High Performance, Durable, Low Cost Membrane Electrode ...€¦ · High Performance, Durable, Low...

3M High Performance, Durable, Low Cost MEAs. 2014 DOE Hydrogen, Fuel Cells, Vehicles Program AMR, June 16-20

High Performance, Durable, Low Cost Membrane Electrode Assemblies for

Transportation Applications

Andrew Steinbach 3M Company

June 18th, 2014

Project ID: FC104

This presentation does not contain any proprietary, confidential, or otherwise restricted information

2014 Annual Merit Review DOE Hydrogen and Fuel Cells and

Vehicle Technologies Programs


Project Overview Timeline

• Project start: 9/1/12 • Project end: 8/30/14

Barriers A. MEA Durability B. Stack Material & Mfg Cost C. MEA Performance

DOE Technical Targets Electrocatalyst (2017)

• Mass Activity: 0.44A/mg • Inv. Spec. Power: 0.125g/kW(rated) • PGM Total Loading: 0.125mg/cm2 • Electrocatalyst, Support Durability:

< 40% Activity, ECSA Loss MEA (2017)

• Q/∆T: 1.45 kW/ºC • Cost: $9 / kW • Durability w/cycling: 5000 hrs • Performance @ 0.8V: 0.300 A/cm2 • Perf. @ Rated Power: 1 W/cm2

Budget • Total DOE Project Value: $4.606MM* • Total Funding Spent: $2.556MM*

• Cost Share Percentage: 20% * Includes DOE, contractor cost-share, and FFRDC funds, as of 3/31/14.

Partners • Johns Hopkins Univ. (J. Erlebacher) • Oak Ridge Nat’l Lab. (D. Cullen) • Lawrence Berkeley Nat’l Lab.(A. Weber) • Michigan Technological Univ. (J. Allen) • Freudenberg FCCT (C. Quick) • Argonne Nat’l Lab. (R. Ahluwalia) • Los Alamos Nat’l Lab. (R. Mukundan, R. Borup) • General Motors (B. Lakshmanan)

2


Objective and Relevance Overall Project Objective: Development of a durable, low-cost, robust, and high performance membrane electrode assembly (MEA) for transportation applications, able to meet or exceed the 2017 DOE MEA targets.

3

Primary Objectives and Approaches This Year

Barriers Addressed

1. Improve MEA Robustness for Cold Startup and Load Transient via Materials Optimization, Characterization and Modeling.

B. Cost C. Performance

2. Evaluate Candidate MEA and Component Durability to Identify Gaps; Improve Durability Through Material Optimization and Diagnostic Studies.

A. Durability

3. Improve Activity, Durability, and Rated Power of MEAs based on Pt3Ni7/NSTF Cathodes via Post-Processing Optimization and Characterization.

A. Durability B. Cost C. Performance

4. Integrate MEAs with High Activity, Rated Power, and Durability with Reduced Cost.

A. Durability B. Cost C. Performance

MEA, Catalyst Targets Addressed 2017 Targets Target Values Obj.

Q/∆T 1.45kW / °C 3,4

Cost $9 / kW 3,4

Durability with cycling

5000 hours w/ < 10% V loss 2,3,4

Performance @ 0.8V 0.300A/cm2 3,4

Performance @ rated power

1W/cm2 3,4

PGM Content (both electrodes)

0.125g/kWRATED 0.125mgPGM/cm2 3,4


Approach, Milestones, and Status v. Targets Approach: Optimize integration of advanced anode and cathode catalysts, based on 3M’s nanostructured thin film (NSTF) catalyst technology platform, with next generation PFSA PEMs, gas diffusion media, cathode interfacial layers, and flow fields for best overall MEA performance, durability, robustness, and cost. 1. Place appropriate emphasis on key commercialization and DOE barriers. 2. Through advanced diagnostics, identify mechanisms of unanticipated component interactions

resulting from integration of low surface area, low PGM, high specific activity electrodes into MEAs.

4

MS ID

Q T R

Project Milestone MS 1.1, 2.1, 5.1 based on 4-5 Project Goals

(See Backup Slides)

% Complete (Apr. ’14)

BUDGET PERIOD 1 (Sept. ‘12-May ‘14) 6.1 2 Baseline MEA: Short Stack Eval. Complete. CANCELLED 1.1 7 Comp. Cand. Meet Interim Perf./Cost Goals. 75% (3 of 4) 2.1 7 Comp. Cand. Meet Interim Cold-Start Goals. 75% (3 of 4) 5.1 7 Comp. Cand. Meet Interim Durability Goals. 66% (8 of 12)

3.1 7 GDL Pore Network Model Validation With ≥ 2 3M Anode GDLs. 50% (1 of 2)

6.2 7 Interim BOC MEA: Short Stack Eval. Complete. 10% (1 of 3)

4.1 Go/

No-Go 7

2014(Mar.) Best of Class MEA Meets G/NG 1) ≤ 0.135mgPGM/cm2 (Total) 2) Rated Power, Q/∆T: ≥0.659V@ 1.41A/cm2, 90ºC, 1.5atm H2/Air

