Performance of Co Coated Nickel Cathode Prepared by Tape Casting for Molten Carbonate Fuel Cells

1. Performance ofCo Coated Nickel Cathode Prepared by Tape Casting for Molten Carbonate FuelCells Prabhu Ganesan, Hector Colon, Bala Haran, R. E. White and Branko Popov Department of Chemical Engineering University of South Carolina, Columbia, South Carolina 29208

2. Outline Lifetime Limitations Materials Characterization New Materials Approach Results Conclusions

3. Component Material / Properties Problem/Solution Material Ni+10wt% Cr Pore size 3 ~ 6 mm Porosity 50~70% Thickness 0.5~1.5 mm Sp. Area 0.1~1 m2/g Anode • Creep/Sintering • - Ni-Al Alloy • NiO dissolution • - Stabilized NiO • - LiCoO2 cathode • - Modified electrolyte Material Lithiated NiO Pore size 6 ~ 9 mm Porosity 80~85% as Ni Thickness 0.5~0.8 mm Sp. Area 0.5 m2/g Cathode Matrix Material g-LiAlO2 Pore size 0.2 ~ 0.5 mm Porosity 50~60% Thickness 0.5 mm Sp. Area 0.1~10 m2/g • Sintering/Thermal Stability • - Fiber or large particles • Phase stability • - a-LiAlO2 • Chromium Dissolution • - Nickel Cladding (Anode) • - Fe-Al alloys Current Collector Material SS316 Lifetime Limitations

4. Electrochemical Characterization: Linear Polarization-RP EIS Materials Characterization Physical Characterizations: SEM – Microstructure Analysis XRD – Crystal Characterization AAS - Dissolution Studies

5. NiO • La0.8Sr0.2CoO3 coated Ni tape • Co coated Ni tape • LiNi0.8Co0.2O2 Tape New Materials Ni dissolution (AAS Data) Polarization Behavior

6. Approach Auto catalytic reduction of Co onto Ni metal particles followed by tape casting Activation in Sodium Hypophosphite @ 85 ºC Cobalt Coating @ 85 ºC Dispersant + Water Plasticizer Binder Milling Milling Milling Binder : Polyvinyl Alcohol Plasticizer: Glycerol, Dispersant: Disperbyk® Filtering + De-Airing Casting

7. RT 1 ºC/min. 130 ºC for 1 hr Nitrogen 1 ºC/min. 230 ºC for 3 hr 1 ºC/min. 400 ºC for 5 hr 5 ºC/min. Hydrogen 800 ºC for 1 hr RT Results TGA Behavior of Co coated Ni green tape Sintering was performed in several steps

8. Results (SEM-Micrographs) Co coated Ni powder electrode after immersion in MC for 200 hr Co coated Ni powder green tape Co coated Ni powder electrode half-cell testing after 1000 hr Sintered Co coated Ni powder 15 mm Magnification X 2000

9. Ni NiO Ni NiO After half-cell Testing (1000 hr) Co-Ni Powder After immersion for 200 hr Results (XRD-Patterns)

10. NiO • Co coated Ni tape • Co coated Ni powder Results (Ni Dissolution) Dissolution Behavior of Co Coated Ni Electrode at 650o C Co coating on Ni powder (~4 wt. %Co) followed by tape casting and sintering

11. Results (Impedance Behavior at 650 ºC) Increasing O2 Increasing CO2 Varying CO2 Partial Pressure Varying O2 Partial Pressure

12. Results (Impedance Behavior at 700 ºC) Increasing O2 Increasing CO2 Varying CO2 Partial Pressure Varying O2 Partial Pressure

13. Results (Impedance Behavior with time at 650 ºC)

14. Conclusions • Dissolution rate of cobalt coated nickel particles is 33% lower than NiO cathode dissolution • Dissolution is lower than cobalt coated Ni tape • Polarization behavior shows similar performance as state of art NiO • Impedance shows after 80 hr of operation the system reaches steady state

15. Acknowledgements Financial sponsors - Dept of Energy, National Energy Technology Laboratory