D. Gervasio (PI) C.A. Angell, R. Marzke, J. Yarger (co-PI)

Arizona State University;

W. Youngs (co-PI)University of Akron

June 9, 2008

Project ID #FC 17

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

2008 DOE Hydrogen Program Review

Protic Salt Polymer Membranes: High-Temperature Water-Free Proton-Conducting Membranes

2

Overview

• January 15, 2006• January 14, 2011

– go/no go end of year 3• 60% completed

• Barriers addressed by this project from the HFCIT Program Multi-Year Program Plan– (A) Durability– (C) Electrode Performance

• Total project funding$1,500K

– DOE: 80%, Contractor: 20%• Funding received in FY06

– $300,000• Funding for FY07

– $300,000• Funding for FY08

– $200,000/$300,000

Timeline

Budget

Barriers

• Arizona State University• University of Akron• Boeing

• DOE Technology Development Manager: Terry Payne• DOE Project Officer: Reginald Tyler• ANL Technical Advisor: Thomas Benjamin

Partners

3

To make proton-conducting solid polymer electrolyte membrane (PEM) materials having:

• high proton conductance at high temperature (up to 120oC)• effectively no co-transport of molecular species with proton• reduction of fuel cell overvoltage• good mechanical strength and chemical stability

Objectives

4

MilestonesMonth/Year Milestone or Go/No-Go DecisionJan-08 Milestone: 2 kinds of high temperature proton-conducting protic salts

membranes were made into MEAs and tested in fuel cells: (i) leachable protic ionic liquid filled membrane and (ii) membranes with non-leachable salt moieties covalently and electrostatically bound to the polymer. Determine conductivity of membrane at 0 to 25% RH and the full range of temperature (-40 to 120oC) and compare to target of 0.1 S/cm . Determine conductivity in absence of free solvents.

May-08 Milestone: Complete initial round of MEA fabrication and testing with selected new polymers (1 done 3 more sent in progress) to provides external validation and information on the catalyst behavior under low RH conditions.

Nov-08 Milestone: Design targets defined and measured for conductivity (0.05 to 0.2S/cm) and gas permeability (< 2mA/cm2 measured with a catalyst coated membrane for both hydrogen and oxygen crossover) for high-temperature, low RH operation without external humidification.

Nov-08 Milestone: Design targets defined and measured for conductivity (0.05 to 0.2S/cm) and gas permeability (< 2mA/cm2 measured with a catalyst coated membrane for both hydrogen and oxygen crossover) for high-temperature, low RH operation without external humidification.

5

SYNTHESIS OF “DRY” PROTON ELECTROLYTE MEMBRANEs (PEMs)PEMs are being made based on “solvent free” protic ionic liquid (pIL) concepts.

pILs can be used to model membranes (stability, conductivity) and to act as a plasticizers in membranes.

Acid and base moieties & polymers are varied to optimize properties in 2 kinds of PEMs.1. pIL filled membranes (pIL act as leachable plasticizers) 2. Membranes with covalently and electrostatically non-leachable immobilized ions are being made.

CHARACTERIZATIONProton conductivity characterized by electrochemical impedance spectroscopy (EIS) from -20 to 120oC

Thermal & oxidative stability of these electrolytes are measured by Thermal Gravimetry (TGA) from -20 to 120oC

Electrochemical stability and chemical reduction polarization are surveyed by cyclic voltammetry on Pt

Fuel cell stability and performance is estimated by short term steady state I/V curves

The mechanism of transport of protons, anions, and molecules investigated three NMR methods:1. pulse field gradient NMR to determine the diffusivity of ions, 2. multipulse solid state NMR to measure the molecular motion and interactions of species in membranes,3. electrochemical NMR to measure distribution of species during proton conduction.

Approach

6

A protic ionic liquid (pIL) is made by transferring a proton from an acid to a base.

