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2005 DOE Hydrogen Program Review
Advanced MEA’s for Enhanced Operating Conditions, Amenable to High
Volume Manufacture
Mark K. Debe 3M Company May 23, 2005
Project ID # FC3
This presentation does not contain any proprietary or confidential information
Overview Timeline Barriers
• Project start 1/1/02 O. Stack Material & Mfg Cost
• Project end 12/31/05 P. Durability
• 80% complete Q. Electrode Performance R. Thermal & Water Mgmt
Budget Targets • Total Project funding
$7 million DOE $2 million contractor share
• Cost: $35/kW, • Durability: > 5000 hrs, • Precious metal loading: 0.2 g/
• Received in FY04: $2 million rated kW
• Projected funding for FY05: $1.8 For fuel cell stack system for 2010 from HFCIT MultiYear Plan
million Partners
• Case Western Reserve Univ. • University of Miami • Colorado School of Mines • University of Minnesota • Dalhousie University • VAIREX Corporation • University of Illinois • Collaboration with LBNL and BNL
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 2
Objectives
Overall Contract Objective Development of high performance, high durability, lower cost membrane electrode assemblies (MEA’s) qualified to meet demanding system operating conditions of higher temperature, little or no humidification, while using less precious metal catalyst.
Past Year Objectives a) Tasks 1 & 3: Demonstrate PFSA based MEA capability with:
adequate membrane and catalyst performance to meet 0.2g Pt/kW , durability to potentially operate for 5000 hours in the range of 85 < T < ~ 120ºC under subsaturated inlet conditions with startstop cycling, and pilotscale production levels.
b) Task 2: Development and characterization of new proton conducting electrolytes and incorporation into membranes for operation at T > 120ºC, based on nonaqueous proton conduction mechanisms.
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 3
Approach Tasks 1 and 3: 85 < T < 120oC MEA by rollgood processes a) Develop 3M PFSA membranes for operation at 85 < T < ~ 120ºC, with
enhanced durability operating on low humidification and pilot scale production capability.
b) Developed advanced 3M NanoStructured Thin Film (NSTF) catalysts with high performance at ultralow Pt loadings having enhanced durability for operation over 85 < T < 120ºC with startstop cycling, using pilot scale production capability.
c) Match the 3M PEM and 3M NSTF catalyst for optimum performance, durability
d) Advance pilot scale process development for rollgood catalyst coated membrane (CCM) fabrication of the NSTF catalysts and 3M PEM from c).
e) Optimize the MEA GDL for dry operation with the CCM from d).
Task 2: High temperature electrolytes (T > 120oC): a) Develop membranes comprising polymers blended with stable nonvolatile
3M superacids. b) Investigate new heteropolyacid additives for proton transport under hotter,
drier conditions and methods for stabilizing in presence of water.
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 4
Technical Accomplishments Task 1, Task 3: 85 < T < 120oC MEA by rollgood processes New 3M PEM shows greater than 15x increase in lifetime under 90/70/70oC load
cycling accelerated tests, compared to standard PFSA membrane. 3M PEM shown to have higher conductivity at lower waterpersulfonate group. New 3M PEM maintains 2530 mS/cm conductivity at 120oC and 80oC dewpoint
Over 1000 ft of 3M PEM coated at pilot scale. 3M NanoStructured Thin Film catalysts achieved 0.22 gPt/kW at 100kPA with
0.12mgPt/cm2MEA; and < 50 mV of mass transport overpotential at 2 A/cm2. 3M NSTF/3M PEM MEA demonstrated over 1000 hour lifetime at 120oC
3M NSTFternary catalysts produce 75x less F than Pt/carbon dispersed catalysts at 120oC with same PEM and GDL.
3M NSTF catalysts are ~ 80x more resistant to loss of ECSA via Pt dissolution by CV cycling between 0.6 – 1.2 volts, than Pt/carbon dispersed catalysts.
