development of high temperature membranes and improved ...ntpa-cs membrane 1000 hrs demonstrated at...

2006 DOE Hydrogen Program ReviewMay 13-16, 2006

Arlington, VA

This presentation does not contain any proprietary or confidential information ID# FC20

Development of High Temperature Development of High Temperature Membranes and Improved CathodeMembranes and Improved Cathode

Catalysts for PEM Fuel CellsCatalysts for PEM Fuel Cells

Lesia ProtsailoUTC Power

DoE Agreement DE-FC04C-02-A1-67608Program Manager – Amy Manheim


Arlington, VA


Objectives and ApproachObjectives and ApproachImproved Cathode Catalysts

Goals:To improve power densityLower cost, $/kW

Approach:Higher activity cathode catalyst systems: binary and ternary alloys. High loading of noble metal to decrease electrode thickness and achieve mass transport benefit

High Temperature Fundamentals and Membrane Development (100-120 C, 1.0-1.5 atm):

Goals to improve:Anode and cathode kineticsSystem heat management

Approach:Collaboration with leading polymer chemists to develop new membrane systems: poly(arylene ether sulfone), PEEK, multiblock polymers and inorganic solid conductor filled Nafion®

Fundamental understanding of HT operation limitations and possible solutions through modeling and experimental work


Arlington, VA


Technical Barriers, Budget, TeamTechnical Barriers, Budget, Team

• Technical Barriers– P. Durability– Q. Electrode Performance– R. Thermal and Water

Management

YearTotal $M

DoE $M

UTC$M

Overall 2002-2005 9.500 7.600 1.900

Received in 2005 1.875 1.500 .375

•Budget

•Program Team at Closing• UTC Power (Dr. L.Protsailo): general coordination, catalyst

development, modeling, fuel cell testing, fundamentals and stackdevelopment

• UTRC (Dr. N.Cipollini): MEA optimization and fabrication• VaTech (Prof. J. McGrath): membrane development, fundamentals of

membrane architecture• UCONN (Prof. J.Fenton): membrane development, MEA fabrication,

HT fundamentals


Arlington, VA


Program ScheduleProgram Schedule

1 2 3 4 5 6 7 8TASK

Phase 1

Task 1.1 Membrane Requirement

Task 1.2 Membrane Synthesis

9 10 11 12 13 14

Task 1.3 Membrane Characterization

Task 2.0 Sub-Scale MEA Catalyst

Phase 3 Stack Demonstration and HT Fundamentals

Task 3.0 Stack MEA Fabrication

Task 3.1, Stack Testing and

15

16

3.2 Demonstration

10

2002 2003 2004

TASK DESCRIPTION

Membrane Chemistry and

Specification

Phase 2 MEA Development & Testing

15 16

6

7

2005

12

9

8

1.0 Catalyst Development

1.01 Catalyst Modeling

1.02 Catalyst Characterization

1.03 Catalyst Synthesis

5

4

32

1

Fabrication and Testing

Catalyst Development

Task 2.1 Sub-Scale High TemperatureMEA Fabrication

Task 2.2 Sub-Scale Testing

Task 2.3 MEA Optimization andSelection

11

11

13

14

Membrane Down select

Catalyst Down select

Task 3.3 Fuel Cell HT Performance Demonstration

Fuel Cell HT Performance and Durability Demonstration

Task 34

17

18


Arlington, VA


Membrane Development ApproachMembrane Development Approach

VaTech approach – sulfonated biphenole-sulfones

O O SO2 co O O SO2

SO3HSO3H

Hydrophobic Hydrophilic

n x1-x Acronym: BPSH-XX Bi P

UCONN approach –

henol Sulfone: H Form

Good mechanical and thermal properties (Tg>>120oC), monomers commercially available (low cost)

composite membranes based on Nafion® and solid proton conductor –retain conductivity at low RH%


Arlington, VA


Technical Accomplishments: Technical Accomplishments: HT Membrane HT Membrane

2 different approaches for HT membrane development were investigated under this program:

• Approach A– First generation: Series II solid

acid doped reinforced Nafion-like membrane

• Nafion®-Teflon®-phosphotungstic acid (NTPA) (Na-form)- Series II membrane

– Second generation: Series IV Cs form in-situ doped reinforced Nafion-like membrane

