Advanced fluorinated materials for low and high temperature PEM water
electrolyser E. Moukheiber, D. Jones, N. Van Dijk, A. Aricò and L. Merlo
Outline
2
1. Electrohypem: project overview2. Development of innovative PFSA membranes for
PEMWE application :- Short side chain Aquivion® PFSA with high EW- Aquivion ® PFSA composite membranes
3. Conclusion
Enhanced performance and cost-effective materials for long-term operation of PEM water electrolysers coupled to renewable power
sources
• Start date and end date : 01-07-2012 / 30-06-2015
• Consortium :
• Aim : Develop cost-effective components for proton conducting membrane electrolysers with enhanced activity and stability in order to reduce stack costs and to improve efficiency, performance and durability.
3
Electrohypem : Project overview
4
• Membrane activity
Development of short side chain PFSA, hydrocarbon membranes and theirinorganic/organic composite derivatives
• Membrane targets
High conductivity High gas barrier properties (under pressure) Maintain performance at high temperature operation (up to 150⁰C) High mechanical resistance at pressurized operation
Electrohypem : Project overview
Outline
5
1. Electrohypem: project overview2. Development of innovative PFSA membranes for
PEMWE application :- Short side chain Aquivion® PFSA with high EW- Aquivion ® PFSA composite membranes
3. Conclusion
6
Aquivion® PFSA free radical polymerization scheme:
CF2=CF2
(TFE)
O
CF2
SO2F
CF2
CF2=CF
(SFVE)
O
CF2
SO3H
CF2
(CF2CF )h (CF2CF2 )k
Commonly known as the Short Side Chain (SSC) ionomer
+
+ hydrolysis
The ratio h / k defines the composition of the ionomer, usually described bythe Equivalent Weight = # of grams to have 1 mole of –SO3H groups
SSC Aquivion® PFSA membranes with high EW
7
Different equivalent weights determine different polymer properties:
-—―—―—―—―—-—
-
—
-
Different crystallizable portion
-—―—―—―—―—-
- -
EW crystallinity
hydration swelling
——
SSC Aquivion® PFSA membranes with high EW
8
0
1
2
3
4
5
600 800 1000 1200 1400EW (g/mol)
Hea
t of f
usio
n (c
al/g
)
Membrane Hydration (100°C)
0
20
40
60
80
100
120
140
500 700 900 1100 1300 1500Equivalent Weight (g/eq)
Hyd
ratio
n %
Aquivion extruded membranes
ImprovedBaseline ImprovedBaseline
Expected advantage : higher mechanical resilience given by higher crystallinity and lower hydration (=higher resistance to pressurized operations in liquid water). Higher gas barrier properties (=lower crossover)
SSC Aquivion® PFSA membranes with high EW
Developement of new brand E100-xxS (EW=1000 g/mol):
9
T=80⁰C 1 mg/cm2 IrO2 on TiO20,5 mg Pt (Pt on C)
0
0,2
0,4
0,6
0,05 0,15 0,25 0,35
‐Z" / oh
m.cm
2
Z'/ ohm.cm2
SSC Aquivion® PFSA membranes with high EW
The performances are dependent on membrane area resistance. Some Aquivion® grades behave better than the state of art. Main advantages?
Selected membrane E100-09S :
46 mΩ.cm2 @ 95⁰C
26 mΩ.cm2 estimated at 140⁰C
Selected membrane E100-09S:
46 mΩ.cm2 at 95°C
26 mΩ.cm2 estimated at 140°C
Single cell performance
@ 1,5 V
*216th ECS Meeting, Abstract #830, © The Electrochemical Society Electrochemical Measurement of O2 PermeationRate through Polymer Electrolyte Membranes. Jingxin Zhang, Ruichun Jiang, Wenbin Gu, and Hubert Gasteiger
H2 and O2 Crossover
00,10,20,30,40,5
E100-05S E100-09S E100-18S N115
H2
cros
sove
r [m
A/c
m2 ]
00,81,62,43,2
4
E100-05S E100-09S E100-18S N115
O2
cros
sove
r [m
A/c
m2 ] T40°C, 1bar
T95°C, 2,9 bar
Pt/C (Cathode), IrO2 (anode)*
SSC Aquivion® PFSA membranes with high EW
10
Thin Aquivion membranes presented better permeationproperties than the state of art. Why?