Task 2 : T > 120oC electrolytes Performance in fuel cell under H2/air at 110oC better than PBI/H3PO4 with
catalyst loading of only 0.4/0.4 mg/cm2 Pt/Pt (3M acid more ORR compatible). Pulse field gradient spin echodiffusion measurements show lower activation
barriers for H+ transport of new heteropolyacids, and higher maximum Temps. Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 53
Technical Accomplishments – 3M PEM Definition The new 3M ionomer has a slightly shorter side chain than standard PFSA membrane ionomer without the pendant CF3 group:
Gives: higher degree of crystallinity, higher modulus, higher Tg at a given equivalent weight (EW).
Allows: lower EW membranes with higher conductivity, improved mechanical properties and durability under hot, dry conditions.
enhanced oxidative stability in Fenton’s test
(CF2CF)n(CF2CF2) (CF2CF)n(CF2CF2)m m
OCF 2CFOCF 2CF2 OCF2CF2CF2CF2
CF3 SO3H SO3H
Standard PFSA New 3M Polymer
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 6
6
8
10
12
14
Technical Accomplishments – 3M PEM Performance Comparison of conductivity at 30°C vs. hydration state (λ) of
1000 EW 3M membrane and standard 1100 EW PFSA membrane
3M Membrane (1000 ew, cast)
Std. PFSA (1100 EW, extruded)
0.14
λ (W
ater
Mol
ecul
es p
er S
ulfo
nate
Gro
up)
3M Membrane
Std. PFSA
0.12
0.1
σ (S
/cm
)
0.08
0.06
0.04 4
0.02 2
00
0 0.2 0.4 0.6 0.8 1 0 5 10 15 20 25
(% RH) λ (Water Molecules per Sulfonate Group)
3M membrane exhibits lower water Conductivity of the 3M membrane uptake for the same water activity increases more rapidly with number of compared to the standard PFSA water molecules per sulfonate group than membrane. standard membrane. This should allow
T. Zawodzinski et al., CWRU drier operation of the MEA.
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 7
Technical Accomplishments – 3M PEM Performance
3M membranes with multiple EW’s have been fabricated and evaluated.
• Conductivity vs. temperature for EW ionomers in 730 – 980 EW range. • The lowest EW ionomer tested so far, 730 EW, shows a conductivity
of about 2530 mS/cm at 120˚ C, 80˚ C DP, very dry conditions.
Proton Conductivity at 80C Dew point
1.00 AC 4point probe measurement, at ambient
3M PFSA 730 EW 3M PFSA 830 EW 3M PFSA 900 EW 3M PFSA 980 EW
Con
duct
ivity
, S/c
m
pressure. 0.10
0.01 70 80 90 100 110 120
Temp (˚C)
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 8
130
Technical Accomplishments – 3M PEM Durability
0.460 with lower EW under hot, 0.440 dry conditions.
• Lifetime defined as when 0.420
OCV drops below 800mV. 0.400
Lifetime and performance vs. EW under load cycling. /cm2V at 0.5A
3M 1,000 EW 3M 900 EW 3M 800 EW 3M 700EW
• No statistically significant Normalized lifetime 5 samples each 200lifetime difference between 180
700 to 1,000 EW 160
0.540 • Test run at 90˚C, 28% RH, 0.520 load cycles between OCV 0.500 and 0.5 A/cm2.
