STABILITY OF LANTHANUM CALCIUM CHROMITE-LANTHANUM STRONTIUM MANGANITEINTERFACES IN SOLID OXIDE FUEL-CELLS

An investigation has been made on the chemical stability of the cathod e-interconnect interface in solid oxide fuel cells. Lanthanum calcium chromite and lanthanum strontium manganite (a dense 10% A-site deficie nt manganite, a porous 10% A-site deficient one or a dense 1% A-site d eficient one) were placed between air and fuel (hydrogen/water) at a s elected electrical current density The electrical conductivity across the interfaces was slightly increased for 300 h. Changes in morphology , chemical composition, and phases were examined by scanning electron microscopy/energy dispersive x-ray and x-ray diffractometry analysis. The dense 10% A-site deficient cathode gave rise to the precipitation of manganese oxide at the air-side surface as well as at the interface . The porous cathode enhanced chemical reactions between lanthanum cal cium chromite and lanthanum strontium manganite. The dense 1% A-site d eficient cathode was most stable. These phenomena have been thermodyna mically analyzed in terms of (i) irreversible mass transfer under an o xygen potential gradient, (ii) changes of the stable composition regio n of the perovskite phases as a function of oxygen potential, and (iii ) an enhancing effect of the liquid formation on reactions at interfac es.