| Solid oxide fuel cell (SOFC) has several advantages, such as higher energy conversion efficiency, low pollution and all solid structure, which has been the hotspot of scientific research today. In order to reduce the limitation of the materials used in high temperature SOFC, it is important to investigate a new type of electrolyte with high ionic conductivity in intermediate temperature (600-800℃).Study shows that doped LaGaO3 electrolyte shows high ionic conductivity in intermediate temperature while its electronic conductivity can be overlooked in wide oxygen presssure. This makes doped LaGaO3 perfect electrolyte for intermediate temperature solid oxide fuel cell. There were many reports about the synthesis of doped LaGaO3 power by chemical methods and solid state reaction, which can not achieve the anticipated results. So it needs to find a new simple method to prepare doped LaGaO3 powder with high ionic conductivity and purity.For the key problems and theory in the synthesis process of doped LaGaO3, we studied the different synthesis methods and then improved them, also the properties of which we prepared were mainly studied. This paper mainly includes:Microwave heating was first used to assist the wet chemical synthesis of doped LaGaO3 electrolyte. Traditional Pechini method and microwave-assisted Pechini method were used to prepare La0.8Sr0.2Ga0.83Mg0.17O2.815 ( denoted as LS0.2GM0.1 ) , La0.9Sr0.1Ga0.8Mg0.2O2.85 ( denoted as LS0.1GM0.2 ) powder and the advantages of microwave heating were elaborated. Then Measurement techniques were used to characterize the quality of the electrolyte powders and the possible reaction mechanism was analyzed. It proves that uniform doped LaGaO3 powder can be prepared by the microwave-assisted wet-chemical method.For the advantages of microwave heating, we continued to study the specific process of microwave-assisted combustion method, microwave-assisted PVA solution polymerization method and improved microwave-assisted solution polymerization method. By improvement, we prepared pure (mesured by XRD)LS0.1GM0.2 after calcination at 1100℃for 6h,La0.9Sr0.1(Ga0.9Co0.1)0.8Mg0.2O2.85(denoted as LS0.1GCM0.2)after calcination at 1300℃for 6h and LS0.2GM0.17, La0.8Sr0.2(Ga0.9Co0.1)0.83Mg0.17O2.815 (denoted as LS0.2GCM0.17) after calcination at 1400℃for 9h.For the properties of the electrolyte in SOFC, we studied the sintering, thermal expansion, chemical compatibilities, thermal stability and electrical properties of doped LaGaO3 electrolyte, including:The sintering temperature of LS0.2GM0.17 , LS0.1GM0.2 , LS0.2GCM0.17 and LS0.1GCM0.2 electrolytes were 1450℃, the densities of which were the highest value at this temperature; At intermediate temperature, the conductivities of the studied electrolytes were higher than that of YSZ. The conductivity of LS0.2GCM0.17 was 0.127 S/cm at 850℃; The thermal coefficients of electrolytes were approached to the usual electrode materials in SOFC; The cathode material La0.8Sr0.2Co0.8Fe0.2O3(denoted as LSCF)and insulation layer material Ce0.6La04O2(denoted as LDC)had good chemical compatibilities with the electrolytes we studied.The unit cell we organized was Ni-LDC(10um)/LDC(20 um)/LS0.2GCM0.17(0.8mm)/LSCF-LS0.2GCM0.17(20um) with flat-plate structure. The efficient area of cell wasπ*52/mm2. The open circuit voltage at 800℃was 0.94V; the maximum power density is 152mW/cm2 and the maximum current density is 324mA/cm2, the result of which was well fitted with the equation V=Eoc- iR ohm-(a+blni). It indicated that the cell voltage is mainly consisted of voltage drop of ohm resistances and electrochemical reaction activation energy.
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