The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Xiao-dong Wang - One of the best experts on this subject based on the ideXlab platform.

  • Effects of operating parameters on transport phenomena and Cell Performance of PEM fuel Cells with conventional and contracted flow field designs
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Xiao-dong Wang, Wei-mon Yan, Wen-chung Won, Duu-jong Lee
    Abstract:

    A contracted parallel flow field design was developed to improve fuel Cell Performance compared with the conventional parallel flow field design. A three-dimensional model was used to compare the Cell Performance for both designs. The effects of the cathode reactant inlet velocity and cathode reactant inlet relative humidity on the Cell Performance for both designs were also investigated. For operating voltages greater than 0.7 V because the electrochemical reaction rates are lower with less oxygen consumption and less liquid water production, the Cell Performance is independent of the flow field designs and operating parameters. However, for lower operating voltages where the electrochemical reaction rates gradually increase, the oxygen transport and the liquid water removal efficiency differ for the various flow field designs and operating parameters; therefore, the Cell Performance is strongly dependent on both the design and operating parameters. For lower operating voltages, the Cell Performance for the contracted design is better than for the conventional design because the reactant flow velocities in the contracted region significantly increase, which enhances liquid water removal and reduces the oxygen transport resistance. For lower operating voltages, as the cathode reactant inlet velocity increases and the cathode reactant inlet relative humidity decreases, the Cell Performance for both designs improves.

  • effects of serpentine flow field with outlet channel contraction on Cell Performance of proton exchange membrane fuel Cells
    Journal of Power Sources, 2008
    Co-Authors: Wei-mon Yan, Pochiao Chiu, Xiao-dong Wang
    Abstract:

    A serpentine flow field with outlet channels having modified heights or lengths was designed to improve reactant utilization and liquid water removal in proton exchange membrane (PEM) fuel Cells. A three-dimensional full-Cell model was developed to analyze the effects of the contraction ratios of height and length on the Cell Performance. Liquid water formation, that influences the transport phenomena and Cell Performance, was included in the model. The predictions show that the reductions of the outlet channel flow areas increase the reactant velocities in these regions, which enhance reactant transport, reactant utilization and liquid water removal; therefore, the Cell Performance is improved compared with the conventional serpentine flow field. The predictions also show that the Cell Performance is improved by increments in the length of the reduced flow area, besides greater decrements in the outlet flow area. If the power losses due to pressure drops are not considered, the Cell Performance with the contracted outlet channel flow areas continues to improve as the outlet flow areas are reduced and the lengths of the reduced flow areas are increased. When the pressure losses are also taken into account, the optimal Performance is obtained at a height contraction ratio of 0.4 and a length contraction ratio of 0.4 in the present design.

  • local transport phenomena and Cell Performance of pem fuel Cells with various serpentine flow field designs
    Journal of Power Sources, 2008
    Co-Authors: Xiao-dong Wang, Yuanyuan Duan, Xiaofeng Peng
    Abstract:

    The flow field design in bipolar plates is very important for improving reactant utilization and liquid water removal in proton exchange membrane fuel Cells (PEMFCs). A three-dimensional model was used to analyze the effect of the design parameters in the bipolar plates, including the number of flow channel bends, number of serpentine flow channels and the flow channel width ratio, on the Cell Performance of miniature PEMFCs with the serpentine flow field. The effect of the liquid water formation on the porosities of the porous layers was also taken into account in the model while the complex two-phase flow was neglected. The predictions show that (1) for the single serpentine flow field, the Cell Performance improves as the number of flow channel bends increases; (2) the single serpentine flow field has better Performance than the double and triple serpentine flow fields; (3) the Cell Performance only improves slowly as the flow channel width increases. The effects of these design parameters on the Cell Performance were evaluated based on the local oxygen mass flow rates and liquid water distributions in the Cells. Analysis of the pressure drops showed that for these miniature PEMFCs, the energy losses due to the pressure drops can be neglected because they are far less than the Cell output power.

