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Materials Science & TechnologyFuel Cell ResearchHydrogen, Fuel Cells & Infrastructure Technologies

Annual Review, May 24-27, 2004

Hydrogen, Fuel Cells & Infrastructure Technologies Program2004 Annual Review

Philadelphia, Pennsylvania, May 24-27, 2004

This presentation does not contain any proprietary or confidential information

Direct Methanol Fuel CellsEric Brosha, John Davey, Fernando Garzon, Christine Hamon

Yu Seung Kim, Manoj Neergat, Piotr Piela, Bryan PivovarGerie Purdy, John Ramsey, John Rowley, Mahlon Wilson

andPiotr Zelenay

Los Alamos National LaboratoryLos Alamos, New Mexico 87545

DOE Program Manager: Nancy GarlandLANL Program Manager: Ken Stroh



• Catalyst Research & DevelopmentJohnson Matthey: Dr. David Thompsett – Pt-Ru catalysts for the anodeSuperior MicroPowders: Dr. Paolina Atanassova – DMFC MEAsE-TEK / de Nora North America: Dr. Emory de Castro – anode and cathode catalysisUniversity of Illinois: Prof. Andrzej Wieckowski – basic electrocatalysisUniversity of New Mexico: Prof. Plamen Atanassov – non-precious metal catalysis

• Membranes / Membrane-Electrode AssembliesVirginia Polytechnic: Prof. James McGrath – alternative polymers and MEAs with significantly improved selectivity and durabilityW. L. Gore: Dr. Karine Gulati – membranes with improved selectivity

• DMFC Stacks & SensorsMesoscopic Devices: Drs. Christine & Jerry Martin – DMFC hardware for portable applications; electrocatalysisBall Aerospace: Dr. Jeff Schmidt – 20 W portable power system for the military (DARPA Palm Power Program)

Selected Collaborations & Commercial Interactions ( )C



Collaboration with Ball Aerospace ( )Portable Power System for DARPA

C

LANL Dual 12-Cell DMFC Stacks Key System Specs

Rated power: 20 W

Voltage: 12 V

Specific power(72 h mission): 500 W/kg

Efficiency: 33%

Energy yieldfrom fuel: 2 kWh/kg

Converter volume: 1.6 L

Converter weight: 1.6 kg

• LANL DMFC stacks and methanol concentration sensors integrated by Ball Aerospace into first DMFC-20 demonstration units for the military

• Respectable specific power & system efficiency



• Determine the impact of Ru crossing on the oxygen reduction kinetics at the DMFC cathode. – March 2004

• Develop methods for synthesis and demonstrate new unsupported DMFC cathode catalyst with average particle size reduced by at least 40% and performance superior to the best commercial cathode catalysts. – March 2004

• Quantify losses in the active surface area of the anode and the cathode over at least 200 h of DMFC operation. – September 2004

• Determine the impact of Ru crossing on the oxygen reduction kinetics at the DMFC cathode. – March 2004

• Develop methods for synthesis and demonstrate new unsupported DMFC cathode catalyst with average particle size reduced by at least 40% and performance superior to the best commercial cathode catalysts. – March 2004

• Quantify losses in the active surface area of the anode and the cathode over at least 200 h of DMFC operation. – September 2004

___________

• Total DOE Funding: $300 KIrrespective of repeatedly high evaluation scores (3.33 in FY 2003), funding of the LANL DMFC project has been decreased in FY 2004. Reason given: “Technology for portable power applications is near commercialization”; HFCIT Program, FY 2003 Merit Review and Peer Evaluation Report.

DMFC Research: Milestones & FY 2004 Funding



• Average particle size reduced from 6 nm (Johnson Matthey’s HiSPEC™1000, the state-of-the-art Pt black catalyst for DMFCs) to 3.6 nm and 4.8 nm, for Pt black and Pt/SiO2 catalysts, respectively.

