scholarly journals Electrochemical Performance Measurements of PBI-Based High-Temperature PEMFCs

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Javier Parrondo ◽  
Chitturi Venkateswara Rao ◽  
Sundara L. Ghatty ◽  
B. Rambabu
Keyword(s):  
Fuel Cell ◽  
Electrochemical Performance ◽  
Electrochemical Impedance ◽  
Gas Diffusion ◽  
Cell Polarization ◽  
Membrane Electrode ◽  
Performance Measurements ◽  
Transfer Resistance ◽  
Warburg Impedance ◽  
Overall Resistance

Acid-doped poly(2,2′-m-phenylene-5,5′-bibenzimidazole) membranes have been prepared and used to assemble membrane electrode assemblies (MEAs) with various contents of PBI (1–30 wt.%) in the gas diffusion electrode (GDE). The MEAs were tested in the temperature range of140∘C–200∘C showing that the PBI content in the electrocatalyst layer influences strongly the electrochemical performance of the fuel cell. The MEAs were assembled using polyphosphoric acid doped PBI membranes having conductivities of 0.1 Scm−1at180∘C. The ionic resistance of the cathode decreased from 0.29 to 0.14 Ohm-cm2(180∘C) when the content of PBI is varied from 1 to 10 wt.%. Similarly, the mass transfer resistance or Warburg impedance increased 2.5 times, reaching values of 6 Ohm-cm2. 5 wt.% PBI-based MEA showed the best performance. The electrochemical impedance measurements were in good agreement with the fuel cell polarization curves obtained, and the optimum performance was obtained when overall resistance was minimal.

Three-dimensional graphene as gas diffusion layer for micro direct methanol fuel cell

2018 ◽  
Vol 32 (12) ◽  
pp. 1850145 ◽  
Author(s):  
Yingli Zhu ◽  
Xiaojian Zhang ◽  
Jianyu Li ◽  
Gary Qi
Keyword(s):  
Fuel Cell ◽  
Diffusion Layer ◽  
Direct Methanol Fuel Cell ◽  
Three Dimensional ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Membrane Electrode ◽  
Transfer Resistance ◽  
Direct Methanol ◽  
Methanol Fuel Cell

The gas diffusion layer (GDL), as an important structure of the membrane electrode assembly (MEA) of the direct methanol fuel cell (DMFC), provides a support layer for the catalyst and the fuel and the product channel. Traditionally, the material of GDL is generally carbon paper (CP). In this paper, a new material, namely three-dimensional graphene (3DG) is used as GDL for micro DMFC. The experimental results reveal that the performance of the DMFC has been improved significantly by application of 3DG. The peak powers increase from 25 mW to 31.2 mW and 32 mW by using 3DG as the anode and cathode GDL instead of CP, respectively. The reason may be the decrease of charge and mass transfer resistance of the cell. This means that the unique 3D porous architecture of the 3DG can provide lower contact resistance and sufficient fuel diffusion paths. The output performance of the cell will be further improved when porous metal current collectors is used.

Understanding of Nafion Membrane Additive Behaviors in Proton Exchange Membrane Fuel Cell Conditioning

2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Nana Zhao ◽  
Zhong Xie ◽  
Zhiqing Shi
Keyword(s):  
Fuel Cell ◽  
Large Scale ◽  
Proton Exchange Membrane ◽  
Electrochemical Impedance ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Production Volume ◽  
Transfer Resistance ◽  
Conditioning Process ◽  
Exchange Membrane

Durability and cost are the two major factors limiting the large-scale implementation of fuel cell technology for use in commercial, residential, or transportation applications. The conditioning cost is usually negligible for making proton exchange membrane fuel cells (PEMFCs) at R&D or demo stage with several tens of stacks each year. However, with industry's focus shifting from component development to commercial high-volume manufacturing, the conditioning process requires significant additional capital investments and operating costs, thus becomes one of the bottlenecks for PEMFC manufacturing, particularly at a high production volume (>1000 stack/year). To understand the mechanisms behind PEMFC conditioning, and to potentially reduce conditioning time or even to eliminate the conditioning process, the conditioning behaviors of commercial Nafion™ XL100 and Nafion® NRE 211 membranes were studied. The potential effects of the membrane additive on fuel cell conditioning were diagnosed using in situ electrochemical impedance spectroscopy (EIS). It was found that the membrane additive led to the significant variation of the charge transfer resistance in EIS during conditioning, which affected the conditioning behavior of the membrane electrode assembly (MEA).