100% 0.129mg/cm2

0.668V

Status Against DOE 2017 Targets

Characteristic 2017 Targets

Status, ’13/’14

Q/∆T (kW / °C) 1.45

1.56/1.56 (0.670V)

Cost ($ / kW) 9 6 / 5

(PGM only @ $35/gPt)

Durability with cycling (hours) 5000 NA

Performance @ 0.8V (mA/cm2) 300 203/125

Performance @ rated power (mW/cm2)

1000

871/932 (0.670V)

PGM total content (g/kW (rated))

0.125

0.157/0.138 (0.670V)

PGM total loading (mg PGM / cm2 electrode area)

0.125 0.137/0.129


Accomplishments and Progress

Improved Robustness for Cold Startup, Load Transient (Task 2): New Anode GDLs Improve Startup Capability - Higher H2O Removal Out Anode

5

• New anode GDL candidates show good promise for improving cold-start capability.

• Improvements in low T performance as the anode GDL is varied correlate with higher anode water removal rates @ 0.25A/cm2.

• As T decreases, performance loss occurs as anode water removal rate limit occurs.

30 35 40 45 50 550.0

0.3

0.6

0.9

1.2

1.5

D

C

B

A

J @

0.4

0V

(A

/cm

2)

Cell T (oC)

30/30/30C,

0/7.35psig H2/Air

800/1800SCCM,

PSS(0.40V, 10miN)

Temperature Sens. v. Anode GDL

Baseline

0.0 0.2 0.4 0.6 0.8 1.00.3

0.4

0.5

0.6

0.7

0.8Water Balance v. Anode GDL

D

C

BA

Ba

se

line

0.25A/cm2,CS2/2, 0/0psig,0% inlet RH

Ce

ll V

@ 0

.25

A/c

m2 (

Vo

lts)

Anode Total Removal Rate

(L/cm2/min)

35oC

0.0 0.2 0.4 0.6 0.8 1.00.3

0.4

0.5

0.6

0.7

0.8Water Balance v. Anode GDL

D

C

BA

Ba

se

line

0.25A/cm2,CS2/2, 0/0psig,0% inlet RH

Ce

ll V

@ 0

.25

A/c

m2 (

Vo

lts)

Anode Total Removal Rate

(L/cm2/min)

35oC


Accomplishments and Progress Cold Startup Modeling (Task 3): MTU Pore Network Model results validated against experimental liquid water transport in 3M GDL (Milestone)

6

Injection Pressure

Wetted Area

Pore Size Distribution

Contact Angle Model vs Experiment GDL “B” (prev. slide)

Energy/Time Scaling

MTU Model Inputs: • PSD, thickness, and contact angle • Operating conditions MTU Model Results: • Transient water distribution • Transient effective permeability,

conductivity, and diffusivity E. F. Médici and J. S. Allen, Phy. Fluids 23 (2011): 122107. E. F. Médici and J. S. Allen, Int. J. Heat Mass Trans., 65 (2013): 779-788.



Cold Startup Modeling (Task 3): Possible Backing Structural Factor Identified

Which Correlates with Improved Low T Response; MTU Modeling Provides Insight

7

30 35 40 45 50 550.0

0.3

0.6

0.9

1.2

1.5

C

A

J @

0.4

0V

(A

/cm

2)

Cell T (oC)

30/30/30C,

0/7.35psig H2/Air

800/1800SCCM,

PSS(0.40V, 10miN)

Temperature Sens. v. Anode GDL

Baseline

• Some backings show apparent physical “banding” (dense/sparse regions) on ca. 1mm scale.

• Qualitative extent of banding correlates with improved low temperature performance.

• MTU model shows that banding can help retain higher gas permeability during simulated cold start and influences local catalyst temperature distribution.

Baseline

A

C

Incr

easi

ng

Den

sity

Mo

du

lati

on

Backlit Optical Microscopy

1 mm

0 50 100 150 20010

-15

10-14

10-13

10-12

10-11

C (Approximated)

A

Effective P

erm

eabili

ty B

(m

2)

Time (Sec)

Baseline

Influence of Dense/Sparse Backing

Alignment w/ FF Land/Channels

30oC, 60% RH, 1.5A/cm

2

50% heat,

80% water to cathode

Effective Permeability During

Simulated Cold Startup



Improved Robustness for Cold Startup, Load Transient (Task 2): Cathode Interlayer Developed: 20C Improvement in Operating Window, and Is Durable

8

• Low loaded Pt/C interlayer (between NSTF cathode and cathode GDL) improves minimum “passing” load transient temperature: 50C (no IL) to 30C (w/ IL).

• Durability - Degradation of IL surface area w/ CV cycling results in improved MEA performance at rated power, and load transient is similar or improved.

30 40 50 60-0.2

0.0

0.2

0.4

0.6

0.8

1.0

30 or 40CoC, w/o IL

30oC, w/ IL

40oC, w/ IL

J

(A/c

m2)

or

V (

Volts)

Time (sec)

50oC, w/ or w/o IL

Benefit of IL, ~ 0.025mgPGM/cm2

xoC Cell, 50/50kPag H

2/Air, 0/0% RH, CS2/2 @ 1A/cm

2

Step J

Increase0

5

10

15

20Total Cathode Area (NSTF + IL)

Spec.

