breaking the fuel cell cost barrier pt-free membrane fuel
TRANSCRIPT
Pt-Free Membrane Fuel Cells
Latest progress on
Alkaline Membrane Fuel Cells (AMFCs)
Dario R. Dekel; [email protected] +1 (828) 348 4444; +972 (54) 252 6370
Breaking the Fuel Cell Cost Barrier
CellEra CONFIDENTIAL
10th Israeli Advanced Power Sources Conference – Tel Aviv
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What is an AMFC ?
From “Alkaline membrane fuel cells”; Dario Dekel, In: Savinell R, Ota K, Kreysa G
(eds) Encyclopedia of applied electrochemistry: Springer reference (www.springer-
reference.com). Springer
Enhanced electrokinetics of
the ORR, allowing for the use
non-Pt catalysts
Extended range of
(available) stack materials
Wider choice of fuels in
addition to H2
AMFC stack structure
Replace acidic solid electrolyte with an alkaline solid electrolyte
3 From www.cellera-inc.com
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*From “Alkaline Membrane Fuel Cells: Membranes”. Dario R. Dekel;
In: Savinell R., Ota K., Kreysa G. (Ed.) Encyclopedia of Applied Electrochemistry:
SpringerReference (www.springerreference.com) (2013)
Schematic diagram showing OH- conductivity mechanism*
Anion conductive polymer: core component
AMFC worldwide - Academy
In 2013 more than 200 papers focused on AEMs, electrocatalysts, and also on small lab scale AMFC preparation and testing were published. Leading academic groups in PennState, Surrey, Wuhan, NREL (etc…) are making interesting progress:
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Hickner (Tew et al., JACS 2012) works on fundamental
development of new anion conducting polymers for
AEMs. Some first polymers already showed practical
conductivity, but poor stability (hours-level).
Varcoe (AMFC workshop, Surrey 2013) keep making
progress using a simple radiation-grafted process to
functionalize commercially available films. Initial
reasonable IECs were already obtained in their ETFE-
based membranes.
Best power density result published for a complete non-Pt cell: 70mW/cm2
Tang DaoPing, et al.; Sci. China Chem. 2 (2010) 53
Best published result in Pt-free-based AMFC technology: Max. power density of 70mW/cm2
AMFC worldwide - Academy
State-of-The-Art in AMFCs
CellEra is defining THE state-of-the-art in AMFC technology
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CONFIDENTIAL
CellEra’s crosslinked AMFC, non-Pt cathode,
dry H2 / filtered air, 60C
CellEra’s results based on
non-Pt anode / non-Pt cathode
CellEra’s state-of-the-art in AMFCs is worldwide recognized by all academic and commercial groups working in this technology. Therefore, CellEra is the leader player in the most important collaborative works being carried out in AMFCs
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CONFIDENTIAL
State-of-The-Art in AMFCs
A Novel Method for Making a Robust AMFC
Rise of HFR with time in old and new CellEra’s cells
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--- Pre polymer modification
--- After polymer modification
CONFIDENTIAL
CellEra developed a new polymer modification approach that stabilizes the functional
groups of the polymer reducing the cell resistance degradation
Full-sized short stack cycling – progress over
time
Improvement in cycle-ability in 6-cell short stacks over time
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CONFIDENTIAL
Initial performance/voltage efficiency of full-sized 6-cell short stacks was improved
by 50% over the last 2 years
Average initial cell voltage of full-sized
short stacks throughout past years
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CONFIDENTIAL
CellEra’s AMFC voltage efficiency – progress over
time
0
100
200
300
400
500
600
0 0.4 0.8 1.2 1.6 2
mW
/cm
2
A/cm2
Y2011 Y2012
5cm2 cells
Pt Anodes Pt Anodes
Ni decorated catalyst
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.4 0.8 1.2 1.6 2
V
A/cm2
Y2013
Ni-decorated Anodes**
Non-Pt cathode catalyst Dry H2 / 3barg Filtered air / 1barg
70C
Electrocatalyst development – status and progress
over time
Pt 1 mg/cm2
** CellEra’s patent PCT/US2013/039853
WO/2013/184269
CONFIDENTIAL
Full size AMFC stack design
• Temperature distribution along the cells is now homogeneous within a very small
variation (±1°C). As a consequence of the good thermal as well as gas flow
homogeneity achieved, voltage distribution along the stack is low (StdDev <20 mV),
proving stack design is optimum.
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CONFIDENTIAL
10 20 30 40 50 605354555657585960616263
Cell # [ ] (from An to Ca, i.e., from gases outlets to inlets)
Te
mp
era
ture
[C
]
58 A (cycle 3): Cell Ca Center[h]
58 A (cycle 3): Cell Ca mid-height; Cold side across cooling channel[h]
58 A (cycle 3): Cell Ca mid-height; Hot side across cooling channel[h]
2h zoom-in on a 12h long ON cycle, Dec 4th 2013
CONFIDENTIAL
840.2 840.4 840.6 840.8 841 841.2 841.4 841.6 841.8 8420
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
0.7
0.75
0.8Test #2892 ; 58 cell(s) ; 235 cm
2 @ AMR4/KIKU1i [/KIKU13i old version w Keithley]
time [h]
Ind
ivid
ual
Cell
Vo
ltag
e [
V]
Full size AMFC stack design
Voltage stability/distribution during long ‘ON’ cycles
Ammonia as a fuel source
• We have initiated testing of our stacks using a fuel mix which simulates the
expected output of the ammonia cracker, using a diluted 75% H2, 25% N2 fuel mix.
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3 4 5 6 70
15
30
45
60
75
90105
120
135
150
165
180
195210
225
240
255
270
285
time [h]
Pow
er [W
] ; I
[A]
Test #2828 ; 6 cell(s) ; 235 cm2 @ KIKU 2-19
3 4 5 6 700.1
0.2
0.3
0.4
0.5
0.60.7
0.8
0.9
1
1.1
1.2
1.31.4
1.5
1.6
1.7
1.8
1.9
Volta
ge/C
ell (
avg)
; Te
mp/
100
[C
]; H
FR [m
/c
ell];
MFC
s/10
0 [s
LPM
]
Power
Current
Voltage
Stack Temperature
HFR
H2/N
2 75/25
mix
pure
H2
CONFIDENTIAL
NH3 75%H2
First results are promising,
achieving 90% of the power density
achievable with neat hydrogen. This
is prior to any optimization in cell
and stack design
** CellEra’s patent US2012/0043519