Energy Diagram for the EAN(ethyl ammonium nitrate) pIL with:- proton transferred (Left) - not transferred (Right),

E

EtNH3+… NO3

- HNO3 … EtNH2

Proton Coordinate

E

EtNH3+… NO3

- HNO3 … EtNH2EtNH3+… NO3

- HNO3 … EtNH2

Proton CoordinateProton Coordinate

Gurney proton energy level diagram. For any pair of levels, the stable entities are

upper right and lower left.

pILs belong to a new class of solvent-free proton-conducting electrolyte that can function at very high temperatures

PROTIC IONIC LIQUID (pIL) CONCEPTS

EANΔpk = 14

7

Plan & Progress

Task 1: pIL Design and Testing- mixed acid and base moieties as electrolyte- models for high temp (120oC) membrane

Task 2: Proton Conducting Membranes2.1.1 - Porous support with a PIL 2.1.2 - PIL swollen in polymers2.2 - Immobilized PIL polymer

Task 3: Temp Dependence of Electrolyte- 3.1 Conductivity, and durability of electrolytes

-- at T = 120°C, 100°C, 80°C, 20°C and -20°

Task 4: Proton Conduction by NMR4.1 Pulsed field gradient NMR 4.2 Electrochemical NMR (eNMR)4.3 eNMR Hittorf

Task 5: Iterate Synthesis- to optimize stability, conductivity

Task 6: Membrane Demonstration- ASU sent 4 membranes to CFU

50%

com

plet

e50

% c

ompl

ete

60%

com

plet

e

33%

com

plet

e75

% c

ompl

ete

50%

com

plet

e

8

Technical Accomplishments: Proton ConductivityComparing to Nafion at 30C 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)

ASU (4-22-08) 30C

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

Sample Result at 80% RH, 30C: 46.7 mS/cm

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

Conductivity Calculatedbased on dry dimensions

and no swelling

4 Electrode Conductivity

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)

ASU #2 (4-23-08) 120C

ASU (4-22-08) 80C

ASU (4-22-08) 30C

Conductivity Calculatedbased on dry dimensions

and no swelling

There are three more membranes soon to be characterized by BEKKTECH:

I. Crosslinked hydroxyethyl cellulose (HEC) containing 40wt% EAN,

II. HEC containing 60wt% mixture of NH4NO3and NH4CF3SO3 (6:4),

III. and crosslinked polysiloxane membrane containing 40wt% EAN

ASU membrane characterized by BEKKTECH and graphically reported here is:

Crosslinked hydroxyethyl cellulose (HEC)with 60wt% ethylammonium nitrate (EAN).

9

Comparing to Nafion at 80C 100 kPa

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)

ASU (4-22-08) 80CNRE-212 (3-20-07) 80CASU #2 (4-23-08) 80C

Conductivity Calculatedbased on dry dimensions

and no swelling

Comparing to Nafion at 30C 100 kPa

1

10

100

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

Relative Humidity (%RH)

Con

duct

ivity

(mS/

cm)

ASU (4-22-08) 30C

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

Conductivity Calculatedbased on dry dimensions

and no swelling

Comparing to Nafion at 120C 230 kPa

1.0

10.0

100.0

1000.0

10000.0

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

Relative Humidity (%RH)

Con

duct

ivity

(mS/

cm)

NRE-212 (3-20-07) 120CASU #2 (4-23-08) 120C

Sample Result at 25% RH, 120C: 20.0 mS/cmSample Result at 50% RH, 120C: 70.0 mS/cmDOE Go / No-Go of 100 mS/cm at 120 C

Conductivity Calculatedbased on dry dimensions

and no swelling

Technical Accomplishments: Proton Conductivity

Proton conductivity determined by BEKKTECH for ASU’s Protic Salt Membrane

Crosslinked hydroxy ethyl cellulose (HEC)with 60wt% ethylammonium nitrate (EAN)

• is similar to the limited conductivity data obtained by ASU

• is representative of many of the Protic Salt Membranes with “sorbed” plasticizer and

• is comparable to the DoE target.

10

0 10 20 30 40 50 60 700.0

0.1

0.2

0.3

0.4

0.5

0.6

0

1

2

3

4

5

6

7

8

9

Pow

er /

mW

cm

-2

I/V curveE

/ V

I / mA cm-2

Polarization Curve for Hydrogen/ Oxygen Fuel Cell with a crosslinked hydroxyethyl cellulose membrane containing 20wt% polyammonium styrenesulfonic acid and 60wt% ionic mixture of 6 NH4NO3 and 4 NH4CF3SO3.

