable power output as well as would need to be replaced more frequently when compared to conventional sources for most applications. Using density functional theory, an ab initio modeling technique, these durability and activity issues are examined for platinum catalysts on graphene and carbon nanotube supports. The carbon supports were also doped by replacing individual carbon atoms with other second row elements (beryllium, boron, nitrogen, and oxygen) and the effect on the platinum-surface interaction along with the interaction between the platinum and the oxygen reduction reaction intermediates are discussed. Keywords: proton exchange membrane fuel cell, density functional theory, platinum catalyst, oxygen reduction reaction, doped carbon surfaces

  5. Vertically aligned carbon-coated titanium dioxide nanorod arrays on carbon paper with low platinum for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Jiang, Shangfeng; Yi, Baolian; Zhang, Changkun; Liu, Sa; Yu, Hongmei; Shao, Zhigang

    2015-02-01

    Carbon-coated titanium dioxide (TiO2-C) has received much attention as a catalyst support in proton exchange membrane fuel cells. In this study, TiO2 nanorod arrays (NRs) are hydrothermally grown on carbon paper and converted into TiO2-C NRs by heat treatment at 900 °C under methane atmosphere. Then, platinum nanoparticles are sputtered onto the TiO2 NRs by physical vapor deposition to produce Pt-TiO2-C. The as-prepared Pt-TiO2-C exhibits high stability during accelerated durability tests. As compared with the commercial gas diffusion electrode (GDE, 34.4% decrease), a minor reduction in the electrochemically active surface area of the Pt-TiO2-C electrode after 1500 cycles (10.6% decrease) is observed. When the as-prepared electrode with ultra-low platinum content (Pt loading: 28.67 μg cm-2) is employed as the cathode of a single cell, the electrode generates power that is 4.84 × that of the commercial GDE (Pt loading: 400 μg cm-2). An electrode that generates power of 11.9 kW gPt-1 (as the cathode) is proposed. The fabricated Pt-TiO2-C electrode can be used in proton exchange membrane fuel cells.

  6. Pre-oxidized and nitrided stainless steel alloy foil for proton exchange membrane fuel cell bipolar plates. Part 2: Single-cell fuel cell evaluation of stamped plates

    NASA Astrophysics Data System (ADS)

    Toops, Todd J.; Brady, Michael P.; Tortorelli, Peter F.; Pihl, Josh A.; Estevez, Francisco; Connors, Daniel; Garzon, Fernando; Rockward, Tommy; Gervasio, Don; Mylan, William; Kosaraju, Sree Harsha

    Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr 2N, CrN, TiN, V 2N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of proton exchange membrane (PEM) single-cell fuel cell studies of stamped and pre-oxidized/nitrided developmental Fe-20Cr-4V weight percent (wt.%) and commercial type 2205 stainless steel alloy foils. The single-cell fuel cell behavior of the stamped and pre-oxidized/nitrided material was compared to as-stamped (no surface treatment) 904L, 2205, and Fe-20Cr-4V stainless steel alloy foils and machined graphite of similar flow field design. The best fuel cell behavior among the alloys was exhibited by the pre-oxidized/nitrided Fe-20Cr-4V, which exhibited ∼5-20% better peak power output than untreated Fe-20Cr-4V, 2205, and 904L metal stampings. Durability was assessed for pre-oxidized/nitrided Fe-20Cr-4V, 904L metal, and graphite plates by 1000+ h of cyclic single-cell fuel cell testing. All three materials showed good durability with no significant degradation in cell power output. Post-test analysis indicated no metal ion contamination of the membrane electrode assemblies (MEAs) occurred with the pre-oxidized and nitrided Fe-20Cr-4V or graphite plates, and only a minor amount of contamination with the 904L plates.

  7. An experimental approach to investigate the transport of ammonia as a fuel contaminant in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Jung, Ryan M.; Cho, Hyun-Seok; Park, Sehkyu; Van Zee, J. W.

    2015-02-01

    Data are presented for the transport of NH3 from the anode to the cathode for various inlet conditions in a N2/N2 laboratory-scale fuel cell at open circuit voltage (OCV). The data were obtained with a material balance technique, which uses an ion selective electrode (ISE) to determine the concentration of ammonium ions. The results show that ammonia did not move across the membrane when the feed to both electrodes was dry. However, with humidified feeds on either side, the ammonia was transported from the anode to the cathode. The data include changes in the relative humidity of the anode inlet and the flowrate on the cathode. The data support a diffusion-solubility mechanism in a N2/N2 system at OCV.

  8. Experimental study on performance of a planar membrane humidifier for a proton exchange membrane fuel cell stack

    NASA Astrophysics Data System (ADS)

    Hwang, Jenn Jiang; Chang, Wei Ru; Kao, Jenn Kun; Wu, Wei

    2012-10-01

    Experiments are conducted to evaluate the performance of a planar membrane humidifier for a PEM fuel cell stack. The humidification performance of the humidifier adopted here includes the dew point approach temperature (DPAT), water recovery ratio (WRR), and water vapor transfer rate (WVTR). Parametric studies involve the dry inlet temperature, the wet inlet dew point, and the flow rate across the humidifier. Results show that increasing the flow rate across the humidifier linearly increases its pressure drop. However, the DPAT increases sharply at high flow rates (>350 SLPM) due to the inadequate WVTR limited by the humidifier size. In addition, increasing the wet inlet dew point reduces the humidification performance by increasing the DPAT and reducing in the WRR. Moreover, an increase in the dry inlet temperature could reduce the DPAT at the low flow rate of 100 SLPM, but does not affect the DPAT at the high flow rate of 450 SLPM. Furthermore, the electrochemical performance of the stack-humidifier assembly is only 10% less than that of the stack tested on a commercial test station. Stability test reveals a satisfactory reliability of the present membrane humidifier as well.

  9. The influence of humidification and temperature differences between inlet gases on water transport through the membrane of a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Huang, Kuan-Jen; Hwang, Sheng-Jye; Lai, Wei-Hsiang

    2015-06-01

    This paper discusses the effects of humidification and temperature differences of the anode and cathode on water transport in a proton exchange membrane fuel cell. Heaters are used to cause a difference in gas temperature between two electrodes before the gases enter the fuel cell. The results show that when the temperature of the cathode is higher than that of the anode, the electro-osmotic drag is suppressed. In contrast, when the temperature of the anode is higher than that of cathode, it is enhanced. These effects are more significant when the temperature difference between the anode and cathode is greater. The same trends are seen with back diffusion. Three cases are tested, and the results show that the suppression due to the temperature difference occurs even when the relative humidity is low at the hotter side. The water transport tendencies of electro-osmotic drag and back diffusion in different situations can be expressed as dominant percentages calculated by the water masses collected at the anode and cathode. The suppression effect due to the temperature difference is relatively insignificant with regard to back diffusion compared to electro-osmosis, so water tends to accumulate on the anode rather than the cathode side.

  10. Performance and durability of carbon black-supported Pd catalyst covered with silica layers in membrane-electrode assemblies of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Fujii, Keitaro; Ito, Mizuki; Sato, Yasushi; Takenaka, Sakae; Kishida, Masahiro

    2015-04-01

    Pd metal particles supported on a high surface area carbon black (Pd/CB) were covered with silica layers to improve the durability under severe cathode condition of proton exchange membrane fuel cells (PEMFCs). The performance and the durability of the silica-coated Pd/CB (SiO2/Pd/CB) were investigated by rotating disk electrode (RDE) in aqueous HClO4 and single cell test of the membrane-electrode assemblies (MEAs). SiO2/Pd/CB showed excellent durability exceeding Pt/CB during potential cycle in single cell test as well as in RDE measurement while Pd/CB significantly degraded. Furthermore, the MEA using SiO2/Pd/CB as the cathode catalyst showed higher performance than that using Pd/CB even in the initial state. The catalytic activity of SiO2/Pd/CB was higher than that of Pd/CB, and the drop of the cell performances due to the inhibition of electron conduction, proton conduction, and oxygen diffusion by the silica layer was not significant. It has been shown that the silica-coating is a very practical technique that can stabilize metal species originally unstable in the cathode condition of PEMFCs without a decrease in the cell performance.

  11. Validation of pore network simulations of ex-situ water distributions in a gas diffusion layer of proton exchange membrane fuel cells with X-ray tomographic images

    NASA Astrophysics Data System (ADS)

    Agaesse, Tristan; Lamibrac, Adrien; Büchi, Felix N.; Pauchet, Joel; Prat, Marc

    2016-11-01

    Understanding and modeling two-phase flows in the gas diffusion layer (GDL) of proton exchange membrane fuel cells are important in order to improve fuel cells performance. They are scientifically challenging because of the peculiarities of GDLs microstructures. In the present work, simulations on a pore network model are compared to X-ray tomographic images of water distributions during an ex-situ water invasion experiment. A method based on watershed segmentation was developed to extract a pore network from the 3D segmented image of the dry GDL. Pore network modeling and a full morphology model were then used to perform two-phase simulations and compared to the experimental data. The results show good agreement between experimental and simulated microscopic water distributions. Pore network extraction parameters were also benchmarked using the experimental data and results from full morphology simulations.

  12. Modeling of Membrane-Electrode-Assembly Degradation in Proton-Exchange-Membrane Fuel Cells - Local H2 Starvation and Start-Stop Induced Carbon-Support Corrosion

    NASA Astrophysics Data System (ADS)

    Gu, Wenbin; Yu, Paul T.; Carter, Robert N.; Makharia, Rohit; Gasteiger, Hubert A.

    Carbon-support corrosion causes electrode structure damage and thus electrode degradation. This chapter discusses fundamental models developed to predict cathode carbon-support corrosion induced by local H2 starvation and start-stop in a proton-exchange-membrane (PEM) fuel cell. Kinetic models based on the balance of current among the various electrode reactions are illustrative, yielding much insight on the origin of carbon corrosion and its implications for future materials developments. They are particularly useful in assessing carbon corrosion rates at a quasi-steady-state when an H2-rich region serves as a power source that drives an H2-free region as a load. Coupled kinetic and transport models are essential in predicting when local H2 starvation occurs and how it affects the carbon corrosion rate. They are specifically needed to estimate length scales at which H2 will be depleted and time scales that are valuable for developing mitigation strategies. To predict carbon-support loss distributions over an entire active area, incorporating the electrode pseudo-capacitance appears necessary for situations with shorter residence times such as start-stop events. As carbon-support corrosion is observed under normal transient operations, further model improvement shall be focused on finding the carbon corrosion kinetics associated with voltage cycling and incorporating mechanisms that can quantify voltage decay with carbon-support loss.

  13. Simulation studies of the membrane exchange assembly of an all-liquid, proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Byrd, Ethan D.; Miley, George H.

    A model has been designed and constructed for the all-liquid, sodium borohydride/hydrogen peroxide fuel cell under development at the University of Illinois at Urbana-Champaign. The electrochemical behavior, momentum balance, and mass balance effects within the fuel cell are modeled using the Butler-Volmer equations, Darcy's law, and Fick's law, respectively, within a finite element modeling platform. The simulations performed with the model indicate that an optimal physical design of the fuel cell's flow channel land area or current collector exists when considering the pressure differential between channels, and the diffusion layer permeability and conductivity. If properties of the diffusion layer are known, the model is an effective method of improving the fuel cell design in order to achieve higher power density.

  14. Direct-hydrogen-fueled proton-exchange-membrane fuel cell system for transportation applications. Hydrogen vehicle safety report

    SciTech Connect

    Thomas, C.E.

    1997-05-01

    This report reviews the safety characteristics of hydrogen as an energy carrier for a fuel cell vehicle (FCV), with emphasis on high pressure gaseous hydrogen onboard storage. The authors consider normal operation of the vehicle in addition to refueling, collisions, operation in tunnels, and storage in garages. They identify the most likely risks and failure modes leading to hazardous conditions, and provide potential countermeasures in the vehicle design to prevent or substantially reduce the consequences of each plausible failure mode. They then compare the risks of hydrogen with those of more common motor vehicle fuels including gasoline, propane, and natural gas.

  15. Corrosion behavior of TiN, TiAlN, TiAlSiN-coated 316L stainless steel in simulated proton exchange membrane fuel cell environment

    NASA Astrophysics Data System (ADS)

    Nam, Nguyen Dang; Vaka, Mahesh; Tran Hung, Nguyen

    2014-12-01

    To gain high hardness, good thermal stability and corrosion resistance, multicomponent TiAlSiN coating has been developed using different deposition methods. In this study, the influence of Al and Si on the electrochemical properties of TiN-coated 316L stainless steel as bipolar plate (BP) materials has been investigated in simulated proton exchange membrane fuel cell environment. The deposited TiN, TiAlN and TiAlSiN possess high hardness of 23.9, 31.7, 35.0 GPa, respectively. The coating performance of the TiN coating is enhanced by Al and Si addition due to lower corrosion current density and higher Rcoating and Rct values. This result could be attributed to the formation of crystalline-refined TiN(200), which improves the surface roughness, surface resistance, corrosion performance, and decreased passive current density.

  16. New Method for Super Hydrophobic Treatment of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells Using Electrochemical Reduction of Diazonium Salts.

    PubMed

    Thomas, Yohann R J; Benayad, Anass; Schroder, Maxime; Morin, Arnaud; Pauchet, Joël

    2015-07-15

    The purpose of this article is to report a new method for the surface functionalization of commercially available gas diffusion layers (GDLs) by the electrochemical reduction of diazonium salt containing hydrophobic functional groups. The method results in superhydrophobic GDLs, over a large area, without pore blocking. An X-ray photoelectron spectroscopy study based on core level spectra and chemical mapping has demonstrated the successful grafting route, resulting in a homogeneous distribution of the covalently bonded hydrophobic molecules on the surface of the GDL fibers. The result was corroborated by contact angle measurement, showing similar hydrophobicity between the grafted and PTFE-modified GDLs. The electrochemically modified GDLs were tested in proton exchange membrane fuel cells under automotive, wet, and dry conditions and demonstrated improved performance over traditional GDLs.

  17. Effect of polytetrafluoroethylene-treatment and microporous layer-coating on the in-plane permeability of gas diffusion layers used in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ismail, M. S.; Damjanovic, T.; Ingham, D. B.; Ma, L.; Pourkashanian, M.

    The in-plane permeability has been experimentally estimated for a number of carbon substrates and microporous layer (MPL)-coated gas diffusion layers (GDLs) as used in proton exchange membrane (PEM) fuel cells. The results show that the in-plane permeability of the tested carbon substrates decreases with increasing polytetrafluoroethylene (PTFE) loading and, in contrast, the greater is the PTFE loading in the MPL, the greater is the permeability. It has been shown that the in-plane permeability of the carbon substrates is reduced by an order of magnitude if they are coated with MPLs. Further, the permeability is different from one in-plane principal direction to another by a factor of about two. Finally, ignoring the inertial terms (for the reported flow rates) and the compressibility of the flowing air results in significant errors in the obtained values of the permeability.

  18. Enhancement of proton exchange membrane fuel cells performance at elevated temperatures and lower humidities by incorporating immobilized phosphotungstic acid in electrodes

    NASA Astrophysics Data System (ADS)

    Bose, Anima B.; Gopu, Susmitha; Li, Wei

    2014-10-01

    Doping phosphotungstic acid immobilized by silicon dioxide (PWA/SiO2) in a Nafion membrane is an effective way to achieve a good proton conductivity of the membrane in proton exchange membrane fuel cells (PEMFCs) at elevated temperatures and lower humidity. To further advance the theory, immobilized PWA/SiO2 was incorporated in the Nafion ionomer as the binder and proton conductor in the electrode matrices for additional performance enhancement. Two sets of membrane electrode assemblies (MEAs) were prepared and tested by incorporating PWA/SiO2 both in the membrane and electrodes (MEA-1) and only in the membrane (MEA-2). Analyses of the ohmic resistance, open circuit voltage, Tafel slope, charge transfer time constant of the two MEAs indicate that the superior performance of MEA-1 at elevated temperatures and low relative humidities was primarily ascribed to a better hydration of electrodes. The protonic transports across the interfaces between the electrodes and membrane were also improved, which has less impact on the performance enhancement. These results also show that the immobilized PWA/SiO2 in the electrodes did not exhibit poisoning effects on the electrocatalysts. The lack of poisoning effects is attributed to the stabilization of PWA in ionic channels with Nafion ionomer which does not interact with the electrocatalysts.

  19. Modification of Nafion membrane with biofunctional SiO2 nanofiber for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Hang; Li, Xiaojie; Zhuang, Xupin; Cheng, Bowen; Wang, Wei; Kang, Weimin; Shi, Lei; Li, Hongjun

    2017-02-01

    Proton currents are an integral part of the most important energy-converting structures in biology. We prepared a new type of bioinspired Nafion (Bio-Nafion) membrane composited of biofunctional SiO2 (Bio-SiO2) nanofiber and Nafion matrix. SiO2 nanofibers were prepared by electrospinning silica sol prepared from tetraethyl orthosilicate. Meanwhile, Bio-SiO2 nanofibers were synthesized by immobilizing amino acids (cysteine, serine, lysine, and glycine) on SiO2 nanofibers, which acted as efficient proton-conducting pathways that involved numerous H+ transport sites. In our study, the SiO2 nanofibers biofunctionalized with cysteine were further oxidized, and the composite membranes were designated as Nafion-Cys, Nafion-Lys, Nafion-Ser, and Nafion-Gly, respectively. We then investigated the different polar groups (sbnd SO3H, sbnd OH, and sbnd NH2) of the amino acids that contributed to membrane properties of thermal stability, water uptake (WU), dimensional stability, proton conductivity, and methanol permeability. Nafion-Cys exhibited the highest proton conductivity of 0.2424 S/cm (80 °C). Nafion-Gly showed the lowest proton conductivity and WU because glycine contains the least number of hydrophilic groups among the amino acids. Overall, the introduction of Bio-SiO2 nanofiber to composite membranes significantly improved proton conductivity, dimensional stability, and methanol permeability.

  20. Research and development of proton-exchange membrane (PEM) fuel cell system for transportation applications. Phase I final report

    SciTech Connect

    1996-01-01

    Objective during Phase I was to develop a methanol-fueled 10-kW fuel cell power source and evaluate its feasibility for transportation applications. This report documents research on component (fuel cell stack, fuel processor, power source ancillaries and system sensors) development and the 10-kW power source system integration and test. The conceptual design study for a PEM fuel cell powered vehicle was documented in an earlier report (DOE/CH/10435-01) and is summarized herein. Major achievements in the program include development of advanced membrane and thin-film low Pt-loaded electrode assemblies that in reference cell testing with reformate-air reactants yielded performance exceeding the program target (0.7 V at 1000 amps/ft{sup 2}); identification of oxidation catalysts and operating conditions that routinely result in very low CO levels ({le} 10 ppm) in the fuel processor reformate, thus avoiding degradation of the fuel cell stack performance; and successful integrated operation of a 10-kW fuel cell stack on reformate from the fuel processor.

