development of high temperature membranes and improved ... · technical accomplishments: pt alloys...

2005 DOE Hydrogen Program ReviewMay 23-26, 2005

Arlington, VA

This presentation does not contain any proprietary or confidential information

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 Fuel Cells

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

Project ID#: FC4


Arlington, VA


Objectives and ApproachObjectives and Approach

Improved Cathode CatalystsGoals:

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 CO toleranceAnode 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 and TargetsTechnical Barriers and Targets

Characteristic Units Calendar Year

2002 2005 2010

Membrane Areal Resistance in cell, operating temperature

Ω-cm2 0.1 0.1 0.1

Cost $/kW 200 100 10

Operating Temperature oC 80 120(100) 120(100)

Durability hours 1000 >4000 >5000

Total catalyst loading (both electrodes) mg/cm2 0.8 0.4 0.1

Performance @ 0.25 power (0.8V) mA/cm2

mW/cm2125100

250200

400320

Performance @ full power mW/cm2 400 800 1280

Extend of performance degradation over lifetime

% 10 10 10

• DoE Technical Barriers for Fuel Cell Components– P. Durability– Q. Electrode Performance– R. Thermal and Water Management

• DoE Technical Targets for Catalyst Coated Membranes


Arlington, VA


Budget and PartnersBudget and Partners

• UTC FC (Dr. L.Protsailo): general coordination, catalyst development, modeling, fuel cell testing, fundamentals and stack development

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

membrane architecture• UCONN (Prof. J.Fenton/R.Kunz): membrane development, MEA

fabrication, HT fundamentals• NorthEastern University (Prof. S. Mukerjee): catalyst development,

durability studies

YearTotal $M

DoE $M

UTC$M

Overall Program 2002-2006 9.500 7.600 1.900FY04 (actual) 2.983 2.387 .593FY05 (planned) 1.875 1.500 .375

Program Team:


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 3.3

17

18


Arlington, VA


Preliminary model completedBegin alloy synthesisComplete alloy synthesisComplete characterization and down-selectionComplete modeling + correlationMembrane specification to team membersInitial sample membraneCharacterization of initial membrane samplesSynthesis of final membrane samplesSelect membrane for Phase 2

Phase 1Membrane Chemistryand CatalystDevelopment

PHASE MILESTONE # MILESTONE

123456789

10

Phase 2MEA Development and Testing

Phase 3Stack Demonstration and High Temperature Fundamentals

1112

1516

Complete stack and test stand assemblyComplete stack verification test

Initial electrode fabricationComplete subscale testing for cathode catalyst and down-select catalystsComplete subscale testing for membranes and down-select membrane(s)Select optimum catalyst-membrane combinationfor Phase 3

13

14

17

18

Fuel cell demonstration of the best performing high temperature materialsFuel cell demonstration of performance and durability best MEA materials for HT operation

Program MilestonesProgram Milestones


Arlington, VA


Project SafetyProject Safety

• Safety reviews of test equipment design and of test processes– Codes and Standards, Hazard Analysis, FTA, HAZOP– Readiness reviews required for major changes, new equipment and

chemicals

• New Catalyst Preparation– Only low environmental impact reagents and materials are used =

greater level of safety from reduction of chemical hazards and procedures

• Tests Safety– All testing is done in well-ventilated automated test stands – Hydrogen detection and emergency stop capabilities– Alarms– All test hardware for the program has been tested and evaluated in

contractor safety review process

• No unusual safety issues have been encountered to date on this project


Arlington, VA


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

• Q1. Insufficient emphasis on lower RH% requirements for HT operation– Emphasis is put on lower %RH. New design point 100oC, 25% RH. Short excursions to

120oC required.

• Q2. …research areas require more fundamental work …not direct sufficient fundamental analysis to each material regarding failure modes.

– Significant emphasis has been put on fundamental analysis and understanding of HT operation issues – program re-scope in August 2004.

– Direction toward fundamental analysis of failure modes - post-test analysis backed up by modeling work. Post tests include EMPA, XRD, fuel cell exhaust water analysis, post test of failed membranes – GPC, viscosity measurements, etc.