2 Theta (Degrees)

20 40 60 80 100In

tens

ity

0

1000

2000

3000

4000

5000

6000

7000

JM Hi-SPEC 1000 Pt black (6 nm, 47 m2/g)

In-house Pt black (3.6 nm, 79 m2/g)

In-house Pt/SiO2 (4.8 nm, 59 m2/g)

Electrocatalysis ResearchPt Cathode Catalysts with Reduced Particle Size: Approach and XRD Patterns

• Average particle size reduced from 6 nm (Johnson Matthey’s HiSPEC™1000, the state-of-the-art Pt black catalyst for DMFCs) to 3.6 nm and 4.8 nm, for Pt black and Pt/SiO2 catalysts, respectively.

40% higher dispersion of Pt cathode catalyst achieved (2004 Milestone)

Preparation of Pt black and Pt/SiO2Two Approaches

Na6[Pt(SO3)4] + H2SO4, 80°C

H2O2, 80°C SiO2

PtO, PtO2 H2O2, 80°C

HCOOH

Pt black Pt, PtO2/SiO2

HCOOH

Pt/SiO2

Preparation of Pt black and Pt/SiO2Two Approaches

Na6[Pt(SO3)4] + H2SO4, 80°C

H2O2, 80°C SiO2

PtO, PtO2 H2O2, 80°C

HCOOH

Pt black Pt, PtO2/SiO2

HCOOH

Pt/SiO2



DMFC

Current Density (A cm-2)

0.0 0.2 0.4 0.6 0.8 1.0

Cel

l Vol

tage

(V)

0.0

0.2

0.4

0.6

0.8 JM Hi-SPEC1000 Pt blackIn-house Pt black (3.8 nm)In-house Pt/SiO2 leachedIn-house Pt black (4.5 nm)

80°C, 1.0 M MeOH, 30 psig airH2-Air


0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Cel

l Vol

tage

(V)

0.0

0.2

0.4

0.6

0.8

1.0

1.2JM Hi-SPEC 1000 Pt blackIn-house Pt black (3.8 nm)In-house leached Pt/SiO2In-house Pt black (4.5 nm)

80°C, 30 psig H2 & air

Electrocatalysis ResearchPt Cathode Catalysts with Reduced Particle Size: Fuel Test Cell Data

• Performance of newly synthesized Pt catalysts matches that of the best commercial DMFC cathode catalysts.

• Catalyst utilization needs to be improved in order to take full advantage of the smaller particle size of LANL’s catalysts.



2 Theta (Degrees)

20 40 60 80 100

Inte

nsity

0

1000

2000

3000

4000

5000

6000

7000

In-house 60 wt % Pt-Co/C (1:1) (6.2 nm, 61 m2/g

In house Pt-Co (1:1) Black (2.7 nm, 139 m2/g)

JM Hi-SPEC 1000 Pt black (6 nm, 47 m2/g)

Electrocatalysis ResearchPt-Co Binary Cathode Catalysts

• Developed two new synthesis approaches for Pt-Co binary catalysts.• High temperature method: Uniquely high metal-loading for Pt-Co/C catalyst

(up to 60 wt%) and small average particle size (6.2 nm).• Low temperature method: Very small average particle size of unsupported

catalyst (~ 2.7 nm – 55% particle size reduction relative to HiSPEC™ 1000).



Alternative aromatic hydrocarbon-based membranes for fuel cells:High conductivity, good mechanical properties and chemical stabilityLow methanol permeabilityAt least an order of magnitude lower cost

Key technical issue:Performance loss due to interfacial incompatibility with Nafion-bonded electrode

Research focusDevelop membranes compatible with Nafion-bonded electrodesDetermine initial and long-term fuel cell performance of MEAs

Membrane / MEA ResearchObjectives

O O

CF3

CF3

CN

1-n

O

CF3

CF3

O SO2

SO3HHO3Sn

co

O O SO2 co O O SO2

HO3S SO3H1-x x

____________________________XX - percentage of disulfonated monomer units

6FCN-XX

BPSH-XX

Collaboration with Virginia TechC



Membrane / MEA ResearchMembrane vs. MEA Selectivity

• Expected selectivity gains of BPSH-40 not realized in fuel cell testing.• 6F-CN-35 MEA exhibits much higher selectivity than regular Nafion MEA.