. T= 125oC; Ptotal= 1 atm. P(H2O)= 24 torr in H2 and O2 feeds.

Leachable

Technical Accomplishments: Fuel Cell Performance

Best Protic Salt Membrane to date: composite polymer with 60 wt% Eutectic plasticizer

Need to test in fuel cell

11

0 10 20 30 40 500.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0

2

4

6

Pow

er /

mW

cm

-2

E / V

I / m A cm -2

I / V curve

Polarization Curve for Hydrogen/Oxygen Fuel Cell with crosslinked hydroxyethyl cellulose membrane containing 60wt% ionic mixture of 6 moles NH4NO3 and 4 moles NH4CF3SO3.

Cell was tested at 138oC with P(H2O )= 24 torr in H2 and O2 feeds.

Leachable

Technical Accomplishments: Fuel Cell PerformanceAnother Protic Salt Membrane with 60wt% of Eutectic Salt Plasticizer

12

0.1 1 100.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.0

0.5

1.0

1.5

E /

V

I / mA cm-2

I / V curve

Pow

er /

mW

cm

-2

Crosslinked hydroxyethyl cellulose loaded with 45wt% Ionic liquid

(NH4NO3:NH4CF3SO3=6:4) at 123oC second run

I’st run 2’nd run

Impedance and Fuel cell Polarization with a crosslinked hydroxycellulose membrane filled with 45wt% of ionic liquid consisting of NH4NO3:NH4CF3SO3 at 123oC. ETEK ELAT electrodes with 0.5 mg-Pt/cm2 and ambient pressure. NO HYDRATION.

Leachable

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.50.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Z" /

Ω

Z' / Ω

70oC 100oC 123oC 123oC after 1st I/V curve 123oC after 2nd I/V curve

EIS for H+ conductivity Fuel Cell I/V Curve

Technical AccomplishmentsProtic Salt Membrane with 45wt% of Eutectic Salt Plasticizer

13

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.50.0

0.2

0.4

0.6

0.8

1.0

1.2

Z" /

Ω

Z' / Ω

75oC 93oC 110oC 127oC 133oC after 1st IV curve 133oC after 3rd IV curve 133oC after 5th IV curve 133oC after 7th IV curve

0.1 1 100.0

0.1

0.2

0.3

0.4

0.5

0.6

0.0

0.5

1.0

1.5

2.0

E /

V

I / mA cm-2

I/V curve

Pow

er /

mW

cm

-2

I/V curve and power for the fuel cell based on anodisc imbibed with polysiloxane with pendant

sulfonic acid that neutralized by methylamine. Fuel cell runs at 127oC

Impedance and polarization curves for “dry” non leachable membranes consisting of an Anodisc (Whatman alumina membrane, t = 60 micron, pore diameter = 100 micron) filled with solid polysiloxane with pendant sulfonic acid that fully neutralized with methylamine

Non-leachablePendant sulfonic acid polymer fully neutralized with methyl amine

Fuel Cell I/V CurveEIS for H+ conductivity

Technical Accomplishments: non-leachable PEM 1

SiO

HO3S

n CH3NH2Si

OSix

On-x

-O3SCH3NH3+

-O3SCH3NH3+

14

6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.50.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Z" /

Ω

Z' / Ω

101oC 122oC 126oC after 1st IV Curve 126oC after 3rd IV Curve 126oC after 5th IV Curve

0.1 1 100.0

0.1

0.2

0.3

0.4

0.5

0.0

0.2

0.4

0.6

0.8

1.0

1.2

E / V

I / mA cm-2

I/V curve

Pow

er /

mW

cm

-2

Anodisc loaded with polysiloxane with pendant amine that fully neutralized with methanesulfonic acid at 126oC

Impedance and polarization curves for “dry” non leachable membranes consisting of an Anodisc (Whatman alumina membrane, t = 60 micron, pore diameter = 100 micron) filled with solid polysiloxane with pendant amine fully neutralized with methylsulfonic acid.