  1. Cross-linked poly (vinyl alcohol)/sulfosuccinic acid polymer as an electrolyte/electrode material for H2-O2 proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ebenezer, D.; Deshpande, Abhijit P.; Haridoss, Prathap

    2016-02-01

    Proton exchange membrane fuel cell (PEMFC) performance with a cross-linked poly (vinyl alcohol)/sulfosuccinic acid (PVA/SSA) polymer is compared with Nafion® N-115 polymer. In this study, PVA/SSA (≈5 wt. % SSA) polymer membranes are synthesized by a solution casting technique. These cross-linked PVA/SSA polymers and Nafion are used as electrolytes and ionomers in catalyst layers, to fabricate different membrane electrode assemblies (MEAs) for PEMFCs. Properties of each MEA are evaluated using scanning electron microscopy, contact angle measurements, impedance spectroscopy and hydrogen pumping technique. I-V characteristics of each cell are evaluated in a H2-O2 fuel cell testing fixture under different operating conditions. PVA/SSA ionomer causes only an additional ≈4% loss in the anode performance compared to Nafion ionomer. The maximum power density obtained from PVA/SSA based cells range from 99 to 117.4 mW cm-2 with current density range of 247 to 293.4 mA cm-2. Ionic conductivity of PVA/SSA based cells is more sensitive to state of hydration of MEA, while maximum power density obtained is less sensitive to state of hydration of MEA. Maximum power density of cross-linked PVA/SSA membrane based cell is about 35% that of Nafion® N-115 based cell. From these results, cross-linked PVA/SSA polymer is identified as potential candidate for PEMFCs.

  2. In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor.

    PubMed

    Lee, Chi-Yuan; Weng, Fang-Bor; Kuo, Yzu-Wei; Tsai, Chao-Hsuan; Cheng, Yen-Ting; Cheng, Chih-Kai; Lin, Jyun-Ting

    2016-10-18

    In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS) are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery.

  3. In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor

    PubMed Central

    Lee, Chi-Yuan; Weng, Fang-Bor; Kuo, Yzu-Wei; Tsai, Chao-Hsuan; Cheng, Yen-Ting; Cheng, Chih-Kai; Lin, Jyun-Ting

    2016-01-01

    In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS) are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery. PMID:27763559

  4. Simultaneous Congo red decolorization and electricity generation in air-cathode single-chamber microbial fuel cell with different microfiltration, ultrafiltration and proton exchange membranes.

    PubMed

    Hou, Bin; Sun, Jian; Hu, Yong-you

    2011-03-01

    Different microfiltration membrane (MFM), proton exchange membrane (PEM) and ultrafiltration membranes (UFMs) with different molecular cutoff weights of 1K (UFM-1K), 5K (UFM-5K) and 10K (UFM-10K) were incorporated into air-cathode single-chamber microbial fuel cells (MFCs) which were explored for simultaneous azo dye decolorization and electricity generation to investigate the effect of membrane on the performance of the MFC. Batch test results showed that the MFC with an UFM-1K produced the highest power density of 324 mW/m(2) coupled with an enhanced coulombic efficiency compared to MFM. The MFC with UMF-10K achieved the fastest decolorization rate (4.77 mg/L h), followed by MFM (3.61 mg/L h), UFM-5K (2.38 mg/L h), UFM-1K (2.02 mg/Lh) and PEM (1.72 mg/Lh). These results demonstrated the possibility of using various membranes in the system described here, and showed that UFM-1K was the best one based on the consideration of both cost and performance.

  5. Proton exchange membrane fuel cell degradation under close to open-circuit conditions. Part I: In situ diagnosis

    NASA Astrophysics Data System (ADS)

    Wu, Jinfeng; Yuan, Xiao-Zi; Martin, Jonathan J.; Wang, Haijiang; Yang, Daijun; Qiao, Jinli; Ma, Jianxin

    Durability of polymer exchange membrane (PEM) fuel cells under a wide range of operational conditions has been generally identified as one of the top technical gaps that need to be overcome for the acceptance of this fuel cell technology as a commercially viable power source, especially for automotive and portable applications. In this study, a 1200 h lifetime test was conducted with a six-cell PEM fuel cell stack under close to open-circuit conditions. In situ measurements of the hydrogen crossover rate through the membrane, high frequency resistance and electrochemically active surface area of each single cell, in combination with cell polarization curves, were used to investigate the degradation mechanisms. Direct gas mass spectrometry of the cathode exhaust gas indicated the formation of HF, H 2O 2 and CO 2 during the durability testing. The overall cell degradation rate under this accelerated stress testing is approximately 0.128 mV h -1. The cell degradation rate for the first 800 h is much lower than that after 800 h, which may result from the dominance of different degradation mechanisms. For the first period, the degradation of fuel cell performance was mainly attributed to catalyst decay, while the subsequent dramatic degradation is likely caused by membrane failure.

  6. Novel composite polybenzimidazole-based proton exchange membranes as efficient and sustainable separators for microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Angioni, S.; Millia, L.; Bruni, G.; Ravelli, D.; Mustarelli, P.; Quartarone, E.

    2017-04-01

    Microbial fuel cells (MFCs) are gaining increasing technological relevance for wastewater remediation and ancillary energy production. MFC separators are often fabricated with ion-exchange perfluorinated membranes, the most common of them being Nafion™. Here, we prepared composite separators based on polybenzimidazole (PBI), where the filler is made of SBA-15 mesostructured silica functionalized with sulphonic moieties. These membranes allowed strong increase of power density (up to one order of magnitude), operating life and wastewater treatment efficiency with respect to Nafion™. Moreover, our sustainability and cost analysis clearly showed that PBI is more convenient than Nafion™ for making these membranes. Therefore, we conclude that PBI-based membranes are very promising as separators for MFCs.

  7. Efficiency measurement and uncertainty discussion of an electric engine powered by a "self-breathing" and "self-humidified" proton exchange membrane fuel cell.

    PubMed

    Schiavetti, Pierluigi; Del Prete, Zaccaria

    2007-08-01

    The efficiency of an automotive engine based on a "self-breathing" and "self-humidified" proton exchange membrane fuel cell stack (PEM FC) connected to a dc brushless electrical motor was measured under variable power load conditions. Experiments have been carried out on a small scale 150 W engine model. After determining the fuel cell static polarization curve and the time response to power steps, the system was driven to copy on the test bench a "standard urban load cycle" and its instantaneous efficiencies were measured at an acquisition rate of 5 Hz. The integral system efficiency over the entire urban load cycle, comprising the losses of the unavoidable auxiliary components of the engine, was then calculated. The fuel cell stack was operated mainly in "partial" dead-end mode, with a periodic anode flow channel purging, and one test was carried out in "pure" dead-end mode, with no anode channel purging. An uncertainty analysis of the efficiencies was carried out, taking into account either type A and type B evaluation methods, strengthening the discussion about the outcomes obtained for a system based on this novel simplified FC type. For our small scale engine we measured over the standard urban cycle, on the basis of the H(2) high heating value (HHV), a tank-to-wheel integral efficiency of (18.2+/-0.8)%, when the fuel cell was operated with periodic flow channel purging, and of (21.5+/-1.3)% in complete dead-end operation mode.

  8. Experimental investigation and numerical comparison of the performance of a proton exchange membrane fuel cell at different channel geometry

    NASA Astrophysics Data System (ADS)

    Khazaee, I.

    2015-08-01

    In this study, the performance of a PEM fuel cell is investigated experimentally and numerically by changing the geometry of the channels. At first an experimental setup is used and three different fuel cells with rectangular, elliptical and triangular serpentine channels are constructed. The active area of each cell is 25 cm2 that its weight is 1,300 g. The material of the gas diffusion layer is carbon clothes, the membrane is nafion 117 and the catalyst layer is a plane with 0.004 g cm-2 platinum. Then a complete three-dimensional model for fuel cell is used to investigate the effect of using this channels geometry on the performance. The proposed model is a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations are solved in a single domain; therefore no interfacial boundary condition is required at the internal boundaries between cell components. The results show that the predicted polarization curves by using this model are in good agreement with the experimental results. Also the results show that when the geometry of channel is rectangular the performance of the cell is better than the triangular and elliptical channel.

  9. A Comparison of Flow-Through Versus Non-Flow-Through Proton Exchange Membrane Fuel Cell Systems for NASA's Exploration Missions

    NASA Technical Reports Server (NTRS)

    Hoberecht, Mark A.

    2010-01-01

    As part of the Exploration Technology Development Program (ETDP) under the auspices of the Exploration Systems Mission Directorate (ESMD), NASA is developing both primary fuel cell power systems and regenerative fuel cell (RFC) energy storage systems within the fuel cell portion of the Energy Storage Project. This effort is being led by the NASA Glenn Research Center (GRC) in partnership with the NASA Johnson Space Center (JSC), Jet Propulsion Laboratory (JPL), NASA Kennedy Space Center (KSC), and industrial partners. The development goals are to improve fuel cell and electrolysis stack electrical performance, reduce system mass, volume, and parasitic power requirements, and increase system life and reliability. A major focus of this effort has been the parallel development of both flow-through and non-flow-through proton exchange membrane (PEM) primary fuel cell power systems. The plan has been, at the appropriate time, to select a single primary fuel cell technology for eventual flight hardware development. Ideally, that appropriate time would occur after both technologies have achieved a technology readiness level (TRL) of six, which represents an engineering model fidelity PEM fuel cell system being successfully tested in a relevant environment. Budget constraints in fiscal year 2009 and beyond have prevented NASA from continuing to pursue the parallel development of both primary fuel cell options. Because very limited data exists for either system, a toplevel, qualitative assessment based on engineering judgement was performed expeditiously to provide guidance for a selection. At that time, the non-flow-through technology was selected for continued development because of potentially major advantages in terms of weight, volume, parasitic power, reliability, and life. This author believes that the advantages are significant enough, and the potential benefits great enough, to offset the higher state of technology readiness of flow-through technology. This paper

  10. Investigation of carbon supported PtW catalysts as CO tolerant anodes at high temperature in proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Hassan, Ayaz; Paganin, Valdecir A.; Ticianelli, Edson A.

    2016-09-01

    The CO tolerance mechanism and the stability of carbon supported PtW electrocatalysts are evaluated in the anode of a proton exchange membrane fuel cell (PEMFC) at two different temperatures. The electrocatalysts are characterized by energy dispersive spectroscopy, X-ray diffraction, and transmission electron spectroscopy. Employed electrochemical techniques include cyclic voltammetry, CO stripping, fuel cell polarization, and online mass spectrometry. At a cell temperature of 85 °C, the PtW/C catalyst shows higher CO tolerance compared to Pt/C due an electronic effect of WOx in the Pt 5d band, which reduces the CO adsorption. An increase in hydrogen oxidation activity in the presence of CO is observed for both the catalysts at a higher temperature, due to the decrease of the Pt-CO coverage. A reduction in the current densities occurs for the PtW/C catalyst in both polarization curves and cyclic voltammograms after 5000 cycles of the anode in the range of 0.1-0.7 V vs. RHE at 50 mVs-1. This decrease in performance is assigned to the dissolution of W, with a consequent increase in the membrane resistivity. However, the observed decline of performance is small either in the presence of pure H2 or in the presence of H2/CO.

  11. Insights into the distribution of water in a self-humidifying H2/O2 proton-exchange membrane fuel cell using 1H NMR microscopy.

    PubMed

    Feindel, Kirk W; Bergens, Steven H; Wasylishen, Roderick E

    2006-11-01

    Proton ((1)H) NMR microscopy is used to investigate in-situ the distribution of water throughout a self-humidifying proton-exchange membrane fuel cell, PEMFC, operating at ambient temperature and pressure on dry H(2)(g) and O(2)(g). The results provide the first experimental images of the in-plane distribution of water within the PEM of a membrane electrode assembly in an operating fuel cell. The effect of gas flow configuration on the distribution of water in the PEM and cathode flow field is investigated, revealing that the counter-flow configurations yield a more uniform distribution of water throughout the PEM. The maximum power output from the PEMFC, while operating under conditions of constant external load, occurs when H(2)O(l) is first visible in the (1)H NMR image of the cathode flow field, and subsequently declines as this H(2)O(l) continues to accumulate. The (1)H NMR microscopy experiments are in qualitative agreement with predictions from several theoretical modeling studies (e.g., Pasaogullari, U.; Wang, C. Y. J. Electrochem. Soc. 2005, 152, A380-A390), suggesting that combined theoretical and experimental approaches will constitute a powerful tool for PEMFC design, diagnosis, and optimization.

  12. Enhanced performance of polybenzimidazole-based high temperature proton exchange membrane fuel cell with gas diffusion electrodes prepared by automatic catalyst spraying under irradiation technique

    NASA Astrophysics Data System (ADS)

    Su, Huaneng; Pasupathi, Sivakumar; Bladergroen, Bernard Jan; Linkov, Vladimir; Pollet, Bruno G.

    2013-11-01

    Gas diffusion electrodes (GDEs) prepared by a novel automatic catalyst spraying under irradiation (ACSUI) technique are investigated for improving the performance of phosphoric acid (PA)-doped polybenzimidazole (PBI) high temperature proton exchange membrane fuel cell (PEMFC). The physical properties of the GDEs are characterized by pore size distribution and scanning electron microscopy (SEM). The electrochemical properties of the membrane electrode assembly (MEA) with the GDEs are evaluated and analyzed by polarization curve, cyclic voltammetry (CV) and electrochemistry impedance spectroscopy (EIS). Effects of PTFE binder content, PA impregnation and heat treatment on the GDEs are investigated to determine the optimum performance of the single cell. At ambient pressure and 160 °C, the maximum power density can reach 0.61 W cm-2, and the current density at 0.6 V is up to 0.38 A cm-2, with H2/air and a platinum loading of 0.5 mg cm-2 on both electrodes. The MEA with the GDEs shows good stability for fuel cell operating in a short term durability test.

  13. Performance degradation studies on an poly 2,5-benzimidazole high-temperature proton exchange membrane fuel cell using an accelerated degradation technique

    NASA Astrophysics Data System (ADS)

    Jung, Guo-Bin; Chen, Hsin-Hung; Yan, Wei-Mon

    2014-02-01

    In this work, the performance degradation of a poly 2,5-benzimidazole (ABPBI) based high-temperature proton exchange membrane fuel cell (HT-PEMFC) was examined using an accelerated degradation technique (ADT). Experiments using an ADT with 30 min intervals were performed by applying 1.5 V to a membrane electrode assembly (MEA) with hydrogen and nitrogen feeding to the anode and cathode, respectively, to simulate the high voltage generated during fuel cell shutdown and restart. The characterization of the MEAs was performed using in-situ and ex-situ electrochemical methods, such as polarization curves, AC impedance, and cyclic voltammetry (CV), and TEM imaging before and after the ADT experiments. The measured results demonstrated that the ADT testing could be used to dramatically reduce the duration of the degradation. The current output at 0.4 V decreased by 48% after performing ADT testing for 30 min. From the AC impedance, CV and RTGA measurements, the decline in cell performance was found to be primarily due to corrosion and thinning of the catalyst layer (or carbon support) during the first 30 min, leading to the dissolution and agglomeration of the platinum catalyst.

  14. Local potential evolutions during proton exchange membrane fuel cell operation with dead-ended anode - Part II: Aging mitigation strategies based on water management and nitrogen crossover

    NASA Astrophysics Data System (ADS)

    Abbou, S.; Dillet, J.; Maranzana, G.; Didierjean, S.; Lottin, O.

    2017-02-01

    Proton exchange membrane (PEM) fuel cells operate with dead-ended anode in order to reduce system cost and complexity when compared with hydrogen re-circulation systems. In the first part of this work, we showed that localized fuel starvation events may occur, because of water and nitrogen accumulation in the anode side, which could be particularly damaging to the cell performance. To prevent these degradations, the anode compartment must be purged which may lead to an overall system efficiency decrease because of significant hydrogen waste. In the second part, we present several purge strategies in order to minimize both hydrogen waste and membrane-electrode assembly degradations during dead-ended anode operation. A linear segmented cell with reference electrodes was used to monitor simultaneously the current density distribution along the gas channel and the time evolution of local anode and cathode potentials. To asses MEA damages, Platinum ElectroChemical Surface Area (ECSA) and cell performance were periodically measured. The results showed that dead-end mode operation with an anode plate maintained at a temperature 5 °C hotter than the cathode plate limits water accumulation in the anode side, reducing significantly purge frequency (and thus hydrogen losses) as well as MEA damages. As nitrogen contribution to hydrogen starvation is predominant in this thermal configuration, we also tested a microleakage solution to discharge continuously most the nitrogen accumulating in the anode side while ensuring low hydrogen losses and minimum ECSA losses provided the right microleakage flow rate is chosen.

  15. SSH2S: Hydrogen storage in complex hydrides for an auxiliary power unit based on high temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Baricco, Marcello; Bang, Mads; Fichtner, Maximilian; Hauback, Bjorn; Linder, Marc; Luetto, Carlo; Moretto, Pietro; Sgroi, Mauro

    2017-02-01

    The main objective of the SSH2S (Fuel Cell Coupled Solid State Hydrogen Storage Tank) project was to develop a solid state hydrogen storage tank based on complex hydrides and to fully integrate it with a High Temperature Proton Exchange Membrane (HT-PEM) fuel cell stack. A mixed lithium amide/magnesium hydride system was used as the main storage material for the tank, due to its high gravimetric storage capacity and relatively low hydrogen desorption temperature. The mixed lithium amide/magnesium hydride system was coupled with a standard intermetallic compound to take advantage of its capability to release hydrogen at ambient temperature and to ensure a fast start-up of the system. The hydrogen storage tank was designed to feed a 1 kW HT-PEM stack for 2 h to be used for an Auxiliary Power Unit (APU). A full thermal integration was possible thanks to the high operation temperature of the fuel cell and to the relative low temperature (170 °C) for hydrogen release from the mixed lithium amide/magnesium hydride system.

  16. Study of the aromatic hydrocarbons poisoning of platinum cathodes on proton exchange membrane fuel cell spatial performance using a segmented cell system

    NASA Astrophysics Data System (ADS)

    Reshetenko, Tatyana V.; St-Pierre, Jean

    2016-11-01

    Aromatic hydrocarbons are produced and used in many industrial processes, which makes them hazardous air pollutants. Currently, air is the most convenient oxidant for proton exchange membrane fuel cells (PEMFCs), and air quality is an important consideration because airborne contaminants can negatively affect fuel cell performance. The effects of exposing the cathode of PEMFCs to benzene and naphthalene were investigated using a segmented cell system. The introduction of 2 ppm C6H6 resulted in moderate performance loss of 40-45 mV at 0.2 A cm-2 and 100-110 mV at 1.0 A cm-2 due to benzene adsorption on Pt and its subsequent electrooxidation to CO2 under operating conditions and cell voltages of 0.5-0.8 V. In contrast, PEMFC poisoning by ∼2 ppm of naphthalene led to a decrease in cell performance from 0.66 to 0.13 V at 1.0 A cm-2, which was caused by the strong adsorption of C10H8 onto Pt at cell voltages of 0.2-1.0 V. Naphthalene desorption and hydrogenation only occurred at potentials below 0.2 V. The PEMFCs' performance loss due to each contaminant was recoverable, and the obtained results demonstrated that the fuel cells' exposure to benzene and naphthalene should be limited to concentrations less than 2 ppm.

