HIGH-PERFORMANCE ELECTRODE FOR MEDIUM-TEMPERATURE SOLID OXIDE FUEL CELLS CONTROL OF MICRO STRUCTURE OF La(Sr)CoO_3 CATHODE WITH HIGHLY DISPERSED Pt ELECTRO CATALYSTS

摘要

In order to enhance gas-diffusion rates in a porous La(Sr)CoO_3 (LSC) cathode, additional μm-sized pores were prepared by sintering a LSC paste containing fine polymer beads (d = 1.2 μm), coated on yttria-stabilized zirconia (YSZ) electrolyte. A thin and dense samaria-doped ceria (SDC) interlayer was used to avoid unfavorable solid-state reactions between LSC and YSZ. Control of the microstructure of LSC cathode appreciably lowered the IR-free overpotential without an increase of the ohmic resistance. The performance of the LSC cathode with optimized microstructure was enhanced further with highly dispersed Pt catalysts at 3 wt% loading, especially at low operating temperature. The current density on the Pt-LSC cathode at an overpotential of -0.05 V was 1 A/cm~2 at 800°C in air.