advanced cathode catalysts and supports for pem fuel cells · electrode (catalyst and support),...

1

Advanced Cathode Catalysts and Supports for

PEM Fuel CellsMark K. Debe3M CompanyMay 20, 2009

Project ID: FC_17_DebeThis presentation does not contain any proprietary, confidential, or otherwise restricted information

2009 DOE Hydrogen Program Review

3M Advanced Cathode Catalysts ……………………... 2009 DOE Hydrogen Program Review, May 18-22

OverviewTimeline

Project start : April 1, 2007Project end : March 30, 201150% Complete (3/30/09)

BarriersA. Electrode and MEA DurabilityB. Stack Material & Mfg CostC. Electrode and MEA Performance

DOE Technical TargetsBudgetTotal Project funding $10.43MM

$8.34 MM DOE and FFRDC$2.09 MM 3M share

Received in FY08: $1.621 MMEst. Funding for FY09: $1.962MM

Dalhousie University (J. Dahn, D. Stevens)JPL (S. R. Narayanan, C. Hays)ANL (N. Markovic, V. Stamenkovic)Project Management – 3M

Partners

Electrocatalyst/ MEA 2010 2015

Lifetime Hrs, > 80oC 2000 5000

Mass Activity(A/mg) 0.44 0.44PGM, (g/KW rated) 0.3 0.2

Performance @ Rated (W/cm2 ) @ 0.8V

10.25

10.25

Additional InteractionsGM Fuel Cell Activities - Honeoye FallsLANL(NIST), ORNL(TEM), ANL (modeling) Proton Energy Sys.; Giner EC Sys. LLCVarious Vendors: for GDM components

3

Define and implement multiple strategies for increasing NSTF support surface area, catalyst activity and durability, with total loadings of < 0.25 mg-Pt/cm2 /MEAWork closely with subcontractors to fabricate and screen new electrocatalysts using high throughput characterization methods, for activity and durability gainsConduct fundamental studies of the NSTF catalyst activities for ORRApply more severe accelerated tests to benchmark the NSTF/MEA durabilityDefine and implement multiple strategies to optimize the MEA water managementAdvance the high volume roll-good NSTF catalyst / membrane integrationWork closely with system integrator to validate NSTF functional properties/issues

Development of a durable, low cost, high performance cathode electrode (catalyst and support), that is fully integrated into a fuel cell membrane electrode assembly with gas diffusion media, fabricated by high volume capable processes, and is able to meet or exceed the 2015 DOE targets.

Overall Project Objectives

3M Advanced Cathode Catalysts ……………………... 2009 DOE Hydrogen Program Review, May 18 -22

Objectives for Past Year

4

4/1/09

Project Timeline and MilestonesBudget Period 1 Budget Period 2

4/1/07 01/01/10

Q1 Q12 Q16Q11

= Go-No Go for Extension of Task

= Go-No Go for Stack Testing = Go-No Go for Large Area, Single Cell Durability Tests

Task 1.3 – Activity Optimization

Task 1.1 – ECSA OptimizationTask 1.2 – Cat. Fundamentals

Task 2 – Cat. Durability Gains

Task 5.1 PEM Integration, Task 5.2 GDL Integration

Task 3

Task 4 – Support durabilityTask 5.3

3M Advanced Cathode Catalysts ……………………... 2009 DOE Hydrogen Program Review, May 18 - 22

Q2 Q3 Q4 Q5

5/20/093/31/11

Q6 Q7 Q8 Q9 Q10

Task 6 – Start-up, conditioning

5

Technical Progress: Task 1 - NSTF catalyst and support fundamentals


NSTF fundamentals – A key focus ~ 500 MEA’s in past 9 months

Increased understanding of fundamentals of whisker geometry:• determining process conditions to generate desired whisker

geometric characteristics (on roll-good production equipment)• two of three designed experiments completed for whisker growth: SEM characterization, fuel cell testing for 14 metrics• relating whisker characteristics to ultimate catalyst ECSA,

particle size, shape, and how those relate to activity• developed model for calculating catalyst ECSA as a

function of whisker geometric factors: N(µm-1),L(µm), ρalloy, Pt loading, roughness factors, backplane deposition

Increase knowledge of how to control the critical factors determining ORR for a given catalyst type and loading: • catalyst composition (> 30 Pt alloys in hundreds of MEAs)• grain size, optimum crystal facets, lattice parameters • surface structure or composition modulation.

0.00 0.03 0.06 0.09 0.12 0.15 0.18 0.210.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

NucleationRegion

Metal islands at preferred sites Square-truncated pyramid crystallites

Elongated whiskerett (along the pillar) Whiskerett: a pyramid top on a tilted pillar

6-7 nm

Whisker side plane

Metal deposition

Short Whisker, L = 0.52μm

Aspect ratio ~ 2 in [111] direction.

Whiskerette growing

Nearly Spherical

Shape

Very low extension in [200] direction

Same extension in[111] and [220]

directions

Longest in [311] direction

WAO 2800-4, N = 73/μm2, L = 0.52μm

Ratio for Spherical Grain

Activity vs Grain Size - graph 9

Rat

ios

of (1

11)/(

hkl)

Gra

in S

izes

Pt Loading (mg/cm2)

111/200 111/220 111/311

Pt fcc grain size ratios vs loading

45 50 55 60 65 70 75 80 852

4

6

8

10

12

14

16

18Std. Pt68.7Co28.5Mn2.7 on WAO-1 Whisker Series

Activity vs Grain Size - graph 30

EC

SA

(cm

2 Pt /c

m2 pl

anar )

Pt(111) Grain Size (Angstroms)

WAO-1 ECSA, ML-2 and P4 Coated - 0.05 mg/cm2 WAO-1 ECSA, All P4 Coated - 0.2mg/cm2 WAO-1 ECSA, ML-2 and P4 Coated - 0.15 mg/cm2 WAO-1 ECSA, ML-2 and P4 Coated - 0.1 mg/cm2

