Effect Of Metal Oxide On The Microstructure And Properties Of CeO₂ Electrolyte

Solid oxide fuel cell(SOFC)is a device to convert chemical energy of fuel directly into electrical energy,which has the advantages of no pollution,no noise and wide adaptability of fuel.The most critical component of SOFC is the electrolyte.The performance of electrolyte materials directly affects the battery operating temperature and power density.The high operating temperature of SOFC,on the one hand,decreased stability of battery components,on the other hand,greatly limited the material selection of the battery pack,resulting in costs increased.Therefore,it is necessary to develop an electrolyte material with good properties at intermediate temperature.In this paper,Gd2O3 and In2O3 co-doped CeO2 electrolyte powders were prepared by sol-gel combustion method,and XRD,SEM,thermal expansion coefficient,space potential difference and electric conductivity of the samples of Ce0.9Gd0.1-xInxO2-?(x = 0-0.05)with different doping quantity were investigated to discuss the influence rule of different doping amount on microstructure and properties of electrolyte.The effects of different sintering temperature and different holding time on the microstructure and properties of the Ce0.9Gd0.08ln0.02O2-6 electrolyte were investigated to obtain electrolyte materials with high perforences at intermediate operating temperature.The research result of the influence of different doping amount on the microstructure and performance of Ce0.9Gd0.1-xInxO2-?(x = 0-0.05)electrolyte indicates that the sol-gel combustion method can be used to prepare Ceo.9Gd0.1-xInxO2-?(x = 0.01?N0.05)of In and Gd doping CeO2 electrolyte evenly,and the second phase is not precipitated.The doping element In improves the sintering performance of Ce0.9Gd0.1-xInxO2-? electrolyte.With the increase of In doping content in the electrolyte,the grain size of the electrolyte increases.The spatial potential difference of the electrolyte at the grain boundary decreases first and then increases;Space potential difference of the specimens of Ce0.9Gd0.08In0.02O2-?electrolyte is the smallest,of which total conductivity is maximal at low operating temperature.At higher test temperatures,the double-doped electrolytes show better ionic conductivity and electrochemical performance than that of the single-doped electrolyte.The ionic conductivity of C.e0.9Gd0.08In0.02O2-? electrolyte is 21.4%higher than that of Ce0.9Gd0.1O2-? electrolyte at the temperature of 800 ?.The research result of the influence of different sintering temperature on the microstructure and properties of Ce0.9Gd0.08In0.02O2-? shows that the average grain size and space potential difference of the samples of Ce0.9Gd0.08ln0.02O2-? electrolyte are affected by the sintering temperature.With the sintering temperature increasing,the grain size increases,and the space potential difference increases,and the grain boundary conductivity decreases in low temperature range.When the sintering temperature is 1300 ?,the total electrical conductivity reaches the maximum value in the high test temperature region.The research result of the influence of different sintering time on the microstructure and properties of Ce0.9Gd0.08In0.02O2-s electrolyte shows that the optimum sintering time of Ce0.9Gd0.08ln0.02O2-? electrolyte is 3h.When the sintering holding time is less than 3h,the grain size of the electrolyte is smaller,which results in O2 moveing difficult,and when the sintering holding time is high than 3h,the oxygen vacancy can not be enough provided inside the electrolyte grain,which decreses the total conductivity.The optimum sintering process of Ce0.9Gd0.08In0.02O2-? electrolyte is 1300 ? and holding for 3h.After this treatment,the conductivity of the Ce0.9Gd0.08In0.02O2-? electrolyte is 0.019S/cm2 at 800 ?.The maximum power density of the single cell prepared with Ce0.9Gd0.08In0.02O2-?electrolyte is 553 mW/cm2 at 700 ?.