4种方法制备的阴极材料PrBa_(0.85)Ca_(0.15)Co_2O_(5+δ)性能研究

Study on the performance of cathode material PrBa_(0.85)Ca_(0.15)Co_2O_(5+δ) prepared by four methods

为了研究探讨制备方法对阴极材料PrBa_(0.85)Ca_(0.15)Co_2O_(5+δ)(PBCC)的物理和电化学性能的影响,以Pr(NO_3)_3·6H_2O,Ba(NO_3)_2,Ca(NO_3)_2·4H_2O,Co(NO_3)_2·6H_2O为原料,分别采用溶胶-凝胶法、共沉淀法、甘氨酸-硝酸盐法和EDTA-甘氨酸法制备出可用来作中温固体氧化物燃料电池阴极材料PBCC,处理好后对样品性能进行表征.经热重-差热(TG-DTA)分析可知,为保证4种方法制备出稳定的双钙钛矿复合材料,对胶体及沉淀物的焙烧温度在1 000℃. XRD测试显示:制备的PBCC阴极材料经处理后,没有杂质相出现,均形成了四方型的双钙钛矿相.扫描电镜(SEM)的微观结构说明:溶胶-凝胶法制得材料的粒径最小且颗粒形状分布最规整,烧结性能好,有利于提高化学性能.电导率的测定结果说明:在空气气氛下,温度范围在400～800℃的测试条件下,溶胶-凝胶法制备PBCC的电导率高于其它3种方法,其中800℃时最高达到928 S/cm,最低是400℃时的431 S/cm,共沉淀法的电导率最低为250 S/cm,满足不低于100 S/cm的要求.阴极材料由共沉淀法制备的热膨胀系数最低为19. 3×10-6K-1,溶胶-凝胶法低于其它2种方法,鉴于溶胶-凝胶法制备PBCC的优良电化学性能,相对高些的TEC,可以通过与SDC复合制备出所需要的IT-SOFC阴极材料.

The PrBa 0.85 Ca 0.15 Co 2O 5+δ(PBCC) cathode materials of solid oxide fuel cell in intermediate temperature were prepared by sol-gel method,coprecipitation method,glycine-nitrate method and EDTA-glycine method,the raw materials of which are Pr(NO 3) 3·6H 2O,Ba(NO 3) 2,Ca(NO 3) 2·4H 2O,Co(NO 3) 2·6H 2O,Cu(NO 3) 2·4H 2O,in order to study its preparation methods. The influence of the physical and electrochemical performance of the sample were characterized. According to thermogravimetric (TG),differential thermal analysis (TG-DTA),the colloid and sediment of the roasting temperatures were kept at 1 000 ℃ for ensuring the stability of the cathode materials with double perovskite composite prepared by the four methods.XRD test showed that the prepared PBCC cathode material had no impurity phase after being treated,and all formed quadrate double perovskite phase.The microstructure of scanning electron microscopy (SEM) showed that the sol-gel method had the smallest particle size and the most regular particle shape distribution,and had good sintering performance,which was beneficial to the improvement of chemical properties. Conductivity measurement results show that under the test condition of air atmosphere and temperature range of 400~800 ℃,PBCC conductivity by the sol-gel method is higher than those by other three methods,reaching up to 928 S/cm in 800 ℃,while its minimum conductivity is 431 S/cm in 400 ℃.The minimum electrical conductivity by coprecipitation method is 250 S/cm,satisfying the requirement of not less than 100 S/cm.The minimum thermal expansion coefficient of cathode materials prepared by co-precipitation method is 19.3× 10 ^-6 K ^-1 ,and the thermal expansion coefficient of sol-gel method is lower than those of the other two methods. In view of the excellent electrochemical properties and relatively high TEC of PBCC prepared by sol-gel method,combined with SDC,the required IT-SOFC cathode materials can be prepared.