ECSA vs fcc grain size & loading

6

Baseline Best-of-Class MEA - Oct., 2007A/C = 0.1/0.15 mgPt/cm2 PtCoMn35 micron 3M PEMNon-standard 3M GDL

Baseline Best-of-Class MEA - Jan., 2009A/C = 0.05/0.10 mgPt/cm2 PtCoMn20 micron 3M PEMImproved 3M GDL

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

FC12969-937R, V FC12969-937R, HFR FC14654-757, V FC14654-757, HFR FC014693-572, V FC014693-596, HFR

Best of Class 1/22/09FC14654, FC14693

Previous Best : A/C = NSTF PtCoMn 0.1/0.15 mgPt/cm2 PEM: 3M 850 EW, 35 micron; GDL: 3M 2975

New Best of Class: A/C = NSTF PtCoMn 0.05/0.10 mgPt/cm2 PEM: 3M 850 EW, 20 micron; GDL: 3M New

Specifc Power Density Projections- graph 6

Galvanodynamic ScansTcell/DP's = 80/68/68 °C H2/air stoich = 2.0/2.5H2/air Inlet pressure = 150 kPaGDS(0.02, 2, 10 step/dec, 180s/pt) 50 cm2 Quad serpentine cell

HFR

Cel

l Vol

tage

(V) a

nd H

FR (o

hm-c

m2 )

J (A/cm2)

MEA Modifications40% reduction in total Pt loading40% reduction in PEM thicknessImproved GDL

Technical Accomplishments: Higher power density, reduced Pt loading

150 kPa H2/Air, 80oC, 67%RH34% reduction in HF impedance40% reduction in mass transport loss85 mV gain at 2 A/cm2


0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

Galvanodynamic ScansTcell = 80°C H2/air stoich = 2.0/2.5H2/air Inlet pressure = 150 kPaRelative Humidity = 67% GDS(0.02, 2, 10 step/dec, 180s/pt)Both MEA electrodes conditioned50 cm2 Quad serpentine cell


FC14693-572, Voltage (V), 150kPa FC14693-572, Power (W/cm2), 150kPa FC14654-757, Power (W/cm2), 150kPa FC14654-757, Voltage (V), 150kPa


Cel

l Vol

tage

(V) a

nd P

ower

(W/c

m2 )

J (A/cm2)

7

48% reduction in gPt / kW at peak power over 2007 - 2008 baseline40% reduction in mass transport over-potential at 2 A/cm2 at 150kPa

0.1 10.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

MTO = 43 mV @ 2A/cm2

E(V

), H

FR (o

hm-c

m2 ) a

nd E

IR-F

ree(V

)

70 mV/decTafel Slope

43 mV

FC14654-757, V FC14654-757, IR-free FC14654-757

HFR

Galvanodynamic ScansTcell/DP's = 80/68/68oCH2/air stoich = 2.0/2.5H2/air Inlet pressure = 150 kPaGDS(0.02, 2, 10 step/dec, 180s/pt)50 cm2 Quad serpentine cell

Specifc Power Density Projections- graph 2J (A/cm2)

New Best of Class MEA Tafel Plot150 kPa Inlet Pressure

Inverse Specific Power Density150 kPa Inlet Pressure

New Baseline MEA exceeds DOE 2015 targets for Inverse Specific Power Density at 150kPa ( < 0.18 gPt total / kW )and total Pt loading: 0.15 mgPt/cm2 of MEA


Technical Accomplishments: Higher power density, reduced Pt loading

0.55 0.60 0.65 0.70 0.75 0.800.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

DOE 2015 Target

Galvanodynamic ScansTcell/DP's = 80/68/68 °C H2/air stoich = 2.0/2.5H2/air Inlet pressure = 150 kPaGDS(0.02, 2, 10 step/dec, 180s/pt)Both MEA electrodes conditioned50 cm2 Quad serpentine cell


FC14654-757FC14693-572

01/22/09

Previous Best of ClassFC12969 - 937R

10/05/07

Cell Voltage (V)

(Spe

cific

Pow

er D

ensi

ty)-1

(gPt

tota

l / k

W)



80 200 400 600 800 1000 12000.0

0.5

1.0

1.5

2.0

2.5

F- Release Rate FC14109 F- Release Rate FC14098

OCV Hold Conditions:90oC, 50 cm2

H2/Air RH = 30%/30%H2/Air P = 250/200 kPaH2/Air FR= 696/1657 sccm

EXP 021_OCV hold under air - graph 2, data 1

F- Rel

ease

Rat

e (μ

g/cm

2 /day

)

Time (hours)

F - ion release rate vs timeOCV vs time


Technical Accomplishments: Accelerated Durability Test: OCV Hold

Open Circuit Voltage Hold TestConditions: 90oC, 30% RH, 250 kPa/200 kPa

H2 Air, CF = 696/1657 sccmTargets: 200 hours, H2 crossover < 20 mA/cm2,

F – ion release monitored onlyPEM: 3M 20 µm, with stabilizing additiveCatalyst: NSTF 0.1/0.15 PtCoMn,Results:• > 900 hours with F – rate < 0.5 µg/cm2/day• H2 X-over < 20mA/cm2 for 0 < t < 800 hrs.