  17. Modelling of the vapour-liquid equilibrium of water and the in situ concentration of H3PO4 in a high temperature proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Kazdal, Timur J.; Lang, Sebastian; Kühl, Frank; Hampe, Manfred J.

    2014-03-01

    The fuel cell technology is a key element for the hydrogen energy economy and therefore crucial for sustainable development. High temperature proton exchange membrane (HT-PEM) fuel cells (FC) can be operated with reformate gas and thus represent an important bridging technology for the energy transition to a renewable energy based system. HT-PEM FCs based on phosphoric acid (PA) are still subject to intense research, investigating the electrolyte behaviour. By enhancing state of the art 2D FEM simulations of FCs with the vapour liquid equilibrium of water-phosphoric acid and evaporation kinetics, a model was created in which the local concentration of PA can be calculated. Knowledge of the concentration field yields the basis for calculating the locally varying ionic conductivity and other physical properties. By describing the volume expansion behaviour of PA it was possible to predict the catalyst particle deactivation due to the swelling of PA. The in situ concentration predicted by the simulation ranges from 96 to 111 wt%. The model was validated using measured data of a single cell design for different temperatures and pressures. By varying the PA content flooding of the simulated fuel cell could be observed and was linked to humidification effects.

  18. Water emergence from the land region and water-sidewall interactions in Proton Exchange Membrane Fuel Cell gas channels with microgrooves

    NASA Astrophysics Data System (ADS)

    Shah, Mihir M.; Kandlikar, Satish G.

    2015-11-01

    Liquid water produced in a Proton Exchange Membrane Fuel Cell (PEMFC) can adversely affect the fuel cell performance in two ways: (a) reduction in surface area available for reactant transport at the channel-gas diffusion layer (GDL) interface, and (b) increase in two-phase pressure drop in channels leading to flow maldistribution and increased pumping power. Further, the channels blocked by water reduce reactant availability at reaction sites. Most of the earlier water transport studies were focused on water droplet formation on the gas diffusion layer (GDL) in the channel and its removal from the gas flow without considering the sidewall interactions. In an actual fuel cell, water under the land emerges in the channel and fills the corner, drawing in additional water from the GDL surface. The present work explores water droplet-sidewall interactions and the transport of water from the corner region. Transverse micro-grooves are introduced on the sidewalls and their effect on water removal from the corner region, flow patterns, area coverage ratio and pressure drop are investigated. The micro-grooves are also seen to introduce a wetting regime that facilitates removal of water at the channel exit without causing blockage at the manifold region.

  19. Comparative degradation study of carbon supported proton exchange membrane fuel cell electrocatalysts - The influence of the platinum to carbon ratio on the degradation rate

    NASA Astrophysics Data System (ADS)

    Speder, Jozsef; Zana, Alessandro; Spanos, Ioannis; Kirkensgaard, Jacob J. K.; Mortensen, Kell; Hanzlik, Marianne; Arenz, Matthias

    2014-09-01

    A colloidal synthesis approach is used to prepare supported proton exchange membrane fuel cell (PEMFC) catalysts with various Pt loadings - from low to extremely high ones. The catalyst samples are used to continue our investigation of the role of the Pt:C ratio in the degradation processes. The influence of the platinum loading on the electrochemical surface area (ECSA) loss is evaluated in a systematic electrochemical study by using two commercially available carbon blacks, namely Vulcan XC72R and Ketjenblack EC-300J. Accelerated degradation tests simulating load cycle and start-up/shutdown conditions are carried out in accordance with the Fuel Cell Commercialization Conference of Japan (FCCJ) recommendations. Under conditions simulating the load cycle of PEM fuel cells no unambiguous correlation between the ECSA loss and the Pt:C ratio is found. By contrast, under conditions simulating the repetitive start-up/shutdown processes of PEMFCs the ECSA loss first increases with increasing Pt loading. However, it decreases again for very high loadings. Furthermore, the Vulcan samples exhibited higher ECSA losses than the Ketjenblack samples, indicating the important role of the physical and chemical properties of pristine carbon supports in the carbon degradation mechanism.

  20. Interfacial Water-Transport Effects in Proton-Exchange Membranes

    SciTech Connect

    Kienitz, Brian; Yamada, Haruhiko; Nonoyama, Nobuaki; Weber, Adam

    2009-11-19

    It is well known that the proton-exchange membrane is perhaps the most critical component of a polymer-electrolyte fuel cell. Typical membranes, such as Nafion(R), require hydration to conduct efficiently and are instrumental in cell water management. Recently, evidence has been shown that these membranes might have different interfacial morphology and transport properties than in the bulk. In this paper, experimental data combined with theoretical simulations will be presented that explore the existence and impact of interfacial resistance on water transport for Nafion(R) 21x membranes. A mass-transfer coefficient for the interfacial resistance is calculated from experimental data using different permeation cells. This coefficient is shown to depend exponentially on relative humidity or water activity. The interfacial resistance does not seem to exist for liquid/membrane or membrane/membrane interfaces. The effect of the interfacial resistance is to flatten the water-content profiles within the membrane during operation. Under typical operating conditions, the resistance is on par with the water-transport resistance of the bulk membrane. Thus, the interfacial resistance can be dominant especially in thin, dry membranes and can affect overall fuel-cell performance.

  1. Highly Durable Supportless Pt Hollow Spheres Designed for Enhanced Oxygen Transport in Cathode Catalyst Layers of Proton Exchange Membrane Fuel Cells.

    PubMed

    Dogan, Didem C; Cho, Seonghun; Hwang, Sun-Mi; Kim, Young-Min; Guim, Hwanuk; Yang, Tae-Hyun; Park, Seok-Hee; Park, Gu-Gon; Yim, Sung-Dae

    2016-10-10

    Supportless Pt catalysts have several advantages over conventional carbon-supported Pt catalysts in that they are not susceptible to carbon corrosion. However, the need for high Pt loadings in membrane electrode assemblies (MEAs) to achieve state-of-the-art fuel cell performance has limited their application in proton exchange membrane fuel cells. Herein, we report a new approach to the design of a supportless Pt catalyst in terms of catalyst layer architecture, which is crucial for fuel cell performance as it affects water management and oxygen transport in the catalyst layers. Large Pt hollow spheres (PtHSs) 100 nm in size were designed and prepared using a carbon template method. Despite their large size, the unique structure of the PtHSs, which are composed of a thin-layered shell of Pt nanoparticles (ca. 7 nm thick), exhibited a high surface area comparable to that of commercial Pt black (PtB). The PtHS structure also exhibited twice the durability of PtB after 2000 potential cycles (0-1.3 V, 50 mV/s). A MEA fabricated with PtHSs showed significant improvement in fuel cell performance compared to PtB-based MEAs at high current densities (>800 mA/cm(2)). This was mainly due to the 2.7 times lower mass transport resistance in the PtHS-based catalyst layers compared to that in PtB, owing to the formation of macropores between the PtHSs and high porosity (90%) in the PtHS catalyst layers. The present study demonstrates a successful example of catalyst design in terms of catalyst layer architecture, which may be applied to a real fuel cell system.

  2. Three-Dimensional Transport Modeling for Proton Exchange Membrane(PEM) Fuel Cell with Micro Parallel Flow Field

    PubMed Central

    Lee, Pil Hyong; Han, Sang Seok; Hwang, Sang Soon

    2008-01-01

    Modeling and simulation for heat and mass transport in micro channel are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize fuel cell designs before building a prototype for engineering application. In this study, we used a single-phase, fully three dimensional simulation model for PEMFC that can deal with both anode and cathode flow field for examining the micro flow channel with electrochemical reaction. The results show that hydrogen and oxygen were solely supplied to the membrane by diffusion mechanism rather than convection transport, and the higher pressure drop at cathode side is thought to be caused by higher flow rate of oxygen at cathode. And it is found that the amount of water in cathode channel was determined by water formation due to electrochemical reaction plus electro-osmotic mass flux directing toward the cathode side. And it is very important to model the back diffusion and electro-osmotic mass flux accurately since the two flux was closely correlated each other and greatly influenced for determination of ionic conductivity of the membrane which directly affects the performance of fuel cell. PMID:27879774

  3. Enhanced performance and stability of high temperature proton exchange membrane fuel cell by incorporating zirconium hydrogen phosphate in catalyst layer

    NASA Astrophysics Data System (ADS)

    Barron, Olivia; Su, Huaneng; Linkov, Vladimir; Pollet, Bruno G.; Pasupathi, Sivakumar

    2015-03-01

    Zirconium hydrogen phosphate (ZHP) together with polytetrafluoroethylene (PTFE) polymer binder is incorporated into the catalyst layers (CLs) of ABPBI (poly(2,5-benzimidazole))-based high temperature polymer electrolyte membrane fuel cell (HT-PEMFCs) to improve its performance and durability. The influence of ZHP content (normalised with respect to dry PTFE) on the CL properties are structurally characterised by scanning electron microscopy (SEM) and mercury intrusion porosimetry. Electrochemical analyses of the resultant membrane electrode assemblies (MEAs) are performed by recording polarisation curves and impedance spectra at 160 °C, ambient pressure and humidity. The result show that a 30 wt.% ZHP/PTFE content in the CL is optimum for improving fuel cell performance, the resultant MEA delivers a peak power of 592 mW cm-2 at a cell voltage of 380 mV. Electrochemical impedance spectra (EIS) indicate that 30% ZHP in the CL can increase the proton conductivity compared to the pristine PTFE-gas diffusion electrode (GDE). A short term stability test (∼500 h) on the 30 wt.% ZHP/PTFE-GDE shows a remarkable high durability with a degradation rate as low as ∼19 μV h-1 at 0.2 A cm-2, while 195 μV h-1 was obtained for the pristine GDE.

  4. Multi-block sulfonated poly(phenylene) copolymer proton exchange membranes

    DOEpatents

    Fujimoto, Cy H [Albuquerque, NM; Hibbs, Michael [Albuquerque, NM; Ambrosini, Andrea [Albuquerque, NM

    2012-02-07

    Improved multi-block sulfonated poly(phenylene) copolymer compositions, methods of making the same, and their use as proton exchange membranes (PEM) in hydrogen fuel cells, direct methanol fuel cells, in electrode casting solutions and electrodes. The multi-block architecture has defined, controllable hydrophobic and hydrophilic segments. These improved membranes have better ion transport (proton conductivity) and water swelling properties.

  5. Use of impedance spectroscopy to investigate factors that influence the performance and durability of proton exchange membrane (PEM) fuel cells

    NASA Astrophysics Data System (ADS)

    Roy, Sunil K.

    Impedance spectroscopy provides the opportunity for in-situ identification and quantification of physical processes and has been used extensively to study the behavior of the fuel cell. However, a key question to be answered is whether the features seen in the impedance response are caused by an artifact or represent a physical process taking place in the system. The measurement model developed by our group can be used to identify the frequency ranges unaffected by bias errors associated with instrument artifacts and non-stationary behavior. Impedance measurements were performed with the 850C fuel-cell test station supplied by Scribner Associates and with a Gamry Instruments FC350 impedance analyzer coupled with a Dynaload electronic load. All electrochemical measurements were performed with a two-electrode cell in which the anode served as a pseudo-reference electrode. The experiments were conducted in galavanostatic mode for a frequency range of 0.001-3000 Hz with 10 mA peak-to-peak sinusoidal perturbation, and ten points were collected per frequency decade. Ultra pure hydrogen was used as the anode fuel, and compressed air was used as oxidant. The measurement model was used to show that low-frequency inductive loops were, in some cases, fully self consistent, and, therefore, the inductive loops could be attributed to processes occurring in the fuel cell. Then we developed first-principle models that incorporate processes that may be responsible for the inductive response seen at low frequencies. We found that side reactions producing hydrogen peroxide intermediates and reactions causing Pt deactivation could yield inductive loops. These side reactions and the intermediates can degrade fuel cell components such as membranes and electrodes, thereby reducing the lifetime the fuel cells. The hypothesized reaction involving of peroxide and PtO formation were supported by microstructural characterization. A more sensitive manner of using impedance spectroscopy to gain

  6. Advanced proton-exchange materials for energy efficient fuel cells.

    SciTech Connect

    Fujimoto, Cy H.; Grest, Gary Stephen; Hickner, Michael A.; Cornelius, Christopher James; Staiger, Chad Lynn; Hibbs, Michael R.

    2005-12-01

    The ''Advanced Proton-Exchange Materials for Energy Efficient Fuel Cells'' Laboratory Directed Research and Development (LDRD) project began in October 2002 and ended in September 2005. This LDRD was funded by the Energy Efficiency and Renewable Energy strategic business unit. The purpose of this LDRD was to initiate the fundamental research necessary for the development of a novel proton-exchange membranes (PEM) to overcome the material and performance limitations of the ''state of the art'' Nafion that is used in both hydrogen and methanol fuel cells. An atomistic modeling effort was added to this LDRD in order to establish a frame work between predicted morphology and observed PEM morphology in order to relate it to fuel cell performance. Significant progress was made in the area of PEM material design, development, and demonstration during this LDRD. A fundamental understanding involving the role of the structure of the PEM material as a function of sulfonic acid content, polymer topology, chemical composition, molecular weight, and electrode electrolyte ink development was demonstrated during this LDRD. PEM materials based upon random and block polyimides, polybenzimidazoles, and polyphenylenes were created and evaluated for improvements in proton conductivity, reduced swelling, reduced O{sub 2} and H{sub 2} permeability, and increased thermal stability. Results from this work reveal that the family of polyphenylenes potentially solves several technical challenges associated with obtaining a high temperature PEM membrane. Fuel cell relevant properties such as high proton conductivity (>120 mS/cm), good thermal stability, and mechanical robustness were demonstrated during this LDRD. This report summarizes the technical accomplishments and results of this LDRD.

  7. Preparation and characterization of polybenzimidzaole/diethylamine hydrogen sulphate for medium temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Mamlouk, M.; Ocon, P.; Scott, K.

    2014-01-01

    Diethlyamine bisulphate/sulphate, an ionic liquid, was synthesised and characterised for high temperature fuel cell applications. Composite hybrid membranes of PBI and the ionic liquid diethlyamine bisulphate/sulfate were fabricated at different composition ratios PBI/xDESH. FTIR spectra showed that the IL did not change the PBI structure. The ionic liquid only weakly interacts with PBI and remains free inside the structure allowing for the observed ionic conduction. PBI/xDESH membranes could operate under a higher temperature values/low humidity conditions with conductivity >0.01 S cm-1. The measured proton conductivity, from symmetrical H2 cell, however, is ca. 4 times lower than that of the measured ionic conductivity. This could be estimated roughly by considering proton conduction where the proton is associated with two anions A- resulting in ionic agglomerate HA2- with more than double the ionic radius of A- and consequently less than half of its diffusivity. Additionally, considering the solvation number of that agglomerate to be 1.0 will result not only in a slower proton diffusion and lower conductivity but will also cause serious flooding and mass transport limitation at the cathode. This cumulative effect will limit the life of the cell due to the IL migration from anode and membrane to the cathode.

  8. Pre-Oxidized and Nitrided Stainless Steel Foil for Proton Exchange Membrane Fuel Cell Bipolar Plates: Part 1 Corrosion, Interfacial Contact Resistance, and Surface Structure

    SciTech Connect

    Brady, Michael P; Wang, Heli; Turner, John; Meyer III, Harry M; More, Karren Leslie; Tortorelli, Peter F; McCarthy, Brian D

    2010-01-01

    Thermal (gas) nitridation of stainless steels can yield low interfacial contact resistance (ICR), electrically-conductive and corrosion-resistant nitride containing surfaces (Cr2N, CrN, TiN, V2N, VN, etc) of interest for fuel cells, batteries, and sensors. This paper presents the results of scale up studies to determine the feasibility of extending the nitridation approach to thin 0.1 mm stainless steel alloy foils for proton exchange membrane fuel cell (PEMFC) bipolar plates. A major emphasis was placed on selection of alloy foil composition and nitidation conditions potentially capable of meeting the stringent cost goals for automotive PEMFC applications. Developmental Fe-20Cr-4V alloy and type 2205 stainless steel foils were treated by pre-oxidation and nitridation to form low-ICR, corrosion-resistant surfaces. Promising behavior was observed under simulated aggressive anode- and cathode- side bipolar plate conditions for both materials. Variation in ICR values were observed for treated 2205 foil, with lower (better) values generally observed for the treated Fe-20Cr-4V. This behavior was linked to the nature of the pre-oxidized and nitrided surface structure, which contained through surface layer thickness V-nitride particles in the case of Fe-20Cr-4V but near continuous chromia in the case of 2205 stainless steel. The implications of these findings for stamped bipolar plate foils are discussed.

  9. Pre-oxidized and nitrided stainless steel alloy foil for proton exchange membrane fuel cell bipolar plates: Part 1. Corrosion, interfacial contact resistance, and surface structure

    NASA Astrophysics Data System (ADS)

    Brady, M. P.; Wang, H.; Turner, J. A.; Meyer, H. M.; More, K. L.; Tortorelli, P. F.; McCarthy, B. D.

    Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr 2N, CrN, TiN, V 2N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of scale-up studies to determine the feasibility of extending the nitridation approach to thin 0.1 mm stainless steel alloy foils for proton exchange membrane fuel cell (PEMFC) bipolar plates. Developmental Fe-20Cr-4V alloy and type 2205 stainless steel foils were treated by pre-oxidation and nitridation to form low-ICR, corrosion-resistant surfaces. As-treated Fe-20Cr-4V foil exhibited target (low) ICR values, whereas 2205 foil suffered from run-to-run variation in ICR values, ranging up to 2× the target value. Pre-oxidized and nitrided surface structure examination revealed surface-through-layer-thickness V-nitride particles for the treated Fe-20Cr-4V, but near continuous chromia for treated 2205 stainless steel, which was linked to the variation in ICR values. Promising corrosion resistance was observed under simulated aggressive PEMFC anode- and cathode-side bipolar plate conditions for both materials, although ICR values were observed to increase. The implications of these findings for stamped bipolar plate foils are discussed.

