Lead Research and Development Activity for DOE’sHigh Temperature, Low Relative

Humidity Membrane ProgramJames Fenton

University of Central Florida-FSECJune 11, 2008 Project ID #

FC 15This presentation does not contain any proprietary, confidential, or otherwise restricted information

2

Overview

• April 1, 2006• March 31, 2011• 40% Complete

• Barriers addressed– D. High Conductivity at Low RH & High T– C. High MEA Performance at Low RH & High T– A. Membrane and MEA durability

• Targets– Conductivity = 0.07 S/cm @ 80% relative humidity

(RH) at room temp using alternate material – 3Q Yr 2 milestone

– Conductivity >0.1 S/cm @ 50% RH at 120 oC – 3Q Yr 3 Go/No Go• Total project funding

– DOE share - $2,500K – Contractor share - $625K

• Funding received in FY07- $550K• Funding for FY08 - $585K

Timeline

Budget

Barriers

• BekkTech LLC – In–plane conductivity protocols

• Scribner Associates – Through-plane conductivity protocols

• Project management

Partners

3

Objectives

• New polymeric electrolyte/phosphotungstic acid membranes

• Development of standardized characterization methodologies– Conductivity f(RH, T, Prep. Procedure) [Through- & In-Plane]– Characterize mechanical, mass transport and surface

properties of membranes– Evaluate fuel cell performance and predict durability of

membranes and MEAs fabricated from other eleven HT Low RH Membrane Programs

• Provide HTMWG members with standardized methodologies

• Organize HTMWG biannual meetings

4

MilestonesMonth/Year Milestone or Go/No-Go Decision

Sept-07 Complete analysis of in-plane and through-plane conductivity of commercial membranes.

Dec-07 Milestone: Complete conductivity characterization of first threemembranes from Topic 1 awardees.

Dec-07 Milestone: Demonstrate conductivity = 0.07 S/cm @ 80% relative humidity (RH) at room temp using alternate material

Jun-08 Milestone: Establish MEA test protocol

Sept-08 Milestone: Complete manufacturing of first MEA from working group members

Dec-08 Go/No-Go Decision: Demonstrate conductivity of 0.1 S/cm, 50% RH, 120 °C

5

Approach

Improve Conductivity:Task 1. FSEC develops non-Nafion®

based Poly[perfluorosulfonic acid] -phosphotungstic acid composite membrane and membrane electrode assembly (MEA) fabrication (PFSA-PTA)

Task 2. FSEC develops sulfonatedpoly(ether ketone ketone) or sulfonated poly(ether ether ketone) - Phosphotungstic Acid Composite Membrane and MEA Fabrication (SPEEK-PTA)

Improve FC Performance:Task 5. Characterize performance of

MEAs for Topic 1 members

Task 6. Characterize membrane and MEA durability for Topic 1 members

Standardize TestingTask 3. In-Plane conductivity

measurements by partner

Task 4. Through-Plane conductivity measurements by partner

Task 7. Meetings and Activities of HTMWG

6

• Conductivity• Performance• Durability

– Chemical– Mechanical

Technical Accomplishments/ Progress/Results

7

In-Plane Conductivity Measurements

1

10

100

1000

10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%

Relative Humidity (%RH)

Con

duct

ivity

(mS/

cm)

NRE-212 (3-20-07) 120C

NRE-212 (3-20-07) 80C

NRE-212 (3-20-07) 30C

Conductivity ≥0.1 S/cm @ 25 -50% RH at 120 °C – 3Q Yr 3

Go/No Go

3QYr 2 Milestone - 0.07S/cm @ 80% RH at 30 oC

Current StatusCurrent Status

Gap

8

30 oC, 80% RH Conductivity MilestoneGroup 1 Membranes

•Samples tested at 30 °C, 80% RH ~100 kPa at BekkTech as of April 24, 2008

0

10

20

30

40

50

60

70

80

90

100

30 °C

Mile

stone

Nafion

® 212 A B C D E F G H I J

Cond

uctiv

ity (m

S/cm

)

9

In-Plane vs. Through-Plane Conductivity (milestone)

