Advanced MEAs for Enhanced Operating Conditions ...3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 12 0 0.4 0.6 0.8 1.0 Technical

2005 DOE Hydrogen Program Review

Advanced MEA’s for Enhanced Operating Conditions, Amenable to High

Volume Manufacture

Mark K. Debe 3M Company May 23, 2005

Project ID # FC3

This presentation does not contain any proprietary or confidential information

Overview Timeline Barriers

• Project start 1/1/02 O. Stack Material & Mfg Cost

• Project end 12/31/05 P. Durability

• 80% complete Q. Electrode Performance R. Thermal & Water Mgmt

Budget Targets • Total Project funding

$7 million DOE $2 million contractor share

• Cost: $35/kW, • Durability: > 5000 hrs, • Precious metal loading: 0.2 g/

• Received in FY04: $2 million rated kW

• Projected funding for FY05: $1.8 For fuel cell stack system for 2010 from HFCIT MultiYear Plan

million Partners

• Case Western Reserve Univ. • University of Miami • Colorado School of Mines • University of Minnesota • Dalhousie University • VAIREX Corporation • University of Illinois • Collaboration with LBNL and BNL

3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 2

Objectives

Overall Contract Objective Development of high performance, high durability, lower cost membrane electrode assemblies (MEA’s) qualified to meet demanding system operating conditions of higher temperature, little or no humidification, while using less precious metal catalyst.

Past Year Objectives a) Tasks 1 & 3: Demonstrate PFSA based MEA capability with:

adequate membrane and catalyst performance to meet 0.2g Pt/kW , durability to potentially operate for 5000 hours in the range of 85 < T < ~ 120ºC under subsaturated inlet conditions with startstop cycling, and pilotscale production levels.

b) Task 2: Development and characterization of new proton conducting electrolytes and incorporation into membranes for operation at T > 120ºC, based on nonaqueous proton conduction mechanisms.


Approach Tasks 1 and 3: 85 < T < 120oC MEA by rollgood processes a) Develop 3M PFSA membranes for operation at 85 < T < ~ 120ºC, with

enhanced durability operating on low humidification and pilot scale production capability.

b) Developed advanced 3M NanoStructured Thin Film (NSTF) catalysts with high performance at ultralow Pt loadings having enhanced durability for operation over 85 < T < 120ºC with startstop cycling, using pilot scale production capability.

c) Match the 3M PEM and 3M NSTF catalyst for optimum performance, durability

d) Advance pilot scale process development for rollgood catalyst coated membrane (CCM) fabrication of the NSTF catalysts and 3M PEM from c).

e) Optimize the MEA GDL for dry operation with the CCM from d).

Task 2: High temperature electrolytes (T > 120oC): a) Develop membranes comprising polymers blended with stable nonvolatile

3M superacids. b) Investigate new heteropolyacid additives for proton transport under hotter,

drier conditions and methods for stabilizing in presence of water.


Technical Accomplishments Task 1, Task 3: 85 < T < 120oC MEA by rollgood processes New 3M PEM shows greater than 15x increase in lifetime under 90/70/70oC load

cycling accelerated tests, compared to standard PFSA membrane. 3M PEM shown to have higher conductivity at lower waterpersulfonate group. New 3M PEM maintains 2530 mS/cm conductivity at 120oC and 80oC dewpoint

Over 1000 ft of 3M PEM coated at pilot scale. 3M NanoStructured Thin Film catalysts achieved 0.22 gPt/kW at 100kPA with

0.12mgPt/cm2MEA; and < 50 mV of mass transport overpotential at 2 A/cm2. 3M NSTF/3M PEM MEA demonstrated over 1000 hour lifetime at 120oC

3M NSTFternary catalysts produce 75x less F than Pt/carbon dispersed catalysts at 120oC with same PEM and GDL.

3M NSTF catalysts are ~ 80x more resistant to loss of ECSA via Pt dissolution by CV cycling between 0.6 – 1.2 volts, than Pt/carbon dispersed catalysts.

