Study Of The Preparation And Performance Of The Anode Materia La Doped SrTiO₃ For Solid Oxide Fuel Cell

Along with the growing energy depletion and the worsening environmental pollution,the solid oxide fuel cell(SOFC)- a clean and efficient energy conversion devices caused widespread attention.In practical aspects, SOFC shows a strong development potential and has a wide application market, the development of which is the trend. Anode is one of the core components of the SOFC. Based on the theory of the three-phase interface, nanopowder anode LaxSr1-xTi O3-δ(LST), nanopowder-based and nanofiber-based composite anode were prepared, by which the impact of the ionic conductivity of the material, electronic conductivity of the material and the microstructure of the electrode on the performance of the electrode were reached.Anode material La0.3Sr0.7Ti O3-δ(LST37) was prepared by the sol-gel method. On the basis of the prepared of the material LST37, LST37-GDC(LST37:GDC=1:0, 0.8:0.2, 0.6:0.4, 0.4:0.6, 0.2:0.8, 0:1)composite electrodes were prepared by adding an ion conducting phase Gd0.2Ce0.8O1.9(GDC). At 1000 ℃, when the mass percent of the composite GDC was 0, 0.2, 0.4, 0.6, 0.8 and 1, polarization resistance(Rp) of the LST37-GDC composite electrode respectively was 13.34Ω, 2.03Ω, 0.95Ω, 0.84Ω, 0.49Ω and 0.15Ω. The addition of GDC, which improved the ionic conductivity of the electrode and increased the surface area of the three phase interface, improved the electrochemical properties of electrodes. The ion conductivity had a significant effect on the performance of the electrode: the higher the ionic conductivity was, the better the performance of the electrode was.Based on the sol-gel technology, anode materials LaxSr1-xTi O3-δ(x=0.1, 0.2, 0.3, 0.4, 0.5, referred LST19, LST28, LST37, LST46, LST55) were prepared, which were doped with different amounts of La. When the materials were prepared to form the electrode, at 1000℃, polarization resistance(Rp) of LST19, LST28, LST37, LST46 and LST55 electrode respectively were 23.14Ω, 17.25Ω, 13.79Ω, 7.74Ω and 21.53Ω. With the increasing of La doping amount, LST electrode the performance of the LST electrode declined after rising first; when the Moore doping amount of La was 0.4 the performance of the LST electrode was the best. Combination with the research reports on the influence of the electronic conductivity of LST materials of the La doping amounts, and in accordance with the analysis of nuclear magnetic resonance(NMR), which tested the LST materials after the reduction in the high temperature, the influence of La doping on the electronic conductivity of the LST was reached. The electronic conductivity had an effect on the properties of electrode materials: the electronic conductivity material is higher, the better the performance of the electrode materials. NMR tests could also be a preliminary evidence that the reduction mechanism of the reduction of Ti4+ also could take charge from the domain distribution mode, which was greatly helpful to improve the electronic conductance of the material, and which was likely to be the key factor of the best electrochemical performance of LST46 material.Based on the reach of the nanopower-based composite electrode LST37-GDC, the nanofiber material LST37 was synthesized by electrospinning technique, and the nanofiber-based composite electrode LST37-GDC(LST37:GDC=1:0, 0.847:0.153, 0.708:0.292, referred LST37-si-0, LST37-si-0.153, LST37-si-0.292) were prepared by impregnating the prodromal solution of the GDC. At the same time, the nanopowerbased composite electrode LST37-GDC(LST37:GDC=1:0, 0.847:0.153, 0.708:0.292, referred LST37-fen-0, LST37-fen-0.153, LST37-fen-0.292) were prepared by adding an ion conducting phase GDC. At 1000 ℃, polarization resistance(Rp) of LST37-si-0, LST37-fen-0, LST37-si-0.153, LST37-fen-0.153, LST37-si-0.292 and LST37-fen-0.292 composite electrode were 18.11Ω, 13.34Ω, 3.26Ω, 3.89Ω, 0.67Ω and 2.85Ω. The performance of nanofiber LST37 electrode was not as good as nanopowder LST37 electrode, but with the increasing amount of GDC composite, The performance of nanofiber-based composite electrode was getting better than the nanopowder-based composite electrode. The structure and microstructure of the electrode had a great influence on the electrode performance, which was the combined effect of the electrode structure, the electrode porosity and the thermal expansion difference.