high-performance fuel cell membranes arumugam manthiram the university of texas at austin
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High-Performance Fuel Cell High-Performance Fuel Cell
MembranesMembranes
Arumugam ManthiramArumugam Manthiram
The University of Texas at AustinThe University of Texas at Austin
Energy outlookEnergy outlook
Energy is the greatest challenge facing humankind in the Energy is the greatest challenge facing humankind in the 21st century.21st century.
Important societal issue, impacts our way of life, the Important societal issue, impacts our way of life, the economy, national security, environment, and our healtheconomy, national security, environment, and our health
Current production cannot keep up with rising needs.Current production cannot keep up with rising needs. Alternative, sustainable, clean energy technologies are Alternative, sustainable, clean energy technologies are
necessary.necessary.
Annual Energy Outlook 2005, http://www.eia.doe.gov/oiaf/aeo/index.html
Why fuel cells?Why fuel cells?
Modular, local• Watt to megawatt power
High power density and high efficiency (60%)• No Carnot limitation
Environmentally friendly• Clean energy• Quiet
Heat
Heat
ElectrolyteAnode Cathode
e-
2e-Air
1/2O2
H+
conductor
H2
O
2e-
+H2 2H+
H2O
H2
e- ~ 0.7 V
H2 + ½ O2 H2O + Electricity + Heat
Catalyst
< 100°C
Current technology commercialization is hampered by high cost, durability, and operability problems linked to materials issues (primarily membranes and catalysts)• Operating temperature <100°C• Humidification requirements• Methanol crossover • High cost
ElectrolyteAnode Cathode
2e-
2e-
1/2O2
H+ or O2-
conductor
H2O
2e-
+H22H+
CH3OH
or
CH4
Challenges of current Challenges of current fuel cell technologiesfuel cell technologies
Membrane High cost of Nafion membrane Limited to < 100°C as it needs to be wet Complex external humidification system Methanol crossover from anode to cathode Degradation (peroxide attack, F- release)
Catalyst Expensive, less abundant Pt catalyst Poisoning of Pt by CO at top < 100°C Poor utilization of Pt (80% waste) Catalyst/support instability/degradation
Solution: Explore alternative, new materials
New polymeric membranesNew polymeric membranes
Consists of an acidic and basic polymers Proton conduction based on acid-base
interactions May not need water for proton conduction Permits operation above 100°C Lower methanol permeability Higher power density Lower platinum catalyst loading Cost savings (up to 90% reduction)
Applications of fuel cellsApplications of fuel cells
Hydrogen fuel cells for stationary power and automobilesHydrogen fuel cells for stationary power and automobiles Direct methanol fuel cell could replace lithium-ion batteries in Direct methanol fuel cell could replace lithium-ion batteries in
portables portables Charging with an electrical outlet can be eliminated Charging with an electrical outlet can be eliminated 10X higher energy density by volume than lithium-ion batteries10X higher energy density by volume than lithium-ion batteries 30X higher energy density by weight than lithium-ion batteries 30X higher energy density by weight than lithium-ion batteries 50% weight saving in laptop (340 Wh/kg vs. lithium-ion’s 160 50% weight saving in laptop (340 Wh/kg vs. lithium-ion’s 160
Wh/kg)Wh/kg)
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