NRE 211 at 30, 80, &120 oCAlso Tested NRE-212, NE-1135 & N 117

ScribnerAssociatesi n c o r p o r a t e d

Through-Plane and In-Plane Conductivity of Nafion NRE-211

1

10

100

1000

10 20 30 40 50 60 70 80 90 100Relative Humidity (%)

Con

duct

ivity

(mS/

cm)

BekkTech, NRE-211, 120C (3-22-07)SAI, NRE-211, 120C, 8/31/2007BekkTech, NRE211 at 80C (3-21-07)SAI, NRE-211, 80C, 8/29/2007BekkTech, NRE211 at 30C (3-21-07)SAI, NRE-211, 30C, 8/30/2007 - #2

Through-PlaneIn-Plane

10

FSEC-3 Meets Conductivity Milestone!(PFSA-PTA)

Comparing to Nafion ® at 30 o C 100 kPa

1

10

100

1000

10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%

Relative Humidity (%RH)

Con

duct

ivity

(mS/

cm)

FSEC-3 (2-26-08) 30 C

NRE-212 (3-20-07) 30C

Sample Result at 80% RH, 30 C: 79.7 mS/cm

DOE Milestone at 80% RH, 30 C: 70 mS/cm

11

FSEC-3 Tested at 30 oC, 80 oC, 120 oC(PFSA-PTA)

1

10

100

1000

10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%Relative Humidity (%RH)

Con

duct

ivity

(mS/

cm)

FSEC-3 (2-27-08) 120 C

FSEC-3 (2-26-08) 80 C

FSEC-3 (2-26-08) 30 C

12

Conductivity of FSEC-SLR3(SPEEK-PTA)

Comparing to Nafion® at 30 oC 100 kPa

0.1

1.0

10.0

100.0

1000.0

10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 110%

Relative Humidity (%RH)

Con

duct

ivity

(mS/

cm)

SLR-3 (4-10-08) 30CNRE-212 (3-20-07) 30CSample Result at 80% RH, 30C: 35.7 mS/cmDOE Milestone at 80% RH, 30 C: 70 mS/cm

13

Progress Toward 120 oC Go/No Go

Meet 30 °C, 80% RH Milestone Status Toward 120 oC, 50% RH Go/No Go

0

20

40

60

80

100

120

120 °CMilestone

Nafion® 212 FSEC-SLR-3 FSEC-2 FSEC-3

Con

duct

ivity

(mS/

cm)

0

10

20

30

40

50

60

70

80

90

30 °CMilestone

Nafion® 212 FSEC-SLR-3 FSEC-2 FSEC-3

Con

duct

ivity

(mS/

cm)

14

Performance

Jun-08 Milestone: Establish MEA test protocol

Sept-08 Milestone: Complete manufacturing of firstMEA from working group members

15

MEA Test Apparatus

VaVc

CathodeHumidifier

CathodeMass Flow Controller

Valve

O2 or Air

AnodeMass Flow Controller

Valve

H2

AnodeHumidifier

MembraneElectrodeAssembly

CathodeExit

AnodeExit

10.2910115050100120

20.79511502582120

6.51701013590120

26.25251502565100

6.51701017090100

13.8635101757380

kPakPakPa%°C°C

Inlet PO2 in AirInlet PH2OPtotalR. H. Inlet CathodeT cathode humidiferTcell

10.2910115050100120

20.79511502582120

6.51701013590120

26.25251502565100

6.51701017090100

13.8635101757380

kPakPakPa%°C°C

Inlet PO2 in AirInlet PH2OPtotalR. H. Inlet CathodeT cathode humidiferTcell

16

Electrochemical Testing

Cell Performance with FSEC-3 Cell Performance with Nafion® 112

CV CV ——> ECA> ECA

CV of Cathode Pt/C

80 oC Air and O2 Performance FSEC-3

Current Density, i (mA/cm2)10 100 1000

Vce

ll Vol

tage

(V)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0R

esis

tanc

e (O

hm-c

m2 )

0.0

0.2

0.4

0.6

0.8

1.0

Voltage, OxygenVoltage, AirResistance, OxygenResistance, Air

80 oC Air and O2 Performance Nafion 112

Current Density, i (mA/cm2)10 100 1000

Vce

ll Vol

tage

(V)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Res

ista

nce

(Ohm

-cm

2 )