• Q4. The catalyst loading of alternative catalysts is not clear….Catalyst shows greater activity but Pt/C not plotted on durability or performance plots.

– Direct comparison of alternative catalysts to pure Platinum with the emphasis on reduced loading benefit

• Q5. Need to investigate durability of alloys catalysts– Large emphasis on durability aspect of alternative catalyst – including electrode

durability and its implications on membrane durability for wide range of operating conditions


Arlington, VA


Technical Accomplishments: Technical Accomplishments: Pt Alloys for Improved Performance PEM Pt Alloys for Improved Performance PEM FCsFCs

• ½ of Pt loading without sacrifice in performance is allowed with Pt75Co25/C system

• Reduced noble metal loading

• FC performance improvement

– Expected performance improvement for for Pt75Co25/C and Pt50Ir25Co25/C systems (assuming TS=70 mV/decade):

PtCo – 20-28mVPtIrCo – 12-20mV

0.860.880.9

0.920.940.960.98

11.02

0 0.5 1 1.5 2 2.5

log i

Vcel

l, IR

free

PtCo 65C Pt 65C Li (Pt65C)

Observed benefit:18-25mV

: MEA: 0.4mgPt/cm2(cathode)

0.45

0.55

0.65

0.75

0.85

0.95

1.05

1.0 10.0 100.0 1000.0 10000.0Current Density, mA/cm2

Vcel

l, Vo

lts

PEM 472 Pt 0.4mgPt/cm2 cathode

PEM460 PtCo 0.22mgPt/cm2 cathode

Fuel: H2

Oxidant: O2

Temperature: 65oC

Pressure: 1atm


Arlington, VA


Technical Accomplishments: Technical Accomplishments: Pt Alloys for Improved Durability of PEM Pt Alloys for Improved Durability of PEM FCsFCs

Potential cycling test between 0.87V and 1.2V

(1.05V for HT) for 2800cycles

Tear down and do EMPA and XRD analysis

Evaluate the performances/ ECAs every 400cycles

MEA performance in subscale fuel cell

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2

-1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0pH

Elec

trod

e po

tent

ial (

V)

λ=7 λ=14 λ=22

PtO

Pt

Pt++

Pourbaix diagram [Pt++] = 10-6 M

Pt stability in fuel cell environment

• Membrane: Nafion® 112• Anode: ~46% Pt/C, 0.4mgPt/cm2

• Cathode: 45-49% Pt (Pt / Pt75Co25 / Pt50Ir25Co25) supported on high surface area carbon (BET~800m2/g)

• Electrode Cyclic Durability: normal and HT operating conditions


Arlington, VA


Technical Accomplishments: Technical Accomplishments: Pt Alloys for Improved Pt Alloys for Improved Durability of PEM Durability of PEM FCsFCs –– Catalyst Dissolution (65Catalyst Dissolution (65ooC)C)

PtIrCo improves cathode durability 5x that of Pt

•EMPA shows no evidence of Co or Ir in the membrane and/or anode.

ECA reduction

during potential cycling

0

0.2

0 .4

0 .6

0 .8

1

1.2

0 100 200 300 400 500 600 700 800 900 1000

C u r r e n t d e n s ity, m A /cm 2

Vcel

l, V

PEM 456 PtIrCo H2_O2 (BOL)

A f ter 3200 c y c les

IP (BOL)

IR (af ter 3200 c y c les )

3200 cycles0

0.2

0 .4

0 .6

0 .8

1

1.2

0 100 200 300 400 500 600 700 800 900 1000


Vcel

l, V



IP (BOL)


3200 cycles

Pt/C

0

0.2

0 .4

0 .6

0 .8

1

1.2

0 100 200 300 400 500 600 700 800 900 1000


Vcel

l, V



IP (BOL)


3200 cycles0

0.2

0 .4

0 .6

0 .8

1

1.2

0 100 200 300 400 500 600 700 800 900 1000


Vcel

l, V



IP (BOL)