  • Numerical Simulation of Cell Performance in Proton Exchange Membrane Fuel Cells with Contracted Flow Field Design
    Journal of The Electrochemical Society, 2008
    Co-Authors: Wen-chung Weng, Wei-mon Yan, Xiao-dong Wang
    Abstract:

    The Cell Performance and transport phenomena in a proton exchange membrane fuel Cell were analyzed numerically for Cells with flow channels that are contracted at the outlet. The effects of various outlet contraction ratios and the liquid water production are examined in detail. The predicted results show that, for operating voltages higher than 0.7 V, the effect of the flow field design on the Cell Performance is not significant due to the weaker electrochemical reaction. However, for operating voltages lower than 0.7 V, the flow field design significantly affects the Cell Performance. The contracted channel design forces the reactants to flow into the gas diffusion layer and the catalyst layer, which enhances liquid water removal and increases reactant utilization, so the Cell Performance is improved compared with the conventional design. In addition, the Cell Performance increases with either decreasing the height contraction ratio or decreasing the length contraction ratio, with the decreasing length contraction ratio being preferred to the decreasing height contraction ratio due to the smaller pressure drops.

  • Effect of humidity of reactants on the Cell Performance of PEM fuel Cells with parallel and interdigitated flow field designs
    Journal of Power Sources, 2008
    Co-Authors: Xiao-dong Wang, Wei-mon Yan, Yuanyuan Duan, Fang-bor Weng
    Abstract:

    Abstract This study investigates the effects of the relative humidity (RH) of the reactants on the Cell Performance and local transport phenomena in proton exchange membrane fuel Cells with parallel and interdigitated flow fields. A three-dimensional model was developed taking into account the effect of the liquid water formation on the reactant transport. The results indicate that the reactant RH and the flow field design all significantly affect Cell Performance. For the same operating conditions and reactant RH, the interdigitated design has better Cell Performance than the parallel design. With a constant anode RH = 100%, for lower operating voltages, a lower cathode RH reduces cathode flooding and improves Cell Performance, while for higher operating voltages, a higher cathode RH maintains the membrane hydration to give better Cell Performance. With a constant cathode RH = 100%, for lower operating voltages, a lower anode RH not only provides more hydrogen to the catalyst layer to participate in the electrochemical reaction, but also increases the difference in the water concentrations between the anode and cathode, which enhances back-diffusion of water from the cathode to the anode, thus reducing cathode flooding to give better Performance. However, for higher operating voltages, the Cell Performance is not dependent on the anode RH.

Trent Molter - One of the best experts on this subject based on the ideXlab platform.

  • Effect of cationic contaminants on polymer electrolyte fuel Cell Performance
    Journal of Power Sources, 2015
    Co-Authors: Xiaofeng Wang, Ugur Pasaogullari, Ozan Ozdemir, Aman Uddin, Leonard J. Bonville, Trent Molter
    Abstract:

    Abstract The effect of cationic contaminants on polymer electrolyte fuel Cell (PEFC) Performance is investigated via in-situ injection of dilute cationic salt solutions. Four foreign cations (K + , Ba 2+ , Ca 2+ , Al 3+ ) are chosen as contaminants in this study due to their prevalence and chemical structure (e.g. valence), however contaminants that have already received extensive coverage in the literature like sodium and iron are excluded. It is found that the Cells with Ba(ClO 4 ) 2 and Ca(ClO 4 ) 2 injection exhibit little Cell Performance change during the current hold test, and the Cells with Al(ClO 4 ) 3 and KClO 4 injection show larger Cell Performance changes, i.e. decreasing Cell voltage and increasing Cell resistance. These Cells with in-situ contaminant injection have a tendency to recover a portion of the lost Performance after the recovery test when switched back to supersaturated air. The degradation in Cell Performance with the presence of cationic contaminants is mainly due, in addition to the membrane resistance increase associated with replacing protons on the sulfonate groups, to the increase in mass transport resistance and decrease in electrochemical surface area.