• Performance increases
Nor
mal
ized
Life
time
Vo
lts
0.480
membranes in this test. 140
120
• All MEA’s tested with 100
dispersed Pt/C ink 80
60electrodes with 0.4/0.4 mg 40
Pt / cm2. 20
0 3M 1,000 EW 3M 900 EW 3M 800 EW 3M 700EW
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 9
Performance and lifetime during accelerated durability testing
Technical Accomplishments – 3M PEM Durability
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 10
00.10.20.30.40.50.60.70.80.9
1
0 0.2 0.4 0.6 0.8 1 1.2
Current Density
Volta
ge
0.060.070.080.090.10.110.120.130.14
mO
hms
cm2
StartAfter 2800 hoursAfter 3500 hoursResistance Start Resistance 2800 hoursResistance 3500 hours
3500>50017.078.1
2800>5003.4102.9
0>5004.2178.3
Testing Time
Short Resistance
(OHMCM2)
H2Crossover (mA/cm2)
Pt/Carbon SEF
(M2/M2)
• 3M membrane with additives shows >15 X increase in lifetime (4 cell average ~ 4100 hrs) vs. 50 micron extruded standard PFSA membrane under load cycling tests at 90oC, w/70oC dewpoints.• Accelerated durability testing was stopped periodically and sample was tested at 70˚C 100%RH. No increase in crossover or shorting was detected before 3500 hours. IR change of PEM was minimal. Most performance loss due to loss of catalyst surface area or mass transport.
3
[111]
1 nm1 nm
Technical Accomplishments – NSTF Fundamentals
Relating fundamental catalyst morphology to enhanced properties. Scanning Transmission Surface free energy of crystallites
3M Scanning Electron Microscopy images are minimized by truncating a [111] Electron Micrographs from U. of Illinois faceted pyramid with a [100] top.
[100]
10 nm10 nm
1 nm1 nm
a
b
Experimentally measured values of a ~ 2nm, b~ 6nm or a/b=1/3.
Calculated energy minimized when r = a/b ~ 0.33.
“Whiskerettes” growing on the sides of the larger whiskers as pyramidal crystallites with fcc(111) side facets and fcc(100) truncated top. (L. Gancs, A. Wieckowski)
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 263 11
Technical Accomplishments – NSTF Catalyst Devel. PtAxBy NSTF ternary catalyst development
113 different compositions/structures fabricated, all by rollgood process. Specific activities in 50 cm2 cells depend on a structure factor, and composition Best performances obtained for most durable catalysts (see later slides) and their performance is insensitive to structure factor, implying a large process window
Best PtCD NSTF ternary Summary of NSTF Ternary Cathode loading: 0.1 mgPt/cm2 Catalyst Specific Activities Anode loading: 0.15 mg/cm2
Spe
cific
Act
ivity
(A/c
m2
Pure Pt 0
1
0 1
(
3
H2/air
PDS(0.85,0.25,0.048,10s/pt)
Cel
l vol
tage
(V)
rea
l)
0.000
0.010
0.020
0.030
PtCx2Dy2 PtCx4Dy4 PtAx2Dy2 PtAx4Dy4 PtDx1By1 PtAx2By2 PtAx3By3 PtCx1By1 PtCx2By2
0.2
0.4
0.6
0.8
0.2 0.4 0.6 0.8 1.2 1.4
Structure Factor S.F.) = 1.2
S.F.=2.1 S. F. =
75C cell, 0/0 psig inlet,
CF800/1800 sccm, Humidity: 66%/45%
0.5 1 1.5 2 2.5 3
NSTF Structure Factor J (A/cm2)
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 12
0
0.4
0.6
0.8
1.0
Technical Accomplishments – NSTF Catalyst Loadings NSTF Catalysts with Ultralow Pt Loading Continue to Improve
• Little effect of anode loading over range of 0.05 to 0.2 mg Pt/cm2 above 0.6 V in MEA’s having PtC Dy ternaries (0.1mg Pt/cm2 ) on the cathode.x
• 3M record performance achieved by better matching NSTF ternary catalyst and whisker support size and density, in MEA’s having 0.060 mgPt/cm2 on A/C.
