National Science Foundation: Nsf-fenton-poster
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November 14, 2001 NSF Workshop on Engineering Fundamentals of Low Temperature PEM Fuel Cells Washington DC
Preparation of High Temperature Composite Membranes and Membrane Electrode Assemblies for Hydrogen Proton Exchange Membrane Fuel Cells H. Russell Kunz and James M. Fenton University of Connecticut Leonard J. Bonville IONOMEM Corp.
PEMFCs above 100 oC and ambient pressure Advantages: • Improved CO-tolerance reduce fuel processing requirement • Accelerated reaction kinetics high performance • Easier water management simplify system design • Recovery of waste heat higher overall energy efficiency • Easier heat rejection higher driving force for heat transfer
Disadvantages: • Dehydration of membrane electrolyte for operation at 1 atm pressure higher ionic resistance • Dry-out of the catalyst layer for operation at 1 atm pressure low catalyst utilization 11/13/2001
University of Connecticut Proprietary Information
2
Work in Progress at UConn/IONOMEM • Scale-Up of MEAs • Optimization of MEAs • Material Characterization • Performance Characterization • Short Stack Development • Endurance Testing Composite membrane (based on Nafion® and solid proton conductor) —Nafion®-Teflon®-phosphotungstic acid (NTPA) —Nafion®-Teflon®-zirconium hydrogen phosphate (NTZP) —Nafion®-Zirconium hydrogen phosphate (NZP) Catalyst layer: —Optimize Proton Conduction —Optimize Mass Transfer Diffusion layer: —Enhance Gas Transfer —Optimize Hydrophilic/Hydrophobic Regions 11/13/2001
University of Connecticut Proprietary Information
3
Performance and Resistance of MEAs at 120 oC Using Hydrogen/Air anode and cathode humidifier temperature: 90 oC; anode: 3.4 stoich; cathode: 4 stoich
0.8 0.7 0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0.0
0
100
200
300
400
500
600
700
800
900
2
0.9
Voltage (V)
1.0
o
SOA Performance (Humidifier at 80 C) o SOA Resistance (Humidifier at 80 C) 0.9 UConn/IONOMEM NTPA Performance UConn/IONOMEM NTPA Resistance 0.8 UConn/IONOMEM NTZHP Performance UConn/IONOMEM NTZHP Resistance UConn/IONOMEM NTPA Performance Using UConn Substrates 0.7 UConn/IONOMEM NTPA Resistance Using UConn Substrates
Resistance (Ohm-cm )
1.0
0.0 1000
2
11/13/2001
Current Density (mA/cm )
University of Connecticut Proprietary Information
4
NZP Membrane Cell Performance with Different CO Concentrations at 120 oC (1 atm; H2+CO saturated at 90 oC, Pt-Ru/C/membrane/Pt/C,O2 saturated at 85 oC) 1.0
Cell Voltage (V)
0.8
0.6
0.8 2
pure H2 resistance with pure H2 H2+10.4 ppm CO resistance with 10.4ppm CO H2+52.4 ppm CO resistance with 52.4 ppm CO H2+104 ppm CO resistance with H2+104 ppm CO H2+196ppm CO resistance with H2+196ppm CO H2+485ppm CO resistance withH2+485ppm CO
0.6
0.4
0.4
0.2
0.2
0.0
0
200
400
600
800
1000
Resistance (Ohm-cm )
1.0
0.0 1200
Current density (mA/cm2)
11/13/2001
University of Connecticut Proprietary Information
5
Effect of Substrate on NZP MEA Performance at 70oC under Non-humidified Conditions Anode:1.3 stoich H2, Cathode:1.5 stoich air; Membrane:1mil NTZP membrane UConn substrate:8.7mil; ETEK 2.11:14mil 1.0
0.8
Perf. with UConn substrate Resistance with UConn substrate Perf. with ETEK 2.11 0.8 Resistance with ETEK 2.11 o Perf. with fully hydrated Membrane (humidifier at 70 C) Resistance with fully hydrated Membrane (humidifier at 70 oC)
0.6
0.6
0.4
0.4
0.2
0.2
0.0
0.0 1400
0
200
400
600
800
1000
1200
Resistance(Ohm-cm2)
Cell Voltage(V)
1.0
Current density(mA/cm2) 11/13/2001
University of Connecticut Proprietary Information
6
Summary • NTPA, NTZP and NZP MEAs > 100 oC higher ionic conductance better performance show CO tolerance • NTPA and NTZP Membranes meet specific US DOE goals above 100 oC thickness (<3mil), resistance, low gas permeability, high mechanical strength, good stability, good dimensional stability • NTPA, NTZP and NZP MEAs enable PEMFCs to reach US DOE building cogeneration goals simplify natural gas processing, 35 % system efficiency, less than 1.5 atm pressure, simple construction 11/13/2001
University of Connecticut Proprietary Information
7
UConn Research in PEM Fuel Cells • • • • • • • • • • 11/13/2001
Methanol Oxidation Electrocatalysts CO Tolerance Electrocatalysts Hydrogen Purification Process (recent NSF Funding) Low Methanol Crossover Membranes High Temperature Membranes Membranes Needing No External Humidification Selective Oxidation Catalysts Reversible PEM Fuel Cells Biomass and Landfill Gas Fuel Processing Design of PEM FC Powered Toys University of Connecticut Proprietary Information
8
Preparation of High Temperature Composite Membranes and Membrane Electrode Assemblies for Hydrogen Proton Exchange Membrane Fuel Cells H. Russell Kunz and James M. Fenton University of Connecticut Leonard J. Bonville IONOMEM Corp.