• Approach B– First generation: BPSH-XX

– Second generation: BPSH-XX with high molecular weight, partially fluorinated, increased acidity of functional group

– Third generation: multiblock copolymers

O O SO2 co O O SO2

SO3HSO3H

Hydrophobic Hydrophilic

n x1-x

UCONN VaTech


Arlington, VA


Technical Accomplishments: Technical Accomplishments: BPSH Membrane BPSH Membrane

Chemical Stability in OCV Test

0.6

0.7

0.8

0.9

1

1.1

0 50 100 150 200 250 300 350 400Time, hours

OC

V, V

-20

0

20

40

60

80

100

120

140

160

180

200

Cro

ssov

er, m

A/c

m2

N112 Pt/K

BPSH35 Pt/K

1. Fails Fenton test

2. Low O2 permeability

3. Outstanding durability at OCV hold conditions


Arlington, VA


Load Cycle Test

20µmEMPA post test analysis:

• BPSH retained its thickness in load cycle test

Load cycle protocol:

• 100oC, 25%RH

• 0.5 SLPM H2/1.0 SLPM O2

• 1min @ 1V, 1min @ 0.4V


60µm

PEM198-BPSH Cycling Results - OCP Decay & Hydrogen x-over Current100 C, 25% RH, 150 kPa, 0.5SLM H2 [Anode], 1.0 SLM O2 [Cathode]

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150 200 250 300 350 400

Time, hours [Cycling protocol: 1 min @ 1V, 1min @ 0.4 V]

OC

V, V

0

2

4

6

8

Cro

ssov

er c

urre

nt a

t 0.4

V,

mA

/cm

2BPSH

N112

PEM198-BPSH Cycling Results - OCP Decay & Hydrogen x-over Current100 C, 25% RH, 150 kPa, 0.5SLM H2 [Anode], 1.0 SLM O2 [Cathode]

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150 200 250 300 350 400

Time, hours [Cycling protocol: 1 min @ 1V, 1min @ 0.4 V]

OC

V, V

0

2

4

6

8

Cro

ssov

er c

urre

nt a

t 0.4

V,

mA

/cm

2BPSH

N112

BPSH-37Nafion® 112


Arlington, VA


MembraneLinear expansion x-

direction, %

Linear expansion y-direction, %

Swelling (boiling), %

BPSH 25 15 41.2

N112 10 3.1 11.4

Strain (%)

0 50 100 150 200

Stre

ss (k

gf/c

m2 )

0

100

200

300

400

500

600

700

1: BPSH-40 (dry)2: BPSH-40 (wet)3: Nafion 117 (dry)4: Nafion 117 (wet)

1

2

3

4

RH Cycle Test

Technical Accomplishments: Technical Accomplishments: BPSH MembraneBPSH Membrane

0%-100% RH cycling at 100oC

0

200

400

600

800

0 50 100 150 200

Time, hours

X-o

ver a

t 3ps

i, C

CM

BPSH

N112


Arlington, VA



Unitized Electrode Assembly

Cracks due to dimensional

changes during expansion-

contraction cycle


Arlington, VA


Composite membranes based on Nafion® and solid proton conductor – retain conductivity at low RH%• Nafion®-Teflon®-phosphotungstic acid (NTPA) (Na-form)- Series II membrane• Nafion®-Teflon®-phosphotungstic acid (NTPA) (Cs-form) – Series IV membrane

• Smaller uniform particle size• Solid acid proton conductor is precipitated in-situ• Cs-form is insoluble• Processed at higher ToC

– durability +Series II Series IV

Technical Accomplishments: Technical Accomplishments: NTPANTPA--Cs Membrane Cs Membrane

1000 hrs demonstrated at 100oC, 25%RH;

No membrane failure observed @ 1000 hours


Arlington, VA


• Performance improves at higher utilizations– RH&Conductivity

DOMINATE PERFORMANCE over O2concentration

HT/Low RH Operation ModelingHT/Low RH Operation Modeling

Performance Curves100 C, 25% RH, 150 kPa, BOM CCM for s700

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400 500 600Current Density, mA/cm2

Vol

tage

, V

U[H2/AIR] = 30,25

U[H2/AIR] = 80,60

Performance Simulations for s700 Planform, H2/Air, 100 C, 25% RH, 150 kPa

Nafion 112

00.10.20.30.40.50.60.70.80.9

1

0 2000 4000 6000 8000 10000CD, A m-2

Cel

l Vol

tage

, V

U=80,60 (H2/O2)U=30,25 (H2/O2)