Probing the influence of the gas diffusion layer on water retention in membrane electrode assemblies via electrochemical impedance spectroscopy

2018 ◽  
Author(s):  
Foroughazam Afsahi ◽  
E. Bradley Easton
Keyword(s):  
Fuel Cell ◽  
Electrochemical Impedance ◽  
Catalyst Layer ◽  
Pem Fuel Cell ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Carbon Paper ◽  
Membrane Electrode ◽  
Fuel Cell Performance ◽  
Electrode Assemblies

The effect of the relative humidity (RH) of supplied gases on PEM fuel cell performance was monitored by electrochemical impedance spectroscopy (EIS). Two different Nafion®-based membrane electrode assemblies (MEAs) were prepared from two commercially available gas diffusion layers (GDLs) based on carbon paper and carbon cloth. By performing EIS measurements under condition where the transmission line model was applicable, both the ionic resistance in catalyst layer (RΣ) and the membrane resistance (Rmem) could be probed. The extent of this impact, however, depends on the GDL substrate properties and the electrode side to which the dry gas was fed. Overall, the carbon paper based MEA provided better fuel cell performance when the dry gas condition was applied, whereas the cloth based MEA revealed better fuel cell performance with fully saturated reactant gases. Moreover, the later one demonstrates a better capability to address the flooding issue at high current density even when symmetric dry gas arrangement (both dry fuel and oxidant gases) was studied. Variation of fuel gas RH at the anode perturb the fuel cell performance less strongly compared with the other arrangements. This implies that with the fully hydrated cathode gas water transport via back diffusion from the cathode to the anode could maintain the hydrated membrane and catalyst layer to some extent. By using this EIS methodology, the interplay of GDL properties and reactant gases RH on PEM fuel cell performance can be more clearly understood.

Modeling Water Content Distribution in the Polymer Electrolyte Membrane of PEM Fuel Cell

2011 ◽  
Author(s):  
Bahareh Alsadat Tavakoli ◽  
Ramin Roshandel
Keyword(s):  
Fuel Cell ◽  
Water Content ◽  
Current Density ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Cell Polarization ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Isothermal Model

Models play an important role in fuel cell design and development. One of the critical problems to overcome in the proton exchange membrane (PEM) fuel cells is the water management. In this work a steady state, two dimensional, isothermal model in a single PEM fuel cell using individual computational fluid dynamics code was presented. Special attention was devoted to the water transport through the membrane which is assumed to be combined effect of diffusion, electro osmotic drag and convection. The effect of current density variation distribution on the Water content (λ) in membrane/electrode assembly (MEA) was determined. After that detailed distribution of oxygen concentration, water content in membrane, net water flux and different overpotentials were calculated. Simulation results show that the reduction of reactant concentration in flow channels has a significant effect on electrochemical reaction in the gas diffusion and catalyst layer. Different fluxes are compared to investigate the effect of operating condition on the water fluxes in membrane. The amount of different fluxes is a strong function of current density which is related to external load. The model prediction of water content curves are compared with one dimensional model predictions data reported in the validated open literature and good compatibility were observed. In addition, the model predicted fuel cell polarization curves compared well with experimental and numerical data.

scholarly journals Unprecedented SPEEK-trimetal Oxide Composites: Physicochemical and Electrochemical Performance in Fuel Cell

2021 ◽  
Author(s):  
Gandhimathi Sivasubramanian ◽  
Senthil Andavan Gurusamy Thangavelu ◽  
Berlina Maria Mahimai ◽  
Krishnan Hariharasubramanian ◽  
PARADESI DEIVANAYAGAM
Keyword(s):  
Fuel Cell ◽  
Electrochemical Performance ◽  
Composite Membrane ◽  
Composite Membranes ◽  
Membrane Electrode Assembly ◽  
Membrane Electrode ◽  
Ether Ether Ketone ◽  
Poly Ether Ether Ketone ◽  
Maximum Water ◽  
Oxide Composites