Are

a

(m2/g

)

PtCoMn/NSTF (no IL)

0.15mgPGM

/cm2

0.50

0.55

0.60

0.65High J H

2/Air Performance

V @

1.4

6m

A/c

m2

H2/A

ir,

(Volts)

80/68/680C

50/50kPag

CS2/2.5, 1.46A/cm2

0 1k 2k 3k0.0

0.1

0.2

0.3

0.4

33/0/00C, 50/50kPag H

2/Air,

696/1657SCCM, GSS(1A/cm2)

Ld T

rans V

(Volts)

# of V Cycles (0.6-1.2V, 100mV/s)

Ld Trans: 60s Ld Trans

32s


Accomplishments and Progress Component Durability Evaluation (Task 5): Component Candidates Generally Show Acceptable Durability; Cathode Cyclic Durability Insufficient

9

Metric Change/Tgt Mass Activity (A/mg) -66±4% / -40%

V @ 0.8A/cm2 -13±15mV/-30mV Surf. Area (m2/g) -28±4% / -40%

Electrocatalyst Cycle Support Cycle MEA Chemical

• Pt3Ni7 cyclic durability insufficient to achieve mass activity target; passes others. • Mostly Spec. Act. loss. • TEM, EDS (ORNL):

Modest coarsening and severe Ni loss.

Metric Change/Tgt Mass Activity (A/mg) -40±7 % / -40%

V @ 0.8A/cm2 -11±3 mV / -30mV Surf. Area (m2/g) -19±3% / -40%

• Pt3Ni7 cathode passes support cycle (previous 400hr 1.2V hold test).

Metric EOT / Target H2 Xover (mA/cm2) 3.7±0.3 / 2

OCV Loss (%) -6 ± 2 / -20 Short Res. (ohm-cm2) 1300±90 / 1000

• 2013 (March) BOC MEA passes (little change after 500 hours).

• 8 Candidates Evaluated (An., PEM, Cath.); All Pass if PEM Additive Present at Low Level.

0.0 0.5 1.0 1.50.50.60.70.80.91.0

Initial 400 Hours

Cell V

olta

ge (V

olts

)

J (A/cm2)

80/68/68C, 7.35/7.35psig H2/Air, CS(2,100)/CS(2.5, 167)GDS(0.02->2->0.02, 10steps/decade, 120s/pt, 0.4V limit, 0.1maxJstep)Upscan (high->low J) only.

0 200 400 6000.8

0.9

1.0

Time (hrs)

OCV

(Vol

ts)

90C, 30/30% RH1.5/1.5atm H2/Air

0.0 0.5 1.0 1.50.50.60.70.80.91.0 Initial

30k Cycles

Cell V

olta

ge (V

olts

)

J (A/cm2)



Accomplishments and Progress MEA Rated Power Durability (Task 5): 3 Primary Factors To Date

10

Cell Temp (°C)

V @ 1A/cm2 Accel. Factor

80°C 0.6 90°C 1

100°C 4

Load Cycle Temp. PEM EW PEM Additive

PFSA EW (g/mol)


1000 0.5 825 1 734 1.9

Add. Level (Arb.)


1 1 0 10

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.5 1.0 1.50.5

0.6

0.7

0.8

0.9

1.0

No Additive

80/68/68C, 7.35/7.35psig H2/Air,

CS(2,100)/CS(2.5, 167)GDS(120s/pt)

BOT EOT

Cell

Volta

ge (V

olts

)

BOT EOTAdditive Level 1

Cell

Volta

ge (V

olts

)

J (A/cm2)

80/68/68C, 7.35/7.35psig H2/Air,

CS(2,100)/CS(2.5, 167)GDS(120s/pt)

0

5

10

15

0

10

20

30

0.50

0.55

0.60

0.65

0.70

SEF

(cm

Pt2 /c

m2 )

80oC 90oC 100oC

ORR

Abs

. Act

ivity

(mA/

cm2 )

Time

V @

1A/

cm2

(Vol

ts)

Method: Mod. Tech Team Load Cycle. Baseline: 0.05/0.15PtCoMn/NSTF, 825EW 20µ PEM, 90°C

0

5

10

15

0.500.550.600.650.70

0

10

20

30

1000EW 825EW 734EW

SEF

(cm

Pt2 /c

m2 )

Time

V @

1A/

cm2

(Vol

ts)

ORR

Abs

. Act

ivity

(mA/

cm2 )

Pt/NSTF on A+C

Pt/NSTF on A+C



MEA Rated Power Durability (Task 5): Voltammetry Suggests Accumulation

of Anionic Contaminant; Rated Power Loss Due to ORR Kinetic Loss

11

• PEM EW, additive, and temp. factors, ORR Act. loss, and HUPD shift consistent: PEM decomp. cathode deact. rated power loss, due to “irreversibly” adsorbed PEM decomp. product(s).

• Species? CF3(CF2)nCOOH (small n), SO42- known reversible

contaminants for NSTF, Pt/C cathodes; why “irreversible” here?