Membrane SelectivityRatio of proton conductivity

to methanol permeability

MEA Selectivity

HFR = MEA impedanceζ = limiting MeOH

crossover value (at OCV)

Relative SelectivityMembrane-to-Nafion

selectivity ratio

BPSH-40

6F-CN-35 Nafi

on

Rel

ativ

e Se

lect

ivity

0.0

0.5

1.0

1.5

2.0

2.5

Free-StandingMembrane

BPSH-40

6F-CN-35 Nafi

on

Complete MEA with Nafion-Bonded Electrode

nHFR lim,1ς

α×

=



Time (hour)

0 100 200 300 400 500 600 700

Cur

rent

den

sity

(A/c

m2 )

0.05

0.10

0.15

0.20

0.25

HFR

(Ohm

cm

2 )

0.0

0.1

0.2

Restart test Restart test

unrecoverable lossrecoverable loss

(a)

Membrane / MEA ResearchPerformance Durability (80°C, 0.5 V)

• Good and stable membrane/electrode interface indicated by no change in the resistance of 6F-CN-35 MEA over time.

• Similar 700-hour performance losses for 6F-CN-35 and Nafion MEAs• Much higher initial performance of 6F-CN-35 maintained throughout the life

test → significant achievement in the alternative DMFC membrane research.

Time (hour)

0 100 200 300 400 500 600 700

Cur

rent

den

sity

(A/c

m2 )

0.05

0.10

0.15

0.20

0.25

HFR

(Ohm

cm

2 )

0.0

0.1

0.2

Restart test Restart test

unrecoverablelossrecoverableloss

(a)

Nafion 1135 MEA 6F-CN-35 MEA



First test of high specific-power stack: (i) uniform operation of individual cells, (ii) very little sensitivity to the air flow, (iii) anode-limited performance.

Growing industrial interest; significant technology transfer potential

High specific-power stack project currently supported byLos Alamos National Laboratory’s Technology Maturation Fund

High Specific-Power Stack for Portable ApplicationsShort Six-Cell Stack Testing


0.00 0.05 0.10 0.15 0.20 0.25

Stack Power (W

)

0

2

4

6

8

10

12

Ave

rage

Cel

l Vol

tage

(V)

0.1

0.2

0.3

0.4

0.5

0.6

0.7

3.0x2.6x2.3x

2.0x

75°C, 0.5 M MeOH, 0 psig air



• Expected maximum specific power of the 25-cell stack: 400 - 500 W/kg.• Expected maximum specific power of the 25-cell stack: 400 - 500 W/kg.• Stack performance promises to exceed DOE’s Technical Targets for

Consumer Electronics systems for both 2006 & 2010

High Specific-Power Stack for Portable ApplicationsStack Performance vs. DOE Technical Targets



Durability Research850-Hour DMFC Life Test: Possible Causes of Cell Performance Loss

75ºC, 80 mA cm-2

Cathode: 0 psig, air stoich 3.4

Time (h)0 200 400 600 800

Volta

ge (V

)0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

1 2

3

4

5

6

• Surface area loss of the cathode and/or anode catalyst• Cathode surface oxidation• Diminished cathode hydrophobicity → “flooding”• Ruthenium crossover and subsequent accumulation at the cathode



Durability ResearchRuthenium Crossover: Effect on Oxygen Reduction

• Cathodes in ‘typical” DMFCs (Pt-Ru black anode, Nafion™ membrane, Pt black cathode) become gradually contaminated by Ru migrating from the anode.

• CO stripping data at different stages of the life test correlate well with the cathode’s kinetic performance.

• Oxygen reduction alone is inhibited by Ru crossover by ~25 mV at 0.1 A cm-2after several hundred hours of cell operation.