  10. Production of high-performance and improved-durability Pt-catalyst /support for proton-exchange-membrane fuel cells with pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Huang, Ting-Wei; Qayyum, Hamza; Lin, Guan-Ren; Chen, Szu-yuan; Tseng, Chung-Jen

    2016-06-01

    Pulsed laser deposition in Ar atmosphere is used to deposit Pt nanoparticles onto gas diffusion layer, and its application to proton-exchange-membrane fuel cell is optimized and characterized. When used at anode side, with a Pt loading of 17 μg cm-2 the fuel-cell current density at 0.6 V reaches 1.08 A cm-2, which is close to that of a cell with the anode made by conventional slurry process using E-TEK Pt /C of 200 μg cm-2 Pt loading. The usage of Pt is decreased by 12 fold. Such a low usage of Pt prepared by pulsed laser deposition can be ascribed to the prevention of forming isolated regions that occurs with Pt /C slurry, good dispersion of Pt particles on support, and small particle sizes of 2-3 nm. Furthermore, using accelerated degradation test, it is found that the pulsed laser deposition sample retains 60% of its initial electrochemical surface area after 5000 potential cycles, much higher than that with E-TEK Pt /C, which retains only 7% of its initial electrochemical surface area. The higher electrochemical durability can be attributed to the higher degree of graphitization in the gas diffusion layer used as compared with the carbon black in E-TEK Pt /C, which leads to stronger binding of the Pt nanoparticles onto the carbon support and stronger corrosion resistance of the carbon support.

  11. A highly stable anode, carbon-free, catalyst support based on tungsten trioxide nanoclusters for proton-exchange membrane fuel cells.

    PubMed

    Dou, Meiling; Hou, Ming; Zhang, Huabing; Li, Guangfu; Lu, Wangting; Wei, Zidong; Shao, Zhigang; Yi, Baolian

    2012-05-01

    Durability is an important issue in proton-exchange membrane fuel cells (PEMFCs). One of the major challenges lies in the degradation caused by the oxidation of the carbon support under high anode potentials (under fuel starvation conditions). Herein, we report highly stable, carbon-free, WO(3) nanoclusters as catalyst supports. The WO(3) nanoclusters are synthesized through a hard template method and characterized by means of electron microscopy and electrochemical analysis. The electrochemical studies show that the WO(3) nanoclusters have excellent electrochemical stability under a high potential (1.6 V for 10 h) compared to Vulcan XC-72. Pt nanoparticles supported on these nanoclusters exhibit high and stable electrocatalytic activity for the oxidation of hydrogen. The catalyst shows negligible loss in electrochemically active surface area (ECA) after an accelerated durability test, whereas the ECA of the Pt nanoparticles immobilized on conventional carbon decreases significantly after the same oxidation condition. Therefore, Pt/WO(3) could be considered as a promising alternative anode catalyst for PEMFCs.

  12. Platinum group metal-free electrocatalysts: Effects of synthesis on structure and performance in proton-exchange membrane fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Workman, Michael J.; Dzara, Michael; Ngo, Chilan; Pylypenko, Svitlana; Serov, Alexey; McKinney, Sam; Gordon, Jonathan; Atanassov, Plamen; Artyushkova, Kateryna

    2017-04-01

    Development of platinum group metal free catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) requires understanding of the interactions between surface chemistry and performance, both of which are strongly dependent on synthesis conditions. To elucidate these complex relationships, a set of Fe-N-C catalysts derived from the same set of precursor materials is fabricated by varying several key synthetic parameters under controlled conditions. The results of physicochemical characterization are presented and compared with the results of rotating disk electrode (RDE) analysis and fuel cell testing. We find that electrochemical performance is strongly correlated with three key properties related to catalyst composition: concentrations of 1) atomically dispersed Fe species, 2) species in which N is bound to Fe, and 3) surface oxides. Not only are these factors related to performance, these types of chemical species are shown to correlate with each other. This study provides evidence supporting the role of iron coordinated with nitrogen as an active species for the ORR, and offers synthetic pathways to increase the density of atomically dispersed iron species and surface oxides for optimum performance.

  13. New electrocatalysts for unitized regenerative fuel cell: Pt-Ir alloy deposited on the proton exchange membrane surface by impregnation-reduction method.

    PubMed

    Wan, Chieh-Hao; Wu, Chun-Lin; Lin, Meng-Tsun; Shih, Chihhsiong

    2010-07-01

    In this paper, a modified technique to prepare Pt-Ir catalyst layer on the proton exchange membrane (PEM) surface using the impregnation-reduction (IR) method is proposed to improve the electrocatalytic activity as well as the life cycle of the bifunctional oxygen electrode (BOE). The resulted electrocatalysts were characterized by the Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Electron Probe Micro-Analysis (EPMA), and Transmission Electron Microscope (TEM). The electrocatalytic properties of the Pt-Ir layer on PEM surface for the oxygen reduction and water oxidation reactions as well as the life cycle of MEA were investigated. Experimental results showed that the Ir particles were dispersed densely in the platinum layer through the modified IR technique. The atomic ratio of Pt over Ir elements was 9:1, and the resulted thickness of the obtained Pt-Ir catalyst layer was about 1.0 microm. The Pt-Ir catalyst layer was composed of Pt layer doped with Ir nano-particles comprising nano Pt-Ir alloy phase. The large surface area of Ir core with Pt shell particles and the presence of nano Pt-Ir alloy phase led to a higher electrocatalytic activity of BOE. Due to the good binding between the Nafion membrane and the Pt-Ir alloy catalyst, as well as the composite structure of the resulted Pt-Ir, the life cycle of Unitized Regenerative Fuel Cell (URFC) is improved through this novel BOE.

  14. Microscale X-ray tomographic investigation of the interfacial morphology between the catalyst and micro porous layers in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Prass, Sebastian; Hasanpour, Sadegh; Sow, Pradeep Kumar; Phillion, André B.; Mérida, Walter

    2016-07-01

    The interfacial morphology between the catalyst layer (CL) and micro porous layer (MPL) influences the performance of proton exchange membrane fuel cells (PEMFCs). Here we report a direct method to investigate the CL-MPL interfacial morphology of stacked and compressed gas diffusion layer (GDL with MPL)-catalyst coated membrane (CCM) assemblies. The area, origin and dimensions of interfacial gaps are studied with high-resolution X-ray micro computed tomography (X-μCT). The projected gap area (fraction of the CL-MPL interface separated by gaps) is higher for GDL-CCM assemblies with large differences in the surface roughness between CL and MPL but reduces with increasing compression and similarity in roughness. Relatively large continuous gaps are found in proximity to cracks in the MPL. These are hypothesized to form due to the presence of large pores on the surface of the GDL. Smaller gaps are induced by the surface roughness features throughout the CL-MPL interface. By modification of the pore sizes on the GDL surface serving as substrate for the MPL, the number and dimension of MPL crack induced gaps can be manipulated. Moreover, adjusting the CL and MPL surface roughness parameters to achieve similar orders of roughness can improve the surface mating characteristics of these two components.

  15. Ozonated graphene oxide film as a proton-exchange membrane.

    PubMed

    Gao, Wei; Wu, Gang; Janicke, Michael T; Cullen, David A; Mukundan, Rangachary; Baldwin, Jon K; Brosha, Eric L; Galande, Charudatta; Ajayan, Pulickel M; More, Karren L; Dattelbaum, Andrew M; Zelenay, Piotr

    2014-04-01

    Graphene oxide (GO) contains several chemical functional groups that are attached to the graphite basal plane and can be manipulated to tailor GO for specific applications. It is now revealed that the reaction of GO with ozone results in a high level of oxidation, which leads to significantly improved ionic (protonic) conductivity of the GO. Freestanding ozonated GO films were synthesized and used as efficient polymer electrolyte fuel cell membranes. The increase in protonic conductivity of the ozonated GO originates from enhanced proton hopping, which is due to the higher content of oxygenated functional groups in the basal planes and edges of ozonated GO as well as the morphology changes in GO that are caused by ozonation. The results of this study demonstrate that the modification of dispersed GO presents a powerful opportunity for optimizing a nanoscale material for proton-exchange membranes.

  16. Miso Model Identification of Proton Exchange Membrane Fuel Cell (PEM-FC) using Least-Square Method

    NASA Astrophysics Data System (ADS)

    Yusivar, F.; Subiantoro, A.; Aryani, D.; Gunawan, R.; Priambodo, P. S.

    2009-09-01

    This paper presents a dynamic model of Polymer Electrolyte Membrane Fuel Cell (PEM FC) as a MISO system using an identification model. The actual PEMFC system is represented in a non linear mathematical model. By identifying the non linear model with Least Square Method, a linear state space model is generated, with and without compensation vector. Another model is derived from linearization in the operating conditions of PEMFC. The Voltage-Current characteristics of each PEMFC models are generated from simulation results, and are compared. It can be seen that the best model is the linear model with compensation vector, since its characteristic is very similar with the typical characteristic of PEMFC. Its Criterion Function of 0.0142 is the smallest among the other models. The smaller the Criterion Function, the model can represent the actual system more accurate. The resulting model can be used for model-based control system.

  17. Renewable Electricity Generation via Solar-Powered Methanol Reforming: Hybrid Proton Exchange Membrane Fuel Cell Systems Based on Novel Non-Concentrating, Intermediate-Temperature Solar Collectors

    NASA Astrophysics Data System (ADS)

    Real, Daniel J.

    Tremendous research efforts have been conducted studying the capturing and conversion of solar energy. Solar thermal power systems offer a compelling opportunity for renewable energy utilization with high efficiencies and excellent cost-effectiveness. The goal of this work was to design a non-concentrating collector capable of reaching temperatures above 250 °C, use this collector to power methanol steam reforming, and operate a proton exchange membrane (PEM) fuel cell using the generated hydrogen. The study presents the construction and characterization of a non-concentrating, intermediate-temperature, fin-in-tube evacuated solar collector, made of copper and capable of reaching stagnation temperatures of 268.5 °C at 1000 W/m2 irradiance. The collector was used to power methanol steam reforming, including the initial heating and vaporization of liquid reactants and the final heating of the gaseous reactants. A preferential oxidation (PROX) catalyst was used to remove CO from simulated reformate gas, and this product gas was used to operate a PEM fuel cell. The results show 1) that the outlet temperature is not limited by heat transfer from the absorber coating to the heat transfer fluid, but by the amount of solar energy absorbed. This implicates a constant heat flux description of the heat transfer process and allows for the usage of materials with lower thermal conductivity than copper. 2) It is possible to operate a PEM fuel cell from reformate gas if a PROX catalyst is used to remove CO from the gas. 3) The performance of the fuel cell is only slightly decreased (~4%) by CO2 dilution present in the reformate and PROX gas. These results provide a foundation for the first renewable electricity generation via solar-powered methanol reforming through a hybrid PEM fuel cell system based on novel non-concentrating, intermediate-temperature solar collectors.

  18. AC impedance modelling study on porous electrodes of proton exchange membrane fuel cells using an agglomerate model

    NASA Astrophysics Data System (ADS)

    Gerteisen, Dietmar; Hakenjos, Alex; Schumacher, Jürgen O.

    A one-dimensional model of the PEM fuel cell cathode is developed to analyse ac impedance spectra and polarisation curves. The porous gas diffusion electrode is assumed to consist of a network of dispersed catalyst (Pt/C) forming spherically shaped agglomerated zones that are filled with electrolyte. The coupled differential equation system describes: ternary gas diffusion in the backing (O2 , N2 , water vapour), Fickian diffusion and Tafel kinetics for the oxygen reduction reaction (ORR) inside the agglomerates, proton migration with ohmic losses and double-layer charging in the electrode. Measurements are made of a temperature-controlled fuel cell with a geometric area of 1.4 cm × 1.4 cm. Lateral homogeneity is ensured by using a high stoichiometry of λmin . The model predicts the behaviour of measured polarisation curves and impedance spectra. It is found that a better humidification of the electrode leads to a higher volumetric double-layer capacity. The catalyst layer resistance shows the same behaviour depending on the humidification as the membrane resistance. Model parameters, e.g. Tafel slope, ionic resistance and agglomerate radius are varied. A sensitivity analysis of the model parameters is conducted.

  19. Synthesizing 2D MoS2 Nanofins on carbon nanospheres as catalyst support for Proton Exchange Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Hu, Yan; Chua, Daniel H. C.

    2016-06-01

    Highly dense 2D MoS2 fin-like nanostructures on carbon nanospheres were fabricated and formed the main catalyst support structure in the oxygen reduction reaction (ORR) for polymer electrolyte membrane (PEM) fuel cells. These nanofins were observed growing perpendicular to the carbon nanosphere surface in random orientations and high resolution transmission electron microscope confirmed 2D layers. The PEM fuel cell test showed enhanced electrochemical activity with good stability, generating over 8.5 W.mgPt-1 as compared to standard carbon black of 7.4 W.mgPt-1 under normal operating conditions. Electrochemical Impedance Spectroscopy confirmed that the performance improvement is highly due to the excellent water management of the MoS2 lamellar network, which facilitates water retention at low current density and flood prevention at high current density. Reliability test further demonstrated that these nanofins are highly stable in the electrochemical reaction and is an excellent ORR catalyst support.

  20. Synthesizing 2D MoS2 Nanofins on carbon nanospheres as catalyst support for Proton Exchange Membrane Fuel Cells

    PubMed Central

    Hu, Yan; Chua, Daniel H. C.

    2016-01-01

    Highly dense 2D MoS2 fin-like nanostructures on carbon nanospheres were fabricated and formed the main catalyst support structure in the oxygen reduction reaction (ORR) for polymer electrolyte membrane (PEM) fuel cells. These nanofins were observed growing perpendicular to the carbon nanosphere surface in random orientations and high resolution transmission electron microscope confirmed 2D layers. The PEM fuel cell test showed enhanced electrochemical activity with good stability, generating over 8.5 W.mgPt−1 as compared to standard carbon black of 7.4 W.mgPt−1 under normal operating conditions. Electrochemical Impedance Spectroscopy confirmed that the performance improvement is highly due to the excellent water management of the MoS2 lamellar network, which facilitates water retention at low current density and flood prevention at high current density. Reliability test further demonstrated that these nanofins are highly stable in the electrochemical reaction and is an excellent ORR catalyst support. PMID:27302135

  1. Enhancement of the fuel cell performance of a high temperature proton exchange membrane fuel cell running with titanium composite polybenzimidazole-based membranes

    NASA Astrophysics Data System (ADS)

    Lobato, Justo; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Pinar, F. Javier

    2011-10-01

    The fuel cell performance of a composite PBI-based membrane with TiO2 has been studied. The behaviour of the membrane has been evaluated by comparison with the fuel cell performance of other PBI-based membranes, all of which were cast from the same polymer with the same molecular weight. The PBI composite membrane incorporating TiO2 showed the best performance and reached 1000 mW cm-2 at 175 °C. Moreover, this new titanium composite PBI-based membrane also showed the best stability during the preliminary long-term test under our operation conditions. Thus, the slope of the increase in the ohmic resistance of the composite membrane was 0.041 mΩ cm2 h-1 and this is five times lower than that of the standard PBI membrane. The increased stability was due to the high phosphoric acid retention capacity - as confirmed during leaching tests, in which the Ti-based composite PBI membrane retained 5 mol of H3PO4/PBI r.u. whereas the PBI standard membrane only retained 1 mol H3PO4/PBI r.u. Taking into account the results obtained in this study, the TiO2-PBI based membranes are good candidates as electrolytes for high temperature PEMFCs.

  2. Efficiency measurement and uncertainty discussion of an electric engine powered by a ``self-breathing'' and ``self-humidified'' proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Schiavetti, Pierluigi; Del Prete, Zaccaria

    2007-08-01

    The efficiency of an automotive engine based on a "self-breathing" and "self-humidified" proton exchange membrane fuel cell stack (PEM FC) connected to a dc brushless electrical motor was measured under variable power load conditions. Experiments have been carried out on a small scale 150W engine model. After determining the fuel cell static polarization curve and the time response to power steps, the system was driven to copy on the test bench a "standard urban load cycle" and its instantaneous efficiencies were measured at an acquisition rate of 5Hz. The integral system efficiency over the entire urban load cycle, comprising the losses of the unavoidable auxiliary components of the engine, was then calculated. The fuel cell stack was operated mainly in "partial" dead-end mode, with a periodic anode flow channel purging, and one test was carried out in "pure" dead-end mode, with no anode channel purging. An uncertainty analysis of the efficiencies was carried out, taking into account either type A and type B evaluation methods, strengthening the discussion about the outcomes obtained for a system based on this novel simplified FC type. For our small scale engine we measured over the standard urban cycle, on the basis of the H2 high heating value (HHV), a tank-to-wheel integral efficiency of (18.2±0.8)%, when the fuel cell was operated with periodic flow channel purging, and of (21.5±1.3)% in complete dead-end operation mode.

  3. Electroless Ni-Cu-P/nano-graphite composite coatings for bipolar plates of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lee, Cheng-Kuo

    2012-12-01

    This study evaluates the effects of an electroless Ni-Cu-P/nano-graphite composite coating on the surface characteristics of anodized 5083 aluminum alloy, including electrical resistivity, corrosion resistance of the alloy in a simulated solution of 0.5 M H2SO4 + 2 ppm NaF in polymer electrolyte membrane fuel cells (PEMFCs). The co-deposition and adhesion of the composite coatings on a 5083 substrate are enhanced by an anodizing process. The electroless Ni-Cu-P plating solution is prepared by adding different CuSO4·5H2O concentrations into the electroless Ni-P plating solution and adding nano-graphite (15-40 nm) particles to form the Ni-Cu-P/nano-graphite composite coatings. Experimental results indicate that the electroless Ni-Cu-P/nano-graphite composite coating enhances the hardness, conductivity, corrosion resistance of the 5083 substrate in the corrosive solution. The anodizing treatment enhances the electroless composite coatings by providing better uniformity, density, and adhesion compared to substrate without anodizing treatment. The electroless Ni-Cu-P/nano-graphite composite coating deposited on the optimal anodized 5083 substrate at a low CuSO4·5H2O concentration of 0.25 g l-1 with 20 g l-1 nano-graphite added have the best surface structure, highest hardness, electrical conductivity and corrosion resistance. Therefore, this novel electroless Ni-Cu-P/nano-graphite composite-coated 5083 aluminum alloy has potential applications in bipolar plates of PEM fuel cells.

  4. Electricity generation using an air-cathode single chamber microbial fuel cell in the presence and absence of a proton exchange membrane.

