【作者】 曲丽娜；

【导师】 刘毅；

【作者基本信息】 贵州大学 ， 材料学， 2009， 硕士

【摘要】 固体氧化物燃料电池（简称SOFC）被称为第四代燃料电池,是目前国际公认具有发电效率高,能量密度大;燃料使用面广,余热利用价值高的燃料电池。但是,SOFC在高温下（800—1000℃）运行会带来一系列的问题,如电池封接困难、寿命短、造价高等,极大的限制了SOFC的推广和使用。因此,研究工作温度为500—800℃中温固体氧化物燃料电池（ITSOFC）变成为了发展的必然趋势。阴极材料是ITSOFC的重要组成部分,随着使用温度的降低,将导致传统阴极材料的极化电阻增大、电导率降低等一系列问题,电池的性能也会大大降低。因此,寻找新的能在中温（500—800℃）条件下工作的阴极材料对于发展SOFC中温化尤为重要。本论文采用溶胶—凝胶法合成制备了具有层状钙钛矿结构的ITSOFC阴极材料YBa_1-xCa_xCo₂O_5+δ（x=0～0.3）,系统地研究了样品体系的晶体结构、热膨胀性能和电输运性能,Ca²⁺的Ba位掺杂对晶体结构、电输运性能和热膨胀性能的影响,还考察了阴极材料与电解质材料的高温粘附性和它的催化活性。研究发现,所制样品体系在1100℃高温烧结后具有3×1×1型层状钙钛矿结构,属四方晶型,空间群为P₄/mmm。Ca²⁺的Ba位掺杂明显地改变YBa_1-xCa_xCo₂O_5+δ的热膨胀性能,随着X的增大,掺杂样品在200℃—800℃内的热膨胀系数逐渐减小,其中YBa_0.7Ca_0.3Co₂O_5+δ与电解质材料8YSZ的热膨胀系数较为接近,说明它与电解质材料8YSZ有良好的匹配性;YBa_1-xCa_xCx₂O_5+δ（x=0～0.3）体系在高温下具有较高的导电率,YBa_0.7Ca_0.3Co₂O_5+δ在800℃时的导电率较高约为41.33Scm^-1;掺杂样品在中低温下（室温—450℃）的Ln（σT）与1/T近似呈直线关系,其电输运机制符合半导体小极化子模型。另外YBa_0.7Ca_0.3Co₂O_5+δ与8YSZ电解质间的高温粘附性能较好,在820℃左右时,阴极材料与电解质之间的界面电阻很小约为4.86Ω·cm²,说明该阴极材料具有较高的催化活性,有利于ITSOFC的正常工作。更多还原

【Abstract】 As the fourth generation fuel cell,SOFC（Solid Oxide Fuel Cell） has many advantages which are internationally recognized,such as high power efficiency,high energy density,much fuel can be used and high value of waste heat utilization. However,SOFC operating at high temperatures will bring about a series of problems, such as sealing cell difficultly,short life,high cost and so on.These problems limit the popularization and application of SOFC greatly.Therefore,it is the obvious trend to research on solid oxide fuel cell（ITSOFC） which is operating at temperatures of 500—800℃.The cathode material is an important part of ITSOFC.It will lead to increase the polarization resistance and reduce the electrical conductivity of traditional cathode material with lowering of temperature.So,it is very important to search for the new kind of cathode material that can be operated at temperatures of 500—800℃.In this thesis,the cathode material YBa_1-xCa_xCo₂O_5+δ（x=0～0.3） of ITSOFC was synthesized by a sol-gel method.We studied the properties such as the cell parameters, thermal expansion and electrical conductivity of samples（x=0）.Then,we also investigate the high-temperature adhesion between the cathode material,and catalytic activity.The structures of the compounds were investigated by XRD,the result show that all structures of the samples belongs to the 3×1×1 tetragonal structure with space group of P₄/mmm at a temperature of 1100℃.We have studied the thermal expansion of samples（x=0～0.3）,and find that the thermal expansion decreases gradually with increasing of Ca²⁺ content.In the temperature of 800℃,the x=0.3 samples has the smallest liner thermal expansion coefficient,which is similar to 8YSZ’s.All of the samples（x=0～0.3） have good electrical properties,and the samples of YBa_0.7Ca_0.3Co₂O_5+δ have relatively high electrical conductivity in the temperature of 800℃,it is about 41.33Scm^-1.The electrical conductivity of samples was found to obey the small polaron hopping mechanism and increase obviously at temperatures of 15—450℃.In addition,the material of YBa_0.7Ca_0.3Co₂O_5+δ has a good high-temperature adhesion.In the temperature of 820℃,the interfacial resistance is about 4.86Ω·cm²,it show that this cathode material is of better catalytic activity,and is beneficial to normal operation of ITSOFC.更多还原