Selected membrane E100-09S:
0.2 (mA/cm2) @ 1 bar, 80°C T=80⁰C, Pt/C electrodes,
Fixed Gas Flow: 800 Sccm N2 ‐250 Sccm H2 / 0 barG N2 /H2
11
Differencial pressure testing system ∆P 15bars + Hyoptima
sensor (palladium film) to detect H2 in exhaust O2 stream.
H2 and O2 Crossover
SSC Aquivion® PFSA membranes with high EW
Similar EW but higher crystallinity for SSC
Selected membrane E100-09S:
1.51 % H2 in O2 (15 bar ∆P, 55°C) < 2% ( Project target)
11
SSC
LSC
12
Aquivion® PFSA composite membranes
Why ePTFE? - Chemical and thermal resistance
- Compatibility with PFSA material
- Nodes-fibrils structure that guarantees very high vacuum degree (80 to 90 % vaccum)
12
ePTFE structure ePTFE reinforced membrane
Development of ePTFE reinforced R95-04S (EW=950 g/mol, 50µm):
R95-04S (50µm) Vs E100-09S (90µm):
52 mΩ.cm2 Vs 46 mΩ.cm2 at 95°C
13
Aquivion® PFSA composite membranes
13
0
20
40
60
80
0 50 100 150 200 250 300St
ress
, (M
Pa)
Strain, (%)
Machine direction (MD)
E100-05SE100-09SE100-18SR95-04S
0
20
40
60
80
0 50 100 150 200 250 300
Stre
ss,
(MPa
)
Strain, (%)
Transversal direction (TD)
Development of ePTFE reinforced R95-04S (EW=950 g/mol, 50µm):
Improved mechanical properties for R95-04S : higher young modulus and stress at break
Tensile tests 23⁰C, 50% RH ASTM D638
MEA conductivity from 90⁰C to 150⁰C measured and stability (24hours) at 150⁰C demonstrated. what about ePTFE effect on permeation?
1414
Aquivion® PFSA composite membranes
Development of ePTFE reinforced R95-04S (EW=950 g/mol, 50µm):
Aquivion® PFSA composite membranes
15
00,10,20,30,40,5
E100-05S E100-09S E100-18S N115 R95-04S
H2
cros
sove
r [m
A/c
m2 ]
00,81,62,43,2
4
E100-05S E100-09S E100-18S N115 R95-04S
O2
cros
sove
r [m
A/c
m2 ] T40°C, 1bar
T95°C, 2,9 bar
The presence of the ePTFE does not help substantially in permeability reduction. inorganic fillers or hydrogenated supports?
Development of ePTFE reinforced R95-04S (EW=950 g/mol, 50µm):
Pt/C (Cathode), IrO2 (anode)*T=80⁰C, Pt/C electrodes,
Fixed Gas Flow: 800 Sccm N2 ‐250 Sccm H2 / 0 barG N2 /H2
*216th ECS Meeting, Abstract #830, © The Electrochemical Society Electrochemical Measurement of O2 PermeationRate through Polymer Electrolyte Membranes. Jingxin Zhang, Ruichun Jiang, Wenbin Gu, and Hubert Gasteiger
<1.8 V @ 2 A cm-²reached at 80 °C
<1.6 V @ 1 A cm-²reached at 80 °C
1.55 V at 140 °C
Composite membrane of Aquivion and electrospun polysulfone nanofibre mats
0 500 1000 1500 2000
1400
1600
1800
80oC 120oC 140oC
Cell
Volt
age
/ m
V
Curent density / mA cm-2
Aquivion® PFSA composite membranes
16
Development of PSU reinforced membranes
Outline
17
1. Electrohypem: project overview2. Development of innovative PFSA membranes for
PEMWE application :- Short side chain Aquivion® PFSA with high EW- Composite PFSA membranes
3. Conclusion
Conclusion
18
• Short side Chain Aquivion® ionomer with high EW allowed the use of thin membrane with good proton conductivity while maintaining low H2& O2 crossover
• Thin ePTFE composite PFSA membranes (50µm) showed improved mechanical properties and thermal stability however..
• ePTFE support wasn’t effective H2 & O2 crossover reduction. other solutions are under investigation such as ionorganic fillers or electrospun hydrogenated supports (PSU)
• Electrohypem’s selected membrane for scale up E100-09S will bevalidated in terms of performance and stability in an electrolyzer stackat ITM with nominal hydrogen rate production capacity of 1 Nm3 h-1.
19
The authors acknowledge the financial support of the EU through the FCH JU Electrohypem Project.
“The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2010-2013)
for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement Electrohypem n°300081.”
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