    PubMed

    Liu, Hong; Logan, Bruce E

    2004-07-15

    Microbial fuel cells (MFCs) are typically designed as a two-chamber system with the bacteria in the anode chamber separated from the cathode chamber by a polymeric proton exchange membrane (PEM). Most MFCs use aqueous cathodes where water is bubbled with air to provide dissolved oxygen to electrode. To increase energy output and reduce the cost of MFCs, we examined power generation in an air-cathode MFC containing carbon electrodes in the presence and absence of a polymeric proton exchange membrane (PEM). Bacteria present in domestic wastewater were used as the biocatalyst, and glucose and wastewater were tested as substrates. Power density was found to be much greater than typically reported for aqueous-cathode MFCs, reaching a maximum of 262 +/- 10 mW/m2 (6.6 +/- 0.3 mW/L; liquid volume) using glucose. Removing the PEM increased the maximum power density to 494 +/- 21 mW/m2 (12.5 +/- 0.5 mW/L). Coulombic efficiency was 40-55% with the PEM and 9-12% with the PEM removed, indicating substantial oxygen diffusion into the anode chamber in the absence of the PEM. Power output increased with glucose concentration according to saturation-type kinetics, with a half saturation constant of 79 mg/L with the PEM-MFC and 103 mg/L in the MFC without a PEM (1000 omega resistor). Similar results on the effect of the PEM on power density were found using wastewater, where 28 +/- 3 mW/m2 (0.7 +/- 0.1 mW/L) (28% Coulombic efficiency) was produced with the PEM, and 146 +/- 8 mW/m2 (3.7 +/- 0.2 mW/L) (20% Coulombic efficiency) was produced when the PEM was removed. The increase in power output when a PEM was removed was attributed to a higher cathode potential as shown by an increase in the open circuit potential. An analysis based on available anode surface area and maximum bacterial growth rates suggests that mediatorless MFCs may have an upper order-of-magnitude limit in power density of 10(3) mW/m2. A cost-effective approach to achieving power densities in this range will likely

  5. Study of the acetonitrile poisoning of platinum cathodes on proton exchange membrane fuel cell spatial performance using a segmented cell system

    NASA Astrophysics Data System (ADS)

    Reshetenko, Tatyana V.; St-Pierre, Jean

    2015-10-01

    Due to the wide applications of acetonitrile as a solvent in the chemical industry, acetonitrile can be present in the air and should be considered a possible pollutant. In this work, the spatial proton exchange membrane fuel cell performance exposed to air with 20 ppm CH3CN was studied using a segmented cell system. The injection of CH3CN led to performance losses of 380 mV at 0.2 A cm-2 and 290 mV at 1.0 A cm-2 accompanied by a significant change in the current density distribution. The observed local currents behavior is likely attributed to acetonitrile chemisorption and the subsequent two consecutive reduction/oxidation reactions. The hydrolysis of CH3CN and its intermediate imine species resulted in NH4+ formation, which increased the high-frequency resistance of the cell and affected oxygen reduction and performance. Other products of hydrolysis can be oxidized to CO2 under the operating conditions. The reintroduction of pure air completely recovered cell performance within 4 h at 1.0 A cm-2, while at 0.2 A cm-2 the cell recovery was only partial. A detailed analysis of the current density distribution, its correlation with spatial electrochemical impedance spectroscopy data, possible CH3CN oxidation/reduction mechanisms and mitigation strategies are presented and discussed.

  6. Multilayered Zr-C/a-C film on stainless steel 316L as bipolar plates for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Bi, Feifei; Peng, Linfa; Yi, Peiyun; Lai, Xinmin

    2016-05-01

    A multilayered zirconium-carbon/amorphous carbon (Zr-C/a-C) coating is synthesized by magnetron sputtering in order to improve the corrosion resistance and interfacial conductivity of stainless steel 316L (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). Zr-C/a-C film contains an outmost pure amorphous carbon layer and a sub zirconium containing carbon layer. Interfacial contact resistance (ICR) between carbon paper and coated SS316L decreases to 3.63 mΩ cm2 at 1.4 MPa. Potentiodynamic polarization results reveal that the corrosion potential of Zr-C/a-C coated sample is more positive than pure a-C coated sample and the current density is only 0.49 μA cm-2 at the cathode applied potential 0.6 V. Electrochemical impendence spectroscopy also indicates that multilayered Zr-C/a-C film coated SS316L has much higher charge transfer resistance than the bare sample. After potentiostatic polarization, ICR values are 3.92 mΩ cm2 and 3.82 mΩ cm2 in the simulated PEMFCs cathode and anode environment, respectively. Moreover, XPS analysis of the coated samples before and after potential holding tests shows little difference, which disclose the chemical stability of multilayered Zr-C/a-C film. Therefore, the multilayered Zr-C/a-C coating exhibits excellent performance in various aspects and is preferred for the application of stainless steel bipolar plates.

  7. Effects of passive films on corrosion resistance of uncoated SS316L bipolar plates for proton exchange membrane fuel cell application

    NASA Astrophysics Data System (ADS)

    Yang, Ying; Ning, Xiaohui; Tang, Hongsheng; Guo, Liejin; Liu, Hongtan

    2014-11-01

    The effects of passive films on the corrosion behaviors of uncoated SS316L in anode and cathode environments of proton exchange membrane fuel cells (PEMFCs) are studied. Potentiodynamic and potentiostatic polarizations are employed to study the corrosion behavior; Mott-Schottky measurements are used to characterize the semiconductor properties of passive films; X-ray photoelectron spectroscopy (XPS) analyses are used to identify the compositions and the depth profiles of passive films. The passive films formed in the PEMFC anode and cathode environments under corresponding conditions both behave as n-type semiconductor. The passive film formed in the anode environment has a single-layer structure, Cr is the major element (Cr/Fe atomic ratio > 1), and the Cr/Fe atomic ratio decreases from the surface to the bulk; while the passive film formed in the PEMFC cathode environment has a bi-layer structure, Fe is the major element (Cr/Fe atomic ratio < 0.5), and in the external layer of the bi-layer structure Fe content increases rapidly and gradually in the internal layer. SS316L shows better corrosion resistance owing to both the high content of Cr oxide in the passive film and low band bending in normal PEMFC anode environments.

  8. Gas-liquid two-phase flow behaviors and performance characteristics of proton exchange membrane fuel cells in a short-term microgravity environment

    NASA Astrophysics Data System (ADS)

    Guo, Hang; Liu, Xuan; Zhao, Jian Fu; Ye, Fang; Ma, Chong Fang

    2017-06-01

    In this work, proton exchange membrane fuel cells (PEMFCs) with transparent windows are designed to study the gas-liquid two-phase flow behaviors inside flow channels and the performance of a PEMFC with vertical channels and a PEMFC with horizontal channels in a normal gravity environment and a 3.6 s short-term microgravity environment. Experiments are conducted under high external circuit load and low external circuit load at low temperature where is 35 °C. The results of the present experimental work demonstrate that the performance and the gas-liquid two-phase flow behaviors of the PEMFC with vertical channels exhibits obvious changes when the PEMFCs enter the 3.6 s short-term microgravity environment from the normal gravity environment. Meanwhile, the performance of the PEMFC with vertical channels increases after the PEMFC enters the 3.6 s short-term microgravity environment under high external circuit load, while under low external circuit load, the PEMFC with horizontal channels exhibits better performance in both the normal gravity environment and the 3.6 s short-term microgravity environment.

  9. Electrochemical behavior of nanocrystalline Ta/TaN multilayer on 316L stainless steel: Novel bipolar plates for proton exchange membrane fuel-cells

    NASA Astrophysics Data System (ADS)

    Alishahi, M.; Mahboubi, F.; Mousavi Khoie, S. M.; Aparicio, M.; Hübner, R.; Soldera, F.; Gago, R.

    2016-08-01

    Insufficient corrosion resistance and surface conductivity are two main issues that plague large-scale application of stainless steel (SS) bipolar plates in proton exchange membrane fuel cells (PEMFCs). This study explores the use of nanocrystalline Ta/TaN multilayer coatings to improve the electrical and electrochemical performance of polished 316L SS bipolar plates. The multilayer coatings have been deposited by (reactive) magnetron sputtering and characterized by X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy. The electrochemical behavior of bare and coated substrates has been evaluated in simulated PEMFC working environments by potentiodynamic and potentiostatic polarization tests at ambient temperature and 80 °C. The results show that the Ta/TaN multilayer coating increases the polarization resistance of 316L SS by about 30 and 104 times at ambient and elevated temperatures, respectively. The interfacial contact resistance (ICR) shows a low value of 12 mΩ × cm2 before the potentiostatic test. This ICR is significantly lower than for the bare substrate and remains mostly unchanged after potentiostatic polarization for 14 h. In addition, the high contact angle (92°) with water for coated substrates indicates a hydrophobic character, which can improve the water management within the cell in PEMFC stacks.

  10. High surface area synthesis, electrochemical activity, and stability of tungsten carbide supported Pt during oxygen reduction in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Chhina, H.; Campbell, S.; Kesler, O.

    The oxidation of carbon catalyst supports to carbon dioxide gas leads to degradation in catalyst performance over time in proton exchange membrane fuel cells (PEMFCs). The electrochemical stability of Pt supported on tungsten carbide has been evaluated on a carbon-based gas diffusion layer (GDL) at 80 °C and compared to that of HiSpec 4000™ Pt/Vulcan XC-72R in 0.5 M H 2SO 4. Due to other electrochemical processes occurring on the GDL, detailed studies were also performed on a gold mesh substrate. The oxygen reduction reaction (ORR) activity was measured both before and after accelerated oxidation cycles between +0.6 V and +1.8 V vs. RHE. Tafel plots show that the ORR activity remained high even after accelerated oxidation tests for Pt/tungsten carbide, while the ORR activity was extremely poor after accelerated oxidation tests for HiSpec 4000™. In order to make high surface area tungsten carbide, three synthesis routes were investigated. Magnetron sputtering of tungsten on carbon was found to be the most promising route, but needs further optimization.

  11. Electrodeposited conductive polypyrrole/polyaniline composite film for the corrosion protection of copper bipolar plates in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Pan, T. J.; Zuo, X. W.; Wang, T.; Hu, J.; Chen, Z. D.; Ren, Y. J.

    2016-01-01

    A conductive composite coating consisting of an inner polypyrrole (PPY) layer and an outer polyaniline (PANI) layer is prepared on a copper substrate by an electrochemical synthesis. Potential application of these composite coatings in a proton exchange membrane fuel cell (PEMFC) is evaluated. The corrosion performance of the copper substrate without and with the polymer coatings in the acidic solutions containing H2SO4 (0.2 M), HCl (0.1 M) and HF (3 ppm) is investigated by electrochemical impedance spectroscopy, polarization and open-circuit potential measurements. The results indicate that both the bilayered PPY/PANI and the single PPY coating can increase the corrosion potential of copper substrate by more than 250 mV (SCE), and effectively decrease the corrosion current density by an order of magnitude in comparison with the uncoated copper substrate. Long-term test further confirms that the bilayered PPY/PANI coating with acceptable contact resistance provides better protection for the substrate than the single PPY coating. The bilayered structure with different ion-permselective nature may serve as an effective physical barrier to the inward penetration of corrosive species.

  12. An investigation on corrosion protection of chromium nitride coated Fe-Cr alloy as a bipolar plate material for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Pan, T. J.; Zhang, B.; Li, J.; He, Y. X.; Lin, F.

    2014-12-01

    The corrosion properties of chromium nitride (CrN) coating are investigated to assess the potential use of this material as a bipolar plate for proton exchange membrane fuel cells (PEMFCs). Conductive metallic ceramic CrN layers are firstly deposited onto Fe-Cr alloy using a multi-arc ion plating technique to increase the corrosion resistance of the base alloy. Electrochemical measurements indicate that the corrosion resistance of the substrate alloy is greatly enhanced by the CrN coating. The free corrosion potential of the substrate is increased by more than 50 mV. Furthermore, a decrease in three orders of magnitude of corrosive current density for the CrN-coated alloy is observed compared to the as-received Fe-Cr alloy. Long-term immersion tests show that the CrN layer is highly stable and effectively acts as a barrier to inhibit permeation of corrosive species. On the contrary, corrosion of the Fe-Cr alloy is rather severe without the protection of CrN coating due to the active dissolution. Finally, the corresponding electrochemical impedance models are proposed to elucidate the corrosion process of the CrN/Fe-Cr alloy submerged in a simulated PEMFCs environment.

  13. Insights into the role of wettability in cathode catalyst layer of proton exchange membrane fuel cell; pore scale immiscible flow and transport processes

    NASA Astrophysics Data System (ADS)

    Fathi, H.; Raoof, A.; Mansouri, S. H.

    2017-05-01

    The production of liquid water in cathode catalyst layer, CCL, is a significant barrier to increase the efficiency of proton exchange membrane fuel cell. Here we present, for the first time, a direct three-dimensional pore-scale modelling to look at the complex immiscible two-phase flow in CCL. After production of the liquid water at the surface of CCL agglomerates due to the electrochemical reactions, water spatial distribution affects transport of oxygen through the CCL as well as the rate of reaction at the agglomerate surfaces. To explore the wettability effects, we apply hydrophilic and hydrophobic properties using different surface contact angles. Effective diffusivity is calculated under several water saturation levels. Results indicate larger diffusive transport values for hydrophilic domain compared to the hydrophobic media where the liquid water preferentially floods the larger pores. However, hydrophobic domain showed more available surface area and higher oxygen consumption rate at the reaction sites under various saturation levels, which is explained by the effect of wettability on pore-scale distribution of water. Hydrophobic domain, with a contact angle of 150, reveals efficient water removal where only 28% of the pore space stays saturated. This condition contributes to the enhanced available reaction surface area and oxygen diffusivity.

  14. Synthesis and structure-activity relationship exploration of carbon-supported PtRuNi nanocomposite as a CO-tolerant electrocatalyst for proton exchange membrane fuel cells.

    PubMed

    Liang, Yongmin; Zhang, Huamin; Tian, Zhiqun; Zhu, Xiaobing; Wang, Xiaoli; Yi, Baolian

    2006-04-20

    A carbon-supported PtRuNi nanocomposite is synthesized via a microwave-irradiated polyol plus annealing synthesis strategy. The catalyst is characterized by transmission electron microscopy, powder X-ray diffraction, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The data are discussed with respect to those for the carbon-supported PtRu nanocomposite prepared following the same way. The characterizations show that the inclusion of Ni in the PtRu system has only a small effect on the particle size, the structure, and the compositional homogeneity. CO-stripping voltammetry and measurements on the single proton exchange membrane fuel cells show that the PtRuNi/C catalyst has an improved activity for CO(ads) electro-oxidation. An accelerated durability test on the catalyst exhibits insignificant loss of activity in acidic media. On the basis of the exploration of the structure-activity relationship, a mechanism for the improved performance of the catalyst is proposed. It is suggested that the improved CO-tolerant performance of the PtRuNi/C nanocomposite should be related to the hydrogen spillover on the catalyst surface, the enhanced oxidation of CO(ads) by nickel hydroxides, and the high proton and electronic conductivity of the hydroxides. The nickel hydroxide passivated surface and/or anchoring of metallic nickel in the platinum lattice may contribute to the durability of the catalyst in acid solution.

  15. Synthesis of platinum-polyaniline composite, its evaluation as a performance boosting interphase in the electrode assembly of proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Jayasree, R.; Mohanraju, K.; Cindrella, L.

    2013-01-01

    Platinum formed on polyaniline (PANi) is used as the interlayer between porous gas diffusion layer and the catalyst layer with the aim to reduce the thickness of the ordinary gas diffusion layer and provide a performance boosting electrostatic layer. The doping tendency of PANi is utilized to incorporate platinum(IV) ion in its matrix by chemisorption followed by its reduction to metallic platinum. Platinum is deposited on polyaniline by a simple wet chemistry method. PANi is prepared by the chemical oxidative polymerization of aniline by ammonium persulphate while Pt deposition on PANi is achieved by a phase transfer method (water-toluene) to yield Pt nanoparticles on PANi. The composite is characterized by XRD, Scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), IR spectroscopy, cyclic voltammetry (CV), AC impedance studies, density and conductivity measurements. The Pt/PANi composite is assessed in the proton exchange membrane fuel cell (PEMFC) using H2/O2 gases at ambient pressure. The performance of the PEMFC with Pt/PANi composite interphase on cathode side of the gas diffusion layer (GDL) shows improvement at high current densities which is attributed to the increased capacitative current of Pt/PANi layer in the presence of O2 thereby improving the kinetics of subsequent reduction of O2.

  16. A review of the stability and durability of non-precious metal catalysts for the oxygen reduction reaction in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Banham, Dustin; Ye, Siyu; Pei, Katie; Ozaki, Jun-ichi; Kishimoto, Takeaki; Imashiro, Yasuo

    2015-07-01

    A major hurdle to the widespread commercialization of proton exchange membrane fuel cells (PEMFCs) is the high loading of noble metal (Pt/Pt-alloy) catalyst at the cathode, which is necessary to facilitate the inherently sluggish oxygen reduction reaction (ORR). To eliminate the use of Pt/Pt-alloy catalysts at the cathode of PEMFCs and thus significantly reduce the cost, extensive research on non-precious metal catalysts (NPMCs) has been carried out over the past decade. Major advances in improving the ORR activity of NPMCs, particularly Fe- and Co-based NPMCs, have elevated these materials to a level at which they can start to be considered as potential alternatives to Pt/Pt-alloy catalysts. Unfortunately, the stability (performance loss following galvanostatic experiments) of these materials is currently unacceptably low and the durability (performance loss following voltage cycling) remains uncertain. The three primary mechanisms of instability are: (a) Leaching of the metal site, (b) Oxidative attack by H2O2, and (c) Protonation followed by possible anion adsorption of the active site. While (a) has largely been solved, further work is required to understand and prevent losses from (b) and/or (c). Thus, this review is focused on historical progress in (and possible future strategies for) improving the stability/durability of NPMCs.

  17. A study on novel pulse preparation and electrocatalytic activities of Pt/C-Nafion electrodes for proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Ye, Feng; Chen, Ling; Wang, Tongtao; Li, Jianling; Wang, Xindong

    To aim at reducing the platinum loading and increasing the utilization of platinum in PEMFC electrode, a new pulse electrodeposition technique for preparing proton exchange membrane fuel cell (PEMFC) electrodes has been developed in this paper. This method combines coating Pt seeds on the C-Nafion substrate and introducing polyethylene glycol (PEG) into the deposition solution. SEM images of the samples show that Pt seeds and PEG take an important role in the morphology of the Pt deposit. The surface area and average particle size of Pt were determined by charge integration under the hydrogen desorption peaks of cyclic voltammetry. The electrocatalytic activities of these electrodes towards oxygen reduction reaction (ORR) were investigated by using rotating disc electrode (RDE). The Pt catalyst which was prepared by Pt seeds and PEG, its active surface area and electrocatalytic activity towards ORR were improved remarkably. And the optimized electrode displayed higher catalytic activity than a conventional electrode made from commercial Pt/C catalyst. The possible reasons for the effects of Pt seeds and PEG on the higher catalytic activity of prepared Pt catalysts have been preliminarily discussed.