3500 4000 4500 5000 5500 6000 6500

CD, A/m230 35 40 45 50 55 60 65

RHMEM, %

3500 4000 4500 5000 5500 6000 6500

CD, A/m230 35 40 45 50 55 60 65

RHMEM, %


Arlington, VA


Cathode Catalyst Development ApproachCathode Catalyst Development Approach

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.0 0.2 0.4 0.6 0.8 1.0 1.2E, V vs RHE

I, m

A/cm

2 (rea

l)

Pt PtIrCo PtCo

Difference in catalyst-water interactions defines catalyst properties

0

10

20

30

40

50

60

Pt PtCo PtIrCo

% E

CA

lost

0.820.870.920.971.02

0 1 2 3log i

Vcell

, IR fr

ee

PtCo 65C

Pt 65C

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.0 0.2 0.4 0.6 0.8 1.0 1.2E, V vs RHE

I, m

A/cm

2 (rea

l)

Pt PtIrCo PtCo

Difference in catalyst-water interactions defines catalyst properties

0

10

20

30

40

50

60

Pt PtCo PtIrCo

% E

CA

lost

0.820.870.920.971.02

0 1 2 3log i

Vcell

, IR fr

ee

PtCo 65C

Pt 65C

• Higher activity cathode catalyst systems: binary and ternary alloys

– Carbothermal synthesis

– PtCo and PtIrColeading systems

• High loading of noble metal to decrease electrode thickness and achieve mass transport benefit


Arlington, VA


MEA OptimizationMEA Optimization

Pt (full cathode loading) vs PtCo (1/2 cathode loading)

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

0.0 200.0 400.0 600.0 800.0 1000.0 1200.0

Current Density, mA/cm2

Vce

ll, V

olts

(IR

free

)

PtCo 1/2 cathode loading Pt full cathode loading

Reduced cathode thickness benefit

Flooding

H2/Air, 65oC

Pt (full cathode loading) vs PtCo (1/2 cathode loading)

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

0.0 200.0 400.0 600.0 800.0 1000.0 1200.0

Current Density, mA/cm2

Vce

ll, V

olts

(IR

free

)

PtCo 1/2 cathode loading Pt full cathode loading

Reduced cathode thickness benefit

Flooding

H2/Air, 65oC


Arlington, VA


PtCo 20PtCo 20--Cell StackCell Stack

PtCo MEA specification:

0.35mgPt/cm2

Nafion® 112

Toray GDL

UTCFC planform(400cm2)

PtCo 20-cell stack was delivered to ANL for durability studies. Technical support is provided.

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

0 200 400 600 800 1000Current Density (mA/cm2)

Ave

rage

Cel

l Vol

tage

(VD

C)

MAX

AVERAGE

MIN


Arlington, VA


Alloy Catalyst DurabilityAlloy Catalyst Durability

0.4

0.5

0.6

0.7

0.8

0.9

1

1 10 100 1000Current Density, mA/cm2

Volta

ge, V

Pt/C initialPt/C 1800 cycles

0.4

0.5

0.6

0.7

0.8

0.9

1


Volta

ge, V

PtIrCo/C initial

PtIrCo/C 1800 cycles

H2/O2, 120oCoC, 50%RH, 1.5atm.

Pt/C: ~ 45% ECA decrease; 25mV performance loss

PtIrCo/C: ~ 6% ECA decrease; 3mV performance loss

Potential cycling conditions:120oC, 50%RH; 2800 cycles; H2/N2 30s 0.87-30s 1.05V

Cathode ECA loss during HT potential cycling

0

10

20

30

40

50

60

Pt Pt75Co25/KB Pt50Ir25Co25

ECA

loss

(afte

r 220

0 cy

cles

), %

0.4

0.5

0.6

0.7

0.8

0.9

1


Volta

ge, V

Pt/C initialPt/C 1800 cycles

0.4

0.5

0.6

0.7

0.8

0.9

1


Volta

ge, V

PtIrCo/C initial

PtIrCo/C 1800 cycles

H2/O2, 120oCoC, 50%RH, 1.5atm.

