Transcript Technological development

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2 Section
Technological development
(MCFC)
Technological development
(MCFC)
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Material used now
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ANODE: Ni-Cr, Ni-Al
CATHODE: LixNi(1-x)O
ELECTROLYTE: Li2CO3/K2CO3
Na2CO3
MATRIX: -LiAlO2
ANODE CC: Ni/AISI310S/Ni
CATHODE CC: AISI310S
SEP. PLATE (AA): AISI310S
SEP. PLATE (NAA): AISI310S/Al
Technological development
(MCFC)
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Materials actually used in MCFC are suitable to have high
electrochemical performance and long operation time
In view of Fuel Cell market, it is still possible to think to
improve materials to obtain higher performance, longer
operation time and low cost
Technological development
(Electrochemical Performance)
Reaction Rate Loss mainly depends on
materials used for anode and cathode
(catalyst property)
Gas Transport
Loss mainly
depends on
anode and
cathode
materials
morfology
Resistance Loss mainly depends on ionic resistance of electrolyte
and electronic resistance of anode, cathode, metallic components
included corrosion layers
Technological development
(Electrochemical Performance)
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Reaction Rate Loss
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Electrochemical properties of Ni (for H2 oxidation
reaction), and NiO (for O2 reduction reaction) are
very high
However, limited improvements should be possible
by addition of catalyst in standard anode, cathode
materials (Cost?, CO use?)
Technological development
(Electrochemical Performance)
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Resistance Loss
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Use of thin electrolyte layer decrease ionic resistance
(gas separation problem)
Use of electrolyte with low ionic resistance:
Li2CO3/Na2CO3 has lower ionic resistance than
Li2CO3/K2CO3
Use of materials for metallic components with higher
corrosion resistance (thin corrosion layer with high
electrical conductivity corrosion products)
Technological development
(Electrochemical Performance)
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Gas Transport Loss
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Porosity, surface area of anode and cathode are
suitable to obtain low gas transport loss (bi-modal
morfology of cathode)
However improvement should be possible with higher
surface area (nanomaterials?)
Technological development
(Operation time)
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Cathode dissolution
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LixNi(1-x)O has not completely chemical stability in
working conditions
Precipitation of Ni in Matrix can produce a direct
electronic contact between anode and cathode
Internal current flow means electrical performance
decay
Use of more chemical stable materials should be
useful (catalyst for cathodic reaction, high
electronic conductivity)
Technological development
(Operation time)
CATHODE (+)
NiO+CO2  Ni++ + CO3--
Ni++
MATRIX
Ni++ +H2+ CO3--  Ni + H2O+CO2
e
ANODE (-)
Technological development
(Operation time)
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Metallic components corrosion
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Metallic components corrosion means mechanical
property degradation
a)
Anode current collector section OM analysis. a) Before operation b) After operation:it is
possible to see Ni coating degradation (lower corrosion protection), and carburisation of
AISI310S grains (lower mechanical property)
b)
Technological development
(Operation time)
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Porous components micro-structural degradation
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Porosity, pore size distribution, surface area and
morfology of anode and cathode material change in
time due to axial load and sintering (Anode)
These changes on electrodes materials mean
electrochemical performance degradation (P=0)
Porosity, pore size distribution, surface area and
morfology of matrix material could change in time
due to -LiAlO2 to -LiAlO2 phase transition (gas
composition)
These changes on matrix material mean gas separation
property degradation (increase of pore size, matrix not
totally filled by electrolyte)
Technological development
(Operation time)
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Electrolyte loss
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Electrolyte loss depends on metallic materials
corrosion, vapour phase in gas stream
When electrolyte quantity is not enough to have
totally filled matrix, direct contact of H2 and O2 will
be possible (electrical performance degradation)
Lab level test
(Performance)
Single cell test
Single cell is useful to test
electrical performance in
lab scale MCFC
Chronogram of single cell voltage/current
characterisation.
1,2
1
15
0,8
10
0,6
0,4
Voltage
5
Current
0,2
0
0
Time
Current (A)
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Voltage (V)
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Lab level test
(Performance)
Characte ri sati o n Vo l tag e and P o w e r/ Curre nt
De nsi ty
Voltage single cell 1
Voltage single cell 2
Power density single cell 1
Power density single cell 2
Activation Pol.
1000
Voltage (V)
15
Ohmic Pol.
800
20
600
10
Power (W)
1200
400
5
Concentration Pol.
200
0
0
50
100
150
200
Current density (mA/cm2)
250
0
300
Lab level test
(Performance)
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Gas analysis
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In-out single cell gas analysis are performed to check
gas utilisation and possible gas reaction through
matrix
Lab level test
(Operation time)
Single cell Voltage, Voltage iR free, iR trend
1100
20
1000
18
900
16
14
700
12
600
10
500
8
400
V (5,5 A)
300
Matrix filling
level control
200
100
IR (mOhm)
500
1000
1500
2000
Time(h)
4
2
0
0
6
2500
3000
3500
0
4000
iR (mOhm)
Voltage (mV)
800
Lab level test
(Operation time)
Lab stack test
Lab size stack is useful
to test electrical
performance of more
cells in stack
configuration
80
18
70
17
60
16
50
15
40
14
30
13
20
12
10
11
10
0
50
100
150
200
250
Time [unit]
300
350
400
450
0
500
Voltage [V]
Current [A]
Current [A]
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19
Voltage [V]
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Lab level test
(Operation time)
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Post test analysis
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SEM-EDS
Lab level test
(Operation time)
ANODE, CATHODE, MATRIX SEM ANALYSIS
(Micro- structural change)
Lab level test
(Operation time)
ANODE, CATHODE, MATRIX PORE SIZE ANALYSIS
(Micro- structural change)
Porosity
reduction
Pore size
distribution
change
Lab level test
(Operation time)
GAS
IN gas
Ingresso
Thermocouple
Termocoppia
Fournacedel forno
Camera
Crogiolo
di allumina
Alumina crucible
Pressure
Caricoload
meccanico
Elettrodo
di Nichelfilled
poroso
Porous
Ni electrode
with Li/K
carbonate
impregnato di carbonati Li/K
Campione
metallico
Metal sample
(spessore
circa
(thickness: 0.3
mm) 0.3 mm)
Elettrodo
di Nichel
poroso
Porous
Ni electrode
filled
with Li/K
carbonate
impregnato con carbonati Li/K
T = 650 °C
ANODIC GAS: H2 / CO2 (80/20)
CATHODIC GAS: Air / CO2
Lab level test
(Operation time)
500
450
400
No corroded section (microns)
350
300
250
Serie1
200
150
100
50
0
0
3000
6000
Corrosion Time (hours)
9000
12000
Trend to
40.000 hours
Lab level test
(Cost reduction)
Material analysis
Lab level test
(Cost reduction)
Tape Casting
Material
analysis
Drying
Material
analysis
Binder burn out and sintering
Lab level test
(Cost reduction)
XRD
SEM
RAW MATERIALS ANALYSIS
Use of cheaper raw materials
GRANULOMETRY
Conclusion
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Fuel cell is an electrochemical device that converts energy
of a chemical reaction into electricity without any kind of
combustion and with high conversion capability and low
environmental emissions.
Molten Carbonate Fuel Cells don’t use expensive catalytic
material (Platinum); it can works using CO (reformed
natural gas); Operating temperature (650 °C) permit use
of stainless steel for metallic components fabrication
MCFC market entry depends on operating life increase and
cost reduction. Both points strongly depend on materials
used in Fuel Cell preparation