• Can 20-30mV kinetic loss be related with 200mV loss at 1A/cm2? • Loss at 1A/cm2 (air) becomes exceptionally large as cathode ORR

activity (O2) decreases below ~10mA/cm2planar.

-0.002

-0.001

0.000

0.001

0.002

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8-0.002

-0.001

0.000

0.001

0.002

1000EW

825EW

734EW

70/70/70C, 0/0psig H2/N

2, 800/1800SCCM

CV(0.65V->0.085V->0.65V, 100mV/s)

Beginning of Test

1000EW

825EW

734EW

End of Test

Cathode E v. RHE (Volts)

70/70/70C, 0/0psig H2/N

2, 800/1800SCCM

CV(0.65V->0.085V->0.65V, 100mV/s)

J (

mA

/cm

2

pla

na

r)

0 5 10 15 20 25 300.2

0.3

0.4

0.5

0.6

0.7

0.8

BOL Only

Contam. Series

Ca. Ldg. Series

Model Fit

BOL and Degraded

EW Series

Temp Series

Additive Series

IR-F

ree

V @

1A

/cm

2

ORR Absolute Activity (mA/cm

2

planar)

V=V0+TS*log(AA

0/AA)

V0=0.76V (Fixed),

AA0= 26 +- 0.5 mA/cm

2

planar

TS=-0.122 +- 0.002 V/dec

R2=0.93

"Rated Power" Loss Due to ORR Kinetic Loss

214 Data Points, 53 MEAs

Correlation with both degraded and BOL MEAs with various BOL ORR activities.

53 MEAs

Mitigation Path: 1) Opt. Materials to Min. Contam. Generation 2) Recovery Method Development

HUPD E shift at EOT trends with performance loss.


Accomplishments and Progress Improved Activity, Rated-Power Capable ORR Catalysts (Task 1.1): SET (Annealing) Improves Activity, Area of Pt3Ni7/NSTF Cathodes

• Annealing optimization: • +30% mass activity, in MEA. • +20% specific area.

• DOE Mass Activity target exceeded.

• Increasing grain size, decreasing lattice constant (XRD) correlates with specific area gains. • Alloy homogenization,

defect reduction. • ORNL TEM: annealing

improves in-situ nanoporosity and increases Ni dissolution.

12

0.300.350.400.450.500.55

0 20 40 60 80 10012

14

16

18

20

ORR

Mas

s Ac

tivity

(A/m

g Pt)

SET Treatment Level (Arb. Units)

DOE2017

Target

Mas

s Sp

ecific

Surfa

ce A

rea

(m2 /g

)

3.66 3.67 3.68 3.69 3.7012

14

16

18

20

Mas

s Sp

ecific

Surfa

ce A

rea

(m2 /g

)

FCC Lattice Const (A)

Annealed Bulk Pt3Ni7

D. Cullen, ORNL

Pt77Ni23

Pt82Ni18


Accomplishments and Progress Improved Activity, Rated-Power Capable ORR Catalysts (Task 1.1): Substantially Increased Rated Power; Mass Activity Retained.

13

• JHU dealloying development has substantially increased rated power capability with Pt3Ni7 cathodes. • Best Chem/EC: +20/+40%% J @ 0.60V

• Optimization for volume production needed.

0.30

0.35

0.40

0.45

Mas

s Ac

t. (A

/mg)

As-Mad

e3M

BL

JHU Che

mJH

U EC12

14

16

18

Spec

. Are

a (m

2 /g)

Mass activity is retained after dealloying; small

area loss.

0.0 0.5 1.0 1.5 2.00.5

0.6

0.7

0.8

0.9

1.0

Best JHUEC Dealloy

To Date

Best JHUChem. Dealloy

To Date

3M BaselineDealloyedCe

ll Vol

tage

(Vol

ts)

J (A/cm2)


Non-Dealloyed

Cathode: Pt3Ni7/NSTF, 0.125mgPt/cm2


Accomplishments and Progress Improved Activity, Rated-Power Capable ORR Catalysts (Task 1.1): Dealloying Transforms Pt3Ni7/NSTF Surface from NiOx to Pt Rich; Forms Nanoporosity

14

Scanning transmission electron microscopy (STEM) and X-ray

photoelectron spectroscopy (XPS) – ORNL, D. Cullen, H. Meyer

No Dealloy – Nonporous Pt3Ni7 with thin NiOx layer.

JHU Chem. Dealloy – Porous Pt42Ni58 with Pt enriched surface layer.


Accomplishments and Progress Best of Class Component Integration (Task 4.1): 2014 3M NSTF Best of Class MEA - High Rated Power and Mass Activity; G/NG Achieved

Go/No Go Metrics

Pre-Proj. Mar. ‘12

2014 BOC Mar. ‘14

≤0.135 mgPGM /cm2

0.151 0.129

≥0.659V @1.41A/cm2

0.609 0.668

Path to 2017 MEA Performance, Loading Targets: 1) Increase 0.80V H2/Air Activity (Min. Transport Loss; Increase Mass Activity > 0.5A/mg (anneal+dealloy))

2) Reduce HFR (Thinner, Low EW Supported PEM; GDLs; Interfacial R. Minimization).

