Research On The Influence Of Precursor Particle Size Distribution On The Electrical Properties Of Doped CeO₂-based Oxygen Ion Conductor

Solid Oxide Fuel Cell?SOFC?,as a new-type of energy conversion device,can directly and efficiently convert chemical energy into electrical energy.Compared to the traditional energy conversion device,SOFC has some promising applications in various fields owing to its great advantages,such as high energy conversion rate,strong fuel adaptability,low cost,environmental friendliness and practicability,all-solid battery structure and so on.As one of the core components,electrolyte material has a significant influence on the operating temperature and performance of the fuel cell.Compared with other conventional electrolyte materials?YSZ,La GaO3,etc.?,CeO₂-based electrolyte materials have the advantages of simple sample preparation and high conductivity,which have been widely concerned by experts and scholars from various countries.In this paper,we selected the doped CeO₂ as the electrolyte material to research the effect of precursor particle size distribution on the electrical properties of GDC oxygen ion conductor and the applicability of the brick layer model.In this paper,Gd doped CeO₂-based materials were prepared by glycine-nitrate method.GDC powders were calcined at different temperatures by controlling variables,and mixed with different mass ratios to adjust the distribution of precursor particle size.The phase composition and morphology of mixed GDC samples were characterized by X-ray diffraction and scanning electron spectroscopy.The influence of the selective distribution of grain boundary?GB?impurities and GB density caused by the uneven distribution of precursor particle size on the GB electrical properties of GDC electrolyte was studied via AC impedance.The GB conductivity of GDC samples decreased significantly once a small amount of 1200 ^oC powder contained in precursor.This is because the selective distribution of GB impurities leads to the uneven GB conductivity,resulting in the inhomogeneous distribution of GB current density,which leads to significant increase in GB resistance,and brick layer model is not applicable.Meanwhile,GDCx samples with different Gd doping concentrations were also synthesized with different mass ratios.The relationship between particle size distribution and the conductivity of GDCx samples was measured by AC impedance spectroscopy,and the influence of Gd doping concentrations on the GB electrical properties of GDCx electrolyte was researched.The results confirmed that the selective distribution of GB impurities caused by precursor particle size distribution is the main reason for the significant change of GB conductivity of GDCx samples with different mass ratios,not the GB density and space charge potential.