Abstract Advanced polymer composite membranes were prepared from a linear sulfonated poly(ether ether ketone) (SPEEK) with bismuth cobalt zinc oxide [BCZO, (Bi2O3)0.07(CoO)0.03(ZnO)0.90] nanopowder as an inorganic additive for the application of H2-O2 fuel cell. Morphology data tend to provide evidences for the incorporation of BCZO into SPEEK polymer. Indeed, composite membrane loaded with 7.5 wt.% of BCZO was identified to uptake maximum water, while the pristine SPEEK membrane occurred to retain only 24.0 %. As such SPEEK matrix loaded with 7.5 wt.% of BCZO was found to exhibit the maximum proton conductivity of 0.030 S cm-1, whereas the pristine membrane was restricted to 0.021 S cm-1. Evidently, TGA profile of the composite membrane was measured to exhibit sufficient thermal stability to employ as electrolyte in fuel cell. The membrane electrode assembly of pristine SPEEK and SP-BCZO-7.5 wt.% membranes were fabricated and studied for their electrochemical performance. Indeed, the characteristics of newly developed composite membranes led to possess incredible feature towards fuel cell applications.

Investigation of Thermal Influence on the Assembly of Polymer Electrolyte Membrane Fuel Cell Stacks

2012 ◽  
Vol 512-515 ◽  
pp. 1509-1514
Author(s):  
Lin Fa Peng ◽  
Dian Kai Qiu ◽  
Pei Yun Yi ◽  
Xin Min Lai
Keyword(s):  
Thermal Expansion ◽  
Fuel Cell ◽  
Contact Pressure ◽  
Proton Exchange Membrane ◽  
Three Dimensional ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Fe Model ◽  
Assembly Process

The assembly force in a proton exchange membrane fuel cell (PEMFC) stack affects the characteristics of the porosity and electrical conductivity. Generally, the stack is assembled at room temperature while it’s operated at about 80 °Cor even higher. As a result, the assembly pressure can’t keep constant due to thermal expansion. This paper focuses on the contact pressure between membrane electrode assembly (MEA) and bipolar plates in real operations. A three-dimensional finite element (FE) model for the assembly process is established with coupled thermal-mechanical effects. The discipline of contact pressure under thermal-mechanical effect is investigated. A single cell stack is fabricated in house for the analysis of contact pressures on gas diffusion layer at different temperatures. The results show that as the temperature increases, contact pressure increases due to thermal expansion. It indicates that the influence of thermal expansion due to temperature variation should be taken into consideration for the design of the stack assembly process.

Study on the Durability Comparsion of STS316 Non-Coated and CrN Coated for Metallic Bipolar Plate

2012 ◽  
Vol 538-541 ◽  
pp. 402-405
Author(s):  
M.S. Moon ◽  
Kee Do Woo ◽  
J.H. Oh ◽  
J.H. Song ◽  
S.J. Kang ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Bipolar Plate ◽  
High Energy ◽  
Transportation System ◽  
Gas Diffusion ◽  
Machining Process ◽  
Membrane Electrode ◽  
Light Weight ◽  
Plate Material ◽  
New Energy

Nowadays, many economists and scientist worry about sharply increased to fuel consumption. New energy sources have to be investigation now. This was a base on the low-emission gas, high-energy efficiency, permanence and possible with co-generation. Especially, transportation system has been restricted to system’s total weight. Light weight of a transportation system offers to increase performance. By using light weight in a transportation system, it gives another benefit that reduced oil consumption, improved fuel efficiency and increased Market-value. Fuel cell is one of the new energy systems for next generation. Normally, fuel cell consists of bipolar plate, MEA (Membrane Electrode Assembly) and GDL (Gas Diffusion Layer). Conventional bipolar plate material was used to graphite. Graphite has been very weak at external shock. Machining process is not easy, and the main problem is that the graphite material supplied by oxidizing and reducing agent composition of the gas leak comes. Thus, the manufacturing cost is increased by this reason. This study will be tried to bipolar plate material replacement from graphite materials to metallic material. In this experiment, STS316 base on austenite stainless steel was used. This experiment was observing an effect of surface conditions with corrosion behavior with Non-coated and CrN coated STS316 on a similar PEMFC operating condition. By the results of experimental, CrN coated condition has better corrosion resistance than that of Non-coated condition due to passivation layer on CrN coated surface.