  18. Reduction of hydrogen peroxide production at anode of proton exchange membrane fuel cell under open-circuit conditions using ruthenium-carbon catalyst

    NASA Astrophysics Data System (ADS)

    Jung, Un Ho; Jeong, Seong Uk; Chun, Kook; Park, Ki Tae; Lee, Hyang Mee; Choi, Dong Woong; Kim, Sung Hyun

    This study examines the effect of hydrogen peroxide (H 2O 2) on the open-circuit voltage (OCV) of a proton exchange membrane fuel cell (PEMFC) and the reduction of H 2O 2 in the membrane using a ruthenium/carbon catalyst (Ru/C) at the anode. Each cathode and anode potential of the PEMFC in the presence of H 2O 2 is examined by constructing a half-cell using 1.0 M H 2SO 4 solution as an electrolyte and Ag/AgCl as the reference electrode. H 2O 2 is added to the H 2SO 4 solution and the half-cell potential is measured at each H 2O 2 concentration. The cathode potential is affected by the H 2O 2 concentration while the anode potential remains stable. A Ru catalyst is used to reduce the level of H 2O 2 formation through O 2 cross-over at the interface of a membrane and the anode. The Ru catalyst is known to produce less H 2O 2 through oxygen reduction at the anode of PEMFC than a Pt catalyst. A Ru/C layer is placed between the Nafion ® 112 membrane and anode catalyst layer and the cell voltage under open-circuit condition is measured. A single cell is constructed to compare the OCV of the Pt/C only anode with that of the Ru/C-layered anode. The level of hydrogen cross-over and the OCV are determined after operation at a current density of 1 A cm -2 for 10 h and stabilization at open-circuit for 1 h to obtain an equilibrium state in the cell. Although there is an increase in the OCV of the cell with the Ru/C layer at the anode, excessive addition of Ru/C has an adverse effect on cell performance.

  19. Towards developing a backing layer for proton exchange membrane electrolyzers

    NASA Astrophysics Data System (ADS)

    Lettenmeier, P.; Kolb, S.; Burggraf, F.; Gago, A. S.; Friedrich, K. A.

    2016-04-01

    Current energy policies require the urgent replacement of fossil energy carriers by carbon neutral ones, such as hydrogen. The backing or micro-porous layer plays an important role in the performance of hydrogen proton exchange membrane (PEM) fuel cells, reducing contact resistance and improving reactant/product management. Such carbon-based coating cannot be used in PEM electrolysis since it oxidizes to CO2 at high voltages. A functional titanium macro-porous layer (MPL) on the current collectors of a PEM electrolyzer is developed by thermal spraying. It improves the contact with the catalyst layers by ca. 20 mΩ cm2, increasing significantly the efficiency of the device when operating at high current densities.

  20. High throughput study of fuel cell proton exchange membranes: Poly(vinylidene fluoride)/acrylic polyelectrolyte blends and nanocomposites with zirconium

    NASA Astrophysics Data System (ADS)

    Zapata B., Pedro Jose

    Sustainability is perhaps one of the most heard buzzwords in the post-20 th century society; nevertheless, it is not without a reason. Our present practices for energy supply are largely unsustainable if we consider their environmental and social impact. In view of this unfavorable panorama, alternative sustainable energy sources and conversion approaches have acquired noteworthy significance in recent years. Among these, proton exchange membrane fuel cells (PEMFCs) are being considered as a pivotal building block in the transition towards a sustainable energy economy in the 21st century. The polyelectrolyte membrane or proton exchange membrane (PEM) is a vital component, as well as a performance-limiting factor, of the PEMFC. Consequently, the development of high-performance PEM materials is of utmost importance for the advance of the PEMFC field. In this work, alternative PEM materials based on semi-interpenetrated networks from blends of poly(vinyledene fluoride) (PVDF) (inert phase) and sulfonated crosslinked acrylic polyelectrolytes (PE) (proton-conducting phase), as well as tri-phase PVDF/PE/zirconium-based composites, are studied. To alleviate the burden resulting from the vast number of possible combinations of the different precursors utilized in the preparation of the membranes (PVDF: 5x, PE: 2x, Nanoparticle: 3x), custom high-throughput (HT) screening systems have been developed for their characterization. By coupling the data spaces obtained via these systems with the appropriate statistical and data analysis tools it was found that, despite not being directly involved in the proton transport process, the inert PVDF phase plays a major role on proton conductivity. Particularly, a univocal inverse correlation between the PVDF crystalline characteristics (i.e., crystallinity and crystallite size) and melt viscosity, and membrane proton conductivity was discovered. Membranes based on highly crystalline and viscous PVDF homopolymers exhibited reduced proton

  1. Method of fabricating electrode catalyst layers with directionally oriented carbon support for proton exchange membrane fuel cell

    DOEpatents

    Liu, Di-Jia [Naperville, IL; Yang, Junbing [Bolingbrook, IL

    2012-03-20

    A membrane electrode assembly (MEA) of the invention comprises an anode and a cathode and a proton conductive membrane therebetween, the anode and the cathode each comprising a patterned sheet of longitudinally aligned transition metal-containing carbon nanotubes, wherein the carbon nanotubes are in contact with and are aligned generally perpendicular to the membrane, wherein a catalytically active transition metal is incorporated throughout the nanotubes.

  2. Lamellar crystals as proton conductors to enhance the performance of proton exchange membrane for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Zhao, Yuning; Jiang, Zhongyi; Xiao, Lulu; Xu, Tao; Wu, Hong

    2011-08-01

    Zirconium glyphosate (ZrG) is a solid proton conductor with layered crystal structure. The inorganic veneer sheets of ZrG are covalently intercalated by glyphosate molecules with carboxylic acid end groups (-COOH). The existence of abundant -COOH groups both inside and on the surface of ZrG provides additional proton-conducting channels facilitating the proton conduction through and around the inorganic crystals. ZrG is incorporated into the sulfonated polyether ether ketone (SPEEK) matrices to prepare proton-conducting hybrid membranes. The conductivity of the hybrid membranes is higher than the pristine SPEEK membrane, and increases with increasing ZrG content. Furthermore, the enhancement of the proton conductivity is more obvious at elevated temperatures. At 25 °C, the proton conductivity of the hybrid membrane with 16 wt% ZrG is 1.4 times higher than that of the pristine membrane. When the temperature increases to 55 °C, the conductivity of the hybrid membrane with 8 wt% ZrG is more than twice that of the pristine SPEEK membrane. The prolonged and tortuous pathways originated from the incorporation of inorganic crystals lead to reduced methanol permeability. The selectivity of the hybrid membrane is increased by as much as 72% compared to the pristine SPEEK membrane.

  3. Heterogeneous Electrocatalyst of Palladium-Cobalt-Phosphorus on Carbon Support for Oxygen Reduction Reaction in High Temperature Proton Exchange Membrane Fuel Cells.

    PubMed

    You, Dae Jong; Pak, Chanho; Jin, Seon-Ah; Lee, Kang Hee; Kwon, Kyungjung; Choi, Kyoung Hwan; Heo, Pil Won; Jang, Hongchul; Kim, Jun Young; Kim, Ji Man

    2016-05-01

    Palladium-cobalt-phosphorus (PdCoP) catalysts supported on carbon (Ketjen Black) were investigated as a cathode catalyst for oxygen reduction reaction (ORR) in high temperature proton exchange membrane fuel cells (HT-PEMFCs). The PdCoP catalyst was synthesized via a modified polyol process in teflon-sealed reactor by microwave-heating. From X-ray diffraction and transmission electron microscopic analysis, the PdCoP catalyst exhibits a face-centered cubic structure, similar to palladium (Pd), which is attributed to form a good solid solution of Co atoms and P atoms in the Pd lattice. The PdCoP nanoparticles with average diameter of 2.3 nm were uniformly distributed on the carbon support. The electrochemical surface area (ECSA) and ORR activity of PdP, PdCo and PdCoP catalysts were measured using a rotating disk electrode technique with cyclic voltammetry and the linear sweep method. The PdCoP catalysts showed the highest performances for ECSA and ORR, which might be attributed both to formation of small nanoparticle by phosphorus atom and to change in lattice constant of Pd by cobalt atom. Furthermore, The HT-PEMFCs single cell performance employing PdCoP catalyst exhibited an enhanced cell performance compared to a single cell using the PdP and PdCo catalysts. This result indicates the importance of electric and geometric control of Pd alloy nanoparticles that can improve the catalytic activity. This synergistic combination of Co and P with Pd could provide the direction of development of non-Pt catalyst for fuel cell system.

  4. Research and development of Proton-Exchange Membrane (PEM) fuel cell system for transportation applications: Initial conceptual design report

    NASA Astrophysics Data System (ADS)

    1993-11-01

    This report addresses Task 1.1, model development and application, and Task 1.2, vehicle mission definition. Overall intent is to produce a methanol-fueled 10-kW power source and to evaluate electrochemical engine (ECE) use in transportation. Major achievements include development of an ECE power source model and its integration into a comprehensive power source/electric vehicle propulsion model, establishment of candidate FCV (fuel cell powered electric vehicle) mission requirements, initial FCV studies, and a candidate FCV recommendation for further study.

  5. Research and Development of Proton-Exchange Membrane (PEM) Fuel Cell System for Transportation Applications: Initial Conceptual Design Report

    SciTech Connect

    Not Available

    1993-11-30

    This report addresses Task 1.1, model development and application, and Task 1.2, vehicle mission definition. Overall intent is to produce a methanol-fueled 10-kW power source, and to evaluate electrochemical engine (ECE) use in transportation. Major achievements include development of an ECE power source model and its integration into a comprehensive power source/electric vehicle propulsion model, establishment of candidate FCV (fuel cell powered electric vehicle) mission requirements, initial FCV studies, and a candidate FCV recommendation for further study.

  6. DOD Residential Proton Exchange Membrane (PEM) Fuel Cell Demonstration Program. Volume 1. Summary of the Fiscal Year 2001 Program

    DTIC Science & Technology

    2004-02-01

    de- tailed special provisions concerning patent rights, rights in technical data and computer software, reporting requirements, equal employment...Fuel Cells (860) 673-9181 Revised draft of the technical report is in the review process. ERDC/CERL TR-04-3 43 IEC TC105 Working Group 2...Champaign, IL 61826-9005 Final Report Approved for public release; distribution is unlimited. Prepared for U.S. Army Corps of Engineers Washington

  7. DOD Residential Proton Exchange Membrane (PEM) Fuel Cell Demonstration Program. Volume 2. Summary of Fiscal Year 2001-2003 Projects

    DTIC Science & Technology

    2005-09-01

    the grid was without power based on Central Power Plant data—while a fuel cell or other distributed generation device may be feeding electricity...they are willing to perform the demonstration at. States and specific cities may be identified, if applicable. Geographic regions from the...pre-proposal, at a mini- mum, the geographic region(s) they are willing to perform the demonstration at. States and specific cities may be identified

  8. Development of high performance carbon composite catalyst for oxygen reduction reaction in PEM Proton Exchange Membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Nallathambi, Vijayadurga; Lee, Jong-Won; Kumaraguru, Swaminatha P.; Wu, Gang; Popov, Branko N.

    Highly active and stable carbon composite catalysts for oxygen reduction in PEM fuel cells were developed through the high-temperature pyrolysis of Co-Fe-N chelate complex, followed by the chemical post-treatment. A metal-free carbon catalyst was used as the support. The carbon composite catalyst showed an onset potential for oxygen reduction as high as 0.87 V (NHE) in H 2SO 4 solution, and generated less than 1% H 2O 2. The PEM fuel cell exhibited a current density as high as 0.27 A cm -2 at 0.6 V and 2.3 A cm -2 at 0.2 V for a catalyst loading of 6.0 mg cm -2. No significant performance degradation was observed over 480 h of continuous fuel cell operation with 2 mg cm -2 catalyst under a load of 200 mA cm -2 as evidenced by a resulting cell voltage of 0.32 V with a voltage decay rate of 80 μV h -1. Materials characterization studies indicated that the metal-nitrogen chelate complexes decompose at high pyrolysis temperatures above 800 °C, resulting in the formation of the metallic species. During the pyrolysis, the transition metals facilitate the incorporation of pyridinic and graphitic nitrogen groups into the carbon matrix, and the carbon surface doped with nitrogen groups is catalytically active for oxygen reduction.

  9. Study on the mesocarbon microbeads/polyphenylene sulfide composite bipolar plates applied for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Shi, Pengfei

    Thermoplastic/graphite composite bipolar plates based on polyphenylene sulfide (PPS) and mesocarbon microbeads (MCMB) were prepared by compression molding at a pressure of 40 MPa and 400 °C. Electrical conductivity, bulk density, flexural strength, water and ethanol absorption were determined as function of PPS content. The influences of molding time, actived carbon and carbon fiber on the properties of the composite bipolar plates were investigated, the cross section of the composite plates were analyzed by scanning electron microscope (SEM). We found that the optimized PPS content is 20 wt% and the required molding time is 30 min. In particular, the composite plates containing 20 wt% PPS demonstrated in-plane conductivity as high as 133.7 S cm -1, through-plane conductivity 21.37 S cm -1, in addition to showing the value of density, flexural strength, water and ethanol absorption as 1.98 g cm -3, 38.82 MPa, 0.0409 and 0.352 g cm -3. The addition of actived carbon degraded all the performance of the bipolar plate, while addition of carbon fiber improved almost all the performance of bipolar plate except bulk density and through-plane conductivity. The performances of fuel cell with this composite bipolar plate were tested, no distinct variation occurred after the composite plates operating in fuel cell. These data indicates the chemical and mechanical stability of the composite plates and their potential application in fuel cell.

  10. Miniaturized proton exchange fuel cell in micromachined silicon surface

    NASA Astrophysics Data System (ADS)

    D'Arrigo, Giuseppe; Spinella, Corrado; Rimini, Emanuele; Rubino, Loredana; Lorenti, Simona

    2004-01-01

    The increasing interest for light and movable electronic systems, cell phones and small digital devices, drives the technological research toward integrated regenerating power sources with small dimensions and great autonomy. Conventional batteries are already unable to deliver power in more and more shrunk volumes maintaining the requirements of long duration and lightweight. A possible solution to overcome these limits is the use of miniaturized fuel cell. The fuel cell offers a greater gravimetric energy density compared to conventional batteries. The micromachining technology of silicon is an important tool to reduce the fuel cell structure to micrometer sizes. The use of silicon also gives the opportunity to integrate the power source and the electronic circuits controlling the fuel cell on the same structure. This paper reports preliminary results concerning the micromachining procedure to fabricate an arrays of microchannels for a Si-based electrocatalytic membrane for miniaturized Si-based proton exchange membrane fuel cells. Several techniques are routinely used to fabricate arrays of microchannels embedded in crystalline silicon. In this paper we present an innovative microchannel formation process, entirely based on surface silicon micromachining, which allows us to produce rhomboidal microchannels embedded on (100) silicon wafers. Compared to the traditional techniques, the proposed process is extremely compatible with the standard microelectronics silicon technology. The kinetics of rhomboidal microchannel formation is monitored by cyclic voltammetry measurements and the results are compared with a detailed structural characterisation performed by scanning electron microscopy. The effectiveness of this process is discussed in view of the possible applications in the fuel cell application.

  11. Method of fabricating electrode catalyst layers with directionally oriented carbon support for proton exchange membrane fuel cell

    DOEpatents

    Liu, Di-Jia; Yang, Junbing

    2010-07-20

    A method of making a membrane electrode assembly (MEA) having an anode and a cathode and a proton conductive membrane there between. A bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated in the nanotubes forms at least one portion of the MEA and is in contact with the membrane. A combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into a first reaction zone maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is transmitted to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes. The nanotubes are in contact with a portion of the MEA at production or being positioned in contact thereafter. Methods of forming a PEMFC are also disclosed.

  12. Effect of heat treatment on the activity and stability of carbon supported PtMo alloy electrocatalysts for hydrogen oxidation in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Hassan, Ayaz; Carreras, Alejo; Trincavelli, Jorge; Ticianelli, Edson Antonio

    2014-02-01

    The effect of heat treatment on the activity, stability and CO tolerance of PtMo/C catalysts was studied, due to their applicability in the anode of proton exchange membrane fuel cells (PEMFCs). To this purpose, a carbon supported PtMo (60:40) alloy electrocatalyst was synthesized by the formic acid reduction method, and samples of this catalyst were heat-treated at various temperatures ranging between 400 and 700 °C. The samples were characterized by temperature programmed reduction (TPR), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), cyclic voltammetry (CV), scanning electron microscopy (SEM) and wavelength dispersive X-ray spectroscopy (WDS). Cyclic voltammetry was used to study the stability, and polarization curves were used to investigate the performance of all materials as CO tolerant anode on a PEM single cell text fixture. The catalyst treated at 600 °C, for which the average crystallite size was 16.7 nm, showed the highest hydrogen oxidation activity in the presence of CO, giving an overpotential induced by CO contamination of 100 mV at 1 Acm-2. This catalyst also showed a better stability up to 5000 potential cycles of cyclic voltammetry, as compared to the untreated catalyst. CV, SEM and WDS results indicated that a partial dissolution of Mo and its migration/diffusion from the anode to the cathode occurs during the single cell cycling. Polarization results showed that the catalytic activity and the stability can be improved by a heat treatment, in spite of a growth of the catalyst particles.