Task 2 : T > 120oC electrolytes Performance in fuel cell under H2/air at 110oC better than PBI/H3PO4 with

catalyst loading of only 0.4/0.4 mg/cm2 Pt/Pt (3M acid more ORR compatible). Pulse field gradient spin echodiffusion measurements show lower activation

barriers for H+ transport of new heteropolyacids, and higher maximum Temps. Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 53

Technical Accomplishments – 3M PEM Definition The new 3M ionomer has a slightly shorter side chain than standard PFSA membrane ionomer without the pendant CF3 group:

Gives: higher degree of crystallinity, higher modulus, higher Tg at a given equivalent weight (EW).

Allows: lower EW membranes with higher conductivity, improved mechanical properties and durability under hot, dry conditions.

enhanced oxidative stability in Fenton’s test

(CF2CF)n(CF2CF2) (CF2CF)n(CF2CF2)m m

OCF 2CFOCF 2CF2 OCF2CF2CF2CF2

CF3 SO3H SO3H

Standard PFSA New 3M Polymer


6

8

10

12

14

Technical Accomplishments – 3M PEM Performance Comparison of conductivity at 30°C vs. hydration state (λ) of

1000 EW 3M membrane and standard 1100 EW PFSA membrane

3M Membrane (1000 ew, cast)

Std. PFSA (1100 EW, extruded)

0.14

λ (W

ater

Mol

ecul

es p

er S

ulfo

nate

Gro

up)

3M Membrane

Std. PFSA

0.12

0.1

σ (S

/cm

)

0.08

0.06

0.04 4

0.02 2

00

0 0.2 0.4 0.6 0.8 1 0 5 10 15 20 25

(% RH) λ (Water Molecules per Sulfonate Group)

3M membrane exhibits lower water Conductivity of the 3M membrane uptake for the same water activity increases more rapidly with number of compared to the standard PFSA water molecules per sulfonate group than membrane. standard membrane. This should allow

T. Zawodzinski et al., CWRU drier operation of the MEA.


Technical Accomplishments – 3M PEM Performance

3M membranes with multiple EW’s have been fabricated and evaluated.

• Conductivity vs. temperature for EW ionomers in 730 – 980 EW range. • The lowest EW ionomer tested so far, 730 EW, shows a conductivity

of about 2530 mS/cm at 120˚ C, 80˚ C DP, very dry conditions.

Proton Conductivity at 80C Dew point

1.00 AC 4point probe measurement, at ambient

3M PFSA 730 EW 3M PFSA 830 EW 3M PFSA 900 EW 3M PFSA 980 EW

Con

duct

ivity

, S/c

m

pressure. 0.10

0.01 70 80 90 100 110 120

Temp (˚C)


130

Technical Accomplishments – 3M PEM Durability

0.460 with lower EW under hot, 0.440 dry conditions.

• Lifetime defined as when 0.420

OCV drops below 800mV. 0.400

Lifetime and performance vs. EW under load cycling. /cm2V at 0.5A

3M 1,000 EW 3M 900 EW 3M 800 EW 3M 700EW

• No statistically significant Normalized lifetime 5 samples each 200lifetime difference between 180

700 to 1,000 EW 160

0.540 • Test run at 90˚C, 28% RH, 0.520 load cycles between OCV 0.500 and 0.5 A/cm2.

