SOFC Anode Materials
Overview
Most common SOFC anode materials are Ni-YSZ composites
- Excellent catalytic activity
- Good electronic conductivity
Ni metal is readily oxidized to NiO or Ni(OH)x in electrolysis environment
- severe electrode polarization and deactivation
- coarsening with extended time at temperature
To address this, we are sythesizing materials and manufacturing
a Ni-free composite anode, primarily an all oxide Mixed-Ionic-Electronic
Conductor (MIEC)
The MIEC is yttrium-doped strontium titanate SrTiO3 (Sr1-1.5xYxTiO3-δ)
Strontium, magnesium and cobalt doped lanthanum gallate (LSGM: La1-xSrxGa1-y-zMgyCozO3-δ)
is used in the composite anode Lanthanum-doped Ceria (LDC) (Ce1-x LaxO2-δ)
is also used in the composite anode Sr0.86Y0.08TiO3-δ has
relatively high electrical conductivity and good chemical stability
under reducing conditions [1,2]
Goal and Objectives
- Investigate nickel-free anode materials for the anode of a reversible
SOFC
- Develop a novel sol-gel process for synthesis of SYT
- Use the novel sol-gel process to synthesize SYT
- Measure SYT properties to determine whether the materials are
promising for use in reversible SOFC anodes
- Manufacture composite SYT anodes (with LDC, LSGMC) and test them in full SOFC button cells
Solid Oxide Fuel Cell
Interface Study
A full cell was fabricated for the study of interfacial characteristics
Fabrication of Full Solid Oxide Fuel Cells
Glycine-nitrate process:
•electrolyte- La0.8Sr0.2Ga0.8Mg0.115Co0.085O3-δ (LSGMC)
•anode component- Ce0.5La0.5O2-δ (LDC)
•cathode component- Sm0.5Sr0.5CoO3-δ (SSC)
Electrolyte: LSGMC Pellet pressed in 1.25” die and sintered to full density
Composite anode: SYT / LDC / LSGMC 0.5/0.4/0.1 wt.
Composite cathode:SSC / LSGMC .7/.3 wt.
Pt paste and mesh used as :current collectors for both anode and cathode
Electrochemical Testing
Electrochemical testing performed on a Solartron® model 1260 and 1480 8-Channel AC Impedance Spectrometer
Temperature controlled by an ATS single zone multi-sample split tube furnace
Environment controlled by Brooks® MFCs
- variable fuel and air flowsand partial pressures
Experimental Apparatus
X-Ray Diffraction
X-ray diffractometry allows for the identification
of materials based on their structure
Data is gathered and compared to a library or simulation based on known or predicted parameters
XRD Patterns of LDC Powder
- LDC powder shows expected crystal structure with peaks shifting at higher La doping levels
- No impurity phases observed
TGA Analysis of SYT Gel
XRD Patterns of SYT Powder
Characteristics of Calcined Foam
Anode Impedance Study
Personnel
Investigators: X. Lu, J. Brouwer, D. Mumm, and G.S. Samuelsen
Staff: R.L. Hack, M.D. Crespin
Students: Tom S. Pine
Sponsors
U.S. Department of Defense, Fuel Cell Program
Edison Materials Technology Center
[2] O. A. Marina, N. L. Canfield, J. W. Stevenson, Solid State Ion., 149 (2002) 21-28.