Progress Report on SequentialFab PlasmaSprayed SOFC Components Rob

Progress Report on Sequential-Fab Plasma-Sprayed SOFC Components Rob S. Hui, H. Zhang, X. Ma, J. Roth, J. Broadhead, D. Xiao, and D. Reisner US Nanocorp , Inc. Fuel cells 2003 The Third Annual BCC Conference 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Stamford, CT Fax: (860) 678 -7569

Outline • • Motivation Brief Review of Previous Work Progress Report Summary 2/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

US Nanocorp 1. Thermal Sprayed Electrodes / Electrolytes for Batteries and Fuel Cells 2. Fuzzy Logic Modeling Methods to Manage Batteries and Fuel Cells 2002 Deloitte & Touche Technology Fast 500 Award 2002 D&T Connecticut Technology Fast 50 Award 3/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Solid Oxide Fuel Cells (SOFCs) Features: • Higher efficiency • More flexible fuels • All solid components Applications: Power plant Residential Transportation Military 4/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Research Motivation High temperature SOFCs (~ 1000 o. C) Fuel YSZ LSM Air Load Ni-YSZ Ø Ø Ø Materials constraints High stress of differential thermal expansion Long term stability poor Precludes nanomaterials High cost of operation Low temperature SOFCs (< 850 o. C) Ø Alternative materials Ø Appropriate cell design Ø Manufacturing routes 5/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

USN’s Enabling SOFC Technology q Nanostructured electrode materials · Enable low Temperature Operation · High activity (high interfacial surface area) · Expect Improved cell performance q Plasma Spray · Integrated fabrication of membrane-type SOFC q New materials with high performance · Sr 1 -1. 5 x. Yx. Ti. O 3 (“SYT”) replaces Ni/YSZ · MIEC has more reaction sites than Ni-cermet · LSGM has four-time higher ionic conductivity than YSZ 6/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

USN’s SOFC Strategy Ø Reduce cell operating temperature Thin film LSGM electrolyte (high conductivity) Nanostructured electrodes (many grain boundaries -> large interface) SYT anode material is a MIEC working at 600 – 800 o. C Ø Increase fuel cell operating efficiency SYT could directly catalyze hydrocarbon fuel SYT has more reaction sites than Ni-cermet Ø Drive down fuel cell manufacturing cost using APS Inexpensive, Universal (Metco 9 MB) Sequential fabrication of cell components Possibility of elimination of reforming unit 7/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Plasma Processing • Brief (on the order of 1 ms) particle residence time • Rapid heating • Steep gradients in HVOF and plasma flow fields 8/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Advantages of Plasma Spray Nanomaterial Feedstock Thermal Spray Gun Substrate Nanocoated Component Graded porosity & Rapid and sequential composition fabrication Excellent interfacial Nanostructured materials contact Accurately controlled Large area and free Thickness 9/23 geometry Potential low cost Unlimited substrates (automation) (@RT) Robotic continuous 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569 No high temperature operation

Feedstock Reconstitution 5 - 20 nm particles loosely agglomerated non-agglomerated 5 - 20 nm particles 20 m m 30 mm hollow shell agglomerates reconstituted sprayable form 10/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Microstructure of Feedstock 100 m 11/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

USN’s Planar SOFC Systems Anode electrode Electrolyte Cathode electrode Free standing plasma sprayed SOFC single cells 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569 12/23

USN’s Tubular SOFC Systems LDC 40 + Ni LDC 40 LSGM SWPC tube Anode: Interlayer: Electrolyte: Cathode: Nano LDC 40 + Ni LDC 40 La 0. 8 Sr 0. 2 Ga 0. 8 Mg 0. 2 O 3 SWPC proprietary tube 13/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Requirements for Sprayed Components Ø Porous electrodes SYT Ø Dense electrolyte Ø Right chemical phase and composition LSGM Ø Compatible electrochemical properties LSM 50 mm 14/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

SEM Images of LSGM 30 mm LSM LSGM feedstock As-sprayed LSGM on LSM 15/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Open-Circuit Voltage 16/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

As-sprayed LSGM X-ray diffraction spectra Ac Impedance measurement 17/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Heat-treatment of Sprayed LSGM Change of ac Impedance spectra Chang of XRD pattern 18/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Sintered & Sprayed LSGM Pressed / Sintered LSGM Sintered vs Sprayed LSGM 19/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Solution Feedstock Plasma Spray Atomizing Nozzle Tungsten Cathode Gas + Gas Plasma + - Tungsten Anode Pump YSZ Liquid Feed Stock Work piece 20/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Advantages of SPS Electrode Forms 3 -D porous structure, leading to high fuel gas permeability for anode Forms nanostructured anode, increases surface area of fuel – solid interaction · Enables thin layer coating formation · Higher thermal shock resistance 21/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Summary ü Nanostructured SOFC was proposed based on the materials selection and fabrication technique ü Planar SOFCs have been successful fabricated by plasma spray technique with dense electrolyte and porous electrodes ü Thick film LSGM has been sprayed and characterized. Sprayed layer has same electrochemical properties with sintered one ü Improvement of electrode structure and characterization of fuel cell performance are needed in the future 22/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569

Acknowledgement This work was supported by the Department of Energy: (1)with Dr. Keqin Huang at Siemens Westinghouse Power Corp. under DOE Prime Contract No. DE-FC 26 -99 FT 40709 (2)under a DOE SBIR Grant No. DE-FG 0201 ER 83340. 23/23 74 Batterson Park Road, Farmington, CT 06032 1 -888 -NANO-888 Fax: (860) 678 -7569