Study On Anode Structure And Cell Performance For Intermediate Temperature Solid Oxide Fuel Cells

Solid oxide fuel cell(SOFC) is an energy conversion device with high efficiency and cleanness. However, the necessity for high operating temperatures has resulted in high costs and materials compatibility challenges. As a consequence, significant effort has been devoted to the development of intermediate-temperature (below 850℃) SOFCs. In SOFC, the anode structure has a great influence on performance of anode and its single cell. In this study, performance of Ni/Ni-GDC double-layer anodes and their single cells, effects of anode functional layer thickness and composition on performance of Ni-GDC double-layer anodes and their single cells, effect of anode pores on Ni-GDC anodes and their single cells were studied.Performance of double-layer anodes with Ni as anode outer layer and Ni-GDC with different composition as inner layer were studied. The research results are as follows:the porosities and conductivities of Ni/Ni-GDC double-layer anodes after reduction increase with increase of Ni content in anode inner layer, and their conductivities are all higher than the conductivity of Ni-GDC single-layer anode. At 700℃, the peak power densities of single cells with NiO-GDC anode inner layer component ratio of 5:5、7:3、9:1 are all higher than that of single cell with Ni-GDC single layer anode. Adding a Ni-GDC composite anode layer between the Ni anode outer layer and GDC electrolyte layer can improve cell’s performance with limits.The effect of anode functional layer(AFL) thickness on performance of Ni-GDC double-layer anodes and their single cells was studied. The results show that: 60%NiO+40%GDC anode powers adding a certain amount graphite as anode supported layer(ASL),40%NiO+60%GDC as AFL, the AFL with a certain thickness range can improve the electrochemical performance of cells. Both the open circuit voltages and the peak power densities of all the single cells increase in the order of AFL thickness 120 μm,0μm,80 μm,40μm,60μm. Cell with a 60μm thick AFL has the best electrochemical performance, its peak power density at 700℃ is 41% higher than that of the cell without AFL. The study of effect of AFL composition on performance of Ni-GDC double-layer anodes and their single cells indicate that:for a series NiO-GDC double-layer anodes and their single cells with 60%NiO+40%GDC anode powers adding a certain amount graphite as ASL and NiO-GDC with component ratio of 4:6,5:5,6:4,7:3,8:2 respectively as AFL, from 600℃to 700℃, single cell with AFL component ratio of 7:3 has the highest electrochemical performance, its peak power density at 700℃ is 41% higher than that of the cell without AFL. Single cell with AFL component ratio of 5:5 has the lowest electrochemical performance.Effects of size and distribution of anode pores on performance of Ni-GDC anodes and their single cells were studied. The results show that:the smaller the anode pores are, the more uniformly the anode pores distribute, the higher the conductivity of anode is, the better the electrochemical performance of its single cell is. The anode fabricated via water bath mixing 40 nm graphite with NiO-GDC anode powers has the highest conductivity after reduction, and its single cell has the best electrochemical performance. The peak power densities of it are 0.173 W·cm-2,0.310 W·cm-2,0.445 W·cm-2 at 600℃,650℃ and 700℃ respectively.