基于La0.6Sr0.4CoO3-δ原位成相的中温固体氧化物燃料电池梯度阴极制备与表征

Fabrication and Characterization of Functionally Graded Cathodes Based on in-situ Formed La(0.6)Sr_(0.4)CoO_(3-δ) for Intermediate Temperature SOFCs

采用溶胶-凝胶法制备出匀质、比表面积高的La0.6Sr0.4CoO3-δ(LSC)阴极前驱体粉体以及其与Ce0.8Gd0.2O2-δ(CGO)的复合阴极粉体,并通过TGA、XRD和BET等手段对粉体进行表征;结果表明:LSC阴极前驱体经在高温氩气中煅烧和在空气中850℃退火2 h后能够完成成相,这相应于功能梯度阴极的制备和SOFC电池堆工作前的退火条件,LSC/CGO和LSC分别沉积在NiO/YSZ阳极支撑的SOFC半电池CGO阴极阻挡层上,功能梯度阴极在氩气中分别在900、950、1000℃温度下进行烧结,SEM和EDX分析发现功能梯度阴极与CGO阻挡层结合良好,但SrZrO2可在YSZ-CGO界面层中形成。LSC原位成相后的单电池性能测试表明,输出性能随着烧结温度的降低而提高,相比而言900℃为最佳烧结温度。

Precursor powders of La0.6Sr0.4CoO3-δ（LSC） and composite powders of LSC precursor and Ce0.8Gd0.2O2-δ（CGO） were prepared by Sol-Gel process. The precursor powders of LSC were characterized by TGA, XRD, BET and exhibited homogeneity and high specific surface area. XRD analysis indicated that single phase of LSC can be formed after calcination at high temperature in Ar and annealing at 850℃ for 2 h in air, which corresponds to the fabrication and annealing condition of functionally graded cathode before SOFC stack operation. Functionally graded cathode of LSC/CGO precursor and LSC precursor were sintered at 900-1000℃ in Ar, which were depos-ited on NiO/YSZ anode supported half cell with YSZ as electrolyte layer and CGO as barrier layer. Microstructural analysis by SEM and EDX indicated that graded cathode contacted well with CGO layer. It was found that SrZrO3 was formed at the YSZ-CGO boundary. The test of single SOFC cells with in-situ formed LSC showed that cell performance was improved with decrease of the sintering temperature. In comparison, the best cell performance was achieved at the sintering temperature 900℃.