H2 Crossover vs time

0 200 400 600 800 1000 1200 14000

10

20

30

40

50

60

70

80

90

100

H2 Crossover FC14109 H2 Crossover FC14098




H2 C

ross

over

(mA

/cm

2 )

Time (hours)

0 200 400 600 800 1000 1200 14000.0

0.2

0.4

0.6

0.8

1.0

Catalyst: NSTF PtCoMn (0.10 / 0.15 mgPt/cm2)PEM: 3M, 20 μm , commercialized stabilizing additive



Periodic Short and Crossover Tests Under H2/N2


FC14109(1300 hours)

FC14098(900 hours)

OC

V (V

olts

)

Time (hours)

9

Load Cycling DurabilityTest protocol in 2008 Review, FC1 MEA: 0.2 mg/cm2 NSTF PtCoMn, 3M ionomer without stabilizing additives, with mechanical stabilization (W. L. Gore).1st MEA > 7300 hrs reported in 20082nd MEA now completed over 7000 hrsExceeds DOE-2015 5000 hour target

0 1000 2000 3000 4000 5000 6000 70000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

7 Dispersed MEA'sA/C Catalyst:

Pt/Carbon: 0.4 mg-Pt/cm2 PEM: 3M, no chemical or mechanical stabilization

All 7 failed in 200 - 600 hrs.

Shiva all NSTF Data 021808 - graph 3

2- NSTF MEA's A/C Catalyst:

0.2 mg-Pt/cm2 PtCoMnPEM: 3M ionomer in mechanicalstabilized support, no chemical

stabilization,Both exceeded 7000 hrs.

4 - NSTF MEA's A/C Catalyst:

0.2 mg-Pt/cm2 PtCoMnPEM: 3M, no chemical or mechanical stabilizationAv. Lifetime ~ 3500 hrs

Cel

l Vol

tage

at O

CV

Time (hrs)

Technical Accomplishments: Accelerated High Voltage and Load Cycling


Hi Voltage CV Cycling0.6 – 1.2 V, 20 mV/sec, 200kPa H2/N2 at 95/95/95 oC cell/dew points .4000 cycles with periodic metrics. (~ stable between 4000 and 12000 cycles.) Results shown for 2 new best of class CCMs: 0.05/0.10 PtCoMn, 20 µm PEM: 2 MEA’s

1) -0.6% loss and +5% gain in Spec. Act.2) -20% and -30 % loss of ECSA (cm2

Pt /cm2geo)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.60.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

BoC CV 95 - graph 1

Station 11

After Cycling

Initial

80/68/68oC cell, 150/150 KPa inlet, H2/air, CS(2/2.5) GDS(0.02 ->2.0 ->0.02, 10 steps/decade, 120s/pt)

Cel

l Vol

tage

(V)

J (A/cm2)

FC15018 353.DAT FC15018 559.DAT FC15030 319.DAT FC15030 549.DAT

10

New NSTF alloy compositions•All 50 cm2 cell tests at 3M• many tens of new compositions made and tested

DOE/GM metric for ORR activity:•150kPa H2/O2, 100%RH, 0.9V(15-20 min)•Activity targets:0.044 mA/cm2

geo , 0.44 A/mgPt

•Correlation to real H2/air performance?•Different Pt oxidation rates for different alloys?

• Results since Dec. ’08: 100% increase in activity•(33)PtCoMn: 0.164 + 0.024 A/mgPt at 0.1 mgPt/cm2

•(3)PtxMy : 0.33 + 0.01 A/mgPt, at 0.1 mgPt/cm2

0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.0400.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

OR

R(9

00m

V) a

t 5 s

econ

ds (A

/cm

2 plan

ar )

0.15 mgPt/cm2

03/21/09

ORR(900 mV) Absolute Activity at 5 seconds vs 1050 seconds.

PtCo PtNiFe PtCoMn PtM PtCoNi PtCoHf PtCoZr PtCoMn Single Target Dep.

Cathode Pt Loading = 0.1 mg/cm2 or as notedAll compositions and test stations, 50 cm2

ORR Files/ORR's at 5 sec - graph 3, data 3

ORR at t = 1050 seconds (A/cm2Planar )


Technical Accomplishments: Higher activity alloy catalysts for ORR

0 200 400 600 800 1000 12000.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.15 mgPt/cm2

0.1 mgPt/cm2

T = 1050 secORR Values Taken

T = 5 sec

Standard Pt69Co28Mn3

PtxMy

ORR's at 5 secs - graph 18, data 7

Cur

rent

Den

sity

at 9

00 m

V (m

A/c

m2 pl

anar)

Time (seconds)

0.00 0.08 0.16 0.24 0.32 0.40 0.480

8

16

24

32

40

48

ORR's at 5 secs - graph 6, data 4

DOETargets

0.05 mg/cm2

0.10 mg/cm2

0.15 mg/cm2

0.2 mg/cm2

Abs

olut

e A

ctiv

ity a

t 900

mV

(mA

/cm

2 plan

ar )

Cathode Mass Activity at 900 mV (A/mgPt)

WAO-1, 0.2 mg/cm2 WAO-1, 0.15 mg/cm2 WAO-1, 0.1mg/cm2 WAO-1, 0.05 mg/cm2 New Alloys and controls

11

Technical Accomplishments – NSTF ORR Activity and E1/2from RDEV. Stamenkovic, D. van der Vliet, N. Markovic


Fundamental Studies of NSTF CatalystsRDE characterization of 3M fabricated NSTF alloy catalysts

30-80 mg sample lots of NSTF catalyst coated whiskers14 alloy sample lots evaluated since December 2008Loading studies determined best loading of 65 µg/cm2

disk3 to 8 repeat measurements for each catalyst typeActivity values obtained at 20oC and 60oCCatalysts are intrinsically “acid washed” in RDE measurement, but not for fuel cell tests.