H2 / O2 Fuel Cell I/V CurveEIS for H+ conductivity

Technical Accomplishments: Non-leachable PEM 2

SiO

n SiO

SixO

n-x

NH2 +NH3O 3S -CH3

O 3S HCH3

+NH3O 3S -CH3

Non-leachablePendant propyl amine polymer fully neutralized with methyl sulfonic acid

15

Si

O

HO3S

nCH3NH2

Si

O

SixO

n-x

-O3SCH3NH3+

-O3SCH3NH3+

Si

O

nSi

O

SixO

n-x

NH2+NH3

O 3S -CH3

O 3S HCH3

+NH3O 3S -CH3

Technical Accomplishments: non-leachable PEMs

Two non-leachable protic salt polymer membranes

1. Pendant sulfonic acid polymer fully neutralized with methyl amine

2. Pendant propyl amine polymer fully neutralized with methyl sulfonic acid

Critique of non-leachable PEMPro: These data do illustrate the concept of using a protic-salt membrane as a “dry” proton-conductor and as a fuel cell membrane.

Con: The data indicate the membrane has limited stability (soft and water soluble) resulting in low performance (low open circuit voltage OCV, 0.45V, and low power, 2mW/cm2) in a fuel cell probably due to reactant crossover or/and possibly poisoning of Pt from decomposition of organics in this PEM.

What’s next?

16

1. With azole directly bound to phenoxy ring.i. hexakis(4-cyanophenoxy)cyclotriphosphazeneii. hexakis(4-tetrazolylphenoxy)cyclotriphosphazeneiii. hexakis[4-(1,2,4-triazol-1-yl)phenoxy]cyclotriphosphazeneiv. hexakis[4-(imidazol-1-yl)phenoxy]cyclotriphosphazenev. poly[bis(4-cyanophenoxy)phosphazene]vi. poly[bis(4-tetrazolylphenoxy)phosphazene]vii. poly[bis(4-(1,2,4-triazol-1-yl)phenoxy)phosphazene]viii. poly[bis(4-(imidazol-1-yl)phenoxy)phosphazene]

2. With methylene units between the azole and the phenoxy ring.i. hexakis(4-(1H-imidazol-1-ylmethyl)phenoxy)cyclotriphospazene ii. hexakis(4-(1H-1,24-triazol-1-ylmethyl)phenoxy)cyclotriphosphazene 4-(1H-1,24-triazol-1-ylmethyl)phenoliii. hexakis(4-(1H-5-methyltetrazol-1-ylmethyl)phenoxy)cyclotriphosphazene 4-(1H-5-methyltetrazol-1-ylmethyl)phenoliv. [ N3P3(p-O-C6H4-CH2C3N2Cl2)6]v. [ N3P3(p-O-C6H4-CH2OH)6 ] vi. [ N3P3(p-O-C6H4-CHO)6 ]vii. [ N3P3(p-O-C6H4-CH2OH)6 ]viii. 4-(1H-1,2,4-Triazol-1-ylmethyl)phenolix. [ N3P3(p-O-C6H4-CH2Br)6]

N P

O

O

nN P

Cl

Cln

N

N N

N

H

N

NN

N

H

1.vi.

1.ii. Syntheses of substituted poly phenoxy phosphazenehave been developed to give low equivalent weight frameworks with a variety (imidazole, triazole and tetrazole) of pendant bases with a wide range of pK suitable for reacting with a variety of acids for optimizing proton conductivity of salt membranes.

