Efficient and robust ceramic interconnects based on a mixed-cation perovskite for solid oxide fuel cells

Abstract

To achieve a required output voltage, a solid oxide fuel cell (SOFC) stack has multiple unit cells connected in series through interconnects (ICs). A dual-layer IC film comprising p- and n-type conducting perovskite oxides is considered to be a promising design in terms of electrical properties and stability; however, its fabrication is materials-intensive and time-consuming. Here, we propose an advanced design of a single-layer IC film inspired by the interfacial nature of the dual-layer IC film. Based on an understanding of cross-diffusion phenomena across the interface between Sr0.7La0.2TiO3 and La0.8Sr0.2MnO3 during the co-sintering process revealed by secondary ion mass spectroscopy, we design and synthesize mixed-cation perovskite oxides, (Sr0.6La0.4)0.9(Ti1–xMnx)O3 (SLTM), for IC applications in SOFCs. Among various compositions, Ti-rich SLTM (x = 0.25) shows high sinterability, leading to the formation of a thin, gas-tight IC film on a porous anode support via simple screen printing and sintering. When exposed to both reducing and oxidizing atmospheres, the fabricated SLTM-IC film is highly conductive and remains stable during continuous operation. The ceramic IC design proposed in this work may provide great benefits in terms of reduced costs of IC materials and fabrication, while maintaining the IC performance required for SOFCs.