3200 cycles

Pt75Ir25Co25/CPt Co IrPt Co Ir


Arlington, VA


Potential cycling conditions:120oC, 50%RH;2800 cycles; H2/N2

0.87-1.05V vs RHE; Diagnostic tests every 400 cycles: ECA, H2/Air, H2/O2

Technical Accomplishments: Technical Accomplishments: Pt Alloys for Improved Pt Alloys for Improved Durability of PEM Durability of PEM FCsFCs -- Catalyst Dissolution at HTCatalyst Dissolution at HT

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

0 400 800 1200 1600 2000 2400 2800 3200 3600

Cycle No.

Nor

m. E

CA

PtIrCo

PtCoPt

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

1 10 100 1000Current Density, mA/cm2

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


Arlington, VA


PtIrCo/C cathode

B.S.E. Pt Co Ir

PtCo/C cathode

B.S.E. Pt

Pt/C cathode

•The electron microprobe analysis shows no evidence of Co or Ir in the membrane and/or anode.• The absence of Co/Ir migration demonstrates a benefit of PtCo and PtIrCo alloy systems – will not poison membrane.

Technical Accomplishments: Technical Accomplishments: Pt Alloys for Improved Pt Alloys for Improved Durability of PEM Durability of PEM FCsFCs -- Catalyst Dissolution at HTCatalyst Dissolution at HT

MEA Post-Test: EMPA Analysis


Arlington, VA


Technical Accomplishments: Technical Accomplishments: Pt Alloys for Improved Pt Alloys for Improved Durability of PEM Durability of PEM FCsFCs –– Peroxide Formation Peroxide Formation

Rate of H2O2 formation:– Pt > PtCo– Low RH% >> High RH%

RRDE experiments


Arlington, VA


Technical Accomplishments: Technical Accomplishments: HT operation HT operation ––performance improvementsperformance improvements

Performance Curve when varying HTparameters120 C, 25 % RH, 150 kPa (abs)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 4000 8000 12000 16000 20000CD (A/m2)

Volta

ge, V

NAF112UConn

UConn best case

•Re-optimize cathode–More ionomer–More conductive ionomer–Thinner–More active catalyst

•Thinner membrane, more conductive–UConn has 25 micron membrane–Good Conductivity

Modeling Experimental Verification

40mVactivity

enhancement with PtCo at 120oC

800EW ionomer in electrode shows up

to 45mV improvement at low

current densities compared to 1100EW

120oC, 35%RH,

1atm, H2/O2

0.50.55

0.60.65

0.70.75

0.80.85

0.90.95

1

1 10 100 1000 10000Current Density, mA/cm2

Volta

ge, V

PEM155, Pt/K,UCONN GDL

PEM159, PtCo/K,UCONN GDL

120oC, 50%RH, 1.5 atm, H2/O2


Arlington, VA


• 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

• 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

VaTechUCONN

Technical Accomplishments: Technical Accomplishments: HT Membrane DevelopmentHT Membrane Development

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

O O SO2 co O O SO2

SO3HSO3H

Hydrophobic Hydrophilic

n x1-x


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 IV MembraneSeries II Membrane

Series IV

Series IISeries II

Series IV

Series IISeries II

Technical Accomplishments: Technical Accomplishments: HT Membrane HT Membrane Development Development -- Approach AApproach A


Arlington, VA


Technical Accomplishments: Technical Accomplishments: HT Membrane Development HT Membrane Development Approach BApproach B

283272BPSH-50

272268BPSH-40

270259BPSH-30

223BPS-0

M2M1

TgCopolymer

• Pros:– Higher stability with post-sulfonation– High conductivity at high RH%– Low O2 permeability mitigates membrane decomposition caused by

peroxide attack– Excellent thermal stability– Commercially available monomers - $$$++

• Cons:– Improvements of conductivity at

low RH% and mechanical strength improvement needed –higher molecular weightpolymer was developed

Sulfonated Biphenyl Sulfones (BPSH)

Target Mn(kg/mol)

