The Preparation And Performance Of Composite Cathode SrCo_0.8Ti_0.15Nb_0.05O_3-?-SNDC For SOFC

Solid Oxide Fuel Cell?SOFC?has caused wide public concern.Intermediate temperature solid oxide fuel cell?IT-SOFC?can improve stability of SOFC,reduce the running cost of battery,increase the optionality of system material.Developing a kind of cathode material with excellent performance in low temperature is a important part of lowering the working temperature of SOFC.SrCo_0.8Ti_0.15Nb_0.05O_3-??SCTN?with cubic perovskite structure has extremely high conductivity,oxygen permeability and stable structure.For the sake of expanding the length of cathode electrolyte and air Three-phase boundary to improve the performance of cathode,different proportions of Sm_0.075Nd_0.075Ce_0.85O_2-??SNDC?are doped into SCTN becoming SCTN-SNDC composite cathode material.And the feasibility and electrochemical performance of SCTN-SNDC composite cathode material has been researched.SCTN cathode powder is synthesized using solid phase method.By the method of glycine-nitrate combustion,the synthesis of SNDC has been done.Then,groups of different proportion of SCTN-SNDC composite cathode are prepared via mechanical mixture method.Their Electrochemical Impedance Spectroscopy?EIS?and scanning electron microscope?SEM?were tested to analysis their electrochemical performance and Investigate their phase structure.The results of X-ray diffraction?XRD?show that there is no new diffraction peak by sintering the SCTN-SNDC composite cathode at 1150?for 10 hours,which means the SCTN and SNDC maintain their phase structure in the high temperature.Chemical compatibility between SCTN and SNDC prove the feasibility of composite cathode.The result of EIS shows that the best sintering temperature of composite cathode is 850?.In addition,by doping SNDC,the impedance of cathode firstly decrease and then increase,which means doping SNDC can improve the performance of cathode and there is a best doping proportion.The AC impedance spectroscopy of some of symmetrical half-cells made up of SCTN and SNDC with different proportion were measured.The result shows that AC impedance of half-cell reduced to the minimum,is 0.132?·cm²,when 30%of SNDC was doped into SCTN.Proper porosity and good three-dimensional network structure was observed by the way of scanning electron microscope when cathode with 30%SNDC doped was sintered 5h at850?.The maximum power density of single cell is 497.63 mW/cm² tested at 800?.In comparison with the single cell with cathode only containing SCTN which the maximum power density is 268.51 mW/cm²,the maximum power density of the composite cathode increase 229.12mW/cm².