15

Go/No Go Metrics Achieved

Key Improvements 1. Anode optimization to min. PGM. 2. Best practice cathode dealloying –

high J and 0.38A/mg mass activity. 3. Improved flow field w/ modestly

narrower lands, channels than FC Tech. Quad Serp. – in line with current trends.

4. 15% thinner PEM.

0.6

0.7

0.8

0.9

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.000.000.050.10

G/NG

2014 Best of Class NSTF MEA - 0.129mgPGM/cm2 TotalAN.:0.019PtCoMn/NSTF. CATH.:0.11Pt3Ni7 (DEALLOY). PEM: 3M 20µ 850EW. GDL: 2979/2979.

2014 BOC MEA0.129mgPGM/cm2

Pre-Contract Status2012 BOC MEA0.151mgPGM/cm2

90/84/84C, 7.35/7.35psig H2/Air, CS(2,100)/CS(2.5, 167)GDS(0.02->2->0.02, 10steps/decade, 120s/pt, 0.4V limit, 0.1maxJstep)High->low J OnlyOUTLET P CONTROL

Cell V

olta

ge(V

olts

)

Kinetic+HFR Only Pol. CurveThrough 1/4 Power, Rated Power,

and Q/∆T(90oC) Targets

HFR Needed to Achieve Target

J (A/cm2)

HFR

(ohm

-cm

2 )


Accomplishments and Progress Best of Class Component Integration (Task 4.1): PGM, Rated and Specific Power Targets Approached @ 150kPa, 0.67V ; All 2017 MEA Perf. Targets @ 250kPa

16

• Steady improvement in total PGM, rated power, and specific power.

• At 150kPa, within 10% of 4 DOE 2017 targets @ 0.67V.

• At 250kPa, all 2017 performance targets approached or achieved.

Characteristic Unit Target Value @ 150kPa Performance @

0.80V mA/cm2 ≥300 125 (~190 w/ low RH)

Q/∆T kW/°C ≤ 1.45 1.56 (0.67V,90°C)

(+20mV @ 90°C) or (+4°C @ 0.67V)

Performance @ rated power mW/cm2 ≥ 1000 932 (0.67V)

Specific Power g/kW ≤ 0.125 0.138 (0.67V) PGM Content mg/cm2 ≤ 0.125 0.129

Value @ 250kPa

285

1.42 (0.70V,90°C)

1020 (0.70V)

0.127 (0.70V) 0.129

0.0 0.5 1.0 1.50.6

0.7

0.8

0.9

2014(March) BOCMEA @ 90oC, 250kPa

J (A/cm2)

Model Curve which meetsRated Power, Specific Power,Q/∆T, & 1/4 Power 2017 Tgts

"Rated Power"1.46A/cm2

@ 0.699V90/76/76C, CS2/2.5 H2/Air, 120s/pt

2012

(Marc

h)

2012

(Sep

t)

2013

(Marc

h)

2013

(Dec

)

2014

(Mar)

DOE 2017

Tgt0.10

0.15

0.20

0.250.6

0.8

1.0

1.2

1.40.10

0.12

0.14

0.16

Target0.125g/kW

250200150

Spec

ific P

ower

(g

PGM/k

W) @

0.6

7V

P(kPa)

Target1W/cm2

250200

150Rate

d Po

wer

W/c

m2 @

0.6

7V

P(kPa)

Target0.125mg/cm2To

tal P

GM

(mg/

cm2 )


Response To Reviewers’ Comments Addressing NSTF MEA Operating Condition and Impurity Sensitivities • “…project is limited to "optimization of existing components and processes" and … "NO COMPONENT

DEVELOPMENT." … unfortunate, since what is required … is … a new catalyst layer architecture.” • “major barrier to commercialization of NSTF is the high sensitivity to operating conditions, yet …

progress on these tasks is delayed or not even started.” • “…NSTF MEAs … extremely sensitive to both temperature and impurities relative to conventional MEAs.” •Component development not allowed in Topic 4 of 2011 FOA. New catalyst layer architecture could require its own project. We believe current Task 2+3 approach will be sufficient. •Work to address operating temp. sensitivity was in progress prior to AMR, but was too early in development for reporting. We agree, this is a key issue and is actively being addressed. •To our understanding, impurity sensitivity is proportional to surface area. Pt3Ni7/NSTF surface areas are increasing under Task 1, and added area from Task 2 interlayers should help.

OEM Participation; Validation in Stacks • “…3M has a history of showing great lab results that do not translate well to practical stacks…” • “… good … to see what stack formats and operating conditions will be used for…integration activities.“ • “For a ... (MEA) project, it is extremely surprising to see that the list of collaborators does not include a

stack developer (either automotive or otherwise).” • General Motors is the project partner responsible for stack testing, but wasn’t finalized until

after last year’s AMR. • We agree that integration into stacks is important. Cold-startup is much less challenging

with low heat capacity stacks than estimates from single cells. Stack optimization to enable demonstrated NSTF MEA rated power capability is necessary, but not in project scope.