Post-fabrication processingApplied to as-received NSTF catalystsScreening of process conditions for best activityHigh Resolution SEM characterization

Measure highest kinetic and mass activity of any catalyst reported.Highest E1/2 values reported => strong case for setting new standard of measurement at 950 mVIdentified optimum post-fabrication parameters for increased activity

Results

NSTF RDE Polarization Curves(up-voltage sweep shown)

0.6 0.7 0.8 0.9 1.0 1.1-2.0

-1.6

-1.2

-0.8

-0.4

0.0

E1/2 = 0.951

RDE Activity Plots - graph 14, data 4

60oC20 mV/secUpscan65 μgPt/cm2

disk1600 rpm, 20 mV/sec0.1M HClO4NSTF as received

PtM

PtNiFePtCoMn

Pt

I (m

A)

E (V vs RHE)

DiffusionEffects at 0.9

12

Technical Accomplishments – NSTF ORR Activity and E1/2 from RDEV. Stamenkovic, D. van der Vliet, N. Markovic


Results (continued)

TKK 5nm Pt/C *

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM

Treated NSTF PtM0

1

2

3

4

5

6

7

8

9

10

All 65 μgPt/cm2disk

1600 rpm, 20 mV/sec0.1M HClO4

DOE Target = 0.72

RDE Activity Plots - graph 6

Spe

cific

Act

ivity

at 9

00 m

V (m

A/c

m2 P

t)

60oC

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

As-Received Alloy Values

PtPtCoPtNiFePtCoMnPtMPtCoNiPtCoZr

Unit slope line


Fuel

cel

l Mas

s A

ctiv

ity 9

00 m

V a

nd 8

0o C (A

/mg Pt

)

RDE NSTF Alloy Mass Activities at 900 mV and 60oC (A/mgPt )

50 cm2 80oC Mass Activities, 1050 sec 50 cm2 80oC Mass Activities, 5 sec

Mass and specific activities of new NSTF alloy candidates can exceed DOE 2015 targetsANL RDE and 3M 50cm2 fuel cell mass activities at 900 mV quantitatively close: FC 5 sec ORR activity values closer to RDE values.Post fabrication treatment can further increase activities of several alloys tested.Several exceed the DOE 2015 mass activity target

TKK 5nm Pt/C *

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM

Treated NSTF PtM0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

DOE 2015 Target = 0.44 A/mg


Mas

s A

ctiv

ity a

t 900

mV

(A/m

g Pt)

60oC

13

Technical Accomplishments: New NSTF catalystsProf. Jeff Dahn, David Stevens, Arnd Garsuch, and students


Advanced catalysts by compositional spread screening at Dalhousie University

Example of composition control with

PtCoMn

64-electrode arrays of thin film catalysts deposited onto NSTF whiskers, made into MEAs at 3M, tested at Dal. U.129 libraries fabricated and tested through 3/20/09 (vs. 60 last yr.)

• 3 basic configurations (over, under, intermixed w/Pt)• 16 Pt binary, 10 Pt ternary, 10 Pt compound systems

investigated in the intermixed configuration) (vs. 25 last yr.)Compositional, structural and functional performance mapping by: electron microprobe, XPS, XRD, ECSA, ORR, high V cycling durability, acid soak resistance.Extensive proprietary results limit what can be shown

14

Technical Accomplishments: Example: Pt1-xCxProf. Jeff Dahn, David Stevens, Arnd Garsuch, and students


0 250 500-0.8

0

0.8

0 250 500 0 250 500 0 250 500Cell Potential (mV)

0 250 500 0 250 500 0 250 500 0 250 500

-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8

Cur

rent

Den

sity

(mA

/cm

2 )

-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8Pt1-xCx – CV’s Measured in Fuel Cell

0 250 500-0.8

0

0.8


0 250 500 0 250 500 0 250 500 0 250 500

-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8

Cur

rent

Den

sity

(mA

/cm

2 )

-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8C

As assembled After break-inPt Reference

Pt

Pt

0 250 500-0.8

0

0.8


0 250 500 0 250 500 0 250 500 0 250 500

-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8

Cur

rent

Den

sity

(mA

/cm

2 )

-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8Pt1-xCx – CV’s Measured in Fuel Cell

0 250 500-0.8

0

0.8


0 250 500 0 250 500 0 250 500 0 250 500

-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8

Cur

rent

Den

sity

(mA

/cm

2 )

-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8-0.8

0

0.8C

As assembled After break-inPt Reference

Pt

Pt

0 0.2 0.4 0.6

x in Pt1-xCx

3.91

3.92

3.93

3.94

Latt

ice

const

ant

0

2

4

6

8

10

Gra

in s

ize

(nm

)

Pt1-xCx – XRD

0 0.2 0.4 0.6

x in Pt1-xCx

3.91

3.92

3.93

3.94

Latt

ice

const

ant

0

2

4

6

8

10

Gra

in s

ize

(nm

)

Pt1-xCx – XRD

30 40 50Scattering angle (deg.)

Inte

nsi

ty (

counts

) (a

rb.

scal

e)

XRDPt1-xCx

C 30 40 50Scattering angle (deg.)

Inte

nsi

ty (

counts

) (a

rb.

scal

e)

XRDPt1-xCx

C

100 120 140 160 180Radial distance (mm)

0

3

6

9

12

15

SEF

(cm

2E

C/c

m2G

EO)

As assembledAfter thermal cycling

Pt1-xCx – ECSA

Increasing C content

As AssembledAfter Break-in conditioning


0

3

6

9

12

15

SEF

(cm

2E

C/c

m2G

EO)

As assembledAfter thermal cycling

Pt1-xCx – ECSA


As AssembledAfter Break-in conditioning

• fcc(hkl) grain sizes• Pt fcc lattice parameter• Cyclic voltammograms• ECSA before and after break-

in or high voltage cycling• ORR before and after high

voltage cycling.• After acid corrosion • HOR

Examples of 64 Array Mappings vs Compositions:


0

3

6

9

12

15

SEF

(cm

2EC/c

m2G

EO)

Before CV cyclingAfter CV cycling

Pt1-xCx – ECSA’s – 0.6 – 1.2 V cycling



0

3

6

9

12

15

SEF

(cm

2EC/c

m2G

EO)

Before CV cyclingAfter CV cycling

Pt1-xCx – ECSA’s – 0.6 – 1.2 V cycling


15


Technical Accomplishments and Progress: GDL Optimization for NSTF CCM

Electrode backing (EB) carbon paper : Designed Experiment7 commercial roll-good papers

Variables: wet proofing and MPL coating area weight (necessary due to variable EB)3 commercial fully coated GDLs also evaluated

Results: Fuel cell results for all were significantly poorer than 3M baseline GDL

Baseline carbon paper improvement : Designed ExperimentVariables : wet proofing and MPL area weightsSeven fuel cell performance metrics

Results:No single set of GDL parameters were optimum for all seven fuel cell metrics.For steady state cool performance, optimal GDL parameters were different for dry conditions (0 % RH) and wet conditions (100 % RH).Good second order linear regression fits were obtained for three responses (PDS, cathode stoich. sensitivity, and % RH sensitivity at 90/60/60 oC).