• Performance increases

Nor

mal

ized

Life

time

Vo

lts

0.480

membranes in this test. 140

120

• All MEA’s tested with 100

dispersed Pt/C ink 80

60electrodes with 0.4/0.4 mg 40

Pt / cm2. 20

0 3M 1,000 EW 3M 900 EW 3M 800 EW 3M 700EW


Performance and lifetime during accelerated durability testing

Technical Accomplishments – 3M PEM Durability

Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 10

00.10.20.30.40.50.60.70.80.9

1

0 0.2 0.4 0.6 0.8 1 1.2

Current Density

Volta

ge

0.060.070.080.090.10.110.120.130.14

mO

hms

cm2

StartAfter 2800 hoursAfter 3500 hoursResistance Start Resistance 2800 hoursResistance 3500 hours

3500>50017.078.1

2800>5003.4102.9

0>5004.2178.3

Testing Time

Short Resistance

(OHMCM2)

H2Crossover (mA/cm2)

Pt/Carbon SEF

(M2/M2)

• 3M membrane with additives shows >15 X increase in lifetime (4 cell average ~ 4100 hrs) vs. 50 micron extruded standard PFSA membrane under load cycling tests at 90oC, w/70oC dewpoints.• Accelerated durability testing was stopped periodically and sample was tested at 70˚C 100%RH. No increase in crossover or shorting was detected before 3500 hours. IR change of PEM was minimal. Most performance loss due to loss of catalyst surface area or mass transport.

3

[111]

1 nm1 nm

Technical Accomplishments – NSTF Fundamentals

Relating fundamental catalyst morphology to enhanced properties. Scanning Transmission Surface free energy of crystallites

3M Scanning Electron Microscopy images are minimized by truncating a [111] Electron Micrographs from U. of Illinois faceted pyramid with a [100] top.

[100]

10 nm10 nm

1 nm1 nm

a

b

Experimentally measured values of a ~ 2nm, b~ 6nm or a/b=1/3.

Calculated energy minimized when r = a/b ~ 0.33.

“Whiskerettes” growing on the sides of the larger whiskers as pyramidal crystallites with fcc(111) side facets and fcc(100) truncated top. (L. Gancs, A. Wieckowski)


Technical Accomplishments – NSTF Catalyst Devel. PtAxBy NSTF ternary catalyst development

113 different compositions/structures fabricated, all by rollgood process. Specific activities in 50 cm2 cells depend on a structure factor, and composition Best performances obtained for most durable catalysts (see later slides) and their performance is insensitive to structure factor, implying a large process window

Best PtCD NSTF ternary Summary of NSTF Ternary Cathode loading: 0.1 mgPt/cm2 Catalyst Specific Activities Anode loading: 0.15 mg/cm2

Spe

cific

Act

ivity

(A/c

m2

Pure Pt 0

1

0 1

(

3

H2/air

PDS(0.85,0.25,0.048,10s/pt)

Cel

l vol

tage

(V)

rea

l)

0.000

0.010

0.020

0.030

PtCx2Dy2 PtCx4Dy4 PtAx2Dy2 PtAx4Dy4 PtDx1By1 PtAx2By2 PtAx3By3 PtCx1By1 PtCx2By2

0.2

0.4

0.6

0.8

0.2 0.4 0.6 0.8 1.2 1.4

Structure Factor S.F.) = 1.2

S.F.=2.1 S. F. =

75C cell, 0/0 psig inlet,

CF800/1800 sccm, Humidity: 66%/45%

0.5 1 1.5 2 2.5 3

NSTF Structure Factor J (A/cm2)


0

0.4

0.6

0.8

1.0

Technical Accomplishments – NSTF Catalyst Loadings NSTF Catalysts with Ultralow Pt Loading Continue to Improve

• Little effect of anode loading over range of 0.05 to 0.2 mg Pt/cm2 above 0.6 V in MEA’s having PtC Dy ternaries (0.1mg Pt/cm2 ) on the cathode.x

• 3M record performance achieved by better matching NSTF ternary catalyst and whisker support size and density, in MEA’s having 0.060 mgPt/cm2 on A/C.

