Electrophoretic Deposition of Dense La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.0115)Co_(0.085)O_(3-δ) Electrolyte Films from Single-Phase Powders for Intermediate Temperature Solid Oxide Fuel Cells

摘要

La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.115)Co_(0.085)O_(3-δ) (LSGMC) powders were prepared by polymeric precursor synthesis, using either polyvi-nyl alcohol (PVA) or citric acid (CA) as complexing agents. The powders were synthesized using different ratios between the complexing agent and the cations dissolved in solution. The obtained polymer gel precursors were dried and calcined at temperatures between 1000° and 1450℃. Single-phase LSGMC powders were obtained at a firing temperature of 1450℃, using PVA and a molar ratio between the hydroxylic groups and the total cations of 3:1. Phase-pure LSGMC powders were used to sinter (1490℃, 2 h) thick pellets. The functional properties of LSGMC pellets were assessed by electrochemical impedance spectroscopy. The electrical conductivity values and the apparent activation energies in different transport regimes were in agreement with literature data. The same LSGMC powders were deposited by electrophoretic deposition (EPD) on a green membrane containing lanthanum-doped ceria (La_(0.4)Ce_(0.6)O_(2-x), LDC), a binder, and carbon powders. The LSGMC/LDC bi-layer obtained by EPD was cofired at 1490℃ for 2 h. A dense and crack-free 8-μm-thick LSGMC film supported on a porous skeleton of LDC was obtained. The combined use of proper powder synthesis and film processing routes has thus proven to be a viable way for manufacturing anode-supported LSGMC films.