Asymmetric anode/cathode GDLs with baseline EB paper : Designed Experiment24-1 factorial with center point replication Variables : wet proofing and MPL coating area weight Still in progress - Largest improvement so far was for extreme difference for anode and cathode GDLs: high wet proofing and MPL weight for anode and low wet proofing and MPL weight for anode.

16

Best GDL Approaches Identified to Date

Technical Accomplishments and Progress: GDL Optimization for NSTF CCM


Greatest higher temperature improvements were for GDL Type B (15 mV for PDS and 30 to 50 mV for GDS).Generally poorer steady state cool performance results than for baseline GDL. Overall best results with minimal impact on steady state cool performance was for GDL D.

PDS, 70 C

GDS, 7.35 psig, 80 C

GDS, 14 psig, 85

C

Cathode Stoich

Sensitivity

% RH Sens.,

V at J = 1.2

V at J = 1.5

V at J = 1.5

V at 1.4 CS, 80 C

Volts at 90/50/50

C/%RH/%RH

30 C, 0/0

30 C, 100/100

40 C, 0/0

40 C, 100/100

Baseline GDL 0.607 0.540 0.600 0.522 0.588 0.342 0.209 0.540 0.250

GDL A 0.603 0.584 0.625 0.521 0.612 0.305 0.172 0.490 0.203

GDL B 0.623 0.591 0.628 0.531 0.536 0.295 0.120 0.514 0.169

GDL C 0.602 0.578 0.629 0.498 0.596 0.277 0.130 0.467 0.154

GDL D 0.595 0.567 0.614 0.510 0.612 0.334 0.200 0.549 0.235

GDL Steady State Cool Start amps/cm2 at 0.6 V

17

CollaborationsSubcontractors

Dalhousie University : Subcontractor, extensive collaborationANL (Markovic group): Subcontractor, extensive collaborationNASA-JPL: Subcontractor, extensive collaboration

System Integrators and stack manufacturers (partial list)GM Fuel Cell Activities -Honeoye Falls: Extensive collaboration outside of DOE H2program with materials generated at 3M under this contract. Multi-year single cell performance and activity validations, stack testing, cold/freeze start and water management evaluations, PEM and GDL integration, durability testing, fundamental modeling studies.Proton Energy Systems – Performance testing of NSTF MEAs in electrolyzers. Moderate interaction, started in past year and ongoing.Giner EC Systems, LLC – Performance testing of NSTF MEAs in electrolyzers. Moderate interaction, started in past year and ongoing.

National LaboratoriesLANL (Borup group) – Neutron imaging of NSTF MEA’s at NIST. Occasional.ORNL (K. More) - TEM imaging of NSTF catalysts. Occasional.ANL (Ahluwalia group) - Systems modeling with 3M supplied NSTF MEA property and functional performance data as requested. Ongoing for several years.

3M Advanced Cathode Catalysts ……………………... 2009 DOE Hydrogen Program Review, May 18-22

18

Future Work

Cathode Catalyst Mass Activity GainContinue to fabricate and test new catalyst compositions and structures to exceed target mass activity of 0.44 A/mgPt and which meet all other performance requirements.Achieve 50% gain in surface area of NSTF supports over current NSTF baseline without loss of specific activity or durability under most severe accelerated test.

Water Management ImprovementOptimize the GDL materials and physical construction for more effective liquid water transport at low temperatures without compromising high temperature performance under dry conditions. Tailor the GDL for both anode and cathode independently to optimize performance over a wider range of operating conditions.

Start-up conditioning (New Task 6)Continue to explore break-in conditioning protocols and catalyst/membrane components to reduce MEA break-in conditioning time to < 3 hours.

Durability ImprovementReduce by 50% any losses in surface area, activity or mass transport over-potential under the more severe fast high voltage cycling protocol (4000 cycles, 0.6 – 1.2 V under H2/N2 at 20mV/sec at 95/95/95 oC).

Stack testingInitiate Task 3, to begin MEA component down-selection for large area, single cell

performance and durability testing.


19

Characteristic Units Targets2010 / 2015

3M Status – 3/09(mfg’d roll-good )

PGM Total Content gPt/kWe rated in stack

0.3 / 0.2 < 0.18gPt/kW for cell V < 0.67 Vin 50 cm2 cell at 150kPa inlet

PGM Total Loading mg PGM/cm2 of total MEA area

0.3 / 0.2 0.15 with current PtCoMn alloy(A/C = 0.05/0.10)

Durability under Load Cycling Hours, T < 80oCHours, T > 80oC

5000 / 50002000 / 5000

> 7000 hours in 50cm2 cellat 80/64/64oC

Mass Activity (150kPa H2/O2 80oC. 100% RH)

A/mg-Pt @ 900 mV, 150kPa O2

0.44 / 0.44 0.16 A/mg in 50 cm2 w/ PtCoMn 0.33A/mg in 50 cm2 with new PtxMy

Specific Activity (150 kPa H2/O2 at 80oC, 100% RH)