  • Effect of Al3+ Contaminant on Polymer Electrolyte Fuel Cell Performance
    Journal of The Electrochemical Society, 2013
    Co-Authors: Xiaofeng Wang, Ugur Pasaogullari, Leonard J. Bonville, Trent Molter
    Abstract:

    To correlate the cationic contaminant uptake of the catalyst coated membrane (CCM) with the polymer electrolyte fuel Cell (PEFC) Performance, CCMs were contaminated by saturating in varying concentrations of H2SO4 and Al2(SO4)3 solution, establishing ex-situ equilibrium cation uptake. The CCMs were then assembled and tested in single Cell hardware to determine the Performance as a function of cationic contamination level. Smaller CCM coupons were also saturated at the same time as the full-size CCM and were characterized by acid site titration to determine the cationic occupation fraction. It is found that the acid site occupation in the CCM increased and the Cell Performance decreased with increased Al ion concentration in the solution. With less than 10% occupation, the Cell Performance dropped from 1000 mA/cm 2 to 100 mA/cm 2 at 0.6 V. Upon re–protonation of the CCM with

  • Influence of Formic Acid Impurity on Proton Exchange Membrane Fuel Cell Performance
    Journal of The Electrochemical Society, 2010
    Co-Authors: Xiaoyu Zhang, Hugo Galindo, Philip Baker, Hector F. Garces, Ugur Pasaogullari, Steven L. Suib, Xiaofeng Wang, Trent Molter
    Abstract:

    The effect of trace amounts of formic acid (HCOOH) in hydrogen fuel on proton exchange membrane fuel Cell (PEMFC) Performance is reported. Long-term stability tests (100 h), periodic cyclic voltammetry scans, and electrochemical impedance spectroscopy analyses are used to evaluate and characterize the effects of this impurity on fuel Cell Performance. The results show that trace amounts of HCOOH cause degradation in fuel Cell Performance and significantly contaminate the electrodes. Furthermore, full recovery from the contamination could not be achieved by applying pure hydrogen to the anode while operating the fuel Cell. However, this degradation may also be caused by the coarsening or dissolution of Pt, in addition to any permanent effects of HCOOH contamination. Mechanisms of contamination of the electrodes and Performance degradation of the PEMFC are also postulated.

  • Influence of Formic Acid Impurity on Proton Exchange Membrane Fuel Cell Performance
    Journal of The Electrochemical Society, 2010
    Co-Authors: Xiaoyu Zhang, Hugo Galindo, Philip Baker, Hector F. Garces, Ugur Pasaogullari, Steven L. Suib, Xiaofeng Wang, Trent Molter
    Abstract:

    The effect of trace amounts of formic acid (HCOOH) in hydrogen fuel on proton exchange membrane fuel Cell (PEMFC) Performance is reported. Long-term stability tests (100 h), periodic cyclic voltammetry scans, and electrochemical impedance spectroscopy analyses are used to evaluate and characterize the effects of this impurity on fuel Cell Performance. The results show that trace amounts of HCOOH cause degradation in fuel Cell Performance and significantly contaminate the electrodes. Furthermore, full recovery from the contamination could not be achieved by applying pure hydrogen to the anode while operating the fuel Cell. However, this degradation may also be caused by the coarsening or dissolution of Pt, in addition to any permanent effects of HCOOH contamination. Mechanisms of contamination of the electrodes and Performance degradation of the PEMFC are also postulated.

Wei-mon Yan - One of the best experts on this subject based on the ideXlab platform.

  • Cell Performance of ABPBI-Based High Temperature PEM Fuel Cells
    Applied Mechanics and Materials, 2012
    Co-Authors: Wei-mon Yan, Hsin Hung Chen, Guo Bin Jung, Chun I Lee, Chang Chung Yang
    Abstract:

    In this work, the Cell Performance of high temperature PEM fuel Cells based on ABPBI membranes was experimentally measured in details. The ABPBI-based high PEM fuel Cell was fabricated by using ABPBI-based gas diffusion electrodewith directly adding carbon-supported- catalyst to a homogeneous ABPBI solution prior to deposition and its membrane electrode assembly. The effects of various Pt loading of the catalyst layer, as well as the effect of different operating conditions were studied. The Cell Performance was evaluated using dry hydrogen/oxygen gases, which added advantage of eliminating the complicated humidification system of nafion Cells. The measured results reveal that a catalyst layer with the higher Pt loading has a higher Cell Performance. In addition, better Cell Performance is noted for a case with higher Cell temperature or higher cathode flowrate.