Cond. (mS/cm2)

20 72

30 78

40 85

50 92

1:1 Stoich 120Results consistent with conductivity measurements

0

0 .1

0 .2

0 .3

0 .4

0 .5

0 .6

0 .7

0 .8

0 .9

1

0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0 2 0 0 0

C u rren t D en s ity , m A/cm 2

Volta

ge, V

0

0 .02

0 .04

0 .06

0 .08

0 .1

0 .12

0 .14

0 .16

0 .18

0 .2

Con

duct

ivity

, S/c

m

8 0 C , 1 0 0 % R H

N A F 112

1 2 0 C , 5 0 % R H

B PS H -35


Arlington, VA


• BPSH O2 permeability is 10x lower that of PSFA-like membrane - significantly increases durability

Technical Accomplishments: Technical Accomplishments: HT Membrane HT Membrane Development Approach BDevelopment Approach B

0

2

4

6

8

10

12

14

16

0 50 100 150 200 250O2 Partial pressure, kPa

Perm

eabi

lity

x 10

12, m

ol/c

m/s

Gore 56XNAF111BPSH35UConnLinear (Gore 56X)

Oxygen Permeability Measurements

Accelerated Membrane Degradation Test

Accelerated Membrane

Degradation Test Conditions:

100oC, 25%RH, 1.5atm

H2/O20.6

0.7

0.8

0.9

1

1.1

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

OC

V, V

0

1

2

3

4

5

6

7

8

9

10

Xove

r, m

A/c

m2

N112

BPSH35


Arlington, VA


Technical Accomplishments: Technical Accomplishments: HT Membrane Development HT Membrane Development Approach B Approach B –– Path ForwardPath Forward

Transmission Electron Micrographs:Transmission Electron Micrographs:PMMAPMMA--gg--PDMS Copolymer PDMS Copolymer –– Path to Cocontinuous Path to Cocontinuous

MultiblocksMultiblocks

/ b /

F

F F

F

F

O

FF

F

CF3

CF3

On

F

F F

F

F

O

FF

F

CF3

CF3

O

F

F F

F

F

FF

F

FFn

+M-O O SO

OO

SO3-M+

SO3-M+

O-M+

n

mO S

O

OO

SO3-M+

SO3-M+

Solvent90-110C4-6 h

/ b /

F

F F

F

F

O

FF

F

CF3

CF3

On

F

F F

F

F

O

FF

F

CF3

CF3

O

F

F F

F

F

FF

F

FFn

+M-O O SO

OO

SO3-M+

SO3-M+

O-M+

n

mO S

O

OO

SO3-M+

SO3-M+

Solvent90-110C4-6 h

F

F F

F

F

O

FF

F

CF3

CF3

On

F

F F

F

F

O

FF

F

CF3

CF3

O

F

F F

F

F

FF

F

FFn

+M-O O SO

OO

SO3-M+

SO3-M+

O-M+

n

mO S

O

OO

SO3-M+

SO3-M+

Solvent90-110C4-6 h

F

F F

F

F

O

FF

F

CF3

CF3

O

F

F F

F

F

FF

F

FFn

+M-O O SO

OO

SO3-M+

SO3-M+

O-M+

n

mO S

O

OO

SO3-M+

SO3-M+

Solvent90-110C4-6 h

XU 1 : 3:3 block length XU 1 : 5:5 block length

Cocontinuous multiblock polymers –path forward for HT membranes

development

0.1

1

10

100

1000

0 20 40 60 80 100 120

Relative Humidity (% RH)

Con

duct

ivity

(mS/

cm)

_

BPSH 35 Random Copolymer8.8K Block CopolymerN112


Arlington, VA


Summary of 05/04Summary of 05/04--05/05 Technical Achievements05/05 Technical Achievements

• PtCo and PtIrCo showed x1.5-2.5 specific activity improvement• PtCo MEAs were optimized and benefit of minimum 20mV was shown in-cell• Two-fold reduction of Pt loading is achieved with PtCo without loss in performance • Up to x5 extension of cyclic durability of electrodes was shown with PtIrCo/C

cathode systems• Durability at high temperature operation was shown to be possible through use of