NSTF MEA (3M PEM and GDL) Performances with Different Anode Pt Loading (.05 to 0.2 mg Pt/cm2)
Cathode: PtAB ternary w/0.1 mg Pt/cm20.12 mg Pt/cm2 total per MEA
V (v
olts
)
2 each
75o2
2
/) ( )
0.4
0.5
0.6
NSTF Loading: A/C = 0.060 mgPt/cm
C cell. Ambient Pressure, H /Air CF: 800/1800 sccm, 50 cm Humidity: 66% 45% PDS(0.85,0.25,0.048,10s , PSS 0.4V,5min3MPEM 1000 EW, 30 microns
0.8
0.7
, 1
0.9 / /45%
/ /72% / /72% / /72%
/ 2/air / l
i/ )
5 min)
FC9321495, 0.15 mg Pt cm2, 66%FC9497483, 0.2 mg Pt cm2, 72%FC9498572, 0.1 mg Pt cm2, 72%FC9499318, 0.05 mg Pt cm2, 72%
75C cell, 00 psig inlet, HCF8001800 sccm, counterfow. Humdity: as stated PDS(0.85,0.25,0.048,10spt , PSS(0.4V, C
ell V
olta
ge (V
)
0.3
0.2
0.1
0
2)J (A/cm0.0 0.2 0.4 0.6 0.8 1.0 1.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4
FC10206graph1 J (A/cm2)
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 13
0.0
0.2
Technical Accomplishments – NSTF electrode Mass transport overpotential (MTO) correlated to NSTF electrode thickness
MT
Ove
rPot
entia
l at 2
A/c
m2 (m
V)
0
20
40
60
80
2
600 800 1000
2 possible for Pt ternary constructions w/ 0.1mgPt/cm2
thicknesses from known loadings
porosity is ~ 75%, filled with ionomer.
HFR
45 mV
TcelloC
H2 i /2.5 H2/
i
70 mV/decade
E(V
) and
Ei
(V)
100
120
140
160
180
200
FC8565
FC8749
FC8876
FC8752
MT
Ove
rPot
entia
l at 2
A/c
m (m
V)
1200 1400 Catalyst Volume/Unit Area (Angstroms)
• MTO < 50 mV at 2A/cm
• SEM thicknesses agree with calculated
• Allows determination that electrode
0.0
0.2
0.4
0.6
0.8
1.0
IRcorrected
Measured
Not Xover corrected
= 80/air Sto ch = 2.0air pressure = 30 psig
Humid ty: 60%/60% RH
reference line
rfre
e
200
180
160 . 140
120
100
80
60
40
20
0
FC8565graph 16 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.1 CorrMaa Xfer Loss vs Cat Vol graph 4 i (A/cm2)
1 Electrode Layer Thickness by SEM (µm)
3 Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 14
0 4 8 12 16 20 24 280
20
40
60
80
100
120
140
160
180
Const Volt. = 0.4 VT = 90oCA/C RH = 100% A/C P = 200kPaA/C FR = 800/1800 SCCMSame 3MPEM and 3MGDL
PtCD
PtAD
FC9xxx F Release Summary Graph 19
Cat
hode
F R
elea
se (n
g/m
in5
0cm
2 )
NSTF Ternary Structure Factor
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 153
• F release rates (by IC) measured for a series of PtAxDy and PtCxDyNSTF ternary catalysts under a fixed protocol.
• F release( peroxide generation) rate is a function of NSTF construction.
• NSTF catalysts do not contain carbon, so any peroxides generated on carbon of carbonsupported dispersed Pt is eliminated.
• NSTF catalysts have 5x higher specific activity than Pt/Carbon, implying less H2O2production
NSTF catalysts and H2O2 production and F release ratesTechnical Accomplishments – NSTF MEA Durability
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 163
• Same 3M PEM• Same 3M GDL
Technical Accomplishments – NSTF Durability120oC Stress tests of MEA and catalyst surface area durability CJ = 0.4 A/cm2, 100 cm2 cell, 300kPa H2/air, A/C inlet % RH = 61%/84% 18 – 66 hrs at 120oC, water collected for F release, then 6 hrs at 75oC for
ECSA, H2 crossover, short resistance measurements. Cycle repeated.Recent results comparing NSTF and Dispersed Pt/Carbon (Neat 3M PEM) reversible impurity adsorption during each 18 hr cycle (cleans up during CV) NSTF MEA lifetimes 1520 x longer than dispersed Pt/Carbon catalyst MEA. MEA lifetime scales with F release. NSTF F release ~ 75 x less than Pt/C.
