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

Outline New Materials Materials Characterization Lifetime Limitations Results Conclusions Approach

Component Material / PropertiesProblem/Solution Anode MaterialNi+10wt% Cr Pore size3 ~ 6  m Porosity 50~70% Thickness 0.5~1.5 mm Sp. Area0.1~1 m 2 /g Creep/Sintering - Ni-Al Alloy Cathode MaterialLithiated NiO Pore size6 ~ 9  m Porosity 80~85% as Ni Thickness 0.5~0.8 mm Sp. Area0.5 m 2 /g NiO dissolution - Stabilized NiO - LiCoO 2 cathode - Modified electrolyte Matrix Material  -LiAlO 2 Pore size0.2 ~ 0.5  m Porosity 50~60% Thickness 0.5 mm Sp. Area0.1~10 m 2 /g Sintering/Thermal Stability - Fiber or large particles Phase stability -  -LiAlO 2 Current Collector MaterialSS316 Chromium Dissolution - Nickel Cladding (Anode) - Fe-Al alloys Lifetime Limitations

Materials Characterization Electrochemical Characterization: Linear Polarization-R P EIS Physical Characterizations: SEM – Microstructure Analysis XRD – Crystal Characterization AAS - Dissolution Studies

New Materials  LiNi 0.8 Co 0.2 O 2 Tape  Co coated Ni tape  La 0.8 Sr 0.2 CoO 3 coated Ni tape  NiO Ni dissolution (AAS Data) Polarization Behavior

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

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

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

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

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

Varying CO 2 Partial Pressure Varying O 2 Partial Pressure Results (Impedance Behavior at 650 ºC) Increasing CO 2 Increasing O 2

Results (Impedance Behavior at 700 ºC) Increasing CO 2 Increasing O 2 Varying CO 2 Partial Pressure Varying O 2 Partial Pressure

Results (Impedance Behavior with time at 650 ºC)

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

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