Technical Accomplishments: Poly-phenoxy-phosphazenes

17

1:1 Triflic acid:water (2mL); WE: Pt; CE: Pt; RE: RHE; Ar purged; T = 25C

-0.3

-0.2

-0.1

0

0.1

0.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Potential (V) vs RHE

Cur

rent

Den

sity

(mA

/cm

2 )

200mV/sec 100mV/sec 50mV/sec 20mV/sec

1:1 Triflic acid:water (2mL) + triazolyl phenoxy trimer (1.2mg); WE: Pt; CE: Pt; RE: RHE; Ar purged; T = 25C

-0.3

-0.2

-0.1

0

0.1

0.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Potential (V) vs RHE

Cur

rent

Den

sity

(mA

/cm

2 )

200mV/sec 100mV/sec 50mV/sec 20mV/sec

Technical Accomplishments: Pt voltammetry under Ar, Stability Test

Observations: Cyclic Phosphazene 1.ii. adsorbs but does not decompose. Conclusion: Phenoxyphosphazene is suitable as a building block for a fuel cell polymer electrolyte membrane (PEM).

18

1:1 Triflic acid:water (2mL); WE: Pt; CE: Pt; RE: RHE; O2 purged; T = 25C

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Potential (V) vs RHE

Cur

rent

Den

sity

(mA

/cm

2 )

200mV/sec 100mV/sec 50mV/sec 20mV/sec

1:1 Triflic acid:water (2mL) + triazolyl phenoxy trimer (1.2mg);

WE: Pt; CE: Pt; RE: RHE; O2 purged; T = 25C

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Potential (V) vs RHE

Cur

rent

Den

sity

(mA

/cm

2 )

200mV/sec 100mV/sec 50mV/sec 20mV/sec

Technical Accomplishments: Pt voltammetry under O2, Activity Test

Observations: Cyclic Phosphazene 1.ii. adsorbs but does not decompose even in the presence of Pt and O2. Adsorption diminishes O2 reduction by ~ factor of 6. NOT a problem with phosphazene covalently immobilized in polymer.Conclusion: Phenyoxyphosphazene is suitable as a building block for a fuel cell polymer electrolyte membrane (PEM).

19

Technical Accomplishments: NMR

D = 3.6 x 10-11 m2/s

PFG-Spin Echo

PFG-Stimulated Echo

I = I0 exp −Dγ 2g2δ2(Δ −δ3)

⎡ ⎣ ⎢

⎤ ⎦ ⎥

CH3

CH2NH3

+

Neat Ethylammonium nitrate (EAN)

PFG Self-Diffusion Measurements on ILs

PFG spin echo D measurements are limited by T2 relaxationPFG stimulated echo is limited by T1 relaxation (in viscous ionic liquids T1>>T2)Stimulated echo D measurements on EAN resulted in identical D for all 1H sites

20

Technical Accomplishments: NMR19F NMR T1 Relaxation Enhancement to Probe O2 Presence in ILs

Triethylammonium bis (perfluoroethylsulfonyl) imide (TEABETi)

CF3

CF2

CF3 T1 = 600 ms, Freeze/Pump/Thawed 5x (no O2)

CF3 T1 = 320 ms, as synthesized (O2 present)

Because O2 is paramagnetic it will greatly impact NMR T1 relaxation

NMR T1 measurements can be used to determine which ionic liquids and which sites in those ionic liquids are influenced by O2 presence

TEABETi (10 F) showed a significant change in T1 with O2 present compared to TEATFSi (6 F)

This is attributed to the larger number of F in TEABETi

21

-24

-23.5

-23

-22.5

-22

-21.5

0.0026 0.0027 0.0028 0.0029 0.003 0.0031 0.0032

ln(1H Diffusivity (m2/s))ln(19F Diffusivity (m2/s))

y = -14.285 - 2812.8x R= 0.99909

y = -13.823 - 3129x R= 0.9996

ln(1 H

, 19F

diff

usiv

ity (m

2 /s))

1/Temperature (1/K)

Ea for transport propertiesH+ diffusion: 23.4 +/- 1.2 kJ/molF diffusion: 26.0 +/- 1.3 kJ/mol Ion Conduction: 22.1 +/- 1.1 kJ/mol Viscosity: 26.9 +/- 1.3 kJ/mol

Technical Accomplishments: NMRActivation energies, Ea, for all transport properties in triflate monohydrate, a

model pIL

•That proton has 1.5x’s higher diffusivity and lower Ea than F over the range of temperatures indicates H+ hopping can occur in a pIL.