Lifetime versus F- ion release rate for NSTF and Dispersed Pt/C MEA’sVoltage vs time for NSTF and Pt/C MEA’s at 120oC
0 150 300 450 600 750 900 1050 1200 1350 1500 1650 18000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Same 3MPEM and 3MGDL on all MEA's.
Pt/Carbon #2: 0.2 mg/cm2
Pt/Carbon #1: 0.4 mg/cm2
NSTF PtCx2Dy2, 0.1 mg/cm2
Total time on test = ~1825 hoursTime at 120°C = ~1082 hours
Stress Conditions: 120°C Cell, Water Balance ~1.1, 30psig, CF723/CF1330, H2/Air
V at
0.4
J (A
/cm
2 )
FC9824Menomoniegraph4Time (hours)0.1 1
0
200
400
600
800
1000
1200
# 2# 1
Pt/CarbonNSTF PtAx1Dy1
NSTF PtCx2Dy2
NSTF PtCx2Dy2(Still Operating 04/20/05)
FC9824Menomoniegraph 5
Life
time
Hou
rs a
t 120
o C
F Ion Release Rate (µg/min)
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 173
0 5 10 15 20 25 30 35 40 45 500.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Total F Release (µg/min)
1824 hourson Station
576 hourson Station
1082 hoursat 120°C
982 hourson Station
Slope of line = 0.00314 V/Stress Test Number = 0.077 mV/Hour on Station
Stress Test conditons: 120C, water balance ~1.1, 30psig
FC9824Menomoniegraph3
Pea
k Vo
ltage
Afte
r Eac
h R
esta
rt (V
)
Stress Test Number
NSTF peak voltage and F- ion release rateduring 1825 hr test, 1080 hrs at 120oC.
To – date : Best NSTF MEA = NSTF ternary PtCx2Dy2 (0.1 mg Pt/cm2)
+ Neat 3M PEM (no additives, or edge protection tested yet)+ 3M GDL
Cathode and anode surface area losses stabilize to ~ 40% and 50% of initial value. Shorting and H2 crossover values remain stable and low until end of life. F ion release rate at 120oC remains < 24 nanogram / hr cm2 over 1800 hours. Decay rate of peak voltage is ~ 77 microvolts/hr over 1800 hr lifetime.
Technical Accomplishments – NSTF Durability
0 200 400 600 800 1000 1200 1400 1600 18000
2
4
6
8
10
12
14
16
18
20
FC9824menomoniegraph2
Anode ECSA Cathode ECSA Cathode H2 Crossover (mA/cm2, not measured with anode overpressure) Cathode Short Resistance (Kohmcm2, not measured with anode overpressure)
Stress Test conditons: 120C, water balance ~1.1, 30psig
EC
SA
, H2 C
ross
ove
r, S
hort
Res
ista
nce
Time (hour)
Surface areas, short resistances, and H2-cross-over of NSTF PtCD MEA at 120oC.
CV cycling stability of catalyst surface area as a function of temperature for one NSTF PtCD ternary versus Pt/Carbon catalysts.
CV cycling stability of catalyst surface area at 80oC for NSTF Pt and best NSTF ternary
versus Pt/C and Pt/graphitic carbon.
0 3000 6000 9000 12000 150000.01
0.1
1
CV cycling datagraph 13
Pt/Graph C(0.4 mg Pt/cm2)
Pt/Carbon (0.4 mg Pt/cm2)
Four NSTF Pt and PtAB ternary (0.10 mg Pt/cm2)
Nor
mal
ized
EC
SA
Number of CV Cycles at 80oC
20 mv/secA/C: H2/N2RH:100/100%
• Same 3M PEM• Same 3M GDL
• NSTF catalysts are much more resistant to loss of surface area from high voltage cycling than are dispersed Pt/Carbon or Pt/graphiticcarbon catalysts. • NSTF catalysts should be more robust against shut down/startup, and local H2
starvation. 70% of NSTF ECSA remains after 12,000 cycles to 1.2 volts at 80oC.