  • Effects of operating parameters on transport phenomena and Cell Performance of PEM fuel Cells with conventional and contracted flow field designs
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Xiao-dong Wang, Wei-mon Yan, Wen-chung Won, Duu-jong Lee
    Abstract:

    A contracted parallel flow field design was developed to improve fuel Cell Performance compared with the conventional parallel flow field design. A three-dimensional model was used to compare the Cell Performance for both designs. The effects of the cathode reactant inlet velocity and cathode reactant inlet relative humidity on the Cell Performance for both designs were also investigated. For operating voltages greater than 0.7 V because the electrochemical reaction rates are lower with less oxygen consumption and less liquid water production, the Cell Performance is independent of the flow field designs and operating parameters. However, for lower operating voltages where the electrochemical reaction rates gradually increase, the oxygen transport and the liquid water removal efficiency differ for the various flow field designs and operating parameters; therefore, the Cell Performance is strongly dependent on both the design and operating parameters. For lower operating voltages, the Cell Performance for the contracted design is better than for the conventional design because the reactant flow velocities in the contracted region significantly increase, which enhances liquid water removal and reduces the oxygen transport resistance. For lower operating voltages, as the cathode reactant inlet velocity increases and the cathode reactant inlet relative humidity decreases, the Cell Performance for both designs improves.

  • effects of serpentine flow field with outlet channel contraction on Cell Performance of proton exchange membrane fuel Cells
    Journal of Power Sources, 2008
    Co-Authors: Wei-mon Yan, Pochiao Chiu, Xiao-dong Wang
    Abstract:

    A serpentine flow field with outlet channels having modified heights or lengths was designed to improve reactant utilization and liquid water removal in proton exchange membrane (PEM) fuel Cells. A three-dimensional full-Cell model was developed to analyze the effects of the contraction ratios of height and length on the Cell Performance. Liquid water formation, that influences the transport phenomena and Cell Performance, was included in the model. The predictions show that the reductions of the outlet channel flow areas increase the reactant velocities in these regions, which enhance reactant transport, reactant utilization and liquid water removal; therefore, the Cell Performance is improved compared with the conventional serpentine flow field. The predictions also show that the Cell Performance is improved by increments in the length of the reduced flow area, besides greater decrements in the outlet flow area. If the power losses due to pressure drops are not considered, the Cell Performance with the contracted outlet channel flow areas continues to improve as the outlet flow areas are reduced and the lengths of the reduced flow areas are increased. When the pressure losses are also taken into account, the optimal Performance is obtained at a height contraction ratio of 0.4 and a length contraction ratio of 0.4 in the present design.

  • Numerical Simulation of Cell Performance in Proton Exchange Membrane Fuel Cells with Contracted Flow Field Design
    Journal of The Electrochemical Society, 2008
    Co-Authors: Wen-chung Weng, Wei-mon Yan, Xiao-dong Wang
    Abstract:

    The Cell Performance and transport phenomena in a proton exchange membrane fuel Cell were analyzed numerically for Cells with flow channels that are contracted at the outlet. The effects of various outlet contraction ratios and the liquid water production are examined in detail. The predicted results show that, for operating voltages higher than 0.7 V, the effect of the flow field design on the Cell Performance is not significant due to the weaker electrochemical reaction. However, for operating voltages lower than 0.7 V, the flow field design significantly affects the Cell Performance. The contracted channel design forces the reactants to flow into the gas diffusion layer and the catalyst layer, which enhances liquid water removal and increases reactant utilization, so the Cell Performance is improved compared with the conventional design. In addition, the Cell Performance increases with either decreasing the height contraction ratio or decreasing the length contraction ratio, with the decreasing length contraction ratio being preferred to the decreasing height contraction ratio due to the smaller pressure drops.