Pt alloy catalyst systems• Significant membrane life extension is possible with alternative alloys due to lower

peroxide generation rates• Improved Series IV membrane was developed in UCONN – will lead to durability

improvements • High molecular weight BPSH membrane was developed and showed HT at least

5x durability improvement compared to PFSA-like membrane• Fundamental studies showed that additional performance benefit can be obtained

at HT operation through the use of advanced catalyst (PtCo) and low EW ionomer in electrodes


Arlington, VA


Going ForwardGoing Forward

• Pt-alloy full size single cell verification• Pt-alloy stack demonstration: full size MEAs fabrication, stack

build and testing• Fundamental understanding of alternative catalyst stability and

its implications on membrane durability• HT operation

– RH% effects – experimental and modeling effort– 100-120oC 25-50%RH membrane endurance demonstration – Demonstration of lessons learned and the best up-to-date

technology for HT operation: single cell performance demonstration

Tasks to be completed by the end of Q1 FY06:Tasks to be completed by the end of Q1 FY06:


Arlington, VA


05/0405/04--05/05 Selected Publications and Presentations05/05 Selected Publications and Presentations

Refereed Articles• Si, Y., H. R. Kunz and J. M. Fenton. 2004. “Nafion®-Teflon®-Zr(HPO4)2 Composite Membranes for High-

Temperature Polymer Electrolyte Membrane Fuel Cells.” Journal of the Electrochemical Society, 151:4, A623 (2004).

• Ramani, V., H. R. Kunz, J. M. Fenton. 2005. “Stabilized Heteropolyacid/Nafion® Composite Membranes for Elevated Temperature / Low Relative Humidity PEFC Operation.” Electrochimica Acta, 50:5, 1181 (2005).

• Song, Y., Y. Wei, H. Xui, M. Williams, Y. Liu, L. J. Bonville, H.R. Kunz, and J.M. Fenton. 2005. “Improvement in high temperature proton exchange membrane fuel cells cathode performance with ammonium carbonate.” Journal of Power Sources, 141:2, 250 (2005)

• M.A. Hickner, H. Ghassemi, Y.S. Kim, B. Einsla and J.E. McGrath, Alternative Polymer Systems for Proton Exchange Membranes, Chemical Reviews (2004), 104(10), 4587-4611

• K.B. Wiles, C. M. de Diego and J .E. McGrath, Poly(arylene sulfide sulfone) Copolymer Composites for Proton Exchange Membrane Fuel Cell Systems: Extraction and Conductivity, Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) (2004), 45(1),724-25.

• Y. Li, T. Mukundan, W. Harrison, M.L. Hill, M. Sankir, J. Yang, and J.E. McGrath, Direct Synthesis of DisulfonatedPoly(arylene ether ketones)s and Investigation of Their Behavior as Proton Exchange Membrane (PEM),American Chemical Society, Division of Fuel Chemistry Preprints, (2004), 49(2), 536-537.

Presentations• “High Temperature Membrane Electrode Assembly Development for Proton Exchange Membrane Fuel Cells.”

Keynote Presentation by Dr. Fenton, 14th International Conference on the Properties of Water and Steam, Kyoto, Japan, August 29 – September 3, 2004. (L. J. Bonville and H.R. Kunz co-authors)

• “Alternative Materials for Improved Performance and Durability of PEM Fuel Cells”, L.Protsailo, A.Haug, J. Meyers; Fuel Cells 2005, Pacific Grove, California , February 2005

• Advanced Polymeric Materials for Proton Exchange Membranes, J.McGrath; Gordon Research Conference on Fuel Cells, July 28, 2004.

May 2004 – May 2005: Over 25 publications in refereed journals and over 35 presentations


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

S. MukerjeeN. HakimP. Adcock

N. CipolliniT. MaddenB. LeTourneauL. Chen

development of high temperature membranes and improved ... · technical accomplishments: pt alloys...

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