H2-Air


0.00 0.05 0.10 0.15 0.20

Vol

tage

(V)

0.75

0.80

0.85

0.90

0.95

1.00100 h360 h615 h847 h

Potential (V)0.2 0.4 0.6 0.8 1.0

Cur

rent

/ Q

CO (A

C-1

)

0.00

0.02

0.04

0.06

Pt-Ruref

100 h360 h

615 h

847 h

Ptref



• Overall DMFC performance penalty resulting from slower oxygen reduction and lower cathode tolerance to crossover methanol: ~ 40 mV (moderate Ru contamination of the cathode after hundreds of hours of DMFC operation).

• Extreme Ru-contamination: ~ 200 mV cell voltage loss.

• Overall DMFC performance penalty resulting from slower oxygen reduction and lower cathode tolerance to crossover methanol: ~ 40 mV (moderate Ru contamination of the cathode after hundreds of hours of DMFC operation).

• Extreme Ru-contamination: ~ 200 mV cell voltage loss.

2004 Milestone Accomplished

Durability ResearchRuthenium Crossover: DMFC Performance Loss

Current Density (A cm-2)0.00 0.05 0.10 0.15 0.20

iR-C

orre

cted

Cel

l Vol

tage

(V)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Ru-free cathodeRu-contaminated cathodePt-Ru cathode

DMFCTypical Ru Contamination

Current Density (A cm-2)0.00 0.02 0.04 0.06 0.08 0.10

iR-c

orre

cted

Cel

l Vol

tage

(V)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Ru-free cathodeExtremely Ru-contaminated cathode

DMFCExtreme Ru Contamination



Durability ResearchRuthenium Crossover: Preparation of MEAs with “Ru-free” Cathodes

• Virtually Ru-free cathodes observed following removal of loosely-bound Ru in the anode catalyst & better anode curing (after break-in data; no life-tests performed).

Cathode Potential (V)0.4 0.6 0.8 1.0

Cur

rent

/ Q

CO (A

C-1

)

0.00

0.02

0.04

0.06

0.08Pt/Pt ReferenceCell

PaintingAlone

DecalTransfer

Painting& Leaching

Decal Transfer& Leaching



Time (h)0 200 400 600 800

Ano

de A

ctiv

e A

rea

(%)

50

60

70

80

90

100

12

3

4

56

Durability ResearchLoss of Anode Active Surface Area

• 35% - 40% anode surface area loss revealed by CO stripping after 850 hours of cells operation.

• Very little impact on DMFC performance.

75ºC

iR-corrected Anode Potential (V vs. DHE)0.20 0.24 0.28 0.32

Cur

rent

Den

sity

(A c

m-2

)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0 h100 h360 h615 h



• 35% - 40% cathode surface area loss revealed by CO stripping after 850 hours of cells operation (similar loss as for the anodes).

• Possible significant impact on cell performance.

• 35% - 40% cathode surface area loss revealed by CO stripping after 850 hours of cells operation (similar loss as for the anodes).

• Possible significant impact on cell performance.

2004 Milestone Accomplished & Exceeded

Durability ResearchLoss of Cathode Active Surface Area

Time (h)0 200 400 600 800

Cat

hode

Act

ive

Are

a (%

)

50

60

70

80

90

100

1

23

45

6



• No obvious correlation observed between the rates of catalytic sites blockage by surface ‘OH’ and/or ‘O’ species and DMFC performance loss.

• Based on percent loss of cell performance over time, ‘O’ is the more likely surface species.

Time (min)0 100 200 300 400 500

Cur

rent

Den

sity

@ 0

.5 V

0.00

0.02

0.04

0.06

0.08

0.10

0.12

1 - θ @ 0.84 V

0.0

0.2

0.4

0.6

0.8

1.0

Time (min)0 100 200 300 400 500

Cur

rent

Den

sity

@ 0

.5 V

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Oxide R

eduction Peak Potential (V)

0.70

0.72

0.74

0.76

0.78

Pt=O

Pt–OH

Durability ResearchCathode Oxidation vs. DMFC Performance Loss

• Transition of the cathode oxide beyond the point of surface coverage saturation is a likely reason for cell performance drop at times longer than two hours (→ lessened Pt catalyst activity in oxygen reduction reaction).