  • Effect of humidity of reactants on the Cell Performance of PEM fuel Cells with parallel and interdigitated flow field designs
    Journal of Power Sources, 2008
    Co-Authors: Xiao-dong Wang, Wei-mon Yan, Yuanyuan Duan, Fang-bor Weng
    Abstract:

    Abstract This study investigates the effects of the relative humidity (RH) of the reactants on the Cell Performance and local transport phenomena in proton exchange membrane fuel Cells with parallel and interdigitated flow fields. A three-dimensional model was developed taking into account the effect of the liquid water formation on the reactant transport. The results indicate that the reactant RH and the flow field design all significantly affect Cell Performance. For the same operating conditions and reactant RH, the interdigitated design has better Cell Performance than the parallel design. With a constant anode RH = 100%, for lower operating voltages, a lower cathode RH reduces cathode flooding and improves Cell Performance, while for higher operating voltages, a higher cathode RH maintains the membrane hydration to give better Cell Performance. With a constant cathode RH = 100%, for lower operating voltages, a lower anode RH not only provides more hydrogen to the catalyst layer to participate in the electrochemical reaction, but also increases the difference in the water concentrations between the anode and cathode, which enhances back-diffusion of water from the cathode to the anode, thus reducing cathode flooding to give better Performance. However, for higher operating voltages, the Cell Performance is not dependent on the anode RH.

Ugur Pasaogullari - One of the best experts on this subject based on the ideXlab platform.

  • Effect of cationic contaminants on polymer electrolyte fuel Cell Performance
    Journal of Power Sources, 2015
    Co-Authors: Xiaofeng Wang, Ugur Pasaogullari, Ozan Ozdemir, Aman Uddin, Leonard J. Bonville, Trent Molter
    Abstract:

    Abstract The effect of cationic contaminants on polymer electrolyte fuel Cell (PEFC) Performance is investigated via in-situ injection of dilute cationic salt solutions. Four foreign cations (K + , Ba 2+ , Ca 2+ , Al 3+ ) are chosen as contaminants in this study due to their prevalence and chemical structure (e.g. valence), however contaminants that have already received extensive coverage in the literature like sodium and iron are excluded. It is found that the Cells with Ba(ClO 4 ) 2 and Ca(ClO 4 ) 2 injection exhibit little Cell Performance change during the current hold test, and the Cells with Al(ClO 4 ) 3 and KClO 4 injection show larger Cell Performance changes, i.e. decreasing Cell voltage and increasing Cell resistance. These Cells with in-situ contaminant injection have a tendency to recover a portion of the lost Performance after the recovery test when switched back to supersaturated air. The degradation in Cell Performance with the presence of cationic contaminants is mainly due, in addition to the membrane resistance increase associated with replacing protons on the sulfonate groups, to the increase in mass transport resistance and decrease in electrochemical surface area.

  • Impact of Interfacial Water Transport in PEMFCs on Cell Performance
    Electrochimica Acta, 2014
    Co-Authors: Toshikazu Kotaka, Ugur Pasaogullari, Yuichiro Tabuchi, Chaoyang Wang
    Abstract:

    Abstract Coupled Cell Performance evaluation, liquid water visualization by neutron radiography (NRG) and numerical modeling based on multiphase mixture (M2) model were performed with three types of GDMs: Micro Porous Layer (MPL) free; Carbon Paper (CP) with MPL; and CP free to investigate interfacial liquid water transport phenomena in PEMFCs and its effect on Cell Performance. The visualized results of MPL free GDM with different wettability of bi-polar plates (BPPs) showed hydrophilic BPP improved liquid water transport at the interface between CP and channel. Numerical modeling results indicated that this difference with BPP wettability was caused by the liquid water coverage difference on CP surface. Thus, controlling liquid water coverage is the one of the key strategies for improving Cell Performance. Additionally, liquid water distributions across the Cell for three types of GDMs were compared and significant difference in liquid water content at the interface between Catalyst Layer (CL) and GDM was observed. Numerical modeling suggests this difference is influenced by the gap at the interface and that the MPL could minimize this effect. The CP free Cell (i.e. only MPL) showed the best Performance and the lowest liquid water content. There were multiple impacts of interfacial liquid water transport both at CL-GDM and GDM-channel interfaces. High hydrophobicity and fine structure of MPLs contributed to enhanced liquid water transport at GDM-channel interface and as a result reduced the liquid water coverage. At the same time, MPL improves contact at the CL-GDM interface in the same manner as seen in CP with MPL case. Thus, the CP free concept showed the best Performance. It is suggested that the design of the interface between each component of the PEMFC has a great impact on Cell Performance and plays a significant role in achievement of high current density operation and cost reduction in FCEVs.