μ A/cm2-Pt @ 900 mV

720 / 720 2,100 for PtCoMn, 0.1mgPt/cm2

2,500 for new PtxMy , 0.1mgPt/cm2

Accel. Loss: 30,000 cycles, 0.7 –0.9V step, 30 s hold at 80/80/80oC

- mV at 0.8 A/cm2

% ECSA loss < 30mV

< 40% / 40 %~ 0 mV loss at 0.8 A/cm2

~ 0% loss ECSA

Accel. Loss: 200 hr hold @ 1.2 V at 95oC, H2/N2, 150kPa, 80% RH

- mV at 1.5 A/cm2

% ECSA loss< 30mV

< 40% / 40%+ 25mV gain at 1.5 A/cm2

~ - 17% loss ECSA

OCV hold without PEM failure under250/200 kPa H2/air, 90oC, 30%RH

Hours

mA/cm2

200< 20

900 – 1300 H2 Crossover < 20 mA/cm2,

F- ion release rate < 0.5 µg/cm2-day

Accel. Loss: 4,000 cycles 0.6 -1.2V, 20mV/sec, 95/95/95oC, 270kPa,H2/N2

ORR Specific Activ % ECSA loss

?? + 5% gain in mA/cm2Pt

- 30 % loss of cm2Pt / cm2

planar

Project Summary : Status Against DOE Targets – March, 2009


20

Project Summary: Overview for 2009Relevance: Critically focused on overcoming the three most critical barriers for fuel cell MEA development (A, B, C on Overview slide)

Approach: Builds on 12 year DOE/3M funded development of NSTF catalyst and MEA technology that fundamentally has higher specific activity, removes all durability issues with carbon supports, much reduced losses due to Pt dissolution and membrane chemical attack, with high volume manufacturing advantages.

Technical Accomplishments and Progress: In 50 cm2 cell tests, have exceeded the DOE 2015 targets for specific power density (gPt/kW), total PGM loadings, and multiple accelerated durability tests (including OCV hold and load cycling). Have demonstrated new alloys that approach the 0.44 A/mgPt mass activity target in 50 cm2 cells and exceed 0.8 A/mgPt in RDE measurements.

Technology Transfer/Collaborations: Extensive interactions with key partners has been productive in developing methods to increase catalyst activities and surface areas. Extensive interactions with a major systems integrator has been critical to validate performances and identify real world gaps and issues, while initial work with electrolyzer integrators offer technology assessment for H2 generation.

Proposed Future Research: Strongly focused on advancing NSTF MEA materials for improved water management with robust operating windows, and implementing increased mass activity and higher durability in practical catalysts.


21

Additional Slides

25

Multi-electrode NSTF Array

Pt-Content in Array (At.%)

50% 35%

E-11

Pt49.9Co37.4Zr

12.7

E-12

Pt47.3Co35Zr1

7.7

E-13

Pt40Co35Zr25

E-14

Pt33.8Co32.7Zr

33.5

E-15

Pt32.5Co28.6Zr

38.9

E-16

Pt35.8Co30Zr34.2

E-21

Pt52.1Co36.5Zr

11.4

E-22

Pt45.1Co36.9Zr

18

E-23

Pt39Co35.3Zr2

5.7

E-24

Pt33.4Co32.6Zr

34

E-25

Pt32Co30.1Zr3

7.9

E-26

Pt37.5Co29.2Zr33.3

E-31

Pt50.5Co33.2Zr

16.3

E-32

Pt44.7Co35Zr2

0.3

E-33

Pt39.2Co36.6Zr

24.2

E-34

Pt33.4Co32.8Zr

33.8

E-35

Pt35.1Co28.5Zr

36.4

E-36

no whiskers

-5.00E-03

-4.00E-03

-3.00E-03

-2.00E-03

-1.00E-03

0.00E+00

1.00E-03

2.00E-03

3.00E-03

4.00E-03

5.00E-03

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Electrode Potential, V vs. NHE

Cur

rent

Den

sity

, A/c

m2

200 mV/s

100 mV/s

80 mV/s

50 mV/s

Pt-Zr NSTF

Pine Rotator

8” OD Crystallization Dish

JPL: Preparation and Characterization of NSTF-Coated Electrode Arraysusing novel rotating electrolyte approach

Composition Range on Electrode ArrayCo-sputtering of Alloy NSTF

Electrochemical Cell Electrochemical Surface Area

Glass SubstrateTi adhesion layer

Au current collector

Sputter targetSputter target

Zr Pt3CoGlass SubstrateTi adhesion layer

Au current collector

Sputter targetSputter target

Zr Pt3CoZr Pt3Co

C. C. Hays and S. R. Narayanan


26

10-6

-9

-8

-7

-6

-5

-4

-3

-2

-1

1

2 Current (Amps)

1.051.000.950.90

Volts (NHE)

E-11: I = -3.6e-6 Amps at 0.892V

E-16: I = -1.8e-6 Amps at 0.892VPt Thin Film: I = -0.81e-6 Amps at 0.892V

E-11,11-16-08 E16, 11-16-08

Polarization Curves for ORR with rotating electrolyte apparatus

-600x10-6

-500

-400

-300

-200

-100

0

100

OR

R C

urre

nt D

ensi

ty (0

.9V

, NH

E),

A/c

m2 )

50403020100ORR Scan Rate (mV/sec)

Potentiostatic (slow stir) Maximum Stir Rate (200-300 rpm?) Reduced Stir Rate (~0.25*Max Rate)

Scan Rate Measurements for ORR on PtCoZr NSTF

C. C. Hays and S. R. Narayanan


Limiting currents (not presented) are about three times less than RDE measured at Dalhousie on the same NSTF configuration at 400 rpm.

The current at 0.9 V at 50 mV/s is 3 – 4 times that measured at 1 mV/s.