17


Collaborations Johns Hopkins University (Jonah Erlebacher) – Subcontractor •Task 1 - Pt3Ni7/NSTF dealloying optimization. Oak Ridge National Laboratory (David Cullen) – Subcontractor •Task 1 - Characterization of dealloy/SET post-processed Pt3Ni7/NSTF cathodes. Freudenberg FCCT (Christian Quick) – Vendor •Task 2 – Experimental anode GDL backings. Michigan Technological University (Jeffrey Allen) – Subcontractor •Task 3 -GDL char.; Integration of 3M anode GDLs into MTU pore network model. Lawrence Berkeley National Laboratory (Adam Weber)–Subcontractor •Task 3 - GDL char.; Integ. MTU PNM into LBNL MEA model; Cold startup modeling. Argonne National Laboratory (Rajesh Ahluwalia) – Collaborator •Task 4 - NSTF BOC MEA HOR/ORR kinetic char. studies; FC systems modeling. Los Alamos National Laboratory (Mukundan, Borup) – Subcontractor •Task 5 – Load cycle durability evaluation General Motors (Balsu Lakshmanan) – Subcontractor •Task 6 – Short stack evaluation.

18


Key Future Work – FY14, FY15 Task 1 – Integration Activities Toward ¼ Power, Performance @ rated power… •Demonstrate Scale-up Feasibility of Downselected Dealloying, Annealing Methods •Integration of Next Generation Supported, Low EW PEMs

Task 2 - Integration …. Transient Response, Cold Start Up … •Continued Anode GDL and Cathode Interlayer Optimization; Diagnostic Studies.

Task 3 - Water Management Modeling for Cold Start • Finalize GDL Modeling @ MTU, Integrate MTU-LBNL Models→ Identify Key A. GDL Factors.

Task 4 - Best of Class MEA Integration Activities •Best of Class Component Integration Towards Project Goals: (≤ 0.125mgPGM/cm2; Rated Power, Q/∆T: 0.709V @ 1.41A/cm2 @ 90°C).

•Improvement in Cathode Activity, Durability Critical

Task 5 - Durability Evaluation and Performance Degradation Mitigation •Evaluation of New Cathodes (as available) to Achieve Electrocatalyst Durability Targets. •Irreversible Peak Power Loss Mitigation (Material Optimization; Recovery Methods)

Task 6 - Short Stack Performance, Power Transient, and Cold Start Evaluation • Achieve Required Robustness Metrics Through Incorporation of Improved Anode GDLs, Cathode Interlayers, and Next Generation PEMs. •Implement Short Stack Testing of Interim and Final Project Best of Class MEAs.

19


Summary

20

Operational Robustness (Cold Start; Load Transient) • Experimentally confirmed operational mechanism of cold-startup variation with

anode GDL backings. MTU GDL model experimentally validated w/ one project GDL to date. Benefits of sparse/dense GDL structures becoming evident.

• Cathode interlayer developed which improves load transient operating window by 20°C and has good durability and low PGM prospects.

Durability (MEA Load Cycling; MEA Chemical; Cathode) • Key mechanism of rated power loss identified – development direction for

improvement is forming. LANL onboarding into task has occurred smoothly. • MEA chemical durability of all components appears sufficient. • Cathode mass activity durability insufficient; being addressed outside project.

Power, Cost (Cathode Post Processing; Best of Class MEA Integration) • Annealing: 30% mass activity gain, via method development and improved

structural understanding. Dealloying: +20-40% lim. J over baseline method. Annealing & Dealloying integration, process feasibility are key next steps.

• MEA integration - substantial gains in specific power (+47% kW/g v. pre-proj.) due to improved absolute performance and PGM reduction towards target. Path to 2017 targets identified. Go/No Go Performance and Loading Metrics Achieved.

21

Technical Back-Up Slides

Instruction


Target Polarization Curve Calculation

• Polarization curves calculated which simultaneously meet ¼ power, Q/∆T, and rated power targets.

• Required performance decreases as cell temperature increases to 88°C (Q/∆T)

• Q/∆T target puts strict requirements on: • Cell T (≥88°C) • HFR (≤0.04ohm-cm2)

• Peak power (1W/cm2)

occurs at < 1.5A/cm2 and >0.70V.

0.00 0.25 0.50 0.75 1.00 1.25 1.500.5

0.6

0.7

0.8

0.9

1.0

88C and Hotter

85C

Target Performance @ 80C Target performance @ 85C Target performance @ 90C Target performance @ 95C

C:\Users\us314230\Documents\DOE6\FC23951_LowTotalLoadingPt3Ni7-[Graph12]

Cell V

olta

ge (V

olts

)

J (A/cm2)

Performance Needed To Simultaneously Achieve DOE2017 MEA Targets At Various Cell Temperatures

For T>90C, increasing temperature just decreases Q/dT furtherFor T<90C, kinetics must increase to increase cell V at peak power