•Similar studies underway for another pIL, fluoropyridinium triflate.

0

5 10-11

1 10-10

1.5 10-10

2 10-10

2.5 10-10

3 10-10

3.5 10-10

4 10-10

30 40 50 60 70 80 90 100 110 120

1H Diffusivity (m2/s)19F Diffusivity (m2/s)

1 H, 19

F D

iffus

ivity

(m2 /s

)

Temperature (°C)

Triflate monohydrate

22

Solution voltammetry of ferrocene in 4 ionic liquids Ar purged, T = 25 oC, SR = 100mV/s, WE: Pt, CE: Pt, RE: RHE

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7

Potential (V) vs. RHE

Cur

rent

(mA

)

EAN TEATFAc TEATf DEMATf

Technical Accomplishments: solution voltammetry of ferroceneDetermining proton activity in protic ionic liquids

E1/2 (ferrocene) vs RHE = 0.4, corresponds to a proton activity of 1 (1M in H+, or pH = 0 )E1/2 (ferrocene) vs RHE > 0.4, corresponds to a proton activity < 1 (more basic, pH > 0) E1/2 (ferrocene) vs RHE < 0.4, corresponds to a proton activity > 1 (more acidic, pH < 0).

The acidity function H can be defined by

-HGF = log a H+ + log (fFc/fFc+)

• GF refers to the electrodes used (Glass, Ferrocene) • f is the activity coefficient• a H+ is the activity of proton • shift of 56 mV is ~ 1 pH unit

From: “Acidity Functions of Aqueous Fluorinated Acid Solutions”. R. Cox, U. Krull, M. Thompson, K. Yates, Anal. Chimica Acta, 106 (1979) 51-57

a H+ = 1Fc/Fc+

0.4 V0 V

NHEa H+ = 10-8

alkaline

-0.44 V

0.88 V

23

Future WorkContinue to make and characterize 2 types of PIL-concept based PEM:

i. ionic liquid (IL) filled PEMs consisting of: ia. bi-phasic porous matrices filled with leachable ionic liquids ib. leachable ionic liquids sorbed in polymers, and

ii. non-leachable PEMs consisting of novel polymers and polymer blends with no plasticizers which allow all acid and base moieties to be immobilized by covalent and electrostatic binding.

a. Polyphosphazenes: low EW, heat-melt formed and water insoluble membranes.

Echem NMR and FTIR • Continue pulse field gradient for H+ mobility of new materials• NMR Imaging under H+ current (“NMR Hittorf”) experiment to investigate

distribution of species during proton conduction

Voltammetry of Pt and other metal electrodes in PILs to investigate:• Pt-oxide formation• Adsorption of pIL on Pt• Check for O2 reduction activity on Pt and non-Pt catalysts • Measure potential shift versus standard potential of “solvent shielded”

metal complexes (e.g., for ferrocene, Eo’ = 0.4V vs NHE) in a pIL to determine proton activity in pIL and its component acid and base. Gives a reliable prediction of pK and rational basis for finding ΔpK = 14.

24

SummaryRelevance: Help develop energy efficient fuel cell using protic salt electrolyte membranes

Approach: Protic salt membrane electrolytes are non-aqueous proton conductors• No bulk water means little or no Pt-OH on surface, expect:

– Lower overpotential for oxygen reduction and higher cell efficiency– Lower corrosion and Pt particle growth– Simplified Fuel Cell: no humidifier, smaller radiator

Technical accomplishments: Status of Protic Ionic Liquids (PILs)• High Conductivity and Fuel Cell Activity Found in some PILs• Stable PILs found • Need to combine high activity and stability• Demonstrated proton conductivity and fuel cell performance in leachable

and non-leachable membranes• Synthesized new poly-phosphazene polymer with pendant nitrogen heterocycles

Proposed Future Work: • Heat-melt cast poly-phosphazene polymer with pendant nitrogen hetero cycles

into a water insoluble membrane and then react with triflic (and other) acids to form protic salt membranes. Test H+-conductivity and fuel cell performance

• Continue NMR characterization of proton mobility.• Finish NMR imaging of membranes under proton current.