NSTF MEA (3M PEM and GDL) Performances with Different Anode Pt Loading (.05 to 0.2 mg Pt/cm2)

Cathode: PtAB ternary w/0.1 mg Pt/cm20.12 mg Pt/cm2 total per MEA

V (v

olts

)

2 each

75o2

2

/) ( )

0.4

0.5

0.6

NSTF Loading: A/C = 0.060 mgPt/cm

C cell. Ambient Pressure, H /Air CF: 800/1800 sccm, 50 cm Humidity: 66% 45% PDS(0.85,0.25,0.048,10s , PSS 0.4V,5min3MPEM 1000 EW, 30 microns

0.8

0.7

, 1

0.9 / /45%

/ /72% / /72% / /72%

/ 2/air / l

i/ )

5 min)

FC9321495, 0.15 mg Pt cm2, 66%FC9497483, 0.2 mg Pt cm2, 72%FC9498572, 0.1 mg Pt cm2, 72%FC9499318, 0.05 mg Pt cm2, 72%

75C cell, 00 psig inlet, HCF8001800 sccm, counterfow. Humdity: as stated PDS(0.85,0.25,0.048,10spt , PSS(0.4V, C

ell V

olta

ge (V

)

0.3

0.2

0.1

0

2)J (A/cm0.0 0.2 0.4 0.6 0.8 1.0 1.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4

FC10206graph1 J (A/cm2)


0.0

0.2

Technical Accomplishments – NSTF electrode Mass transport overpotential (MTO) correlated to NSTF electrode thickness

MT

Ove

rPot

entia

l at 2

A/c

m2 (m

V)

0

20

40

60

80

2

600 800 1000

2 possible for Pt ternary constructions w/ 0.1mgPt/cm2

thicknesses from known loadings

porosity is ~ 75%, filled with ionomer.

HFR

45 mV

TcelloC

H2 i /2.5 H2/

i

70 mV/decade

E(V

) and

Ei

(V)

100

120

140

160

180

200

FC8565

FC8749

FC8876

FC8752

MT

Ove

rPot

entia

l at 2

A/c

m (m

V)

1200 1400 Catalyst Volume/Unit Area (Angstroms)

• MTO < 50 mV at 2A/cm

• SEM thicknesses agree with calculated

• Allows determination that electrode

0.0

0.2

0.4

0.6

0.8

1.0

IRcorrected

Measured

Not Xover corrected

= 80/air Sto ch = 2.0air pressure = 30 psig

Humid ty: 60%/60% RH

reference line

rfre

e

200

180

160 . 140

120

100

80

60

40

20

0

FC8565graph 16 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.1 CorrMaa Xfer Loss vs Cat Vol graph 4 i (A/cm2)

1 Electrode Layer Thickness by SEM (µm)


0 4 8 12 16 20 24 280

20

40

60

80

100

120

140

160

180

Const Volt. = 0.4 VT = 90oCA/C RH = 100% A/C P = 200kPaA/C FR = 800/1800 SCCMSame 3MPEM and 3MGDL

PtCD

PtAD

FC9xxx F Release Summary Graph 19

Cat

hode

F R

elea

se (n

g/m

in5

0cm

2 )

NSTF Ternary Structure Factor


• F release rates (by IC) measured for a series of PtAxDy and PtCxDyNSTF ternary catalysts under a fixed protocol.

• F release( peroxide generation) rate is a function of NSTF construction.

• NSTF catalysts do not contain carbon, so any peroxides generated on carbon of carbonsupported dispersed Pt is eliminated.

• NSTF catalysts have 5x higher specific activity than Pt/Carbon, implying less H2O2production

NSTF catalysts and H2O2 production and F release ratesTechnical Accomplishments – NSTF MEA Durability


• Same 3M PEM• Same 3M GDL

Technical Accomplishments – NSTF Durability120oC Stress tests of MEA and catalyst surface area durability CJ = 0.4 A/cm2, 100 cm2 cell, 300kPa H2/air, A/C inlet % RH = 61%/84% 18 – 66 hrs at 120oC, water collected for F release, then 6 hrs at 75oC for

ECSA, H2 crossover, short resistance measurements. Cycle repeated.Recent results comparing NSTF and Dispersed Pt/Carbon (Neat 3M PEM) reversible impurity adsorption during each 18 hr cycle (cleans up during CV) NSTF MEA lifetimes 1520 x longer than dispersed Pt/Carbon catalyst MEA. MEA lifetime scales with F release. NSTF F release ~ 75 x less than Pt/C.