0.0

0.2

0.4

0.6

0.8

1.0

Voltage, OxygenVoltage, AirResistance, OxygenResistance, Air

LSV LSV →→ HH22 CrossoverCrossover

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.0 0.2 0.4 0.6 0.8 1.0

E (V)

Curr

ent D

ensi

ty (A

/cm

2)

(Area under peak)

(scan rate)*(210μC/cm2-Pt)*(Pt loading)ECA =(Area under peak)

(scan rate)*(210μC/cm2-Pt)*(Pt loading)ECA =

-0.040

-0.030

-0.020

-0.010

0.000

0.010

0.020

0.030

0.040

0.050

0.0 0.2 0.4 0.6 0.8 1.0

E (V)

I (A

/cm

2)

H2 crossover, LSV

CV CV ——> ECA> ECA

CV of Cathode Pt/C

80 oC Air and O2 Performance FSEC-3

Current Density, i (mA/cm2)10 100 1000

Vce

ll Vol

tage

(V)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0R

esis

tanc

e (O

hm-c

m2 )

0.0

0.2

0.4

0.6

0.8

1.0

Voltage, OxygenVoltage, AirResistance, OxygenResistance, Air

80 oC Air and O2 Performance Nafion 112

Current Density, i (mA/cm2)10 100 1000

Vce

ll Vol

tage

(V)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Res

ista

nce

(Ohm

-cm

2 )

0.0

0.2

0.4

0.6

0.8

1.0

Voltage, OxygenVoltage, AirResistance, OxygenResistance, Air

LSV LSV →→ HH22 CrossoverCrossover

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.0 0.2 0.4 0.6 0.8 1.0

E (V)

Curr

ent D

ensi

ty (A

/cm

2)

(Area under peak)

(scan rate)*(210μC/cm2-Pt)*(Pt loading)ECA =(Area under peak)

(scan rate)*(210μC/cm2-Pt)*(Pt loading)ECA =

-0.040

-0.030

-0.020

-0.010

0.000

0.010

0.020

0.030

0.040

0.050

0.0 0.2 0.4 0.6 0.8 1.0

E (V)

I (A

/cm

2)

80 oC Air and O2 Performance FSEC-3

Current Density, i (mA/cm2)10 100 1000

Vce

ll Vol

tage

(V)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0R

esis

tanc

e (O

hm-c

m2 )

0.0

0.2

0.4

0.6

0.8

1.0

Voltage, OxygenVoltage, AirResistance, OxygenResistance, Air

80 oC Air and O2 Performance Nafion 112

Current Density, i (mA/cm2)10 100 1000

Vce

ll Vol

tage

(V)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Res

ista

nce

(Ohm

-cm

2 )

0.0

0.2

0.4

0.6

0.8

1.0

Voltage, OxygenVoltage, AirResistance, OxygenResistance, Air

LSV LSV →→ HH22 CrossoverCrossover

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.0 0.2 0.4 0.6 0.8 1.0

E (V)

Curr

ent D

ensi

ty (A

/cm

2)

(Area under peak)

(scan rate)*(210μC/cm2-Pt)*(Pt loading)ECA =(Area under peak)

(scan rate)*(210μC/cm2-Pt)*(Pt loading)ECA =-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.0 0.2 0.4 0.6 0.8 1.0

E (V)

Curr

ent D

ensi

ty (A

/cm

2)

(Area under peak)

(scan rate)*(210μC/cm2-Pt)*(Pt loading)ECA =(Area under peak)

(scan rate)*(210μC/cm2-Pt)*(Pt loading)ECA =

-0.040

-0.030

-0.020

-0.010

0.000

0.010

0.020

0.030

0.040

0.050

0.0 0.2 0.4 0.6 0.8 1.0

E (V)

I (A

/cm

2)

H2 crossover, LSV

-0.004

-0.003

-0.002

-0.001

0.000

0.001

0.002

0.003

0.004

0.0 0.2 0.4 0.6 0.8 1.0

E (V)

I (A

/cm

2)