JPL: Preparation and Characterization of NSTF-Coated Electrode Arraysusing novel rotating electrolyte approach

27

Technical Accomplishments – RDE ORR (0.9 v) Activity and E1/2 at 20oC from vs NSTF alloy type

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM

Treated NSTF PtM0.90

0.92

0.94

0.96

0.98




H

alf-W

ave

Pot

entia

l, E 1/

2 (V

)

20oC

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM


0.92

0.94

0.96

0.98

Hal

f-Wav

e P

oten

tial,

E 1/2 (

V)




60oc

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM

Treated NSTF PtM0

1

2

3

4

5

6

7

8

9



DOE Target = 0.72


Spe

cific

Act

ivity

at 9

00 m

V (m

A/c

m2 P

t)

20oC

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM

Treated NSTF PtM0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

DOE 2015 Target = 0.44 A/mg


Mas

s A

ctiv

ity a

t 900

mV

(A/m

g Pt) 20oC


28

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM


0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20


M

ass

Act

ivity

at 9

50 m

V (A

/mg P

t)

20oC

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM


0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18


Mas

s A

ctiv

ity a

t 950

mV

(A/m

g Pt)

60oC

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM

Treated NSTF PtM0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4




Spe

cific

Act

ivity

at 9

50 m

V (m

A/c

m2 Pt

)

60oC

NSTF Pt

Treated NSTF Pt

NSTF PtCoMn

Treated NSTF PtCoMn

NSTF PtNiFe

Treated NSTF PtNiFe

NSTF PtM

Treated NSTF PtM0.0

0.5

1.0

1.5

2.0




Spe

cific

Act

ivity

at 9

50 m

V (m

A/c

m2 Pt

)

20oC

Technical Accomplishments – RDE ORR Activity at 950 mV and 20 and 60 oC vs NSTF Alloy

Type


29

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Anode/Cathode: NSTF PtCoMn 0.05/0.10 mgPt/cm2 PEM: 3M 850 EW, 20 micron; GDL: 3M New

FC14654 760.DAT FC14654 760.DAT - HFR FC12969-939R, J FC12969-939R - HFR FC014693 575.RAW HFR

Anode/Cathode: NSTF PtCoMn 0.1/0.15 mgPt/cm2

PEM: 3M 850 EW, 35 micron; GDL: 3M 2975


NSTF Base Line10/10/07A/C=0.10/0.15

Best of Class 01/22/09FC14654, FC14693A/C=0.05/0.10


Cel

l Vol

tage

(V) a

nd H

FR (o

hm-c

m2 )

J (A/cm2)

200 kPa50mV gain at 2 A/cm2

28% reduction in impedance

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

FC12969-937R, V FC12969-937R, HFR FC14654-757, V FC14654-757, HFR FC014693-572, V FC014693-596, HFR

Best of Class 1/22/09FC14654, FC14693




Galvanodynamic ScansTcell/DP's = 80/68/68 °C H2/air stoich = 2.0/2.5H2/air Inlet pressure = 150 kPaGDS(0.02, 2, 10 step/dec, 180s/pt) 50 cm2 Quad serpentine cell

HFR

Cel

l Vol

tage

(V) a

nd H

FR (o

hm-c

m2 )

J (A/cm2)

150 kPa85mV gain at 2 A/cm2

34% reduction in impedance

GDS Polarization Curves

40% reduction in Pt loading20 vs 35 µm thick 3M PEMImproved 3M GDL

Improvement from:

Technical Accomplishments: higher power density, reduced loading


30

Baseline Best of Class MEA - Oct., 2007A/C Loading =0.1/0.15 mgPt/cm2

35 micron 3M PEMStd. 3M GDL

Baseline Best of Class MEA - Jan., 2009A/C Loading = 0.05/0.10 mgPt/cm2

20 micron 3M PEMNew 3M GDL

40% reduction in Pt loading40% reduction in mass transport over-potential at 2 A/cm2, 150kPa

0.1 10.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

MTO = 72 mV @ 2A/cm2

72 mV

0.02 2

HFR

70 mV/decadeTafel Slope

FC12969-graph18

Tcell/DP's = 80/68/68°C H2/air stoich = 2.0/2.5H2/air pressure = 7.5/7.5 psigGDS(0.02, 2, 10 step/dec, 180s/pt, 0.5V limit)50 cm2 Quad serpentine cell

E(V

), H

FR (o

hm-c

m2 ) a

nd E

IR-F

ree(V

)

Current Density (A/cm²)

FC12969-937R FC12969-937R, HFR, (ohm-cm²) FC12969-937R, IR-Free Cell Voltage, (volts)

Previous Best of Class New Best of Class



31

48% reduction in specific power density at peak power40% reduction in Pt loadingExceeds DOE-2015 targets for Specific Power Density and total PGM loading

Inverse Specific Power Density200 kPa Inlet Pressure


0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3



FC14654-760, Power Density, 200kPa FC14654-760, Voltage, 200kPa FC14693-575, Power Density, 200kPa FC14693-575, Voltage, 200kPa


Cel

l Vol

tage

(V) a

nd P

ower

(W/c

m2 )

J (A/cm2)

Cell Voltage and Power200 kPa Inlet Pressures


0.55 0.60 0.65 0.70 0.75 0.800.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

DOE 2015 Target

Galvanodynamic ScansTcell/DP's = 80/68/68 °C H2/air stoich = 2.0/2.5H2/air Inlet pressure = 200 kPaGDS(0.02, 2, 10 step/dec, 180s/pt)Both MEA electrodes conditioned50 cm2 Quad serpentine cell


FC14654-760FC14693-575

01/22/09

Previous Best of ClassFC12969-939R

10/05/07

Cell Voltage (V)

(Spe

cific

Pow

er D

ensi

ty)-1

(gPt

tota

l / k

W)



32

Example Studyto Illustrate the Methodology

- Pt1-xZrx -

Tasks 1.1.2, 1.3, 2: Dalhousie/3M


33

0.00

0.06

0.12

0.18

0.24

0.30

0.36

• Constant Pt, ~75 nm planar equivalent (~0.15 mg/cm2)• Linear gradient out to ~ 40 atomic% Zr intimately mixed with the Pt

Incr

easi

ng Z

r

Constant Pt

Dashed rectangle shows region measured with microprobe. Circles show positions of FC channels 100 120 140 160

