The Property Improving And Optimizing Of LaCo_0.6Ni_0.4O_3-δ Cathode Contact Material For Intermediate Temperature Solid Oxide Fuel Cells

The cathode contact materials(CCM) between cathode and interconnect earn its importance in IT-SOFC, which playing a critical role in collecting electric current and cushioning internal forces especially in those stacks with metal interconnect. However, the current researches of the CCM are still in the stage of exploration. Although Platinum is widely researched as its high electric conduction ability, but the high price makes it is impossible for commercial application.The traditional perovskite ceramic materials have good electric conductive ability. however, their compatibility with metal interconnect is required to be developed by further study. Thus, finding a material with both good performance and affordable price is important for researchers.In this article, a kind of perovskite ceramic based material had been studied. The researcher use Ni doped LaCoO3 by taking the advantage of optimizing the thermal expansion coefficient and keeping the high electrical conductivity of perovskite ceramic materials. LCN is prepared through the polymeric steric entrapment precursor route with polyvinyl alcohol(PVA) as the entrapment agent and then calcined at 800°C and 1100°C for 3h respectively. With the XRD, SEM and grading analysis, which proved the purity of the ascalcined LCN and synthesized some uniform powder with grain diameter 0.25μm in 800°C, 1.10μm in 1100°C by PVA method. This LCN64 pervoskite material has a conductivity which is higher than 600 S cm-1 between the temperature of 600°C and 800°C. Therefore, LCN64 can be considered as potential contact layer materials for IT-SOFC.This research is aimed at optimizing LCN64 CCM from two aspects:A multilayer contact opproach for use in IT-SOFC include at least 3 layers( fine//coarse//fine) of an electrically conductive perovskite which had a better contacting with metal interconnect. And the coarse layer is a stress relief layer, which could fracture during thermal cycling to relieve internal stress, the conductivity remained and prevented further mechanical damage from more critical interfaces.Silver-perovskite composites with LCN64 is evaluated as the contact material, which is tested during isothermal exposure at 750°C in air for about 50 h. The area specific resistances of the test specimens were highly dependent on the percentage of Silver.