  • Effect of Al3+ Contaminant on Polymer Electrolyte Fuel Cell Performance
    Journal of The Electrochemical Society, 2013
    Co-Authors: Xiaofeng Wang, Ugur Pasaogullari, Leonard J. Bonville, Trent Molter
    Abstract:

    To correlate the cationic contaminant uptake of the catalyst coated membrane (CCM) with the polymer electrolyte fuel Cell (PEFC) Performance, CCMs were contaminated by saturating in varying concentrations of H2SO4 and Al2(SO4)3 solution, establishing ex-situ equilibrium cation uptake. The CCMs were then assembled and tested in single Cell hardware to determine the Performance as a function of cationic contamination level. Smaller CCM coupons were also saturated at the same time as the full-size CCM and were characterized by acid site titration to determine the cationic occupation fraction. It is found that the acid site occupation in the CCM increased and the Cell Performance decreased with increased Al ion concentration in the solution. With less than 10% occupation, the Cell Performance dropped from 1000 mA/cm 2 to 100 mA/cm 2 at 0.6 V. Upon re–protonation of the CCM with

  • Influence of Formic Acid Impurity on Proton Exchange Membrane Fuel Cell Performance
    Journal of The Electrochemical Society, 2010
    Co-Authors: Xiaoyu Zhang, Hugo Galindo, Philip Baker, Hector F. Garces, Ugur Pasaogullari, Steven L. Suib, Xiaofeng Wang, Trent Molter
    Abstract:

    The effect of trace amounts of formic acid (HCOOH) in hydrogen fuel on proton exchange membrane fuel Cell (PEMFC) Performance is reported. Long-term stability tests (100 h), periodic cyclic voltammetry scans, and electrochemical impedance spectroscopy analyses are used to evaluate and characterize the effects of this impurity on fuel Cell Performance. The results show that trace amounts of HCOOH cause degradation in fuel Cell Performance and significantly contaminate the electrodes. Furthermore, full recovery from the contamination could not be achieved by applying pure hydrogen to the anode while operating the fuel Cell. However, this degradation may also be caused by the coarsening or dissolution of Pt, in addition to any permanent effects of HCOOH contamination. Mechanisms of contamination of the electrodes and Performance degradation of the PEMFC are also postulated.

  • Influence of Formic Acid Impurity on Proton Exchange Membrane Fuel Cell Performance
    Journal of The Electrochemical Society, 2010
    Co-Authors: Xiaoyu Zhang, Hugo Galindo, Philip Baker, Hector F. Garces, Ugur Pasaogullari, Steven L. Suib, Xiaofeng Wang, Trent Molter
    Abstract:

    The effect of trace amounts of formic acid (HCOOH) in hydrogen fuel on proton exchange membrane fuel Cell (PEMFC) Performance is reported. Long-term stability tests (100 h), periodic cyclic voltammetry scans, and electrochemical impedance spectroscopy analyses are used to evaluate and characterize the effects of this impurity on fuel Cell Performance. The results show that trace amounts of HCOOH cause degradation in fuel Cell Performance and significantly contaminate the electrodes. Furthermore, full recovery from the contamination could not be achieved by applying pure hydrogen to the anode while operating the fuel Cell. However, this degradation may also be caused by the coarsening or dissolution of Pt, in addition to any permanent effects of HCOOH contamination. Mechanisms of contamination of the electrodes and Performance degradation of the PEMFC are also postulated.

Xiaofeng Wang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of cationic contaminants on polymer electrolyte fuel Cell Performance
    Journal of Power Sources, 2015
    Co-Authors: Xiaofeng Wang, Ugur Pasaogullari, Ozan Ozdemir, Aman Uddin, Leonard J. Bonville, Trent Molter
    Abstract:

