A high performance interconnecting ceramics for solid oxide fuel cells (SOFCs)

摘要

In order to improve the electrical conductivity and sintering capability of doped lanthanum chromite, the well-known interconnecting ceramic for solid oxide fuel cells (SOFCs), the composite material system La0.7Ca0.3CrO3-delta (LCC)+x wt-%Sm0.2Ce0.8O1.9 (SDC) (x=0-10) has been investigated. The high sintering activity LCC and SDC powders used in this study were prepared by an auto-ignition process and the composite materials were made by pressing the mixture of LCC and SDC powders and then firing. The relative density of pellets sintered at 1400 degrees C for 4 h in air was 97.4% for only LCC powder and increased with the increase of SDC content, reaching 98.7% when the SDC content was up to 10%. The electrical conductivity of the samples dramatically increased with SDC addition and reached maximal value of 687.81 S cm(-1) in air at 800 degrees C for the sample with 5% SDC content, which is 38.7 times higher than that of pure LCC (17.77 S cm(-1)). The conductivity in pure H, at 800 degrees C was 3.57 S cm(-1), which is also higher than the pure LCC ceramics (2.5 S cm(-1)). The average thermal expansion coefficient (TEC) at 30-1000 degrees C in air increased slightly with SDC content, ranging from 11.12 x 10(-6) K-1 to 12.46 x 10(-6) K-1. We assume that there is negligible oxygen ion conduction. Such an assumption makes us state that it is still an electronically conducting ceramic. The above results demonstrate that it is a very promising interconnect material for intermediate temperature SOFCs. (c) 2006 Elsevier B.V. All rights reserved.