J, V to Achieve Rated Power, Q/dT, 1/4 Power Targets80C: 1.31A/cm2 @ 0.761V. 0.760A/cm2 @ 0.80V85C: 1.37A/cm2 @ 0.725V. 0.417A/cm2 @ 0.80V.90C: 1.41A/cm2 @ 0.709V. 0.301A/cm2 @ 0.80V95C: 1.41A/cm2 @ 0.709V. 0.301A/cm2 @ 0.80V

80C

Targets Addressed: J @ 1/4 Power (0.8V, 0.30A/cm2), Rated Power (1W/cm2), and Q/∆T (1.45kW/degC)Model Assumptions: HFR: 0.04ohm-cm2, Tafel: 70mV/dec, No MTO, 90kW Stack

JRJJLOGVV −

−=

00 07.0

CTV

VkW

TQ

rated

rated

rated

40

25.190

−

−∗

=∆

22

3M High Performance, Durable, Low Cost MEAs. 2014 DOE Hydrogen, Fuel Cells, Vehicles Program AMR, June 16-20 23

0.0 0.2 0.4 0.6 0.8 1.0 1.20.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0Anode: 0.20PtCoMn/NSTF. Cathode: 0.20PtCoMn/NSTF.

PEM: 3M/G. GDL: 2975/2975

After 8550hrs

Initial

Ce

ll V

(V

olts),

HF

R (

oh

m-c

m2)

J (A/cm2)

FC12682 315.DAT NFAL (INITIAL)

FC12682 321.DAT NFAL

FC12682 712.DAT NFAL

Peformance After ~ x hours on Shiva, FC12682

80/80/80C, 0/0psig inlet, CF696/1657 H2/Air

GDS(0.0A/cm2->0.40V->0.0A/cm

2, 0.05 or 0.025A/cm

2/step, 20s/step)

After 3800hrs

Predicted Loss

0 2 4 6 8 10 12 140.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.00.5

0.6

0.7

0.8

0.9

0.0 0.5 1.0 1.5 2.00.5

0.6

0.7

0.8

0.9Limiting Current v. Cathode Surface Area

J @

0.5

0V

(A

/cm

2)

Cathode Catalyst Pt Surface Area

(cm2-Pt/cm

2-planar)

7200A PR

Initial Performance

1.2V CV Cycling, 95C

1.2V CV Cycling, 80C

80C Load Cycling (After Several 1000hrs)

Gas Replace Test

USFCC

Black Squares: Initial

Colored: After Durability

C

0.05/xPtCoMn/NSTF

3M 850EW Unsupported

0.05/xPtCoMn/NSTF

3M 850EW Unsupported

A

BOL Pol. Curves v. Support Area

0.05mgPt/cm

2

NSTF (5.8)

0.10mgPt/cm

2

NSTF (9.1)

Ce

ll V

(V

olts

)

J (A/cm2)

BOL Pol. Curves v. Loading

B

"Bad Support"

0.10mgPt/cm

2

NSTF (3.2)

"Good Support"

0.10mgPt/cm

2

NSTF (9.5)

Ce

ll V

(V

olts

)

J (A/cm2)

80/68/68C, 150/150kPa H2/Air, CS2/2.5 GDS (OCV->lim->OCV, 120s/pt)

• While PtCoMn/NSTF surface area is relatively stable, MEA performance degradation under H2/Air load cycling can be substantial. • Much larger than kinetic (70mV/dec)

and ohmic losses predict. • Appears irreversible – thermal cycling,

high E scans, … ineffective to date towards fully recovering performance.

Factors 1. H2/Air performance sensitivity to

cathode surface area (< 9cm2/cm2) 2. Previous work by collaborator

suggested 2nd possible mode, related to PEM degradation catalyst contamination.

BOL and Durability Aged Historical H2/Air Performance w/

80C Load and RH Cycling, 8500 hours 1000EW PEM, 0.20PtCoMn/NSTF on A+C

MEA Rated Power Durability – Background


2014 (March) Best of Class MEA – Kinetic Analysis

• Recent BOC MEA candidates show surprisingly strong H2/Air kinetic performance sensitivity to RH.

• Significant kinetic gains occur as RH is reduced below BOC test conditions (which are optimized for high J) – suggests possible O2 transport issue at cathode. • Low heat generation rates- waste heat aids

thermal gradient driven water removal. • Development in progress to improve kinetic

response under H2/Air via operational and material approaches.

Best of Class MEA H2/Air Kinetics, Mass Activities

MEA

H2/Air J @ 0.80V

(A/cm2

H2/O2 ORR Mass

Activity (A/mg)

Ca. PGM (mg/cm2)

2012 (March) 0.19 0.37 ± 0.01 0.121

2014 (March) 0.125 0.38 ± 0.02 0.110

0.0 0.1 0.2 0.3 0.40.70

0.75

0.80

0.85

Cell V

olta

ge (V

olts

)

J (A/cm2)

FC30550 531-637.RAW 80C FC30550 531-637.RAW 68C FC30550 531-637.RAW 61C FC30550 531-637.RAW 59C FC30550 531-637.RAW 53C FC30550 531-637.RAW 42C

80/x/xC, 7.35/7.35psig H2/Air, CS(2,100)/CS(2.5, 167)GDS(0.3->0.1, 0.05/step, 120s/pt) w/ 0.65V Precondition

Kinetic RHSens for Dealloyed Pt3Ni7 in FF2

~BOC TestCondition

When measured under “Best of Class” test conditions, 2014(March) BOC MEA

showed substantial decrease in ¼ Power Performance compared to 2012 MEA, but

mass activity relatively unchanged.

