confidentialwww.solidcell.com0 SolidCell Composite Interconnect for SOFC Sergey Somov 1, Olivia Graeve 2, Sam Ghosh 3, and Heinz Nabielek 1 1 Solid Cell Inc., 771 Elmgrove Rd., Rochester NY Alfred University, 2 Pine St., Alfred NY RocCera LLC, 771 Elmgrove Rd., Rochester NY Daytona Beach, January 25, 2012

confidentialwww.solidcell.com1 SolidCell The Interconnect as a Key Component Metallic-based Advantages High mechanical strength & plasticity High electric conductivity High thermal conductivity Disadvantages Formation of oxide scale in air Poisoning of cathodes by chromium from stainless steel Oxide-based Advantages Stability in air & fuel Mechanical stability at high temperatures Disadvantages Fragile ceramic materials Changes in dimensions from variation of oxygen activity Traditional materials

confidentialwww.solidcell.com2 SolidCell Composite Interconnect A combination of oxide and metallic materials produces a composite with high temperature stability, mechanical robustness, high electrical conductivity, and an adjustable coefficient of thermal expansion (CTE). Also, it withstands corrosion. The general interconnect composition is: xNi + (1 – x – y)TiO 2 + yNb 2 O 5

confidentialwww.solidcell.com3 SolidCell Composite Interconnect The general interconnect composition is: xNi + (1 – x – y)TiO 2 + yNb 2 O 5 Oxide components provide strength and corrosion resistance Metallic component increases electrical conductivity and plasticity

confidentialwww.solidcell.com4 SolidCell Oxide Component of the Composite Titania doped by niobium oxide has high electrical conductivity in fuel and moderate conductivity in air.

confidentialwww.solidcell.com5 SolidCell Thermal Expansion Influence of Ni content on thermal expansion Dependence of CTE on Ni content at 850 o C

confidentialwww.solidcell.com6 SolidCell Supporting High Conductivity on the Cathode Side air H2H2 Interconnect disc YSZ tube hydrogen replacement by air Slight IC porosity provides penetration of hydrogen and keeps the composite in reduced state

confidentialwww.solidcell.com7 SolidCell Changes of TiO2 (Nb2O5) Resistance After Replacement of the Gas Environment a) The slow change of the resistance is explained by an extremely low rate of oxygen diffusion into doped titania. Change of gas environment from air to hydrogen and back: a) –short time; b) –long time b)b)

confidentialwww.solidcell.com8 SolidCell Composite Interconnect in the MPC Stack

confidentialwww.solidcell.com9 SolidCell Composite Interconnect in the MPC Design

confidentialwww.solidcell.com10 SolidCell Conclusion  The novel composite interconnect consisting of nickel and titania doped by niobium oxide has high mechanical strength, and high electrical conductivity in air and fuel.  It withstands thermal cycling and oxidation by air.  The coefficient of thermal expansion may be adjusted by variation of the metallic and oxide component ratio. Acknowledgements: This work was co-funded by NYSERDA (Project No 23644).