Effects Of Adding Heterogeneous MgO Particles And Electrospun Fibers On The Conductivity Of CeO₂-based Electrolytes

Recently,developing novel ox ygen ion solid electrolytes for intermedium temperature solid oxygen fuel cells and oxygen sensor have become a research hotspot.Among the many ox ygen ion solid electrolytes,cerium oxide-based solid electrolyte materials with fluorite structure have attracted researchers more attention due to the high ox ygen ion conductivity in the mid-temperature range.In this paper,Ce_0.8Sm_0.2O_1.9(SDC)with the highest ionic conductivity in Sm-doped Ce O₂ system as the matrix material,then Ce O₂-based electrolyte was prepared b y conventional sintering and spark plasma sintering(SPS)after addition Mg O particles and SDC fibers into the matrix material,the phase composition,micro-morpholog y and electrical conductivity were analyzed by XRD,SEM,TEM,EDS and EIS to explore the influence of the addition of heterogeneous phase Mg O and SDC fibers on the electrical conductivity of Ce O₂-based solid electrolyte.Ce_0.8Sm_0.2O_1.9(SDC)-x Mg O(x=0,5,10,15,20 mol%)composite powders were prepared by sol-gel method,Ce_0.8Sm_0.2O_1.9(SDC)-x Mg O(x=0,5,10,15,20mol%)composite ceramics were obtained by SPS sintering(sintered at 1100^°C for10 min).SDC-Mg O composite ceramics are mainly composed of SDC and Mg O phases,and Mg O is interspersed among SDC grains in the form of lamellar structure.With the increase of Mg O content,the conductivity shows a trend of first increasing and then decreasing,it is optimal to add 5 mol%Mg O to the SDCmatrix.The conductivity of SDC-5%Mg O composite ceramic sample is 2.76×10^-2 S/cm at 650^°C,which is 9.65%higher than that of pure SDC.Ce_0.8Sm_0.2O_1.9(SDC)-x Mg O(x=0,5,10,15,20 mol%)composite powders were prepared by sol-gel method,Ce_0.8Sm_0.2O_1.9(SDC)-x Mg O(x=0,5,10,15,20mol%)composite ceramics were obtained by conventional sintering(sintered at1400^°C for 5 h).SDC-Mg O composite ceramics are mainly composed of SDC and Mg O phases,and Mg O is dispersed among SDC grains in the form of polygonal grains.The grain size of SDC-Mg O composite ceramics remains stable,and the average grain size is within 628?654 nm.With the increase of Mg O content,the conductivity shows a trend of first increasing and then decreasing,it is optimal to add 5 mol%Mg O to the SDCmatrix.The conductivity of SDC-5%Mg O composite ceramic sample is 2.66×10^-2 S/cm at 650^°C,which is 7.69%higher than that of pure SDC.Ce_0.8Sm_0.2O_1.9(SDC)powders and Ce_0.8Sm_0.2O_1.9(SDC)fibers were prepared by sol-gel method and electrospinning method,respectively.Mix SDC fibers and powers with mechanical agitation.SDC-x Fiber(x=0,20,40,60 wt%)ceramics were obtained by SPS sintering(sintered at 700°C for 7 min).SDC fiber/powder ceramics are mainly composed of SDC phase,and SDC fibers is interspersed among the grains of SDC.With the increase of SDC fibers content,the conductivity shows a trend of first decreasing and then increasing,however,the conductivity of ceramic samples with SDC fibers was lower than that of pure SDC.