PEMFCs above 100 oC and ambient pressure Advantages: • Improved CO-tolerance reduce fuel processing requirement • Accelerated reaction kinetics high performance • Easier water management simplify system design • Recovery of waste heat higher overall energy efficiency • Easier heat rejection higher driving force for heat transfer
Disadvantages: • Dehydration of membrane electrolyte for operation at 1 atm pressure higher ionic resistance • Dry-out of the catalyst layer for operation at 1 atm pressure low catalyst utilization 11/13/2001
University of Connecticut Proprietary Information
2
Work in Progress at UConn/IONOMEM • Scale-Up of MEAs • Optimization of MEAs • Material Characterization • Performance Characterization • Short Stack Development • Endurance Testing Composite membrane (based on Nafion® and solid proton conductor) —Nafion®-Teflon®-phosphotungstic acid (NTPA) —Nafion®-Teflon®-zirconium hydrogen phosphate (NTZP) —Nafion®-Zirconium hydrogen phosphate (NZP) Catalyst layer: —Optimize Proton Conduction —Optimize Mass Transfer Diffusion layer: —Enhance Gas Transfer —Optimize Hydrophilic/Hydrophobic Regions 11/13/2001
University of Connecticut Proprietary Information
3
Performance and Resistance of MEAs at 120 oC Using Hydrogen/Air anode and cathode humidifier temperature: 90 oC; anode: 3.4 stoich; cathode: 4 stoich
0.8 0.7 0.6
0.6
0.5
0.5
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0.0
0
100
200
300
400
500
600
700
800
900
2
0.9
Voltage (V)
1.0
o
SOA Performance (Humidifier at 80 C) o SOA Resistance (Humidifier at 80 C) 0.9 UConn/IONOMEM NTPA Performance UConn/IONOMEM NTPA Resistance 0.8 UConn/IONOMEM NTZHP Performance UConn/IONOMEM NTZHP Resistance UConn/IONOMEM NTPA Performance Using UConn Substrates 0.7 UConn/IONOMEM NTPA Resistance Using UConn Substrates
Resistance (Ohm-cm )
1.0
0.0 1000
2
11/13/2001
Current Density (mA/cm )
University of Connecticut Proprietary Information
4
NZP Membrane Cell Performance with Different CO Concentrations at 120 oC (1 atm; H2+CO saturated at 90 oC, Pt-Ru/C/membrane/Pt/C,O2 saturated at 85 oC) 1.0
Cell Voltage (V)
0.8
0.6
0.8 2
pure H2 resistance with pure H2 H2+10.4 ppm CO resistance with 10.4ppm CO H2+52.4 ppm CO resistance with 52.4 ppm CO H2+104 ppm CO resistance with H2+104 ppm CO H2+196ppm CO resistance with H2+196ppm CO H2+485ppm CO resistance withH2+485ppm CO
0.6
0.4
0.4
0.2
0.2
0.0
0
200
400
600
800
1000
Resistance (Ohm-cm )
1.0
0.0 1200
Current density (mA/cm2)
11/13/2001
University of Connecticut Proprietary Information
5
Effect of Substrate on NZP MEA Performance at 70oC under Non-humidified Conditions Anode:1.3 stoich H2, Cathode:1.5 stoich air; Membrane:1mil NTZP membrane UConn substrate:8.7mil; ETEK 2.11:14mil 1.0
0.8
Perf. with UConn substrate Resistance with UConn substrate Perf. with ETEK 2.11 0.8 Resistance with ETEK 2.11 o Perf. with fully hydrated Membrane (humidifier at 70 C) Resistance with fully hydrated Membrane (humidifier at 70 oC)
0.6
0.6
0.4
0.4
0.2
0.2
0.0
0.0 1400
0
200
400
600
800
1000
1200
Resistance(Ohm-cm2)
Cell Voltage(V)
1.0
Current density(mA/cm2) 11/13/2001
University of Connecticut Proprietary Information
6
Summary • NTPA, NTZP and NZP MEAs > 100 oC higher ionic conductance better performance show CO tolerance • NTPA and NTZP Membranes meet specific US DOE goals above 100 oC thickness (<3mil), resistance, low gas permeability, high mechanical strength, good stability, good dimensional stability • NTPA, NTZP and NZP MEAs enable PEMFCs to reach US DOE building cogeneration goals simplify natural gas processing, 35 % system efficiency, less than 1.5 atm pressure, simple construction 11/13/2001
University of Connecticut Proprietary Information
7
UConn Research in PEM Fuel Cells • • • • • • • • • • 11/13/2001
Methanol Oxidation Electrocatalysts CO Tolerance Electrocatalysts Hydrogen Purification Process (recent NSF Funding) Low Methanol Crossover Membranes High Temperature Membranes Membranes Needing No External Humidification Selective Oxidation Catalysts Reversible PEM Fuel Cells Biomass and Landfill Gas Fuel Processing Design of PEM FC Powered Toys University of Connecticut Proprietary Information
8
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