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Performance of Titanium Alloy and Co Plated Titanium Alloy for MCFC Current Collector. Hector Colon, Prabhu Ganesan, Bala Haran, R. E. White and Branko Popov Department of Chemical Engineering University of South Carolina, Columbia, South Carolina 29208. Outline. Lifetime Limitations. - PowerPoint PPT Presentation
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Hector Colon, Prabhu Ganesan, Bala Haran, R. E. White and Branko Popov
Department of Chemical Engineering
University of South Carolina,
Columbia, South Carolina 29208
Performance of Titanium Alloy and Co Plated Titanium Alloy for MCFC Current Collector
Outline
Experimental
Objective
Lifetime Limitations
Results
Conclusions
Materials Characterization
Component Material / Properties Problem/Solution
Anode Material Ni+10wt% CrPore size 3 ~ 6 mPorosity 50~70%Thickness 0.5~1.5 mmSp. Area 0.1~1 m2/g
• Creep/Sintering - Ni-Al Alloy
CathodeMaterial Lithiated NiOPore size 6 ~ 9 mPorosity 80~85% as NiThickness 0.5~0.8 mmSp. Area 0.5 m2/g
• NiO dissolution - Stabilized NiO - LiCoO2 cathode - Modified electrolyte
Matrix Material -LiAlO2
Pore size 0.2 ~ 0.5 mPorosity 50~60%Thickness 0.5 mmSp. Area 0.1~10 m2/g
• Sintering/Thermal Stability - Fiber or large particles• Phase stability - -LiAlO2
CurrentCollector
Material SS316 •Chromium Dissolution - Nickel Cladding (Anode) - Fe-Al alloys
Lifetime Limitations
Lifetime Limitations (SS 316)
0
10
20
30
40
50
60
70
80
90
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400
Time (hours)
Chr
omiu
m M
ole
Frac
tion
(x 1
06 )
0
5
10
15
20
25
30
Nic
kel M
ole
Frac
tion
(x 1
06 )
(b)
Ni
Cr
SS 316(After 350 hr of testing)
Lifetime Limitations (SS 316)
Objective
To find a candidate that will has better corrosion resistance than the state of art current collector
To characterize the performance of a titanium alloy (Ti77.5/Mo12/Zr 4.5/Sn 4.5) with different surface treatmentsHeat TreatmentCobalt platting on the surface
Experimental
Heat treatment was performed in order to increase the thickness and form a more uniform protective corrosion layer Kept at 400 ºC in 99 % N2 & 1% O2 atmosphere for
62 hrCo plating was performed to reduce the possible
dissolution of components and to improve the conductivity of the oxide layer Cobalt chloride and sodium citrate bath 1 mA/cm2 for 2.5 hours at pH 9.5
Materials Characterization
Electrochemical Characterization:Linear Polarization-RP
EIS
Physical Characterizations:SEM – Microstructure AnalysisXRD – Crystal Characterization
AAS - Dissolution Studies
Gold Wire (Reference electrode)
50% LiAlO2 / 50% Electrolyte Plug
O2/CO2 Reference Gas
Alumina Tube
Alumina Tube Wall
Heating Block
SS 304 Rod
Perforated SS 304 Current Collector
Electrolyte andSeparator Matrix
Working Electrode
Cathode Gas Inlet
Gold Wire (Reference electrode)
50% LiAlO2 / 50% Electrolyte Plug
O2/CO2 Reference Gas
Alumina Tube
Alumina Tube Wall
Heating Block
SS 304 Rod
Perforated SS 304 Current Collector
Electrolyte andSeparator Matrix
Working Electrode
Cathode Gas Inlet
O2/CO2 Reference Gas
Alumina Tube
Alumina Tube Wall
Heating Block
SS 304 Rod
Perforated SS 304 Current Collector
Electrolyte andSeparator Matrix
Working Electrode
Cathode Gas Inlet
Results (Mo Dissolution)
Dissolution of Mo from Titanium alloy at 650o C
0
5
10
15
20
25
30
35
40
45
0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400
Time (hours)
Mol
ybd
enu
m M
ole
Fra
ctio
n (
x 10
6 )
Bare Ti Alloy
Heat Treated Ti alloy
Cobalt plated Ti Alloy
(a)
Heat Treated Ti Alloy
Bare Ti Alloy
Cobalt Coated Ti Alloy
Cobalt coated Titanium Alloy (Before testing)
Results (SEM-Micrographs)
Bare Titanium Alloy(After 350 hr of testing)
Results (SEM-Micrographs)
Heat Treated Titanium Alloy(After 350 hr of testing)
Results (SEM-Micrographs)
Results (SEM-Micrographs)
Cobalt Coated Titanium Alloy(After 350 hr of testing)
Results (XRD-Pattern after 350 hr testing)
Li2TiO3 – Lithium Titamium Oxide
LiTiO2 – Lithium Titamium Oxide
Titanium Alloys (After 350 hr of testing)
Results (Impedance Behavior with Time)
0
5
10
15
20
25
30
35
0 10 20 30 40 50 60 70 80Zreal ()
-Zim
g (
)
10hr
60hr
107hr
131hr
248hr
344hr
Bare Titanium Alloy
Results (Impedance Behavior with Time)
0
5
10
15
20
25
30
35
0 20 40 60 80 100 120 140
Zreal ()
-Zim
g (
)
18.5hr43.5hr110.5hr139hr159hr208hr308.5hr
Heat Treated Titanium Alloy
Results (Impedance Behavior with Time)
0
10
20
30
40
50
60
0 20 40 60 80 100 120 140 160Zreal ()
-Zim
g(
)
11hr
35hr
85hr
131hr
162.5hr
347hr
Cobalt coated Titanium Alloy
Results (Impedance Behavior with Time)
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14 16Zreal ()
-Zim
g (
)
106081203229344
SS 316
Conclusions
Immersion test indicate a decrease in molybdenum dissolution in the case of Cobalt coated Ti alloy
Surface mainly consist of Titanium oxides The polarization resistance for this alloy is significantly
higher than state of art current collectorCobalt coated titanium alloy gives the highest corrosion
resistance
Financial sponsors - Dept of Energy,
National Energy Technology Laboratory
Acknowledgements