Design and Testing of a Unitized Regenerative Fuel Cell

2009 ◽  
Vol 6 (3) ◽  
Author(s):  
Jeremy Fall ◽  
Drew Humphreys ◽  
S. M. Guo
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Platinum Catalyst ◽  
Oxygen Electrode ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Hydrogen Electrode ◽  
Iridium Catalysts ◽  
Regenerative Fuel Cell

A unitized regenerative fuel cell (URFC) is designed and tested for energy conversion and storage under the support of a NASA funded student design project. The URFC is of the proton exchange membrane type with an active cell area of 25cm2. In the URFC design, liquid water is stored internally to the fuel cell within graphite bipolar plates while hydrogen and oxygen gases, electrolyzed from water, are stored in containers external to the fuel cell. A spraying technique is used to produce a functional membrane electrode assembly. Catalyst ink is prepared using E-TEK Inc. platinum and iridium catalysts loaded on Vulcan XC-72. Platinum catalyst is used for the hydrogen electrode. 50wt% platinum∕50wt% iridium catalyst is used for the oxygen electrode. The metal weight on carbon is 30% for both the platinum and iridium catalysts. Water management within the fuel cell is handled by treatment of the gas diffusion layer with a Teflon emulsion to create the proper balance of hydrophobic and hydrophilic pores. The single cell unit is tested in either fuel cell mode or electrolysis mode for different catalyst loadings. Polarization curves for the URFC are generated to evaluate system performance.

scholarly journals Performance and Ethanol Crossover of Passive Direct Ethanol Fuel Cell Stack

2020 ◽  
Vol 141 ◽  
pp. 01008
Author(s):  
Panuwat Ekdharmasuit
Keyword(s):  
Fuel Cell ◽  
Electrochemical Impedance ◽  
Cell Structure ◽  
Cell Polarization ◽  
Cell Performance ◽  
Feed Concentration ◽  
Ethanol Fuel ◽  
Direct Ethanol Fuel Cell ◽  
Term Operation

A dual-cell passive direct ethanol fuel cell (DEFC) stack with single ethanol tank was designed and tested to obtain the voltage requirement of electronics and to reduce weight and volume for practical applications. Ethanol crossover and cell performance were determined at different ethanol feed concentrations. Characterization techniques were used, including a cell polarization tests, a long-term steady voltage discharging measurement, and an electrochemical impedance spectroscopy (EIS). It was found that, before long-term steady voltage test, the optimum ethanol feed concentration was 2 M. The ethanol crossover increases with ethanol concentration increment over 2 M and the ethanol crossover exhibited a negative effect on the open circuit voltage (OCV) and the cell performance. However, after a long-term steady voltage test, the best ethanol feed concentration was changed to 3 M. It was due to the difference of current density discharged during long-term operation. It can also be found that, after long-term steady voltage test, the cell resistance was apparently reduced. It may be explained that the mass transport of both liquid fuel and air as a reactant in the cell structure reached equilibrium during long-term operation.

scholarly journals Optimization of Perfluoropolyether-Based Gas Diffusion Media Preparation for PEM Fuel Cells

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1831 ◽  
Author(s):  
Riccardo Balzarotti ◽  
Saverio Latorrata ◽  
Marco Mariani ◽  
Paola Gallo Stampino ◽  
Giovanni Dotelli
Keyword(s):  
Fuel Cell ◽  
Electrochemical Impedance ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Cathode Side ◽  
Porous Substrate ◽  
Materials Properties ◽  
Electrochemical Tests ◽  
Electrochemical Parameters ◽  
Diffusion Media

A hydrophobic perfluoropolyether (PFPE)-based polymer, namely Fluorolink® P56, was studied instead of the commonly used polytetrafluoroethylene (PTFE), in order to enhance gas diffusion media (GDM) water management behavior, on the basis of a previous work in which such polymers had already proved to be superior. In particular, an attempt to optimize the GDM production procedure and to improve the microporous layer (MPL) adhesion to the substrate was carried out. Materials properties have been correlated with production routes by means of both physical characterization and electrochemical tests. The latter were performed in a single PEM fuel cell, at different relative humidity (namely 80% on anode side and 60%/100% on cathode side) and temperature (60 °C and 80 °C) conditions. Additionally, electrochemical impedance spectroscopy measurements were performed in order to assess MPLs properties and to determine the influence of production procedure on cell electrochemical parameters. The durability of the best performing sample was also evaluated and compared to a previously developed benchmark. It was found that a final dipping step into PFPE-based dispersion, following MPL deposition, seems to improve the adhesion of the MPL to the macro-porous substrate and to reduce diffusive limitations during fuel cell operation.

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