H2 crossover, LSV

17

In Situ Investigation of MEA Degradation

• MEAs investigated: – Nafion® and FSEC-1 and FSEC-3

• Tested MEAs under different degradation conditions: – 90 °C; 35% RH; OCV; 100 hr

• Degradation evaluated in several ways: – Electrochemical Pre- and Post-testing

• H2 crossover, ECA, polarization, resistance – Material testing before and after degradation test

• mechanical strength, materials science– During the test

• fluoride emission rate, voltage monitored

18

Membrane Durability

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1 10 100 1000 10000I (mA/cm2)

E (V

)

0

50

100

150

200

250

N112 Pretest N112 PosttestFSEC1 Pretest FSEC1 PosttestFSEC3 Pretest FSEC3 PosttestR N112 Pretest R N112 PosttestR FSEC1 Pretest R FSEC1 PosttestFSEC3 Pretest R FSEC3 Posttest

Res

ista

nce(

ohm

-cm

2 )

19

Fluoride Emission Rate90 °C; 35% RH; OCV; 100 hr

90C 30% RH, OCV

0

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150

Time (hr)

FER

( μm

ol/c

m2 h

)N112 AnodeN112 CathodeFSEC1 AnodeFSEC1 CathodeFSEC3 AnodeFSEC3 Cathode

20

Rationale for the Investigation of Membrane/MEA Mechanical Degradation

• Mechanical properties degradation: phenomena and relevance– The beginning-of-life (BOL) mechanical properties of membranes are

adequate, typically– Mechanical properties rapidly decay as a result of accumulated

chemical (e.g., load cycling + OCV) and mechanical effects (e.g., RH cycling)

– Fracture of mechanically weakened membrane can be the life-limiting failure mode for PEM devices

• It is important to – quantify the membrane mechanical robustness while optimizing other

properties of high temperature membrane– further understand the underlying mechanisms that are responsible

for the mechanical decay

21

Membrane/MEA mechanical degradation: modulus of toughness

X. Huang, W. Yoon, M. Rodgers

Modulus of toughness = Energy per unit volume necessary to rupture the material,Joule/m3 or milli‐Joule/mm3

21.757

0.012

26.554

0.429

25.040

0.011

24.113

0.426

16.446

0.067

19.865

0.2020.245

23.159

0.828

0

5

10

15

20

25

N112 control N112 after OCV FSEC1 control FSEC1 after OCV

Modulus of Toughness (m

J/mm^3)

90 °C; 35% RH; OCV; 100 hr

22

Future Work

• Complete characterization of HTMWG membranes

• Establish MEA test protocol (milestone)

• Manufacture first MEA from HTMWG membrane (milestone)

• Demonstrate conductivity of 0.1 S/cm, 50% RH, 120 °C (Go/No Go)

23

TOP VIEW

SIDE VIEW8-Cell MEA Durability Test System

ScribnerAssociatesi n c o r p o r a t e d

• Simultaneous, independent operation of 8 cells

• Fully automatic – 24/7 operation• Common RH system• Adjustable cell temperature and

reactant flow• Individual cell diagnostics• Manual over ride• Individual cell replacement

24

Summary• Relevance - A new membrane material for PEM Fuel Cells with sufficiently improved

conductivity at high temperature(120 °C) and low RH is required for the transportation F/C market. A new method for measuring membrane conductivities with sufficient accuracy and reliability is required for DOE program decisions.

• Approach - Develop and demonstrate new materials for membranes, and define and apply new tools and procedures for membrane conductivity testing.

• Tech. Accomplishments /Progress– FSEC-3 exceeds conductivity goal, demonstrating conductivity >0.07 mS/cm at

80% RH and 30 oC. – Manufactured MEAs from Nafion® and FSEC membranes– Performance and durability testing of Nafion® and FSEC MEAs– Much reduced FER with FSEC membranes– Provided independent conductivity measurements for HTMWG members

• Collaborations– Active partnership with BekkTech LLC and Scribner Associates – Working closely with HTMWG members to provide accurate data under

standardized conditions– Provided protocol to HTMWG members– Demonstrated Agreement between through-plane and in-plane conductivity

measurements