Technical Accomplishments – NSTF Durability
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 18
CV cycling measurements from 0.6 – 1.2 V test stability against Pt dissolution
0 3000 6000 9000 12000 150000.01
0.1
1
Pt/CNSTF90oC
NSTF85oC
NSTF75oC
NSTF75oC
NSTF 95oC
65oC
Pt/C80oC
Pt/C 95oC
CV cycling datagraph 14
Nor
mal
ized
EC
SA
Number of CV Cycles
• Same 3M PEM• Same 3M GDL
3
30 40 50 60 70 80 90 100 1100.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
90/0/0oC85/0/0oC
80/0/0oC
75/0/0oC
70/0/0oC
7090C cell0/0% Inlet RH
15/15psig H2/AirCS2/2
GSS(0.4, 120min)
HFR
(ohm
cm
2 )
Outlet RH (%)
Technical Accomplishments – Thermal Water Manag.Dry operation –GDL Screening and Optimization• Operation with totally dry inlet H2/air is possible at 75oC and 200kPa with no loss
of performance for some GDL/NSTF combinations. (1000 EW 3M PEM)• Introducing some inlet RH allows operation at higher ToC.• Further optimization necessary for both hot dry and cold start.• All GDL’s are rollgood fabricated, like NSTF and 3MPEM.
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 193
Cell voltage operation at 15 psig and 0%/0% RH inlet humidification with varying temperature for different GDL’s.
30 40 50 60 70 80 90 100 1100.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
90/0/0oC
85/0/0oC 80/0/0oC
75/0/0oC 70/0/0oC
7090C cell0/0% Inlet RH
15/15psig H2/AirCS2/2
GSS(0.4, 120min)
Cel
l V (V
olts
) @ G
SS(0
.4)
Outlet RH (%)
High frequency impedance changes at 15 psig and 0%/0% RH inlet humidification for varying temperature (7090oC) with different GDL’s.
2 hrs stabilization time/point
Technical Accomplishments – Performance Targets
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 203
• NSTF Pt specific power density is < 0.3 gPt/kW for cell voltages < 0.70 Vfor conditions shown. Entitlement may be lower still due to:
- Opportunity to increase mass activity by optimizing support whisker- Opportunity to further reduce impedance of electrode and GDL
• NSTF catalyst based MEA’s with 3M PEM clearly show potential toreach 5000 hours of lifetime for 80oC < T < 120oC, due to:
- Enhanced stability and lower F- release rates of NSTF catalyst, - Enhanced stability, mechanical properties of 3M PEM
• Stable operation with totally dry input gases is possible under conditions near water balance –requires optimization of the GDL and further gains matching lower EW PEM to NSTF catalysts.
• All 3M PEM, NSTF catalyst, and GDL are currently fabricated using scalable, cost-effective, roll-good fabrication processes.
0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.850.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0.06mgPt/cm2 on cathode0.06mg Pt/cm2 on Anode.
100kPa H2/air, CF 800/1800sccm
0.10mgPt/cm2 on cathode0.05mg Pt/cm2 on Anode.300kPa H2/air, CS 2.0/2.5
DOE 2005 Targetat rated power
DOE 2010 Target
NSTF Pt-Specific Power Densities (gPt/kW)
FC8565 - graph 32
g-Pt
/ kW
Cell Voltage (V)
0.001
0.01
0.1
1
80 90 100 110 120 130
Temperature, C
Con
duct
ivity
S/c
m
Acid A Acid B Acid CPBI Phos acid 1:6
Technical Accomplishments – Electrolytes for T > 120oC
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 213
• Temp/RH dependence was significantly lower for polymer swollen with Acid A than with Acid B or C measured by AC impedance. Conductivity was measured with an 80˚C dew point.