Pt/C: ~ 45% ECA decrease; 25mV performance loss

PtIrCo/C: ~ 6% ECA decrease; 3mV performance loss

Potential cycling conditions:120oC, 50%RH; 2800 cycles; H2/N2 30s 0.87-30s 1.05V

Cathode ECA loss during HT potential cycling

0

10

20

30

40

50

60

Pt Pt75Co25/KB Pt50Ir25Co25

ECA

loss

(afte

r 220

0 cy

cles

), %


Arlington, VA


Alloy Effect on Ionomer DurabilityAlloy Effect on Ionomer Durability

Pt EMPA map after cycling– 10 % H2 in N2, low utilization– Electrode Ionic resistance changes

with time– PtIrCo cathode prevents ionomer

poisoningPt PtIrCoPtCo

H2 Pump ELECTRODE RESISTANCEPt/C

0.001

0.01

0.1

1

0 100 200 300 400 500Current Density, mA/cm 2

EL

EC

TRO

DE

RE

SIS

TAN

CE

,

Tcell=120-0 c ycles Tcell=120-600 cycles#1 Tcell=120-1000 cy cles#1 Tcell=120-1400 cy cles#1 Tcell=120-1800 cy cles#1 Tcell=120-2200 cy cles#1

H2 Pump ELECTRODE RESISTANCE CurvesPtIrCo/C

0.001

0.01

0.1

1


Vo

ltage

, V Tcell=120-0 cycles Tcell=120-200 cycles#2 Tcell=120-600 cycles Tcell=120-1000 cycles Tcell=120-1400 cycles Tcell=120-1800 cycles Tcell=120-2800 cycles

H2 Pump ELECTRODE RESISTANCEPt/C

0.001

0.01

0.1

1

0 100 200 300 400 500Current Density, mA/cm 2

EL

EC

TRO

DE

RE

SIS

TAN

CE

,

Tcell=120-0 c ycles Tcell=120-600 cycles#1 Tcell=120-1000 cy cles#1 Tcell=120-1400 cy cles#1 Tcell=120-1800 cy cles#1 Tcell=120-2200 cy cles#1

H2 Pump ELECTRODE RESISTANCE CurvesPtIrCo/C

0.001

0.01

0.1

1


Vo

ltage

, V Tcell=120-0 cycles Tcell=120-200 cycles#2 Tcell=120-600 cycles Tcell=120-1000 cycles Tcell=120-1400 cycles Tcell=120-1800 cycles Tcell=120-2800 cycles


Arlington, VA


Summary of Program Accomplishments Summary of Program Accomplishments

2002 - 2005

• Established the importance of cyclic durability• Developed best in class PtIrCo alloy catalyst and

demonstrated 5x cyclic durability improvement vs. Pt

• Established membrane down-select criteria• Developed fundamental understanding of hydrocarbon

membrane durability• Demonstrated 1000 hours of operation at 100oC,

25%RH


Arlington, VA


Responses to Previous Year Reviewers’ Responses to Previous Year Reviewers’ CommentsComments

• Q1. Shows results on hydrogen/oxygen primarily– Initial stages of alloy work were dedicated to activity investigations (thus

oxygen data are more useful). MEA optimization step operated with H2/air performance

• Q2. Membrane durability studies weak – the new materials are interesting, but durability data are limiting

– Significant emphasis has been put on fundamental analysis and understanding of alternative membrane durability – especially hydrocarbon membranes

• Q3. Testing of new catalysts in full-size cells and a stack to compliment fundamental studies of catalyst and membrane durability is needed

– PtCo catalyst was tested in full size cell and 20-cell stack was built and delivered for testing to ANL facilities

– Attempt to test hydrocarbon membrane in full size cell was made. Unitizing BPSH for full-size testing is a challenging task due to dimensional instability of the membrane.


Arlington, VA


AcknowledgementsAcknowledgements

A. HaugM. FortinM. PembertonP. PlasseJ. MeyersS. MotupallyCSA Durability group

J.E. McGrathX. Yu

K. Wiles A. RoyX. Li

H.R. KunzJ. FentonL. Bonville (IONOMEM)Y. SongV. MittalY. DuF. KassimY. LiuH. XuV. Ramani

N. CipolliniT. MaddenB. LeTourneau

development of high temperature membranes and improved ...ntpa-cs membrane 1000 hrs demonstrated at...

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