  13. Experimental study of clamping effects on the performances of a single proton exchange membrane fuel cell and a 10-cell stack

    NASA Astrophysics Data System (ADS)

    Wen, Chih-Yung; Lin, Yu-Sheng; Lu, Chien-Heng

    The contact pressure distribution is known to have significant influences on the contact ohmic resistance, porosity of gas diffusion layers (GDLs) and performance of the proton exchange membrane fuel cell (PEMFC) consequently. This work experimentally investigated the effects of various combinations of bolt configuration and clamping torque on the corresponding contact pressure distributions and performances of a single PEMFC and a 10-cell stack. The pressure-sensitive films (FUJI-FILM I&I) were used to visualize the contact pressure distributions under three different clamping torques and three different bolt configurations in the experiments. The importance of the proper stacking design was clearly demonstrated by these contact pressure images. The mean value and the fluctuation intensity of the contact pressure were extracted statistically from the data of pressure-sensitive films. A non-dimensional pressure fluctuation intensity, which indicates the relative dispersion to its mean value, was proposed to gauge the uniformity of the contact pressure distribution, similar to the definition of the turbulence intensity in fluid mechanics. The experimental results showed that, for the single cell under the current experiment conditions, the larger mean contact pressure tends to yield the higher maximum power, regardless of the bolt configuration and the applied torque. The uniformity of the contact pressure distribution, the ohmic resistance and the mass transport limit current had highly linear correlations with the mean contact pressure. In the case of the 10-cell stack, the effects of various combinations of bolt configuration and clamping torque on its performance and the mass transport limit current could not be reflected by the stack mean contact pressure only. Increasing the mean contact pressure improved the uniformity of the contact pressure distribution and reduced the contact ohmic resistance, in general. However, the maximum power did not increase

  14. An air-breathing single cell small proton exchange membrane fuel cell system with AB5-type metal hydride and an ultra-low voltage input boost converter

    NASA Astrophysics Data System (ADS)

    Akiyama, Kazuya; Matsumoto, Satoshi; Miyasaka, Akihiro; Shodai, Takahisa

    A new strategy for increasing the power density of an air-breathing small proton exchange membrane fuel cell (PEMFC) system for the main energy source of portable consumer electronics is presented. The small PEMFC system is composed of a single cell. Utilizing the output voltage of the single cell, we introduce a newly designed ultra-low voltage input boost converter. The boost converter can generate 4.1 V output from input sources with low voltage ranges, such as under 1.0 V. The cathode plate is made from a thin SUS 316L stainless steel plate and has ribs that prevent the cathode from bending. The hydrogen is supplied by a metal hydride (MH) tank cartridge. The MH tank contains highly packed AB5-type MH. The MH tank cartridge has a volume of 13.2 cm 3 and can absorb 6.7 L of hydrogen. The maximum power of the small PEMFC is 4.42 W at room temperature. Using 6.7 L of hydrogen, the small PEMFC can generate 11 Wh of electricity. The power density of the small PEMFC reaches 0.51 Wh cm -3. And the power density of the whole small PEMFC system, which contains the boost converter, a small Li-ion battery for a load absorber, and a case for the system, reaches 0.14 Wh cm -3. This value matches that of external Li-ion battery chargers for cell phones. We installed the small PEMFC system in a cell phone and confirmed the operations of calling, receiving, videophone, connecting to the Internet, and watching digital TV. And also confirmed that the small PEMFC system provides approximately 8.25 h of talk time, which is about three times as long as that for the original Li-ion battery.

  15. Investigation of titanium nitride as catalyst support material and development of durable electrocatalysts for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Avasarala, Bharat K.

    The impending energy and climatic crisis makes it imperative for human society to seek non-fossil based alternative sources for our energy needs. Although many alternative energy technologies are currently being developed, fuel cell technology provides energy solutions, which satisfy a wide range of applications. But the current fuel cell technology is far from its target of large scale commercialization mainly because of its high cost and poor durability. Considerable work has been done in reducing the cost but its durability still needs significant improvement. Of the various materials in a PEM fuel cell, the degradation of electrocatalyst affects its durability the most, leading to performance loss. Carbon black (C) support corrosion plays a significant role in the electrocatalyst degradation and its severe affects due to potential cycling has been identified through my research. Through my resaerch, I introduce titanium nitride nanoparticles (TiN NP) as alternative catalyst supports replacing carbon black. TiN NP has higher electrical conductivity and corrosion resistance compared to that of C. The physical and electrochemical properties of TiN NP were studied and the Pt/TiN electrocatalyst was synthesized using polyol process. Upon optimizing using DOE, for desired catalyst particle size and activity, Pt/TiN is shown to have higher catalytic performance than conventional Pt/C. TiN NP are significantly influenced by the electrochemical conditions and show 'active' or 'passive' nature depending on the temperature and acidic concentration; and a temperature dependence model is proposed to understand the active/passive nature of TiN NP. A one-to-one comparison between TiN NP and C electrodes under similar electrochemical conditions show a superior performance of TiN NP as a catalyst support. The durability of the Pt/TiN electrocatalyst is also tested and it agrees well with the proposed model of active/passive nature of the TiN NP. Through theoretical calculation

  16. Final report on LDRD project : elucidating performance of proton-exchange-membrane fuel cells via computational modeling with experimental discovery and validation.

    SciTech Connect

    Wang, Chao Yang (Pennsylvania State University, University Park, PA); Pasaogullari, Ugur (Pennsylvania State University, University Park, PA); Noble, David R.; Siegel, Nathan P.; Hickner, Michael A.; Chen, Ken Shuang

    2006-11-01

    In this report, we document the accomplishments in our Laboratory Directed Research and Development project in which we employed a technical approach of combining experiments with computational modeling and analyses to elucidate the performance of hydrogen-fed proton exchange membrane fuel cells (PEMFCs). In the first part of this report, we document our focused efforts on understanding water transport in and removal from a hydrogen-fed PEMFC. Using a transparent cell, we directly visualized the evolution and growth of liquid-water droplets at the gas diffusion layer (GDL)/gas flow channel (GFC) interface. We further carried out a detailed experimental study to observe, via direct visualization, the formation, growth, and instability of water droplets at the GDL/GFC interface using a specially-designed apparatus, which simulates the cathode operation of a PEMFC. We developed a simplified model, based on our experimental observation and data, for predicting the onset of water-droplet instability at the GDL/GFC interface. Using a state-of-the-art neutron imaging instrument available at NIST (National Institute of Standard and Technology), we probed liquid-water distribution inside an operating PEMFC under a variety of operating conditions and investigated effects of evaporation due to local heating by waste heat on water removal. Moreover, we developed computational models for analyzing the effects of micro-porous layer on net water transport across the membrane and GDL anisotropy on the temperature and water distributions in the cathode of a PEMFC. We further developed a two-phase model based on the multiphase mixture formulation for predicting the liquid saturation, pressure drop, and flow maldistribution across the PEMFC cathode channels. In the second part of this report, we document our efforts on modeling the electrochemical performance of PEMFCs. We developed a constitutive model for predicting proton conductivity in polymer electrolyte membranes and compared

  17. Degradation mechanisms of Platinum Nanoparticle Catalysts in Proton Exchange Membrane Fuel Cells: The Role of Particle Size

    SciTech Connect

    Yu, Kang; Groom, Daniel J.; Wang, Xiaoping; Yang, Zhiwei; Gummalla, Mallika; Ball, Sarah C.; Myers, Deborah J.; Ferreira, Paulo J.

    2014-10-14

    Five membrane-electrode assemblies (MEAs) with different average sizes of platinum (Pt) nanoparticles (2.2, 3.5, 5.0, 6.7, and 11.3 nm) in the cathode were analyzed before and after potential cycling (0.6 to 1.0 V, 50 mV/s) by transmission electron microscopy. Cathodes loaded with 2.2 nm and 3.5 nm catalyst nanoparticles exhibit the following changes during electrochemical cycling: (i) substantial broadening of the size distribution relative to the initial size distribution, (ii) presence of coalesced particles within the electrode, and (iii) precipitation of sub-micron-sized particles with complex shapes within the membrane. In contrast, cathodes loaded with 5.0 nm, 6.7 nm and 11.3 nm size catalyst nanoparticles are significantly less prone to the aforementioned effects. As a result, the electrochemically-active surface area (ECA) of MEA cathodes loaded with 2.2 nm and 3.5 nm nanoparticle catalysts degrades dramatically within 1,000 cycles of operation, while the electrochemically-active surface area of MEA cathodes loaded with 5.0 nm, 6.7 nm and 11.3 nm nanoparticle catalysts appears to be stable even after 10,000 cycles. The loss in MEA performance for cathodes loaded with 2.2 nm and 3.5 nm nanoparticle catalysts appears to be due to the loss in electrochemically-active surface area concomitant with the observed morphological changes in these nanoparticle catalysts

  18. Pt and PtRu catalyst bilayers increase efficiencies for ethanol oxidation in proton exchange membrane electrolysis and fuel cells

    NASA Astrophysics Data System (ADS)

    Altarawneh, Rakan M.; Pickup, Peter G.

    2017-10-01

    Polarization curves, product distributions, and reaction stoichiometries have been measured for the oxidation of ethanol at anodes consisting of Pt and PtRu bilayers and a homogeneous mixture of the two catalysts. These anode structures all show synergies between the two catalysts that can be attributed to the oxidation of acetaldehyde produced at the PtRu catalyst by the Pt catalyst. The use of a PtRu layer over a Pt layer produces the strongest effect, with higher currents than a Pt on PtRu bilayer, mixed layer, or either catalyst alone, except for Pt at high potentials. Reaction stoichiometries (average number of electrons transferred per ethanol molecule) were closer to the values for Pt alone for both of the bilayer configurations but much lower for PtRu and mixed anodes. Although Pt alone would provide the highest overall fuel cell efficiency at low power densities, the PtRu on Pt bilayer would provide higher power densities without a significant loss of efficiency. The origin of the synergy between the Pt and PtRu catalysts was elucidated by separation of the total current into the individual components for generation of carbon dioxide and the acetaldehyde and acetic acid byproducts.

  19. Fault detection and isolation of high temperature proton exchange membrane fuel cell stack under the influence of degradation

    NASA Astrophysics Data System (ADS)

    Jeppesen, Christian; Araya, Samuel Simon; Sahlin, Simon Lennart; Thomas, Sobi; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2017-08-01

    This study proposes a data-drive impedance-based methodology for fault detection and isolation of low and high cathode stoichiometry, high CO concentration in the anode gas, high methanol vapour concentrations in the anode gas and low anode stoichiometry, for high temperature PEM fuel cells. The fault detection and isolation algorithm is based on an artificial neural network classifier, which uses three extracted features as input. Two of the proposed features are based on angles in the impedance spectrum, and are therefore relative to specific points, and shown to be independent of degradation, contrary to other available feature extraction methods in the literature. The experimental data is based on a 35 day experiment, where 2010 unique electrochemical impedance spectroscopy measurements were recorded. The test of the algorithm resulted in a good detectability of the faults, except for high methanol vapour concentration in the anode gas fault, which was found to be difficult to distinguish from a normal operational data. The achieved accuracy for faults related to CO pollution, anode- and cathode stoichiometry is 100% success rate. Overall global accuracy on the test data is 94.6%.

  20. Cryo-SEM of hydrated high temperature proton exchange membranes

    SciTech Connect

    Perry, Kelly A; More, Karren Leslie; Walker, Larry R; Benicewicz, Brian

    2009-01-01

    Alternative energy technologies, such as high temperature fuel cells and hydrogen pumps, rely on proton exchange membranes (PEM). A chemically and thermally stable PEM with rapid proton transport is sol-gel phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes. It is believed that the key to the high ionic conductivity of PA-doped PBI membranes is related to the gel morphology. However, the gel structure and general morphology of this PA-doped PBI membrane has not been widely investigated. In an effort to understand the gel morphology, two SEM sample preparation methodologies have been developed for PA-doped PBI membranes. Due to the high vacuum environment of conventional SEM, the beam-sensitivity of these membranes was reduced with a mild 120 C heat treatment to remove excess water without structural rearrangement (as verified from wide angle X-ray scattering). Cryo-SEM has also been implemented for both initial and heated membranes. Cryo-SEM is known to prevent dehydration of the specimen and reduce beam-sensitivity. The SEM cross-section image (Fig. 1A) of the heated samples exhibit 3{micro}m spheroidal features that are elongated in the direction of the casting blade. These features are distorted to 2{micro}m under conventional SEM conditions (Fig. 1B). The fine-scale gel morphology image (Fig. 2) is composed of 65nm diameter domains and 30nm walls, which resembles a cellular structure. In the future, the PA-doped PBI membranes will be cryo-microtomed and cryotransferred for elemental analysis in a TEM.

  1. Molecular sieve/sulfonated poly(ether ketone ether sulfone) composite membrane as proton exchange membrane

    NASA Astrophysics Data System (ADS)

    Changkhamchom, Sairung; Sirivat, Anuvat

    2012-02-01

    A proton exchange membrane (PEM) is an electrolyte membrane used in both polymer electrolyte membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFCs). Currently, PEMs typically used for PEMFCs are mainly the commercially available Nafion^ membranes, which is high cost and loss of proton conductivity at elevated temperature. In this work, the Sulfonated poly(ether ketone ether sulfone), (S-PEKES), was synthesized by the nucleophilic aromatic substitution polycondensation between bisphenol S and 4,4'-dichlorobenzophenone, and followed by the sulfonation reaction with concentrated sulfuric acid. The molecular sieve was added in the S-PEKES matrix at various ratios to form composite membranes to be the candidate for PEM. Properties of both pure sulfonated polymer and composite membranes were compared with the commercial Nafion^ 117 membrane from Dupont. S-PEKES membranes cast from these materials were evaluated as a polymer electrolyte membrane for direct methanol fuel cells. The main properties investigated were the proton conductivity, methanol permeability, thermal, chemical, oxidative, and mechanical stabilities by using a LCR meter, Gas Chromatography, Thermogravimetric Analysis, Fourier Transform Infrared Spectroscopy, Fenton's reagent, and Universal Testing Machine. The addition of the molecular sieve helped to increase both the proton conductivity and the methanol stability. These composite membranes are shown as to be potential candidates for use as a Proton Exchange Membrane (PEM).

  2. Study of coupled transport and its effect on different electrochemical systems: Implications in high temperature energy storage batteries and proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Parthasarathy, Preethy

    Coupled transport is studied on two electrochemical systems: Na-ZnCl 2 batteries and Proton Exchange Membrane Fuel Cells (PEMFC). The energy storage system of interest here is based on sodium β"-alumina solid electrolyte (BASE): Na/BASE/ZnCl2. BASE is an excellent Na+ conductor with a very high conductivity at 300°C. Its high Na+ ion conductivity and high stability are the principal reasons for its application in electrochemical storage systems. A novel vapor phase process was invented facilitating the fabrication of high strength and moisture/CO 2 resistant BASE. A two-phase composite of alumiNa+YSZ is formed by sintering and exposed to Na2O vapor, keeping the activity of Na2O lower than that in NaAlO2. This prevents the formation of hygroscopic NaAlO2 at the grain boundaries. A thin layer of β"-alumina is formed on the surface upon exposure. Further reaction occurs by transporting Na+ ions through the formed β"-alumina and a parallel transport of O2- ions through YSZ. This occurs by a coupled transport of Na+ through β"-alumina and O 2- ions through YSZ, thus expediting the process. The second electrochemical system of interest is PEMFC. The degradation mechanism of catalysts is studied using inexpensive copper particles. The mechanism of growth involves a coupled transport of Cu2+ through the aqueous medium and an electron transport through the direct particle-to-particle contact. Effect of applied stress on coarsening of platinum was also investigated. Two platinum wires/foils were immersed in a PtCl4+DMSO (Dimethyl sulfoxide) solution. A tensile load was applied to one wire/foil and the other one was left load-free. The wire/foil subjected to a tensile load became cathodic with respect to the unstressed wire/foil. Thus, under a tensile stress, the chemical potential of Pt decreases. This result suggests design strategies for core-shell catalysts used in PEMFCs: stable core-shell catalysts for PEMFC with Pt shell should be designed such that the shell is

  3. Molecular Simulations of Hydrated Proton Exchange Membranes: the Structure

    NASA Astrophysics Data System (ADS)

    Marchand, Gabriel; Bopp, Philippe A.; Spohr, Eckhard

    2013-02-01

    The structure of two hydrated proton exchange membranes for fuel cells (PEMFC), Nafion® (Dupont) and Hyflon® (Solvay), is studied by all-atom molecular dynamics (MD) computer simulations. Since the characteristic times of these systems are long compared to the times for which they can be simulated, several different, but equivalent, initial configurations with a large degree of randomness are generated for different water contents and then equilibrated and simulated in parallel. A more constrained structure, analog to the newest model proposed in the literature based on scattering experiments, is investigated in the same way. One might speculate that a limited degree of entanglement of the polymer chains is a key feature of the structures showing the best agreement with experiment. Nevertheless, the overall conclusion remains that the scattering experiments cannot distinguish between the several, in our view equally plausible, structural models. We thus find that the characteristic features of experimental scattering curves are, after equilibration, fairly well reproduced by all systems prepared with our method. We thus study in more detail some structural details. We attempt to characterize the spatial and size distribution of the water rich domains, which is where the proton diffusion mostly takes place, using several clustering algorithms.

  4. HYDROGEN ISOTOPE RECOVERY USING PROTON EXCHANGE MEMBRANE ELECTROLYSIS OF WATER

    SciTech Connect

    Fox, E; Scott Greenway, S; Amy Ekechukwu, A

    2007-08-27

    A critical component of tritium glovebox operations is the recovery of high value tritium from the water vapor in the glove box atmosphere. One proposed method to improve existing tritium recovery systems is to replace the disposable hot magnesium beds used to separate the hydrogen and oxygen in water with continuous use Proton Exchange Membrane Electrolyzers (PEMEs). This study examines radiation exposure to the membrane of a PEME and examines the sizing difference that would be needed if the electrolyzer were operated with a cathode water vapor feed instead of an anode liquid water feed.

  5. Preparation and characterization of polymer blend based on sulfonated poly (ether ether ketone) and polyetherimide (SPEEK/PEI) as proton exchange membranes for fuel cells

    SciTech Connect

    Hashim, Nordiana; Ali, Ab Malik Marwan; Lepit, Ajis; Rasmidi, Rosfayanti; Subban, Ri Hanum Yahaya; Yahya, Muhd Zu Azhan

    2015-08-28

    Blends of sulfonated poly (ether ether ketone) (SPEEK) and polyetherimide (PEI) were prepared in five different weight ratios using N-methyl-2-pyrrolidone (NMP) as solvent by the solution cast technique. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d{sub 6}) solution of the purified polymer using {sup 1}H NMR method. The properties studied in the present investigation includes conductivity, water uptake, thermal stability and structure analysis of pure SPEEK as well as SPEEK-PEI polymer blend membranes. The experimental results show that the conductivity of the membranes increased with increase in temperature from 30 to 80°C, except for that of pure SPEEK membrane which increased with temperature from 30 to 60°C while its conductivity decreased with increasing temperature from 60 to 80°C. The conductivity of 70wt.%SPEEK-30wt.%PEI blend membrane at 80% relative humidity (RH) is found to be 1.361 × 10{sup −3} Scm{sup −1} at 30°C and 3.383 × 10{sup −3} Scm{sup −1} at 80°C respectively. It was also found that water uptake and thermal stability of the membranes slightly improved upon blending with PEI. Structure analysis was carried out using Fourier Transform Infrared (FTIR) spectroscopy which revealed considerable interactions between sulfonic acid group of SPEEK and imide groups of PEI. Modification of SPEEK by blending with PEI shows good potential for improving the electrical and physical properties of proton exchange membranes.