Lifetime versus F- ion release rate for NSTF and Dispersed Pt/C MEA’sVoltage vs time for NSTF and Pt/C MEA’s at 120oC

0 150 300 450 600 750 900 1050 1200 1350 1500 1650 18000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Same 3MPEM and 3MGDL on all MEA's.

Pt/Carbon #2: 0.2 mg/cm2

Pt/Carbon #1: 0.4 mg/cm2

NSTF PtCx2Dy2, 0.1 mg/cm2

Total time on test = ~1825 hoursTime at 120°C = ~1082 hours

Stress Conditions: 120°C Cell, Water Balance ~1.1, 30psig, CF723/CF1330, H2/Air

V at

0.4

J (A

/cm

2 )

FC9824Menomoniegraph4Time (hours)0.1 1

0

200

400

600

800

1000

1200

# 2# 1

Pt/CarbonNSTF PtAx1Dy1

NSTF PtCx2Dy2

NSTF PtCx2Dy2(Still Operating 04/20/05)

FC9824Menomoniegraph 5

Life

time

Hou

rs a

t 120

o C

F Ion Release Rate (µg/min)


0 5 10 15 20 25 30 35 40 45 500.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Total F Release (µg/min)

1824 hourson Station

576 hourson Station

1082 hoursat 120°C

982 hourson Station

Slope of line = 0.00314 V/Stress Test Number = 0.077 mV/Hour on Station

Stress Test conditons: 120C, water balance ~1.1, 30psig

FC9824Menomoniegraph3

Pea

k Vo

ltage

Afte

r Eac

h R

esta

rt (V

)

Stress Test Number

NSTF peak voltage and F- ion release rateduring 1825 hr test, 1080 hrs at 120oC.

To – date : Best NSTF MEA = NSTF ternary PtCx2Dy2 (0.1 mg Pt/cm2)

+ Neat 3M PEM (no additives, or edge protection tested yet)+ 3M GDL

Cathode and anode surface area losses stabilize to ~ 40% and 50% of initial value. Shorting and H2 crossover values remain stable and low until end of life. F ion release rate at 120oC remains < 24 nanogram / hr cm2 over 1800 hours. Decay rate of peak voltage is ~ 77 microvolts/hr over 1800 hr lifetime.

Technical Accomplishments – NSTF Durability

0 200 400 600 800 1000 1200 1400 1600 18000

2

4

6

8

10

12

14

16

18

20

FC9824menomoniegraph2

Anode ECSA Cathode ECSA Cathode H2 Crossover (mA/cm2, not measured with anode overpressure) Cathode Short Resistance (Kohmcm2, not measured with anode overpressure)

Stress Test conditons: 120C, water balance ~1.1, 30psig

EC

SA

, H2 C

ross

ove

r, S

hort

Res

ista

nce

Time (hour)

Surface areas, short resistances, and H2-cross-over of NSTF PtCD MEA at 120oC.

CV cycling stability of catalyst surface area as a function of temperature for one NSTF PtCD ternary versus Pt/Carbon catalysts.

CV cycling stability of catalyst surface area at 80oC for NSTF Pt and best NSTF ternary

versus Pt/C and Pt/graphitic carbon.

0 3000 6000 9000 12000 150000.01

0.1

1

CV cycling datagraph 13

Pt/Graph C(0.4 mg Pt/cm2)

Pt/Carbon (0.4 mg Pt/cm2)

Four NSTF Pt and PtAB ternary (0.10 mg Pt/cm2)

Nor

mal

ized

EC

SA

Number of CV Cycles at 80oC

20 mv/secA/C: H2/N2RH:100/100%


• NSTF catalysts are much more resistant to loss of surface area from high voltage cycling than are dispersed Pt/Carbon or Pt/graphiticcarbon catalysts. • NSTF catalysts should be more robust against shut down/startup, and local H2

starvation. 70% of NSTF ECSA remains after 12,000 cycles to 1.2 volts at 80oC.