Radial distance from center of table (mm)

0.10

0.15

0.20

0.25

0.30

Load

ing

(mg/

cm2 )

100 120 140 160Radial distance from center of table (mm)

0.00

0.10

0.20

0.30

0.40

x in

Pt 1-

xZr x

x = 3.54 x 10-3 D - 0.261

Example of Pt1-xZrx Binary Study: Sputtering Details


34

14 days, 80°C, 0.5 M H2SO4

0 0.1 0.2 0.3 0.4Predicted x in Pt1-xZrx

0

0.1

0.2

0.3

0.4

Mea

sure

d x

in P

t 1-xZ

r x

Pre-corrosion testingPost-corrosion testing

Example of Pt1-xZrx Binary Study: Corrosion Testing, XRD Data


30 40 50 60 70 80 902θ Scattering Angle (°)

Inte

nsity

(cou

nts)

0.05

0.10

0.15

0.20

0.25

0.30

0.35

xin

Pt1-x Zrx

Extract grain size and lattice parameters as a function of composition

35

Incr

easi

ng Z

r A B C D E F G H8

7

6

5

4

3

2

1

Before break-in conditioning

After break-in conditioning

0 250 500

-0.4

0.4


0 250 500 0 250 500 0 250 500 0 250 500

-0.4

0.4-0.4

0.4-0.4

0.4

Cur

rent

Den

sity

(mA

/cm

2 )

-0.4

0.4-0.4

0.4-0.4

0.4-0.4

0.4

0 250 500

-0.4

0.4


0 250 500 0 250 500 0 250 500 0 250 500

-0.4

0.4-0.4

0.4-0.4

0.4

Cur

rent

Den

sity

(mA

/cm

2 )

-0.4

0.4-0.4

0.4-0.4

0.4-0.4

0.4

Example of Pt1-xZrx Binary Study: Cyclic Voltammetry


36

Incr

easi

ng Z

r

A B C D E F G H8

7

6

5

4

3

2

1

After 10s at potential

After 1 min at potential

0 5001000500

750

0 5001000 0 5001000 0 5001000Current Density (mA/cm2)

0 5001000 0 5001000 0 5001000 0 5001000

500

750

500

750

500

750

Cha

nnel

Pot

entia

l (m

V)

500

750

500

750

500

750

500

750

1000

0 5001000500

750

0 5001000 0 5001000 0 5001000Current Density (mA/cm2)

0 5001000 0 5001000 0 5001000 0 5001000

500

750

500

750

500

750

Cha

nnel

Pot

entia

l (m

V)

500

750

500

750

500

750

500

750

1000

Example of Pt1-xZrx Binary Study: ORR performance under O2


37

0 0.1 0.2 0.3x in Pt1-xZrx

0

50

100

150

200

250

300

iR-c

orre

cted

Cur

rent

Den

sity

at 8

00m

V (m

A/c

m2 )

0 0.1 0.2 0.3 0.4x in Pt1-xZrx

After holding for 10s After holding for 1 min

Example of Pt1-xZrx Binary Study: ORR performance under O2


38

0 0.1 0.2 0.3 0.4x in Pt1-xZrx

0

50

100

150

200

250

300iR

-cor

rect

ed c

urre

nt d

ensi

ty a

t 800

mV

(mA

/cm

2 )

Before Durability TestingAfter Durability Testing

Example of Pt1-xZrx Binary Study: ORR specific activity


39

0 0.1 0.2 0.3x in Pt1-xZrx

5

10

15

20

25

30Sp

ecifi

c C

urre

nt D

ensi

ty a

t 800

mV

(mA

/cm

2 EC)

0 0.1 0.2 0.3 0.4x in Pt1-xZrx

After holding for 10s After holding for 1 min

Example of Pt1-xZrx Binary Study: ORR specific activity


40

0 125 2500

4080

0 125 250 0 125 250 0 125 250Current Density (mA/cm2)

0 125 250 0 125 250 0 125 250 0 125 250

040800

40800

4080

Cha

nnel

Pot

entia

l (m

V)

040800

40800

40800

4080

Incr

easi

ng Z

r

A B C D E F G H8

7

6

5

4

3

2

1

Example of Pt1-xZrx Binary Study:H2 oxidation performance


41

0 400 800-1012

0 400 8000 400 8000 400 800

Cell Potential (mV)

0 400 8000 400 8000 400 8000 400 800

-1012-1012-1012-1012

Cur

rent

Den

sity

(mA

/cm

2 )

-1012-1012-1012

A B C D E F G H8

7

6

5

4

3

2

1

Incr

easi

ng Z

r

75°C, 100% RH

Example of Pt1-xZrx Binary Study: Crossover determination


42

0 20 40 60Channel Number

0

0.4

0.8

1.2

1.6C

ross

over

Cur

rent

Den

sity

(mA

/cm

2 )

Example of Pt1-xZrx Binary Study: Crossover determination


43

0 250 500

-0.4

0.4


0 250 500 0 250 500 0 250 500 0 250 500

-0.4

0.4-0.4

0.4-0.4

0.4

Cur

rent

Den

sity

(mA

/cm

2 )

-0.4

0.4-0.4

0.4-0.4

0.4-0.4

0.4A B C D E F G H

8

7

6

5

4

3

2

10 250 500

-0.4

0.4


0 250 500 0 250 500 0 250 500 0 250 500

-0.4

0.4-0.4

0.4-0.4

0.4

Cur

rent

Den

sity

(mA

/cm

2 )

-0.4

0.4-0.4

0.4-0.4

0.4-0.4

0.4

Incr

easi

ng Z

r

Before CV Cycling After CV Cycling (3000 cycles)

High Voltage CV Cycling 600 – 1200 mV cycling

Example of Pt1-xZrx Binary Study: Durability testing


advanced cathode catalysts and supports for pem fuel cells · electrode (catalyst and support),...

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