  6. Preparation and characterization of polymer blend based on sulfonated poly (ether ether ketone) and polyetherimide (SPEEK/PEI) as proton exchange membranes for fuel cells

    NASA Astrophysics Data System (ADS)

    Hashim, Nordiana; Ali, Ab Malik Marwan; Lepit, Ajis; Rasmidi, Rosfayanti; Subban, Ri Hanum Yahaya; Yahya, Muhd Zu Azhan

    2015-08-01

    Blends of sulfonated poly (ether ether ketone) (SPEEK) and polyetherimide (PEI) were prepared in five different weight ratios using N-methyl-2-pyrrolidone (NMP) as solvent by the solution cast technique. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d6) solution of the purified polymer using 1H NMR method. The properties studied in the present investigation includes conductivity, water uptake, thermal stability and structure analysis of pure SPEEK as well as SPEEK-PEI polymer blend membranes. The experimental results show that the conductivity of the membranes increased with increase in temperature from 30 to 80°C, except for that of pure SPEEK membrane which increased with temperature from 30 to 60°C while its conductivity decreased with increasing temperature from 60 to 80°C. The conductivity of 70wt.%SPEEK-30wt.%PEI blend membrane at 80% relative humidity (RH) is found to be 1.361 × 10-3 Scm-1 at 30°C and 3.383 × 10-3 Scm-1 at 80°C respectively. It was also found that water uptake and thermal stability of the membranes slightly improved upon blending with PEI. Structure analysis was carried out using Fourier Transform Infrared (FTIR) spectroscopy which revealed considerable interactions between sulfonic acid group of SPEEK and imide groups of PEI. Modification of SPEEK by blending with PEI shows good potential for improving the electrical and physical properties of proton exchange membranes.

  7. Platinum-cobalt catalysts for the oxygen reduction reaction in high temperature proton exchange membrane fuel cells - Long term behavior under ex-situ and in-situ conditions

    NASA Astrophysics Data System (ADS)

    Schenk, Alexander; Grimmer, Christoph; Perchthaler, Markus; Weinberger, Stephan; Pichler, Birgit; Heinzl, Christoph; Scheu, Christina; Mautner, Franz-Andreas; Bitschnau, Brigitte; Hacker, Viktor

    2014-11-01

    Platinum cobalt catalysts (Pt-Co) have attracted much interest as cathode catalysts for proton exchange membrane fuel cells (PEMFCs) due to their high activity toward oxygen reduction reaction (ORR). Many of the reported catalysts show outstanding performance in ex-situ experiments. However, the laborious synthesis protocols of these Pt-Co catalysts disable an efficient and economic production of membrane electrode assemblies (MEAs). We present an economic, flexible and continuous Pt-M/C catalyst preparation method as part of a large scale membrane electrode assembly manufacturing. In comparison, the as-prepared Pt-Co/C based high temperature (HT)-PEM MEA showed an equal performance to a commercially available HT-PEM MEA during 600 h of operation under constant load, although the commercial one had a significantly higher Pt loading at the cathode.

  8. Effect of assembly error of bipolar plate on the contact pressure distribution and stress failure of membrane electrode assembly in proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Liu, Dong'an; Peng, Linfa; Lai, Xinmin

    In practice, the assembly error of the bipolar plate (BPP) in a PEM fuel cell stack is unavoidable based on the current assembly process. However its effect on the performance of the PEM fuel cell stack is not reported yet. In this study, a methodology based on FEA model, "least squares-support vector machine (LS-SVM)" simulation and statistical analysis is developed to investigate the effect of the assembly error of the BPP on the pressure distribution and stress failure of membrane electrode assembly (MEA). At first, a parameterized FEA model of a metallic BPP/MEA assembly is established. Then, the LS-SVM simulation process is conducted based on the FEA model, and datasets for the pressure distribution and Von Mises stress of MEA are obtained, respectively for each assembly error. At last, the effect of the assembly error is obtained by applying the statistical analysis to the LS-SVM results. A regression equation between the stress failure and the assembly error is also built, and the allowed maximum assembly error is calculated based on the equation. The methodology in this study is beneficial to understand the mechanism of the assembly error and can be applied to guide the assembly process for the PEM fuel cell stack.

  9. In-plane biaxial cyclic mechanical behavior of proton exchange membranes

    NASA Astrophysics Data System (ADS)

    Lin, Qiang; Shi, Shouwen; Wang, Lei; Chen, Shan; Chen, Xu; Chen, Gang

    2017-08-01

    The durability of a proton exchange membrane is affected by both mechanical degradation and chemical degradation. While fatigue and relative humidity cycling tests have been conducted to address mechanical degradation, the cyclic behavior that bridges the gap between the stress-strain response and fatigue behavior is not well established. The objective of this study is to understand the strain evolution during biaxial cyclic loading that resemble the actual stress state of the membrane. In particular, the effect of loading paths on strain evolution is examined to account for the stress state on strain accumulation. It is found that the constraint effect of stress in one direction on strain evolution in another direction strongly depends on the stress state of the membrane, and the equibiaxial stress state imposes the most significant constraint on strain evolution. Furthermore, the constraint effect induced by biaxial loading is more significant at higher relative humidity values. Moreover, high-stress amplitude cycle acts to retard strain accumulation in the subsequent low-stress amplitude cycle. The findings reported here will provide new evidence for an understanding of the fatigue behavior of a proton exchange membrane as well as durability modeling of proton exchange membrane fuel cells.

  10. Water hydrogen bonding in proton exchange and neutral polymer membranes

    NASA Astrophysics Data System (ADS)

    Smedley, Sarah Black

    Understanding the dynamics of water sorbed into polymer films is critical to reveal structure-property relationships in membranes for energy and water treatment applications, where membranes must interact with water to facilitate or inhibit the transport of ions. The chemical structure of the polymer has drastic effects on the transport properties of the membrane due to the morphological structure of the polymer and how water is interacting with the functional groups on the polymer backbone. Therefore studying the dynamics of water adsorbed into a membrane will give insight into how water-polymer interactions influence transport properties of the film. With a better understanding of how to design materials to have specific properties, we can accelerate development of smarter materials for both energy and water treatment applications to increase efficiency and create high-flux materials and processes. The goal of this dissertation is to investigate the water-polymer interactions in proton exchange and uncharged membranes and make correlations to their charge densities and transport properties. A linear Fourier Transform Infrared (FTIR) spectroscopic method for measuring the hydrogen bonding distribution of water sorbed in proton exchange membranes is described in this thesis. The information on the distribution of the microenvironments of water in an ionic polymer is critical to understanding the effects of different acidic groups on the proton conductivity of proton exchange membranes at low relative humidity. The OD stretch of dilute HOD in H2O is a single, well-defined vibrational band. When HOD in dilute H2O is sorbed into a proton exchange membrane, the OD stretch peak shifts based on the microenvironment that water encounters within the nanophase separated structure of the material. This peak shift is a signature of different hydrogen bonding populations within the membrane, which can be deconvoluted rigorously for dilute HOD in H 2O compared to only

  11. Random and Block Sulfonated Polyaramides as Advanced Proton Exchange Membranes

    SciTech Connect

    Kinsinger, Corey L.; Liu, Yuan; Liu, Feilong; Yang, Yuan; Seifert, Soenke; Knauss, Daniel M.; Herring, Andrew M; Maupin, C. Mark

    2015-10-09

    We present here the experimental and computational characterization of two novel copolyaramide proton exchange membranes (PEMs) with higher conductivity than Nafion at relatively high temperatures, good mechanical properties, high thermal stability, and the capability to operate in low humidity conditions. The random and block copolyaramide PEMs are found to possess different ion exchange capacities (IEC) in addition to subtle structural and morphological differences, which impact the stability and conductivity of the membranes. SAXS patterns indicate the ionomer peak for the dry block copolymer resides at q = 0.1 Å–1, which increases in amplitude when initially hydrated to 25% relative humidity, but then decrease in amplitude with additional hydration. This pattern is hypothesized to signal the transport of water into the polymer matrix resulting in a reduced degree of phase separation. Coupled to these morphological changes, the enhanced proton transport characteristics and structural/mechanical stability for the block copolymer are hypothesized to be primarily due to the ordered structure of ionic clusters that create connected proton transport pathways while reducing swelling upon hydration. Interestingly, the random copolymer did not possess an ionomer peak at any of the hydration levels investigated, indicating a lack of any significant ionomer structure. The random copolymer also demonstrated higher proton conductivity than the block copolymer, which is opposite to the trend normally seen in polymer membranes. However, it has reduced structural/mechanical stability as compared to the block copolymer. In conclusion, this reduction in stability is due to the random morphology formed by entanglements of polymer chains and the adverse swelling characteristics upon hydration. Therefore, the block copolymer with its enhanced proton conductivity characteristics, as compared to Nafion, and favorable structural/mechanical stability, as compared to the

  12. Random and Block Sulfonated Polyaramides as Advanced Proton Exchange Membranes

    DOE PAGES

    Kinsinger, Corey L.; Liu, Yuan; Liu, Feilong; ...

    2015-10-09

    We present here the experimental and computational characterization of two novel copolyaramide proton exchange membranes (PEMs) with higher conductivity than Nafion at relatively high temperatures, good mechanical properties, high thermal stability, and the capability to operate in low humidity conditions. The random and block copolyaramide PEMs are found to possess different ion exchange capacities (IEC) in addition to subtle structural and morphological differences, which impact the stability and conductivity of the membranes. SAXS patterns indicate the ionomer peak for the dry block copolymer resides at q = 0.1 Å–1, which increases in amplitude when initially hydrated to 25% relative humidity,more » but then decrease in amplitude with additional hydration. This pattern is hypothesized to signal the transport of water into the polymer matrix resulting in a reduced degree of phase separation. Coupled to these morphological changes, the enhanced proton transport characteristics and structural/mechanical stability for the block copolymer are hypothesized to be primarily due to the ordered structure of ionic clusters that create connected proton transport pathways while reducing swelling upon hydration. Interestingly, the random copolymer did not possess an ionomer peak at any of the hydration levels investigated, indicating a lack of any significant ionomer structure. The random copolymer also demonstrated higher proton conductivity than the block copolymer, which is opposite to the trend normally seen in polymer membranes. However, it has reduced structural/mechanical stability as compared to the block copolymer. In conclusion, this reduction in stability is due to the random morphology formed by entanglements of polymer chains and the adverse swelling characteristics upon hydration. Therefore, the block copolymer with its enhanced proton conductivity characteristics, as compared to Nafion, and favorable structural/mechanical stability, as compared to the

  13. Composite proton exchange membrane based on sulfonated organic nanoparticles

    NASA Astrophysics Data System (ADS)

    Pitia, Emmanuel Sokiri

    As the world sets its sight into the future, energy remains a great challenge. Proton exchange membrane (PEM) fuel cell is part of the solution to the energy challenge because of its high efficiency and diverse application. The purpose of the PEM is to provide a path for proton transport and to prevent direct mixing of hydrogen and oxygen at the anode and the cathode, respectively. Hence, PEMs must have good proton conductivity, excellent chemical stability, and mechanical durability. The current state-of-the-art PEM is a perfluorosulfonate ionomer, Nafion®. Although Nafion® has many desirable properties, it has high methanol crossover and it is expensive. The objective of this research was to develop a cost effective two-phase, composite PEM wherein a dispersed conductive organic phase preferentially aligned in the transport direction controls proton transport, and a continuous hydrophobic phase provides mechanical durability to the PEM. The hypothesis that was driving this research was that one might expect better dispersion, higher surface to volume ratio and improved proton conductivity of a composite membrane if the dispersed particles were nanometer in size and had high ion exchange capacity (IEC, = [mmol sulfonic acid]/gram of polymer). In view of this, considerable efforts were employed in the synthesis of high IEC organic nanoparticles and fabrication of a composite membrane with controlled microstructure. High IEC, ~ 4.5 meq/g (in acid form, theoretical limit is 5.4 meq/g) nanoparticles were achieved by emulsion copolymerization of a quaternary alkyl ammonium (QAA) neutralized-sulfonated styrene (QAA-SS), styrene, and divinylbenzene (DVB). The effects of varying the counterion of the sulfonated styrene (SS) monomer (alkali metal and QAA cations), SS concentration, and the addition of a crosslinking agent (DVB) on the ability to stabilize the nanoparticles to higher IECs were assessed. The nanoparticles were ion exchanged to acid form. The extent of ion

  14. Toward a predictive understanding of water and charge transport in proton exchange membranes.

    PubMed

    Selvan, Myvizhi Esai; Calvo-Muñoz, Elisa; Keffer, David J

    2011-03-31

    An analytical model for water and charge transport in highly acidic and highly confined systems such as proton exchange membranes of fuel cells is developed and compared to available experimental data. The model is based on observations from both experiment and multiscale simulation. The model accounts for three factors in the system including acidity, confinement, and connectivity. This model has its basis in the molecular-level mechanisms of water transport but has been coarse-grained to the extent that it can be expressed in an analytical form. The model uses the concentration of H(3)O(+) ion to characterize acidity, interfacial surface area per water molecule to characterize confinement, and percolation theory to describe connectivity. Several important results are presented. First, an integrated multiscale simulation approach including both molecular dynamics simulation and confined random walk theory is capable of quantitatively reproducing experimentally measured self-diffusivities of water in the perfluorinated sulfonic acid proton exchange membrane material, Nafion. The simulations, across a range of hydration conditions from minimally hydrated to fully saturated, have an average error for the self-diffusivity of water of 16% relative to experiment. Second, accounting for three factors-acidity, confinement, and connectivity-is necessary and sufficient to understand the self-diffusivity of water in proton exchange membranes. Third, an analytical model based on percolation theory is capable of quantitatively reproducing experimentally measured self-diffusivities of both water and charge in Nafion across a full range of hydration.

  15. Fabrication of a nanosize-Pt-embedded membrane electrode assembly to enhance the utilization of Pt in proton exchange membrane fuel cells.

    PubMed

    Choe, Junseok; Kim, Doyoung; Shim, Jinyong; Lee, Inhae; Tak, Yongsug

    2011-08-01

    A procedure to locate the Pt nanostructure inside the hydrophilic channel of a Nafion membrane was developed in order to enhance Pt utilization in PEMFCs. Nanosize Pt-embedded MEA was constructed by Cu electroless plating and subsequent Pt electrodeposition inside the hydrophilic channels of the Nafion membrane. The metallic Pt nanostructure fabricated inside the membrane was employed as an oxygen reduction catalyst for a PEMFC and facilitated effective use of the hydrophilic channels inside the membrane. Compared to the conventional MEA, a Pt-embedded MEA with only 68% Pt loading showed better PEMFC performance.

  16. Research and development of Proton-Exchange-Membrane (PEM) fuel cell system for transportation applications. Fuel cell infrastructure and commercialization study

    SciTech Connect

    1996-11-01

    This paper has been prepared in partial fulfillment of a subcontract from the Allison Division of General Motors under the terms of Allison`s contract with the U.S. Department of Energy (DE-AC02-90CH10435). The objective of this task (The Fuel Cell Infrastructure and Commercialization Study) is to describe and prepare preliminary evaluations of the processes which will be required to develop fuel cell engines for commercial and private vehicles. This report summarizes the work undertaken on this study. It addresses the availability of the infrastructure (services, energy supplies) and the benefits of creating public/private alliances to accelerate their commercialization. The Allison prime contract includes other tasks related to the research and development of advanced solid polymer fuel cell engines and preparation of a demonstration automotive vehicle. The commercialization process starts when there is sufficient understanding of a fuel cell engine`s technology and markets to initiate preparation of a business plan. The business plan will identify each major step in the design of fuel cell (or electrochemical) engines, evaluation of the markets, acquisition of manufacturing facilities, and the technical and financial resources which will be required. The process will end when one or more companies have successfully developed and produced fuel cell engines at a profit. This study addressed the status of the information which will be required to prepare business plans, develop the economic and market acceptance data, and to identify the mobility, energy and environment benefits of electrochemical or fuel cell engines. It provides the reader with information on the status of fuel cell or electrochemical engine development and their relative advantages over competitive propulsion systems. Recommendations and descriptions of additional technical and business evaluations that are to be developed in more detail in Phase II, are included.

  17. Study of nitrile-containing proton exchange membranes prepared by radiation grafting: Performance and degradation in the polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Zhang, Zhuoxiang; Jetsrisuparb, Kaewta; Wokaun, Alexander; Gubler, Lorenz

    2013-12-01

    The fuel cell performance and durability of three kinds of styrene based radiation grafted membranes are investigated and compared in the single cell. The styrene/methacrylonitrile (MAN) co-grafted membrane exhibits the best performance among the tested radiation grafted membranes. The accelerated tests under open circuit voltage (OCV) conditions and post-mortem analysis demonstrate that the nitrile-containing membranes exhibit significantly enhanced durability compared to the pure styrene grafted membrane, which is associated with the reduced gas crossover rates and attributed to the improved gases barrier properties due to the polarity of the nitrile group. To understand the influence of each functional group in the co-monomer units, both styrene/MAN and styrene/acrylonitrile (AN) co-grafted membranes are evaluated in a set of tests at OCV. The degrees of loss of the graft components are subsequently quantitatively analyzed based on FTIR spectra, showing a comparable decomposition rate of grafted styrene units, but more loss of nitrile in case of the styrene/AN co-grafted membrane. The styrene/AN co-grafted membrane, with AN lacking protection at the α-position in contrast to MAN, is found to be susceptible to significant hydrolysis, directly leading to an accelerated degradation in the late stages of the 130 h OCV test and inhomogeneous in-plane degradation.

  18. Post-mortem analysis of a long-term tested proton exchange membrane fuel cell stack under low cathode humidification conditions

    NASA Astrophysics Data System (ADS)

    Kim, Nam-In; Seo, Yongho; Kim, Ki Buem; Lee, Naesung; Lee, Jin-Hwa; Song, Inseob; Choi, Hanshin; Park, Jun-Young

    2014-05-01

    During continuous power operation for 2740 h, the major mechanisms and patterns of performance degradation in a polymer electrolyte membrane fuel cell (PEMFC) stack are investigated under low cathode humidification with simulated reformate fuel gases through the use of various physicochemical and electrochemical analysis tools. As operating time increases, the operating voltages and open-circuit voltages (OCVs) of the stack decrease with the large voltage distributions. In the post-mortem analysis of the stack, the delamination of the catalyst layer (CL) of unstable operating membrane electrode assemblies (MEAs) is significant near the cathode gas inlets. This observation is in agreement with the results of OCV, hydrogen crossover current, and anode off-gas measurements. This phenomenon may be due to the acceleration of carbon corrosion in the cathode during the frequent start-up and shut-down process, because the local cathode potential can reach more than 1.5 V in the air/fuel boundary. Additionally, the frequent membrane hydration and dehydration by the accumulation of excess water (through electrochemical reaction) and faster water evaporation (under dry-air cathode conditions and high operating temperatures) may accelerate the interface delamination between the membrane and cathode CL with a substantially uneven distribution of water.

  19. V-doped TiO2 supported Pt as a promising oxygen reduction reaction catalyst: Synthesis, characterization and in-situ evaluation in proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Bharti, Abha; Cheruvally, Gouri

    2017-09-01

    This study deals with the synthesis and characterization of V-doped, TiO2 supported Pt catalyst (Pt/V-TiO2) for oxygen reduction reaction (ORR) and its in-situ performance investigation in proton exchange membrane (PEM) fuel cell.