Technical Accomplishments – NSTF Durability


CV cycling measurements from 0.6 – 1.2 V test stability against Pt dissolution

0 3000 6000 9000 12000 150000.01

0.1

1

Pt/CNSTF90oC

NSTF85oC

NSTF75oC

NSTF75oC

NSTF 95oC

65oC

Pt/C80oC

Pt/C 95oC

CV cycling datagraph 14

Nor

mal

ized

EC

SA

Number of CV Cycles


3

30 40 50 60 70 80 90 100 1100.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

90/0/0oC85/0/0oC

80/0/0oC

75/0/0oC

70/0/0oC

7090C cell0/0% Inlet RH

15/15psig H2/AirCS2/2

GSS(0.4, 120min)

HFR

(ohm

cm

2 )

Outlet RH (%)

Technical Accomplishments – Thermal Water Manag.Dry operation –GDL Screening and Optimization• Operation with totally dry inlet H2/air is possible at 75oC and 200kPa with no loss

of performance for some GDL/NSTF combinations. (1000 EW 3M PEM)• Introducing some inlet RH allows operation at higher ToC.• Further optimization necessary for both hot dry and cold start.• All GDL’s are rollgood fabricated, like NSTF and 3MPEM.


Cell voltage operation at 15 psig and 0%/0% RH inlet humidification with varying temperature for different GDL’s.

30 40 50 60 70 80 90 100 1100.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

90/0/0oC

85/0/0oC 80/0/0oC

75/0/0oC 70/0/0oC

7090C cell0/0% Inlet RH

15/15psig H2/AirCS2/2

GSS(0.4, 120min)

Cel

l V (V

olts

) @ G

SS(0

.4)

Outlet RH (%)

High frequency impedance changes at 15 psig and 0%/0% RH inlet humidification for varying temperature (7090oC) with different GDL’s.

2 hrs stabilization time/point

Technical Accomplishments – Performance Targets


• NSTF Pt specific power density is < 0.3 gPt/kW for cell voltages < 0.70 Vfor conditions shown. Entitlement may be lower still due to:

- Opportunity to increase mass activity by optimizing support whisker- Opportunity to further reduce impedance of electrode and GDL

• NSTF catalyst based MEA’s with 3M PEM clearly show potential toreach 5000 hours of lifetime for 80oC < T < 120oC, due to:

- Enhanced stability and lower F- release rates of NSTF catalyst, - Enhanced stability, mechanical properties of 3M PEM

• Stable operation with totally dry input gases is possible under conditions near water balance –requires optimization of the GDL and further gains matching lower EW PEM to NSTF catalysts.

• All 3M PEM, NSTF catalyst, and GDL are currently fabricated using scalable, cost-effective, roll-good fabrication processes.

0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.850.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.06mgPt/cm2 on cathode0.06mg Pt/cm2 on Anode.

100kPa H2/air, CF 800/1800sccm

0.10mgPt/cm2 on cathode0.05mg Pt/cm2 on Anode.300kPa H2/air, CS 2.0/2.5

DOE 2005 Targetat rated power

DOE 2010 Target

NSTF Pt-Specific Power Densities (gPt/kW)

FC8565 - graph 32

g-Pt

/ kW

Cell Voltage (V)

0.001

0.01

0.1

1

80 90 100 110 120 130

Temperature, C

Con

duct

ivity

S/c

m

Acid A Acid B Acid CPBI Phos acid 1:6

Technical Accomplishments – Electrolytes for T > 120oC


• Temp/RH dependence was significantly lower for polymer swollen with Acid A than with Acid B or C measured by AC impedance. Conductivity was measured with an 80˚C dew point.

