Controllable Preparation And Ionic Conductivity Of Zirconia-based Nano Solid Electrolytes

The solid oxide fuel cell(SOFC)is all-solid-state electrochemical device,which converts the chemical energy directly into electrical energy and non-polluting.The electrolyte is the core component of SOFC.Due to good chemical stability,mechanical properties,excellent oxidation and corrosion resistance,ZrO2 solid electrolytes have been gradually applied to SOFC,Sensors and other fields.The microstructure of ZrO2 base solid electrolyte is one of key factors affecting the conductivity of oxygen ions.In addition,high sintering and working temperature are the main bottlenecks restricting its popularization.Therefore,it has become central point in the preparation of medium and low temperature solid electrolytes that regulating microstructure,reducing temperature and improving the ionic conductivity.Zirconium oxychloride as zirconium source,YxZr1-xO2 and BixY0.04Zr0.96-xO2 powder and solid electrolyte were prepared by SDS/C10H22O/H2O layered liquid crystal template introducing bismuth nitrate and yttrium nitrate in this paper.The influence of different reactant doping amount on the stability of template layered phase structure determined by polarizing microscope.On the basis,the influence of single doping or co-doping of yttrium nitrate and bismuth nitrate on the crystal form,particle size distribution,morphology and conductivity of solid electrolyte were investigated,determining the optimal doping amount of solid electrolyte with good conductivity.In addition,the conductivity of BixY0.07Zr0.93-xO2 solid electrolyte prepared by adopting bismuth oxide as bismuth source was studied.Microstructure of powder and conductivity of solid electrolyte were characterized by X ray diffraction analysis,scanning electron microscope and the AC impedance spectroscopy and so on.The results are as follows:1.In order to determine stability of the template,observing layered liquid crystal template of SDS/C10H22O/H2O before and after adding 5mol/L ammonia water by means of polarizing microscope.The result showed that the lamellar structure of SDS/C10H22O/H2O system are stable in the range of 3-7 mol%YxZr1-xO2,1-5 mol%BixY0.04Zr0.96-xO2and 1-3 mol%BixY0.07Zr0.93-xO2,respectively.2.On the basis of stable layered liquid crystal template,powder with doping amount of 3-7 mol%YxZr1-xO2 and 1-5 mol%BixY0.04Zr0.96-xO2 were prepared by calcining 2 h of 700? with yttrium nitrate,bismuth nitrate and zirconium chloride as raw materials.The result showed that microstructure of powder is tetragonal phase,monodisperse spherical morphology with an average particle size of less than 15 nm.3.Yx2r1-xO2 and BixY0.04Zr0.96-xO2 solid electrolytes were prepared by sintering 2 h of 1200? and 1100?,respectively.For YxZr1-xO2 solid electrolyte,ionic conductivity of yttrium nitrate doped with 4 mol%is relatively optimal,3.26×10-6 S/cm,corresponding activation energy 0.82 eV.Introducing Bi(NO3)3 into YxZr1-xO2 solid electrolytes,bismuth nitrate with doping amount of 3 mol%has good conductivity,7.41 ×10-5 S/cm,and the minimum activation energy 0.72 eV.The comparison showed that sintering temperature is lower 100? than YxZr1-xO2,conductivity increases by an order of magnitude after the introduction of Bi(NO3)3 under the same conditions.4.The solid electrolyte was prepared from bismuth oxide,yttrium oxide and zirconium oxychloride.The results showed that suitable doping amount of yttrium oxide and bismuth oxide is 7 mol%,1 mol%,respectively.