Durability ResearchNovel DMFC MEA with Improved Stability

• New LANL-developed Nafion-based MEA tested for 3000 hours under challenging conditions of low air “stoich” and ambient cathode pressure.

• 3000-hour performance loss limited to ~12% (with fully oxidized cathode).

New MEA

Time (h)0 500 1000 1500 2000 2500 3000

Cur

rent

Den

sity

(A c

m-2

)

0.00

0.02

0.05

0.07

0.09

0.11

0.14

0.1675°C, 0.5 V

Cathode: 0 psig, < 2.5x stoich



Performance Durability:Determined impact of Ru crossover on DMFC cathode performance (Milestone #1); proposed two methods for Ru crossover reductionQuantified anode & cathode surface area losses in the 850-hour life test (Milestone #3)Correlated transformation of Pt oxide and cathode performance lossDemonstrated new Nafion-based MEA with performance loss reduced to ~12% over 3000 hours

Membrane & MEA Research:Demonstrated much higher than Nafion’s selectivity of 6F-CN-35 membrane in operating cellMaintained superior performance of the 6F-CN-35 MEA for 700 hours

Cathode Electrocatalysis:Synthesized in-house Pt and Pt-Co catalysts (unsupported and supported) with significantly reduced average particle size – Milestone #2’s 40% particle-size reduction goal achieved; work will focus on performance

High Specific-Power Portable Stack:Designed, built and successfully tested first short six-cell stack

Technical Accomplishments & Progress (Highlights)



Selected Reviewers’ Comments

“Astonishing productivity on all key areas of DMFC”“Good balance of theoretical understanding and practical experiments. But why move to higher power?” Higher power stack effort was abandoned in late FY03. Instead, the project has focused even more on key issues for the future of DMFCs: (i) performance durability, (ii) alternative membrane/MEA development and (iii) cathode operation. Small effort has continued in the high specific-power DMFC stack, the project now internally supported by LANL..“Transfer stack making technology to an industrial company”A government-use license has been issued to Ball Aerospace for military applications (20 W portable system). Several companies expressedsignificant interest in the stack, methanol-sensor and novel-MEA technologies. Substantial discussions in progress.“Stay with your strengths – focus on improving performance and fundamental understanding” These have actually been the two main thrust areas of the DMFC research at LANL in FY04. “Continue funding”

R

R

R

R

R



Research Plans

Remainder of FY 2004• Determine and optimize performance of new LANL-synthesized

highly-dispersed cathode catalysts• Verify performance stability of novel Nafion-based MEAs, recently

life-tested for 3000 hours• Demonstrate a complete 25-cell high specific-power stack for

portable applications

FY 2005 Objectives (All key to successful commercialization of DMFCs)

• Determine impact of changing hydrophilic/hydrophobic properties of the cathode on DMFC performance and performance durability

• Explore introduction of non-precious metal electrocatalysts as means of lowering DMFC cost

• Minimize or altogether eliminate Ru crossover in DMFCs• Establish materials and techniques allowing consistent fabrication of

highly selective and durable alternative MEAs for DMFCs



Administrative Safety ControlsHazard Control Plan (HCP): Hazard-based safety reviewIntegrated Work Document (IWD): Task-based safety reviewIntegrated Safety Management (ISM): Define work → Analyze Hazards → Develop controls → Perform work → Ensure performance

Engineering ControlsHydrogen and carbon monoxide laboratory sensors for hydrogen testing (cell break-in, anode polarization testing, surface area determination)In the process of replacing tube hydrogen gas storage with on-demand electrolytic hydrogen generatorsGenerally low and very low risk operations

Potentially Useful DMFC Safety TipDirect sink disposal of low-concentration aqueous methanol waste is acceptable after dissolved CO2 is removed by neutral gas purging and, consequently, initially acidic solution pH increases to neutral.

DMFC Research: Project Safety

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