Study On Microscopic Mechanism Of The Conduction Of CeO₂-based Electrolyte Modified By Metal Oxide

In this paper,composite Ce O₂-based electrolyte is taken as the main research object,metal oxide is used to compound with Ce O₂-based electrolyte material,to explore the influence of metal oxide on the conductivity of Ce O₂-based electrolyte,and to conduct experimental research on how to improve the performance of Ce O₂-based electrolyte.Firstly,the solid electrolyte Ce_0.8Gd_0.2O_1.9doped with Gd₂O₃was prepared by solid-state blending method..GDC+x Zn O?x=0.5mol%,1.5mol%,5mol%,10mol%,15mol%?composite electrolyte materials were prepared by the same method.At the same sintering temperature,XRD phase analysis,SEM morphology observation,AC impedance spectrum analysis and single cell output power test of GDC+x Zn O show that GDC+0.5Zn O and GDC+1.5Zn O have good single-phase structure of cubic fluorite,while GDC+5Zn O,GDC+10Zn O and GDC+15Zn O have additional peaks.This can be attributed to the existence of Zn O with hexagonal wurtzite structure as the second phase.From the analysis of AC impedance spectrum,it is found that the conductivity of GDC decreases with the composition of Zn O.In the GDC of composite Zn O,the conductivity of GDC+10Zn O is the highest.The single cell power density of GDC+x Zn O electrolyte is significantly higher than that of GDC.At 800?,the single cell power density of GDC is 115m W/cm²,and the single cell power density of GDC+10Zn O is 189m W/cm²,which is due to the obvious proton conduction of Zn O as a semiconductor.The composite electrolyte materials of GDC+10Zn O+x Fe₂O₃?x=0.5mol%,1mol%,2mol%?were prepared by solid-state blending method.XRD,SEM,ac impedance spectrum and single cell output characteristics were used to characterize the phase,crystal morphology,conductivity and power density of the GDC+10Zn O+x Fe₂O₃ electrolyte.The results showed that the GDC+10Zn O+x Fe₂O₃ samples presented a good cubic fluorite structure,and no second phase of Fe was observed.Fe2O3 further promoted the grain growth of GDC+10Zn O.Compared with GDC+10Zn O,the crystal cells of the three samples all increased,while the cell parameters of these three samples first decreased and then increased.The results of ac impedance spectroscopy showed that the conductivity of GDC+10Zn O+x Fe₂O₃ electrolyte was significantly improved compared with that of GDC+10Zn O,mainly due to the improvement of grain boundary conductivity.At the same time,GDC+10Zn O+x Fe₂O₃ single battery also shows better output power,among which the Fe₂O₃ compound mole ratio of 1%GDC+10Zn O+1Fe₂O₃ single cell has the best performance,and the power density reaches215.8m W/cm².