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)