Powder Characteristics And Fuel Cell Performances Of La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-? Powders Prepared By Spray Pyrolysis

Solid oxide fuel cell(SOFC)has quite a lot of advantages,such as high energy conversion efficiency,low pollution,solid structure and so on.And thus has become a hotspot of researches these days.Commonly used Y2O3 doping ZrO2(YSZ)electrolyte material only shows a high ionic conductivity under high temperatures(around 1000?),this limited the choice of other materials in SOFC system,and also shortened the service life of the cell.Recent study showed that doped LaGaO3 material with perovskite structure has a high ionic conductivity in intermediate temperatures,and its electric conductivity could be ignored over a wide range of oxygen pressure.This makes it perfect choice for electrolyte material in SOFCs.Many experiments proved that Sr,Mg doped LaGaO3 is a promising electrolyte material,even may replace the role of ZrO2-based solid oxide electrolyte material.In this study,we chose the method of ultra spray pyrolysis to synthesize LSGM precursors.The concentration of the starting solution was divided into five groups:0.01mol/L,0.05mol/L,0.1mol/L,0.15mol/L and 0.2mol/L,respectively.The phase compositions of the precursors were detected by X-ray Diffraction(XRD),microstructure of the precursors was observed by Scanning Electron Microscope(SEM).The particle size and distribution were measured.The relationship between starting solution concentration and the powder properties were studied.The relative density was calculated,the sintering property of LSGM material was studied.Pt was painted to LSGM electrolytes as the anode and cathode material,the fuel cell property of the single cell was tested.The result was compared with other related researches.The LSGM precursors were successfully prepared by ultra spray pyrolysis.The XRD patterns of the precursors showed many peaks with rather low intensities,the powders were composed of many inter-phases,besides LaGaO3,there were SrLaGa3O7,SrLaGaO4 and LaaGa2O9.The XRD patterns of powders under 800? calcinations showed almost the same,except that the relative intensity of the impurity phase and LaGaO3 phase was changed,as a result of the increase in the content of LaGaO3 phase.The XRD patterns of 1450? calcined powders showed pure LSGM peaks,no impurities were detected.It could be seen in the SEM pictures that all of the LSGM precursor powders showed a spherical particle shape,regardless of their difference in concentration of starting solutions.No big differences in particle shape were found between these pictures,the size ranged from 0.57 to 1.19?m.From the average particle size picture,the average particle size showed the tendency to increase with the increase of solution concentration.All of the sintering bodies'relative densities were over 90%,however,no big differences have been found between each other,despite of the difference in concentration.This proved that the starting solution concentration has little influence on the density of electrolyte obtained later.Sintering the pellets at different temperatures,the density reached to maximum when sintered at 1450?.Thus,1450? was the best sintering temperature for LSGM material.The fuel cell property was tested under 800?.The single cell had a circuit voltage of 1.1V,close to its theoretical value.The maximum power density was 72.07mW/cm2.After comparing with others' research,it was clear that optimizing the selection of electrode materials,the performance of the single cells with LSGM electrolytes could be further improved.