Utilization of (La1-xSrx)CoO3-δ/(La1-ySry)2CoO4±δ heterostructures as cathode for it-SOFCs

Torunoğlu, Ziya Çağrı
Perovskite type ABO3 oxides have been studied as one of the promising candidates for the cathode of intermediate temperature (500-700 ˚C) solid oxide fuel cells (SOFCs). The one of the best one among them is (La1-xSrx)CoO3-δ (LSC113) in terms of SOFC cathode performance. However, LSC drastically suffers from strong chemical instability problem manifested as surface Strontium segregation, triggered by increasing operation temperature. Lowering temperature, on the other hand, blocks oxygen reduction performance of cathode, constituting a contradiction. Recently, a thousand times greater oxygen reduction reaction coefficient, k (cm/s), around the (La1-xSrx)CoO3-δ/(La1-ySry)2CoO4±δ interface than LSC113 has been reported in recent years. This hetero-interface can decrease operation temperature of SOFC cathode to reasonable levels by facilitating oxygen reduction. The aim of this study is to utilize this hetero-interface for cathode by integrating different interface construction approaches and examine their results in terms of their compatibility at desired low temperatures. Simultaneous-sputtering of (La1-xSrx)CoO3-δ and (La1-ySry)2CoO4±δ as thin film cathode and dual phase synthesis from one solution as route-oriented conventional thick cathode has been adopted as the progressive ways to maximize interfaces, the former of which yielded positive results in terms of increasing hetero-interface and reducing cathode resistance. On the other hand, although dual phase syntheses of powders were successful, were not composed of agglomerates of two phases and did result in fınely dispersed nano-particles, it yet resulted in poor interface maximization and temperature reduction in form of conventional thick film cathode application.