• Polymer swollen with Acid C retained acid much better when immersed in water than PBI/H3PO4 as shown by pH versus time.
• Even though Acid C had lower conductivity, Fuel cell performance was higher, presumably due to better cathode kinetics.
H2/Air, 110/80/80, 0.4/0.4 mg/cm2 Pt/Pt
00.10.20.30.40.50.60.70.80.9
0 0.2 0.4 0.6A/cm2
V
Acid CMembranePBI Phos acid1:6
0
1
2
3
4
5
6
0.0 1.0 2.0 3.0 4.0 5.0 6.0Time (min.)
pH
Acid C membrane
PBI Phos acid 1:6
Technical Accomplishments – Electrolytes for T > 120oC
Advanced MEAs for Advanced Operating Conditions – 2005 DOE Hydrogen Program Review, May 23 – 26 223
Pulse Field Gradient Spin Echo –Diffusion Measurements
• Preliminary measurements on dry membranes
• Control Ea = 27.5 KJ mol1, Most HPA doped around 15 KJ mol1
0
2
4
6
8
10
12
0 20 40 60 80 100 120 140T (oC)
D x
107
cm
2s1
Control dryPFSA1% HPA Y dryPFSA5% HPA Y dry
SAXS• Two scattering domains:• hydrophilic <D> 1.7, d 3.1 nm – dry
<D> 3.8, d 5.1 nm – wet• hydrophobic <D> 8, d 14 nm – wet or dry• HPA – higher scattering intensity, larger
distribution of scattering domains and a Bragg peak corresponding to HPA crystallites
0
1
10
100
0.1 1 10q (nm1)
SA
XS
Inte
nsity
3M ionomer Dry
3M ionomer in H2O
3M ionomer+1%HPA X Dry
3M ionomer+1%HPA X in H2O
3M ionomer+5%HPA X Dry
3M ionomer+5%HPA X in H2O
A. Herring, Colorado School of Mines
Response to 2004 Reviewers’ Comments 1. “I have mixed reactions to 3M’s claims re: less fluoride generation by their
new membranes. Are these results because of mismanufacturing of Nafionbased MEA’s?”
* F release rates from new 3M PEM are well documented and correlate with much longer lifetimes under accelerated testing.
* 3M has sold over 200,000 MEA’s using Nafion based ionomers andhas optimized the manufacturing process.
* 3M’s NSTF catalysts can lower F rates even further with 3M PEM.
2. “Stay the course but do accelerate the outside collaborations with industry.” * 3M will introduce the new 3M PEM to selected customers 2nd quarter 2005, and NSTF ternary MEA’s to selected customers end of 2005.
3. “Conductivity and fuel cell polarization measurements should be extended down to 20oC, perhaps even down to –20oC.”
* Low temperature testing is outside the scope of the project and DOE targets for the contracted work.
* However, cold start and freeze tolerance are very important and are being studied at 3M.
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Future Work
Completion of Task 3: Advanced MEA Development for 85< T < 120oC: MEA pilot level scaleup and large area stack testing.
• M1 – downselection of final x/y values for PtCxDy ternary and loading • M2 – downselection of final 3MPEM properties for durability, rampup • M3 – downselection of final GDL for reduced IR loss and dry operation • M4 – CCM process transfer to new pilot scale equipment • M5 – Statistical validation of pilot scale rollgood fabricated CCM’s • M6 – MEA fabrication for designated stack testing (312 cm2) • M7 – Short stack testing (~ 35 kW) • M8 – Testing customized Vairex air management systems w/NSTF MEA.
Completion of Task 2: High Temp. Electrolytes for T > 120oC.
• Further characterization of polymer/acid combinations focused on membrane conductivity and stability.
• Moving to immobilized heteropolyacids for fuel cell testing.
