La 0.8 Sr 0.2 CoO 3 Coated Nickel Cathodes for Molten Carbonate Fuel Cells

1. La0.8Sr0.2CoO3 Coated Nickel Cathodes for Molten Carbonate Fuel Cells Prabhu Ganesan, Hector Colon, Bala Haran, R. E. White and Branko Popov Department of Chemical Engineering University of South Carolina, Columbia, SC 29208.

2. Presentation Outline • Objectives • Prepare a stable cathode material with lower solubility and comparable performance as NiO • Coating of La0.8Sr0.2CoO3 using sol-gel process • Characterization Studies • Polarization performance • AAS – Solubility measurements • SEM – Microstructure analysis • EIS • Full cell studies

3. Component Material / Properties Problem/Solution Anode 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 • Creep/Sintering • - Ni-Al Alloy • Electrolyte retaining • - Coating of Oxides Cathode 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 • NiO dissolution • - Stabilized NiO • - LiCoO2 cathode • - Modified electrolyte Material g-LiAlO2 Pore size 0.2 ~ 0.5 mm Porosity 50~60% Thickness 0.5 mm Sp. Area 0.1~10 m2/g Matrix • Sintering/Thermal Stability • - Fiber or large particles • Phase stability • - a-LiAlO2 • Chromium Dissolution • - Nickel Cladding (Anode) • - Fe-Al alloys Material SS316 Current Collector State-of-the Art Molten Carbonate Fuel Cells

4. Cathode Materials for Molten Carbonate Fuel Cells • State-of-the-art NiO(Li) • Alternate Cathodes • LiCoO2, LiNiO2 • LiCoO2 Coated Nickel Oxide • Ni-Ce and Ni – La2O3 • Ni-Nb Surface Alloy • Perovskites such as La0.8Sr0.2CoO3 • Cobalt Encapsulated Nickel • Mixed Lithium Nickel Cobalt Oxides

5. Porous Ni Cathode USC Molten Carbonate Fuel Cell (Half Cell) Perforated SUS 304 Current Collector

6. USC Molten Carbonate Fuel Cell (Full Cell)

7. Dispersant + Water Ni Powder Milling 24 h Milling 12 h Binder Plasticizer Milling 12 h Filtering De-airing Casting Sintering Drying Flow chart for Ni electrode preparation

8. TGA Behavior of Ni green tape

9. 800OC 1 h 800 OC Nitrogen 5 OC/min 5 h 400 OC 400 OC 1 OC/min 3 h 230 OC 230 OC 1 OC/min Hydrogen 1 h 130 OC 130 OC 1 OC/min RT RT Sintering schedule for Ni electrodes 1 OC/min

10. La, Sr, Co-Acetates Dist. Water Stirring at 80o C Citric Acid Ethylene Glycol Stirring Gel Ni Electrodes Drying in Vacuum at 90o C Sintering at 900o C in Air Flow chart for LSC Coated Ni electrode preparation

11. XRD Patterns of La0.8Sr0.2CoO3 at different temperatures

12. SEM Pictures of La0.8Sr0.2CoO3 coated Ni electrode After Sintering at 900°C Bare Ni Electrode LSC Coated Ni Electrode Sintered at 900o C LSC Coated Ni Electrode after immersion in molten carbonate Melt for 200 hours Magnification X 2000

13. Dissolution Behavior La0.8Sr0.2CoO3 coatedNi electrode at 650o C

14. Polarization Behavior of Ni

15. Polarization Behavior of La0.8Sr0.2CoO3 coated Ni electrode

16. Comparison of Impedance Behavior of Ni

17. EIS response for La0.8Sr0.2CoO3 coated Ni electrode at 650°C

18. EIS response for La0.8Sr0.2CoO3 coated Ni electrode at 700°C

19. EIS response for La0.8Sr0.2CoO3 coated Ni electrode at 750°C

20. EIS response of La0.8Sr0.2CoO3 coated Ni electrode in Full Cell at 650°C

21. Conclusions • Rate of dissolution of Ni decreased significantly after La0.8Sr0.2CoO3coating. • The observed increase in polarization may be due to the decrease in porosity and change in surface morphology. • La0.8Sr0.2CoO3coatednickel oxides offer better stability in MCFC cathode environment.

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