• Polymer swollen with Acid C retained acid much better when immersed in water than PBI/H3PO4 as shown by pH versus time.

• Even though Acid C had lower conductivity, Fuel cell performance was higher, presumably due to better cathode kinetics.

H2/Air, 110/80/80, 0.4/0.4 mg/cm2 Pt/Pt

00.10.20.30.40.50.60.70.80.9

0 0.2 0.4 0.6A/cm2

V

Acid CMembranePBI Phos acid1:6

0

1

2

3

4

5

6

0.0 1.0 2.0 3.0 4.0 5.0 6.0Time (min.)

pH

Acid C membrane

PBI Phos acid 1:6

Technical Accomplishments – Electrolytes for T > 120oC


Pulse Field Gradient Spin Echo –Diffusion Measurements

• Preliminary measurements on dry membranes

• Control Ea = 27.5 KJ mol1, Most HPA doped around 15 KJ mol1

0

2

4

6

8

10

12

0 20 40 60 80 100 120 140T (oC)

D x

107

cm

2s1

Control dryPFSA1% HPA Y dryPFSA5% HPA Y dry

SAXS• Two scattering domains:• hydrophilic <D> 1.7, d 3.1 nm – dry

<D> 3.8, d 5.1 nm – wet• hydrophobic <D> 8, d 14 nm – wet or dry• HPA – higher scattering intensity, larger

distribution of scattering domains and a Bragg peak corresponding to HPA crystallites

0

1

10

100

0.1 1 10q (nm1)

SA

XS

Inte

nsity

3M ionomer Dry

3M ionomer in H2O

3M ionomer+1%HPA X Dry

3M ionomer+1%HPA X in H2O

3M ionomer+5%HPA X Dry

3M ionomer+5%HPA X in H2O

A. Herring, Colorado School of Mines

Response to 2004 Reviewers’ Comments 1. “I have mixed reactions to 3M’s claims re: less fluoride generation by their

new membranes. Are these results because of mismanufacturing of Nafionbased MEA’s?”

* F release rates from new 3M PEM are well documented and correlate with much longer lifetimes under accelerated testing.

* 3M has sold over 200,000 MEA’s using Nafion based ionomers andhas optimized the manufacturing process.

* 3M’s NSTF catalysts can lower F rates even further with 3M PEM.

2. “Stay the course but do accelerate the outside collaborations with industry.” * 3M will introduce the new 3M PEM to selected customers 2nd quarter 2005, and NSTF ternary MEA’s to selected customers end of 2005.

3. “Conductivity and fuel cell polarization measurements should be extended down to 20oC, perhaps even down to –20oC.”

* Low temperature testing is outside the scope of the project and DOE targets for the contracted work.

* However, cold start and freeze tolerance are very important and are being studied at 3M.


Future Work

Completion of Task 3: Advanced MEA Development for 85< T < 120oC: MEA pilot level scaleup and large area stack testing.

• M1 – downselection of final x/y values for PtCxDy ternary and loading • M2 – downselection of final 3MPEM properties for durability, rampup • M3 – downselection of final GDL for reduced IR loss and dry operation • M4 – CCM process transfer to new pilot scale equipment • M5 – Statistical validation of pilot scale rollgood fabricated CCM’s • M6 – MEA fabrication for designated stack testing (312 cm2) • M7 – Short stack testing (~ 35 kW) • M8 – Testing customized Vairex air management systems w/NSTF MEA.

Completion of Task 2: High Temp. Electrolytes for T > 120oC.

• Further characterization of polymer/acid combinations focused on membrane conductivity and stability.

• Moving to immobilized heteropolyacids for fuel cell testing.


