Novel composite interconnecting ceramics La 0.7Ca 0.3CrO 3− δ/Ce 0.8Sm 0.2O 1.9 for solid oxide fuel cells

Abstract

In this paper, an interconnecting ceramic for solid oxide fuel cells was developed, based on the modification from La 0.7Ca 0.3CrO 3− δ by addition of Ce 0.8Sm 0.2O 1.9. It is found that addition of small amount Ce 0.8Sm 0.2O 1.9 into La 0.7Ca 0.3CrO 3− δ dramatically increased the electrical conductivity. For the best system, La 0.7Ca 0.3CrO 3− δ + 5 wt.% Ce 0.8Sm 0.2O 1.9, the electrical conductivity reached 687.8 S cm −1 at 800 °C in air. In H 2 at 800 °C, the specimen with 3 wt.% Ce 0.8Sm 0.2O 1.9 had the maximal electrical conductivity of 7.1 S cm −1. With the increase of Ce 0.8Sm 0.2O 1.9 content the relative density increased, reaching 98.7% when the Ce 0.8Sm 0.2O 1.9 content was 10 wt.%. The average coefficient of thermal expansion at 30–1000 °C in air increased with Ce 0.8Sm 0.2O 1.9 content, ranging from 11.12 × 10 −6 to 12.46 × 10 −6 K −1. The oxygen permeation measurement illustrated a negligible oxygen ionic conduction, indicating it is still an electronically conducting ceramic. Therefore, this material system will be a very promising interconnect for solid oxide fuel cells.