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Publications & Presentations 1. “Dissolution of Fe and Ni in Combinatorially Sputtered Pt 1x Fe and Pt 1x Nix(0<x<1) Electrocatalysts,” A.x
Bonakdarpour, J. Wenzel, D. A. Stevens, S. Sheng, T. L. Monchesky, R. T. Atanasoski, A. K. Schmoeckel, G. D. Vernstrom, M. K. Debe and J. R. Dahn, presented at the First International Conference on Fuel Cell development and Deployment, March 710, 2004, Connecticut Global Fuel Cell Center, Stores, CT.
2. “Studies of Transition Metal Dissolution from Combinatorially Sputtered, NanoStructured Pt 1x Mx (M=Fe, Ni;0<x<1) Electrocatalysts for PEM Fuel Cells,” A. Bonakdarpour, J. Wenzel, D. A. Stevens, S. Sheng, T. L. Monchesky, R. Lobel, R. T. Atanasoski, A. K. Schmoeckel, G. D. Vernstrom, M. K. Debe and J. R. Dahn, J. Electrochemical Society, Vol. 152 (1), 2005, A61A72.
3. “Insitu Vibrational Spectroscopy with Fuel Cell Catalysts,” Andrzej Wieckowski, Lajos Gancs, Matthew McGovern, GuoQiang Lu, Radoslav Atanasoski, and Mark K. Debe, presented at the American Chemical Society meeting, Anaheim, CA, March 29April 2, 2004.
4. “Advanced MEA’s for Enhanced Operating Conditions,” 2004 DOE Hydrogen Fuel Cells and Infrastructure Technologies Annual Review, Philadelphia, PA, May 24-27,2004.
5. “Advanced MEA’s for Enhanced Operating Conditions,” submitted for 2004 Hydrogen Program Annual Report, July, 2004.
6. “NanoStructured Thin Film, Thin Layer Electrodes Optimized for PEM Fuel Cell Performance at High Current Density,” 2005 Fuel Cell Seminar, San Antonio, TX, Nov. 15, 2004.
7. “Corrosion of Transition Metals in Pt 1xMx (M=Fe, Ni, Mn) Proton Exchange Membrane Fuel Cell Electrocatalysts,” A. Bonakdarpour et al., presented at the Fall 2004 Electrochemical Society Meeting, Honolulu, HI, USA.
8. “64Channel Fuel Cell for Testing Sputtered Combinatorial Arrays of Oxygen Reduction Catalysts,“ D. A. Stevens et al., presented at the Fall 2004 Electrochemical Society Meeting, Honolulu, HI, USA.
9. “Combinatorial PEM Fuel Cell Studies of Binary Platinum Alloys,” D. A. Stevens et al., presented at the Fall 2004 Electrochemical Society Meeting, Honolulu, HI, USA.
10. “The Search for Higher Temperature Proton Conductors for the PEM Fuel Cell,” J. Woods Halley, Symposium on Fuel Cells, MRS Meeting, Boston, MA, December 1, 2004,
11. "The Development of New Membranes for PEM Fuel Cells", Steve Hamrock, Advances in Materials for Proton Exchange Membrane Fuel Cell Systems, Asilomar Conference Grounds, Pacific Grove, CA, February 21, 2005.
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Hydrogen Safety
The most significant hydrogen hazard associated with this project is:
• Accidental H2 release in cylinder closet leading to ignition from: H2 line or manifold breach Accident during replacement of cylinders
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Hydrogen Safety
Our approach to deal with this hazard is: • Design
Hydrogen cylinder closet and gas distribution system adhere to codes. Reduction in number of cylinders in the closet 2step regulators (less susceptible to failure and designed to fail closed) H2 sensors in all labs and cylinder closet, alarm system Automatic shutoff of H2 gas supply if sensors detect H2 release
• Procedures SOP’s for cylinder changing, alarm responses, test station operation Cylinder changing restricted to highly trained personnel Regular maintenance checks – sensors, leak check of valves etc.
• Installing H2 Generator (in noninhabited mechanical room) to significantly reduce total volume of H2 in facility
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