Publications & Presentations 1. “Dissolution of Fe and Ni in Combinatorially Sputtered Pt 1x Fe and Pt 1x Nix(0<x<1) Electrocatalysts,” A.x

Bonakdarpour, J. Wenzel, D. A. Stevens, S. Sheng, T. L. Monchesky, R. T. Atanasoski, A. K. Schmoeckel, G. D. Vernstrom, M. K. Debe and J. R. Dahn, presented at the First International Conference on Fuel Cell development and Deployment, March 710, 2004, Connecticut Global Fuel Cell Center, Stores, CT.

2. “Studies of Transition Metal Dissolution from Combinatorially Sputtered, NanoStructured Pt 1x Mx (M=Fe, Ni;0<x<1) Electrocatalysts for PEM Fuel Cells,” A. Bonakdarpour, J. Wenzel, D. A. Stevens, S. Sheng, T. L. Monchesky, R. Lobel, R. T. Atanasoski, A. K. Schmoeckel, G. D. Vernstrom, M. K. Debe and J. R. Dahn, J. Electrochemical Society, Vol. 152 (1), 2005, A61A72.

3. “Insitu Vibrational Spectroscopy with Fuel Cell Catalysts,” Andrzej Wieckowski, Lajos Gancs, Matthew McGovern, GuoQiang Lu, Radoslav Atanasoski, and Mark K. Debe, presented at the American Chemical Society meeting, Anaheim, CA, March 29April 2, 2004.

4. “Advanced MEA’s for Enhanced Operating Conditions,” 2004 DOE Hydrogen Fuel Cells and Infrastructure Technologies Annual Review, Philadelphia, PA, May 24-27,2004.

5. “Advanced MEA’s for Enhanced Operating Conditions,” submitted for 2004 Hydrogen Program Annual Report, July, 2004.

6. “NanoStructured Thin Film, Thin Layer Electrodes Optimized for PEM Fuel Cell Performance at High Current Density,” 2005 Fuel Cell Seminar, San Antonio, TX, Nov. 15, 2004.

7. “Corrosion of Transition Metals in Pt 1xMx (M=Fe, Ni, Mn) Proton Exchange Membrane Fuel Cell Electrocatalysts,” A. Bonakdarpour et al., presented at the Fall 2004 Electrochemical Society Meeting, Honolulu, HI, USA.

8. “64Channel Fuel Cell for Testing Sputtered Combinatorial Arrays of Oxygen Reduction Catalysts,“ D. A. Stevens et al., presented at the Fall 2004 Electrochemical Society Meeting, Honolulu, HI, USA.

9. “Combinatorial PEM Fuel Cell Studies of Binary Platinum Alloys,” D. A. Stevens et al., presented at the Fall 2004 Electrochemical Society Meeting, Honolulu, HI, USA.

10. “The Search for Higher Temperature Proton Conductors for the PEM Fuel Cell,” J. Woods Halley, Symposium on Fuel Cells, MRS Meeting, Boston, MA, December 1, 2004,

11. "The Development of New Membranes for PEM Fuel Cells", Steve Hamrock, Advances in Materials for Proton Exchange Membrane Fuel Cell Systems, Asilomar Conference Grounds, Pacific Grove, CA, February 21, 2005.


Hydrogen Safety

The most significant hydrogen hazard associated with this project is:

• Accidental H2 release in cylinder closet leading to ignition from: H2 line or manifold breach Accident during replacement of cylinders


Hydrogen Safety

Our approach to deal with this hazard is: • Design

Hydrogen cylinder closet and gas distribution system adhere to codes. Reduction in number of cylinders in the closet 2step regulators (less susceptible to failure and designed to fail closed) H2 sensors in all labs and cylinder closet, alarm system Automatic shutoff of H2 gas supply if sensors detect H2 release

• Procedures SOP’s for cylinder changing, alarm responses, test station operation Cylinder changing restricted to highly trained personnel Regular maintenance checks – sensors, leak check of valves etc.

• Installing H2 Generator (in noninhabited mechanical room) to significantly reduce total volume of H2 in facility


Documents

Advanced MEAs for Enhanced Operating Conditions ...3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 12 0 0.4 0.6 0.8 1.0 Technical