24

60 80 100 1200.000.050.100.150.200.25

60 80 100 1200.740.750.760.770.780.790.80

90oC Cell, 7.35/7.35psig H2/Air (OUTLET), CS(2,100)/CS(2.5, 167)

J (A

/cm

2 ) @ 0

.80V

Calc. Outlet RH (%)

FC029436 FC029489

Extracted from Pol. Curves,

Best Of ClassTesting RH

V @

0.3

0A/c

m2

(Vol

ts)

Calc. Outlet RH (%)

FC30392 V @ 0.3A/cm2March('14) BOC

y

Stable Valuesfrom 30minGSS Holds)

Best Of ClassTesting RH


Task 6 – Short Stack Evaluation – Robustness Metrics

1070 1080 1090 1100 1110-0.2

0.0

0.5

1.0 30/25/25C,

x/150kPa H2/Air,

522/1491SCCM

(CS1.5/1.8 @ 1A/cm2)

Cell V too low,

station reset to OCV

Initiate Fast

Step Up to

1A/cm2

30/25/25C,

x/150kPa H2/Air,

522/1491SCCM (CS1.5/1.8 @ 1A/cm2)

1) 1.0A/cm2, 15min

2) 0.1A/cm2, 3min

3) 0.25A/cm2, 1s

4) 0.50A/cm2, 1s

5) 0.75A/cm2, 1s

6) 1.00A/cm2, 1min

J (

A/c

m2),

V (

Vo

lts)

Time (sec)

FC30114 502-507.RAW Current Density Measured

V, 150kPa

V, 125kPa

V, 100kPa

Transient Sensitivity Test, x/150kPa

J (A/cm2)

Cell V

"Almost"

Recovery

w/ 100kPa

Anode

0 10 20 30-0.2

0.0

0.5

1.0

1) 1.0A/cm2, 15min

2) 0.1A/cm2, 3min

3) 0.25A/cm2, 1s

4) 0.50A/cm2, 1s

5) 0.75A/cm2, 1s

6) 1.00A/cm2, 1min

J (

A/c

m2),

V (

Vo

lts)

Time (sec)

FC30114 502-507.RAW Current Density Measured

V, 150kPa

V, 125kPa

V, 100kPa

Steady State Sensitivity Test, x/150kPa

J (A/cm2)

Cell V @ 150, 125, 100kPa Anode

Cell V too low,

station reset to OCV

30/25/25C,

x/150kPa H2/Air,

522/1491SCCM (CS1.5/1.8 @ 1A/cm2)

• NSTF MEA w/ interim downselect anode GDL, cathode interlayer from Task 2 “almost” passes cold operation and cold transient tests (above).

• Easily passes Hot Operation test (right).

Cold Operation Test v. PA Cold Transient Test v. PA

0 10 20 300.0

0.5

1.0

0 10 20 3075

80

85

90

95

HFR

90C Cell

VAvg: 0.648V

x/59/59C, 150/150kPa H2/Air,

CS(1.5,100)/CS(1.8, 167)

GSS(1)

J (

A/c

m2

), V

(V

olts),

HF

R (

oh

m-c

m2)

80C Cell

VAvg: 0.642V

J

Ce

ll T

(d

eg

C)

Time (min)

FC30114 543-544.RAW Cell Temperature Measured

Hot Robustness Test, Trial 1

CCM: 0.05PtCoMn/0.15PtCoMn, 3M 20u 825EW Anode GDL: X+PTFE, MPL (interim DS). Cathode IL: 2979+ “B” IL @ ca. 0.03mgPt/cm2(interim DS)

25

3M High Performance, Durable, Low Cost MEAs. 2014 DOE Hydrogen, Fuel Cells, Vehicles Program AMR, June 16-20 26

Cold Startup: Effective Properties

Model prediction and experimental measurement [1] of effective thermal conductivity for a dry GDL under strain. MTU Pore Network Model accounts for change in contact resistance due to GDL compression.

Effective Thermal Conductivity

Freudenberg H2315 at 1.5A/cm2

with 50% heat and 80% water on cathode for a range of conditions. Steady-state effective permea-bilities were also calculated for Toray T060 and found to corre-spond to experimental values [2].

Transient Effective Permeability Transient Effective Diffusivity

Toray T060 w/ and w/o MPL on cathode side at 1.5A/cm2 with 50% heat and 50% water.

Cold Startup Modeling (Task 3): MTU Pore Network Model Calculations of GDL Effective Properties.

1. Burheim, Pharoah, Lampert, Vie, and Kjelstrup, J. Fuel Cell Sci. Tech., 8(2): 021013 (2011) 2. Gostick, Fowler, Pritzker, Ioannidis, and Behra, J. Power Sources ,162(1): 228-238 (2006)

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