    Abstract The effect of cationic contaminants on polymer electrolyte fuel Cell (PEFC) Performance is investigated via in-situ injection of dilute cationic salt solutions. Four foreign cations (K + , Ba 2+ , Ca 2+ , Al 3+ ) are chosen as contaminants in this study due to their prevalence and chemical structure (e.g. valence), however contaminants that have already received extensive coverage in the literature like sodium and iron are excluded. It is found that the Cells with Ba(ClO 4 ) 2 and Ca(ClO 4 ) 2 injection exhibit little Cell Performance change during the current hold test, and the Cells with Al(ClO 4 ) 3 and KClO 4 injection show larger Cell Performance changes, i.e. decreasing Cell voltage and increasing Cell resistance. These Cells with in-situ contaminant injection have a tendency to recover a portion of the lost Performance after the recovery test when switched back to supersaturated air. The degradation in Cell Performance with the presence of cationic contaminants is mainly due, in addition to the membrane resistance increase associated with replacing protons on the sulfonate groups, to the increase in mass transport resistance and decrease in electrochemical surface area.

  • Effect of Al3+ Contaminant on Polymer Electrolyte Fuel Cell Performance
    Journal of The Electrochemical Society, 2013
    Co-Authors: Xiaofeng Wang, Ugur Pasaogullari, Leonard J. Bonville, Trent Molter
    Abstract:

    To correlate the cationic contaminant uptake of the catalyst coated membrane (CCM) with the polymer electrolyte fuel Cell (PEFC) Performance, CCMs were contaminated by saturating in varying concentrations of H2SO4 and Al2(SO4)3 solution, establishing ex-situ equilibrium cation uptake. The CCMs were then assembled and tested in single Cell hardware to determine the Performance as a function of cationic contamination level. Smaller CCM coupons were also saturated at the same time as the full-size CCM and were characterized by acid site titration to determine the cationic occupation fraction. It is found that the acid site occupation in the CCM increased and the Cell Performance decreased with increased Al ion concentration in the solution. With less than 10% occupation, the Cell Performance dropped from 1000 mA/cm 2 to 100 mA/cm 2 at 0.6 V. Upon re–protonation of the CCM with

  • Influence of Formic Acid Impurity on Proton Exchange Membrane Fuel Cell Performance
    Journal of The Electrochemical Society, 2010
    Co-Authors: Xiaoyu Zhang, Hugo Galindo, Philip Baker, Hector F. Garces, Ugur Pasaogullari, Steven L. Suib, Xiaofeng Wang, Trent Molter
    Abstract:

    The effect of trace amounts of formic acid (HCOOH) in hydrogen fuel on proton exchange membrane fuel Cell (PEMFC) Performance is reported. Long-term stability tests (100 h), periodic cyclic voltammetry scans, and electrochemical impedance spectroscopy analyses are used to evaluate and characterize the effects of this impurity on fuel Cell Performance. The results show that trace amounts of HCOOH cause degradation in fuel Cell Performance and significantly contaminate the electrodes. Furthermore, full recovery from the contamination could not be achieved by applying pure hydrogen to the anode while operating the fuel Cell. However, this degradation may also be caused by the coarsening or dissolution of Pt, in addition to any permanent effects of HCOOH contamination. Mechanisms of contamination of the electrodes and Performance degradation of the PEMFC are also postulated.

  • Influence of Formic Acid Impurity on Proton Exchange Membrane Fuel Cell Performance
    Journal of The Electrochemical Society, 2010
    Co-Authors: Xiaoyu Zhang, Hugo Galindo, Philip Baker, Hector F. Garces, Ugur Pasaogullari, Steven L. Suib, Xiaofeng Wang, Trent Molter
    Abstract:

    The effect of trace amounts of formic acid (HCOOH) in hydrogen fuel on proton exchange membrane fuel Cell (PEMFC) Performance is reported. Long-term stability tests (100 h), periodic cyclic voltammetry scans, and electrochemical impedance spectroscopy analyses are used to evaluate and characterize the effects of this impurity on fuel Cell Performance. The results show that trace amounts of HCOOH cause degradation in fuel Cell Performance and significantly contaminate the electrodes. Furthermore, full recovery from the contamination could not be achieved by applying pure hydrogen to the anode while operating the fuel Cell. However, this degradation may also be caused by the coarsening or dissolution of Pt, in addition to any permanent effects of HCOOH contamination. Mechanisms of contamination of the electrodes and Performance degradation of the PEMFC are also postulated.